Higher-Order Theory for Functionally Graded Materials

NASA Technical Reports Server (NTRS)

Aboudi, Jacob; Pindera, Marek-Jerzy; Arnold, Steven M.

1999-01-01

This paper presents the full generalization of the Cartesian coordinate-based higher-order theory for functionally graded materials developed by the authors during the past several years. This theory circumvents the problematic use of the standard micromechanical approach, based on the concept of a representative volume element, commonly employed in the analysis of functionally graded composites by explicitly coupling the local (microstructural) and global (macrostructural) responses. The theoretical framework is based on volumetric averaging of the various field quantities, together with imposition of boundary and interfacial conditions in an average sense between the subvolumes used to characterize the composite's functionally graded microstructure. The generalization outlined herein involves extension of the theoretical framework to enable the analysis of materials characterized by spatially variable microstructures in three directions. Specialization of the generalized theoretical framework to previously published versions of the higher-order theory for materials functionally graded in one and two directions is demonstrated. In the applications part of the paper we summarize the major findings obtained with the one-directional and two-directional versions of the higher-order theory. The results illustrate both the fundamental issues related to the influence of microstructure on microscopic and macroscopic quantities governing the response of composites and the technologically important applications. A major issue addressed herein is the applicability of the classical homogenization schemes in the analysis of functionally graded materials. The technologically important applications illustrate the utility of functionally graded microstructures in tailoring the response of structural components in a variety of applications involving uniform and gradient thermomechanical loading.

Schema Theories as a Base for the Structural Representation of the Knowledge State.

ERIC Educational Resources Information Center

Dochy, F. J. R. C.; Bouwens, M. R. J.

From the view of schema-transfer theory, the use of schemata with their several functions gives an explanation for the facilitative effect of prior knowledge on learning processes. This report gives a theoretical exploration of the concept of schemata, underlying schema theories, and functions of schemata to indicate the importance of schema…

The Development of the Functional Literacy Experience Scale Based upon Ecological Theory (FLESBUET) and Validity-Reliability Study

ERIC Educational Resources Information Center

Özenç, Emine Gül; Dogan, M. Cihangir

2014-01-01

This study aims to perform a validity-reliability test by developing the Functional Literacy Experience Scale based upon Ecological Theory (FLESBUET) for primary education students. The study group includes 209 fifth grade students at Sabri Taskin Primary School in the Kartal District of Istanbul, Turkey during the 2010-2011 academic year.…

On the calculation of charge transfer transitions with standard density functionals using constrained variational density functional theory.

PubMed

Ziegler, Tom; Krykunov, Mykhaylo

2010-08-21

It is well known that time-dependent density functional theory (TD-DFT) based on standard gradient corrected functionals affords both a quantitative and qualitative incorrect picture of charge transfer transitions between two spatially separated regions. It is shown here that the well known failure can be traced back to the use of linear response theory. Further, it is demonstrated that the inclusion of higher order terms readily affords a qualitatively correct picture even for simple functionals based on the local density approximation. The inclusion of these terms is done within the framework of a newly developed variational approach to excitation energies called constrained variational density functional theory (CV-DFT). To second order [CV(2)-DFT] this theory is identical to adiabatic TD-DFT within the Tamm-Dancoff approximation. With inclusion of fourth order corrections [CV(4)-DFT] it affords a qualitative correct description of charge transfer transitions. It is finally demonstrated that the relaxation of the ground state Kohn-Sham orbitals to first order in response to the change in density on excitation together with CV(4)-DFT affords charge transfer excitations in good agreement with experiment. The new relaxed theory is termed R-CV(4)-DFT. The relaxed scheme represents an effective way in which to introduce double replacements into the description of single electron excitations, something that would otherwise require a frequency dependent kernel.

Non-empirical exchange-correlation parameterizations based on exact conditions from correlated orbital theory.

PubMed

Haiduke, Roberto Luiz A; Bartlett, Rodney J

2018-05-14

Some of the exact conditions provided by the correlated orbital theory are employed to propose new non-empirical parameterizations for exchange-correlation functionals from Density Functional Theory (DFT). This reparameterization process is based on range-separated functionals with 100% exact exchange for long-range interelectronic interactions. The functionals developed here, CAM-QTP-02 and LC-QTP, show mitigated self-interaction error, correctly predict vertical ionization potentials as the negative of eigenvalues for occupied orbitals, and provide nice excitation energies, even for challenging charge-transfer excited states. Moreover, some improvements are observed for reaction barrier heights with respect to the other functionals belonging to the quantum theory project (QTP) family. Finally, the most important achievement of these new functionals is an excellent description of vertical electron affinities (EAs) of atoms and molecules as the negative of appropriate virtual orbital eigenvalues. In this case, the mean absolute deviations for EAs in molecules are smaller than 0.10 eV, showing that physical interpretation can indeed be ascribed to some unoccupied orbitals from DFT.

Non-empirical exchange-correlation parameterizations based on exact conditions from correlated orbital theory

NASA Astrophysics Data System (ADS)

Haiduke, Roberto Luiz A.; Bartlett, Rodney J.

2018-05-01

Some of the exact conditions provided by the correlated orbital theory are employed to propose new non-empirical parameterizations for exchange-correlation functionals from Density Functional Theory (DFT). This reparameterization process is based on range-separated functionals with 100% exact exchange for long-range interelectronic interactions. The functionals developed here, CAM-QTP-02 and LC-QTP, show mitigated self-interaction error, correctly predict vertical ionization potentials as the negative of eigenvalues for occupied orbitals, and provide nice excitation energies, even for challenging charge-transfer excited states. Moreover, some improvements are observed for reaction barrier heights with respect to the other functionals belonging to the quantum theory project (QTP) family. Finally, the most important achievement of these new functionals is an excellent description of vertical electron affinities (EAs) of atoms and molecules as the negative of appropriate virtual orbital eigenvalues. In this case, the mean absolute deviations for EAs in molecules are smaller than 0.10 eV, showing that physical interpretation can indeed be ascribed to some unoccupied orbitals from DFT.

Features analysis of five-element theory and its basal effects on construction of visceral manifestation theory.

PubMed

Ma, Zimi; Jia, Chunhua; Guo, Jin; Gu, Haorong; Miao, Yanhuan

2014-02-01

To study the Chinese ancient five-element theory, one of the philosophical foundations of Traditional Chinese Medicine (TCM) theory construction, from the perspective of comtemporary cognitive science, and to reveal the important functions of five-element theory in the construction of TCM theory. The basic effects of five-element theory in the construction of TCM theory are intensively expounded and proved from the following aspects: embodiment of five-element theory in cognizing the world, quasi axiom of five-element theory in essence, classification thery of family resemblance and deductive inference pattern of five-element theory, and the openness and expansibility of five-element theory. If five-element theory is considered a cognitive pattern or cognitive system related to culture, then there should be features of cognitive embodiment in the cognitive system. If five-element theory is regarded as a symbolic system, however, then there should be a quasi-axiom for the system, and inferential deduction. If, however, five-element theory is taken as a theoretical constructive metaphor, then there should be features of opening and expansibility for the metaphor. Based on five-element theory, this study provides a cognitive frame for the construction of TCM (a medicine that originated in China, and is characterized by holism and treatment based on pattern identification differentiation) theory with the function of constructing a concept base, thereby implying further research strategies. Useful information may be produced from the creative inferences obtained from the incorporation of five-element theory.

Effective model hierarchies for dynamic and static classical density functional theories

NASA Astrophysics Data System (ADS)

Majaniemi, S.; Provatas, N.; Nonomura, M.

2010-09-01

The origin and methodology of deriving effective model hierarchies are presented with applications to solidification of crystalline solids. In particular, it is discussed how the form of the equations of motion and the effective parameters on larger scales can be obtained from the more microscopic models. It will be shown that tying together the dynamic structure of the projection operator formalism with static classical density functional theories can lead to incomplete (mass) transport properties even though the linearized hydrodynamics on large scales is correctly reproduced. To facilitate a more natural way of binding together the dynamics of the macrovariables and classical density functional theory, a dynamic generalization of density functional theory based on the nonequilibrium generating functional is suggested.

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.

Excitation energies from Görling-Levy perturbation theory along the range-separated adiabatic connection

NASA Astrophysics Data System (ADS)

Rebolini, Elisa; Teale, Andrew M.; Helgaker, Trygve; Savin, Andreas; Toulouse, Julien

2018-06-01

A Görling-Levy (GL)-based perturbation theory along the range-separated adiabatic connection is assessed for the calculation of electronic excitation energies. In comparison with the Rayleigh-Schrödinger (RS)-based perturbation theory this GL-based perturbation theory keeps the ground-state density constant at each order and thus gives the correct ionisation energy at each order. Excitation energies up to first order in the perturbation have been calculated numerically for the helium and beryllium atoms and the hydrogen molecule without introducing any density-functional approximations. In comparison with the RS-based perturbation theory, the present GL-based perturbation theory gives much more accurate excitation energies for Rydberg states but similar excitation energies for valence states.

Tight-binding approximations to time-dependent density functional theory — A fast approach for the calculation of electronically excited states

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rüger, Robert, E-mail: rueger@scm.com; Department of Theoretical Chemistry, Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam; Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Linnéstr. 2, 04103 Leipzig

2016-05-14

We propose a new method of calculating electronically excited states that combines a density functional theory based ground state calculation with a linear response treatment that employs approximations used in the time-dependent density functional based tight binding (TD-DFTB) approach. The new method termed time-dependent density functional theory TD-DFT+TB does not rely on the DFTB parametrization and is therefore applicable to systems involving all combinations of elements. We show that the new method yields UV/Vis absorption spectra that are in excellent agreement with computationally much more expensive TD-DFT calculations. Errors in vertical excitation energies are reduced by a factor of twomore » compared to TD-DFTB.« less

Generalization of the Kohn-Sham system that can represent arbitrary one-electron density matrices

DOE PAGES

Hubertus J. J. van Dam

2016-04-27

Density functional theory is currently the most widely applied method in electronic structure theory. The Kohn-Sham method, based on a fictitious system of noninteracting particles, is the workhorse of the theory. The particular form of the Kohn-Sham wave function admits only idempotent one-electron density matrices whereas wave functions of correlated electrons in post-Hartree-Fock methods invariably have fractional occupation numbers. Here we show that by generalizing the orbital concept and introducing a suitable dot product as well as a probability density, a noninteracting system can be chosen that can represent the one-electron density matrix of any system, even one with fractionalmore » occupation numbers. This fictitious system ensures that the exact electron density is accessible within density functional theory. It can also serve as the basis for reduced density matrix functional theory. Moreover, to aid the analysis of the results the orbitals may be assigned energies from a mean-field Hamiltonian. This produces energy levels that are akin to Hartree-Fock orbital energies such that conventional analyses based on Koopmans' theorem are available. Lastly, this system is convenient in formalisms that depend on creation and annihilation operators as they are trivially applied to single-determinant wave functions.« less

A new theory of gravity

NASA Technical Reports Server (NTRS)

Ni, W.

1972-01-01

A new relativistic theory of gravity is presented. This theory agrees with all experiments to date. It is a metric theory, it is Lagrangian-based, and it possesses a preferred frame with conformally-flat space slices. With an appropriate choice of certain adjustable functions and parameters, this theory possesses precisely the same post-Newtonian limit as general relativity.

Nonequilibrium Green's function theory for nonadiabatic effects in quantum electron transport

NASA Astrophysics Data System (ADS)

Kershaw, Vincent F.; Kosov, Daniel S.

2017-12-01

We develop nonequilibrium Green's function-based transport theory, which includes effects of nonadiabatic nuclear motion in the calculation of the electric current in molecular junctions. Our approach is based on the separation of slow and fast time scales in the equations of motion for Green's functions by means of the Wigner representation. Time derivatives with respect to central time serve as a small parameter in the perturbative expansion enabling the computation of nonadiabatic corrections to molecular Green's functions. Consequently, we produce a series of analytic expressions for non-adiabatic electronic Green's functions (up to the second order in the central time derivatives), which depend not solely on the instantaneous molecular geometry but likewise on nuclear velocities and accelerations. An extended formula for electric current is derived which accounts for the non-adiabatic corrections. This theory is concisely illustrated by the calculations on a model molecular junction.

Nonequilibrium Green's function theory for nonadiabatic effects in quantum electron transport.

PubMed

Kershaw, Vincent F; Kosov, Daniel S

2017-12-14

We develop nonequilibrium Green's function-based transport theory, which includes effects of nonadiabatic nuclear motion in the calculation of the electric current in molecular junctions. Our approach is based on the separation of slow and fast time scales in the equations of motion for Green's functions by means of the Wigner representation. Time derivatives with respect to central time serve as a small parameter in the perturbative expansion enabling the computation of nonadiabatic corrections to molecular Green's functions. Consequently, we produce a series of analytic expressions for non-adiabatic electronic Green's functions (up to the second order in the central time derivatives), which depend not solely on the instantaneous molecular geometry but likewise on nuclear velocities and accelerations. An extended formula for electric current is derived which accounts for the non-adiabatic corrections. This theory is concisely illustrated by the calculations on a model molecular junction.

Derivation of Hunt equation for suspension distribution using Shannon entropy theory

NASA Astrophysics Data System (ADS)

Kundu, Snehasis

2017-12-01

In this study, the Hunt equation for computing suspension concentration in sediment-laden flows is derived using Shannon entropy theory. Considering the inverse of the void ratio as a random variable and using principle of maximum entropy, probability density function and cumulative distribution function of suspension concentration is derived. A new and more general cumulative distribution function for the flow domain is proposed which includes several specific other models of CDF reported in literature. This general form of cumulative distribution function also helps to derive the Rouse equation. The entropy based approach helps to estimate model parameters using suspension data of sediment concentration which shows the advantage of using entropy theory. Finally model parameters in the entropy based model are also expressed as functions of the Rouse number to establish a link between the parameters of the deterministic and probabilistic approaches.

Extending density functional embedding theory for covalently bonded systems.

PubMed

Yu, Kuang; Carter, Emily A

2017-12-19

Quantum embedding theory aims to provide an efficient solution to obtain accurate electronic energies for systems too large for full-scale, high-level quantum calculations. It adopts a hierarchical approach that divides the total system into a small embedded region and a larger environment, using different levels of theory to describe each part. Previously, we developed a density-based quantum embedding theory called density functional embedding theory (DFET), which achieved considerable success in metals and semiconductors. In this work, we extend DFET into a density-matrix-based nonlocal form, enabling DFET to study the stronger quantum couplings between covalently bonded subsystems. We name this theory density-matrix functional embedding theory (DMFET), and we demonstrate its performance in several test examples that resemble various real applications in both chemistry and biochemistry. DMFET gives excellent results in all cases tested thus far, including predicting isomerization energies, proton transfer energies, and highest occupied molecular orbital-lowest unoccupied molecular orbital gaps for local chromophores. Here, we show that DMFET systematically improves the quality of the results compared with the widely used state-of-the-art methods, such as the simple capped cluster model or the widely used ONIOM method.

Decomposition Theory in the Teaching of Elementary Linear Algebra.

ERIC Educational Resources Information Center

London, R. R.; Rogosinski, H. P.

1990-01-01

Described is a decomposition theory from which the Cayley-Hamilton theorem, the diagonalizability of complex square matrices, and functional calculus can be developed. The theory and its applications are based on elementary polynomial algebra. (KR)

Local density approximation in site-occupation embedding theory

NASA Astrophysics Data System (ADS)

Senjean, Bruno; Tsuchiizu, Masahisa; Robert, Vincent; Fromager, Emmanuel

2017-01-01

Site-occupation embedding theory (SOET) is a density functional theory (DFT)-based method which aims at modelling strongly correlated electrons. It is in principle exact and applicable to model and quantum chemical Hamiltonians. The theory is presented here for the Hubbard Hamiltonian. In contrast to conventional DFT approaches, the site (or orbital) occupations are deduced in SOET from a partially interacting system consisting of one (or more) impurity site(s) and non-interacting bath sites. The correlation energy of the bath is then treated implicitly by means of a site-occupation functional. In this work, we propose a simple impurity-occupation functional approximation based on the two-level (2L) Hubbard model which is referred to as two-level impurity local density approximation (2L-ILDA). Results obtained on a prototypical uniform eight-site Hubbard ring are promising. The extension of the method to larger systems and more sophisticated model Hamiltonians is currently in progress.

Excited-state absorption in tetrapyridyl porphyrins: comparing real-time and quadratic-response time-dependent density functional theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bowman, David N.; Asher, Jason C.; Fischer, Sean A.

2017-01-01

Threemeso-substituted tetrapyridyl porphyrins (free base, Ni(ii), and Cu(ii)) were investigated for their optical limiting (OL) capabilities using real-time (RT-), linear-response (LR-), and quadratic-response (QR-) time-dependent density functional theory (TDDFT) methods.

Combining Density Functional Theory and Green's Function Theory: Range-Separated, Nonlocal, Dynamic, and Orbital-Dependent Hybrid Functional.

PubMed

Kananenka, Alexei A; Zgid, Dominika

2017-11-14

We present a rigorous framework which combines single-particle Green's function theory with density functional theory based on a separation of electron-electron interactions into short- and long-range components. Short-range contribution to the total energy and exchange-correlation potential is provided by a density functional approximation, while the long-range contribution is calculated using an explicit many-body Green's function method. Such a hybrid results in a nonlocal, dynamic, and orbital-dependent exchange-correlation functional of a single-particle Green's function. In particular, we present a range-separated hybrid functional called srSVWN5-lrGF2 which combines the local-density approximation and the second-order Green's function theory. We illustrate that similarly to density functional approximations, the new functional is weakly basis-set dependent. Furthermore, it offers an improved description of the short-range dynamic correlation. The many-body contribution to the functional mitigates the many-electron self-interaction error present in many density functional approximations and provides a better description of molecular properties. Additionally, we illustrate that the new functional can be used to scale down the self-energy and, therefore, introduce an additional sparsity to the self-energy matrix that in the future can be exploited in calculations for large molecules or periodic systems.

Two-body perturbation theory versus first order perturbation theory: A comparison based on the square-well fluid.

PubMed

Mercier Franco, Luís Fernando; Castier, Marcelo; Economou, Ioannis G

2017-12-07

We show that the Zwanzig first-order perturbation theory can be obtained directly from a truncated Taylor series expansion of a two-body perturbation theory and that such truncation provides a more accurate prediction of thermodynamic properties than the full two-body perturbation theory. This unexpected result is explained by the quality of the resulting approximation for the fluid radial distribution function. We prove that the first-order and the two-body perturbation theories are based on different approximations for the fluid radial distribution function. To illustrate the calculations, the square-well fluid is adopted. We develop an analytical expression for the two-body perturbed Helmholtz free energy for the square-well fluid. The equation of state obtained using such an expression is compared to the equation of state obtained from the first-order approximation. The vapor-liquid coexistence curve and the supercritical compressibility factor of a square-well fluid are calculated using both equations of state and compared to Monte Carlo simulation data. Finally, we show that the approximation for the fluid radial distribution function given by the first-order perturbation theory provides closer values to the ones calculated via Monte Carlo simulations. This explains why such theory gives a better description of the fluid thermodynamic behavior.

COGNITIVE AND MOTIVATIONAL FACTORS IN AGING AND DISENGAGEMENT.

ERIC Educational Resources Information Center

BACK, KURT W.; GERGEN, KENNETH J.

PREVIOUS THEORIES OF THE AGING PROCESS HAVE DERIVED BEHAVIOR AS NECESSARY FUNCTIONS OF SOCIAL OR INDIVIDUAL VARIABLES. AN INTERMEDIATE THEORY, PERSONAL ORIENTATION, ALLOWS THE INDIVIDUAL THE POSSIBILITY OF CHOICE WITHIN HIS CAPACITIES AND SOCIAL SITUATION. THIS THEORY IS BASED ON A DISENGAGEMENT THEORY OF AGING THAT SUGGESTS THAT A PERSON…

Extension of many-body theory and approximate density functionals to fractional charges and fractional spins.

PubMed

Yang, Weitao; Mori-Sánchez, Paula; Cohen, Aron J

2013-09-14

The exact conditions for density functionals and density matrix functionals in terms of fractional charges and fractional spins are known, and their violation in commonly used functionals has been shown to be the root of many major failures in practical applications. However, approximate functionals are designed for physical systems with integer charges and spins, not in terms of the fractional variables. Here we develop a general framework for extending approximate density functionals and many-electron theory to fractional-charge and fractional-spin systems. Our development allows for the fractional extension of any approximate theory that is a functional of G(0), the one-electron Green's function of the non-interacting reference system. The extension to fractional charge and fractional spin systems is based on the ensemble average of the basic variable, G(0). We demonstrate the fractional extension for the following theories: (1) any explicit functional of the one-electron density, such as the local density approximation and generalized gradient approximations; (2) any explicit functional of the one-electron density matrix of the non-interacting reference system, such as the exact exchange functional (or Hartree-Fock theory) and hybrid functionals; (3) many-body perturbation theory; and (4) random-phase approximations. A general rule for such an extension has also been derived through scaling the orbitals and should be useful for functionals where the link to the Green's function is not obvious. The development thus enables the examination of approximate theories against known exact conditions on the fractional variables and the analysis of their failures in chemical and physical applications in terms of violations of exact conditions of the energy functionals. The present work should facilitate the calculation of chemical potentials and fundamental bandgaps with approximate functionals and many-electron theories through the energy derivatives with respect to the fractional charge. It should play an important role in developing accurate approximate density functionals and many-body theory.

Neo-classical theory of competition or Adam Smith's hand as mathematized ideology

NASA Astrophysics Data System (ADS)

McCauley, Joseph L.

2001-10-01

Orthodox economic theory (utility maximization, rational agents, efficient markets in equilibrium) is based on arbitrarily postulated, nonempiric notions. The disagreement between economic reality and a key feature of neo-classical economic theory was criticized empirically by Osborne. I show that the orthodox theory is internally self-inconsistent for the very reason suggested by Osborne: lack of invertibility of demand and supply as functions of price to obtain price as functions of supply and demand. The reason for the noninvertibililty arises from nonintegrable excess demand dynamics, a feature of their theory completely ignored by economists.

Density functional theory for polymeric systems in 2D.

PubMed

Słyk, Edyta; Roth, Roland; Bryk, Paweł

2016-06-22

We propose density functional theory for polymeric fluids in two dimensions. The approach is based on Wertheim's first order thermodynamic perturbation theory (TPT) and closely follows density functional theory for polymers proposed by Yu and Wu (2002 J. Chem. Phys. 117 2368). As a simple application we evaluate the density profiles of tangent hard-disk polymers at hard walls. The theoretical predictions are compared against the results of the Monte Carlo simulations. We find that for short chain lengths the theoretical density profiles are in an excellent agreement with the Monte Carlo data. The agreement is less satisfactory for longer chains. The performance of the theory can be improved by recasting the approach using the self-consistent field theory formalism. When the self-avoiding chain statistics is used, the theory yields a marked improvement in the low density limit. Further improvements for long chains could be reached by going beyond the first order of TPT.

Toward a revised evolutionary adaptationist analysis of depression: the social navigation hypothesis.

PubMed

Watson, Paul J; Andrews, Paul W

2002-10-01

Evolutionary biologists use Darwinian theory and functional design ("reverse engineering") analyses, to develop and test hypotheses about the adaptive functions of traits. Based upon a consideration of human social life and a functional design analysis of depression's core symptomatology we offer a comprehensive theory of its adaptive significance called the Social Navigation Hypothesis (SNH). The SNH attempts to account for all intensities of depression based on standard evolutionary theories of sociality, communication and psychological pain. The SNH suggests that depression evolved to perform two complimentary social problem-solving functions. First, depression induces cognitive changes that focus and enhance capacities for the accurate analysis and solution of key social problems, suggesting a social rumination function. Second, the costs associated with the anhedonia and psychomotor perturbation of depression can persuade reluctant social partners to provide help or make concessions via two possible mechanisms, namely, honest signaling and passive, unintentional fitness extortion. Thus it may also have a social motivation function.

The effect of stimulus strength on the speed and accuracy of a perceptual decision.

PubMed

Palmer, John; Huk, Alexander C; Shadlen, Michael N

2005-05-02

Both the speed and the accuracy of a perceptual judgment depend on the strength of the sensory stimulation. When stimulus strength is high, accuracy is high and response time is fast; when stimulus strength is low, accuracy is low and response time is slow. Although the psychometric function is well established as a tool for analyzing the relationship between accuracy and stimulus strength, the corresponding chronometric function for the relationship between response time and stimulus strength has not received as much consideration. In this article, we describe a theory of perceptual decision making based on a diffusion model. In it, a decision is based on the additive accumulation of sensory evidence over time to a bound. Combined with simple scaling assumptions, the proportional-rate and power-rate diffusion models predict simple analytic expressions for both the chronometric and psychometric functions. In a series of psychophysical experiments, we show that this theory accounts for response time and accuracy as a function of both stimulus strength and speed-accuracy instructions. In particular, the results demonstrate a close coupling between response time and accuracy. The theory is also shown to subsume the predictions of Piéron's Law, a power function dependence of response time on stimulus strength. The theory's analytic chronometric function allows one to extend theories of accuracy to response time.

Where are family theories in family-based obesity treatment?: conceptualizing the study of families in pediatric weight management

PubMed Central

Skelton, JA; Buehler, C; Irby, MB; Grzywacz, JG

2014-01-01

Family-based approaches to pediatric obesity treatment are considered the ‘gold-standard,’ and are recommended for facilitating behavior change to improve child weight status and health. If family-based approaches are to be truly rooted in the family, clinicians and researchers must consider family process and function in designing effective interventions. To bring a better understanding of family complexities to family-based treatment, two relevant reviews were conducted and are presented: (1) a review of prominent and established theories of the family that may provide a more comprehensive and in-depth approach for addressing pediatric obesity; and (2) a systematic review of the literature to identify the use of prominent family theories in pediatric obesity research, which found little use of theories in intervention studies. Overlapping concepts across theories include: families are a system, with interdependence of units; the idea that families are goal-directed and seek balance; and the physical and social environment imposes demands on families. Family-focused theories provide valuable insight into the complexities of families. Increased use of these theories in both research and practice may identify key leverage points in family process and function to prevent the development of or more effectively treat obesity. The field of family studies provides an innovative approach to the difficult problem of pediatric obesity, building on the long-established approach of family-based treatment. PMID:22531090

Implementation and benchmark of a long-range corrected functional in the density functional based tight-binding method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lutsker, V.; Niehaus, T. A., E-mail: thomas.niehaus@physik.uni-regensburg.de; Aradi, B.

2015-11-14

Bridging the gap between first principles methods and empirical schemes, the density functional based tight-binding method (DFTB) has become a versatile tool in predictive atomistic simulations over the past years. One of the major restrictions of this method is the limitation to local or gradient corrected exchange-correlation functionals. This excludes the important class of hybrid or long-range corrected functionals, which are advantageous in thermochemistry, as well as in the computation of vibrational, photoelectron, and optical spectra. The present work provides a detailed account of the implementation of DFTB for a long-range corrected functional in generalized Kohn-Sham theory. We apply themore » method to a set of organic molecules and compare ionization potentials and electron affinities with the original DFTB method and higher level theory. The new scheme cures the significant overpolarization in electric fields found for local DFTB, which parallels the functional dependence in first principles density functional theory (DFT). At the same time, the computational savings with respect to full DFT calculations are not compromised as evidenced by numerical benchmark data.« less

Electron transport in polycyclic aromatic hydrocarbons/boron nitride hybrid structures: density functional theory combined with the nonequilibrium Green's function.

PubMed

Panahi, S F K S; Namiranian, Afshin; Soleimani, Maryam; Jamaati, Maryam

2018-02-07

We investigate the electronic transport properties of two types of junction based on single polyaromatic hydrocarbons (PAHs) and PAHs embedded in boron nitride (h-BN) nanoribbons, using nonequilibrium Green's functions (NEGF) and density functional theory (DFT). In the PAH junctions, a Fano resonance line shape at the Fermi energy in the transport feature can be clearly seen. In hybrid junctions, structural asymmetries enable interactions between the electronic states, leading to observation of interface-based transport. Our findings reveal that the interface of PAH/h-BN strongly affects the transport properties of the structures.

A new theory of gravity.

NASA Technical Reports Server (NTRS)

Ni, W.-T.

1973-01-01

A new relativistic theory of gravity is presented. This theory agrees with all experiments to date. It is a metric theory; it is Lagrangian-based; and it possesses a preferred frame with conformally flat space slices. With an appropriate choice of certain adjustable functions and parameters and of the cosmological model, this theory possesses precisely the same post-Newtonian limit as general relativity.

Postbuckling response of long thick plates loaded in compression including higher order transverse shearing effects

NASA Technical Reports Server (NTRS)

Stein, Manuel; Sydow, P. Daniel; Librescu, Liviu

1990-01-01

Buckling and postbuckling results are presented for compression-loaded simply-supported aluminum plates and composite plates with a symmetric lay-up of thin + or - 45 deg plies composed of many layers. Buckling results for aluminum plates of finite length are given for various length-to-width ratios. Asymptotes to the curves based on buckling results give N(sub xcr) for plates of infinite length. Postbuckling results for plates with transverse shearing flexibility are compared to results from classical theory for various width-to-thickness ratios. Characteristic curves indicating the average longitudinal direct stress resultant as a function of the applied displacements are calculated based on four different theories: Classical von Karman theory using the Kirchoff assumptions, first-order shear deformation theory, higher-order shear deformation theory, and 3-D flexibility theory. Present results indicate that the 3-D flexibility theory gives the lowest buckling loads. The higher-order shear deformation theory has fewer unknowns than the 3-D flexibility theory but does not take into account through-the-thickness effects. The figures presented show that small differences occur in the average longitudinal direct stress resultants from the four theories that are functions of applied end-shortening displacement.

The metric on field space, functional renormalization, and metric–torsion quantum gravity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reuter, Martin, E-mail: reuter@thep.physik.uni-mainz.de; Schollmeyer, Gregor M., E-mail: schollmeyer@thep.physik.uni-mainz.de

Searching for new non-perturbatively renormalizable quantum gravity theories, functional renormalization group (RG) flows are studied on a theory space of action functionals depending on the metric and the torsion tensor, the latter parameterized by three irreducible component fields. A detailed comparison with Quantum Einstein–Cartan Gravity (QECG), Quantum Einstein Gravity (QEG), and “tetrad-only” gravity, all based on different theory spaces, is performed. It is demonstrated that, over a generic theory space, the construction of a functional RG equation (FRGE) for the effective average action requires the specification of a metric on the infinite-dimensional field manifold as an additional input. A modifiedmore » FRGE is obtained if this metric is scale-dependent, as it happens in the metric–torsion system considered.« less

Functional neural networks of honesty and dishonesty in children: Evidence from graph theory analysis.

PubMed

Ding, Xiao Pan; Wu, Si Jia; Liu, Jiangang; Fu, Genyue; Lee, Kang

2017-09-21

The present study examined how different brain regions interact with each other during spontaneous honest vs. dishonest communication. More specifically, we took a complex network approach based on the graph-theory to analyze neural response data when children are spontaneously engaged in honest or dishonest acts. Fifty-nine right-handed children between 7 and 12 years of age participated in the study. They lied or told the truth out of their own volition. We found that lying decreased both the global and local efficiencies of children's functional neural network. This finding, for the first time, suggests that lying disrupts the efficiency of children's cortical network functioning. Further, it suggests that the graph theory based network analysis is a viable approach to study the neural development of deception.

Theoretical Developments in Decision Field Theory: Comment on Tsetsos, Usher, and Chater (2010)

ERIC Educational Resources Information Center

Hotaling, Jared M.; Busemeyer, Jerome R.; Li, Jiyun

2010-01-01

Tsetsos, Usher, and Chater (2010) presented several criticisms of decision field theory (DFT) involving its distance function, instability under externally controlled stopping times, and lack of robustness to various multialternative choice scenarios. Here, we counter those claims with a specification of a distance function based on the…

Massively parallel sparse matrix function calculations with NTPoly

NASA Astrophysics Data System (ADS)

Dawson, William; Nakajima, Takahito

2018-04-01

We present NTPoly, a massively parallel library for computing the functions of sparse, symmetric matrices. The theory of matrix functions is a well developed framework with a wide range of applications including differential equations, graph theory, and electronic structure calculations. One particularly important application area is diagonalization free methods in quantum chemistry. When the input and output of the matrix function are sparse, methods based on polynomial expansions can be used to compute matrix functions in linear time. We present a library based on these methods that can compute a variety of matrix functions. Distributed memory parallelization is based on a communication avoiding sparse matrix multiplication algorithm. OpenMP task parallellization is utilized to implement hybrid parallelization. We describe NTPoly's interface and show how it can be integrated with programs written in many different programming languages. We demonstrate the merits of NTPoly by performing large scale calculations on the K computer.

The ordering of symmetric diblock copolymers: A comparison of self-consistent-field and density functional approaches

NASA Astrophysics Data System (ADS)

Nath, Shyamal K.; McCoy, John D.; Curro, John G.; Saunders, Randall S.

1997-02-01

Polymer reference interaction site model (PRISM) based density functional (DF) theory is used to evaluate the structure and thermodynamics of structurally symmetric, freely jointed, diblock chains with 0.50 volume fraction. These results are compared to the results of self-consistent-field (SCF) theory. Agreement between the predictions of the SCF and DF theories is found for the lamella spacing well above the order-disorder transition (ODT) and for the qualitative behavior of the interfacial thickness as a function of both chain length and Flory-Huggins χ parameter. Disagreement is found for the magnitude of the interfacial thickness where DF theory indicates that the thickness is 1.7±0.2 times larger than that predicted by SCF theory. It appears that behavior on the monomer length scale is sensitive to system specific details which are neglected by SCF theory.

Re-evaluating concepts of biological function in clinical medicine: towards a new naturalistic theory of disease.

PubMed

Chin-Yee, Benjamin; Upshur, Ross E G

2017-08-01

Naturalistic theories of disease appeal to concepts of biological function, and use the notion of dysfunction as the basis of their definitions. Debates in the philosophy of biology demonstrate how attributing functions in organisms and establishing the function-dysfunction distinction is by no means straightforward. This problematization of functional ascription has undermined naturalistic theories and led some authors to abandon the concept of dysfunction, favoring instead definitions based in normative criteria or phenomenological approaches. Although this work has enhanced our understanding of disease and illness, we need not necessarily abandon naturalistic concepts of function and dysfunction in the disease debate. This article attempts to move towards a new naturalistic theory of disease that overcomes the limitations of previous definitions and offers advantages in the clinical setting. Our approach involves a re-evaluation of concepts of biological function employed by naturalistic theories. Drawing on recent insights from the philosophy of biology, we develop a contextual and evaluative account of function that is better suited to clinical medicine and remains consistent with contemporary naturalism. We also show how an updated naturalistic view shares important affinities with normativist and phenomenological positions, suggesting a possibility for consilience in the disease debate.

Analytical gradients for subsystem density functional theory within the slater-function-based amsterdam density functional program.

PubMed

Schlüns, Danny; Franchini, Mirko; Götz, Andreas W; Neugebauer, Johannes; Jacob, Christoph R; Visscher, Lucas

2017-02-05

We present a new implementation of analytical gradients for subsystem density-functional theory (sDFT) and frozen-density embedding (FDE) into the Amsterdam Density Functional program (ADF). The underlying theory and necessary expressions for the implementation are derived and discussed in detail for various FDE and sDFT setups. The parallel implementation is numerically verified and geometry optimizations with different functional combinations (LDA/TF and PW91/PW91K) are conducted and compared to reference data. Our results confirm that sDFT-LDA/TF yields good equilibrium distances for the systems studied here (mean absolute deviation: 0.09 Å) compared to reference wave-function theory results. However, sDFT-PW91/PW91k quite consistently yields smaller equilibrium distances (mean absolute deviation: 0.23 Å). The flexibility of our new implementation is demonstrated for an HCN-trimer test system, for which several different setups are applied. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Remarks on a New Possible Discretization Scheme for Gauge Theories

NASA Astrophysics Data System (ADS)

Magnot, Jean-Pierre

2018-03-01

We propose here a new discretization method for a class of continuum gauge theories which action functionals are polynomials of the curvature. Based on the notion of holonomy, this discretization procedure appears gauge-invariant for discretized analogs of Yang-Mills theories, and hence gauge-fixing is fully rigorous for these discretized action functionals. Heuristic parts are forwarded to the quantization procedure via Feynman integrals and the meaning of the heuristic infinite dimensional Lebesgue integral is questioned.

Exact hierarchical clustering in one dimension. [in universe

NASA Technical Reports Server (NTRS)

Williams, B. G.; Heavens, A. F.; Peacock, J. A.; Shandarin, S. F.

1991-01-01

The present adhesion model-based one-dimensional simulations of gravitational clustering have yielded bound-object catalogs applicable in tests of analytical approaches to cosmological structure formation. Attention is given to Press-Schechter (1974) type functions, as well as to their density peak-theory modifications and the two-point correlation function estimated from peak theory. The extent to which individual collapsed-object locations can be predicted by linear theory is significant only for objects of near-characteristic nonlinear mass.

Remarks on a New Possible Discretization Scheme for Gauge Theories

NASA Astrophysics Data System (ADS)

Magnot, Jean-Pierre

2018-07-01

We propose here a new discretization method for a class of continuum gauge theories which action functionals are polynomials of the curvature. Based on the notion of holonomy, this discretization procedure appears gauge-invariant for discretized analogs of Yang-Mills theories, and hence gauge-fixing is fully rigorous for these discretized action functionals. Heuristic parts are forwarded to the quantization procedure via Feynman integrals and the meaning of the heuristic infinite dimensional Lebesgue integral is questioned.

Multireference second order perturbation theory with a simplified treatment of dynamical correlation.

PubMed

Xu, Enhua; Zhao, Dongbo; Li, Shuhua

2015-10-13

A multireference second order perturbation theory based on a complete active space configuration interaction (CASCI) function or density matrix renormalized group (DMRG) function has been proposed. This method may be considered as an approximation to the CAS/A approach with the same reference, in which the dynamical correlation is simplified with blocked correlated second order perturbation theory based on the generalized valence bond (GVB) reference (GVB-BCPT2). This method, denoted as CASCI-BCPT2/GVB or DMRG-BCPT2/GVB, is size consistent and has a similar computational cost as the conventional second order perturbation theory (MP2). We have applied it to investigate a number of problems of chemical interest. These problems include bond-breaking potential energy surfaces in four molecules, the spectroscopic constants of six diatomic molecules, the reaction barrier for the automerization of cyclobutadiene, and the energy difference between the monocyclic and bicyclic forms of 2,6-pyridyne. Our test applications demonstrate that CASCI-BCPT2/GVB can provide comparable results with CASPT2 (second order perturbation theory based on the complete active space self-consistent-field wave function) for systems under study. Furthermore, the DMRG-BCPT2/GVB method is applicable to treat strongly correlated systems with large active spaces, which are beyond the capability of CASPT2.

A distributed parameter electromechanical model for bimorph piezoelectric energy harvesters based on the refined zigzag theory

NASA Astrophysics Data System (ADS)

Chen, Chung-De

2018-04-01

In this paper, a distributed parameter electromechanical model for bimorph piezoelectric energy harvesters based on the refined zigzag theory (RZT) is developed. In this model, the zigzag function is incorporated into the axial displacement, and the zigzag distribution of the displacement between the adjacent layers of the bimorph structure can be considered. The governing equations, including three equations of motions and one equation of circuit, are derived using Hamilton’s principle. The natural frequency, its corresponding modal function and the steady state response of the base excitation motion are given in exact forms. The presented results are benchmarked with the finite element method and two beam theories, the first-order shear deformation theory and the classical beam theory. Comparing examples shows that the RZT provides predictions of output voltage and generated power at high accuracy, especially for the case of a soft middle layer. Variation of the parameters, such as the beam thickness, excitation frequencies and the external electrical loads, is investigated and its effects on the performance of the energy harvesters are studied by using the RZT developed in this paper. Based on this refined theory, analysts and engineers can capture more details on the electromechanical behavior of piezoelectric harvesters.

Topological strings on singular elliptic Calabi-Yau 3-folds and minimal 6d SCFTs

NASA Astrophysics Data System (ADS)

Del Zotto, Michele; Gu, Jie; Huang, Min-xin; Kashani-Poor, Amir-Kian; Klemm, Albrecht; Lockhart, Guglielmo

2018-03-01

We apply the modular approach to computing the topological string partition function on non-compact elliptically fibered Calabi-Yau 3-folds with higher Kodaira singularities in the fiber. The approach consists in making an ansatz for the partition function at given base degree, exact in all fiber classes to arbitrary order and to all genus, in terms of a rational function of weak Jacobi forms. Our results yield, at given base degree, the elliptic genus of the corresponding non-critical 6d string, and thus the associated BPS invariants of the 6d theory. The required elliptic indices are determined from the chiral anomaly 4-form of the 2d worldsheet theories, or the 8-form of the corresponding 6d theories, and completely fix the holomorphic anomaly equation constraining the partition function. We introduce subrings of the known rings of Weyl invariant Jacobi forms which are adapted to the additional symmetries of the partition function, making its computation feasible to low base wrapping number. In contradistinction to the case of simpler singularities, generic vanishing conditions on BPS numbers are no longer sufficient to fix the modular ansatz at arbitrary base wrapping degree. We show that to low degree, imposing exact vanishing conditions does suffice, and conjecture this to be the case generally.

On the classic and modern theories of matching.

PubMed

McDowell, J J

2005-07-01

Classic matching theory, which is based on Herrnstein's (1961) original matching equation and includes the well-known quantitative law of effect, is almost certainly false. The theory is logically inconsistent with known experimental findings, and experiments have shown that its central constant-k assumption is not tenable. Modern matching theory, which is based on the power function version of the original matching equation, remains tenable, although it has not been discussed or studied extensively. The modern theory is logically consistent with known experimental findings, it predicts the fact and details of the violation of the classic theory's constant-k assumption, and it accurately describes at least some data that are inconsistent with the classic theory.

Linear-response time-dependent density-functional theory with pairing fields.

PubMed

Peng, Degao; van Aggelen, Helen; Yang, Yang; Yang, Weitao

2014-05-14

Recent development in particle-particle random phase approximation (pp-RPA) broadens the perspective on ground state correlation energies [H. van Aggelen, Y. Yang, and W. Yang, Phys. Rev. A 88, 030501 (2013), Y. Yang, H. van Aggelen, S. N. Steinmann, D. Peng, and W. Yang, J. Chem. Phys. 139, 174110 (2013); D. Peng, S. N. Steinmann, H. van Aggelen, and W. Yang, J. Chem. Phys. 139, 104112 (2013)] and N ± 2 excitation energies [Y. Yang, H. van Aggelen, and W. Yang, J. Chem. Phys. 139, 224105 (2013)]. So far Hartree-Fock and approximated density-functional orbitals have been utilized to evaluate the pp-RPA equation. In this paper, to further explore the fundamentals and the potential use of pairing matrix dependent functionals, we present the linear-response time-dependent density-functional theory with pairing fields with both adiabatic and frequency-dependent kernels. This theory is related to the density-functional theory and time-dependent density-functional theory for superconductors, but is applied to normal non-superconducting systems for our purpose. Due to the lack of the proof of the one-to-one mapping between the pairing matrix and the pairing field for time-dependent systems, the linear-response theory is established based on the representability assumption of the pairing matrix. The linear response theory justifies the use of approximated density-functionals in the pp-RPA equation. This work sets the fundamentals for future density-functional development to enhance the description of ground state correlation energies and N ± 2 excitation energies.

Research on Capturing of Customer Requirements Based on Innovation Theory

NASA Astrophysics Data System (ADS)

junwu, Ding; dongtao, Yang; zhenqiang, Bao

To exactly and effectively capture customer requirements information, a new customer requirements capturing modeling method was proposed. Based on the analysis of function requirement models of previous products and the application of technology system evolution laws of the Theory of Innovative Problem Solving (TRIZ), the customer requirements could be evolved from existing product designs, through modifying the functional requirement unit and confirming the direction of evolution design. Finally, a case study was provided to illustrate the feasibility of the proposed approach.

New Approaches and Applications for Monte Carlo Perturbation Theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aufiero, Manuele; Bidaud, Adrien; Kotlyar, Dan

2017-02-01

This paper presents some of the recent and new advancements in the extension of Monte Carlo Perturbation Theory methodologies and application. In particular, the discussed problems involve Brunup calculation, perturbation calculation based on continuous energy functions, and Monte Carlo Perturbation Theory in loosely coupled systems.

Site-occupation embedding theory using Bethe ansatz local density approximations

NASA Astrophysics Data System (ADS)

Senjean, Bruno; Nakatani, Naoki; Tsuchiizu, Masahisa; Fromager, Emmanuel

2018-06-01

Site-occupation embedding theory (SOET) is an alternative formulation of density functional theory (DFT) for model Hamiltonians where the fully interacting Hubbard problem is mapped, in principle exactly, onto an impurity-interacting (rather than a noninteracting) one. It provides a rigorous framework for combining wave-function (or Green function)-based methods with DFT. In this work, exact expressions for the per-site energy and double occupation of the uniform Hubbard model are derived in the context of SOET. As readily seen from these derivations, the so-called bath contribution to the per-site correlation energy is, in addition to the latter, the key density functional quantity to model in SOET. Various approximations based on Bethe ansatz and perturbative solutions to the Hubbard and single-impurity Anderson models are constructed and tested on a one-dimensional ring. The self-consistent calculation of the embedded impurity wave function has been performed with the density-matrix renormalization group method. It has been shown that promising results are obtained in specific regimes of correlation and density. Possible further developments have been proposed in order to provide reliable embedding functionals and potentials.

Theory of melting at high pressures: Amending density functional theory with quantum Monte Carlo

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shulenburger, L.; Desjarlais, M. P.; Mattsson, T. R.

We present an improved first-principles description of melting under pressure based on thermodynamic integration comparing Density Functional Theory (DFT) and quantum Monte Carlo (QMC) treatments of the system. The method is applied to address the longstanding discrepancy between density functional theory (DFT) calculations and diamond anvil cell (DAC) experiments on the melting curve of xenon, a noble gas solid where van der Waals binding is challenging for traditional DFT methods. The calculations show excellent agreement with data below 20 GPa and that the high-pressure melt curve is well described by a Lindemann behavior up to at least 80 GPa, amore » finding in stark contrast to DAC data.« less

Theory of melting at high pressures: Amending density functional theory with quantum Monte Carlo

DOE PAGES

Shulenburger, L.; Desjarlais, M. P.; Mattsson, T. R.

2014-10-01

We present an improved first-principles description of melting under pressure based on thermodynamic integration comparing Density Functional Theory (DFT) and quantum Monte Carlo (QMC) treatments of the system. The method is applied to address the longstanding discrepancy between density functional theory (DFT) calculations and diamond anvil cell (DAC) experiments on the melting curve of xenon, a noble gas solid where van der Waals binding is challenging for traditional DFT methods. The calculations show excellent agreement with data below 20 GPa and that the high-pressure melt curve is well described by a Lindemann behavior up to at least 80 GPa, amore » finding in stark contrast to DAC data.« less

Exact density functional theory for ideal polymer fluids with nearest neighbor bonding constraints.

PubMed

Woodward, Clifford E; Forsman, Jan

2008-08-07

We present a new density functional theory of ideal polymer fluids, assuming nearest-neighbor bonding constraints. The free energy functional is expressed in terms of end site densities of chain segments and thus has a simpler mathematical structure than previously used expressions using multipoint distributions. This work is based on a formalism proposed by Tripathi and Chapman [Phys. Rev. Lett. 94, 087801 (2005)]. Those authors obtain an approximate free energy functional for ideal polymers in terms of monomer site densities. Calculations on both repulsive and attractive surfaces show that their theory is reasonably accurate in some cases, but does differ significantly from the exact result for longer polymers with attractive surfaces. We suggest that segment end site densities, rather than monomer site densities, are the preferred choice of "site functions" for expressing the free energy functional of polymer fluids. We illustrate the application of our theory to derive an expression for the free energy of an ideal fluid of infinitely long polymers.

Basis convergence of range-separated density-functional theory.

PubMed

Franck, Odile; Mussard, Bastien; Luppi, Eleonora; Toulouse, Julien

2015-02-21

Range-separated density-functional theory (DFT) is an alternative approach to Kohn-Sham density-functional theory. The strategy of range-separated density-functional theory consists in separating the Coulomb electron-electron interaction into long-range and short-range components and treating the long-range part by an explicit many-body wave-function method and the short-range part by a density-functional approximation. Among the advantages of using many-body methods for the long-range part of the electron-electron interaction is that they are much less sensitive to the one-electron atomic basis compared to the case of the standard Coulomb interaction. Here, we provide a detailed study of the basis convergence of range-separated density-functional theory. We study the convergence of the partial-wave expansion of the long-range wave function near the electron-electron coalescence. We show that the rate of convergence is exponential with respect to the maximal angular momentum L for the long-range wave function, whereas it is polynomial for the case of the Coulomb interaction. We also study the convergence of the long-range second-order Møller-Plesset correlation energy of four systems (He, Ne, N2, and H2O) with cardinal number X of the Dunning basis sets cc - p(C)V XZ and find that the error in the correlation energy is best fitted by an exponential in X. This leads us to propose a three-point complete-basis-set extrapolation scheme for range-separated density-functional theory based on an exponential formula.

Excited state absorption spectra of dissolved and aggregated distyrylbenzene: A TD-DFT state and vibronic analysis

NASA Astrophysics Data System (ADS)

Oliveira, Eliezer Fernando; Shi, Junqing; Lavarda, Francisco Carlos; Lüer, Larry; Milián-Medina, Begoña; Gierschner, Johannes

2017-07-01

A time-dependent density functional theory study is performed to reveal the excited state absorption (ESA) features of distyrylbenzene (DSB), a prototype π-conjugated organic oligomer. Starting with a didactic insight to ESA based on simple molecular orbital and configuration considerations, the performance of various density functional theory functionals is tested to reveal the full vibronic ESA features of DSB at short and long probe delay times.

Fluid and Crystallized Intelligence--Theory and Research in Later Adulthood.

ERIC Educational Resources Information Center

Willis, Sherry L.; Baltes, Paul B.

Two studies examined modifiability in intellectual functioning in older adults. The fluid-crystallized theory provided a theory base for the research. (Fluid intelligence follows a normative decline through adulthood, while crystallized intelligence remains stable or even increases.) In the first study thirty subjects (average age 69.2)…

Molecular simulation of disjoining-pressure isotherms for free liquid , Lennard-Jones thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhatt, Divesh; Newman, John; Radke, C.J.

2001-10-01

We present canonical-ensemble molecular-dynamics simulations of disjoining-pressure isotherms in Lennard-Jones free liquid films. Thermodynamics demands that the disjoining pressure is determined uniquely as a function of the chemical potential purely from the phase diagram of the fluid. Our results from molecular dynamics validate this argument. The inverse-sixth-power distance term in the Lennard-Jones intermolecular potential represents van der Waals dispersion forces. Hence, we compare our results with classical Hamaker theory that is based on dispersion forces but assumes a slab geometry for the density profile and completely neglects fluid structure and entropy. We find that the Hamaker constant obtained from ourmore » simulations is about an order of magnitude larger than that from classical theory. To investigate the origin of this discrepancy, we calculate the disjoining-pressure isotherm using a density-functional theory relaxing the inherent assumptions in the Hamaker theory and imparting to the fluid an approximate structure. For disjoining pressure as a function of chemical potential, the results of density-functional theory and molecular dynamics are very close. Even for disjoining-pressure isotherms, and the subsequently calculated Hamaker constant, results of the density-functional theory are closer to the molecular-dynamics simulations by about a factor of 4 compared to Hamaker theory. [References: 44]« less

Some Applications of Gröbner Bases in Robotics and Engineering

NASA Astrophysics Data System (ADS)

Abłamowicz, Rafał

Gröbner bases in polynomial rings have numerous applications in geometry, applied mathematics, and engineering. We show a few applications of Gröbner bases in robotics, formulated in the language of Clifford algebras, and in engineering to the theory of curves, including Fermat and Bézier cubics, and interpolation functions used in finite element theory.

A recursively formulated first-order semianalytic artificial satellite theory based on the generalized method of averaging. Volume 1: The generalized method of averaging applied to the artificial satellite problem

NASA Technical Reports Server (NTRS)

Mcclain, W. D.

1977-01-01

A recursively formulated, first-order, semianalytic artificial satellite theory, based on the generalized method of averaging is presented in two volumes. Volume I comprehensively discusses the theory of the generalized method of averaging applied to the artificial satellite problem. Volume II presents the explicit development in the nonsingular equinoctial elements of the first-order average equations of motion. The recursive algorithms used to evaluate the first-order averaged equations of motion are also presented in Volume II. This semianalytic theory is, in principle, valid for a term of arbitrary degree in the expansion of the third-body disturbing function (nonresonant cases only) and for a term of arbitrary degree and order in the expansion of the nonspherical gravitational potential function.

Analysis of Undergraduate Students’ Mathematical Understanding Ability of the Limit of Function Based on APOS Theory Perspective

NASA Astrophysics Data System (ADS)

Afgani, M. W.; Suryadi, D.; Dahlan, J. A.

2017-09-01

The aim of this study was to know the level of undergraduate students’ mathematical understanding ability based on APOS theory perspective. The APOS theory provides an evaluation framework to describe the level of students’ understanding and mental structure about their conception to a mathematics concept. The levels of understanding in APOS theory are action, process, object, and schema conception. The subjects were 59 students of mathematics education whom had attended a class of the limit of function at a university in Palembang. The method was qualitative descriptive with 4 test items. The result showed that most of students were still at the level of action conception. They could calculate and use procedure precisely to the mathematics objects that was given, but could not reach the higher conception yet.

Introduction to Generalized Functions with Applications in Aerodynamics and Aeroacoustics

NASA Technical Reports Server (NTRS)

Farassat, F.

1994-01-01

Generalized functions have many applications in science and engineering. One useful aspect is that discontinuous functions can be handled as easily as continuous or differentiable functions and provide a powerful tool in formulating and solving many problems of aerodynamics and acoustics. Furthermore, generalized function theory elucidates and unifies many ad hoc mathematical approaches used by engineers and scientists. We define generalized functions as continuous linear functionals on the space of infinitely differentiable functions with compact support, then introduce the concept of generalized differentiation. Generalized differentiation is the most important concept in generalized function theory and the applications we present utilize mainly this concept. First, some results of classical analysis, are derived with the generalized function theory. Other applications of the generalized function theory in aerodynamics discussed here are the derivations of general transport theorems for deriving governing equations of fluid mechanics, the interpretation of the finite part of divergent integrals, the derivation of the Oswatitsch integral equation of transonic flow, and the analysis of velocity field discontinuities as sources of vorticity. Applications in aeroacoustics include the derivation of the Kirchhoff formula for moving surfaces, the noise from moving surfaces, and shock noise source strength based on the Ffowcs Williams-Hawkings equation.

On the abundance of extreme voids II: a survey of void mass functions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chongchitnan, Siri; Hunt, Matthew, E-mail: s.chongchitnan@hull.ac.uk, E-mail: m.d.hunt@2012.hull.ac.uk

2017-03-01

The abundance of cosmic voids can be described by an analogue of halo mass functions for galaxy clusters. In this work, we explore a number of void mass functions: from those based on excursion-set theory to new mass functions obtained by modifying halo mass functions. We show how different void mass functions vary in their predictions for the largest void expected in an observational volume, and compare those predictions to observational data. Our extreme-value formalism is shown to be a new practical tool for testing void theories against simulation and observation.

A kernel function method for computing steady and oscillatory supersonic aerodynamics with interference.

NASA Technical Reports Server (NTRS)

Cunningham, A. M., Jr.

1973-01-01

The method presented uses a collocation technique with the nonplanar kernel function to solve supersonic lifting surface problems with and without interference. A set of pressure functions are developed based on conical flow theory solutions which account for discontinuities in the supersonic pressure distributions. These functions permit faster solution convergence than is possible with conventional supersonic pressure functions. An improper integral of a 3/2 power singularity along the Mach hyperbola of the nonplanar supersonic kernel function is described and treated. The method is compared with other theories and experiment for a variety of cases.

Theory of mind and executive function during middle childhood across cultures.

PubMed

Wang, Zhenlin; Devine, Rory T; Wong, Keri K; Hughes, Claire

2016-09-01

Previous studies with preschoolers have reported "East-West" contrasts in children's executive function (East>West) and theory of mind (East

Invariant resolutions for several Fueter operators

NASA Astrophysics Data System (ADS)

Colombo, Fabrizio; Souček, Vladimir; Struppa, Daniele C.

2006-07-01

A proper generalization of complex function theory to higher dimension is Clifford analysis and an analogue of holomorphic functions of several complex variables were recently described as the space of solutions of several Dirac equations. The four-dimensional case has special features and is closely connected to functions of quaternionic variables. In this paper we present an approach to the Dolbeault sequence for several quaternionic variables based on symmetries and representation theory. In particular we prove that the resolution of the Cauchy-Fueter system obtained algebraically, via Gröbner bases techniques, is equivalent to the one obtained by R.J. Baston (J. Geom. Phys. 1992).

Operationalizing Levels of Academic Mastery Based on Vygotsky's Theory: The Study of Mathematical Knowledge

ERIC Educational Resources Information Center

Nezhnov, Peter; Kardanova, Elena; Vasilyeva, Marina; Ludlow, Larry

2015-01-01

The present study tested the possibility of operationalizing levels of knowledge acquisition based on Vygotsky's theory of cognitive growth. An assessment tool (SAM-Math) was developed to capture a hypothesized hierarchical structure of mathematical knowledge consisting of procedural, conceptual, and functional levels. In Study 1, SAM-Math was…

Size-expanded DNA bases: An ab-initio study of their structural and electronic properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fuentes-Cabrera, Miguel A; Sumpter, Bobby G; Wells, Jack C

2005-01-01

The size-expanded DNA bases, xA, xC, xG, and xT, are benzo-homologue forms of the natural DNA bases; i.e., their structure can be seen as the fusion of a natural base and a benzene ring. Recently, a variety of DNAs, known as xDNAs, have been synthesized in which size-expanded and natural bases are paired. In this paper we use second-order Moeller-Plesset perturbation theory and density functional theory to investigate the structural and electronic properties of xA, xC, xG, and xT and their natural counterparts. We find that whereas natural and size-expanded bases have both nonplanar amino groups the latter have alsomore » nonplanar aromatic rings. When density functional theory is used to investigate the electronic properties of size-expanded and natural bases, it is found that the HOMO-LUMO gap of the size-expanded bases is smaller than that of the natural bases. Also, xG should be easier to oxidize than G.« less

Melting slope of MgO from molecular dynamics and density functional theory

NASA Astrophysics Data System (ADS)

Tangney, Paul; Scandolo, Sandro

2009-09-01

We combine density functional theory (DFT) with molecular dynamics simulations based on an accurate atomistic force field to calculate the pressure derivative of the melting temperature of magnesium oxide at ambient pressure—a quantity for which a serious disagreement between theory and experiment has existed for almost 15 years. We find reasonable agreement with previous DFT results and with a very recent experimental determination of the slope. We pay particular attention to areas of possible weakness in theoretical calculations and conclude that the long-standing discrepancy with experiment could only be explained by a dramatic failure of existing density functionals or by flaws in the original experiment.

Examining Differential Item Functions of Different Item Ordered Test Forms According to Item Difficulty Levels

ERIC Educational Resources Information Center

Çokluk, Ömay; Gül, Emrah; Dogan-Gül, Çilem

2016-01-01

The study aims to examine whether differential item function is displayed in three different test forms that have item orders of random and sequential versions (easy-to-hard and hard-to-easy), based on Classical Test Theory (CTT) and Item Response Theory (IRT) methods and bearing item difficulty levels in mind. In the correlational research, the…

Functional network-based statistics in depression: Theory of mind subnetwork and importance of parietal region.

PubMed

Lai, Chien-Han; Wu, Yu-Te; Hou, Yuh-Ming

2017-08-01

The functional network analysis of whole brain is an emerging field for research in depression. We initiated this study to investigate which subnetwork is significantly altered within the functional connectome in major depressive disorder (MDD). The study enrolled 52 first-episode medication-naïve patients with MDD and 40 controls for functional network analysis. All participants received the resting-state functional imaging using a 3-Tesla magnetic resonance scanner. After preprocessing, we calculated the connectivity matrix of functional connectivity in whole brain for each subject. The network-based statistics of connectome was used to perform group comparisons between patients and controls. The correlations between functional connectivity and clinical parameters were also performed. MDD patients had significant alterations in the network involving "theory of mind" regions, such as the left precentral gyrus, left angular gyrus, bilateral rolandic operculums and left inferior frontal gyrus. The center node of significant network was the left angular gyrus. No significant correlations of functional connectivity within the subnetwork and clinical parameters were noted. Functional connectivity of "theory of mind" subnetwork may be the core issue for pathophysiology in MDD. In addition, the center role of parietal region should be emphasized in future study. Copyright © 2017. Published by Elsevier B.V.

Improving measurement of injection drug risk behavior using item response theory.

PubMed

Janulis, Patrick

2014-03-01

Recent research highlights the multiple steps to preparing and injecting drugs and the resultant viral threats faced by drug users. This research suggests that more sensitive measurement of injection drug HIV risk behavior is required. In addition, growing evidence suggests there are gender differences in injection risk behavior. However, the potential for differential item functioning between genders has not been explored. To explore item response theory as an improved measurement modeling technique that provides empirically justified scaling of injection risk behavior and to examine for potential gender-based differential item functioning. Data is used from three studies in the National Institute on Drug Abuse's Criminal Justice Drug Abuse Treatment Studies. A two-parameter item response theory model was used to scale injection risk behavior and logistic regression was used to examine for differential item functioning. Item fit statistics suggest that item response theory can be used to scale injection risk behavior and these models can provide more sensitive estimates of risk behavior. Additionally, gender-based differential item functioning is present in the current data. Improved measurement of injection risk behavior using item response theory should be encouraged as these models provide increased congruence between construct measurement and the complexity of injection-related HIV risk. Suggestions are made to further improve injection risk behavior measurement. Furthermore, results suggest direct comparisons of composite scores between males and females may be misleading and future work should account for differential item functioning before comparing levels of injection risk behavior.

Calculation of exchange coupling constants in triply-bridged dinuclear Cu(II) compounds based on spin-flip constricted variational density functional theory.

PubMed

Seidu, Issaka; Zhekova, Hristina R; Seth, Michael; Ziegler, Tom

2012-03-08

The performance of the second-order spin-flip constricted variational density functional theory (SF-CV(2)-DFT) for the calculation of the exchange coupling constant (J) is assessed by application to a series of triply bridged Cu(II) dinuclear complexes. A comparison of the J values based on SF-CV(2)-DFT with those obtained by the broken symmetry (BS) DFT method and experiment is provided. It is demonstrated that our methodology constitutes a viable alternative to the BS-DFT method. The strong dependence of the calculated exchange coupling constants on the applied functionals is demonstrated. Both SF-CV(2)-DFT and BS-DFT affords the best agreement with experiment for hybrid functionals.

Complex basis functions for molecular resonances: Methodology and applications

NASA Astrophysics Data System (ADS)

White, Alec; McCurdy, C. William; Head-Gordon, Martin

The computation of positions and widths of metastable electronic states is a challenge for molecular electronic structure theory because, in addition to the difficulty of the many-body problem, such states obey scattering boundary conditions. These resonances cannot be addressed with naïve application of traditional bound state electronic structure theory. Non-Hermitian electronic structure methods employing complex basis functions is one way that we may rigorously treat resonances within the framework of traditional electronic structure theory. In this talk, I will discuss our recent work in this area including the methodological extension from single determinant SCF-based approaches to highly correlated levels of wavefunction-based theory such as equation of motion coupled cluster and many-body perturbation theory. These approaches provide a hierarchy of theoretical methods for the computation of positions and widths of molecular resonances. Within this framework, we may also examine properties of resonances including the dependence of these parameters on molecular geometry. Some applications of these methods to temporary anions and dianions will also be discussed.

Self-consistent Green's function embedding for advanced electronic structure methods based on a dynamical mean-field concept

NASA Astrophysics Data System (ADS)

Chibani, Wael; Ren, Xinguo; Scheffler, Matthias; Rinke, Patrick

2016-04-01

We present an embedding scheme for periodic systems that facilitates the treatment of the physically important part (here a unit cell or a supercell) with advanced electronic structure methods, that are computationally too expensive for periodic systems. The rest of the periodic system is treated with computationally less demanding approaches, e.g., Kohn-Sham density-functional theory, in a self-consistent manner. Our scheme is based on the concept of dynamical mean-field theory formulated in terms of Green's functions. Our real-space dynamical mean-field embedding scheme features two nested Dyson equations, one for the embedded cluster and another for the periodic surrounding. The total energy is computed from the resulting Green's functions. The performance of our scheme is demonstrated by treating the embedded region with hybrid functionals and many-body perturbation theory in the GW approach for simple bulk systems. The total energy and the density of states converge rapidly with respect to the computational parameters and approach their bulk limit with increasing cluster (i.e., computational supercell) size.

Space-time models based on random fields with local interactions

NASA Astrophysics Data System (ADS)

Hristopulos, Dionissios T.; Tsantili, Ivi C.

2016-08-01

The analysis of space-time data from complex, real-life phenomena requires the use of flexible and physically motivated covariance functions. In most cases, it is not possible to explicitly solve the equations of motion for the fields or the respective covariance functions. In the statistical literature, covariance functions are often based on mathematical constructions. In this paper, we propose deriving space-time covariance functions by solving “effective equations of motion”, which can be used as statistical representations of systems with diffusive behavior. In particular, we propose to formulate space-time covariance functions based on an equilibrium effective Hamiltonian using the linear response theory. The effective space-time dynamics is then generated by a stochastic perturbation around the equilibrium point of the classical field Hamiltonian leading to an associated Langevin equation. We employ a Hamiltonian which extends the classical Gaussian field theory by including a curvature term and leads to a diffusive Langevin equation. Finally, we derive new forms of space-time covariance functions.

On Painlevé/gauge theory correspondence

NASA Astrophysics Data System (ADS)

Bonelli, Giulio; Lisovyy, Oleg; Maruyoshi, Kazunobu; Sciarappa, Antonio; Tanzini, Alessandro

2017-12-01

We elucidate the relation between Painlevé equations and four-dimensional rank one N = 2 theories by identifying the connection associated with Painlevé isomonodromic problems with the oper limit of the flat connection of the Hitchin system associated with gauge theories and by studying the corresponding renormalization group flow. Based on this correspondence, we provide long-distance expansions at various canonical rays for all Painlevé τ -functions in terms of magnetic and dyonic Nekrasov partition functions for N = 2 SQCD and Argyres-Douglas theories at self-dual Omega background ɛ _1 + ɛ _2 = 0 or equivalently in terms of c=1 irregular conformal blocks.

Recall Latencies, Confidence, and Output Positions of True and False Memories: Implications for Recall and Metamemory Theories

ERIC Educational Resources Information Center

Jou, Jerwen

2008-01-01

Recall latency, recall accuracy rate, and recall confidence were examined in free recall as a function of recall output serial position using a modified Deese-Roediger-McDermott paradigm to test a strength-based theory against the dual-retrieval process theory of recall output sequence. The strength theory predicts the item output sequence to be…

A new quasi-relativistic approach for density functional theory based on the normalized elimination of the small component

NASA Astrophysics Data System (ADS)

Filatov, Michael; Cremer, Dieter

2002-01-01

A recently developed variationally stable quasi-relativistic method, which is based on the low-order approximation to the method of normalized elimination of the small component, was incorporated into density functional theory (DFT). The new method was tested for diatomic molecules involving Ag, Cd, Au, and Hg by calculating equilibrium bond lengths, vibrational frequencies, and dissociation energies. The method is easy to implement into standard quantum chemical programs and leads to accurate results for the benchmark systems studied.

Oscillatory supersonic kernel function method for interfering surfaces

NASA Technical Reports Server (NTRS)

Cunningham, A. M., Jr.

1974-01-01

In the method presented in this paper, a collocation technique is used with the nonplanar supersonic kernel function to solve multiple lifting surface problems with interference in steady or oscillatory flow. The pressure functions used are based on conical flow theory solutions and provide faster solution convergence than is possible with conventional functions. In the application of the nonplanar supersonic kernel function, an improper integral of a 3/2 power singularity along the Mach hyperbola is described and treated. The method is compared with other theories and experiment for two wing-tail configurations in steady and oscillatory flow.

Basis convergence of range-separated density-functional theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Franck, Odile, E-mail: odile.franck@etu.upmc.fr; Mussard, Bastien, E-mail: bastien.mussard@upmc.fr; CNRS, UMR 7616, Laboratoire de Chimie Théorique, F-75005 Paris

2015-02-21

Range-separated density-functional theory (DFT) is an alternative approach to Kohn-Sham density-functional theory. The strategy of range-separated density-functional theory consists in separating the Coulomb electron-electron interaction into long-range and short-range components and treating the long-range part by an explicit many-body wave-function method and the short-range part by a density-functional approximation. Among the advantages of using many-body methods for the long-range part of the electron-electron interaction is that they are much less sensitive to the one-electron atomic basis compared to the case of the standard Coulomb interaction. Here, we provide a detailed study of the basis convergence of range-separated density-functional theory. Wemore » study the convergence of the partial-wave expansion of the long-range wave function near the electron-electron coalescence. We show that the rate of convergence is exponential with respect to the maximal angular momentum L for the long-range wave function, whereas it is polynomial for the case of the Coulomb interaction. We also study the convergence of the long-range second-order Møller-Plesset correlation energy of four systems (He, Ne, N{sub 2}, and H{sub 2}O) with cardinal number X of the Dunning basis sets cc − p(C)V XZ and find that the error in the correlation energy is best fitted by an exponential in X. This leads us to propose a three-point complete-basis-set extrapolation scheme for range-separated density-functional theory based on an exponential formula.« less

Can time-dependent density functional theory predict intersystem crossing in organic chromophores? A case study on benzo(bis)-X-diazole based donor-acceptor-donor type molecules.

PubMed

Tam, Teck Lip Dexter; Lin, Ting Ting; Chua, Ming Hui

2017-06-21

Here we utilized new diagnostic tools in time-dependent density functional theory to explain the trend of intersystem crossing in benzo(bis)-X-diazole based donor-acceptor-donor type molecules. These molecules display a wide range of fluorescence quantum yields and triplet yields, making them excellent candidates for testing the validity of these diagnostic tools. We believe that these tools are cost-effective and can be applied to structurally similar organic chromophores to predict/explain the trends of intersystem crossing, and thus fluorescence quantum yields and triplet yields without the use of complex and expensive multireference configuration interaction or multireference pertubation theory methods.

What Density Functional Theory could do for Quantum Information

NASA Astrophysics Data System (ADS)

Mattsson, Ann

2015-03-01

The Hohenberg-Kohn theorem of Density Functional Theory (DFT), and extensions thereof, tells us that all properties of a system of electrons can be determined through their density, which uniquely determines the many-body wave-function. Given access to the appropriate, universal, functionals of the density we would, in theory, be able to determine all observables of any electronic system, without explicit reference to the wave-function. On the other hand, the wave-function is at the core of Quantum Information (QI), with the wave-function of a set of qubits being the central computational resource in a quantum computer. While there is seemingly little overlap between DFT and QI, reliance upon observables form a key connection. Though the time-evolution of the wave-function and associated phase information is fundamental to quantum computation, the initial and final states of a quantum computer are characterized by observables of the system. While observables can be extracted directly from a system's wave-function, DFT tells us that we may be able to intuit a method for extracting them from its density. In this talk, I will review the fundamentals of DFT and how these principles connect to the world of QI. This will range from DFT's utility in the engineering of physical qubits, to the possibility of using it to efficiently (but approximately) simulate Hamiltonians at the logical level. The apparent paradox of describing algorithms based on the quantum mechanical many-body wave-function with a DFT-like theory based on observables will remain a focus throughout. The ultimate goal of this talk is to initiate a dialog about what DFT could do for QI, in theory and in practice. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

On the application of the partition of unity method for nonlocal response of low-dimensional structures

NASA Astrophysics Data System (ADS)

Natarajan, Sundararajan

2014-12-01

The main objectives of the paper are to (1) present an overview of nonlocal integral elasticity and Aifantis gradient elasticity theory and (2) discuss the application of partition of unity methods to study the response of low-dimensional structures. We present different choices of approximation functions for gradient elasticity, namely Lagrange intepolants, moving least-squares approximants and non-uniform rational B-splines. Next, we employ these approximation functions to study the response of nanobeams based on Euler-Bernoulli and Timoshenko theories as well as to study nanoplates based on first-order shear deformation theory. The response of nanobeams and nanoplates is studied using Eringen's nonlocal elasticity theory. The influence of the nonlocal parameter, the beam and the plate aspect ratio and the boundary conditions on the global response is numerically studied. The influence of a crack on the axial vibration and buckling characteristics of nanobeams is also numerically studied.

The pair correlation function of krypton in the critical region: theory and experiment

NASA Astrophysics Data System (ADS)

Barocchi, F.; Chieux, P.; Fontana, R.; Magli, R.; Meroni, A.; Parola, A.; Reatto, L.; Tau, M.

1997-10-01

We present the results of high-precision measurements of the structure factor S(k) of krypton in the near-critical region of the liquid - vapour phase transition for values of k ranging from 1.5 up to 0953-8984/9/42/003/img15. The experimental results are compared with a theoretical calculation based on the hierarchical reference theory (HRT) with an accurate potential which includes two- and three-body contributions. The theory is based on a new implementation of HRT in which we avoid the use of hard spheres as a reference system. With this soft-core formulation we find a generally good agreement with experiments both at large k, where S(k) probes the short-range correlations, as well as at small k, where critical fluctuations become dominant. Also, for the density derivative of the pair correlation function there is an overall good agreement between theory and experiment.

Quantum Theory of Orbital Magnetization and Its Generalization to Interacting Systems

NASA Astrophysics Data System (ADS)

Shi, Junren; Vignale, G.; Xiao, Di; Niu, Qian

2007-11-01

Based on standard perturbation theory, we present a full quantum derivation of the formula for the orbital magnetization in periodic systems. The derivation is generally valid for insulators with or without a Chern number, for metals at zero or finite temperatures, and at weak as well as strong magnetic fields. The formula is shown to be valid in the presence of electron-electron interaction, provided the one-electron energies and wave functions are calculated self-consistently within the framework of the exact current and spin-density functional theory.

Nonadiabatic Dynamics in Single-Electron Tunneling Devices with Time-Dependent Density-Functional Theory

NASA Astrophysics Data System (ADS)

Dittmann, Niklas; Splettstoesser, Janine; Helbig, Nicole

2018-04-01

We simulate the dynamics of a single-electron source, modeled as a quantum dot with on-site Coulomb interaction and tunnel coupling to an adjacent lead in time-dependent density-functional theory. Based on this system, we develop a time-nonlocal exchange-correlation potential by exploiting analogies with quantum-transport theory. The time nonlocality manifests itself in a dynamical potential step. We explicitly link the time evolution of the dynamical step to physical relaxation timescales of the electron dynamics. Finally, we discuss prospects for simulations of larger mesoscopic systems.

Nonadiabatic Dynamics in Single-Electron Tunneling Devices with Time-Dependent Density-Functional Theory.

PubMed

Dittmann, Niklas; Splettstoesser, Janine; Helbig, Nicole

2018-04-13

We simulate the dynamics of a single-electron source, modeled as a quantum dot with on-site Coulomb interaction and tunnel coupling to an adjacent lead in time-dependent density-functional theory. Based on this system, we develop a time-nonlocal exchange-correlation potential by exploiting analogies with quantum-transport theory. The time nonlocality manifests itself in a dynamical potential step. We explicitly link the time evolution of the dynamical step to physical relaxation timescales of the electron dynamics. Finally, we discuss prospects for simulations of larger mesoscopic systems.

A Comparison of Measurement Equivalence Methods Based on Confirmatory Factor Analysis and Item Response Theory.

ERIC Educational Resources Information Center

Flowers, Claudia P.; Raju, Nambury S.; Oshima, T. C.

Current interest in the assessment of measurement equivalence emphasizes two methods of analysis, linear, and nonlinear procedures. This study simulated data using the graded response model to examine the performance of linear (confirmatory factor analysis or CFA) and nonlinear (item-response-theory-based differential item function or IRT-Based…

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…

Poverty Lines Based on Fuzzy Sets Theory and Its Application to Malaysian Data

ERIC Educational Resources Information Center

Abdullah, Lazim

2011-01-01

Defining the poverty line has been acknowledged as being highly variable by the majority of published literature. Despite long discussions and successes, poverty line has a number of problems due to its arbitrary nature. This paper proposes three measurements of poverty lines using membership functions based on fuzzy set theory. The three…

Applications of the Conceptual Density Functional Theory Indices to Organic Chemistry Reactivity.

PubMed

Domingo, Luis R; Ríos-Gutiérrez, Mar; Pérez, Patricia

2016-06-09

Theoretical reactivity indices based on the conceptual Density Functional Theory (DFT) have become a powerful tool for the semiquantitative study of organic reactivity. A large number of reactivity indices have been proposed in the literature. Herein, global quantities like the electronic chemical potential μ, the electrophilicity ω and the nucleophilicity N indices, and local condensed indices like the electrophilic P k + and nucleophilic P k - Parr functions, as the most relevant indices for the study of organic reactivity, are discussed.

Second-Order Perturbation Theory for Generalized Active Space Self-Consistent-Field Wave Functions.

PubMed

Ma, Dongxia; Li Manni, Giovanni; Olsen, Jeppe; Gagliardi, Laura

2016-07-12

A multireference second-order perturbation theory approach based on the generalized active space self-consistent-field (GASSCF) wave function is presented. Compared with the complete active space (CAS) and restricted active space (RAS) wave functions, GAS wave functions are more flexible and can employ larger active spaces and/or different truncations of the configuration interaction expansion. With GASSCF, one can explore chemical systems that are not affordable with either CASSCF or RASSCF. Perturbation theory to second order on top of GAS wave functions (GASPT2) has been implemented to recover the remaining electron correlation. The method has been benchmarked by computing the chromium dimer ground-state potential energy curve. These calculations show that GASPT2 gives results similar to CASPT2 even with a configuration interaction expansion much smaller than the corresponding CAS expansion.

Cubic Zig-Zag Enrichment of the Classical Kirchhoff Kinematics for Laminated and Sandwich Plates

NASA Technical Reports Server (NTRS)

Nemeth, Michael P.

2012-01-01

A detailed anaylsis and examples are presented that show how to enrich the kinematics of classical Kirchhoff plate theory by appending them with a set of continuous piecewise-cubic functions. This analysis is used to obtain functions that contain the effects of laminate heterogeneity and asymmetry on the variations of the inplane displacements and transverse shearing stresses, for use with a {3, 0} plate theory in which these distributions are specified apriori. The functions used for the enrichment are based on the improved zig-zag plate theory presented recently by Tessler, Di Scuva, and Gherlone. With the approach presented herein, the inplane displacements are represented by a set of continuous piecewise-cubic functions, and the transverse shearing stresses and strains are represented by a set of piecewise-quadratic functions that are discontinuous at the ply interfaces.

The function of self-esteem in terror management theory and sociometer theory: comment on Pyszczynski et al. (2004).

PubMed

Leary, Mark R

2004-05-01

By applying different standards of evidence to sociometer theory than to terror management theory (TMT), T. Pyszczynski, J. Greenberg, S. Solomon, J. Arndt, and J. Schimel's (2004) review offers an imbalanced appraisal of the theories' merits. Many of Pyszczynski et al.'s (2004) criticisms of sociometer theory apply equally to TMT. and others are based on misconstruals of the theory or misunderstandings regarding how people respond when rejected. Furthermore, much of their review is only indirectly relevant to TMT's position on the function of self-esteem, and the review fails to acknowledge logical and empirical challenges to TMT. A more balanced review suggests that each theory trumps the other in certain respects, both have difficulty explaining all of the evidence regarding self-esteem, and the propositions of each theory can be roughly translated into the concepts of the other. For these reasons, declaring a theoretical winner at this time is premature. ((c) 2004 APA, all rights reserved)

Exact density functional and wave function embedding schemes based on orbital localization

NASA Astrophysics Data System (ADS)

Hégely, Bence; Nagy, Péter R.; Ferenczy, György G.; Kállay, Mihály

2016-08-01

Exact schemes for the embedding of density functional theory (DFT) and wave function theory (WFT) methods into lower-level DFT or WFT approaches are introduced utilizing orbital localization. First, a simple modification of the projector-based embedding scheme of Manby and co-workers [J. Chem. Phys. 140, 18A507 (2014)] is proposed. We also use localized orbitals to partition the system, but instead of augmenting the Fock operator with a somewhat arbitrary level-shift projector we solve the Huzinaga-equation, which strictly enforces the Pauli exclusion principle. Second, the embedding of WFT methods in local correlation approaches is studied. Since the latter methods split up the system into local domains, very simple embedding theories can be defined if the domains of the active subsystem and the environment are treated at a different level. The considered embedding schemes are benchmarked for reaction energies and compared to quantum mechanics (QM)/molecular mechanics (MM) and vacuum embedding. We conclude that for DFT-in-DFT embedding, the Huzinaga-equation-based scheme is more efficient than the other approaches, but QM/MM or even simple vacuum embedding is still competitive in particular cases. Concerning the embedding of wave function methods, the clear winner is the embedding of WFT into low-level local correlation approaches, and WFT-in-DFT embedding can only be more advantageous if a non-hybrid density functional is employed.

Compensatory recruitment of neural resources in chronic alcoholism.

PubMed

Chanraud, Sandra; Sullivan, Edith V

2014-01-01

Functional recovery occurs with sustained sobriety, but the neural mechanisms enabling recovery are only now emerging. Theories about promising mechanisms involve concepts of neuroadaptation, where excessive alcohol consumption results in untoward structural and functional brain changes which are subsequently candidates for reversal with sobriety. Views on functional adaptation in chronic alcoholism have expanded with results from neuroimaging studies. Here, we first describe and define the concept of neuroadaptation according to emerging theories based on the growing literature in aging-related cognitive functioning. Then we describe findings as they apply to chronic alcoholism and factors that could influence compensation, such as functional brain reserve and the integrity of brain structure. Finally, we review brain plasticity based on physiologic mechanisms that could underlie mechanisms of neural compensation. Where possible, we provide operational criteria to define functional and neural compensation. © 2014 Elsevier B.V. All rights reserved.

Perspectives on hand function in girls and women with Rett syndrome.

PubMed

Downs, Jenny; Parkinson, Stephanie; Ranelli, Sonia; Leonard, Helen; Diener, Pamela; Lotan, Meir

2014-06-01

Rett syndrome is a rare neurodevelopmental disorder that is usually associated with a mutation on the X-linked MECP2 gene. Hand function is particularly affected and we discuss theoretical and practical perspectives for optimising hand function in Rett syndrome. We reviewed the literature pertaining to hand function and stereotypies in Rett syndrome and developed a toolkit for their assessment and treatment. There is little published information on management of hand function in Rett syndrome. We suggest assessment and treatment strategies based on available literature, clinical experience and grounded in theories of motor control and motor learning. Additional studies are needed to determine the best treatments for hand function in Rett syndrome. Meanwhile, clinical needs can be addressed by supplementing the evidence base with an understanding of the complexities of Rett syndrome, clinical experience, environmental enrichment animal studies and theories of motor control and motor learning.

A Comparison of Web-Based and Face-to-Face Functional Measurement Experiments

ERIC Educational Resources Information Center

Van Acker, Frederik; Theuns, Peter

2010-01-01

Information Integration Theory (IIT) is concerned with how people combine information into an overall judgment. A method is hereby presented to perform Functional Measurement (FM) experiments, the methodological counterpart of IIT, on the Web. In a comparison of Web-based FM experiments, face-to-face experiments, and computer-based experiments in…

Requirements for Predictive Density Functional Theory Methods for Heavy Materials Equation of State

NASA Astrophysics Data System (ADS)

Mattsson, Ann E.; Wills, John M.

2012-02-01

The difficulties in experimentally determining the Equation of State of actinide and lanthanide materials has driven the development of many computational approaches with varying degree of empiricism and predictive power. While Density Functional Theory (DFT) based on the Schr"odinger Equation (possibly with relativistic corrections including the scalar relativistic approach) combined with local and semi-local functionals has proven to be a successful and predictive approach for many materials, it is not giving enough accuracy, or even is a complete failure, for the actinides. To remedy this failure both an improved fundamental description based on the Dirac Equation (DE) and improved functionals are needed. Based on results obtained using the appropriate fundamental approach of DFT based on the DE we discuss the performance of available semi-local functionals, the requirements for improved functionals for actinide/lanthanide materials, and the similarities in how functionals behave in transition metal oxides. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Concrete Operations as "Natural" Thinking.

ERIC Educational Resources Information Center

Reifschneider, Thomas J.

Proster Theory is a theory of learning which has been proposed by Leslie A. Hart (1975). The theory is based on the functions of the brain. Learning is seen as the formation of programs, which are simply sequences of instructions by which the brain directs the muscles, sense organs, or other portions of the neurological system. Programs which are…

The ideomotor recycling theory for language.

PubMed

Badets, Arnaud

2016-01-01

For language acquisition and processing, the ideomotor theory predicts that the comprehension and the production of language are functionally based on their expected perceptual effects (i.e., linguistic events). This anticipative mechanism is central for action-perception behaviors in human and nonhuman animals, but a recent ideomotor recycling theory has emphasized a language account throughout an evolutionary perspective.

Time-based and event-based prospective memory in autism spectrum disorder: the roles of executive function and theory of mind, and time-estimation.

PubMed

Williams, David; Boucher, Jill; Lind, Sophie; Jarrold, Christopher

2013-07-01

Prospective memory (remembering to carry out an action in the future) has been studied relatively little in ASD. We explored time-based (carry out an action at a pre-specified time) and event-based (carry out an action upon the occurrence of a pre-specified event) prospective memory, as well as possible cognitive correlates, among 21 intellectually high-functioning children with ASD, and 21 age- and IQ-matched neurotypical comparison children. We found impaired time-based, but undiminished event-based, prospective memory among children with ASD. In the ASD group, time-based prospective memory performance was associated significantly with diminished theory of mind, but not with diminished cognitive flexibility. There was no evidence that time-estimation ability contributed to time-based prospective memory impairment in ASD.

Quantum Sensors for the Generating Functional of Interacting Quantum Field Theories

NASA Astrophysics Data System (ADS)

Bermudez, A.; Aarts, G.; Müller, M.

2017-10-01

Difficult problems described in terms of interacting quantum fields evolving in real time or out of equilibrium abound in condensed-matter and high-energy physics. Addressing such problems via controlled experiments in atomic, molecular, and optical physics would be a breakthrough in the field of quantum simulations. In this work, we present a quantum-sensing protocol to measure the generating functional of an interacting quantum field theory and, with it, all the relevant information about its in- or out-of-equilibrium phenomena. Our protocol can be understood as a collective interferometric scheme based on a generalization of the notion of Schwinger sources in quantum field theories, which make it possible to probe the generating functional. We show that our scheme can be realized in crystals of trapped ions acting as analog quantum simulators of self-interacting scalar quantum field theories.

Unveiling the nature of post-linear response Z-vector method for time-dependent density functional theory.

PubMed

Pastore, Mariachiara; Assfeld, Xavier; Mosconi, Edoardo; Monari, Antonio; Etienne, Thibaud

2017-07-14

We report a theoretical study on the analysis of the relaxed one-particle difference density matrix characterizing the passage from the ground to the excited state of a molecular system, as obtained from time-dependent density functional theory. In particular, this work aims at using the physics contained in the so-called Z-vector, which differentiates between unrelaxed and relaxed difference density matrices to analyze excited states' nature. For this purpose, we introduce novel quantum-mechanical quantities, based on the detachment/attachment methodology, for analysing the Z-vector transformation for different molecules and density functional theory functionals. A derivation pathway of these novel descriptors is reported, involving a numerical integration to be performed in the Euclidean space on the density functions. This topological analysis is then applied to two sets of chromophores, and the correlation between the level of theory and the behavior of our descriptors is properly rationalized. In particular, the effect of range-separation on the relaxation amplitude is discussed. The relaxation term is finally shown to be system-specific (for a given level of theory) and independent of the number of electrons (i.e., the relaxation amplitude is not simply the result of a collective phenomenon).

Transitioning NWChem to the Next Generation of Manycore Machines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bylaska, Eric J.; Apra, E; Kowalski, Karol

The NorthWest chemistry (NWChem) modeling software is a popular molecular chemistry simulation software that was designed from the start to work on massively parallel processing supercomputers [1-3]. It contains an umbrella of modules that today includes self-consistent eld (SCF), second order Møller-Plesset perturbation theory (MP2), coupled cluster (CC), multiconguration self-consistent eld (MCSCF), selected conguration interaction (CI), tensor contraction engine (TCE) many body methods, density functional theory (DFT), time-dependent density functional theory (TDDFT), real-time time-dependent density functional theory, pseudopotential plane-wave density functional theory (PSPW), band structure (BAND), ab initio molecular dynamics (AIMD), Car-Parrinello molecular dynamics (MD), classical MD, hybrid quantum mechanicsmore » molecular mechanics (QM/MM), hybrid ab initio molecular dynamics molecular mechanics (AIMD/MM), gauge independent atomic orbital nuclear magnetic resonance (GIAO NMR), conductor like screening solvation model (COSMO), conductor-like screening solvation model based on density (COSMO-SMD), and reference interaction site model (RISM) solvation models, free energy simulations, reaction path optimization, parallel in time, among other capabilities [4]. Moreover, new capabilities continue to be added with each new release.« less

HOTCFGM-1D: A Coupled Higher-Order Theory for Cylindrical Structural Components with Through-Thickness Functionally Graded Microstructures

NASA Technical Reports Server (NTRS)

Pindera, Marek-Jerzy; Aboudi, Jacob

1998-01-01

The objective of this three-year project was to develop and deliver to NASA Lewis one-dimensional and two-dimensional higher-order theories, and related computer codes, for the analysis, optimization and design of cylindrical functionally graded materials/structural components for use in advanced aircraft engines (e.g., combustor linings, rotor disks, heat shields, blisk blades). To satisfy this objective, a quasi one-dimensional version of the higher-order theory, HOTCFGM-1D, and four computer codes based on this theory, for the analysis, design and optimization of cylindrical structural components functionally graded in the radial direction were developed. The theory is applicable to thin multi-phased composite shell/cylinders subjected to macroscopically axisymmetric thermomechanical and inertial loading applied uniformly along the axial direction such that the overall deformation is characterized by a constant average axial strain. The reinforcement phases are uniformly distributed in the axial and circumferential directions, and arbitrarily distributed in the radial direction, thereby allowing functional grading of the internal reinforcement in this direction.

Predicting Bond Dissociation Energies of Transition-Metal Compounds by Multiconfiguration Pair-Density Functional Theory and Second-Order Perturbation Theory Based on Correlated Participating Orbitals and Separated Pairs.

PubMed

Bao, Junwei Lucas; Odoh, Samuel O; Gagliardi, Laura; Truhlar, Donald G

2017-02-14

We study the performance of multiconfiguration pair-density functional theory (MC-PDFT) and multireference perturbation theory for the computation of the bond dissociation energies in 12 transition-metal-containing diatomic molecules and three small transition-metal-containing polyatomic molecules and in two transition-metal dimers. The first step is a multiconfiguration self-consistent-field calculation, for which two choices must be made: (i) the active space and (ii) its partition into subspaces, if the generalized active space formulation is used. In the present work, the active space is chosen systematically by using three correlated-participating-orbitals (CPO) schemes, and the partition is chosen by using the separated-pair (SP) approximation. Our calculations show that MC-PDFT generally has similar accuracy to CASPT2, and the active-space dependence of MC-PDFT is not very great for transition-metal-ligand bond dissociation energies. We also find that the SP approximation works very well, and in particular SP with the fully translated BLYP functional SP-ftBLYP is more accurate than CASPT2. SP greatly reduces the number of configuration state functions relative to CASSCF. For the cases of FeO and NiO with extended-CPO active space, for which complete active space calculations are unaffordable, SP calculations are not only affordable but also of satisfactory accuracy. All of the MC-PDFT results are significantly better than the corresponding results with broken-symmetry spin-unrestricted Kohn-Sham density functional theory. Finally we test a perturbation theory method based on the SP reference and find that it performs slightly worse than CASPT2 calculations, and for most cases of the nominal-CPO active space, the approximate SP perturbation theory calculations are less accurate than the much less expensive SP-PDFT calculations.

Comments on the variational modified-hypernetted-chain theory for simple fluids

NASA Astrophysics Data System (ADS)

Rosenfeld, Yaakov

1986-02-01

The variational modified-hypernetted-chain (VMHNC) theory, based on the approximation of universality of the bridge functions, is reformulated. The new formulation includes recent calculations by Lado and by Lado, Foiles, and Ashcroft, as two stages in a systematic approach which is analyzed. A variational iterative procedure for solving the exact (diagrammatic) equations for the fluid structure which is formally identical to the VMHNC is described, featuring the theory of simple classical fluids as a one-iteration theory. An accurate method for calculating the pair structure for a given potential and for inverting structure factor data in order to obtain the potential and the thermodynamic functions, follows from our analysis.

Quantile Functions, Convergence in Quantile, and Extreme Value Distribution Theory.

DTIC Science & Technology

1980-11-01

Gnanadesikan (1968). Quantile functions are advocated by Parzen (1979) as providing an approach to probability-based data analysis. Quantile functions are... Gnanadesikan , R. (1968). Probability Plotting Methods for the Analysis of Data, Biomtrika, 55, 1-17.

Left Handed Materials Based on Magnetic Nanocomposites

DTIC Science & Technology

2006-10-18

theory that unifies DNMs and SNMs as a function of two flmdamental material parameters: quality factors for permittivity (Qe=e’/e") and permeability (Qu...simultaneously negative effective permeability/uff and permittivity Seff to form LHM or only single negative parameter (SNM) to form negative indexed...developed a theory that unifies DNMs and SNMs as a function of two fundamental material parameters: quality factors for permittivity (Q, = -’/ 6") and

The integrated bispectrum in modified gravity theories

NASA Astrophysics Data System (ADS)

Munshi, Dipak

2017-01-01

Gravity-induced non-Gaussianity can provide important clues to Modified Gravity (MG) Theories. Several recent studies have suggested using the Integrated Bispectrum (IB) as a probe for squeezed configuration of bispectrum. Extending previous studies on the IB, we include redshift-space distortions to study a class of (parametrised) MG theories that include the string-inspired Dvali, Gabadadze & Porrati (DGP) model. Various contributions from redshift-space distortions are derived in a transparent manner, and squeezed contributions from these terms are derived separately. Results are obtained using the Zel'dovich Approximation (ZA). Results are also presented for projected surveys (2D). We use the Press-Schechter (PS) and Sheth-Tormen (ST) mass functions to compute the IB for collapsed objects that can readily be extended to peak-theory based approaches. The cumulant correlators (CCs) generalise the ordinary cumulants and are known to probe collapsed configurations of higher order correlation functions. We generalise the concept of CCs to halos of different masses. We also introduce a generating function based approach to analyse more general non-local biasing models. The Fourier representations of the CCs, the skew-spectrum, or the kurt-spctra are discussed in this context. The results are relevant for the study of the Minkowski Functionals (MF) of collapsed tracers in redshift-space.

The integrated bispectrum in modified gravity theories

DOE Office of Scientific and Technical Information (OSTI.GOV)

Munshi, Dipak, E-mail: D.Munshi@sussex.ac.uk

2017-01-01

Gravity-induced non-Gaussianity can provide important clues to Modified Gravity (MG) Theories. Several recent studies have suggested using the Integrated Bispectrum (IB) as a probe for squeezed configuration of bispectrum. Extending previous studies on the IB, we include redshift-space distortions to study a class of (parametrised) MG theories that include the string-inspired Dvali, Gabadadze and Porrati (DGP) model. Various contributions from redshift-space distortions are derived in a transparent manner, and squeezed contributions from these terms are derived separately. Results are obtained using the Zel'dovich Approximation (ZA). Results are also presented for projected surveys (2D). We use the Press-Schechter (PS) and Sheth-Tormenmore » (ST) mass functions to compute the IB for collapsed objects that can readily be extended to peak-theory based approaches. The cumulant correlators (CCs) generalise the ordinary cumulants and are known to probe collapsed configurations of higher order correlation functions. We generalise the concept of CCs to halos of different masses. We also introduce a generating function based approach to analyse more general non-local biasing models. The Fourier representations of the CCs, the skew-spectrum, or the kurt-spctra are discussed in this context. The results are relevant for the study of the Minkowski Functionals (MF) of collapsed tracers in redshift-space.« less

Axial postbuckling analysis of multilayer functionally graded composite nanoplates reinforced with GPLs based on nonlocal strain gradient theory

NASA Astrophysics Data System (ADS)

Sahmani, S.; Aghdam, M. M.

2017-11-01

In this paper, a new size-dependent inhomogeneous plate model is constructed to analyze the nonlinear buckling and postbuckling characteristics of multilayer functionally graded composite nanoplates reinforced with graphene platelet (GPL) nanofillers under axial compressive load. To this purpose, the nonlocal strain gradient theory of elasticity is implemented into a refined hyperbolic shear deformation plate theory. The mechanical properties of multilayer graphene platelet-reinforced composite (GPLRC) nanoplates are evaluated based upon the Halpin-Tsai micromechanical scheme. The weight fraction of randomly dispersed GPLs remain constant in each individual layer, which results in U-GPLRC nanoplate, or changes layerwise in accordance with three different functionally graded patterns, which make X-GPLRC, O-GPLRC and A-GPLRC nanoplates. Via a two-stepped perturbation technique, explicit analytical expressions for nonlocal strain gradient stability paths are established for layerwise functionally graded GPLRC nanoplates. It is demonstrated that both the nonlocal and strain gradient size dependencies are more significant for multilayer GPLRC nanoplates filling by GPL nanofillers with higher length-to-thickness and width-to-thickness ratios.

Decision making generalized by a cumulative probability weighting function

NASA Astrophysics Data System (ADS)

dos Santos, Lindomar Soares; Destefano, Natália; Martinez, Alexandre Souto

2018-01-01

Typical examples of intertemporal decision making involve situations in which individuals must choose between a smaller reward, but more immediate, and a larger one, delivered later. Analogously, probabilistic decision making involves choices between options whose consequences differ in relation to their probability of receiving. In Economics, the expected utility theory (EUT) and the discounted utility theory (DUT) are traditionally accepted normative models for describing, respectively, probabilistic and intertemporal decision making. A large number of experiments confirmed that the linearity assumed by the EUT does not explain some observed behaviors, as nonlinear preference, risk-seeking and loss aversion. That observation led to the development of new theoretical models, called non-expected utility theories (NEUT), which include a nonlinear transformation of the probability scale. An essential feature of the so-called preference function of these theories is that the probabilities are transformed by decision weights by means of a (cumulative) probability weighting function, w(p) . We obtain in this article a generalized function for the probabilistic discount process. This function has as particular cases mathematical forms already consecrated in the literature, including discount models that consider effects of psychophysical perception. We also propose a new generalized function for the functional form of w. The limiting cases of this function encompass some parametric forms already proposed in the literature. Far beyond a mere generalization, our function allows the interpretation of probabilistic decision making theories based on the assumption that individuals behave similarly in the face of probabilities and delays and is supported by phenomenological models.

An information theory framework for dynamic functional domain connectivity.

PubMed

Vergara, Victor M; Miller, Robyn; Calhoun, Vince

2017-06-01

Dynamic functional network connectivity (dFNC) analyzes time evolution of coherent activity in the brain. In this technique dynamic changes are considered for the whole brain. This paper proposes an information theory framework to measure information flowing among subsets of functional networks call functional domains. Our method aims at estimating bits of information contained and shared among domains. The succession of dynamic functional states is estimated at the domain level. Information quantity is based on the probabilities of observing each dynamic state. Mutual information measurement is then obtained from probabilities across domains. Thus, we named this value the cross domain mutual information (CDMI). Strong CDMIs were observed in relation to the subcortical domain. Domains related to sensorial input, motor control and cerebellum form another CDMI cluster. Information flow among other domains was seldom found. Other methods of dynamic connectivity focus on whole brain dFNC matrices. In the current framework, information theory is applied to states estimated from pairs of multi-network functional domains. In this context, we apply information theory to measure information flow across functional domains. Identified CDMI clusters point to known information pathways in the basal ganglia and also among areas of sensorial input, patterns found in static functional connectivity. In contrast, CDMI across brain areas of higher level cognitive processing follow a different pattern that indicates scarce information sharing. These findings show that employing information theory to formally measured information flow through brain domains reveals additional features of functional connectivity. Copyright © 2017 Elsevier B.V. All rights reserved.

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.

Plato: A localised orbital based density functional theory code

NASA Astrophysics Data System (ADS)

Kenny, S. D.; Horsfield, A. P.

2009-12-01

The Plato package allows both orthogonal and non-orthogonal tight-binding as well as density functional theory (DFT) calculations to be performed within a single framework. The package also provides extensive tools for analysing the results of simulations as well as a number of tools for creating input files. The code is based upon the ideas first discussed in Sankey and Niklewski (1989) [1] with extensions to allow high-quality DFT calculations to be performed. DFT calculations can utilise either the local density approximation or the generalised gradient approximation. Basis sets from minimal basis through to ones containing multiple radial functions per angular momenta and polarisation functions can be used. Illustrations of how the package has been employed are given along with instructions for its utilisation. Program summaryProgram title: Plato Catalogue identifier: AEFC_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEFC_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 219 974 No. of bytes in distributed program, including test data, etc.: 1 821 493 Distribution format: tar.gz Programming language: C/MPI and PERL Computer: Apple Macintosh, PC, Unix machines Operating system: Unix, Linux and Mac OS X Has the code been vectorised or parallelised?: Yes, up to 256 processors tested RAM: Up to 2 Gbytes per processor Classification: 7.3 External routines: LAPACK, BLAS and optionally ScaLAPACK, BLACS, PBLAS, FFTW Nature of problem: Density functional theory study of electronic structure and total energies of molecules, crystals and surfaces. Solution method: Localised orbital based density functional theory. Restrictions: Tight-binding and density functional theory only, no exact exchange. Unusual features: Both atom centred and uniform meshes available. Can deal with arbitrary angular momenta for orbitals, whilst still retaining Slater-Koster tables for accuracy. Running time: Test cases will run in a few minutes, large calculations may run for several days.

The Organizational Account of Function is an Etiological Account of Function.

PubMed

Artiga, Marc; Martínez, Manolo

2016-06-01

The debate on the notion of function has been historically dominated by dispositional and etiological accounts, but recently a third contender has gained prominence: the organizational account. This original theory of function is intended to offer an alternative account based on the notion of self-maintaining system. However, there is a set of cases where organizational accounts seem to generate counterintuitive results. These cases involve cross-generational traits, that is, traits that do not contribute in any relevant way to the self-maintenance of the organism carrying them, but instead have very important effects on organisms that belong to the next generation. We argue that any plausible solution to the problem of cross-generational traits shows that the organizational account just is a version of the etiological theory and, furthermore, that it does not provide any substantive advantage over standard etiological theories of function.

Brønsted acidity of protic ionic liquids: a modern ab initio valence bond theory perspective.

PubMed

Patil, Amol Baliram; Mahadeo Bhanage, Bhalchandra

2016-09-21

Room temperature ionic liquids (ILs), especially protic ionic liquids (PILs), are used in many areas of the chemical sciences. Ionicity, the extent of proton transfer, is a key parameter which determines many physicochemical properties and in turn the suitability of PILs for various applications. The spectrum of computational chemistry techniques applied to investigate ionic liquids includes classical molecular dynamics, Monte Carlo simulations, ab initio molecular dynamics, Density Functional Theory (DFT), CCSD(t) etc. At the other end of the spectrum is another computational approach: modern ab initio Valence Bond Theory (VBT). VBT differs from molecular orbital theory based methods in the expression of the molecular wave function. The molecular wave function in the valence bond ansatz is expressed as a linear combination of valence bond structures. These structures include covalent and ionic structures explicitly. Modern ab initio valence bond theory calculations of representative primary and tertiary ammonium protic ionic liquids indicate that modern ab initio valence bond theory can be employed to assess the acidity and ionicity of protic ionic liquids a priori.

Complex Chern-Simons Theory at Level k via the 3d-3d Correspondence

NASA Astrophysics Data System (ADS)

Dimofte, Tudor

2015-10-01

We use the 3d-3d correspondence together with the DGG construction of theories T n [ M] labelled by 3-manifolds M to define a non-perturbative state-integral model for Chern-Simons theory at any level k, based on ideal triangulations. The resulting partition functions generalize a widely studied k = 1 state-integral, as well as the 3d index, which is k = 0. The Chern-Simons partition functions correspond to partition functions of T n [ M] on squashed lens spaces L( k, 1). At any k, they admit a holomorphic-antiholomorphic factorization, corresponding to the decomposition of L( k, 1) into two solid tori, and the associated holomorphic block decomposition of the partition functions of T n [ M]. A generalization to L( k, p) is also presented. Convergence of the state integrals, for any k, requires triangulations to admit a positive angle structure; we propose that this is also necessary for the DGG gauge theory T n [ M] to flow to a desired IR SCFT.

Magnetic exchange couplings from constrained density functional theory: an efficient approach utilizing analytic derivatives.

PubMed

Phillips, Jordan J; Peralta, Juan E

2011-11-14

We introduce a method for evaluating magnetic exchange couplings based on the constrained density functional theory (C-DFT) approach of Rudra, Wu, and Van Voorhis [J. Chem. Phys. 124, 024103 (2006)]. Our method shares the same physical principles as C-DFT but makes use of the fact that the electronic energy changes quadratically and bilinearly with respect to the constraints in the range of interest. This allows us to use coupled perturbed Kohn-Sham spin density functional theory to determine approximately the corrections to the energy of the different spin configurations and construct a priori the relevant energy-landscapes obtained by constrained spin density functional theory. We assess this methodology in a set of binuclear transition-metal complexes and show that it reproduces very closely the results of C-DFT. This demonstrates a proof-of-concept for this method as a potential tool for studying a number of other molecular phenomena. Additionally, routes to improving upon the limitations of this method are discussed. © 2011 American Institute of Physics

Examining Differential Item Functioning: IRT-Based Detection in the Framework of Confirmatory Factor Analysis

ERIC Educational Resources Information Center

Dimitrov, Dimiter M.

2017-01-01

This article offers an approach to examining differential item functioning (DIF) under its item response theory (IRT) treatment in the framework of confirmatory factor analysis (CFA). The approach is based on integrating IRT- and CFA-based testing of DIF and using bias-corrected bootstrap confidence intervals with a syntax code in Mplus.

Development of bilingual tools to assess functional health patterns.

PubMed

Krozy, R E; McCarthy, N C

1999-01-01

The theory and process of developing bilingual assessment tools based on Gordon's 11 functional health patterns. To facilitate assessing the individual, family, and community in a student clinical practicum in a Spanish-speaking country. Multiple family and community health promotion theories; translation theories, Gordon's Manual of Nursing Diagnosis (1982); translation/back-translation involving Ecuadorian faculty and students; student community assessments; faculty and staff workshops in Ecuador. Bilingual, culturally sensitive health assessment tools facilitate history taking, establish nursing diagnoses and interventions, and promote mutual learning. These outcomes demonstrate potential application to other systems in the international nursing community.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burke, J.V.

The published work on exact penalization is indeed vast. Recently this work has indicated an intimate relationship between exact penalization, Lagrange multipliers, and problem stability or calmness. In the present work we chronicle this development within a simple idealized problem framework, wherein we unify, extend, and refine much of the known theory. In particular, most of the foundations for constrained optimization are developed with the aid of exact penalization techniques. Our approach is highly geometric and is based upon the elementary subdifferential theory for distance functions. It is assumed that the reader is familiar with the theory of convex setsmore » and functions. 54 refs.« less

Gurtin-Murdoch surface elasticity theory revisit: An orbital-free density functional theory perspective

NASA Astrophysics Data System (ADS)

Zhu, Yichao; Wei, Yihai; Guo, Xu

2017-12-01

In the present paper, the well-established Gurtin-Murdoch theory of surface elasticity (Gurtin and Murdoch, 1975, 1978) is revisited from an orbital-free density functional theory (OFDFT) perspective by taking the boundary layer into consideration. Our analysis indicates that firstly, the quantities introduced in the Gurtin-Murdoch theory of surface elasticity can all find their explicit expressions in the derived OFDFT-based theoretical model. Secondly, the derived expression for surface energy density captures a competition between the surface normal derivatives of the electron density and the electrostatic potential, which well rationalises the onset of signed elastic constants that are observed both experimentally and computationally. Thirdly, the established model naturally yields an inversely linear relationship between the materials surface stiffness and its size, which conforms to relevant findings in literature. Since the proposed OFDFT-based model is established under arbitrarily imposed boundary condition of electron density, electrostatic potential and external load, it also has the potential of being used to investigate the electro-mechanical behaviour of nanoscale materials manifesting surface effect.

Fundamental measure theory for the inhomogeneous hard-sphere system based on Santos' consistent free energy.

PubMed

Hansen-Goos, Hendrik; Mortazavifar, Mostafa; Oettel, Martin; Roth, Roland

2015-05-01

Based on Santos' general solution for the scaled-particle differential equation [Phys. Rev. E 86, 040102(R) (2012)], we construct a free-energy functional for the hard-sphere system. The functional is obtained by a suitable generalization and extension of the set of scaled-particle variables using the weighted densities from Rosenfeld's fundamental measure theory for the hard-sphere mixture [Phys. Rev. Lett. 63, 980 (1989)]. While our general result applies to the hard-sphere mixture, we specify remaining degrees of freedom by requiring the functional to comply with known properties of the pure hard-sphere system. Both for mixtures and pure systems, the functional can be systematically extended following the lines of our derivation. We test the resulting functionals regarding their behavior upon dimensional reduction of the fluid as well as their ability to accurately describe the hard-sphere crystal and the liquid-solid transition.

On Dreams and Motivation: Comparison of Freud's and Hobson's Views.

PubMed

Boag, Simon

2016-01-01

The merits of Freudian dream theory continue to be debated and both supporters and critics appeal to empirical evidence to support their respective positions. What receives much less attention is the theoretical coherency of either Freudian dream theory or alternative perspectives. This paper examines Freudian dream theory and J. Allan Hobson's alternative position by addressing the role of motivation in dreams. This paper first discusses motivation in Freudian theory and its relation to dreams and disguise-censorship. The role of motivation in Hobson's theory is then considered. Hobson's claim that dream plot and content selection is random and based on design error and functional imbalance is then discussed in relation to the protoconsciousness theory proposal that dreams serve an adaptive function. While there are apparent inconsistencies in Hobson's position, his appeal to emotions and instincts provides a preliminary platform for understanding the role of motivation in dreams that is consonant with the Freudian position.

Excited State Charge Transfer reaction with dual emission from 5-(4-dimethylamino-phenyl)-penta-2,4-dienenitrile: Spectral measurement and theoretical density functional theory calculation

NASA Astrophysics Data System (ADS)

Jana, Sankar; Dalapati, Sasanka; Ghosh, Shalini; Kar, Samiran; Guchhait, Nikhil

2011-07-01

The excited state intramolecular charge transfer process in donor-chromophore-acceptor system 5-(4-dimethylamino-phenyl)-penta-2,4-dienenitrile (DMAPPDN) has been investigated by steady state absorption and emission spectroscopy in combination with Density Functional Theory (DFT) calculations. This flexible donor acceptor molecule DMAPPDN shows dual fluorescence corresponding to emission from locally excited and charge transfer state in polar solvent. Large solvatochromic emission shift, effect of variation of pH and HOMO-LUMO molecular orbital pictures support excited state intramolecular charge transfer process. The experimental findings have been correlated with the calculated structure and potential energy surfaces based on the Twisted Intramolecular Charge Transfer (TICT) model obtained at DFT level using B3LYP functional and 6-31+G( d, p) basis set. The theoretical potential energy surfaces for the excited states have been generated in vacuo and acetonitrile solvent using Time Dependent Density Functional Theory (TDDFT) and Time Dependent Density Functional Theory Polarized Continuum Model (TDDFT-PCM) method, respectively. All the theoretical results show well agreement with the experimental observations.

Multicomponent density functional theory embedding formulation.

PubMed

Culpitt, Tanner; Brorsen, Kurt R; Pak, Michael V; Hammes-Schiffer, Sharon

2016-07-28

Multicomponent density functional theory (DFT) methods have been developed to treat two types of particles, such as electrons and nuclei, quantum mechanically at the same level. In the nuclear-electronic orbital (NEO) approach, all electrons and select nuclei, typically key protons, are treated quantum mechanically. For multicomponent DFT methods developed within the NEO framework, electron-proton correlation functionals based on explicitly correlated wavefunctions have been designed and used in conjunction with well-established electronic exchange-correlation functionals. Herein a general theory for multicomponent embedded DFT is developed to enable the accurate treatment of larger systems. In the general theory, the total electronic density is separated into two subsystem densities, denoted as regular and special, and different electron-proton correlation functionals are used for these two electronic densities. In the specific implementation, the special electron density is defined in terms of spatially localized Kohn-Sham electronic orbitals, and electron-proton correlation is included only for the special electron density. The electron-proton correlation functional depends on only the special electron density and the proton density, whereas the electronic exchange-correlation functional depends on the total electronic density. This scheme includes the essential electron-proton correlation, which is a relatively local effect, as well as the electronic exchange-correlation for the entire system. This multicomponent DFT-in-DFT embedding theory is applied to the HCN and FHF(-) molecules in conjunction with two different electron-proton correlation functionals and three different electronic exchange-correlation functionals. The results illustrate that this approach provides qualitatively accurate nuclear densities in a computationally tractable manner. The general theory is also easily extended to other types of partitioning schemes for multicomponent systems.

Multicomponent density functional theory embedding formulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Culpitt, Tanner; Brorsen, Kurt R.; Pak, Michael V.

Multicomponent density functional theory (DFT) methods have been developed to treat two types of particles, such as electrons and nuclei, quantum mechanically at the same level. In the nuclear-electronic orbital (NEO) approach, all electrons and select nuclei, typically key protons, are treated quantum mechanically. For multicomponent DFT methods developed within the NEO framework, electron-proton correlation functionals based on explicitly correlated wavefunctions have been designed and used in conjunction with well-established electronic exchange-correlation functionals. Herein a general theory for multicomponent embedded DFT is developed to enable the accurate treatment of larger systems. In the general theory, the total electronic density ismore » separated into two subsystem densities, denoted as regular and special, and different electron-proton correlation functionals are used for these two electronic densities. In the specific implementation, the special electron density is defined in terms of spatially localized Kohn-Sham electronic orbitals, and electron-proton correlation is included only for the special electron density. The electron-proton correlation functional depends on only the special electron density and the proton density, whereas the electronic exchange-correlation functional depends on the total electronic density. This scheme includes the essential electron-proton correlation, which is a relatively local effect, as well as the electronic exchange-correlation for the entire system. This multicomponent DFT-in-DFT embedding theory is applied to the HCN and FHF{sup −} molecules in conjunction with two different electron-proton correlation functionals and three different electronic exchange-correlation functionals. The results illustrate that this approach provides qualitatively accurate nuclear densities in a computationally tractable manner. The general theory is also easily extended to other types of partitioning schemes for multicomponent systems.« less

Predicting Multicomponent Adsorption Isotherms in Open-Metal Site Materials Using Force Field Calculations Based on Energy Decomposed Density Functional Theory.

PubMed

Heinen, Jurn; Burtch, Nicholas C; Walton, Krista S; Fonseca Guerra, Célia; Dubbeldam, David

2016-12-12

For the design of adsorptive-separation units, knowledge is required of the multicomponent adsorption behavior. Ideal adsorbed solution theory (IAST) breaks down for olefin adsorption in open-metal site (OMS) materials due to non-ideal donor-acceptor interactions. Using a density-function-theory-based energy decomposition scheme, we develop a physically justifiable classical force field that incorporates the missing orbital interactions using an appropriate functional form. Our first-principles derived force field shows greatly improved quantitative agreement with the inflection points, initial uptake, saturation capacity, and enthalpies of adsorption obtained from our in-house adsorption experiments. While IAST fails to make accurate predictions, our improved force field model is able to correctly predict the multicomponent behavior. Our approach is also transferable to other OMS structures, allowing the accurate study of their separation performances for olefins/paraffins and further mixtures involving complex donor-acceptor interactions. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Construction of Higher Education Entrepreneur Services Network System a Research Based on Ecological Systems Theory

NASA Astrophysics Data System (ADS)

Xue, Jingxin

The article aims to completely, systematically and objectively analyze the current situation of Entrepreneurship Education in China with Ecological Systems Theory. From this perspective, the author discusses the structure, function and its basic features of higher education entrepreneur services network system, and puts forward the opinion that every entrepreneurship organization in higher education institution does not limited to only one platform. Different functional supporting platforms should be combined closed through composite functional organization to form an integrated network system, in which each unit would impels others' development.

Theory of time-resolved photoelectron imaging. Comparison of a density functional with a time-dependent density functional approach

NASA Astrophysics Data System (ADS)

Suzuki, Yoshi-ichi; Seideman, Tamar; Stener, Mauro

2004-01-01

Time-resolved photoelectron differential cross sections are computed within a quantum dynamical theory that combines a formally exact solution of the nuclear dynamics with density functional theory (DFT)-based approximations of the electronic dynamics. Various observables of time-resolved photoelectron imaging techniques are computed at the Kohn-Sham and at the time-dependent DFT levels. Comparison of the results serves to assess the reliability of the former method and hence its usefulness as an economic approach for time-domain photoelectron cross section calculations, that is applicable to complex polyatomic systems. Analysis of the matrix elements that contain the electronic dynamics provides insight into a previously unexplored aspect of femtosecond-resolved photoelectron imaging.

Density functional and theoretical study of the temperature and pressure dependency of the plasmon energy of solids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Attarian Shandiz, M., E-mail: mohammad.attarianshandiz@mail.mcgill.ca; Gauvin, R.

The temperature and pressure dependency of the volume plasmon energy of solids was investigated by density functional theory calculations. The volume change of crystal is the major factor responsible for the variation of valence electron density and plasmon energy in the free electron model. Hence, to introduce the effect of temperature and pressure for the density functional theory calculations of plasmon energy, the temperature and pressure dependency of lattice parameter was used. Also, by combination of the free electron model and the equation of state based on the pseudo-spinodal approach, the temperature and pressure dependency of the plasmon energy wasmore » modeled. The suggested model is in good agreement with the results of density functional theory calculations and available experimental data for elements with the free electron behavior.« less

A prototype of behavior selection mechanism based on emotion

NASA Astrophysics Data System (ADS)

Zhang, Guofeng; Li, Zushu

2007-12-01

In bionic methodology rather than in design methodology more familiar with, summarizing the psychological researches of emotion, we propose the biologic mechanism of emotion, emotion selection role in creature evolution and a anima framework including emotion similar to the classical control structure; and consulting Prospect Theory, build an Emotion Characteristic Functions(ECF) that computer emotion; two more emotion theories are added to them that higher emotion is preferred and middle emotion makes brain run more efficiently, emotional behavior mechanism comes into being. A simulation of proposed mechanism are designed and carried out on Alife Swarm software platform. In this simulation, a virtual grassland ecosystem is achieved where there are two kinds of artificial animals: herbivore and preyer. These artificial animals execute four types of behavior: wandering, escaping, finding food, finding sex partner in their lives. According the theories of animal ethnology, escaping from preyer is prior to other behaviors for its existence, finding food is secondly important behavior, rating is third one and wandering is last behavior. In keeping this behavior order, based on our behavior characteristic function theory, the specific functions of emotion computing are built of artificial autonomous animals. The result of simulation confirms the behavior selection mechanism.

Multiconfigurational short-range density-functional theory for open-shell systems

NASA Astrophysics Data System (ADS)

Hedegârd, Erik Donovan; Toulouse, Julien; Jensen, Hans Jørgen Aagaard

2018-06-01

Many chemical systems cannot be described by quantum chemistry methods based on a single-reference wave function. Accurate predictions of energetic and spectroscopic properties require a delicate balance between describing the most important configurations (static correlation) and obtaining dynamical correlation efficiently. The former is most naturally done through a multiconfigurational (MC) wave function, whereas the latter can be done by, e.g., perturbation theory. We have employed a different strategy, namely, a hybrid between multiconfigurational wave functions and density-functional theory (DFT) based on range separation. The method is denoted by MC short-range DFT (MC-srDFT) and is more efficient than perturbative approaches as it capitalizes on the efficient treatment of the (short-range) dynamical correlation by DFT approximations. In turn, the method also improves DFT with standard approximations through the ability of multiconfigurational wave functions to recover large parts of the static correlation. Until now, our implementation was restricted to closed-shell systems, and to lift this restriction, we present here the generalization of MC-srDFT to open-shell cases. The additional terms required to treat open-shell systems are derived and implemented in the DALTON program. This new method for open-shell systems is illustrated on dioxygen and [Fe(H2O)6]3+.

Reading the Freudian theory of sexual drives from a functional neuroimaging perspective

PubMed Central

Stoléru, Serge

2014-01-01

One of the essential tasks of neuropsychoanalysis is to investigate the neural correlates of sexual drives. Here, we consider the four defining characteristics of sexual drives as delineated by Freud: their pressure, aim, object, and source. We systematically examine the relations between these characteristics and the four-component neurophenomenological model that we have proposed based on functional neuroimaging studies, which comprises a cognitive, a motivational, an emotional and an autonomic/neuroendocrine component. Functional neuroimaging studies of sexual arousal (SA) have thrown a new light on the four fundamental characteristics of sexual drives by identifying their potential neural correlates. While these studies are essentially consistent with the Freudian model of drives, the main difference emerging between the functional neuroimaging perspective on sexual drives and the Freudian theory relates to the source of drives. From a functional neuroimaging perspective, sources of sexual drives, conceived by psychoanalysis as processes of excitation occurring in a peripheral organ, do not seem, at least in adult subjects, to be an essential part of the determinants of SA. It is rather the central processing of visual or genital stimuli that gives to these stimuli their sexually arousing and sexually pleasurable character. Finally, based on functional neuroimaging results, some possible improvements to the psychoanalytic theory of sexual drives are suggested. PMID:24672467

Evidence for an expectancy-based theory of avoidance behaviour.

PubMed

Declercq, Mieke; De Houwer, Jan; Baeyens, Frank

2008-01-01

In most studies on avoidance learning, participants receive an aversive unconditioned stimulus after a warning signal is presented, unless the participant performs a particular response. Lovibond (2006) recently proposed a cognitive theory of avoidance learning, according to which avoidance behaviour is a function of both Pavlovian and instrumental conditioning. In line with this theory, we found that avoidance behaviour was based on an integration of acquired knowledge about, on the one hand, the relation between stimuli and, on the other hand, the relation between behaviour and stimuli.

Functional thermo-dynamics: a generalization of dynamic density functional theory to non-isothermal situations.

PubMed

Anero, Jesús G; Español, Pep; Tarazona, Pedro

2013-07-21

We present a generalization of Density Functional Theory (DFT) to non-equilibrium non-isothermal situations. By using the original approach set forth by Gibbs in his consideration of Macroscopic Thermodynamics (MT), we consider a Functional Thermo-Dynamics (FTD) description based on the density field and the energy density field. A crucial ingredient of the theory is an entropy functional, which is a concave functional. Therefore, there is a one to one connection between the density and energy fields with the conjugate thermodynamic fields. The connection between the three levels of description (MT, DFT, FTD) is clarified through a bridge theorem that relates the entropy of different levels of description and that constitutes a generalization of Mermin's theorem to arbitrary levels of description whose relevant variables are connected linearly. Although the FTD level of description does not provide any new information about averages and correlations at equilibrium, it is a crucial ingredient for the dynamics in non-equilibrium states. We obtain with the technique of projection operators the set of dynamic equations that describe the evolution of the density and energy density fields from an initial non-equilibrium state towards equilibrium. These equations generalize time dependent density functional theory to non-isothermal situations. We also present an explicit model for the entropy functional for hard spheres.

(Small) Resonant non-Gaussianities: Signatures of a Discrete Shift Symmetry in the Effective Field Theory of Inflation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Behbahani, Siavosh R.; /SLAC /Stanford U., Phys. Dept. /Boston U.; Dymarsky, Anatoly

2012-06-06

We apply the Effective Field Theory of Inflation to study the case where the continuous shift symmetry of the Goldstone boson {pi} is softly broken to a discrete subgroup. This case includes and generalizes recently proposed String Theory inspired models of Inflation based on Axion Monodromy. The models we study have the property that the 2-point function oscillates as a function of the wavenumber, leading to oscillations in the CMB power spectrum. The non-linear realization of time diffeomorphisms induces some self-interactions for the Goldstone boson that lead to a peculiar non-Gaussianity whose shape oscillates as a function of the wavenumber.more » We find that in the regime of validity of the effective theory, the oscillatory signal contained in the n-point correlation functions, with n > 2, is smaller than the one contained in the 2-point function, implying that the signature of oscillations, if ever detected, will be easier to find first in the 2-point function, and only then in the higher order correlation functions. Still the signal contained in higher-order correlation functions, that we study here in generality, could be detected at a subleading level, providing a very compelling consistency check for an approximate discrete shift symmetry being realized during inflation.« less

[Research on the Clinical Alarm Management Mechanism Based on Closed-loop Control Theory].

PubMed

Lin, Zhongkuan; Zheng, Kun; Shen, Yunming; Wu, Yunyun

2018-05-30

This paper proposes a clinical alarm management system based on the theory of the closed loop control. The alarm management mechanism can be divided into the expected standard, improving execution rule, rule execution, medical devices with alarm functions, results analysis strategy and the output link. And, we make relevant application and discussion. Results showed that the mechanism can be operable and effective.

Alternative probability theories for cognitive psychology.

PubMed

Narens, Louis

2014-01-01

Various proposals for generalizing event spaces for probability functions have been put forth in the mathematical, scientific, and philosophic literatures. In cognitive psychology such generalizations are used for explaining puzzling results in decision theory and for modeling the influence of context effects. This commentary discusses proposals for generalizing probability theory to event spaces that are not necessarily boolean algebras. Two prominent examples are quantum probability theory, which is based on the set of closed subspaces of a Hilbert space, and topological probability theory, which is based on the set of open sets of a topology. Both have been applied to a variety of cognitive situations. This commentary focuses on how event space properties can influence probability concepts and impact cognitive modeling. Copyright © 2013 Cognitive Science Society, Inc.

A world apart? Bridging the gap between theory and applied social gerontology.

PubMed

Hendricks, Jon; Applebaum, Robert; Kunkel, Suzanne

2010-06-01

This article is based on the premise that there is inadequate attention to the link between theory and applied research in social gerontology. The article contends that applied research studies do not often or effectively employ a theoretical framework and that theory-based articles, including theory-based research, are not often focused on questions related to applied social gerontology. We explore the extent to which theory and applied research could reasonably be expected to overlap, present data from an analysis of 5 years of articles in three leading journals, and posit some possible explanations for the current divide between theory and applied social gerontology research. We argue that the divide weakens research and inhibits the functions that theory can play in helping to organize the accumulation of knowledge, and we offer some suggestions about how the field can address this challenge, including changes to the journal review and submission process to reflect the importance of the link between theory and/or conceptual models and research, and an expansion of professional conference opportunities to link research and practice.

Stringy horizons and generalized FZZ duality in perturbation theory

NASA Astrophysics Data System (ADS)

Giribet, Gaston

2017-02-01

We study scattering amplitudes in two-dimensional string theory on a black hole bakground. We start with a simple derivation of the Fateev-Zamolodchikov-Zamolodchikov (FZZ) duality, which associates correlation functions of the sine-Liouville integrable model on the Riemann sphere to tree-level string amplitudes on the Euclidean two-dimensional black hole. This derivation of FZZ duality is based on perturbation theory, and it relies on a trick originally due to Fateev, which involves duality relations between different Selberg type integrals. This enables us to rewrite the correlation functions of sine-Liouville theory in terms of a special set of correlators in the gauged Wess-Zumino-Witten (WZW) theory, and use this to perform further consistency checks of the recently conjectured Generalized FZZ (GFZZ) duality. In particular, we prove that n-point correlation functions in sine-Liouville theory involving n - 2 winding modes actually coincide with the correlation functions in the SL(2,R)/U(1) gauged WZW model that include n - 2 oscillator operators of the type described by Giveon, Itzhaki and Kutasov in reference [1]. This proves the GFZZ duality for the case of tree level maximally winding violating n-point amplitudes with arbitrary n. We also comment on the connection between GFZZ and other marginal deformations previously considered in the literature.

Utility function under decision theory: A construction arbitration application

NASA Astrophysics Data System (ADS)

Alozn, Ahmad E.; Galadari, Abdulla

2017-08-01

While a wide range of dispute resolution mechanisms exist, practitioners favor legally binding ones such as litigation and arbitration. Since initiating a litigation or arbitration case against a business partner may dissolve the business relationship between them, predicting the arbitrator's decision becomes valuable to the arbitrating parties. This paper proposes a construction-specific utility framework for the arbitrating party through decision theory, and based on expected utility theory. The proposed framework preserves the industry practicality and most importantly, considers direct short-term factors and indirect long-term factors as well. It is suggested that the arbitrating parties' utility functions could be then used to identify equilibrium points among them when interact via game theory principles, which would serve the purpose of predicting the arbitration outcome.

Thermo-Elastic Triangular Sandwich Element for the Complete Stress Field Based on a Single-Layer Theory

NASA Technical Reports Server (NTRS)

Das, M.; Barut, A.; Madenci, E.; Ambur, D. R.

2004-01-01

This study presents a new triangular finite element for modeling thick sandwich panels, subjected to thermo-mechanical loading, based on a {3,2}-order single-layer plate theory. A hybrid energy functional is employed in the derivation of the element because of a C interelement continuity requirement. The single-layer theory is based on five weighted-average field variables arising from the cubic and quadratic representations of the in-plane and transverse displacement fields, respectively. The variations of temperature and distributed loading acting on the top and bottom surfaces are non-uniform. The temperature varies linearly through the thickness.

Beta-decay rate and beta-delayed neutron emission probability of improved gross theory

NASA Astrophysics Data System (ADS)

Koura, Hiroyuki

2014-09-01

A theoretical study has been carried out on beta-decay rate and beta-delayed neutron emission probability. The gross theory of the beta decay is based on an idea of the sum rule of the beta-decay strength function, and has succeeded in describing beta-decay half-lives of nuclei overall nuclear mass region. The gross theory includes not only the allowed transition as the Fermi and the Gamow-Teller, but also the first-forbidden transition. In this work, some improvements are introduced as the nuclear shell correction on nuclear level densities and the nuclear deformation for nuclear strength functions, those effects were not included in the original gross theory. The shell energy and the nuclear deformation for unmeasured nuclei are adopted from the KTUY nuclear mass formula, which is based on the spherical-basis method. Considering the properties of the integrated Fermi function, we can roughly categorized energy region of excited-state of a daughter nucleus into three regions: a highly-excited energy region, which fully affect a delayed neutron probability, a middle energy region, which is estimated to contribute the decay heat, and a region neighboring the ground-state, which determines the beta-decay rate. Some results will be given in the presentation. A theoretical study has been carried out on beta-decay rate and beta-delayed neutron emission probability. The gross theory of the beta decay is based on an idea of the sum rule of the beta-decay strength function, and has succeeded in describing beta-decay half-lives of nuclei overall nuclear mass region. The gross theory includes not only the allowed transition as the Fermi and the Gamow-Teller, but also the first-forbidden transition. In this work, some improvements are introduced as the nuclear shell correction on nuclear level densities and the nuclear deformation for nuclear strength functions, those effects were not included in the original gross theory. The shell energy and the nuclear deformation for unmeasured nuclei are adopted from the KTUY nuclear mass formula, which is based on the spherical-basis method. Considering the properties of the integrated Fermi function, we can roughly categorized energy region of excited-state of a daughter nucleus into three regions: a highly-excited energy region, which fully affect a delayed neutron probability, a middle energy region, which is estimated to contribute the decay heat, and a region neighboring the ground-state, which determines the beta-decay rate. Some results will be given in the presentation. This work is a result of Comprehensive study of delayed-neutron yields for accurate evaluation of kinetics of high-burn up reactors entrusted to Tokyo Institute of Technology by the Ministry of Education, Culture, Sports, Science and Technology of Japan.

Superconformal indices of generalized Argyres-Douglas theories from 2d TQFT

DOE PAGES

Song, Jaewon

2016-02-05

We present superconformal indices of 4d N = 2 class S theories with certain irregular punctures called type I k,N. This class of theories include generalized Argyres-Douglas theories of type (A k-1, A N-1) and more. We conjecture the superconformal indices in certain simplifi ed limits based on the TQFT structure of the class S theories by writing an expression for the wave function corresponding to the puncture I k,N. We write the Schur limit of the wave function when k and N are coprime. When k = 2, we also conjecture a closed-form expression for the Hall-Littlewood index andmore » the Macdonald index for odd N. From the index, we argue that certain short-multiplet which can appear in the OPE of the stress-energy tensor is absent in the (A 1,A 2n) theory. In addition, we discuss the mixed Schur indices for the N = 1 class S theories with irregular punctures.« less

Towards an exact correlated orbital theory for electrons

NASA Astrophysics Data System (ADS)

Bartlett, Rodney J.

2009-12-01

The formal and computational attraction of effective one-particle theories like Hartree-Fock and density functional theory raise the question of how far such approaches can be taken to offer exact results for selected properties of electrons in atoms, molecules, and solids. Some properties can be exactly described within an effective one-particle theory, like principal ionization potentials and electron affinities. This fact can be used to develop equations for a correlated orbital theory (COT) that guarantees a correct one-particle energy spectrum. They are built upon a coupled-cluster based frequency independent self-energy operator presented here, which distinguishes the approach from Dyson theory. The COT also offers an alternative to Kohn-Sham density functional theory (DFT), whose objective is to represent the electronic density exactly as a single determinant, while paying less attention to the energy spectrum. For any estimate of two-electron terms COT offers a litmus test of its accuracy for principal Ip's and Ea's. This feature for approximating the COT equations is illustrated numerically.

Superconformal indices of generalized Argyres-Douglas theories from 2d TQFT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, Jaewon

We present superconformal indices of 4d N = 2 class S theories with certain irregular punctures called type I k,N. This class of theories include generalized Argyres-Douglas theories of type (A k-1, A N-1) and more. We conjecture the superconformal indices in certain simplifi ed limits based on the TQFT structure of the class S theories by writing an expression for the wave function corresponding to the puncture I k,N. We write the Schur limit of the wave function when k and N are coprime. When k = 2, we also conjecture a closed-form expression for the Hall-Littlewood index andmore » the Macdonald index for odd N. From the index, we argue that certain short-multiplet which can appear in the OPE of the stress-energy tensor is absent in the (A 1,A 2n) theory. In addition, we discuss the mixed Schur indices for the N = 1 class S theories with irregular punctures.« less

Generalized-active-space pair-density functional theory: an efficient method to study large, strongly correlated, conjugated systems.

PubMed

Ghosh, Soumen; Cramer, Christopher J; Truhlar, Donald G; Gagliardi, Laura

2017-04-01

Predicting ground- and excited-state properties of open-shell organic molecules by electronic structure theory can be challenging because an accurate treatment has to correctly describe both static and dynamic electron correlation. Strongly correlated systems, i.e. , systems with near-degeneracy correlation effects, are particularly troublesome. Multiconfigurational wave function methods based on an active space are adequate in principle, but it is impractical to capture most of the dynamic correlation in these methods for systems characterized by many active electrons. We recently developed a new method called multiconfiguration pair-density functional theory (MC-PDFT), that combines the advantages of wave function theory and density functional theory to provide a more practical treatment of strongly correlated systems. Here we present calculations of the singlet-triplet gaps in oligoacenes ranging from naphthalene to dodecacene. Calculations were performed for unprecedently large orbitally optimized active spaces of 50 electrons in 50 orbitals, and we test a range of active spaces and active space partitions, including four kinds of frontier orbital partitions. We show that MC-PDFT can predict the singlet-triplet splittings for oligoacenes consistent with the best available and much more expensive methods, and indeed MC-PDFT may constitute the benchmark against which those other models should be compared, given the absence of experimental data.

Adaptive-Wall Wind-Tunnel Investigations

DTIC Science & Technology

1981-02-01

boundary condition for unconfined flow. In this way, theory and experiment are combined to minimize wall interference. The concept of an adaptive wall...should be noted that although shock waves extend to the walls, the exterior-flow calculation was based on subcritical-flow theory . Goodyer’s configuration...and v by aerodynamic probes. Both subsonic and transonic small- disturbance theory were used, as appropriate, to evaluate the functional rela

[Theories of stages of life within the anthropology of romanticism].

PubMed

Schweizer, Pia-Johanna; Schweizer, Stefan

2006-12-01

The essay discusses the importance and prominence of theories about different stages of life in the anthropological and medical discourse of romanticism. This discourse has clearly a stabilising and restaurative function, favouring the age of moderate manhood. The political and social regulative implications of these theories demand a restaurative roll-back. The essay is based on a concept of sociology of knowledge formation.

Final Technical Report for DE-SC0001878 [Theory and Simulation of Defects in Oxide Materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chelikowsky, James R.

2014-04-14

We explored a wide variety of oxide materials and related problems, including materials at the nanoscale and generic problems associated with oxide materials such as the development of more efficient computational tools to examine these materials. We developed and implemented methods to understand the optical and structural properties of oxides. For ground state properties, our work is predominantly based on pseudopotentials and density functional theory (DFT), including new functionals and going beyond the local density approximation (LDA): LDA+U. To study excited state properties (quasiparticle and optical excitations), we use time dependent density functional theory, the GW approach, and GW plusmore » Bethe-Salpeter equation (GW-BSE) methods based on a many-body Green function approaches. Our work focused on the structural, electronic, optical and magnetic properties of defects (such as oxygen vacancies) in hafnium oxide, titanium oxide (both bulk and clusters) and related materials. We calculated the quasiparticle defect states and charge transition levels of oxygen vacancies in monoclinic hafnia. we presented a milestone G0W0 study of two of the crystalline phases of dye-sensitized TiO{sub 2} clusters. We employed hybrid density functional theory to examine the electronic structure of sexithiophene/ZnO interfaces. To identify the possible effect of epitaxial strain on stabilization of the ferromagnetic state of LaCoO{sub 3} (LCO), we compare the total energy of the magnetic and nonmagnetic states of the strained theoretical bulk structure.« less

Photophysical properties of Schiff's bases from 3-(1,3-benzothiazol-2-yl)-2-hydroxy naphthalene-1-carbaldehyde.

PubMed

Satam, Manjaree A; Telore, Rahul D; Sekar, Nagaiyan

2014-11-11

A series of novel Schiff's bases have been synthesized from 3-(1,3-benzothiazol-2-yl)-2-hydroxynaphthalene-1-carbaldehyde. The presence of hydroxyl group ortho to the benzothiazolyl group as well as the imine linkage lead to the occurrence of excited state intramolecular proton transfer process. The computational strategy was used to study the ESIPT process of the synthesized Schiff's bases, which revealed surprisingly that the keto form predominantly exists in the ground state contradicting the ESIPT process. Density functional theory and time dependent density functional theory have been used to investigate the structural parameters and photophysical properties in different solvents of one of the Schiff's bases. The experimental results correlate well with the computed results. All Schiff's bases show good thermal stability. Copyright © 2014 Elsevier B.V. All rights reserved.

Probing the Structure, Stability and Hydrogen Adsorption of Lithium Functionalized Isoreticular MOF-5 (Fe, Cu, Co, Ni and Zn) by Density Functional Theory

PubMed Central

Venkataramanan, Natarajan Sathiyamoorthy; Sahara, Ryoji; Mizuseki, Hiroshi; Kawazoe, Yoshiyuki

2009-01-01

Li adsorption on isoreticular MOFs with metal Fe, Cu, Co, Ni and Zn was studied using density function theory. Li functionalization shows a considerable structural change associated with a volume change in isoreticular MOF-5 except for the Zn metal center. Hydrogen binding energies on Li functionalized MOFs are seen to be in the range of 0.2 eV, which is the desired value for an ideal reversible storage system. This study has clearly shown that Li doping is possible only in Zn-based MOF-5, which would be better candidate to reversibly store hydrogen. PMID:19468328

Lyapounov Functions of Closed Cone Fields: From Conley Theory to Time Functions

NASA Astrophysics Data System (ADS)

Bernard, Patrick; Suhr, Stefan

2018-03-01

We propose a theory "à la Conley" for cone fields using a notion of relaxed orbits based on cone enlargements, in the spirit of space time geometry. We work in the setting of closed (or equivalently semi-continuous) cone fields with singularities. This setting contains (for questions which are parametrization independent such as the existence of Lyapounov functions) the case of continuous vector-fields on manifolds, of differential inclusions, of Lorentzian metrics, and of continuous cone fields. We generalize to this setting the equivalence between stable causality and the existence of temporal functions. We also generalize the equivalence between global hyperbolicity and the existence of a steep temporal function.

A new theory of health promoting schools based on human functioning, school organisation and pedagogic practice.

PubMed

Markham, Wolfgang A; Aveyard, Paul

2003-03-01

This paper outlines a novel explanatory frame for understanding how schools may intervene in order to promote pupils' health. The new theory is synthesised from an Aristotelian interpretation of human functioning and a theory of cultural transmission. In keeping with recent influential theoretical developments, it is proposed that health has its roots in human functioning. It follows from this concept that the promotion of pupils' health is facilitated by the promotion of pupil functioning and the primary mechanisms through which schools promote pupil functioning and, hence, health, are through the influences of school organisation, curriculum development and pedagogic practice on pupil development. According to the new theory, good human functioning is dependent on the realisation of a number of identified essential human capacities and the meeting of identified fundamental human needs. Two essential capacities, the capacity for practical reasoning and the capacity for affiliation with other humans, plan and organise the other essential capacities. The realisation of these two capacities should, it is argued, be the primary focus of health promoting schools. Additionally, health promoting schools should ensure that fundamental human needs concerning non-useful pain and information about the body are met. A number of testable hypotheses are generated from the new theory. Comparisons with existing interpretations of health promoting schools indicate there are similarities in the actions schools should take to promote health. However, the new theory can, uniquely, be used to predict which pupils will enjoy the best health at school and in adulthood. Additionally, according to the new theory, schools do not need designated health education classes or teaching staff with specialist health education roles in order to be health promoting. It is concluded that the new theory may have a number of advantages over existing theories at both the policy and intervention levels.

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.

Basis set construction for molecular electronic structure theory: natural orbital and Gauss-Slater basis for smooth pseudopotentials.

PubMed

Petruzielo, F R; Toulouse, Julien; Umrigar, C J

2011-02-14

A simple yet general method for constructing basis sets for molecular electronic structure calculations is presented. These basis sets consist of atomic natural orbitals from a multiconfigurational self-consistent field calculation supplemented with primitive functions, chosen such that the asymptotics are appropriate for the potential of the system. Primitives are optimized for the homonuclear diatomic molecule to produce a balanced basis set. Two general features that facilitate this basis construction are demonstrated. First, weak coupling exists between the optimal exponents of primitives with different angular momenta. Second, the optimal primitive exponents for a chosen system depend weakly on the particular level of theory employed for optimization. The explicit case considered here is a basis set appropriate for the Burkatzki-Filippi-Dolg pseudopotentials. Since these pseudopotentials are finite at nuclei and have a Coulomb tail, the recently proposed Gauss-Slater functions are the appropriate primitives. Double- and triple-zeta bases are developed for elements hydrogen through argon. These new bases offer significant gains over the corresponding Burkatzki-Filippi-Dolg bases at various levels of theory. Using a Gaussian expansion of the basis functions, these bases can be employed in any electronic structure method. Quantum Monte Carlo provides an added benefit: expansions are unnecessary since the integrals are evaluated numerically.

Model-Based Reinforcement Learning under Concurrent Schedules of Reinforcement in Rodents

ERIC Educational Resources Information Center

Huh, Namjung; Jo, Suhyun; Kim, Hoseok; Sul, Jung Hoon; Jung, Min Whan

2009-01-01

Reinforcement learning theories postulate that actions are chosen to maximize a long-term sum of positive outcomes based on value functions, which are subjective estimates of future rewards. In simple reinforcement learning algorithms, value functions are updated only by trial-and-error, whereas they are updated according to the decision-maker's…

Nonorthogonal orbital based N-body reduced density matrices and their applications to valence bond theory. I. Hamiltonian matrix elements between internally contracted excited valence bond wave functions

NASA Astrophysics Data System (ADS)

Chen, Zhenhua; Chen, Xun; Wu, Wei

2013-04-01

In this series, the n-body reduced density matrix (n-RDM) approach for nonorthogonal orbitals and their applications to ab initio valence bond (VB) methods are presented. As the first paper of this series, Hamiltonian matrix elements between internally contracted VB wave functions are explicitly provided by means of nonorthogonal orbital based RDM approach. To this end, a more generalized Wick's theorem, called enhanced Wick's theorem, is presented both in arithmetical and in graphical forms, by which the deduction of expressions for the matrix elements between internally contracted VB wave functions is dramatically simplified, and the matrix elements are finally expressed in terms of tensor contractions of electronic integrals and n-RDMs of the reference VB self-consistent field wave function. A string-based algorithm is developed for the purpose of evaluating n-RDMs in an efficient way. Using the techniques presented in this paper, one is able to develop new methods and efficient algorithms for nonorthogonal orbital based many-electron theory much easier than by use of the first quantized formulism.

Rational Density Functional Selection Using Game Theory.

PubMed

McAnanama-Brereton, Suzanne; Waller, Mark P

2018-01-22

Theoretical chemistry has a paradox of choice due to the availability of a myriad of density functionals and basis sets. Traditionally, a particular density functional is chosen on the basis of the level of user expertise (i.e., subjective experiences). Herein we circumvent the user-centric selection procedure by describing a novel approach for objectively selecting a particular functional for a given application. We achieve this by employing game theory to identify optimal functional/basis set combinations. A three-player (accuracy, complexity, and similarity) game is devised, through which Nash equilibrium solutions can be obtained. This approach has the advantage that results can be systematically improved by enlarging the underlying knowledge base, and the deterministic selection procedure mathematically justifies the density functional and basis set selections.

Computational studies of molecular charge transfer complexes of heterocyclic 4-methylepyridine-2-azomethine-p-benzene derivatives with picric acid and m-dinitrobenzene.

PubMed

Al-Harbi, L M; El-Mossalamy, E H; Obaid, A Y; Al-Jedaani, A H

2014-01-01

Charge transfer complexes of substituted aryl Schiff bases as donors with picric acid and m-dinitrobenzene as acceptors were investigated by using computational analysis calculated by Configuration Interaction Singles Hartree-Fock (CIS-HF) at standard 6-31G∗ basis set and Time-Dependent Density-Functional Theory (TD-DFT) levels of theory at standard 6-31G∗∗ basis set, infrared spectra, visible and nuclear magnetic resonance spectra are investigated. The optimized geometries and vibrational frequencies were evaluated. The energy and oscillator strength were calculated by Configuration Interaction Singles Hartree-Fock method (CIS-HF) and the Time-Dependent Density-Functional Theory (TD-DFT) results. Electronic properties, such as HOMO and LUMO energies and band gaps of CTCs set, were studied by the Time-Dependent density functional theory with Becke-Lee-Young-Parr (B3LYP) composite exchange correlation functional and by Configuration Interaction Singles Hartree-Fock method (CIS-HF). The ionization potential Ip and electron affinity EA were calculated by PM3, HF and DFT methods. The columbic force was calculated theoretically by using (CIS-HF and TD-DFT) methods. This study confirms that the theoretical calculation of vibrational frequencies for (aryl Schiff bases--(m-dinitrobenzene and picric acid)) complexes are quite useful for the vibrational assignment and for predicting new vibrational frequencies. Copyright © 2013 Elsevier B.V. All rights reserved.

The charger transfer electronic coupling in diabatic perspective: A multi-state density functional theory study

NASA Astrophysics Data System (ADS)

Guo, Xinwei; Qu, Zexing; Gao, Jiali

2018-01-01

The multi-state density functional theory (MSDFT) provides a convenient way to estimate electronic coupling of charge transfer processes based on a diabatic representation. Its performance has been benchmarked against the HAB11 database with a mean unsigned error (MUE) of 17 meV between MSDFT and ab initio methods. The small difference may be attributed to different representations, diabatic from MSDFT and adiabatic from ab initio calculations. In this discussion, we conclude that MSDFT provides a general and efficient way to estimate the electronic coupling for charge-transfer rate calculations based on the Marcus-Hush model.

Extended Importance Sampling for Reliability Analysis under Evidence Theory

NASA Astrophysics Data System (ADS)

Yuan, X. K.; Chen, B.; Zhang, B. Q.

2018-05-01

In early engineering practice, the lack of data and information makes uncertainty difficult to deal with. However, evidence theory has been proposed to handle uncertainty with limited information as an alternative way to traditional probability theory. In this contribution, a simulation-based approach, called ‘Extended importance sampling’, is proposed based on evidence theory to handle problems with epistemic uncertainty. The proposed approach stems from the traditional importance sampling for reliability analysis under probability theory, and is developed to handle the problem with epistemic uncertainty. It first introduces a nominal instrumental probability density function (PDF) for every epistemic uncertainty variable, and thus an ‘equivalent’ reliability problem under probability theory is obtained. Then the samples of these variables are generated in a way of importance sampling. Based on these samples, the plausibility and belief (upper and lower bounds of probability) can be estimated. It is more efficient than direct Monte Carlo simulation. Numerical and engineering examples are given to illustrate the efficiency and feasible of the proposed approach.

Random matrix theory for analyzing the brain functional network in attention deficit hyperactivity disorder

NASA Astrophysics Data System (ADS)

Wang, Rong; Wang, Li; Yang, Yong; Li, Jiajia; Wu, Ying; Lin, Pan

2016-11-01

Attention deficit hyperactivity disorder (ADHD) is the most common childhood neuropsychiatric disorder and affects approximately 6 -7 % of children worldwide. Here, we investigate the statistical properties of undirected and directed brain functional networks in ADHD patients based on random matrix theory (RMT), in which the undirected functional connectivity is constructed based on correlation coefficient and the directed functional connectivity is measured based on cross-correlation coefficient and mutual information. We first analyze the functional connectivity and the eigenvalues of the brain functional network. We find that ADHD patients have increased undirected functional connectivity, reflecting a higher degree of linear dependence between regions, and increased directed functional connectivity, indicating stronger causality and more transmission of information among brain regions. More importantly, we explore the randomness of the undirected and directed functional networks using RMT. We find that for ADHD patients, the undirected functional network is more orderly than that for normal subjects, which indicates an abnormal increase in undirected functional connectivity. In addition, we find that the directed functional networks are more random, which reveals greater disorder in causality and more chaotic information flow among brain regions in ADHD patients. Our results not only further confirm the efficacy of RMT in characterizing the intrinsic properties of brain functional networks but also provide insights into the possibilities RMT offers for improving clinical diagnoses and treatment evaluations for ADHD patients.

Differential item functioning magnitude and impact measures from item response theory models.

PubMed

Kleinman, Marjorie; Teresi, Jeanne A

2016-01-01

Measures of magnitude and impact of differential item functioning (DIF) at the item and scale level, respectively are presented and reviewed in this paper. Most measures are based on item response theory models. Magnitude refers to item level effect sizes, whereas impact refers to differences between groups at the scale score level. Reviewed are magnitude measures based on group differences in the expected item scores and impact measures based on differences in the expected scale scores. The similarities among these indices are demonstrated. Various software packages are described that provide magnitude and impact measures, and new software presented that computes all of the available statistics conveniently in one program with explanations of their relationships to one another.

REMOTE LAND MINE(FIELD) DETECTION. An Overview of Techniques (DETECTIE VAN LANDMIJNEN EN MIJNENVELDEN OP AFSTAND. Een Overzicht van de technieken),

DTIC Science & Technology

1994-09-01

titel DETECTIE VAN LANDMIJNEN EN MIJNENVELDEN OP AFSTAND, een overzicht van de technieken auteur (s) Drs. J.S. Groot, Ir. Y.H.L. Janssen datum september...functions based on set theory . The fundamental theory is developed in the sixties. This theory was applicable to binary images (black-and-white images...held at TNO-FEL. Various subjects related to fusion techniques: Dempster Shafer theory , Bayesian inference, Kalman filtering, fuzzy logic. [A15], [B4

Morse homotopy and Chern-Simons perturbation theory

NASA Astrophysics Data System (ADS)

Fukaya, Kenji

1996-11-01

We define and invariant of a three manifold equipped with a flat bundle with vanishing homology. The construction is based on Morse theory using several Morse functions simultaneously and is regarded as a higher loop analogue of various product operations in algebraic topology. There is a heuristic argument that this invariant is related to perturbative Chern-Simons Gauge theory by Axelrod-Singer, etc. There is also a theorem which gives a relation of the construction to open string theory on the cotangent bundle.

Universal calculational recipe for solvent-mediated potential: based on a combination of integral equation theory and density functional theory

NASA Astrophysics Data System (ADS)

Zhou, Shiqi

2004-07-01

A universal formalism, which enables calculation of solvent-mediated potential (SMP) between two equal or non-equal solute particles with any shape immersed in solvent reservior consisting of atomic particle and/or polymer chain or their mixture, is proposed by importing a density functional theory externally into OZ equation systems. Only if size asymmetry of the solvent bath components is moderate, the present formalism can calculate the SMP in any complex fluids at the present development stage of statistical mechanics, and therefore avoids all of limitations of previous approaches for SMP. Preliminary calculation indicates the reliability of the present formalism.

Nekrasov and Argyres-Douglas theories in spherical Hecke algebra representation

NASA Astrophysics Data System (ADS)

Rim, Chaiho; Zhang, Hong

2017-06-01

AGT conjecture connects Nekrasov instanton partition function of 4D quiver gauge theory with 2D Liouville conformal blocks. We re-investigate this connection using the central extension of spherical Hecke algebra in q-coordinate representation, q being the instanton expansion parameter. Based on AFLT basis together with intertwiners we construct gauge conformal state and demonstrate its equivalence to the Liouville conformal state, with careful attention to the proper scaling behavior of the state. Using the colliding limit of regular states, we obtain the formal expression of irregular conformal states corresponding to Argyres-Douglas theory, which involves summation of functions over Young diagrams.

TRIZ theory in NEA photocathode preparation system

NASA Astrophysics Data System (ADS)

Qiao, Jianliang; Huang, Dayong; Li, Xiangjiang; Gao, Youtang

2016-09-01

The solutions to the engineering problems were provided according to the innovation principle based on the theory of TRIZ. The ultra high vacuum test and evaluation system for the preparation of negative electron affinity (NEA) photocathode has the characteristics of complex structure and powerful functions. Segmentation principle, advance function principle, curved surface principle, dynamic characteristics principle and nested principle adopted by the design of ultra high vacuum test and evaluation system for cathode preparation were analyzed. The applications of the physical contradiction and the substance-field analysis method of the theory of TRIZ in the cathode preparation ultra high vacuum test and evaluation system were discussed.

Formal optimization of hovering performance using free wake lifting surface theory

NASA Technical Reports Server (NTRS)

Chung, S. Y.

1986-01-01

Free wake techniques for performance prediction and optimization of hovering rotor are discussed. The influence functions due to vortex ring, vortex cylinder, and source or vortex sheets are presented. The vortex core sizes of rotor wake vortices are calculated and their importance is discussed. Lifting body theory for finite thickness body is developed for pressure calculation, and hence performance prediction of hovering rotors. Numerical optimization technique based on free wake lifting line theory is presented and discussed. It is demonstrated that formal optimization can be used with the implicit and nonlinear objective or cost function such as the performance of hovering rotors as used in this report.

On the multiple zeros of a real analytic function with applications to the averaging theory of differential equations

NASA Astrophysics Data System (ADS)

García, Isaac A.; Llibre, Jaume; Maza, Susanna

2018-06-01

In this work we consider real analytic functions , where , Ω is a bounded open subset of , is an interval containing the origin, are parameters, and ε is a small parameter. We study the branching of the zero-set of at multiple points when the parameter ε varies. We apply the obtained results to improve the classical averaging theory for computing T-periodic solutions of λ-families of analytic T-periodic ordinary differential equations defined on , using the displacement functions defined by these equations. We call the coefficients in the Taylor expansion of in powers of ε the averaged functions. The main contribution consists in analyzing the role that have the multiple zeros of the first non-zero averaged function. The outcome is that these multiple zeros can be of two different classes depending on whether the zeros belong or not to the analytic set defined by the real variety associated to the ideal generated by the averaged functions in the Noetheriang ring of all the real analytic functions at . We bound the maximum number of branches of isolated zeros that can bifurcate from each multiple zero z 0. Sometimes these bounds depend on the cardinalities of minimal bases of the former ideal. Several examples illustrate our results and they are compared with the classical theory, branching theory and also under the light of singularity theory of smooth maps. The examples range from polynomial vector fields to Abel differential equations and perturbed linear centers.

A simple laminate theory using the orthotropic viscoplasticity theory based on overstress. I - In-plane stress-strain relationships for metal matrix composites

NASA Technical Reports Server (NTRS)

Krempl, Erhard; Hong, Bor Zen

1989-01-01

A macromechanics analysis is presented for the in-plane, anisotropic time-dependent behavior of metal matrix laminates. The small deformation, orthotropic viscoplasticity theory based on overstress represents lamina behavior in a modified simple laminate theory. Material functions and constants can be identified in principle from experiments with laminae. Orthotropic invariants can be repositories for tension-compression asymmetry and for linear elasticity in one direction while the other directions behave in a viscoplastic manner. Computer programs are generated and tested for either unidirectional or symmetric laminates under in-plane loading. Correlations with the experimental results on metal matrix composites are presented.

Surface modification of carbon nanotubes using 3-aminopropyltriethoxysilane to improve mechanical properties of nanocomposite based polymer matrix: Experimental and Density functional theory study

NASA Astrophysics Data System (ADS)

Hamed Mashhadzadeh, A.; Fereidoon, Ab.; Ghorbanzadeh Ahangari, M.

2017-10-01

In current study we combined theoretical and experimental studies to evaluate the effect of functionalization and silanization on mechanical behavior of polymer-based/CNT nanocomposites. Epoxy was selected as thermoset polymer, polypropylene and poly vinyl chloride were selected as thermoplastic polymers. The whole procedure is divided to two sections . At first we applied density functional theory (DFT) to analyze the effect of functionalization on equilibrium distance and adsorption energy of unmodified, functionalized by sbnd OH group and silanized epoxy/CNT, PP/CNT and PVC/CNT nanocomposites and the results showed that functionalization increased adsorption energy and reduced the equilibrium distance in all studied nanocomposites and silanization had higher effect comparing to OH functionalizing. Then we prepared experimental samples of all mentioned nanocomposites and tested their tensile and flexural strength properties. The obtained results showed that functionalization increased the studied mechanical properties in all evaluated nanocomposites. Finally we compared the results of experimental and theoretical sections with each other and estimated a suitable agreement between these parts.

Effective Biot theory and its generalization to poroviscoelastic models

NASA Astrophysics Data System (ADS)

Liu, Xu; Greenhalgh, Stewart; Zhou, Bing; Greenhalgh, Mark

2018-02-01

A method is suggested to express the effective bulk modulus of the solid frame of a poroelastic material as a function of the saturated bulk modulus. This method enables effective Biot theory to be described through the use of seismic dispersion measurements or other models developed for the effective saturated bulk modulus. The effective Biot theory is generalized to a poroviscoelastic model of which the moduli are represented by the relaxation functions of the generalized fractional Zener model. The latter covers the general Zener and the Cole-Cole models as special cases. A global search method is described to determine the parameters of the relaxation functions, and a simple deterministic method is also developed to find the defining parameters of the single Cole-Cole model. These methods enable poroviscoelastic models to be constructed, which are based on measured seismic attenuation functions, and ensure that the model dispersion characteristics match the observations.

Magnetic exchange couplings from noncollinear perturbation theory: dinuclear CuII complexes.

PubMed

Phillips, Jordan J; Peralta, Juan E

2014-08-07

To benchmark the performance of a new method based on noncollinear coupled-perturbed density functional theory [J. Chem. Phys. 138, 174115 (2013)], we calculate the magnetic exchange couplings in a series of triply bridged ferromagnetic dinuclear Cu(II) complexes that have been recently synthesized [Phys. Chem. Chem. Phys. 15, 1966 (2013)]. We find that for any basis-set the couplings from our noncollinear coupled-perturbed methodology are practically identical to those of spin-projected energy-differences when a hybrid density functional approximation is employed. This demonstrates that our methodology properly recovers a Heisenberg description for these systems, and is robust in its predictive power of magnetic couplings. Furthermore, this indicates that the failure of density functional theory to capture the subtle variation of the exchange couplings in these complexes is not simply an artifact of broken-symmetry methods, but rather a fundamental weakness of current approximate density functionals for the description of magnetic couplings.

Systems theory as a framework for examining a college campus-based support program for the former foster youth.

PubMed

Schelbe, Lisa; Randolph, Karen A; Yelick, Anna; Cheatham, Leah P; Groton, Danielle B

2018-01-01

Increased attention to former foster youth pursuing post-secondary education has resulted in the creation of college campus based support programs to address their need. However, limited empirical evidence and theoretical knowledge exist about these programs. This study seeks to describe the application of systems theory as a framework for examining a college campus based support program for former foster youth. In-depth semi-structured interviews were conducted with 32 program stakeholders including students, mentors, collaborative members, and independent living program staff. Using qualitative data analysis software, holistic coding techniques were employed to analyze interview transcripts. Then applying principles of extended case method using systems theory, data were analyzed. Findings suggest systems theory serves as a framework for understanding the functioning of a college campus based support program. The theory's concepts help delineate program components and roles of stakeholders; outline boundaries between and interactions among stakeholders; and identify program strengths and weakness. Systems theory plays an important role in identifying intervention components and providing a structure through which to identify and understand program elements as a part of the planning process. This study highlights the utility of systems theory as a framework for program planning and evaluation.

Selectivity for CO2 over CH4 on a functionalized periodic mesoporous phenylene-silica explained by transition state theory

NASA Astrophysics Data System (ADS)

Kunkel, Christian; Viñes, Francesc; Lourenço, Mirtha A. O.; Ferreira, Paula; Gomes, José R. B.; Illas, Francesc

2017-03-01

Efficient separation of CO2/CH4 is critical in biogas upgrading, requiring highly selective adsorbents. Based on the adsorption energies of -0.30 and -0.14 eV, previously calculated by dispersion corrected density functional theory for adsorption/desorption of CO2 and CH4 on the functionalized periodic mesoporous phenylene-silica material APTMS@Ph-PMO, respectively, transition state theory rates were derived and used to simulate the adsorption/desorption rates of these two gases on APTMS@Ph-PMO. The latter yielded an estimation of initial CO2/CH4 selectivity at various temperatures. At T = 298 K, selectivity of 32.2 agrees to an experimental value of 26.1, which validates the method used for evaluating CO2/CH4 adsorption selectivities.

Innovating Method of Existing Mechanical Product Based on TRIZ Theory

NASA Astrophysics Data System (ADS)

Zhao, Cunyou; Shi, Dongyan; Wu, Han

Main way of product development is adaptive design and variant design based on existing product. In this paper, conceptual design frame and its flow model of innovating products is put forward through combining the methods of conceptual design and TRIZ theory. Process system model of innovating design that includes requirement analysis, total function analysis and decomposing, engineering problem analysis, finding solution of engineering problem and primarily design is constructed and this establishes the base for innovating design of existing product.

Converging Paradigms: A Reflection on Parallel Theoretical Developments in Psychoanalytic Metapsychology and Empirical Dream Research.

PubMed

Schmelowszky, Ágoston

2016-08-01

In the last decades one can perceive a striking parallelism between the shifting perspective of leading representatives of empirical dream research concerning their conceptualization of dreaming and the paradigm shift within clinically based psychoanalytic metapsychology with respect to its theory on the significance of dreaming. In metapsychology, dreaming becomes more and more a central metaphor of mental functioning in general. The theories of Klein, Bion, and Matte-Blanco can be considered as milestones of this paradigm shift. In empirical dream research, the competing theories of Hobson and of Solms respectively argued for and against the meaningfulness of the dream-work in the functioning of the mind. In the meantime, empirical data coming from various sources seemed to prove the significance of dream consciousness for the development and maintenance of adaptive waking consciousness. Metapsychological speculations and hypotheses based on empirical research data seem to point in the same direction, promising for contemporary psychoanalytic practice a more secure theoretical base. In this paper the author brings together these diverse theoretical developments and presents conclusions regarding psychoanalytic theory and technique, as well as proposing an outline of an empirical research plan for testing the specificity of psychoanalysis in developing dream formation.

Modulation transfer function of a fish-eye lens based on the sixth-order wave aberration theory.

PubMed

Jia, Han; Lu, Lijun; Cao, Yiqing

2018-01-10

A calculation program of the modulation transfer function (MTF) of a fish-eye lens is developed with the autocorrelation method, in which the sixth-order wave aberration theory of ultra-wide-angle optical systems is used to simulate the wave aberration distribution at the exit pupil of the optical systems. The autocorrelation integral is processed with the Gauss-Legendre integral, and the magnification chromatic aberration is discussed to calculate polychromatic MTF. The MTF calculation results of a given example are then compared with those previously obtained based on the fourth-order wave aberration theory of plane-symmetrical optical systems and with those from the Zemax program. The study shows that MTF based on the sixth-order wave aberration theory has satisfactory calculation accuracy even for a fish-eye lens with a large acceptance aperture. And the impacts of different types of aberrations on the MTF of a fish-eye lens are analyzed. Finally, we apply the self-adaptive and normalized real-coded genetic algorithm and the MTF developed in the paper to optimize the Nikon F/2.8 fish-eye lens; consequently, the optimized system shows better MTF performances than those of the original design.

Implications of Whole-Brained Theories of Learning and Thinking for Computer-Based Instruction.

ERIC Educational Resources Information Center

Torrance, E. Paul

1981-01-01

Discusses the implications of theories of hemispheric dominance for computer-assisted instruction, highlights some of the computer's instructional uses, lists specialized functions of the cerebral hemispheres, and lists recommended solutions to CBI program problems which were submitted by gifted children. Thirty-five sources are listed. (FM)

Some Sociological Alternatives to Human Capital Theory and Their Implications for Research on Post-Compulsory Education and Training.

ERIC Educational Resources Information Center

Fevre, Ralph; Rees, Gareth; Gorard, Stephen

1999-01-01

Based on research in South Wales, a sociological theory of participation in education and training is developed, identifying types of orientations: functional avoidance, instrumental credentialism, and vocational transformation. The inclusion of sociological insights in human-capital development policy is recommended. (SK)

Theory, Method and Practice of Neuroscientific Findings in Science Education

ERIC Educational Resources Information Center

Liu, Chia-Ju; Chiang, Wen-Wei

2014-01-01

This report provides an overview of neuroscience research that is applicable for science educators. It first offers a brief analysis of empirical studies in educational neuroscience literature, followed by six science concept learning constructs based on the whole brain theory: gaining an understanding of brain function; pattern recognition and…

The relativity of biological function.

PubMed

Laubichler, Manfred D; Stadler, Peter F; Prohaska, Sonja J; Nowick, Katja

2015-12-01

Function is a central concept in biological theories and explanations. Yet discussions about function are often based on a narrow understanding of biological systems and processes, such as idealized molecular systems or simple evolutionary, i.e., selective, dynamics. Conflicting conceptions of function continue to be used in the scientific literature to support certain claims, for instance about the fraction of "functional DNA" in the human genome. Here we argue that all biologically meaningful interpretations of function are necessarily context dependent. This implies that they derive their meaning as well as their range of applicability only within a specific theoretical and measurement context. We use this framework to shed light on the current debate about functional DNA and argue that without considering explicitly the theoretical and measurement contexts all attempts to integrate biological theories are prone to fail.

Implementation of Complexity Analyzing Based on Additional Effect

NASA Astrophysics Data System (ADS)

Zhang, Peng; Li, Na; Liang, Yanhong; Liu, Fang

According to the Complexity Theory, there is complexity in the system when the functional requirement is not be satisfied. There are several study performances for Complexity Theory based on Axiomatic Design. However, they focus on reducing the complexity in their study and no one focus on method of analyzing the complexity in the system. Therefore, this paper put forth a method of analyzing the complexity which is sought to make up the deficiency of the researches. In order to discussing the method of analyzing the complexity based on additional effect, this paper put forth two concepts which are ideal effect and additional effect. The method of analyzing complexity based on additional effect combines Complexity Theory with Theory of Inventive Problem Solving (TRIZ). It is helpful for designers to analyze the complexity by using additional effect. A case study shows the application of the process.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liakh, Dmitry I

While the formalism of multiresolution analysis (MRA), based on wavelets and adaptive integral representations of operators, is actively progressing in electronic structure theory (mostly on the independent-particle level and, recently, second-order perturbation theory), the concepts of multiresolution and adaptivity can also be utilized within the traditional formulation of correlated (many-particle) theory which is based on second quantization and the corresponding (generally nonorthogonal) tensor algebra. In this paper, we present a formalism called scale-adaptive tensor algebra (SATA) which exploits an adaptive representation of tensors of many-body operators via the local adjustment of the basis set quality. Given a series of locallymore » supported fragment bases of a progressively lower quality, we formulate the explicit rules for tensor algebra operations dealing with adaptively resolved tensor operands. The formalism suggested is expected to enhance the applicability and reliability of local correlated many-body methods of electronic structure theory, especially those directly based on atomic orbitals (or any other localized basis functions).« less

Reliability assessment of different plate theories for elastic wave propagation analysis in functionally graded plates.

PubMed

Mehrkash, Milad; Azhari, Mojtaba; Mirdamadi, Hamid Reza

2014-01-01

The importance of elastic wave propagation problem in plates arises from the application of ultrasonic elastic waves in non-destructive evaluation of plate-like structures. However, precise study and analysis of acoustic guided waves especially in non-homogeneous waveguides such as functionally graded plates are so complicated that exact elastodynamic methods are rarely employed in practical applications. Thus, the simple approximate plate theories have attracted much interest for the calculation of wave fields in FGM plates. Therefore, in the current research, the classical plate theory (CPT), first-order shear deformation theory (FSDT) and third-order shear deformation theory (TSDT) are used to obtain the transient responses of flexural waves in FGM plates subjected to transverse impulsive loadings. Moreover, comparing the results with those based on a well recognized hybrid numerical method (HNM), we examine the accuracy of the plate theories for several plates of various thicknesses under excitations of different frequencies. The material properties of the plate are assumed to vary across the plate thickness according to a simple power-law distribution in terms of volume fractions of constituents. In all analyses, spatial Fourier transform together with modal analysis are applied to compute displacement responses of the plates. A comparison of the results demonstrates the reliability ranges of the approximate plate theories for elastic wave propagation analysis in FGM plates. Furthermore, based on various examples, it is shown that whenever the plate theories are used within the appropriate ranges of plate thickness and frequency content, solution process in wave number-time domain based on modal analysis approach is not only sufficient but also efficient for finding the transient waveforms in FGM plates. Copyright © 2013 Elsevier B.V. All rights reserved.

Local electric dipole moments for periodic systems via density functional theory embedding.

PubMed

Luber, Sandra

2014-12-21

We describe a novel approach for the calculation of local electric dipole moments for periodic systems. Since the position operator is ill-defined in periodic systems, maximally localized Wannier functions based on the Berry-phase approach are usually employed for the evaluation of local contributions to the total electric dipole moment of the system. We propose an alternative approach: within a subsystem-density functional theory based embedding scheme, subset electric dipole moments are derived without any additional localization procedure, both for hybrid and non-hybrid exchange-correlation functionals. This opens the way to a computationally efficient evaluation of local electric dipole moments in (molecular) periodic systems as well as their rigorous splitting into atomic electric dipole moments. As examples, Infrared spectra of liquid ethylene carbonate and dimethyl carbonate are presented, which are commonly employed as solvents in Lithium ion batteries.

Bootstrapping conformal field theories with the extremal functional method.

PubMed

El-Showk, Sheer; Paulos, Miguel F

2013-12-13

The existence of a positive linear functional acting on the space of (differences between) conformal blocks has been shown to rule out regions in the parameter space of conformal field theories (CFTs). We argue that at the boundary of the allowed region the extremal functional contains, in principle, enough information to determine the dimensions and operator product expansion (OPE) coefficients of an infinite number of operators appearing in the correlator under analysis. Based on this idea we develop the extremal functional method (EFM), a numerical procedure for deriving the spectrum and OPE coefficients of CFTs lying on the boundary (of solution space). We test the EFM by using it to rederive the low lying spectrum and OPE coefficients of the two-dimensional Ising model based solely on the dimension of a single scalar quasiprimary--no Virasoro algebra required. Our work serves as a benchmark for applications to more interesting, less known CFTs in the near future.

2D problems of surface growth theory with applications to additive manufacturing

NASA Astrophysics Data System (ADS)

Manzhirov, A. V.; Mikhin, M. N.

2018-04-01

We study 2D problems of surface growth theory of deformable solids and their applications to the analysis of the stress-strain state of AM fabricated products and structures. Statements of the problems are given, and a solution method based on the approaches of the theory of functions of a complex variable is suggested. Computations are carried out for model problems. Qualitative and quantitative results are discussed.

Diagrams for comprehensive molecular orbital-based chemical reaction analyses: reactive orbital energy diagrams.

PubMed

Tsuneda, Takao; Singh, Raman Kumar; Chattaraj, Pratim Kumar

2018-05-15

Reactive orbital energy diagrams are presented as a tool for comprehensively performing orbital-based reaction analyses. The diagrams rest on the reactive orbital energy theory, which is the expansion of conceptual density functional theory (DFT) to an orbital energy-based theory. The orbital energies on the intrinsic reaction coordinates of fundamental reactions are calculated by long-range corrected DFT, which is confirmed to provide accurate orbital energies of small molecules, combining with a van der Waals (vdW) correlation functional, in order to examine the vdW effect on the orbital energies. By analysing the reactions based on the reactive orbital energy theory using these accurate orbital energies, it is found that vdW interactions significantly affect the orbital energies in the initial reaction processes and that more than 70% of reactions are determined to be initially driven by charge transfer, while the remaining structural deformation (dynamics)-driven reactions are classified into identity, cyclization and ring-opening, unimolecular dissociation, and H2 reactions. The reactive orbital energy diagrams, which are constructed using these results, reveal that reactions progress so as to delocalize the occupied reactive orbitals, which are determined as contributing orbitals and are usually not HOMOs, by hybridizing the unoccupied reactive orbitals, which are usually not LUMOs. These diagrams also raise questions about conventional orbital-based diagrams such as frontier molecular orbital diagrams, even for the well-established interpretation of Diels-Alder reactions.

Electron-Ion Dynamics with Time-Dependent Density Functional Theory: Towards Predictive Solar Cell Modeling: Final Technical Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maitra, Neepa

2016-07-14

This project investigates the accuracy of currently-used functionals in time-dependent density functional theory, which is today routinely used to predict and design materials and computationally model processes in solar energy conversion. The rigorously-based electron-ion dynamics method developed here sheds light on traditional methods and overcomes challenges those methods have. The fundamental research undertaken here is important for building reliable and practical methods for materials discovery. The ultimate goal is to use these tools for the computational design of new materials for solar cell devices of high efficiency.

X-ray absorption in insulators with non-Hermitian real-time time-dependent density functional theory.

PubMed

Fernando, Ranelka G; Balhoff, Mary C; Lopata, Kenneth

2015-02-10

Non-Hermitian real-time time-dependent density functional theory was used to compute the Si L-edge X-ray absorption spectrum of α-quartz using an embedded finite cluster model and atom-centered basis sets. Using tuned range-separated functionals and molecular orbital-based imaginary absorbing potentials, the excited states spanning the pre-edge to ∼20 eV above the ionization edge were obtained in good agreement with experimental data. This approach is generalizable to TDDFT studies of core-level spectroscopy and dynamics in a wide range of materials.

Serenity: A subsystem quantum chemistry program.

PubMed

Unsleber, Jan P; Dresselhaus, Thomas; Klahr, Kevin; Schnieders, David; Böckers, Michael; Barton, Dennis; Neugebauer, Johannes

2018-05-15

We present the new quantum chemistry program Serenity. It implements a wide variety of functionalities with a focus on subsystem methodology. The modular code structure in combination with publicly available external tools and particular design concepts ensures extensibility and robustness with a focus on the needs of a subsystem program. Several important features of the program are exemplified with sample calculations with subsystem density-functional theory, potential reconstruction techniques, a projection-based embedding approach and combinations thereof with geometry optimization, semi-numerical frequency calculations and linear-response time-dependent density-functional theory. © 2018 Wiley Periodicals, Inc. © 2018 Wiley Periodicals, Inc.

Electronic damping of anharmonic adsorbate vibrations at metallic surfaces

NASA Astrophysics Data System (ADS)

Tremblay, Jean Christophe; Monturet, Serge; Saalfrank, Peter

2010-03-01

The nonadiabatic coupling of an adsorbate close to a metallic surface leads to electronic damping of adsorbate vibrations and line broadening in vibrational spectroscopy. Here, a perturbative treatment of the electronic contribution to the lifetime broadening serves as a building block for a new approach, in which anharmonic vibrational transition rates are calculated from a position-dependent coupling function. Different models for the coupling function will be tested, all related to embedding theory. The first two are models based on a scattering approach with (i) a jellium-type and (ii) a density functional theory based embedding density, respectively. In a third variant a further refined model is used for the embedding density, and a semiempirical approach is taken in which a scaling factor is chosen to match harmonic, single-site, first-principles transition rates, obtained from periodic density functional theory. For the example of hydrogen atoms on (adsorption) and below (subsurface absorption) a Pd(111) surface, lifetimes of and transition rates between vibrational levels are computed. The transition rates emerging from different models serve as input for the selective subsurface adsorption of hydrogen in palladium starting from an adsorption site, by using sequences of infrared laser pulses in a laser distillation scheme.

Preserving knee function following osteoarthritis diagnosis: a sustainability theory and social ecology clinical commentary.

PubMed

Nyland, J; Wera, J; Henzman, C; Miller, T; Jakob, R; Caborn, D N M

2015-02-01

To sustain natural systems, there must be an ongoing balance between environmental, social, and economic considerations. A key element of sustainability theory is to identify the most vulnerable surroundings. The most vulnerable knee tissue is the articular cartilage as it is the last line of osteoarthritis (OA) defense. This tissue has a poor capacity for healing. Based on sustainability theory and social ecology concepts we propose that several key factors contribute to knee function preservation. Factors include health history, genetic predisposition, personal behaviors, and socio-environmental factors in addition to local-regional-global physiological system function. Addressing only some of these factors or any one factor in isolation may lead to less than optimal treatment effectiveness. The purpose of this commentary is to introduce a medical, surgical and rehabilitation management approach for patients with knee OA that considers more than physical function improvement. This approach also considers social, emotional, and environmental factors to better ensure patient satisfaction, fulfilled expectations and successful outcomes. A clinical care pathway is presented for a 57-year-old patient with medial compartment knee OA who is contemplating early arthroplasty versus a knee function preservation treatment approach. Early arthroplasty refers to high revision likelihood based on a minimum 15 year prosthesis life-expectancy. Copyright © 2014 Elsevier Ltd. All rights reserved.

Angular coherence in ultrasound imaging: Theory and applications

PubMed Central

Li, You Leo; Dahl, Jeremy J.

2017-01-01

The popularity of plane-wave transmits at multiple transmit angles for synthetic transmit aperture (or coherent compounding) has spawned a number of adaptations and new developments of ultrasonic imaging. However, the coherence properties of backscattered signals with plane-wave transmits at different angles are unknown and may impact a subset of these techniques. To provide a framework for the analysis of the coherence properties of such signals, this article introduces the angular coherence theory in medical ultrasound imaging. The theory indicates that the correlation function of such signals forms a Fourier transform pair with autocorrelation function of the receive aperture function. This conclusion can be considered as an extended form of the van Cittert Zernike theorem. The theory is validated with simulation and experimental results obtained on speckle targets. On the basis of the angular coherence of the backscattered wave, a new short-lag angular coherence beamformer is proposed and compared with an existing spatial-coherence-based beamformer. An application of the theory in phase shift estimation and speed of sound estimation is also presented. PMID:28372139

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.

Prospect theory on the brain? Toward a cognitive neuroscience of decision under risk.

PubMed

Trepel, Christopher; Fox, Craig R; Poldrack, Russell A

2005-04-01

Most decisions must be made without advance knowledge of their consequences. Economists and psychologists have devoted much attention to modeling decisions made under conditions of risk in which options can be characterized by a known probability distribution over possible outcomes. The descriptive shortcomings of classical economic models motivated the development of prospect theory (D. Kahneman, A. Tversky, Prospect theory: An analysis of decision under risk. Econometrica, 4 (1979) 263-291; A. Tversky, D. Kahneman, Advances in prospect theory: Cumulative representation of uncertainty. Journal of Risk and Uncertainty, 5 (4) (1992) 297-323) the most successful behavioral model of decision under risk. In the prospect theory, subjective value is modeled by a value function that is concave for gains, convex for losses, and steeper for losses than for gains; the impact of probabilities are characterized by a weighting function that overweights low probabilities and underweights moderate to high probabilities. We outline the possible neural bases of the components of prospect theory, surveying evidence from human imaging, lesion, and neuropharmacology studies as well as animal neurophysiology studies. These results provide preliminary suggestions concerning the neural bases of prospect theory that include a broad set of brain regions and neuromodulatory systems. These data suggest that focused studies of decision making in the context of quantitative models may provide substantial leverage towards a fuller understanding of the cognitive neuroscience of decision making.

On consciousness, resting state fMRI, and neurodynamics

PubMed Central

2010-01-01

Background During the last years, functional magnetic resonance imaging (fMRI) of the brain has been introduced as a new tool to measure consciousness, both in a clinical setting and in a basic neurocognitive research. Moreover, advanced mathematical methods and theories have arrived the field of fMRI (e.g. computational neuroimaging), and functional and structural brain connectivity can now be assessed non-invasively. Results The present work deals with a pluralistic approach to "consciousness'', where we connect theory and tools from three quite different disciplines: (1) philosophy of mind (emergentism and global workspace theory), (2) functional neuroimaging acquisitions, and (3) theory of deterministic and statistical neurodynamics – in particular the Wilson-Cowan model and stochastic resonance. Conclusions Based on recent experimental and theoretical work, we believe that the study of large-scale neuronal processes (activity fluctuations, state transitions) that goes on in the living human brain while examined with functional MRI during "resting state", can deepen our understanding of graded consciousness in a clinical setting, and clarify the concept of "consiousness" in neurocognitive and neurophilosophy research. PMID:20522270

Towards a quantitative description of tunneling conductance of superconductors: Application to LiFeAs

DOE PAGES

Kreisel, A.; Nelson, R.; Berlijn, T.; ...

2016-12-27

Since the discovery of iron-based superconductors, a number of theories have been put forward to explain the qualitative origin of pairing, but there have been few attempts to make quantitative, material-specific comparisons to experimental results. The spin-fluctuation theory of electronic pairing, based on first-principles electronic structure calculations, makes predictions for the superconducting gap. Within the same framework, the surface wave functions may also be calculated, allowing, e.g., for detailed comparisons between theoretical results and measured scanning tunneling topographs and spectra. We present such a comparison between theory and experiment on the Fe-based superconductor LiFeAs. Our results for the homogeneous surfacemore » as well as impurity states are presented as a benchmark test of the theory. For the homogeneous system, we argue that the maxima of topographic image intensity may be located at positions above either the As or Li atoms, depending on tip height and the setpoint current of the measurement. We further report the experimental observation of transitions between As- and Li-registered lattices as functions of both tip height and setpoint bias, in agreement with this prediction. Next, we give a detailed comparison between the simulated scanning tunneling microscopy images of transition-metal defects with experiment. Finally, we discuss possible extensions of the current framework to obtain a theory with true predictive power for scanning tunneling microscopy in Fe-based systems.« less

Towards a quantitative description of tunneling conductance of superconductors: Application to LiFeAs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kreisel, A.; Nelson, R.; Berlijn, T.

Since the discovery of iron-based superconductors, a number of theories have been put forward to explain the qualitative origin of pairing, but there have been few attempts to make quantitative, material-specific comparisons to experimental results. The spin-fluctuation theory of electronic pairing, based on first-principles electronic structure calculations, makes predictions for the superconducting gap. Within the same framework, the surface wave functions may also be calculated, allowing, e.g., for detailed comparisons between theoretical results and measured scanning tunneling topographs and spectra. We present such a comparison between theory and experiment on the Fe-based superconductor LiFeAs. Our results for the homogeneous surfacemore » as well as impurity states are presented as a benchmark test of the theory. For the homogeneous system, we argue that the maxima of topographic image intensity may be located at positions above either the As or Li atoms, depending on tip height and the setpoint current of the measurement. We further report the experimental observation of transitions between As- and Li-registered lattices as functions of both tip height and setpoint bias, in agreement with this prediction. Next, we give a detailed comparison between the simulated scanning tunneling microscopy images of transition-metal defects with experiment. Finally, we discuss possible extensions of the current framework to obtain a theory with true predictive power for scanning tunneling microscopy in Fe-based systems.« less

An advanced kinetic theory for morphing continuum with inner structures

NASA Astrophysics Data System (ADS)

Chen, James

2017-12-01

Advanced kinetic theory with the Boltzmann-Curtiss equation provides a promising tool for polyatomic gas flows, especially for fluid flows containing inner structures, such as turbulence, polyatomic gas flows and others. Although a Hamiltonian-based distribution function was proposed for diatomic gas flow, a general distribution function for the generalized Boltzmann-Curtiss equations and polyatomic gas flow is still out of reach. With assistance from Boltzmann's entropy principle, a generalized Boltzmann-Curtiss distribution for polyatomic gas flow is introduced. The corresponding governing equations at equilibrium state are derived and compared with Eringen's morphing (micropolar) continuum theory derived under the framework of rational continuum thermomechanics. Although rational continuum thermomechanics has the advantages of mathematical rigor and simplicity, the presented statistical kinetic theory approach provides a clear physical picture for what the governing equations represent.

Particle connectedness and cluster formation in sequential depositions of particles: integral-equation theory.

PubMed

Danwanichakul, Panu; Glandt, Eduardo D

2004-11-15

We applied the integral-equation theory to the connectedness problem. The method originally applied to the study of continuum percolation in various equilibrium systems was modified for our sequential quenching model, a particular limit of an irreversible adsorption. The development of the theory based on the (quenched-annealed) binary-mixture approximation includes the Ornstein-Zernike equation, the Percus-Yevick closure, and an additional term involving the three-body connectedness function. This function is simplified by introducing a Kirkwood-like superposition approximation. We studied the three-dimensional (3D) system of randomly placed spheres and 2D systems of square-well particles, both with a narrow and with a wide well. The results from our integral-equation theory are in good accordance with simulation results within a certain range of densities.

Particle connectedness and cluster formation in sequential depositions of particles: Integral-equation theory

NASA Astrophysics Data System (ADS)

Danwanichakul, Panu; Glandt, Eduardo D.

2004-11-01

We applied the integral-equation theory to the connectedness problem. The method originally applied to the study of continuum percolation in various equilibrium systems was modified for our sequential quenching model, a particular limit of an irreversible adsorption. The development of the theory based on the (quenched-annealed) binary-mixture approximation includes the Ornstein-Zernike equation, the Percus-Yevick closure, and an additional term involving the three-body connectedness function. This function is simplified by introducing a Kirkwood-like superposition approximation. We studied the three-dimensional (3D) system of randomly placed spheres and 2D systems of square-well particles, both with a narrow and with a wide well. The results from our integral-equation theory are in good accordance with simulation results within a certain range of densities.

Einstein gravity 3-point functions from conformal field theory

NASA Astrophysics Data System (ADS)

Afkhami-Jeddi, Nima; Hartman, Thomas; Kundu, Sandipan; Tajdini, Amirhossein

2017-12-01

We study stress tensor correlation functions in four-dimensional conformal field theories with large N and a sparse spectrum. Theories in this class are expected to have local holographic duals, so effective field theory in anti-de Sitter suggests that the stress tensor sector should exhibit universal, gravity-like behavior. At the linearized level, the hallmark of locality in the emergent geometry is that stress tensor three-point functions 〈 T T T 〉, normally specified by three constants, should approach a universal structure controlled by a single parameter as the gap to higher spin operators is increased. We demonstrate this phenomenon by a direct CFT calculation. Stress tensor exchange, by itself, violates causality and unitarity unless the three-point functions are carefully tuned, and the unique consistent choice exactly matches the prediction of Einstein gravity. Under some assumptions about the other potential contributions, we conclude that this structure is universal, and in particular, that the anomaly coefficients satisfy a ≈ c as conjectured by Camanho et al. The argument is based on causality of a four-point function, with kinematics designed to probe bulk locality, and invokes the chaos bound of Maldacena, Shenker, and Stanford.

Predictive equation of state method for heavy materials based on the Dirac equation and density functional theory

NASA Astrophysics Data System (ADS)

Wills, John M.; Mattsson, Ann E.

2012-02-01

Density functional theory (DFT) provides a formally predictive base for equation of state properties. Available approximations to the exchange/correlation functional provide accurate predictions for many materials in the periodic table. For heavy materials however, DFT calculations, using available functionals, fail to provide quantitative predictions, and often fail to be even qualitative. This deficiency is due both to the lack of the appropriate confinement physics in the exchange/correlation functional and to approximations used to evaluate the underlying equations. In order to assess and develop accurate functionals, it is essential to eliminate all other sources of error. In this talk we describe an efficient first-principles electronic structure method based on the Dirac equation and compare the results obtained with this method with other methods generally used. Implications for high-pressure equation of state of relativistic materials are demonstrated in application to Ce and the light actinides. Sandia National Laboratories is a multi-program laboratory managed andoperated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Multiple exciton generation in chiral carbon nanotubes: Density functional theory based computation

NASA Astrophysics Data System (ADS)

Kryjevski, Andrei; Mihaylov, Deyan; Kilina, Svetlana; Kilin, Dmitri

2017-10-01

We use a Boltzmann transport equation (BE) to study time evolution of a photo-excited state in a nanoparticle including phonon-mediated exciton relaxation and the multiple exciton generation (MEG) processes, such as exciton-to-biexciton multiplication and biexciton-to-exciton recombination. BE collision integrals are computed using Kadanoff-Baym-Keldysh many-body perturbation theory based on density functional theory simulations, including exciton effects. We compute internal quantum efficiency (QE), which is the number of excitons generated from an absorbed photon in the course of the relaxation. We apply this approach to chiral single-wall carbon nanotubes (SWCNTs), such as (6,2) and (6,5). We predict efficient MEG in the (6,2) and (6,5) SWCNTs within the solar spectrum range starting at the 2Eg energy threshold and with QE reaching ˜1.6 at about 3Eg, where Eg is the electronic gap.

Control theory based airfoil design for potential flow and a finite volume discretization

NASA Technical Reports Server (NTRS)

Reuther, J.; Jameson, A.

1994-01-01

This paper describes the implementation of optimization techniques based on control theory for airfoil design. In previous studies it was shown that control theory could be used to devise an effective optimization procedure for two-dimensional profiles in which the shape is determined by a conformal transformation from a unit circle, and the control is the mapping function. The goal of our present work is to develop a method which does not depend on conformal mapping, so that it can be extended to treat three-dimensional problems. Therefore, we have developed a method which can address arbitrary geometric shapes through the use of a finite volume method to discretize the potential flow equation. Here the control law serves to provide computationally inexpensive gradient information to a standard numerical optimization method. Results are presented, where both target speed distributions and minimum drag are used as objective functions.

Numerical implementation of multiple peeling theory and its application to spider web anchorages.

PubMed

Brely, Lucas; Bosia, Federico; Pugno, Nicola M

2015-02-06

Adhesion of spider web anchorages has been studied in recent years, including the specific functionalities achieved through different architectures. To better understand the delamination mechanisms of these and other biological or artificial fibrillar adhesives, and how their adhesion can be optimized, we develop a novel numerical model to simulate the multiple peeling of structures with arbitrary branching and adhesion angles, including complex architectures. The numerical model is based on a recently developed multiple peeling theory, which extends the energy-based single peeling theory of Kendall, and can be applied to arbitrarily complex structures. In particular, we numerically show that a multiple peeling problem can be treated as the superposition of single peeling configurations even for complex structures. Finally, we apply the developed numerical approach to study spider web anchorages, showing how their function is achieved through optimal geometrical configurations.

Numerical implementation of multiple peeling theory and its application to spider web anchorages

PubMed Central

Brely, Lucas; Bosia, Federico; Pugno, Nicola M.

2015-01-01

Adhesion of spider web anchorages has been studied in recent years, including the specific functionalities achieved through different architectures. To better understand the delamination mechanisms of these and other biological or artificial fibrillar adhesives, and how their adhesion can be optimized, we develop a novel numerical model to simulate the multiple peeling of structures with arbitrary branching and adhesion angles, including complex architectures. The numerical model is based on a recently developed multiple peeling theory, which extends the energy-based single peeling theory of Kendall, and can be applied to arbitrarily complex structures. In particular, we numerically show that a multiple peeling problem can be treated as the superposition of single peeling configurations even for complex structures. Finally, we apply the developed numerical approach to study spider web anchorages, showing how their function is achieved through optimal geometrical configurations. PMID:25657835

Multiple exciton generation in chiral carbon nanotubes: Density functional theory based computation.

PubMed

Kryjevski, Andrei; Mihaylov, Deyan; Kilina, Svetlana; Kilin, Dmitri

2017-10-21

We use a Boltzmann transport equation (BE) to study time evolution of a photo-excited state in a nanoparticle including phonon-mediated exciton relaxation and the multiple exciton generation (MEG) processes, such as exciton-to-biexciton multiplication and biexciton-to-exciton recombination. BE collision integrals are computed using Kadanoff-Baym-Keldysh many-body perturbation theory based on density functional theory simulations, including exciton effects. We compute internal quantum efficiency (QE), which is the number of excitons generated from an absorbed photon in the course of the relaxation. We apply this approach to chiral single-wall carbon nanotubes (SWCNTs), such as (6,2) and (6,5). We predict efficient MEG in the (6,2) and (6,5) SWCNTs within the solar spectrum range starting at the 2E g energy threshold and with QE reaching ∼1.6 at about 3E g , where E g is the electronic gap.

Density functional theory calculation of refractive indices of liquid-forming silicon oil compounds

NASA Astrophysics Data System (ADS)

Lee, Sanghun; Park, Sung Soo; Hagelberg, Frank

2012-02-01

A combination of quantum chemical calculation and molecular dynamics simulation is applied to compute refractive indices of liquid-forming silicon oils. The densities of these species are obtained from molecular dynamics simulations based on the NPT ensemble while the molecular polarizabilities are evaluated by density functional theory. This procedure is shown to yield results well compatible with available experimental data, suggesting that it represents a robust and economic route for determining the refractive indices of liquid-forming organic complexes containing silicon.

Trait-based plant ecology: moving towards a unifying species coexistence theory : Features of the Special Section.

PubMed

Escudero, Adrián; Valladares, Fernando

2016-04-01

Functional traits are the center of recent attempts to unify key ecological theories on species coexistence and assembling in populations and communities. While the plethora of studies on the role of functional traits to explain patterns and dynamics of communities has rendered a complex picture due to the idiosyncrasies of each study system and approach, there is increasing evidence on their actual relevance when aspects such as different spatial scales, intraspecific variability and demography are considered.

Stochastic Gravity: Theory and Applications.

PubMed

Hu, Bei Lok; Verdaguer, Enric

2004-01-01

Whereas semiclassical gravity is based on the semiclassical Einstein equation with sources given by the expectation value of the stress-energy tensor of quantum fields, stochastic semiclassical gravity is based on the Einstein-Langevin equation, which has in addition sources due to the noise kernel. The noise kernel is the vacuum expectation value of the (operatorvalued) stress-energy bi-tensor which describes the fluctuations of quantum matter fields in curved spacetimes. In the first part, we describe the fundamentals of this new theory via two approaches: the axiomatic and the functional. The axiomatic approach is useful to see the structure of the theory from the framework of semiclassical gravity, showing the link from the mean value of the stress-energy tensor to their correlation functions. The functional approach uses the Feynman-Vernon influence functional and the Schwinger-Keldysh closed-time-path effective action methods which are convenient for computations. It also brings out the open systems concepts and the statistical and stochastic contents of the theory such as dissipation, fluctuations, noise, and decoherence. We then focus on the properties of the stress-energy bi-tensor. We obtain a general expression for the noise kernel of a quantum field defined at two distinct points in an arbitrary curved spacetime as products of covariant derivatives of the quantum field's Green function. In the second part, we describe three applications of stochastic gravity theory. First, we consider metric perturbations in a Minkowski spacetime. We offer an analytical solution of the Einstein-Langevin equation and compute the two-point correlation functions for the linearized Einstein tensor and for the metric perturbations. Second, we discuss structure formation from the stochastic gravity viewpoint, which can go beyond the standard treatment by incorporating the full quantum effect of the inflaton fluctuations. Third, we discuss the backreaction of Hawking radiation in the gravitational background of a quasi-static black hole (enclosed in a box). We derive a fluctuation-dissipation relation between the fluctuations in the radiation and the dissipative dynamics of metric fluctuations.

On Dreams and Motivation: Comparison of Freud’s and Hobson’s Views

PubMed Central

Boag, Simon

2017-01-01

The merits of Freudian dream theory continue to be debated and both supporters and critics appeal to empirical evidence to support their respective positions. What receives much less attention is the theoretical coherency of either Freudian dream theory or alternative perspectives. This paper examines Freudian dream theory and J. Allan Hobson’s alternative position by addressing the role of motivation in dreams. This paper first discusses motivation in Freudian theory and its relation to dreams and disguise-censorship. The role of motivation in Hobson’s theory is then considered. Hobson’s claim that dream plot and content selection is random and based on design error and functional imbalance is then discussed in relation to the protoconsciousness theory proposal that dreams serve an adaptive function. While there are apparent inconsistencies in Hobson’s position, his appeal to emotions and instincts provides a preliminary platform for understanding the role of motivation in dreams that is consonant with the Freudian position. PMID:28111554

Stepwise Analysis of Differential Item Functioning Based on Multiple-Group Partial Credit Model.

ERIC Educational Resources Information Center

Muraki, Eiji

1999-01-01

Extended an Item Response Theory (IRT) method for detection of differential item functioning to the partial credit model and applied the method to simulated data using a stepwise procedure. Then applied the stepwise DIF analysis based on the multiple-group partial credit model to writing trend data from the National Assessment of Educational…

Excitation spectra of retinal by multiconfiguration pair-density functional theory.

PubMed

Dong, Sijia S; Gagliardi, Laura; Truhlar, Donald G

2018-03-07

Retinal is the chromophore in proteins responsible for vision. The absorption maximum of retinal is sensitive to mutations of the protein. However, it is not easy to predict the absorption spectrum of retinal accurately, and questions remain even after intensive investigation. Retinal poses a challenge for Kohn-Sham density functional theory (KS-DFT) because of the charge transfer character in its excitations, and it poses a challenge for wave function theory because the large size of the molecule makes multiconfigurational perturbation theory methods expensive. In this study, we demonstrate that multiconfiguration pair-density functional theory (MC-PDFT) provides an efficient way to predict the vertical excitation energies of 11-Z retinal, and it reproduces the experimentally determined absorption band widths and peak positions better than complete active space second-order perturbation theory (CASPT2). The consistency between complete active space self-consistent field (CASSCF) and KS-DFT dipole moments is demonstrated to be a useful criterion in selecting the active space. We also found that the nature of the terminal groups and the conformations of retinal play a significant role in the absorption spectrum. By considering a thermal distribution of conformations, we predict an absorption spectrum of retinal that is consistent with the experimental gas-phase spectrum. The location of the absorption peak and the spectral broadening based on MC-PDFT calculations agree better with experiments than those of CASPT2.

[An oral function improvement program utilizing health behavior theories ameliorates oral functions and oral hygienic conditions of pre-frail elderly persons].

PubMed

Sakaguchi, Hideo

2014-06-01

Oral function improvement programs utilizing health behavior theories are considered to be effective in preventing the need for long-term social care. In the present study, an oral function improvement program based upon health behavior theories was designed, and its utility was assessed in 102 pre-frail elderly persons (33 males, 69 females, mean age: 76.9 +/- 5.7) considered to be in potential need of long-term social care and attending a long-term care prevention class in Sayama City, Saitama Prefecture, Japan. The degree of improvement in oral functions (7 items) and oral hygienic conditions (3 items) was assessed by comparing oral health before and after participation in the program. The results showed statistically significant improvements in the following oral functions: (1) lip functions (oral diadochokinesis, measured by the regularity of the repetition of the syllable "Pa"), (2) tongue functions, (3) tongue root motor skills (oral diadochokinesis, measured by the regularity of the repetition of the syllables "Ta" and "Ka"), (4) tongue extension/retraction, (5) side-to-side tongue movement functions, (6) cheek motor skills, and (7) repetitive saliva swallowing test (RSST). The following measures of oral hygiene also showed a statistically significant improvement: (1) debris on dentures or teeth, (2) coated tongue, and (3) frequency of oral cleaning. These findings demonstrated that an improvement program informed by health behavior theories is useful in improving oral functions and oral hygiene conditions.

Unifying model of carpal mechanics based on computationally derived isometric constraints and rules-based motion - the stable central column theory.

PubMed

Sandow, M J; Fisher, T J; Howard, C Q; Papas, S

2014-05-01

This study was part of a larger project to develop a (kinetic) theory of carpal motion based on computationally derived isometric constraints. Three-dimensional models were created from computed tomography scans of the wrists of ten normal subjects and carpal spatial relationships at physiological motion extremes were assessed. Specific points on the surface of the various carpal bones and the radius that remained isometric through range of movement were identified. Analysis of the isometric constraints and intercarpal motion suggests that the carpus functions as a stable central column (lunate-capitate-hamate-trapezoid-trapezium) with a supporting lateral column (scaphoid), which behaves as a 'two gear four bar linkage'. The triquetrum functions as an ulnar translation restraint, as well as controlling lunate flexion. The 'trapezoid'-shaped trapezoid places the trapezium anterior to the transverse plane of the radius and ulna, and thus rotates the principal axis of the central column to correspond to that used in the 'dart thrower's motion'. This study presents a forward kinematic analysis of the carpus that provides the basis for the development of a unifying kinetic theory of wrist motion based on isometric constraints and rules-based motion.

Excitation energies from range-separated time-dependent density and density matrix functional theory.

PubMed

Pernal, Katarzyna

2012-05-14

Time-dependent density functional theory (TD-DFT) in the adiabatic formulation exhibits known failures when applied to predicting excitation energies. One of them is the lack of the doubly excited configurations. On the other hand, the time-dependent theory based on a one-electron reduced density matrix functional (time-dependent density matrix functional theory, TD-DMFT) has proven accurate in determining single and double excitations of H(2) molecule if the exact functional is employed in the adiabatic approximation. We propose a new approach for computing excited state energies that relies on functionals of electron density and one-electron reduced density matrix, where the latter is applied in the long-range region of electron-electron interactions. A similar approach has been recently successfully employed in predicting ground state potential energy curves of diatomic molecules even in the dissociation limit, where static correlation effects are dominating. In the paper, a time-dependent functional theory based on the range-separation of electronic interaction operator is rigorously formulated. To turn the approach into a practical scheme the adiabatic approximation is proposed for the short- and long-range components of the coupling matrix present in the linear response equations. In the end, the problem of finding excitation energies is turned into an eigenproblem for a symmetric matrix. Assignment of obtained excitations is discussed and it is shown how to identify double excitations from the analysis of approximate transition density matrix elements. The proposed method used with the short-range local density approximation (srLDA) and the long-range Buijse-Baerends density matrix functional (lrBB) is applied to H(2) molecule (at equilibrium geometry and in the dissociation limit) and to Be atom. The method accounts for double excitations in the investigated systems but, unfortunately, the accuracy of some of them is poor. The quality of the other excitations is in general much better than that offered by TD-DFT-LDA or TD-DMFT-BB approximations if the range-separation parameter is properly chosen. The latter remains an open problem.

Computational Thermochemistry: Scale Factor Databases and Scale Factors for Vibrational Frequencies Obtained from Electronic Model Chemistries.

PubMed

Alecu, I M; Zheng, Jingjing; Zhao, Yan; Truhlar, Donald G

2010-09-14

Optimized scale factors for calculating vibrational harmonic and fundamental frequencies and zero-point energies have been determined for 145 electronic model chemistries, including 119 based on approximate functionals depending on occupied orbitals, 19 based on single-level wave function theory, three based on the neglect-of-diatomic-differential-overlap, two based on doubly hybrid density functional theory, and two based on multicoefficient correlation methods. Forty of the scale factors are obtained from large databases, which are also used to derive two universal scale factor ratios that can be used to interconvert between scale factors optimized for various properties, enabling the derivation of three key scale factors at the effort of optimizing only one of them. A reduced scale factor optimization model is formulated in order to further reduce the cost of optimizing scale factors, and the reduced model is illustrated by using it to obtain 105 additional scale factors. Using root-mean-square errors from the values in the large databases, we find that scaling reduces errors in zero-point energies by a factor of 2.3 and errors in fundamental vibrational frequencies by a factor of 3.0, but it reduces errors in harmonic vibrational frequencies by only a factor of 1.3. It is shown that, upon scaling, the balanced multicoefficient correlation method based on coupled cluster theory with single and double excitations (BMC-CCSD) can lead to very accurate predictions of vibrational frequencies. With a polarized, minimally augmented basis set, the density functionals with zero-point energy scale factors closest to unity are MPWLYP1M (1.009), τHCTHhyb (0.989), BB95 (1.012), BLYP (1.013), BP86 (1.014), B3LYP (0.986), MPW3LYP (0.986), and VSXC (0.986).

Enskog theory for polydisperse granular mixtures. I. Navier-Stokes order transport.

PubMed

Garzó, Vicente; Dufty, James W; Hrenya, Christine M

2007-09-01

A hydrodynamic description for an s -component mixture of inelastic, smooth hard disks (two dimensions) or spheres (three dimensions) is derived based on the revised Enskog theory for the single-particle velocity distribution functions. In this first part of the two-part series, the macroscopic balance equations for mass, momentum, and energy are derived. Constitutive equations are calculated from exact expressions for the fluxes by a Chapman-Enskog expansion carried out to first order in spatial gradients, thereby resulting in a Navier-Stokes order theory. Within this context of small gradients, the theory is applicable to a wide range of restitution coefficients and densities. The resulting integral-differential equations for the zeroth- and first-order approximations of the distribution functions are given in exact form. An approximate solution to these equations is required for practical purposes in order to cast the constitutive quantities as algebraic functions of the macroscopic variables; this task is described in the companion paper.

Density-Functional Theory with Optimized Effective Potential and Self-Interaction Correction for the Double Ionization of He and Be Atoms

NASA Astrophysics Data System (ADS)

Heslar, John; Telnov, Dmitry; Chu, Shih-I.

2012-06-01

We present a self-interaction-free (SIC) time-dependent density-functional theory (TDDFT) for the treatment of double ionization processes of many-electron systems. The method is based on the Krieger-Li-Iafrate (KLI) treatment of the optimized effective potential (OEP) theory and the incorporation of an explicit self-interaction correction (SIC) term. In the framework of the time-dependent density functional theory, we have performed 3D calculations of double ionization of He and Be atoms by strong near-infrared laser fields. We make use of the exchange-correlation potential with the integer discontinuity which improves the description of the double ionization process. We found that proper description of the double ionization requires the TDDFT exchange-correlation potential with the discontinuity with respect to the variation of the spin particle numbers (SPN) only. The results for the intensity-dependent probabilities of single and double ionization are presented and reproduce the famous ``knee'' structure.

Molecular density functional theory of water describing hydrophobicity at short and long length scales

NASA Astrophysics Data System (ADS)

Jeanmairet, Guillaume; Levesque, Maximilien; Borgis, Daniel

2013-10-01

We present an extension of our recently introduced molecular density functional theory of water [G. Jeanmairet et al., J. Phys. Chem. Lett. 4, 619 (2013)] to the solvation of hydrophobic solutes of various sizes, going from angstroms to nanometers. The theory is based on the quadratic expansion of the excess free energy in terms of two classical density fields: the particle density and the multipolar polarization density. Its implementation requires as input a molecular model of water and three measurable bulk properties, namely, the structure factor and the k-dependent longitudinal and transverse dielectric susceptibilities. The fine three-dimensional water structure around small hydrophobic molecules is found to be well reproduced. In contrast, the computed solvation free-energies appear overestimated and do not exhibit the correct qualitative behavior when the hydrophobic solute is grown in size. These shortcomings are corrected, in the spirit of the Lum-Chandler-Weeks theory, by complementing the functional with a truncated hard-sphere functional acting beyond quadratic order in density, and making the resulting functional compatible with the Van-der-Waals theory of liquid-vapor coexistence at long range. Compared to available molecular simulations, the approach yields reasonable solvation structure and free energy of hard or soft spheres of increasing size, with a correct qualitative transition from a volume-driven to a surface-driven regime at the nanometer scale.

[Religion and brain functioning (part 1): are our mental structures designed for religion?].

PubMed

Kornreich, C; Neu, D

2010-01-01

Religions are seen everywhere in the world. Two main theories are competing to explain this phenomenon. The first one is based on the assumption that our cognitive structures are predisposing us to nurture religious beliefs. Religion would then be a by-product of mental functions useful for survival. Examples of these mental functions are children credulity, anthropomorphism and teleology. The second one hypothesizes that religion is maintained trough direct adaptation benefits occurring in cooperation exchanges. In particular, religion could function as an insurance mechanism given by the religious group. It is likely that both theories are complementary and useful to explain why religion is a universal phenomenon in the human species.

In Silico Modeling of Indigo and Tyrian Purple Single-Electron Nano-Transistors Using Density Functional Theory Approach

NASA Astrophysics Data System (ADS)

Shityakov, Sergey; Roewer, Norbert; Förster, Carola; Broscheit, Jens-Albert

2017-07-01

The purpose of this study was to develop and implement an in silico model of indigoid-based single-electron transistor (SET) nanodevices, which consist of indigoid molecules from natural dye weakly coupled to gold electrodes that function in a Coulomb blockade regime. The electronic properties of the indigoid molecules were investigated using the optimized density-functional theory (DFT) with a continuum model. Higher electron transport characteristics were determined for Tyrian purple, consistent with experimentally derived data. Overall, these results can be used to correctly predict and emphasize the electron transport functions of organic SETs, demonstrating their potential for sustainable nanoelectronics comprising the biodegradable and biocompatible materials.

From the crust to the core of neutron stars on a microscopic basis

NASA Astrophysics Data System (ADS)

Baldo, M.; Burgio, G. F.; Centelles, M.; Sharma, B. K.; Viñas, X.

2014-09-01

Within a microscopic approach the structure of Neutron Stars is usually studied by modelling the homogeneous nuclear matter of the core by a suitable Equation of State, based on a many-body theory, and the crust by a functional based on a more phenomenological approach. We present the first calculation of Neutron Star overall structure by adopting for the core an Equation of State derived from the Brueckner-Hartree-Fock theory and for the crust, including the pasta phase, an Energy Density Functional based on the same Equation of State, and which is able to describe accurately the binding energy of nuclei throughout the mass table. Comparison with other approaches is discussed. The relevance of the crust Equation of State for the Neutron Star radius is particularly emphasised.

Information Resources Usage in Project Management Digital Learning System

ERIC Educational Resources Information Center

Davidovitch, Nitza; Belichenko, Margarita; Kravchenko, Yurii

2017-01-01

The article combines a theoretical approach to structuring knowledge that is based on the integrated use of fuzzy semantic network theory predicates, Boolean functions, theory of complexity of network structures and some practical aspects to be considered in the distance learning at the university. The paper proposes a methodological approach that…

Comparison of field theory models of interest rates with market data

NASA Astrophysics Data System (ADS)

Baaquie, Belal E.; Srikant, Marakani

2004-03-01

We calibrate and test various variants of field theory models of the interest rate with data from Eurodollar futures. Models based on psychological factors are seen to provide the best fit to the market. We make a model independent determination of the volatility function of the forward rates from market data.

Taking and Coordinating Perspectives: From Prereflective Interactivity, through Reflective Intersubjectivity, to Metareflective Sociality

ERIC Educational Resources Information Center

Martin, Jack; Sokol, Bryan W.; Elfers, Theo

2008-01-01

Despite being eclipsed in recent years by simulation theory, theory of mind and accounts of executive functioning, social-relational approaches to perspective taking and coordination based on the ideas of Jean Piaget and George Herbert Mead have never completely disappeared from the literature of developmental psychology. According to the…

School Discipline and Social Work Practice: Application of Research and Theory to Intervention

ERIC Educational Resources Information Center

Cameron, Mark; Sheppard, Sandra M.

2006-01-01

Research has identified a relationship between school disciplinary actions and poor academic and psychosocial functioning of students subjected to them. The ways in which school discipline is a direct contributor to students' academic and psychosocial difficulty needs to be further established empirically. Several theories, based in existing…

Ab initio theory of noble gas atoms in bcc transition metals

DOE PAGES

Jiang, Chao; Zhang, Yongfeng; Gao, Yipeng; ...

2018-01-01

Systematic ab initio calculations based on density functional theory have been performed to gain fundamental understanding of the interactions between noble gas atoms (He, Ne, Ar and Kr) and bcc transition metals in groups 5B (V, Nb and Ta), 6B (Cr, Mo and W) and 8B (Fe).

Full-band quantum simulation of electron devices with the pseudopotential method: Theory, implementation, and applications

NASA Astrophysics Data System (ADS)

Pala, M. G.; Esseni, D.

2018-03-01

This paper presents the theory, implementation, and application of a quantum transport modeling approach based on the nonequilibrium Green's function formalism and a full-band empirical pseudopotential Hamiltonian. We here propose to employ a hybrid real-space/plane-wave basis that results in a significant reduction of the computational complexity compared to a full plane-wave basis. To this purpose, we provide a theoretical formulation in the hybrid basis of the quantum confinement, the self-energies of the leads, and the coupling between the device and the leads. After discussing the theory and the implementation of the new simulation methodology, we report results for complete, self-consistent simulations of different electron devices, including a silicon Esaki diode, a thin-body silicon field effect transistor (FET), and a germanium tunnel FET. The simulated transistors have technologically relevant geometrical features with a semiconductor film thickness of about 4 nm and a channel length ranging from 10 to 17 nm. We believe that the newly proposed formalism may find applications also in transport models based on ab initio Hamiltonians, as those employed in density functional theory methods.

Design of vibration isolation systems using multiobjective optimization techniques

NASA Technical Reports Server (NTRS)

Rao, S. S.

1984-01-01

The design of vibration isolation systems is considered using multicriteria optimization techniques. The integrated values of the square of the force transmitted to the main mass and the square of the relative displacement between the main mass and the base are taken as the performance indices. The design of a three degrees-of-freedom isolation system with an exponentially decaying type of base disturbance is considered for illustration. Numerical results are obtained using the global criterion, utility function, bounded objective, lexicographic, goal programming, goal attainment and game theory methods. It is found that the game theory approach is superior in finding a better optimum solution with proper balance of the various objective functions.

Multiphase aluminum equations of state via density functional theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sjostrom, Travis; Crockett, Scott; Rudin, Sven

2016-10-03

We have performed density functional theory (DFT) based calculations for aluminum in extreme conditions of both pressure and temperature, up to five times compressed ambient density, and over 1 000 000 K in temperature. In order to cover such a domain, DFT methods including phonon calculations, quantum molecular dynamics, and orbital-free DFT are employed. Our results are then used to construct a SESAME equation of state for the aluminum 1100 alloy, encompassing the fcc, hcp, and bcc solid phases as well as the liquid regime. We also provide extensive comparison with experiment, and based on this we also provide amore » slightly modified equation of state for the aluminum 6061 alloy.« less

A second-order accurate kinetic-theory-based method for inviscid compressible flows

NASA Technical Reports Server (NTRS)

Deshpande, Suresh M.

1986-01-01

An upwind method for the numerical solution of the Euler equations is presented. This method, called the kinetic numerical method (KNM), is based on the fact that the Euler equations are moments of the Boltzmann equation of the kinetic theory of gases when the distribution function is Maxwellian. The KNM consists of two phases, the convection phase and the collision phase. The method is unconditionally stable and explicit. It is highly vectorizable and can be easily made total variation diminishing for the distribution function by a suitable choice of the interpolation strategy. The method is applied to a one-dimensional shock-propagation problem and to a two-dimensional shock-reflection problem.

A comparison of design variables for control theory based airfoil optimization

NASA Technical Reports Server (NTRS)

Reuther, James; Jameson, Antony

1995-01-01

This paper describes the implementation of optimization techniques based on control theory for airfoil design. In our previous work in the area it was shown that control theory could be employed to devise effective optimization procedures for two-dimensional profiles by using either the potential flow or the Euler equations with either a conformal mapping or a general coordinate system. We have also explored three-dimensional extensions of these formulations recently. The goal of our present work is to demonstrate the versatility of the control theory approach by designing airfoils using both Hicks-Henne functions and B-spline control points as design variables. The research also demonstrates that the parameterization of the design space is an open question in aerodynamic design.

Tried and True: Self-Regulation Theory as a Guiding Framework for Teaching Parents Diabetes Education Using Human Patient Simulation

PubMed Central

Sullivan-Bolyai, Susan; Johnson, Kimberly; Cullen, Karen; Hamm, Terry; Bisordi, Jean; Blaney, Kathleen; Maguire, Laura; Melkus, Gail

2014-01-01

Parents become emotionally upset when learning their child has Type 1 Diabetes, yet they are expected to quickly learn functional diabetes management. The purpose of this article is to describe the application of Self-Regulation theory to guide a family-focused education intervention using human patient simulation to enhance the initial education of parents in diabetes management. A brief description is provided of the intervention framed by Self-Regulation theory. Based on the literature, we describe the educational vignettes used based on Self-Regulation in the randomized controlled trial entitled Parent Education Through Simulation-Diabetes. Examples of theory-in-practice will be illustrated by parental learning responses to this alternative educational innovation. PMID:25365286

Tetragonal and collapsed-tetragonal phases of CaFe2As2 : A view from angle-resolved photoemission and dynamical mean-field theory

NASA Astrophysics Data System (ADS)

van Roekeghem, Ambroise; Richard, Pierre; Shi, Xun; Wu, Shangfei; Zeng, Lingkun; Saparov, Bayrammurad; Ohtsubo, Yoshiyuki; Qian, Tian; Sefat, Athena S.; Biermann, Silke; Ding, Hong

2016-06-01

We present a study of the tetragonal to collapsed-tetragonal transition of CaFe2As2 using angle-resolved photoemission spectroscopy and dynamical mean field theory-based electronic structure calculations. We observe that the collapsed-tetragonal phase exhibits reduced correlations and a higher coherence temperature due to the stronger Fe-As hybridization. Furthermore, a comparison of measured photoemission spectra and theoretical spectral functions shows that momentum-dependent corrections to the density functional band structure are essential for the description of low-energy quasiparticle dispersions. We introduce those using the recently proposed combined "screened exchange + dynamical mean field theory" scheme.

Benchmarking Density Functional Theory Based Methods To Model NiOOH Material Properties: Hubbard and van der Waals Corrections vs Hybrid Functionals.

PubMed

Zaffran, Jeremie; Caspary Toroker, Maytal

2016-08-09

NiOOH has recently been used to catalyze water oxidation by way of electrochemical water splitting. Few experimental data are available to rationalize the successful catalytic capability of NiOOH. Thus, theory has a distinctive role for studying its properties. However, the unique layered structure of NiOOH is associated with the presence of essential dispersion forces within the lattice. Hence, the choice of an appropriate exchange-correlation functional within Density Functional Theory (DFT) is not straightforward. In this work, we will show that standard DFT is sufficient to evaluate the geometry, but DFT+U and hybrid functionals are required to calculate the oxidation states. Notably, the benefit of DFT with van der Waals correction is marginal. Furthermore, only hybrid functionals succeed in opening a bandgap, and such methods are necessary to study NiOOH electronic structure. In this work, we expect to give guidelines to theoreticians dealing with this material and to present a rational approach in the choice of the DFT method of calculation.

Current Density Functional Theory Using Meta-Generalized Gradient Exchange-Correlation Functionals.

PubMed

Furness, James W; Verbeke, Joachim; Tellgren, Erik I; Stopkowicz, Stella; Ekström, Ulf; Helgaker, Trygve; Teale, Andrew M

2015-09-08

We present the self-consistent implementation of current-dependent (hybrid) meta-generalized gradient approximation (mGGA) density functionals using London atomic orbitals. A previously proposed generalized kinetic energy density is utilized to implement mGGAs in the framework of Kohn-Sham current density functional theory (KS-CDFT). A unique feature of the nonperturbative implementation of these functionals is the ability to seamlessly explore a wide range of magnetic fields up to 1 au (∼235 kT) in strength. CDFT functionals based on the TPSS and B98 forms are investigated, and their performance is assessed by comparison with accurate coupled-cluster singles, doubles, and perturbative triples (CCSD(T)) data. In the weak field regime, magnetic properties such as magnetizabilities and nuclear magnetic resonance shielding constants show modest but systematic improvements over generalized gradient approximations (GGA). However, in the strong field regime, the mGGA-based forms lead to a significantly improved description of the recently proposed perpendicular paramagnetic bonding mechanism, comparing well with CCSD(T) data. In contrast to functionals based on the vorticity, these forms are found to be numerically stable, and their accuracy at high field suggests that the extension of mGGAs to CDFT via the generalized kinetic energy density should provide a useful starting point for further development of CDFT approximations.

Active vibration control of functionally graded beams with piezoelectric layers based on higher order shear deformation theory

NASA Astrophysics Data System (ADS)

Bendine, K.; Boukhoulda, F. B.; Nouari, M.; Satla, Z.

2016-12-01

This paper reports on a study of active vibration control of functionally graded beams with upper and lower surface-bonded piezoelectric layers. The model is based on higher-order shear deformation theory and implemented using the finite element method (FEM). The proprieties of the functionally graded beam (FGB) are graded along the thickness direction. The piezoelectric actuator provides a damping effect on the FGB by means of a velocity feedback control algorithm. A Matlab program has been developed for the FGB model and compared with ANSYS APDL. Using Newmark's method numerical solutions are obtained for the dynamic equations of FGB with piezoelectric layers. Numerical results show the effects of the constituent volume fraction and the influence the feedback control gain on the frequency and dynamic response of FGBs.

Applicability of Kerker preconditioning scheme to the self-consistent density functional theory calculations of inhomogeneous systems

NASA Astrophysics Data System (ADS)

Zhou, Yuzhi; Wang, Han; Liu, Yu; Gao, Xingyu; Song, Haifeng

2018-03-01

The Kerker preconditioner, based on the dielectric function of homogeneous electron gas, is designed to accelerate the self-consistent field (SCF) iteration in the density functional theory calculations. However, a question still remains regarding its applicability to the inhomogeneous systems. We develop a modified Kerker preconditioning scheme which captures the long-range screening behavior of inhomogeneous systems and thus improves the SCF convergence. The effectiveness and efficiency is shown by the tests on long-z slabs of metals, insulators, and metal-insulator contacts. For situations without a priori knowledge of the system, we design the a posteriori indicator to monitor if the preconditioner has suppressed charge sloshing during the iterations. Based on the a posteriori indicator, we demonstrate two schemes of the self-adaptive configuration for the SCF iteration.

Nonlinear constitutive theory for turbine engine structural analysis

NASA Technical Reports Server (NTRS)

Thompson, R. L.

1982-01-01

A number of viscoplastic constitutive theories and a conventional constitutive theory are evaluated and compared in their ability to predict nonlinear stress-strain behavior in gas turbine engine components at elevated temperatures. Specific application of these theories is directed towards the structural analysis of combustor liners undergoing transient, cyclic, thermomechanical load histories. The combustor liner material considered in this study is Hastelloy X. The material constants for each of the theories (as a function of temperature) are obtained from existing, published experimental data. The viscoplastic theories and a conventional theory are incorporated into a general purpose, nonlinear, finite element computer program. Several numerical examples of combustor liner structural analysis using these theories are given to demonstrate their capabilities. Based on the numerical stress-strain results, the theories are evaluated and compared.

FDE-vdW: A van der Waals inclusive subsystem density-functional theory.

PubMed

Kevorkyants, Ruslan; Eshuis, Henk; Pavanello, Michele

2014-07-28

We present a formally exact van der Waals inclusive electronic structure theory, called FDE-vdW, based on the Frozen Density Embedding formulation of subsystem Density-Functional Theory. In subsystem DFT, the energy functional is composed of subsystem additive and non-additive terms. We show that an appropriate definition of the long-range correlation energy is given by the value of the non-additive correlation functional. This functional is evaluated using the fluctuation-dissipation theorem aided by a formally exact decomposition of the response functions into subsystem contributions. FDE-vdW is derived in detail and several approximate schemes are proposed, which lead to practical implementations of the method. We show that FDE-vdW is Casimir-Polder consistent, i.e., it reduces to the generalized Casimir-Polder formula for asymptotic inter-subsystems separations. Pilot calculations of binding energies of 13 weakly bound complexes singled out from the S22 set show a dramatic improvement upon semilocal subsystem DFT, provided that an appropriate exchange functional is employed. The convergence of FDE-vdW with basis set size is discussed, as well as its dependence on the choice of associated density functional approximant.

FDE-vdW: A van der Waals inclusive subsystem density-functional theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kevorkyants, Ruslan; Pavanello, Michele, E-mail: m.pavanello@rutgers.edu; Eshuis, Henk

2014-07-28

We present a formally exact van der Waals inclusive electronic structure theory, called FDE-vdW, based on the Frozen Density Embedding formulation of subsystem Density-Functional Theory. In subsystem DFT, the energy functional is composed of subsystem additive and non-additive terms. We show that an appropriate definition of the long-range correlation energy is given by the value of the non-additive correlation functional. This functional is evaluated using the fluctuation–dissipation theorem aided by a formally exact decomposition of the response functions into subsystem contributions. FDE-vdW is derived in detail and several approximate schemes are proposed, which lead to practical implementations of the method.more » We show that FDE-vdW is Casimir-Polder consistent, i.e., it reduces to the generalized Casimir-Polder formula for asymptotic inter-subsystems separations. Pilot calculations of binding energies of 13 weakly bound complexes singled out from the S22 set show a dramatic improvement upon semilocal subsystem DFT, provided that an appropriate exchange functional is employed. The convergence of FDE-vdW with basis set size is discussed, as well as its dependence on the choice of associated density functional approximant.« less

The effect of different π-bridge configuration on bi-anchored triphenylamine and phenyl modified triphenylamine based dyes for dye sensitized solar cell (DSSC) application: A theoretical approach.

PubMed

Pounraj, P; Mohankumar, V; Pandian, M Senthil; Ramasamy, P

2018-01-01

Twenty eight bi-anchored triphenylamine (TH-1 to TH-14) and phenyl modified triphenylamine (PH-TH-1 to PH-TH-14) based metal free organic dyes are designed for DSSC application. The electronic effect of different π-bridge configurations in donor-π-bridge-acceptor (D-π-A) 2 structure was theoretically simulated and verified using density functional theory (DFT) and time dependent density functional theory (TD-DFT). The triphenylamine and phenyl modified triphenylamine groups are used as donor and cyanoacrylic acid group is used as acceptor. Thiophene and cyanovinyl groups are used as π-bridge. The ground state molecular structure was optimized by density functional theory and the electronic absorption spectra were calculated by time dependent density functional theory. The light harvesting efficiency (LHE), dye regeneration energy (ΔG reg ) and electron injection energy (ΔG inject ) are determined by computational examination. It is observed that, when the number of π-bridge increases, the band gap of the dye decreases. Also the absorption maximum and molar extinction coefficient of the dyes are increased. Theoretical result shows that the thiophene-cyanovinyl and thiophene-thiophene-cyanovinyl-cyanovinyl configurations give broader and red shifted absorption spectrum compared to other configurations. Also the results of phenyl modified triphenylamine (PH-TH) dyes clearly show better absorption and dye regeneration energy compared to TH dyes. Copyright © 2017 Elsevier Inc. All rights reserved.

Assessment of ten density functionals through the use of local hyper-softness to get insights about the catalytic activity : Iron-based organometallic compounds for ethylene polymerization as testing molecules.

PubMed

Martínez-Araya, Jorge I; Glossman-Mitnik, Daniel

2018-01-18

Ten functionals were used to assess their capability to compute a local reactivity descriptor coming from the Conceptual Density Functional Theory on a group of iron-based organometallic compounds that have been synthesized by Zohuri, G.H. et al. in 2010; these compounds bear the following substituent groups: H-, O 2 N- and CH 3 O- at the para position of the pyridine ring and their catalytic activities were experimentally measured by these authors. The present work involved a theoretical analysis applied on the aforementioned iron-based compounds thus leading to suggest a new 2,6-bis(imino)pyridine catalyst based on iron(II) bearing a fluorine atom whose possible catalytic activity is suggested to be near the catalytic activity of the complex bearing a hydrogen atom as a substituent group by means of the so called local hyper-softness (LHS) thus opening a chance to estimate a possible value of catalytic activity for a new catalyst that has not been synthesized yet without simulating the entire process of ethylene polymerization. Since Conceptual DFT is not a predictive theory, but rather interpretative, an analysis of the used reactivity descriptor and its dependence upon the level of theory was carried in the present work, thus revealing that care should be taken when DFT calculations are used for these purposes.

[Effects of a Multi-disciplinary Approached, Empowerment Theory Based Self-management Intervention in Older Adults with Chronic Illness].

PubMed

Park, Chorong; Song, Misoon; Cho, Belong; Lim, Jaeyoung; Song, Wook; Chang, Heekyung; Park, Yeon-Hwan

2015-04-01

The purpose of this study was to develop a multi-disciplinary self-management intervention based on empowerment theory and to evaluate the effectiveness of the intervention for older adults with chronic illness. A randomized controlled trial design was used with 43 Korean older adults with chronic illness (Experimental group=22, Control group=21). The intervention consisted of two phases: (1) 8-week multi-disciplinary, team guided, group-based health education, exercise session, and individual empowerment counseling, (2) 16-week self-help group activities including weekly exercise and group discussion to maintain acquired self-management skills and problem-solving skills. Baseline, 8-week, and 24-week assessments measured health empowerment, exercise self-efficacy, physical activity, and physical function. Health empowerment, physical activity, and physical function in the experimental group increased significantly compared to the control group over time. Exercise self-efficacy significantly increased in experimental group over time but there was no significant difference between the two groups. The self-management program based on empowerment theory improved health empowerment, physical activity, and physical function in older adults. The study finding suggests that a health empowerment strategy may be an effective approach for older adults with multiple chronic illnesses in terms of achieving a sense of control over their chronic illness and actively engaging self-management.

Some applications of mathematics in theoretical physics - A review

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bora, Kalpana

2016-06-21

Mathematics is a very beautiful subject−very much an indispensible tool for Physics, more so for Theoretical Physics (by which we mean here mainly Field Theory and High Energy Physics). These branches of Physics are based on Quantum Mechanics and Special Theory of Relativity, and many mathematical concepts are used in them. In this work, we shall elucidate upon only some of them, like−differential geometry, infinite series, Mellin transforms, Fourier and integral transforms, special functions, calculus, complex algebra, topology, group theory, Riemannian geometry, functional analysis, linear algebra, operator algebra, etc. We shall also present, some physics issues, where these mathematical toolsmore » are used. It is not wrong to say that Mathematics is such a powerful tool, without which, there can not be any Physics theory!! A brief review on our research work is also presented.« less

Theoretical study on the sound absorption of electrolytic solutions. I. Theoretical formulation.

PubMed

Yamaguchi, T; Matsuoka, T; Koda, S

2007-04-14

A theory is formulated that describes the sound absorption of electrolytic solutions due to the relative motion of ions, including the formation of ion pairs. The theory is based on the Kubo-Green formula for the bulk viscosity. The time correlation function of the pressure is projected onto the bilinear product of the density modes of ions. The time development of the product of density modes is described by the diffusive limit of the generalized Langevin equation, and approximate expressions for the three- and four-body correlation functions required are given with the hypernetted-chain integral equation theory. Calculations on the aqueous solutions of model electrolytes are performed. It is demonstrated that the theory describes both the activated barrier crossing between contact and solvent-separated ion pairs and the Coulombic correlation between ions.

Theoretical study on the sound absorption of electrolytic solutions. I. Theoretical formulation

NASA Astrophysics Data System (ADS)

Yamaguchi, T.; Matsuoka, T.; Koda, S.

2007-04-01

A theory is formulated that describes the sound absorption of electrolytic solutions due to the relative motion of ions, including the formation of ion pairs. The theory is based on the Kubo-Green formula for the bulk viscosity. The time correlation function of the pressure is projected onto the bilinear product of the density modes of ions. The time development of the product of density modes is described by the diffusive limit of the generalized Langevin equation, and approximate expressions for the three- and four-body correlation functions required are given with the hypernetted-chain integral equation theory. Calculations on the aqueous solutions of model electrolytes are performed. It is demonstrated that the theory describes both the activated barrier crossing between contact and solvent-separated ion pairs and the Coulombic correlation between ions.

Stimulus overselectivity four decades later: a review of the literature and its implications for current research in autism spectrum disorder.

PubMed

Ploog, Bertram O

2010-11-01

This review of several topics related to "stimulus overselectivity" (Lovaas et al., J Abnormal Psychol 77:211-222, 1971) has three main purposes: (1) To outline the factors that may contribute to overselectivity; (2) to link the behavior-analytical notion of overselectivity to current nonbehavior-analytical research and theory; and (3) to suggest remedial strategies based on the behavior-analytical approach. While it is clear that overselectivity is not specific to autism spectrum disorder (ASD) and also that not all persons with ASD exhibit overselectivity, it is prevalent in ASD and has critical implications for symptoms, treatment, research, and theory. Weak Central Coherence and Enhanced Perceptual Functioning theories are briefly considered. The research areas addressed here include theory of mind, joint attention, language development, and executive function.

Some applications of mathematics in theoretical physics - A review

NASA Astrophysics Data System (ADS)

Bora, Kalpana

2016-06-01

Mathematics is a very beautiful subject-very much an indispensible tool for Physics, more so for Theoretical Physics (by which we mean here mainly Field Theory and High Energy Physics). These branches of Physics are based on Quantum Mechanics and Special Theory of Relativity, and many mathematical concepts are used in them. In this work, we shall elucidate upon only some of them, like-differential geometry, infinite series, Mellin transforms, Fourier and integral transforms, special functions, calculus, complex algebra, topology, group theory, Riemannian geometry, functional analysis, linear algebra, operator algebra, etc. We shall also present, some physics issues, where these mathematical tools are used. It is not wrong to say that Mathematics is such a powerful tool, without which, there can not be any Physics theory!! A brief review on our research work is also presented.

Teaching about the U.S. Constitution through Metaphor: Government as a Machine.

ERIC Educational Resources Information Center

Mills, Randy K.

1988-01-01

Briefly reviews theories of brain hemisphere functions and draws implications for social studies instruction. Maintains that the metaphor aids the development of understanding because it connects right and left brain functions. Provides a learning activity based on the metaphor of the U.S. government functioning as a machine. (BSR)

Lattice dynamics calculations based on density-functional perturbation theory in real space

NASA Astrophysics Data System (ADS)

Shang, Honghui; Carbogno, Christian; Rinke, Patrick; Scheffler, Matthias

2017-06-01

A real-space formalism for density-functional perturbation theory (DFPT) is derived and applied for the computation of harmonic vibrational properties in molecules and solids. The practical implementation using numeric atom-centered orbitals as basis functions is demonstrated exemplarily for the all-electron Fritz Haber Institute ab initio molecular simulations (FHI-aims) package. The convergence of the calculations with respect to numerical parameters is carefully investigated and a systematic comparison with finite-difference approaches is performed both for finite (molecules) and extended (periodic) systems. Finally, the scaling tests and scalability tests on massively parallel computer systems demonstrate the computational efficiency.

A DYNAMIC DENSITY FUNCTIONAL THEORY APPROACH TO DIFFUSION IN WHITE DWARFS AND NEUTRON STAR ENVELOPES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Diaw, A.; Murillo, M. S.

2016-09-20

We develop a multicomponent hydrodynamic model based on moments of the Born–Bogolyubov–Green–Kirkwood–Yvon hierarchy equations for physical conditions relevant to astrophysical plasmas. These equations incorporate strong correlations through a density functional theory closure, while transport enters through a relaxation approximation. This approach enables the introduction of Coulomb coupling correction terms into the standard Burgers equations. The diffusive currents for these strongly coupled plasmas is self-consistently derived. The settling of impurities and its impact on cooling can be greatly affected by strong Coulomb coupling, which we show can be quantified using the direct correlation function.

Optimization of an exchange-correlation density functional for water

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fritz, Michelle; Fernández-Serra, Marivi; Institute for Advanced Computational Science, Stony Brook University, Stony Brook, New York 11794-3800

2016-06-14

We describe a method, that we call data projection onto parameter space (DPPS), to optimize an energy functional of the electron density, so that it reproduces a dataset of experimental magnitudes. Our scheme, based on Bayes theorem, constrains the optimized functional not to depart unphysically from existing ab initio functionals. The resulting functional maximizes the probability of being the “correct” parameterization of a given functional form, in the sense of Bayes theory. The application of DPPS to water sheds new light on why density functional theory has performed rather poorly for liquid water, on what improvements are needed, and onmore » the intrinsic limitations of the generalized gradient approximation to electron exchange and correlation. Finally, we present tests of our water-optimized functional, that we call vdW-DF-w, showing that it performs very well for a variety of condensed water systems.« less

A statistical mechanical theory of proton transport kinetics in hydrogen-bonded networks based on population correlation functions with applications to acids and bases.

PubMed

Tuckerman, Mark E; Chandra, Amalendu; Marx, Dominik

2010-09-28

Extraction of relaxation times, lifetimes, and rates associated with the transport of topological charge defects in hydrogen-bonded networks from molecular dynamics simulations is a challenge because proton transfer reactions continually change the identity of the defect core. In this paper, we present a statistical mechanical theory that allows these quantities to be computed in an unbiased manner. The theory employs a set of suitably defined indicator or population functions for locating a defect structure and their associated correlation functions. These functions are then used to develop a chemical master equation framework from which the rates and lifetimes can be determined. Furthermore, we develop an integral equation formalism for connecting various types of population correlation functions and derive an iterative solution to the equation, which is given a graphical interpretation. The chemical master equation framework is applied to the problems of both hydronium and hydroxide transport in bulk water. For each case it is shown that the theory establishes direct links between the defect's dominant solvation structures, the kinetics of charge transfer, and the mechanism of structural diffusion. A detailed analysis is presented for aqueous hydroxide, examining both reorientational time scales and relaxation of the rotational anisotropy, which is correlated with recent experimental results for these quantities. Finally, for OH(-)(aq) it is demonstrated that the "dynamical hypercoordination mechanism" is consistent with available experimental data while other mechanistic proposals are shown to fail. As a means of going beyond the linear rate theory valid from short up to intermediate time scales, a fractional kinetic model is introduced in the Appendix in order to describe the nonexponential long-time behavior of time-correlation functions. Within the mathematical framework of fractional calculus the power law decay ∼t(-σ), where σ is a parameter of the model and depends on the dimensionality of the system, is obtained from Mittag-Leffler functions due to their long-time asymptotics, whereas (stretched) exponential behavior is found for short times.

Hole localization in Fe2O3 from density functional theory and wave-function-based methods

NASA Astrophysics Data System (ADS)

Ansari, Narjes; Ulman, Kanchan; Camellone, Matteo Farnesi; Seriani, Nicola; Gebauer, Ralph; Piccinin, Simone

2017-08-01

Hematite (α -Fe2O3 ) is a promising photocatalyst material for water splitting, where photoinduced holes lead to the oxidation of water and the release of molecular oxygen. In this work, we investigate the properties of holes in hematite using density functional theory (DFT) calculations with hybrid functionals. We find that holes form small polarons and, depending on the fraction of exact exchange included in the PBE0 functional, the site where the holes localize changes from Fe to O. We find this result to be independent of the size and structure of the system: small Fe2O3 clusters with tetrahedral coordination, larger clusters with octahedral coordination, Fe2O3 (001) surfaces in contact with water, and bulk Fe2O3 display a very similar behavior in terms of hole localization as a function of the fraction of exact exchange. We then use wave-function-based methods such as coupled cluster with single and double excitations and Møller-Plesset second-order perturbation theory applied on a cluster model of Fe2O3 to shed light on which of the two solutions is correct. We find that these high-level quantum chemistry methods suggest holes in hematite are localized on oxygen atoms. We also explore the use of the DFT +U approach as a computationally convenient way to overcome the known limitations of generalized gradient approximation functionals and recover a gap in line with experiments and hole localization on oxygen in agreement with quantum chemistry methods.

Regarding the use and misuse of retinal protonated Schiff base photochemistry as a test case for time-dependent density-functional theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Valsson, Omar; Filippi, Claudia, E-mail: c.filippi@utwente.nl; Casida, Mark E., E-mail: mark.casida@ujf-grenoble.fr

2015-04-14

The excited-state relaxation of retinal protonated Schiff bases (PSBs) is an important test case for biological applications of time-dependent (TD) density-functional theory (DFT). While well-known shortcomings of approximate TD-DFT might seem discouraging for application to PSB relaxation, progress continues to be made in the development of new functionals and of criteria allowing problematic excitations to be identified within the framework of TD-DFT itself. Furthermore, experimental and theoretical ab initio advances have recently lead to a revised understanding of retinal PSB photochemistry, calling for a reappraisal of the performance of TD-DFT in describing this prototypical photoactive system. Here, we re-investigate themore » performance of functionals in (TD-)DFT calculations in light of these new benchmark results, which we extend to larger PSB models. We focus on the ability of the functionals to describe primarily the early skeletal relaxation of the chromophore and investigate how far along the out-of-plane pathways these functionals are able to describe the subsequent rotation around formal single and double bonds. Conventional global hybrid and range-separated hybrid functionals are investigated as the presence of Hartree-Fock exchange reduces problems with charge-transfer excitations as determined by the Peach-Benfield-Helgaker-Tozer Λ criterion and by comparison with multi-reference perturbation theory results. While we confirm that most functionals cannot render the complex photobehavior of the retinal PSB, do we also observe that LC-BLYP gives the best description of the initial part of the photoreaction.« less

5-brane webs for 5d N = 1 G 2 gauge theories

NASA Astrophysics Data System (ADS)

Hayashi, Hirotaka; Kim, Sung-Soo; Lee, Kimyeong; Yagi, Futoshi

2018-03-01

We propose 5-brane webs for 5d N = 1 G 2 gauge theories. From a Higgsing of the SO(7) gauge theory with a hypermultiplet in the spinor representation, we construct two types of 5-brane web configurations for the pure G 2 gauge theory using an O5-plane or an \\tilde{O5} -plane. Adding flavors to the 5-brane web for the pure G 2 gauge theory is also discussed. Based on the obtained 5-brane webs, we compute the partition functions for the 5d G 2 gauge theories using the recently suggested topological vertex formulation with an O5-plane, and we find agreement with known results.

Intrinsic or Extrinsic? Using Videogames to Motivate Stroke Survivors: A Systematic Review.

PubMed

Swanson, LaTasha R; Whittinghill, David M

2015-06-01

The main objective of this study was to explore, via a systematic review of available literature, the effectiveness of videogame-based rehabilitation interventions on the motivation and health outcomes of stroke patients. Using a systematic literature review of 18 articles, we sought to address three key research questions: (1) Do videogames improve function or health outcomes among stroke survivors? (2) Do videogames increase stroke patients' motivation to engage in rehabilitation exercise and activities? (3) Which motivational techniques, principles, and theoretical frameworks have been applied in the reviewed studies? A key word search was conducted, and articles were coded for inclusion of motivational theories or principles, intervention effectiveness, and participants' motivation to perform tasks. Three motivational frameworks and principles were used (self-determination theory [SDT], flow theory, and operant conditioning) to investigate intrinsic and extrinsic approaches. Past research suggests videogame-based interventions are effective at improving and increasing a variety of health-related outcomes, including motor functioning, energy expenditure, muscle strength, and recovery times in stroke patients. Past evidence shows videogame-based interventions are a promising tool to motivate stroke patients' engagement in effective rehabilitation activities. This study also identifies an opportunity for future research to apply motivational theories from SDT to studies on stroke rehabilitation and videogames.

Coordination of fractional-order nonlinear multi-agent systems via distributed impulsive control

NASA Astrophysics Data System (ADS)

Ma, Tiedong; Li, Teng; Cui, Bing

2018-01-01

The coordination of fractional-order nonlinear multi-agent systems via distributed impulsive control method is studied in this paper. Based on the theory of impulsive differential equations, algebraic graph theory, Lyapunov stability theory and Mittag-Leffler function, two novel sufficient conditions for achieving the cooperative control of a class of fractional-order nonlinear multi-agent systems are derived. Finally, two numerical simulations are verified to illustrate the effectiveness and feasibility of the proposed method.

Operationalizing Levels of Academic Mastery Based on Vygotsky’s Theory

PubMed Central

Nezhnov, Peter; Kardanova, Elena; Ludlow, Larry

2014-01-01

The present study tested the possibility of operationalizing levels of knowledge acquisition based on Vygotsky’s theory of cognitive growth. An assessment tool (SAM-Math) was developed to capture a hypothesized hierarchical structure of mathematical knowledge consisting of procedural, conceptual, and functional levels. In Study 1, SAM-Math was administered to 4th-grade students (N = 2,216). The results of Rasch analysis indicated that the test provided an operational definition for the construct of mathematical competence that included the three levels of mastery corresponding to the theoretically based hierarchy of knowledge. In Study 2, SAM-Math was administered to students in 4th, 6th, 8th, and 10th grades (N = 396) to examine developmental changes in the levels of mathematics knowledge. The results showed that the mastery of mathematical concepts presented in elementary school continued to deepen beyond elementary school, as evidenced by a significant growth in conceptual and functional levels of knowledge. The findings are discussed in terms of their implications for psychological theory, test design, and educational practice. PMID:29795820

Brain Graph Topology Changes Associated with Anti-Epileptic Drug Use

PubMed Central

Levin, Harvey S.; Chiang, Sharon

2015-01-01

Abstract Neuroimaging studies of functional connectivity using graph theory have furthered our understanding of the network structure in temporal lobe epilepsy (TLE). Brain network effects of anti-epileptic drugs could influence such studies, but have not been systematically studied. Resting-state functional MRI was analyzed in 25 patients with TLE using graph theory analysis. Patients were divided into two groups based on anti-epileptic medication use: those taking carbamazepine/oxcarbazepine (CBZ/OXC) (n=9) and those not taking CBZ/OXC (n=16) as a part of their medication regimen. The following graph topology metrics were analyzed: global efficiency, betweenness centrality (BC), clustering coefficient, and small-world index. Multiple linear regression was used to examine the association of CBZ/OXC with graph topology. The two groups did not differ from each other based on epilepsy characteristics. Use of CBZ/OXC was associated with a lower BC. Longer epilepsy duration was also associated with a lower BC. These findings can inform graph theory-based studies in patients with TLE. The changes observed are discussed in relation to the anti-epileptic mechanism of action and adverse effects of CBZ/OXC. PMID:25492633

Semiclassical Path Integral Calculation of Nonlinear Optical Spectroscopy.

PubMed

Provazza, Justin; Segatta, Francesco; Garavelli, Marco; Coker, David F

2018-02-13

Computation of nonlinear optical response functions allows for an in-depth connection between theory and experiment. Experimentally recorded spectra provide a high density of information, but to objectively disentangle overlapping signals and to reach a detailed and reliable understanding of the system dynamics, measurements must be integrated with theoretical approaches. Here, we present a new, highly accurate and efficient trajectory-based semiclassical path integral method for computing higher order nonlinear optical response functions for non-Markovian open quantum systems. The approach is, in principle, applicable to general Hamiltonians and does not require any restrictions on the form of the intrasystem or system-bath couplings. This method is systematically improvable and is shown to be valid in parameter regimes where perturbation theory-based methods qualitatively breakdown. As a test of the methodology presented here, we study a system-bath model for a coupled dimer for which we compare against numerically exact results and standard approximate perturbation theory-based calculations. Additionally, we study a monomer with discrete vibronic states that serves as the starting point for future investigation of vibronic signatures in nonlinear electronic spectroscopy.

Exact exchange and Wilson-Levy correlation: a pragmatic device for studying complex weakly-bonded systems.

PubMed

Walsh, T R

2005-02-07

The Wilson-Levy (WL) correlation functional is used together with Hartree-Fock (HF) theory to evaluate interaction energies at intermediate separations (i.e. around equilibrium separation) for several weakly-bonded systems. The HF+WL approach reproduces binding trends for all complexes studied: selected rare-gas dimers, isomers of the methane dimer, benzene dimer and naphthalene dimer, and base-pair stacking structures for pyrimidine, cytosine, uracil and guanine dimers. These HF+WL data are contrasted against results obtained from some popular functionals (including B3LYP and PBE), as well as two newly-developed functionals, X3LYP and xPBE. The utility of HF+WL, with reference to exact-exchange (EXX) density-functional theory, is discussed in terms of a suggested EXXWL exchange-correlation functional.

A Site Density Functional Theory for Water: Application to Solvation of Amino Acid Side Chains.

PubMed

Liu, Yu; Zhao, Shuangliang; Wu, Jianzhong

2013-04-09

We report a site density functional theory (SDFT) based on the conventional atomistic models of water and the universality ansatz of the bridge functional. The excess Helmholtz energy functional is formulated in terms of a quadratic expansion with respect to the local density deviation from that of a uniform system and a universal functional for all higher-order terms approximated by that of a reference hard-sphere system. With the atomistic pair direct correlation functions of the uniform system calculated from MD simulation and an analytical expression for the bridge functional from the modified fundamental measure theory, the SDFT can be used to predict the structure and thermodynamic properties of water under inhomogeneous conditions with a computational cost negligible in comparison to that of brute-force simulations. The numerical performance of the SDFT has been demonstrated with the predictions of the solvation free energies of 15 molecular analogs of amino acid side chains in water represented by SPC/E, SPC, and TIP3P models. For theTIP3P model, a comparison of the theoretical predictions with MD simulation and experimental data shows agreement within 0.64 and 1.09 kcal/mol on average, respectively.

On irregular singularity wave functions and superconformal indices

NASA Astrophysics Data System (ADS)

Buican, Matthew; Nishinaka, Takahiro

2017-09-01

We generalize, in a manifestly Weyl-invariant way, our previous expressions for irregular singularity wave functions in two-dimensional SU(2) q-deformed Yang-Mills theory to SU( N). As an application, we give closed-form expressions for the Schur indices of all ( A N - 1 , A N ( n - 1)-1) Argyres-Douglas (AD) superconformal field theories (SCFTs), thus completing the computation of these quantities for the ( A N , A M ) SCFTs. With minimal effort, our wave functions also give new Schur indices of various infinite sets of "Type IV" AD theories. We explore the discrete symmetries of these indices and also show how highly intricate renormalization group (RG) flows from isolated theories and conformal manifolds in the ultraviolet to isolated theories and (products of) conformal manifolds in the infrared are encoded in these indices. We compare our flows with dimensionally reduced flows via a simple "monopole vev RG" formalism. Finally, since our expressions are given in terms of concise Lie algebra data, we speculate on extensions of our results that might be useful for probing the existence of hypothetical SCFTs based on other Lie algebras. We conclude with a discussion of some open problems.

Density functional theory calculations of the water interactions with ZrO2 nanoparticles Y2O3 doped

NASA Astrophysics Data System (ADS)

Subhoni, Mekhrdod; Kholmurodov, Kholmirzo; Doroshkevich, Aleksandr; Asgerov, Elmar; Yamamoto, Tomoyuki; Lyubchyk, Andrei; Almasan, Valer; Madadzada, Afag

2018-03-01

Development of a new electricity generation techniques is one of the most relevant tasks, especially nowadays under conditions of extreme growth in energy consumption. The exothermic heterogeneous electrochemical energy conversion to the electric energy through interaction of the ZrO2 based nanopowder system with atmospheric moisture is one of the ways of electric energy obtaining. The questions of conversion into the electric form of the energy of water molecules adsorption in 3 mol% Y2O3 doped ZrO2 nanopowder systems were investigated using the density functional theory calculations. The density functional theory calculations has been realized as in the Kohn-Sham formulation, where the exchange-correlation potential is approximated by a functional of the electronic density. The electronic density, total energy and band structure calculations are carried out using the all-electron, full potential, linear augmented plane wave method of the electronic density and related approximations, i.e. the local density, the generalized gradient and their hybrid approximations.

Cryogenic terahertz spectrum of (+)-methamphetamine hydrochloride and assignment using solid-state density functional theory.

PubMed

Hakey, Patrick M; Allis, Damian G; Ouellette, Wayne; Korter, Timothy M

2009-04-30

The cryogenic terahertz spectrum of (+)-methamphetamine hydrochloride from 10.0 to 100.0 cm(-1) is presented, as is the complete structural analysis and vibrational assignment of the compound using solid-state density functional theory. This cryogenic investigation reveals multiple spectral features that were not previously reported in room-temperature terahertz studies of the title compound. Modeling of the compound employed eight density functionals utilizing both solid-state and isolated-molecule methods. The results clearly indicate the necessity of solid-state simulations for the accurate assignment of solid-state THz spectra. Assignment of the observed spectral features to specific atomic motions is based on the BP density functional, which provided the best-fit solid-state simulation of the experimental spectrum. The seven experimental spectral features are the result of thirteen infrared-active vibrational modes predicted at a BP/DNP level of theory with more than 90% of the total spectral intensity associated with external crystal vibrations.

Generalized quantum Fokker-Planck, diffusion, and Smoluchowski equations with true probability distribution functions.

PubMed

Banik, Suman Kumar; Bag, Bidhan Chandra; Ray, Deb Shankar

2002-05-01

Traditionally, quantum Brownian motion is described by Fokker-Planck or diffusion equations in terms of quasiprobability distribution functions, e.g., Wigner functions. These often become singular or negative in the full quantum regime. In this paper a simple approach to non-Markovian theory of quantum Brownian motion using true probability distribution functions is presented. Based on an initial coherent state representation of the bath oscillators and an equilibrium canonical distribution of the quantum mechanical mean values of their coordinates and momenta, we derive a generalized quantum Langevin equation in c numbers and show that the latter is amenable to a theoretical analysis in terms of the classical theory of non-Markovian dynamics. The corresponding Fokker-Planck, diffusion, and Smoluchowski equations are the exact quantum analogs of their classical counterparts. The present work is independent of path integral techniques. The theory as developed here is a natural extension of its classical version and is valid for arbitrary temperature and friction (the Smoluchowski equation being considered in the overdamped limit).

Similarities and Dissimilarities in Coauthorship Networks: Gestalt Theory as Explanation for Well-Ordered Collaboration Structures and Production of Scientific Literature.

ERIC Educational Resources Information Center

Kretschmer, Hildrun

2002-01-01

Based on Gestalt theory, the author assumes the existence of a field-force equilibrium to explain how, according to the conciseness principle, mathematically precise gestalts could exist in coauthorship networks. Develops a mathematical function to describe these gestalts in scientific literature and discusses structural characteristics of…

A Cue-Based Approach to "Theory of Mind": Re-Examining the Notion of Automaticity

ERIC Educational Resources Information Center

German, Tamsin C.; Cohen, Adam S.

2012-01-01

The potential utility of a distinction between "automatic (or spontaneous) and implicit" versus "controlled and explicit" processes in theory of mind (ToM) is undercut by the fact that the terms can be employed to describe different but related distinctions within cognitive systems serving that function. These include distinctions in the…

A Leonard-Sanders-Budiansky-Koiter-Type Nonlinear Shell Theory with a Hierarchy of Transverse-Shearing Deformations

NASA Technical Reports Server (NTRS)

Nemeth, Michael P.

2013-01-01

A detailed exposition on a refined nonlinear shell theory suitable for nonlinear buckling analyses of laminated-composite shell structures is presented. This shell theory includes the classical nonlinear shell theory attributed to Leonard, Sanders, Koiter, and Budiansky as an explicit proper subset. This approach is used in order to leverage the exisiting experience base and to make the theory attractive to industry. In addition, the formalism of general tensors is avoided in order to expose the details needed to fully understand and use the theory. The shell theory is based on "small" strains and "moderate" rotations, and no shell-thinness approximations are used. As a result, the strain-displacement relations are exact within the presumptions of "small" strains and "moderate" rotations. The effects of transverse-shearing deformations are included in the theory by using analyst-defined functions to describe the through-the-thickness distributions of transverse-shearing strains. Constitutive equations for laminated-composite shells are derived without using any shell-thinness approximations, and simplified forms and special cases are presented.

Germanium multiphase equation of state

DOE PAGES

Crockett, Scott D.; Lorenzi-Venneri, Giulia De; Kress, Joel D.; ...

2014-05-07

A new SESAME multiphase germanium equation of state (EOS) has been developed using the best available experimental data and density functional theory (DFT) calculations. The equilibrium EOS includes the Ge I (diamond), the Ge II (β-Sn) and the liquid phases. The foundation of the EOS is based on density functional theory calculations which are used to determine the cold curve and the Debye temperature. Results are compared to Hugoniot data through the solid-solid and solid-liquid transitions. We propose some experiments to better understand the dynamics of this element

First-principles Theory of Inelastic Transport and Local Heating in Atomic Gold Wires

NASA Astrophysics Data System (ADS)

Frederiksen, Thomas; Paulsson, Magnus; Brandbyge, Mads; Jauho, Antti-Pekka

2007-04-01

We present theoretical calculations of the inelastic transport properties in atomic gold wires. Our method is based on a combination of density functional theory and non-equilibrium Green's functions. The vibrational spectra for extensive series of wire geometries have been calculated using SIESTA, and the corresponding effects in the conductance are analyzed. In particular, we focus on the heating of the active vibrational modes. By a detailed comparison with experiments we are able to estimate an order of magnitude for the external damping of the active vibrations.

Methanol clusters (CH3OH)n: putative global minimum-energy structures from model potentials and dispersion-corrected density functional theory.

PubMed

Kazachenko, Sergey; Bulusu, Satya; Thakkar, Ajit J

2013-06-14

Putative global minima are reported for methanol clusters (CH3OH)n with n ≤ 15. The predictions are based on global optimization of three intermolecular potential energy models followed by local optimization and single-point energy calculations using two variants of dispersion-corrected density functional theory. Recurring structural motifs include folded and/or twisted rings, folded rings with a short branch, and stacked rings. Many of the larger structures are stabilized by weak C-H···O bonds.

A Unifying Theory of Biological Function.

PubMed

van Hateren, J H

2017-01-01

A new theory that naturalizes biological function is explained and compared with earlier etiological and causal role theories. Etiological (or selected effects) theories explain functions from how they are caused over their evolutionary history. Causal role theories analyze how functional mechanisms serve the current capacities of their containing system. The new proposal unifies the key notions of both kinds of theories, but goes beyond them by explaining how functions in an organism can exist as factors with autonomous causal efficacy. The goal-directedness and normativity of functions exist in this strict sense as well. The theory depends on an internal physiological or neural process that mimics an organism's fitness, and modulates the organism's variability accordingly. The structure of the internal process can be subdivided into subprocesses that monitor specific functions in an organism. The theory matches well with each intuition on a previously published list of intuited ideas about biological functions, including intuitions that have posed difficulties for other theories.

Differential Forms: A New Tool in Economics

NASA Astrophysics Data System (ADS)

Mimkes, Jürgen

Econophysics is the transfer of methods from natural to socio-economic sciences. This concept has first been applied to finance1, but it is now also used in various applications of economics and social sciences [2,3]. The present paper focuses on problems in macro economics and growth. 1. Neoclassical theory [4, 5] neglects the “ex post” property of income and growth. Income Y(K, L) is assumed to be a function of capital and labor. But functions cannot model the “ex post” character of income. 2. Neoclassical theory is based on a Cobb Douglas function [6] with variable elasticity α, which may be fitted to economic data. But an undefined elasticity α leads to a descriptive rather than a predictive economic theory. The present paper introduces a new tool - differential forms and path dependent integrals - to macro economics. This is a solution to the problems above: 1. The integral of not exact differential forms is path dependent and can only be calculated “ex post” like income and economic growth. 2. Not exact differential forms can be made exact by an integrating factor, this leads to a new, well defined, unique production function F and a predictive economic theory.

Hemispheric asymmetry of electroencephalography-based functional brain networks.

PubMed

Jalili, Mahdi

2014-11-12

Electroencephalography (EEG)-based functional brain networks have been investigated frequently in health and disease. It has been shown that a number of graph theory metrics are disrupted in brain disorders. EEG-based brain networks are often studied in the whole-brain framework, where all the nodes are grouped into a single network. In this study, we studied the brain networks in two hemispheres and assessed whether there are any hemispheric-specific patterns in the properties of the networks. To this end, resting state closed-eyes EEGs from 44 healthy individuals were processed and the network structures were extracted separately for each hemisphere. We examined neurophysiologically meaningful graph theory metrics: global and local efficiency measures. The global efficiency did not show any hemispheric asymmetry, whereas the local connectivity showed rightward asymmetry for a range of intermediate density values for the constructed networks. Furthermore, the age of the participants showed significant direct correlations with the global efficiency of the left hemisphere, but only in the right hemisphere, with local connectivity. These results suggest that only local connectivity of EEG-based functional networks is associated with brain hemispheres.

Communication: Density functional theory model for multi-reference systems based on the exact-exchange hole normalization

NASA Astrophysics Data System (ADS)

Laqua, Henryk; Kussmann, Jörg; Ochsenfeld, Christian

2018-03-01

The correct description of multi-reference electronic ground states within Kohn-Sham density functional theory (DFT) requires an ensemble-state representation, employing fractionally occupied orbitals. However, the use of fractional orbital occupation leads to non-normalized exact-exchange holes, resulting in large fractional-spin errors for conventional approximative density functionals. In this communication, we present a simple approach to directly include the exact-exchange-hole normalization into DFT. Compared to conventional functionals, our model strongly improves the description for multi-reference systems, while preserving the accuracy in the single-reference case. We analyze the performance of our proposed method at the example of spin-averaged atoms and spin-restricted bond dissociation energy surfaces.

Probability density function learning by unsupervised neurons.

PubMed

Fiori, S

2001-10-01

In a recent work, we introduced the concept of pseudo-polynomial adaptive activation function neuron (FAN) and presented an unsupervised information-theoretic learning theory for such structure. The learning model is based on entropy optimization and provides a way of learning probability distributions from incomplete data. The aim of the present paper is to illustrate some theoretical features of the FAN neuron, to extend its learning theory to asymmetrical density function approximation, and to provide an analytical and numerical comparison with other known density function estimation methods, with special emphasis to the universal approximation ability. The paper also provides a survey of PDF learning from incomplete data, as well as results of several experiments performed on real-world problems and signals.

Research and exploration of product innovative design for function

NASA Astrophysics Data System (ADS)

Wang, Donglin; Wei, Zihui; Wang, Youjiang; Tan, Runhua

2009-07-01

Products innovation is under the prerequisite of realizing the new function, the realization of the new function must solve the contradiction. A new process model of new product innovative design was proposed based on Axiomatic Design (AD) Theory and Functional Structure Analysis (FSA), imbedded Principle of Solving Contradiction. In this model, employ AD Theory to guide FSA, determine the contradiction for the realization of the principle solution. To provide powerful support for innovative design tools in principle solution, Principle of Solving Contradiction in the model were imbedded, so as to boost up the innovation of principle solution. As a case study, an innovative design of button battery separator paper punching machine has been achieved with application of the proposed model.

Communication: Density functional theory model for multi-reference systems based on the exact-exchange hole normalization.

PubMed

Laqua, Henryk; Kussmann, Jörg; Ochsenfeld, Christian

2018-03-28

The correct description of multi-reference electronic ground states within Kohn-Sham density functional theory (DFT) requires an ensemble-state representation, employing fractionally occupied orbitals. However, the use of fractional orbital occupation leads to non-normalized exact-exchange holes, resulting in large fractional-spin errors for conventional approximative density functionals. In this communication, we present a simple approach to directly include the exact-exchange-hole normalization into DFT. Compared to conventional functionals, our model strongly improves the description for multi-reference systems, while preserving the accuracy in the single-reference case. We analyze the performance of our proposed method at the example of spin-averaged atoms and spin-restricted bond dissociation energy surfaces.

[Behavioral phenotypes: cognitive and emotional explanation].

PubMed

Pérez-Alvarez, F; Timoneda-Gallart, C

We present a series of Behavioural phenotypes treated with neurocognitive and neuroemotional procedure. A sample of 26 cases were selected according to qualitative methodology from neuropediatric patients. The method was based on using the PASS theory of intelligence to approach the cognitive problem and the theory of masquerade behaviour as self-defence to solve the emotional problem. Both theories have neurological bases. DN:CAS battery was utilized for assessment of cognitive processes. On the other hand, analysis of cases was carried out doing data analysis with video recorder device. All cases were considered responder cases although in different degree. The responder was defined as the patient which reached better intellectual achievement with respect to cognitive function and which gave up, at least partially, masquerade Behaviour with respect to emotional function. The Behaviour of the Behavioural phenotypes has neurological rationale. The PASS theory and the planning, in particular, supported by prefrontal cortex justifies consistently some behaviours. The masquerade Behaviour theory is explained by the fear emotional response mechanism which means emotion is a cerebral processing with neurological rationale. The Behavioural phenotypes are Behaviours and every Behaviour can be explained by neurological reasons both cognitive and emotional reasons. So, they can be treated by a cognitive and emotional procedure understood in the light of the neurology.

Density functional theory and an experimentally-designed energy functional of electron density.

PubMed

Miranda, David A; Bueno, Paulo R

2016-09-21

We herein demonstrate that capacitance spectroscopy (CS) experimentally allows access to the energy associated with the quantum mechanical ground state of many-electron systems. Priorly, electrochemical capacitance, C [small mu, Greek, macron] [ρ], was previously understood from conceptual and computational density functional theory (DFT) calculations. Thus, we herein propose a quantum mechanical experiment-based variational method for electron charging processes based on an experimentally-designed functional of the ground state electron density. In this methodology, the electron state density, ρ, and an energy functional of the electron density, E [small mu, Greek, macron] [ρ], can be obtained from CS data. CS allows the derivative of the electrochemical potential with respect to the electron density, (δ[small mu, Greek, macron][ρ]/δρ), to be obtained as a unique functional of the energetically minimised system, i.e., β/C [small mu, Greek, macron] [ρ], where β is a constant (associated with the size of the system) and C [small mu, Greek, macron] [ρ] is an experimentally observable quantity. Thus the ground state energy (at a given fixed external potential) can be obtained simply as E [small mu, Greek, macron] [ρ], from the experimental measurement of C [small mu, Greek, macron] [ρ]. An experimental data-set was interpreted to demonstrate the potential of this quantum mechanical experiment-based variational principle.

Embedded-cluster calculations in a numeric atomic orbital density-functional theory framework.

PubMed

Berger, Daniel; Logsdail, Andrew J; Oberhofer, Harald; Farrow, Matthew R; Catlow, C Richard A; Sherwood, Paul; Sokol, Alexey A; Blum, Volker; Reuter, Karsten

2014-07-14

We integrate the all-electron electronic structure code FHI-aims into the general ChemShell package for solid-state embedding quantum and molecular mechanical (QM/MM) calculations. A major undertaking in this integration is the implementation of pseudopotential functionality into FHI-aims to describe cations at the QM/MM boundary through effective core potentials and therewith prevent spurious overpolarization of the electronic density. Based on numeric atomic orbital basis sets, FHI-aims offers particularly efficient access to exact exchange and second order perturbation theory, rendering the established QM/MM setup an ideal tool for hybrid and double-hybrid level density functional theory calculations of solid systems. We illustrate this capability by calculating the reduction potential of Fe in the Fe-substituted ZSM-5 zeolitic framework and the reaction energy profile for (photo-)catalytic water oxidation at TiO2(110).

Embedded-cluster calculations in a numeric atomic orbital density-functional theory framework

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berger, Daniel, E-mail: daniel.berger@ch.tum.de; Oberhofer, Harald; Reuter, Karsten

2014-07-14

We integrate the all-electron electronic structure code FHI-aims into the general ChemShell package for solid-state embedding quantum and molecular mechanical (QM/MM) calculations. A major undertaking in this integration is the implementation of pseudopotential functionality into FHI-aims to describe cations at the QM/MM boundary through effective core potentials and therewith prevent spurious overpolarization of the electronic density. Based on numeric atomic orbital basis sets, FHI-aims offers particularly efficient access to exact exchange and second order perturbation theory, rendering the established QM/MM setup an ideal tool for hybrid and double-hybrid level density functional theory calculations of solid systems. We illustrate this capabilitymore » by calculating the reduction potential of Fe in the Fe-substituted ZSM-5 zeolitic framework and the reaction energy profile for (photo-)catalytic water oxidation at TiO{sub 2}(110)« less

The mGluR theory of fragile X mental retardation.

PubMed

Bear, Mark F; Huber, Kimberly M; Warren, Stephen T

2004-07-01

Many of the diverse functional consequences of activating group 1 metabotropic glutamate receptors require translation of pre-existing mRNA near synapses. One of these consequences is long-term depression (LTD) of transmission at hippocampal synapses. Loss of fragile X mental retardation protein (FMRP), the defect responsible for fragile X syndrome in humans, increases LTD in mouse hippocampus. This finding is consistent with the growing evidence that FMRP normally functions as a repressor of translation of specific mRNAs. Here we present a theory that can account for diverse neurological and psychiatric aspects of fragile X syndrome, based on the assumption that many of the protein-synthesis-dependent functions of metabotropic receptors are exaggerated in fragile X syndrome. The theory suggests new directions for basic research as well as novel therapeutic approaches for the treatment of humans with fragile X, the most frequent inherited cause of mental retardation and an identified cause of autism.

Energy decomposition analysis of single bonds within Kohn-Sham density functional theory.

PubMed

Levine, Daniel S; Head-Gordon, Martin

2017-11-28

An energy decomposition analysis (EDA) for single chemical bonds is presented within the framework of Kohn-Sham density functional theory based on spin projection equations that are exact within wave function theory. Chemical bond energies can then be understood in terms of stabilization caused by spin-coupling augmented by dispersion, polarization, and charge transfer in competition with destabilizing Pauli repulsions. The EDA reveals distinguishing features of chemical bonds ranging across nonpolar, polar, ionic, and charge-shift bonds. The effect of electron correlation is assessed by comparison with Hartree-Fock results. Substituent effects are illustrated by comparing the C-C bond in ethane against that in bis(diamantane), and dispersion stabilization in the latter is quantified. Finally, three metal-metal bonds in experimentally characterized compounds are examined: a [Formula: see text]-[Formula: see text] dimer, the [Formula: see text]-[Formula: see text] bond in dizincocene, and the Mn-Mn bond in dimanganese decacarbonyl.

Four-Component Relativistic Density-Functional Theory Calculations of Nuclear Spin-Rotation Constants: Relativistic Effects in p-Block Hydrides.

PubMed

Komorovsky, Stanislav; Repisky, Michal; Malkin, Elena; Demissie, Taye B; Ruud, Kenneth

2015-08-11

We present an implementation of the nuclear spin-rotation (SR) constants based on the relativistic four-component Dirac-Coulomb Hamiltonian. This formalism has been implemented in the framework of the Hartree-Fock and Kohn-Sham theory, allowing assessment of both pure and hybrid exchange-correlation functionals. In the density-functional theory (DFT) implementation of the response equations, a noncollinear generalized gradient approximation (GGA) has been used. The present approach enforces a restricted kinetic balance condition for the small-component basis at the integral level, leading to very efficient calculations of the property. We apply the methodology to study relativistic effects on the spin-rotation constants by performing calculations on XHn (n = 1-4) for all elements X in the p-block of the periodic table and comparing the effects of relativity on the nuclear SR tensors to that observed for the nuclear magnetic shielding tensors. Correlation effects as described by the density-functional theory are shown to be significant for the spin-rotation constants, whereas the differences between the use of GGA and hybrid density functionals are much smaller. Our calculated relativistic spin-rotation constants at the DFT level of theory are only in fair agreement with available experimental data. It is shown that the scaling of the relativistic effects for the spin-rotation constants (varying between Z(3.8) and Z(4.5)) is as strong as for the chemical shieldings but with a much smaller prefactor.

Octanol-Water Partition Coefficient from 3D-RISM-KH Molecular Theory of Solvation with Partial Molar Volume Correction.

PubMed

Huang, WenJuan; Blinov, Nikolay; Kovalenko, Andriy

2015-04-30

The octanol-water partition coefficient is an important physical-chemical characteristic widely used to describe hydrophobic/hydrophilic properties of chemical compounds. The partition coefficient is related to the transfer free energy of a compound from water to octanol. Here, we introduce a new protocol for prediction of the partition coefficient based on the statistical-mechanical, 3D-RISM-KH molecular theory of solvation. It was shown recently that with the compound-solvent correlation functions obtained from the 3D-RISM-KH molecular theory of solvation, the free energy functional supplemented with the correction linearly related to the partial molar volume obtained from the Kirkwood-Buff/3D-RISM theory, also called the "universal correction" (UC), provides accurate prediction of the hydration free energy of small compounds, compared to explicit solvent molecular dynamics [ Palmer , D. S. ; J. Phys.: Condens. Matter 2010 , 22 , 492101 ]. Here we report that with the UC reparametrized accordingly this theory also provides an excellent agreement with the experimental data for the solvation free energy in nonpolar solvent (1-octanol) and so accurately predicts the octanol-water partition coefficient. The performance of the Kovalenko-Hirata (KH) and Gaussian fluctuation (GF) functionals of the solvation free energy, with and without UC, is tested on a large library of small compounds with diverse functional groups. The best agreement with the experimental data for octanol-water partition coefficients is obtained with the KH-UC solvation free energy functional.

Further evidence of alerted default network connectivity and association with theory of mind ability in schizophrenia.

PubMed

Mothersill, Omar; Tangney, Noreen; Morris, Derek W; McCarthy, Hazel; Frodl, Thomas; Gill, Michael; Corvin, Aiden; Donohoe, Gary

2017-06-01

Resting-state functional magnetic resonance imaging (rs-fMRI) has repeatedly shown evidence of altered functional connectivity of large-scale networks in schizophrenia. The relationship between these connectivity changes and behaviour (e.g. symptoms, neuropsychological performance) remains unclear. Functional connectivity in 27 patients with schizophrenia or schizoaffective disorder, and 25 age and gender matched healthy controls was examined using rs-fMRI. Based on seed regions from previous studies, we examined functional connectivity of the default, cognitive control, affective and attention networks. Effects of symptom severity and theory of mind performance on functional connectivity were also examined. Patients showed increased connectivity between key nodes of the default network including the precuneus and medial prefrontal cortex compared to controls (p<0.01, FWE-corrected). Increasing positive symptoms and increasing theory of mind performance were both associated with altered connectivity of default regions within the patient group (p<0.01, FWE-corrected). This study confirms previous findings of default hyper-connectivity in schizophrenia spectrum patients and reveals an association between altered default connectivity and positive symptom severity. As a novel find, this study also shows that default connectivity is correlated to and predictive of theory of mind performance. Extending these findings by examining the effects of emerging social cognition treatments on both default connectivity and theory of mind performance is now an important goal for research. Copyright © 2016 Elsevier B.V. All rights reserved.

Study on evaluation of construction reliability for engineering project based on fuzzy language operator

NASA Astrophysics Data System (ADS)

Shi, Yu-Fang; Ma, Yi-Yi; Song, Ping-Ping

2018-03-01

System Reliability Theory is a research hotspot of management science and system engineering in recent years, and construction reliability is useful for quantitative evaluation of project management level. According to reliability theory and target system of engineering project management, the defination of construction reliability appears. Based on fuzzy mathematics theory and language operator, value space of construction reliability is divided into seven fuzzy subsets and correspondingly, seven membership function and fuzzy evaluation intervals are got with the operation of language operator, which provides the basis of corresponding method and parameter for the evaluation of construction reliability. This method is proved to be scientific and reasonable for construction condition and an useful attempt for theory and method research of engineering project system reliability.

Lattice density functional theory for confined Ising fluids: comparison between different functional approximations in slit pore

NASA Astrophysics Data System (ADS)

Chen, Xueqian; Feng, Wei; Liu, Honglai; Hu, Ying

2016-09-01

In this paper, Lafuente and Cuesta's cluster density functional theory (CDFT) and lattice mean field approximation (LMFA) are formulated and compared within the framework of lattice density functional theory (LDFT). As a comparison, an LDFT based on our previous work on nonrandom correction to LMFA is also developed, where local density approximation is adopted on the correction. The numerical results of density distributions of an Ising fluid confined in a slit pore obtained from Monte Carlo simulation are used to check these functional approximations. Due to rational treatment on the coupling between site-excluding entropic effect and contact-attracting enthalpic effect by CDFT with Bethe-Peierls approximation (named as BPA-CDFT for short), the improvement of BPA-CDFT beyond LMFA is checked as expected. And it is interesting that our LDFT has a comparative accuracy with BPA-CDFT. Apparent differences between the profiles such as solvation force, excess adsorption quantity and interfacial tension from LMFA and non-LMFAs are found in our calculations. We also discuss some possible theoretical extensions of BPA-CDFT.

Modern control techniques in active flutter suppression using a control moment gyro

NASA Technical Reports Server (NTRS)

Buchek, P. M.

1974-01-01

Development of organized synthesis techniques, using concepts of modern control theory was studied for the design of active flutter suppression systems for two and three-dimensional lifting surfaces, utilizing a control moment gyro (CMG) to generate the required control torques. Incompressible flow theory is assumed, with the unsteady aerodynamic forces and moments for arbitrary airfoil motion obtained by using the convolution integral based on Wagner's indicial lift function. Linear optimal control theory is applied to find particular optimal sets of gain values which minimize a quadratic performance function. The closed loop system's response to impulsive gust disturbances and the resulting control power requirements are investigated, and the system eigenvalues necessary to minimize the maximum value of control power are determined.

Density Functional Theory (DFT) Study of Molecularly Imprinted Polymer (MIP) Methacrylic Acid (MAA) with D-Glucose

NASA Astrophysics Data System (ADS)

Wungu, T. D. K.; Marsha, S. E.; Widayani; Suprijadi

2017-07-01

In order to find an alternative biosensor material which enables to detect the glucose level, therefore in this study, the interaction between Methacrylic Acid (MAA) based Molecularly Imprinted Polymer (MIP) with D-Glucose is investigated using the Density Functional Theory (DFT). The aim of this study is to determine whether a molecule of the MAA can be functioned as a bio-sensing of glucose. In this calculation, the Gaussian 09 with B3LYP and 631+G(d) basis sets is used to calculate all electronic properties. It is found that the interaction between a molecule of MAA and a molecule of D-Glucose was observed through the shortened distance between the two molecules. The binding energy of MAA/D-glucose and the Mulliken population analysis are investigated for checking possible interaction. From analysis, the MAA based MIP can be used as a bio-sensing material.

Ab initio approach to the ion stopping power at the plasma-solid interface

NASA Astrophysics Data System (ADS)

Bonitz, Michael; Schlünzen, Niclas; Wulff, Lasse; Joost, Jan-Philip; Balzer, Karsten

2016-10-01

The energy loss of ions in solids is of key relevance for many applications of plasmas, ranging from plasma technology to fusion. Standard approaches are based on density functional theory or SRIM simulations, however, the applicability range and accuracy of these results are difficult to assess, in particular, for low energies. Here we present an independent approach that is based on ab initio nonequilibrium Green functions theory, e.g. that allows to incorporate electronic correlations effects of the solid. We present the first application of this method to low-temperature plasmas, concentrating on proton and alpha-particle stopping in a graphene layer. In addition to the stopping power we present time-dependent results for the local electron density, the spectral function and the photoemission spectrum that is directly accessible in optical, UV or x-ray diagnostics. http://www.itap.uni-kiel.de/theo-physik/bonitz/.

DFT based vibrational spectroscopic investigations and biological activity of toxic material monocrotophos

NASA Astrophysics Data System (ADS)

Nimmi, D. E.; Sam, S. P. Chandhini; Praveen, S. G.; Binoy, J.

2018-05-01

Many organophosphate compounds exhibiting toxicity are widely used as pesticides and insecticides whose structural features can be explained excellently using geometric simulation using density functional theory and vibrational spectrum. In this work, the molecular structural parameters and vibrational frequencies of the fundamental modes of Monocrotophoshave been obtained using Density functional theory (DFT), using B3LYP functional with 6-311++G(d, p) basis sets and the detailed vibrational analysis of FT-IR and FT-Ramanspectral bands have been carried out using potential energy distribution (PED). The deviation from the resonance structure of phosphate group due to `bridging of oxygen' and π-resonance of amides has been investigated based on the spectral and geometric data. The molecular docking simulation of Monocrotophos with BSA and DNA has been performed to find the mode of binding and the interactions with BSA has been investigated with UV-Visible spectroscopic method, to assess the strength of binding.

Insight into the C-F bond mechanism of molecular analogs for antibacterial drug design.

PubMed

Liu, Junna; Lv, Biyu; Liu, Huaqing; Li, Xin; Yin, Weiping

2018-06-01

The activities of biological molecules usually rely on both of intra-molecular and intermolecular interactions between their function groups. These interactions include interonic attraction theory, Van der Waal's forces and the function of geometry on the individual molecules, whether they are naturally or synthetic. The purpose of this study was to evaluate the antibacterial activity of C-F bond compound using combination of experiments verification and theoretical calculation. We target on the insect natural products from the maggots of Chrysomyis megacephala Fabricius. Based on density functional theory(DFT) and B3LYP method, a theoretical study of the C-F bond on fluoride was designed to explore compounds 2 and 4 antibacterial structure-activity relationship. With the progress in DFT, first-principle calculation based on DFT has gradually become a routine method for drug design, quantum chemistry and other science fields.

The atomic scale structure of CXV carbon: wide-angle x-ray scattering and modeling studies.

PubMed

Hawelek, L; Brodka, A; Dore, J C; Honkimaki, V; Burian, A

2013-11-13

The disordered structure of commercially available CXV activated carbon produced from finely powdered wood-based carbon has been studied using the wide-angle x-ray scattering technique, molecular dynamics and density functional theory simulations. The x-ray scattering data has been converted to the real space representation in the form of the pair correlation function via the Fourier transform. Geometry optimizations using classical molecular dynamics based on the reactive empirical bond order potential and density functional theory at the B3LYP/6-31g* level have been performed to generate nanoscale models of CXV carbon consistent with the experimental data. The final model of the structure comprises four chain-like and buckled graphitic layers containing a small percentage of four-fold coordinated atoms (sp(3) defects) in each layer. The presence of non-hexagonal rings in the atomic arrangement has been also considered.

High-throughput density-functional perturbation theory phonons for inorganic materials

NASA Astrophysics Data System (ADS)

Petretto, Guido; Dwaraknath, Shyam; P. C. Miranda, Henrique; Winston, Donald; Giantomassi, Matteo; van Setten, Michiel J.; Gonze, Xavier; Persson, Kristin A.; Hautier, Geoffroy; Rignanese, Gian-Marco

2018-05-01

The knowledge of the vibrational properties of a material is of key importance to understand physical phenomena such as thermal conductivity, superconductivity, and ferroelectricity among others. However, detailed experimental phonon spectra are available only for a limited number of materials, which hinders the large-scale analysis of vibrational properties and their derived quantities. In this work, we perform ab initio calculations of the full phonon dispersion and vibrational density of states for 1521 semiconductor compounds in the harmonic approximation based on density functional perturbation theory. The data is collected along with derived dielectric and thermodynamic properties. We present the procedure used to obtain the results, the details of the provided database and a validation based on the comparison with experimental data.

First-Principles pH Theory

NASA Astrophysics Data System (ADS)

Kim, Yong-Hyun; Zhang, S. B.

2006-03-01

Despite being one of the most important macroscopic measures and a long history even before the quantum mechanics, the concept of pH has rarely been mentioned in microscopic theories, nor being incorporated computationally into first-principles theory of aqueous solutions. Here, we formulate a theory for the pH dependence of solution formation energy by introducing the proton chemical potential as the microscopic counterpart of pH in atomistic solution models. Within the theory, the general acid-base chemistry can be cast in a simple pictorial representation. We adopt density-functional molecular dynamics to demonstrate the usefulness of the method by studying a number of solution systems including water, small solute molecules such as NH3 and HCOOH, and more complex amino acids with several functional groups. For pure water, we calculated the auto- ionization constant to be 13.2 with a 95 % accuracy. For other solutes, the calculated dissociation constants, i.e., the so- called pKa, are also in reasonable agreement with experiments. Our first-principles pH theory can be readily applied to broad solution chemistry problems such as redox reactions.

Neonatal physical therapy. Part II: Practice frameworks and evidence-based practice guidelines.

PubMed

Sweeney, Jane K; Heriza, Carolyn B; Blanchard, Yvette; Dusing, Stacey C

2010-01-01

(1) To outline frameworks for neonatal physical therapy based on 3 theoretical models, (2) to describe emerging literature supporting neonatal physical therapy practice, and (3) to identify evidence-based practice recommendations. Three models are presented as a framework for neonatal practice: (1) dynamic systems theory including synactive theory and the theory of neuronal group selection, (2) the International Classification of Functioning, Disability and Health, and (3) family-centered care. Literature is summarized to support neonatal physical therapists in the areas of examination, developmental care, intervention, and parent education. Practice recommendations are offered with levels of evidence identified. Neonatal physical therapy practice has a theoretical and evidence-based structure, and evidence is emerging for selected clinical procedures. Continued research to expand the science of neonatal physical therapy is critical to elevate the evidence and support practice recommendations.

The Role of Intelligence and Education in the Division of Labor. Report No. 355.

ERIC Educational Resources Information Center

Gottfredson, Linda S.

This paper suggests that the occupational hierarchy is based on functionally important differences among workers and their jobs and proposes a modified functional theory of occupational stratification. Section I examines the role of education in social stratification. Sections II, III, and IV review (1) functions of schooling, (2) evidence about…

Density-functional theory based on the electron distribution on the energy coordinate

NASA Astrophysics Data System (ADS)

Takahashi, Hideaki

2018-03-01

We developed an electronic density functional theory utilizing a novel electron distribution n(ɛ) as a basic variable to compute ground state energy of a system. n(ɛ) is obtained by projecting the electron density n({\\boldsymbol{r}}) defined on the space coordinate {\\boldsymbol{r}} onto the energy coordinate ɛ specified with the external potential {\\upsilon }ext}({\\boldsymbol{r}}) of interest. It was demonstrated that the Kohn-Sham equation can also be formulated with the exchange-correlation functional E xc[n(ɛ)] that employs the density n(ɛ) as an argument. It turned out an exchange functional proposed in our preliminary development suffices to describe properly the potential energies of several types of chemical bonds with comparable accuracies to the corresponding functional based on local density approximation. As a remarkable feature of the distribution n(ɛ) it inherently involves the spatially non-local information of the exchange hole at the bond dissociation limit in contrast to conventional approximate functionals. By taking advantage of this property we also developed a prototype of the static correlation functional E sc including no empirical parameters, which showed marked improvements in describing the dissociations of covalent bonds in {{{H}}}2,{{{C}}}2{{{H}}}4 and {CH}}4 molecules.

Electronic Coupling Calculations for Bridge-Mediated Charge Transfer Using Constrained Density Functional Theory (CDFT) and Effective Hamiltonian Approaches at the Density Functional Theory (DFT) and Fragment-Orbital Density Functional Tight Binding (FODFTB) Level

DOE PAGES

Gillet, Natacha; Berstis, Laura; Wu, Xiaojing; ...

2016-09-09

In this paper, four methods to calculate charge transfer integrals in the context of bridge-mediated electron transfer are tested. These methods are based on density functional theory (DFT). We consider two perturbative Green's function effective Hamiltonian methods (first, at the DFT level of theory, using localized molecular orbitals; second, applying a tight-binding DFT approach, using fragment orbitals) and two constrained DFT implementations with either plane-wave or local basis sets. To assess the performance of the methods for through-bond (TB)-dominated or through-space (TS)-dominated transfer, different sets of molecules are considered. For through-bond electron transfer (ET), several molecules that were originally synthesizedmore » by Paddon-Row and co-workers for the deduction of electronic coupling values from photoemission and electron transmission spectroscopies, are analyzed. The tested methodologies prove to be successful in reproducing experimental data, the exponential distance decay constant and the superbridge effects arising from interference among ET pathways. For through-space ET, dedicated p-stacked systems with heterocyclopentadiene molecules were created and analyzed on the basis of electronic coupling dependence on donor-acceptor distance, structure of the bridge, and ET barrier height. The inexpensive fragment-orbital density functional tight binding (FODFTB) method gives similar results to constrained density functional theory (CDFT) and both reproduce the expected exponential decay of the coupling with donor-acceptor distances and the number of bridging units. Finally, these four approaches appear to give reliable results for both TB and TS ET and present a good alternative to expensive ab initio methodologies for large systems involving long-range charge transfers.« less

Electronic Coupling Calculations for Bridge-Mediated Charge Transfer Using Constrained Density Functional Theory (CDFT) and Effective Hamiltonian Approaches at the Density Functional Theory (DFT) and Fragment-Orbital Density Functional Tight Binding (FODFTB) Level

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gillet, Natacha; Berstis, Laura; Wu, Xiaojing

In this paper, four methods to calculate charge transfer integrals in the context of bridge-mediated electron transfer are tested. These methods are based on density functional theory (DFT). We consider two perturbative Green's function effective Hamiltonian methods (first, at the DFT level of theory, using localized molecular orbitals; second, applying a tight-binding DFT approach, using fragment orbitals) and two constrained DFT implementations with either plane-wave or local basis sets. To assess the performance of the methods for through-bond (TB)-dominated or through-space (TS)-dominated transfer, different sets of molecules are considered. For through-bond electron transfer (ET), several molecules that were originally synthesizedmore » by Paddon-Row and co-workers for the deduction of electronic coupling values from photoemission and electron transmission spectroscopies, are analyzed. The tested methodologies prove to be successful in reproducing experimental data, the exponential distance decay constant and the superbridge effects arising from interference among ET pathways. For through-space ET, dedicated p-stacked systems with heterocyclopentadiene molecules were created and analyzed on the basis of electronic coupling dependence on donor-acceptor distance, structure of the bridge, and ET barrier height. The inexpensive fragment-orbital density functional tight binding (FODFTB) method gives similar results to constrained density functional theory (CDFT) and both reproduce the expected exponential decay of the coupling with donor-acceptor distances and the number of bridging units. Finally, these four approaches appear to give reliable results for both TB and TS ET and present a good alternative to expensive ab initio methodologies for large systems involving long-range charge transfers.« less

Electronic Coupling Calculations for Bridge-Mediated Charge Transfer Using Constrained Density Functional Theory (CDFT) and Effective Hamiltonian Approaches at the Density Functional Theory (DFT) and Fragment-Orbital Density Functional Tight Binding (FODFTB) Level.

PubMed

Gillet, Natacha; Berstis, Laura; Wu, Xiaojing; Gajdos, Fruzsina; Heck, Alexander; de la Lande, Aurélien; Blumberger, Jochen; Elstner, Marcus

2016-10-11

In this article, four methods to calculate charge transfer integrals in the context of bridge-mediated electron transfer are tested. These methods are based on density functional theory (DFT). We consider two perturbative Green's function effective Hamiltonian methods (first, at the DFT level of theory, using localized molecular orbitals; second, applying a tight-binding DFT approach, using fragment orbitals) and two constrained DFT implementations with either plane-wave or local basis sets. To assess the performance of the methods for through-bond (TB)-dominated or through-space (TS)-dominated transfer, different sets of molecules are considered. For through-bond electron transfer (ET), several molecules that were originally synthesized by Paddon-Row and co-workers for the deduction of electronic coupling values from photoemission and electron transmission spectroscopies, are analyzed. The tested methodologies prove to be successful in reproducing experimental data, the exponential distance decay constant and the superbridge effects arising from interference among ET pathways. For through-space ET, dedicated π-stacked systems with heterocyclopentadiene molecules were created and analyzed on the basis of electronic coupling dependence on donor-acceptor distance, structure of the bridge, and ET barrier height. The inexpensive fragment-orbital density functional tight binding (FODFTB) method gives similar results to constrained density functional theory (CDFT) and both reproduce the expected exponential decay of the coupling with donor-acceptor distances and the number of bridging units. These four approaches appear to give reliable results for both TB and TS ET and present a good alternative to expensive ab initio methodologies for large systems involving long-range charge transfers.

High-functioning autism patients share similar but more severe impairments in verbal theory of mind than schizophrenia patients.

PubMed

Tin, L N W; Lui, S S Y; Ho, K K Y; Hung, K S Y; Wang, Y; Yeung, H K H; Wong, T Y; Lam, S M; Chan, R C K; Cheung, E F C

2018-06-01

Evidence suggests that autism and schizophrenia share similarities in genetic, neuropsychological and behavioural aspects. Although both disorders are associated with theory of mind (ToM) impairments, a few studies have directly compared ToM between autism patients and schizophrenia patients. This study aimed to investigate to what extent high-functioning autism patients and schizophrenia patients share and differ in ToM performance. Thirty high-functioning autism patients, 30 schizophrenia patients and 30 healthy individuals were recruited. Participants were matched in age, gender and estimated intelligence quotient. The verbal-based Faux Pas Task and the visual-based Yoni Task were utilised to examine first- and higher-order, affective and cognitive ToM. The task/item difficulty of two paradigms was examined using mixed model analyses of variance (ANOVAs). Multiple ANOVAs and mixed model ANOVAs were used to examine group differences in ToM. The Faux Pas Task was more difficult than the Yoni Task. High-functioning autism patients showed more severely impaired verbal-based ToM in the Faux Pas Task, but shared similar visual-based ToM impairments in the Yoni Task with schizophrenia patients. The findings that individuals with high-functioning autism shared similar but more severe impairments in verbal ToM than individuals with schizophrenia support the autism-schizophrenia continuum. The finding that verbal-based but not visual-based ToM was more impaired in high-functioning autism patients than schizophrenia patients could be attributable to the varied task/item difficulty between the two paradigms.

Mechanism on brain information processing: Energy coding

NASA Astrophysics Data System (ADS)

Wang, Rubin; Zhang, Zhikang; Jiao, Xianfa

2006-09-01

According to the experimental result of signal transmission and neuronal energetic demands being tightly coupled to information coding in the cerebral cortex, the authors present a brand new scientific theory that offers a unique mechanism for brain information processing. They demonstrate that the neural coding produced by the activity of the brain is well described by the theory of energy coding. Due to the energy coding model's ability to reveal mechanisms of brain information processing based upon known biophysical properties, they cannot only reproduce various experimental results of neuroelectrophysiology but also quantitatively explain the recent experimental results from neuroscientists at Yale University by means of the principle of energy coding. Due to the theory of energy coding to bridge the gap between functional connections within a biological neural network and energetic consumption, they estimate that the theory has very important consequences for quantitative research of cognitive function.

Density functional theory (DFT) study of a new novel bionanosensor hybrid; tryptophan/Pd doped single walled carbon nanotube

NASA Astrophysics Data System (ADS)

Yoosefian, Mehdi; Etminan, Nazanin

2016-07-01

In order to explore a new novel L-amino acid/transition metal doped single walled carbon nanotube based biosensor, density functional theory calculations were studied. These hybrid structures of organic-inorganic nanobiosensors are able to detect the smallest amino acid building block of proteins. The configurations of amine and carbonyl group coordination of tryptophan aromatic amino acid adsorbed on Pd/doped single walled carbon nanotube were compared. The frontier molecular orbital theory, quantum theory atom in molecule and natural bond orbital analysis were performed. The molecular electrostatic potential and the electron density surfaces were constructed. The calculations indicated that the Pd/SWCNT was sensitive to tryptophan suggesting the importance of interaction with biological molecule and potential detecting application. The proposed nanobiosensor represents a highly sensitive detection of protein at ultra-low concentration in diagnosis applications.

Energy coding in biological neural networks

PubMed Central

Zhang, Zhikang

2007-01-01

According to the experimental result of signal transmission and neuronal energetic demands being tightly coupled to information coding in the cerebral cortex, we present a brand new scientific theory that offers an unique mechanism for brain information processing. We demonstrate that the neural coding produced by the activity of the brain is well described by our theory of energy coding. Due to the energy coding model’s ability to reveal mechanisms of brain information processing based upon known biophysical properties, we can not only reproduce various experimental results of neuro-electrophysiology, but also quantitatively explain the recent experimental results from neuroscientists at Yale University by means of the principle of energy coding. Due to the theory of energy coding to bridge the gap between functional connections within a biological neural network and energetic consumption, we estimate that the theory has very important consequences for quantitative research of cognitive function. PMID:19003513

Generalized framework for testing gravity with gravitational-wave propagation. II. Constraints on Horndeski theory

NASA Astrophysics Data System (ADS)

Arai, Shun; Nishizawa, Atsushi

2018-05-01

Gravitational waves (GW) are generally affected by modification of a gravity theory during propagation at cosmological distances. We numerically perform a quantitative analysis on Horndeski theory at the cosmological scale to constrain the Horndeski theory by GW observations in a model-independent way. We formulate a parametrization for a numerical simulation based on the Monte Carlo method and obtain the classification of the models that agrees with cosmic accelerating expansion within observational errors of the Hubble parameter. As a result, we find that a large group of the models in the Horndeski theory that mimic cosmic expansion of the Λ CDM model can be excluded from the simultaneous detection of a GW and its electromagnetic transient counterpart. Based on our result and the latest detection of GW170817 and GRB170817A, we conclude that the subclass of Horndeski theory including arbitrary functions G4 and G5 can hardly explain cosmic accelerating expansion without fine-tuning.

Finding accurate frontiers: A knowledge-intensive approach to relational learning

NASA Technical Reports Server (NTRS)

Pazzani, Michael; Brunk, Clifford

1994-01-01

An approach to analytic learning is described that searches for accurate entailments of a Horn Clause domain theory. A hill-climbing search, guided by an information based evaluation function, is performed by applying a set of operators that derive frontiers from domain theories. The analytic learning system is one component of a multi-strategy relational learning system. We compare the accuracy of concepts learned with this analytic strategy to concepts learned with an analytic strategy that operationalizes the domain theory.

On Riemann boundary value problems for null solutions of the two dimensional Helmholtz equation

NASA Astrophysics Data System (ADS)

Bory Reyes, Juan; Abreu Blaya, Ricardo; Rodríguez Dagnino, Ramón Martin; Kats, Boris Aleksandrovich

2018-01-01

The Riemann boundary value problem (RBVP to shorten notation) in the complex plane, for different classes of functions and curves, is still widely used in mathematical physics and engineering. For instance, in elasticity theory, hydro and aerodynamics, shell theory, quantum mechanics, theory of orthogonal polynomials, and so on. In this paper, we present an appropriate hyperholomorphic approach to the RBVP associated to the two dimensional Helmholtz equation in R^2 . Our analysis is based on a suitable operator calculus.

LSMS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eisenbach, Markus; Li, Ying Wai; Liu, Xianglin

2017-12-01

LSMS is a first principles, Density Functional theory based, electronic structure code targeted mainly at materials applications. LSMS calculates the local spin density approximation to the diagonal part of the electron Green's function. The electron/spin density and energy are easily determined once the Green's function is known. Linear scaling with system size is achieved in the LSMS by using several unique properties of the real space multiple scattering approach to the Green's function.

Solid Rocket Fuel Constitutive Theory and Polymer Cure

NASA Technical Reports Server (NTRS)

Ream, Robert

2006-01-01

Solid Rocket Fuel is a complex composite material for which no general constitutive theory, based on first principles, has been developed. One of the principles such a relation would depend on is the morphology of the binder. A theory of polymer curing is required to determine this morphology. During work on such a theory an algorithm was developed for counting the number of ways a polymer chain could assemble. The methods used to develop and check this algorithm led to an analytic solution to the problem. This solution is used in a probability distribution function which characterizes the morphology of the polymer.

Generalized-active-space pair-density functional theory: an efficient method to study large, strongly correlated, conjugated systems

DOE PAGES

Ghosh, Soumen; Cramer, Christopher J.; Truhlar, Donald G.; ...

2017-01-19

Predicting ground- and excited-state properties of open-shell organic molecules by electronic structure theory can be challenging because an accurate treatment has to correctly describe both static and dynamic electron correlation. Strongly correlated systems, i.e., systems with near-degeneracy correlation effects, are particularly troublesome. Multiconfigurational wave function methods based on an active space are adequate in principle, but it is impractical to capture most of the dynamic correlation in these methods for systems characterized by many active electrons. Here, we recently developed a new method called multiconfiguration pair-density functional theory (MC-PDFT), that combines the advantages of wave function theory and density functionalmore » theory to provide a more practical treatment of strongly correlated systems. Here we present calculations of the singlet–triplet gaps in oligoacenes ranging from naphthalene to dodecacene. Calculations were performed for unprecedently large orbitally optimized active spaces of 50 electrons in 50 orbitals, and we test a range of active spaces and active space partitions, including four kinds of frontier orbital partitions. We show that MC-PDFT can predict the singlet–triplet splittings for oligoacenes consistent with the best available and much more expensive methods, and indeed MC-PDFT may constitute the benchmark against which those other models should be compared, given the absence of experimental data.« less

Generalized-active-space pair-density functional theory: an efficient method to study large, strongly correlated, conjugated systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ghosh, Soumen; Cramer, Christopher J.; Truhlar, Donald G.

Predicting ground- and excited-state properties of open-shell organic molecules by electronic structure theory can be challenging because an accurate treatment has to correctly describe both static and dynamic electron correlation. Strongly correlated systems, i.e., systems with near-degeneracy correlation effects, are particularly troublesome. Multiconfigurational wave function methods based on an active space are adequate in principle, but it is impractical to capture most of the dynamic correlation in these methods for systems characterized by many active electrons. Here, we recently developed a new method called multiconfiguration pair-density functional theory (MC-PDFT), that combines the advantages of wave function theory and density functionalmore » theory to provide a more practical treatment of strongly correlated systems. Here we present calculations of the singlet–triplet gaps in oligoacenes ranging from naphthalene to dodecacene. Calculations were performed for unprecedently large orbitally optimized active spaces of 50 electrons in 50 orbitals, and we test a range of active spaces and active space partitions, including four kinds of frontier orbital partitions. We show that MC-PDFT can predict the singlet–triplet splittings for oligoacenes consistent with the best available and much more expensive methods, and indeed MC-PDFT may constitute the benchmark against which those other models should be compared, given the absence of experimental data.« less

Density functional perturbational orbital theory of spin polarization in electronic systems. II. Transition metal dimer complexes.

PubMed

Seo, Dong-Kyun

2007-11-14

We present a theoretical scheme for a semiquantitative analysis of electronic structures of magnetic transition metal dimer complexes within spin density functional theory (DFT). Based on the spin polarization perturbational orbital theory [D.-K. Seo, J. Chem. Phys. 125, 154105 (2006)], explicit spin-dependent expressions of the spin orbital energies and coefficients are derived, which allows to understand how spin orbitals form and change their energies and shapes when two magnetic sites are coupled either ferromagnetically or antiferromagnetically. Upon employment of the concept of magnetic orbitals in the active-electron approximation, a general mathematical formula is obtained for the magnetic coupling constant J from the analytical expression for the electronic energy difference between low-spin broken-symmetry and high-spin states. The origin of the potential exchange and kinetic exchange terms based on the one-electron picture is also elucidated. In addition, we provide a general account of the DFT analysis of the magnetic exchange interactions in compounds for which the active-electron approximation is not appropriate.

Circuit theory and model-based inference for landscape connectivity

USGS Publications Warehouse

Hanks, Ephraim M.; Hooten, Mevin B.

2013-01-01

Circuit theory has seen extensive recent use in the field of ecology, where it is often applied to study functional connectivity. The landscape is typically represented by a network of nodes and resistors, with the resistance between nodes a function of landscape characteristics. The effective distance between two locations on a landscape is represented by the resistance distance between the nodes in the network. Circuit theory has been applied to many other scientific fields for exploratory analyses, but parametric models for circuits are not common in the scientific literature. To model circuits explicitly, we demonstrate a link between Gaussian Markov random fields and contemporary circuit theory using a covariance structure that induces the necessary resistance distance. This provides a parametric model for second-order observations from such a system. In the landscape ecology setting, the proposed model provides a simple framework where inference can be obtained for effects that landscape features have on functional connectivity. We illustrate the approach through a landscape genetics study linking gene flow in alpine chamois (Rupicapra rupicapra) to the underlying landscape.

Formally exact integral equation theory of the exchange-only potential in density functional theory: Refined closure approximation

NASA Astrophysics Data System (ADS)

March, N. H.; Nagy, Á.

A fonnally exact integral equation theory for the exchange-only potential Vx(r) in density functional theory was recently set up by Howard and March [I.A. Howard, N.H. March, J. Chem. Phys. 119 (2003) 5789]. It involved a `closure' function P(r) satisfying the exact sum rule ∫ P(r) dr = 0. The simplest choice P(r) = 0 recovers then the approximation proposed by Della Sala and Görling [F. Della Sala, A. Görling, J. Chem. Phys. 115 (2001) 5718] and by Gritsenko and Baerends [O.V. Gritsenko, E.J. Baerends, Phys. Rev. A 64 (2001) 042506]. Here, refined choices of P(r) are proposed, the most direct being based on the KLI (Krieger-Li-Iafrate) approximation. A further choice given some attention is where P(r) involves frontier orbital properties. In particular, the introduction of the LUMO (lowest unoccupied molecular) orbital, along with the energy separation between HOMO (highest occupied molecular orbital) and LUMO levels, should prove a significant step beyond current approximations to the optimized potential method, all of which involve only single-particle occupied orbitals.

Time-dependent density-functional theory with optimized effective potential and self-interaction correction and derivative discontinuity for the treatment of double ionization of He and Be atoms in intense laser fields

NASA Astrophysics Data System (ADS)

Heslar, John; Telnov, Dmitry A.; Chu, Shih-I.

2013-05-01

We present a self-interaction-free time-dependent density-functional theory (TDDFT) for the treatment of double-ionization processes of many-electron systems. The method is based on the extension of the Krieger-Li-Iafrate (KLI) treatment of the optimized effective potential (OEP) theory and the incorporation of an explicit self-interaction correction (SIC) term. In the framework of the time-dependent density functional theory, we have performed three-dimensional (3D) calculations of double ionization of He and Be atoms by intense near-infrared laser fields. We make use of the exchange-correlation potential with the integer discontinuity which improves the description of the double-ionization process. We found that a proper description of the double ionization requires the TDDFT exchange-correlation potential with the discontinuity with respect to the variation of the total particle number (TPN). The results for the intensity-dependent rates of double ionization of He and Be atoms are presented.

Exaggerated risk: prospect theory and probability weighting in risky choice.

PubMed

Kusev, Petko; van Schaik, Paul; Ayton, Peter; Dent, John; Chater, Nick

2009-11-01

In 5 experiments, we studied precautionary decisions in which participants decided whether or not to buy insurance with specified cost against an undesirable event with specified probability and cost. We compared the risks taken for precautionary decisions with those taken for equivalent monetary gambles. Fitting these data to Tversky and Kahneman's (1992) prospect theory, we found that the weighting function required to model precautionary decisions differed from that required for monetary gambles. This result indicates a failure of the descriptive invariance axiom of expected utility theory. For precautionary decisions, people overweighted small, medium-sized, and moderately large probabilities-they exaggerated risks. This effect is not anticipated by prospect theory or experience-based decision research (Hertwig, Barron, Weber, & Erev, 2004). We found evidence that exaggerated risk is caused by the accessibility of events in memory: The weighting function varies as a function of the accessibility of events. This suggests that people's experiences of events leak into decisions even when risk information is explicitly provided. Our findings highlight a need to investigate how variation in decision content produces variation in preferences for risk.

Autism: reduced connectivity between cortical areas involved in face expression, theory of mind, and the sense of self.

PubMed

Cheng, Wei; Rolls, Edmund T; Gu, Huaguang; Zhang, Jie; Feng, Jianfeng

2015-05-01

Whole-brain voxel-based unbiased resting state functional connectivity was analysed in 418 subjects with autism and 509 matched typically developing individuals. We identified a key system in the middle temporal gyrus/superior temporal sulcus region that has reduced cortical functional connectivity (and increased with the medial thalamus), which is implicated in face expression processing involved in social behaviour. This system has reduced functional connectivity with the ventromedial prefrontal cortex, which is implicated in emotion and social communication. The middle temporal gyrus system is also implicated in theory of mind processing. We also identified in autism a second key system in the precuneus/superior parietal lobule region with reduced functional connectivity, which is implicated in spatial functions including of oneself, and of the spatial environment. It is proposed that these two types of functionality, face expression-related, and of one's self and the environment, are important components of the computations involved in theory of mind, whether of oneself or of others, and that reduced connectivity within and between these regions may make a major contribution to the symptoms of autism. © The Author (2015). Published by Oxford University Press on behalf of the Guarantors of Brain.

Probability and Quantum Paradigms: the Interplay

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kracklauer, A. F.

Since the introduction of Born's interpretation of quantum wave functions as yielding the probability density of presence, Quantum Theory and Probability have lived in a troubled symbiosis. Problems arise with this interpretation because quantum probabilities exhibit features alien to usual probabilities, namely non Boolean structure and non positive-definite phase space probability densities. This has inspired research into both elaborate formulations of Probability Theory and alternate interpretations for wave functions. Herein the latter tactic is taken and a suggested variant interpretation of wave functions based on photo detection physics proposed, and some empirical consequences are considered. Although incomplete in a fewmore » details, this variant is appealing in its reliance on well tested concepts and technology.« less

Equal Area Logistic Estimation for Item Response Theory

NASA Astrophysics Data System (ADS)

Lo, Shih-Ching; Wang, Kuo-Chang; Chang, Hsin-Li

2009-08-01

Item response theory (IRT) models use logistic functions exclusively as item response functions (IRFs). Applications of IRT models require obtaining the set of values for logistic function parameters that best fit an empirical data set. However, success in obtaining such set of values does not guarantee that the constructs they represent actually exist, for the adequacy of a model is not sustained by the possibility of estimating parameters. In this study, an equal area based two-parameter logistic model estimation algorithm is proposed. Two theorems are given to prove that the results of the algorithm are equivalent to the results of fitting data by logistic model. Numerical results are presented to show the stability and accuracy of the algorithm.

Incorporating "motivation" into the functional analysis of challenging behavior: on the interactive and integrative potential of the motivating operation.

PubMed

Langthorne, Paul; McGill, Peter; O'Reilly, Mark

2007-07-01

Sensitivity theory attempts to account for the variability often observed in challenging behavior by recourse to the "aberrant motivation" of people with intellectual and developmental disabilities. In this article, we suggest that a functional analysis based on environmental (challenging environments) and biological (challenging needs) motivating operations provides a more parsimonious and empirically grounded account of challenging behavior than that proposed by sensitivity theory. It is argued that the concept of the motivating operation provides a means of integrating diverse strands of research without the undue inference of mentalistic constructs. An integrated model of challenging behavior is proposed, one that remains compatible with the central tenets of functional analysis.

Probability and Quantum Paradigms: the Interplay

NASA Astrophysics Data System (ADS)

Kracklauer, A. F.

2007-12-01

Since the introduction of Born's interpretation of quantum wave functions as yielding the probability density of presence, Quantum Theory and Probability have lived in a troubled symbiosis. Problems arise with this interpretation because quantum probabilities exhibit features alien to usual probabilities, namely non Boolean structure and non positive-definite phase space probability densities. This has inspired research into both elaborate formulations of Probability Theory and alternate interpretations for wave functions. Herein the latter tactic is taken and a suggested variant interpretation of wave functions based on photo detection physics proposed, and some empirical consequences are considered. Although incomplete in a few details, this variant is appealing in its reliance on well tested concepts and technology.

Density functional theory for field emission from carbon nano-structures.

PubMed

Li, Zhibing

2015-12-01

Electron field emission is understood as a quantum mechanical many-body problem in which an electronic quasi-particle of the emitter is converted into an electron in vacuum. Fundamental concepts of field emission, such as the field enhancement factor, work-function, edge barrier and emission current density, will be investigated, using carbon nanotubes and graphene as examples. A multi-scale algorithm basing on density functional theory is introduced. We will argue that such a first principle approach is necessary and appropriate for field emission of nano-structures, not only for a more accurate quantitative description, but, more importantly, for deeper insight into field emission. Copyright © 2015 The Author. Published by Elsevier B.V. All rights reserved.

Rhetorical Interpretation of Abstracts in Sci-Tech Theses Based on Burke's Identification Theory

ERIC Educational Resources Information Center

Zhong, Jihong

2017-01-01

Abstract of a thesis is the brief and accurate representation of the thesis, with the important function of persuading readers to read on the thesis. So how the writer constructs the abstract and wins readers' recognition is our main focus. On the basis of Burke's Identification Theory, this paper analyzed 10 abstracts from "Nature" from…

Using Collective Intelligence to Route Internet Traffic

NASA Technical Reports Server (NTRS)

Wolpert, David H.; Tumer, Kagan; Frank, Jeremy

1998-01-01

A Collective Intelligence (COIN) is a community of interacting reinforcement learning (RL) algorithms designed so that their collective behavior maximizes a global utility function. We introduce the theory of COINs, then present experiments using that theory to design COINs to control internet traffic routing. These experiments indicate that COINs outperform previous RL-based systems for such routing that have previously been investigated.

A Multidimensional Ideal Point Item Response Theory Model for Binary Data

ERIC Educational Resources Information Center

Maydeu-Olivares, Albert; Hernandez, Adolfo; McDonald, Roderick P.

2006-01-01

We introduce a multidimensional item response theory (IRT) model for binary data based on a proximity response mechanism. Under the model, a respondent at the mode of the item response function (IRF) endorses the item with probability one. The mode of the IRF is the ideal point, or in the multidimensional case, an ideal hyperplane. The model…

Dynamic Geometry Software and Tracing Tangents in the Context of the Mean Value Theorem: Technique and Theory Production

ERIC Educational Resources Information Center

Martínez-Hernández, Cesar; Ulloa-Azpeitia, Ricardo

2017-01-01

Based on the theoretical elements of the instrumental approach to tool use known as Task-Technique-Theory (Artigue, 2002), this paper analyses and discusses the performance of graduate students enrolled in a Teacher Training program. The latter performance relates to tracing tangent lines to the curve of a quadratic function in Dynamic Geometry…

Plain Speaking: A Theory and Grammar of Spontaneous Discourse.

DTIC Science & Technology

1981-06-01

reveals surface linguistic phenomena that contradict traditional theories based on single sentence studies and longer texts artificially constructed...Excerpt 1 , Chapter 1, to illustrate the importance of functional development and discernment. In the midst of discussing the case of two twins under study ...his social interactive behavior in kindergarten. Authority: Source: Study Method : Investigative filming of kids over time. Credentials: Excellent

Research on collaborative innovation mechanism of green construction supply chain based on united agency

NASA Astrophysics Data System (ADS)

Zhang, Min; He, Weiyi

2018-06-01

Under the guidance of principal-agent theory and modular theory, the collaborative innovation of green technology-based companies, design contractors and project builders based on united agency will provide direction for the development of green construction supply chain in the future. After analyzing the existing independent agencies, this paper proposes the industry-university-research bilateral collaborative innovation network architecture and modularization with the innovative function of engineering design in the context of non-standard transformation interfaces, analyzes the innovation responsibility center, and gives some countermeasures and suggestions to promote the performance of bilateral cooperative innovation network.

On the distribution of a product of N Gaussian random variables

NASA Astrophysics Data System (ADS)

Stojanac, Željka; Suess, Daniel; Kliesch, Martin

2017-08-01

The product of Gaussian random variables appears naturally in many applications in probability theory and statistics. It has been known that the distribution of a product of N such variables can be expressed in terms of a Meijer G-function. Here, we compute a similar representation for the corresponding cumulative distribution function (CDF) and provide a power-log series expansion of the CDF based on the theory of the more general Fox H-functions. Numerical computations show that for small values of the argument the CDF of products of Gaussians is well approximated by the lowest orders of this expansion. Analogous results are also shown for the absolute value as well as the square of such products of N Gaussian random variables. For the latter two settings, we also compute the moment generating functions in terms of Meijer G-functions.

Four-body correlation embedded in antisymmetrized geminal power wave function.

PubMed

Kawasaki, Airi; Sugino, Osamu

2016-12-28

We extend the Coleman's antisymmetrized geminal power (AGP) to develop a wave function theory that can incorporate up to four-body correlation in a region of strong correlation. To facilitate the variational determination of the wave function, the total energy is rewritten in terms of the traces of geminals. This novel trace formula is applied to a simple model system consisting of one dimensional Hubbard ring with a site of strong correlation. Our scheme significantly improves the result obtained by the AGP-configuration interaction scheme of Uemura et al. and also achieves more efficient compression of the degrees of freedom of the wave function. We regard the result as a step toward a first-principles wave function theory for a strongly correlated point defect or adsorbate embedded in an AGP-based mean-field medium.

Nonlocal kinetic energy functional from the jellium-with-gap model: Applications to orbital-free density functional theory

NASA Astrophysics Data System (ADS)

Constantin, Lucian A.; Fabiano, Eduardo; Della Sala, Fabio

2018-05-01

Orbital-free density functional theory (OF-DFT) promises to describe the electronic structure of very large quantum systems, being its computational cost linear with the system size. However, the OF-DFT accuracy strongly depends on the approximation made for the kinetic energy (KE) functional. To date, the most accurate KE functionals are nonlocal functionals based on the linear-response kernel of the homogeneous electron gas, i.e., the jellium model. Here, we use the linear-response kernel of the jellium-with-gap model to construct a simple nonlocal KE functional (named KGAP) which depends on the band-gap energy. In the limit of vanishing energy gap (i.e., in the case of metals), the KGAP is equivalent to the Smargiassi-Madden (SM) functional, which is accurate for metals. For a series of semiconductors (with different energy gaps), the KGAP performs much better than SM, and results are close to the state-of-the-art functionals with sophisticated density-dependent kernels.

A Systematic Approach for Computing Zero-Point Energy, Quantum Partition Function, and Tunneling Effect Based on Kleinert's Variational Perturbation Theory.

PubMed

Wong, Kin-Yiu; Gao, Jiali

2008-09-09

In this paper, we describe an automated integration-free path-integral (AIF-PI) method, based on Kleinert's variational perturbation (KP) theory, to treat internuclear quantum-statistical effects in molecular systems. We have developed an analytical method to obtain the centroid potential as a function of the variational parameter in the KP theory, which avoids numerical difficulties in path-integral Monte Carlo or molecular dynamics simulations, especially at the limit of zero-temperature. Consequently, the variational calculations using the KP theory can be efficiently carried out beyond the first order, i.e., the Giachetti-Tognetti-Feynman-Kleinert variational approach, for realistic chemical applications. By making use of the approximation of independent instantaneous normal modes (INM), the AIF-PI method can readily be applied to many-body systems. Previously, we have shown that in the INM approximation, the AIF-PI method is accurate for computing the quantum partition function of a water molecule (3 degrees of freedom) and the quantum correction factor for the collinear H(3) reaction rate (2 degrees of freedom). In this work, the accuracy and properties of the KP theory are further investigated by using the first three order perturbations on an asymmetric double-well potential, the bond vibrations of H(2), HF, and HCl represented by the Morse potential, and a proton-transfer barrier modeled by the Eckart potential. The zero-point energy, quantum partition function, and tunneling factor for these systems have been determined and are found to be in excellent agreement with the exact quantum results. Using our new analytical results at the zero-temperature limit, we show that the minimum value of the computed centroid potential in the KP theory is in excellent agreement with the ground state energy (zero-point energy) and the position of the centroid potential minimum is the expectation value of particle position in wave mechanics. The fast convergent property of the KP theory is further examined in comparison with results from the traditional Rayleigh-Ritz variational approach and Rayleigh-Schrödinger perturbation theory in wave mechanics. The present method can be used for thermodynamic and quantum dynamic calculations, including to systematically determine the exact value of zero-point energy and to study kinetic isotope effects for chemical reactions in solution and in enzymes.

Viable inflationary evolution from Einstein frame loop quantum cosmology

NASA Astrophysics Data System (ADS)

de Haro, Jaume; Odintsov, S. D.; Oikonomou, V. K.

2018-04-01

In this work we construct a bottom-up reconstruction technique for loop quantum cosmology scalar-tensor theories, from the observational indices. Particularly, the reconstruction technique is based on fixing the functional form of the scalar-to-tensor ratio as a function of the e -foldings number. The aim of the technique is to realize viable inflationary scenarios, and the only assumption that must hold true in order for the reconstruction technique to work is that the dynamical evolution of the scalar field obeys the slow-roll conditions. We use two functional forms for the scalar-to-tensor ratio, one of which corresponds to a popular inflationary class of models, the α attractors. For the latter, we calculate the leading order behavior of the spectral index and we demonstrate that the resulting inflationary theory is viable and compatible with the latest Planck and BICEP2/Keck-Array data. In addition, we find the classical limit of the theory, and as we demonstrate, the loop quantum cosmology corrected theory and the classical theory are identical at leading order in the perturbative expansion quantified by the parameter ρc, which is the critical density of the quantum theory. Finally, by using the formalism of slow-roll scalar-tensor loop quantum cosmology, we investigate how several inflationary potentials can be realized by the quantum theory, and we calculate directly the slow-roll indices and the corresponding observational indices. In addition, the f (R ) gravity frame picture is presented.

Carving out the end of the world or (superconformal bootstrap in six dimensions)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chang, Chi-Ming; Lin, Ying-Hsuan

We bootstrap N=(1,0) superconformal field theories in six dimensions, by analyzing the four-point function of flavor current multiplets. By assuming E 8 flavor group, we present universal bounds on the central charge C T and the flavor central charge C J. Based on the numerical data, we conjecture that the rank-one E-string theory saturates the universal lower bound on C J , and numerically determine the spectrum of long multiplets in the rank-one E-string theory. We comment on the possibility of solving the higher-rank E-string theories by bootstrap and thereby probing M-theory on AdS 7×S 4/Z 2 .

Carving out the end of the world or (superconformal bootstrap in six dimensions)

DOE PAGES

Chang, Chi-Ming; Lin, Ying-Hsuan

2017-08-29

We bootstrap N=(1,0) superconformal field theories in six dimensions, by analyzing the four-point function of flavor current multiplets. By assuming E 8 flavor group, we present universal bounds on the central charge C T and the flavor central charge C J. Based on the numerical data, we conjecture that the rank-one E-string theory saturates the universal lower bound on C J , and numerically determine the spectrum of long multiplets in the rank-one E-string theory. We comment on the possibility of solving the higher-rank E-string theories by bootstrap and thereby probing M-theory on AdS 7×S 4/Z 2 .

Beta value coupled wave theory for nonslanted reflection gratings.

PubMed

Neipp, Cristian; Francés, Jorge; Gallego, Sergi; Bleda, Sergio; Martínez, Francisco Javier; Pascual, Inmaculada; Beléndez, Augusto

2014-01-01

We present a modified coupled wave theory to describe the properties of nonslanted reflection volume diffraction gratings. The method is based on the beta value coupled wave theory, which will be corrected by using appropriate boundary conditions. The use of this correction allows predicting the efficiency of the reflected order for nonslanted reflection gratings embedded in two media with different refractive indices. The results obtained by using this method will be compared to those obtained using a matrix method, which gives exact solutions in terms of Mathieu functions, and also to Kogelnik's coupled wave theory. As will be demonstrated, the technique presented in this paper means a significant improvement over Kogelnik's coupled wave theory.

Beta Value Coupled Wave Theory for Nonslanted Reflection Gratings

PubMed Central

Neipp, Cristian; Francés, Jorge; Gallego, Sergi; Bleda, Sergio; Martínez, Francisco Javier; Pascual, Inmaculada; Beléndez, Augusto

2014-01-01

We present a modified coupled wave theory to describe the properties of nonslanted reflection volume diffraction gratings. The method is based on the beta value coupled wave theory, which will be corrected by using appropriate boundary conditions. The use of this correction allows predicting the efficiency of the reflected order for nonslanted reflection gratings embedded in two media with different refractive indices. The results obtained by using this method will be compared to those obtained using a matrix method, which gives exact solutions in terms of Mathieu functions, and also to Kogelnik's coupled wave theory. As will be demonstrated, the technique presented in this paper means a significant improvement over Kogelnik's coupled wave theory. PMID:24723811

An introduction to generalized functions with some applications in aerodynamics and aeroacoustics

NASA Technical Reports Server (NTRS)

Farassat, F.

1994-01-01

In this paper, we start with the definition of generalized functions as continuous linear functionals on the space of infinitely differentiable functions with compact support. The concept of generalization differentiation is introduced next. This is the most important concept in generalized function theory and the applications we present utilize mainly this concept. First, some of the results of classical analysis, such as Leibniz rule of differentiation under the integral sign and the divergence theorem, are derived using the generalized function theory. It is shown that the divergence theorem remains valid for discontinuous vector fields provided that the derivatives are all viewed as generalized derivatives. This implies that all conservation laws of fluid mechanics are valid as they stand for discontinuous fields with all derivatives treated as generalized deriatives. Once these derivatives are written as ordinary derivatives and jumps in the field parameters across discontinuities, the jump conditions can be easily found. For example, the unsteady shock jump conditions can be derived from mass and momentum conservation laws. By using a generalized function theory, this derivative becomes trivial. Other applications of the generalized function theory in aerodynamics discussed in this paper are derivation of general transport theorems for deriving governing equations of fluid mechanics, the interpretation of finite part of divergent integrals, derivation of Oswatiitsch integral equation of transonic flow, and analysis of velocity field discontinuities as sources of vorticity. Applications in aeroacoustics presented here include the derivation of the Kirchoff formula for moving surfaces,the noise from moving surfaces, and shock noise source strength based on the Ffowcs Williams-Hawkings equation.

Relativistic density functional theory with picture-change corrected electron density based on infinite-order Douglas-Kroll-Hess method

NASA Astrophysics Data System (ADS)

Oyama, Takuro; Ikabata, Yasuhiro; Seino, Junji; Nakai, Hiromi

2017-07-01

This Letter proposes a density functional treatment based on the two-component relativistic scheme at the infinite-order Douglas-Kroll-Hess (IODKH) level. The exchange-correlation energy and potential are calculated using the electron density based on the picture-change corrected density operator transformed by the IODKH method. Numerical assessments indicated that the picture-change uncorrected density functional terms generate significant errors, on the order of hartree for heavy atoms. The present scheme was found to reproduce the energetics in the four-component treatment with high accuracy.

Magnetic order at a single-crystal surface in the diffuse-scattering theory

NASA Astrophysics Data System (ADS)

Zasada, I.

2003-06-01

A theoretical description of incoherent spin-dependent multiple scattering of electrons at a magnetically disordered single-crystal surface is reported. A formalism in which the spin operators specify the magnetic state of a surface atom is used for the description of magnetic order at the surface. The theory is based upon the concepts used in multiple scattering spin-dependent diffuse LEED theory (DSPLEED) theory. In the present considerations, this theory is extended to the case of magnetic materials by using the time-independent Dirac equation with an effective magnetic field. Thus, an expression for incoherent spin-dependent intensity for magnetic material is obtained. It depends on the Fourier transform on the surface lattice of the spin-pair correlation function and, as a consequence, on the magnetic properties of the surface. The equations for the description of magnetization and various correlation functions in the frame of effective field theory are derived and the results of the numerical calculations are presented for the particular case of Ni(1 0 0) surface. The spin-orbit induced and exchange asymmetries are calculated. It is found that the magnetic DSPLEED is sensitive to the properties of the surface characterized by the spin-pair correlation functions. Thus, it is demonstrated that the magnetic DSPLEED can be an effective method in the investigation of critical behaviour of magnetic surfaces.

Lensing-induced morphology changes in CMB temperature maps in modified gravity theories

DOE Office of Scientific and Technical Information (OSTI.GOV)

Munshi, D.; Coles, P.; Hu, B.

2016-04-01

Lensing of the Cosmic Microwave Background (CMB) changes the morphology of pattern of temperature fluctuations, so topological descriptors such as Minkowski Functionals can probe the gravity model responsible for the lensing. We show how the recently introduced two-to-two and three-to-one kurt-spectra (and their associated correlation functions), which depend on the power spectrum of the lensing potential, can be used to probe modified gravity theories such as f ( R ) theories of gravity and quintessence models. We also investigate models based on effective field theory, which include the constant-Ω model, and low-energy Hořava theories. Estimates of the cumulative signal-to-noise formore » detection of lensing-induced morphology changes, reaches O(10{sup 3}) for the future planned CMB polarization mission COrE{sup +}. Assuming foreground removal is possible to ℓ{sub max}=3000, we show that many modified gravity theories can be rejected with a high level of significance, making this technique comparable in power to galaxy weak lensing or redshift surveys. These topological estimators are also useful in distinguishing lensing from other scattering secondaries at the level of the four-point function or trispectrum. Examples include the kinetic Sunyaev-Zel'dovich (kSZ) effect which shares, with lensing, a lack of spectral distortion. We also discuss the complication of foreground contamination from unsubtracted point sources.« less

Reliability analysis in interdependent smart grid systems

NASA Astrophysics Data System (ADS)

Peng, Hao; Kan, Zhe; Zhao, Dandan; Han, Jianmin; Lu, Jianfeng; Hu, Zhaolong

2018-06-01

Complex network theory is a useful way to study many real complex systems. In this paper, a reliability analysis model based on complex network theory is introduced in interdependent smart grid systems. In this paper, we focus on understanding the structure of smart grid systems and studying the underlying network model, their interactions, and relationships and how cascading failures occur in the interdependent smart grid systems. We propose a practical model for interdependent smart grid systems using complex theory. Besides, based on percolation theory, we also study the effect of cascading failures effect and reveal detailed mathematical analysis of failure propagation in such systems. We analyze the reliability of our proposed model caused by random attacks or failures by calculating the size of giant functioning components in interdependent smart grid systems. Our simulation results also show that there exists a threshold for the proportion of faulty nodes, beyond which the smart grid systems collapse. Also we determine the critical values for different system parameters. In this way, the reliability analysis model based on complex network theory can be effectively utilized for anti-attack and protection purposes in interdependent smart grid systems.

Social competence intervention for youth with Asperger Syndrome and high-functioning autism: an initial investigation.

PubMed

Stichter, Janine P; Herzog, Melissa J; Visovsky, Karen; Schmidt, Carla; Randolph, Jena; Schultz, Tia; Gage, Nicholas

2010-09-01

Individuals with high functioning autism (HFA) or Asperger Syndrome (AS) exhibit difficulties in the knowledge or correct performance of social skills. This subgroup's social difficulties appear to be associated with deficits in three social cognition processes: theory of mind, emotion recognition and executive functioning. The current study outlines the development and initial administration of the group-based Social Competence Intervention (SCI), which targeted these deficits using cognitive behavioral principles. Across 27 students age 11-14 with a HFA/AS diagnosis, results indicated significant improvement on parent reports of social skills and executive functioning. Participants evidenced significant growth on direct assessments measuring facial expression recognition, theory of mind and problem solving. SCI appears promising, however, larger samples and application in naturalistic settings are warranted.

Ramsay-Curve Differential Item Functioning

ERIC Educational Resources Information Center

Woods, Carol M.

2011-01-01

Differential item functioning (DIF) occurs when an item on a test, questionnaire, or interview has different measurement properties for one group of people versus another, irrespective of true group-mean differences on the constructs being measured. This article is focused on item response theory based likelihood ratio testing for DIF (IRT-LR or…

Public Relations Roles and Systems Theory: Functional and Historicist Causal Models.

ERIC Educational Resources Information Center

Broom, Glen M.

The effectiveness of an organizations's adaptive behavior depends on the extent to which public relations concerns are considered in goal setting and program planning. The following five open systems propositions, based on a "functional" paradigm, address the complex relationship between public relations and organizational intelligence and do not…

Implementation of a method for calculating temperature-dependent resistivities in the KKR formalism

NASA Astrophysics Data System (ADS)

Mahr, Carsten E.; Czerner, Michael; Heiliger, Christian

2017-10-01

We present a method to calculate the electron-phonon induced resistivity of metals in scattering-time approximation based on the nonequilibrium Green's function formalism. The general theory as well as its implementation in a density-functional theory based Korringa-Kohn-Rostoker code are described and subsequently verified by studying copper as a test system. We model the thermal expansion by fitting a Debye-Grüneisen curve to experimental data. Both the electronic and vibrational structures are discussed for different temperatures, and employing a Wannier interpolation of these quantities we evaluate the scattering time by integrating the electron linewidth on a triangulation of the Fermi surface. Based thereupon, the temperature-dependent resistivity is calculated and found to be in good agreement with experiment. We show that the effect of thermal expansion has to be considered in the whole calculation regime. Further, for low temperatures, an accurate sampling of the Fermi surface becomes important.

Gas-Kinetic Theory Based Flux Splitting Method for Ideal Magnetohydrodynamics

NASA Technical Reports Server (NTRS)

Xu, Kun

1998-01-01

A gas-kinetic solver is developed for the ideal magnetohydrodynamics (MHD) equations. The new scheme is based on the direct splitting of the flux function of the MHD equations with the inclusion of "particle" collisions in the transport process. Consequently, the artificial dissipation in the new scheme is much reduced in comparison with the MHD Flux Vector Splitting Scheme. At the same time, the new scheme is compared with the well-developed Roe-type MHD solver. It is concluded that the kinetic MHD scheme is more robust and efficient than the Roe- type method, and the accuracy is competitive. In this paper the general principle of splitting the macroscopic flux function based on the gas-kinetic theory is presented. The flux construction strategy may shed some light on the possible modification of AUSM- and CUSP-type schemes for the compressible Euler equations, as well as to the development of new schemes for a non-strictly hyperbolic system.

An Analysis of Grade 11 Learners' Levels of Understanding of Functions in Terms of APOS Theory

ERIC Educational Resources Information Center

Chimhande, Tinoda; Naidoo, Ana; Stols, Gerrit

2017-01-01

This article reports on a study of six Grade 11 learners' levels of understanding of concepts related to the function definition and representation. Task-based clinical interviews were used to elicit the learners' interpretations and reasoning when working with these function-related concepts. Indicators for Action-Process-Object-Schema (APOS)…

On the role of general system theory for functional neuroimaging.

PubMed

Stephan, Klaas Enno

2004-12-01

One of the most important goals of neuroscience is to establish precise structure-function relationships in the brain. Since the 19th century, a major scientific endeavour has been to associate structurally distinct cortical regions with specific cognitive functions. This was traditionally accomplished by correlating microstructurally defined areas with lesion sites found in patients with specific neuropsychological symptoms. Modern neuroimaging techniques with high spatial resolution have promised an alternative approach, enabling non-invasive measurements of regionally specific changes of brain activity that are correlated with certain components of a cognitive process. Reviewing classic approaches towards brain structure-function relationships that are based on correlational approaches, this article argues that these approaches are not sufficient to provide an understanding of the operational principles of a dynamic system such as the brain but must be complemented by models based on general system theory. These models reflect the connectional structure of the system under investigation and emphasize context-dependent couplings between the system elements in terms of effective connectivity. The usefulness of system models whose parameters are fitted to measured functional imaging data for testing hypotheses about structure-function relationships in the brain and their potential for clinical applications is demonstrated by several empirical examples.

On the role of general system theory for functional neuroimaging

PubMed Central

Stephan, Klaas Enno

2004-01-01

One of the most important goals of neuroscience is to establish precise structure–function relationships in the brain. Since the 19th century, a major scientific endeavour has been to associate structurally distinct cortical regions with specific cognitive functions. This was traditionally accomplished by correlating microstructurally defined areas with lesion sites found in patients with specific neuropsychological symptoms. Modern neuroimaging techniques with high spatial resolution have promised an alternative approach, enabling non-invasive measurements of regionally specific changes of brain activity that are correlated with certain components of a cognitive process. Reviewing classic approaches towards brain structure–function relationships that are based on correlational approaches, this article argues that these approaches are not sufficient to provide an understanding of the operational principles of a dynamic system such as the brain but must be complemented by models based on general system theory. These models reflect the connectional structure of the system under investigation and emphasize context-dependent couplings between the system elements in terms of effective connectivity. The usefulness of system models whose parameters are fitted to measured functional imaging data for testing hypotheses about structure–function relationships in the brain and their potential for clinical applications is demonstrated by several empirical examples. PMID:15610393

An automated integration-free path-integral method based on Kleinert's variational perturbation theory

NASA Astrophysics Data System (ADS)

Wong, Kin-Yiu; Gao, Jiali

2007-12-01

Based on Kleinert's variational perturbation (KP) theory [Path Integrals in Quantum Mechanics, Statistics, Polymer Physics, and Financial Markets, 3rd ed. (World Scientific, Singapore, 2004)], we present an analytic path-integral approach for computing the effective centroid potential. The approach enables the KP theory to be applied to any realistic systems beyond the first-order perturbation (i.e., the original Feynman-Kleinert [Phys. Rev. A 34, 5080 (1986)] variational method). Accurate values are obtained for several systems in which exact quantum results are known. Furthermore, the computed kinetic isotope effects for a series of proton transfer reactions, in which the potential energy surfaces are evaluated by density-functional theory, are in good accordance with experiments. We hope that our method could be used by non-path-integral experts or experimentalists as a "black box" for any given system.

[What is an emotion? An introduction to the study of emotions].

PubMed

Derouesné, Christian

2011-03-01

Human emotions are hypothetic constructs based on psychological and physiological data. According to the psychoevolutionnist theories, all emotions derive from a set of discrete basic emotions, common to human and animals, genetically determined. Basic emotions are thus considered as physiological processes based on specific neuronal circuits. On the contrary, for appraisal and social theories, emotions are psychological processes resulting from the cognitive appraisal of the stimulus-event for the well-being and objectives of the subject, and are of social origin. They develop during life, especially in childhood, from interactions between the individual and his environement. According to the appraisal or constructivist theories, no sharp distinction is to be made between emotions and other manifestations of the affective life. Emotions require the global functioning of the brain, even if more specialized regions are involved. They play a fundamental role in the development of the child's psychological and social life. They mediate the subject's response to the stimulus-event, allowing more appropriate reactions than fixed instinctive ones. Nevertheless, the adaptative function of every emotion or their every component can be questioned. Emotional disturbances are major consequences of psychiatric or neurological disorders. The link between the results of neuropsychological studies of emotions based on the recognition of emotional facal expression according to the basic emotion theory, and the emotional disturbances experienced in daily life is highly questionable on account of the high complexity of human affective life.

Nanofilter platform based on functionalized carbon nanotubes for adsorption and elimination of Acrolein, a toxicant in cigarette smoke

NASA Astrophysics Data System (ADS)

Yoosefian, Mehdi; Pakpour, Atef; Etminan, Nazanin

2018-06-01

This paper discusses the use of carboxylated single-walled carbon nanotube as a general nanofilter platform for the removal of acrolein carcinogen from cigarette smoke. The analyses carried out in the detailed study of the electronic and structural effects of the adsorption of acrolein onto COOH loaded on single-walled carbon nanotube under the density functional theory framework. The results of Bader theory of atoms in molecules, natural bond orbital, molecular potential electron surface and density of state confirm the potential application of the suggested nanofilter platform.

Theoretical studies of electronically excited states

DOE Office of Scientific and Technical Information (OSTI.GOV)

Besley, Nicholas A.

2014-10-06

Time-dependent density functional theory is the most widely used quantum chemical method for studying molecules in electronically excited states. However, excited states can also be computed within Kohn-Sham density functional theory by exploiting methods that converge the self-consistent field equations to give excited state solutions. The usefulness of single reference self-consistent field based approaches for studying excited states is demonstrated by considering the calculation of several types of spectroscopy including the infrared spectroscopy of molecules in an electronically excited state, the rovibrational spectrum of the NO-Ar complex, core electron binding energies and the emission spectroscopy of BODIPY in water.

[Analysis of Conformational Features of Watson-Crick Duplex Fragments by Molecular Mechanics and Quantum Mechanics Methods].

PubMed

Poltev, V I; Anisimov, V M; Sanchez, C; Deriabina, A; Gonzalez, E; Garcia, D; Rivas, F; Polteva, N A

2016-01-01

It is generally accepted that the important characteristic features of the Watson-Crick duplex originate from the molecular structure of its subunits. However, it still remains to elucidate what properties of each subunit are responsible for the significant characteristic features of the DNA structure. The computations of desoxydinucleoside monophosphates complexes with Na-ions using density functional theory revealed a pivotal role of DNA conformational properties of single-chain minimal fragments in the development of unique features of the Watson-Crick duplex. We found that directionality of the sugar-phosphate backbone and the preferable ranges of its torsion angles, combined with the difference between purines and pyrimidines. in ring bases, define the dependence of three-dimensional structure of the Watson-Crick duplex on nucleotide base sequence. In this work, we extended these density functional theory computations to the minimal' fragments of DNA duplex, complementary desoxydinucleoside monophosphates complexes with Na-ions. Using several computational methods and various functionals, we performed a search for energy minima of BI-conformation for complementary desoxydinucleoside monophosphates complexes with different nucleoside sequences. Two sequences are optimized using ab initio method at the MP2/6-31++G** level of theory. The analysis of torsion angles, sugar ring puckering and mutual base positions of optimized structures demonstrates that the conformational characteristic features of complementary desoxydinucleoside monophosphates complexes with Na-ions remain within BI ranges and become closer to the corresponding characteristic features of the Watson-Crick duplex crystals. Qualitatively, the main characteristic features of each studied complementary desoxydinucleoside monophosphates complex remain invariant when different computational methods are used, although the quantitative values of some conformational parameters could vary lying within the limits typical for the corresponding family. We observe that popular functionals in density functional theory calculations lead to the overestimated distances between base pairs, while MP2 computations and the newer complex functionals produce the structures that have too close atom-atom contacts. A detailed study of some complementary desoxydinucleoside monophosphate complexes with Na-ions highlights the existence of several energy minima corresponding to BI-conformations, in other words, the complexity of the relief pattern of the potential energy surface of complementary desoxydinucleoside monophosphate complexes. This accounts for variability of conformational parameters of duplex fragments with the same base sequence. Popular molecular mechanics force fields AMBER and CHARMM reproduce most of the conformational characteristics of desoxydinucleoside monophosphates and their complementary complexes with Na-ions but fail to reproduce some details of the dependence of the Watson-Crick duplex conformation on the nucleotide sequence.

Social cognition in anorexia nervosa: evidence of preserved theory of mind and impaired emotional functioning.

PubMed

Adenzato, Mauro; Todisco, Patrizia; Ardito, Rita B

2012-01-01

The findings of the few studies that have to date investigated the way in which individuals with Anorexia Nervosa (AN) navigate their social environment are somewhat contradictory. We undertook this study to shed new light on the social-cognitive profile of patients with AN, analysing Theory of Mind and emotional functioning. Starting from previous evidence on the role of the amygdala in the neurobiology of AN and in the social cognition, we hypothesise preserved Theory of Mind and impaired emotional functioning in patients with AN. Thirty women diagnosed with AN and thirty-two women matched for education and age were involved in the study. Theory of Mind and emotional functioning were assessed with a set of validated experimental tasks. A measure of perceived social support was also used to test the correlations between this dimension and the social-cognitive profile of AN patients. The performance of patients with AN is significantly worse than that of healthy controls on tasks assessing emotional functioning, whereas patients' performance is comparable to that of healthy controls on the Theory of Mind task. Correlation analyses showed no relationship between scores on any of the social-cognition tasks and either age of onset or duration of illness. A correlation between social support and emotional functioning was found. This latter result seems to suggest a potential role of social support in the treatment and recovery of AN. The pattern of results followed the experimental hypothesis. They may be useful to help us better understand the social-cognitive profile of patients with AN and to contribute to the development of effective interventions based on the ways in which patients with AN actually perceive their social environment.

Development of affective theory of mind across adolescence: disentangling the role of executive functions.

PubMed

Vetter, Nora C; Altgassen, Mareike; Phillips, Louise; Mahy, Caitlin E V; Kliegel, Matthias

2013-01-01

Theory of mind, the ability to understand mental states, involves inferences about others' cognitive (cognitive theory of mind) and emotional (affective theory of mind) mental states. The current study explored the role of executive functions in developing affective theory of mind across adolescence. Affective theory of mind and three subcomponents of executive functions (inhibition, updating, and shifting) were measured. Affective theory of mind was positively related to age, and all three executive functions. Specifically, inhibition explained the largest amount of variance in age-related differences in affective theory of mind.

Stress-strain state on non-thin plates and shells. Generalized theory (survey)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nemish, Yu.N.; Khoma, I.Yu.

1994-05-01

In the first part of this survey, we examined exact and approximate analytic solutions of specific problems for thick shells and plates obtained on the basis of three-dimensional equations of the mathematical theory of elasticity. The second part of the survey, presented here, is devoted to systematization and analysis of studies made in regard to a generalized theory of plates and shells based on expansion of the sought functions into Fourier series in Legendre polynomials of the thickness coordinate. Methods are described for constructing systems of differential equations in the coefficients of the expansions (as functions of two independent variablesmore » and time), along with the corresponding boundary and initial conditions. Matters relating to substantiation of the given approach and its generalizations are also discussed.« less

Advanced capabilities for materials modelling with Quantum ESPRESSO

NASA Astrophysics Data System (ADS)

Giannozzi, P.; Andreussi, O.; Brumme, T.; Bunau, O.; Buongiorno Nardelli, M.; Calandra, M.; Car, R.; Cavazzoni, C.; Ceresoli, D.; Cococcioni, M.; Colonna, N.; Carnimeo, I.; Dal Corso, A.; de Gironcoli, S.; Delugas, P.; DiStasio, R. A., Jr.; Ferretti, A.; Floris, A.; Fratesi, G.; Fugallo, G.; Gebauer, R.; Gerstmann, U.; Giustino, F.; Gorni, T.; Jia, J.; Kawamura, M.; Ko, H.-Y.; Kokalj, A.; Küçükbenli, E.; Lazzeri, M.; Marsili, M.; Marzari, N.; Mauri, F.; Nguyen, N. L.; Nguyen, H.-V.; Otero-de-la-Roza, A.; Paulatto, L.; Poncé, S.; Rocca, D.; Sabatini, R.; Santra, B.; Schlipf, M.; Seitsonen, A. P.; Smogunov, A.; Timrov, I.; Thonhauser, T.; Umari, P.; Vast, N.; Wu, X.; Baroni, S.

2017-11-01

Quantum EXPRESSO is an integrated suite of open-source computer codes for quantum simulations of materials using state-of-the-art electronic-structure techniques, based on density-functional theory, density-functional perturbation theory, and many-body perturbation theory, within the plane-wave pseudopotential and projector-augmented-wave approaches. Quantum EXPRESSO owes its popularity to the wide variety of properties and processes it allows to simulate, to its performance on an increasingly broad array of hardware architectures, and to a community of researchers that rely on its capabilities as a core open-source development platform to implement their ideas. In this paper we describe recent extensions and improvements, covering new methodologies and property calculators, improved parallelization, code modularization, and extended interoperability both within the distribution and with external software.

Advanced capabilities for materials modelling with Quantum ESPRESSO.

PubMed

Giannozzi, P; Andreussi, O; Brumme, T; Bunau, O; Buongiorno Nardelli, M; Calandra, M; Car, R; Cavazzoni, C; Ceresoli, D; Cococcioni, M; Colonna, N; Carnimeo, I; Dal Corso, A; de Gironcoli, S; Delugas, P; DiStasio, R A; Ferretti, A; Floris, A; Fratesi, G; Fugallo, G; Gebauer, R; Gerstmann, U; Giustino, F; Gorni, T; Jia, J; Kawamura, M; Ko, H-Y; Kokalj, A; Küçükbenli, E; Lazzeri, M; Marsili, M; Marzari, N; Mauri, F; Nguyen, N L; Nguyen, H-V; Otero-de-la-Roza, A; Paulatto, L; Poncé, S; Rocca, D; Sabatini, R; Santra, B; Schlipf, M; Seitsonen, A P; Smogunov, A; Timrov, I; Thonhauser, T; Umari, P; Vast, N; Wu, X; Baroni, S

2017-10-24

Quantum EXPRESSO is an integrated suite of open-source computer codes for quantum simulations of materials using state-of-the-art electronic-structure techniques, based on density-functional theory, density-functional perturbation theory, and many-body perturbation theory, within the plane-wave pseudopotential and projector-augmented-wave approaches. Quantum EXPRESSO owes its popularity to the wide variety of properties and processes it allows to simulate, to its performance on an increasingly broad array of hardware architectures, and to a community of researchers that rely on its capabilities as a core open-source development platform to implement their ideas. In this paper we describe recent extensions and improvements, covering new methodologies and property calculators, improved parallelization, code modularization, and extended interoperability both within the distribution and with external software.

Advanced capabilities for materials modelling with Quantum ESPRESSO.

PubMed

Andreussi, Oliviero; Brumme, Thomas; Bunau, Oana; Buongiorno Nardelli, Marco; Calandra, Matteo; Car, Roberto; Cavazzoni, Carlo; Ceresoli, Davide; Cococcioni, Matteo; Colonna, Nicola; Carnimeo, Ivan; Dal Corso, Andrea; de Gironcoli, Stefano; Delugas, Pietro; DiStasio, Robert; Ferretti, Andrea; Floris, Andrea; Fratesi, Guido; Fugallo, Giorgia; Gebauer, Ralph; Gerstmann, Uwe; Giustino, Feliciano; Gorni, Tommaso; Jia, Junteng; Kawamura, Mitsuaki; Ko, Hsin-Yu; Kokalj, Anton; Küçükbenli, Emine; Lazzeri, Michele; Marsili, Margherita; Marzari, Nicola; Mauri, Francesco; Nguyen, Ngoc Linh; Nguyen, Huy-Viet; Otero-de-la-Roza, Alberto; Paulatto, Lorenzo; Poncé, Samuel; Giannozzi, Paolo; Rocca, Dario; Sabatini, Riccardo; Santra, Biswajit; Schlipf, Martin; Seitsonen, Ari Paavo; Smogunov, Alexander; Timrov, Iurii; Thonhauser, Timo; Umari, Paolo; Vast, Nathalie; Wu, Xifan; Baroni, Stefano

2017-09-27

Quantum ESPRESSO is an integrated suite of open-source computer codes for quantum simulations of materials using state-of-the art electronic-structure techniques, based on density-functional theory, density-functional perturbation theory, and many-body perturbation theory, within the plane-wave pseudo-potential and projector-augmented-wave approaches. Quantum ESPRESSO owes its popularity to the wide variety of properties and processes it allows to simulate, to its performance on an increasingly broad array of hardware architectures, and to a community of researchers that rely on its capabilities as a core open-source development platform to implement theirs ideas. In this paper we describe recent extensions and improvements, covering new methodologies and property calculators, improved parallelization, code modularization, and extended interoperability both within the distribution and with external software. © 2017 IOP Publishing Ltd.

Multitrophic microbial interactions for eco- and agro-biotechnological processes: theory and practice.

PubMed

Saleem, Muhammad; Moe, Luke A

2014-10-01

Multitrophic level microbial loop interactions mediated by protist predators, bacteria, and viruses drive eco- and agro-biotechnological processes such as bioremediation, wastewater treatment, plant growth promotion, and ecosystem functioning. To what extent these microbial interactions are context-dependent in performing biotechnological and ecosystem processes remains largely unstudied. Theory-driven research may advance the understanding of eco-evolutionary processes underlying the patterns and functioning of microbial interactions for successful development of microbe-based biotechnologies for real world applications. This could also be a great avenue to test the validity or limitations of ecology theory for managing diverse microbial resources in an era of altering microbial niches, multitrophic interactions, and microbial diversity loss caused by climate and land use changes. Copyright © 2014 Elsevier Ltd. All rights reserved.

An evaluation of a coupled microstructural approach for the analysis of functionally graded composites via the finite-element method

NASA Technical Reports Server (NTRS)

Pindera, Marek-Jerzy; Dunn, Patrick

1995-01-01

A comparison is presented between the predictions of the finite-element analysis and a recently developed higher-order theory for functionally graded materials subjected to a thorough-thickness temperature gradient. In contrast to existing micromechanical theories that utilize classical (i.e., uncoupled) homogenization schemes to calculate micro-level and macro-level stress and displacement fields in materials with uniform or nonuniform fiber spacing (i.e., functionally graded materials), the new theory explicitly couples the microstructural details with the macrostructure of the composite. Previous thermo-elastic analysis has demonstrated that such coupling is necessary when: the temperature gradient is large with respect to the dimension of the reinforcement; the characteristic dimension of the reinforcement is large relative to the global dimensions of the composite and the number of reinforcing fibers or inclusions is small. In these circumstances, the standard micromechanical analyses based on the concept of the representative volume element used to determine average composite properties produce questionable results. The comparison between the predictions of the finite-element method and the higher-order theory presented herein establish the theory's accuracy in predicting thermal and stress fields within composites with a finite number of fibers in the thickness direction subjected to a thorough-thickness thermal gradient.

NbIT - A New Information Theory-Based Analysis of Allosteric Mechanisms Reveals Residues that Underlie Function in the Leucine Transporter LeuT

PubMed Central

LeVine, Michael V.; Weinstein, Harel

2014-01-01

Complex networks of interacting residues and microdomains in the structures of biomolecular systems underlie the reliable propagation of information from an input signal, such as the concentration of a ligand, to sites that generate the appropriate output signal, such as enzymatic activity. This information transduction often carries the signal across relatively large distances at the molecular scale in a form of allostery that is essential for the physiological functions performed by biomolecules. While allosteric behaviors have been documented from experiments and computation, the mechanism of this form of allostery proved difficult to identify at the molecular level. Here, we introduce a novel analysis framework, called N-body Information Theory (NbIT) analysis, which is based on information theory and uses measures of configurational entropy in a biomolecular system to identify microdomains and individual residues that act as (i)-channels for long-distance information sharing between functional sites, and (ii)-coordinators that organize dynamics within functional sites. Application of the new method to molecular dynamics (MD) trajectories of the occluded state of the bacterial leucine transporter LeuT identifies a channel of allosteric coupling between the functionally important intracellular gate and the substrate binding sites known to modulate it. NbIT analysis is shown also to differentiate residues involved primarily in stabilizing the functional sites, from those that contribute to allosteric couplings between sites. NbIT analysis of MD data thus reveals rigorous mechanistic elements of allostery underlying the dynamics of biomolecular systems. PMID:24785005

Vicinage effect in the energy loss of H2 dimers: Experiment and calculations based on time-dependent density-functional theory

NASA Astrophysics Data System (ADS)

Koval, N. E.; Borisov, A. G.; Rosa, L. F. S.; Stori, E. M.; Dias, J. F.; Grande, P. L.; Sánchez-Portal, D.; Muiño, R. Díez

2017-06-01

We present a combined theoretical and experimental study of the energy loss of H2+ molecular ions interacting with thin oxide and carbon films. As a result of quantum mechanical interference of the target electrons, the energy loss of a molecular projectile differs from the sum of the energy losses of individual atomic projectiles. This difference is known as the vicinage effect. Calculations based on the time-dependent density functional theory allow the first-principles description of the dynamics of target excitations produced by the correlated motion of the nucleons forming the molecule. We investigate in detail the dependence of the vicinage effect on the speed and charge state of the projectile and find an excellent agreement between calculated and measured data.

Anharmonic, dimensionality and size effects in phonon transport

NASA Astrophysics Data System (ADS)

Thomas, Iorwerth O.; Srivastava, G. P.

2017-12-01

We have developed and employed a numerically efficient semi- ab initio theory, based on density-functional and relaxation-time schemes, to examine anharmonic, dimensionality and size effects in phonon transport in three- and two-dimensional solids of different crystal symmetries. Our method uses third- and fourth-order terms in crystal Hamiltonian expressed in terms of a temperature-dependent Grüneisen’s constant. All input to numerical calculations are generated from phonon calculations based on the density-functional perturbation theory. It is found that four-phonon processes make important and measurable contribution to lattice thermal resistivity above the Debye temperature. From our numerical results for bulk Si, bulk Ge, bulk MoS2 and monolayer MoS2 we find that the sample length dependence of phonon conductivity is significantly stronger in low-dimensional solids.

Fast and accurate quantum molecular dynamics of dense plasmas across temperature regimes

DOE PAGES

Sjostrom, Travis; Daligault, Jerome

2014-10-10

Here, we develop and implement a new quantum molecular dynamics approximation that allows fast and accurate simulations of dense plasmas from cold to hot conditions. The method is based on a carefully designed orbital-free implementation of density functional theory. The results for hydrogen and aluminum are in very good agreement with Kohn-Sham (orbital-based) density functional theory and path integral Monte Carlo calculations for microscopic features such as the electron density as well as the equation of state. The present approach does not scale with temperature and hence extends to higher temperatures than is accessible in the Kohn-Sham method and lowermore » temperatures than is accessible by path integral Monte Carlo calculations, while being significantly less computationally expensive than either of those two methods.« less

Orbital-free extension to Kohn-Sham density functional theory equation of state calculations: Application to silicon dioxide

DOE PAGES

Sjostrom, Travis; Crockett, Scott

2015-09-02

The liquid regime equation of state of silicon dioxide SiO 2 is calculated via quantum molecular dynamics in the density range of 5 to 15 g/cc and with temperatures from 0.5 to 100 eV, including the α-quartz and stishovite phase Hugoniot curves. Below 8 eV calculations are based on Kohn-Sham density functional theory (DFT), and above 8 eV a new orbital-free DFT formulation, presented here, based on matching Kohn-Sham DFT calculations is employed. Recent experimental shock data are found to be in very good agreement with the current results. Finally both experimental and simulation data are used in constructing amore » new liquid regime equation of state table for SiO 2.« less

A Wigner Monte Carlo approach to density functional theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sellier, J.M., E-mail: jeanmichel.sellier@gmail.com; Dimov, I.

2014-08-01

In order to simulate quantum N-body systems, stationary and time-dependent density functional theories rely on the capacity of calculating the single-electron wave-functions of a system from which one obtains the total electron density (Kohn–Sham systems). In this paper, we introduce the use of the Wigner Monte Carlo method in ab-initio calculations. This approach allows time-dependent simulations of chemical systems in the presence of reflective and absorbing boundary conditions. It also enables an intuitive comprehension of chemical systems in terms of the Wigner formalism based on the concept of phase-space. Finally, being based on a Monte Carlo method, it scales verymore » well on parallel machines paving the way towards the time-dependent simulation of very complex molecules. A validation is performed by studying the electron distribution of three different systems, a Lithium atom, a Boron atom and a hydrogenic molecule. For the sake of simplicity, we start from initial conditions not too far from equilibrium and show that the systems reach a stationary regime, as expected (despite no restriction is imposed in the choice of the initial conditions). We also show a good agreement with the standard density functional theory for the hydrogenic molecule. These results demonstrate that the combination of the Wigner Monte Carlo method and Kohn–Sham systems provides a reliable computational tool which could, eventually, be applied to more sophisticated problems.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hégely, Bence; Nagy, Péter R.; Kállay, Mihály, E-mail: kallay@mail.bme.hu

Exact schemes for the embedding of density functional theory (DFT) and wave function theory (WFT) methods into lower-level DFT or WFT approaches are introduced utilizing orbital localization. First, a simple modification of the projector-based embedding scheme of Manby and co-workers [J. Chem. Phys. 140, 18A507 (2014)] is proposed. We also use localized orbitals to partition the system, but instead of augmenting the Fock operator with a somewhat arbitrary level-shift projector we solve the Huzinaga-equation, which strictly enforces the Pauli exclusion principle. Second, the embedding of WFT methods in local correlation approaches is studied. Since the latter methods split up themore » system into local domains, very simple embedding theories can be defined if the domains of the active subsystem and the environment are treated at a different level. The considered embedding schemes are benchmarked for reaction energies and compared to quantum mechanics (QM)/molecular mechanics (MM) and vacuum embedding. We conclude that for DFT-in-DFT embedding, the Huzinaga-equation-based scheme is more efficient than the other approaches, but QM/MM or even simple vacuum embedding is still competitive in particular cases. Concerning the embedding of wave function methods, the clear winner is the embedding of WFT into low-level local correlation approaches, and WFT-in-DFT embedding can only be more advantageous if a non-hybrid density functional is employed.« less

Designing a curriculum for communication skills training from a theory and evidence-based perspective.

PubMed

Street, Richard L; De Haes, Hanneke C J M

2013-10-01

Because quality health care delivery requires effective clinician-patient communication, successful training of health professionals requires communication skill curricula of the highest quality. Two approaches for developing medical communication curricula are a consensus approach and a theory driven approach. We propose a theory-driven, communication function framework for identifying important communication skills, one that is focused on the key goals and outcomes that need to be accomplished in clinical encounters. We discuss 7 communication functions important to medical encounters and the types of skills needed to accomplish each. The functional approach has important pedagogical implications including the importance of distinguishing the performance of a behavior (capacity) from the outcome of that behavior in context (effectiveness) and the recognition that what counts as effective communication depends on perspective (e.g., observer, patient). Consensus and theory-driven approaches to medical communication curricula are not necessarily contradictory and can be integrated to further enhance ongoing development and improvements in medical communication education. A functional approach should resonate with practicing clinicians and continuing education initiatives in that it is embraces the notion that competent communication is situation-specific as clinicians creatively use communicative skills to accomplish the key goals of the encounter. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Monte Carlo Perturbation Theory Estimates of Sensitivities to System Dimensions

DOE PAGES

Burke, Timothy P.; Kiedrowski, Brian C.

2017-12-11

Here, Monte Carlo methods are developed using adjoint-based perturbation theory and the differential operator method to compute the sensitivities of the k-eigenvalue, linear functions of the flux (reaction rates), and bilinear functions of the forward and adjoint flux (kinetics parameters) to system dimensions for uniform expansions or contractions. The calculation of sensitivities to system dimensions requires computing scattering and fission sources at material interfaces using collisions occurring at the interface—which is a set of events with infinitesimal probability. Kernel density estimators are used to estimate the source at interfaces using collisions occurring near the interface. The methods for computing sensitivitiesmore » of linear and bilinear ratios are derived using the differential operator method and adjoint-based perturbation theory and are shown to be equivalent to methods previously developed using a collision history–based approach. The methods for determining sensitivities to system dimensions are tested on a series of fast, intermediate, and thermal critical benchmarks as well as a pressurized water reactor benchmark problem with iterated fission probability used for adjoint-weighting. The estimators are shown to agree within 5% and 3σ of reference solutions obtained using direct perturbations with central differences for the majority of test problems.« less

A density matrix-based method for the linear-scaling calculation of dynamic second- and third-order properties at the Hartree-Fock and Kohn-Sham density functional theory levels.

PubMed

Kussmann, Jörg; Ochsenfeld, Christian

2007-11-28

A density matrix-based time-dependent self-consistent field (D-TDSCF) method for the calculation of dynamic polarizabilities and first hyperpolarizabilities using the Hartree-Fock and Kohn-Sham density functional theory approaches is presented. The D-TDSCF method allows us to reduce the asymptotic scaling behavior of the computational effort from cubic to linear for systems with a nonvanishing band gap. The linear scaling is achieved by combining a density matrix-based reformulation of the TDSCF equations with linear-scaling schemes for the formation of Fock- or Kohn-Sham-type matrices. In our reformulation only potentially linear-scaling matrices enter the formulation and efficient sparse algebra routines can be employed. Furthermore, the corresponding formulas for the first hyperpolarizabilities are given in terms of zeroth- and first-order one-particle reduced density matrices according to Wigner's (2n+1) rule. The scaling behavior of our method is illustrated for first exemplary calculations with systems of up to 1011 atoms and 8899 basis functions.

Exploring the Relationships among Mirror Neurons, Theory of Mind, and Achievement Goals: Towards a Model of Achievement Goal Contagion in Educational Settings

ERIC Educational Resources Information Center

Eren, Altay

2009-01-01

This article aimed to examine the relationship between mirror neuron and theory of mind functions and to explore their possible roles in the emergence of an achievement goal contagion in educational settings such as classrooms. Based on the evidence from different lines of research such as neurobiology, neuropsychology, social psychology, and…

An EQT-cDFT approach to determine thermodynamic properties of confined fluids.

PubMed

Mashayak, S Y; Motevaselian, M H; Aluru, N R

2015-06-28

We present a continuum-based approach to predict the structure and thermodynamic properties of confined fluids at multiple length-scales, ranging from a few angstroms to macro-meters. The continuum approach is based on the empirical potential-based quasi-continuum theory (EQT) and classical density functional theory (cDFT). EQT is a simple and fast approach to predict inhomogeneous density and potential profiles of confined fluids. We use EQT potentials to construct a grand potential functional for cDFT. The EQT-cDFT-based grand potential can be used to predict various thermodynamic properties of confined fluids. In this work, we demonstrate the EQT-cDFT approach by simulating Lennard-Jones fluids, namely, methane and argon, confined inside slit-like channels of graphene. We show that the EQT-cDFT can accurately predict the structure and thermodynamic properties, such as density profiles, adsorption, local pressure tensor, surface tension, and solvation force, of confined fluids as compared to the molecular dynamics simulation results.

Prediction of global vapor-liquid equilibria for mixtures containing polar and associating components with improved renormalization group theory.

PubMed

Mi, Jianguo; Tang, Yiping; Zhong, Chongli; Li, Yi-Gui

2005-11-03

Our recently improved renormalization group (RG) theory is further reformulated within the context of density functional theory. To improve the theory for polar and associating fluids, an explicit and complete expression of the theory is derived in which the density fluctuation is expanded up to the third-order term instead of the original second-order term. A new predictive equation of state based on the first-order mean spherical approximation statistical associating fluid theory (FMSA-SAFT) and the newly improved RG theory is proposed for systems containing polar and associating fluids. The calculated results for both pure fluids and mixtures are in good agreement with experimental data both inside and outside the critical region. This work demonstrates that the RG theory incorporated with the solution of FMSA is a promising route for accurately describing the global phase behavior of complex fluids and mixtures.

Combinatorial quantisation of the Euclidean torus universe

NASA Astrophysics Data System (ADS)

Meusburger, C.; Noui, K.

2010-12-01

We quantise the Euclidean torus universe via a combinatorial quantisation formalism based on its formulation as a Chern-Simons gauge theory and on the representation theory of the Drinfel'd double DSU(2). The resulting quantum algebra of observables is given by two commuting copies of the Heisenberg algebra, and the associated Hilbert space can be identified with the space of square integrable functions on the torus. We show that this Hilbert space carries a unitary representation of the modular group and discuss the role of modular invariance in the theory. We derive the classical limit of the theory and relate the quantum observables to the geometry of the torus universe.

Emergent geometric description for a topological phase transition in the Kitaev superconductor model

NASA Astrophysics Data System (ADS)

Kim, Ki-Seok; Park, Miok; Cho, Jaeyoon; Park, Chanyong

2017-10-01

Resorting to Wilsonian renormalization group (RG) transformations, we propose an emergent geometric description for a topological phase transition in the Kitaev superconductor model. An effective field theory consists of an emergent bulk action with an extra dimension, an ultraviolet (UV) boundary condition for an initial value of a coupling function, and an infrared (IR) effective action with a fully renormalized coupling function. The bulk action describes the evolution of the coupling function along the direction of the extra dimension, where the extra dimension is identified with an RG scale and the resulting equation of motion is nothing but a β function. In particular, the IR effective field theory turns out to be consistent with a Callan-Symanzik equation which takes into account both the bulk and IR boundary contributions. This derived Callan-Symanzik equation gives rise to a metric structure. Based on this emergent metric tensor, we uncover the equivalence of the entanglement entropy between the emergent geometric description and the quantum field theory in the vicinity of the quantum critical point.

Hepatitis disease detection using Bayesian theory

NASA Astrophysics Data System (ADS)

Maseleno, Andino; Hidayati, Rohmah Zahroh

2017-02-01

This paper presents hepatitis disease diagnosis using a Bayesian theory for better understanding of the theory. In this research, we used a Bayesian theory for detecting hepatitis disease and displaying the result of diagnosis process. Bayesian algorithm theory is rediscovered and perfected by Laplace, the basic idea is using of the known prior probability and conditional probability density parameter, based on Bayes theorem to calculate the corresponding posterior probability, and then obtained the posterior probability to infer and make decisions. Bayesian methods combine existing knowledge, prior probabilities, with additional knowledge derived from new data, the likelihood function. The initial symptoms of hepatitis which include malaise, fever and headache. The probability of hepatitis given the presence of malaise, fever, and headache. The result revealed that a Bayesian theory has successfully identified the existence of hepatitis disease.

Generalized nonequilibrium vertex correction method in coherent medium theory for quantum transport simulation of disordered nanoelectronics

NASA Astrophysics Data System (ADS)

Yan, Jiawei; Ke, Youqi

2016-07-01

Electron transport properties of nanoelectronics can be significantly influenced by the inevitable and randomly distributed impurities/defects. For theoretical simulation of disordered nanoscale electronics, one is interested in both the configurationally averaged transport property and its statistical fluctuation that tells device-to-device variability induced by disorder. However, due to the lack of an effective method to do disorder averaging under the nonequilibrium condition, the important effects of disorders on electron transport remain largely unexplored or poorly understood. In this work, we report a general formalism of Green's function based nonequilibrium effective medium theory to calculate the disordered nanoelectronics. In this method, based on a generalized coherent potential approximation for the Keldysh nonequilibrium Green's function, we developed a generalized nonequilibrium vertex correction method to calculate the average of a two-Keldysh-Green's-function correlator. We obtain nine nonequilibrium vertex correction terms, as a complete family, to express the average of any two-Green's-function correlator and find they can be solved by a set of linear equations. As an important result, the averaged nonequilibrium density matrix, averaged current, disorder-induced current fluctuation, and averaged shot noise, which involve different two-Green's-function correlators, can all be derived and computed in an effective and unified way. To test the general applicability of this method, we applied it to compute the transmission coefficient and its fluctuation with a square-lattice tight-binding model and compared with the exact results and other previously proposed approximations. Our results show very good agreement with the exact results for a wide range of disorder concentrations and energies. In addition, to incorporate with density functional theory to realize first-principles quantum transport simulation, we have also derived a general form of conditionally averaged nonequilibrium Green's function for multicomponent disorders.

Research on Liquidity Risk Evaluation of Chinese A-Shares Market Based on Extension Theory

NASA Astrophysics Data System (ADS)

Bai-Qing, Sun; Peng-Xiang, Liu; Lin, Zhang; Yan-Ge, Li

This research defines the liquidity risk of stock market in matter-element theory and affair-element theory, establishes the indicator system of the forewarning for liquidity risks,designs the model and the process of early warning using the extension set method, extension dependent function and the comprehensive evaluation model. And the paper studies empirically A-shares market through the data of 1A0001, which prove that the model can better describe liquidity risk of China’s A-share market. At last, it gives the corresponding policy recommendations.

Noun-phrase anaphors and focus: the informational load hypothesis.

PubMed

Almor, A

1999-10-01

The processing of noun-phrase (NP) anaphors in discourse is argued to reflect constraints on the activation and processing of semantic information in working memory. The proposed theory views NP anaphor processing as an optimization process that is based on the principle that processing cost, defined in terms of activating semantic information, should serve some discourse function--identifying the antecedent, adding new information, or both. In a series of 5 self-paced reading experiments, anaphors' functionality was manipulated by changing the discourse focus, and their cost was manipulated by changing the semantic relation between the anaphors and their antecedents. The results show that reading times of NP anaphors reflect their functional justification: Anaphors were read faster when their cost had a better functional justification. These results are incompatible with any theory that treats NP anaphors as one homogeneous class regardless of discourse function and processing cost.

Analysis of STM images with pure and CO-functionalized tips: A first-principles and experimental study

NASA Astrophysics Data System (ADS)

Gustafsson, Alexander; Okabayashi, Norio; Peronio, Angelo; Giessibl, Franz J.; Paulsson, Magnus

2017-08-01

We describe a first-principles method to calculate scanning tunneling microscopy (STM) images, and compare the results to well-characterized experiments combining STM with atomic force microscopy (AFM). The theory is based on density functional theory with a localized basis set, where the wave functions in the vacuum gap are computed by propagating the localized-basis wave functions into the gap using a real-space grid. Constant-height STM images are computed using Bardeen's approximation method, including averaging over the reciprocal space. We consider copper adatoms and single CO molecules adsorbed on Cu(111), scanned with a single-atom copper tip with and without CO functionalization. The calculated images agree with state-of-the-art experiments, where the atomic structure of the tip apex is determined by AFM. The comparison further allows for detailed interpretation of the STM images.

Phytochemical, spectroscopic and density functional theory study of Diospyrin, and non-bonding interactions of Diospyrin with atmospheric gases

NASA Astrophysics Data System (ADS)

Fazl-i-Sattar; Ullah, Zakir; Ata-ur-Rahman; Rauf, Abdur; Tariq, Muhammad; Tahir, Asif Ali; Ayub, Khurshid; Ullah, Habib

2015-04-01

Density functional theory (DFT) and phytochemical study of a natural product, Diospyrin (DO) have been carried out. A suitable level of theory was developed, based on correlating the experimental and theoretical data. Hybrid DFT method at B3LYP/6-31G (d,p) level of theory is employed for obtaining the electronic, spectroscopic, inter-molecular interaction and thermodynamic properties of DO. The exact structure of DO is confirmed from the nice validation of the theory and experiment. Non-covalent interactions of DO with different atmospheric gases such as NH3, CO2, CO, and H2O were studied to find out its electroactive nature. The experimental and predicted geometrical parameters, IR and UV-vis spectra (B3LYP/6-31+G (d,p) level of theory) show excellent correlation. Inter-molecular non-bonding interaction of DO with atmospheric gases is investigated through geometrical parameters, electronic properties, charge analysis, and thermodynamic parameters. Electronic properties include, ionization potential (I.P.), electron affinities (E.A.), electrostatic potential (ESP), density of states (DOS), HOMO, LUMO, and band gap. All these characterizations have corroborated each other and confirmed the presence of non-covalent nature in DO with the mentioned gases.

Slowly rotating homogeneous masses revisited

NASA Astrophysics Data System (ADS)

Reina, Borja

2016-02-01

Hartle's model for slowly rotating stars has been extensively used to compute equilibrium configurations of slowly rotating stars to second order in perturbation theory in general relativity, given a barotropic equation of state. A recent study based on the modern theory of perturbed matchings concludes that the functions in the (first and second order) perturbation tensors can always be taken as continuous at the surface of the star, except for the second-order function m0. This function presents a jump at the surface of the star proportional to the discontinuity of the energy density there. This concerns only a particular outcome of the model: the change in mass δM. In this paper, the amended change in mass is calculated for the case of constant density stars.

Controlled growth and form of precipitating microsculptures

NASA Astrophysics Data System (ADS)

Kaplan, C. Nadir; Noorduin, Wim L.; Li, Ling; Sadza, Roel; Folkertsma, Laura; Aizenberg, Joanna; Mahadevan, L.

2017-03-01

Controlled self-assembly of three-dimensional shapes holds great potential for fabrication of functional materials. Their practical realization requires a theoretical framework to quantify and guide the dynamic sculpting of the curved structures that often arise in accretive mineralization. Motivated by a variety of bioinspired coprecipitation patterns of carbonate and silica, we develop a geometrical theory for the kinetics of the growth front that leaves behind thin-walled complex structures. Our theory explains the range of previously observed experimental patterns and, in addition, predicts unexplored assembly pathways. This allows us to design a number of functional base shapes of optical microstructures, which we synthesize to demonstrate their light-guiding capabilities. Overall, our framework provides a way to understand and control the growth and form of functional precipitating microsculptures.

Communication: Density functional theory overcomes the failure of predicting intermolecular interaction energies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Podeszwa, Rafal; Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716; Szalewicz, Krzysztof

2012-04-28

Density-functional theory (DFT) revolutionized the ability of computational quantum mechanics to describe properties of matter and is by far the most often used method. However, all the standard variants of DFT fail to predict intermolecular interaction energies. In recent years, a number of ways to go around this problem has been proposed. We show that some of these approaches can reproduce interaction energies with median errors of only about 5% in the complete range of intermolecular configurations. Such errors are comparable to typical uncertainties of wave-function-based methods in practical applications. Thus, these DFT methods are expected to find broad applicationsmore » in modelling of condensed phases and of biomolecules.« less

Theory of Mind intervention for outpatients with schizophrenia.

PubMed

Bechi, Margherita; Spangaro, Marco; Bosia, Marta; Zanoletti, Andrea; Fresi, Francesco; Buonocore, Mariachiara; Cocchi, Federica; Guglielmino, Carmelo; Smeraldi, Enrico; Cavallaro, Roberto

2013-01-01

Social disability is one of the critical areas known to be a predictor of daily functioning in schizophrenia. Recent studies showed that impairments in Theory of Mind (ToM) contribute to real-world social functioning and are more strongly associated with community outcomes than other neuropsychological domains of cognition. Several experiments revealed an improving potential of social cognition targeted training, particularly through introduction of verbalisation and explicit manipulation of information about others' mental states. Based on these data, we evaluated longitudinally, with a controlled trial, the feasibility and efficacy of ToM training and the possible influences of daily functioning and IQ on the enhancement of ToM abilities. Thirty outpatients with schizophrenia were recruited and randomly allocated to two groups: ToM Intervention (ToMI), based on verbalisation of selected comic strips representing ToM scenarios, or active control group (ACG). Results showed a significant improvement of ToM abilities among subjects allocated to ToMI compared to ACG, confirming the hypothesis of the enhancing potential of training methods targeting ToM functions. Moreover, we observed no influences of neuropsychological and functional variables on ToM improvement. Development of future studies should take into account possible effects of ToM training on functional outcome, according to the strong associations between ToM abilities and real-world social functioning.

1,8-Naphthyridine-2,7-diamine: a potential universal reader of Watson-Crick base pairs for DNA sequencing by electron tunneling.

PubMed

Liang, Feng; Lindsay, Stuart; Zhang, Peiming

2012-11-21

With the aid of Density Functional Theory (DFT), we designed 1,8-naphthyridine-2,7-diamine as a recognition molecule to read DNA base pairs for genomic sequencing by electron tunneling. NMR studies show that it can form stable triplets with both A : T and G : C base pairs through hydrogen bonding. Our results suggest that the naphthyridine molecule should be able to function as a universal base pair reader in a tunneling gap, generating distinguishable signatures under electrical bias for each of DNA base pairs.

1,8-Naphthyridine-2,7-diamine: A Potential Universal Reader of the Watson-Crick Base Pairs for DNA Sequencing by Electron Tunneling

PubMed Central

Liang, Feng; Lindsay, Stuart; Zhang, Peiming

2013-01-01

With the aid of Density Functional Theory (DFT), we designed 1,8-naphthyridine-2,7-diamine as a recognition molecule to read the DNA base pairs for genomic sequencing by electron tunneling. NMR studies show that it can form stable triplets with both A:T and G:C base pairs through hydrogen bonding. Our results suggest that the naphthyridine molecule should be able to function as a universal base pair reader in a tunneling gap, generating distinguishable signatures under electrical bias for each of DNA base pairs. PMID:23038027

Non-empirical Prediction of the Photophysical and Magnetic Properties of Systems with Open d- and f-Shells Based on Combined Ligand Field and Density Functional Theory (LFDFT).

PubMed

Daul, Claude

2014-09-01

Despite the important growth of ab initio and computational techniques, ligand field theory in molecular science or crystal field theory in condensed matter offers the most intuitive way to calculate multiplet energy levels arising from systems with open shells d and/or f electrons. Over the past decade we have developed a ligand field treatment of inorganic molecular modelling taking advantage of the dominant localization of the frontier orbitals within the metal-sphere. This feature, which is observed in any inorganic coordination compound, especially if treated by Density Functional Theory calculation, allows the determination of the electronic structure and properties with a surprising good accuracy. In ligand field theory, the theoretical concepts consider only a single atom center; and treat its interaction with the chemical environment essentially as a perturbation. Therefore success in the simple ligand field theory is no longer questionable, while the more accurate molecular orbital theory does in general over-estimate the metal-ligand covalence, thus yields wave functions that are too delocalized. Although LF theory has always been popular as a semi-empirical method when dealing with molecules of high symmetry e.g. cubic symmetry where the number of parameters needed is reasonably small (3 or 5), this is no more the case for molecules without symmetry and involving both an open d- and f-shell (# parameters ∼90). However, the combination of LF theory and Density Functional (DF) theory that we introduced twenty years ago can easily deal with complex molecules of any symmetry with two and more open shells. The accuracy of these predictions from 1(st) principles achieves quite a high accuracy (<5%) in terms of states energies. Hence, this approach is well suited to predict the magnetic and photo-physical properties arbitrary molecules and materials prior to their synthesis, which is the ultimate goal of each computational chemist. We will illustrate the performance of LFDFT for the design of phosphors that produces light similar to our sun and predict the magnetic anisotropy energy of single ion magnets.

Recursive Techniques for Computing Gluon Scattering in Anti-de-Sitter Space

NASA Astrophysics Data System (ADS)

Shyaka, Claude; Kharel, Savan

2016-03-01

The anti-de Sitter/conformal field theory correspondence is a relationship between two kinds of physical theories. On one side of the duality are special type of quantum (conformal) field theories known as the Yang-Mills theory. These quantum field theories are known to be equivalent to theories of gravity in Anti-de Sitter (AdS) space. The physical observables in the theory are the correlation functions that live in the boundary of AdS space. In general correlation functions are computed using configuration space and the expressions are extremely complicated. Using momentum basis and recursive techniques developed by Raju, we extend tree level correlation functions for four and five-point correlation functions in Yang-Mills theory in Anti-de Sitter space. In addition, we show that for certain external helicity, the correlation functions have simple analytic structure. Finally, we discuss how one can generalize these results to n-point functions. Hendrix college odyssey Grant.

Maximum entropy formalism for the analytic continuation of matrix-valued Green's functions

NASA Astrophysics Data System (ADS)

Kraberger, Gernot J.; Triebl, Robert; Zingl, Manuel; Aichhorn, Markus

2017-10-01

We present a generalization of the maximum entropy method to the analytic continuation of matrix-valued Green's functions. To treat off-diagonal elements correctly based on Bayesian probability theory, the entropy term has to be extended for spectral functions that are possibly negative in some frequency ranges. In that way, all matrix elements of the Green's function matrix can be analytically continued; we introduce a computationally cheap element-wise method for this purpose. However, this method cannot ensure important constraints on the mathematical properties of the resulting spectral functions, namely positive semidefiniteness and Hermiticity. To improve on this, we present a full matrix formalism, where all matrix elements are treated simultaneously. We show the capabilities of these methods using insulating and metallic dynamical mean-field theory (DMFT) Green's functions as test cases. Finally, we apply the methods to realistic material calculations for LaTiO3, where off-diagonal matrix elements in the Green's function appear due to the distorted crystal structure.

A recipe for free-energy functionals of polarizable molecular fluids

NASA Astrophysics Data System (ADS)

Sundararaman, Ravishankar; Letchworth-Weaver, Kendra; Arias, T. A.

2014-04-01

Classical density-functional theory is the most direct approach to equilibrium structures and free energies of inhomogeneous liquids, but requires the construction of an approximate free-energy functional for each liquid of interest. We present a general recipe for constructing functionals for small-molecular liquids based only on bulk experimental properties and ab initio calculations of a single solvent molecule. This recipe combines the exact free energy of the non-interacting system with fundamental measure theory for the repulsive contribution and a weighted density functional for the short-ranged attractive interactions. We add to these ingredients a weighted polarization functional for the long-range correlations in both the rotational and molecular-polarizability contributions to the dielectric response. We also perform molecular dynamics calculations for the free energy of cavity formation and the high-field dielectric response, and show that our free-energy functional adequately describes these properties (which are key for accurate solvation calculations) for all three solvents in our study: water, chloroform, and carbon tetrachloride.

A new method for finding the minimum free energy pathway of ions and small molecule transportation through protein based on 3D-RISM theory and the string method

NASA Astrophysics Data System (ADS)

Yoshida, Norio

2018-05-01

A new method for finding the minimum free energy pathway (MFEP) of ions and small molecule transportation through a protein based on the three-dimensional reference interaction site model (3D-RISM) theory combined with the string method has been proposed. The 3D-RISM theory produces the distribution function, or the potential of mean force (PMF), for transporting substances around the given protein structures. By applying the string method to the PMF surface, one can readily determine the MFEP on the PMF surface. The method has been applied to consider the Na+ conduction pathway of channelrhodopsin as an example.

Global exponential stability and lag synchronization for delayed memristive fuzzy Cohen-Grossberg BAM neural networks with impulses.

PubMed

Yang, Wengui; Yu, Wenwu; Cao, Jinde; Alsaadi, Fuad E; Hayat, Tasawar

2018-02-01

This paper investigates the stability and lag synchronization for memristor-based fuzzy Cohen-Grossberg bidirectional associative memory (BAM) neural networks with mixed delays (asynchronous time delays and continuously distributed delays) and impulses. By applying the inequality analysis technique, homeomorphism theory and some suitable Lyapunov-Krasovskii functionals, some new sufficient conditions for the uniqueness and global exponential stability of equilibrium point are established. Furthermore, we obtain several sufficient criteria concerning globally exponential lag synchronization for the proposed system based on the framework of Filippov solution, differential inclusion theory and control theory. In addition, some examples with numerical simulations are given to illustrate the feasibility and validity of obtained results. Copyright © 2017 Elsevier Ltd. All rights reserved.

A density functional theory study of the magnetic exchange coupling in dinuclear manganese(II) inverse crown structures.

PubMed

Vélez, Ederley; Alberola, Antonio; Polo, Víctor

2009-12-17

The magnetic exchange coupling constants between two Mn(II) centers for a set of five inverse crown structures have been investigated by means of a methodology based on broken-symmetry unrestricted density functional theory. These novel and highly unstable compounds present superexchange interactions between two Mn centers, each one with S = 5/2 through anionic "guests" such as oxygen, benzene, or hydrides or through the cationic ring formed by amide ligands and alkali metals (Na, Li). Magnetic exchange couplings calculated at B3LYP/6-31G(d,p) level yield strong antiferromagnetic couplings for compounds linked via an oxygen atom or hydride and very small antiferromagnetic couplings for those linked via a benzene molecule, deprotonated in either 1,4- or 1,3- positions. Analysis of the magnetic orbitals and spin polarization maps provide an understanding of the exchange mechanism between the Mn centers. The dependence of J with respect to 10 different density functional theory potentials employed and the basis set has been analyzed.

Limitations of the clump-correlation theories of shear-induced turbulence suppression

NASA Astrophysics Data System (ADS)

Zhang, Y. Z.; Mahajan, S. M.

2017-05-01

The clump theory, primarily constructed by Dupree [Phys. Fluids 15, 334 (1972)] based on the moment approach and then generalized to the correlation theory [Y. Z. Zhang and S. M. Mahajan, Phys. Fluids B 5, 2000 (1993)], has long served as a basis for constructing theories of turbulence suppression by shear flow. In order to reveal the "intrinsic approximation" invoked in the clump-correlation theory, we examine a model based on two dimensional magnetized drift waves. After a rigorous derivation of the exact response function—a key to average the Green function of the system—we show that the Dupree, Zhang-Mahajan approach is recovered as the lowest order approximation in a small dimensionless parameter ϒ which is a triple product of the correlation time, wave number, and fluctuating drift velocity. The clump-correlation theory, thus, constitutes the Gaussian and lowest order non-Markovian process for a homogeneous stationary turbulence. We also provide, especially for the tokamak community, a readily usable formula to evaluate the effectiveness of shear-flow suppression; this formula pertains regardless of the specific model of correlation time.

Function projective synchronization of memristor-based Cohen-Grossberg neural networks with time-varying delays.

PubMed

Abdurahman, Abdujelil; Jiang, Haijun; Rahman, Kaysar

2015-12-01

This paper deals with the problem of function projective synchronization for a class of memristor-based Cohen-Grossberg neural networks with time-varying delays. Based on the theory of differential equations with discontinuous right-hand side, some novel criteria are obtained to realize the function projective synchronization of addressed networks by combining open loop control and linear feedback control. As some special cases, several control strategies are given to ensure the realization of complete synchronization, anti-synchronization and the stabilization of the considered memristor-based Cohen-Grossberg neural network. Finally, a numerical example and its simulations are provided to demonstrate the effectiveness of the obtained results.

The Scope of Usage-Based Theory

PubMed Central

Ibbotson, Paul

2013-01-01

Usage-based approaches typically draw on a relatively small set of cognitive processes, such as categorization, analogy, and chunking to explain language structure and function. The goal of this paper is to first review the extent to which the “cognitive commitment” of usage-based theory has had success in explaining empirical findings across domains, including language acquisition, processing, and typology. We then look at the overall strengths and weaknesses of usage-based theory and highlight where there are significant debates. Finally, we draw special attention to a set of culturally generated structural patterns that seem to lie beyond the explanation of core usage-based cognitive processes. In this context we draw a distinction between cognition permitting language structure vs. cognition entailing language structure. As well as addressing the need for greater clarity on the mechanisms of generalizations and the fundamental units of grammar, we suggest that integrating culturally generated structures within existing cognitive models of use will generate tighter predictions about how language works. PMID:23658552

Density functional study of molecular interactions in secondary structures of proteins.

PubMed

Takano, Yu; Kusaka, Ayumi; Nakamura, Haruki

2016-01-01

Proteins play diverse and vital roles in biology, which are dominated by their three-dimensional structures. The three-dimensional structure of a protein determines its functions and chemical properties. Protein secondary structures, including α-helices and β-sheets, are key components of the protein architecture. Molecular interactions, in particular hydrogen bonds, play significant roles in the formation of protein secondary structures. Precise and quantitative estimations of these interactions are required to understand the principles underlying the formation of three-dimensional protein structures. In the present study, we have investigated the molecular interactions in α-helices and β-sheets, using ab initio wave function-based methods, the Hartree-Fock method (HF) and the second-order Møller-Plesset perturbation theory (MP2), density functional theory, and molecular mechanics. The characteristic interactions essential for forming the secondary structures are discussed quantitatively.

Adsorption and oxidation of SO2 by graphene oxides: A van der Waals density functional theory study

NASA Astrophysics Data System (ADS)

Zhang, Huijuan; Cen, Wanglai; Liu, Jie; Guo, Jiaxiu; Yin, Huaqiang; Ning, Ping

2015-01-01

Carbon materials have been used for low temperature (20-150 °C) catalytic removal of SO2 from the coal-burned flue gases for a long time, but the mechanism at atomic level is still controversial. Density functional theory was used to investigate the adsorption and oxidation of SO2 on elaborated graphene oxides (GOs) to discover the insights. It is found that the hydroxyl groups on GO surface possess bi-functional effects: both enhancing the adsorption of SO2 through H-bonding interaction and reducing the reaction barrier for its oxidation to SO3. The promotion of oxidation is related to a pre-activation of the surface epoxy group. Based on Bader population, charge difference and electron localization function analysis, a charge transfer channel is proposed to explain the pre-activation.

How Reasoning, Judgment, and Decision Making are Colored by Gist-based Intuition: A Fuzzy-Trace Theory Approach

PubMed Central

Corbin, Jonathan C.; Reyna, Valerie F.; Weldon, Rebecca B.; Brainerd, Charles J.

2015-01-01

Fuzzy-trace theory distinguishes verbatim (literal, exact) from gist (meaningful) representations, predicting that reliance on gist increases with experience and expertise. Thus, many judgment-and-decision-making biases increase with development, such that cognition is colored by context in ways that violate logical coherence and probability theories. Nevertheless, this increase in gist-based intuition is adaptive: Gist is stable, less sensitive to interference, and easier to manipulate. Moreover, gist captures the functionally significant essence of information, supporting healthier and more robust decision processes. We describe how fuzzy-trace theory accounts for judgment-and-decision making phenomena, predicting the paradoxical arc of these processes with the development of experience and expertise. We present data linking gist memory processes to gist processing in decision making and provide illustrations of gist reliance in medicine, public health, and intelligence analysis. PMID:26664820

How Reasoning, Judgment, and Decision Making are Colored by Gist-based Intuition: A Fuzzy-Trace Theory Approach.

PubMed

Corbin, Jonathan C; Reyna, Valerie F; Weldon, Rebecca B; Brainerd, Charles J

2015-12-01

Fuzzy-trace theory distinguishes verbatim (literal, exact) from gist (meaningful) representations, predicting that reliance on gist increases with experience and expertise. Thus, many judgment-and-decision-making biases increase with development, such that cognition is colored by context in ways that violate logical coherence and probability theories. Nevertheless, this increase in gist-based intuition is adaptive: Gist is stable, less sensitive to interference, and easier to manipulate. Moreover, gist captures the functionally significant essence of information, supporting healthier and more robust decision processes. We describe how fuzzy-trace theory accounts for judgment-and-decision making phenomena, predicting the paradoxical arc of these processes with the development of experience and expertise. We present data linking gist memory processes to gist processing in decision making and provide illustrations of gist reliance in medicine, public health, and intelligence analysis.

What Is True Halving in the Payoff Matrix of Game Theory?

PubMed Central

Hasegawa, Eisuke; Yoshimura, Jin

2016-01-01

In game theory, there are two social interpretations of rewards (payoffs) for decision-making strategies: (1) the interpretation based on the utility criterion derived from expected utility theory and (2) the interpretation based on the quantitative criterion (amount of gain) derived from validity in the empirical context. A dynamic decision theory has recently been developed in which dynamic utility is a conditional (state) variable that is a function of the current wealth of a decision maker. We applied dynamic utility to the equal division in dove-dove contests in the hawk-dove game. Our results indicate that under the utility criterion, the half-share of utility becomes proportional to a player’s current wealth. Our results are consistent with studies of the sense of fairness in animals, which indicate that the quantitative criterion has greater validity than the utility criterion. We also find that traditional analyses of repeated games must be reevaluated. PMID:27487194

What Is True Halving in the Payoff Matrix of Game Theory?

PubMed

Ito, Hiromu; Katsumata, Yuki; Hasegawa, Eisuke; Yoshimura, Jin

2016-01-01

In game theory, there are two social interpretations of rewards (payoffs) for decision-making strategies: (1) the interpretation based on the utility criterion derived from expected utility theory and (2) the interpretation based on the quantitative criterion (amount of gain) derived from validity in the empirical context. A dynamic decision theory has recently been developed in which dynamic utility is a conditional (state) variable that is a function of the current wealth of a decision maker. We applied dynamic utility to the equal division in dove-dove contests in the hawk-dove game. Our results indicate that under the utility criterion, the half-share of utility becomes proportional to a player's current wealth. Our results are consistent with studies of the sense of fairness in animals, which indicate that the quantitative criterion has greater validity than the utility criterion. We also find that traditional analyses of repeated games must be reevaluated.

A minimal model for the structural energetics of VO2

NASA Astrophysics Data System (ADS)

Kim, Chanul; Marianetti, Chris; The Marianetti Group Team

Resolving the structural, magnetic, and electronic structure of VO2 from the first-principles of quantum mechanics is still a forefront problem despite decades of attention. Hybrid functionals have been shown to qualitatively ruin the structural energetics. While density functional theory (DFT) combined with cluster extensions of dynamical mean-field theory (DMFT) have demonstrated promising results in terms of the electronic properties, structural phase stability has not yet been addressed. In order to capture the basic physics of the structural transition, we propose a minimal model of VO2 based on the one dimensional Peierls-Hubbard model and parameterize this based on DFT calculations of VO2. The total energy versus dimerization in the minimal mode is then solved numerically exactly using density matrix renormalization group (DMRG) and compared to the Hartree-Fock solution. We demonstrate that the Hartree-Fock solution exhibits the same pathologies as DFT+U, and spin density functional theory for that matter, while the DMRG solution is consistent with experimental observation. Our results demonstrate the critical role of non-locality in the total energy, and this will need to be accounted for to obtain a complete description of VO2 from first-principles. The authors acknowledge support from FAME, one of six centers of STARnet, a Semiconductor Research Corporation program sponsored by MARCO and DARPA.

DFT treatment of transport through Anderson junction: exact results and approximations

NASA Astrophysics Data System (ADS)

Burke, Kieron

2012-02-01

Since the pioneering break-junction experiments of Reed and Tour measuring the conductance of dithiolated benzene between gold leads, many researchers in physics and chemistry have been calculating conductance for such systems using density functional theory (DFT). Off resonance, the predicted current is often 10-100 times larger than that measured. This error is often ascribed to the application of ground-state DFT to a non-equilibrium problem. I will argue that, in fact, this is largely due to errors in the density functional approximations in popular use, rather than necessarily errors in the methodology. A stark illustration of this principle is the ability of DFT to reproduce the exact transmission through an Anderson junction at zero-temperature and weak bias, including the Kondo plateau, but only if the exact ground-state density functional is used. In fact, this case can be used to reverse-engineer the exact functional for this problem. Popular approximations can also be tested, including both smooth and discontinuous functionals of the density, as well as symmetry-broken approaches. [4pt] [1] Kondo effect given exactly by density functional theory, J. P. Bergfield, Z. Liu, K. Burke, and C. A. Stafford, arXiv:1106.3104; [0pt] [2] Broadening of the Derivative Discontinuity in Density Functional Theory, F. Evers, and P. Schmitteckert, arXiv:1106.3658; [0pt] [3] DFT-based transport calculations, Friedel's sum rule and the Kondo effect, P. Tr"oster, P. Schmitteckert, and F. Evers, arXiv:1106.3669; [0pt] [4] Towards a description of the Kondo effect using time-dependent density functional theory, G. Stefanucci, and S. Kurth, arXiv:1106.3728.

Using a syndemics theory approach to study HIV risk taking in a population of men who use the internet to find partners for unprotected sex.

PubMed

Klein, Hugh

2011-11-01

This study examines the value of using syndemics theory as a model for understanding HIV risk taking in a population of men who are at great risk for acquiring and/or transmitting HIV. The principal aim is to provide an empirical test of the applicability of the theory to sexual risk behaviors in this particular research population. The study was based on a national random sample of 332 men who have sex with men, or MSM, who use the Internet to seek men with whom they can engage in unprotected sex. Data collection was conducted via telephone interviews between January 2008 and May 2009. As hypothesized in the syndemics theory model, attitudes toward condom use were central to understanding men's involvement in risky sex. As hypothesized, these attitudes depended on various demographic, psychological/psychosocial functioning, and sex-related preference measures. Also as hypothesized, psychological and psychosocial functioning were found to be very important to the overall model, and as expected, these factors were shaped greatly by factors such as demographic characteristics and childhood maltreatment experiences. The structural equation assessing the fit of the overall model indicated solid support for the syndemics theory approach. Overall, syndemics theory seems to apply fairly well to understanding the complexity of the factors that underlie men's risk-taking practices. The complicated interplay among factors such as attitudes toward condom use, childhood maltreatment experiences, psychological and psychosocial functioning, and substance use and abuse-all of which are central to a syndemics theory approach to studying risk-was demonstrated.

Evolution of the transfer function characterization of surface scatter phenomena

NASA Astrophysics Data System (ADS)

Harvey, James E.; Pfisterer, Richard N.

2016-09-01

Based upon the empirical observation that BRDF measurements of smooth optical surfaces exhibited shift-invariant behavior when plotted versus    o , the original Harvey-Shack (OHS) surface scatter theory was developed as a scalar linear systems formulation in which scattered light behavior was characterized by a surface transfer function (STF) reminiscent of the optical transfer function (OTF) of modern image formation theory (1976). This shift-invariant behavior combined with the inverse power law behavior when plotting log BRDF versus log   o was quickly incorporated into several optical analysis software packages. Although there was no explicit smooth-surface approximation in the OHS theory, there was a limitation on both the incident and scattering angles. In 1988 the modified Harvey-Shack (MHS) theory removed the limitation on the angle of incidence; however, a moderate-angle scattering limitation remained. Clearly for large incident angles the BRDF was no longer shift-invariant as a different STF was now required for each incident angle. In 2011 the generalized Harvey-Shack (GHS) surface scatter theory, characterized by a two-parameter family of STFs, evolved into a practical modeling tool to calculate BRDFs from optical surface metrology data for situations that violate the smooth surface approximation inherent in the Rayleigh-Rice theory and/or the moderate-angle limitation of the Beckmann-Kirchhoff theory. And finally, the STF can be multiplied by the classical OTF to provide a complete linear systems formulation of image quality as degraded by diffraction, geometrical aberrations and surface scatter effects from residual optical fabrication errors.

Spin-Multiplet Components and Energy Splittings by Multistate Density Functional Theory.

PubMed

Grofe, Adam; Chen, Xin; Liu, Wenjian; Gao, Jiali

2017-10-05

Kohn-Sham density functional theory has been tremendously successful in chemistry and physics. Yet, it is unable to describe the energy degeneracy of spin-multiplet components with any approximate functional. This work features two contributions. (1) We present a multistate density functional theory (MSDFT) to represent spin-multiplet components and to determine multiplet energies. MSDFT is a hybrid approach, taking advantage of both wave function theory and density functional theory. Thus, the wave functions, electron densities and energy density-functionals for ground and excited states and for different components are treated on the same footing. The method is illustrated on valence excitations of atoms and molecules. (2) Importantly, a key result is that for cases in which the high-spin components can be determined separately by Kohn-Sham density functional theory, the transition density functional in MSDFT (which describes electronic coupling) can be defined rigorously. The numerical results may be explored to design and optimize transition density functionals for configuration coupling in multiconfigurational DFT.

Security Analysis of Selected AMI Failure Scenarios Using Agent Based Game Theoretic Simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abercrombie, Robert K; Schlicher, Bob G; Sheldon, Frederick T

Information security analysis can be performed using game theory implemented in dynamic Agent Based Game Theoretic (ABGT) simulations. Such simulations can be verified with the results from game theory analysis and further used to explore larger scale, real world scenarios involving multiple attackers, defenders, and information assets. We concentrated our analysis on the Advanced Metering Infrastructure (AMI) functional domain which the National Electric Sector Cyber security Organization Resource (NESCOR) working group has currently documented 29 failure scenarios. The strategy for the game was developed by analyzing five electric sector representative failure scenarios contained in the AMI functional domain. From thesemore » five selected scenarios, we characterize them into three specific threat categories affecting confidentiality, integrity and availability (CIA). The analysis using our ABGT simulation demonstrates how to model the AMI functional domain using a set of rationalized game theoretic rules decomposed from the failure scenarios in terms of how those scenarios might impact the AMI network with respect to CIA.« less

Orientation-dependent integral equation theory for a two-dimensional model of water

NASA Astrophysics Data System (ADS)

Urbič, T.; Vlachy, V.; Kalyuzhnyi, Yu. V.; Dill, K. A.

2003-03-01

We develop an integral equation theory that applies to strongly associating orientation-dependent liquids, such as water. In an earlier treatment, we developed a Wertheim integral equation theory (IET) that we tested against NPT Monte Carlo simulations of the two-dimensional Mercedes Benz model of water. The main approximation in the earlier calculation was an orientational averaging in the multidensity Ornstein-Zernike equation. Here we improve the theory by explicit introduction of an orientation dependence in the IET, based upon expanding the two-particle angular correlation function in orthogonal basis functions. We find that the new orientation-dependent IET (ODIET) yields a considerable improvement of the predicted structure of water, when compared to the Monte Carlo simulations. In particular, ODIET predicts more long-range order than the original IET, with hexagonal symmetry, as expected for the hydrogen bonded ice in this model. The new theoretical approximation still errs in some subtle properties; for example, it does not predict liquid water's density maximum with temperature or the negative thermal expansion coefficient.

Goal striving within agentic and communal roles: separate but functionally similar pathways to enhanced well-being.

PubMed

Sheldon, Kennon M; Cooper, M Lynne

2008-06-01

Do agency and communion strivings provide functionally similar but predictively independent pathways to enhanced well-being? We tested this idea via a year-long study of 493 diverse community adults. Our process model, based on self-determination and motive disposition theories, fit the data well. First, the need for achievement predicted initial autonomous motivation for agentic (work and school) role-goals and the need for intimacy predicted felt autonomy for communal (relationship and parenting) goals. For both agentic and communal goals, autonomous motivation predicted corresponding initial expectancies that predicted later goal attainment. Finally, each type of attainment predicted improved adjustment or role-satisfaction over the year. Besides being similar across agency and communion, the model was also similar across race and gender, except that the beneficial effects of communal goal attainment were stronger for high need for intimacy women and Blacks. Implications for agency/communion theories, motivation theories, and theories of well-being are discussed.

Approach to atmospheric laser-propagation theory based on the extended Huygens-Fresnel principle and a self-consistency concept.

PubMed

Bochove, Erik J; Rao Gudimetla, V S

2017-01-01

We propose a self-consistency condition based on the extended Huygens-Fresnel principle, which we apply to the propagation kernel of the mutual coherence function of a partially coherent laser beam propagating through a turbulent atmosphere. The assumption of statistical independence of turbulence in neighboring propagation segments leads to an integral equation in the propagation kernel. This integral equation is satisfied by a Gaussian function, with dependence on the transverse coordinates that is identical to the previous Gaussian formulation by Yura [Appl. Opt.11, 1399 (1972)APOPAI0003-693510.1364/AO.11.001399], but differs in the transverse coherence length's dependence on propagation distance, so that this established version violates our self-consistency principle. Our formulation has one free parameter, which in the context of Kolmogorov's theory is independent of turbulence strength and propagation distance. We determined its value by numerical fitting to the rigorous beam propagation theory of Yura and Hanson [J. Opt. Soc. Am. A6, 564 (1989)JOAOD60740-323210.1364/JOSAA.6.000564], demonstrating in addition a significant improvement over other Gaussian models.

Bohmian mechanics without wave function ontology

NASA Astrophysics Data System (ADS)

Solé, Albert

2013-11-01

In this paper, I critically assess different interpretations of Bohmian mechanics that are not committed to an ontology based on the wave function being an actual physical object that inhabits configuration space. More specifically, my aim is to explore the connection between the denial of configuration space realism and another interpretive debate that is specific to Bohmian mechanics: the quantum potential versus guidance approaches. Whereas defenders of the quantum potential approach to the theory claim that Bohmian mechanics is better formulated as quasi-Newtonian, via the postulation of forces proportional to acceleration; advocates of the guidance approach defend the notion that the theory is essentially first-order and incorporates some concepts akin to those of Aristotelian physics. Here I analyze whether the desideratum of an interpretation of Bohmian mechanics that is both explanatorily adequate and not committed to configuration space realism favors one of these two approaches to the theory over the other. Contrary to some recent claims in the literature, I argue that the quasi-Newtonian approach based on the idea of a quantum potential does not come out the winner.

Understanding and Remediating Social-Cognitive Dysfunctions in Patients with Serious Mental Illness Using Relational Frame Theory.

PubMed

Hendriks, Annemieke L; Barnes-Holmes, Yvonne; McEnteggart, Ciara; De Mey, Hubert R A; Janssen, Gwenny T L; Egger, Jos I M

2016-01-01

Impairments in social cognition and perspective-taking play an important role in the psychopathology and social functioning of individuals with social anxiety, autism, or schizophrenia-spectrum disorders, among other clinical presentations. Perspective-taking has mostly been studied using the concept of Theory of Mind (ToM), which describes the sequential development of these skills in young children, as well as clinical populations experiencing perspective-taking difficulties. Several studies mention positive results of ToM based training programs; however, the precise processes involved in the achievement of these improvements are difficult to determine. Relational Frame Theory (RFT) is a modern behavioral account of complex cognitive functions, and is argued to provide a more precise approach to the assessment and training of perspective-taking, among other relational skills. Results of RFT-based studies of perspective-taking in developmental and clinical settings are discussed. The development of training methods targeting perspective-taking deficits from an RFT point of view appears to provide promising applications for the enhancement of current treatments of people with social-cognitive dysfunctions.

From conflict management to reward-based decision making: actors and critics in primate medial frontal cortex.

PubMed

Silvetti, Massimo; Alexander, William; Verguts, Tom; Brown, Joshua W

2014-10-01

The role of the medial prefrontal cortex (mPFC) and especially the anterior cingulate cortex has been the subject of intense debate for the last decade. A number of theories have been proposed to account for its function. Broadly speaking, some emphasize cognitive control, whereas others emphasize value processing; specific theories concern reward processing, conflict detection, error monitoring, and volatility detection, among others. Here we survey and evaluate them relative to experimental results from neurophysiological, anatomical, and cognitive studies. We argue for a new conceptualization of mPFC, arising from recent computational modeling work. Based on reinforcement learning theory, these new models propose that mPFC is an Actor-Critic system. This system is aimed to predict future events including rewards, to evaluate errors in those predictions, and finally, to implement optimal skeletal-motor and visceromotor commands to obtain reward. This framework provides a comprehensive account of mPFC function, accounting for and predicting empirical results across different levels of analysis, including monkey neurophysiology, human ERP, human neuroimaging, and human behavior. Copyright © 2013 Elsevier Ltd. All rights reserved.

Associative and sensorimotor learning for parenting involves mirror neurons under the influence of oxytocin.

PubMed

Ho, S Shaun; Macdonald, Adam; Swain, James E

2014-04-01

Mirror neuron-based associative learning may be understood according to associative learning theories, in addition to sensorimotor learning theories. This is important for a comprehensive understanding of the role of mirror neurons and related hormone modulators, such as oxytocin, in complex social interactions such as among parent-infant dyads and in examples of mirror neuron function that involve abnormal motor systems such as depression.

A generalized functional response for predators that switch between multiple prey species.

PubMed

van Leeuwen, E; Brännström, Å; Jansen, V A A; Dieckmann, U; Rossberg, A G

2013-07-07

We develop a theory for the food intake of a predator that can switch between multiple prey species. The theory addresses empirical observations of prey switching and is based on the behavioural assumption that a predator tends to continue feeding on prey that are similar to the prey it has consumed last, in terms of, e.g., their morphology, defences, location, habitat choice, or behaviour. From a predator's dietary history and the assumed similarity relationship among prey species, we derive a general closed-form multi-species functional response for describing predators switching between multiple prey species. Our theory includes the Holling type II functional response as a special case and makes consistent predictions when populations of equivalent prey are aggregated or split. An analysis of the derived functional response enables us to highlight the following five main findings. (1) Prey switching leads to an approximate power-law relationship between ratios of prey abundance and prey intake, consistent with experimental data. (2) In agreement with empirical observations, the theory predicts an upper limit of 2 for the exponent of such power laws. (3) Our theory predicts deviations from power-law switching at very low and very high prey-abundance ratios. (4) The theory can predict the diet composition of a predator feeding on multiple prey species from diet observations for predators feeding only on pairs of prey species. (5) Predators foraging on more prey species will show less pronounced prey switching than predators foraging on fewer prey species, thus providing a natural explanation for the known difficulties of observing prey switching in the field. Copyright © 2013 Elsevier Ltd. All rights reserved.

Low cost estimation of the contribution of post-CCSD excitations to the total atomization energy using density functional theory calculations

NASA Astrophysics Data System (ADS)

Sánchez, H. R.; Pis Diez, R.

2016-04-01

Based on the Aλ diagnostic for multireference effects recently proposed [U.R. Fogueri, S. Kozuch, A. Karton, J.M. Martin, Theor. Chem. Acc. 132 (2013) 1], a simple method for improving total atomization energies and reaction energies calculated at the CCSD level of theory is proposed. The method requires a CCSD calculation and two additional density functional theory calculations for the molecule. Two sets containing 139 and 51 molecules are used as training and validation sets, respectively, for total atomization energies. An appreciable decrease in the mean absolute error from 7-10 kcal mol-1 for CCSD to about 2 kcal mol-1 for the present method is observed. The present method provides atomization energies and reaction energies that compare favorably with relatively recent scaled CCSD methods.

Dynamic response of porous functionally graded material nanobeams subjected to moving nanoparticle based on nonlocal strain gradient theory

NASA Astrophysics Data System (ADS)

Barati, Mohammad Reza

2017-11-01

Up to now, nonlocal strain gradient theory (NSGT) is broadly applied to examine free vibration, static bending and buckling of nanobeams. This theory captures nonlocal stress field effects together with the microstructure-dependent strain gradient effects. In this study, forced vibrations of NSGT nanobeams on elastic substrate subjected to moving loads are examined. The nanobeam is made of functionally graded material (FGM) with even and uneven porosity distributions inside the material structure. The graded material properties with porosities are described by a modified power-law model. Dynamic deflection of the nanobeam is obtained via Galerkin and inverse Laplace transform methods. The importance of nonlocal parameter, strain gradient parameter, moving load velocity, porosity volume fraction, type of porosity distribution and elastic foundation on forced vibration behavior of nanobeams are discussed.

Topological and Orthomodular Modeling of Context in Behavioral Science

NASA Astrophysics Data System (ADS)

Narens, Louis

2017-02-01

Two non-boolean methods are discussed for modeling context in behavioral data and theory. The first is based on intuitionistic logic, which is similar to classical logic except that not every event has a complement. Its probability theory is also similar to classical probability theory except that the definition of probability function needs to be generalized to unions of events instead of applying only to unions of disjoint events. The generalization is needed, because intuitionistic event spaces may not contain enough disjoint events for the classical definition to be effective. The second method develops a version of quantum logic for its underlying probability theory. It differs from Hilbert space logic used in quantum mechanics as a foundation for quantum probability theory in variety of ways. John von Neumann and others have commented about the lack of a relative frequency approach and a rational foundation for this probability theory. This article argues that its version of quantum probability theory does not have such issues. The method based on intuitionistic logic is useful for modeling cognitive interpretations that vary with context, for example, the mood of the decision maker, the context produced by the influence of other items in a choice experiment, etc. The method based on this article's quantum logic is useful for modeling probabilities across contexts, for example, how probabilities of events from different experiments are related.

Development and Validation of an Instrument for Evaluating Inquiry-Based Tasks in Science Textbooks

ERIC Educational Resources Information Center

Yang, Wenyuan; Liu, Enshan

2016-01-01

This article describes the development and validation of an instrument that can be used for content analysis of inquiry-based tasks. According to the theories of educational evaluation and qualities of inquiry, four essential functions that inquiry-based tasks should serve are defined: (1) assisting in the construction of understandings about…

Carbonic anhydrase inhibition of Schiff base derivative of imino-methyl-naphthalen-2-ol: Synthesis, structure elucidation, molecular docking, dynamic simulation and density functional theory calculations

NASA Astrophysics Data System (ADS)

Abbas, Saghir; Nasir, Hafiza Huma; Zaib, Sumera; Ali, Saqib; Mahmood, Tariq; Ayub, Khurshid; Tahir, Muhammad Nawaz; Iqbal, Jamshed

2018-03-01

In the present study, we have designed and synthesized a Schiff base derivative 3 and characterized by FT-IR, 1H and 13C NMR spectroscopy. Single crystal X-ray diffraction and NMR studies were also performed. The synthetic compound was screened for its inhibitory potential against carbonic anhydrase II. The experimental results were validated by molecular docking and dynamic simulations of compound 3 in the active pocket of enzyme. Important binding interactions with the key residues in the active site of the carbonic anhydrase enzyme were revealed. Moreover, supramolecular assembly of the title compound was analyzed by density functional theory (DFT) calculations. These studies rendered a more clear understanding for the demonstration of novel molecular mechanism involved in CA II inhibition by the synthesized compound.

Total-energy Assisted Tight-binding Method Based on Local Density Approximation of Density Functional Theory

NASA Astrophysics Data System (ADS)

Fujiwara, Takeo; Nishino, Shinya; Yamamoto, Susumu; Suzuki, Takashi; Ikeda, Minoru; Ohtani, Yasuaki

2018-06-01

A novel tight-binding method is developed, based on the extended Hückel approximation and charge self-consistency, with referring the band structure and the total energy of the local density approximation of the density functional theory. The parameters are so adjusted by computer that the result reproduces the band structure and the total energy, and the algorithm for determining parameters is established. The set of determined parameters is applicable to a variety of crystalline compounds and change of lattice constants, and, in other words, it is transferable. Examples are demonstrated for Si crystals of several crystalline structures varying lattice constants. Since the set of parameters is transferable, the present tight-binding method may be applicable also to molecular dynamics simulations of large-scale systems and long-time dynamical processes.

A third-generation density-functional-theory-based method for calculating canonical molecular orbitals of large molecules.

PubMed

Hirano, Toshiyuki; Sato, Fumitoshi

2014-07-28

We used grid-free modified Cholesky decomposition (CD) to develop a density-functional-theory (DFT)-based method for calculating the canonical molecular orbitals (CMOs) of large molecules. Our method can be used to calculate standard CMOs, analytically compute exchange-correlation terms, and maximise the capacity of next-generation supercomputers. Cholesky vectors were first analytically downscaled using low-rank pivoted CD and CD with adaptive metric (CDAM). The obtained Cholesky vectors were distributed and stored on each computer node in a parallel computer, and the Coulomb, Fock exchange, and pure exchange-correlation terms were calculated by multiplying the Cholesky vectors without evaluating molecular integrals in self-consistent field iterations. Our method enables DFT and massively distributed memory parallel computers to be used in order to very efficiently calculate the CMOs of large molecules.

Market Mechanism Design for Renewable Energy based on Risk Theory

NASA Astrophysics Data System (ADS)

Yang, Wu; Bo, Wang; Jichun, Liu; Wenjiao, Zai; Pingliang, Zeng; Haobo, Shi

2018-02-01

Generation trading between renewable energy and thermal power is an efficient market means for transforming supply structure of electric power into sustainable development pattern. But the trading is hampered by the output fluctuations of renewable energy and the cost differences between renewable energy and thermal power at present. In this paper, the external environmental cost (EEC) is defined and the EEC is introduced into the generation cost. At same time, the incentive functions of renewable energy and low-emission thermal power are designed, which are decreasing functions of EEC. On these bases, for the market risks caused by the random variability of EEC, the decision-making model of generation trading between renewable energy and thermal power is constructed according to the risk theory. The feasibility and effectiveness of the proposed model are verified by simulation results.

Postural Control in Children: Implications for Pediatric Practice

ERIC Educational Resources Information Center

Westcott, Sarah L.; Burtner, Patricia

2004-01-01

Based on a systems theory of motor control, reactive postural control (RPA) and anticipatory postural control (APA) in children are reviewed from several perspectives in order to develop an evidence-based intervention strategy for improving postural control in children with limitations in motor function. Research on development of postural…

Mediating Language Learning: Teacher Interactions with ESL Students in a Content-Based Classroom.

ERIC Educational Resources Information Center

Gibbons, Pauline

2003-01-01

Draws on constructs of "mediation" from sociocultural theory and "mode continuum" from systemic functional linguistics to investigate how student-teacher talk in a content-based classroom contributes to learners' language development. Shows how teachers mediate between students' linguistic levels in English and their…

Numerical methods for the inverse problem of density functional theory

DOE PAGES

Jensen, Daniel S.; Wasserman, Adam

2017-07-17

Here, the inverse problem of Kohn–Sham density functional theory (DFT) is often solved in an effort to benchmark and design approximate exchange-correlation potentials. The forward and inverse problems of DFT rely on the same equations but the numerical methods for solving each problem are substantially different. We examine both problems in this tutorial with a special emphasis on the algorithms and error analysis needed for solving the inverse problem. Two inversion methods based on partial differential equation constrained optimization and constrained variational ideas are introduced. We compare and contrast several different inversion methods applied to one-dimensional finite and periodic modelmore » systems.« less

Gauge fields at finite temperatures—"Thermo field dynamics" and the KMS condition and their extension to gauge theories

NASA Astrophysics Data System (ADS)

Ojima, Izumi

1981-11-01

"Thermo field dynamics," allowing the Feynman diagram method to be applied to real-time causal Green's functions at finite temperatures ( not temperature Green's functions with imaginary times) expressed in the form of "vacuum" expectation values, is reconsidered in light of its connection with the algebraic formulation of statical machanics based upon the KMS condition. On the basis of so-obtained general basic formulae, the formalism is extended to the case of gauge theories, where the subsidiary condition specifying physical states, the notion of observables, and the structure of the physical subspace at finite temperatures are clarified.

Application of Van Der Waals Density Functional Theory to Study Physical Properties of Energetic Materials

NASA Astrophysics Data System (ADS)

Conroy, M. W.; Budzevich, M. M.; Lin, Y.; Oleynik, I. I.; White, C. T.

2009-12-01

An empirical correction to account for van der Waals interactions based on the work of Neumann and Perrin [J. Phys. Chem. B 109, 15531 (2005)] was applied to density functional theory calculations of energetic molecular crystals. The calculated equilibrium unit-cell volumes of FOX-7, β-HMX, solid nitromethane, PETN-I, α-RDX, and TATB show a significant improvement in the agreement with experimental results. Hydrostatic-compression simulations of β-HMX, PETN-I, and α-RDX were also performed. The isothermal equations of state calculated from the results show increased agreement with experiment in the pressure intervals studied.

Generating functionals and Gaussian approximations for interruptible delay reactions

NASA Astrophysics Data System (ADS)

Brett, Tobias; Galla, Tobias

2015-10-01

We develop a generating functional description of the dynamics of non-Markovian individual-based systems in which delay reactions can be terminated before completion. This generalizes previous work in which a path-integral approach was applied to dynamics in which delay reactions complete with certainty. We construct a more widely applicable theory, and from it we derive Gaussian approximations of the dynamics, valid in the limit of large, but finite, population sizes. As an application of our theory we study predator-prey models with delay dynamics due to gestation or lag periods to reach the reproductive age. In particular, we focus on the effects of delay on noise-induced cycles.

Monte Carlo Simulations of Electron Energy-Loss Spectra with the Addition of Fine Structure from Density Functional Theory Calculations.

PubMed

Attarian Shandiz, Mohammad; Guinel, Maxime J-F; Ahmadi, Majid; Gauvin, Raynald

2016-02-01

A new approach is presented to introduce the fine structure of core-loss excitations into the electron energy-loss spectra of ionization edges by Monte Carlo simulations based on an optical oscillator model. The optical oscillator strength is refined using the calculated electron energy-loss near-edge structure by density functional theory calculations. This approach can predict the effects of multiple scattering and thickness on the fine structure of ionization edges. In addition, effects of the fitting range for background removal and the integration range under the ionization edge on signal-to-noise ratio are investigated.

Construct Validation Theory Applied to the Study of Personality Dysfunction

PubMed Central

Zapolski, Tamika C. B.; Guller, Leila; Smith, Gregory T.

2013-01-01

The authors review theory validation and construct validation principles as related to the study of personality dysfunction. Historically, personality disorders have been understood to be syndromes of heterogeneous symptoms. The authors argue that the syndrome approach to description results in diagnoses of unclear meaning and constrained validity. The alternative approach of describing personality dysfunction in terms of homogeneous dimensions of functioning avoids the problems of the syndromal approach and has been shown to provide more valid description and diagnosis. The authors further argue that description based on homogeneous dimensions of personality function/dysfunction is more useful, because it provides direct connections to validated treatments. PMID:22321263

Native and hydrogen-containing point defects in Mg3N2 : A density functional theory study

NASA Astrophysics Data System (ADS)

Lange, Björn; Freysoldt, Christoph; Neugebauer, Jörg

2010-06-01

The formation energy and solubility of hydrogen in magnesium nitride bulk (antibixbyite Mg3N2 ) have been studied employing density functional theory in the generalized gradient approximation. The effect of doping and the presence of native defects and complex formation have been taken into account. Our results show that magnesium nitride is a nearly defect-free insulator with insignificant hydrogen-storage capacity. Based on this insight we derive a model that highlights the role of the formation and presence of the parasitic Mg3N2 inclusions in the activation of p -doped GaN in optoelectronic devices.

Numerical methods for the inverse problem of density functional theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jensen, Daniel S.; Wasserman, Adam

Here, the inverse problem of Kohn–Sham density functional theory (DFT) is often solved in an effort to benchmark and design approximate exchange-correlation potentials. The forward and inverse problems of DFT rely on the same equations but the numerical methods for solving each problem are substantially different. We examine both problems in this tutorial with a special emphasis on the algorithms and error analysis needed for solving the inverse problem. Two inversion methods based on partial differential equation constrained optimization and constrained variational ideas are introduced. We compare and contrast several different inversion methods applied to one-dimensional finite and periodic modelmore » systems.« less

A Lie based 4-dimensional higher Chern-Simons theory

NASA Astrophysics Data System (ADS)

Zucchini, Roberto

2016-05-01

We present and study a model of 4-dimensional higher Chern-Simons theory, special Chern-Simons (SCS) theory, instances of which have appeared in the string literature, whose symmetry is encoded in a skeletal semistrict Lie 2-algebra constructed from a compact Lie group with non discrete center. The field content of SCS theory consists of a Lie valued 2-connection coupled to a background closed 3-form. SCS theory enjoys a large gauge and gauge for gauge symmetry organized in an infinite dimensional strict Lie 2-group. The partition function of SCS theory is simply related to that of a topological gauge theory localizing on flat connections with degree 3 second characteristic class determined by the background 3-form. Finally, SCS theory is related to a 3-dimensional special gauge theory whose 2-connection space has a natural symplectic structure with respect to which the 1-gauge transformation action is Hamiltonian, the 2-curvature map acting as moment map.

Education Based on Theory of Planned Behavior over Sexual Function of Women with Breast Cancer in Iran.

PubMed

Jalambadani, Zeinab; Garmaroudi, Gholamreza; Tavousi, Mahmood

2018-01-01

Sexual function in patients with breast cancer, especially in younger patients, is an important issue from clinical and psychosocial perspectives. Theory of planned behavior (TPB) is one of the important theories that explain the main process of adopting healthy behaviors. This study investigated the effect of education based on TPB on sexual function of women with breast cancer in Mashhad, Iran. In this quasi-experimental study, 120 women (60 women in education group, 60 women in control group) visiting Razavi Hospital of Mashhad city were studied, selected by using the random method in 2016. The data collection tool was a questionnaire which was completed during the interview. The validity and reliability of this questionnaire were determined through the face and content validity and through Cronbach's alpha and test-retest, respectively. Data were analyzed using statistical SPSS 22 software. Using linear regression analysis, it was determined that attitudes, subjective norm, and perceived behavioral control (PBC) predict 0.85 overall of the total variance of sexual function intention, which among these variables, the effect of the subjective norm was more than the other ones ( P < 0.05). After educational intervention, the average rates of knowledge, attitude, PBC, and intention of sexual function in sex education group were significantly increased ( P < 0.05); these changes were not meaningful in the control group. There was no statistically significant difference in subjective norm between the two groups after intervention. The results of this research suggest that TPB can be used in sex education interventions and have relevant results.

Grassmann phase space methods for fermions. II. Field theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dalton, B.J., E-mail: bdalton@swin.edu.au; Jeffers, J.; Barnett, S.M.

In both quantum optics and cold atom physics, the behaviour of bosonic photons and atoms is often treated using phase space methods, where mode annihilation and creation operators are represented by c-number phase space variables, with the density operator equivalent to a distribution function of these variables. The anti-commutation rules for fermion annihilation, creation operators suggests the possibility of using anti-commuting Grassmann variables to represent these operators. However, in spite of the seminal work by Cahill and Glauber and a few applications, the use of Grassmann phase space methods in quantum-atom optics to treat fermionic systems is rather rare, thoughmore » fermion coherent states using Grassmann variables are widely used in particle physics. This paper presents a phase space theory for fermion systems based on distribution functionals, which replace the density operator and involve Grassmann fields representing anti-commuting fermion field annihilation, creation operators. It is an extension of a previous phase space theory paper for fermions (Paper I) based on separate modes, in which the density operator is replaced by a distribution function depending on Grassmann phase space variables which represent the mode annihilation and creation operators. This further development of the theory is important for the situation when large numbers of fermions are involved, resulting in too many modes to treat separately. Here Grassmann fields, distribution functionals, functional Fokker–Planck equations and Ito stochastic field equations are involved. Typical applications to a trapped Fermi gas of interacting spin 1/2 fermionic atoms and to multi-component Fermi gases with non-zero range interactions are presented, showing that the Ito stochastic field equations are local in these cases. For the spin 1/2 case we also show how simple solutions can be obtained both for the untrapped case and for an optical lattice trapping potential.« less

Potential Functions and the Characterization of Economics-Based Information

NASA Astrophysics Data System (ADS)

Haven, Emmanuel

2015-10-01

The formulation of quantum mechanics as a diffusion process by Nelson (Phys Rev 150:1079-1085, 1966) provides for an interesting approach on how we may transit from classical mechanics into quantum mechanics. Besides the presence of the real potential function, another type of potential function (often denoted as `quantum potential') forms an intrinsic part of this theory. In this paper we attempt to show how both types of potential functions can have a use in a resolutely macroscopic context like financial asset pricing. We are particularly interested in uncovering how the `quantum potential' can add to the economics-based relevant information which is already supplied by the real potential function.

Mobile applications for weight management: theory-based content analysis.

PubMed

Azar, Kristen M J; Lesser, Lenard I; Laing, Brian Y; Stephens, Janna; Aurora, Magi S; Burke, Lora E; Palaniappan, Latha P

2013-11-01

The use of smartphone applications (apps) to assist with weight management is increasingly prevalent, but the quality of these apps is not well characterized. The goal of the study was to evaluate diet/nutrition and anthropometric tracking apps based on incorporation of features consistent with theories of behavior change. A comparative, descriptive assessment was conducted of the top-rated free apps in the Health and Fitness category available in the iTunes App Store. Health and Fitness apps (N=200) were evaluated using predetermined inclusion/exclusion criteria and categorized based on commonality in functionality, features, and developer description. Four researchers then evaluated the two most popular apps in each category using two instruments: one based on traditional behavioral theory (score range: 0-100) and the other on the Fogg Behavioral Model (score range: 0-6). Data collection and analysis occurred in November 2012. Eligible apps (n=23) were divided into five categories: (1) diet tracking; (2) healthy cooking; (3) weight/anthropometric tracking; (4) grocery decision making; and (5) restaurant decision making. The mean behavioral theory score was 8.1 (SD=4.2); the mean persuasive technology score was 1.9 (SD=1.7). The top-rated app on both scales was Lose It! by Fitnow Inc. All apps received low overall scores for inclusion of behavioral theory-based strategies. © 2013 American Journal of Preventive Medicine.

Thermalization of Wightman functions in AdS/CFT and quasinormal modes

NASA Astrophysics Data System (ADS)

Keränen, Ville; Kleinert, Philipp

2016-07-01

We study the time evolution of Wightman two-point functions of scalar fields in AdS3 -Vaidya, a spacetime undergoing gravitational collapse. In the boundary field theory, the collapse corresponds to a quench process where the dual 1 +1 -dimensional CFT is taken out of equilibrium and subsequently thermalizes. From the two-point function, we extract an effective occupation number in the boundary theory and study how it approaches the thermal Bose-Einstein distribution. We find that the Wightman functions, as well as the effective occupation numbers, thermalize with a rate set by the lowest quasinormal mode of the scalar field in the BTZ black hole background. We give a heuristic argument for the quasinormal decay, which is expected to apply to more general Vaidya spacetimes also in higher dimensions. This suggests a unified picture in which thermalization times of one- and two-point functions are determined by the lowest quasinormal mode. Finally, we study how these results compare to previous calculations of two-point functions based on the geodesic approximation.

Computational design of surfaces, nanostructures and optoelectronic materials

NASA Astrophysics Data System (ADS)

Choudhary, Kamal

Properties of engineering materials are generally influenced by defects such as point defects (vacancies, interstitials, substitutional defects), line defects (dislocations), planar defects (grain boundaries, free surfaces/nanostructures, interfaces, stacking faults) and volume defects (voids). Classical physics based molecular dynamics and quantum physics based density functional theory can be useful in designing materials with controlled defect properties. In this thesis, empirical potential based molecular dynamics was used to study the surface modification of polymers due to energetic polyatomic ion, thermodynamics and mechanics of metal-ceramic interfaces and nanostructures, while density functional theory was used to screen substituents in optoelectronic materials. Firstly, polyatomic ion-beams were deposited on polymer surfaces and the resulting chemical modifications of the surface were examined. In particular, S, SC and SH were deposited on amorphous polystyrene (PS), and C2H, CH3, and C3H5 were deposited on amorphous poly (methyl methacrylate) (PMMA) using molecular dynamics simulations with classical reactive empirical many-body (REBO) potentials. The objective of this work was to elucidate the mechanisms by which the polymer surface modification took place. The results of the work could be used in tailoring the incident energy and/or constituents of ion beam for obtaining a particular chemistry inside the polymer surface. Secondly, a new Al-O-N empirical potential was developed within the charge optimized many body (COMB) formalism. This potential was then used to examine the thermodynamic stability of interfaces and mechanical properties of nanostructures composed of aluminum, its oxide and its nitride. The potentials were tested for these materials based on surface energies, defect energies, bulk phase stability, the mechanical properties of the most stable bulk phase, its phonon properties as well as with a genetic algorithm based evolution theory of the materials to ensure that no spurious phases had a lower cohesive energy. Thirdly, lanthanide doped and co-doped Y3Al5O 12 were examined using density functional theory (DFT) with semi-local and local functional. Theoretical results were compared and validated with experimental data and new co-doped materials with high efficiency were predicted. Finally, Transition element doped CH3NH3PbI3 were studied with DFT for validation of the model with experimental data and replacement materials for toxic Pb were predicted.

Pseudosatellite technologies based on the use of functionally stable complexes of remote-piloted aircrafts

NASA Astrophysics Data System (ADS)

Mashkov, O. A.; Samborskiy, I. I.

2009-10-01

A bundle of papers dealing with functionally stable systems requires the necessity of analyzing of obtained results and their understanding in a general context of cybernetic's development and applications. Description of this field of science, main results and perspectives of the new theory of functionally stability of dynamical systems concerning the problem of remote-piloted aircrafts engineering using pseudosatellite technologies are proposed in the paper.

Framework for scalable adsorbate–adsorbate interaction models

DOE PAGES

Hoffmann, Max J.; Medford, Andrew J.; Bligaard, Thomas

2016-06-02

Here, we present a framework for physically motivated models of adsorbate–adsorbate interaction between small molecules on transition and coinage metals based on modifications to the substrate electronic structure due to adsorption. We use this framework to develop one model for transition and one for coinage metal surfaces. The models for transition metals are based on the d-band center position, and the models for coinage metals are based on partial charges. The models require no empirical parameters, only two first-principles calculations per adsorbate as input, and therefore scale linearly with the number of reaction intermediates. By theory to theory comparison withmore » explicit density functional theory calculations over a wide range of adsorbates and surfaces, we show that the root-mean-squared error for differential adsorption energies is less than 0.2 eV for up to 1 ML coverage.« less

TOPICS IN THEORY OF GENERALIZED PARTON DISTRIBUTIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Radyushkin, Anatoly V.

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, wemore » 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.« less

A general framework for numerical simulation of improvised explosive device (IED)-detection scenarios using density functional theory (DFT) and terahertz (THz) spectra.

PubMed

Shabaev, Andrew; Lambrakos, Samuel G; Bernstein, Noam; Jacobs, Verne L; Finkenstadt, Daniel

2011-04-01

We have developed a general framework for numerical simulation of various types of scenarios that can occur for the detection of improvised explosive devices (IEDs) through the use of excitation using incident electromagnetic waves. A central component model of this framework is an S-matrix representation of a multilayered composite material system. Each layer of the system is characterized by an average thickness and an effective electric permittivity function. The outputs of this component are the reflectivity and the transmissivity as functions of frequency and angle of the incident electromagnetic wave. The input of the component is a parameterized analytic-function representation of the electric permittivity as a function of frequency, which is provided by another component model of the framework. The permittivity function is constructed by fitting response spectra calculated using density functional theory (DFT) and parameter adjustment according to any additional information that may be available, e.g., experimentally measured spectra or theory-based assumptions concerning spectral features. A prototype simulation is described that considers response characteristics for THz excitation of the high explosive β-HMX. This prototype simulation includes a description of a procedure for calculating response spectra using DFT as input to the Smatrix model. For this purpose, the DFT software NRLMOL was adopted. © 2011 Society for Applied Spectroscopy

Derivation of the RPA (Random Phase Approximation) Equation of ATDDFT (Adiabatic Time Dependent Density Functional Ground State Response Theory) from an Excited State Variational Approach Based on the Ground State Functional.

PubMed

Ziegler, Tom; Krykunov, Mykhaylo; Autschbach, Jochen

2014-09-09

The random phase approximation (RPA) equation of adiabatic time dependent density functional ground state response theory (ATDDFT) has been used extensively in studies of excited states. It extracts information about excited states from frequency dependent ground state response properties and avoids, thus, in an elegant way, direct Kohn-Sham calculations on excited states in accordance with the status of DFT as a ground state theory. Thus, excitation energies can be found as resonance poles of frequency dependent ground state polarizability from the eigenvalues of the RPA equation. ATDDFT is approximate in that it makes use of a frequency independent energy kernel derived from the ground state functional. It is shown in this study that one can derive the RPA equation of ATDDFT from a purely variational approach in which stationary states above the ground state are located using our constricted variational DFT (CV-DFT) method and the ground state functional. Thus, locating stationary states above the ground state due to one-electron excitations with a ground state functional is completely equivalent to solving the RPA equation of TDDFT employing the same functional. The present study is an extension of a previous work in which we demonstrated the equivalence between ATDDFT and CV-DFT within the Tamm-Dancoff approximation.

Time-dependent mean-field theory for x-ray near-edge spectroscopy

NASA Astrophysics Data System (ADS)

Bertsch, G. F.; Lee, A. J.

2014-02-01

We derive equations of motion for calculating the near-edge x-ray absorption spectrum in molecules and condensed matter, based on a two-determinant approximation and Dirac's variational principle. The theory provides an exact solution for the linear response when the Hamiltonian or energy functional has only diagonal interactions in some basis. We numerically solve the equations to compare with the Mahan-Nozières-De Dominicis theory of the edge singularity in metallic conductors. Our extracted power-law exponents are similar to those of the analytic theory, but are not in quantitative agreement. The calculational method can be readily generalized to treat Kohn-Sham Hamiltonians with electron-electron interactions derived from correlation-exchange potentials.

Relationship between theory of mind and functional independence is mediated by executive function.

PubMed

Ahmed, Fayeza S; Miller, L Stephen

2013-06-01

Theory of mind (ToM) is the ability to comprehend another person's perspective. Although there is much literature of ToM in children, there is a limited and somewhat inconclusive amount of studies examining ToM in a geriatric population. This study examined ToM's relationship to functional independence. Two tests of ToM, tests of executive function, and a measure of functional ability were administered to cognitively intact older adults. Results showed that 1 test of ToM (Strange Stories test) significantly accounted for variance in functional ability, whereas the other did not (Faux Pas test). In addition, Strange Stories test performance was partially driven by a verbal abstraction-based executive function: proverb interpretation. A multiple mediation model was employed to examine whether executive functions explained the relationship between the Strange Stories test and functional ability. Results showed that both the combined and individual indirect effects of the executive function measures mediated the relationship. We argue that, although components of ToM are associated with functional independence, ToM does not appear to account for additional variance in functional independence beyond executive function measures. PsycINFO Database Record (c) 2013 APA, all rights reserved.

Pattern activation/recognition theory of mind

PubMed Central

du Castel, Bertrand

2015-01-01

In his 2012 book How to Create a Mind, Ray Kurzweil defines a “Pattern Recognition Theory of Mind” that states that the brain uses millions of pattern recognizers, plus modules to check, organize, and augment them. In this article, I further the theory to go beyond pattern recognition and include also pattern activation, thus encompassing both sensory and motor functions. In addition, I treat checking, organizing, and augmentation as patterns of patterns instead of separate modules, therefore handling them the same as patterns in general. Henceforth I put forward a unified theory I call “Pattern Activation/Recognition Theory of Mind.” While the original theory was based on hierarchical hidden Markov models, this evolution is based on their precursor: stochastic grammars. I demonstrate that a class of self-describing stochastic grammars allows for unifying pattern activation, recognition, organization, consistency checking, metaphor, and learning, into a single theory that expresses patterns throughout. I have implemented the model as a probabilistic programming language specialized in activation/recognition grammatical and neural operations. I use this prototype to compute and present diagrams for each stochastic grammar and corresponding neural circuit. I then discuss the theory as it relates to artificial network developments, common coding, neural reuse, and unity of mind, concluding by proposing potential paths to validation. PMID:26236228

Extensions and evaluations of a general quantitative theory of forest structure and dynamics

PubMed Central

Enquist, Brian J.; West, Geoffrey B.; Brown, James H.

2009-01-01

Here, we present the second part of a quantitative theory for the structure and dynamics of forests under demographic and resource steady state. The theory is based on individual-level allometric scaling relations for how trees use resources, fill space, and grow. These scale up to determine emergent properties of diverse forests, including size–frequency distributions, spacing relations, canopy configurations, mortality rates, population dynamics, successional dynamics, and resource flux rates. The theory uniquely makes quantitative predictions for both stand-level scaling exponents and normalizations. We evaluate these predictions by compiling and analyzing macroecological datasets from several tropical forests. The close match between theoretical predictions and data suggests that forests are organized by a set of very general scaling rules. Our mechanistic theory is based on allometric scaling relations, is complementary to “demographic theory,” but is fundamentally different in approach. It provides a quantitative baseline for understanding deviations from predictions due to other factors, including disturbance, variation in branching architecture, asymmetric competition, resource limitation, and other sources of mortality, which are not included in the deliberately simplified theory. The theory should apply to a wide range of forests despite large differences in abiotic environment, species diversity, and taxonomic and functional composition. PMID:19363161

Pattern activation/recognition theory of mind.

PubMed

du Castel, Bertrand

2015-01-01

In his 2012 book How to Create a Mind, Ray Kurzweil defines a "Pattern Recognition Theory of Mind" that states that the brain uses millions of pattern recognizers, plus modules to check, organize, and augment them. In this article, I further the theory to go beyond pattern recognition and include also pattern activation, thus encompassing both sensory and motor functions. In addition, I treat checking, organizing, and augmentation as patterns of patterns instead of separate modules, therefore handling them the same as patterns in general. Henceforth I put forward a unified theory I call "Pattern Activation/Recognition Theory of Mind." While the original theory was based on hierarchical hidden Markov models, this evolution is based on their precursor: stochastic grammars. I demonstrate that a class of self-describing stochastic grammars allows for unifying pattern activation, recognition, organization, consistency checking, metaphor, and learning, into a single theory that expresses patterns throughout. I have implemented the model as a probabilistic programming language specialized in activation/recognition grammatical and neural operations. I use this prototype to compute and present diagrams for each stochastic grammar and corresponding neural circuit. I then discuss the theory as it relates to artificial network developments, common coding, neural reuse, and unity of mind, concluding by proposing potential paths to validation.

Second-order perturbation theory with a density matrix renormalization group self-consistent field reference function: theory and application to the study of chromium dimer.

PubMed

Kurashige, Yuki; Yanai, Takeshi

2011-09-07

We present a second-order perturbation theory based on a density matrix renormalization group self-consistent field (DMRG-SCF) reference function. The method reproduces the solution of the complete active space with second-order perturbation theory (CASPT2) when the DMRG reference function is represented by a sufficiently large number of renormalized many-body basis, thereby being named DMRG-CASPT2 method. The DMRG-SCF is able to describe non-dynamical correlation with large active space that is insurmountable to the conventional CASSCF method, while the second-order perturbation theory provides an efficient description of dynamical correlation effects. The capability of our implementation is demonstrated for an application to the potential energy curve of the chromium dimer, which is one of the most demanding multireference systems that require best electronic structure treatment for non-dynamical and dynamical correlation as well as large basis sets. The DMRG-CASPT2/cc-pwCV5Z calculations were performed with a large (3d double-shell) active space consisting of 28 orbitals. Our approach using large-size DMRG reference addressed the problems of why the dissociation energy is largely overestimated by CASPT2 with the small active space consisting of 12 orbitals (3d4s), and also is oversensitive to the choice of the zeroth-order Hamiltonian. © 2011 American Institute of Physics

Accurate and computationally efficient prediction of thermochemical properties of biomolecules using the generalized connectivity-based hierarchy.

PubMed

Sengupta, Arkajyoti; Ramabhadran, Raghunath O; Raghavachari, Krishnan

2014-08-14

In this study we have used the connectivity-based hierarchy (CBH) method to derive accurate heats of formation of a range of biomolecules, 18 amino acids and 10 barbituric acid/uracil derivatives. The hierarchy is based on the connectivity of the different atoms in a large molecule. It results in error-cancellation reaction schemes that are automated, general, and can be readily used for a broad range of organic molecules and biomolecules. Herein, we first locate stable conformational and tautomeric forms of these biomolecules using an accurate level of theory (viz. CCSD(T)/6-311++G(3df,2p)). Subsequently, the heats of formation of the amino acids are evaluated using the CBH-1 and CBH-2 schemes and routinely employed density functionals or wave function-based methods. The calculated heats of formation obtained herein using modest levels of theory and are in very good agreement with those obtained using more expensive W1-F12 and W2-F12 methods on amino acids and G3 results on barbituric acid derivatives. Overall, the present study (a) highlights the small effect of including multiple conformers in determining the heats of formation of biomolecules and (b) in concurrence with previous CBH studies, proves that use of the more effective error-cancelling isoatomic scheme (CBH-2) results in more accurate heats of formation with modestly sized basis sets along with common density functionals or wave function-based methods.

Parent Ratings of ADHD Symptoms: Generalized Partial Credit Model Analysis of Differential Item Functioning across Gender

ERIC Educational Resources Information Center

Gomez, Rapson

2012-01-01

Objective: Generalized partial credit model, which is based on item response theory (IRT), was used to test differential item functioning (DIF) for the "Diagnostic and Statistical Manual of Mental Disorders" (4th ed.), inattention (IA), and hyperactivity/impulsivity (HI) symptoms across boys and girls. Method: To accomplish this, parents completed…

Incorporating "Motivation" into the Functional Analysis of Challenging Behavior: On the Interactive and Integrative Potential of the Motivating Operation

ERIC Educational Resources Information Center

Langthorne, Paul; McGill, Peter; O'Reilly, Mark

2007-01-01

Sensitivity theory attempts to account for the variability often observed in challenging behavior by recourse to the "aberrant motivation" of people with intellectual and developmental disabilities. In this article, we suggest that a functional analysis based on environmental (challenging environments) and biological (challenging needs) motivating…

Treatment of a Disorder of Self through Functional Analytic Psychotherapy

ERIC Educational Resources Information Center

Ferro-Garcia, Rafael; Lopez-Bermudez, Miguel Angel; Valero-Aguayo, Luis

2012-01-01

This paper presents a clinical case study of a depressed female, treated by means of Functional Analytic Psychotherapy (FAP) based on the theory and techniques for treating an "unstable self" (Kohlenberg & Tsai, 1991), instead of the classic treatment for depression. The client was a 20-year-old college student. The trigger for her problems was a…

Network analysis reveals disrupted functional brain circuitry in drug-naive social anxiety disorder.

PubMed

Yang, Xun; Liu, Jin; Meng, Yajing; Xia, Mingrui; Cui, Zaixu; Wu, Xi; Hu, Xinyu; Zhang, Wei; Gong, Gaolang; Gong, Qiyong; Sweeney, John A; He, Yong

2017-12-07

Social anxiety disorder (SAD) is a common and disabling condition characterized by excessive fear and avoidance of public scrutiny. Psychoradiology studies have suggested that the emotional and behavior deficits in SAD are associated with abnormalities in regional brain function and functional connectivity. However, little is known about whether intrinsic functional brain networks in patients with SAD are topologically disrupted. Here, we collected resting-state fMRI data from 33 drug-naive patients with SAD and 32 healthy controls (HC), constructed functional networks with 34 predefined regions based on previous meta-analytic research with task-based fMRI in SAD, and performed network-based statistic and graph-theory analyses. The network-based statistic analysis revealed a single connected abnormal circuitry including the frontolimbic circuit (termed the "fear circuit", including the dorsolateral prefrontal cortex, ventral medial prefrontal cortex and insula) and posterior cingulate/occipital areas supporting perceptual processing. In this single altered network, patients with SAD had higher functional connectivity than HC. At the global level, graph-theory analysis revealed that the patients exhibited a lower normalized characteristic path length than HC, which suggests a disorder-related shift of network topology toward randomized configurations. SAD-related deficits in nodal degree, efficiency and participation coefficient were detected in the parahippocampal gyrus, posterior cingulate cortex, dorsolateral prefrontal cortex, insula and the calcarine sulcus. Aspects of abnormal connectivity were associated with anxiety symptoms. These findings highlight the aberrant topological organization of functional brain network organization in SAD, which provides insights into the neural mechanisms underlying excessive fear and avoidance of social interactions in patients with debilitating social anxiety. Copyright © 2017. Published by Elsevier Inc.

Charge Transfer Enhancement in the D-π-A Type Porphyrin Dyes: A Density Functional Theory (DFT) and Time-Dependent Density Functional Theory (TD-DFT) Study.

PubMed

Kang, Guo-Jun; Song, Chao; Ren, Xue-Feng

2016-11-25

The electronic geometries and optical properties of two D-π-A type zinc porphyrin dyes (NCH₃-YD2 and TPhe-YD) were systematically investigated by density functional theory (DFT) and time-dependent density functional theory (TD-DFT) to reveal the origin of significantly altered charge transfer enhancement by changing the electron donor of the famous porphyrin-based sensitizer YD2-o-C8. The molecular geometries and photophysical properties of dyes before and after binding to the TiO₂ cluster were fully investigated. From the analyses of natural bond orbital (NBO), extended charge decomposition analysis (ECDA), and electron density variations (Δρ) between the excited state and ground state, it was found that the introduction of N(CH₃)₂ and 1,1,2-triphenylethene groups enhanced the intramolecular charge-transfer (ICT) character compared to YD2-o-C8. The absorption wavelength and transition possess character were significantly influenced by N(CH₃)₂ and 1,1,2-triphenylethene groups. NCH₃-YD2 with N(CH₃)₂ groups in the donor part is an effective way to improve the interactions between the dyes and TiO₂ surface, light having efficiency (LHE), and free energy change (ΔG inject ), which is expected to be an efficient dye for use in dye-sensitized solar cells (DSSCs).

Health behaviour change theories: contributions to an ICF-based behavioural exercise therapy for individuals with chronic diseases.

PubMed

Geidl, Wolfgang; Semrau, Jana; Pfeifer, Klaus

2014-01-01

The purpose of this perspective is (1) to incorporate recent psychological health behaviour change (HBC) theories into exercise therapeutic programmes, and (2) to introduce the International Classification of Functioning (ICF)-based concept of a behavioural exercise therapy (BET). Relevant personal modifiable factors of physical activity (PA) were identified based on three recent psychological HBC theories. Following the principles of intervention mapping, a matrix of proximal programme objectives specifies desirable parameter values for each personal factor. As a result of analysing reviews on behavioural techniques and intervention programmes of the German rehabilitation setting, we identified exercise-related techniques that impact the personal determinants. Finally, the techniques were integrated into an ICF-based BET concept. Individuals' attitudes, skills, emotions, beliefs and knowledge are important personal factors of PA behaviour. BET systematically addresses these personal factors by a systematic combination of adequate exercise contents with related behavioural techniques. The presented 28 intervention techniques serve as a theory-driven "tool box" for designing complex BET programmes to promote PA. The current paper highlights the usefulness of theory-based integrative research in the field of exercise therapy, offers explicit methods and contents for physical therapists to promote PA behaviour, and introduces the ICF-based conceptual idea of a BET. Implications for Rehabilitation Irrespective of the clients' indication, therapeutic exercise programmes should incorporate effective, theory-based approaches to promote physical activity. Central determinants of physical activity behaviour are a number of personal factors: individuals' attitudes, skills, emotions, beliefs and knowledge. Clinicians implementing exercise therapy should set it within a wider theoretical framework including the personal factors that influence physical activity. To increase exercise-adherence and promote long-term physical activity behaviour change, the concept of a behavioural exercise therapy (BET) offers a theory-based approach to systematically address relevant personal factors with a combination of adequate contents of exercise with exercise-related techniques of behaviour change.