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Sample records for dissymmetry combining theory

  1. Optical signatures of molecular dissymmetry: combining theory with experiments to address stereochemical puzzles.

    PubMed

    Mukhopadhyay, Parag; Wipf, Peter; Beratan, David N

    2009-06-16

    quadrupole and magnetic dipole perturbations by the electromagnetic field. Moreover, OR arises from a combination of nearly canceling contributions to the electronic response. Indeed, the challenge posed by the chiroptical properties delayed the advent of even qualitatively accurate descriptions for some chiroptical signatures until the past decade when, for example, prediction of the observed sign of experimental OR became accessible to theory. The computation of chiroptical signatures, in close coordination with synthesis and spectroscopy, provides a powerful framework to diagnose and interpret the dissymmetry of chemical structures and molecular assemblies. Chiroptical theory now produces new schemes to elucidate structure, to describe the specific molecular sources of chiroptical signatures, and to assist in our understanding of how dissymmetry is templated and propagated in the condensed phase.

  2. Optical signatures of molecular dissymmetry: Combining theory with experiments to address stereochemical puzzles

    PubMed Central

    Mukhopadhyay, Parag; Wipf, Peter; Beratan, David N.

    2009-01-01

    electric dipole and the weaker electric quadrupole and magnetic dipole perturbations of the electromagnetic field. Moreover, OR arises from a combination of nearly canceling contributions to the electronic response. Indeed, the challenge posed by the chiroptical properties delayed the advent of even qualitatively accurate descriptions for some chiroptical signatures until the last decade when, for example, prediction of the observed sign of experimental OR became accessible to theory. The computation of chiroptical signatures, in close coordination with synthesis and spectroscopy, provides a powerful framework to diagnose and to interpret the dissymmetry of chemical structures and molecular assemblies. Chiroptical theory now produces new schemes to elucidate structure, to describe the specific molecular sources of chiroptical signatures, and to assist in our understanding of how dissymmetry is templated and propagated in the condensed phase. PMID:19378940

  3. REVIEWS OF TOPICAL PROBLEMS: Optical activity and dissymmetry in living systems

    NASA Astrophysics Data System (ADS)

    Kizel', V. A.

    1980-06-01

    This brief review describes a characteristic property of living systems-dissymmetry. The progression of phenomena beginning with dissymmetry in the simple chiral molecules that make up living organisms and leading to the manifestation of dissymmetry in psychology is examined. The advantages contributed by dissymmetry in simple molecules to the more complex formations, which originate from and are composed of these molecules and which bring about organization in living systems, are indicated. The theory of chirodiastaltic interactions, as an agent of this organization, is examined. The possibility of initiating and maintaining dissymetry in the form of chiral purity of matter with the participation of autocatalytic and nonequilibrium thermodynamic processes is analyzed. The current hypotheses that explain the emergence of dissymmetry during the evolution of life are reviewed. The fluctuation hypotheses and assumptions concerning the influence of weak constant factors are examined and the corresponding schemes for evolution are presented.

  4. Louis Pasteur, language, and molecular chirality. I. Background and dissymmetry.

    PubMed

    Gal, Joseph

    2011-01-01

    Louis Pasteur resolved sodium ammonium (±)-tartrate in 1848, thereby discovering molecular chirality. Although hindered by the primitive state of organic chemistry, he introduced new terminology and nomenclature for his new science of molecular and crystal chirality. He was well prepared for this task by his rigorous education and innate abilities, and his linguistic achievements eventually earned him membership in the supreme institution for the French language, the Académie française. Dissymmetry had been in use in French from the early 1820s for disruption or absence of symmetry or for dissimilarity or difference in appearance between two objects, and Pasteur initially used it in the latter connotation, without any reference to handedness or enantiomorphism. Soon, however, he adopted it in the meaning of chirality. Asymmetry had been in use in French since 1691 but Pasteur ignored it in favor of dissymmetry. The two terms are not synonymous but it is not clear whether Pasteur recognized this difference in choosing the former over the latter. However, much of the literature mistranslates his dissymmetry as asymmetry. Twenty years before Pasteur the British polymath John Herschel proposed that optical rotation in the noncrystalline state is due to the "unsymmetrical" [his term] nature of the molecules and later used dissymmetrical for handed. Chirality, coined by Lord Kelvin in 1894 and introduced into chemistry by Mislow in 1962, has nearly completely replaced dissymmetry in the meaning of handedness, but the use of dissymmetry continues today in other contexts for lack of symmetry, reduction of symmetry, or dissimilarity. Copyright © 2010 Wiley-Liss, Inc.

  5. Chiral quantum supercrystals with total dissymmetry of optical response

    NASA Astrophysics Data System (ADS)

    Baimuratov, Anvar S.; Gun’Ko, Yurii K.; Baranov, Alexander V.; Fedorov, Anatoly V.; Rukhlenko, Ivan D.

    2016-03-01

    Since chiral nanoparticles are much smaller than the optical wavelength, their enantiomers show little difference in the interaction with circularly polarized light. This scale mismatch makes the enhancement of enantioselectivity in optical excitation of nanoobjects a fundamental challenge in modern nanophotonics. Here we demonstrate that a strong dissymmetry of optical response from achiral nanoobjects can be achieved through their arrangement into chiral superstructures with the length scale comparable to the optical wavelength. This concept is illustrated by the example of the simple helix supercrystal made of semiconductor quantum dots. We show that this supercrystal almost fully absorbs light with one circular polarization and does not absorb the other. The giant circular dichroism of the supercrystal comes from the formation of chiral bright excitons, which are the optically active collective excitations of the entire supercrystal. Owing to the recent advances in assembly and self-organization of nanocrystals in large superparticle structures, the proposed principle of enantioselectivity enhancement has great potential of benefiting various chiral and analytical methods, which are used in biophysics, chemistry, and pharmaceutical science.

  6. Chiral quantum supercrystals with total dissymmetry of optical response

    PubMed Central

    Baimuratov, Anvar S.; Gun’ko, Yurii K.; Baranov, Alexander V.; Fedorov, Anatoly V.; Rukhlenko, Ivan D.

    2016-01-01

    Since chiral nanoparticles are much smaller than the optical wavelength, their enantiomers show little difference in the interaction with circularly polarized light. This scale mismatch makes the enhancement of enantioselectivity in optical excitation of nanoobjects a fundamental challenge in modern nanophotonics. Here we demonstrate that a strong dissymmetry of optical response from achiral nanoobjects can be achieved through their arrangement into chiral superstructures with the length scale comparable to the optical wavelength. This concept is illustrated by the example of the simple helix supercrystal made of semiconductor quantum dots. We show that this supercrystal almost fully absorbs light with one circular polarization and does not absorb the other. The giant circular dichroism of the supercrystal comes from the formation of chiral bright excitons, which are the optically active collective excitations of the entire supercrystal. Owing to the recent advances in assembly and self-organization of nanocrystals in large superparticle structures, the proposed principle of enantioselectivity enhancement has great potential of benefiting various chiral and analytical methods, which are used in biophysics, chemistry, and pharmaceutical science. PMID:26991549

  7. The connection between robustness angles and dissymmetry factors in vibrational circular dichroism spectra

    NASA Astrophysics Data System (ADS)

    Longhi, Giovanna; Tommasini, Matteo; Abbate, Sergio; Polavarapu, Prasad L.

    2015-10-01

    To analyze vibrational circular dichroism (VCD) spectra the angle between the electric and magnetic dipole transition moments was introduced as robustness index. We demonstrate that VCD for each normal mode can be made robust by a suitable translation of the coordinate system origin to a robust point. Normal modes differ in how VCD band robustness varies under translations from these respective robust points. It is shown that variation in robustness of a VCD band depends on a parameter inversely proportional to the dissymmetry factor g. Thus, robustness varies slowly for VCD bands with large dissymmetry factors and vice versa.

  8. Circularly Polarized Phosphorescent Electroluminescence with a High Dissymmetry Factor from PHOLEDs Based on a Platinahelicene.

    PubMed

    Brandt, Jochen R; Wang, Xuhua; Yang, Ying; Campbell, Alasdair J; Fuchter, Matthew J

    2016-08-10

    Circularly polarized (CP) light is of interest in areas such as quantum optical computing, optical spintronics, biomedicine, and high efficiency displays. Direct emission of CP light from organic light-emitting diodes (OLEDs) has been a focus of research as it has the immediate application of increasing efficiency and simplifying device architecture in OLED based displays. High dissymmetry (gEL) factor values have been reported for devices employing fluorescent polymers, but these CP-OLEDs are limited in their ultimate efficiencies by the type of emissive electronic transitions involved. In contrast, phosphorescent OLEDs (PHOLEDs) can emit light from triplet excited states and can therefore achieve very high efficiencies. However, CP-PHOLEDs are significantly understudied, and the two previous reports suffered from very low brightness or gEL values. Here, we use a platinahelicene complex to construct a CP-PHOLED that achieves both a display level brightness and a high gEL factor. The dissymmetry of CP emission reached with this proof-of-concept single-layer helicene-based device is sufficient to provide real-world benefits over nonpolarized emission and paves the way toward chiral metal complex-based CP-PHOLED displays.

  9. A combinational theory for maintenance of sex

    PubMed Central

    Hörandl, E

    2010-01-01

    Sexual reproduction implies high costs, but it is difficult to give evidence for evolutionary advantages that would explain the predominance of meiotic sex in eukaryotes. A combinational theory discussing evolution, maintenance and loss of sex may resolve the problem. The main function of sex is the restoration of DNA and consequently a higher quality of offspring. Recombination at meiosis evolved, perhaps, as a repair mechanism of DNA strand damages. This mechanism is most efficient for DNA restoration in multicellular eukaryotes, because the initial cell starts with a re-optimized genome, which is passed to all the daughter cells. Meiosis acts also as creator of variation in haploid stages, in which selection can purge most efficiently deleterious mutations. A prolonged diploid phase buffers the effects of deleterious recessive alleles as well as epigenetic defects and is thus optimal for prolonged growth periods. For complex multicellular organisms, the main advantage of sexuality is thus the alternation of diploid and haploid stages, combining advantages of both. A loss of sex is constrained by several, partly group-specific, developmental features. Hybridization may trigger shifts from sexual to asexual reproduction, but crossing barriers of the parental sexual species limit this process. For the concerted break-up of meiosis-outcrossing cycles plus silencing of secondary features, various group-specific changes in the regulatory system may be required. An establishment of asexuals requires special functional modifications and environmental opportunities. Costs for maintenance of meiotic sex are consequently lower than a shift to asexual reproduction. PMID:19623209

  10. A combinational theory for maintenance of sex.

    PubMed

    Hörandl, E

    2009-12-01

    Sexual reproduction implies high costs, but it is difficult to give evidence for evolutionary advantages that would explain the predominance of meiotic sex in eukaryotes. A combinational theory discussing evolution, maintenance and loss of sex may resolve the problem. The main function of sex is the restoration of DNA and consequently a higher quality of offspring. Recombination at meiosis evolved, perhaps, as a repair mechanism of DNA strand damages. This mechanism is most efficient for DNA restoration in multicellular eukaryotes, because the initial cell starts with a re-optimized genome, which is passed to all the daughter cells. Meiosis acts also as creator of variation in haploid stages, in which selection can purge most efficiently deleterious mutations. A prolonged diploid phase buffers the effects of deleterious recessive alleles as well as epigenetic defects and is thus optimal for prolonged growth periods. For complex multicellular organisms, the main advantage of sexuality is thus the alternation of diploid and haploid stages, combining advantages of both. A loss of sex is constrained by several, partly group-specific, developmental features. Hybridization may trigger shifts from sexual to asexual reproduction, but crossing barriers of the parental sexual species limit this process. For the concerted break-up of meiosis-outcrossing cycles plus silencing of secondary features, various group-specific changes in the regulatory system may be required. An establishment of asexuals requires special functional modifications and environmental opportunities. Costs for maintenance of meiotic sex are consequently lower than a shift to asexual reproduction.

  11. Combination or Differentiation? Two theories of processing order in classification.

    PubMed

    Wills, Andy J; Inkster, Angus B; Milton, Fraser

    2015-08-01

    Does cognition begin with an undifferentiated stimulus whole, which can be divided into distinct attributes if time and cognitive resources allow (Differentiation Theory)? Or does it begin with the attributes, which are combined if time and cognitive resources allow (Combination Theory)? Across psychology, use of the terms analytic and non-analytic imply that Differentiation Theory is correct-if cognition begins with the attributes, then synthesis, rather than analysis, is the more appropriate chemical analogy. We re-examined four classic studies of the effects of time pressure, incidental training, and concurrent load on classification and category learning (Kemler Nelson, 1984; Smith & Kemler Nelson, 1984; Smith & Shapiro, 1989; Ward, 1983). These studies are typically interpreted as supporting Differentiation Theory over Combination Theory, while more recent work in classification (Milton et al., 2008, et seq.) supports the opposite conclusion. Across seven experiments, replication and re-analysis of the four classic studies revealed that they do not support Differentiation Theory over Combination Theory-two experiments support Combination Theory over Differentiation Theory, and the remainder are compatible with both accounts. We conclude that Combination Theory provides a parsimonious account of both classic and more recent work in this area. The presented data do not require Differentiation Theory, nor a Combination-Differentiation hybrid account.

  12. Combined linear theory/impact theory method for analysis and design of high speed configurations

    NASA Technical Reports Server (NTRS)

    Brooke, D.; Vondrasek, D. V.

    1980-01-01

    Pressure distributions on a wing body at Mach 4.63 are calculated. The combined theory is shown to give improved predictions over either linear theory or impact theory alone. The combined theory is also applied in the inverse design mode to calculate optimum camber slopes at Mach 4.63. Comparisons with optimum camber slopes obtained from unmodified linear theory show large differences. Analysis of the results indicate that the combined theory correctly predicts the effect of thickness on the loading distributions at high Mach numbers, and that finite thickness wings optimized at high Mach numbers using unmodified linear theory will not achieve the minimum drag characteristics for which they are designed.

  13. Combined theory of reflectance and emittance spectroscopy

    NASA Technical Reports Server (NTRS)

    Hapke, Bruce

    1995-01-01

    The theory in which either or both reflected sunlight and thermally emitted radiation contribute to the power received by a detector viewing a particulate medium, such as a powder in the laboratory or a planetary regolith, is considered theoretically. This theory is of considerable interest for the interpretation of data from field or spacecraft instruments that are sensitive to the near-infrared region of the spectrum, such as NIMS (near-infrared mapping spectrometer) and VIMS (visual and infrared mapping spectrometer), as well as thermal infrared detectors.

  14. Quantum and concept combination, entangled measurements, and prototype theory.

    PubMed

    Aerts, Diederik

    2014-01-01

    We analyze the meaning of the violation of the marginal probability law for situations of correlation measurements where entanglement is identified. We show that for quantum theory applied to the cognitive realm such a violation does not lead to the type of problems commonly believed to occur in situations of quantum theory applied to the physical realm. We briefly situate our quantum approach for modeling concepts and their combinations with respect to the notions of "extension" and "intension" in theories of meaning, and in existing concept theories.

  15. Explaining Academic Progress via Combining Concepts of Integration Theory and Rational Choice Theory.

    ERIC Educational Resources Information Center

    Beekhoven, S.; De Jong, U.; Van Hout, H.

    2002-01-01

    Compared elements of rational choice theory and integration theory on the basis of their power to explain variance in academic progress. Asserts that the concepts should be combined, and the distinction between social and academic integration abandoned. Empirical analysis showed that an extended model, comprising both integration and rational…

  16. Evidence Combination From an Evolutionary Game Theory Perspective.

    PubMed

    Deng, Xinyang; Han, Deqiang; Dezert, Jean; Deng, Yong; Shyr, Yu

    2016-09-01

    Dempster-Shafer evidence theory is a primary methodology for multisource information fusion because it is good at dealing with uncertain information. This theory provides a Dempster's rule of combination to synthesize multiple evidences from various information sources. However, in some cases, counter-intuitive results may be obtained based on that combination rule. Numerous new or improved methods have been proposed to suppress these counter-intuitive results based on perspectives, such as minimizing the information loss or deviation. Inspired by evolutionary game theory, this paper considers a biological and evolutionary perspective to study the combination of evidences. An evolutionary combination rule (ECR) is proposed to help find the most biologically supported proposition in a multievidence system. Within the proposed ECR, we develop a Jaccard matrix game to formalize the interaction between propositions in evidences, and utilize the replicator dynamics to mimick the evolution of propositions. Experimental results show that the proposed ECR can effectively suppress the counter-intuitive behaviors appeared in typical paradoxes of evidence theory, compared with many existing methods. Properties of the ECR, such as solution's stability and convergence, have been mathematically proved as well.

  17. A gain-control theory of binocular combination.

    PubMed

    Ding, Jian; Sperling, George

    2006-01-24

    In binocular combination, light images on the two retinas are combined to form a single "cyclopean" perceptual image, in contrast to binocular rivalry which occurs when the two eyes have incompatible ("rivalrous") inputs and only one eye;s stimulus is perceived. We propose a computational theory for binocular combination with two basic principles of interaction: in every spatial neighborhood, each eye (i) exerts gain control on the other eye's signal in proportion to the contrast energy of its own input and (ii) additionally exerts gain control on the other eye's gain control. For stimuli of ordinary contrast, when either eye is stimulated alone, the predicted cyclopean image is the same as when both eyes are stimulated equally, coinciding with an easily observed property of natural vision. The gain-control theory is contrast dependent: Very low-contrast stimuli to the left- and right-eye add linearly to form the predicted cyclopean image. The intrinsic nonlinearity manifests itself only as contrast increases. To test the theory more precisely, a horizontal sine wave grating of 0.68 cycles per degree is presented to each eye. The gratings differ in contrast and phase. The predicted (and perceived) cyclopean grating also is a sine wave; its apparent phase indicates the relative contribution of the two eyes to the cyclopean image. For 48 measured combinations of phase and contrast, the theory with only one estimated parameter accounts for 95% of the variance of the data. Therefore, a simple, robust, physiologically plausible gain-control theory accurately describes an early stage of binocular combination.

  18. Comprehensive theory for star-like polymer micelles; combining classical nucleation and polymer brush theory.

    PubMed

    Sprakel, Joris; Leermakers, Frans A M; Cohen Stuart, Martien A; Besseling, Nicolaas A M

    2008-09-14

    A comprehensive theory is proposed that combines classical nucleation and polymer brush theory to describe star-like polymer micelles. With a minimum of adjustable parameters, the model predicts properties such as critical micelle concentrations and micellar size distributions. The validity of the present theory is evidenced in direct comparison to experiments; this revealed that the proportionality constant in the Daoud-Cotton model is of the order of unity and that the star-limit is valid down to relatively short corona chains. Furthermore, we show that the predicted saddle points in the free energy correspond to those solutions that are accessible with self-consistent field methods for self-assembly.

  19. Tutorial: Defects in semiconductors—Combining experiment and theory

    NASA Astrophysics Data System (ADS)

    Alkauskas, Audrius; McCluskey, Matthew D.; Van de Walle, Chris G.

    2016-05-01

    Point defects affect or even completely determine physical and chemical properties of semiconductors. Characterization of point defects based on experimental techniques alone is often inconclusive. In such cases, the combination of experiment and theory is crucial to gain understanding of the system studied. In this tutorial, we explain how and when such comparison provides new understanding of the defect physics. More specifically, we focus on processes that can be analyzed or understood in terms of configuration coordinate diagrams of defects in their different charge states. These processes include light absorption, luminescence, and nonradiative capture of charge carriers. Recent theoretical developments to describe these processes are reviewed.

  20. Correlation effects in the theory of combined Doppler and pressure broadening. I - Classical theory

    NASA Technical Reports Server (NTRS)

    Ward, J.; Cooper, J.; Smith, E. W.

    1974-01-01

    An investigation is conducted of the combined effects of radiator-perturber collisions and radiator translational motion in the context of foreign gas broadening of optical transitions in neutral radiators. Questions concerning the speed-dependent collision frequency are considered and aspects of general theory are explored, taking into account the correlation function, the ensemble average, and the kinetic equation formalism. An elementary solution is discussed along with a one-perturber approximation, inverse power law model calculations, and a comparison with the Voigt profile.

  1. Feasibility of combining linear theory and impact theory methods for the analysis and design of high speed configurations

    NASA Technical Reports Server (NTRS)

    Brooke, D.; Vondrasek, D. V.

    1978-01-01

    The aerodynamic influence coefficients calculated using an existing linear theory program were used to modify the pressures calculated using impact theory. Application of the combined approach to several wing-alone configurations shows that the combined approach gives improved predictions of the local pressure and loadings over either linear theory alone or impact theory alone. The approach not only removes most of the short-comings of the individual methods, as applied in the Mach 4 to 8 range, but also provides the basis for an inverse design procedure applicable to high speed configurations.

  2. [A proposal to combine Roy's conceptual framework with crisis theory].

    PubMed

    Luis, M V

    1990-04-01

    It is reported the crisis theory framework's and is proposed its linkage with the Callista Roy conceptual Model. The aim is to provide the nurse with an instrumental and theoretical framework of the knowledge of the person in crisis intervention. In this proposition is still suggested, a guide to nursing care. It is derived of both theories and exemplified by the author trough practice application.

  3. School Psychology Research: Combining Ecological Theory and Prevention Science

    ERIC Educational Resources Information Center

    Burns, Matthew K.

    2011-01-01

    The current article comments on the importance of theoretical implications within school psychological research, and proposes that ecological theory and prevention science could provide the conceptual framework for school psychology research and practice. Articles published in "School Psychology Review" should at least discuss potential…

  4. School Psychology Research: Combining Ecological Theory and Prevention Science

    ERIC Educational Resources Information Center

    Burns, Matthew K.

    2011-01-01

    The current article comments on the importance of theoretical implications within school psychological research, and proposes that ecological theory and prevention science could provide the conceptual framework for school psychology research and practice. Articles published in "School Psychology Review" should at least discuss potential…

  5. Cycloalkyl-based unsymmetrical unsaturated (U₂)-NHC ligands: flexibility and dissymmetry in ruthenium-catalysed olefin metathesis.

    PubMed

    Rouen, Mathieu; Borré, Etienne; Falivene, Laura; Toupet, Loic; Berthod, Mikaël; Cavallo, Luigi; Olivier-Bourbigou, Hélène; Mauduit, Marc

    2014-05-21

    Air-stable Ru-indenylidene and Hoveyda-type complexes bearing new unsymmetrical unsaturated N-heterocyclic carbene (U2-NHC) ligands combining a mesityl unit and a flexible cycloalkyl moiety as N-substituents were synthesised. Structural features, chemical stabilities and catalytic profiles in olefin metathesis of this new library of cycloalkyl-based U2-NHC Ru complexes were studied and compared with their unsymmetrical saturated NHC-Ru homologues as well as a set of commercially available Ru-catalysts bearing either symmetrical SIMes or IMes NHC ligands.

  6. Combining Optimal Control Theory and Molecular Dynamics for Protein Folding

    PubMed Central

    Arkun, Yaman; Gur, Mert

    2012-01-01

    A new method to develop low-energy folding routes for proteins is presented. The novel aspect of the proposed approach is the synergistic use of optimal control theory with Molecular Dynamics (MD). In the first step of the method, optimal control theory is employed to compute the force field and the optimal folding trajectory for the atoms of a Coarse-Grained (CG) protein model. The solution of this CG optimization provides an harmonic approximation of the true potential energy surface around the native state. In the next step CG optimization guides the MD simulation by specifying the optimal target positions for the atoms. In turn, MD simulation provides an all-atom conformation whose positions match closely the reference target positions determined by CG optimization. This is accomplished by Targeted Molecular Dynamics (TMD) which uses a bias potential or harmonic restraint in addition to the usual MD potential. Folding is a dynamical process and as such residues make different contacts during the course of folding. Therefore CG optimization has to be reinitialized and repeated over time to accomodate these important changes. At each sampled folding time, the active contacts among the residues are recalculated based on the all-atom conformation obtained from MD. Using the new set of contacts, the CG potential is updated and the CG optimal trajectory for the atoms is recomputed. This is followed by MD. Implementation of this repetitive CG optimization - MD simulation cycle generates the folding trajectory. Simulations on a model protein Villin demonstrate the utility of the method. Since the method is founded on the general tools of optimal control theory and MD without any restrictions, it is widely applicable to other systems. It can be easily implemented with available MD software packages. PMID:22238629

  7. Combining optimal control theory and molecular dynamics for protein folding.

    PubMed

    Arkun, Yaman; Gur, Mert

    2012-01-01

    A new method to develop low-energy folding routes for proteins is presented. The novel aspect of the proposed approach is the synergistic use of optimal control theory with Molecular Dynamics (MD). In the first step of the method, optimal control theory is employed to compute the force field and the optimal folding trajectory for the Cα atoms of a Coarse-Grained (CG) protein model. The solution of this CG optimization provides an harmonic approximation of the true potential energy surface around the native state. In the next step CG optimization guides the MD simulation by specifying the optimal target positions for the Cα atoms. In turn, MD simulation provides an all-atom conformation whose Cα positions match closely the reference target positions determined by CG optimization. This is accomplished by Targeted Molecular Dynamics (TMD) which uses a bias potential or harmonic restraint in addition to the usual MD potential. Folding is a dynamical process and as such residues make different contacts during the course of folding. Therefore CG optimization has to be reinitialized and repeated over time to accomodate these important changes. At each sampled folding time, the active contacts among the residues are recalculated based on the all-atom conformation obtained from MD. Using the new set of contacts, the CG potential is updated and the CG optimal trajectory for the Cα atoms is recomputed. This is followed by MD. Implementation of this repetitive CG optimization-MD simulation cycle generates the folding trajectory. Simulations on a model protein Villin demonstrate the utility of the method. Since the method is founded on the general tools of optimal control theory and MD without any restrictions, it is widely applicable to other systems. It can be easily implemented with available MD software packages.

  8. Hegemonic masculinity: combining theory and practice in gender interventions

    PubMed Central

    Jewkes, Rachel; Morrell, Robert; Hearn, Jeff; Lundqvist, Emma; Blackbeard, David; Lindegger, Graham; Quayle, Michael; Sikweyiya, Yandisa; Gottzén, Lucas

    2015-01-01

    The concept of hegemonic masculinity has been used in gender studies since the early-1980s to explain men’s power over women. Stressing the legitimating power of consent (rather than crude physical or political power to ensure submission), it has been used to explain men’s health behaviours and the use of violence. Gender activists and others seeking to change men’s relations with women have mobilised the concept of hegemonic masculinity in interventions, but the links between gender theory and activism have often not been explored. The translation of ‘hegemonic masculinity’ into interventions is little examined. We show how, in South Africa and Sweden, the concept has been used to inform theoretically-based gender interventions and to ensure that men are brought into broader social efforts to build gender equity. We discuss the practical translational challenges of using gender theory broadly, and hegemonic masculinity in particular, in a Swedish case study, of the intervention Machofabriken [The Macho Factory], and illustrate how the concept is brought to life in this activist work with men. The concept has considerable practical application in developing a sustainable praxis of theoretically grounded interventions that are more likely to have enduring effect, but evaluating broader societal change in hegemonic masculinity remains an enduring challenge. PMID:26680535

  9. Hegemonic masculinity: combining theory and practice in gender interventions.

    PubMed

    Jewkes, Rachel; Morrell, Robert; Hearn, Jeff; Lundqvist, Emma; Blackbeard, David; Lindegger, Graham; Quayle, Michael; Sikweyiya, Yandisa; Gottzén, Lucas

    2015-01-01

    The concept of hegemonic masculinity has been used in gender studies since the early-1980s to explain men's power over women. Stressing the legitimating power of consent (rather than crude physical or political power to ensure submission), it has been used to explain men's health behaviours and the use of violence. Gender activists and others seeking to change men's relations with women have mobilised the concept of hegemonic masculinity in interventions, but the links between gender theory and activism have often not been explored. The translation of 'hegemonic masculinity' into interventions is little examined. We show how, in South Africa and Sweden, the concept has been used to inform theoretically-based gender interventions and to ensure that men are brought into broader social efforts to build gender equity. We discuss the practical translational challenges of using gender theory broadly, and hegemonic masculinity in particular, in a Swedish case study, of the intervention Machofabriken [The Macho Factory], and illustrate how the concept is brought to life in this activist work with men. The concept has considerable practical application in developing a sustainable praxis of theoretically grounded interventions that are more likely to have enduring effect, but evaluating broader societal change in hegemonic masculinity remains an enduring challenge.

  10. Combining theory and experiment in electrocatalysis: Insights into materials design.

    PubMed

    Seh, Zhi Wei; Kibsgaard, Jakob; Dickens, Colin F; Chorkendorff, Ib; Nørskov, Jens K; Jaramillo, Thomas F

    2017-01-13

    Electrocatalysis plays a central role in clean energy conversion, enabling a number of sustainable processes for future technologies. This review discusses design strategies for state-of-the-art heterogeneous electrocatalysts and associated materials for several different electrochemical transformations involving water, hydrogen, and oxygen, using theory as a means to rationalize catalyst performance. By examining the common principles that govern catalysis for different electrochemical reactions, we describe a systematic framework that clarifies trends in catalyzing these reactions, serving as a guide to new catalyst development while highlighting key gaps that need to be addressed. We conclude by extending this framework to emerging clean energy reactions such as hydrogen peroxide production, carbon dioxide reduction, and nitrogen reduction, where the development of improved catalysts could allow for the sustainable production of a broad range of fuels and chemicals.

  11. Combining theory and experiment in electrocatalysis: Insights into materials design

    DOE PAGES

    Seh, Zhi Wei; Kibsgaard, Jakob; Dickens, Colin F.; ...

    2017-01-12

    Electrocatalysis plays a central role in clean energy conversion, enabling a number of sustainable processes for future technologies. This review discusses design strategies for state-of-the-art heterogeneous electrocatalysts and associated materials for several different electrochemical transformations involving water, hydrogen, and oxygen, using theory as a means to rationalize catalyst performance. By examining the common principles that govern catalysis for different electrochemical reactions, we describe a systematic framework that clarifies trends in catalyzing these reactions, serving as a guide to new catalyst development while highlighting key gaps that need to be addressed. Here, we conclude by extending this framework to emerging cleanmore » energy reactions such as hydrogen peroxide production, carbon dioxide reduction, and nitrogen reduction, where the development of improved catalysts could allow for the sustainable production of a broad range of fuels and chemicals.« less

  12. Blockage fault diagnosis method of combine harvester based on BPNN and DS evidence theory

    NASA Astrophysics Data System (ADS)

    Chen, Jin; Xu, Kai; Wang, Yifan; Wang, Kun; Wang, Shuqing

    2017-01-01

    According to the complexity and the lack of intelligent analysis method of combine harvester blockage fault , this paper puts forward a method , based on the combination of BP neural network (BPNN)and DS evidence theory , for combine harvester blockage fault diagnosis. Choosing cutting table auger, conveyer trough, threshing cylinder and grain conveying auger as the study, this paper divides the condition of combine harvester into four categories, namely, normal, slightly blocking, blockage, severe blockage, which being as an identification framework for DS evidence theory. BP neural network is used for analysing speed information of monitoring points and distributing basic probability for each proposition in the identification framework. Dempster combination rule converged information at different time to obtain diagnostic results.Test results show that this method can timely and accurately judge the work state of combine harvester, the blocking fault warning time will be increased to 2 seconds and the success probability of blocking fault warning reach more than 90%.

  13. Literacity: A multimedia adult literacy package combining NASA technology, recursive ID theory, and authentic instruction theory

    NASA Technical Reports Server (NTRS)

    Willis, Jerry; Willis, Dee Anna; Walsh, Clare; Stephens, Elizabeth; Murphy, Timothy; Price, Jerry; Stevens, William; Jackson, Kevin; Villareal, James A.; Way, Bob

    1994-01-01

    An important part of NASA's mission involves the secondary application of its technologies in the public and private sectors. One current application under development is LiteraCity, a simulation-based instructional package for adults who do not have functional reading skills. Using fuzzy logic routines and other technologies developed by NASA's Information Systems Directorate and hypermedia sound, graphics, and animation technologies the project attempts to overcome the limited impact of adult literacy assessment and instruction by involving the adult in an interactive simulation of real-life literacy activities. The project uses a recursive instructional development model and authentic instruction theory. This paper describes one component of a project to design, develop, and produce a series of computer-based, multimedia instructional packages. The packages are being developed for use in adult literacy programs, particularly in correctional education centers. They use the concepts of authentic instruction and authentic assessment to guide development. All the packages to be developed are instructional simulations. The first is a simulation of 'finding a friend a job.'

  14. Combined experiment and theory approach in surface chemistry: Stairway to heaven?

    NASA Astrophysics Data System (ADS)

    Exner, Kai S.; Heß, Franziska; Over, Herbert; Seitsonen, Ari Paavo

    2015-10-01

    In this perspective we discuss how an intimate interaction of experiments with theory is able to deepen our insight into the catalytic reaction system on the molecular level. This strategy is illustrated by discussing various examples from our own research of surface chemistry and model catalysis. The particular examples were carefully chosen to balance the specific strength of both approaches - theory and experiment - and emphasize the benefit of this combined approach. We start with the determination of complex surface structures, where diffraction techniques in combination with theory are clear-cut. The promoter action of alkali metals in heterogeneous catalysis is rationalized with theory and experiment for the case of CO coadsorption. Predictive power of theory is limited as demonstrated with the apparent activity of chlorinated TiO2(110) in the oxidation of HCl: Even if we know all elementary reaction steps of a catalytic reaction mechanism, the overall kinetics may remain elusive and require the application kinetic Monte Carlo simulations. Catalysts are not always stable under reaction conditions and may chemically transform as discussed for the CO oxidation reaction over ruthenium. Under oxidizing reaction conditions ruthenium transforms into RuO2, a process which is hardly understood on the molecular level. Lastly we focus on electrochemical reactions. Here theory is clearly ahead since spectroscopic methods are not available to resolve the processes at the electrode surface.

  15. Atomic Theory and Multiple Combining Proportions: The Search for Whole Number Ratios.

    PubMed

    Usselman, Melvyn C; Brown, Todd A

    2015-04-01

    John Dalton's atomic theory, with its postulate of compound formation through atom-to-atom combination, brought a new perspective to weight relationships in chemical reactions. A presumed one-to-one combination of atoms A and B to form a simple compound AB allowed Dalton to construct his first table of relative atomic weights from literature analyses of appropriate binary compounds. For such simple binary compounds, the atomic theory had little advantages over affinity theory as an explanation of fixed proportions by weight. For ternary compounds of the form AB2, however, atomic theory made quantitative predictions that were not deducible from affinity theory. Atomic theory required that the weight of B in the compound AB2 be exactly twice that in the compound AB. Dalton, Thomas Thomson and William Hyde Wollaston all published within a few years of each other experimental data that claimed to give the predicted results with the required accuracy. There are nonetheless several experimental barriers to obtaining the desired integral multiple proportions. In this paper I will discuss replication experiments which demonstrate that only Wollaston's results are experimentally reliable. It is likely that such replicability explains why Wollaston's experiments were so influential.

  16. A combined theory for magnetohydrodynamic equilibria with anisotropic pressure and magnetic shear

    NASA Astrophysics Data System (ADS)

    Hodgson, J. D. B.; Neukirch, T.

    2017-03-01

    We present a new approach to the theory of magnetohydrodynamic equilibria with anisotropic pressure, magnetic shear and translational/rotational invariance. This approach involves combining two existing formalisms in order to eliminate their individual weaknesses. The theoretical aspects of the method are explored in detail along with numerical solutions which make use of the method. Eventually, this method could be applied to model various plasma systems, such as planetary magnetospheres.

  17. Exploring the Combination of Dempster-Shafer Theory and Neural Network for Predicting Trust and Distrust.

    PubMed

    Wang, Xin; Wang, Ying; Sun, Hongbin

    2016-01-01

    In social media, trust and distrust among users are important factors in helping users make decisions, dissect information, and receive recommendations. However, the sparsity and imbalance of social relations bring great difficulties and challenges in predicting trust and distrust. Meanwhile, there are numerous inducing factors to determine trust and distrust relations. The relationship among inducing factors may be dependency, independence, and conflicting. Dempster-Shafer theory and neural network are effective and efficient strategies to deal with these difficulties and challenges. In this paper, we study trust and distrust prediction based on the combination of Dempster-Shafer theory and neural network. We firstly analyze the inducing factors about trust and distrust, namely, homophily, status theory, and emotion tendency. Then, we quantify inducing factors of trust and distrust, take these features as evidences, and construct evidence prototype as input nodes of multilayer neural network. Finally, we propose a framework of predicting trust and distrust which uses multilayer neural network to model the implementing process of Dempster-Shafer theory in different hidden layers, aiming to overcome the disadvantage of Dempster-Shafer theory without optimization method. Experimental results on a real-world dataset demonstrate the effectiveness of the proposed framework.

  18. Exploring the Combination of Dempster-Shafer Theory and Neural Network for Predicting Trust and Distrust

    PubMed Central

    Wang, Xin; Wang, Ying; Sun, Hongbin

    2016-01-01

    In social media, trust and distrust among users are important factors in helping users make decisions, dissect information, and receive recommendations. However, the sparsity and imbalance of social relations bring great difficulties and challenges in predicting trust and distrust. Meanwhile, there are numerous inducing factors to determine trust and distrust relations. The relationship among inducing factors may be dependency, independence, and conflicting. Dempster-Shafer theory and neural network are effective and efficient strategies to deal with these difficulties and challenges. In this paper, we study trust and distrust prediction based on the combination of Dempster-Shafer theory and neural network. We firstly analyze the inducing factors about trust and distrust, namely, homophily, status theory, and emotion tendency. Then, we quantify inducing factors of trust and distrust, take these features as evidences, and construct evidence prototype as input nodes of multilayer neural network. Finally, we propose a framework of predicting trust and distrust which uses multilayer neural network to model the implementing process of Dempster-Shafer theory in different hidden layers, aiming to overcome the disadvantage of Dempster-Shafer theory without optimization method. Experimental results on a real-world dataset demonstrate the effectiveness of the proposed framework. PMID:27034651

  19. Influence of Fock exchange in combined many-body perturbation and dynamical mean field theory

    NASA Astrophysics Data System (ADS)

    Ayral, Thomas; Biermann, Silke; Werner, Philipp; Boehnke, Lewin

    2017-06-01

    In electronic systems with long-range Coulomb interaction, the nonlocal Fock-exchange term has a band-widening effect. While this effect is included in combined many-body perturbation theory and dynamical mean field theory (DMFT) schemes, it is not taken into account in standard extended DMFT (EDMFT) calculations. Here, we include this instantaneous term in both approaches and investigate its effect on the phase diagram and dynamically screened interaction. We show that the largest deviations between previously presented EDMFT and G W +EDMFT results originate from the nonlocal Fock term, and that the quantitative differences are especially large in the strong-coupling limit. Furthermore, we show that the charge-ordering phase diagram obtained in G W +EDMFT methods for moderate interaction values is very similar to the one predicted by dual-boson methods that include the fermion-boson or four-point vertex.

  20. Analysing collaboration among HIV agencies through combining network theory and relational coordination.

    PubMed

    Khosla, Nidhi; Marsteller, Jill Ann; Hsu, Yea Jen; Elliott, David L

    2016-02-01

    Agencies with different foci (e.g. nutrition, social, medical, housing) serve people living with HIV (PLHIV). Serving needs of PLHIV comprehensively requires a high degree of coordination among agencies which often benefits from more frequent communication. We combined Social Network theory and Relational Coordination theory to study coordination among HIV agencies in Baltimore. Social Network theory implies that actors (e.g., HIV agencies) establish linkages amongst themselves in order to access resources (e.g., information). Relational Coordination theory suggests that high quality coordination among agencies or teams relies on the seven dimensions of frequency, timeliness and accuracy of communication, problem-solving communication, knowledge of agencies' work, mutual respect and shared goals. We collected data on frequency of contact from 57 agencies using a roster method. Response options were ordinal ranging from 'not at all' to 'daily'. We analyzed data using social network measures. Next, we selected agencies with which at least one-third of the sample reported monthly or more frequent interaction. This yielded 11 agencies whom we surveyed on seven relational coordination dimensions with questions scored on a Likert scale of 1-5. Network density, defined as the proportion of existing connections to all possible connections, was 20% when considering monthly or higher interaction. Relational coordination scores from individual agencies to others ranged between 1.17 and 5.00 (maximum possible score 5). The average scores for different dimensions across all agencies ranged between 3.30 and 4.00. Shared goals (4.00) and mutual respect (3.91) scores were highest, while scores such as knowledge of each other's work and problem-solving communication were relatively lower. Combining theoretically driven analyses in this manner offers an innovative way to provide a comprehensive picture of inter-agency coordination and the quality of exchange that underlies

  1. Projected Hartree-Fock theory as a polynomial of particle-hole excitations and its combination with variational coupled cluster theory

    NASA Astrophysics Data System (ADS)

    Qiu, Yiheng; Henderson, Thomas M.; Scuseria, Gustavo E.

    2017-05-01

    Projected Hartree-Fock theory provides an accurate description of many kinds of strong correlations but does not properly describe weakly correlated systems. Coupled cluster theory, in contrast, does the opposite. It therefore seems natural to combine the two so as to describe both strong and weak correlations with high accuracy in a relatively black-box manner. Combining the two approaches, however, is made more difficult by the fact that the two techniques are formulated very differently. In earlier work, we showed how to write spin-projected Hartree-Fock in a coupled-cluster-like language. Here, we fill in the gaps in that earlier work. Further, we combine projected Hartree-Fock and coupled cluster theory in a variational formulation and show how the combination performs for the description of the Hubbard Hamiltonian and for several small molecular systems.

  2. Characterizing Molecular Structure by Combining Experimental Measurements with Density Functional Theory Computations

    NASA Astrophysics Data System (ADS)

    Lopez-Encarnacion, Juan M.

    2016-06-01

    In this talk, the power and synergy of combining experimental measurements with density functional theory computations as a single tool to unambiguously characterize the molecular structure of complex atomic systems is shown. Here, we bring three beautiful cases where the interaction between the experiment and theory is in very good agreement for both finite and extended systems: 1) Characterizing Metal Coordination Environments in Porous Organic Polymers: A Joint Density Functional Theory and Experimental Infrared Spectroscopy Study 2) Characterization of Rhenium Compounds Obtained by Electrochemical Synthesis After Aging Process and 3) Infrared Study of H(D)2 + Co4+ Chemical Reaction: Characterizing Molecular Structures. J.M. López-Encarnación, K.K. Tanabe, M.J.A. Johnson, J. Jellinek, Chemistry-A European Journal 19 (41), 13646-13651 A. Vargas-Uscategui, E. Mosquera, J.M. López-Encarnación, B. Chornik, R. S. Katiyar, L. Cifuentes, Journal of Solid State Chemistry 220, 17-21

  3. Mott Multiferroics and Ferroelectric Metals from Dynamical Mean-Field Theory combined with Density-Functional Theory

    NASA Astrophysics Data System (ADS)

    Capone, Massimo

    2015-03-01

    Multiferroic materials, in which ferroelectricity and long-range magnetic ordering coexist, are natural candidates for applications. In this perspective, the most promising compounds are those in which the two phenomena do not simply coexist, but they influence each other through a magnetoelectric coupling. We present different applications of Density Functional Theory combined with Dynamical Mean-Field Theory in which electron-electron correlation effects are crucial in the stabilization of multiferroic behavior and in the magnetoelectric coupling. Within this wide family we can distinguish different cases. In Sr0.5Ba0.5MnO3 the multiferroic behavior is associated with a Mott insulating state in which the Mn half-filled t2g orbitals are responsible of the magnetic properties and the value of the polarization is strongly affected by the magnetic state. LiOsO3 shares the same electronic configuration with half-filled Os t2g orbitals. Despite this configuration enhances the effect of electron-electron interactions, the material remains metallic and represents a peculiar ferroelectric metal. We propose however how to turn this non-magnetic polar metal into a multiferroic through the design of a superlattice, which increases the degree of correlation, leading to Mott localization of the Os orbitals. In completely different systems, such as organic crystals like (TMTTF)2-X, strong correlations can lead to multiferroicity in organic crystals such as (TMTTF)2-X, where charge ordering promotes a polarization which is favored by an antiferromagnetic ordering. We finally discuss how strong correlations can play a major role away from half-filling when the Hund's coupling is sizable in compounds with a nominal valence of, e.g., two electrons in the three t2g orbitals. Such ``Hund's metals'' are correlated despite being far from Mott localization. This physical regime can be a fertile ground to obtain other ferroelectric metals. This work is supported by ERC/FP7 through the

  4. Generalized Hybrid-Orbital Method for Combining Density Functional Theory with Molecular Mechanicals

    PubMed Central

    Pu, Jingzhi; Gao, Jiali; Truhlar, Donald G.

    2015-01-01

    The generalized hybrid orbital (GHO) method has previously been formulated for combining molecular mechanics with various levels of quantum mechanics, in particular semiempirical neglect of diatomic differential overlap theory, ab initio Hartree–Fock theory, and self-consistent charge density functional tight-binding theory. To include electron-correlation effects accurately and efficiently in GHO calculations, we extend the GHO method to density functional theory in the generalized-gradient approximation and hybrid density functional theory (denoted by GHO-DFT and GHO-HDFT, respectively) using Gaussian-type orbitals as basis functions. In the proposed GHO-(H)DFT formalism, charge densities in auxiliary hybrid orbitals are included to calculate the total electron density. The orthonormality constraints involving the auxiliary Kohn–Sham orbitals are satisfied by carrying out the hybridization in terms of a set of Löwdin symmetrically orthogonalized atomic basis functions. Analytical gradients are formulated for GHO-(H)DFT by incorporating additional forces associated with GHO basis transformations. Scaling parameters are introduced for some of the one-electron integrals and are optimized to obtain the correct charges and geometry near the QM/MM boundary region. The GHO-(H)DFT method based on the generalized gradient approach (GGA) (BLYP and mPWPW91) and HDFT methods (B3 LYP, mPW1PW91, and MPW1K) is tested—for geometries and atomic charges—against a set of small molecules. The following quantities are tested: 1) the C–C stretch potential in ethane, 2) the torsional barrier for internal rotation around the central C–C bond in n-butane, 3) proton affinities for a set of alcohols, amines, thiols, and acids, 4) the conformational energies of alanine dipeptide, and 5) the barrier height of the hydrogenatom transfer between n-C4H10 and n-C4H9, where the reaction center is described at the MPW1K/6–31G(d) level of theory. PMID:16086343

  5. A multimedia adult literacy program: Combining NASA technology, instructional design theory, and authentic literacy concepts

    NASA Technical Reports Server (NTRS)

    Willis, Jerry W.

    1993-01-01

    For a number of years, the Software Technology Branch of the Information Systems Directorate has been involved in the application of cutting edge hardware and software technologies to instructional tasks related to NASA projects. The branch has developed intelligent computer aided training shells, instructional applications of virtual reality and multimedia, and computer-based instructional packages that use fuzzy logic for both instructional and diagnostic decision making. One outcome of the work on space-related technology-supported instruction has been the creation of a significant pool of human talent in the branch with current expertise on the cutting edges of instructional technologies. When the human talent is combined with advanced technologies for graphics, sound, video, CD-ROM, and high speed computing, the result is a powerful research and development group that both contributes to the applied foundations of instructional technology and creates effective instructional packages that take advantage of a range of advanced technologies. Several branch projects are currently underway that combine NASA-developed expertise to significant instructional problems in public education. The branch, for example, has developed intelligent computer aided software to help high school students learn physics and staff are currently working on a project to produce educational software for young children with language deficits. This report deals with another project, the adult literacy tutor. Unfortunately, while there are a number of computer-based instructional packages available for adult literacy instruction, most of them are based on the same instructional models that failed these students when they were in school. The teacher-centered, discrete skill and drill-oriented, instructional strategies, even when they are supported by color computer graphics and animation, that form the foundation for most of the computer-based literacy packages currently on the market may not

  6. Recent advances in combination of capillary electrophoresis with mass spectrometry: methodology and theory.

    PubMed

    Klepárník, Karel

    2015-01-01

    This review focuses on the latest development of microseparation electromigration methods in capillaries and microfluidic devices with MS detection and identification. A wide selection of 183 relevant articles covers the literature published from June 2012 till May 2014 as a continuation of the review article on the same topic by Kleparnik [Electrophoresis 2013, 34, 70-86]. Special attention is paid to the new improvements in the theory of instrumentation and methodology of MS interfacing with capillary versions of zone electrophoresis, ITP, and IEF. Ionization methods in MS include ESI, MALDI, and ICP. Although the main attention is paid to the development of instrumentation and methodology, representative examples illustrate also applications in the proteomics, glycomics, metabolomics, biomarker research, forensics, pharmacology, food analysis, and single-cell analysis. The combinations of MS with capillary versions of electrochromatography and micellar electrokinetic chromatography are not included.

  7. Major Successes of Theory-and-Experiment-Combined Studies in Surface Chemistry and Heterogeneous Catalysis.

    SciTech Connect

    Somorjai, Gabor A.; Li, Yimin

    2009-11-21

    Experimental discoveries followed by theoretical interpretations that pave the way of further advances by experimentalists is a developing pattern in modern surface chemistry and catalysis. The revolution of modern surface science started with the development of surface-sensitive techniques such as LEED, XPS, AES, ISS and SIMS, in which the close collaboration between experimentalists and theorists led to the quantitative determination of surface structure and composition. The experimental discovery of the chemical activity of surface defects and the trends in the reactivity of transitional metals followed by the explanations from the theoretical studies led to the molecular level understanding of active sites in catalysis. The molecular level knowledge, in turn, provided a guide for experiments to search for new generation of catalysts. These and many other examples of successes in experiment-and-theory-combined studies demonstrate the importance of the collaboration between experimentalists and theorists in the development of modern surface science.

  8. A combined picture from theory and experiments on water oxidation, oxygen reduction and proton pumping.

    PubMed

    Siegbahn, Per E M; Blomberg, Margareta R A

    2009-08-14

    In order to illustrate how theory and experiments can be combined, examples are taken from two projects that have been going on for a decade. The goal is to obtain the full mechanistic picture of water oxidation in photosystem II and proton pumping in cytochrome c oxidase. It is argued that for obtaining a complete description of these processes, both experiments and theoretical calculations are needed. It is obvious that there are aspects, which are out of reach for computations, but there are also key aspects that can not be obtained by experiments. This concerns very short-lived species but also, in the case of photosynthesis in particular, structural information that is presently out of reach. The main contributions from theory in the present cases, is for photosynthesis a mechanism for O-O bond formation including new and improved structures for all S-states, and for proton pumping a plausible and simple mechanism for proton gating. The examples also illustrate that sometimes rather qualitative experimental information can be of highest importance.

  9. A Combined Density Functional Theory and Monte Carlo Study of Manganites for Magnetic Refrigeration

    NASA Astrophysics Data System (ADS)

    Korotana, Romi; Mallia, Giuseppe; Gercsi, Zsolt; Harrison, Nicholas

    2015-03-01

    Perovskite oxides are considered to be strong candidates for applications in magnetic refrigeration technology, due to their remarkable properties, in addition to low processing costs. Manganites with the general formula R1-xAxMnO3, particularly for A=Ca and 0 . 2 < x < 0 . 5 , undergo a field driven transition from a paramagnetic to ferromagnetic state, which is accompanied by changes in the lattice and electronic structure. Therefore, one may anticipate a large entropy change across the phase transition due to the first order nature. The present work aims to achieve an understanding of the relevant structural, magnetic, and electronic entropy contributions in the doped compound La0.75Ca0.25MnO3. A combination of thermodynamics and first principles theory is applied to determine individual contributions to the total entropy change of the system. Hybrid-exchange density functional (B3LYP) calculations for La0.75Ca0.25MnO3 predict an anti-Jahn-Teller polaron in the localised hole state, which is influenced by long-range cooperative Jahn-Teller distortions. Through the analysis of individual entropy contributions, it is identified that the electronic and vibrational terms have a deleterious effect on the total entropy change.

  10. Exploring the chemical kinetics of partially oxidized intermediates by combining experiments, theory, and kinetic modeling.

    PubMed

    Hoyermann, Karlheinz; Mauß, Fabian; Olzmann, Matthias; Welz, Oliver; Zeuch, Thomas

    2017-07-19

    Partially oxidized intermediates play a central role in combustion and atmospheric chemistry. In this perspective, we focus on the chemical kinetics of alkoxy radicals, peroxy radicals, and Criegee intermediates, which are key species in both combustion and atmospheric environments. These reactive intermediates feature a broad spectrum of chemical diversity. Their reactivity is central to our understanding of how volatile organic compounds are degraded in the atmosphere and converted into secondary organic aerosol. Moreover, they sensitively determine ignition timing in internal combustion engines. The intention of this perspective article is to provide the reader with information about the general mechanisms of reactions initiated by addition of atomic and molecular oxygen to alkyl radicals and ozone to alkenes. We will focus on critical branching points in the subsequent reaction mechanisms and discuss them from a consistent point of view. As a first example of our integrated approach, we will show how experiment, theory, and kinetic modeling have been successfully combined in the first infrared detection of Criegee intermediates during the gas phase ozonolysis. As a second example, we will examine the ignition timing of n-heptane/air mixtures at low and intermediate temperatures. Here, we present a reduced, fuel size independent kinetic model of the complex chemistry initiated by peroxy radicals that has been successfully applied to simulate standard n-heptane combustion experiments.

  11. Combined Molecular Dynamics Simulation-Molecular-Thermodynamic Theory Framework for Predicting Surface Tensions.

    PubMed

    Sresht, Vishnu; Lewandowski, Eric P; Blankschtein, Daniel; Jusufi, Arben

    2017-08-22

    A molecular modeling approach is presented with a focus on quantitative predictions of the surface tension of aqueous surfactant solutions. The approach combines classical Molecular Dynamics (MD) simulations with a molecular-thermodynamic theory (MTT) [ Y. J. Nikas, S. Puvvada, D. Blankschtein, Langmuir 1992 , 8 , 2680 ]. The MD component is used to calculate thermodynamic and molecular parameters that are needed in the MTT model to determine the surface tension isotherm. The MD/MTT approach provides the important link between the surfactant bulk concentration, the experimental control parameter, and the surfactant surface concentration, the MD control parameter. We demonstrate the capability of the MD/MTT modeling approach on nonionic alkyl polyethylene glycol surfactants at the air-water interface and observe reasonable agreement of the predicted surface tensions and the experimental surface tension data over a wide range of surfactant concentrations below the critical micelle concentration. Our modeling approach can be extended to ionic surfactants and their mixtures with both ionic and nonionic surfactants at liquid-liquid interfaces.

  12. Theory of mind deficits in patients with esophageal cancer combined with depression.

    PubMed

    Cao, Yin; Zhao, Quan-Di; Hu, Li-Jun; Sun, Zhi-Qin; Sun, Su-Ping; Yun, Wen-Wei; Yuan, Yong-Gui

    2013-05-21

    To characterize the two components of theory of mind (ToM) in patients with esophageal cancer combined with depression. Sixty-five patients with esophageal cancer combined with depression (depressed group) and 62 normal controls (control group) were assessed using reading the mind in the eyes test, faux pas task, verbal fluency test, digit span test and WAIS IQ test. The depressed group was divided into two subgroups including psychotic depressed (PD) group (32 cases) and nonpsychotic depressed (NPD) group (33 cases). The clinical symptoms of patients were assessed using Beck depression inventory version II and brief psychiatric reacting scale (BPRS). There was a significant difference between the depressed group and the control group on tasks involving ToM social perceptual components (mind reading: t = 7.39, P < 0.01) and tests involving ToM social cognitive components (faux pas questions: t = 13.75, P < 0.01), respectively. A significant difference was also found among the PD group, the NPD group and the control group on mind reading (F = 32.98, P < 0.01) and faux pas questions (χ² = 78.15, P < 0.01), respectively. The PD group and NPD group performed worse than normal group controls both on mind reading and faux pas questions (P < 0.05). The PD group performed significantly worse than the NPD group on tasks involving ToM (mind reading: F = 18.99, P < 0.01; faux pas questions: F = 36.01, P < 0.01). In the depressed group, there was a negative correlation between ToM performances and BPRS total score (mind reading: r = -0.35, P < 0.01; faux pas questions: r = -0.51, P < 0.01), and between ToM performances and hostile suspiciousness factor score (mind reading: r = -0.75, P < 0.01; faux pas questions: r = -0.73, P < 0.01), respectively. The two components of ToM are both impaired in patients with esophageal cancer combined with depression. This indicates that there may be an association between ToM deficits and psychotic symptoms in clinical depression.

  13. Economic theory and nursing administration research--is this a good combination?

    PubMed

    Jones, Terry L; Yoder, Linda

    2010-01-01

    Economic theory is used to describe and explain decision making in the context of scarce resources. This paper presents two applications of economic theory to the delivery of nursing services in acute care hospitals and evaluates its usefulness in guiding nursing administration research. The description of economic theory and the proposed applications for nursing are based on current nursing, healthcare, and economic literature. Evaluation of the potential usefulness of economic theory in guiding nursing administration research is based on the criteria of significance and testability as described by Fawcett and Downs. While economic theory can be very useful in explaining how decisions about nursing time allocation and nursing care production are made, it will not address the issue of how they should be made. Normative theories and ethical frameworks also must be incorporated in the decision-making process around these issues. Economic theory and nursing administration are a good fit when balanced with the values and goals of nursing.

  14. Analysis of surface segregation in polymer mixtures: A combination of mean field and statistical associated fluid theories

    NASA Astrophysics Data System (ADS)

    Krawczyk, Jaroslaw; Croce, Salvatore; Chakrabarti, Buddhapriya; Tasche, Jos

    The surface segregation in polymer mixtures remains a challenging problem for both academic exploration as well as industrial applications. Despite its ubiquity and several theoretical attempts a good agreement between computed and experimentally observed profiles has not yet been achieved. A simple theoretical model proposed in this context by Schmidt and Binder combines Flory-Huggins free energy of mixing with the square gradient theory of wetting of a wall by fluid. While the theory gives us a qualitative understanding of the surface induced segregation and the surface enrichment it lacks the quantitative comparison with the experiment. The statistical associating fluid theory (SAFT) allows us to calculate accurate free energy for a real polymeric materials. In an earlier work we had shown that increasing the bulk modulus of a polymer matrix through which small molecules migrate to the free surface causes reduction in the surface migrant fraction using Schmidt-Binder and self-consistent field theories. In this work we validate this idea by combining mean field theories and SAFT to identify parameter ranges where such an effect should be observable. Department of Molecular Physics, Łódź University of Technology, Żeromskiego 116, 90-924 Łódź, Poland.

  15. Economic Theory and Nursing Administration Research—Is This a Good Combination?

    PubMed Central

    Jones, Terry L.; Yoder, Linda

    2017-01-01

    TOPIC Economic theory is used to describe and explain decision making in the context of scarce resources. PURPOSE This paper presents two applications of economic theory to the delivery of nursing services in acute care hospitals and evaluates its usefulness in guiding nursing administration research. SOURCES OF INFORMATION The description of economic theory and the proposed applications for nursing are based on current nursing, healthcare, and economic literature. Evaluation of the potential usefulness of economic theory in guiding nursing administration research is based on the criteria of significance and testability as described by Fawcett and Downs. CONCLUSIONS While economic theory can be very useful in explaining how decisions about nursing time allocation and nursing care production are made, it will not address the issue of how they should be made. Normative theories and ethical frameworks also must be incorporated in the decision-making process around these issues. Economic theory and nursing administration are a good fit when balanced with the values and goals of nursing. PMID:20137023

  16. Homogeneous droplet nucleation modeled using the gradient theory combined with the PC-SAFT equation of state

    NASA Astrophysics Data System (ADS)

    Planková, Barbora; Hrubý, Jan; Vinš, Václav

    2013-04-01

    In this work, we used the density gradient theory (DGT) combined with the cubic equation of state (EoS) by Peng and Robinson (PR) and the perturbed chain (PC) modification of the SAFT EoS developed by Gross and Sadowski [1]. The PR EoS is based on very simplified physical foundations, it has significant limitations in the accuracy of the predicted thermodynamic properties. On the other hand, the PC-SAFT EoS combines different intermolecular forces, e.g., hydrogen bonding, covalent bonding, Coulombic forces which makes it more accurate in predicting of the physical variables. We continued in our previous works [2,3] by solving the boundary value problem which arose by mathematical solution of the DGT formulation and including the boundary conditions. Achieving the numerical solution was rather tricky; this study describes some of the crucial developments that helped us to overcome the partial problems. The most troublesome were computations for low temperatures where we achieved great improvements compared to [3]. We applied the GT for the n-alkanes: nheptane, n-octane, n-nonane, and n-decane because of the availability of the experimental data. Comparing them with our numerical results, we observed great differences between the theories; the best results gave the combination of the GT and the PC-SAFT. However, a certain temperature drift was observed that is not satisfactorily explained by the present theories.

  17. Examining the Potential of Combining the Methods of Grounded Theory and Narrative Inquiry: A Comparative Analysis

    ERIC Educational Resources Information Center

    Lal, Shalini; Suto, Melinda; Ungar, Michael

    2012-01-01

    Increasingly, qualitative researchers are combining methods, processes, and principles from two or more methodologies over the course of a research study. Critics charge that researchers adopting combined approaches place too little attention on the historical, epistemological, and theoretical aspects of the research design. Rather than…

  18. Capturing static and dynamic correlations by a combination of projected Hartree-Fock and density functional theories.

    PubMed

    Garza, Alejandro J; Jiménez-Hoyos, Carlos A; Scuseria, Gustavo E

    2013-04-07

    This paper explores the possibility of combining projected Hartree-Fock and density functional theories for treating static and dynamic correlations in molecular systems with mean-field computational cost. The combination of spin-projected unrestricted Hartree-Fock (SUHF) with the TPSS correlation functional (SUHF+TPSS) yields excellent results for non-metallic molecular dissociations and singlet-triplet splittings. However, SUHF+TPSS fails to provide the qualitatively correct dissociation curve for the notoriously difficult case of the chromium dimer. By tuning the TPSS correlation parameters and adding complex conjugation symmetry breaking and restoration to SUHF, the right curve shape for Cr2 can be obtained; unfortunately, such a combination is found to lead to overcorrelation in the general case.

  19. Combined quantum mechanics (TDDFT) and classical electrodynamics (Mie theory) methods for calculating surface enhanced Raman and hyper-Raman spectra.

    PubMed

    Mullin, Jonathan; Valley, Nicholas; Blaber, Martin G; Schatz, George C

    2012-09-27

    Multiscale models that combine quantum mechanics and classical electrodynamics are presented, which allow for the evaluation of surface-enhanced Raman (SERS) and hyper-Raman scattering spectra (SEHRS) for both chemical (CHEM) and electrodynamic (EM) enhancement mechanisms. In these models, time-dependent density functional theory (TDDFT) for a system consisting of the adsorbed molecule and a metal cluster fragment of the metal particle is coupled to Mie theory for the metal particle, with the surface of the cluster being overlaid with the surface of the metal particle. In model A, the electromagnetic enhancement from plasmon-excitation of the metal particle is combined with the chemical enhancement associated with a static treatment of the molecule-metal structure to determine overall spectra. In model B, the frequency dependence of the Raman spectrum of the isolated molecule is combined with the enhancements determined in model A to refine the enhancement estimate. An equivalent theory at the level of model A is developed for hyper-Raman spectra calculations. Application to pyridine interacting with a 20 nm diameter silver sphere is presented, including comparisons with an earlier model (denoted G), which combines plasmon enhanced fields with gas-phase Raman (or hyper-Raman) spectra. The EM enhancement factor for spherical particles at 357 nm is found to be 10(4) and 10(6) for SERS and SEHRS, respectively. Including both chemical and electromagnetic mechanisms at the level of model A leads to enhancements on the order of 10(4) and 10(9) for SERS and SEHRS.

  20. Field-Theoretical Approach to Many-Body Perturbation Theory: Combining MBPT and QED

    SciTech Connect

    Lindgren, Ingvar; Salomonson, Sten; Hedendahl, Daniel

    2007-12-26

    Many-Body Perturbation Theory (MBPT) is today highly developed. The electron correlation of atomic and molecular systems can be evaluated to essentially all orders of perturbation theory--also relativistically (RMBPT)--by means of techniques of Coupled-Cluster type. When high accuracy is needed, effects beyond RMBPT will enter, i.e., effects of retarded Breit interaction and of radiative effects (Lamb shift), effects normally referred to as QED effects. These effects can be evaluated by means of special techniques, like S-matrix formulation, which cannot simultaneously treat electron correlation. It would for many applications be desirable to have access to a numerical technique, where effects of electron correlation and of QED could be treated on the same footing. Such a technique is presently being developed and gradually implemented at our laboratory. Some numerical results will be given.

  1. Combining facts and values in environmental impact assessment: Theories and techniques

    SciTech Connect

    Hyman, E.L.; Stiftel, B.; Moreau, D.H.; Nichols, R.C.

    1986-01-01

    This book integrates theories and techniques from a wide range of disciplines in an effort to improve the practice of existing environmental impact assessment methods. The authors discuss benefit-cost analysis; land-suitability analysis; checklists; matrices; and networks; modeling, simulation, and resource management approaches; as well as multiple objective analysis. They also explore common pitfalls and suggest ways to improve the handling of facts and values, risk and uncertainty, and the presentation and communication of findings. The book extends current practices by drawing upon relevant theories and techniques from political science, economics, psychology, and ecology. From this broad, interdisciplinary perspective, the authors discuss and debate various means of estimating how the general public places social and economic value on the environment. To remedy the shortcomings of existing methods, the book concludes by presenting a new method for environmental assessment, including a case study application in land-use watershed management.

  2. Electrocatalysis of borohydride oxidation: a review of density functional theory approach combined with experimental validation

    NASA Astrophysics Data System (ADS)

    Sison Escaño, Mary Clare; Lacdao Arevalo, Ryan; Gyenge, Elod; Kasai, Hideaki

    2014-09-01

    The electrocatalysis of borohydride oxidation is a complex, up-to-eight-electron transfer process, which is essential for development of efficient direct borohydride fuel cells. Here we review the progress achieved by density functional theory (DFT) calculations in explaining the adsorption of BH4- on various catalyst surfaces, with implications for electrocatalyst screening and selection. Wherever possible, we correlate the theoretical predictions with experimental findings, in order to validate the proposed models and to identify potential directions for further advancements.

  3. Combining Nuclear Magnetic Resonance Spectroscopy and Density Functional Theory Calculations to Characterize Carvedilol Polymorphs.

    PubMed

    Rezende, Carlos A; San Gil, Rosane A S; Borré, Leandro B; Pires, José Ricardo; Vaiss, Viviane S; Resende, Jackson A L C; Leitão, Alexandre A; De Alencastro, Ricardo B; Leal, Katia Z

    2016-09-01

    The experiments of carvedilol form II, form III, and hydrate by (13)C and (15)N cross-polarization magic-angle spinning (CP MAS) are reported. The GIPAW (gauge-including projector-augmented wave) method from DFT (density functional theory) calculations was used to simulate (13)C and (15)N chemical shifts. A very good agreement was found for the comparison between the global results of experimental and calculated nuclear magnetic resonance (NMR) chemical shifts for carvedilol polymorphs. This work aims a comprehensive understanding of carvedilol crystalline forms employing solution and solid-state NMR as well as DFT calculations. Copyright © 2016. Published by Elsevier Inc.

  4. Note: Determination of torsional spring constant of atomic force microscopy cantilevers: combining normal spring constant and classical beam theory.

    PubMed

    Álvarez-Asencio, R; Thormann, E; Rutland, M W

    2013-09-01

    A technique has been developed for the calculation of torsional spring constants for AFM cantilevers based on the combination of the normal spring constant and plate/beam theory. It is easy to apply and allow the determination of torsional constants for stiff cantilevers where the thermal power spectrum is difficult to obtain due to the high resonance frequency and low signal/noise ratio. The applicability is shown to be general and this simple approach can thus be used to obtain torsional constants for any beam shaped cantilever.

  5. Equations of state, transport properties, and compositions of argon plasma: combination of self-consistent fluid variation theory and linear response theory.

    PubMed

    Quan, W L; Chen, Q F; Fu, Z J; Sun, X W; Zheng, J; Gu, Y J

    2015-02-01

    A consistent theoretical model that can be applied in a wide range of densities and temperatures is necessary for understanding the variation of a material's properties during compression and heating. Taking argon as an example, we show that the combination of self-consistent fluid variational theory and linear response theory is a promising route for studying warm dense matter. Following this route, the compositions, equations of state, and transport properties of argon plasma are calculated in a wide range of densities (0.001-20 g/cm(3)) and temperatures (5-100 kK). The obtained equations of state and electrical conductivities are found in good agreement with available experimental data. The plasma phase transition of argon is observed at temperatures below 30 kK and density about 2-6g/cm(3). The minimum density for the metallization of argon is found to be about 5.8 g/cm(3), occurring at 30-40 kK. The effects of many-particle correlations and dynamic screening on the electrical conductivity are also discussed through the effective potentials.

  6. Simulations of nanocrystals under pressure: combining electronic enthalpy and linear-scaling density-functional theory.

    PubMed

    Corsini, Niccolò R C; Greco, Andrea; Hine, Nicholas D M; Molteni, Carla; Haynes, Peter D

    2013-08-28

    We present an implementation in a linear-scaling density-functional theory code of an electronic enthalpy method, which has been found to be natural and efficient for the ab initio calculation of finite systems under hydrostatic pressure. Based on a definition of the system volume as that enclosed within an electronic density isosurface [M. Cococcioni, F. Mauri, G. Ceder, and N. Marzari, Phys. Rev. Lett. 94, 145501 (2005)], it supports both geometry optimizations and molecular dynamics simulations. We introduce an approach for calibrating the parameters defining the volume in the context of geometry optimizations and discuss their significance. Results in good agreement with simulations using explicit solvents are obtained, validating our approach. Size-dependent pressure-induced structural transformations and variations in the energy gap of hydrogenated silicon nanocrystals are investigated, including one comparable in size to recent experiments. A detailed analysis of the polyamorphic transformations reveals three types of amorphous structures and their persistence on depressurization is assessed.

  7. Simulations of nanocrystals under pressure: Combining electronic enthalpy and linear-scaling density-functional theory

    SciTech Connect

    Corsini, Niccolò R. C. Greco, Andrea; Haynes, Peter D.; Hine, Nicholas D. M.; Molteni, Carla

    2013-08-28

    We present an implementation in a linear-scaling density-functional theory code of an electronic enthalpy method, which has been found to be natural and efficient for the ab initio calculation of finite systems under hydrostatic pressure. Based on a definition of the system volume as that enclosed within an electronic density isosurface [M. Cococcioni, F. Mauri, G. Ceder, and N. Marzari, Phys. Rev. Lett.94, 145501 (2005)], it supports both geometry optimizations and molecular dynamics simulations. We introduce an approach for calibrating the parameters defining the volume in the context of geometry optimizations and discuss their significance. Results in good agreement with simulations using explicit solvents are obtained, validating our approach. Size-dependent pressure-induced structural transformations and variations in the energy gap of hydrogenated silicon nanocrystals are investigated, including one comparable in size to recent experiments. A detailed analysis of the polyamorphic transformations reveals three types of amorphous structures and their persistence on depressurization is assessed.

  8. Galaxy power spectrum in redshift space: Combining perturbation theory with the halo model

    SciTech Connect

    Okumura, Teppei; Hand, Nick; Seljak, Uros; Vlah, Zvonimir; Desjacques, Vincent

    2015-11-19

    Theoretical modeling of the redshift-space power spectrum of galaxies is crucially important to correctly extract cosmological information from galaxy redshift surveys. The task is complicated by the nonlinear biasing and redshift space distortion (RSD) effects, which change with halo mass, and by the wide distribution of halo masses and their occupations by galaxies. One of the main modeling challenges is the existence of satellite galaxies that have both radial distribution inside the halos and large virial velocities inside halos, a phenomenon known as the Finger-of-God (FoG) effect. We present a model for the redshift-space power spectrum of galaxies in which we decompose a given galaxy sample into central and satellite galaxies and relate different contributions to the power spectrum to 1-halo and 2-halo terms in a halo model. Our primary goal is to ensure that any parameters that we introduce have physically meaningful values, and are not just fitting parameters. For the lowest order 2-halo terms we use the previously developed RSD modeling of halos in the context of distribution function and perturbation theory approach. This term needs to be multiplied by the effect of radial distances and velocities of satellites inside the halo. To this one needs to add the 1-halo terms, which are nonperturbative. We show that the real space 1-halo terms can be modeled as almost constant, with the finite extent of the satellites inside the halo inducing a small k2R2 term over the range of scales of interest, where R is related to the size of the halo given by its halo mass. Furthermore, we adopt a similar model for FoG in redshift space, ensuring that FoG velocity dispersion is related to the halo mass. For FoG k2 type expansions do not work over the range of scales of interest and FoG resummation must be used instead. We test several simple damping functions to model the velocity dispersion FoG effect. Applying the formalism to mock

  9. Galaxy power spectrum in redshift space: Combining perturbation theory with the halo model

    DOE PAGES

    Okumura, Teppei; Hand, Nick; Seljak, Uros; ...

    2015-11-19

    Theoretical modeling of the redshift-space power spectrum of galaxies is crucially important to correctly extract cosmological information from galaxy redshift surveys. The task is complicated by the nonlinear biasing and redshift space distortion (RSD) effects, which change with halo mass, and by the wide distribution of halo masses and their occupations by galaxies. One of the main modeling challenges is the existence of satellite galaxies that have both radial distribution inside the halos and large virial velocities inside halos, a phenomenon known as the Finger-of-God (FoG) effect. We present a model for the redshift-space power spectrum of galaxies in whichmore » we decompose a given galaxy sample into central and satellite galaxies and relate different contributions to the power spectrum to 1-halo and 2-halo terms in a halo model. Our primary goal is to ensure that any parameters that we introduce have physically meaningful values, and are not just fitting parameters. For the lowest order 2-halo terms we use the previously developed RSD modeling of halos in the context of distribution function and perturbation theory approach. This term needs to be multiplied by the effect of radial distances and velocities of satellites inside the halo. To this one needs to add the 1-halo terms, which are nonperturbative. We show that the real space 1-halo terms can be modeled as almost constant, with the finite extent of the satellites inside the halo inducing a small k2R2 term over the range of scales of interest, where R is related to the size of the halo given by its halo mass. Furthermore, we adopt a similar model for FoG in redshift space, ensuring that FoG velocity dispersion is related to the halo mass. For FoG k2 type expansions do not work over the range of scales of interest and FoG resummation must be used instead. We test several simple damping functions to model the velocity dispersion FoG effect. Applying the formalism to mock galaxies modeled after the

  10. Galaxy power spectrum in redshift space: Combining perturbation theory with the halo model

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

    Theoretical modeling of the redshift-space power spectrum of galaxies is crucially important to correctly extract cosmological information from galaxy redshift surveys. The task is complicated by the nonlinear biasing and redshift space distortion (RSD) effects, which change with halo mass, and by the wide distribution of halo masses and their occupations by galaxies. One of the main modeling challenges is the existence of satellite galaxies that have both radial distribution inside the halos and large virial velocities inside halos, a phenomenon known as the Finger-of-God (FoG) effect. We present a model for the redshift-space power spectrum of galaxies in which we decompose a given galaxy sample into central and satellite galaxies and relate different contributions to the power spectrum to 1-halo and 2-halo terms in a halo model. Our primary goal is to ensure that any parameters that we introduce have physically meaningful values, and are not just fitting parameters. For the lowest order 2-halo terms we use the previously developed RSD modeling of halos in the context of distribution function and perturbation theory approach. This term needs to be multiplied by the effect of radial distances and velocities of satellites inside the halo. To this one needs to add the 1-halo terms, which are nonperturbative. We show that the real space 1-halo terms can be modeled as almost constant, with the finite extent of the satellites inside the halo inducing a small k2R2 term over the range of scales of interest, where R is related to the size of the halo given by its halo mass. We adopt a similar model for FoG in redshift space, ensuring that FoG velocity dispersion is related to the halo mass. For FoG k2 type expansions do not work over the range of scales of interest and FoG resummation must be used instead. We test several simple damping functions to model the velocity dispersion FoG effect. Applying the formalism to mock galaxies modeled after the "CMASS" sample of the

  11. Combining experiment and theory to elucidate the role of supercritical water in sulfide decomposition.

    PubMed

    Kida, Yuko; Class, Caleb A; Concepcion, Anthony J; Timko, Michael T; Green, William H

    2014-05-28

    The cleavage of C-S linkages plays a key role in fuel processing and organic geochemistry. Water is known to affect these processes, and several hypotheses have been proposed, but the mechanism has been elusive. Here we use both experiment and theory to demonstrate that supercritical water reacts with intermediates formed during alkyl sulfide decomposition. During hexyl sulfide decomposition in supercritical water, pentane and CO + CO2 were detected in addition to the expected six carbon products. A multi-step reaction sequence for hexyl sulfide reacting with supercritical water is proposed which explains the surprising products, and quantum chemical calculations provide quantitative rates that support the proposed mechanism. The key sequence is cleavage of one C-S bond to form a thioaldehyde via radical reactions, followed by a pericyclic addition of water to the C[double bond, length as m-dash]S bond to form a geminal mercaptoalcohol. The mercaptoalcohol decomposes into an aldehyde and H2S either directly or via a water-catalyzed 6-membered ring transition state. The aldehyde quickly decomposes into CO plus pentane by radical reactions. The time is ripe for quantitative modelling of organosulfur reaction kinetics based on modern quantum chemistry.

  12. Spectral-spatial classification combined with diffusion theory based inverse modeling of hyperspectral images

    NASA Astrophysics Data System (ADS)

    Paluchowski, Lukasz A.; Bjorgan, Asgeir; Nordgaard, Hâvard B.; Randeberg, Lise L.

    2016-02-01

    Hyperspectral imagery opens a new perspective for biomedical diagnostics and tissue characterization. High spectral resolution can give insight into optical properties of the skin tissue. However, at the same time the amount of collected data represents a challenge when it comes to decomposition into clusters and extraction of useful diagnostic information. In this study spectral-spatial classification and inverse diffusion modeling were employed to hyperspectral images obtained from a porcine burn model using a hyperspectral push-broom camera. The implemented method takes advantage of spatial and spectral information simultaneously, and provides information about the average optical properties within each cluster. The implemented algorithm allows mapping spectral and spatial heterogeneity of the burn injury as well as dynamic changes of spectral properties within the burn area. The combination of statistical and physics informed tools allowed for initial separation of different burn wounds and further detailed characterization of the injuries in short post-injury time.

  13. Combined aerodynamic and structural dynamic problem emulating routines (CASPER): Theory and implementation

    NASA Technical Reports Server (NTRS)

    Jones, William H.

    1985-01-01

    The Combined Aerodynamic and Structural Dynamic Problem Emulating Routines (CASPER) is a collection of data-base modification computer routines that can be used to simulate Navier-Stokes flow through realistic, time-varying internal flow fields. The Navier-Stokes equation used involves calculations in all three dimensions and retains all viscous terms. The only term neglected in the current implementation is gravitation. The solution approach is of an interative, time-marching nature. Calculations are based on Lagrangian aerodynamic elements (aeroelements). It is assumed that the relationships between a particular aeroelement and its five nearest neighbor aeroelements are sufficient to make a valid simulation of Navier-Stokes flow on a small scale and that the collection of all small-scale simulations makes a valid simulation of a large-scale flow. In keeping with these assumptions, it must be noted that CASPER produces an imitation or simulation of Navier-Stokes flow rather than a strict numerical solution of the Navier-Stokes equation. CASPER is written to operate under the Parallel, Asynchronous Executive (PAX), which is described in a separate report.

  14. Theory of combined photoassociation and Feshbach resonances in a Bose-Einstein condensate

    SciTech Connect

    Mackie, Matt; DeBrosse, Catherine

    2010-04-15

    We model combined photoassociation and Feshbach resonances in a Bose-Einstein condensate, where the shared dissociation continuum allows for quantum interference in losses from the condensate, as well as a dispersive-like shift of resonance. A seemingly oversimplified model is revisited, explaining it as based on the limit of weakly bound molecules, reinforcing it with a comparison to numerical experiments that explicitly include dissociation to noncondensate modes, comparing it against the unitarity limit on condensate losses, and lastly, checking its universal implications. In particular, for a resonant laser and an off-resonant magnetic field, these numerical experiments reveal a rate limit on condensate losses that is larger for smaller condensate densities, approaches the rate limit for magnetoassociation alone near the Feshbach resonance, and agrees best with the analytical model for low density. Comparing the analytical rate limit against the unitary limit, which is set by the size of the condensate, agreement is found only for a limited range of near-resonant magnetic fields. Finally, for a resonant magnetic field and an off-resonant laser, the analytical shift of the Feshbach resonance is found to depend on the size of the Feshbach molecule, signifying nonuniversal physics in a strongly interacting system.

  15. Combined Heat Transfer in High-Porosity High-Temperature Fibrous Insulations: Theory and Experimental Validation

    NASA Technical Reports Server (NTRS)

    Daryabeigi, Kamran; Cunnington, George R.; Miller, Steve D.; Knutson, Jeffry R.

    2010-01-01

    Combined radiation and conduction heat transfer through various high-temperature, high-porosity, unbonded (loose) fibrous insulations was modeled based on first principles. The diffusion approximation was used for modeling the radiation component of heat transfer in the optically thick insulations. The relevant parameters needed for the heat transfer model were derived from experimental data. Semi-empirical formulations were used to model the solid conduction contribution of heat transfer in fibrous insulations with the relevant parameters inferred from thermal conductivity measurements at cryogenic temperatures in a vacuum. The specific extinction coefficient for radiation heat transfer was obtained from high-temperature steady-state thermal measurements with large temperature gradients maintained across the sample thickness in a vacuum. Standard gas conduction modeling was used in the heat transfer formulation. This heat transfer modeling methodology was applied to silica, two types of alumina, and a zirconia-based fibrous insulation, and to a variation of opacified fibrous insulation (OFI). OFI is a class of insulations manufactured by embedding efficient ceramic opacifiers in various unbonded fibrous insulations to significantly attenuate the radiation component of heat transfer. The heat transfer modeling methodology was validated by comparison with more rigorous analytical solutions and with standard thermal conductivity measurements. The validated heat transfer model is applicable to various densities of these high-porosity insulations as long as the fiber properties are the same (index of refraction, size distribution, orientation, and length). Furthermore, the heat transfer data for these insulations can be obtained at any static pressure in any working gas environment without the need to perform tests in various gases at various pressures.

  16. Combination of uncertainty theories and decision-aiding methods for natural risk management in a context of imperfect information

    NASA Astrophysics Data System (ADS)

    Tacnet, Jean-Marc; Dupouy, Guillaume; Carladous, Simon; Dezert, Jean; Batton-Hubert, Mireille

    2017-04-01

    In mountain areas, natural phenomena such as snow avalanches, debris-flows and rock-falls, put people and objects at risk with sometimes dramatic consequences. Risk is classically considered as a combination of hazard, the combination of the intensity and frequency of the phenomenon, and vulnerability which corresponds to the consequences of the phenomenon on exposed people and material assets. Risk management consists in identifying the risk level as well as choosing the best strategies for risk prevention, i.e. mitigation. In the context of natural phenomena in mountainous areas, technical and scientific knowledge is often lacking. Risk management decisions are therefore based on imperfect information. This information comes from more or less reliable sources ranging from historical data, expert assessments, numerical simulations etc. Finally, risk management decisions are the result of complex knowledge management and reasoning processes. Tracing the information and propagating information quality from data acquisition to decisions are therefore important steps in the decision-making process. One major goal today is therefore to assist decision-making while considering the availability, quality and reliability of information content and sources. A global integrated framework is proposed to improve the risk management process in a context of information imperfection provided by more or less reliable sources: uncertainty as well as imprecision, inconsistency and incompleteness are considered. Several methods are used and associated in an original way: sequential decision context description, development of specific multi-criteria decision-making methods, imperfection propagation in numerical modeling and information fusion. This framework not only assists in decision-making but also traces the process and evaluates the impact of information quality on decision-making. We focus and present two main developments. The first one relates to uncertainty and imprecision

  17. Van der Waals interactions in density functional theory by combining the quantum harmonic oscillator-model with localized Wannier functions.

    PubMed

    Silvestrelli, Pier Luigi

    2013-08-07

    We present a new scheme to include the van der Waals (vdW) interactions in approximated Density Functional Theory (DFT) by combining the quantum harmonic oscillator model with the maximally localized Wannier function technique. With respect to the recently developed DFT/vdW-WF2 method, also based on Wannier Functions, the new approach is more general, being no longer restricted to the case of well separated interacting fragments. Moreover, it includes higher than pairwise energy contributions, coming from the dipole-dipole coupling among quantum oscillators. The method is successfully applied to the popular S22 molecular database, and also to extended systems, namely graphite and H2 adsorbed on the Cu(111) metal surface (in this case metal screening effects are taken into account). The results are also compared with those obtained by other vdW-corrected DFT schemes.

  18. Electronic correlation without double counting via a combination of spin projected Hartree-Fock and density functional theories

    SciTech Connect

    Garza, Alejandro J.; Jiménez-Hoyos, Carlos A.; Scuseria, Gustavo E.

    2014-06-28

    Several schemes to avoid the double counting of correlations in methods that merge multireference wavefunctions with density functional theory (DFT) are studied and here adapted to a combination of spin-projected Hartree-Fock (SUHF) and DFT. The advantages and limitations of the new method, denoted SUHF+f{sub c}DFT, are explored through calculations on benchmark sets in which the accounting of correlations is challenging for pure SUHF or DFT. It is shown that SUHF+f{sub c}DFT can greatly improve the description of certain molecular properties (e.g., singlet-triplet energy gaps) which are not improved by simple addition of DFT dynamical correlation to SUHF. However, SUHF+f{sub c}DFT is also shown to have difficulties dissociating certain types of bonds and describing highly charged ions with static correlation. Possible improvements to the current SUHF+f{sub c}DFT scheme are discussed in light of these results.

  19. Combining theory and experiment for X-ray absorption spectroscopy and resonant X-ray scattering characterization of polymers

    SciTech Connect

    Su, Gregory M.; Cordova, Isvar A.; Brady, Michael A.; Prendergast, David; Wang, Cheng

    2016-07-04

    We present that an improved understanding of fundamental chemistry, electronic structure, morphology, and dynamics in polymers and soft materials requires advanced characterization techniques that are amenable to in situ and operando studies. Soft X-ray methods are especially useful in their ability to non-destructively provide information on specific materials or chemical moieties. Analysis of these experiments, which can be very dependent on X-ray energy and polarization, can quickly become complex. Complementary modeling and predictive capabilities are required to properly probe these critical features. Here, we present relevant background on this emerging suite of techniques. Finally, we focus on how the combination of theory and experiment has been applied and can be further developed to drive our understanding of how these methods probe relevant chemistry, structure, and dynamics in soft materials.

  20. Multilayer graphene nanostructure separate CO2/CH4 mixture: Combining molecular simulations with ideal adsorbed solution theory

    NASA Astrophysics Data System (ADS)

    Cheng, Huiyuan; Lei, Guangping

    2016-09-01

    The molecular simulations (Grand canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulations) combined with ideal adsorbed solution theory (IAST) are adopted to investigate the adsorption of CO2, CH4 and their mixture in multilayer graphene nanostructure. The effects of pressure, temperature and pre-adsorbed water on the separation behaviors are examined. The IAST accurately predict the loading of two species, but it has a slight deviation for the selectivity predictions. It is beneficial to the CO2/CH4 mixture separation by reducing temperature or pre-adsorbing some water. Due to additional adsorbate-H2O interactions, the diffusivities of two species drop down as the pre-adsorbed water content increases.

  1. BiFeO3 Domain Wall Energies and Structures: A Combined Experimental and Density Functional Theory+U Study

    NASA Astrophysics Data System (ADS)

    Wang, Yi; Nelson, Chris; Melville, Alexander; Winchester, Benjamin; Shang, Shunli; Liu, Zi-Kui; Schlom, Darrell G.; Pan, Xiaoqing; Chen, Long-Qing

    2013-06-01

    We determined the atomic structures and energies of 109°, 180°, and 71° domain walls in BiFeO3, combining density functional theory+U calculations and aberration-corrected transmission electron microscopy images. We find a substantial Bi sublattice shift and a rather uniform Fe sublattice across the walls. The calculated wall energies (γ) follow the sequence γ109<γ180<γ71 for the 109°, 180°, and 71° walls. We attribute the high 71° wall energy to an opposite tilting rotation of the oxygen octahedra and the low 109° wall energy to the opposite twisting rotation of the oxygen octahedra across the domain walls.

  2. Brillouin-zone integration scheme for many-body density of states: Tetrahedron method combined with cluster perturbation theory

    NASA Astrophysics Data System (ADS)

    Seki, K.; Yunoki, S.

    2016-06-01

    By combining the tetrahedron method with the cluster perturbation theory (CPT), we present an accurate method to numerically calculate the density of states of interacting fermions without introducing the Lorentzian broadening parameter η or the numerical extrapolation of η →0 . The method is conceptually based on the notion of the effective single-particle Hamiltonian which can be subtracted in the Lehmann representation of the single-particle Green's function within the CPT. Indeed, we show the general correspondence between the self-energy and the effective single-particle Hamiltonian which describes exactly the single-particle excitation energies of interacting fermions. The detailed formalism is provided for two-dimensional multiorbital systems and a benchmark calculation is performed for the two-dimensional single-band Hubbard model. The method can be adapted straightforwardly to symmetry-broken states, three-dimensional systems, and finite-temperature calculations.

  3. Kinetic theory of ligand recombination of myoglobin: a model for a combination of entropic and enthalpic effects

    NASA Astrophysics Data System (ADS)

    Yang, Dah-Yen; Sheu, Wen-Shyan; Sheu, Sheh-Yi; Lin, S. H.

    A kinetic theory of ligand recombination of myoglobin is obtained through a microscopic model. The macroscopic time dependent rate constant is obtained by the first passage time distribution random walk method. When the ligand is outside the haem pocket, it diffuses in a continuum space. In this process, this rate corresponds to a Smoluchowski rate constant times the concentration of myoglobin. After penetrating through the hydration shell, the ligand waits in front of the gate or diffuses on the myoglobin surface for entering the gate. This waiting time refers to a large scale fluctuation of protein to open the gate. When the ligand is inside the pocket, the motion of the ligand ranges from a ballistic to a diffusive limit. To cover the whole range of friction, it is necessary to solve exactly a finite area random walk model with periodic gating in one- and two-dimensional finite lattices with slippery boundary conditions. Protein dynamics influence the ligand motion indirectly through the collision between the ligand and the heme pocket well. The first step corresponds to an adiabatic dissociation process. A branching diagram method is used to show a detailed pathway analysis of the adiabaticity by introducing intermediate states in the quintet states for the CO ligand binding. The rate theories of ligand recombination of myoglobin are a combination of entropic and enthalpic effects.

  4. Optimal control of open quantum systems: a combined surrogate hamiltonian optimal control theory approach applied to photochemistry on surfaces.

    PubMed

    Asplund, Erik; Klüner, Thorsten

    2012-03-28

    In this paper, control of open quantum systems with emphasis on the control of surface photochemical reactions is presented. A quantum system in a condensed phase undergoes strong dissipative processes. From a theoretical viewpoint, it is important to model such processes in a rigorous way. In this work, the description of open quantum systems is realized within the surrogate hamiltonian approach [R. Baer and R. Kosloff, J. Chem. Phys. 106, 8862 (1997)]. An efficient and accurate method to find control fields is optimal control theory (OCT) [W. Zhu, J. Botina, and H. Rabitz, J. Chem. Phys. 108, 1953 (1998); Y. Ohtsuki, G. Turinici, and H. Rabitz, J. Chem. Phys. 120, 5509 (2004)]. To gain control of open quantum systems, the surrogate hamiltonian approach and OCT, with time-dependent targets, are combined. Three open quantum systems are investigated by the combined method, a harmonic oscillator immersed in an ohmic bath, CO adsorbed on a platinum surface, and NO adsorbed on a nickel oxide surface. Throughout this paper, atomic units, i.e., ℏ = m(e) = e = a(0) = 1, have been used unless otherwise stated.

  5. Phase transition analysis of V-shaped liquid crystal: Combined temperature-dependent FTIR and density functional theory approach.

    PubMed

    Singh, Swapnil; Singh, Harshita; Karthick, T; Tandon, Poonam; Prasad, Veena

    2018-01-05

    Temperature-dependent Fourier transform infrared spectroscopy (FTIR) combined with density functional theory (DFT) is employed to study the mechanism of phase transitions of V-shaped bent-core liquid crystal. Since it has a large number of flexible bonds, one-dimensional potential energy scan (PES) was performed on the flexible bonds and predicted the most stable conformer I. A detailed analysis of vibrational normal modes of conformer I have been done on the basis of potential energy distribution. The good agreement between the calculated spectrum of conformer I and observed FTIR spectrum at room temperature validates our theoretical structure model. Furthermore, the prominent changes observed in the stretching vibrational bands of CH3/CH2, CO, ring CC, ring CO, ring CH in-plane bending, and ring CH out-of-plane bending at Iso→nematic phase transition (at 155°C) have been illustrated. However, the minor changes in the spectral features observed for the other phase transitions might be due to the shape or bulkiness of molecules. Combined FTIR and PES study beautifully explained the dynamics of the molecules, molecular realignment, H-bonding, and conformational changes at the phase transitions. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Optimal control of open quantum systems: A combined surrogate Hamiltonian optimal control theory approach applied to photochemistry on surfaces

    SciTech Connect

    Asplund, Erik; Kluener, Thorsten

    2012-03-28

    In this paper, control of open quantum systems with emphasis on the control of surface photochemical reactions is presented. A quantum system in a condensed phase undergoes strong dissipative processes. From a theoretical viewpoint, it is important to model such processes in a rigorous way. In this work, the description of open quantum systems is realized within the surrogate Hamiltonian approach [R. Baer and R. Kosloff, J. Chem. Phys. 106, 8862 (1997)]. An efficient and accurate method to find control fields is optimal control theory (OCT) [W. Zhu, J. Botina, and H. Rabitz, J. Chem. Phys. 108, 1953 (1998); Y. Ohtsuki, G. Turinici, and H. Rabitz, J. Chem. Phys. 120, 5509 (2004)]. To gain control of open quantum systems, the surrogate Hamiltonian approach and OCT, with time-dependent targets, are combined. Three open quantum systems are investigated by the combined method, a harmonic oscillator immersed in an ohmic bath, CO adsorbed on a platinum surface, and NO adsorbed on a nickel oxide surface. Throughout this paper, atomic units, i.e., ({Dirac_h}/2{pi})=m{sub e}=e=a{sub 0}= 1, have been used unless otherwise stated.

  7. Effective charges of ionic liquid determined self-consistently through combination of molecular dynamics simulation and density-functional theory.

    PubMed

    Ishizuka, Ryosuke; Matubayasi, Nobuyuki

    2017-07-18

    A self-consistent scheme combining the molecular dynamics (MD) simulation and density functional theory (DFT) was recently proposed to incorporate the effects of the charge transfer and polarization of ions into non-poralizable force fields of ionic liquids for improved description of energetics and dynamics. The purpose of the present work is to analyze the detailed setups of the MD/DFT scheme by focusing on how the basis set, exchange-correlation (XC) functional, charge-fitting method or force field for the intramolecular and Lennard-Jones interactions affects the MD/DFT results of 1,3-dimethylimidazolium bis(trifluoromethylsulfonyl) imide ( [C1mim][NTf2]) and 1-ethyl-3-methylimidazolium glycinate ( [C2mim][Gly]). It was found that the double-zeta valence polarized or larger size of basis set is required for the convergence of the effective charge of the ion. The choice of the XC functional was further not influential as far as the generalized gradient approximation is used. The charge-fitting method and force field govern the accuracy of the MD/DFT scheme, on the other hand. We examined the charge-fitting methods of Blöchl, the iterative Hirshfeld (Hirshfeld-I), and REPEAT in combination with Lopes et al.'s force field and general AMBER force field. There is no single combination of charge fitting and force field that provides good agreements with the experiments, while the MD/DFT scheme reduces the effective charges of the ions and leads to better description of energetics and dynamics compared to the original force field with unit charges. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  8. Learning from doing: the case for combining normalisation process theory and participatory learning and action research methodology for primary healthcare implementation research.

    PubMed

    de Brún, Tomas; O'Reilly-de Brún, Mary; O'Donnell, Catherine A; MacFarlane, Anne

    2016-08-03

    The implementation of research findings is not a straightforward matter. There are substantive and recognised gaps in the process of translating research findings into practice and policy. In order to overcome some of these translational difficulties, a number of strategies have been proposed for researchers. These include greater use of theoretical approaches in research focused on implementation, and use of a wider range of research methods appropriate to policy questions and the wider social context in which they are placed. However, questions remain about how to combine theory and method in implementation research. In this paper, we respond to these proposals. Focussing on a contemporary social theory, Normalisation Process Theory, and a participatory research methodology, Participatory Learning and Action, we discuss the potential of their combined use for implementation research. We note ways in which Normalisation Process Theory and Participatory Learning and Action are congruent and may therefore be used as heuristic devices to explore, better understand and support implementation. We also provide examples of their use in our own research programme about community involvement in primary healthcare. Normalisation Process Theory alone has, to date, offered useful explanations for the success or otherwise of implementation projects post-implementation. We argue that Normalisation Process Theory can also be used to prospectively support implementation journeys. Furthermore, Normalisation Process Theory and Participatory Learning and Action can be used together so that interventions to support implementation work are devised and enacted with the expertise of key stakeholders. We propose that the specific combination of this theory and methodology possesses the potential, because of their combined heuristic force, to offer a more effective means of supporting implementation projects than either one might do on its own, and of providing deeper understandings of

  9. Combination of molecular dynamics method and 3D-RISM theory for conformational sampling of large flexible molecules in solution.

    PubMed

    Miyata, Tatsuhiko; Hirata, Fumio

    2008-04-30

    We have developed an algorithm for sampling the conformational space of large flexible molecules in solution, which combines the molecular dynamics (MD) method and the three-dimensional reference interaction site model (3D-RISM) theory. The solvent-induced force acting on solute atoms was evaluated as the gradient of the solvation free energy with respect to the solute-atom coordinates. To enhance the computation speed, we have applied a multiple timestep algorithm based on the RESPA (Reversible System Propagator Algorithm) to the combined MD/3D-RISM method. By virtue of the algorithm, one can choose a longer timestep for renewing the solvent-induced force compared with that of the conformational update. To illustrate the present MD/3D-RISM simulation, we applied the method to a model of acetylacetone in aqueous solution. The multiple timestep algorithm succeeded in enhancing the computation speed by 3.4 times for this model case. Acetylacetone possesses an intramolecular hydrogen-bonding capability between the hydroxyl group and the carbonyl oxygen atom, and the molecule is significantly stabilized due to this hydrogen bond, especially in gas phase. The intramolecular hydrogen bond was kept intact during almost entire course of the MD simulation in gas phase, while in the aqueous solutions the bond is disrupted in a significant number of conformations. This result qualitatively agrees with the behavior on a free energy barrier lying upon the process for rotating a torsional degree of freedom of the hydroxyl group, where it is significantly reduced in aqueous solution by a cancellation between the electrostatic interaction and the solvation free energy.

  10. Combined Computational Approach Based on Density Functional Theory and Artificial Neural Networks for Predicting The Solubility Parameters of Fullerenes.

    PubMed

    Perea, J Darío; Langner, Stefan; Salvador, Michael; Kontos, Janos; Jarvas, Gabor; Winkler, Florian; Machui, Florian; Görling, Andreas; Dallos, Andras; Ameri, Tayebeh; Brabec, Christoph J

    2016-05-19

    The solubility of organic semiconductors in environmentally benign solvents is an important prerequisite for the widespread adoption of organic electronic appliances. Solubility can be determined by considering the cohesive forces in a liquid via Hansen solubility parameters (HSP). We report a numerical approach to determine the HSP of fullerenes using a mathematical tool based on artificial neural networks (ANN). ANN transforms the molecular surface charge density distribution (σ-profile) as determined by density functional theory (DFT) calculations within the framework of a continuum solvation model into solubility parameters. We validate our model with experimentally determined HSP of the fullerenes C60, PC61BM, bisPC61BM, ICMA, ICBA, and PC71BM and through comparison with previously reported molecular dynamics calculations. Most excitingly, the ANN is able to correctly predict the dispersive contributions to the solubility parameters of the fullerenes although no explicit information on the van der Waals forces is present in the σ-profile. The presented theoretical DFT calculation in combination with the ANN mathematical tool can be easily extended to other π-conjugated, electronic material classes and offers a fast and reliable toolbox for future pathways that may include the design of green ink formulations for solution-processed optoelectronic devices.

  11. CO adsorption on W(100) during temperature-programmed desorption: A combined density functional theory and kinetic Monte Carlo study

    NASA Astrophysics Data System (ADS)

    Albao, Marvin A.; Padama, Allan Abraham B.

    2017-02-01

    Using a combined density functional theory (DFT) and kinetic Monte Carlo (KMC) simulations, we study the adsorption at 800 K and subsequent desorption of CO on W(100) at higher temperatures. The resulting TPD profiles are known experimentally to exhibit three desorption peaks β1, β2, and β3 at 930 K, 1070 K, and 1375 K, respectively. Unlike more recent theoretical studies that propose that all three aforementioned peaks are molecularly rather than associatively desorbed, our KMC analyses are in support of the latter, since at 800 K dissociation is facile and that CO exists as dissociation fragments C and O. We show that these peaks arise from desorption from the same adsorption site but whose binding energy varies depending on local environment, that is, the presence of CO as well as dissociation fragments C and O nearby. Furthermore we show that several key parameters, such as desorption, dissociation and recombination barriers all play a key role in the TPD spectra-these parameter effectively controls not only the location of the TPD peaks but the shape and width of the desorption peaks as well. Moreover, our KMC simulations reveal that varying the heating rate shifts the peaks but leaves their shape intact.

  12. Combining transition state theory with quasiclassical trajectory calculations. III. Applications to the three-dimensional H + H 2(ν) reaction

    NASA Astrophysics Data System (ADS)

    Frost, Robert J.; Smith, Ian W. M.

    1987-11-01

    A new method is described of using quasiclassical trajectories to study the dynamics of elementary reactions in three dimensions. Trajectories are initiated in the phase space of suitably chosen transition state and run forwards and backwards in time from the same starting point to simulate a complete collision. The transition state for a given vibrational level ν is determined by first finding pods (periodic orbiting dividing surfaces) on fixed-angle potential energy surfaces for which the action over one cycle of the pods motion is (ν + 1/2) h. The complete transition is then defined by joining these pods together. Methods are described for pseudo-randomly sampling the phase space of these transition states. Results for collisions of H + H 2(ν) with ν = 0-5 and 9 on the accurate Liu-Siegbahn-Truhlar-Horowitz surface are presented and compared with the results of conventional quasiclassical trajectory studies that have already been reported in the literature. Absolute values of rate constants are obtained using the adiabatic reactive sudden version of the transition state theory. Comparisons of our combined method with conventional techniques are encouraging and there is a considerable saving in computer time resulting from the elimination of trajectories which do not reach the strong interaction zone. Only slight differences are found when the energy of the transition state bending motion is set equal to its zero-point quantum value rather than selected from a classical Boltzmann distribution.

  13. Combining transition state theory with quasiclassical trajectory calculations: application to the nitrogen exchange reaction N+N 2( v)

    NASA Astrophysics Data System (ADS)

    Frost, Robert J.; Smith, Ian W. M.

    1987-10-01

    The dynamics of collisions between N atoms and vibrationally excited N 2( v⩽ 15) have been studied using a new method in which quasiclassical trajectories are initiated at suitably chosen transition states. The transition state for a particular vibrational level v is determined by first finding PODSs (periodic orbiting dividing surfaces) on fixed-angle potential energy surfaces for which the action over one cycle of the PODS motion is ( v+ 1/2) h. The complete transition state is defined by joining these PODSs together and its phase space is sampled pseudorandomly to select starting points for quasiclassical trajectories. The results of the calculations are compared with those from conventional quasiclassical trajectory calculations on the same LEPS potential energy surface, using the adiabatic reactive sudden version of transition state theory to estimate absolute rate constants from our results. The agreement is good and the combined method brings about a great saving in computing time by eliminating trajectories which do not reach the strong interaction zone.

  14. Predicting adherence to combination antiretroviral therapy for HIV in Tanzania: A test of an extended theory of planned behaviour model.

    PubMed

    Banas, Kasia; Lyimo, Ramsey A; Hospers, Harm J; van der Ven, Andre; de Bruin, Marijn

    2017-02-13

    Combination antiretroviral therapy (cART) for HIV is widely available in sub-Saharan Africa. Adherence is crucial to successful treatment. This study aimed to apply an extended theory of planned behaviour (TPB) model to predict objectively measured adherence to cART in Tanzania. Prospective observational study (n = 158) where patients completed questionnaires on demographics (Month 0), socio-cognitive variables including intentions (Month 1), and action planning and self-regulatory processes hypothesised to mediate the intention-behaviour relationship (Month 3), to predict adherence (Month 5). Taking adherence was measured objectively using the Medication Events Monitoring System (MEMS) caps. Model tests were conducted using regression and bootstrap mediation analyses. Perceived behavioural control (PBC) was positively (β = .767, p < .001, R(2) = 57.5%) associated with adherence intentions. Intentions only exercised an indirect effect on adherence (B = 1.29 [0.297-3.15]) through self-regulatory processes (B = 1.10 [0.131-2.87]). Self-regulatory processes (β = .234, p = .010, R(2) = 14.7%) predicted better adherence. This observational study using an objective behavioural measure, identified PBC as the main driver of adherence intentions. The effect of intentions on adherence was only indirect through self-regulatory processes, which were the main predictor of objectively assessed adherence.

  15. Combined local-density and dynamical mean field theory calculations for the compressed lanthanides Ce, Pr, and Nd

    SciTech Connect

    McMahan, A K

    2005-03-30

    This paper reports calculations for compressed Ce (4f{sup 1}), Pr (4f{sup 2}), and Nd (4f{sup 3}) using a combination of the local-density approximation (LDA) and dynamical mean field theory (DMFT), or LDA+DMFT. The 4f moment, spectra, and the total energy among other properties are examined as functions of volume and atomic number for an assumed face-centered cubic (fcc) structure. These materials are seen to be strongly localized at ambient pressure and for compressions up through the experimentally observed fcc phases ({gamma} phase for Ce), in the sense of having fully formed Hund's rules moments and little 4f spectral weight at the Fermi level. Subsequent compression for all three lanthanides brings about significant deviation of the moments from their Hund's rules values, a growing Kondo resonance at the fermi level, an associated softening in the total energy, and quenching of the spin orbit since the Kondo resonance is of mixed spin-orbit character while the lower Hubbard band is predominantly j = 5/2. while the most dramatic changes for Ce occur within the two-phase region of the {gamma}-{alpha} volume collapse transition, as found in earlier work, those for Pr and Nd occur within the volume range of the experimentally observed distorted fcc (dfcc) phase, which is therefore seen here as transitional and not part of the localized trivalent lanthanide sequence. The experimentally observed collapse to the {alpha}-U structure in Pr occurs only on further compression, and no such collapse is found in Nd. These lanthanides start closer to the localized limit for increasing atomic number, and so the theoretical signatures noted above are also offset to smaller volume as well, which is possibly related to the measured systematics of the size of the volume collapse being 15%, 9%, and none for Ce, Pr, and Nd, respectively.

  16. Combining Stress and Dopamine Based Models of Addiction: Towards a Psycho-Neuro-Endocrinological Theory of Addiction.

    PubMed

    Johnston, James H; Linden, David E J; van den Bree, Marianne B M

    2016-01-01

    The literature on the two main models of addiction (dopamine-based positive reinforcement and stress-based negative reinforcement models) have made many important contributions to understanding this brain disorder. However, rarely has there been a comprehensive critique of the limitations of both models. This article seeks to resolve theoretical issues inherent to each model, as well as propose a more comprehensive psycho-neuro-endocrinological theory of addiction which reconciles important elements of both. We suggest that there is not only direct interaction of dopaminergic and stress systems throughout the addiction cycle, from initial use, via the abusing stage, to the endpoint of addiction, but that this interaction is present prior to initial use. A combination of genetic factors and/or experiences of adversity may result in a stress-triggered sensitisation of dopaminergic networks which is present before the onset of substance use, which cannot be explained solely in terms of dopaminergic (positive) reinforcement. Rather these processes are best explained by an allostatic model which reconciles aspects of both models of addiction and shows how dopamine/stress interactions become increasingly pathological in the addiction cycle. Our model suggests that chronic stress eventually creates baseline hypodopaminergic activity, but also prompts dopaminergic hyperactivity in cue reactivity. This is the neural marker of allostatic mechanisms observed at endpoint addiction. We propose a multi-circuit explanation of how this cumulative effect of stress increasingly impacts on dopaminergic networks of reward, affect, attention, memory and behavioural control. This revised model provides a useful frame of reference for further research and ultimately clinical practice.

  17. Combined social cognitive and neurocognitive rehabilitation strategies in schizophrenia: neuropsychological and psychopathological influences on Theory of Mind improvement.

    PubMed

    Bechi, M; Bosia, M; Spangaro, M; Buonocore, M; Cocchi, F; Pigoni, A; Piantanida, M; Guglielmino, C; Bianchi, L; Smeraldi, E; Cavallaro, R

    2015-11-01

    Neurocognitive and social cognitive impairments represent important treatment targets in schizophrenia, as they are significant predictors of functional outcome. Different rehabilitative interventions have recently been developed, addressing both cognitive and psychosocial domains. Although promising, results are still heterogeneous and predictors of treatment outcome are not yet identified. In this study we evaluated the efficacy of two newly developed social cognitive interventions, respectively based on the use of videotaped material and comic strips, combined with domain-specific Cognitive Remediation Therapy (CRT). We also analysed possible predictors of training outcome, including basal neurocognitive performance, the degree of cognitive improvement after CRT and psychopathological variables. Seventy-five patients with schizophrenia treated with CRT, were randomly assigned to: social cognitive training (SCT) group, Theory of Mind Intervention (ToMI) group, and active control group (ACG). ANOVAs showed that SCT and ToMI groups improved significantly in ToM measures, whereas the ACG did not. We reported no influences of neuropsychological measures and improvement after CRT on changes in ToM. Both paranoid and non-paranoid subjects improved significantly after ToMI and SCT, without differences between groups, despite the better performance in basal ToM found among paranoid patients. In the ACG only non-paranoid patients showed an improvement in non-verbal ToM. Results showed that both ToMI and SCT are effective in improving ToM in schizophrenia with no influence of neuropsychological domains. Our data also suggest that paranoid symptoms may discriminate between different types of ToM difficulties in schizophrenia.

  18. Development of an equation of state for electrolyte solutions by combining the statistical associating fluid theory and the mean spherical approximation for the nonprimitive model.

    PubMed

    Zhao, Honggang; dos Ramos, M Carolina; McCabe, Clare

    2007-06-28

    A statistical associating fluid theory to model electrolyte fluids that explicitly accounts for solvent molecules by modeling water as a dipolar square-well associating fluid is presented. Specifically the statistical associating fluid theory for potentials of variable range (SAFT-VR) is combined with integral equation theory and the generalized mean spherical approximation using the nonprimitive model to describe the long-range ion-ion, ion-dipole, and dipole-dipole interactions. Isothermal-isobaric ensemble Monte Carlo simulations have been performed in order to test the new theoretical approach. In particular, simulations are performed for different ion concentrations and different ratios of the cation, anion, and solvent segment diameters. Predictions for the thermodynamic properties from the new equation of state are compared with the computer simulation data. Additionally, results from a combination of the SAFT-VR approach with Debye-Huckel theory and the primitive model are also presented and compared to those obtained with the nonprimitive model to illustrate the advantages of the new statistical associating fluid theory for potentials of variable range plus dipole and electrolytes (SAFT-VR+DE) approach. The results show that the proposed equation of state provides a good description of the PVT properties of electrolyte fluids with different sizes of ions and solvent.

  19. Analysis of the spin Hall effect in CuIr alloys: Combined approach of density functional theory and Hartree-Fock approximation

    SciTech Connect

    Xu, Zhuo Gu, Bo; Mori, Michiyasu; Maekawa, Sadamichi; Ziman, Timothy

    2015-05-07

    We analyze the spin Hall effect in CuIr alloys in theory by the combined approach of the density functional theory (DFT) and Hartree-Fock (HF) approximation. The spin Hall angle (SHA) is obtained to be negative without the local correlation effects. After including the local correlation effects of the 5d orbitals of Ir impurities, the SHA becomes positive with realistic correlation parameters and consistent with experiment [Niimi et al., Phys. Rev. Lett. 106, 126601 (2011)]. Moreover, our analysis shows that the DFT + HF approach is a convenient and general method to study the influence of local correlation effects on the spin Hall effect.

  20. An online study combining the constructs from the theory of planned behaviour and protection motivation theory in predicting intention to test for chlamydia in two testing contexts.

    PubMed

    Powell, Rachael; Pattison, Helen M; Francis, Jill J

    2016-01-01

    Chlamydia is a common sexually transmitted infection that has potentially serious consequences unless detected and treated early. The health service in the UK offers clinic-based testing for chlamydia but uptake is low. Identifying the predictors of testing behaviours may inform interventions to increase uptake. Self-tests for chlamydia may facilitate testing and treatment in people who avoid clinic-based testing. Self-testing and being tested by a health care professional (HCP) involve two contrasting contexts that may influence testing behaviour. However, little is known about how predictors of behaviour differ as a function of context. In this study, theoretical models of behaviour were used to assess factors that may predict intention to test in two different contexts: self-testing and being tested by a HCP. Individuals searching for or reading about chlamydia testing online were recruited using Google Adwords. Participants completed an online questionnaire that addressed previous testing behaviour and measured constructs of the Theory of Planned Behaviour and Protection Motivation Theory, which propose a total of eight possible predictors of intention. The questionnaire was completed by 310 participants. Sufficient data for multiple regression were provided by 102 and 118 respondents for self-testing and testing by a HCP respectively. Intention to self-test was predicted by vulnerability and self-efficacy, with a trend-level effect for response efficacy. Intention to be tested by a HCP was predicted by vulnerability, attitude and subjective norm. Thus, intentions to carry out two testing behaviours with very similar goals can have different predictors depending on test context. We conclude that interventions to increase self-testing should be based on evidence specifically related to test context.

  1. Combining Vision with Voice: A Learning and Implementation Structure Promoting Teachers' Internalization of Practices Based on Self-Determination Theory

    ERIC Educational Resources Information Center

    Assor, Avi; Kaplan, Haya; Feinberg, Ofra; Tal, Karen

    2009-01-01

    We propose that self-determination theory's conceptualization of internalization may help school reformers overcome the recurrent problem of "the predictable failure of educational reform" (Sarason, 1993). Accordingly, we present a detailed learning and implementation structure to promote teachers' internalization and application of ideas and…

  2. Combining Vision with Voice: A Learning and Implementation Structure Promoting Teachers' Internalization of Practices Based on Self-Determination Theory

    ERIC Educational Resources Information Center

    Assor, Avi; Kaplan, Haya; Feinberg, Ofra; Tal, Karen

    2009-01-01

    We propose that self-determination theory's conceptualization of internalization may help school reformers overcome the recurrent problem of "the predictable failure of educational reform" (Sarason, 1993). Accordingly, we present a detailed learning and implementation structure to promote teachers' internalization and application of ideas and…

  3. Combined density functional/polarizable continuum model study of magnetochiral birefringence: Can theory and experiment be brought to agreement?

    NASA Astrophysics Data System (ADS)

    Jansík, Branislav; Rizzo, Antonio; Frediani, Luca; Ruud, Kenneth; Coriani, Sonia

    2006-12-01

    The magnetic-field-induced axial birefringence (magnetochirality) of five closed-shell chiral molecules (three substituted oxiranes, carvone, and limonene) is studied at the density functional theory level using Becke's 3-parameter Lee-Yang-Parr functional and frequency-dependent quadratic response theory. The influence of the environment and the conformational distribution on the property is also studied. The environment effects are described by the polarizable continuum model in its integral-equation formulation. The effect of the conformational distribution is investigated by performing calculations on several conformers—for carvone and limonene—followed by Boltzmann averaging. The calculated values for the magnetochiral birefringence are compared to previous ab initio results and experimental data where available. The refined model presented here brings the ab initio values closer to experiment. Still, disagreements remain in some cases and it appears difficult to resolve these discrepancies.

  4. Combined density functional/polarizable continuum model study of magnetochiral birefringence: can theory and experiment be brought to agreement?

    PubMed

    Jansík, Branislav; Rizzo, Antonio; Frediani, Luca; Ruud, Kenneth; Coriani, Sonia

    2006-12-21

    The magnetic-field-induced axial birefringence (magnetochirality) of five closed-shell chiral molecules (three substituted oxiranes, carvone, and limonene) is studied at the density functional theory level using Becke's 3-parameter Lee-Yang-Parr functional and frequency-dependent quadratic response theory. The influence of the environment and the conformational distribution on the property is also studied. The environment effects are described by the polarizable continuum model in its integral-equation formulation. The effect of the conformational distribution is investigated by performing calculations on several conformers-for carvone and limonene-followed by Boltzmann averaging. The calculated values for the magnetochiral birefringence are compared to previous ab initio results and experimental data where available. The refined model presented here brings the ab initio values closer to experiment. Still, disagreements remain in some cases and it appears difficult to resolve these discrepancies.

  5. [Variable selection methods combined with local linear embedding theory used for optimization of near infrared spectral quantitative models].

    PubMed

    Hao, Yong; Sun, Xu-Dong; Yang, Qiang

    2012-12-01

    Variables selection strategy combined with local linear embedding (LLE) was introduced for the analysis of complex samples by using near infrared spectroscopy (NIRS). Three methods include Monte Carlo uninformation variable elimination (MCUVE), successive projections algorithm (SPA) and MCUVE connected with SPA were used for eliminating redundancy spectral variables. Partial least squares regression (PLSR) and LLE-PLSR were used for modeling complex samples. The results shown that MCUVE can both extract effective informative variables and improve the precision of models. Compared with PLSR models, LLE-PLSR models can achieve more accurate analysis results. MCUVE combined with LLE-PLSR is an effective modeling method for NIRS quantitative analysis.

  6. First time combination of frozen density embedding theory with the algebraic diagrammatic construction scheme for the polarization propagator of second order

    NASA Astrophysics Data System (ADS)

    Prager, Stefan; Zech, Alexander; Aquilante, Francesco; Dreuw, Andreas; Wesolowski, Tomasz A.

    2016-05-01

    The combination of Frozen Density Embedding Theory (FDET) and the Algebraic Diagrammatic Construction (ADC) scheme for the polarization propagator for describing environmental effects on electronically excited states is presented. Two different ways of interfacing and expressing the so-called embedding operator are introduced. The resulting excited states are compared with supermolecular calculations of the total system at the ADC(2) level of theory. Molecular test systems were chosen to investigate molecule-environment interactions of varying strength from dispersion interaction up to multiple hydrogen bonds. The overall difference between the supermolecular and the FDE-ADC calculations in excitation energies is lower than 0.09 eV (max) and 0.032 eV in average, which is well below the intrinsic error of the ADC(2) method itself.

  7. Combination of poroelasticity theory and constant strain rate test in modelling land subsidence due to groundwater extraction

    NASA Astrophysics Data System (ADS)

    Pham, Tien Hung; Rühaak, Wolfram; Sass, Ingo

    2017-04-01

    Extensive groundwater extraction leads to a drawdown of the ground water table. Consequently, soil effective stress increases and can cause land subsidence. Analysis of land subsidence generally requires a numerical model based on poroelasticity theory, which was first proposed by Biot (1941). In the review of regional land subsidence accompanying groundwater extraction, Galloway and Burbey (2011) stated that more research and application is needed in coupling of stress-dependent land subsidence process. In geotechnical field, the constant rate of strain tests (CRS) was first introduced in 1969 (Smith and Wahls 1969) and was standardized in 1982 through the designation D4186-82 by American Society for Testing and Materials. From the reading values of CRS tests, the stress-dependent parameters of poroelasticity model can be calculated. So far, there is no research to link poroelasticity theory with CRS tests in modelling land subsidence due to groundwater extraction. One dimensional CRS tests using conventional compression cell and three dimension CRS tests using Rowe cell were performed. The tests were also modelled by using finite element method with mixed elements. Back analysis technique is used to find the suitable values of hydraulic conductivity and bulk modulus that depend on the stress or void ratio. Finally, the obtained results are used in land subsidence models. Biot, M. A. (1941). "General theory of three-dimensional consolidation." Journal of applied physics 12(2): 155-164. Galloway, D. L. and T. J. Burbey (2011). "Review: Regional land subsidence accompanying groundwater extraction." Hydrogeology Journal 19(8): 1459-1486. Smith, R. E. and H. E. Wahls (1969). "Consolidation under constant rates of strain." Journal of Soil Mechanics & Foundations Div.

  8. Canonical variational transition state theory for a radical combination reaction on ab initio potential energy surfaces: H+CH3

    NASA Astrophysics Data System (ADS)

    LeBlanc, James F.; Pacey, Philip D.

    1985-11-01

    Canonical variational transition state theory calculations have been performed for the reaction H+CH3→CH4 on potential energy surfaces based on ab initio calculations. Most vibrations were treated as harmonic. The resulting energy levels and partition functions were compared to empirical rules. For the two rotational degrees of freedom (χ) of CH3 which become bending vibrations in CH4, changing from a harmonic oscillator treatment to a hindered rotor treatment changed the partition functions by an order of magnitude or more for C ṡ ṡ ṡ H distances, R, greater than 0.3 nm. The variation of potential energy with R was taken as a standard Morse function, as a stiff Morse function with a variable parameter β or as a Lippincott function. The value of R for which the rate was minimum was found to vary between 0.25 and 0.5 nm, depending on the temperature and the assumed variation of potential energy with R and χ. Provided the χ bending modes were treated as hindered rotations for large values of R, the limiting values of the rate coefficients were similar to the results of experiments, of classical trajectory calculations, and of a modified version of simple collision theory.

  9. Long-range Coulomb interactions in surface systems: a first-principles description within self-consistently combined GW and dynamical mean-field theory.

    PubMed

    Hansmann, P; Ayral, T; Vaugier, L; Werner, P; Biermann, S

    2013-04-19

    Systems of adatoms on semiconductor surfaces display competing ground states and exotic spectral properties typical of two-dimensional correlated electron materials which are dominated by a complex interplay of spin and charge degrees of freedom. We report a fully ab initio derivation of low-energy Hamiltonians for the adatom systems Si(111):X, with X=Sn, Si, C, Pb, that we solve within self-consistently combined GW and dynamical mean-field theory. Calculated photoemission spectra are in agreement with available experimental data. We rationalize experimentally observed trends from Mott physics toward charge ordering along the series as resulting from substantial long-range interactions.

  10. Dynamical quantum-electrodynamics embedding: combining time-dependent density functional theory and the near-field method.

    PubMed

    Gao, Yi; Neuhauser, Daniel

    2012-08-21

    We develop an approach for dynamical (ω > 0) embedding of mixed quantum mechanical (QM)/classical (or more precisely QM/electrodynamics) systems with a quantum sub-region, described by time-dependent density functional theory (TDDFT), within a classical sub-region, modeled here by the recently proposed near-field (NF) method. Both sub-systems are propagated simultaneously and are coupled through a common Coulomb potential. As a first step we implement the method to study the plasmonic response of a metal film which is half jellium-like QM and half classical. The resulting response is in good agreement with both full-scale TDDFT and the purely classical NF method. The embedding method is able to describe the optical response of the whole system while capturing quantum mechanical effects, so it is a promising approach for studying electrodynamics in hybrid molecules-metals nanostructures.

  11. A new method for sperm characterization for infertility treatment: hypothesis testing by using combination of watershed segmentation and graph theory.

    PubMed

    Shojaedini, Seyed Vahab; Heydari, Masoud

    2014-10-01

    Shape and movement features of sperms are important parameters for infertility study and treatment. In this article, a new method is introduced for characterization sperms in microscopic videos. In this method, first a hypothesis framework is defined to distinguish sperms from other particles in captured video. Then decision about each hypothesis is done in following steps: Selecting some primary regions as candidates for sperms by watershed-based segmentation, pruning of some false candidates during successive frames using graph theory concept and finally confirming correct sperms by using their movement trajectories. Performance of the proposed method is evaluated on real captured images belongs to semen with high density of sperms. The obtained results show the proposed method may detect 97% of sperms in presence of 5% false detections and track 91% of moving sperms. Furthermore, it can be shown that better characterization of sperms in proposed algorithm doesn't lead to extracting more false sperms compared to some present approaches.

  12. Combining theory and experiment for X-ray absorption spectroscopy and resonant X-ray scattering characterization of polymers

    DOE PAGES

    Su, Gregory M.; Cordova, Isvar A.; Brady, Michael A.; ...

    2016-07-04

    We present that an improved understanding of fundamental chemistry, electronic structure, morphology, and dynamics in polymers and soft materials requires advanced characterization techniques that are amenable to in situ and operando studies. Soft X-ray methods are especially useful in their ability to non-destructively provide information on specific materials or chemical moieties. Analysis of these experiments, which can be very dependent on X-ray energy and polarization, can quickly become complex. Complementary modeling and predictive capabilities are required to properly probe these critical features. Here, we present relevant background on this emerging suite of techniques. Finally, we focus on how the combinationmore » of theory and experiment has been applied and can be further developed to drive our understanding of how these methods probe relevant chemistry, structure, and dynamics in soft materials.« less

  13. A hybrid method for predicting the microstructure of polymers with complex architecture: combination of single-chain simulation with density functional theory.

    PubMed

    Cao, Dapeng; Jiang, Tao; Wu, Jianzhong

    2006-04-28

    A hybrid method is proposed to investigate the microstructure of various polymeric fluids confined between two parallel surfaces. The hybrid method combines a single-chain Monte Carlo (MC) simulation for the ideal-gas part of the Helmholtz energy and a density functional theory (DFT) for the excess part that arises from nonbonded intersegment interactions. The latter consists of a modified fundamental measure theory for excluded-volume effect, the first-order thermodynamics perturbation theory for chain connectivity, and a mean-field approximation for the van der Waals attraction. In comparison with a conventional DFT, the hybrid method avoids calculation of the time-consuming recursive functions and is directly applicable to polymers with arbitrary molecular architecture. Its numerical performance has been validated by extensive comparisons with MC data for the density distributions of totally flexible, semiflexible, or rigid polymers and those with starlike architecture. Special attention is also given to the formation of a nematic monolayer by rigid molecules laying perpendicular to a planar surface. The hybrid method predicts the surface pressure versus surface coverage in good agreement with experiment.

  14. Aerodynamic characteristics of wings designed with a combined-theory method to cruise at a Mach number of 4.5

    NASA Technical Reports Server (NTRS)

    Mack, Robert J.

    1988-01-01

    A wind-tunnel study was conducted to determine the capability of a method combining linear theory and shock-expansion theory to design optimum camber surfaces for wings that will fly at high-supersonic/low-hypersonic speeds. Three force models (a flat-plate reference wing and two cambered and twisted wings) were used to obtain aerodynamic lift, drag, and pitching-moment data. A fourth pressure-orifice model was used to obtain surface-pressure data. All four wing models had the same planform, airfoil section, and centerbody area distribution. The design Mach number was 4.5, but data were also obtained at Mach numbers of 3.5 and 4.0. Results of these tests indicated that the use of airfoil thickness as a theoretical optimum, camber-surface design constraint did not improve the aerodynamic efficiency or performance of a wing as compared with a wing that was designed with a zero-thickness airfoil (linear-theory) constraint.

  15. Study of collective radial breathing-like modes in double-walled carbon nanotubes: combination of continuous two-dimensional membrane theory and Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Levshov, Dmitry I.; Avramenko, Marina V.; Than, Xuan-Tinh; Michel, Thierry; Arenal, Raul; Paillet, Matthieu; Rybkovskiy, Dmitry V.; Osadchy, Alexander V.; Rochal, Sergei B.; Yuzyuk, Yuri I.; Sauvajol, Jean-Louis

    2016-01-01

    Radial breathing modes (RBMs) are widely used for the atomic structure characterization and index assignment of single-walled carbon nanotubes (SWNTs) from resonant Raman spectroscopy. However, for double-walled carbon nanotubes (DWNTs), the use of conventional ωRBM(d) formulas is complicated due to the van der Waals interaction between the layers, which strongly affects the frequencies of radial modes and leads to new collective vibrations. This paper presents an alternative way to theoretically study the collective radial breathing-like modes (RBLMs) of DWNTs and to account for interlayer interaction, namely the continuous two-dimensional membrane theory. We obtain an analytical ωRBLM(do,di) relation, being the equivalent of the conventional ωRBM(d) expressions, established for SWNTs. We compare our theoretical predictions with Raman data, measured on individual index-identified suspended DWNTs, and find a good agreement between experiment and theory. Moreover, we show that the interlayer coupling in individual DWNTs strongly depends on the interlayer distance, which is manifested in the frequency shifts of the RBLMs with respect to the RBMs of the individual inner and outer tubes. In terms of characterization, this means that the combination of Raman spectroscopy data and predictions of continuous membrane theory may give additional criteria for the index identification of DWNTs, namely the interlayer distance.

  16. Interfacial tension of nonassociating pure substances and binary mixtures by density functional theory combined with Peng-Robinson equation of state

    NASA Astrophysics Data System (ADS)

    Li, Zhidong; Firoozabadi, Abbas

    2009-04-01

    We develop a density functional theory and investigate the interfacial tension of several pure substances N2, CO2, H2S, normal alkanes from C1 to nC10, and binary mixtures C1/C3, C1/nC5, C1/nC7, C1/nC10, CO2/nC4, N2/nC5, N2/nC6, N2/nC8, N2/nC10, nC6/nC7, nC6/nC8, and nC6/nC10. The theory is combined with the semiempirical Peng-Robinson equation of state (PR-EOS). The weighted density approximation (WDA) is adopted to extend the bulk excess Helmholtz free energy to the inhomogeneous interface. Besides, a supplementary term, quadratic density expansion (QDE), is introduced to account for the long-range characteristic of intermolecular dispersion attractions, which cannot be accurately described by the WDA. In the bulk limit, the QDE vanishes and the theory is reduced to the PR-EOS. For pure substances, the potential expansion parameter is the only adjustable parameter in the QDE and determined by using a single measured interfacial tension at the lowest temperature examined. Then without any parameter adjustment, we faithfully predict the interfacial tensions of pure substances and mixtures over a wide range of conditions.

  17. Interfacial tension of nonassociating pure substances and binary mixtures by density functional theory combined with Peng-Robinson equation of state.

    PubMed

    Li, Zhidong; Firoozabadi, Abbas

    2009-04-21

    We develop a density functional theory and investigate the interfacial tension of several pure substances N(2), CO(2), H(2)S, normal alkanes from C(1) to nC(10), and binary mixtures C(1)/C(3), C(1)/nC(5), C(1)/nC(7), C(1)/nC(10), CO(2)/nC(4), N(2)/nC(5), N(2)/nC(6), N(2)/nC(8), N(2)/nC(10), nC(6)/nC(7), nC(6)/nC(8), and nC(6)/nC(10). The theory is combined with the semiempirical Peng-Robinson equation of state (PR-EOS). The weighted density approximation (WDA) is adopted to extend the bulk excess Helmholtz free energy to the inhomogeneous interface. Besides, a supplementary term, quadratic density expansion (QDE), is introduced to account for the long-range characteristic of intermolecular dispersion attractions, which cannot be accurately described by the WDA. In the bulk limit, the QDE vanishes and the theory is reduced to the PR-EOS. For pure substances, the potential expansion parameter is the only adjustable parameter in the QDE and determined by using a single measured interfacial tension at the lowest temperature examined. Then without any parameter adjustment, we faithfully predict the interfacial tensions of pure substances and mixtures over a wide range of conditions.

  18. The combination of perception of other individuals and exogenous manipulation of arousal enhances social facilitation as an aftereffect: re-examination of Zajonc’s drive theory

    PubMed Central

    Ukezono, Masatoshi; Nakashima, Satoshi F.; Sudo, Ryunosuke; Yamazaki, Akira; Takano, Yuji

    2015-01-01

    Zajonc’s drive theory postulates that arousal enhanced through the perception of the presence of other individuals plays a crucial role in social facilitation (Zajonc, 1965). Here, we conducted two experiments to examine whether the elevation of arousal through a stepping exercise performed in front of others as an exogenous factor causes social facilitation of a cognitive task in a condition where the presence of others does not elevate the arousal level. In the main experiment, as an “aftereffect of social stimulus,” we manipulated the presence or absence of others and arousal enhancement before participants conducted the primary cognitive task. The results showed that the strongest social facilitation was induced by the combination of the perception of others and arousal enhancement. In a supplementary experiment, we manipulated these factors by adding the presence of another person during the task. The results showed that the effect of the presence of the other during the primary task is enough on its own to produce facilitation of task performance regardless of the arousal enhancement as an aftereffect of social stimulus. Our study therefore extends the framework of Zajonc’s drive theory in that the combination of the perception of others and enhanced arousal as an “aftereffect” was found to induce social facilitation especially when participants did not experience the presence of others while conducting the primary task. PMID:25999906

  19. The combination of perception of other individuals and exogenous manipulation of arousal enhances social facilitation as an aftereffect: re-examination of Zajonc's drive theory.

    PubMed

    Ukezono, Masatoshi; Nakashima, Satoshi F; Sudo, Ryunosuke; Yamazaki, Akira; Takano, Yuji

    2015-01-01

    Zajonc's drive theory postulates that arousal enhanced through the perception of the presence of other individuals plays a crucial role in social facilitation (Zajonc, 1965). Here, we conducted two experiments to examine whether the elevation of arousal through a stepping exercise performed in front of others as an exogenous factor causes social facilitation of a cognitive task in a condition where the presence of others does not elevate the arousal level. In the main experiment, as an "aftereffect of social stimulus," we manipulated the presence or absence of others and arousal enhancement before participants conducted the primary cognitive task. The results showed that the strongest social facilitation was induced by the combination of the perception of others and arousal enhancement. In a supplementary experiment, we manipulated these factors by adding the presence of another person during the task. The results showed that the effect of the presence of the other during the primary task is enough on its own to produce facilitation of task performance regardless of the arousal enhancement as an aftereffect of social stimulus. Our study therefore extends the framework of Zajonc's drive theory in that the combination of the perception of others and enhanced arousal as an "aftereffect" was found to induce social facilitation especially when participants did not experience the presence of others while conducting the primary task.

  20. Dynamical screening effects in correlated electron materials-a progress report on combined many-body perturbation and dynamical mean field theory: 'GW + DMFT'.

    PubMed

    Biermann, Silke

    2014-04-30

    We give a summary of recent progress in the field of electronic structure calculations for materials with strong electronic Coulomb correlations. The discussion focuses on developments beyond the by now well established combination of density functional and dynamical mean field theory dubbed 'LDA + DMFT'. It is organized around the description of dynamical screening effects in the solid. Indeed, screening in the solid gives rise to dynamical local Coulomb interactions U(ω) (Aryasetiawan et al 2004 Phys. Rev. B 70 195104), and this frequency dependence leads to effects that cannot be neglected in a truly first principles description. We review the recently introduced extension of LDA + DMFT to dynamical local Coulomb interactions 'LDA + U(ω) + DMFT' (Casula et al 2012 Phys. Rev. B 85 035115, Werner et al 2012 Nature Phys. 1745-2481). A reliable description of dynamical screening effects is also a central ingredient of the 'GW + DMFT' scheme (Biermann et al 2003 Phys. Rev. Lett. 90 086402), a combination of many-body perturbation theory in Hedin's GW approximation and dynamical mean field theory. Recently, the first GW + DMFT calculations including dynamical screening effects for real materials have been achieved, with applications to SrV O3 (Tomczak et al 2012 Europhys. Lett. 100 67001, Tomczak et al Phys. Rev. B submitted (available electronically as arXiv:1312.7546)) and adatom systems on surfaces (Hansmann et al 2013 Phys. Rev. Lett. 110 166401). We review these and comment on further perspectives in the field. This review is an attempt to put elements of the original works into the broad perspective of the development of truly first principles techniques for correlated electron materials.

  1. Elementary processes of H2 plasma-graphene interaction: A combined molecular dynamics and density functional theory study

    NASA Astrophysics Data System (ADS)

    Despiau-Pujo, E.; Davydova, A.; Cunge, G.; Delfour, L.; Magaud, L.; Graves, D. B.

    2013-03-01

    Elementary interactions between H atoms and monolayer graphene are investigated using classical molecular dynamics (CMD) and density functional theory (DFT). C-H interatomic potential curves and associated energy barriers are reported depending on the H impact position (top, bridge, hollow, vacancy, or edge sites of graphene nanoribbons). Chemisorption of atomic hydrogen and formation of molecular hydrogen from chemisorbed H states on graphene are examined. The influence of graphene temperature and incident species energy on adsorption, reflection, and penetration mechanisms is also presented. Except for impacts at graphene nanoribbon (GNR) edges or at defect locations, H atoms are shown to experience a repulsive force due to delocalized π-electrons which prevents any species with less than 0.4-0.6 eV to chemisorb on the graphene surface. C-H bond formation requires a local sp2-sp3 rehybridization resulting in structural changes of the graphene sample. Chemisorption sites with deep potential wells and no activation barrier are found on GNR edges, which indicate that H thermal radicals can functionalize GNRs on edges while they cannot do it in the basal plane. The presence of one or more H adsorbates on the graphene surface strongly influences subsequent H adsorption and promotes the formation of energetically favourable H pairs at the para- and ortho-locations. Formation of H2 molecule via Eley-Rideal recombination of hot radicals [1-1.3 eV] with chemisorbed H atoms is observed.

  2. New insights into the tropospheric oxidation of isoprene: combining field measurements, laboratory studies, chemical modelling and quantum theory.

    PubMed

    Whalley, Lisa; Stone, Daniel; Heard, Dwayne

    2014-01-01

    In this chapter we discuss some of the recent work directed at further understanding the chemistry of our atmosphere in regions of low NO x , such as forests, where there are considerable emissions of biogenic volatile organic compounds, for example reactive hydrocarbons such as isoprene. Recent field measurements have revealed some surprising results, for example that OH concentrations are measured to be considerably higher than can be understood using current chemical mechanisms. It has also not proven possible to reconcile field measurements of other species, such as oxygenated VOCs, or emission fluxes of isoprene, using current mechanisms. Several complementary approaches have been brought to bear on formulating a solution to this problem, namely field studies using state-of-the-art instrumentation, chamber studies to isolate sub-sections of the chemistry, laboratory studies to measure rate coefficients, product branching ratios and photochemical yields, the development of ever more detailed chemical mechanisms, and high quality ab initio quantum theory to calculate the energy landscape for relevant reactions and to enable the rates of formation of products and intermediates for previously unknown and unstudied reactions to be predicted. The last few years have seen significant activity in this area, with several contrasting postulates put forward to explain the experimental findings, and here we attempt to synthesise the evidence and ideas.

  3. Free radicals generated during oxidation of green tea polyphenols: electron paramagnetic resonance spectroscopy combined with density functional theory calculations.

    PubMed

    Severino, Joyce Ferreira; Goodman, Bernard A; Kay, Christopher W M; Stolze, Klaus; Tunega, Daniel; Reichenauer, Thomas G; Pirker, Katharina F

    2009-04-15

    Electron paramagnetic resonance spectroscopy and density functional theory calculations have been used to investigate the redox properties of the green tea polyphenols (GTPs) (-)-epigallocatechin gallate (EGCG), (-)-epigallocatechin (EGC), and (-)-epicatechin gallate (ECG). Aqueous extracts of green tea and these individual phenols were autoxidized at alkaline pH and oxidized by superoxide anion (O(2)(-)) radicals in dimethyl sulfoxide. Several new aspects of the free radical chemistry of GTPs were revealed. EGCG can be oxidized on both the B and the D ring. The B ring was the main oxidation site during autoxidation, but the D ring was the preferred site for O(2)(-) oxidation. Oxidation of the D ring was followed by structural degradation, leading to generation of a radical identical to that of oxidized gallic acid. Alkaline autoxidation of green tea extracts produced four radicals that were related to products of the oxidation of EGCG, EGC, ECG, and gallic acid, whereas the spectra from O(2)(-) oxidation could be explained solely by radicals generated from EGCG. Assignments of hyperfine coupling constants were made by DFT calculations, allowing the identities of the radicals observed to be confirmed.

  4. An improved interatomic potential for xenon in UO2: a combined density functional theory/genetic algorithm approach.

    PubMed

    Thompson, Alexander E; Meredig, Bryce; Wolverton, C

    2014-03-12

    We have created an improved xenon interatomic potential for use with existing UO2 potentials. This potential was fit to density functional theory calculations with the Hubbard U correction (DFT + U) using a genetic algorithm approach called iterative potential refinement (IPR). We examine the defect energetics of the IPR-fitted xenon interatomic potential as well as other, previously published xenon potentials. We compare these potentials to DFT + U derived energetics for a series of xenon defects in a variety of incorporation sites (large, intermediate, and small vacant sites). We find the existing xenon potentials overestimate the energy needed to add a xenon atom to a wide set of defect sites representing a range of incorporation sites, including failing to correctly rank the energetics of the small incorporation site defects (xenon in an interstitial and xenon in a uranium site neighboring uranium in an interstitial). These failures are due to problematic descriptions of Xe-O and/or Xe-U interactions of the previous xenon potentials. These failures are corrected by our newly created xenon potential: our IPR-generated potential gives good agreement with DFT + U calculations to which it was not fitted, such as xenon in an interstitial (small incorporation site) and xenon in a double Schottky defect cluster (large incorporation site). Finally, we note that IPR is very flexible and can be applied to a wide variety of potential forms and materials systems, including metals and EAM potentials.

  5. Atomic-scale wear of amorphous hydrogenated carbon during intermittent contact: a combined study using experiment, simulation, and theory.

    PubMed

    Vahdat, Vahid; Ryan, Kathleen E; Keating, Pamela L; Jiang, Yijie; Adiga, Shashishekar P; Schall, J David; Turner, Kevin T; Harrison, Judith A; Carpick, Robert W

    2014-07-22

    In this study, we explore the wear behavior of amplitude modulation atomic force microscopy (AM-AFM, an intermittent-contact AFM mode) tips coated with a common type of diamond-like carbon, amorphous hydrogenated carbon (a-C:H), when scanned against an ultra-nanocrystalline diamond (UNCD) sample both experimentally and through molecular dynamics (MD) simulations. Finite element analysis is utilized in a unique way to create a representative geometry of the tip to be simulated in MD. To conduct consistent and quantitative experiments, we apply a protocol that involves determining the tip-sample interaction geometry, calculating the tip-sample force and normal contact stress over the course of the wear test, and precisely quantifying the wear volume using high-resolution transmission electron microscopy imaging. The results reveal gradual wear of a-C:H with no sign of fracture or plastic deformation. The wear rate of a-C:H is consistent with a reaction-rate-based wear theory, which predicts an exponential dependence of the rate of atom removal on the average normal contact stress. From this, kinetic parameters governing the wear process are estimated. MD simulations of an a-C:H tip, whose radius is comparable to the tip radii used in experiments, making contact with a UNCD sample multiple times exhibit an atomic-level removal process. The atomistic wear events observed in the simulations are correlated with under-coordinated atomic species at the contacting surfaces.

  6. Combining ZHENG Theory and High-Throughput Expression Data to Predict New Effects of Chinese Herbal Formulae

    PubMed Central

    Yu, Shuhao; Guo, Zhizhong; Guan, Yan; Lu, Yi-Yu; Hao, Pei; Li, Yixue; Su, Shi-Bing

    2012-01-01

    ZHENG is the key theory in traditional Chinese medicine (TCM) and it is very important to find the molecular pharmacology of traditional Chinese herbal formulae. One ZHENG is related to many diseases and the herbal formulae are aiming to ZHENG. Therefore, many herbal formulae whose effects on a certain disease have been confirmed might also treat other diseases with the same ZHENG. In this study, the microarrays collected from patients with QiXuXueYu ZHENG (Qi-deficiency and Blood-stasis syndrome) before treatment and after being treated with Fuzheng Huayu Capsule were analyzed by a high-throughput gene microarrays-based drug similarity comparison method, which could find the small molecules which had similar effects with Fuzheng Huayu Capsule. Besides getting the results of anti-inflammatory and anti-fibrosis drugs which embody the known effect of Fuzheng Huayu Capsule, many other small molecules were screened out and could reflect other types of effects of this formula in treating QiXuXueYu ZHENG, including anti-hyperglycemic, anti-hyperlipidemic, hyposenstive effect. Then we integrated this information to display the effect of Fuzheng Huayu Capsule and its potential multiple-target molecular pharmacology. Moreover, through using clinical blood-tested data to verify our prediction, Fuzheng Huayu Capsule was proved to have effects on diabetes and dyslipidemia. PMID:22666299

  7. Using a combined protection motivation theory and health action process approach intervention to promote exercise during pregnancy.

    PubMed

    Gaston, Anca; Prapavessis, Harry

    2014-04-01

    Despite the benefits of exercise during pregnancy, many expectant mothers are inactive. This study examined whether augmenting a protection motivation theory (PMT) intervention with a Health Action Process Approach can enhance exercise behavior change among pregnant women. Sixty inactive pregnant women were randomly assigned to one of three treatment groups: PMT-only, PMT + action-planning, and PMT + action-and-coping-planning. Week-long objective (accelerometer) and subjective (self-report) exercise measures were collected at baseline, and at 1- and 4-weeks post-intervention. Repeated-measures ANOVAs demonstrated that while all participants reported increased exercise from baseline to 1-week post-intervention, participants in both planning groups were significantly more active (p < .001) than those in the PMT-only group by 4-weeks post-intervention (η (2) = .13 and .15 for accelerometer and self-report data, respectively). In conclusion, augmenting a PMT intervention with action or action-and-coping-planning can enhance exercise behavior change in pregnant women.

  8. CO2 migration and sequestration by combined capillary and solubility trapping: theory, experiments, and capacity estimates at the basin scale

    NASA Astrophysics Data System (ADS)

    Juanes, Ruben

    2011-11-01

    The large-scale injection and storage of carbon dioxide (CO2) into deep saline aquifers is a promising tool for reducing atmospheric CO2 emissions to mitigate climate change. Success of geologic sequestration relies on trapping the buoyant CO2, to minimize the risk of leakage into shallower formations through pre- existing wells, fractures or faults. However, traditional reservoir-simulation tools are currently unable to resolve the impact of small-scale trapping processes on fluid flow at the scale of a geologic basin. Here, we formulate a sharp-interface mathematical model for the post-injection migration of a CO2 plume driven by groundwater flow in a sloping aquifer, subject to both capillary trapping and CO2 dissolution by convective mixing. We develop semi-analytical solutions that elucidate the nontrivial interplay between the two trapping mechanisms, and how their synergetic action controls plume migration. We validate the theory by means of laboratory experiments with analogue fluids to study how convective mixing arrests the buoyant current. We use our findings to estimate the dimensionless rate of solubility trapping for several large saline aquifers in the United States, and assess the importance of solubility trapping in practice.

  9. Combining density functional theory calculations, supercomputing, and data-driven methods to design new materials (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Jain, Anubhav

    2017-04-01

    Density functional theory (DFT) simulations solve for the electronic structure of materials starting from the Schrödinger equation. Many case studies have now demonstrated that researchers can often use DFT to design new compounds in the computer (e.g., for batteries, catalysts, and hydrogen storage) before synthesis and characterization in the lab. In this talk, I will focus on how DFT calculations can be executed on large supercomputing resources in order to generate very large data sets on new materials for functional applications. First, I will briefly describe the Materials Project, an effort at LBNL that has virtually characterized over 60,000 materials using DFT and has shared the results with over 17,000 registered users. Next, I will talk about how such data can help discover new materials, describing how preliminary computational screening led to the identification and confirmation of a new family of bulk AMX2 thermoelectric compounds with measured zT reaching 0.8. I will outline future plans for how such data-driven methods can be used to better understand the factors that control thermoelectric behavior, e.g., for the rational design of electronic band structures, in ways that are different from conventional approaches.

  10. Deriving C4 photosynthetic parameters from combined gas exchange and chlorophyll fluorescence using an Excel tool: theory and practice.

    PubMed

    Bellasio, Chandra; Beerling, David J; Griffiths, Howard

    2016-06-01

    The higher photosynthetic potential of C4 plants has led to extensive research over the past 50 years, including C4 -dominated natural biomes, crops such as maize, or for evaluating the transfer of C4 traits into C3 lineages. Photosynthetic gas exchange can be measured in air or in a 2% Oxygen mixture using readily available commercial gas exchange and modulated PSII fluorescence systems. Interpretation of these data, however, requires an understanding (or the development) of various modelling approaches, which limit the use by non-specialists. In this paper we present an accessible summary of the theory behind the analysis and derivation of C4 photosynthetic parameters, and provide a freely available Excel Fitting Tool (EFT), making rigorous C4 data analysis accessible to a broader audience. Outputs include those defining C4 photochemical and biochemical efficiency, the rate of photorespiration, bundle sheath conductance to CO2 diffusion and the in vivo biochemical constants for PEP carboxylase. The EFT compares several methodological variants proposed by different investigators, allowing users to choose the level of complexity required to interpret data. We provide a complete analysis of gas exchange data on maize (as a model C4 organism and key global crop) to illustrate the approaches, their analysis and interpretation. © 2015 John Wiley & Sons Ltd.

  11. Combined Maxwell and kinetic guiding-center theory with polarization drift: Regularized variational formulation with local charge and energy conservation

    NASA Astrophysics Data System (ADS)

    Correa-Restrepo, D.; Pfirsch, D.; Wimmel, H. K.

    1986-06-01

    A formerly derived regularization method is applied to time-dependent Lagrangian guiding-center mechanics, with the polarization drift included. This approach removes the singularity that occurs for B-fields with non-vanishing parallel curl. From the Lagrangian equations of motion, Liouville's theorem and a collisionless kinetic equation for the “regularized guiding centers” are derived. A common Lagrangian density for both the guiding centers and the Maxwell fields is obtained by using a “constrained” Hamiltonian and a formely derived, new variational principle. From this variational formalism local conservation laws for electric charge and energy are derived, together with the correct charge, current, energy and energy flux densities. These densities combined point-like contributions with electric polarization and magnetization terms.

  12. A range-dependent propagation model based on a combination of ray theory and plane-wave reflection coefficients

    NASA Astrophysics Data System (ADS)

    Hovem, Jens M.; Knobles, D. P.

    2002-11-01

    The paper describes a range-dependent propagation model based on a combination of range-dependent ray tracing and plane-wave bottom responses. The ray-tracing module of the model determines all the eigenrays between any source/receiver pairs and stores the ray histories. The received wave field is then synthesized by adding the contributions of all the eigenrays, taking into account the reflections from the bottom and the surface. The model can treat arbitrarily varying bottom topography and a layered elastic bottom as long as the layers are parallel. In the current version, the bottom is modeled with a sedimentary layer over an elastic half space, but more complicated structures are easily implemented. The new model has been tested against other models on several benchmark problems and also applied in the analysis and modeling of up-slope and down-slope propagation data recorded on a 52-element center-tapered array that was deployed at two locations about 70 miles east of Jacksonville, FL. The paper presents the results of these tests with an assessment of the potential use in connection with geo-acoustic inversion of range-dependent and elastic scenarios. [Work supported by Applied Research Laboratories, The University of Texas.

  13. Interfacial instability of amorphous LiPON against lithium: A combined Density Functional Theory and spectroscopic study

    NASA Astrophysics Data System (ADS)

    Sicolo, Sabrina; Fingerle, Mathias; Hausbrand, René; Albe, Karsten

    2017-06-01

    The chemical instability of the glassy solid electrolyte LiPON against metallic lithium and the occurrence of side reactions at their interface is investigated by combining a surface science approach and quantum-mechanical calculations. Using an evolutionary structure search followed by a melt-quenching protocol, a model for the disordered structure of LiPON is generated and put into contact with lithium. Even the static optimization of a simple model interface suggests that the diffusion of lithium into LiPON is driven by a considerable driving force that could easily take place under experimental conditions. Calculated reaction energies indicate that the reduction and decomposition of LiPON is thermodynamically favorable. By monitoring the evolution of the LiPON core levels as a function of lithium exposure, the disruption of the LiPON network alongside the occurrence of new phases is observed. The direct comparison between UV photoelectron spectroscopy measurements and calculated electronic densities of states for increasing stages of lithiation univocally identifies the new phases as Li2O, Li3P and Li3N. These products are stable against Li metal and form a passivation layer which shields the electrolyte from further decomposition while allowing for the diffusion of Li ions.

  14. Combining mass spectrometry diagnostic and density functional theory calculations for a better understanding of the plasma polymerization of ethyl lactate.

    PubMed

    Ligot, S; Guillaume, M; Gerbaux, P; Thiry, D; Renaux, F; Cornil, J; Dubois, P; Snyders, R

    2014-04-17

    The focus of this work is on the growth mechanism of ethyl lactate-based plasma polymer film (ELPPF) that could be used as barrier coatings. In such an application, the ester density of the plasma polymer has to be controlled to tune the degradation rate of the material. Our strategy consists of correlating the plasma chemistry evaluated by RGA mass spectrometry and understanding, via DFT calculations, the chemistry of the synthesized thin films. The theoretical calculations helped us to understand the plasma chemistry in plasma ON and OFF conditions. From these data it is unambiguously shown that the signal m/z 75 can directly be correlated with the precursor density in the plasma phase. The combination of XPS and chemical derivatization experiments reveal that the ester content in the ELPFF can be tailored from 2 to 18 at. % by decreasing the RF power, which is perfectly correlated with the evolution of the plasma chemistry. Our results also highlight that the ELPPF chemistry, especially the ester content, is affected by the plasma mode of operation (continuous or pulsed discharge, at similar injected mean power) for similar ester content in the plasma. This could be related to different energy conditions at the interface of the growing films that could affect the sticking coefficient of the ester-bearing fragments.

  15. An Excel tool for deriving key photosynthetic parameters from combined gas exchange and chlorophyll fluorescence: theory and practice.

    PubMed

    Bellasio, Chandra; Beerling, David J; Griffiths, Howard

    2016-06-01

    Combined photosynthetic gas exchange and modulated fluorometres are widely used to evaluate physiological characteristics associated with phenotypic and genotypic variation, whether in response to genetic manipulation or resource limitation in natural vegetation or crops. After describing relatively simple experimental procedures, we present the theoretical background to the derivation of photosynthetic parameters, and provide a freely available Excel-based fitting tool (EFT) that will be of use to specialists and non-specialists alike. We use data acquired in concurrent variable fluorescence-gas exchange experiments, where A/Ci and light-response curves have been measured under ambient and low oxygen. From these data, the EFT derives light respiration, initial PSII (photosystem II) photochemical yield, initial quantum yield for CO2 fixation, fraction of incident light harvested by PSII, initial quantum yield for electron transport, electron transport rate, rate of photorespiration, stomatal limitation, Rubisco (ribulose 1·5-bisphosphate carboxylase/oxygenase) rate of carboxylation and oxygenation, Rubisco specificity factor, mesophyll conductance to CO2 diffusion, light and CO2 compensation point, Rubisco apparent Michaelis-Menten constant, and Rubisco CO2 -saturated carboxylation rate. As an example, a complete analysis of gas exchange data on tobacco plants is provided. We also discuss potential measurement problems and pitfalls, and suggest how such empirical data could subsequently be used to parameterize predictive photosynthetic models.

  16. Item response theory methods can improve the measurement of physical function by combining the modified health assessment questionnaire and the SF-36 physical function scale.

    PubMed

    Martin, Marie; Kosinski, Mark; Bjorner, Jakob B; Ware, John E; Maclean, Ross; Li, Tracy

    2007-05-01

    To compare the measurement properties of the Modified Health Assessment Questionnaire [MHAQ], the SF-36((R)) Health Survey 10 item Physical Functioning scale [PF10], and scores from an item response theory (IRT) based scale combining the two measures. Rheumatoid arthritis (RA) patients (n = 339) enrolled in a multi-center, randomized, double-blind, placebo-controlled trial completed the MHAQ and the SF-36 pre- and post-treatment. Psychometric analyses used confirmatory factor analysis and IRT models. Analyses of variance were used to assess sensitivity to changes in disease severity (defined by the American College of Rheumatism (ACR)) using change scores in MHAQ, PF10, and IRT scales. Analyses of covariance were used to assess treatment responsiveness. For the entire score range, the 95% confidence interval around individual patient scores was smaller for the combined (total) IRT based scale than for other measures. The MHAQ and PF10 were about 70% and 50% as efficient as the total IRT score of physical functioning in discriminating among ACR groups, respectively. The MHAQ and PF10 were also less efficient than the total IRT score in discriminating among treatment groups. Combining scales from the two short forms yields a more powerful tool with greater sensitivity to treatment response.

  17. Accurate prediction of thermodynamic properties of alkyl peroxides by combining density functional theory calculation with least-square calibration.

    PubMed

    Liu, Cun-Xi; Li, Ze-Rong; Zhou, Chong-Wen; Li, Xiang-Yuan

    2009-05-01

    Owing to the significance in kinetic modeling of the oxidation and combustion mechanisms of hydrocarbons, a fast and relatively accurate method was developed for the prediction of Delta(f)H(298)(o) of alkyl peroxides. By this method, a raw Delta(f)H(298)(o) value was calculated from the optimized geometry and vibration frequencies at B3LYP/6-31G(d,p) level and then an accurate Delta(f)H(298)(o) value was obtained by a least-square procedure. The least-square procedure is a six-parameter linear equation and is validated by a leave-one out technique, giving a cross-validation squared correlation coefficient q(2) of 0.97 and a squared correlation coefficient of 0.98 for the final model. Calculated results demonstrated that the least-square calibration leads to a remarkable reduction of error and to the accurate Delta(f)H(298)(o) values within the chemical accuracy of 8 kJ mol(-1) except (CH(3))(2)CHCH(2)CH(2)CH(2)OOH which has an error of 8.69 kJ mol(-1). Comparison of the results by CBS-Q, CBS-QB3, G2, and G3 revealed that B3LYP/6-31G(d,p) in combination with a least-square calibration is reliable in the accurate prediction of the standard enthalpies of formation for alkyl peroxides. Standard entropies at 298 K and heat capacities in the temperature range of 300-1500 K for alkyl peroxides were also calculated using the rigid rotor-harmonic oscillator approximation.

  18. Effect of Tai Chi Exercise Combined with Mental Imagery Theory in Improving Balance in a Diabetic and Elderly Population

    PubMed Central

    Alsubiheen, Abdulrahman; Petrofsky, Jerrold; Daher, Noha; Lohman, Everett; Balbas, Edward

    2015-01-01

    Background One of the effects of diabetes mellitus (DM), peripheral neuropathy, affects the sensation in the feet and can increase the chance of falling. The purpose of the study was to investigate the effect of 8 weeks of Tai Chi (TC) training combined with mental imagery (MI) on improving balance in people with diabetes and an age matched control group. Material/Methods Seventeen healthy subjects and 12 diabetic sedentary subjects ranging from 40–80 years of age were recruited. All subjects in both groups attended a Yang style of TC class using MI strategies, 2 sessions a week for 8 weeks. Each session was one hour long. Measures were taken using a balance platform test, an Activities-specific Balance Confidence (ABC) Scale, a one leg standing test (OLS), functional reach test (FRT) and hemoglobin A1C. These measures were taken twice, pre and post-study, for both groups. Results Both groups experienced significant improvements in ABC, OLS, FRT (P<0.01) after completing 8 weeks of TC exercise with no significant improvement between groups. Subjects using the balance platform test demonstrated improvement in balance in all different tasks with no significant change between groups. There was no significant change in HbA1C for the diabetic group. Conclusions All results showed an improvement in balance in the diabetic and the control groups; however, no significant difference between the groups was observed. Since the DM group had more problems with balance impairment at baseline than the control, the diabetic group showed the most benefit from the TC exercise. PMID:26454826

  19. Effect of Tai Chi Exercise Combined with Mental Imagery Theory in Improving Balance in a Diabetic and Elderly Population.

    PubMed

    Alsubiheen, Abdulrahman; Petrofsky, Jerrold; Daher, Noha; Lohman, Everett; Balbas, Edward

    2015-10-10

    One of the effects of diabetes mellitus (DM), peripheral neuropathy, affects the sensation in the feet and can increase the chance of falling. The purpose of the study was to investigate the effect of 8 weeks of Tai Chi (TC) training combined with mental imagery (MI) on improving balance in people with diabetes and an age matched control group. Seventeen healthy subjects and 12 diabetic sedentary subjects ranging from 40-80 years of age were recruited. All subjects in both groups attended a Yang style of TC class using MI strategies, 2 sessions a week for 8 weeks. Each session was one hour long. Measures were taken using a balance platform test, an Activities-specific Balance Confidence (ABC) Scale, a one leg standing test (OLS), functional reach test (FRT) and hemoglobin A1C. These measures were taken twice, pre and post-study, for both groups. Both groups experienced significant improvements in ABC, OLS, FRT (P<0.01) after completing 8 weeks of TC exercise with no significant improvement between groups. Subjects using the balance platform test demonstrated improvement in balance in all different tasks with no significant change between groups. There was no significant change in HbA1C for the diabetic group. All results showed an improvement in balance in the diabetic and the control groups; however, no significant difference between the groups was observed. Since the DM group had more problems with balance impairment at baseline than the control, the diabetic group showed the most benefit from the TC exercise.

  20. Predicting pressure-dependent unimolecular rate constants using variational transition state theory with multidimensional tunneling combined with system-specific quantum RRK theory: a definitive test for fluoroform dissociation.

    PubMed

    Bao, Junwei Lucas; Zhang, Xin; Truhlar, Donald G

    2016-06-22

    Understanding the falloff in rate constants of gas-phase unimolecular reaction rate constants as the pressure is lowered is a fundamental problem in chemical kinetics, with practical importance for combustion, atmospheric chemistry, and essentially all gas-phase reaction mechanisms. In the present work, we use our recently developed system-specific quantum RRK theory, calibrated by canonical variational transition state theory with small-curvature tunneling, combined with the Lindemann-Hinshelwood mechanism, to model the dissociation reaction of fluoroform (CHF3), which provides a definitive test for falloff modeling. Our predicted pressure-dependent thermal rate constants are in excellent agreement with experimental values over a wide range of pressures and temperatures. The present validation of our methodology, which is able to include variational transition state effects, multidimensional tunneling based on the directly calculated potential energy surface along the tunneling path, and torsional and other vibrational anharmonicity, together with state-of-the-art reaction-path-based direct dynamics calculations, is important because the method is less empirical than models routinely used for generating full mechanisms, while also being simpler in key respects than full master equation treatments and the full reduced falloff curve and modified strong collision methods of Troe.

  1. Investigation on the neutral and anionic BxAlyH2 (x + y = 7, 8, 9) clusters using density functional theory combined with photoelectron spectroscopy.

    PubMed

    Ding, Li-Ping; Shao, Peng; Lu, Cheng; Zhang, Fang-Hui; Ding, Lei; Yuan, Tao Li

    2016-08-17

    The structure and bonding nature of neutral and negatively charged BxAlyH2 (x + y = 7, 8, 9) clusters are investigated with the aid of previously published experimental photoelectron spectra combined with the present density functional theory calculations. The comparison between the experimental photoelectron spectra and theoretical simulated spectra helps to identify the ground state structures. The accuracy of the obtained ground state structures is further verified by calculating their adiabatic electron affinities and vertical detachment energies and comparing them against available experimental data. The results show that the structures of BxAlyH2 transform from three-dimensional to planar structures as the number of boron atoms increases. Moreover, boron atoms tend to bind together forming Bn units. The hydrogen atoms prefer to bind with boron atoms rather than aluminum atoms. The analyses of the molecular orbital on the ground state structures further support the abovementioned results.

  2. Magnetic exchange interaction in the μ-hydroxo bridged vanadium(IV) dimers: a density functional theory combined with broken-symmetry approach

    NASA Astrophysics Data System (ADS)

    Zhang, Lei; Chen, Zhida

    2001-09-01

    Magnetic exchange interaction for the μ-hydroxo bridged vanadium(IV) dimers is investigated based on calculations of density functional theory combined with the broken-symmetry approach. It is found that there is an exponential correlation between the V-O(hydroxo)-V angle, the V-O(hydroxo) distance and the exchange coupling constants J. Meanwhile, the calculated results reveal that the deprotonation of the bridging hydroxo ligand causes a sharp increase of the exchange coupling interaction, but the magnetic coupling constant J is insensitive to the deprotonation of the bridging aquo ligand. Moreover, simplifying each 1,2-bridging squarate ligand with two -OCH 2 groups almost does not influence magnetic exchange behavior between the two vanadium(IV) ions, and the principle of the shortest superexchange pathway is available for the multiplicity of the bridging ligand in the μ-hydroxo bridged vanadium(IV) dimers.

  3. Reprint of: Combining theory and experiment for X-ray absorption spectroscopy and resonant X-ray scattering characterization of polymers

    SciTech Connect

    Su, GM; Cordova, IA; Brady, MA; Prendergast, D; Wang, C

    2016-05-23

    © 2016. An improved understanding of fundamental chemistry, electronic structure, morphology, and dynamics in polymers and soft materials requires advanced characterization techniques that are amenable to . in situ and . operando studies. Soft X-ray methods are especially useful in their ability to non-destructively provide information on specific materials or chemical moieties. Analysis of these experiments, which can be very dependent on X-ray energy and polarization, can quickly become complex. Complementary modeling and predictive capabilities are required to properly probe these critical features. Here, we present relevant background on this emerging suite of techniques. We focus on how the combination of theory and experiment has been applied and can be further developed to drive our understanding of how these methods probe relevant chemistry, structure, and dynamics in soft materials.

  4. Predicting the Oxygen-Binding Properties of Platinum Nanoparticle Ensembles by Combining High-Precision Electron Microscopy and Density Functional Theory.

    PubMed

    Aarons, Jolyon; Jones, Lewys; Varambhia, Aakash; MacArthur, Katherine E; Ozkaya, Dogan; Sarwar, Misbah; Skylaris, Chris-Kriton; Nellist, Peter D

    2017-07-12

    Many studies of heterogeneous catalysis, both experimental and computational, make use of idealized structures such as extended surfaces or regular polyhedral nanoparticles. This simplification neglects the morphological diversity in real commercial oxygen reduction reaction (ORR) catalysts used in fuel-cell cathodes. Here we introduce an approach that combines 3D nanoparticle structures obtained from high-throughput high-precision electron microscopy with density functional theory. Discrepancies between experimental observations and cuboctahedral/truncated-octahedral particles are revealed and discussed using a range of widely used descriptors, such as electron-density, d-band centers, and generalized coordination numbers. We use this new approach to determine the optimum particle size for which both detrimental surface roughness and particle shape effects are minimized.

  5. An efficient nonequilibrium Green's function formalism combined with density functional theory approach for calculating electron transport properties of molecular devices with quasi-one-dimensional electrodes.

    PubMed

    Qian, Zekan; Li, Rui; Hou, Shimin; Xue, Zengquan; Sanvito, Stefano

    2007-11-21

    An efficient self-consistent approach combining the nonequilibrium Green's function formalism with density functional theory is developed to calculate electron transport properties of molecular devices with quasi-one-dimensional (1D) electrodes. Two problems associated with the low dimensionality of the 1D electrodes, i.e., the nonequilibrium state and the uncertain boundary conditions for the electrostatic potential, are circumvented by introducing the reflectionless boundary conditions at the electrode-contact interfaces and the zero electric field boundary conditions at the electrode-molecule interfaces. Three prototypical systems, respectively, an ideal ballistic conductor, a high resistance tunnel junction, and a molecular device, are investigated to illustrate the accuracy and efficiency of our approach.

  6. Reprint of: Combining theory and experiment for X-ray absorption spectroscopy and resonant X-ray scattering characterization of polymers

    SciTech Connect

    Su, Gregory M.; Cordova, Isvar A.; Brady, Michael A.; Prendergast, David; Wang, Cheng

    2016-11-01

    An improved understanding of fundamental chemistry, electronic structure, morphology, and dynamics in polymers and soft materials requires advanced characterization techniques that are amenable to in situ and operando studies. Soft X-ray methods are especially useful in their ability to non-destructively provide information on specific materials or chemical moieties. Analysis of these experiments, which can be very dependent on X-ray energy and polarization, can quickly become complex. Complementary modeling and predictive capabilities are required to properly probe these critical features. Here in this paper, we present relevant background on this emerging suite of techniques. We focus on how the combination of theory and experiment has been applied and can be further developed to drive our understanding of how these methods probe relevant chemistry, structure, and dynamics in soft materials.

  7. Analysis of three-dimensional-cavity-backed aperture antennas using a Combined Finite Element Method/Method of Moments/Geometrical Theory of Diffraction technique

    NASA Technical Reports Server (NTRS)

    Reddy, C. J.; Deshpande, M. D.; Cockrell, C. R.; Beck, F. B.

    1995-01-01

    A combined finite element method (FEM) and method of moments (MoM) technique is presented to analyze the radiation characteristics of a cavity-fed aperture in three dimensions. Generalized feed modeling has been done using the modal expansion of fields in the feed structure. Numerical results for some feeding structures such as a rectangular waveguide, circular waveguide, and coaxial line are presented. The method also uses the geometrical theory of diffraction (GTD) to predict the effect of a finite ground plane on radiation characteristics. Input admittance calculations for open radiating structures such as a rectangular waveguide, a circular waveguide, and a coaxial line are shown. Numerical data for a coaxial-fed cavity with finite ground plane are verified with experimental data.

  8. Reprint of: Combining theory and experiment for X-ray absorption spectroscopy and resonant X-ray scattering characterization of polymers

    DOE PAGES

    Su, Gregory M.; Cordova, Isvar A.; Brady, Michael A.; ...

    2016-11-01

    An improved understanding of fundamental chemistry, electronic structure, morphology, and dynamics in polymers and soft materials requires advanced characterization techniques that are amenable to in situ and operando studies. Soft X-ray methods are especially useful in their ability to non-destructively provide information on specific materials or chemical moieties. Analysis of these experiments, which can be very dependent on X-ray energy and polarization, can quickly become complex. Complementary modeling and predictive capabilities are required to properly probe these critical features. Here in this paper, we present relevant background on this emerging suite of techniques. We focus on how the combination ofmore » theory and experiment has been applied and can be further developed to drive our understanding of how these methods probe relevant chemistry, structure, and dynamics in soft materials.« less

  9. Combining Persuasive Technology With Behavioral Theory to Support Weight Maintenance Through a Mobile Phone App: Protocol for the MotiMate App

    PubMed Central

    Hendrie, Gilly A; Freyne, Jill

    2016-01-01

    Background The prevalence of health-focused mobile phone apps available for download increases daily, with weight management apps being among the most proliferative. However, most lack theoretic grounding or evidence of efficacy. There is a significant body of literature which provides evidence for behaviors which are associated with successful weight loss maintenance. Behavioral theory also provides further insight regarding successful behavior change and maintenance. Objective We aimed to apply this knowledge to the development of the functionality of an app targeting weight loss maintenance. Methods We have subsequently undertaken the development of a persuasive and behavior targeting mobile app (MotiMate) to assist in maintenance of weight loss. MotiMate combines persuasive and behavior change theories in a practical targeted tool through its motivational messages, personalized feedback, and intelligent supportive tools to manage weight, food, exercise, mood and stress. Results The development and trial of MotiMate received funding support in May 2014. All 88 volunteers started the trial by December 2014 and were in the process of completing their final visits when this paper was submitted (May 2015). Data analysis is currently underway. Conclusions The paper has presented a scientifically informed mobile phone app to support weight loss maintenance. Further evaluation of its efficacy is in progress. Trial Registration ANZCTR 12614000474651; https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=366120 (Archived by WebCite at http://www.webcitation.org/6eJeQiKxi). PMID:26747725

  10. Combining Persuasive Technology With Behavioral Theory to Support Weight Maintenance Through a Mobile Phone App: Protocol for the MotiMate App.

    PubMed

    Brindal, Emily; Hendrie, Gilly A; Freyne, Jill

    2016-01-08

    The prevalence of health-focused mobile phone apps available for download increases daily, with weight management apps being among the most proliferative. However, most lack theoretic grounding or evidence of efficacy. There is a significant body of literature which provides evidence for behaviors which are associated with successful weight loss maintenance. Behavioral theory also provides further insight regarding successful behavior change and maintenance. We aimed to apply this knowledge to the development of the functionality of an app targeting weight loss maintenance. We have subsequently undertaken the development of a persuasive and behavior targeting mobile app (MotiMate) to assist in maintenance of weight loss. MotiMate combines persuasive and behavior change theories in a practical targeted tool through its motivational messages, personalized feedback, and intelligent supportive tools to manage weight, food, exercise, mood and stress. The development and trial of MotiMate received funding support in May 2014. All 88 volunteers started the trial by December 2014 and were in the process of completing their final visits when this paper was submitted (May 2015). Data analysis is currently underway. The paper has presented a scientifically informed mobile phone app to support weight loss maintenance. Further evaluation of its efficacy is in progress. ANZCTR 12614000474651; https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=366120 (Archived by WebCite at http://www.webcitation.org/6eJeQiKxi).

  11. Combining linear polarization spectroscopy and the Representative Layer Theory to measure the Beer-Lambert law absorbance of highly scattering materials.

    PubMed

    Gobrecht, Alexia; Bendoula, Ryad; Roger, Jean-Michel; Bellon-Maurel, Véronique

    2015-01-01

    Visible and Near Infrared (Vis-NIR) Spectroscopy is a powerful non destructive analytical method used to analyze major compounds in bulk materials and products and requiring no sample preparation. It is widely used in routine analysis and also in-line in industries, in-vivo with biomedical applications or in-field for agricultural and environmental applications. However, highly scattering samples subvert Beer-Lambert law's linear relationship between spectral absorbance and the concentrations. Instead of spectral pre-processing, which is commonly used by Vis-NIR spectroscopists to mitigate the scattering effect, we put forward an optical method, based on Polarized Light Spectroscopy to improve the absorbance signal measurement on highly scattering samples. This method selects part of the signal which is less impacted by scattering. The resulted signal is combined in the Absorption/Remission function defined in Dahm's Representative Layer Theory to compute an absorbance signal fulfilling Beer-Lambert's law, i.e. being linearly related to concentration of the chemicals composing the sample. The underpinning theories have been experimentally evaluated on scattering samples in liquid form and in powdered form. The method produced more accurate spectra and the Pearson's coefficient assessing the linearity between the absorbance spectra and the concentration of the added dye improved from 0.94 to 0.99 for liquid samples and 0.84-0.97 for powdered samples.

  12. Surface Tension of Binary Mixtures Including Polar Components Modeled by the Density Gradient Theory Combined with the PC-SAFT Equation of State

    NASA Astrophysics Data System (ADS)

    Vinš, Václav; Planková, Barbora; Hrubý, Jan

    2013-05-01

    In this study, the Cahn-Hilliard density gradient theory (GT) is used for predicting the surface tension of various binary mixtures at relatively wide temperature ranges and for testing the application of the GT for predictions of homogeneous nucleation. The GT was combined with two physically based equations of state (EoS), namely the perturbed-chain (PC) statistical associating fluid theory (SAFT) and its modification for polar substances the perturbed-chain polar (PCP) SAFT. The GT applied to the planar phase interface was employed to predict the interfacial tension for various quadrupolar (CO2 and benzene) and dipolar (difluoromethane, i.e., R32; pentafluoroethane, i.e., R125; and 1,1,1,2-tetrafluoroethane, i.e., R134a) substances and for five binary mixtures including polar components ( n-decane + CO2, benzene + CO2, R32 + R125, R32 + R134a, R134a + R125). The PCP-SAFT EoS combined with the GT provides more accurate results for both the quadrupolar and dipolar substances than the original PC-SAFT EoS. Besides the planar phase interface, the GT was also applied to the spherical phase interface simulating a critical cluster occurring in homogeneous nucleation of droplets. Carbon dioxide was considered, because it has a relatively high quadrupole moment and because of its relevance to natural gas processing. Application of the PCP-SAFT EoS provides a significant improvement compared to the PC-SAFT EoS, and it is clearly superior to the classical cubic Peng-Robinson EoS, which is still used for modeling droplet nucleation.

  13. High-throughput design and optimization of fast lithium ion conductors by the combination of bond-valence method and density functional theory

    PubMed Central

    Xiao, Ruijuan; Li, Hong; Chen, Liquan

    2015-01-01

    Looking for solid state electrolytes with fast lithium ion conduction is an important prerequisite for developing all-solid-state lithium secondary batteries. By combining the simulation techniques in different levels of accuracy, e.g. the bond-valence (BV) method and the density functional theory (DFT), a high-throughput design and optimization scheme is proposed for searching fast lithium ion conductors as candidate solid state electrolytes for lithium rechargeable batteries. The screening from more than 1000 compounds is performed through BV-based method, and the ability to predict reliable tendency of the Li+ migration energy barriers is confirmed by comparing with the results from DFT calculations. β-Li3PS4 is taken as a model system to demonstrate the application of this combination method in optimizing properties of solid electrolytes. By employing the high-throughput DFT simulations to more than 200 structures of the doping derivatives of β-Li3PS4, the effects of doping on the ionic conductivities in this material are predicted by the BV calculations. The O-doping scheme is proposed as a promising way to improve the kinetic properties of this materials, and the validity of the optimization is proved by the first-principles molecular dynamics (FPMD) simulations. PMID:26387639

  14. Theoretical study of the ammonia nitridation rate on an Fe (100) surface: A combined density functional theory and kinetic Monte Carlo study

    SciTech Connect

    Yeo, Sang Chul; Lee, Hyuck Mo; Lo, Yu Chieh; Li, Ju

    2014-10-07

    Ammonia (NH{sub 3}) nitridation on an Fe surface was studied by combining density functional theory (DFT) and kinetic Monte Carlo (kMC) calculations. A DFT calculation was performed to obtain the energy barriers (E{sub b}) of the relevant elementary processes. The full mechanism of the exact reaction path was divided into five steps (adsorption, dissociation, surface migration, penetration, and diffusion) on an Fe (100) surface pre-covered with nitrogen. The energy barrier (E{sub b}) depended on the N surface coverage. The DFT results were subsequently employed as a database for the kMC simulations. We then evaluated the NH{sub 3} nitridation rate on the N pre-covered Fe surface. To determine the conditions necessary for a rapid NH{sub 3} nitridation rate, the eight reaction events were considered in the kMC simulations: adsorption, desorption, dissociation, reverse dissociation, surface migration, penetration, reverse penetration, and diffusion. This study provides a real-time-scale simulation of NH{sub 3} nitridation influenced by nitrogen surface coverage that allowed us to theoretically determine a nitrogen coverage (0.56 ML) suitable for rapid NH{sub 3} nitridation. In this way, we were able to reveal the coverage dependence of the nitridation reaction using the combined DFT and kMC simulations.

  15. Polite Theories Revisited

    NASA Astrophysics Data System (ADS)

    Jovanović, Dejan; Barrett, Clark

    The classic method of Nelson and Oppen for combining decision procedures requires the theories to be stably-infinite. Unfortunately, some important theories do not fall into this category (e.g. the theory of bit-vectors). To remedy this problem, previous work introduced the notion of polite theories. Polite theories can be combined with any other theory using an extension of the Nelson-Oppen approach. In this paper we revisit the notion of polite theories, fixing a subtle flaw in the original definition. We give a new combination theorem which specifies the degree to which politeness is preserved when combining polite theories. We also give conditions under which politeness is preserved when instantiating theories by identifying two sorts. These results lead to a more general variant of the theorem for combining multiple polite theories.

  16. Transferability and accuracy by combining dispersionless density functional and incremental post-Hartree-Fock theories: Noble gases adsorption on coronene/graphene/graphite surfaces

    NASA Astrophysics Data System (ADS)

    de Lara-Castells, María Pilar; Bartolomei, Massimiliano; Mitrushchenkov, Alexander O.; Stoll, Hermann

    2015-11-01

    The accuracy and transferability of the electronic structure approach combining dispersionless density functional theory (DFT) [K. Pernal et al., Phys. Rev. Lett. 103, 263201 (2009)] with the method of increments [H. Stoll, J. Chem. Phys. 97, 8449 (1992)], are validated for the interaction between the noble-gas Ne, Ar, Kr, and Xe atoms and coronene/graphene/graphite surfaces. This approach uses the method of increments for surface cluster models to extract intermonomer dispersion-like (2- and 3-body) correlation terms at coupled cluster singles and doubles and perturbative triples level, while periodic dispersionless density functionals calculations are performed to estimate the sum of Hartree-Fock and intramonomer correlation contributions. Dispersion energy contributions are also obtained using DFT-based symmetry-adapted perturbation theory [SAPT(DFT)]. An analysis of the structure of the X/surface (X = Ne, Ar, Kr, and Xe) interaction energies shows the excellent transferability properties of the leading intermonomer correlation contributions across the sequence of noble-gas atoms, which are also discussed using the Drude oscillator model. We further compare these results with van der Waals-(vdW)-corrected DFT-based approaches. As a test of accuracy, the energies of the low-lying nuclear bound states supported by the laterally averaged X/graphite potentials (X = 3He, 4He, Ne, Ar, Kr, and Xe) are calculated and compared with the best estimations from experimental measurements and an atom-bond potential model using the ab initio-assisted fine-tuning of semiempirical parameters. The bound-state energies determined differ by less than 6-7 meV (6%) from the atom-bond potential model. The crucial importance of including incremental 3-body dispersion-type terms is clearly demonstrated, showing that the SAPT(DFT) approach effectively account for these terms. With the deviations from the best experimental-based estimations smaller than 2.3 meV (1.9%), the accuracy of the

  17. Transferability and accuracy by combining dispersionless density functional and incremental post-Hartree-Fock theories: Noble gases adsorption on coronene/graphene/graphite surfaces.

    PubMed

    de Lara-Castells, María Pilar; Bartolomei, Massimiliano; Mitrushchenkov, Alexander O; Stoll, Hermann

    2015-11-21

    The accuracy and transferability of the electronic structure approach combining dispersionless density functional theory (DFT) [K. Pernal et al., Phys. Rev. Lett. 103, 263201 (2009)] with the method of increments [H. Stoll, J. Chem. Phys. 97, 8449 (1992)], are validated for the interaction between the noble-gas Ne, Ar, Kr, and Xe atoms and coronene/graphene/graphite surfaces. This approach uses the method of increments for surface cluster models to extract intermonomer dispersion-like (2- and 3-body) correlation terms at coupled cluster singles and doubles and perturbative triples level, while periodic dispersionless density functionals calculations are performed to estimate the sum of Hartree-Fock and intramonomer correlation contributions. Dispersion energy contributions are also obtained using DFT-based symmetry-adapted perturbation theory [SAPT(DFT)]. An analysis of the structure of the X/surface (X = Ne, Ar, Kr, and Xe) interaction energies shows the excellent transferability properties of the leading intermonomer correlation contributions across the sequence of noble-gas atoms, which are also discussed using the Drude oscillator model. We further compare these results with van der Waals-(vdW)-corrected DFT-based approaches. As a test of accuracy, the energies of the low-lying nuclear bound states supported by the laterally averaged X/graphite potentials (X = (3)He, (4)He, Ne, Ar, Kr, and Xe) are calculated and compared with the best estimations from experimental measurements and an atom-bond potential model using the ab initio-assisted fine-tuning of semiempirical parameters. The bound-state energies determined differ by less than 6-7 meV (6%) from the atom-bond potential model. The crucial importance of including incremental 3-body dispersion-type terms is clearly demonstrated, showing that the SAPT(DFT) approach effectively account for these terms. With the deviations from the best experimental-based estimations smaller than 2.3 meV (1.9%), the accuracy of

  18. Transferability and accuracy by combining dispersionless density functional and incremental post-Hartree-Fock theories: Noble gases adsorption on coronene/graphene/graphite surfaces

    SciTech Connect

    Lara-Castells, María Pilar de Bartolomei, Massimiliano; Mitrushchenkov, Alexander O.; Stoll, Hermann

    2015-11-21

    The accuracy and transferability of the electronic structure approach combining dispersionless density functional theory (DFT) [K. Pernal et al., Phys. Rev. Lett. 103, 263201 (2009)] with the method of increments [H. Stoll, J. Chem. Phys. 97, 8449 (1992)], are validated for the interaction between the noble-gas Ne, Ar, Kr, and Xe atoms and coronene/graphene/graphite surfaces. This approach uses the method of increments for surface cluster models to extract intermonomer dispersion-like (2- and 3-body) correlation terms at coupled cluster singles and doubles and perturbative triples level, while periodic dispersionless density functionals calculations are performed to estimate the sum of Hartree-Fock and intramonomer correlation contributions. Dispersion energy contributions are also obtained using DFT-based symmetry-adapted perturbation theory [SAPT(DFT)]. An analysis of the structure of the X/surface (X = Ne, Ar, Kr, and Xe) interaction energies shows the excellent transferability properties of the leading intermonomer correlation contributions across the sequence of noble-gas atoms, which are also discussed using the Drude oscillator model. We further compare these results with van der Waals-(vdW)-corrected DFT-based approaches. As a test of accuracy, the energies of the low-lying nuclear bound states supported by the laterally averaged X/graphite potentials (X = {sup 3}He, {sup 4}He, Ne, Ar, Kr, and Xe) are calculated and compared with the best estimations from experimental measurements and an atom-bond potential model using the ab initio-assisted fine-tuning of semiempirical parameters. The bound-state energies determined differ by less than 6–7 meV (6%) from the atom-bond potential model. The crucial importance of including incremental 3-body dispersion-type terms is clearly demonstrated, showing that the SAPT(DFT) approach effectively account for these terms. With the deviations from the best experimental-based estimations smaller than 2.3 meV (1.9%), the

  19. Density functional theory (DFT) and combined quantum mechanical/molecular mechanics (QM/MM) studies on the oxygen activation step in nitric oxide synthase enzymes.

    PubMed

    de Visser, Sam P

    2009-04-01

    In this review paper, we will give an overview of recent theoretical studies on the catalytic cycle(s) of NOS (nitric oxide synthase) enzymes and in particular on the later stages of these cycles where experimental work is difficult due to the short lifetime of intermediates. NOS enzymes are vital for human health and are involved in the biosynthesis of toxic nitric oxide. Despite many experimental efforts in the field, the catalytic cycle of this important enzyme is still surrounded by many unknowns and controversies. Our theoretical studies were focused on the grey zones of the catalytic cycle, where intermediates are short-lived and experimental detection is impossible. Thus combined QM/MM (quantum mechanics/molecular mechanics) as well as DFT (density functional theory) studies on NOS enzymes and active site models have established a novel mechanism of oxygen activation and the conversion of L-arginine into N(omega)-hydroxo-arginine. Although NOS enzymes show many structural similarities to cytochrome P450 enzymes, it has long been anticipated that therefore they should have a similar catalytic cycle where molecular oxygen binds to a haem centre and is converted into an Fe(IV)-oxo haem(+*) active species (Compound I). Compound I, however, is elusive in the cytochrome P450s as well as in NOS enzymes, but indirect experimental evidence on cytochrome P450 systems combined with theoretical modelling have shown it to be the oxidant responsible for hydroxylation reactions in cytochrome P450 enzymes. By contrast, in the first catalytic cycle of NOS it has been shown that Compound I is first reduced to Compound II before the hydroxylation of arginine. Furthermore, substrate arginine in NOS enzymes appears to have a dual function, namely first as a proton donor in the catalytic cycle to convert the ferric-superoxo into a ferric-hydroperoxo complex and secondly as the substrate that is hydroxylated in the process leading to N(omega)-hydroxo-arginine.

  20. Theory-Based Interventions Combining Mental Simulation and Planning Techniques to Improve Physical Activity: Null Results from Two Randomized Controlled Trials

    PubMed Central

    Meslot, Carine; Gauchet, Aurélie; Allenet, Benoît; François, Olivier; Hagger, Martin S.

    2016-01-01

    Interventions to assist individuals in initiating and maintaining regular participation in physical activity are not always effective. Psychological and behavioral theories advocate the importance of both motivation and volition in interventions to change health behavior. Interventions adopting self-regulation strategies that foster motivational and volitional components may, therefore, have utility in promoting regular physical activity participation. We tested the efficacy of an intervention adopting motivational (mental simulation) and volitional (implementation intentions) components to promote a regular physical activity in two studies. Study 1 adopted a cluster randomized design in which participants (n = 92) were allocated to one of three conditions: mental simulation plus implementation intention, implementation intention only, or control. Study 2 adopted a 2 (mental simulation vs. no mental simulation) × 2 (implementation intention vs. no implementation intention) randomized controlled design in which fitness center attendees (n = 184) were randomly allocated one of four conditions: mental simulation only, implementation intention only, combined, or control. Physical activity behavior was measured by self-report (Study 1) or fitness center attendance (Study 2) at 4- (Studies 1 and 2) and 19- (Study 2 only) week follow-up periods. Findings revealed no statistically significant main or interactive effects of the mental simulation and implementation intention conditions on physical activity outcomes in either study. Findings are in contrast to previous research which has found pervasive effects for both intervention strategies. Findings are discussed in light of study limitations including the relatively small sample sizes, particularly for Study 1, deviations in the operationalization of the intervention components from previous research and the lack of a prompt for a goal intention. Future research should focus on ensuring uniformity in the format of the

  1. Theory-Based Interventions Combining Mental Simulation and Planning Techniques to Improve Physical Activity: Null Results from Two Randomized Controlled Trials.

    PubMed

    Meslot, Carine; Gauchet, Aurélie; Allenet, Benoît; François, Olivier; Hagger, Martin S

    2016-01-01

    Interventions to assist individuals in initiating and maintaining regular participation in physical activity are not always effective. Psychological and behavioral theories advocate the importance of both motivation and volition in interventions to change health behavior. Interventions adopting self-regulation strategies that foster motivational and volitional components may, therefore, have utility in promoting regular physical activity participation. We tested the efficacy of an intervention adopting motivational (mental simulation) and volitional (implementation intentions) components to promote a regular physical activity in two studies. Study 1 adopted a cluster randomized design in which participants (n = 92) were allocated to one of three conditions: mental simulation plus implementation intention, implementation intention only, or control. Study 2 adopted a 2 (mental simulation vs. no mental simulation) × 2 (implementation intention vs. no implementation intention) randomized controlled design in which fitness center attendees (n = 184) were randomly allocated one of four conditions: mental simulation only, implementation intention only, combined, or control. Physical activity behavior was measured by self-report (Study 1) or fitness center attendance (Study 2) at 4- (Studies 1 and 2) and 19- (Study 2 only) week follow-up periods. Findings revealed no statistically significant main or interactive effects of the mental simulation and implementation intention conditions on physical activity outcomes in either study. Findings are in contrast to previous research which has found pervasive effects for both intervention strategies. Findings are discussed in light of study limitations including the relatively small sample sizes, particularly for Study 1, deviations in the operationalization of the intervention components from previous research and the lack of a prompt for a goal intention. Future research should focus on ensuring uniformity in the format of the

  2. Potassium-induced effect on structure and chemical activity of CuxO/Cu(111) (x≤2) surface: A combined scanning tunneling microscopy and density functional theory study

    DOE PAGES

    Liu, Ping; An, Wei; Stacchiola, Dario; ...

    2015-10-16

    Potassium (K) plays an essential role in promoting catalytic reaction in many established industrial catalytic processes. Here, we report a combined study using scanning tunneling microscopy (STM) and density functional theory (DFT) in understanding the effect of depositing K on the atomic and electronic structures as well as chemical activities of CuxO/Cu(111) (x≤2). The DFT calculations observe a pseudomorphic growth of K on CuxO/Cu(111) up to 0.19 monolayer (ML) of coverage, where K binds the surface via strong ionic interaction with chemisorbed oxygen and the relatively weak electrostatic interactions with copper ions, lower and upper oxygen on the CuxO rings.more » The simulated STM pattern based on the DFT results agrees well with the experimental observations. The deposited K displays great impact on the surface electronic structure of CuxO/Cu(111), which induces significant reduction in work function and leads to a strong electron polarization on the surface. The promotion of K on the surface binding properties is selective. It varies depending on the nature of adsorbates. According to our results, K has little effect on surface acidity, while it enhances the surface basicity significantly. As a consequence, the presence of K does not help for CO adsorption on CuxO/Cu(111), but being able to accelerate the activation of CO2. Thus, such promotion strongly depends on the combinations from both geometric and electronic effects. Our results highlight the origin of promoting effect of alkalis in the design of catalysts for the complex reactions.« less

  3. Applying factor analysis combined with kriging and information entropy theory for mapping and evaluating the stability of groundwater quality variation in Taiwan.

    PubMed

    Shyu, Guey-Shin; Cheng, Bai-You; Chiang, Chi-Ting; Yao, Pei-Hsuan; Chang, Tsun-Kuo

    2011-04-01

    In Taiwan many factors, whether geological parent materials, human activities, and climate change, can affect the groundwater quality and its stability. This work combines factor analysis and kriging with information entropy theory to interpret the stability of groundwater quality variation in Taiwan between 2005 and 2007. Groundwater quality demonstrated apparent differences between the northern and southern areas of Taiwan when divided by the Wu River. Approximately 52% of the monitoring wells in southern Taiwan suffered from progressing seawater intrusion, causing unstable groundwater quality. Industrial and livestock wastewaters also polluted 59.6% of the monitoring wells, resulting in elevated EC and TOC concentrations in the groundwater. In northern Taiwan, domestic wastewaters polluted city groundwater, resulting in higher NH(3)-N concentration and groundwater quality instability was apparent among 10.3% of the monitoring wells. The method proposed in this study for analyzing groundwater quality inspects common stability factors, identifies potential areas influenced by common factors, and assists in elevating and reinforcing information in support of an overall groundwater management strategy.

  4. Applying Factor Analysis Combined with Kriging and Information Entropy Theory for Mapping and Evaluating the Stability of Groundwater Quality Variation in Taiwan

    PubMed Central

    Shyu, Guey-Shin; Cheng, Bai-You; Chiang, Chi-Ting; Yao, Pei-Hsuan; Chang, Tsun-Kuo

    2011-01-01

    In Taiwan many factors, whether geological parent materials, human activities, and climate change, can affect the groundwater quality and its stability. This work combines factor analysis and kriging with information entropy theory to interpret the stability of groundwater quality variation in Taiwan between 2005 and 2007. Groundwater quality demonstrated apparent differences between the northern and southern areas of Taiwan when divided by the Wu River. Approximately 52% of the monitoring wells in southern Taiwan suffered from progressing seawater intrusion, causing unstable groundwater quality. Industrial and livestock wastewaters also polluted 59.6% of the monitoring wells, resulting in elevated EC and TOC concentrations in the groundwater. In northern Taiwan, domestic wastewaters polluted city groundwater, resulting in higher NH3-N concentration and groundwater quality instability was apparent among 10.3% of the monitoring wells. The method proposed in this study for analyzing groundwater quality inspects common stability factors, identifies potential areas influenced by common factors, and assists in elevating and reinforcing information in support of an overall groundwater management strategy. PMID:21695030

  5. Photovoltaic Properties of Two-Dimensional (CH3NH3)2Pb(SCN)2I2 Perovskite: A Combined Experimental and Density Functional Theory Study.

    PubMed

    Xiao, Zewen; Meng, Weiwei; Saparov, Bayrammurad; Duan, Hsin-Sheng; Wang, Changlei; Feng, Chunbao; Liao, Weiqiang; Ke, Weijun; Zhao, Dewei; Wang, Jianbo; Mitzi, David B; Yan, Yanfa

    2016-04-07

    We explore the photovoltaic-relevant properties of the 2D MA2Pb(SCN)2I2 (where MA = CH3NH3(+)) perovskite using a combination of materials synthesis, characterization and density functional theory calculation, and determine electronic properties of MA2Pb(SCN)2I2 that are significantly different from those previously reported in literature. The layered perovskite with mixed-anions exhibits an indirect bandgap of ∼2.04 eV, with a slightly larger direct bandgap of ∼2.11 eV. The carriers (both electrons and holes) are also found to be confined within the 2D layers. Our results suggest that the 2D MA2Pb(SCN)2I2 perovskite may not be among the most promising absorbers for efficient single-junction solar cell applications; however, use as an absorber for the top cell of a tandem solar cell may still be a possibility if films are grown with the 2D layers aligned perpendicular to the substrates.

  6. CuPc/Au(1 1 0): Determination of the azimuthal alignment by a combination of angle-resolved photoemission and density functional theory

    PubMed Central

    Lüftner, Daniel; Milko, Matus; Huppmann, Sophia; Scholz, Markus; Ngyuen, Nam; Wießner, Michael; Schöll, Achim; Reinert, Friedrich; Puschnig, Peter

    2014-01-01

    Here we report on a combined experimental and theoretical study on the structural and electronic properties of a monolayer of Copper-Phthalocyanine (CuPc) on the Au(1 1 0) surface. Low-energy electron diffraction reveals a commensurate overlayer unit cell containing one adsorbate species. The azimuthal alignment of the CuPc molecule is revealed by comparing experimental constant binding energy (kxky)-maps using angle-resolved photoelectron spectroscopy with theoretical momentum maps of the free molecule's highest occupied molecular orbital (HOMO). This structural information is confirmed by total energy calculations within the framework of van-der-Waals corrected density functional theory. The electronic structure is further analyzed by computing the molecule-projected density of states, using both a semi-local and a hybrid exchange-correlation functional. In agreement with experiment, the HOMO is located about 1.2 eV below the Fermi-level, while there is no significant charge transfer into the molecule and the CuPc LUMO remains unoccupied on the Au(1 1 0) surface. PMID:25284953

  7. CO2 capture properties of alkaline earth metal oxides and hydroxides: A combined density functional theory and lattice phonon dynamics study

    NASA Astrophysics Data System (ADS)

    Duan, Yuhua; Sorescu, Dan C.

    2010-08-01

    By combining density functional theory and lattice phonon dynamics, the thermodynamic properties of CO2 absorption/desorption reactions with alkaline earth metal oxides MO and hydroxides M(OH)2 (where M=Be,Mg,Ca,Sr,Ba) are analyzed. The heats of reaction and the chemical potential changes of these solids upon CO2 capture reactions have been calculated and used to evaluate the energy costs. Relative to CaO, a widely used system in practical applications, MgO and Mg(OH)2 systems were found to be better candidates for CO2 sorbent applications due to their lower operating temperatures (600-700 K). In the presence of H2O, MgCO3 can be regenerated into Mg(OH)2 at low temperatures or into MgO at high temperatures. This transition temperature depends not only on the CO2 pressure but also on the H2O pressure. Based on our calculated results and by comparing with available experimental data, we propose a general computational search methodology which can be used as a general scheme for screening a large number of solids for use as CO2 sorbents.

  8. Drastic Compensation of Electronic and Solvation Effects on ATP Hydrolysis Revealed through Large-Scale QM/MM Simulations Combined with a Theory of Solutions.

    PubMed

    Takahashi, Hideaki; Umino, Satoru; Miki, Yuji; Ishizuka, Ryosuke; Maeda, Shu; Morita, Akihiro; Suzuki, Makoto; Matubayasi, Nobuyuki

    2017-03-16

    Hydrolysis of adenosine triphosphate (ATP) is the "energy source" for a variety of biochemical processes. In the present work, we address key features of ATP hydrolysis: the relatively moderate value (about -10 kcal/mol) of the standard free energy, ΔGhyd, of reaction and the insensitivity of ΔGhyd to the number of excess electrons on ATP. We conducted quantum mechanical/molecular mechanical simulation combined with the energy-representation theory of solutions to analyze the electronic-state and solvation contributions to ΔGhyd. It was revealed that the electronic-state contribution in ΔGhyd is largely negative (favorable) upon hydrolysis, due to the reduction of electrostatic repulsion accompanying the breakage of the P-O bond. In contrast, the solvation effect was found to be strongly more favorable on the reactant side. Thus, we showed that a drastic compensation of the two opposite effects takes place, leading to the modest value of ΔGhyd at each number of excess electrons examined. The computational analyses were also conducted for pyrophosphate ions (PPi), and the parallelism between the ATP and PPi hydrolyses was confirmed. Classical molecular dynamics simulation was further carried out to discuss the effect of the solvent environment; the insensitivity of ΔGhyd to the number of excess electrons was seen to hold in solvent water and ethanol.

  9. Microscopic origin of the charge transfer in single crystals based on thiophene derivatives: A combined NEXAFS and density functional theory approach

    NASA Astrophysics Data System (ADS)

    Chernenkaya, A.; Morherr, A.; Backes, S.; Popp, W.; Witt, S.; Kozina, X.; Nepijko, S. A.; Bolte, M.; Medjanik, K.; Öhrwall, G.; Krellner, C.; Baumgarten, M.; Elmers, H. J.; Schönhense, G.; Jeschke, H. O.; Valentí, R.

    2016-07-01

    We have investigated the charge transfer mechanism in single crystals of DTBDT-TCNQ and DTBDT-F4TCNQ (where DTBDT is dithieno[2,3-d;2',3'-d'] benzo[1,2-b;4,5-b']dithiophene) using a combination of near-edge X-ray absorption spectroscopy (NEXAFS) and density functional theory calculations (DFT) including final state effects beyond the sudden state approximation. In particular, we find that a description that considers the partial screening of the electron-hole Coulomb correlation on a static level as well as the rearrangement of electronic density shows excellent agreement with experiment and allows to uncover the details of the charge transfer mechanism in DTBDT-TCNQ and DTBDT-F4 TCNQ, as well as a reinterpretation of previous NEXAFS data on pure TCNQ. Finally, we further show that almost the same quality of agreement between theoretical results and experiment is obtained by the much faster Z+1/2 approximation, where the core hole effects are simulated by replacing N or F with atomic number Z with the neighboring atom with atomic number Z+1/2.

  10. Rapid QM/MM approach for biomolecular systems under periodic boundary conditions: Combination of the density-functional tight-binding theory and particle mesh Ewald method.

    PubMed

    Nishizawa, Hiroaki; Okumura, Hisashi

    2016-12-05

    A quantum mechanical/molecular mechanical (QM/MM) approach based on the density-functional tight-binding (DFTB) theory is a useful tool for analyzing chemical reaction systems in detail. In this study, an efficient QM/MM method is developed by the combination of the DFTB/MM and particle mesh Ewald (PME) methods. Because the Fock matrix, which is required in the DFTB calculation, is analytically obtained by the PME method, the Coulomb energy is accurately and rapidly computed. For assessing the performance of this method, DFTB/MM calculations and molecular dynamics simulation are conducted for a system consisting of two amyloid-β(1-16) peptides and a zinc ion in explicit water under periodic boundary conditions. As compared with that of the conventional Ewald summation method, the computational cost of the Coulomb energy by utilizing the present approach is drastically reduced, i.e., 166.5 times faster. Furthermore, the deviation of the electronic energy is less than 10-6 Eh. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  11. Comparison of the site occupancies determined by combined Rietveld refinement and density functional theory calculations: example of the ternary Mo-Ni-Re σ phase.

    PubMed

    Yaqoob, Khurram; Crivello, Jean-Claude; Joubert, Jean-Marc

    2012-03-05

    The site occupancies of the Mo-Ni-Re σ phase have been studied as a function of the composition in the ternary homogeneity domain by both experimental measurements and calculations. Because of the possible simultaneous occupancy of three elements on the five sites of the crystal structure, the experimental determination of the site occupancies was achieved by using combined Rietveld refinement of X-ray and neutron diffraction data, whereas calculation of the site occupancies was carried out by using the density functional theory results of every ordered (i.e., 3(5) = 243) configuration appearing in the ternary system. A comparison of the experimental and calculation results showed good agreement, which suggests that the topologically close-packed phases, such as the σ phase, could be described by the Bragg-Williams approximation (i.e., ignoring the short-range-order contributions). On the other hand, the atomic distribution on different crystallographic sites of the Mo-Ni-Re σ phase was found to be governed by the atomic sizes. Ni, having the smallest atomic size, showed a preference for low-coordination-number (CN) sites, whereas Mo, being the largest in atomic size, preferred occupying high-CN sites. However, the preference of Re, having intermediate atomic size, varied depending on the composition, and a clear reversal in the preference of Re as a function of the composition was evidenced in both the calculated and experimental site-occupancy results.

  12. Phase diagram of the CulnSe{sub 2}-CuGaSe{sub 2} pseudobinary system studied by combined ab initio density functional theory and thermodynamic calculation

    SciTech Connect

    Xue, H. T.; Tang, F. L.; Lu, W. J.; Li, X. K.; Zhang, Y.; Feng, Y. D.

    2014-08-07

    The phase diagram of the CuInSe{sub 2}-CuGaSe{sub 2} pseudobinary system was determined using a combination of special quasirandom structure approach, ab initio density functional theory calculations, and thermodynamic modelling. It is shown that the CuIn{sub 1−x}Ga{sub x}Se{sub 2} solution phase has a tendency to phase separation at low temperature. The calculated consolute temperature is 485 K. It is found that both the binodal and spinodal curves are significantly asymmetric and on both curves there are a local maximum and a local minimum, which have not been reported in the previous studies. Our phase diagram can well explain the finding that the inhomogeneity of CuIn{sub 0.25}Ga{sub 0.75}Se{sub 2} is higher than that of CuIn{sub 0.75}Ga{sub 0.25}Se{sub 2} at the same temperature, while the previous phase diagrams cannot. Hence, our phase diagram should be more reliable and applicable.

  13. Solvation Mechanism of Task-Specific Ionic Liquids in Water: A Combined Investigation Using Classical Molecular Dynamics and Density Functional Theory.

    PubMed

    Yuvaraj, Surya V J; Zhdanov, Ravil K; Belosludov, Rodion V; Belosludov, Vladimir R; Subbotin, Oleg S; Kanie, Kiyoshi; Funaki, Kenji; Muramatsu, Atsushi; Nakamura, Takashi; Kawazoe, Yoshiyuki

    2015-10-08

    The solvation behavior of task-specific ionic liquids (TSILs) containing a common, L-histidine derived imidazolium cation [C20H28N3O3](+) and different anions, bromide-[Br](-) and bis(trifluoromethylsulfonyl)amide-[NTF2](-), in water is examined, computationally. These amino acid functionalized ionic liquids (ILs) are taken into account because of their ability to react with rare earth metal salts. It has been noted that the TSIL with [Br](-) is more soluble than its counterpart TSIL with [NTF2](-), experimentally. In this theoretical work, the combined classical molecular dynamics (CMD) and density functional theory (DFT) calculations are performed to study the behavior of the bulk phase of these two TSILs in the vicinity of water (H2O) molecules with different concentrations. Initially, all the constructed systems are equilibrated using the CMD method. The final structures of the equilibrated systems are extracted for DFT calculations. Under CMD operation, the radial distribution function (RDF) plots and viscosity of TSILs are analyzed to understand the effect of water on TSILs. In the DFT regime, binding energy per H2O, charge transfer, charge density mapping, and electronic density of states (EDOS) analyses are done. The CMD results along with the DFT results are consolidated to support the hydrophilic and hydrophobic nature of the TSILs. Interestingly, we have found a strong correlation between the viscosity and the EDOS results that leads to an understanding of the hydration properties of the TSILs.

  14. Effects of Polytypism on the Thermoelectric Properties of Group-IV Semiconductor Nanowires: A Combination of Density Functional Theory and Boltzmann Transport Calculations

    NASA Astrophysics Data System (ADS)

    Akiyama, Toru; Komoda, Takato; Nakamura, Kohji; Ito, Tomonori

    2017-08-01

    The effects of polytypism on thermoelectric properties of Si and Ge nanowires (NWs) are systematically investigated by using a combination of density functional theory and Boltzmann transport calculations. The calculations for NWs with various polytypes demonstrate that the thermoelectric figure of merit Z T of Si and Ge NWs can be tuned by changing different stacking sequences along the growth direction. In particular, the Z T values of n -type Si and Ge NWs with hexagonal (2 H ) structure at 300 K are significantly larger than Z T of Si and Ge NWs with a cubic (3 C ) structure. The underlying mechanism for the enhanced Z T value in Si NWs with a 2 H structure compared with a 3 C structure is attributed by the different Seebeck coefficient depending on the structure, while that in Ge NWs is due to the difference in both the Seebeck coefficient and electrical conductivity. The calculated results offer a way to design high-performance thermoelectric materials by controlling the polytype of NWs.

  15. Combining density functional theory (DFT) and collision cross-section (CCS) calculations to analyze the gas-phase behaviour of small molecules and their protonation site isomers.

    PubMed

    Boschmans, Jasper; Jacobs, Sam; Williams, Jonathan P; Palmer, Martin; Richardson, Keith; Giles, Kevin; Lapthorn, Cris; Herrebout, Wouter A; Lemière, Filip; Sobott, Frank

    2016-06-20

    Electrospray ion mobility-mass spectrometry (IM-MS) data show that for some small molecules, two (or even more) ions with identical sum formula and mass, but distinct drift times are observed. In spite of showing their own unique and characteristic fragmentation spectra in MS/MS, no configurational or constitutional isomers are found to be present in solution. Instead the observation and separation of such ions appears to be inherent to their gas-phase behaviour during ion mobility experiments. The origin of multiple drift times is thought to be the result of protonation site isomers ('protomers'). Although some important properties of protomers have been highlighted by other studies, correlating the experimental collision cross-sections (CCSs) with calculated values has proven to be a major difficulty. As a model, this study uses the pharmaceutical compound melphalan and a number of related molecules with alternative (gas-phase) protonation sites. Our study combines density functional theory (DFT) calculations with modified MobCal methods (e.g. nitrogen-based Trajectory Method algorithm) for the calculation of theoretical CCS values. Calculated structures can be linked to experimentally observed signals, and a strong correlation is found between the difference of the calculated dipole moments of the protomer pairs and their experimental CCS separation.

  16. Fast clustering algorithm for large ECG data sets based on CS theory in combination with PCA and K-NN methods.

    PubMed

    Balouchestani, Mohammadreza; Krishnan, Sridhar

    2014-01-01

    Long-term recording of Electrocardiogram (ECG) signals plays an important role in health care systems for diagnostic and treatment purposes of heart diseases. Clustering and classification of collecting data are essential parts for detecting concealed information of P-QRS-T waves in the long-term ECG recording. Currently used algorithms do have their share of drawbacks: 1) clustering and classification cannot be done in real time; 2) they suffer from huge energy consumption and load of sampling. These drawbacks motivated us in developing novel optimized clustering algorithm which could easily scan large ECG datasets for establishing low power long-term ECG recording. In this paper, we present an advanced K-means clustering algorithm based on Compressed Sensing (CS) theory as a random sampling procedure. Then, two dimensionality reduction methods: Principal Component Analysis (PCA) and Linear Correlation Coefficient (LCC) followed by sorting the data using the K-Nearest Neighbours (K-NN) and Probabilistic Neural Network (PNN) classifiers are applied to the proposed algorithm. We show our algorithm based on PCA features in combination with K-NN classifier shows better performance than other methods. The proposed algorithm outperforms existing algorithms by increasing 11% classification accuracy. In addition, the proposed algorithm illustrates classification accuracy for K-NN and PNN classifiers, and a Receiver Operating Characteristics (ROC) area of 99.98%, 99.83%, and 99.75% respectively.

  17. Kinetic network study of the diversity and temperature dependence of Trp-Cage folding pathways: combining transition path theory with stochastic simulations.

    PubMed

    Zheng, Weihua; Gallicchio, Emilio; Deng, Nanjie; Andrec, Michael; Levy, Ronald M

    2011-02-17

    We present a new approach to study a multitude of folding pathways and different folding mechanisms for the 20-residue mini-protein Trp-Cage using the combined power of replica exchange molecular dynamics (REMD) simulations for conformational sampling, transition path theory (TPT) for constructing folding pathways, and stochastic simulations for sampling the pathways in a high dimensional structure space. REMD simulations of Trp-Cage with 16 replicas at temperatures between 270 and 566 K are carried out with an all-atom force field (OPLSAA) and an implicit solvent model (AGBNP). The conformations sampled from all temperatures are collected. They form a discretized state space that can be used to model the folding process. The equilibrium population for each state at a target temperature can be calculated using the weighted-histogram-analysis method (WHAM). By connecting states with similar structures and creating edges satisfying detailed balance conditions, we construct a kinetic network that preserves the equilibrium population distribution of the state space. After defining the folded and unfolded macrostates, committor probabilities (P(fold)) are calculated by solving a set of linear equations for each node in the network and pathways are extracted together with their fluxes using the TPT algorithm. By clustering the pathways into folding "tubes", a more physically meaningful picture of the diversity of folding routes emerges. Stochastic simulations are carried out on the network, and a procedure is developed to project sampled trajectories onto the folding tubes. The fluxes through the folding tubes calculated from the stochastic trajectories are in good agreement with the corresponding values obtained from the TPT analysis. The temperature dependence of the ensemble of Trp-Cage folding pathways is investigated. Above the folding temperature, a large number of diverse folding pathways with comparable fluxes flood the energy landscape. At low temperature

  18. Interaction of Isophorone with Pd(111): A Combination of Infrared Reflection-Absorption Spectroscopy, Near-Edge X-ray Absorption Fine Structure, and Density Functional Theory Studies.

    PubMed

    Dostert, Karl-Heinz; O'Brien, Casey P; Riedel, Wiebke; Savara, Aditya; Liu, Wei; Oehzelt, Martin; Tkatchenko, Alexandre; Schauermann, Swetlana

    2014-12-04

    Atomistic level understanding of interaction of α,β-unsaturated carbonyls with late transition metals is a key prerequisite for rational design of new catalytic materials with the desired selectivity toward C=C or C=O bond hydrogenation. The interaction of this class of compounds with transition metals was investigated on α,β-unsaturated ketone isophorone on Pd(111) as a prototypical system. In this study, infrared reflection-absorption spectroscopy (IRAS), near-edge X-ray absorption fine structure (NEXAFS) experiments, and density functional theory calculations including van der Waals interactions (DFT+vdW) were combined to obtain detailed information on the binding of isophorone to palladium at different coverages and on the effect of preadsorbed hydrogen on the binding and adsorption geometry. According to these experimental observations and the results of theoretical calculations, isophorone adsorbs on Pd(111) in a flat-lying geometry at low coverages. With increasing coverage, both C=C and C=O bonds of isophorone tilt with respect to the surface plane. The tilting is considerably more pronounced for the C=C bond on the pristine Pd(111) surface, indicating a prominent perturbation and structural distortion of the conjugated π system upon interaction with Pd. Preadsorbed hydrogen leads to higher tilting angles of both π bonds, which points to much weaker interaction of isophorone with hydrogen-precovered Pd and suggests the conservation of the in-plane geometry of the conjugated π system. The results of the DFT+vdW calculations provide further insights into the perturbation of the molecular structure of isophorone on Pd(111).

  19. Interaction of Isophorone with Pd(111): A Combination of Infrared Reflection–Absorption Spectroscopy, Near-Edge X-ray Absorption Fine Structure, and Density Functional Theory Studies

    PubMed Central

    2014-01-01

    Atomistic level understanding of interaction of α,β-unsaturated carbonyls with late transition metals is a key prerequisite for rational design of new catalytic materials with the desired selectivity toward C=C or C=O bond hydrogenation. The interaction of this class of compounds with transition metals was investigated on α,β-unsaturated ketone isophorone on Pd(111) as a prototypical system. In this study, infrared reflection–absorption spectroscopy (IRAS), near-edge X-ray absorption fine structure (NEXAFS) experiments, and density functional theory calculations including van der Waals interactions (DFT+vdW) were combined to obtain detailed information on the binding of isophorone to palladium at different coverages and on the effect of preadsorbed hydrogen on the binding and adsorption geometry. According to these experimental observations and the results of theoretical calculations, isophorone adsorbs on Pd(111) in a flat-lying geometry at low coverages. With increasing coverage, both C=C and C=O bonds of isophorone tilt with respect to the surface plane. The tilting is considerably more pronounced for the C=C bond on the pristine Pd(111) surface, indicating a prominent perturbation and structural distortion of the conjugated π system upon interaction with Pd. Preadsorbed hydrogen leads to higher tilting angles of both π bonds, which points to much weaker interaction of isophorone with hydrogen-precovered Pd and suggests the conservation of the in-plane geometry of the conjugated π system. The results of the DFT+vdW calculations provide further insights into the perturbation of the molecular structure of isophorone on Pd(111). PMID:26089998

  20. Structures and chemical bonding of B3O3 (-/0) and B3O3H(-/0): A combined photoelectron spectroscopy and first-principles theory study.

    PubMed

    Zhao, Li-Juan; Tian, Wen-Juan; Ou, Ting; Xu, Hong-Guang; Feng, Gang; Xu, Xi-Ling; Zhai, Hua-Jin; Li, Si-Dian; Zheng, Wei-Jun

    2016-03-28

    We present a combined photoelectron spectroscopy and first-principles theory study on the structural and electronic properties and chemical bonding of B3O3 (-/0) and B3O3H(-/0) clusters. The concerted experimental and theoretical data show that the global-minimum structures of B3O3 and B3O3H neutrals are very different from those of their anionic counterparts. The B3O3 (-) anion is characterized to possess a V-shaped OB-B-BO chain with overall C2 v symmetry (1A), in which the central B atom interacts with two equivalent boronyl (B≡O) terminals via B-B single bonds as well as with one O atom via a B=O double bond. The B3O3H(-) anion has a Cs (2A) structure, containing an asymmetric OB-B-OBO zig-zag chain and a terminal H atom interacting with the central B atom. In contrast, the C2 v (1a) global minimum of B3O3 neutral contains a rhombic B2O2 ring with one B atom bonded to a BO terminal and that of neutral B3O3H (2a) is also of C2 v symmetry, which is readily constructed from C2 v (1a) by attaching a H atom to the opposite side of the BO group. The H atom in B3O3H(-/0) (2A and 2a) prefers to interact terminally with a B atom, rather than with O. Chemical bonding analyses reveal a three-center four-electron (3c-4e) π hyperbond in the B3O3H(-) (2A) cluster and a four-center four-electron (4c-4e) π bond (that is, the so-called o-bond) in B3O3 (1a) and B3O3H (2a) neutral clusters.

  1. Identifying the proton transfer reaction mechanism via a proton-bound dimeric intermediate for esomeprazoles by a kinetic method combined with density functional theory calculations.

    PubMed

    Cao, Xiaoji; Zhang, Feifei; Zhu, Kundan; Ye, Xuemin; Shen, Lingxiao; Chen, Jiaoyu; Mo, Weimin

    2014-05-15

    Esomeprazole analogs are a class of important proton pump inhibitors for the treatment of gastro-esophageal reflux diseases. Understanding the fragmentation reaction mechanism of the protonated esomeprazole analogs will facilitate the characterization of their complex metabolic fate in humans. In this paper, the kinetic method and theoretical calculations were applied to evaluate the fragmentation of protonated esomeprazole analogs. All collision-induced dissociation (CID) mass spectrometry experiments were carried out using electrospray ionization (ESI) ion trap mass spectrometry in positive ion mode. Also the accurate masses of fragments were measured on by ESI quadrupole time-of-flight (QTOF) MS in positive ion mode. Theoretical calculations were carried out by the density functional theory (DFT) method with the 6-31G(d) basis set in the Gaussian 03 program. In the fragmentation of the protonated esomeprazole analogs, C-S bond breakage is observed, which gives rise to protonated 2-(sulfinylmethylene)pyridines and protonated benzimidazoles. DFT calculations demonstrate that the nitrogen atom of the pyridine part is the thermodynamically most favorable protonation site, and the C-S bond cleavage is triggered by the transfer of this ionizing proton from the nitrogen atom of the pyridine part to the carbon atom of the benzimidazole part to which the sulfinyl is attached. Moreover, with the kinetic plot, the intensity ratios of two protonated product ions yield a linear relationship with the differences in proton affinities of the corresponding neutral molecules, which provides strong experimental evidence that the reaction proceeds via proton-bound 2-(sulfinylmethylene)pyridine/benzimidazole complex intermediates. The kinetic method combined with theoretical calculations was successfully applied to probe the proton transfer reaction by proton-bound 2-(sulfinylmethylene)pyridine/benzimidazole complexes in the fragmentation of protonated esomeprazole analogs by ESI

  2. Investigation of the dominant hydration structures among the ionic species in aqueous solution: Novel quantum mechanics/molecular mechanics simulations combined with the theory of energy representation

    NASA Astrophysics Data System (ADS)

    Takahashi, Hideaki; Ohno, Hajime; Yamauchi, Toshihiko; Kishi, Ryohei; Furukawa, Shin-ichi; Nakano, Masayoshi; Matubayasi, Nobuyuki

    2008-02-01

    In the present work, we have performed quantum chemical calculations to determine preferable species among the ionic complexes that are present in ambient water due to the autodissociation of water molecule. First, we have formulated the relative population of the hydrated complexes with respect to the bare ion (H3O+ or OH -) in terms of the solvation free energies of the relevant molecules. The solvation free energies for various ionic species (H3O+, H5O2+, H7O3+, H9O4+ or OH -, H3O2-, H5O3-, H7O4-, H9O5-), categorized as proton or hydroxide ion in solution, have been computed by employing the QM/MM-ER method recently developed by combining the quantum mechanical/molecular mechanical (QM/MM) approach with the theory of energy representation (ER). Then, the computed solvation free energies have been used to evaluate the ratio of the populations of the ionic complexes to that of the bare ion (H3O+ or OH -). Our results suggest that the Zundel form, i.e., H5O2+, is the most preferable in the solution among the cationic species listed above though the Eigen form (H9O4+) is very close to the Zundel complex in the free energy, while the anionic fragment from water molecules mostly takes the form of OH -. It has also been found that the loss of the translational entropy of water molecules associated with the formation of the complex plays a role in determining the preferable size of the cluster.

  3. Interpolation and Approximation Theory.

    ERIC Educational Resources Information Center

    Kaijser, Sten

    1991-01-01

    Introduced are the basic ideas of interpolation and approximation theory through a combination of theory and exercises written for extramural education at the university level. Topics treated are spline methods, Lagrange interpolation, trigonometric approximation, Fourier series, and polynomial approximation. (MDH)

  4. Adsorption of isophorone and trimethyl-cyclohexanone on Pd(111): A combination of infrared reflection absorption spectroscopy and density functional theory studies

    NASA Astrophysics Data System (ADS)

    Dostert, Karl-Heinz; O'Brien, Casey P.; Liu, Wei; Riedel, Wiebke; Savara, Aditya; Tkatchenko, Alexandre; Schauermann, Swetlana; Freund, Hans-Joachim

    2016-08-01

    Understanding the interaction of α,β-unsaturated carbonyl compounds with late transition metals is a key prerequisite for rational design of new catalysts with desired selectivity towards C = C or C = O bond hydrogenation. The interaction of the α,β-unsaturated ketone isophorone and the saturated ketone TMCH (3,3,5-trimethylcyclohexanone) with Pd(111) was investigated in this study as a prototypical system. Infrared reflection-absorption spectroscopy (IRAS) and density functional theory calculations including van der Waals interactions (DFT + vdWsurf) were combined to form detailed assignments of IR vibrational modes in the range from 3000 cm- 1 to 1000 cm- 1 in order to obtain information on the binding of isophorone and TMCH to Pd(111) as well as to study the effect of co-adsorbed hydrogen. IRAS measurements were performed with deuterium-labeled (d5-) isophorone, in addition to unlabeled isophorone and unlabeled TMCH. Experimentally observed IR absorption features and calculated vibrational frequencies indicate that isophorone and TMCH molecules in multilayers have a mostly unperturbed structure with random orientation. At sub-monolayer coverages, strong perturbation and preferred orientations of the adsorbates were found. At low coverage, isophorone interacts strongly with Pd(111) and adsorbs in a flat-lying geometry with the C = C and C = O bonds parallel, and a CH3 group perpendicular, to the surface. At intermediate sub-monolayer coverage, the C = C bond is strongly tilted, while the C = O bond remains flat-lying, which indicates a prominent perturbation of the conjugated π system. Pre-adsorbed hydrogen leads to significant changes in the adsorption geometry of isophorone, which suggests a weakening of its binding to Pd(111). At low coverage, the structure of the CH3 groups seems to be mostly unperturbed on the hydrogen pre-covered surface. With increasing coverage, a conservation of the in-plane geometry of the conjugated π system was observed in the

  5. Modelling the Factors that Affect Individuals' Utilisation of Online Learning Systems: An Empirical Study Combining the Task Technology Fit Model with the Theory of Planned Behaviour

    ERIC Educational Resources Information Center

    Yu, Tai-Kuei; Yu, Tai-Yi

    2010-01-01

    Understanding learners' behaviour, perceptions and influence in terms of learner performance is crucial to predict the use of electronic learning systems. By integrating the task-technology fit (TTF) model and the theory of planned behaviour (TPB), this paper investigates the online learning utilisation of Taiwanese students. This paper provides a…

  6. Combining Concept Maps and Interviews to Produce Representations of Personal Professional Theories in Higher Vocational Education: Effects of Order and Vocational Domain

    ERIC Educational Resources Information Center

    van den Bogaart, Antoine C. M.; Schaap, Harmen; Hummel, Hans G. K.; Kirschner, Paul A.

    2017-01-01

    This article presents the use of personal professional theories (PPTs) in Dutch higher vocational education. PPTs are internalised bodies of formal and practical knowledge and convictions that professionals use to direct their behaviour. With the aid of high-quality representations of students' PPTs teachers can access, monitor, and support the…

  7. Modelling the Factors that Affect Individuals' Utilisation of Online Learning Systems: An Empirical Study Combining the Task Technology Fit Model with the Theory of Planned Behaviour

    ERIC Educational Resources Information Center

    Yu, Tai-Kuei; Yu, Tai-Yi

    2010-01-01

    Understanding learners' behaviour, perceptions and influence in terms of learner performance is crucial to predict the use of electronic learning systems. By integrating the task-technology fit (TTF) model and the theory of planned behaviour (TPB), this paper investigates the online learning utilisation of Taiwanese students. This paper provides a…

  8. Adaptation of the Theodorsen theory to the representation of an airfoil as a combination of a lifting line and a thickness distribution

    NASA Technical Reports Server (NTRS)

    Barger, R. L.

    1975-01-01

    The theory provides a direct method for resolving an airfoil into a lifting line and a thickness distribution as well as a means of synthesizing thickness and lift components into a resultant airfoil and computing its aerodynamic characteristics. Specific applications of the technique are discussed.

  9. 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

  10. Structural and physicochemical properties of liquid Al-Zn alloys: a combined study based on molecular dynamics simulations and the quasi-lattice theory.

    PubMed

    Trybula, M; Jakse, N; Gasior, W; Pasturel, A

    2014-12-14

    Ordering phenomena have been investigated in liquid Al-Zn alloys performing molecular dynamics (MD) simulations using "empirical oscillating pair potentials." The local structural order is studied by computing two microscopic functions, namely, the concentration fluctuation function and the Warren-Cowley short-range order parameter. We also study the influence of ordering phenomena on transport properties like diffusivity and viscosity. The MD results are confronted to those determined from measurements and in the framework of the quasi-lattice theory.

  11. Investigation of the Abstraction and Dissociation Mechanism in the Nitrogen Trifluoride Channels: Combined Post-Hartree-Fock and Transition State Theory Approaches.

    PubMed

    Claudino, D; Gargano, R; Carvalho-Silva, Valter H; E Silva, Geraldo M; da Cunha, W F

    2016-07-21

    The present paper concludes our series of kinetics studies on the reactions involved in the complex mechanism of nitrogen trifluoride decomposition. Two other related reactions that, along with this mechanism, take part in an efficient boron nitride growth process are also investigated. We report results concerning two abstraction reactions, namely NF2 + N ⇄ 2NF and NF3 + NF ⇄ 2NF2, and two dissociations, N2F4 ⇄ 2NF2 and N2F3 ⇄ NF2 + NF. State-of-the-art electronic structure calculations at the CCSD(T)/cc-pVTZ level of theory were considered to determine geometries and frequencies of reactants, products, and transition states. Extrapolation of the energies to the complete basis set limit was used to obtain energies of all the species. We applied transition state theory to compute thermal rate constants including Wigner, Eckart, Bell, and deformed theory corrections in order to take tunneling effects into account. The obtained results are in good agreement with the experimental data available in the literature and are expected to provide a better phenomenological understanding of the NF3 decomposition role in the boron nitride growth for a wide range of temperature values.

  12. Interplay between tetrel and triel bonds in RC6H4CN⋯MF3CN⋯BX3 complexes: A combined symmetry-adapted perturbation theory, Møller-Plesset, and quantum theory of atoms-in-molecules study.

    PubMed

    Yourdkhani, Sirous; Korona, Tatiana; Hadipour, Nasser L

    2015-12-15

    Intermolecular ternary complexes composed of: (1) the centrally placed trifluoroacetonitrile or its higher analogs with central carbon exchanged by silicon or germanium (M = C, Si, Ge), (2) the benzonitrile molecule or its para derivatives on one side, and (3) the boron trifluoride of trichloride molecule (X = F, Cl) on the opposite side as well as the corresponding intermolecular tetrel- and triel-bonded binary complexes, were investigated by symmetry-adapted perturbation theory (SAPT) and the supermolecular Møller-Plesset method (MP2) at the complete basis set limit for optimized geometries. A character of interactions was studied by quantum theory of atoms-in-molecules (QTAIM). A comparison of interaction energies and QTAIM bond descriptors for dimers and trimers reveals that tetrel and triel bonds increase in their strength if present together in the trimer. For the triel-bonded complex, this growth leads to a change of the bond character from closed-shell to partly covalent for Si or Ge tetrel atoms, so the resulting bonding scheme corresponds to a preliminary stage of the SN2 reaction. Limitations of the Lewis theory of acids and bases were shown by its failure in predicting the stability order of the triel complexes. The necessity of including interaction energy terms beyond the electrostatic component for an elucidation of the nature of σ- and π-holes was presented by a SAPT energy decomposition and by a study of differences in monomer electrostatic potentials obtained either from isolated monomer densities, or from densities resulting from a perturbation with the effective field of another monomer.

  13. Development and validation of the coronary heart disease scale under the system of quality of life instruments for chronic diseases QLICD-CHD: combinations of classical test theory and Generalizability theory

    PubMed Central

    2014-01-01

    Background Quality of life (QOL) for patients with coronary heart disease (CHD) is now concerned worldwide with the specific instruments being seldom and no one developed by the modular approach. Objectives This paper is aimed to develop the CHD scale of the system of Quality of Life Instruments for Chronic Diseases (QLICD-CHD) by the modular approach and validate it by both classical test theory and Generalizability Theory. Methods The QLICD-CHD was developed based on programmed decision procedures with multiple nominal and focus group discussions, in-depth interview, pre-testing and quantitative statistical procedures. 146 inpatients with CHD were used to provide the data measuring QOL three times before and after treatments. The psychometric properties of the scale were evaluated with respect to validity, reliability and responsiveness employing correlation analysis, factor analyses, multi-trait scaling analysis, t-tests and also G studies and D studies of Genralizability Theory analysis. Results Multi-trait scaling analysis, correlation and factor analyses confirmed good construct validity and criterion-related validity when using SF-36 as a criterion. The internal consistency α and test-retest reliability coefficients (Pearson r and Intra-class correlations ICC) for the overall instrument and all domains were higher than 0.70 and 0.80 respectively; The overall and all domains except for social domain had statistically significant changes after treatments with moderate effect size SRM (standardized response mea) ranging from 0.32 to 0.67. G-coefficients and index of dependability (Ф coefficients) confirmed the reliability of the scale further with more exact variance components. Conclusions The QLICD-CHD has good validity, reliability, and moderate responsiveness and some highlights, and can be used as the quality of life instrument for patients with CHD. However, in order to obtain better reliability, the numbers of items for social domain should be

  14. Combining Flux Balance and Energy Balance Analysis for Large-Scale Metabolic Network: Biochemical Circuit Theory for Analysis of Large-Scale Metabolic Networks

    NASA Technical Reports Server (NTRS)

    Beard, Daniel A.; Liang, Shou-Dan; Qian, Hong; Biegel, Bryan (Technical Monitor)

    2001-01-01

    Predicting behavior of large-scale biochemical metabolic networks represents one of the greatest challenges of bioinformatics and computational biology. Approaches, such as flux balance analysis (FBA), that account for the known stoichiometry of the reaction network while avoiding implementation of detailed reaction kinetics are perhaps the most promising tools for the analysis of large complex networks. As a step towards building a complete theory of biochemical circuit analysis, we introduce energy balance analysis (EBA), which compliments the FBA approach by introducing fundamental constraints based on the first and second laws of thermodynamics. Fluxes obtained with EBA are thermodynamically feasible and provide valuable insight into the activation and suppression of biochemical pathways.

  15. Combining Adult Learning Theory with Occupational Therapy Intervention for Bladder and Bowel Management after Spinal Cord Injury: A Case Report.

    PubMed

    Gallagher, Gina; Bell, Alison

    2016-01-01

    Bladder and bowel management is an important goal of rehabilitation for clients with spinal cord injury. Dependence is these areas have been linked to a variety of secondary complications, including decreased quality of life, urinary tract infections and pressure ulcers (Hammell, 2010; Hicken et al, 2001). Occupational therapists have been identified as important members of the health care team in spinal cord injury rehabilitation; however, specific roles and interventions have not been clearly described. This case report will describe occupational therapy interventions embedded with principles of adult learning theory to address bladder and bowel management with an adult client who sustained an incomplete thoracic level spinal cord injury.

  16. Lunar phases, myocardial infarction and hemorrheological character. A Western medical study combined with appraisal of the related traditional Chinese medical theory.

    PubMed

    Sha, L R; Xu, N T; Song, X H; Zhang, L P; Zhang, Y

    1989-09-01

    Lunar phases and their connections with acute myocardial infarction (AMI) and hemorrheological character (HCh) are studied with the lunar calendar (LC) instead of the solar calendar. AMI onset is maximal on the 1st day of the LC month, decreasing with an obvious trough around the 15th day. After the 15th day, occurrence increases gradually. The end and beginning of the lunar months show sharp peaks of AMI incidence. This study shows also that HCh variations have similar LC monthly rhythms. Our investigation demonstrates the correctness of traditional Chinese medical theory. This monthly rhythm forecasts the onset of AMI peaks and contributes to the secondary prevention of coronary heart disease (CHD).

  17. Evaluation of protein-protein docking model structures using all-atom molecular dynamics simulations combined with the solution theory in the energy representation.

    PubMed

    Takemura, Kazuhiro; Guo, Hao; Sakuraba, Shun; Matubayasi, Nobuyuki; Kitao, Akio

    2012-12-07

    We propose a method to evaluate binding free energy differences among distinct protein-protein complex model structures through all-atom molecular dynamics simulations in explicit water using the solution theory in the energy representation. Complex model structures are generated from a pair of monomeric structures using the rigid-body docking program ZDOCK. After structure refinement by side chain optimization and all-atom molecular dynamics simulations in explicit water, complex models are evaluated based on the sum of their conformational and solvation free energies, the latter calculated from the energy distribution functions obtained from relatively short molecular dynamics simulations of the complex in water and of pure water based on the solution theory in the energy representation. We examined protein-protein complex model structures of two protein-protein complex systems, bovine trypsin/CMTI-1 squash inhibitor (PDB ID: 1PPE) and RNase SA/barstar (PDB ID: 1AY7), for which both complex and monomer structures were determined experimentally. For each system, we calculated the energies for the crystal complex structure and twelve generated model structures including the model most similar to the crystal structure and very different from it. In both systems, the sum of the conformational and solvation free energies tended to be lower for the structure similar to the crystal. We concluded that our energy calculation method is useful for selecting low energy complex models similar to the crystal structure from among a set of generated models.

  18. Global Uncertainty Propagation and Sensitivity Analysis in the CH3OCH2 + O2 System: Combining Experiment and Theory To Constrain Key Rate Coefficients in DME Combustion.

    PubMed

    Shannon, R J; Tomlin, A S; Robertson, S H; Blitz, M A; Pilling, M J; Seakins, P W

    2015-07-16

    Statistical rate theory calculations, in particular formulations of the chemical master equation, are widely used to calculate rate coefficients of interest in combustion environments as a function of temperature and pressure. However, despite the increasing accuracy of electronic structure calculations, small uncertainties in the input parameters for these master equation models can lead to relatively large uncertainties in the calculated rate coefficients. Master equation input parameters may be constrained further by using experimental data and the relationship between experiment and theory warrants further investigation. In this work, the CH3OCH2 + O2 system, of relevance to the combustion of dimethyl ether (DME), is used as an example and the input parameters for master equation calculations on this system are refined through fitting to experimental data. Complementing these fitting calculations, global sensitivity analysis is used to explore which input parameters are constrained by which experimental conditions, and which parameters need to be further constrained to accurately predict key elementary rate coefficients. Finally, uncertainties in the calculated rate coefficients are obtained using both correlated and uncorrelated distributions of input parameters.

  19. Comment on Pisarenko et al., "Characterization of the Tail of the Distribution of Earthquake Magnitudes by Combining the GEV and GPD Descriptions of Extreme Value Theory"

    NASA Astrophysics Data System (ADS)

    Raschke, Mathias

    2016-02-01

    In this short note, I comment on the research of Pisarenko et al. (Pure Appl. Geophys 171:1599-1624, 2014) regarding the extreme value theory and statistics in the case of earthquake magnitudes. The link between the generalized extreme value distribution (GEVD) as an asymptotic model for the block maxima of a random variable and the generalized Pareto distribution (GPD) as a model for the peaks over threshold (POT) of the same random variable is presented more clearly. Inappropriately, Pisarenko et al. (Pure Appl. Geophys 171:1599-1624, 2014) have neglected to note that the approximations by GEVD and GPD work only asymptotically in most cases. This is particularly the case with truncated exponential distribution (TED), a popular distribution model for earthquake magnitudes. I explain why the classical models and methods of the extreme value theory and statistics do not work well for truncated exponential distributions. Consequently, these classical methods should be used for the estimation of the upper bound magnitude and corresponding parameters. Furthermore, I comment on various issues of statistical inference in Pisarenko et al. and propose alternatives. I argue why GPD and GEVD would work for various types of stochastic earthquake processes in time, and not only for the homogeneous (stationary) Poisson process as assumed by Pisarenko et al. (Pure Appl. Geophys 171:1599-1624, 2014). The crucial point of earthquake magnitudes is the poor convergence of their tail distribution to the GPD, and not the earthquake process over time.

  20. Application of the IAS theory combining to a three compartments description of natural organic matter to the adsorption of atrazine or diuron on activated carbon.

    PubMed

    Baudu, M; Raveau, D; Guibaud, G

    2004-07-01

    The study of natural organic matter (NOM) adsorption on an activated carbon showed that equilibrium cannot be described according to a simple model such as a Freundlich isotherm and confirms the need for a closer description of the organic matter to simulate the competitive adsorption with micropollutants. A representation of the organic matter in three fractions is chosen: non-adsorbable, weak and strong adsorbable. The Ideal Adsorbed Solution Theory (IAST) can, under restrictive conditions, be used to effectively predict the competition between the pesticides and the organic matter. Therefore, it was noted that the model simulated with good precision the competition between atrazine or diuron and natural organic matter in aqueous solution for two activated carbons (A and B). The same parameters for the modeling of organic matter adsorption (Freudlich constants for two absorbable fractions) are used with the two pesticides. However, IAST does not allow correct modeling of pesticide adsorption onto two other (C and D) activated carbons in solution in natural water to be described. IAS theory does not reveal competition between diuron and NOM and pore blockage mechanism by the NOM is proposed as the major effect for the adsorption capacity reduction. However, the difference observed between the two pesticides could be due to in addition to the pore blockage effect, a particular phenomenon with the diuron, especially with D activated carbon. We can suppose specific interactions between the diuron and the adsorbed organic matter and a competition between adsorption sites of NOM and activated carbon surface.

  1. Combined application of information theory on laboratory results with classification and regression tree analysis: analysis of unnecessary biopsy for prostate cancer.

    PubMed

    Hwang, Sang-Hyun; Pyo, Tina; Oh, Heung-Bum; Park, Hyun Jun; Lee, Kwan-Jeh

    2013-01-16

    The probability of a prostate cancer-positive biopsy result varies with PSA concentration. Thus, we applied information theory on classification and regression tree (CART) analysis for decision making predicting the probability of a biopsy result at various PSA concentrations. From 2007 to 2009, prostate biopsies were performed in 664 referred patients in a tertiary hospital. We created 2 CART models based on the information theory: one for moderate uncertainty (PSA concentration: 2.5-10 ng/ml) and the other for high uncertainty (PSA concentration: 10-25 ng/ml). The CART model for moderate uncertainty (n=321) had 3 splits based on PSA density (PSAD), hypoechoic nodules, and age and the other CART for high uncertainty (n=160) had 2 splits based on prostate volume and percent-free PSA. In this validation set, the patients (14.3% and 14.0% for moderate and high uncertainty groups, respectively) could avoid unnecessary biopsies without false-negative results. Using these CART models based on uncertainty information of PSA, the overall reduction in unnecessary prostate biopsies was 14.0-14.3% and CART models were simplified. Using uncertainty of laboratory results from information theoretic approach can provide additional information for decision analysis such as CART. Copyright © 2012 Elsevier B.V. All rights reserved.

  2. Theory and social practice of agency in combining breastfeeding and employment: A qualitative study among health workers in New Delhi, India.

    PubMed

    Omer-Salim, Amal; Suri, Shobha; Dadhich, Jai Prakash; Faridi, Mohammad Moonis Akbar; Olsson, Pia

    2014-12-01

    Women's agency, or intentional actions, in combining breastfeeding and employment is significant for health and labour productivity. Previous research in India showed that mothers use various collaborative strategies to ensure a "good enough" combination of breastfeeding and employment. Bandura's theoretical agency constructs previously applied in various realms could facilitate the exploration of agency in an Indian context. To explore manifestations of agency in combining breastfeeding and employment amongst Indian health workers using Bandura's theoretical constructs of agency and women's experiences. Qualitative semi-structured interviews were conducted with ten women employees within the governmental health sector in New Delhi, India. Both deductive and inductive qualitative content analyses were used. Bandura's features and modes of agency revealed that intentionality is underpinned by knowledge, forethought means being prepared, self-reactiveness includes collaboration and that self-reflectiveness gives perspective. Women's interviews revealed four approaches to agency entitled: 'All within my stride or the knowledgeable navigator'; 'Much harder than expected, but ok overall'; This is a very lonely job'; and 'Out of my control'. Agency features and their elements are complex, dynamic and involve family members. Bandura's theoretical agency constructs are partially useful in this context, but additional social practice constructs of family structure and relationship quality are needed for better correspondence with women's experiences of agency. The variation in individual approaches to agency has implications for supportive health and workplace services. Copyright © 2014 Australian College of Midwives. Published by Elsevier Ltd. All rights reserved.

  3. Adatom Extraction from Pristine Metal Terraces by Dissociative Oxygen Adsorption: Combined STM and Density Functional Theory Investigation of O/Ag(110).

    PubMed

    Pal, Jagriti; Rawal, Takat B; Smerieri, Marco; Hong, Sampyo; Alatalo, Matti; Savio, Letizia; Vattuone, Luca; Rahman, Talat S; Rocca, Mario

    2017-06-02

    The reconstruction and modification of metal surfaces upon O_{2} adsorption plays an important role in oxidation processes and in gauging their catalytic activity. Here, we show by employing scanning tunneling microscopy and the ab initio density functional theory that Ag atoms are extracted from pristine (110) terraces upon O_{2} dissociation, resulting in vacancies and in Ag-O complexes. The substrate roughening generates undercoordinated atoms and opens pathways to the Ag subsurface layer. With increasing O coverage, multiple vacancies give rise to remarkable structures. The mechanism is expected to be very general depending on the delicate interplay of energy and entropy, so that it may be active for other materials at different temperatures.

  4. Adatom Extraction from Pristine Metal Terraces by Dissociative Oxygen Adsorption: Combined STM and Density Functional Theory Investigation of O /Ag (110 )

    NASA Astrophysics Data System (ADS)

    Pal, Jagriti; Rawal, Takat B.; Smerieri, Marco; Hong, Sampyo; Alatalo, Matti; Savio, Letizia; Vattuone, Luca; Rahman, Talat S.; Rocca, Mario

    2017-06-01

    The reconstruction and modification of metal surfaces upon O2 adsorption plays an important role in oxidation processes and in gauging their catalytic activity. Here, we show by employing scanning tunneling microscopy and the ab initio density functional theory that Ag atoms are extracted from pristine (110) terraces upon O2 dissociation, resulting in vacancies and in Ag-O complexes. The substrate roughening generates undercoordinated atoms and opens pathways to the Ag subsurface layer. With increasing O coverage, multiple vacancies give rise to remarkable structures. The mechanism is expected to be very general depending on the delicate interplay of energy and entropy, so that it may be active for other materials at different temperatures.

  5. A Combined Density Functional Theory and Spectrophotometry Study of the Bonding Interactions of [NpO2·M]4+ Cation–Cation Complexes

    DOE PAGES

    Freiderich, John W.; Burn, Adam G.; Martin, Leigh R.; ...

    2017-04-14

    The equilibrium constants for [NpO2M∙]4+ (M = Al3+, In3+, Sc3+, Fe3+) in μ = 10 M nitric acid and [NpO2∙Ga]4+ in μ = 10 M hydrochloric acid media have been determined. The trend in the interaction strength follows: Fe3+ > Sc3+ In3+ > Ga3+ Al3+. These equilibrium constants are compared to those of previously reported values for NpO2+ complexes with Cr3+ and Rh3+ within the literature. Thermodynamic parameters and bonding modes are discussed, with density functional theory and natural bond orbital analysis indicating that the NpO2+ dioxocation acts as a -donor with transition-metal cations and a sigma donor with groupmore » 13 cations. The small changes in electron-donating ability is modulated by the overlap with the coordinating metal ion's valence atomic orbitals.« less

  6. Atomic motions in poly(vinyl methyl ether): A combined study by quasielastic neutron scattering and molecular dynamics simulations in the light of the mode coupling theory.

    PubMed

    Capponi, S; Arbe, A; Alvarez, F; Colmenero, J; Frick, B; Embs, J P

    2009-11-28

    Quasielastic neutron scattering experiments (time-of-flight, neutron spin echo, and backscattering) on protonated poly(vinyl methyl ether) (PVME) have revealed the hydrogen dynamics above the glass-transition temperature. Fully atomistic molecular dynamics simulations properly validated with the neutron scattering results have allowed further characterization of the atomic motions accessing the correlation functions directly in real space. Deviations from Gaussian behavior are found in the high-momentum transfer range, which are compatible with the predictions of mode coupling theory (MCT). We have applied the MCT phenomenological version to the self-correlation functions of PVME atoms calculated from our simulation data, obtaining consistent results. The unusually large value found for the lambda-exponent parameter is close to that recently reported for polybutadiene and simple polymer models with intramolecular barriers.

  7. The Shared Decision Making Frontier: a Feasibility and Usability Study for Managing Non-Critical Chronic Illness by Combining Behavioural & Decision Theory with Online Technology.

    PubMed

    Russell, Amina; Van Woensel, William; Abidi, Samina Raza

    2015-01-01

    The objective of this study is to determine if shared decisions for managing non-critical chronic illness, made through an online biomedical technology intervention, us feasible and usable. The technology intervention incorporates behavioural and decision theories to increase patient engagement, and ultimately long term adherence to health behaviour change. We devised the iheart web intervention as a "proof of concept" in five phases. The implementation incorporates the Vaadin web application framework, Drools, EclipseLink and a MySQL database. Two-thirds of the study participants favoured the technology intervention, based on Likert-scale questions from a post-study questionnaire. Qualitative analysis of think aloud feedback, video screen captures and open-ended questions from the post-study questionnaire uncovered six main areas or themes for improvement. We conclude that online shared decisions for managing a non-critical chronic illness are feasible and usable through the iheart web intervention.

  8. Anisotropic pair correlations in binary and multicomponent hard-sphere mixtures in the vicinity of a hard wall: A combined density functional theory and simulation study.

    PubMed

    Härtel, Andreas; Kohl, Matthias; Schmiedeberg, Michael

    2015-10-01

    The fundamental measure approach to classical density functional theory has been shown to be a powerful tool to predict various thermodynamic properties of hard-sphere systems. We employ this approach to determine not only one-particle densities but also two-particle correlations in binary and six-component mixtures of hard spheres in the vicinity of a hard wall. The broken isotropy enables us to carefully test a large variety of theoretically predicted two-particle features by quantitatively comparing them to the results of Brownian dynamics simulations. Specifically, we determine and compare the one-particle density, the total correlation functions, their contact values, and the force distributions acting on a particle. For this purpose, we follow the compressibility route and theoretically calculate the direct correlation functions by taking functional derivatives. We usually observe an excellent agreement between theory and simulations, except for small deviations in cases where local crystal-like order sets in. Our results set the course for further investigations on the consistency of functionals as well as for structural analysis on, e.g., the primitive model. In addition, we demonstrate that due to the suppression of local crystallization, the predictions of six-component mixtures are better than those in bidisperse or monodisperse systems. Finally, we are confident that our results of the structural modulations induced by the wall lead to a deeper understanding of ordering in anisotropic systems in general, the onset of heterogeneous crystallization, caging effects, and glassy dynamics close to a wall, as well as structural properties in systems with confinement.

  9. Anisotropic pair correlations in binary and multicomponent hard-sphere mixtures in the vicinity of a hard wall: A combined density functional theory and simulation study

    NASA Astrophysics Data System (ADS)

    Härtel, Andreas; Kohl, Matthias; Schmiedeberg, Michael

    2015-10-01

    The fundamental measure approach to classical density functional theory has been shown to be a powerful tool to predict various thermodynamic properties of hard-sphere systems. We employ this approach to determine not only one-particle densities but also two-particle correlations in binary and six-component mixtures of hard spheres in the vicinity of a hard wall. The broken isotropy enables us to carefully test a large variety of theoretically predicted two-particle features by quantitatively comparing them to the results of Brownian dynamics simulations. Specifically, we determine and compare the one-particle density, the total correlation functions, their contact values, and the force distributions acting on a particle. For this purpose, we follow the compressibility route and theoretically calculate the direct correlation functions by taking functional derivatives. We usually observe an excellent agreement between theory and simulations, except for small deviations in cases where local crystal-like order sets in. Our results set the course for further investigations on the consistency of functionals as well as for structural analysis on, e.g., the primitive model. In addition, we demonstrate that due to the suppression of local crystallization, the predictions of six-component mixtures are better than those in bidisperse or monodisperse systems. Finally, we are confident that our results of the structural modulations induced by the wall lead to a deeper understanding of ordering in anisotropic systems in general, the onset of heterogeneous crystallization, caging effects, and glassy dynamics close to a wall, as well as structural properties in systems with confinement.

  10. Reaction rate constant of CH2O + H = HCO + H2 revisited: a combined study of direct shock tube measurement and transition state theory calculation.

    PubMed

    Wang, Shengkai; Dames, Enoch E; Davidson, David F; Hanson, Ronald K

    2014-11-06

    The rate constant of the H-abstraction reaction of formaldehyde (CH2O) by hydrogen atoms (H), CH2O + H = H2 + HCO, has been studied behind reflected shock waves with use of a sensitive mid-IR laser absorption diagnostic for CO, over temperatures of 1304-2006 K and at pressures near 1 atm. C2H5I was used as an H atom precursor and 1,3,5-trioxane as the CH2O precursor, to generate a well-controlled CH2O/H reacting system. By designing the experiments to maintain relatively constant H atom concentrations, the current study significantly boosted the measurement sensitivity of the target reaction and suppressed the influence of interfering reactions. The measured CH2O + H rate constant can be expressed in modified Arrhenius from as kCH2O+H(1304-2006 K, 1 atm) = 1.97 × 10(11)(T/K)(1.06) exp(-3818 K/T) cm(3) mol(-1)s(-1), with uncertainty limits estimated to be +18%/-26%. A transition-state-theory (TST) calculation, using the CCSD(T)-F12/VTZ-F12 level of theory, is in good agreement with the shock tube measurement and extended the temperature range of the current study to 200-3000 K, over which a modified Arrhenius fit of the rate constant can be expressed as kCH2O+H(200-3000 K) = 5.86 × 10(3)(T/K)(3.13) exp(-762 K/T) cm(3) mol(-1)s(-1).

  11. Combining Theory-Driven Evaluation and Causal Loop Diagramming for Opening the 'Black Box' of an Intervention in the Health Sector: A Case of Performance-Based Financing in Western Uganda.

    PubMed

    Renmans, Dimitri; Holvoet, Nathalie; Criel, Bart

    2017-09-03

    Increased attention on "complexity" in health systems evaluation has resulted in many different methodological responses. Theory-driven evaluations and systems thinking are two such responses that aim for better understanding of the mechanisms underlying given outcomes. Here, we studied the implementation of a performance-based financing intervention by the Belgian Technical Cooperation in Western Uganda to illustrate a methodological strategy of combining these two approaches. We utilized a systems dynamics tool called causal loop diagramming (CLD) to generate hypotheses feeding into a theory-driven evaluation. Semi-structured interviews were conducted with 30 health workers from two districts (Kasese and Kyenjojo) and with 16 key informants. After CLD, we identified three relevant hypotheses: "success to the successful", "growth and underinvestment", and "supervision conundrum". The first hypothesis leads to increasing improvements in performance, as better performance leads to more incentives, which in turn leads to better performance. The latter two hypotheses point to potential bottlenecks. Thus, the proposed methodological strategy was a useful tool for identifying hypotheses that can inform a theory-driven evaluation. The hypotheses are represented in a comprehensible way while highlighting the underlying assumptions, and are more easily falsifiable than hypotheses identified without using CLD.

  12. On the Buckling of Imperfect Anisotropic Shells with Elastic Edge Supports Under Combined Loading Part I:. Pt. 1; Theory and Numerical Analysis

    NASA Technical Reports Server (NTRS)

    Arbocz, Johann; deVries, J.; Hol, J. M. A. M.

    1998-01-01

    A rigorous solution is presented for the case of stiffened anisotropic cylindrical shells with general imperfections under combined loading, where the edge supports are provided by symmetrical or unsymmetrical elastic rings. The circumferential dependence is eliminated by a truncated Fourier series. The resulting nonlinear 2-point boundary value problem is solved numerically via the "Parallel Shooting Method". The changing deformation patterns resulting from the different degrees of interaction between the given initial imperfections and the specified end rings are displayed. Recommendations are made as to the minimum ring stiffnesses required for optimal load carrying configurations.

  13. Quantum Mechanics/Molecular Mechanics Method Combined with Hybrid All-Atom and Coarse-Grained Model: Theory and Application on Redox Potential Calculations.

    PubMed

    Shen, Lin; Yang, Weitao

    2016-04-12

    We developed a new multiresolution method that spans three levels of resolution with quantum mechanical, atomistic molecular mechanical, and coarse-grained models. The resolution-adapted all-atom and coarse-grained water model, in which an all-atom structural description of the entire system is maintained during the simulations, is combined with the ab initio quantum mechanics and molecular mechanics method. We apply this model to calculate the redox potentials of the aqueous ruthenium and iron complexes by using the fractional number of electrons approach and thermodynamic integration simulations. The redox potentials are recovered in excellent accordance with the experimental data. The speed-up of the hybrid all-atom and coarse-grained water model renders it computationally more attractive. The accuracy depends on the hybrid all-atom and coarse-grained water model used in the combined quantum mechanical and molecular mechanical method. We have used another multiresolution model, in which an atomic-level layer of water molecules around redox center is solvated in supramolecular coarse-grained waters for the redox potential calculations. Compared with the experimental data, this alternative multilayer model leads to less accurate results when used with the coarse-grained polarizable MARTINI water or big multipole water model for the coarse-grained layer.

  14. Effect of metal in M3(btc)2 and M2(dobdc) MOFs for O2/N2 separations: A combined density functional theory and experimental study

    DOE PAGES

    Parkes, Marie V.; Sava Gallis, Dorina F.; Greathouse, Jeffery A.; ...

    2015-03-02

    Computational screening of metal-organic framework (MOF) materials for selective oxygen adsorption from air could lead to new sorbents for the oxyfuel combustion process feedstock streams. A comprehensive study on the effect of MOF metal chemistry on gas binding energies in two common but structurally disparate metal-organic frameworks has been undertaken. Dispersion-corrected density functional theory methods were used to calculate the oxygen and nitrogen binding energies with each of fourteen metals, respectively, substituted into two MOF series, M2(dobdc) and M3(btc)2. The accuracy of DFT methods was validated by comparing trends in binding energy with experimental gas sorption measurements. A periodic trendmore » in oxygen binding energies was found, with greater oxygen binding energies for early transition-metal-substituted MOFs compared to late transition metal MOFs; this was independent of MOF structural type. The larger binding energies were associated with oxygen binding in a side-on configuration to the metal, with concomitant lengthening of the O-O bond. In contrast, nitrogen binding energies were similar across the transition metal series, regardless of both MOF structural type and metal identity. Altogether, these findings suggest that early transition metal MOFs are best suited to separating oxygen from nitrogen, and that the MOF structural type is less important than the metal identity.« less

  15. Thermal stability of mullite RMn₂O₅ (R  =  Bi, Y, Pr, Sm or Gd): combined density functional theory and experimental study.

    PubMed

    Li, Chenzhe; Thampy, Sampreetha; Zheng, Yongping; Kweun, Joshua M; Ren, Yixin; Chan, Julia Y; Kim, Hanchul; Cho, Maenghyo; Kim, Yoon Young; Hsu, Julia W P; Cho, Kyeongjae

    2016-03-31

    Understanding and effectively predicting the thermal stability of ternary transition metal oxides with heavy elements using first principle simulations are vital for understanding performance of advanced materials. In this work, we have investigated the thermal stability of mullite RMn2O5 (R  =  Bi, Pr, Sm, or Gd) structures by constructing temperature phase diagrams using an efficient mixed generalized gradient approximation (GGA) and the GGA  +  U method. Simulation predicted stability regions without corrections on heavy elements show a 4-200 K underestimation compared to our experimental results. We have found the number of d/f electrons in the heavy elements shows a linear relationship with the prediction deviation. Further correction on the strongly correlated electrons in heavy elements could significantly reduce the prediction deviations. Our corrected simulation results demonstrate that further correction of R-site elements in RMn2O5 could effectively reduce the underestimation of the density functional theory-predicted decomposition temperature to within 30 K. Therefore, it could produce an accurate thermal stability prediction for complex ternary transition metal oxide compounds with heavy elements.

  16. Thermal stability of mullite RMn2O5 (R  =  Bi, Y, Pr, Sm or Gd): combined density functional theory and experimental study

    NASA Astrophysics Data System (ADS)

    Li, Chenzhe; Thampy, Sampreetha; Zheng, Yongping; Kweun, Joshua M.; Ren, Yixin; Chan, Julia Y.; Kim, Hanchul; Cho, Maenghyo; Kim, Yoon Young; Hsu, Julia W. P.; Cho, Kyeongjae

    2016-03-01

    Understanding and effectively predicting the thermal stability of ternary transition metal oxides with heavy elements using first principle simulations are vital for understanding performance of advanced materials. In this work, we have investigated the thermal stability of mullite RMn2O5 (R  =  Bi, Pr, Sm, or Gd) structures by constructing temperature phase diagrams using an efficient mixed generalized gradient approximation (GGA) and the GGA  +  U method. Simulation predicted stability regions without corrections on heavy elements show a 4-200 K underestimation compared to our experimental results. We have found the number of d/f electrons in the heavy elements shows a linear relationship with the prediction deviation. Further correction on the strongly correlated electrons in heavy elements could significantly reduce the prediction deviations. Our corrected simulation results demonstrate that further correction of R-site elements in RMn2O5 could effectively reduce the underestimation of the density functional theory-predicted decomposition temperature to within 30 K. Therefore, it could produce an accurate thermal stability prediction for complex ternary transition metal oxide compounds with heavy elements.

  17. Relativistic Zeroth-Order Regular Approximation Combined with Nonhybrid and Hybrid Density Functional Theory: Performance for NMR Indirect Nuclear Spin-Spin Coupling in Heavy Metal Compounds.

    PubMed

    Moncho, Salvador; Autschbach, Jochen

    2010-01-12

    A benchmark study for relativistic density functional calculations of NMR spin-spin coupling constants has been performed. The test set contained 47 complexes with heavy metal atoms (W, Pt, Hg, Tl, Pb) with a total of 88 coupling constants involving one or two heavy metal atoms. One-, two-, three-, and four-bond spin-spin couplings have been computed at different levels of theory (nonhybrid vs hybrid DFT, scalar vs two-component relativistic). The computational model was based on geometries fully optimized at the BP/TZP scalar relativistic zeroth-order regular approximation (ZORA) and the conductor-like screening model (COSMO) to include solvent effects. The NMR computations also employed the continuum solvent model. Computations in the gas phase were performed in order to assess the importance of the solvation model. The relative median deviations between various computational models and experiment were found to range between 13% and 21%, with the highest-level computational model (hybrid density functional computations including scalar plus spin-orbit relativistic effects, the COSMO solvent model, and a Gaussian finite-nucleus model) performing best.

  18. Self-Consistent Determination of Atomic Charges of Ionic Liquid through a Combination of Molecular Dynamics Simulation and Density Functional Theory.

    PubMed

    Ishizuka, Ryosuke; Matubayasi, Nobuyuki

    2016-02-09

    A self-consistent scheme is developed to determine the atomic partial charges of ionic liquid. Molecular dynamics (MD) simulation was conducted to sample a set of ion configurations, and these configurations were subject to density functional theory (DFT) calculations to determine the partial charges. The charges were then averaged and used as inputs for the subsequent MD simulation, and MD and DFT calculations were repeated until the MD results are not altered any more. We applied this scheme to 1,3-dimethylimidazolium bis(trifluoromethylsulfonyl) imide ([C1mim][NTf2]) and investigated its structure and dynamics as a function of temperature. At convergence, the average ionic charges were ±0.84 e at 350 K due to charge transfer among ions, where e is the elementary charge, while the reduced ionic charges do not affect strongly the density of [C1mim][NTf2] and radial distribution function. Instead, major effects are found on the energetics and dynamics, with improvements of the overestimated heat of vaporization and the too slow motions of ions observed in MD simulations using commonly used force fields.

  19. Influence of atomic tip structure on the intensity of inelastic tunneling spectroscopy data analyzed by combined scanning tunneling spectroscopy, force microscopy, and density functional theory

    NASA Astrophysics Data System (ADS)

    Okabayashi, Norio; Gustafsson, Alexander; Peronio, Angelo; Paulsson, Magnus; Arai, Toyoko; Giessibl, Franz J.

    2016-04-01

    Achieving a high intensity in inelastic scanning tunneling spectroscopy (IETS) is important for precise measurements. The intensity of the IETS signal can vary by up to a factor of 3 for various tips without an apparent reason accessible by scanning tunneling microscopy (STM) alone. Here, we show that combining STM and IETS with atomic force microscopy enables carbon monoxide front-atom identification, revealing that high IETS intensities for CO/Cu(111) are obtained for single-atom tips, while the intensity drops sharply for multiatom tips. Adsorption of the CO molecule on a Cu adatom [CO/Cu/Cu(111)] such that the molecule is elevated over the substrate strongly diminishes the tip dependence of IETS intensity, showing that an elevated position channels most of the tunneling current through the CO molecule even for multiatom tips, while a large fraction of the tunneling current bypasses the CO molecule in the case of CO/Cu(111).

  20. Identification of novel histone deacetylase 1 inhibitors by combined pharmacophore modeling, 3D-QSAR analysis, in silico screening and Density Functional Theory (DFT) approaches

    NASA Astrophysics Data System (ADS)

    Choubey, Sanjay K.; Mariadasse, Richard; Rajendran, Santhosh; Jeyaraman, Jeyakanthan

    2016-12-01

    Overexpression of HDAC1, a member of Class I histone deacetylase is reported to be implicated in breast cancer. Epigenetic alteration in carcinogenesis has been the thrust of research for few decades. Increased deacetylation leads to accelerated cell proliferation, cell migration, angiogenesis and invasion. HDAC1 is pronounced as the potential drug target towards the treatment of breast cancer. In this study, the biochemical potential of 6-aminonicotinamide derivatives was rationalized. Five point pharmacophore model with one hydrogen-bond acceptor (A3), two hydrogen-bond donors (D5, D6), one ring (R12) and one hydrophobic group (H8) was developed using 6-aminonicotinamide derivatives. The pharmacophore hypothesis yielded a 3D-QSAR model with correlation-coefficient (r2 = 0.977, q2 = 0.801) and it was externally validated with (r2pred = 0.929, r2cv = 0.850 and r2m = 0.856) which reveals the statistical significance of the model having high predictive power. The model was then employed as 3D search query for virtual screening against compound libraries (Zinc, Maybridge, Enamine, Asinex, Toslab, LifeChem and Specs) in order to identify novel scaffolds which can be experimentally validated to design future drug molecule. Density Functional Theory (DFT) at B3LYP/6-31G* level was employed to explore the electronic features of the ligands involved in charge transfer reaction during receptor ligand interaction. Binding free energy (ΔGbind) calculation was done using MM/GBSA which defines the affinity of ligands towards the receptor.

  1. The spectroscopic (FT-IR, FT-Raman, dispersive Raman and NMR) study of ethyl-6-chloronicotinate molecule by combined density functional theory.

    PubMed

    Karabacak, Mehmet; Calisir, Zuhre; Kurt, Mustafa; Kose, Etem; Atac, Ahmet

    2016-01-15

    In this study, ethyl-6-chloronicotinate (E-6-ClN) molecule is recorded in the region 4000-400 cm(-1) and 3500-100 cm(-1) (FT-IR, FT-Raman and dispersive Raman, respectively) in the solid phase. ((1))H and ((13))C nuclear magnetic resonance (NMR) spectra are recorded in DMSO solution. The structural and spectroscopic data of the molecule are obtained for two possible isomers (S1 and S2) from DFT (B3LYP) with 6-311++G(d,p) basis set calculations. The geometry of the molecule is fully optimized, vibrational spectra are calculated and fundamental vibrations are assigned on the basis of the potential energy distribution (PED) of the vibrational modes. ((1))H and ((13))C NMR chemical shifts are calculated by using the gauge-invariant atomic orbital (GIAO) method. The electronic properties, such as excitation energies, oscillator strengths, wavelengths, HOMO and LUMO energies, are performed by time-dependent density functional theory (TD-DFT). Total and partial density of state and overlap population density of state diagrams analysis are presented for E-6-ClN molecule. Furthermore, frontier molecular orbitals (FMO), molecular electrostatic potential, and thermodynamic features are performed. In addition to these, reduced density gradient of the molecule is performed and discussed. As a conclusion, the calculated results are compared with the experimental spectra of the title compound. The results of the calculations are applied to simulate the vibrational spectra of the molecule, which show excellent agreement with the observed ones. The theoretical and tentative results will give us a detailed description of the structural and physicochemical properties of the molecule. Natural bond orbital analysis is done to have more information stability of the molecule arising from charge delocalization, and to reveal the information regarding charge transfer within the molecules. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Positively charged carbon vacancy in three inequivalent lattice sites of 6H-SiC: Combined EPR and density functional theory study

    SciTech Connect

    Bratus', V.Ya.; Petrenko, T.T.; Okulov, S.M.; Petrenko, T.L.

    2005-03-15

    The Ky1, Ky2, and Ky3 centers are the dominant defects produced in the electron-irradiated p-type 6H-SiC crystals. The electron paramagnetic resonance study of these defects has been performed in the temperature range of 4.2-300 K at X, K, and Q bands. The centers are characterized by the fourfold silicon coordination established on a basis of the observed hyperfine structure. At low temperatures both Ky1 and Ky2 defects reveal the C{sub S} symmetry that only slightly deviates from the D{sub 2d} one. At high temperatures, the thermally activated reorientation from one Jahn-Teller distortion to the others causes the averaging of the Ky1 and Ky2 spectra in such a manner that their spin-Hamiltonians correspond to the axial symmetry. The Ky3 center has axial symmetry in all the temperature range under investigation. Its hyperfine parameters for the first-shell silicon atoms are substantially different from those determined for the Ky1 and Ky2 centers. Based on the density functional theory, the calculations of the electronic structure of a number of fourfold silicon coordinated defects have been carried out for the unambiguous identification of the observed defects through the comparison of experimentally determined and calculated hyperfine parameters. The present study proves an assignment of the Ky1, Ky2, and Ky3 centers to the positively charged carbon vacancy located in two quasicubic and hexagonal sites of the 6H-SiC lattice, respectively. The features of the V{sub C}{sup +} defect related to the multivalley character of its potential energy surface are also discussed. It is shown that this defect can be localized in the minima of different symmetry depending on the occupied lattice site, and these minima are experimentally distinguishable by the values of hyperfine parameters.

  3. Healing outcomes of MRSA-infected wounds with a protocol combining Oakin dressing with elements of the de-escalation theory.

    PubMed

    Graham, G S

    2014-02-01

    This paper presents a novel wound healing protocol for the treatment of MRSA-infected lower extremity wounds of various etiologies, and describes the healing rate at 30, 60 and 90 days. A total of 40 participants with singular wounds were enrolled and treated with a specially designed protocol, which involves elements of the de-escalation theory together with a wound dress containing Oakin, in a private practice setting or a wound care center. The primary endpoint was the number of participants who achieved wound closure at 90 days. Data analysed and collected included wound etiology, wound size, gender, healing time by setting, and days to heal overall. Due to the anticipated small cohort of wound types, several statistical calculations were considered, including one-way ANOVA, Pearson correlation, and Levene's test. All wounds were classified by etiology: 58% (n=23), diabetic neuropathic ulcers (DNU), 25% (n=10) venous insufficiency ulcers (VU), and 17% (n=7) pressure ulcers (PU). Overall, 35% (n=14) healed within 30 days (22.14 ± 4.47), 60% (n=24) healed in 60 days (31.76 ± 13.02), and 78% (n=31) healed in 90 days (40.81 ± 22.23). After 90 days, the remaining 23% (n=9) of participants were no longer followed. This clinical evaluation demonstrated the overall effectiveness of this treatment protocol by attaining nearly 80% wound closure within 90 days. This protocol is intended to provide a roadmap for clinicians to follow and adapt to their wound care practice should a high prevalence of MRSA-infected wounds be present. The author has disclosed that he has worked doing clinical case studies for Amerx Health Care Corp. and is on their speaker bureau. The author has also disclosed that he has no financial relationship or vested interest with Amerx Health Care Corp. No funding was provided by the NIH, Wellcome Trust, HHMI, or others.

  4. Embodied Conceptual Combination

    PubMed Central

    Lynott, Dermot; Connell, Louise

    2010-01-01

    Conceptual combination research investigates the processes involved in creating new meaning from old referents. It is therefore essential that embodied theories of cognition are able to explain this constructive ability and predict the resultant behavior. However, by failing to take an embodied or grounded view of the conceptual system, existing theories of conceptual combination cannot account for the role of perceptual, motor, and affective information in conceptual combination. In the present paper, we propose the embodied conceptual combination (ECCo) model to address this oversight. In ECCo, conceptual combination is the result of the interaction of the linguistic and simulation systems, such that linguistic distributional information guides or facilitates the combination process, but the new concept is fundamentally a situated, simulated entity. So, for example, a cactus beetle is represented as a multimodal simulation that includes visual (e.g., the shiny appearance of a beetle) and haptic (e.g., the prickliness of the cactus) information, all situated in the broader location of a desert environment under a hot sun, and with (at least for some people) an element of creepy-crawly revulsion. The ECCo theory differentiates interpretations according to whether the constituent concepts are destructively, or non-destructively, combined in the situated simulation. We compare ECCo to other theories of conceptual combination, and discuss how it accounts for classic effects in the literature. PMID:21833267

  5. Embodied conceptual combination.

    PubMed

    Lynott, Dermot; Connell, Louise

    2010-01-01

    Conceptual combination research investigates the processes involved in creating new meaning from old referents. It is therefore essential that embodied theories of cognition are able to explain this constructive ability and predict the resultant behavior. However, by failing to take an embodied or grounded view of the conceptual system, existing theories of conceptual combination cannot account for the role of perceptual, motor, and affective information in conceptual combination. In the present paper, we propose the embodied conceptual combination (ECCo) model to address this oversight. In ECCo, conceptual combination is the result of the interaction of the linguistic and simulation systems, such that linguistic distributional information guides or facilitates the combination process, but the new concept is fundamentally a situated, simulated entity. So, for example, a cactus beetle is represented as a multimodal simulation that includes visual (e.g., the shiny appearance of a beetle) and haptic (e.g., the prickliness of the cactus) information, all situated in the broader location of a desert environment under a hot sun, and with (at least for some people) an element of creepy-crawly revulsion. The ECCo theory differentiates interpretations according to whether the constituent concepts are destructively, or non-destructively, combined in the situated simulation. We compare ECCo to other theories of conceptual combination, and discuss how it accounts for classic effects in the literature.

  6. Combining electronic structure and many-body theory with large databases: A method for predicting the nature of 4 f states in Ce compounds

    NASA Astrophysics Data System (ADS)

    Herper, H. C.; Ahmed, T.; Wills, J. M.; Di Marco, I.; Björkman, T.; Iuşan, D.; Balatsky, A. V.; Eriksson, O.

    2017-08-01

    Recent progress in materials informatics has opened up the possibility of a new approach to accessing properties of materials in which one assays the aggregate properties of a large set of materials within the same class in addition to a detailed investigation of each compound in that class. Here we present a large scale investigation of electronic properties and correlated magnetism in Ce-based compounds accompanied by a systematic study of the electronic structure and 4 f -hybridization function of a large body of Ce compounds. We systematically study the electronic structure and 4 f -hybridization function of a large body of Ce compounds with the goal of elucidating the nature of the 4 f states and their interrelation with the measured Kondo energy in these compounds. The hybridization function has been analyzed for more than 350 data sets (being part of the IMS database) of cubic Ce compounds using electronic structure theory that relies on a full-potential approach. We demonstrate that the strength of the hybridization function, evaluated in this way, allows us to draw precise conclusions about the degree of localization of the 4 f states in these compounds. The theoretical results are entirely consistent with all experimental information, relevant to the degree of 4 f localization for all investigated materials. Furthermore, a more detailed analysis of the electronic structure and the hybridization function allows us to make precise statements about Kondo correlations in these systems. The calculated hybridization functions, together with the corresponding density of states, reproduce the expected exponential behavior of the observed Kondo temperatures and prove a consistent trend in real materials. This trend allows us to predict which systems may be correctly identified as Kondo systems. A strong anticorrelation between the size of the hybridization function and the volume of the systems has been observed. The information entropy for this set of systems is

  7. Phosphate Ester Bond Hydrolysis Promoted by Lanthanide-Substituted Keggin-type Polyoxometalates Studied by a Combined Experimental and Density Functional Theory Approach.

    PubMed

    Luong, Thi Kim Nga; Mihaylov, Tzvetan T; Absillis, Gregory; Shestakova, Pavletta; Pierloot, Kristine; Parac-Vogt, Tatjana N

    2016-10-03

    Hydrolytic cleavage of 4-nitrophenyl phosphate (NPP), a commonly used DNA model substrate, was examined in the presence of series of lanthanide-substituted Keggin-type polyoxometalates (POMs) [Me2NH2]11[Ce(III)(PW11O39)2], [Me2NH2]10[Ce(IV)(PW11O39)2] (abbreviated as (Ce(IV)(PW11)2), and K4[EuPW11O39] by means of NMR and luminescence spectroscopies and density functional theory (DFT) calculations. Among the examined complexes, the Ce(IV)-substituted Keggin POM (Ce(IV)(PW11)2) showed the highest reactivity, and its aqueous speciation was fully determined under different conditions of pD, temperature, concentration, and ionic strength by means of (31)P and (31)P diffusion-ordered NMR spectroscopy. The cleavage of the phosphoester bond of NPP in the presence of (Ce(IV)(PW11)2) proceeded with an observed rate constant kobs = (5.31 ± 0.06) × 10(-6) s(-1) at pD 6.4 and 50 °C. The pD dependence of NPP hydrolysis exhibits a bell-shaped profile, with the fastest rate observed at pD 6.4. The formation constant (Kf = 127 M(-1)) and catalytic rate constant (kc = 19.41 × 10(-5) s(-1)) for the NPP-Ce(IV)-Keggin POM complex were calculated, and binding between Ce(IV)(PW11)2 and the phosphate group of NPP was also evidenced by the change of the chemical shift of the (31)P nucleus in NPP upon addition of the POM complex. DFT calculations revealed that binding of NPP to the parent catalyst Ce(IV)(PW11)2 is thermodynamically unlikely. On the contrary, formation of complexes with the monomeric 1:1 species, Ce(IV)PW11, is considered to be more favorable, and the most stable complex, [Ce(IV)PW11(H2O)2(NPP-κO)2](7-), was found to involve two NPP ligands coordinated to the Ce(IV)center of Ce(IV)PW11 in the monodentate fashion. The formation of such species is considered to be responsible for the hydrolytic activity of Ce(IV)(PW11)2 toward phosphomonoesters. On the basis of these findings a principle mechanism for the hydrolysis of NPP by the POM is proposed.

  8. Site selectivity in the protonation of a phosphinito bridged Pt(I)-Pt(I) complex: a combined NMR and density-functional theory mechanistic study.

    PubMed

    Latronico, Mario; Polini, Flavia; Gallo, Vito; Mastrorilli, Piero; Calmuschi-Cula, Beatrice; Englert, Ulli; Re, Nazzareno; Repo, Timo; Räisänen, Minna

    2008-11-03

    The protonation of the dinuclear phosphinito bridged complex [(PHCy2)Pt(mu-PCy2){kappa(2)P,O-mu-P(O)Cy2}Pt(PHCy2)] (Pt-Pt) (1) by Brønsted acids affords hydrido bridged Pt-Pt species the structure of which depends on the nature and on the amount of the acid used. The addition of 1 equiv of HX (X = Cl, Br, I) gives products of formal protonation of the Pt-Pt bond of formula syn-[(PHCy2)(X)Pt(mu-PCy2)(mu-H)Pt(PHCy2){kappaP-P(O)Cy2}] (Pt-Pt) (5, X = Cl; 6, X = Br; 8, X = I), containing a Pt-X bond and a dangling kappa P-P(O)Cy2 ligand. Uptake of a second equivalent of HX results in the protonation of the P(O)Cy2 ligand with formation of the complexes [(PHCy2)(X)Pt(mu-PCy2)(mu-H)Pt(PHCy2){kappaP-P(OH)Cy2}]X (Pt-Pt) (3, X = Cl; 4, X = Br; 9, X = I). Each step of protonation is reversible, thus reactions of 3, 4, with NaOH give, first, the corresponding neutral complexes 5, 6, and then the parent compound 1. While the complexes 3 and 4 are indefinitely stable, the iodine analogue 9 transforms into anti-[(PHCy2)(I)Pt(mu-PCy2)(mu-H)Pt(PHCy2)(I)] (Pt-Pt) (7) deriving from substitution of an iodo group for the P(OH)Cy2 ligand. Complexes 3 and 4 are isomorphous crystallizing in the triclinic space group P1 and show an intramolecular hydrogen bond and an interaction between the halide counteranion and the POH hydrogen. The occurrence of such an interaction also in solution was ascertained for 3 by (35)Cl NMR. Multinuclear NMR spectroscopy (including (31)P-(1)H HOESY) and density-functional theory calculations indicate that the mechanism of the reaction starts with a prior protonation of the oxygen with formation of an intermediate (12) endowed with a six membered Pt(1)-X...H-O-P-Pt(2) ring that evolves into thermodynamically stable products featuring the hydride ligand bridging the Pt atoms. Energy profiles calculated for the various steps of the reaction between 1 and HCl showed very low barriers for the proton transfer and the subsequent rearrangement to 12, while a barrier

  9. Two bonding configurations of acetylene on Si(001)-(2 x 1): a combined high-resolution electron energy loss spectroscopy and density functional theory study.

    PubMed

    Mineva, T; Nathaniel, R; Kostov, K L; Widdra, W

    2006-11-21

    Two coexisting adsorption states of molecularly adsorbed acetylene on the Si(001)-(2 x 1) surface have been identified by a combined study based on the high-resolution electron energy loss spectroscopy and density functional computations. Seven possible adsorbate-substrate structures are considered theoretically including their full vibrational analysis. Based on a significantly enhanced experimental resolution, the assignment of 15 C2H2- and C2D2-derived vibrational modes identifies a dominant di-sigma bonded molecule adsorbed on top of a single Si-Si dimer. Additionally there is clear evidence for a second minority species which is di-sigma bonded between two Si-Si dimers within the same dimer row (end-bridge geometry). The possible symmetries of the adsorbate complexes are discussed based on the specular and off-specular vibrational measurements. They suggest lower than ideal C(2v) and C(s) symmetries for on-top and end-bridge species, respectively. At low coverages the symmetry reductions might be lifted.

  10. Combined short and long-delay tandem shock waves to improve shock wave lithotripsy according to the Gilmore-Akulichev theory.

    PubMed

    de Icaza-Herrera, Miguel; Fernández, Francisco; Loske, Achim M

    2015-04-01

    Extracorporeal shock wave lithotripsy is a common non-invasive treatment for urinary stones whose fragmentation is achieved mainly by acoustic cavitation and mechanical stress. A few years ago, in vitro and in vivo experimentation demonstrated that such fragmentation can be improved, without increasing tissue damage, by sending a second shock wave hundreds of microseconds after the previous wave. Later, numerical simulations revealed that if the second pulse had a longer full width at half maximum than a standard shock wave, cavitation could be enhanced significantly. On the other side, a theoretical study showed that stress inside the stone can be increased if two lithotripter shock waves hit the stone with a delay of only 20 μs. We used the Gilmore-Akulichev formulation to show that, in principle, both effects can be combined, that is, stress and cavitation could be increased using a pressure pulse with long full width at half maximum, which reaches the stone within hundreds of microseconds after two 20 μs-delayed initial shock waves. Implementing the suggested pressure profile into clinical devices could be feasible, especially with piezoelectric shock wave sources. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Free-energy analysis of water affinity in polymer studied by atomistic molecular simulation combined with the theory of solutions in the energy representation

    NASA Astrophysics Data System (ADS)

    Kawakami, Tomonori; Shigemoto, Isamu; Matubayasi, Nobuyuki

    2012-12-01

    Affinity of small molecule to polymer is an essential property for designing polymer materials with tuned permeability. In the present work, we develop a computational approach to the free energy ΔG of binding a small solute molecule into polymer using the atomistic molecular dynamics (MD) simulation combined with the method of energy representation. The binding free energy ΔG is obtained by viewing a single polymer as a collection of fragments and employing an approximate functional constructed from distribution functions of the interaction energy between solute and the fragment obtained from MD simulation. The binding of water is then examined against 9 typical polymers. The relationship is addressed between the fragment size and the calculated ΔG, and a useful fragment size is identified to compromise the performance of the free-energy functional and the sampling efficiency. It is found with the appropriate fragment size that the ΔG convergence at a statistical error of ˜0.2 kcal/mol is reached at ˜4 ns of replica-exchange MD of the water-polymer system and that the mean absolute deviation of the computational ΔG from the experimental is 0.5 kcal/mol. The connection is further discussed between the polymer structure and the thermodynamic ΔG.

  12. An accurate density functional theory based estimation of pK(a) values of polar residues combined with experimental data: from amino acids to minimal proteins.

    PubMed

    Matsui, Toru; Baba, Takeshi; Kamiya, Katsumasa; Shigeta, Yasuteru

    2012-03-28

    We report a scheme for estimating the acid dissociation constant (pK(a)) based on quantum-chemical calculations combined with a polarizable continuum model, where a parameter is determined for small reference molecules. We calculated the pK(a) values of variously sized molecules ranging from an amino acid to a protein consisting of 300 atoms. This scheme enabled us to derive a semiquantitative pK(a) value of specific chemical groups and discuss the influence of the surroundings on the pK(a) values. As applications, we have derived the pK(a) value of the side chain of an amino acid and almost reproduced the experimental value. By using our computing schemes, we showed the influence of hydrogen bonds on the pK(a) values in the case of tripeptides, which decreases the pK(a) value by 3.0 units for serine in comparison with those of the corresponding monopeptides. Finally, with some assumptions, we derived the pK(a) values of tyrosines and serines in chignolin and a tryptophan cage. We obtained quite different pK(a) values of adjacent serines in the tryptophan cage; the pK(a) value of the OH group of Ser13 exposed to bulk water is 14.69, whereas that of Ser14 not exposed to bulk water is 20.80 because of the internal hydrogen bonds.

  13. Investigating Sodium Storage Mechanisms in Tin Anodes: A Combined Pair Distribution Function Analysis, Density Functional Theory, and Solid-State NMR Approach

    DOE PAGES

    Stratford, Joshua M.; Mayo, Martin; Allan, Phoebe K.; ...

    2017-05-04

    Here, the alloying mechanism of high-capacity tin anodes for sodium-ion batteries is investigated using a combined theoretical and experimental approach. Ab initio random structure searching (AIRSS) and high-throughput screening using a species-swap method provide insights into a range of possible sodium–tin structures. These structures are linked to experiments using both average and local structure probes in the form of operando pair distribution function analysis, X-ray diffraction, and 23Na solid-state nuclear magnetic resonance (ssNMR), along with ex situ 119Sn ssNMR. Through this approach, we propose structures for the previously unidentified crystalline and amorphous intermediates. The first electrochemical process of sodium insertionmore » into tin results in the conversion of crystalline tin into a layered structure consisting of mixed Na/Sn occupancy sites intercalated between planar hexagonal layers of Sn atoms (approximate stoichiometry NaSn3). Following this, NaSn2, which is predicted to be thermodynamically stable by AIRSS, forms; this contains hexagonal layers closely related to NaSn3, but has no tin atoms between the layers. NaSn2 is broken down into an amorphous phase of approximate composition Na1.2Sn. Reverse Monte Carlo refinements of an ab initio molecular dynamics model of this phase show that the predominant tin connectivity is chains. Further reaction with sodium results in the formation of structures containing Sn–Sn dumbbells, which interconvert through a solid-solution mechanism. These structures are based upon Na5–xSn2, with increasing occupancy of one of its sodium sites commensurate with the amount of sodium added. ssNMR results indicate that the final product, Na15Sn4, can store additional sodium atoms as an off-stoichiometry compound (Na15+xSn4) in a manner similar to Li15Si4.« less

  14. Reactivity of Dimeric Tetrazirconium(IV) Wells-Dawson Polyoxometalate toward Dipeptide Hydrolysis Studied by a Combined Experimental and Density Functional Theory Approach.

    PubMed

    Ly, Hong Giang T; Mihaylov, Tzvetan; Absillis, Gregory; Pierloot, Kristine; Parac-Vogt, Tatjana N

    2015-12-07

    Detailed kinetic studies on the hydrolysis of glycylglycine (Gly-Gly) in the presence of the dimeric tetrazirconium(IV)-substituted Wells-Dawson-type polyoxometalate Na14[Zr4(P2W16O59)2(μ3-O)2(OH)2(H2O)4] · 57H2O (1) were performed by a combination of (1)H, (13)C, and (31)P NMR spectroscopies. The catalyst was shown to be stable under a broad range of reaction conditions. The effect of pD on the hydrolysis of Gly-Gly showed a bell-shaped profile with the fastest hydrolysis observed at pD 7.4. The observed rate constant for the hydrolysis of Gly-Gly at pD 7.4 and 60 °C was 4.67 × 10(-7) s(-1), representing a significant acceleration as compared to the uncatalyzed reaction. (13)C NMR data were indicative for coordination of Gly-Gly to 1 via its amide oxygen and amine nitrogen atoms, resulting in a hydrolytically active complex. Importantly, the effective hydrolysis of a series of Gly-X dipeptides with different X side chain amino acids in the presence of 1 was achieved, and the observed rate constant was shown to be dependent on the volume, chemical nature, and charge of the X amino acid side chain. To give a mechanistic explanation of the observed catalytic hydrolysis of Gly-Gly, a detailed quantum-chemical study was performed. The theoretical results confirmed the nature of the experimentally suggested binding mode in the hydrolytically active complex formed between Gly-Gly and 1. To elucidate the role of 1 in the hydrolytic process, both the uncatalyzed and the polyoxometalate-catalyzed reactions were examined. In the rate-determining step of the uncatalyzed Gly-Gly hydrolysis, a carboxylic oxygen atom abstracts a proton from a solvent water molecule and the nascent OH nucleophile attacks the peptide carbon atom. Analogous general-base activity of the free carboxylic group was found to take place also in the case of polyoxometalate-catalyzed hydrolysis as the main catalytic effect originates from the -C═O···Zr(IV) binding.

  15. Rate theories for biologists

    PubMed Central

    Zhou, Huan-Xiang

    2012-01-01

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

  16. Rate theories for biologists.

    PubMed

    Zhou, Huan-Xiang

    2010-05-01

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

  17. String Theory and Gauge Theories

    SciTech Connect

    Maldacena, Juan

    2009-02-20

    We will see how gauge theories, in the limit that the number of colors is large, give string theories. We will discuss some examples of particular gauge theories where the corresponding string theory is known precisely, starting with the case of the maximally supersymmetric theory in four dimensions which corresponds to ten dimensional string theory. We will discuss recent developments in this area.

  18. Geographical Theories.

    ERIC Educational Resources Information Center

    Golledge, Reginald G.

    1996-01-01

    Discusses the origin of theories in geography and particularly the development of location theories. Considers the influence of economic theory on agricultural land use, industrial location, and geographic location theories. Explores a set of interrelated activities that show how the marketing process illustrates process theory. (MJP)

  19. Educational Theory

    ERIC Educational Resources Information Center

    Schubert, Leo

    1973-01-01

    Briefly describes two antagonistic learning theories: the Association Theory proposed by Skinner and the Field or Cognitive Theory supported by Piaget. Suggests the need for consistency in theoretical approach in the teaching of science at the college level. (JR)

  20. Differentiated Success: Combining Theories to Explain Learning

    ERIC Educational Resources Information Center

    Jorgensen, Robyn; Larkin, Kevin

    2015-01-01

    This paper explores the value of different paradigms to explain dispositions towards mathematics among primary school students from different social backgrounds. As part of a larger project designed to elicit students' thinking and attitudes towards mathematics, we seek to develop an explanatory model for the socially-differentiated outcomes in…

  1. Computation of the free energy due to electron density fluctuation of a solute in solution: A QM/MM method with perturbation approach combined with a theory of solutions

    SciTech Connect

    Suzuoka, Daiki; Takahashi, Hideaki Morita, Akihiro

    2014-04-07

    We developed a perturbation approach to compute solvation free energy Δμ within the framework of QM (quantum mechanical)/MM (molecular mechanical) method combined with a theory of energy representation (QM/MM-ER). The energy shift η of the whole system due to the electronic polarization of the solute is evaluated using the second-order perturbation theory (PT2), where the electric field formed by surrounding solvent molecules is treated as the perturbation to the electronic Hamiltonian of the isolated solute. The point of our approach is that the energy shift η, thus obtained, is to be adopted for a novel energy coordinate of the distribution functions which serve as fundamental variables in the free energy functional developed in our previous work. The most time-consuming part in the QM/MM-ER simulation can be, thus, avoided without serious loss of accuracy. For our benchmark set of molecules, it is demonstrated that the PT2 approach coupled with QM/MM-ER gives hydration free energies in excellent agreements with those given by the conventional method utilizing the Kohn-Sham SCF procedure except for a few molecules in the benchmark set. A variant of the approach is also proposed to deal with such difficulties associated with the problematic systems. The present approach is also advantageous to parallel implementations. We examined the parallel efficiency of our PT2 code on multi-core processors and found that the speedup increases almost linearly with respect to the number of cores. Thus, it was demonstrated that QM/MM-ER coupled with PT2 deserves practical applications to systems of interest.

  2. Novel quantum mechanical/molecular mechanical method combined with the theory of energy representation: Free energy calculation for the Beckmann rearrangement promoted by proton transfers in the supercritical water

    NASA Astrophysics Data System (ADS)

    Takahashi, Hideaki; Tanabe, Kohsuke; Aketa, Masataka; Kishi, Ryohei; Furukawa, Shin-ichi; Nakano, Masayoshi

    2007-02-01

    The Beckmann rearrangement of acetone oxime promoted by proton transfers in the supercritical water has been investigated by means of the hybrid quantum mechanical/molecular mechanical approach combined with the theory of energy representation (QM/MM-ER) recently developed. The transition state (TS) structures have been explored by ab initio calculations for the reaction of hydrated acetone oxime on the assumption that the reaction is catalyzed by proton transfers along the hydrogen bonds connecting the solute and the solvent water molecules. Up to two water molecules have been considered as reactants that take part in the proton transfers. As a result of the density functional theory calculations with B3LYP functional and aug-cc-pVDZ basis set, it has been found that participation of two water molecules in the reaction reduces the activation free energy by -12.3kcal/mol. Furthermore, the QM/MM-ER simulations have revealed that the TS is more stabilized than the reactant state in the supercritical water by 2.7kcal/mol when two water molecules are involved in the reaction. Solvation free energies of the reactant and the TS have been decomposed into terms due to the electronic polarization of the solute, electron density fluctuation, and others to elucidate the origin of the stabilization of the TS as compared with the reactant. It has been revealed that the promotion of the chemical reaction due to the hydration mainly originates from the interaction between the nonpolarized solute and the solvent water molecules at the supercritical state.

  3. Potassium-induced effect on structure and chemical activity of CuxO/Cu(111) (x≤2) surface: A combined scanning tunneling microscopy and density functional theory study

    SciTech Connect

    Liu, Ping; An, Wei; Stacchiola, Dario; Xu, Fang

    2015-10-16

    Potassium (K) plays an essential role in promoting catalytic reaction in many established industrial catalytic processes. Here, we report a combined study using scanning tunneling microscopy (STM) and density functional theory (DFT) in understanding the effect of depositing K on the atomic and electronic structures as well as chemical activities of CuxO/Cu(111) (x≤2). The DFT calculations observe a pseudomorphic growth of K on CuxO/Cu(111) up to 0.19 monolayer (ML) of coverage, where K binds the surface via strong ionic interaction with chemisorbed oxygen and the relatively weak electrostatic interactions with copper ions, lower and upper oxygen on the CuxO rings. The simulated STM pattern based on the DFT results agrees well with the experimental observations. The deposited K displays great impact on the surface electronic structure of CuxO/Cu(111), which induces significant reduction in work function and leads to a strong electron polarization on the surface. The promotion of K on the surface binding properties is selective. It varies depending on the nature of adsorbates. According to our results, K has little effect on surface acidity, while it enhances the surface basicity significantly. As a consequence, the presence of K does not help for CO adsorption on CuxO/Cu(111), but being able to accelerate the activation of CO2. Thus, such promotion strongly depends on the combinations from both geometric and electronic effects. Our results highlight the origin of promoting effect of alkalis in the design of catalysts for the complex reactions.

  4. Investigation of the Fe{sup 3+} centers in perovskite KMgF{sub 3} through a combination of ab initio (density functional theory) and semi-empirical (superposition model) calculations

    SciTech Connect

    Emül, Y.; Erbahar, D.; Açıkgöz, M.

    2015-08-14

    Analyses of the local crystal and electronic structure in the vicinity of Fe{sup 3+} centers in perovskite KMgF{sub 3} crystal have been carried out in a comprehensive manner. A combination of density functional theory (DFT) and a semi-empirical superposition model (SPM) is used for a complete analysis of all Fe{sup 3+} centers in this study for the first time. Some quantitative information has been derived from the DFT calculations on both the electronic structure and the local geometry around Fe{sup 3+} centers. All of the trigonal (K-vacancy case, K-Li substitution case, and normal trigonal Fe{sup 3+} center case), FeF{sub 5}O cluster, and tetragonal (Mg-vacancy and Mg-Li substitution cases) centers have been taken into account based on the previously suggested experimental and theoretical inferences. The collaboration between the experimental data and the results of both DFT and SPM calculations provides us to understand most probable structural model for Fe{sup 3+} centers in KMgF{sub 3}.

  5. 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.

  6. A randomized controlled trial of a brief online intervention to reduce alcohol consumption in new university students: Combining self-affirmation, theory of planned behaviour messages, and implementation intentions.

    PubMed

    Norman, Paul; Cameron, David; Epton, Tracy; Webb, Thomas L; Harris, Peter R; Millings, Abigail; Sheeran, Paschal

    2017-09-20

    Excessive alcohol consumption increases when students enter university. This study tests whether combining (1) messages that target key beliefs from the theory of planned behaviour (TPB) that underlie binge drinking, (2) a self-affirmation manipulation to reduce defensive processing, and (3) implementation intentions (if-then plans to avoid binge drinking) reduces alcohol consumption in the first 6 months at university. A 2 (self-affirmation) × 2 (TPB messages) × 2 (implementation intention) between-participants randomized controlled trial with 6-month follow-up. Before starting university, students (N = 2,951) completed measures of alcohol consumption and were randomly assigned to condition in a full-factorial design. TPB cognitions about binge drinking were assessed immediately post-intervention (n = 2,682). Alcohol consumption was assessed after 1 week (n = 1,885), 1 month (n = 1,389), and 6 months (n = 892) at university. TPB cognitions were assessed again at 1 and 6 months. Participants who received the TPB messages had significantly less favourable cognitions about binge drinking (except perceived control), consumed fewer units of alcohol, engaged in binge drinking less frequently, and had less harmful patterns of alcohol consumption during their first 6 months at university. The other main effects were non-significant. The findings support the use of TPB-based interventions to reduce students' alcohol consumption, but question the use of self-affirmation and implementation intentions before starting university when the messages may not represent a threat to self-identity and when students may have limited knowledge and experience of the pressures to drink alcohol at university. Statement of contribution What is already known on this subject? Alcohol consumption increases when young people enter university. Significant life transitions represent potential teachable moments to change behaviour. Interventions with a strong theoretical

  7. String Theory: Big Problem for Small Size

    ERIC Educational Resources Information Center

    Sahoo, S.

    2009-01-01

    String theory is the most promising candidate theory for a unified description of all the fundamental forces that exist in nature. It provides a mathematical framework that combines quantum theory with Einstein's general theory of relativity. The typical size of a string is of the order of 10[superscript -33] cm, called the Planck length. But due…

  8. String Theory: Big Problem for Small Size

    ERIC Educational Resources Information Center

    Sahoo, S.

    2009-01-01

    String theory is the most promising candidate theory for a unified description of all the fundamental forces that exist in nature. It provides a mathematical framework that combines quantum theory with Einstein's general theory of relativity. The typical size of a string is of the order of 10[superscript -33] cm, called the Planck length. But due…

  9. Co-Determination of Crystal Structures at High Pressure: Combined Application of Theory and Experiment to the AuGa2 Intermetallic analog to High-Pressure SiO2

    NASA Astrophysics Data System (ADS)

    Godwal, B. K.; Stackhouse, S.; Yan, J.; Speziale, S.; Militzer, B.; Jeanloz, R.

    2012-12-01

    The intermetallic compounds AuX2 (X = In, Ga, Al) crystallize in the calcium fluorite (CaF2) structure, making them analogs for SiO2 at TPa pressures. A combination of high-pressure x-ray diffraction experiments and first-principles calculations reveals the sequence of crystal-structural phase transitions in AuGa2 from cubic (Fm3m) to orthorhombic (Pnma) at 10 (± 4) GPa, and then to monoclinic (P21/n) at 33 (± 6) GPa. The post-cotunnite (P1121/a) phase identified as the final step in the phase-transition sequence for other AX2 compounds is found to be unstable. As the structural sequence followed by AuGa2 is similar to that observed in ACl2 (A = Pb, Sn) compounds it implies that AX2 compounds iso-structural to PbCl2 will acquire the monoclinic (P21/n) structure at extreme pressures. Neither theory nor experiment would have been adequate, on their own, in documenting this sequence of phases, but together they confirm a sequence differing from the Fm3m → Pnma → P63/mmc transitions predicted for CaF2, and observed for the intermetallic analog compounds AuIn2 and AuAl2 under pressure. Experimental [and theoretical] values of zero-pressure volume and bulk modulus are 224.5 (± 0.2) [219.5] Å3 and 81 (± 5) [95] GPa; 204.0 (± 1) [204.8] Å3 and 112 (± 12) [96] GPa; and 192 (± 4) [201.1] Å3 and 157 (± 5) [99] GPa for the cubic, orthorhombic and monoclinic phases, respectively.

  10. C-C bond unsaturation degree in monosubstituted ferrocenes for molecular electronics investigated by a combined near-edge x-ray absorption fine structure, x-ray photoemission spectroscopy, and density functional theory approach

    SciTech Connect

    Boccia, A.; Lanzilotto, V.; Marrani, A. G.; Zanoni, R.; Stranges, S.; Alagia, M.; Fronzoni, G.; Decleva, P.

    2012-04-07

    We present the results of an experimental and theoretical investigation of monosubstituted ethyl-, vinyl-, and ethynyl-ferrocene (EtFC, VFC, and EFC) free molecules, obtained by means of synchrotron-radiation based C 1s photoabsorption (NEXAFS) and photoemission (C 1s XPS) spectroscopies, and density functional theory (DFT) calculations. Such a combined study is aimed at elucidating the role played by the C-C bond unsaturation degree of the substituent on the electronic structure of the ferrocene derivatives. Such substituents are required for molecular chemical anchoring onto relevant surfaces when ferrocenes are used for molecular electronics hybrid devices. The high resolution C 1s NEXAFS spectra exhibit distinctive features that depend on the degree of unsaturation of the hydrocarbon substituent. The theoretical approach to consider the NEXAFS spectrum made of three parts allowed to disentangle the specific contribution of the substituent group to the experimental spectrum as a function of its unsaturation degree. C 1s IEs were derived from the experimental data analysis based on the DFT calculated IE values for the different carbon atoms of the substituent and cyclopentadienyl (Cp) rings. Distinctive trends of chemical shifts were observed for the substituent carbon atoms and the substituted atom of the Cp ring along the series of ferrocenes. The calculated IE pattern was rationalized in terms of initial and final state effects influencing the IE value, with special regard to the different mechanism of electron conjugation between the Cp ring and the substituent, namely the {sigma}/{pi} hyperconjugation in EtFC and the {pi}-conjugation in VFC and EFC.

  11. Combining theory with experiment: Assessment of the thermochemistry of SF{sub n}, SF{sub n}{sup +}, and SF{sub n}{sup -}, n=1-6

    SciTech Connect

    Cheung, Y.S.; Chen, Y.J.; Ng, C.Y. |; Chiu, S.W.; Li, W.K.

    1995-09-27

    The comparison of the experimental thermochemical data and G2 or [G2(MP2)] predictions for SF{sub n}, SF{sub n}{sup +}, and SF{sub n} {sup -} (n = 1-6) allows us to recommend a self-consistent set of experimental {Delta}{sub f}H{degree}{sub 0}, IE, EA, D{degree}{sub 0} values for these systems. This work shows that for reliable determinations of the thermochemical data for a complex system such as SF{sub n}, SF{sub n} {sup +}, and SF{sub n}{sup -} (n = 1-6), it is necessary to combine experimental measurements made using different techniques and theoretical predictions calculated using a sufficiently accurate theoretical procedure. The comparison of experimental and theoretical results in this study further confirms that G2 and G2(MP2) procedures are reliable theoretical methods for providing energetic predictions accurate to 4-5 kcal/mol for complex sulfur-containing molecular species. The theoretical equilibrium structures obtained for SF{sub n}, SF{sub n}{sup +}, and SF{sub n}{sup -} (n = 1-6) have been rationalized using the VSEPR theory. Furthermore, we have provided an explanation to account for the observed alternating patterns in IE, EA, and D{degree}{sub 0} values for SF{sub n}, SF{sub n}{sup +}, and SF{sub n}{sup -} (n = 1-6). Alternating patterns in IE, EA, and D{degree}{sub 0} values are expected for other similar hypervalent species. 60 refs., 2 figs., 4 tabs.

  12. Lewis Acid and Substituent Effects on the Molecular Mechanism for the Nazarov Reaction of Penta-1,4-dien-3-one and Derivatives. A Topological Analysis Based on the Combined Use of Electron Localization Function and Catastrophe Theory.

    PubMed

    Polo, Victor; Andrés, Juan

    2007-05-01

    The joint use of the topological analysis provided by the electron localization function (ELF) and catastrophe theory (CT), at the B3LYP/6-31G(d) calculation level, allows us to examine the Lewis acid (protonation H(+) and presence of BH3) and the role of an electron donor substituent (-OCH3) at α and β positions along the course of the molecular mechanism for the Nazarov rearrangement of penta-1,4-dien-3-one and eight derivatives. The progress of the reaction is monitored by the changes of the ELF structural stability domains (SSDs), each change being controlled by a turning point derived from CT. These SSDs and the corresponding turning points are associated with a sequence of elementary chemical steps. Along the cyclization path of penta-1,4-diene-3-one, four SSDs as well as three turning points (cusp1-fold1-cusp2) have been characterized. The first and second SSDs correspond to a polarization of the C-O bond and electronic redistribution among the C-C bonds, respectively, and they can be associated with the formation of an oxyallyl structure. The third and fourth SSDs can be assigned to the ring closure process. Protonation of the oxygen atom shifts the reactive directly into the second SSD, greatly reducing the activation and reaction energies. The electronic effects due to Lewis acids and electron donor substituents have been rationalized in terms of calculations of mesomeric structures from ELF basin populations. The combination of Lewis acids together with α and β -OCH3 substitutions renders a cooperative and competitive effect on activation and reaction free energies, respectively.

  13. C-C bond unsaturation degree in monosubstituted ferrocenes for molecular electronics investigated by a combined near-edge x-ray absorption fine structure, x-ray photoemission spectroscopy, and density functional theory approach

    NASA Astrophysics Data System (ADS)

    Boccia, A.; Lanzilotto, V.; Marrani, A. G.; Stranges, S.; Zanoni, R.; Alagia, M.; Fronzoni, G.; Decleva, P.

    2012-04-01

    We present the results of an experimental and theoretical investigation of monosubstituted ethyl-, vinyl-, and ethynyl-ferrocene (EtFC, VFC, and EFC) free molecules, obtained by means of synchrotron-radiation based C 1s photoabsorption (NEXAFS) and photoemission (C 1s XPS) spectroscopies, and density functional theory (DFT) calculations. Such a combined study is aimed at elucidating the role played by the C-C bond unsaturation degree of the substituent on the electronic structure of the ferrocene derivatives. Such substituents are required for molecular chemical anchoring onto relevant surfaces when ferrocenes are used for molecular electronics hybrid devices. The high resolution C 1s NEXAFS spectra exhibit distinctive features that depend on the degree of unsaturation of the hydrocarbon substituent. The theoretical approach to consider the NEXAFS spectrum made of three parts allowed to disentangle the specific contribution of the substituent group to the experimental spectrum as a function of its unsaturation degree. C 1s IEs were derived from the experimental data analysis based on the DFT calculated IE values for the different carbon atoms of the substituent and cyclopentadienyl (Cp) rings. Distinctive trends of chemical shifts were observed for the substituent carbon atoms and the substituted atom of the Cp ring along the series of ferrocenes. The calculated IE pattern was rationalized in terms of initial and final state effects influencing the IE value, with special regard to the different mechanism of electron conjugation between the Cp ring and the substituent, namely the σ/π hyperconjugation in EtFC and the π-conjugation in VFC and EFC.

  14. Packaging Theory.

    ERIC Educational Resources Information Center

    Williams, Jeffrey

    1994-01-01

    Considers the recent flood of anthologies of literary criticism and theory as exemplifications of the confluence of pedagogical concerns, economics of publishing, and other historical factors. Looks specifically at how these anthologies present theory. Cites problems with their formatting theory and proposes alternative ways of organizing theory…

  15. Grounded theory.

    PubMed

    Harris, Tina

    2015-04-29

    Grounded theory is a popular research approach in health care and the social sciences. This article provides a description of grounded theory methodology and its key components, using examples from published studies to demonstrate practical application. It aims to demystify grounded theory for novice nurse researchers, by explaining what it is, when to use it, why they would want to use it and how to use it. It should enable nurse researchers to decide if grounded theory is an appropriate approach for their research, and to determine the quality of any grounded theory research they read.

  16. Probing the Li Insertion Mechanism of ZnFe2O4 in Li-Ion Batteries: A Combined X-Ray Diffraction, Extended X-Ray Absorption Fine Structure, and Density Functional Theory Study [Probing the Li insertion mechanism of ZnFe2O4 in Li ion batteries: A combined XRD, EXAFS, and DFT study

    DOE PAGES

    Zhang, Yiman; Pelliccione, Christopher J.; Brady, Alexander B.; ...

    2017-04-24

    Here, we report an extensive study on fundamental properties that determine the functional electrochemistry of ZnFe2O4 spinel (theoretical capacity of 1000 mAh/g). For the first time, the reduction mechanism is followed through a combination of in situ X-ray diffraction data, synchrotron based powder diffraction, and ex-situ extended X-ray absorption fine structure allowing complete visualization of reduction products irrespective of their crystallinity. The first 0.5 electron equivalents (ee) do not significantly change the starting crystal structure. Subsequent lithiation results in migration of Zn2+ ions from 8a tetrahedral sites into vacant 16c sites. Density functional theory shows that Li+ ions insert intomore » 16c site initially and then 8a site with further lithiation. Fe metal is formed over the next eight ee of reduction with no evidence of concurrent Zn2+ reduction to Zn metal. Despite the expected formation of LiZn alloy from the electron count, we find no evidence for this phase under the tested conditions. Additionally, upon oxidation to 3 V, we observe an FeO phase with no evidence of Fe2O3. Electrochemistry data show higher electron equivalent transfer than can be accounted for solely based on ZnFe2O4 reduction indicating excess capacity ascribed to carbon reduction or surface electrolyte interphase formation.« less

  17. Probability Theory

    NASA Astrophysics Data System (ADS)

    Jaynes, E. T.; Bretthorst, G. Larry

    2003-04-01

    Foreword; Preface; Part I. Principles and Elementary Applications: 1. Plausible reasoning; 2. The quantitative rules; 3. Elementary sampling theory; 4. Elementary hypothesis testing; 5. Queer uses for probability theory; 6. Elementary parameter estimation; 7. The central, Gaussian or normal distribution; 8. Sufficiency, ancillarity, and all that; 9. Repetitive experiments, probability and frequency; 10. Physics of 'random experiments'; Part II. Advanced Applications: 11. Discrete prior probabilities, the entropy principle; 12. Ignorance priors and transformation groups; 13. Decision theory: historical background; 14. Simple applications of decision theory; 15. Paradoxes of probability theory; 16. Orthodox methods: historical background; 17. Principles and pathology of orthodox statistics; 18. The Ap distribution and rule of succession; 19. Physical measurements; 20. Model comparison; 21. Outliers and robustness; 22. Introduction to communication theory; References; Appendix A. Other approaches to probability theory; Appendix B. Mathematical formalities and style; Appendix C. Convolutions and cumulants.

  18. Information Design Theories

    ERIC Educational Resources Information Center

    Pettersson, Rune

    2014-01-01

    Information design has practical and theoretical components. As an academic discipline we may view information design as a combined discipline, a practical theory, or as a theoretical practice. So far information design has incorporated facts, influences, methods, practices, principles, processes, strategies, and tools from a large number of…

  19. [United theory of aging].

    PubMed

    Trubitsyn, A G

    2012-01-01

    In attempts to develop a means of life prolongation the humankind has created more than three hundred theories of the aging; each of them offers the original cause of aging. However, none of them has given practical result by now. The majority of the theories have now only historical interest. There are several different theories that are mainly under consideration currently. They are based on reliable, proven evidence: the free radical theory, the protein error theory, the replicative senescence theory, the theory of reparation weakening, the immunological theory, several versions of neuroendocrinal theories, and programmed aging theory. The theory presented here is based on conception that the life as the phenomenon represents many of the interconnected physical and chemical processes propelled by energy of the mitochondrial bioenergetical machine. Gradual degradation of all vital processes is caused by the programmed decrease in level of bioenergetics. This theory unites all existing theories of aging constructed on authentic facts: it is shown, that such fundamental phenomena accompanying aging process as the increase in level of reactive oxygen species (ROS), the decrease in the general level of protein synthesis, the limitation of cellular dividing (Haiflick limit), decrease in efficiency of reparation mechanisms are caused by bioenergetics attenuation. Each of these phenomena in turn generates a number of harmful secondary processes. Any of the theories bases on one of these destructive phenomena or their combination. Hence, each of them describes one of sides of process of the aging initially caused by programmed decrease of level of bioenergetics. This united theory gives the chance to understand the nature of aging clock and explains a phenomenon of increase in longevity at the condition of food restriction. Failures of attempts to develop means from aging are explained by that the manipulations with the separate secondary phenomena of attenuation of

  20. High-resolution 3D structural and optical analyses of hybrid or composite materials by means of scanning probe microscopy combined with the ultramicrotome technique: an example of application to engineering of liquid crystals doped with fluorescent quantum dots

    NASA Astrophysics Data System (ADS)

    Mochalov, Konstantin E.; Efimov, Anton E.; Bobrovsky, Alexey Yu.; Agapov, Igor I.; Chistyakov, Anton A.; Oleinikov, Vladimir A.; Nabiev, Igor

    2013-05-01

    Combination of nanometer-scale 3D structural analysis with optical characterization of the same material is a challenging task. Its results may be important for nanophotonics, materials science, and quality control. We have developed a new technique for complementary high-resolution structural and optical characterization followed by optical spectroscopic and microscopic measurements accompanied by reconstruction of the 3D structure in the same area of the sample. The 3D structure is reconstructed by combination of ultramicrotomic and SPM techniques allowing the study of the 3D distribution of implanted nanoparticles and their effect on the matrix structure. The combination of scanning probe nanotomography (SPN) and optical microspectroscopy makes it possible to direct estimate how the 3D structural characteristics of materials affect their macroscopic optical properties. The technique developed has been applied to the engineering of materials made from cholesteric liquid crystals and fluorescent quantum dots (QDs). These materials permit photochemical patterning and image recording through the changes in the dissymmetry factor of circular polarization of QD emission. The differences in the polarisation images and morphological characteristics of the liquid crystal matrix have proved to be correlated with the arrangement of the areas of homogeneous distribution and nonhomogeneous clustering of QDs. The reconstruction of the 3D structure of the liquid crystal matrix in the areas of homogeneous QD distribution has shown that QDs embedded into cholesteric liquid crystal matrices do not perturb their periodic planar texture. The combined optical/SPM/ultramicrotome technique will be indispensable for evaluating the effects of inorganic nanoparticles on the organisation of organic and liquid crystal matrices, biomedical materials, cells, and tissues.

  1. Power combiner

    DOEpatents

    Arnold, Mobius; Ives, Robert Lawrence

    2006-09-05

    A power combiner for the combining of symmetric and asymmetric traveling wave energy comprises a feed waveguide having an input port and a launching port, a reflector for reflecting launched wave energy, and a final waveguide for the collection and transport of launched wave energy. The power combiner has a launching port for symmetrical waves which comprises a cylindrical section coaxial to the feed waveguide, and a launching port for asymmetric waves which comprises a sawtooth rotated about a central axis.

  2. Elucidating Potential Energy Surfaces for Singlet O2 Reactions with Protonated, Deprotonated, and Di-Deprotonated Cystine Using a Combination of Approximately Spin-Projected Density Functional Theory and Guided-Ion-Beam Mass Spectrometry.

    PubMed

    Lu, Wenchao; Tsai, I-Hsien Midas; Sun, Yan; Zhou, Wenjing; Liu, Jianbo

    2017-08-24

    The reactivity of cystine toward electronically excited singlet O2 (a(1)Δg) has been long debated, despite the fact that most organic disulfides are susceptible to oxidation by singlet O2. We report a combined experimental and computational study on reactions of singlet O2 with gas-phase cystine at different ionization and hydration states, aimed to determine reaction outcomes, mechanisms, and potential energy surfaces (PESs). Ion-molecule collisions of protonated and di-deprotonated cystine ions with singlet O2, in both the absence and the presence of a water ligand, were measured over a center-of-mass collision energy (Ecol) range from 0.1 to 1.0 eV, using a guided-ion-beam scattering tandem mass spectrometer. No oxidation was observed for these reactant ions except collision-induced dissociation at high energies. Guided by density functional theory (DFT)-calculated PESs, reaction coordinates were established to unravel the origin of the nonreactivity of cystine ions toward singlet O2. To account for mixed open- and closed-shell characters, singlet O2 and critical structures along reaction coordinates were evaluated using broken-symmetry, open-shell DFT with spin contamination errors removed by an approximate spin-projection method. It was found that collision of protonated cystine with singlet O2 follows a repulsive potential surface and possesses no chemically significant interaction and that collision-induced dissociation of protonated cystine is dominated by loss of water and CO. Collision of di-deprotonated cystine with singlet O2, on the other hand, forms a short-lived electrostatically bonded precursor complex at low Ecol. The latter may evolve to a covalently bonded persulfoxide, but the conversion is blocked by an activation barrier lying 0.39 eV above reactants. At high Ecol, C-S bond cleavage dominates the collision-induced dissociation of di-deprotonated cystine, leading to charge-separated fragmentation. Cross section for the ensuing fragment ion H2

  3. Near-infrared-emitting phthalocyanines. A combined experimental and density functional theory study of the structural, optical, and photophysical properties of Pd(II) and Pt(II) α-butoxyphthalocyanines.

    PubMed

    Soldatova, Alexandra V; Kim, Junhwan; Rizzoli, Corrado; Kenney, Malcolm E; Rodgers, Michael A J; Rosa, Angela; Ricciardi, Giampaolo

    2011-02-07

    The structural, optical, and photophysical properties of 1,4,8,11,15,18,22,25-octabutoxyphthalocyaninato-palladium(II), PdPc(OBu)(8), and the newly synthesized platinum analogue PtPc(OBu)(8) are investigated combining X-ray crystallography, static and transient absorption spectroscopy, and relativistic zeroth-order regular approximation (ZORA) Density Functional Theory (DFT)/Time Dependent DFT (TDDFT) calculations where spin-orbit coupling (SOC) effects are explicitly considered. The results are compared to those previously reported for NiPc(OBu)(8) (J. Phys. Chem. A 2005, 109, 2078) in an effort to highlight the effect of the central metal on the structural and photophysical properties of the group 10 transition metal octabutoxyphthalocyanines. Different from the nickel analogue, PdPc(OBu)(8) and PtPc(OBu)(8) show a modest and irregular saddling distortion of the macrocycle, but share with the first member of the group similar UV-vis spectra, with the deep red and intense Q-band absorption experiencing a blue shift down the group, as observed in virtually all tetrapyrrolic complexes of this triad. The blue shift of the Q-band along the MPc(OBu)(8) (M = Ni, Pd, Pt) series is interpreted on the basis of the metal-induced electronic structure changes. Besides the intense deep red absorption, the title complexes exhibit a distinct near-infrared (NIR) absorption due to a transition to the double-group 1E (π,π*) state, which is dominated by the lowest single-group (3)E (π,π*) state. Unlike NiPc(OBu)(8), which is nonluminescent, PdPc(OBu)(8) and PtPc(OBu)(8) show both deep red fluorescence emission and NIR phosphorescence emission. Transient absorption experiments and relativistic spin-orbit TDDFT calculations consistently indicate that fluorescence and phosphorescence emissions occur from the S(1)(π,π*) and T(1)(π,π*) states, respectively, the latter being directly populated from the former, and the triplet state decays directly to the S(0) surface (the triplet

  4. Confabulation Theory

    NASA Astrophysics Data System (ADS)

    Solari, Soren; Smith, Andrew; Minnett, Rupert; Hecht-Nielsen, Robert

    2008-06-01

    Confabulation Theory [Hecht-Nielsen R. Confabulation theory. Springer-Verlag; 2007] is the first comprehensive theory of human and animal cognition. Here, we briefly describe Confabulation Theory and discuss experimental results that suggest the theory is correct. Simply put, Confabulation Theory proposes that thinking is like moving. In humans, the theory postulates that there are roughly 4000 thalamocortical modules, the “muscles of thought”. Each module performs an internal competition ( confabulation) between its symbols, influenced by inputs delivered via learned axonal associations with symbols in other modules. In each module, this competition is controlled, as in an individual muscle, by a single graded (i.e., analog) thought control signal. The final result of this confabulation process is a single active symbol, the expression of which also results in launching of action commands that trigger and control subsequent movements and/or thought processes. Modules are manipulated in groups under coordinated, event-contingent control, in a similar manner to our 700 muscles. Confabulation Theory hypothesizes that the control of thinking is a direct evolutionary outgrowth of the control of movement. Establishing a complete understanding of Confabulation Theory will require launching and sustaining a massive new phalanx of confabulation neuroscience research.

  5. Game theory.

    PubMed

    Dufwenberg, Martin

    2011-03-01

    Game theory is a toolkit for examining situations where decision makers influence each other. I discuss the nature of game-theoretic analysis, the history of game theory, why game theory is useful for understanding human psychology, and why game theory has played a key role in the recent explosion of interest in the field of behavioral economics. WIREs Cogni Sci 2011 2 167-173 DOI: 10.1002/wcs.119 For further resources related to this article, please visit the WIREs website.

  6. Graph Theory

    SciTech Connect

    Sanfilippo, Antonio P.

    2005-12-27

    Graph theory is a branch of discrete combinatorial mathematics that studies the properties of graphs. The theory was pioneered by the Swiss mathematician Leonhard Euler in the 18th century, commenced its formal development during the second half of the 19th century, and has witnessed substantial growth during the last seventy years, with applications in areas as diverse as engineering, computer science, physics, sociology, chemistry and biology. Graph theory has also had a strong impact in computational linguistics by providing the foundations for the theory of features structures that has emerged as one of the most widely used frameworks for the representation of grammar formalisms.

  7. Areal Theory

    NASA Astrophysics Data System (ADS)

    Curtright, Thomas

    2002-07-01

    New features are described for models with multi-particle area-dependent potentials, in any number of dimensions. The corresponding many-body field theories are investigated for classical configurations. Some explicit solutions are given, and some conjectures are made about chaos in such field theories.

  8. Collaboration Theory

    ERIC Educational Resources Information Center

    Colbry, Stephanie; Hurwitz, Marc; Adair, Rodger

    2014-01-01

    Theories of collaboration exist at the interfirm and intergroup level, but not the intragroup or team level. Team interactions are often framed in terms of leadership and followership, a categorization which may, or may not, accurately reflect the dynamics of intragroup interactions. To create a grounded theory of collaboration, the Farmer's…

  9. Perspective: Nonadiabatic dynamics theory

    NASA Astrophysics Data System (ADS)

    Tully, John C.

    2012-12-01

    Nonadiabatic dynamics—nuclear motion evolving on multiple potential energy surfaces—has captivated the interest of chemists for decades. Exciting advances in experimentation and theory have combined to greatly enhance our understanding of the rates and pathways of nonadiabatic chemical transformations. Nevertheless, there is a growing urgency for further development of theories that are practical and yet capable of reliable predictions, driven by fields such as solar energy, interstellar and atmospheric chemistry, photochemistry, vision, single molecule electronics, radiation damage, and many more. This Perspective examines the most significant theoretical and computational obstacles to achieving this goal, and suggests some possible strategies that may prove fruitful.

  10. Gauge theories on compact toric surfaces, conformal field theories and equivariant Donaldson invariants

    NASA Astrophysics Data System (ADS)

    Bershtein, Mikhail; Bonelli, Giulio; Ronzani, Massimiliano; Tanzini, Alessandro

    2017-08-01

    We show that equivariant Donaldson polynomials of compact toric surfaces can be calculated as residues of suitable combinations of Virasoro conformal blocks, by building on AGT correspondence between N = 2 supersymmetric gauge theories and two-dimensional conformal field theory.

  11. Projected coupled cluster theory

    NASA Astrophysics Data System (ADS)

    Qiu, Yiheng; Henderson, Thomas M.; Zhao, Jinmo; Scuseria, Gustavo E.

    2017-08-01

    Coupled cluster theory is the method of choice for weakly correlated systems. But in the strongly correlated regime, it faces a symmetry dilemma, where it either completely fails to describe the system or has to artificially break certain symmetries. On the other hand, projected Hartree-Fock theory captures the essential physics of many kinds of strong correlations via symmetry breaking and restoration. In this work, we combine and try to retain the merits of these two methods by applying symmetry projection to broken symmetry coupled cluster wave functions. The non-orthogonal nature of states resulting from the application of symmetry projection operators furnishes particle-hole excitations to all orders, thus creating an obstacle for the exact evaluation of overlaps. Here we provide a solution via a disentanglement framework theory that can be approximated rigorously and systematically. Results of projected coupled cluster theory are presented for molecules and the Hubbard model, showing that spin projection significantly improves unrestricted coupled cluster theory while restoring good quantum numbers. The energy of projected coupled cluster theory reduces to the unprojected one in the thermodynamic limit, albeit at a much slower rate than projected Hartree-Fock.

  12. Simultaneous control of emission localization and two-photon absorption efficiency in dissymmetrical chromophores

    SciTech Connect

    Tretiak, Sergei

    2009-01-01

    The aim of the present work is to demonstrate that combined spectral tuning of fluorescence and two-photon absorption (TPA) properties of multipolar chromophores can be achieved by introduction of slight electronic chemical dissymmetry. In that perspective, two novel series of structurally related chromophores have been designed and studied: a first series based on rod-like quadrupolar chromophores bearing different electron-donating (D) end groups and a second series based on three-branched octupolar chromophores built from a trigonal donating moiety and bearing various acceptor (A) peripheral groups. The influence of the electronic dissymmetry is investigated by combined experimental and theoretical studies of the linear and nonlinear optical properties of dissymmetric chromophores compared to their symmetrical counterparts. In both types of systems (i.e. quadrupoles and octupoles) experiments and theory reveal that excitation is essentially delocalized and that excitation involves synchronized charge redistribution between the different D and A moieties within the multipolar structure (i.e. concerted intramolecular charge transfer). In contrast, the emission stems only from a particular dipolar subunit bearing the strongest D or A moieties due to fast excitation localization after excitation prior to emission. Hence control of emission characteristics (polarization and emission spectrum) in addition to localization can be achieved by controlled introduction of electronic dissymmetry (i.e. replacement of one of the D or A end-groups by a slightly stronger D{prime} or A{prime} units). Interestingly dissymmetrical functionalization of both quadrupolar and octupolar compounds does not lead to significant loss in TPA responses and can even be beneficial due to the spectral broadening and peak position tuning that it allows. This study thus reveals an original molecular engineering route strategy allowing major TPA enhancement in multipolar structures due to concerted

  13. Activity Theory.

    ERIC Educational Resources Information Center

    Koschmann, Timothy; Roschelle, Jeremy; Nardi, Bonnie A.

    1998-01-01

    Includes three articles that discuss activity theory, based on "Context and Consciousness." Topics include human-computer interaction; computer interfaces; hierarchical structuring; mediation; contradictions and development; failure analysis; and designing educational technology. (LRW)

  14. Activity Theory.

    ERIC Educational Resources Information Center

    Koschmann, Timothy; Roschelle, Jeremy; Nardi, Bonnie A.

    1998-01-01

    Includes three articles that discuss activity theory, based on "Context and Consciousness." Topics include human-computer interaction; computer interfaces; hierarchical structuring; mediation; contradictions and development; failure analysis; and designing educational technology. (LRW)

  15. Dual combination combination multi switching synchronization of eight chaotic systems

    NASA Astrophysics Data System (ADS)

    Khan, Ayub; Khattar, Dinesh; Prajapati, Nitish

    2017-08-01

    In this paper, a novel scheme for synchronizing four drive and four response systems is proposed by the authors. The idea of multi switching and dual combination synchronization is extended to dual combination-combination multi switching synchronization involving eight chaotic systems and is a first of its kind. Due to the multiple combination of chaotic systems and multi switching the resultant dynamic behaviour is so complex that, in communication theory, transmission and security of the resultant signal is more effective. Using Lyapunov stability theory, sufficient conditions are achieved and suitable controllers are designed to realise the desired synchronization. Corresponding theoretical analysis is presented and numerical simulations performed to demonstrate the effectiveness of the proposed scheme.

  16. Theory of cortical function

    PubMed Central

    Heeger, David J.

    2017-01-01

    Most models of sensory processing in the brain have a feedforward architecture in which each stage comprises simple linear filtering operations and nonlinearities. Models of this form have been used to explain a wide range of neurophysiological and psychophysical data, and many recent successes in artificial intelligence (with deep convolutional neural nets) are based on this architecture. However, neocortex is not a feedforward architecture. This paper proposes a first step toward an alternative computational framework in which neural activity in each brain area depends on a combination of feedforward drive (bottom-up from the previous processing stage), feedback drive (top-down context from the next stage), and prior drive (expectation). The relative contributions of feedforward drive, feedback drive, and prior drive are controlled by a handful of state parameters, which I hypothesize correspond to neuromodulators and oscillatory activity. In some states, neural responses are dominated by the feedforward drive and the theory is identical to a conventional feedforward model, thereby preserving all of the desirable features of those models. In other states, the theory is a generative model that constructs a sensory representation from an abstract representation, like memory recall. In still other states, the theory combines prior expectation with sensory input, explores different possible perceptual interpretations of ambiguous sensory inputs, and predicts forward in time. The theory, therefore, offers an empirically testable framework for understanding how the cortex accomplishes inference, exploration, and prediction. PMID:28167793

  17. Theory of cortical function.

    PubMed

    Heeger, David J

    2017-02-21

    Most models of sensory processing in the brain have a feedforward architecture in which each stage comprises simple linear filtering operations and nonlinearities. Models of this form have been used to explain a wide range of neurophysiological and psychophysical data, and many recent successes in artificial intelligence (with deep convolutional neural nets) are based on this architecture. However, neocortex is not a feedforward architecture. This paper proposes a first step toward an alternative computational framework in which neural activity in each brain area depends on a combination of feedforward drive (bottom-up from the previous processing stage), feedback drive (top-down context from the next stage), and prior drive (expectation). The relative contributions of feedforward drive, feedback drive, and prior drive are controlled by a handful of state parameters, which I hypothesize correspond to neuromodulators and oscillatory activity. In some states, neural responses are dominated by the feedforward drive and the theory is identical to a conventional feedforward model, thereby preserving all of the desirable features of those models. In other states, the theory is a generative model that constructs a sensory representation from an abstract representation, like memory recall. In still other states, the theory combines prior expectation with sensory input, explores different possible perceptual interpretations of ambiguous sensory inputs, and predicts forward in time. The theory, therefore, offers an empirically testable framework for understanding how the cortex accomplishes inference, exploration, and prediction.

  18. Compatible quantum theory

    NASA Astrophysics Data System (ADS)

    Friedberg, R.; Hohenberg, P. C.

    2014-09-01

    Formulations of quantum mechanics (QM) can be characterized as realistic, operationalist, or a combination of the two. In this paper a realistic theory is defined as describing a closed system entirely by means of entities and concepts pertaining to the system. An operationalist theory, on the other hand, requires in addition entities external to the system. A realistic formulation comprises an ontology, the set of (mathematical) entities that describe the system, and assertions, the set of correct statements (predictions) the theory makes about the objects in the ontology. Classical mechanics is the prime example of a realistic physical theory. A straightforward generalization of classical mechanics to QM is hampered by the inconsistency of quantum properties with classical logic, a circumstance that was noted many years ago by Birkhoff and von Neumann. The present realistic formulation of the histories approach originally introduced by Griffiths, which we call ‘compatible quantum theory (CQT)’, consists of a ‘microscopic’ part (MIQM), which applies to a closed quantum system of any size, and a ‘macroscopic’ part (MAQM), which requires the participation of a large (ideally, an infinite) system. The first (MIQM) can be fully formulated based solely on the assumption of a Hilbert space ontology and the noncontextuality of probability values, relying in an essential way on Gleason's theorem and on an application to dynamics due in large part to Nistico. Thus, the present formulation, in contrast to earlier ones, derives the Born probability formulas and the consistency (decoherence) conditions for frameworks. The microscopic theory does not, however, possess a unique corpus of assertions, but rather a multiplicity of contextual truths (‘c-truths’), each one associated with a different framework. This circumstance leads us to consider the microscopic theory to be physically indeterminate and therefore incomplete, though logically coherent. The

  19. Predictions from String Theory

    NASA Astrophysics Data System (ADS)

    Kuflik, Eric

    String theory is the leading candidate for an underlying theory of nature, as it provides a framework through which to address critical questions left unanswered by the Standard Model and Supersymmetry. A number of predictions of string constructions can be empirically tested at the Large Hadron Collider (LHC) and dark matter experiments. In this work I aim to make generic predictions of string theory, while combining bottom-up approaches to fill in the gaps in our understanding of string theory to make predictions for current and upcoming experiments. First I study moduli masses and claim that moduli dominated the energy density of the universe prior to big bang nucleosynthesis. We argue that in any string theory with stabilized moduli there will be at least one modulus field whose mass is of order the gravitino mass. Cosmology then generically requires the gravitino mass to be greater than 30 TeV and the early cosmological history of the Universe be non-thermal. We are then led to believe that the best-motivated channel for early LHC discovery is gluino pair-production events decaying into a high multiplicity of third generation quarks. We analyze signals and background at the LHC for 7 TeV center of mass energy for 1 fb -1 integrated luminosity, suggesting a reach for gluinos for masses about 650 GeV. Second, I seek to construct a Grand Unified Theory (GUT) within different branches of string theory. One promising GUT, developed outside of string theory, is Flipped-SU(5), which I show has serious phenomenological difficulties. I demonstrate both that Flipped-SU(5) requires an R-symmetry to solve the mu-problem, and that no R-symmetries exist in F-theory. Thus Flipped-SU(5) cannot serve as a GUT within F-theory. Similarly, I seek to construct a GUT within M-theory. My study is based upon the discrete symmetry proposed by Witten that forbids the mu-term and solves the doublet-triplet splitting problem, but does not address how the symmetry might be broken. I find

  20. Compatible quantum theory.

    PubMed

    Friedberg, R; Hohenberg, P C

    2014-09-01

    Formulations of quantum mechanics (QM) can be characterized as realistic, operationalist, or a combination of the two. In this paper a realistic theory is defined as describing a closed system entirely by means of entities and concepts pertaining to the system. An operationalist theory, on the other hand, requires in addition entities external to the system. A realistic formulation comprises an ontology, the set of (mathematical) entities that describe the system, and assertions, the set of correct statements (predictions) the theory makes about the objects in the ontology. Classical mechanics is the prime example of a realistic physical theory. A straightforward generalization of classical mechanics to QM is hampered by the inconsistency of quantum properties with classical logic, a circumstance that was noted many years ago by Birkhoff and von Neumann. The present realistic formulation of the histories approach originally introduced by Griffiths, which we call 'compatible quantum theory (CQT)', consists of a 'microscopic' part (MIQM), which applies to a closed quantum system of any size, and a 'macroscopic' part (MAQM), which requires the participation of a large (ideally, an infinite) system. The first (MIQM) can be fully formulated based solely on the assumption of a Hilbert space ontology and the noncontextuality of probability values, relying in an essential way on Gleason's theorem and on an application to dynamics due in large part to Nistico. Thus, the present formulation, in contrast to earlier ones, derives the Born probability formulas and the consistency (decoherence) conditions for frameworks. The microscopic theory does not, however, possess a unique corpus of assertions, but rather a multiplicity of contextual truths ('c-truths'), each one associated with a different framework. This circumstance leads us to consider the microscopic theory to be physically indeterminate and therefore incomplete, though logically coherent. The completion of the theory

  1. Effective theories of universal theories

    SciTech Connect

    Wells, James D.; Zhang, Zhengkang

    2016-01-20

    It is well-known but sometimes overlooked that constraints on the oblique parameters (most notably S and T parameters) are generally speaking only applicable to a special class of new physics scenarios known as universal theories. The oblique parameters should not be associated with Wilson coefficients in a particular operator basis in the effective field theory (EFT) framework, unless restrictions have been imposed on the EFT so that it describes universal theories. Here, we work out these restrictions, and present a detailed EFT analysis of universal theories. We find that at the dimension-6 level, universal theories are completely characterized by 16 parameters. They are conveniently chosen to be: 5 oblique parameters that agree with the commonly-adopted ones, 4 anomalous triple-gauge couplings, 3 rescaling factors for the h3, hff, hV V vertices, 3 parameters for hV V vertices absent in the Standard Model, and 1 four-fermion coupling of order yf2. Furthermore, all these parameters are defined in an unambiguous and basis-independent way, allowing for consistent constraints on the universal theories parameter space from precision electroweak and Higgs data.

  2. Effective theories of universal theories

    DOE PAGES

    Wells, James D.; Zhang, Zhengkang

    2016-01-20

    It is well-known but sometimes overlooked that constraints on the oblique parameters (most notably S and T parameters) are generally speaking only applicable to a special class of new physics scenarios known as universal theories. The oblique parameters should not be associated with Wilson coefficients in a particular operator basis in the effective field theory (EFT) framework, unless restrictions have been imposed on the EFT so that it describes universal theories. Here, we work out these restrictions, and present a detailed EFT analysis of universal theories. We find that at the dimension-6 level, universal theories are completely characterized by 16more » parameters. They are conveniently chosen to be: 5 oblique parameters that agree with the commonly-adopted ones, 4 anomalous triple-gauge couplings, 3 rescaling factors for the h3, hff, hV V vertices, 3 parameters for hV V vertices absent in the Standard Model, and 1 four-fermion coupling of order yf2. Furthermore, all these parameters are defined in an unambiguous and basis-independent way, allowing for consistent constraints on the universal theories parameter space from precision electroweak and Higgs data.« less

  3. Antifungal combinations.

    PubMed

    Vitale, Roxana G; Afeltra, Javier; Dannaoui, Eric

    2005-01-01

    The increase in fungal infections and the change in fungal epidemiology is caused by the extensive use of antifungal agents to treat fungal infections that are being diagnosed in severly immunocompromised hosts. In addition, opportunistic fungal infections resistant to antifungal drugs have become increasingly common, and the armamentarium for treatment remains limited. A possible approach to overcoming these problems is to combine antifungal drugs, especially if the mechanisms of action are different. The in vitro test is the first step to evaluate possible antifungal combinations. In this chapter, the three most frequently used metholodologies are described: checkerboard, E-test, and time-kill curves. The description of each technique and intrepretaion of the results are addressed in detail.

  4. Combination Light

    NASA Astrophysics Data System (ADS)

    1990-01-01

    The Rayovac TANDEM is an advanced technology combination work light and general purpose flashlight that incorporates several NASA technologies. The TANDEM functions as two lights in one. It features a long range spotlight and wide angle floodlight; simple one-hand electrical switching changes the beam from spot to flood. TANDEM developers made particular use of NASA's extensive research in ergonomics in the TANDEM's angled handle, convenient shape and different orientations. The shatterproof, water resistant plastic casing also draws on NASA technology, as does the shape and beam distance of the square diffused flood. TANDEM's heavy duty magnet that permits the light to be affixed to any metal object borrows from NASA research on rare earth magnets that combine strong magnetic capability with low cost. Developers used a NASA-developed ultrasonic welding technique in the light's interior.

  5. Multiswitching combination-combination synchronization of chaotic systems

    NASA Astrophysics Data System (ADS)

    Khan, Ayub; Khattar, Dinesh; Prajapati, Nitish

    2017-03-01

    In this paper, a novel synchronization scheme is investigated for a class of chaotic systems. The multiswitching synchronization scheme is extended to the combination-combination synchronization scheme such that the combination of state variables of two drive systems synchronize with different combination of state variables of two response systems, simultaneously. The new scheme, multiswitching combination-combination synchronization (MSCCS), is a notable extension of the earlier multiswitching schemes concerning only the single drive-response system model. Various multiswitching modified projective synchronization schemes are obtained as special cases of MSCCS, for a suitable choice of scaling factors. Suitable controllers have been designed and using Lyapunov stability theory sufficient condition is obtained to achieve MSCCS between four hyperchaotic systems and the corresponding theoretical proof is given. Numerical simulations are performed to validate the theoretical results.

  6. Conference on Operator Theory, Wavelet Theory and Control Theory

    DTIC Science & Technology

    1993-09-30

    Bourbaki 662 (1985-1986). [9] Meyer, Y., Ondelettes et operateurs I, Hermann editeurs des sciences et des arts, 1990. [10] Natanson, I. P., Theory of...OPERATOR THEORY , WAVELET THEORY & CONTROL THEORY (U)F 6. AUTHOR(S) 2304/ES Professor Xingde Dai F49620-93-1-0180 7. PERFORMING ORGANIZATION NAME(S) AND...1STRIBUTION IS UNLIMITED UTL 13. ABSTRACT (Maximum 200 words) The conference on Interaction Between Operator Theory , Wavelet Theory and Control Theory

  7. Abstract class field theory (a finitary approach)

    SciTech Connect

    Ershov, Yu L

    2003-02-28

    A definition of the reciprocity homomorphism in Neukirch's abstract class field theory is given. This definition uses fairly large additional non-ramified extensions, but they are all finite. This will enable one to apply the theory thus constructed to the effectivization (algorithmization) of local and global class field theory alike. The combination of Neukirch's and Hazewinkel's approaches used in the paper clarifies class field theory even at the abstract level of exposition.

  8. Control Theory.

    ERIC Educational Resources Information Center

    Toso, Robert B.

    2000-01-01

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

  9. Control Theory.

    ERIC Educational Resources Information Center

    Toso, Robert B.

    2000-01-01

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

  10. Leadership Theories.

    ERIC Educational Resources Information Center

    Sferra, Bobbie A.; Paddock, Susan C.

    This booklet describes various theoretical aspects of leadership, including the proper exercise of authority, effective delegation, goal setting, exercise of control, assignment of responsibility, performance evaluation, and group process facilitation. It begins by describing the evolution of general theories of leadership from historic concepts…

  11. Large-Nc Gauge Theory and Chiral Random Matrix Theory

    NASA Astrophysics Data System (ADS)

    Hanada, Masanori; Lee, Jong-Wan; Yamada, Norikazu

    Effective theory approaches and the large-Nc limit are useful for studying the strongly coupled gauge theories. In this talk we consider how the chiral random matrix theory (χRMT) can be used in the study of large-Nc gauge theories. It turns out the parameter regions, in which each of these two approaches are valid, are different. Still, however, we show that the breakdown of chiral symmetry can be detected by combining the large-Nc argument and the χRMT with some cares. As a demonstration, we numerically study the four dimensional SU(Nc) gauge theory with Nf = 2 heavy adjoint fermions on a 24 lattice by using Monte-Carlo simulations, which is related to the infinite volume lattice through the Eguchi-Kawai equivalence.

  12. Analgesic combinations

    PubMed Central

    Raffa, Robert B.; Pergolizzi, Joseph V.; Tallarida, Ronald J.

    2010-01-01

    When the pathophysiology of a medical condition is multi-modal, i.e., related to multiple physiological causes or mediated by multiple pathways, the optimal strategy can be to use a drug or a combination of drugs that contribute multiple mechanisms to the therapeutic endpoint. In such situations, a rational multi-modal approach can also result in the fewest adverse effects. We discuss the quantitative analysis of multi-modal action using the treatment of pain as a practical example and give examples of its application to some widely used analgesic drugs. PMID:20338825

  13. Theory Survey or Survey Theory?

    ERIC Educational Resources Information Center

    Dean, Jodi

    2010-01-01

    Matthew Moore's survey of political theorists in U.S. American colleges and universities is an impressive contribution to political science (Moore 2010). It is the first such survey of political theory as a subfield, the response rate is very high, and the answers to the survey questions provide new information about how political theorists look…

  14. Theory Survey or Survey Theory?

    ERIC Educational Resources Information Center

    Dean, Jodi

    2010-01-01

    Matthew Moore's survey of political theorists in U.S. American colleges and universities is an impressive contribution to political science (Moore 2010). It is the first such survey of political theory as a subfield, the response rate is very high, and the answers to the survey questions provide new information about how political theorists look…

  15. Variational formulation of two scalar-tetradic theories of gravitation

    SciTech Connect

    Saez, D.

    1983-06-15

    In this paper we obtain two scalar-tetradic theories of gravitation (theories A and B) from a variational principle. In these theories the gravitational energy is localized and the principle of equivalence holds. They combine some aspects of Moller theory and the Brans-Dicke theory. The first-order approximations and an introduction to the study of both theories in the static spherically symmetric case are presented.

  16. Adaptive Motivation Theory

    DTIC Science & Technology

    1985-06-01

    working taxonomy with the following categories: Need Theory, Reinforcement Theory, Balance Theory, Expectancy Theory and Goal Setting Theory. This taxonomy...that must be met in order to create positive emotional states or eliminate tension. Reinforcement theory 6 !A Variously known as incentive theory, S-R...theory, the associationist approach, behaviorism or reinforcement theory, this groups of theories includes those approaches which pay particular

  17. Helicopter theory

    NASA Technical Reports Server (NTRS)

    Johnson, W.

    1980-01-01

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

  18. Demystifying theory and its use in improvement

    PubMed Central

    Davidoff, Frank; Dixon-Woods, Mary; Leviton, Laura; Michie, Susan

    2015-01-01

    The role and value of theory in improvement work in healthcare has been seriously underrecognised. We join others in proposing that more informed use of theory can strengthen improvement programmes and facilitate the evaluation of their effectiveness. Many professionals, including improvement practitioners, are unfortunately mystified—and alienated—by theory, which discourages them from using it in their work. In an effort to demystify theory we make the point in this paper that, far from being discretionary or superfluous, theory (‘reason-giving’), both informal and formal, is intimately woven into virtually all human endeavour. We explore the special characteristics of grand, mid-range and programme theory; consider the consequences of misusing theory or failing to use it; review the process of developing and applying programme theory; examine some emerging criteria of ‘good’ theory; and emphasise the value, as well as the challenge, of combining informal experience-based theory with formal, publicly developed theory. We conclude that although informal theory is always at work in improvement, practitioners are often not aware of it or do not make it explicit. The germane issue for improvement practitioners, therefore, is not whether they use theory but whether they make explicit the particular theory or theories, informal and formal, they actually use. PMID:25616279

  19. The study of the action of self-friction field on the atom and molecular structures by using combined Hartree-Fock-Roothaan theory for closed and open shells of any symmetry

    NASA Astrophysics Data System (ADS)

    Mamedov, B. A.; Çopuroğlu, E.

    2016-06-01

    In this work, we study the effects of self-friction field on the states of a single configuration of closed and open shells by using the Combined Hartree-Fock-Roothaan equations for atomic-molecular and nuclear systems. Here, we present a program that implements the evaluation of the various properties of atoms and molecular systems with respect to the various values of self-friction quantum numbers. An especially fast and accurate algorithm for the calculation of the self-friction multicenter molecular integrals is obtained by using one-range addition theorems. To demonstrate the action of self-friction field on the atomic and molecular systems we have performed the calculations of H2O, CH3, CH2 and NH3 molecules. For the derivations of the orbital, kinetic and total energies and linear combination coefficients, the results are given for various values of self-friction quantum numbers. For various values of self-friction quantum numbers the obtained results of the orbital, kinetic and total energies and linear combination coefficients have been analyzed.

  20. Ethyl 3-[1-(5,5-dimethyl-2-oxo-1,3,2-dioxaphosphorin-2-yl)propan-2-ylidene]carbazate: a combined X-ray and density functional theory (DFT) study.

    PubMed

    Arfaoui, Youssef; Kouass, Salah; Salah, Nesrine; Ben Akacha, Azaiez; Guesmi, Abderrahmen

    2010-07-01

    In the title compound, C(11)H(21)N(2)O(5)P, one of the two carbazate N atoms is involved in the C=N double bond and the H atom of the second N atom is engaged in an intramolecular hydrogen bond with an O atom from the dimethylphosphorin-2-yl group, which is in an uncommon cis position with respect to the carbamate group. The cohesion of the crystal structure is also reinforced by weak intermolecular hydrogen bonds. Density functional theory (DFT) calculations at the B3LYP/6-311++g(2d,2p) level revealed the lowest energy structure to have a Z configuration at the C=N bond, which is consistent with the configuration found in the X-ray crystal structure, as well as a less stable E counterpart which lies 2.0 kcal mol(-1) higher in potential energy. Correlations between the experimental and computational studies are discussed.

  1. Metallic behavior and negative differential resistance properties of (InAs)n (n = 2 - 4) molecule cluster junctions via a combined non-equilibrium Green's function and density functional theory study

    NASA Astrophysics Data System (ADS)

    Wang, Qi; Zhang, Jianbing; Li, Rong; Xu, Yuanlan; Miao, Xiangshui; Zhang, Daoli

    2014-06-01

    In this present work, the geometric structures and electronic transport properties of (InAs)n (n = 2, 3, 4) molecule cluster junctions are comparatively investigated using NEGF combined with DFT. Results indicate that all (InAs)n molecule cluster junctions present metallic behavior at the low applied biases ([-2V, 2V]), while NDR appears at a certain high bias range. Our calculation shows that the current of (InAs)4 molecule cluster-based junction is almost the largest at any bias. The mechanisms of the current-voltage characteristics of all the three molecule cluster junctions are proposed.

  2. Metallic behavior and negative differential resistance properties of (InAs){sub n} (n = 2 − 4) molecule cluster junctions via a combined non–equilibrium Green's function and density functional theory study

    SciTech Connect

    Wang, Qi; Li, Rong; Xu, Yuanlan; Zhang, Jianbing; Miao, Xiangshui; Zhang, Daoli

    2014-06-21

    In this present work, the geometric structures and electronic transport properties of (InAs){sub n} (n = 2, 3, 4) molecule cluster junctions are comparatively investigated using NEGF combined with DFT. Results indicate that all (InAs){sub n} molecule cluster junctions present metallic behavior at the low applied biases ([−2V, 2V]), while NDR appears at a certain high bias range. Our calculation shows that the current of (InAs){sub 4} molecule cluster–based junction is almost the largest at any bias. The mechanisms of the current–voltage characteristics of all the three molecule cluster junctions are proposed.

  3. Decompression Theory.

    DTIC Science & Technology

    1980-06-25

    new experiments at 30 m ( 4 ATA) is appropriate for comparing N2 and He with respect to half times and surfacing ratios. Table 4 demonstrates the...THEORY C4 i t44 4 ’I9 41-*1 ai4 p80 7 10 009 UM"tUBNC*nm N4MDOf 29WS (DT) 6-25-80 The Seventeenth Undersea Medical Society Workshop DECOMPRESSION...Hamilton, Jr., Ph.D. Edward L Beckman, M.D. Hamilton Research Ltd. University of Hawaii 80 Grove Street School of Medicine Tarrytown, New York 10591

  4. Theory of ultracold superstrings

    SciTech Connect

    Snoek, Michiel; Vandoren, S.; Stoof, H. T. C.

    2006-09-15

    The combination of a vortex line in a one-dimensional optical lattice with fermions bound to the vortex core makes up an ultracold superstring. We give a detailed derivation of the way to make this supersymmetric string in the laboratory. In particular, we discuss the presence of a fermionic bound state in the vortex core and the tuning of the laser beams needed to achieve supersymmetry. Moreover, we discuss experimental consequences of supersymmetry and identify the precise supersymmetry in the problem. Finally, we make the mathematical connection with string theory.

  5. Mechanism of the hydride transfer between Anabaena Tyr303Ser FNR(rd)/FNR(ox) and NADP+/H. A combined pre-steady-state kinetic/ensemble-averaged transition-state theory with multidimensional tunneling study.

    PubMed

    Lans, Isaias; Peregrina, José Ramón; Medina, Milagros; Garcia-Viloca, Mireia; González-Lafont, Angels; Lluch, José M

    2010-03-11

    The flavoenzyme ferredoxin-NADP(+) reductase (FNR) catalyzes the production of NADPH during photosynthesis. The hydride-transfer reactions between the Anabaena mutant Tyr303Ser FNR(rd)/FNR(ox) and NADP(+)/H have been studied both experimentally and theoretically. Stopped-flow pre-steady-state kinetic measurements have shown that, in contrast to that observed for WT FNR, the physiological hydride transfer from Tyr303Ser FNR(rd) to NADP(+) does not occur. Conversely, the reverse reaction does take place with a rate constant just slightly slower than for WT FNR. This latter process shows temperature-dependent rates, but essentially temperature independent kinetic isotope effects, suggesting the reaction takes place following the vibration-driven tunneling model. In turn, ensemble-averaged variational transition-state theory with multidimensional tunneling calculations provide reaction rate constant values and kinetic isotope effects that agree with the experimental results, the experimental and the theoretical values for the reverse process being noticeably similar. The reaction mechanism behind these hydride transfers has been analyzed. The formation of a close contact ionic pair FADH(-):NADP(+) surrounded by the polar environment of the enzyme in the reactant complex of the mutant might be the cause of the huge difference between the direct and the reverse reaction.

  6. Calculating the equation of state parameters and predicting the spinodal curve of isotactic polypropylene/poly(ethylene-co-octene) blend by molecular dynamics simulations combined with Sanchez-Lacombe lattice fluid theory.

    PubMed

    Li, Zhan-Wei; Lu, Zhong-Yuan; Sun, Zhao-Yan; Li, Ze-Sheng; An, Li-Jia

    2007-05-31

    Molecular dynamics simulations are adopted to calculate the equation of state characteristic parameters P*, rho*, and T* of isotactic polypropylene (iPP) and poly(ethylene-co-octene) (PEOC), which can be further used in the Sanchez-Lacombe lattice fluid theory (SLLFT) to describe the respective physical properties. The calculated T* is a function of the temperature, which was also found in the literature. To solve this problem, we propose a Boltzmann fitting of the data and obtain T* at the high-temperature limit. With these characteristic parameters, the pressure-volume-temperature (PVT) data of iPP and PEOC are predicted by the SLLFT equation of state. To justify the correctness of our results, we also obtain the PVT data for iPP and PEOC by experiments. Good agreement is found between the two sets of data. By integrating the Euler-Lagrange equation and the Cahn-Hilliard relation, we predict the density profiles and the surface tensions for iPP and PEOC, respectively. Furthermore, a recursive method is proposed to obtain the characteristic interaction energy parameter between iPP and PEOC. This method, which does not require fitting to the experimental phase equilibrium data, suggests an alternative way to predict the phase diagrams that are not easily obtained in experiments. As an example, in the framework of SLLFT, the spinodal curve for the iPP/PEOC blend is predicted at the low molecular weights that are used in the simulations.

  7. Concurrent Validity and Holland's Theory

    ERIC Educational Resources Information Center

    Gaffey, Robert L.; Walsh, W. Bruce

    1974-01-01

    This study was designed to explore two areas: (1) the concurrent validity of Holland's theory for employed men using four different operational definitions of vocational orientation, and (2) the relationships among all possible combinations of same named scales across the four inventories. Findings tend to support the concurrent validity of…

  8. Concurrent Validity and Holland's Theory

    ERIC Educational Resources Information Center

    Gaffey, Robert L.; Walsh, W. Bruce

    1974-01-01

    This study was designed to explore two areas: (1) the concurrent validity of Holland's theory for employed men using four different operational definitions of vocational orientation, and (2) the relationships among all possible combinations of same named scales across the four inventories. Findings tend to support the concurrent validity of…

  9. Generalizing Prototype Theory: A Formal Quantum Framework

    PubMed Central

    Aerts, Diederik; Broekaert, Jan; Gabora, Liane; Sozzo, Sandro

    2016-01-01

    Theories of natural language and concepts have been unable to model the flexibility, creativity, context-dependence, and emergence, exhibited by words, concepts and their combinations. The mathematical formalism of quantum theory has instead been successful in capturing these phenomena such as graded membership, situational meaning, composition of categories, and also more complex decision making situations, which cannot be modeled in traditional probabilistic approaches. We show how a formal quantum approach to concepts and their combinations can provide a powerful extension of prototype theory. We explain how prototypes can interfere in conceptual combinations as a consequence of their contextual interactions, and provide an illustration of this using an intuitive wave-like diagram. This quantum-conceptual approach gives new life to original prototype theory, without however making it a privileged concept theory, as we explain at the end of our paper. PMID:27065436

  10. Generalizing Prototype Theory: A Formal Quantum Framework.

    PubMed

    Aerts, Diederik; Broekaert, Jan; Gabora, Liane; Sozzo, Sandro

    2016-01-01

    Theories of natural language and concepts have been unable to model the flexibility, creativity, context-dependence, and emergence, exhibited by words, concepts and their combinations. The mathematical formalism of quantum theory has instead been successful in capturing these phenomena such as graded membership, situational meaning, composition of categories, and also more complex decision making situations, which cannot be modeled in traditional probabilistic approaches. We show how a formal quantum approach to concepts and their combinations can provide a powerful extension of prototype theory. We explain how prototypes can interfere in conceptual combinations as a consequence of their contextual interactions, and provide an illustration of this using an intuitive wave-like diagram. This quantum-conceptual approach gives new life to original prototype theory, without however making it a privileged concept theory, as we explain at the end of our paper.

  11. Translation of Ligand-Centered Hydrogen Evolution Reaction Activity and Mechanism of a Rhenium-Thiolate from Solution to Modified Electrodes: A Combined Experimental and Density Functional Theory Study.

    PubMed

    Zhang, Wuyu; Haddad, Andrew Z; Garabato, Brady D; Kozlowski, Pawel M; Buchanan, Robert M; Grapperhaus, Craig A

    2017-02-20

    The homogeneous, nonaqueous catalytic activity of the rhenium-thiolate complex ReL3 (L = diphenylphosphinobenzenethiolate) for the hydrogen evolution reaction (HER) has been transferred from nonaqueous homogeneous to aqueous heterogeneous conditions by immobilization on a glassy carbon electrode surface. A series of modified electrodes based on ReL3 and its oxidized precursor [ReL3][PF6] were fabricated by drop-cast methods, yielding catalytically active species with HER overpotentials for a current density of 10 mA/cm(2), ranging from 357 to 919 mV. The overpotential correlates with film resistance as measured by electrochemical impedance spectroscopy and film morphology as determined by scanning and transmission electron microscopy. The lowest overpotential was for films based on the ionic [ReL3][PF6] precursor with the inclusion of carbon black. Stability measurements indicate a 2 to 3 h conditioning period in which the overpotential increases, after which no change in activity is observed within 24 h or upon reimmersion in fresh aqueous, acidic solution. Electronic spectroscopy results are consistent with ReL3 as the active species on the electrode surface; however, the presence of an undetected quantity of catalytically active degradation species cannot be excluded. The HER mechanism was evaluated by Tafel slope analysis, which is consistent with a novel Volmer-Heyrovsky-Tafel-like mechanism that parallels the proposed homogeneous HER pathway. Proposed mechanisms involving traditional metal-hydride processes vs ligand-centered reactivity were examined by density functional theory, including identification and characterization of relevant transition states. The ligand-centered path is energetically favored with protonation of cis-sulfur sites culminating in homolytic S-H bond cleavage with H2 evolution via H atom coupling.

  12. Combined IR/NIR and density functional theory calculations analysis of the solvent effects on frequencies and intensities of the fundamental and overtones of the C ═ O stretching vibrations of acetone and 2-hexanone.

    PubMed

    Chen, Yujing; Morisawa, Yusuke; Futami, Yoshisuke; Czarnecki, Mirosław A; Wang, Hai-Shui; Ozaki, Yukihiro

    2014-04-10

    Vibrational overtone studies primarily focus on X-H stretching overtone transitions, where X is an atom like C, O, N, or S. In contrast, the studies on the C ═ O stretching overtones are very scattered. To advance the research in this field, we measured the fundamental, first, and second overtones of the C ═ O stretching vibration of acetone and 2-hexanone in n-hexane, CCl4, and CHCl3, as well as in the vapor phase using FT-IR/FT-NIR spectroscopy. Density functional theory (DFT) calculations have also been performed to help the assignment of the C ═ O stretching bands and to guide interpretation of the experimental results. It was found that the wavenumbers, absorption intensities, and oscillator strengths of the C ═ O stretching bands show marked solvent dependence. In the fundamental and the first overtone regions, the intensities of the C ═ O stretching vibration were found to be pronouncedly more intense than those of the C-H stretching vibration. In the second overtone region, the intensities of the C-H stretching vibration are comparable to those of the C ═ O stretching vibration. The theoretical and observed decrease in integrated intensity upon going from the fundamental to the first overtone of the C ═ O stretching vibration is around 50, which is significantly larger than those of the O-H, C-H, and S-H stretching vibration. Both the calculated and experimental results suggest that excessive weakness in the C ═ O stretching overtone was shown to be a result of both a low anharmonicity and a substantial reduction in the oscillator strength. These results provide new insight into our understanding of the C ═ O stretching vibration.

  13. Thermal effects in dislocation theory

    NASA Astrophysics Data System (ADS)

    Langer, J. S.

    2016-12-01

    The mechanical behaviors of polycrystalline solids are determined by the interplay between phenomena governed by two different thermodynamic temperatures: the configurational effective temperature that controls the density of dislocations, and the ordinary kinetic-vibrational temperature that controls activated depinning mechanisms and thus deformation rates. This paper contains a review of the effective-temperature theory and its relation to conventional dislocation theories. It includes a simple illustration of how these two thermal effects can combine to produce a predictive theory of spatial heterogeneities such as shear-banding instabilities. Its main message is a plea that conventional dislocation theories be reformulated in a thermodynamically consistent way so that the vast array of observed behaviors can be understood systematically.

  14. Theories of Suggestion

    PubMed Central

    Brown, William

    1928-01-01

    The word “suggestion” has been used in educational, scientific and medical literature in slightly different senses. In psychological medicine the use of suggestion has developed out of the earlier use of hypnotic influence. Charcot defined hypnosis as an artificial hysteria, Bernheim as an artificially increased suggestibility. The two definitions need to be combined to give an adequate account of hypnosis. Moreover, due allowance should be made for the factors of dissociation and of rapport in hypnotic phenomena. The relationships between dissociation, suggestibility, and hypnotizability. Theories of suggestion propounded by Pierre Janet, Freud, McDougall, Pawlow and others. Ernest Jones's theory of the nature of auto-suggestion. Janet explains suggestion in terms of ideo-motor action in which the suggested idea, because of the inactivity of competing ideas, produces its maximum effect. Freud explains rapport in terms of the sex instinct “inhibited in its aim” (transference) and brings in his distinction of “ego” and “ego-ideal” (or “super-ego”) to supplement the theory. Jones explains auto-suggestion in terms of narcissism. McDougall explains hypnotic suggestion in terms of the instinct of self-abasement. But different instincts may supply the driving power to produce suggestion-effects in different circumstances. Such instincts as those of self-preservation (fear) and gregariousness may play their part. Auto-suggestion as a therapeutic factor is badly named. It supplements, but does not supplant the will, and makes complete volition possible. PMID:19986306

  15. Graph-based linear scaling electronic structure theory

    NASA Astrophysics Data System (ADS)

    Niklasson, Anders M. N.; Mniszewski, Susan M.; Negre, Christian F. A.; Cawkwell, Marc J.; Swart, Pieter J.; Mohd-Yusof, Jamal; Germann, Timothy C.; Wall, Michael E.; Bock, Nicolas; Rubensson, Emanuel H.; Djidjev, Hristo

    2016-06-01

    We show how graph theory can be combined with quantum theory to calculate the electronic structure of large complex systems. The graph formalism is general and applicable to a broad range of electronic structure methods and materials, including challenging systems such as biomolecules. The methodology combines well-controlled accuracy, low computational cost, and natural low-communication parallelism. This combination addresses substantial shortcomings of linear scaling electronic structure theory, in particular with respect to quantum-based molecular dynamics simulations.

  16. Graph-based linear scaling electronic structure theory.

    PubMed

    Niklasson, Anders M N; Mniszewski, Susan M; Negre, Christian F A; Cawkwell, Marc J; Swart, Pieter J; Mohd-Yusof, Jamal; Germann, Timothy C; Wall, Michael E; Bock, Nicolas; Rubensson, Emanuel H; Djidjev, Hristo

    2016-06-21

    We show how graph theory can be combined with quantum theory to calculate the electronic structure of large complex systems. The graph formalism is general and applicable to a broad range of electronic structure methods and materials, including challenging systems such as biomolecules. The methodology combines well-controlled accuracy, low computational cost, and natural low-communication parallelism. This combination addresses substantial shortcomings of linear scaling electronic structure theory, in particular with respect to quantum-based molecular dynamics simulations.

  17. A Partial Theory of Executive Succession.

    ERIC Educational Resources Information Center

    Thiemann, Francis C.

    This study has two purposes: (1) To construct a partial theory of succession, and (2) to utilize a method of theory construction which combines some of the concepts of Hans Zetterberg with the principles of formal symbolic logic. A bibliography on succession in complex organizations with entries on descriptive and empirical studies from various…

  18. Improved hardening theory for cyclic plasticity.

    NASA Technical Reports Server (NTRS)

    Vos, R. G.; Armstrong, W. H.

    1973-01-01

    A temperature-dependent version of a combined hardening theory, including isotropic and kinematic hardening, is presented within the framework of recent plasticity formulations. This theory has been found to be especially useful in finite-element analysis of aerospace vehicle engines under conditions of large plastic strain and low-cycle fatigue.

  19. Scandura's Structural Learning Theory: A Critique.

    ERIC Educational Resources Information Center

    Ikegulu, Nelson T.

    This paper offers a pragmatic critique of the instructional prescriptions based on Structural Learning Theory (SLT) conceived by Joseph M. Scandura in 1973. SLT is rooted in clarifying the roles of expository and discovery modes of problem solving in instruction. It is a cognitively oriented model combining learning theories, instructional…

  20. Polarization measurement through combination polarizers

    NASA Astrophysics Data System (ADS)

    Bai, Yunfeng; Li, Linjun; He, Zhelong; Liu, Yanwei; Ma, Cheng; Shi, Guang; Liu, Lu

    2014-02-01

    Polarization measurement approaches only using polarizer and grating is present. The combination polarizers consists of two polarizers: one is γ degree with the X axis; the other is along the Y axis. Binary grating is covered by the combination polarizers, and based on Fraunhofer diffraction, the diffraction intensity formula is deduced. The polarization state of incident light can be gotten by fitting the diffraction pattern with the deduced formula. Compared with the traditional polarization measurement method, this measurement only uses polarizer and grating, therefore, it can be applied to measure a wide wavelength range without replacing device in theory.

  1. {N}=3 four dimensional field theories

    NASA Astrophysics Data System (ADS)

    García-Etxebarria, Iñaki; Regalado, Diego

    2016-03-01

    We introduce a class of four dimensional field theories constructed by quotienting ordinary {N}=4 U(N ) SYM by particular combinations of R-symmetry and SL(2, ℤ) automorphisms. These theories appear naturally on the worldvolume of D3 branes probing terminal singularities in F-theory, where they can be thought of as non-perturbative generalizations of the O3 plane. We focus on cases preserving only 12 supercharges, where the quotient gives rise to theories with coupling fixed at a value of order one. These constructions possess an unconventional large N limit described by a non-trivial F-theory fibration with base AdS 5 × (S 5/ ℤ k ). Upon reduction on a circle the {N}=3 theories flow to well-known {N}=6 ABJM theories.

  2. Strength of orthotropic materials subjected to combined stresses

    Treesearch

    Charles B. Norris

    1962-01-01

    A theory of the strength of orthotropic materials subjected to combined stresses, based on the Henky-von Mises theory of energy due to change of shape, is presented. When this theory is applied to macroscopically isotropic materials, it yields the diagram currently used in design with metals. Equations relating the strength of orthotropic materials subjected to a...

  3. Eight myths on motivating social services workers: theory-based perspectives.

    PubMed

    Latting, J K

    1991-01-01

    A combination of factors has made formal motivational and reward systems rare in human service organizations generally and virtually non-existent in social service agencies. The author reviews eight of these myths by reference to eight motivational theories which refute them: need theory, expectancy theory, feedback theory, equity theory, reinforcement theory, cognitive evaluation theory, goal setting theory, and social influence theory. Although most of these theories have been developed and applied in the private sector, relevant research has also been conducted in social service agencies. The author concludes with a summary of guidelines suggested by the eight theories for motivating human service workers.

  4. Magnetron theory

    NASA Astrophysics Data System (ADS)

    Riyopoulos, Spilios

    1996-03-01

    A guiding center fluid theory is applied to model steady-state, single mode, high-power magnetron operation. A hub of uniform, prescribed density, feeds the current spokes. The spoke charge follows from the continuity equation and the incompressibility of the guiding center flow. Included are the spoke self-fields (DC and AC), obtained by an expansion around the unperturbed (zero-spoke charge) flow in powers of ν/V1, ν, and V1 being the effective charge density and AC amplitude. The spoke current is obtained as a nonlinear function of the detuning from the synchronous (Buneman-Hartree, BH) voltage Vs; the spoke charge is included in the self-consistent definition of Vs. It is shown that there is a DC voltage region of width ‖V-Vs‖˜V1, where the spoke width is constant and the spoke current is simply proportional to the AC voltage. The magnetron characteristic curves are ``flat'' in that range, and are approximated by a linear expansion around Vs. The derived formulas differ from earlier results [J. F. Hull, in Cross Field Microwave Devices, edited by E. Okress (Academic, New York, 1961), pp. 496-527] in (a) there is no current cutoff at synchronism; the tube operates well below as well above the BH voltage; (b) the characteristics are single valued within the synchronous voltage range; (c) the hub top is not treated as virtual cathode; and (d) the hub density is not equal to the Brillouin density; comparisons with tube measurements show the best agreement for hub density near half the Brillouin density. It is also shown that at low space charge and low power the gain curve is symmetric relative to the voltage (frequency) detuning. While symmetry is broken at high-power/high space charge magnetron operation, the BH voltage remains between the current cutoff voltages.

  5. Lay theories of heroin addiction.

    PubMed

    Furnham, A; Thomson, L

    1996-07-01

    This study examined the structure and determinants of lay people's implicit theories of heroin addiction. A questionnaire was derived from interviews with lay people about their beliefs and theories of heroin addiction and academic literature on the subject. One hundred and forty-four subjects completed the questionnaire, in which they rated 105 statements about the causes, correlates and cures of heroin addiction. The three parts of the questionnaire were individually factor analyzed and a clear, interpretable factor structure emerged for each. The factors seemed similar to explicit academic theories, but the exception was beliefs about cure, which did not show overall support for the most clinically used models. When the three factor analyses were combined into a single 'higher-order' factor analysis four factors emerged, labelled moralistic, psychosocial, sociocultural and drug treatment, which reflect more or less coherent views on the nature of heroin addiction. Subjects' political beliefs was the greatest (demographic and attitudinal) determinant of lay beliefs in these factors, with experience of addiction, addicts, drugs and age also highly correlated. Vote was the main determinant and best predictor of the four 'higher-order' structured lay theories: right-wing voters emphasizing moralistic and individualistic theory and left-wing voters supporting the psychological and societal ideas. Implications for policy and interventions to addicts of these lay theories are considered.

  6. Theory of coherent resonance energy transfer

    SciTech Connect

    Jang, Seogjoo; Cheng, Y.-C.; Reichman, David R.; Eaves, Joel D.

    2008-09-14

    A theory of coherent resonance energy transfer is developed combining the polaron transformation and a time-local quantum master equation formulation, which is valid for arbitrary spectral densities including common modes. The theory contains inhomogeneous terms accounting for nonequilibrium initial preparation effects and elucidates how quantum coherence and nonequilibrium effects manifest themselves in the coherent energy transfer dynamics beyond the weak resonance coupling limit of the Foerster and Dexter (FD) theory. Numerical tests show that quantum coherence can cause significant changes in steady state donor/acceptor populations from those predicted by the FD theory and illustrate delicate cooperation of nonequilibrium and quantum coherence effects on the transient population dynamics.

  7. Analyzing Test-Taking Behavior: Decision Theory Meets Psychometric Theory.

    PubMed

    Budescu, David V; Bo, Yuanchao

    2015-12-01

    We investigate the implications of penalizing incorrect answers to multiple-choice tests, from the perspective of both test-takers and test-makers. To do so, we use a model that combines a well-known item response theory model with prospect theory (Kahneman and Tversky, Prospect theory: An analysis of decision under risk, Econometrica 47:263-91, 1979). Our results reveal that when test-takers are fully informed of the scoring rule, the use of any penalty has detrimental effects for both test-takers (they are always penalized in excess, particularly those who are risk averse and loss averse) and test-makers (the bias of the estimated scores, as well as the variance and skewness of their distribution, increase as a function of the severity of the penalty).

  8. Cue combination on the circle and the sphere.

    PubMed

    Murray, Richard F; Morgenstern, Yaniv

    2010-09-01

    Bayesian cue combination models have been used to examine how human observers combine information from several cues to form estimates of linear quantities like depth. Here we develop an analogous theory for circular quantities like planar direction. The circular theory is broadly similar to the linear theory but differs in significant ways. First, in the circular theory the combined estimate is a nonlinear function of the individual cue estimates. Second, in the circular theory the mean of the combined estimate is affected not only by the means of individual cues and the weights assigned to individual cues but also by the variability of individual cues. Third, in the circular theory the combined estimate can be less certain than the individual estimates, if the individual estimates disagree with one another. Fourth, the circular theory does not have some of the closed-form expressions available in the linear theory, so data analysis requires numerical methods. We describe a vector sum model that gives a heuristic approximation to the circular theory's behavior. We also show how the theory can be extended to deal with spherical quantities like direction in three-dimensional space.

  9. Decidability of formal theories and hyperincursivity theory

    NASA Astrophysics Data System (ADS)

    Grappone, Arturo G.

    2000-05-01

    This paper shows the limits of the Proof Standard Theory (briefly, PST) and gives some ideas of how to build a proof anticipatory theory (briefly, PAT) that has no such limits. Also, this paper considers that Gödel's proof of the undecidability of Principia Mathematica formal theory is not valid for axiomatic theories that use a PAT to build their proofs because the (hyper)incursive functions are self-representable.

  10. Generating Curriculum Theory Through Grounded Theory Research.

    ERIC Educational Resources Information Center

    Gehrke, Nathalie J.; Parker, Walter C.

    The purpose of this paper is threefold: to describe grounded theory research strategies, to present a summary of several studies in education that have followed this approach, and to explore the potential uses of the grounded theory techniques in curriculum theory generation. The paper is arranged into six parts. In the first and second parts of…

  11. Retarded gravitation theory

    NASA Astrophysics Data System (ADS)

    Raju, C. K.

    2012-10-01

    We propose a Lorentz-covariant theory of gravity, and explain its theoretical origins in the problem of time in Newtonian physics. In this retarded gravitation theory (RGT), the gravitational force depends upon both retarded position and velocity, and the equations of motion are time-asymmetric retarded functional differential equations. We explicitly solve these equations, under simplifying assumptions, for various NASA spacecraft. This shows that the differences from Newtonian gravity, though tiny within the solar system, are just appropriate to explain the flyby anomaly as a ν/c effect due to earth's rotation. The differences can, however, be large in the case of a spiral galaxy, and we show that the combined velocity drag from a large number of co-rotating stars enormously speeds up a test particle. Thus, the non-Newtonian behaviour of rotation curves in a spiral galaxy may be explained as being due to velocity drag rather than dark matter. RGT can also be tested in the laboratory. It necessitates a reappraisal of current laboratory methods of determining the Newtonian gravitational constant G. Since RGT makes no speculative assumptions, its refutation would have serious implications across physics.

  12. Toward a theory of constraints.

    PubMed

    Breunlin, D C

    1999-06-01

    Grounded in the cybernetic concept of negative explanation, the theory of constraints examines how human systems are kept from solving problems. To identify constraints, therapists must know where to look for them and what to look for. The theory proposes that constraints exist among the levels of a biopsychosocial system, which include biology, person, relationship, family, community, and society. The six metaframeworks of organization, sequences, mind, development, gender, and culture assist constraint identification. Combining the levels and metaframeworks creates a web of constraints, the complexity of which determines how difficult it will be to solve a given problem. The theory of constraint offers an integrative and pragmatic approach to therapy while simultaneously honoring the complexity of human systems.

  13. Generalized SU(2) Proca theory

    NASA Astrophysics Data System (ADS)

    Allys, Erwan; Peter, Patrick; Rodríguez, Yeinzon

    2016-10-01

    Following previous works on generalized Abelian Proca theory, also called vector Galileon, we investigate the massive extension of an SU(2) gauge theory, i.e., the generalized SU(2) Proca model, which could be dubbed non-Abelian vector Galileon. This particular symmetry group permits fruitful applications in cosmology such as inflation driven by gauge fields. Our approach consists in building, in an exhaustive way, all the Lagrangians containing up to six contracted Lorentz indices. For this purpose, and after identifying by group theoretical considerations all the independent Lagrangians which can be written at these orders, we consider the only linear combinations propagating 3 degrees of freedom and having healthy dynamics for their longitudinal mode, i.e., whose pure Stückelberg contribution turns into the SU(2) multi-Galileon dynamics. Finally, and after having considered the curved space-time expansion of these Lagrangians, we discuss the form of the theory at all subsequent orders.

  14. Eigenvalue Detonation of Combined Effects Aluminized Explosives

    NASA Astrophysics Data System (ADS)

    Capellos, Christos; Baker, Ernest; Balas, Wendy; Nicolich, Steven; Stiel, Leonard

    2007-06-01

    This paper reports on the development of theory and performance for recently developed combined effects aluminized explosives. Traditional high energy explosives used for metal pushing incorporate high loading percentages of HMX or RDX, whereas blast explosives incorporate some percentage of aluminum. However, the high blast explosives produce increased blast energies, with reduced metal pushing capability due to late time aluminum reaction. Metal pushing capability refers to the early volume expansion work produced during the first few volume expansions associated with cylinder wall velocities and Gurney energies. Our Recently developed combined effects aluminized explosives (PAX-29C, PAX-30, PAX-42) are capable of achieving excellent metal pushing and high blast energies. Traditional Chapman-Jouguet detonation theory does not explain the observed detonation states achieved by these combined effects explosives. This work demonstrates, with the use of cylinder expansion data and thermochemical code calculations (JAGUAR and CHEETAH), that eigenvalue detonation theory explains the observed behavior.

  15. Crisis Decision Theory: Decisions in the Face of Negative Events

    ERIC Educational Resources Information Center

    Sweeney, Kate

    2008-01-01

    How do people respond to negative life events? Crisis decision theory combines the strengths of coping theories with research on decision making to predict the responses people choose under negative circumstances. The theory integrates literatures on coping, health behavior, and decision making, among others, into 3 stages that describe the…

  16. Theory of nanorod antenna resonances including end-reflection phase

    NASA Astrophysics Data System (ADS)

    Su, Wei; Li, Xiangyin; Bornemann, Jens; Gordon, Reuven

    2015-04-01

    We present a fully analytic theory for nanorod resonances including the phase of reflection from the rounded ends using a transmission line approach. It combines the circuit theory response of spherical nanoparticles with standard transmission line theory using the Sommerfeld wave dispersion. The approach agrees well with comprehensive numerical calculations.

  17. Crisis Decision Theory: Decisions in the Face of Negative Events

    ERIC Educational Resources Information Center

    Sweeney, Kate

    2008-01-01

    How do people respond to negative life events? Crisis decision theory combines the strengths of coping theories with research on decision making to predict the responses people choose under negative circumstances. The theory integrates literatures on coping, health behavior, and decision making, among others, into 3 stages that describe the…

  18. A Social Extension of a Psychological Interest Theory

    ERIC Educational Resources Information Center

    Bikner-Ahsbahs, Angelika

    2003-01-01

    Based on an individual interest theory as a sensitising theory, empirical data are used to gain social interest concepts, as there are situated collective interest and interest-dense situation. These concepts serve as a basis for a social extension of a psychological interest theory. Its construction combines social interactions, the dynamic of…

  19. Job Satisfaction: A Possible Integration of Two Theories

    ERIC Educational Resources Information Center

    Hazer, John T.

    1976-01-01

    A rationale for deciding which motivation methods to use for employees who have differing levels of satisfaction. Discusses pros and cons of two theories on job satisfaction--Herzberg's theory and the traditional theory--suggesting strongly a need to combine both ideas. (WL)

  20. Grounded theory, feminist theory, critical theory: toward theoretical triangulation.

    PubMed

    Kushner, Kaysi Eastlick; Morrow, Raymond

    2003-01-01

    Nursing and social science scholars have examined the compatibility between feminist and grounded theory traditions in scientific knowledge generation, concluding that they are complementary, yet not without certain tensions. This line of inquiry is extended to propose a critical feminist grounded theory methodology. The construction of symbolic interactionist, feminist, and critical feminist variants of grounded theory methodology is examined in terms of the presuppositions of each tradition and their interplay as a process of theoretical triangulation.

  1. Foundations for a theory of gravitation theories

    NASA Technical Reports Server (NTRS)

    Thorne, K. S.; Lee, D. L.; Lightman, A. P.

    1972-01-01

    A foundation is laid for future analyses of gravitation theories. This foundation is applicable to any theory formulated in terms of geometric objects defined on a 4-dimensional spacetime manifold. The foundation consists of (1) a glossary of fundamental concepts; (2) a theorem that delineates the overlap between Lagrangian-based theories and metric theories; (3) a conjecture (due to Schiff) that the Weak Equivalence Principle implies the Einstein Equivalence Principle; and (4) a plausibility argument supporting this conjecture for the special case of relativistic, Lagrangian-based theories.

  2. Object relations theory and activity theory: a proposed link by way of the procedural sequence model.

    PubMed

    Ryle, A

    1991-12-01

    An account of object relations theory (ORT), represented in terms of the procedural sequence model (PSM), is compared to the ideas of Vygotsky and activity theory (AT). The two models are seen to be compatible and complementary and their combination offers a satisfactory account of human psychology, appropriate for the understanding and integration of psychotherapy.

  3. Utilizing general information theories for uncertainty quantification

    SciTech Connect

    Booker, J. M.

    2002-01-01

    Uncertainties enter into a complex problem from many sources: variability, errors, and lack of knowledge. A fundamental question arises in how to characterize the various kinds of uncertainty and then combine within a problem such as the verification and validation of a structural dynamics computer model, reliability of a dynamic system, or a complex decision problem. Because uncertainties are of different types (e.g., random noise, numerical error, vagueness of classification), it is difficult to quantify all of them within the constructs of a single mathematical theory, such as probability theory. Because different kinds of uncertainty occur within a complex modeling problem, linkages between these mathematical theories are necessary. A brief overview of some of these theories and their constituents under the label of Generalized lnforrnation Theory (GIT) is presented, and a brief decision example illustrates the importance of linking at least two such theories.

  4. Designing Innovative Counseling Courses: Combining Technology, Theory, and Practice

    ERIC Educational Resources Information Center

    Cicco, Gina

    2012-01-01

    This article will discuss the development of an innovative instructional design for teaching graduate courses in counselor education programs. The teaching strategies that will be highlighted evolved during a collaborative team-teaching project conducted by two counselor educators. These two faculty members worked together to redesign a course in…

  5. Cognitive Diagnosis Combined with Latent Trait Theory and Multiphase Responses.

    DTIC Science & Technology

    1994-11-25

    exists, instead of turning to multidimensional latent trait models . Some appropriate model for the dichotomous item, such as the normal ogive model ...process must be repeated by adopting another dichotomous model . After a model has been validated, using the nonparametric approach the operating...2] Masters, G. N. (1982). A Rasch model for partial credit scoring. Psychometrika, 47, 149-174. [3] Muraki, E. (1992). A generalized partial credit

  6. Theory of using magnetic deflections to combine charged particle beams

    SciTech Connect

    Steckbeck, Mackenzie K.; Doyle, Barney Lee

    2014-09-01

    Several radiation effects projects in the Ion Beam Lab (IBL) have recently required two disparate charged particle beams to simultaneously strike a single sample through a single port of the target chamber. Because these beams have vastly different mass–energy products (MEP), the low-MEP beam requires a large angle of deflection toward the sample by a bending electromagnet. A second electromagnet located further upstream provides a means to compensate for the small angle deflection experienced by the high-MEP beam during its path through the bending magnet. This paper derives the equations used to select the magnetic fields required by these two magnets to achieve uniting both beams at the target sample. A simple result was obtained when the separation of the two magnets was equivalent to the distance from the bending magnet to the sample, and the equation is given by: Bs= 1/2(rc/rs) Bc, where Bs and Bc are the magnetic fields in the steering and bending magnet and rc/rs is the ratio of the radii of the bending magnet to that of the steering magnet. This result is not dependent upon the parameters of the high MEP beam, i.e. energy, mass, charge state. Therefore, once the field of the bending magnet is set for the low-MEP beam, and the field in the steering magnet is set as indicted in the equation, the trajectory path of any high-MEP beam will be directed into the sample.

  7. Technology, Teachers, and Training: Combining Theory with Macedonia's Experience

    ERIC Educational Resources Information Center

    Hosman, Laura; Cvetanoska, Maja

    2013-01-01

    Numerous developing countries are currently planning or executing projects that introduce technology into their educational systems. This article asserts that such projects will have limited long-term success or impact until they are reconceptualized to incorporate three transformative concepts: teachers play the key role in determining the…

  8. Some directions in ecological theory.

    PubMed

    Kendall, Bruce E

    2015-12-01

    The role of theory within ecology has changed dramatically in recent decades. Once primarily a source of qualitative conceptual framing, ecological theories and models are now often used to develop quantitative explanations of empirical patterns and to project future dynamics of specific ecological systems. In this essay, I recount my own experience of this transformation, in which accelerating computing power and the widespread incorporation of stochastic processes into ecological theory combined to create some novel integration of mathematical and statistical models. This stronger integration drives theory towards incorporating more biological realism, and I explore ways in which we can grapple with that realism to generate new general theoretical insights. This enhanced realism, in turn, may lead to frameworks for projecting ecological responses to anthropogenic change, which is, arguably, the central challenge for 21st-century ecology. In an era of big data and synthesis, ecologists are increasingly seeking to infer causality from observational data; but conventional biometry provides few tools for this project. This is a realm where theorists can and should play an important role, and I close by pointing towards some analytical and philosophical approaches developed in our sister discipline of economics that address this very problem. While I make no grand prognostications about the likely discoveries of ecological theory over the coming century, you will find in this essay a scattering of more or less far-fetched ideas that I, at least, think are interesting and (possibly) fruitful directions for our field.

  9. Fidelity to Theory in PA Intervention Research.

    PubMed

    Keller, Colleen; Fleury, Julie; Sidani, Souraya; Ainsworth, Barbara

    2009-04-01

    Research using theory-based interventions to promote regular physical activity (PA) has increased substantially over the past decade. The purpose of this article is to provide a review and summary of PA intervention research specific to fidelity to intervention theory, providing an overview of the concept of fidelity to intervention theory, defining the evaluative components of fidelity: (a) conceptualization of the problem, (b) operationalization of the theory, (c) specification of mediating processes, and (d) specification of outcome variables. Using journal scans and computerized literature database searches, the authors identified 470 PA activity intervention studies that incorporated a theoretical perspective. A validity framework explicated by was used to summarize intervention research in light of fidelity to intervention theory. In all, 15 intervention studies met the inclusion criteria and were incorporated into the review. Theoretical models for health behavior change, including social cognitive theory (SCT), cognitive behavioral theory (CBT), the transtheoretical model (TTM, the TTM combined with SCT), the reversal theory (theory of psychological reversals), and the disconnected values theory, were used as a basis for intervention design and evaluation.

  10. Semiclassical gravitation theory: Why transitional scientific theories are theories

    NASA Astrophysics Data System (ADS)

    Mattingly, James Madison

    The foundations of quantum gravity are considered. A challenge is made to the assumption that the gravitational field is quantized. The semiclassical theory of gravity, particularly its relation to classical general relativity, is examined. The status of energy conditions in classical and semiclassical gravity is assessed. It is concluded that, as currently understood, the energy conditions required for proving singularity theorems do not hold. General issues in the philosophy of science are raised, and an analysis of the semantic conception of theories is undertaken. It is shown that the basic philosophical presupposition of that conception---that formulations of theories are irrelevant---is untenable. Examples include the transition from Euclidean to non-Euclidean geometry, the transition from classical to quantum mechanics, and the development of quantum field theory on curved spacetime from quantum field theory in Minkowski space. I argue for three significant and novel theses in the philosophy of science. First I have attempted to show that the semiclassical theory of gravity is significant as a theory and that it thus merits philosophical attention and reflection upon by philosophers of science. This is a point that has been long overlooked in the philosophy of science. Second I have indicated how the insights generated by new sciences can have profound influences on how we understand older sciences. This insight is similar to Stein's (1967) reconceptualization of Newtonian gravitation theory via the technology of dynamical geometry. My discussion illustrates in a concrete way that our understanding of even the factual claims made by an older theory (in this case that general relativistic models of our universe are singular) can be undermined by results in newer theories without challenging that theory itself. Finally I have argued for a new way of thinking about scientific theories that charts a middle course between the syntactic view of theories and the

  11. Contributions of treatment theory and enablement theory to rehabilitation research and practice.

    PubMed

    Whyte, John

    2014-01-01

    Scientific theory is crucial to the advancement of clinical research. The breadth of rehabilitation treatment requires that many different theoretical perspectives be incorporated into the design and testing of treatment interventions. In this article, the 2 broad classes of theory relevant to rehabilitation research and practice are defined, and their distinct but complementary contributions to research and clinical practice are explored. These theory classes are referred to as treatment theories (theories about how to effect change in clinical targets) and enablement theories (theories about how changes in a proximal clinical target will influence distal clinical aims). Treatment theories provide the tools for inducing clinical change but do not specify how far reaching the ultimate impact of the change will be. Enablement theories model the impact of changes on other areas of function but provide no insight as to how treatment can create functional change. Treatment theories are more critical in the early stages of treatment development, whereas enablement theories become increasingly relevant in specifying the clinical significance and practical effectiveness of more mature treatments. Understanding the differences in the questions these theory classes address and how to combine their insights is crucial for effective research development and clinical practice.

  12. Large-Nc gauge theory and chiral random matrix theory

    NASA Astrophysics Data System (ADS)

    Hanada, Masanori; Lee, Jong-Wan; Yamada, Norikazu

    2013-07-01

    We discuss how the 1/Nc expansion and the chiral random matrix theory (χRMT) can be used in the study of large-Nc gauge theories. We first clarify the parameter region in which each of these two approaches is valid. While the fermion mass m is fixed in the standard large-Nc arguments (’t Hooft large-Nc limit), m must be scaled appropriately with a certain negative power of Nc in order for the gauge theories to be described by the χRMT. Then, although these two limits are not compatible in general, we show that the breakdown of chiral symmetry can be detected by combining the large-Nc argument and the χRMT with some care. As a concrete example, we numerically study the four-dimensional SU(Nc) gauge theory with Nf=2 heavy adjoint fermions, introduced as the center symmetry preserver keeping the infrared physics intact, on a 24 lattice. By looking at the low-lying eigenvalues of the overlap-Dirac operator for a massless probe fermion in the adjoint representation, we find that the chiral symmetry is indeed broken with the expected breaking pattern. This result reproduces a well-known fact that the chiral symmetry is spontaneously broken in the pure SU(Nc) gauge theory in the large-Nc and the large-volume limit and therefore supports the validity of the combined approach. We also provide an interpretation of the gap and unexpected Nc scaling, both of which are observed in the Dirac spectrum.

  13. Modern Quantum Field Theory

    NASA Astrophysics Data System (ADS)

    Banks, Tom

    2008-09-01

    1. Introduction; 2. Quantum theory of free scalar fields; 3. Interacting field theory; 4. Particles of spin one, and gauge invariance; 5. Spin 1/2 particles and Fermi statistics; 6. Massive quantum electrodynamics; 7. Symmetries, Ward identities and Nambu Goldstone bosons; 8. Non-abelian gauge theory; 9. Renormalization and effective field theory; 10. Instantons and solitons; 11. Concluding remarks; Appendices; References; Index.

  14. Theories and Modes

    ERIC Educational Resources Information Center

    Apsche, Jack A.

    2005-01-01

    In his work on the Theory of Modes, Beck (1996) suggested that there were flaws with his cognitive theory. He suggested that though there are shortcomings to his cognitive theory, there were not similar shortcomings to the practice of Cognitive Therapy. The author suggests that if there are shortcomings to cognitive theory the same shortcomings…

  15. Nonrelativistic superstring theories

    SciTech Connect

    Kim, Bom Soo

    2007-12-15

    We construct a supersymmetric version of the critical nonrelativistic bosonic string theory [B. S. Kim, Phys. Rev. D 76, 106007 (2007).] with its manifest global symmetry. We introduce the anticommuting bc conformal field theory (CFT) which is the super partner of the {beta}{gamma} CFT. The conformal weights of the b and c fields are both 1/2. The action of the fermionic sector can be transformed into that of the relativistic superstring theory. We explicitly quantize the theory with manifest SO(8) symmetry and find that the spectrum is similar to that of type IIB superstring theory. There is one notable difference: the fermions are nonchiral. We further consider noncritical generalizations of the supersymmetric theory using the superspace formulation. There is an infinite range of possible string theories similar to the supercritical string theories. We comment on the connection between the critical nonrelativistic string theory and the lightlike linear dilaton theory.

  16. Quantum Theory is an Information Theory

    NASA Astrophysics Data System (ADS)

    D'Ariano, Giacomo M.; Perinotti, Paolo

    2016-03-01

    In this paper we review the general framework of operational probabilistic theories (OPT), along with the six axioms from which quantum theory can be derived. We argue that the OPT framework along with a relaxed version of five of the axioms, define a general information theory. We close the paper with considerations about the role of the observer in an OPT, and the interpretation of the von Neumann postulate and the Schrödinger-cat paradox.

  17. Theoretical investigation on single-molecule chiroptical spectroscopy

    SciTech Connect

    Wakabayashi, M.; Yokojima, S.; Fukaminato, T.; Ogata, K.; Nakamura, S.

    2013-12-10

    Some experimental results of chiroptical response of single molecule have already reported. In those experiments, dissymmetry parameter, g was used as an indicator of the relative circular dichroism intensity. The parameter for individual molecules was measured. For the purpose of giving an interpretation or explanation to the experimental result, the dissymmetry parameter is formulated on the basis of Fermi’s golden rule. Subsequently, the value of individual molecules is evaluated as a function of the direction of light propagation to the orientationary fixed molecules. The ground and excited wavefunction of electrons in the molecule and transition moments needed are culculated using the density functional theory.

  18. Teaching Theory X and Theory Y in Organizational Communication

    ERIC Educational Resources Information Center

    Noland, Carey

    2014-01-01

    The purpose of the activity described here is to integrate McGregor's Theory X and Theory Y into a group application: design a syllabus that embodies either Theory X or Theory Y tenets. Students should be able to differentiate between Theory X and Theory Y, create a syllabus based on Theory X or Theory Y tenets, evaluate the different syllabi…

  19. Teaching Theory X and Theory Y in Organizational Communication

    ERIC Educational Resources Information Center

    Noland, Carey

    2014-01-01

    The purpose of the activity described here is to integrate McGregor's Theory X and Theory Y into a group application: design a syllabus that embodies either Theory X or Theory Y tenets. Students should be able to differentiate between Theory X and Theory Y, create a syllabus based on Theory X or Theory Y tenets, evaluate the different syllabi…

  20. Identity theory and personality theory: mutual relevance.

    PubMed

    Stryker, Sheldon

    2007-12-01

    Some personality psychologists have found a structural symbolic interactionist frame and identity theory relevant to their work. This frame and theory, developed in sociology, are first reviewed. Emphasized in the review are a multiple identity conception of self, identities as internalized expectations derived from roles embedded in organized networks of social interaction, and a view of social structures as facilitators in bringing people into networks or constraints in keeping them out, subsequently, attention turns to a discussion of the mutual relevance of structural symbolic interactionism/identity theory and personality theory, looking to extensions of the current literature on these topics.

  1. Generalizability Theory and Classical Test Theory

    ERIC Educational Resources Information Center

    Brennan, Robert L.

    2011-01-01

    Broadly conceived, reliability involves quantifying the consistencies and inconsistencies in observed scores. Generalizability theory, or G theory, is particularly well suited to addressing such matters in that it enables an investigator to quantify and distinguish the sources of inconsistencies in observed scores that arise, or could arise, over…

  2. Separation-individuation theory and attachment theory.

    PubMed

    Blum, Harold P

    2004-01-01

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

  3. Generalizability Theory and Classical Test Theory

    ERIC Educational Resources Information Center

    Brennan, Robert L.

    2011-01-01

    Broadly conceived, reliability involves quantifying the consistencies and inconsistencies in observed scores. Generalizability theory, or G theory, is particularly well suited to addressing such matters in that it enables an investigator to quantify and distinguish the sources of inconsistencies in observed scores that arise, or could arise, over…

  4. Sentence Combining and the Learning Disabled Student.

    ERIC Educational Resources Information Center

    Nutter, Norma; Safran, Stephen P.

    Theory and research indicated that sentence-combining exercises (SCE's) might be effective for improving the writing of learning disabled (LD) pupils. Seven college seniors in special education were trained to implement SCE's naturalistically in tutoring 13 LD pupils in grades 1-6 over a 10 week period, with a control group of 8 seniors tutoring…

  5. Asymptotic Distributions for Tests of Combined Significance.

    ERIC Educational Resources Information Center

    Becker, Betsy Jane

    This paper discusses distribution theory and power computations for four common "tests of combined significance." These tests are calculated using one-sided sample probabilities or p values from independent studies (or hypothesis tests), and provide an overall significance level for the series of results. Noncentral asymptotic sampling…

  6. Comparisons and connections between mean field dynamo theory and accretion disc theory

    NASA Astrophysics Data System (ADS)

    Blackman, E. G.

    2010-01-01

    The origin of large scale magnetic fields in astrophysical rotators, and the conversion of gravitational energy into radiation near stars and compact objects via accretion have been subjects of active research for a half century. Magnetohydrodynamic turbulence makes both problems highly nonlinear, so both subjects have benefitted from numerical simulations.However, understanding the key principles and practical modeling of observations warrants testable semi-analytic mean field theories that distill the essential physics. Mean field dynamo (MFD) theory and alpha-viscosity accretion disc theory exemplify this pursuit. That the latter is a mean field theory is not always made explicit but the combination of turbulence and global symmetry imply such. The more commonly explicit presentation of assumptions in 20th century textbook MFDT has exposed it to arguably more widespread criticism than incurred by 20th century alpha-accretion theory despite complementary weaknesses. In the 21st century however, MFDT has experienced a breakthrough with a dynamical saturation theory that consistently agrees with simulations. Such has not yet occurred in accretion disc theory, though progress is emerging. Ironically however, for accretion engines, MFDT and accretion theory are presently two artificially uncoupled pieces of what should be a single coupled theory. Large scale fields and accretion flows are dynamically intertwined because large scale fields likely play a key role in angular momentum transport. I discuss and synthesize aspects of recent progress in MFDT and accretion disc theory to suggest why the two likely conspire in a unified theory.

  7. On multiscale moving contact line theory

    PubMed Central

    Li, Shaofan; Fan, Houfu

    2015-01-01

    In this paper, a multiscale moving contact line (MMCL) theory is presented and employed to simulate liquid droplet spreading and capillary motion. The proposed MMCL theory combines a coarse-grained adhesive contact model with a fluid interface membrane theory, so that it can couple molecular scale adhesive interaction and surface tension with hydrodynamics of microscale flow. By doing so, the intermolecular force, the van der Waals or double layer force, separates and levitates the liquid droplet from the supporting solid substrate, which avoids the shear stress singularity caused by the no-slip condition in conventional hydrodynamics theory of moving contact line. Thus, the MMCL allows the difference of the surface energies and surface stresses to drive droplet spreading naturally. To validate the proposed MMCL theory, we have employed it to simulate droplet spreading over various elastic substrates. The numerical simulation results obtained by using MMCL are in good agreement with the molecular dynamics results reported in the literature. PMID:26345090

  8. 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.

  9. Property attribution in combined concepts.

    PubMed

    Spalding, Thomas L; Gagné, Christina L

    2015-05-01

    Recent research shows that the judged likelihood of properties of modified nouns (baby ducks have webbed feet) is reduced relative to judgments for unmodified nouns (ducks have webbed feet). This modification effect has been taken as evidence both for and against the idea that combined concepts automatically inherit properties from their constituent concepts. Experiments 1 and 2 replicate this effect and demonstrate a reversed modification effect with false properties. That is, false properties are judged more likely with modification (e.g., purple candles have teeth is judged more likely than candles have teeth). These experiments also show that properties that are neither generically true nor false are unaffected by modification. Experiments 3 and 4 manipulate participants' expectation of contrast by showing modified and unmodified nouns that either match or mismatch in terms of a property and show that the judged likelihood of properties depends on the expectations of contrast set up by the manipulation. These results show that the modification effect is primarily driven by participants' understanding of the relation of subcategories to categories, rather than by the features of the concepts being combined, suggesting that the process of property attribution in combined concepts is strongly affected by pragmatic factors and is less strongly dependent on conceptual content than most theories of conceptual combination would suggest. (c) 2015 APA, all rights reserved).

  10. Recent advances in analytical satellite theory

    NASA Technical Reports Server (NTRS)

    Gaposchkin, E. M.

    1978-01-01

    Recent work on analytical satellite perturbation theory has involved the completion of a revision to 4th order for zonal harmonics, the addition of a treatment for ocean tides, an extension of the treatment for the noninertial reference system, and the completion of a theory for direct solar-radiation pressure and earth-albedo pressure. Combined with a theory for tesseral-harmonics, lunisolar, and body-tide perturbations, these formulations provide a comprehensive orbit-computation program. Detailed comparisons with numerical integration and observations are presented to assess the accuracy of each theoretical development.

  11. Theory and performance of plated thermocouples.

    NASA Technical Reports Server (NTRS)

    Pesko, R. N.; Ash, R. L.; Cupschalk, S. G.; Germain, E. F.

    1972-01-01

    A theory has been developed to describe the performance of thermocouples which have been formed by electroplating portions of one thermoelectric material with another. The electroplated leg of the thermocouple was modeled as a collection of infinitesimally small homogeneous thermocouples connected in series. Experiments were performed using several combinations of Constantan wire sizes and copper plating thicknesses. A transient method was used to develop the thermoelectric calibrations, and the theory was found to be in quite good agreement with the experiments. In addition, data gathered in a Soviet experiment were also found to be in close agreement with the theory.

  12. Disengagement theory revisited.

    PubMed

    Markson, E W

    1975-01-01

    Cumming and Henry erected the basic frame for a socio-cultural theory of normal aging in their 1961 book, Growing Old. The basic postulates of this theory are reviewed, and the overall structure of the theory briefly examined. Critical data necessary either to accept or reject disengagement theory are not yet available, although useful information has been gathered since the theory first appeared. Part of the difficulty in amassing "proof" or "disproof" is inherent in the intricate and complex nature of the aging process itself. This orienting paper introduced a set of contributtions by other commentators on disengagement theory.

  13. Dynamic density functional theory versus kinetic theory of simple fluids.

    PubMed

    Marini Bettolo Marconi, Umberto; Melchionna, Simone

    2010-09-15

    By combining methods of kinetic and density functional theory, we present a description of molecular fluids which accounts for their microscopic structure and thermodynamic properties as well as their hydrodynamic behavior. We focus on the evolution of the one-particle phase space distribution, rather than on the evolution of the average particle density which features in dynamic density functional theory. The resulting equation can be studied in two different physical limits: diffusive dynamics, typical of colloidal fluids without hydrodynamic interaction where particles are subject to overdamped motion resulting from coupling with a solvent at rest, and inertial dynamics, typical of molecular fluids. Finally, we propose an algorithm to solve numerically and efficiently the resulting kinetic equation by employing a discretization procedure analogous to the one used in the lattice Boltzmann method.

  14. Reduced density-matrix functionals from many-particle theory

    NASA Astrophysics Data System (ADS)

    Schade, Robert; Kamil, Ebad; Blöchl, Peter

    2017-07-01

    In materials with strong electron correlation the proper treatment of local atomic physics described by orbital occupations is crucial. Reduced density-matrix functional theory is a natural extension of density functional theory for systems that are dominated by orbital physics. We review the current state of reduced density-matrix functional theory (RDMFT). For atomic structure relaxations or ab-initio molecular dynamics the combination of density functional theory (DFT) and dynamical mean-field theory (DMFT) possesses a number of disadvantages, like the cumbersome evaluation of forces. We therefore describe a method, DFT+RDMFT, that combines many-particle effects based on reduced density-matrix functional theory with a density functional-like framework. A recent development is the construction of density-matrix functionals directly from many-particle theory such as methods from quantum chemistry or many-particle Green's functions. We present the underlying exact theorems and describe current progress towards quantitative functionals.

  15. Physical causality and brain theories.

    PubMed

    Yates, F E

    1980-05-01

    The history of deterministic theories in physics is reviewed, and four levels of determinism are found: 1) absolute, 2) asymptotic, 3) probabilistic, and 4) absolute indeterminism. Nagel's view that all causal laws are deterministic in the frame of the state descriptions to which they refer is acknowledged, but the inevitability of macroscopic measurement noise may hint that dynamical laws are innately noisy. Quantum mechanical effects are not the noise source. Symmetry and broken symmetry are introduced as physical concepts that can account both for lawfulness, and for the hierarchical nature of the universe. Physical ideas are chosen over those of formal systems with indirect self-reference as the basis of a global theory of brains. By exclusion it is concluded that only a statistical thermodynamics, combined with nonlinear mechanics, has the features needed for theorizing about brains in a physical sense. Quantum mechanics is judged not to be relevant. New statistical thermodynamic theories are briefly described, and their strengths and weaknesses noted. The question, "Why should neuroscience look to physics for its theories?" is raised and answered. Some concrete objectives for a program of theoretical research are stated.

  16. Theory of Characteristics

    NASA Technical Reports Server (NTRS)

    Tollmien, W.

    1949-01-01

    The theory of characteristics will be presented generally for quasilinear differential equations of the second order in two variables. This is necessary because of the manifold requirements to be demanded from the theory of characteristics.

  17. Elementary particle theory

    SciTech Connect

    Marciano, W.J.

    1984-12-01

    The present state of the art in elementary particle theory is reviewed. Topics include quantum electrodynamics, weak interactions, electroweak unification, quantum chromodynamics, and grand unified theories. 113 references. (WHK)

  18. Dissipative Field Theory

    SciTech Connect

    Kheirandish, F.; Amooshahi, M.

    2008-11-18

    Quantum field theory of a damped vibrating string as the simplest dissipative scalar field theory is investigated by introducing a minimal coupling method. The rate of energy flowing between the system and its environment is obtained.

  19. Stabilizing bottomless action theories

    NASA Astrophysics Data System (ADS)

    Greensite, J.; Halpern, M. B.

    1984-08-01

    We show how to construct the euclidean quantum theory corresponding to classical actions which are unbounded from below. Our method preserves the classical limit, the large- N limit, and the perturbative expansion of the unstabilized theories.

  20. Covariant Noncommutative Field Theory

    SciTech Connect

    Estrada-Jimenez, S.; Garcia-Compean, H.; Obregon, O.; Ramirez, C.

    2008-07-02

    The covariant approach to noncommutative field and gauge theories is revisited. In the process the formalism is applied to field theories invariant under diffeomorphisms. Local differentiable forms are defined in this context. The lagrangian and hamiltonian formalism is consistently introduced.

  1. Theory of cascade refrigeration

    NASA Astrophysics Data System (ADS)

    Quack, Hans H.

    2012-06-01

    The maximum difference between the warm and cold temperature of a refrigeration cycle is limited by properties of the refrigerant and/or losses associated with the transport of the refrigerant. For larger temperature differences, one has to arrange several refrigeration cycles "above" each other, each cycle spanning a certain temperature difference. This approach is called cascade refrigeration and has played an important role in the history of cryogenics. For a theory of cascade refrigeration it is helpful to define a general one-stage non-reversible refrigeration step and to visualize it within the temperature-entropy diagram. Then one can combine several one-stage cycles to a cascade. There exist two types of cascades: "Full" cascades, where all entropy gains of a lower stage are transferred to the next higher temperature stage, and "partial" cascades, where each single cycle goes up to ambient temperature, where a part of the entropy gain is removed, and only the rest of the entropy gain is transferred to the next higher temperature stage. In cryogenic refrigeration "partial" cascades are generally more efficient than "full" cascades.

  2. [Chronotherapy and relativity theory].

    PubMed

    Polishchuk, N A

    2008-01-01

    The course of time itself in alive organisms is treated from positions of the special theory of the relativity created by A. Einstein in 1905 and added by the Nobel winners H.A.Lorentsem, M. Plankom, M. fon Laue. These achievements of fundamental physics have been put in a basis of special medical technology "Resonant chronophytotherapy" (SMT RCPT) which is applied in practice of treatment of chronic diseases for 27 years. Grass tinctures in various dosages are used in SMT RCPT, which patients take once a day during precisely designated time. Parameters "dosage-time" daily vary. SMT RCPT have been conducted in treatment of epilepsy bronchial asthma, rheumatism, sclerodermia, hypertension, chronic glomerulonephritis, vegeto-vascular dystonia, female sterility, circular alopecia, vitiligo, eczema, psoriasis, onychomycosis. SMT RCPT does have adverse events, has no contra-indications to its use, directed, first of all, on elimination of nonspecific signs of a disease, reduces dependence and complications of the use of chemical synthetic preparations. SMT RCPT can be combined with any kind of specific treatment. Internet-variant of SMT RCPT has been developed. Chronomedicine is priority tendency in industrialized countries of the world--the USA, the Great Britain, Germany, France, Russia, China, Japan and appears on lead positions among alternative methods of treatment, both traditional, and non-traditional.

  3. Computational quantum field theory

    NASA Astrophysics Data System (ADS)

    Grobe, Rainer

    2006-05-01

    I will give an overview on recent attempts to solve the time-dependent Dirac equation for the electron-positron field operator. These numerical solutions permit a first temporally and spatially resolved insight into the mechanisms of how an electron-positron pair can be created from vacuum in a very strong force field. This approach has helped to illuminate a wide range of controversial questions. Some of these questions arise for complicated physical situations such as how an electron scatters off a supercritical potential barrier (Klein paradox). This requires the application of quantum field theory to study the combined effect of the pair-production due to the supercriticality of the potential together with the scattering at the barrier involving the Pauli-principle. Other phenomena include Schr"odinger's Zitterbewegung and the localization problem for a relativistic particle. This work has been supported by the NSF and Research Corporation. P. Krekora, K. Cooley, Q. Su and R. Grobe, Phys. Rev. Lett. 95, 070403 (2005). P. Krekora, Q. Su and R. Grobe, Phys. Rev. Lett. 93, 043004 (2004). P. Krekora, Q. Su and R. Grobe, Phys. Rev. Lett. 92, 040406 (2004).

  4. Issues in Optical Diffraction Theory

    PubMed Central

    Mielenz, Klaus D.

    2009-01-01

    This paper focuses on unresolved or poorly documented issues pertaining to Fresnel’s scalar diffraction theory and its modifications. In Sec. 2 it is pointed out that all thermal sources used in practice are finite in size and errors can result from insufficient coherence of the optical field. A quarter-wave criterion is applied to show how such errors can be avoided by placing the source at a large distance from the aperture plane, and it is found that in many cases it may be necessary to use collimated light as on the source side of a Fraunhofer experiment. If these precautions are not taken the theory of partial coherence may have to be used for the computations. In Sec. 3 it is recalled that for near-zone computations the Kirchhoff or Rayleigh-Sommerfeld integrals are applicable, but fail to correctly describe the energy flux across the aperture plane because they are not continuously differentiable with respect to the assumed geometrical field on the source side. This is remedied by formulating an improved theory in which the field on either side of a semi-reflecting screen is expressed as the superposition of mutually incoherent components which propagate in the opposite directions of the incident and reflected light. These components are defined as linear combinations of the Rayleigh-Sommerfeld integrals, so that they are rigorous solutions of the wave equation as well as continuously differentiable in the aperture plane. Algorithms for using the new theory for computing the diffraction patterns of circular apertures and slits at arbitrary distances z from either side of the aperture (down to z = ± 0.0003 λ) are presented, and numerical examples of the results are given. These results show that the incident geometrical field is modulated by diffraction before it reaches the aperture plane while the reflected field is spilled into the dark space. At distances from the aperture which are large compared to the wavelength λ these field expressions are

  5. Issues in Optical Diffraction Theory.

    PubMed

    Mielenz, Klaus D

    2009-01-01

    This paper focuses on unresolved or poorly documented issues pertaining to Fresnel's scalar diffraction theory and its modifications. In Sec. 2 it is pointed out that all thermal sources used in practice are finite in size and errors can result from insufficient coherence of the optical field. A quarter-wave criterion is applied to show how such errors can be avoided by placing the source at a large distance from the aperture plane, and it is found that in many cases it may be necessary to use collimated light as on the source side of a Fraunhofer experiment. If these precautions are not taken the theory of partial coherence may have to be used for the computations. In Sec. 3 it is recalled that for near-zone computations the Kirchhoff or Rayleigh-Sommerfeld integrals are applicable, but fail to correctly describe the energy flux across the aperture plane because they are not continuously differentiable with respect to the assumed geometrical field on the source side. This is remedied by formulating an improved theory in which the field on either side of a semi-reflecting screen is expressed as the superposition of mutually incoherent components which propagate in the opposite directions of the incident and reflected light. These components are defined as linear combinations of the Rayleigh-Sommerfeld integrals, so that they are rigorous solutions of the wave equation as well as continuously differentiable in the aperture plane. Algorithms for using the new theory for computing the diffraction patterns of circular apertures and slits at arbitrary distances z from either side of the aperture (down to z = ± 0.0003 λ) are presented, and numerical examples of the results are given. These results show that the incident geometrical field is modulated by diffraction before it reaches the aperture plane while the reflected field is spilled into the dark space. At distances from the aperture which are large compared to the wavelength λ these field expressions are reduced

  6. Habit Formation and Story Telling: A Theory for Guiding Ethical Action.

    ERIC Educational Resources Information Center

    Sullivan, Dale L.; Martin, Michael S.

    2001-01-01

    Proposes retrospective narrative justifications combined with classical concepts of habit formation as a theory of ethics appropriate for practicing technical communicators. Draws on Alasdair MacIntyre's ethical theory, which involves habit formation and narrative theory; on apologia and account-giving theory; and on traditional ethical stances,…

  7. Activity Theory and Ontology

    ERIC Educational Resources Information Center

    Peim, Nick

    2009-01-01

    This paper seeks to re-examine Yrio Engestrom's activity theory as a technology of knowledge designed to enable positive transformations of specific practices. The paper focuses on a key paper where Engestrom defines the nature and present state of activity theory. Beginning with a brief account of the relations between activity theory and…

  8. Whither Social Theory?

    ERIC Educational Resources Information Center

    Pais, Alexandre; Valero, Paola

    2014-01-01

    What is the place of social theory in mathematics education research, and what is it for? This special issue of "Educational Studies in Mathematics" offers insights on what could be the role of some sociological theories in a field that has historically privileged learning theories coming from psychology and mathematics as the main…

  9. Quantum Electrodynamics: Theory

    SciTech Connect

    Lincoln, Don

    2016-03-30

    The Standard Model of particle physics is composed of several theories that are added together. The most precise component theory is the theory of quantum electrodynamics or QED. In this video, Fermilab’s Dr. Don Lincoln explains how theoretical QED calculations can be done. This video links to other videos, giving the viewer a deep understanding of the process.

  10. Measurement Decision Theory.

    ERIC Educational Resources Information Center

    Rudner, Lawrence M.

    This paper describes and evaluates the use of decision theory as a tool for classifying examinees based on their item response patterns. Decision theory, developed by A. Wald (1947) and now widely used in engineering, agriculture, and computing, provides a simple model for the analysis of categorical data. Measurement decision theory requires only…

  11. Reflections on Activity Theory

    ERIC Educational Resources Information Center

    Bakhurst, David

    2009-01-01

    It is sometimes suggested that activity theory represents the most important legacy of Soviet philosophy and psychology. But what exactly "is" activity theory? The canonical account in the West is given by Engestrom, who identifies three stages in the theory's development: from Vygotsky's insights, through Leontiev's articulation of the…

  12. Quantum Electrodynamics: Theory

    ScienceCinema

    Lincoln, Don

    2016-07-12

    The Standard Model of particle physics is composed of several theories that are added together. The most precise component theory is the theory of quantum electrodynamics or QED. In this video, Fermilab’s Dr. Don Lincoln explains how theoretical QED calculations can be done. This video links to other videos, giving the viewer a deep understanding of the process.

  13. Reflections on Activity Theory

    ERIC Educational Resources Information Center

    Bakhurst, David

    2009-01-01

    It is sometimes suggested that activity theory represents the most important legacy of Soviet philosophy and psychology. But what exactly "is" activity theory? The canonical account in the West is given by Engestrom, who identifies three stages in the theory's development: from Vygotsky's insights, through Leontiev's articulation of the…

  14. Constructor theory of probability.

    PubMed

    Marletto, Chiara

    2016-08-01

    Unitary quantum theory, having no Born Rule, is non-probabilistic. Hence the notorious problem of reconciling it with the unpredictability and appearance of stochasticity in quantum measurements. Generalizing and improving upon the so-called 'decision-theoretic approach', I shall recast that problem in the recently proposed constructor theory of information-where quantum theory is represented as one of a class of superinformation theories, which are local, non-probabilistic theories conforming to certain constructor-theoretic conditions. I prove that the unpredictability of measurement outcomes (to which constructor theory gives an exact meaning) necessarily arises in superinformation theories. Then I explain how the appearance of stochasticity in (finitely many) repeated measurements can arise under superinformation theories. And I establish sufficient conditions for a superinformation theory to inform decisions (made under it) as if it were probabilistic, via a Deutsch-Wallace-type argument-thus defining a class of decision-supporting superinformation theories. This broadens the domain of applicability of that argument to cover constructor-theory compliant theories. In addition, in this version some of the argument's assumptions, previously construed as merely decision-theoretic, follow from physical properties expressed by constructor-theoretic principles.

  15. Modern Theories of Language.

    ERIC Educational Resources Information Center

    Davis, Philip W.

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

  16. Cognitive Theories of Autism

    ERIC Educational Resources Information Center

    Rajendran, Gnanathusharan; Mitchell, Peter

    2007-01-01

    This article considers three theories of autism: The Theory of Mind Deficit, Executive Dysfunction and the Weak Central Coherence accounts. It outlines each along with studies relevant to their emergence, their expansion, their limitations and their possible integration. Furthermore, consideration is given to any implication from the theories in…

  17. Activity Theory and Ontology

    ERIC Educational Resources Information Center

    Peim, Nick

    2009-01-01

    This paper seeks to re-examine Yrio Engestrom's activity theory as a technology of knowledge designed to enable positive transformations of specific practices. The paper focuses on a key paper where Engestrom defines the nature and present state of activity theory. Beginning with a brief account of the relations between activity theory and…

  18. Generalized theory of gravitation

    SciTech Connect

    Moffat, J.W.

    1984-12-01

    The mathematical formulation of the nonsymmetric gravitation theory (NGT) as a geometrical structure is developed in a higher-dimensional space. The reduction of the geometrical scheme to a dynamical theory of gravitation in four-dimensional space-time is investigated and the basic physical laws of the theory are reviewed in detail.

  19. Frankl's Theory and Therapy.

    ERIC Educational Resources Information Center

    Missinne, Leo E.; Wilcox, Victoria

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

  20. Constructor theory of probability

    PubMed Central

    2016-01-01

    Unitary quantum theory, having no Born Rule, is non-probabilistic. Hence the notorious problem of reconciling it with the unpredictability and appearance of stochasticity in quantum measurements. Generalizing and improving upon the so-called ‘decision-theoretic approach’, I shall recast that problem in the recently proposed constructor theory of information—where quantum theory is represented as one of a class of superinformation theories, which are local, non-probabilistic theories conforming to certain constructor-theoretic conditions. I prove that the unpredictability of measurement outcomes (to which constructor theory gives an exact meaning) necessarily arises in superinformation theories. Then I explain how the appearance of stochasticity in (finitely many) repeated measurements can arise under superinformation theories. And I establish sufficient conditions for a superinformation theory to inform decisions (made under it) as if it were probabilistic, via a Deutsch–Wallace-type argument—thus defining a class of decision-supporting superinformation theories. This broadens the domain of applicability of that argument to cover constructor-theory compliant theories. In addition, in this version some of the argument's assumptions, previously construed as merely decision-theoretic, follow from physical properties expressed by constructor-theoretic principles. PMID:27616914

  1. Combining Approaches for the Analysis of Collaborative Mathematics Learning

    ERIC Educational Resources Information Center

    Tatsis, Konstantinos; Dekker, Rijkje

    2010-01-01

    An episode of two students working collaboratively on a mathematical problem is analysed combining two approaches, namely the process model for mathematical level raising and role theory. The process model stresses the importance of key and regulating activities, while role theory deals with the inter- and intrapersonal concerns of the…

  2. Combining Approaches for the Analysis of Collaborative Mathematics Learning

    ERIC Educational Resources Information Center

    Tatsis, Konstantinos; Dekker, Rijkje

    2010-01-01

    An episode of two students working collaboratively on a mathematical problem is analysed combining two approaches, namely the process model for mathematical level raising and role theory. The process model stresses the importance of key and regulating activities, while role theory deals with the inter- and intrapersonal concerns of the…

  3. World sheet commuting {beta}{gamma} conformal field theory and nonrelativistic string theories

    SciTech Connect

    Kim, Bom Soo

    2007-11-15

    We construct a sigma model in two dimensions with Galilean symmetry in flat target space similar to the sigma model of the critical string theory with Lorentz symmetry in 10 flat spacetime dimensions. This is motivated by the works of Gomis and Ooguri [J. Math. Phys. (N.Y.) 42, 3127 (2001)] and Danielsson et al. [J. High Energy Phys. 10 (2000) 020; J. High Energy Phys. 03 (2001) 041.]. Our theory is much simpler than their theory and does not assume a compact coordinate. This nonrelativistic string theory has a bosonic matter {beta}{gamma} conformal field theory with the conformal weight of {beta} as 1. It is natural to identify time as a linear combination of {gamma} and {gamma} through an explicit realization of the Galilean boost symmetry. The angle between {gamma} and {gamma} parametrizes one parameter family of selection sectors. These selection sectors are responsible for having a nonrelativistic dispersion relation without a nontrivial topology in the nonrelativistic setup, which is one of the major differences from the previous works of Gomis and Ooguri and of Danielsson and co-workers. This simple theory is the nonrelativistic analogue of the critical string theory, and there are many different avenues ahead to be investigated. We mention a possible consistent generalization of this theory with different conformal weights for the {beta}{gamma} conformal field theory. We also mention supersymmetric generalizations of these theories.

  4. La theorie autrement (Theory in Another Light).

    ERIC Educational Resources Information Center

    Bertocchini, Paola; Costanzo, Edwige

    1985-01-01

    Outlines a technique using articles from "Le Francais dans le Monde" to teach reading comprehension and theory simultaneously to teachers of French as a second language. Describes a program in Italy using this approach. (MSE)

  5. Combine User's Manual

    NASA Astrophysics Data System (ADS)

    Reegen, P.

    2011-12-01

    Combine is an add-on to SigSpec and Cinderella. A SigSpec result file or a file generated by Cinderella contains the significant sinusoidal signal components in a time series. In this file, Combine checks one frequency after the other for being a linear combination of previously examined frequencies. If this attempt fails, the corresponding frequency is considered "genuine". Only genuine frequencies are used to form linear combinations subsequently. A purely heuristic model is employed to assign a reliability to each linear combination and to justify whether to consider a frequency genuine or a linear combination.

  6. A guide to knowledge translation theory.

    PubMed

    Estabrooks, Carole A; Thompson, David S; Lovely, J Jacque E; Hofmeyer, Anne

    2006-01-01

    Despite calls over several decades for theory development, there remains no overarching knowledge-translation theory. However, a range of models and theoretical perspectives focused on narrower and related areas have been available for some time. We provide an overview of selected perspectives that we believe are particularly useful for developing testable and useful knowledge-translation interventions. In addition, we discuss adjuvant theories necessary to complement these perspectives. We draw from organizational innovation, health, and social sciences literature to illustrate the similarities and differences of various theoretical perspectives related to the knowledge-translation field.A variety of theoretical perspectives useful to knowledge translation exist. They are often spread across disciplinary boundaries, making them difficult to locate and use. Poor definitional clarity, discipline-specific terminology, and implicit assumptions often hinder the use of complementary perspectives. Health care environments are complex, and assessing the setting prior to selecting a theory should be the first step in knowledge-translation initiatives. Finding a fit between setting (context) and theory is important for knowledge-translation initiatives to succeed. Because one theory will not fit all contexts, it is helpful to understand and use several different theories. Although there are often barriers associated with combining theories from different disciplines, such obstacles can be overcome, and to do so will increase the likelihood that knowledge-translation initiatives will succeed.

  7. Structural Characterization of CO-Inhibited Mo-Nitrogenase by Combined Application of Nuclear Resonance Vibrational Spectroscopy, Extended X-ray Absorption Fine Structure, and Density Functional Theory: New Insights into the Effects of CO Binding and the Role of the Interstitial Atom

    DOE PAGES

    Scott, Aubrey D.; Pelmenschikov, Vladimir; Guo, Yisong; ...

    2014-10-02

    The properties of CO-inhibited Azotobacter vinelandii (Av) Mo-nitrogenase (N2ase) have been examined by the combined application of nuclear resonance vibrational spectroscopy (NRVS), extended X-ray absorption fine structure (EXAFS), and density functional theory (DFT). Dramatic changes in the NRVS are seen under high-CO conditions, especially in a 188 cm–1 mode associated with symmetric breathing of the central cage of the FeMo-cofactor. Similar changes are reproduced with the α-H195Q N2ase variant. In the frequency region above 450 cm–1, additional features are seen that are assigned to Fe-CO bending and stretching modes (confirmed by 13CO isotope shifts). The EXAFS for wild-type N2ase showsmore » evidence for a significant cluster distortion under high-CO conditions, most dramatically in the splitting of the interaction between Mo and the shell of Fe atoms originally at 5.08 Å in the resting enzyme. A DFT model with both a terminal ₋CO and a partially reduced ₋CHO ligand bound to adjacent Fe sites is consistent with both earlier FT-IR experiments, and the present EXAFS and NRVS observations for the wild-type enzyme. Another DFT model with two terminal CO ligands on the adjacent Fe atoms yields Fe-CO bands consistent with the α-H195Q variant NRVS. The calculations also shed light on the vibrational “shake” modes of the interstitial atom inside the central cage, and their interaction with the Fe-CO modes. We discuss implications for the CO and N2 reactivity of N2ase.« less

  8. Structural characterization of CO-inhibited Mo-nitrogenase by combined application of nuclear resonance vibrational spectroscopy, extended X-ray absorption fine structure, and density functional theory: new insights into the effects of CO binding and the role of the interstitial atom.

    PubMed

    Scott, Aubrey D; Pelmenschikov, Vladimir; Guo, Yisong; Yan, Lifen; Wang, Hongxin; George, Simon J; Dapper, Christie H; Newton, William E; Yoda, Yoshitaka; Tanaka, Yoshihito; Cramer, Stephen P

    2014-11-12

    The properties of CO-inhibited Azotobacter vinelandii (Av) Mo-nitrogenase (N2ase) have been examined by the combined application of nuclear resonance vibrational spectroscopy (NRVS), extended X-ray absorption fine structure (EXAFS), and density functional theory (DFT). Dramatic changes in the NRVS are seen under high-CO conditions, especially in a 188 cm(-1) mode associated with symmetric breathing of the central cage of the FeMo-cofactor. Similar changes are reproduced with the α-H195Q N2ase variant. In the frequency region above 450 cm(-1), additional features are seen that are assigned to Fe-CO bending and stretching modes (confirmed by (13)CO isotope shifts). The EXAFS for wild-type N2ase shows evidence for a significant cluster distortion under high-CO conditions, most dramatically in the splitting of the interaction between Mo and the shell of Fe atoms originally at 5.08 Å in the resting enzyme. A DFT model with both a terminal -CO and a partially reduced -CHO ligand bound to adjacent Fe sites is consistent with both earlier FT-IR experiments, and the present EXAFS and NRVS observations for the wild-type enzyme. Another DFT model with two terminal CO ligands on the adjacent Fe atoms yields Fe-CO bands consistent with the α-H195Q variant NRVS. The calculations also shed light on the vibrational "shake" modes of the interstitial atom inside the central cage, and their interaction with the Fe-CO modes. Implications for the CO and N2 reactivity of N2ase are discussed.

  9. Family systems theory, attachment theory, and culture.

    PubMed

    Rothbaum, Fred; Rosen, Karen; Ujiie, Tatsuo; Uchida, Nobuko

    2002-01-01

    Family systems theory and attachment theory have important similarities and complementarities. Here we consider two areas in which the theories converge: (a) in family system theorists' description of an overly close, or "enmeshed," mother-child dyad, which attachment theorists conceptualize as the interaction of children's ambivalent attachment and mothers' preoccupied attachment; (b) in family system theorists' description of the "pursuer-distance cycle" of marital conflict, which attachment theorists conceptualize as the interaction of preoccupied and dismissive partners. We briefly review family systems theory evidence, and more extensively review attachment theory evidence, pertaining to these points of convergence. We also review cross-cultural research, which leads us to conclude that the dynamics described in both theories reflect, in part, Western ways of thinking and Western patterns of relatedness. Evidence from Japan suggests that extremely close ties between mother and child are perceived as adaptive, and are more common, and that children experience less adverse effects from such relationships than do children in the West. Moreover, in Japan there is less emphasis on the importance of the exclusive spousal relationship, and less need for the mother and father to find time alone to rekindle romantic, intimate feelings and to resolve conflicts by openly communicating their differences. Thus, the "maladaptive" pattern frequently cited by Western theorists of an extremely close mother-child relationship, an unromantic, conflictual marriage characterized by little verbal communication and a peripheral, distant father, may function very differently in other cultures. While we believe that both theories will be greatly enriched by their integration, we caution against the application of either theory outside the cultures in which they were developed.

  10. Theories of autism.

    PubMed

    Levy, Florence

    2007-11-01

    The purpose of the present paper was to review psychological theories of autism, and to integrate these theories with neurobiological findings. Cognitive, theory of mind, language and coherence theories were identified, and briefly reviewed. Psychological theories were found not to account for the rigid/repetitive behaviours universally described in autistic subjects, and underlying neurobiological systems were identified. When the developing brain encounters constrained connectivity, it evolves an abnormal organization, the features of which may be best explained by a developmental failure of neural connectivity, where high local connectivity develops in tandem with low long-range connectivity, resulting in constricted repetitive behaviours.

  11. Variational Transition State Theory

    SciTech Connect

    Truhlar, Donald G.

    2016-09-29

    This is the final report on a project involving the development and applications of variational transition state theory. This project involved the development of variational transition state theory for gas-phase reactions, including optimized multidimensional tunneling contributions and the application of this theory to gas-phase reactions with a special emphasis on developing reaction rate theory in directions that are important for applications to combustion. The development of variational transition state theory with optimized multidimensional tunneling as a useful computational tool for combustion kinetics involved eight objectives.

  12. Atomistic k ṡ p theory

    NASA Astrophysics Data System (ADS)

    Pryor, Craig E.; Pistol, M.-E.

    2015-12-01

    Pseudopotentials, tight-binding models, and k ṡ p theory have stood for many years as the standard techniques for computing electronic states in crystalline solids. Here, we present the first new method in decades, which we call atomistic k ṡ p theory. In its usual formulation, k ṡ p theory has the advantage of depending on parameters that are directly related to experimentally measured quantities, however, it is insensitive to the locations of individual atoms. We construct an atomistic k ṡ p theory by defining envelope functions on a grid matching the crystal lattice. The model parameters are matrix elements which are obtained from experimental results or ab initio wave functions in a simple way. This is in contrast to the other atomistic approaches in which parameters are fit to reproduce a desired dispersion and are not expressible in terms of fundamental quantities. This fitting is often very difficult. We illustrate our method by constructing a four-band atomistic model for a diamond/zincblende crystal and show that it is equivalent to the sp3 tight-binding model. We can thus directly derive the parameters in the sp3 tight-binding model from experimental data. We then take the atomistic limit of the widely used eight-band Kane model and compute the band structures for all III-V semiconductors not containing nitrogen or boron using parameters fit to experimental data. Our new approach extends k ṡ p theory to problems in which atomistic precision is required, such as impurities, alloys, polytypes, and interfaces. It also provides a new approach to multiscale modeling by allowing continuum and atomistic k ṡ p models to be combined in the same system.

  13. Theory Interpretations in PVS

    NASA Technical Reports Server (NTRS)

    Owre, Sam; Shankar, Natarajan; Butler, Ricky W. (Technical Monitor)

    2001-01-01

    The purpose of this task was to provide a mechanism for theory interpretations in a prototype verification system (PVS) so that it is possible to demonstrate the consistency of a theory by exhibiting an interpretation that validates the axioms. The mechanization makes it possible to show that one collection of theories is correctly interpreted by another collection of theories under a user-specified interpretation for the uninterpreted types and constants. A theory instance is generated and imported, while the axiom instances are generated as proof obligations to ensure that the interpretation is valid. Interpretations can be used to show that an implementation is a correct refinement of a specification, that an axiomatically defined specification is consistent, or that a axiomatically defined specification captures its intended models. In addition, the theory parameter mechanism has been extended with a notion of theory as parameter so that a theory instance can be given as an actual parameter to an imported theory. Theory interpretations can thus be used to refine an abstract specification or to demonstrate the consistency of an axiomatic theory. In this report we describe the mechanism in detail. This extension is a part of PVS version 3.0, which will be publicly released in mid-2001.

  14. [Introduction to grounded theory].

    PubMed

    Wang, Shou-Yu; Windsor, Carol; Yates, Patsy

    2012-02-01

    Grounded theory, first developed by Glaser and Strauss in the 1960s, was introduced into nursing education as a distinct research methodology in the 1970s. The theory is grounded in a critique of the dominant contemporary approach to social inquiry, which imposed "enduring" theoretical propositions onto study data. Rather than starting from a set theoretical framework, grounded theory relies on researchers distinguishing meaningful constructs from generated data and then identifying an appropriate theory. Grounded theory is thus particularly useful in investigating complex issues and behaviours not previously addressed and concepts and relationships in particular populations or places that are still undeveloped or weakly connected. Grounded theory data analysis processes include open, axial and selective coding levels. The purpose of this article was to explore the grounded theory research process and provide an initial understanding of this methodology.

  15. Birth control pills - combination

    MedlinePlus

    ... this page: //medlineplus.gov/ency/patientinstructions/000655.htm Birth control pills - combination To use the sharing features on ... contain both progestin and estrogen. What Are Combination Birth Control Pills? Birth control pills help keep you from ...

  16. Avionics. Progress Record and Theory Outline.

    ERIC Educational Resources Information Center

    Connecticut State Dept. of Education, Hartford. Div. of Vocational-Technical Schools.

    This combination progress record and course outline is designed for use by individuals teaching a course in avionics that is intended to prepare students for employment in the field of aerospace electronics. Included among the topics addressed in the course are the following: shop practices, aircraft and the theory of flight, electron physics,…

  17. Numerical techniques for lattice gauge theories

    SciTech Connect

    Creutz, M.

    1981-02-06

    The motivation for formulating gauge theories on a lattice is reviewed. Monte Carlo simulation techniques are then discussed for these systems. Finally, the Monte Carlo methods are combined with renormalization group analysis to give strong numerical evidence for confinement of quarks by non-Abelian gauge fields.

  18. Literary Theory in the English Classroom.

    ERIC Educational Resources Information Center

    Fitch, Raymond E., Ed.

    1981-01-01

    Focusing on the notion that the author supplies the words in a text while the reader supplies the meaning, this issue contains essays that combine literary theories with classroom practices. Following an introduction by R. E. Fitch, articles include "Teaching a Western: Jack Schaefer's 'Shane'" (J. R. Ruff); "Pragmatic Criticism in…

  19. Literary Theory in the English Classroom.

    ERIC Educational Resources Information Center

    Fitch, Raymond E., Ed.

    1981-01-01

    Focusing on the notion that the author supplies the words in a text while the reader supplies the meaning, this issue contains essays that combine literary theories with classroom practices. Following an introduction by R. E. Fitch, articles include "Teaching a Western: Jack Schaefer's 'Shane'" (J. R. Ruff); "Pragmatic Criticism in…

  20. A Grand Unified Theory of Interdisciplinarity

    ERIC Educational Resources Information Center

    Davis, Lennard J.

    2007-01-01

    Aside from the appeal to administrators as a tool to reduce costs by combining less robust departments with heftier relations, interdisciplinarity is a powerful idea because it implies that different branches of knowledge can benefit from talking to one another: a grand, unified theory of knowledge in which each discipline contributes building…

  1. A Grand Unified Theory of Interdisciplinarity

    ERIC Educational Resources Information Center

    Davis, Lennard J.

    2007-01-01

    Aside from the appeal to administrators as a tool to reduce costs by combining less robust departments with heftier relations, interdisciplinarity is a powerful idea because it implies that different branches of knowledge can benefit from talking to one another: a grand, unified theory of knowledge in which each discipline contributes building…

  2. A Grounded Theory of Adult Student Persistence

    ERIC Educational Resources Information Center

    Capps, Rosemary

    2010-01-01

    This grounded theory study investigates adult student persistence at a community college. Student persistence in college is a prerequisite for degree achievement, which correlates with higher earnings and overall better quality of life. Persistence rates remain low for adult students, who combine their college endeavors with responsibilities to…

  3. The Plaid Theory of Color Mixing.

    ERIC Educational Resources Information Center

    Hanlon, Heather

    1990-01-01

    Develops a multimedia approach for teaching color theory suitable for grade four through adult. Students select the hue, value, and degree of translucence they wish to work with and through a combination of crayon work and tissue collage, create a multicolored plaid. Outlines materials, art concepts, and process involved. (KM)

  4. A computational theory of visual attention.

    PubMed Central

    Bundesen, C

    1998-01-01

    A computational theory of visual attention is presented. The basic theory (TVA) combines the biased-choice model for single-stimulus recognition with the fixed-capacity independent race model (FIRM) for selection from multi-element displays. TVA organizes a large body of experimental findings on performance in visual recognition and attention tasks. A recent development (CTVA) combines TVA with a theory of perceptual grouping by proximity. CTVA explains effects of perceptual grouping and spatial distance between items in multi-element displays. A new account of spatial focusing is proposed in this paper. The account provides a framework for understanding visual search as an interplay between serial and parallel processes. PMID:9770221

  5. Studies in quantum information theory

    NASA Astrophysics Data System (ADS)

    Menicucci, Nicolas C.

    Quantum information theory started as the backdrop for quantum computing and is often considered only in relation to this technology, which is still in its infancy. But quantum information theory is only partly about quantum computing. While much of the interest in this field is spurred by the possible use of quantum computers for code breaking using fast factoring algorithms, to a physicist interested in deeper issues, it presents an entirely new set of questions based on an entirely different way of looking at the quantum world. This thesis is an exploration of several topics in quantum information theory. But it is also more than this. This thesis explores the new paradigm brought about by quantum information theory---that of physics as the flow of information. The thesis consists of three main parts. The first part describes my work on continuous-variable cluster states, a new platform for quantum computation. This begins with background material discussing classical and quantum computation and emphasizing the physical underpinnings of each, followed by a discussion of two recent unorthodox models of quantum computation. These models are combined into an original proposal for quantum computation using continuous-variable cluster states, including a proposed optical implementation. These are followed by a mathematical result radically simplifying the optical construction. Subsequent work simplifies this connection even further and provides a constructive proposal for scalable generation of large-scale cluster states---necessary if there is to be any hope of using this method in practical quantum computation. Experimental implementation is currently underway by my collaborators at The University of Virginia. The second part describes my work related to the physics of trapped ions, starting with an overview of the basic theory of linear ion traps. Although ion traps are often discussed in terms of their potential use for quantum computation, my work looks at their

  6. Supersymmetry and String Theory

    NASA Astrophysics Data System (ADS)

    Dine, Michael

    2016-01-01

    Preface to the first edition; Preface to the second edition; A note on choice of metric; Text website; Part I. Effective Field Theory: The Standard Model, Supersymmetry, Unification: 1. Before the Standard Model; 2. The Standard Model; 3. Phenomenology of the Standard Model; 4. The Standard Model as an effective field theory; 5. Anomalies, instantons and the strong CP problem; 6. Grand unification; 7. Magnetic monopoles and solitons; 8. Technicolor: a first attempt to explain hierarchies; Part II. Supersymmetry: 9. Supersymmetry; 10. A first look at supersymmetry breaking; 11. The Minimal Supersymmetric Standard Model; 12. Supersymmetric grand unification; 13. Supersymmetric dynamics; 14. Dynamical supersymmetry breaking; 15. Theories with more than four conserved supercharges; 16. More supersymmetric dynamics; 17. An introduction to general relativity; 18. Cosmology; 19. Astroparticle physics and inflation; Part III. String Theory: 20. Introduction; 21. The bosonic string; 22. The superstring; 23. The heterotic string; 24. Effective actions in ten dimensions; 25. Compactification of string theory I. Tori and orbifolds; 26. Compactification of string theory II. Calabi-Yau compactifications; 27. Dynamics of string theory at weak coupling; 28. Beyond weak coupling: non-perturbative string theory; 29. Large and warped extra dimensions; 30. The landscape: a challenge to the naturalness principle; 31. Coda: where are we headed?; Part IV. The Appendices: Appendix A. Two-component spinors; Appendix B. Goldstone's theorem and the pi mesons; Appendix C. Some practice with the path integral in field theory; Appendix D. The beta function in supersymmetric Yang-Mills theory; References; Index.

  7. Testing metabolic theories.

    PubMed

    Kearney, Michael R; White, Craig R

    2012-11-01

    Metabolism is the process by which individual organisms acquire energy and materials from their environment and use them for maintenance, differentiation, growth, and reproduction. There has been a recent push to build an individual-based metabolic underpinning into ecological theory-that is, a metabolic theory of ecology. However, the two main theories of individual metabolism that have been applied in ecology-Kooijman's dynamic energy budget (DEB) theory and the West, Brown, and Enquist (WBE) theory-have fundamentally different assumptions. Surprisingly, the core assumptions of these two theories have not been rigorously compared from an empirical perspective. Before we can build an understanding of ecology on the basis of individual metabolism, we must resolve the differences between these theories and thus set the appropriate foundation. Here we compare the DEB and WBE theories in detail as applied to ontogenetic growth and metabolic scaling, from which we identify circumstances where their predictions diverge most strongly. Promising experimental areas include manipulative studies of tissue regeneration, body shape, body condition, temperature, and oxygen. Much empirical work designed specifically with DEB and WBE theory in mind is required before any consensus can be reached on the appropriate theoretical basis for a metabolic theory of ecology.

  8. A Bayesian Framework for False Belief Reasoning in Children: A Rational Integration of Theory-Theory and Simulation Theory.

    PubMed

    Asakura, Nobuhiko; Inui, Toshio

    2016-01-01

    Two apparently contrasting theories have been proposed to account for the development of children's theory of mind (ToM): theory-theory and simulation theory. We present a Bayesian framework that rationally integrates both theories for false belief reasoning. This framework exploits two internal models for predicting the belief states of others: one of self and one of others. These internal models are responsible for simulation-based and theory-based reasoning, respectively. The framework further takes into account empirical studies of a developmental ToM scale (e.g., Wellman and Liu, 2004): developmental progressions of various mental state understandings leading up to false belief understanding. By representing the internal models and their interactions as a causal Bayesian network, we formalize the model of children's false belief reasoning as probabilistic computations on the Bayesian network. This model probabilistically weighs and combines the two internal models and predicts children's false belief ability as a multiplicative effect of their early-developed abilities to understand the mental concepts of diverse beliefs and knowledge access. Specifically, the model predicts that children's proportion of correct responses on a false belief task can be closely approximated as the product of their proportions correct on the diverse belief and knowledge access tasks. To validate this prediction, we illustrate that our model provides good fits to a variety of ToM scale data for preschool children. We discuss the implications and extensions of our model for a deeper understanding of developmental progressions of children's ToM abilities.

  9. Steps in the philosophy of quantum theory

    NASA Astrophysics Data System (ADS)

    Görnitz, Th.; Weizsäcker, C. F. V.

    1. Interpretation. The Copenhagen Interpretation (CI) is a minimal semantics to quantum theory, expressing what we know at least. It can be extended into a universal Quantum Theory, applied to the observer as well as to the observed object. 2. A Universal Theory as a Philosophical Problem. A circular epistemology is proposed, consisting of nonhierarchical realism, empirism, apriorism and evolutionism, combined in a description of time: past. as discrete facts, future as continuous possibilities. 3. Quantum Logic and the Reconstruction of Quantum Theory. Non-distributive logic and Bell's theorem are discussed following Doebner and Lücke. Reconstruction is briefly described. 4. Further Philosophical Questions. Mind-body problem and holism are briefly discussed.

  10. Understanding nursing units with data and theory.

    PubMed

    Diers, Donna; Hendrickson, Karrie; Rimar, Joan; Donovan, Donna

    2013-01-01

    Nursing units are social systems whose function depends on many variables. Available nursing data, combined with a theory of organizational diagnosis, can be used to understand nursing unit performance. One troubled unit served as a case study in organizational diagnosis and treatment using modern methods of data mining and performance improvement. Systems theory did not prescribe how to fix an underbounded system. The theory did suggest, however, that addressing the characteristics of overbounded and underbounded systems can provide some order and structure and identify helpful resources. In this instance, the data analysis served to help define the unit's problems in conjunction with information gained from talking with the nurses and touring the unit, but it was the theory that gave hints for direction for change.

  11. Quantum Embedding Theories.

    PubMed

    Sun, Qiming; Chan, Garnet Kin-Lic

    2016-12-20

    In complex systems, it is often the case that the region of interest forms only one part of a much larger system. The idea of joining two different quantum simulations-a high level calculation on the active region of interest, and a low level calculation on its environment-formally defines a quantum embedding. While any combination of techniques constitutes an embedding, several rigorous formalisms have emerged that provide for exact feedback between the embedded system and its environment. These three formulations: density functional embedding, Green's function embedding, and density matrix embedding, respectively, use the single-particle density, single-particle Green's function, and single-particle density matrix as the quantum variables of interest. Many excellent reviews exist covering these methods individually. However, a unified presentation of the different formalisms is so far lacking. Indeed, the various languages commonly used, functional equations for density functional embedding, diagrammatics for Green's function embedding, and entanglement arguments for density matrix embedding, make the three formulations appear vastly different. In this Account, we introduce the basic equations of all three formulations in such a way as to highlight their many common intellectual strands. While we focus primarily on a straightforward theoretical perspective, we also give a brief overview of recent applications and possible future developments. The first section starts with density functional embedding, where we introduce the key embedding potential via the Euler equation. We then discuss recent work concerning the treatment of the nonadditive kinetic potential, before describing mean-field density functional embedding and wave function in density functional embedding. We finish the section with extensions to time-dependence and excited states. The second section is devoted to Green's function embedding. Here, we use the Dyson equation to obtain equations that

  12. Information processing in generalized probabilistic theories

    SciTech Connect

    Barrett, Jonathan

    2007-03-15

    I introduce a framework in which a variety of probabilistic theories can be defined, including classical and quantum theories, and many others. From two simple assumptions, a tensor product rule for combining separate systems can be derived. Certain features, usually thought of as specifically quantum, turn out to be generic in this framework, meaning that they are present in all except classical theories. These include the nonunique decomposition of a mixed state into pure states, a theorem involving disturbance of a system on measurement (suggesting that the possibility of secure key distribution is generic), and a no-cloning theorem. Two particular theories are then investigated in detail, for the sake of comparison with the classical and quantum cases. One of these includes states that can give rise to arbitrary nonsignaling correlations, including the superquantum correlations that have become known in the literature as nonlocal machines or Popescu-Rohrlich boxes. By investigating these correlations in the context of a theory with well-defined dynamics, I hope to make further progress with a question raised by Popescu and Rohrlich, which is why does quantum theory not allow these strongly nonlocal correlations? The existence of such correlations forces much of the dynamics in this theory to be, in a certain sense, classical, with consequences for teleportation, cryptography, and computation. I also investigate another theory in which all states are local. Finally, I raise the question of what further axiom(s) could be added to the framework in order to identify quantum theory uniquely, and hypothesize that quantum theory is optimal for computation.

  13. Differential polarization imaging. I. Theory.

    PubMed Central

    Kim, M; Keller, D; Bustamante, C

    1987-01-01

    A theory of differential polarization imaging is derived using Mueller calculus. It is shown that, for any arbitrary object, 16 images (in general different) can be obtained by combining different incident polarizations of light and measuring the specific polarization components transmitted or scattered by the object. These are called the Mueller images of the object. Mathematical expressions of these images for an object of arbitrary geometry are derived using classical vector diffraction theory and the paraxial and thin lens approximations. The object is described as a collection of point polarizable groups. The electromagnetic fields are calculated using the first Born-Approximation, but extension of the theory to higher-order approximations is shown to be straightforward. These expressions are obtained for the transmission, or bright-field, geometry, and the scattering, or dark-field, configuration. In both cases, the contributions of scattering, absorption, and background illumination to the Mueller images are characterized. The contributions of linear dichroism, circular dichroism, and linear and circular intensity differential scattering to certain Mueller images are established. It is shown that the Mueller images represent a complete two-dimensional mapping of the molecular anisotropy of the object. PMID:3427199

  14. Ordering theories: Typologies and conceptual frameworks for sociotechnical change.

    PubMed

    Sovacool, Benjamin K; Hess, David J

    2017-06-01

    What theories or concepts are most useful at explaining socio technical change? How can - or cannot - these be integrated? To provide an answer, this study presents the results from 35 semi-structured research interviews with social science experts who also shared more than two hundred articles, reports and books on the topic of the acceptance, adoption, use, or diffusion of technology. This material led to the identification of 96 theories and conceptual approaches spanning 22 identified disciplines. The article begins by explaining its research terms and methods before honing in on a combination of fourteen theories deemed most relevant and useful by the material. These are: Sociotechnical Transitions, Social Practice Theory, Discourse Theory, Domestication Theory, Large Technical Systems, Social Construction of Technology, Sociotechnical Imaginaries, Actor-Network Theory, Social Justice Theory, Sociology of Expectations, Sustainable Development, Values Beliefs Norms Theory, Lifestyle Theory, and the Unified Theory of Acceptance and Use of Technology. It then positions these theories in terms of two distinct typologies. Theories can be placed into five general categories of being centered on agency, structure, meaning, relations or norms. They can also be classified based on their assumptions and goals rooted in functionalism, interpretivism, humanism or conflict. The article lays out tips for research methodology before concluding with insights about technology itself, analytical processes associated with technology, and the framing and communication of results. An interdisciplinary theoretical and conceptual inventory has much to offer students, analysts and scholars wanting to study technological change and society.

  15. How rats combine temporal cues.

    PubMed

    Guilhardi, Paulo; Keen, Richard; MacInnis, Mika L M; Church, Russell M

    2005-05-31

    The procedures for classical and operant conditioning, and for many timing procedures, involve the delivery of reinforcers that may be related to the time of previous reinforcers and responses, and to the time of onsets and terminations of stimuli. The behavior resulting from such procedures can be described as bouts of responding that occur in some pattern at some rate. A packet theory of timing and conditioning is described that accounts for such behavior under a wide range of procedures. Applications include the food searching by rats in Skinner boxes under conditions of fixed and random reinforcement, brief and sustained stimuli, and several response-food contingencies. The approach is used to describe how multiple cues from reinforcers and stimuli combine to determine the rate and pattern of response bouts.

  16. Children's theories of motivation.

    PubMed

    Gurland, Suzanne T; Glowacky, Victoria C

    2011-09-01

    To investigate children's theories of motivation, we asked 166 children (8-12 years of age) to rate the effect of various motivational strategies on task interest, over the short and long terms, in activities described as appealing or unappealing. Children viewed the rewards strategy as resulting in greatest interest except when implemented over the long term for appealing activities. Individual difference analyses revealed that some children held operant theories of motivation, in which rewards were central, and others held hybrid theories, in which rewards were key, but some allowance was made for interest to be self-sustaining in the absence of inducements. Children's theories predicted their academic self-regulation. Their theories are discussed relative to an expert theory of motivation.

  17. 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.

  18. Domains and Naive Theories.

    PubMed

    Gelman, Susan A; Noles, Nicholaus S

    2011-09-01

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

  19. Domains and Naive Theories

    PubMed Central

    Gelman, Susan A.; Noles, Nicholaus S.

    2013-01-01

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

  20. Adaptive Motivation Theory.

    DTIC Science & Technology

    1982-02-01

    decades in an attempt to guide theory and research in animal and human learning . More recently, the orthodox behaviorists have added the category of...suggestion which will prove important in the discussion of Adaptive Motivation Theory below: he suggests that two subdivisions of learning involve learning ...of Adaptive Motivation Theory Figure 1 presents a hierarchy of learning sequences. This Insert Figure I about here hierarchy suggests that individuals

  1. The theory of flotation

    NASA Technical Reports Server (NTRS)

    Ostwald, Wolfgang

    1988-01-01

    A brief summary of the fundamentals of the Linear theory of flotation is given. The theory by no means contradicts the previous Laminar theory or even the thermodynamics (Wark-Siedler), rather it is a refinement of the known Hardy-Langmuir-Harkin conceptions for the case when there are not two phases and phase boundaries, but rather three phases and corresponding phase boundary edges. The appearance of such three-phase boundaries (ore, water, air) is characteristic for modern flotation methods.

  2. Theory Modeling and Simulation

    SciTech Connect

    Shlachter, Jack

    2012-08-23

    Los Alamos has a long history in theory, modeling and simulation. We focus on multidisciplinary teams that tackle complex problems. Theory, modeling and simulation are tools to solve problems just like an NMR spectrometer, a gas chromatograph or an electron microscope. Problems should be used to define the theoretical tools needed and not the other way around. Best results occur when theory and experiments are working together in a team.

  3. Automated Lattice Perturbation Theory

    SciTech Connect

    Monahan, Christopher

    2014-11-01

    I review recent developments in automated lattice perturbation theory. Starting with an overview of lattice perturbation theory, I focus on the three automation packages currently "on the market": HiPPy/HPsrc, Pastor and PhySyCAl. I highlight some recent applications of these methods, particularly in B physics. In the final section I briefly discuss the related, but distinct, approach of numerical stochastic perturbation theory.

  4. Why Do We Have Theories?

    ERIC Educational Resources Information Center

    Costley, Kevin C.

    2006-01-01

    University professors teaching pre-service teachers base much of their philosophies on theories. Students often ask "Why do we have theories?" "What is the purpose of theories?" "If we like a theory, do we have to use all of the theory?" The most frequent controversial issue is how to use a particular theory in a practical way. In the quest for…

  5. Making Theory Relevant: The Gender Attitude and Belief Inventory

    ERIC Educational Resources Information Center

    McCabe, Janice

    2013-01-01

    This article describes and evaluates the Gender Attitude and Belief Inventory (GABI), a teaching tool designed to aid students in (a) realizing how sociological theory links to their personal beliefs and (b) exploring any combination of 11 frequently used theoretical perspectives on gender, including both conservative theories (physiological,…

  6. ILLIAC 4 and lifting surface theory with boundary layer

    NASA Technical Reports Server (NTRS)

    Dowell, E. H.

    1976-01-01

    Aerodynamic flutter and a re-written computer program for its study are discussed. Data cover: (1) lifting surface theory with boundary layer, (2) incompressible, two dimensional, unsteady flow with control surfaces, (3) improved unsteady theory, (4) combined transonic airfoil thickness and shear layer thickness effects, and (5) bending-torsion flutter calculations.

  7. Teaching English Reading through MI Theory in Primary Schools

    ERIC Educational Resources Information Center

    Jing, Jinxiu

    2013-01-01

    The theory of Multiple Intelligences (MI theory), put forward by Gardner in 1983, claims that each person possesses different combinations of nine intelligences. In education, it advocates that teachers should address students' personal uniqueness and provide a wide range of intelligence-oriented activities and experiences to facilitate learning,…

  8. The Basics of Item Response Theory. Second Edition.

    ERIC Educational Resources Information Center

    Baker, Frank B.

    This book is combined with a Web site to allow the reader to acquire the basic concepts of item response theory without becoming enmeshed in the underlying mathematical and computational complexities. The first edition, with its accompanying software, was designed to give the reader access to the basic concepts of item response theory without…

  9. Propeller theory of Professor Joukowski and his pupils

    NASA Technical Reports Server (NTRS)

    Margoulis, W

    1922-01-01

    This report gives a summary of the work done in Russia from 1911 to 1914, by Professor Joukowski and his pupils. This summary will show that these men were the true originators of the theory, which combines the theory of the wing element and of the slipstream.

  10. Professional Education: The Theory-Practice Issue Reconsidered

    ERIC Educational Resources Information Center

    Morehead, Joseph H.

    1973-01-01

    Professional education exhibits a dichotomous nature that seeks to emphasize theory while recognizing the practical component. The question of theory versus practice that has informed the perennial debate is a false one. In several professions wide variation exists in ways theoretical studies and experential component are combined in curricula.…

  11. Adolescent Marijuana Use Intentions: Using Theory to Plan an Intervention

    ERIC Educational Resources Information Center

    Sayeed, Sarah; Fishbein, Martin; Hornik, Robert; Cappella, Joseph; Kirkland Ahern, R.

    2005-01-01

    This paper uses an integrated model of behavior change to predict intentions to use marijuana occasionally and regularly in a US-based national sample of male and female 12 to 18 year olds (n = 600). The model combines key constructs from the theory of reasoned action and social cognitive theory. The survey was conducted on laptop computers, and…

  12. Making Theory Relevant: The Gender Attitude and Belief Inventory

    ERIC Educational Resources Information Center

    McCabe, Janice

    2013-01-01

    This article describes and evaluates the Gender Attitude and Belief Inventory (GABI), a teaching tool designed to aid students in (a) realizing how sociological theory links to their personal beliefs and (b) exploring any combination of 11 frequently used theoretical perspectives on gender, including both conservative theories (physiological,…

  13. Berry Fermi liquid theory

    NASA Astrophysics Data System (ADS)

    Chen, Jing-Yuan; Son, Dam Thanh

    2017-02-01

    We develop an extension of the Landau Fermi liquid theory to systems of interacting fermions with non-trivial Berry curvature. We propose a kinetic equation and a constitutive relation for the electromagnetic current that together encode the linear response of such systems to external electromagnetic perturbations, to leading and next-to-leading orders in the expansion over the frequency and wave number of the perturbations. We analyze the Feynman diagrams in a large class of interacting quantum field theories and show that, after summing up all orders in perturbation theory, the current-current correlator exactly matches with the result obtained from the kinetic theory.

  14. The Big Bang Theory

    SciTech Connect

    Lincoln, Don

    2014-09-30

    The Big Bang is the name of the most respected theory of the creation of the universe. Basically, the theory says that the universe was once smaller and denser and has been expending for eons. One common misconception is that the Big Bang theory says something about the instant that set the expansion into motion, however this isn’t true. In this video, Fermilab’s Dr. Don Lincoln tells about the Big Bang theory and sketches some speculative ideas about what caused the universe to come into existence.

  15. Ostwald ripening theory

    NASA Technical Reports Server (NTRS)

    Baird, J. K.

    1986-01-01

    The Ostwald-ripening theory is deduced and discussed starting from the fundamental principles such as Ising model concept, Mayer cluster expansion, Langer condensation point theory, Ginzburg-Landau free energy, Stillinger cutoff-pair potential, LSW-theory and MLSW-theory. Mathematical intricacies are reduced to an understanding version. Comparison of selected works, from 1949 to 1984, on solution of diffusion equation with and without sink/sources term(s) is presented. Kahlweit's 1980 work and Marqusee-Ross' 1954 work are more emphasized. Odijk and Lekkerkerker's 1985 work on rodlike macromolecules is introduced in order to simulate interested investigators.

  16. Between Theory and Observations

    NASA Astrophysics Data System (ADS)

    Wepster, Steven

    Three great mathematicians dominate the history of lunar theory in the middle of the eighteenth century: Leonhard Euler, Alexis Clairaut, and Jean le Rond d’Alembert. Each of them made a lasting contribution to the theory of celestial mechanics and their results had a broader impact than on lunar theory alone. To name but a few examples, Euler codified the trigonometric functions and pioneered the method of variation of orbital constants; Clairaut solved the arduous problem of the motion of the lunar apogee, thereby dealing a decisive blow to the sceptics of Newton’s law of gravitation; and d’Alembert worked out an accurate theory of precession and nutation.

  17. The Big Bang Theory

    ScienceCinema

    Lincoln, Don

    2016-07-12

    The Big Bang is the name of the most respected theory of the creation of the universe. Basically, the theory says that the universe was once smaller and denser and has been expending for eons. One common misconception is that the Big Bang theory says something about the instant that set the expansion into motion, however this isn’t true. In this video, Fermilab’s Dr. Don Lincoln tells about the Big Bang theory and sketches some speculative ideas about what caused the universe to come into existence.

  18. Study on vapor-liquid equilibria and surface tensions for nonpolar fluids by renormalization group theory and density gradient theory.

    PubMed

    Fu, Dong

    2006-10-05

    An equation of state (EOS) applicable for both the uniform and nonuniform fluids is established by using the density-gradient theory (DGT). In the bulk phases, the EOS reduces to statistical associating fluid theory (SAFT). By combining the EOS with the renormalization group theory (RGT), the vapor-liquid-phase equilibria and surface tensions for 10 nonpolar chainlike fluids are investigated from low temperature up to the critical point. The obtained results agree well with the experimental data.

  19. Analysis of fractals with combined partition

    NASA Astrophysics Data System (ADS)

    Dedovich, T. G.; Tokarev, M. V.

    2016-03-01

    The space—time properties in the general theory of relativity, as well as the discreteness and non-Archimedean property of space in the quantum theory of gravitation, are discussed. It is emphasized that the properties of bodies in non-Archimedean spaces coincide with the properties of the field of P-adic numbers and fractals. It is suggested that parton showers, used for describing interactions between particles and nuclei at high energies, have a fractal structure. A mechanism of fractal formation with combined partition is considered. The modified SePaC method is offered for the analysis of such fractals. The BC, PaC, and SePaC methods for determining a fractal dimension and other fractal characteristics (numbers of levels and values of a base of forming a fractal) are considered. It is found that the SePaC method has advantages for the analysis of fractals with combined partition.

  20. A Theory of Imperfection: An Imperfect Theory?

    ERIC Educational Resources Information Center

    Piel, Ellen R.

    1979-01-01

    Problems faced by counselor education programs is that of reconciling the split between the traditional academic emphasis on teaching and research and practical experience and personal growth. Contends counselors' failure to recognize the value of theories in counseling may pose some problems for our profession as a whole. (Author)

  1. A Theory of Imperfection: An Imperfect Theory?

    ERIC Educational Resources Information Center

    Piel, Ellen R.

    1979-01-01

    Problems faced by counselor education programs is that of reconciling the split between the traditional academic emphasis on teaching and research and practical experience and personal growth. Contends counselors' failure to recognize the value of theories in counseling may pose some problems for our profession as a whole. (Author)

  2. Eigenvalue Detonation of Combined Effects Aluminized Explosives

    NASA Astrophysics Data System (ADS)

    Capellos, C.; Baker, E. L.; Nicolich, S.; Balas, W.; Pincay, J.; Stiel, L. I.

    2007-12-01

    Theory and performance for recently developed combined—effects aluminized explosives are presented. Our recently developed combined-effects aluminized explosives (PAX-29C, PAX-30, PAX-42) are capable of achieving excellent metal pushing, as well as high blast energies. Metal pushing capability refers to the early volume expansion work produced during the first few volume expansions associated with cylinder and wall velocities and Gurney energies. Eigenvalue detonation explains the observed detonation states achieved by these combined effects explosives. Cylinder expansion data and thermochemical calculations (JAGUAR and CHEETAH) verify the eigenvalue detonation behavior.

  3. Prediction of Exercise in Patients across Various Stages of Bariatric Surgery: A Comparison of the Merits of the Theory of Reasoned Action versus the Theory of Planned Behavior

    ERIC Educational Resources Information Center

    Hunt, Hillary R.; Gross, Alan M.

    2009-01-01

    Obesity is a world-wide health concern approaching epidemic proportions. Successful long-term treatment involves a combination of bariatric surgery, diet, and exercise. Social cognitive models, such as the Theory of Reasoned Action (TRA) and the Theory of Planned Behavior (TPB), are among the most commonly tested theories utilized in the…

  4. Prediction of Exercise in Patients across Various Stages of Bariatric Surgery: A Comparison of the Merits of the Theory of Reasoned Action versus the Theory of Planned Behavior

    ERIC Educational Resources Information Center

    Hunt, Hillary R.; Gross, Alan M.

    2009-01-01

    Obesity is a world-wide health concern approaching epidemic proportions. Successful long-term treatment involves a combination of bariatric surgery, diet, and exercise. Social cognitive models, such as the Theory of Reasoned Action (TRA) and the Theory of Planned Behavior (TPB), are among the most commonly tested theories utilized in the…

  5. Optical activity of chirally distorted nanocrystals

    NASA Astrophysics Data System (ADS)

    Tepliakov, Nikita V.; Baimuratov, Anvar S.; Baranov, Alexander V.; Fedorov, Anatoly V.; Rukhlenko, Ivan D.

    2016-05-01

    We develop a general theory of optical activity of semiconductor nanocrystals whose chirality is induced by a small perturbation of their otherwise achiral electronic subsystems. The optical activity is described using the quantum-mechanical expressions for the rotatory strengths and dissymmetry factors introduced by Rosenfeld. We show that the rotatory strengths of optically active transitions are decomposed on electric dipole and magnetic dipole contributions, which correspond to the electric dipole and magnetic dipole transitions between the unperturbed quantum states. Remarkably, while the two kinds of rotatory strengths are of the same order of magnitude, the corresponding dissymmetry factors can differ by a factor of 105. By maximizing the dissymmetry of magnetic dipole absorption one can significantly enhance the enantioselectivity in the interaction of semiconductor nanocrystals with circularly polarized light. This feature may advance chiral and analytical methods, which will benefit biophysics, chemistry, and pharmaceutical science. The developed theory is illustrated by an example of intraband transitions inside a semiconductor nanocuboid, whose rotatory strengths and dissymmetry factors are calculated analytically.

  6. Optical activity of chirally distorted nanocrystals

    SciTech Connect

    Tepliakov, Nikita V.; Baimuratov, Anvar S.; Baranov, Alexander V.; Fedorov, Anatoly V.; Rukhlenko, Ivan D.

    2016-05-21

    We develop a general theory of optical activity of semiconductor nanocrystals whose chirality is induced by a small perturbation of their otherwise achiral electronic subsystems. The optical activity is described using the quantum-mechanical expressions for the rotatory strengths and dissymmetry factors introduced by Rosenfeld. We show that the rotatory strengths of optically active transitions are decomposed on electric dipole and magnetic dipole contributions, which correspond to the electric dipole and magnetic dipole transitions between the unperturbed quantum states. Remarkably, while the two kinds of rotatory strengths are of the same order of magnitude, the corresponding dissymmetry factors can differ by a factor of 10{sup 5}. By maximizing the dissymmetry of magnetic dipole absorption one can significantly enhance the enantioselectivity in the interaction of semiconductor nanocrystals with circularly polarized light. This feature may advance chiral and analytical methods, which will benefit biophysics, chemistry, and pharmaceutical science. The developed theory is illustrated by an example of intraband transitions inside a semiconductor nanocuboid, whose rotatory strengths and dissymmetry factors are calculated analytically.

  7. Combination opioid analgesics.

    PubMed

    Smith, Howard S

    2008-01-01

    Although there is no "ideal analgesic," scientists and clinicians alike continue to search for compounds with qualities which may approach the "ideal analgesic." Characteristics of an "ideal" analgesic may include: the agent is a full agonist providing optimal/maximal analgesia for a wide range/variety of pain states (e.g., broad spectrum analgesic activity), it does not exhibit tolerance, it produces no unwanted effects and minimal adverse effects, it has no addictive potential, it does not facilitate pain/hyperalgesia, it has a long duration, it has high oral bioavailability, it is not vulnerable to important drug interactions, it is not significantly bound to plasma proteins, it has no active metabolites, it has linear kinetics, and it is eliminated partly by hydrolysis to an inactive metabolite (without involvement of oxidative and conjugative enzymes). Investigators have concentrated on ways to alter existing analgesics or to combine existing analgesic compounds with compounds which may improve efficacy over time or minimize adverse effects. The addition of an analgesic with a second agent (which may or may not also be an analgesic) to achieve a "combination analgesic" is a concept which has been exploited for many years. Although there may be many reasons to add 2 agents together in efforts to achieve analgesia, for purposes of this article - reasons for combining an opioid with a second agent to produce a combination opioid analgesic may be classified into 6 major categories: 1.) combinations to prolong analgesic duration; 2.) combinations to enhance or optimize analgesic efficacy (e.g., analgesic synergy); 3.) combinations to diminish or minimize adverse effects; 4.) combinations to diminish opioid effects which are not beneficial (or contrariwise to or enhance beneficial opioid effects); 5.) combinations to reduce opioid tolerance/opioid-induced hyperalgesia; and 6.) combinations to combat dependency issues/addiction potential/craving sensations

  8. Piaget's Social Theory.

    ERIC Educational Resources Information Center

    DeVries, Rheta

    1997-01-01

    Argues that Piaget did not consider social factors to be important in his developmental theory and considers some of the practical educational implications of Piaget's social theory. Piaget's notion of the role of social factors is reviewed, and the educational implications of the cooperative context favoring operational development with reference…

  9. Schema Theory Revisited

    ERIC Educational Resources Information Center

    McVee, Mary B.; Dunsmore, Kailonnie; Gavelek, James R.

    2005-01-01

    During the 1970s, schema theory gained prominence as reading researchers took up early work by cognitive scientists to explore the role of schemas in reading. In the 1980s and '90s, the field shifted as researchers increasingly used sociocultural theories, particularly the work of L. S. Vygotsky, to frame investigations of literacy. This article…

  10. Reimagining Critical Theory

    ERIC Educational Resources Information Center

    Rexhepi, Jevdet; Torres, Carlos Alberto

    2011-01-01

    This paper discusses Critical Theory, a model of theorizing in the field of the political sociology of education. We argue for a "reimagined" Critical Theory to herald an empowering, liberatory education that fosters curiosity and critical thinking, and a means for successful bottom-up, top-down political engagement. We present arguments…

  11. Towards Extended Vantage Theory

    ERIC Educational Resources Information Center

    Glaz, Adam

    2010-01-01

    The applicability of Vantage Theory (VT), a model of (colour) categorization, to linguistic data largely depends on the modifications and adaptations of the model for the purpose. An attempt to do so proposed here, called Extended Vantage Theory (EVT), slightly reformulates the VT conception of vantage by capitalizing on some of the entailments of…

  12. Greek Atomic Theory.

    ERIC Educational Resources Information Center

    Roller, Duane H. D.

    1981-01-01

    Focusing on history of physics, which began about 600 B.C. with the Ionian Greeks and reaching full development within three centuries, suggests that the creation of the concept of the atom is understandable within the context of Greek physical theory; so is the rejection of the atomic theory by the Greek physicists. (Author/SK)

  13. Theory and Motivational Psychology.

    ERIC Educational Resources Information Center

    Atkinson, John W.

    Motivational psychology and test theory are compared in this discussion, which focuses on distinguishing the effects of motivation and of ability on test performance and educational achievement. Recent theory in achievement motivation considers the motivational significance of future goals as they affect present activities that are instrumental in…

  14. Organization Theory as Ideology.

    ERIC Educational Resources Information Center

    Greenfield, Thomas B.

    The theory that organizations are ideological inventions of the human mind is discussed. Organizational science is described as an ideology which is based upon social concepts and experiences. The main justification for organizational theory is that it attempts to answer why we behave as we do in social organizations. Ways in which ideas and…

  15. Put Theory into Practice

    ERIC Educational Resources Information Center

    Jaeger, Audrey J.; Dunstan, Stephany; Thornton, Courtney; Rockenbach, Alyssa B.; Gayles, Joy G.; Haley, Karen J.

    2013-01-01

    When making decisions that impact student learning, college educators often consider previous experiences, precedent, common sense, and advice from colleagues. But how often do they consider theory? At a recent state-level educators' meeting, the authors of this article asked 50 student affairs educators about the use of theory in their practice.…

  16. Theory and Motivational Psychology.

    ERIC Educational Resources Information Center

    Atkinson, John W.

    Motivational psychology and test theory are compared in this discussion, which focuses on distinguishing the effects of motivation and of ability on test performance and educational achievement. Recent theory in achievement motivation considers the motivational significance of future goals as they affect present activities that are instrumental in…

  17. Put Theory into Practice

    ERIC Educational Resources Information Center

    Jaeger, Audrey J.; Dunstan, Stephany; Thornton, Courtney; Rockenbach, Alyssa B.; Gayles, Joy G.; Haley, Karen J.

    2013-01-01

    When making decisions that impact student learning, college educators often consider previous experiences, precedent, common sense, and advice from colleagues. But how often do they consider theory? At a recent state-level educators' meeting, the authors of this article asked 50 student affairs educators about the use of theory in their practice.…

  18. Entanglement in theory space

    NASA Astrophysics Data System (ADS)

    Yamazaki, Masahito

    2013-07-01

    We propose a new concept of entanglement for quantum systems: entanglement in theory space. This is defined by decomposing a theory into two by an un-gauging procedure. We provide two examples where this newly introduced entanglement is closely related to conventional geometric entropies: deconstruction and AGT-type correspondence.

  19. Evolution: Theory or Dogma?

    ERIC Educational Resources Information Center

    Mayer, William V.

    In this paper the author examines the question of whether evolution is a theory or a dogma. He refutes the contention that there is a monolithic scientific conspiracy to present evolution as dogma and suggests that his own presentation might be more appropriately entitled "Creationism: Theory or Dogma." (PEB)

  20. Greek Atomic Theory.

    ERIC Educational Resources Information Center

    Roller, Duane H. D.

    1981-01-01

    Focusing on history of physics, which began about 600 B.C. with the Ionian Greeks and reaching full development within three centuries, suggests that the creation of the concept of the atom is understandable within the context of Greek physical theory; so is the rejection of the atomic theory by the Greek physicists. (Author/SK)

  1. Towards Extended Vantage Theory

    ERIC Educational Resources Information Center

    Glaz, Adam

    2010-01-01

    The applicability of Vantage Theory (VT), a model of (colour) categorization, to linguistic data largely depends on the modifications and adaptations of the model for the purpose. An attempt to do so proposed here, called Extended Vantage Theory (EVT), slightly reformulates the VT conception of vantage by capitalizing on some of the entailments of…

  2. What Is Integral Theory?

    ERIC Educational Resources Information Center

    Marquis, Andre

    2007-01-01

    Integral theory is a way of knowing that helps foster the recognition that disparate aspects of reality--such as biological constitution, cultural worldviews, felt-sense of selfhood, and social systems--are all critically important to any knowledge quest. Integral theory provides an "all quadrants, all levels" (K. Wilber, 2006, p. 26)…

  3. Game Theory .net.

    ERIC Educational Resources Information Center

    Shor, Mikhael

    2003-01-01

    States making game theory relevant and accessible to students is challenging. Describes the primary goal of GameTheory.net is to provide interactive teaching tools. Indicates the site strives to unite educators from economics, political and computer science, and ecology by providing a repository of lecture notes and tests for courses using…

  4. Why Bohm's Quantum Theory?

    NASA Astrophysics Data System (ADS)

    Zeh, H. D.

    1999-04-01

    This is a brief reply to S. Goldstein's article "Quantum theory without observers" in Physics Today. It is pointed out that Bohm's pilot wave theory is successful only because it keeps Schrödinger's (exact) wave mechanics unchanged, while the rest of it is observationally meaningless and solely based on classical prejudice.

  5. Evolution - A Theory Evolving

    ERIC Educational Resources Information Center

    Weinberg, Janet H.

    1975-01-01

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

  6. French Theory's American Adventures

    ERIC Educational Resources Information Center

    Cusset, Francois

    2008-01-01

    In this article, the author discusses how it is simply too late to be still speaking about French theory and its role in the intellectual life of the United States today. It seems to many observers that the gap between real-life politics and theory's guerrillas is much too wide already, after 30 years of academic fever, for the two worlds to even…

  7. History, Theory, and Education

    ERIC Educational Resources Information Center

    Rury, John L.

    2011-01-01

    In this article, the author discusses the question of theory as it may pertain to the history of education, with particular attention to the United States. Historians, like everyone else, have little choice regarding the use of theory; to one extent or another they must. The question is how much and to what end. The author aims to consider the…

  8. Progress in string theory

    NASA Astrophysics Data System (ADS)

    Maldacena, Juan Martín

    D-Branes on Calabi-Yau manifolds / Paul S. Aspinwall -- Lectures on AdS/CFT / Juan M. Maldacena -- Tachyon dynamics in open string theory / Ashoke Sen -- TASI/PITP/ISS lectures on moduli and microphysics / Eva Silverstein -- The duality cascade / Matthew J. Strassler -- Perturbative computations in string field theory / Washington Taylor -- Student seminars -- Student participants -- Lecturers, directors, and local organizing committee.

  9. Evaluating Conceptual Metaphor Theory

    ERIC Educational Resources Information Center

    Gibbs, Raymond W., Jr.

    2011-01-01

    A major revolution in the study of metaphor occurred 30 years ago with the introduction of "conceptual metaphor theory" (CMT). Unlike previous theories of metaphor and metaphorical meaning, CMT proposed that metaphor is not just an aspect of language, but a fundamental part of human thought. Indeed, most metaphorical language arises from…

  10. History, Theory, and Education

    ERIC Educational Resources Information Center

    Rury, John L.

    2011-01-01

    In this article, the author discusses the question of theory as it may pertain to the history of education, with particular attention to the United States. Historians, like everyone else, have little choice regarding the use of theory; to one extent or another they must. The question is how much and to what end. The author aims to consider the…

  11. Universality and string theory

    NASA Astrophysics Data System (ADS)

    Bachlechner, Thomas Christian

    The first run at the Large Hadron Collider has deeply challenged conventional notions of naturalness, and CMB polarization experiments are about to open a new window to early universe cosmology. As a compelling candidate for the ultraviolet completion of the standard model, string theory provides a prime opportunity to study both early universe cosmology and particle physics. However, relating low energy observations to ultraviolet physics requires knowledge of the metastable states of string theory through the study of vacua. While it is difficult to directly obtain infrared data from explicit string theory constructions, string theory imposes constraints on low energy physics. The study of ensembles of low energy theories consistent with ultra-violet constraints provides insight on generic features we might expect to occur in string compactifications. In this thesis we present a statistical treatment of vacuum stability and vacuum properties in the context of random supergravity theories motivated by string theory. Early universe cosmology provides another avenue to high energy physics. From the low energy perspective large field inflation is typically considered highly unnatural: the scale relevant for the diameter of flat regions in moduli space is sub-Planckian in regions of perturbative control. To approach this problem, we consider generic Calabi-Yau compactifications of string theory and find that super-Planckian diameters of axion fundamental domains in fact arise generically. We further demonstrate that such super-Planckian flat regions are plausibly consistent with theWeak Gravity Conjecture.

  12. The Theory of Electricity

    NASA Astrophysics Data System (ADS)

    Livens, G. H.

    2016-10-01

    Preface; 1. The electric field; 2. Dielectric theory; 3. Electric currents; 4. The magnetic field; 5. The dynamics of the magnetic field; 6. Maxwell's electromagnetic theory; 7. Electromagnetic oscillations and waves; 8. The electrodynamics of moving media; Appendix 1. On the mechanism of magnetic induction; Appendix 2. On the mechanism of metallic conduction; Index.

  13. In Defense of Theory

    ERIC Educational Resources Information Center

    Jackendoff, Ray

    2017-01-01

    Formal theories of mental representation have receded from the importance they had in the early days of cognitive science. I argue that such theories are crucial in any mental domain, not just for their own sake, but to guide experimental inquiry, as well as to integrate the domain into the mind as a whole. To illustrate the criteria of adequacy…

  14. The Learning Theory Jungle

    ERIC Educational Resources Information Center

    Minter, Robert L.

    2011-01-01

    This article addresses the myriad of pedagogical and andragogical issues facing university educators in the student learning process. It briefly explores the proliferation of learning theories in an attempt to develop awareness among faculty who teach at the university/college levels that not all theories of learning apply to the adult learner. In…

  15. Evaluating Conceptual Metaphor Theory

    ERIC Educational Resources Information Center

    Gibbs, Raymond W., Jr.

    2011-01-01

    A major revolution in the study of metaphor occurred 30 years ago with the introduction of "conceptual metaphor theory" (CMT). Unlike previous theories of metaphor and metaphorical meaning, CMT proposed that metaphor is not just an aspect of language, but a fundamental part of human thought. Indeed, most metaphorical language arises from…

  16. Flory theory for polymers.

    PubMed

    Bhattacharjee, Somendra M; Giacometti, Achille; Maritan, Amos

    2013-12-18

    We review various simple analytical theories for homopolymers within a unified framework. The common guideline of our approach is the Flory theory, and its various avatars, with the attempt at being reasonably self-contained. We expect this review to be useful as an introduction to the topic at the graduate student level.

  17. Test Theory Reconceived.

    ERIC Educational Resources Information Center

    Mislevy, Robert J.

    Educational test theory consists of statistical and methodological tools to support inferences about examinees' knowledge, skills, and accomplishments. The evolution of test theory has been shaped by the nature of users' inferences which, until recently, have been framed almost exclusively in terms of trait and behavioral psychology. Progress in…

  18. Personal Theories of Teaching.

    ERIC Educational Resources Information Center

    Fox, Dennis

    1983-01-01

    Four theories of teaching are presented based on faculty definitions of teaching: knowledge transfer; shaping students to a predetermined mold; exploratory; and developmental. These theories are related to student attitudes about learning and are offered as a means of resolving misunderstandings among teachers and between teachers and students.…

  19. Plasma Theory and Simulation.

    DTIC Science & Technology

    1981-03-31

    measured and appear to be comparable to those predicted by the Vlasov-fluid theory of Seylerl and the finite Larmor radius theory of Freidberg and...C.E. Seyler, "Vlasov-Fluid Stability of a Rigidly Rotating Theta Pinch," Phys. Fluids 22, 2324, (1979). 2. J.P. Freidberg , L.D. Pearlstein

  20. The Learning Theory Jungle

    ERIC Educational Resources Information Center

    Minter, Robert L.

    2011-01-01

    This article addresses the myriad of pedagogical and andragogical issues facing university educators in the student learning process. It briefly explores the proliferation of learning theories in an attempt to develop awareness among faculty who teach at the university/college levels that not all theories of learning apply to the adult learner. In…