Zinc surface complexes on birnessite: A density functional theory study
Energy Technology Data Exchange (ETDEWEB)
Kwon, Kideok D.; Refson, Keith; Sposito, Garrison
2009-01-05
Biogeochemical cycling of zinc is strongly influenced by sorption on birnessite minerals (layer-type MnO2), which are found in diverse terrestrial and aquatic environments. Zinc has been observed to form both tetrahedral (Zn{sup IV}) and octahedral (Zn{sup VI}) triple-corner-sharing surface complexes (TCS) at Mn(IV) vacancy sites in hexagonal birnessite. The octahedral complex is expected to be similar to that of Zn in the Mn oxide mineral, chalcophanite (ZnMn{sub 3}O{sub 7} {center_dot} 3H{sub 2}O), but the reason for the occurrence of the four-coordinate Zn surface species remains unclear. We address this issue computationally using spin-polarized Density Functional Theory (DFT) to examine the Zn{sub IV}-TCS and Zn{sup VI}-TCS species. Structural parameters obtained by DFT geometry optimization were in excellent agreement with available experimental data on Zn-birnessites. Total energy, magnetic moments, and electron-overlap populations obtained by DFT for isolated Zn{sup IV}-TCS revealed that this species is stable in birnessite without a need for Mn(III) substitution in the octahedral sheet and that it is more effective in reducing undersaturation of surface O at a Mn vacancy than is Zn{sub VI}-TCS. Comparison between geometry-optimized ZnMn{sub 3}O{sub 7} {center_dot} 3H{sub 2}O (chalcophanite) and the hypothetical monohydrate mineral, ZnMn{sub 3}O{sub 7} {center_dot} H{sub 2}O, which contains only tetrahedral Zn, showed that the hydration state of Zn significantly affects birnessite structural stability. Finally, our study also revealed that, relative to their positions in an ideal vacancy-free MnO{sub 2}, Mn nearest to Zn in a TCS surface complex move toward the vacancy by 0.08-0.11 {angstrom}, while surface O bordering the vacancy move away from it by 0.16-0.21 {angstrom}, in agreement with recent X-ray absorption spectroscopic analyses.
Corrected Debye-Hückel analysis of surface complexation. II. A theory of surface charging.
Gunnarsson, Magnus; Abbas, Zareen; Ahlberg, Elisabet; Gobom, Sylvia; Nordholm, Sture
2002-05-01
A theory of surface charging of colloidal particles suspended in an electrolyte solution is presented. The charging at the particle surface is assumed to originate from the adsorption and desorption of protons and is therefore strongly dependent on the acidity of the solution. The surface binding of protons occurs locally at sites of occupancy zero or one that are described by a binding energy u(0) and a three-dimensional vibration of frequency nu. The diffuse screening of ions at the surface is described by the corrected Debye-Hückel analysis assuming linear response. The model contains a capacitor layer close to the charged surface and the finite size of the electrolyte ions is taken into account. The theory has been applied to titrated surface charge data on goethite (alpha-FeOOH) at NaClO(4) background concentrations ranging from 0.01 to 1.0 M. The protonation mechanism used in the modeling of these data corresponds to the 1-pK approach. A very good description of the experimental data was obtained at the highest ionic strength. Close to the pH(pzc) the theory also gave a good description at lower ionic strengths. However, at low salt concentrations and pH values far away from the pH(pzc) the electrostatic potential outside the capacitor layer becomes so high that nonlinear electrostatic effects become important and the theory therefore underestimates the surface charge. These results were compared with model calculations obtained using existing surface complexation models.
Lee, William H K.
2016-01-01
A complex system consists of many interacting parts, generates new collective behavior through self organization, and adaptively evolves through time. Many theories have been developed to study complex systems, including chaos, fractals, cellular automata, self organization, stochastic processes, turbulence, and genetic algorithms.
Operational Shock Complexity Theory
2005-05-26
Theory : Recommendations For The National Strategy To Defeat Terrorism.” Student Issue Paper, Center for Strategic Leadership , US Army War College, July...Lens of Complexity Theory : Recommendations For The National Strategy To Defeat Terrorism.” (Student Issue Paper, Center for Strategic Leadership , US...planners managed to cause confusion in the enemy’s internal model by operating in an unexpected manner. 140 Glenn E. James, “Chaos Theory : The
Energy Technology Data Exchange (ETDEWEB)
Kostyrko, T., E-mail: tkos@amu.edu.pl; Ślusarski, T. [Faculty of Physics, A. Mickiewicz University, ul. Umultowska 85, 61-614 Poznań (Poland)
2015-01-21
A modification of the electronic and magnetic structure of a metalorganic complex by chemisorption at a metallic surface is addressed. The density functional theory (DFT) is applied to investigate a simplified form of a copper-dioxolene complex in a free state and connected to Au(111) surface with alkanethiol linkers. A systematic study of the dependence of the system electronic structure on the linker length is performed. It is found that the electronic structure of the complex is well preserved during the adsorption process. The magnetic moment of the Cu-dioxolene functional group is shown to be strictly correlated with the amount of the charge residing at the complex. On the basis of the DFT results, a model Hamiltonian of the adsorbed metalorganic system is proposed. The model is an extension of the Sandorfy's model of the alkanes and includes explicitly Coulomb interaction between electrons both within the alkane's backbone and the end group. We show that the latter feature is necessary to understand the evolution of the system's properties with the length of the linkers. The advantage of this approach is that it not only reproduces the main results of our DFT analysis but also provides a simple common basis to analyse a wide class of metal complexes bound to metal surfaces with alkanethiol linkers.
Theories of computational complexity
Calude, C
1988-01-01
This volume presents four machine-independent theories of computational complexity, which have been chosen for their intrinsic importance and practical relevance. The book includes a wealth of results - classical, recent, and others which have not been published before.In developing the mathematics underlying the size, dynamic and structural complexity measures, various connections with mathematical logic, constructive topology, probability and programming theories are established. The facts are presented in detail. Extensive examples are provided, to help clarify notions and constructions. The lists of exercises and problems include routine exercises, interesting results, as well as some open problems.
Sarason, Donald
2007-01-01
Complex Function Theory is a concise and rigorous introduction to the theory of functions of a complex variable. Written in a classical style, it is in the spirit of the books by Ahlfors and by Saks and Zygmund. Being designed for a one-semester course, it is much shorter than many of the standard texts. Sarason covers the basic material through Cauchy's theorem and applications, plus the Riemann mapping theorem. It is suitable for either an introductory graduate course or an undergraduate course for students with adequate preparation. The first edition was published with the title Notes on Co
Shao, Yangfan; Li, Chongyang; Feng, Yuanming; Lin, Wang
2013-12-01
This paper experimentally and theoretically investigated Raman and surface-enhanced Raman scattering (SERS) of 1,4-benzenedithiol (1,4-BDT). Density functional theory methods were used to study Raman scattering spectra of isolated 1,4-BDT and 1,4-BDT-Agn (n=2,4,6) complexes with B3LYP/6-311+g(d)(C,H,S)/Lanl2dz(Ag) basis set. A full assignment of the Raman spectrum of 1,4-BDT has been made based on the DFT analysis. The calculated data showed good agreement with experimental observations. The adsorption sites, metal cluster size, and HOMO-LUMO energies are discussed to give insight in the SERS mechanisms for 1,4-BDT molecules. Copyright © 2013 Elsevier B.V. All rights reserved.
Complexity in governance network theory
E-H. Klijn (Erik-Hans); J.F.M. Koppenjan (Joop)
2014-01-01
markdownabstractIn this article, we discuss how complexity is viewed in governance network theory. The article provides a systematic elaboration of the notion of complexity, distinguishing three types: substantive, strategic , and institutional complexity. We argue that dealing with these types of
Advances in computational complexity theory
Cai, Jin-Yi
1993-01-01
This collection of recent papers on computational complexity theory grew out of activities during a special year at DIMACS. With contributions by some of the leading experts in the field, this book is of lasting value in this fast-moving field, providing expositions not found elsewhere. Although aimed primarily at researchers in complexity theory and graduate students in mathematics or computer science, the book is accessible to anyone with an undergraduate education in mathematics or computer science. By touching on some of the major topics in complexity theory, this book sheds light on this burgeoning area of research.
Complexity in governance network theory
Klijn, Erik-Hans; Koppenjan, Joop
2014-01-01
markdownabstractIn this article, we discuss how complexity is viewed in governance network theory. The article provides a systematic elaboration of the notion of complexity, distinguishing three types: substantive, strategic , and institutional complexity. We argue that dealing with these types of complexity in networks is essentially a matter of mutual adaption and cooperation. An important explanation for the occurrence of deadlocks, breakthroughs and outcomes is the presence and the qualit...
Bläser, Markus; Manthey, Bodo
Smoothed analysis is a new way of analyzing algorithms introduced by Spielman and Teng. Classical methods like worst-case or average-case analysis have accompanying complexity classes, such as P and Avg-P, respectively. Whereas worst-case or average-case analysis give us a means to talk about the
Predictive Surface Complexation Modeling
Energy Technology Data Exchange (ETDEWEB)
Sverjensky, Dimitri A. [Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Earth and Planetary Sciences
2016-11-29
Surface complexation plays an important role in the equilibria and kinetics of processes controlling the compositions of soilwaters and groundwaters, the fate of contaminants in groundwaters, and the subsurface storage of CO_{2} and nuclear waste. Over the last several decades, many dozens of individual experimental studies have addressed aspects of surface complexation that have contributed to an increased understanding of its role in natural systems. However, there has been no previous attempt to develop a model of surface complexation that can be used to link all the experimental studies in order to place them on a predictive basis. Overall, my research has successfully integrated the results of the work of many experimentalists published over several decades. For the first time in studies of the geochemistry of the mineral-water interface, a practical predictive capability for modeling has become available. The predictive correlations developed in my research now enable extrapolations of experimental studies to provide estimates of surface chemistry for systems not yet studied experimentally and for natural and anthropogenically perturbed systems.
Surface chemistry theory and applications
Bikerman, J J
2013-01-01
Surface Chemistry Theory and Applications focuses on liquid-gas, liquid-liquid, solid-gas, solid-liquid, and solid-solid surfaces. The book first offers information on liquid-gas surfaces, including surface tension, measurement of surface tension, rate of capillarity rise, capillary attraction, bubble pressure and pore size, and surface tension and temperature. The text then ponders on liquid-liquid and solid-gas surfaces. Discussions focus on surface energy of solids, surface roughness and cleanness, adsorption of gases and vapors, adsorption hysteresis, interfacial tension, and interfacial t
Association theories for complex thermodynamics
DEFF Research Database (Denmark)
Kontogeorgis, Georgios; Rafiqul Gani
2013-01-01
models, we have now come to the understanding that simple one-fluid theories like the cubic equations of state or the various forms of local composition models will never be able to model a wide range of complex systems with sufficient accuracy. While various modern approaches have appeared, one very...
International Nuclear Information System (INIS)
Bonnal, J.-F.; Pelissier, Andre
1974-01-01
After a brief theoretical review, the relationship existing between the ionization rate in the vicinity of a metallic plate in thermodynamic equilibrium with a cesium plasma and the density of electron current issued from the same plate is presented. The evolution of this density of current is represented by the Langmuir S-curves. It is shown that knowledge of the S-curves leads to that of the critical temperatures and of the ionization rates when the generated ions are extracted by an electric field. The influence of the principal parameters (the nature and temperature of the plate and the cesium flow supplying it) is analyzed using the Rasor theory. The theoretical results obtained using a model of the flat plate represent fairly closely the operations observed experimentally on porous tungstem ionizers [fr
Holographic subregion complexity for singular surfaces
Energy Technology Data Exchange (ETDEWEB)
Bakhshaei, Elaheh [Isfahan University of Technology, Department of Physics, Isfahan (Iran, Islamic Republic of); Mollabashi, Ali [Institute for Research in Fundamental Sciences (IPM), School of Physics, Tehran (Iran, Islamic Republic of); Shirzad, Ahmad [Isfahan University of Technology, Department of Physics, Isfahan (Iran, Islamic Republic of); Institute for Research in Fundamental Sciences (IPM), School of Particles and Accelerators, Tehran (Iran, Islamic Republic of)
2017-10-15
Recently holographic prescriptions were proposed to compute the quantum complexity of a given state in the boundary theory. A specific proposal known as 'holographic subregion complexity' is supposed to calculate the complexity of a reduced density matrix corresponding to a static subregion. We study different families of singular subregions in the dual field theory and find the divergence structure and universal terms of holographic subregion complexity for these singular surfaces. We find that there are new universal terms, logarithmic in the UV cut-off, due to the singularities of a family of surfaces including a kink in (2 + 1) dimensions and cones in even dimensional field theories. We also find examples of new divergent terms such as squared logarithm and negative powers times the logarithm of the UV cut-off parameter. (orig.)
Complex multiplication of abelian surfaces
Streng, Theodorus Cornelis
2010-01-01
The theory of complex multiplication makes it possible to construct certain class fields and abelian varieties. The main theme of this thesis is making these constructions explicit for the case where the abelian varieties have dimension 2. Chapter I is an introduction to complex
Surface electrostatics: theory and computations
Chatzigeorgiou, G.
2014-02-05
The objective of this work is to study the electrostatic response of materials accounting for boundary surfaces with their own (electrostatic) constitutive behaviour. The electric response of materials with (electrostatic) energetic boundary surfaces (surfaces that possess material properties and constitutive structures different from those of the bulk) is formulated in a consistent manner using a variational framework. The forces and moments that appear due to bulk and surface electric fields are also expressed in a consistent manner. The theory is accompanied by numerical examples on porous materials using the finite-element method, where the influence of the surface electric permittivity on the electric displacement, the polarization stress and the Maxwell stress is examined.
Gauge theories, tessellations & Riemann surfaces
International Nuclear Information System (INIS)
He, Yang-Hui; Loon, Mark van
2014-01-01
We study and classify regular and semi-regular tessellations of Riemann surfaces of various genera and investigate their corresponding supersymmetric gauge theories. These tessellations are generalizations of brane tilings, or bipartite graphs on the torus as well as the Platonic and Archimedean solids on the sphere. On higher genus they give rise to intricate patterns. Special attention will be paid to the master space and the moduli space of vacua of the gauge theory and to how their geometry is determined by the tessellations.
Machining of Complex Sculptured Surfaces
2012-01-01
The machining of complex sculptured surfaces is a global technological topic in modern manufacturing with relevance in both industrialized and emerging in countries particularly within the moulds and dies sector whose applications include highly technological industries such as the automotive and aircraft industry. Machining of Complex Sculptured Surfaces considers new approaches to the manufacture of moulds and dies within these industries. The traditional technology employed in the manufacture of moulds and dies combined conventional milling and electro-discharge machining (EDM) but this has been replaced with high-speed milling (HSM) which has been applied in roughing, semi-finishing and finishing of moulds and dies with great success. Machining of Complex Sculptured Surfaces provides recent information on machining of complex sculptured surfaces including modern CAM systems and process planning for three and five axis machining as well as explanations of the advantages of HSM over traditional methods ra...
Kolmogorov Complexity Theory over the reals
Ziegler, M.; Koolen, W.M.
2008-01-01
Kolmogorov Complexity constitutes an integral part of computability theory, information theory, and computational complexity theory—in the discrete setting of bits and Turing machines. Over real numbers, on the other hand, the BSS-machine (aka real-RAM) has been established as a major model of
Introduction to complex theory of differential equations
Savin, Anton
2017-01-01
This book discusses the complex theory of differential equations or more precisely, the theory of differential equations on complex-analytic manifolds. Although the theory of differential equations on real manifolds is well known – it is described in thousands of papers and its usefulness requires no comments or explanations – to date specialists on differential equations have not focused on the complex theory of partial differential equations. However, as well as being remarkably beautiful, this theory can be used to solve a number of problems in real theory, for instance, the Poincaré balayage problem and the mother body problem in geophysics. The monograph does not require readers to be familiar with advanced notions in complex analysis, differential equations, or topology. With its numerous examples and exercises, it appeals to advanced undergraduate and graduate students, and also to researchers wanting to familiarize themselves with the subject.
Complexity measurement based on information theory and kolmogorov complexity.
Lui, Leong Ting; Terrazas, Germán; Zenil, Hector; Alexander, Cameron; Krasnogor, Natalio
2015-01-01
In the past decades many definitions of complexity have been proposed. Most of these definitions are based either on Shannon's information theory or on Kolmogorov complexity; these two are often compared, but very few studies integrate the two ideas. In this article we introduce a new measure of complexity that builds on both of these theories. As a demonstration of the concept, the technique is applied to elementary cellular automata and simulations of the self-organization of porphyrin molecules.
Circuit complexity in quantum field theory
Jefferson, Robert A.; Myers, Robert C.
2017-10-01
Motivated by recent studies of holographic complexity, we examine the question of circuit complexity in quantum field theory. We provide a quantum circuit model for the preparation of Gaussian states, in particular the ground state, in a free scalar field theory for general dimensions. Applying the geometric approach of Nielsen to this quantum circuit model, the complexity of the state becomes the length of the shortest geodesic in the space of circuits. We compare the complexity of the ground state of the free scalar field to the analogous results from holographic complexity, and find some surprising similarities.
Glass Durability Modeling, Activated Complex Theory (ACT)
International Nuclear Information System (INIS)
CAROL, JANTZEN
2005-01-01
atomic ratios is shown to represent the structural effects of the glass on the dissolution and the formation of activated complexes in the glass leached layer. This provides two different methods by which a linear glass durability model can be formulated. One based on the quasi- crystalline mineral species in a glass and one based on cation ratios in the glass: both are related to the activated complexes on the surface by the law of mass action. The former would allow a new Thermodynamic Hydration Energy Model to be developed based on the hydration of the quasi-crystalline mineral species if all the pertinent thermodynamic data were available. Since the pertinent thermodynamic data is not available, the quasi-crystalline mineral species and the activated complexes can be related to cation ratios in the glass by the law of mass action. The cation ratio model can, thus, be used by waste form producers to formulate durable glasses based on fundamental structural and activated complex theories. Moreover, glass durability model based on atomic ratios simplifies HLW glass process control in that the measured ratios of only a few waste components and glass formers can be used to predict complex HLW glass performance with a high degree of accuracy, e.g. an R 2 approximately 0.97
Minimal Model Theory for Log Surfaces
Fujino, Osamu
2012-01-01
We discuss the log minimal model theory for log surfaces. We show that the log minimal model program, the finite generation of log canonical rings, and the log abundance theorem for log surfaces hold true under assumptions weaker than the usual framework of the log minimal model theory.
Holographic complexity and noncommutative gauge theory
Couch, Josiah; Eccles, Stefan; Fischler, Willy; Xiao, Ming-Lei
2018-03-01
We study the holographic complexity of noncommutative field theories. The four-dimensional N=4 noncommutative super Yang-Mills theory with Moyal algebra along two of the spatial directions has a well known holographic dual as a type IIB supergravity theory with a stack of D3 branes and non-trivial NS-NS B fields. We start from this example and find that the late time holographic complexity growth rate, based on the "complexity equals action" conjecture, experiences an enhancement when the non-commutativity is turned on. This enhancement saturates a new limit which is exactly 1/4 larger than the commutative value. We then attempt to give a quantum mechanics explanation of the enhancement. Finite time behavior of the complexity growth rate is also studied. Inspired by the non-trivial result, we move on to more general setup in string theory where we have a stack of D p branes and also turn on the B field. Multiple noncommutative directions are considered in higher p cases.
Quantum theory in complex Hilbert space
International Nuclear Information System (INIS)
Sharma, C.S.
1988-01-01
The theory of complexification of a real Hilbert space as developed by the author is scrutinized with the aim of explaining why quantum theory should be done in a complex Hilbert space in preference to real Hilbert space. It is suggested that, in order to describe periodic motions in stationary states of a quantum system, the mathematical object modelling a state of a system should have enough points in it to be able to describe explicit time dependence of a periodic motion without affecting the probability distributions of observables. Heuristic evidence for such an assumption comes from Dirac's theory of interaction between radiation and matter. If the assumption is adopted as a requirement on the mathematical model for a quantum system, then a real Hilbert space is ruled out in favour of a complex Hilbert space for a possible model for such a system
Towards an Information Theory of Complex Networks
Dehmer, Matthias; Mehler, Alexander
2011-01-01
For over a decade, complex networks have steadily grown as an important tool across a broad array of academic disciplines, with applications ranging from physics to social media. A tightly organized collection of carefully-selected papers on the subject, Towards an Information Theory of Complex Networks: Statistical Methods and Applications presents theoretical and practical results about information-theoretic and statistical models of complex networks in the natural sciences and humanities. The book's major goal is to advocate and promote a combination of graph-theoretic, information-theoreti
Momentum and hamiltonian in complex action theory
DEFF Research Database (Denmark)
Nagao, Keiichi; Nielsen, Holger Frits Bech
2012-01-01
In the complex action theory (CAT) we explicitly examine how the momentum and Hamiltonian are defined from the Feynman path integral (FPI) point of view. In arXiv:1104.3381[quant-ph], introducing a philosophy to keep the analyticity in parameter variables of FPI and defining a modified set...... of complex conjugate, hermitian conjugates and bras, we have extended $| q >$ and $| p >$ to complex $q$ and $p$ so that we can deal with a complex coordinate $q$ and a complex momentum $p$. After reviewing them briefly, we describe in terms of the newly introduced devices the time development of a $\\xi......$-parametrized wave function, which is a solution to an eigenvalue problem of a momentum operator $\\hat{p}$, in FPI with a starting Lagrangian. Solving the eigenvalue problem, we derive the momentum and Hamiltonian. Oppositely, starting from the Hamiltonian we derive the Lagrangian in FPI, and we are led...
Complex Decision Making Theory and Practice
Qudrat-Ullah, Hassan; Spector, J Michael
2007-01-01
The increasingly complex environment of today's world, characterized by technological innovation and global communication, generates myriads of possible and actual interactions while limited physical and intellectual resources severely impinge on decision makers, be it in the public or private domains. At the core of the decision-making process is the need for quality information that allows the decision maker to better assess the impact of decisions in terms of outcomes, nonlinear feedback processes and time delays on the performance of the complex system invoked. This volume is a timely review on the principles underlying complex decision making, the handling of uncertainties in dynamic envrionments and of the various modeling approaches used. The book consists of five parts, each composed of several chapters: I: Complex Decision Making: Concepts, Theories and Empirical Evidence II: Tools and Techniques for Decision Making in Complex Environments and Systems III: System Dynamics and Agent-Based Modeling IV:...
Function theory of several complex variables
Krantz, Steven G
2001-01-01
The theory of several complex variables can be studied from several different perspectives. In this book, Steven Krantz approaches the subject from the point of view of a classical analyst, emphasizing its function-theoretic aspects. He has taken particular care to write the book with the student in mind, with uniformly extensive and helpful explanations, numerous examples, and plentiful exercises of varying difficulty. In the spirit of a student-oriented text, Krantz begins with an introduction to the subject, including an insightful comparison of analysis of several complex variables with th
Riemann surfaces with boundaries and string theory
International Nuclear Information System (INIS)
Morozov, A.Yu.; Roslyj, A.A.
1989-01-01
A consideration of the cutting and joining operations for Riemann surfaces permits one to express the functional integral on a Riemann surface in terms of integrals over its pieces which are suarfaces with boundaries. This yields an expression for the determinant of the Laplacian on a Riemann surface in terms of Krichever maps for its pieces. Possible applications of the methods proposed to a study of the string perturbation theory in terms of an universal moduli space are mentioned
Computational Complexity of Combinatorial Surfaces
Vegter, Gert; Yap, Chee K.
1990-01-01
We investigate the computational problems associated with combinatorial surfaces. Specifically, we present an algorithm (based on the Brahana-Dehn-Heegaard approach) for transforming the polygonal schema of a closed triangulated surface into its canonical form in O(n log n) time, where n is the
Topics in the theory of Riemann surfaces
Accola, Robert D M
1994-01-01
The book's main concern is automorphisms of Riemann surfaces, giving a foundational treatment from the point of view of Galois coverings, and treating the problem of the largest automorphism group for a Riemann surface of a given genus. In addition, the extent to which fixed points of automorphisms are generalized Weierstrass points is considered. The extremely useful inequality of Castelnuovo- Severi is also treated. While the methods are elementary, much of the material does not appear in the current texts on Riemann surfaces, algebraic curves. The book is accessible to a reader who has had an introductory course on the theory of Riemann surfaces or algebraic curves.
A complexity theory based on Boolean algebra
DEFF Research Database (Denmark)
Skyum, Sven; Valiant, Leslie
1985-01-01
A projection of a Boolean function is a function obtained by substituting for each of its variables a variable, the negation of a variable, or a constant. Reducibilities among computational problems under this relation of projection are considered. It is shown that much of what is of everyday rel...... relevance in Turing-machine-based complexity theory can be replicated easily and naturally in this elementary framework. Finer distinctions about the computational relationships among natural problems can be made than in previous formulations and some negative results are proved....
Complex Systems: An Introduction-Information Theory, Chaos ...
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 14; Issue 8. Complex Systems: An Introduction - Information Theory, Chaos Theory and Computational Complexity. V K Wadhawan. General Article Volume 14 Issue 8 August 2009 pp 761-781 ...
BRST quantization of superconformal theories on higher genus Riemann surfaces
International Nuclear Information System (INIS)
Leman Kuang
1992-01-01
A complex contour integral method is constructed and applied to the Becchi-Rouet-Stora-Tyutin (BRST) quantization procedure of string theories on higher genus Riemann surfaces with N=0 and 1 Krichever-Novikov (KN) algebras. This method makes calculations very simple. It is shown that the critical spacetime dimension of the string theories on a genus-g Riemann surface equals that of the string theories on a genus-zero Riemann surface, and that the 'Regge intercepts' in the genus-g case are α(g)=1-3/4g-9/8g 2 and 1/2-3/4g-17/16g 2 for bosonic strings and superstrings, respectively. (orig.)
Theories and simulations of complex social systems
Mago, Vijay
2014-01-01
Research into social systems is challenging due to their complex nature. Traditional methods of analysis are often difficult to apply effectively as theories evolve over time. This can be due to a lack of appropriate data, or too much uncertainty. It can also be the result of problems which are not yet understood well enough in the general sense so that they can be classified, and an appropriate solution quickly identified. Simulation is one tool that deals well with these challenges, fits in well with the deductive process, and is useful for testing theory. This field is still relatively new, and much of the work is necessarily innovative, although it builds upon a rich and varied foundation. There are a number of existing modelling paradigms being applied to complex social systems research. Additionally, new methods and measures are being devised through the process of conducting research. We expect that readers will enjoy the collection of high quality research works from new and accomplished researchers. ...
Theory of magnetism application to surface physics
Diep, Hung T
2014-01-01
The book is intended for graduate students and researchers who wish to master the main properties of magnetic materials in the bulk state and at the nanometric scale such as for thin films and multilayers. This textbook provides the theories and methods of simulation to study and to understand these properties in an explicit manner. In the first part of the book, the quantum theory of magnetism is presented while the second part of the book is devoted to the application of the theory of magnetism to surface physics. Numerous examples covering typical cases in ferromagnets, antiferromagnets, ferrimagnets, helimagnets, and frustrated spin systems are all illustrated. Fundamental surface effects are shown and discussed. Lastly, the spin transport is described — in which the basic formulation of the Boltzmann's equation is recalled — and the recent methods of Monte Carlo simulation to deal with the spin resistivity are explained. This book contains a large number of detailed solutions for the problems given ...
Marked fatgraph complexes and surface automorphisms
DEFF Research Database (Denmark)
Kuno, Yusuke; Penner, Robert; Turaev, Vladimir
2013-01-01
Combinatorial aspects of the Torelli-Johnson-Morita theory of surface automorphisms are extended to certain subgroups of the mapping class groups. These subgroups are defined relative to a specified homomorphism from the fundamental group of the surface onto an arbitrary group $K$. For $K$ abelia...
Nodal aberration theory applied to freeform surfaces
Fuerschbach, Kyle; Rolland, Jannick P.; Thompson, Kevin P.
2014-12-01
When new three-dimensional packages are developed for imaging optical systems, the rotational symmetry of the optical system is often broken, changing its imaging behavior and making the optical performance worse. A method to restore the performance is to use freeform optical surfaces that compensate directly the aberrations introduced from tilting and decentering the optical surfaces. In order to effectively optimize the shape of a freeform surface to restore optical functionality, it is helpful to understand the aberration effect the surface may induce. Using nodal aberration theory the aberration fields induced by a freeform surface in an optical system are explored. These theoretical predications are experimentally validated with the design and implementation of an aberration generating telescope.
Enumeration of RNA complexes via random matrix theory.
Andersen, Jørgen E; Chekhov, Leonid O; Penner, Robert C; Reidys, Christian M; Sułkowski, Piotr
2013-04-01
In the present article, we review a derivation of the numbers of RNA complexes of an arbitrary topology. These numbers are encoded in the free energy of the Hermitian matrix model with potential V(x)=x2/2-stx/(1-tx), where s and t are respective generating parameters for the number of RNA molecules and hydrogen bonds in a given complex. The free energies of this matrix model are computed using the so-called topological recursion, which is a powerful new formalism arising from random matrix theory. These numbers of RNA complexes also have profound meaning in mathematics: they provide the number of chord diagrams of fixed genus with specified numbers of backbones and chords as well as the number of cells in Riemann's moduli spaces for bordered surfaces of fixed topological type.
Enumeration of RNA complexes via random matrix theory
DEFF Research Database (Denmark)
Andersen, Jørgen E; Chekhov, Leonid O.; Penner, Robert C
2013-01-01
molecules and hydrogen bonds in a given complex. The free energies of this matrix model are computed using the so-called topological recursion, which is a powerful new formalism arising from random matrix theory. These numbers of RNA complexes also have profound meaning in mathematics: they provide......In the present article, we review a derivation of the numbers of RNA complexes of an arbitrary topology. These numbers are encoded in the free energy of the Hermitian matrix model with potential V(x)=x(2)/2 - stx/(1 - tx), where s and t are respective generating parameters for the number of RNA...... the number of chord diagrams of fixed genus with specified numbers of backbones and chords as well as the number of cells in Riemann's moduli spaces for bordered surfaces of fixed topological type....
On P vs. NP, Geometric Complexity Theory, Explicit Proofs and the Complexity Barrier
Mulmuley, Ketan D.
2009-01-01
Geometric complexity theory (GCT) is an approach to the P vs. NP and related problems. This article gives its complexity theoretic overview without assuming any background in algebraic geometry or representation theory.
A nucleation theory of cell surface capping
International Nuclear Information System (INIS)
Coutsias, E.A.; Wester, M.J.; Perelson, A.S.
1997-01-01
We propose a new theory of cell surface capping based on the principles of nucleation. When antibody interacts with cell surface molecules, the molecules initially form small aggregates called patches that later coalesce into a large aggregate called a cap. While a cap can form by patches being pulled together by action of the cell''s cytoskeleton, in the case of some molecules, disruption of the cytoskeleton does not prevent cap formation. Diffusion of large aggregates on a cell surface is slow, and thus we propose that a cap can form solely through the diffusion of small aggregates containing just one or a few cell surface molecules. Here we consider the extreme case in which single molecules are mobile, but aggregates of all larger sizes are immobile. We show that a set of patches in equilibrium with a open-quotes seaclose quotes of free cell surface molecules can undergo a nucleation-type phase transition in which the largest patch will bind free cell surface molecules, deplete the concentration of such molecules in the open-quotes seaclose quotes and thus cause the other patches to shrink in size. We therefore show that a cap can form without patches having to move, collide with each other, and aggregate
Electrodynamics as a theory of interacting complex charges
International Nuclear Information System (INIS)
Akeyo Omolo, Joseph
2003-04-01
In this paper, we formulate a general theory of electrodynamics which incorporates both electric and magnetic charges. The mathematical origin of a second vector potential and magnetic charge is established. Electrodynamics is then reformulated in complex form as a theory of complex charges moving in a complex force field. This provides the framework for complex charged particle interactions as a generalization of Schwinger's theory of dyon-dyon interactions. The concept of duality transformation relating electric and magnetic charge spaces is developed within the general framework of electrodynamics in complex form. (author)
Surface complexation of antimony on kaolinite.
Rakshit, Sudipta; Sarkar, Dibyendu; Datta, Rupali
2015-01-01
Geochemical fate of antimony (Sb) - a similar oxyanion as arsenic (As) - in a variety of environment is largely unexplored. Kaolinite is an important, naturally occurring clay mineral in soils and aquifers and is known to control the fate of several contaminants via a multitude of geochemical processes, primarily adsorption. Here we report adsorption of antimony on kaolinite as a function of solution chemistry: initial antimony concentration, pH, ionic strength, and a competing anion. A surface complexation modeling (SCM) approach was undertaken to understand the potential mechanistic implications of sorption envelope data. In the SCM, a multicomponent additive approach, in which kaolinite is assumed to be a (1:1) mixture of quartz (≡SiOH) and gibbsite (≡AlOH), was tested. Results indicated that ionic strength has a minimal effect on antimony adsorption. For the lower initial antimony concentration (4.11 μM), the additive model with binuclear surface complexes on quartz and gibbsite showed a better fit at pH3.5. However, the additive model with binuclear surface complex on quartz and mononuclear surface complex on gibbsite showed an excellent fit of the data. Phosphate greatly influenced antimony adsorption on kaolinite at both low and high antimony loadings, indicating competition for available surface sites. Copyright © 2014 Elsevier Ltd. All rights reserved.
Antimonene: Experiments and theory of surface conductivity
Palacios, Juan Jose; Ares, Pablo; Pakdel, Sahar; Paz, Wendel; Zamora, Felix; Gomez-Herrero, Julio
Very recently antimony has been demonstrated to be amenable to standard exfoliation procedures opening the possibility of studying the electronic properties of isolated few-layers flakes of this material, a.k.a. antimonene. Antimony is a topological semimetal, meaning that its electronic structure presents spin-split helical states (or Dirac cones) on the surface, but it is still trivially metallic in bulk. Antimonene, on the other hand, may present a much reduced electronic bulk contribution for a small number of layers. A novel technique to make electrical contacts on the surface of individual thin flakes (5-10 monolayers) has allowed us to measure the (surface) conductivity of these in ambient conditions. Our measurements show a high conductivity in the range of 1 - 2e2 / h , which we attribute to the surface Dirac electrons. We have also carried out theoretical work to address the origin of this value, in particular, the importance of scattering between the Dirac electrons and the bulk bands. Our calculations are based on density functional theory for the electronic structure and Kubo formalism for the conductivity, the latter considering random disorder and the presence of water. Ministerio de Economia y Competitividad, Grant FIS2016-80434-P.
Formulation and applications of complex network theory
Park, Juyong
In recent years, there has been a great surge of interest among physicists in modeling social, technological, or biological systems as networks. Analyses of large-scale networks such as the Internet have led to discoveries of many unexpected network properties, including power-law degree distributions. These discoveries have prompted physicists to devise novel ways to model networks, both computational and theoretical. In this dissertation, we present several network models and their applications. First, we study the theory of Exponential Random Graphs. We derive it from the principle of maximum entropy, thereby showing that it is the equivalent of the Gibbs ensemble for networks. Using tools of statistical physics, we solve well-known and new examples that include power-law networks and the two-star model. Our solutions confirm the existence of a first-order phase transition for the latter whose exact behavior has not been presented previously. We also study degree correlations and clustering in networks. Degrees of adjacent vertices are positively correlated in social networks, whereas they are negatively correlated in other types of networks. We demonstrate that a negative degree correlation is a more natural state of a network, and therefore that social networks are an exception. We argue that variations in the number of vertices in social groups cause positive degree correlations, and analyze a model that incorporates such a mechanism. The model indeed shows a high level of degree correlation and clustering that is similar in value to those of real networks. Finally, we develop algorithms for ranking vertices in networks that represent pairwise comparisons. The first algorithm is based on the familiar concept of indirect wins and losses. The second algorithm is based on the concept of retrodictive accuracy, which is maximized by positioning as many winners above the losers as possible. We compare the rankings of American college football teams generated by our
Applying complexity theory: a review to inform evaluation design.
Walton, Mat
2014-08-01
Complexity theory has increasingly been discussed and applied within evaluation literature over the past decade. This article reviews the discussion and use of complexity theory within academic journal literature. The aim is to identify the issues to be considered when applying complexity theory to evaluation. Reviewing 46 articles, two groups of themes are identified. The first group considers implications of applying complexity theory concepts for defining evaluation purpose, scope and units of analysis. The second group of themes consider methodology and method. Results provide a starting point for a configuration of an evaluation approach consistent with complexity theory, whilst also identifying a number of design considerations to be resolved within evaluation planning. Copyright © 2014 Elsevier Ltd. All rights reserved.
Surface-complexation models for sorption onto heterogeneous surfaces
International Nuclear Information System (INIS)
Harvey, K.B.
1997-10-01
This report provides a description of the discrete-logK spectrum model, together with a description of its derivation, and of its place in the larger context of surface-complexation modelling. The tools necessary to apply the discrete-logK spectrum model are discussed, and background information appropriate to this discussion is supplied as appendices. (author)
Luo, Yuan; Tan, Meng-Chwan; Vasko, Petr; Zhao, Qin
2017-05-01
We perform a series of dimensional reductions of the 6d, \\mathcal{N} = (2, 0) SCFT on S 2 × Σ × I × S 1 down to 2d on Σ. The reductions are performed in three steps: (i) a reduction on S 1 (accompanied by a topological twist along Σ) leading to a supersymmetric Yang-Mills theory on S 2 × Σ × I, (ii) a further reduction on S 2 resulting in a complex Chern-Simons theory defined on Σ × I, with the real part of the complex Chern-Simons level being zero, and the imaginary part being proportional to the ratio of the radii of S 2 and S 1, and (iii) a final reduction to the boundary modes of complex Chern-Simons theory with the Nahm pole boundary condition at both ends of the interval I, which gives rise to a complex Toda CFT on the Riemann surface Σ. As the reduction of the 6d theory on Σ would give rise to an \\mathcal{N} = 2 supersymmetric theory on S 2 × I × S 1, our results imply a 4d-2d duality between four-dimensional \\mathcal{N} = 2 supersymmetric theory with boundary and two-dimensional complex Toda theory.
Complex analysis a modern first course in function theory
Muir, Jerry R
2015-01-01
A thorough introduction to the theory of complex functions emphasizing the beauty, power, and counterintuitive nature of the subject Written with a reader-friendly approach, Complex Analysis: A Modern First Course in Function Theory features a self-contained, concise development of the fundamental principles of complex analysis. After laying groundwork on complex numbers and the calculus and geometric mapping properties of functions of a complex variable, the author uses power series as a unifying theme to define and study the many rich and occasionally surprising properties of analytic fun
Instruction sequences and non-uniform complexity theory
Bergstra, J.A.; Middelburg, C.A.
2008-01-01
We develop theory concerning non-uniform complexity in a setting in which the notion of single-pass instruction sequence considered in program algebra is the central notion. We define counterparts of the complexity classes P/poly and NP/poly and formulate a counterpart of the complexity theoretic
Constructivist learning theories and complex learning environments
R-J. Simons; Dr. S. Bolhuis
2004-01-01
Learning theories broadly characterised as constructivist, agree on the importance to learning of the environment, but differ on what exactly it is that constitutes this importance. Accordingly, they also differ on the educational consequences to be drawn from the theoretical perspective. Cognitive
The adjunction theory of complex projective varieties
Sommese, Andrew J
1995-01-01
An overview of developments in the past 15 years of adjunction theory, the study of the interplay between the intrinsic geometry of a projective variety and the geometry connected with some embedding of the variety into a projective space. Topics include consequences of positivity, the Hilbert schem
COMPLEX SURFACE HARDENING OF STEEL ARTICLES
Directory of Open Access Journals (Sweden)
A. V. Kovalchuk
2014-01-01
Full Text Available The method of complex surface hardening of steel detailswas designed. The method is a compound of two processes of hardening: chemical heat treatment and physical vapor deposition (PVD of the coating. The result, achieved in this study is much higher, than in other work on this topic and is cumulative. The method designed can be used in mechanical engineering, medicine, energetics and is perspective for military and space technologies.
Surface field theories of point group symmetry protected topological phases
Huang, Sheng-Jie; Hermele, Michael
2018-02-01
We identify field theories that describe the surfaces of three-dimensional bosonic point group symmetry protected topological (pgSPT) phases. The anomalous nature of the surface field theories is revealed via a dimensional reduction argument. Specifically, we study three different surface field theories. The first field theory is quantum electrodynamics in three space-time dimensions (QED3) with four flavors of fermions. We show this theory can describe the surfaces of a majority of bosonic pgSPT phases protected by a single mirror reflection, or by Cn v point group symmetry for n =2 ,3 ,4 ,6 . The second field theory is a variant of QED3 with charge-1 and charge-3 Dirac fermions. This field theory can describe the surface of a reflection symmetric pgSPT phase built by placing an E8 state on the mirror plane. The third field theory is an O (4 ) nonlinear sigma model with a topological theta term at θ =π , or, equivalently, a noncompact CP1 model. Using a coupled wire construction, we show this is a surface theory for bosonic pgSPT phases with U (1 ) ×Z2P symmetry. For the latter two field theories, we discuss the connection to gapped surfaces with topological order. Moreover, we conjecture that the latter two field theories can describe surfaces of more general bosonic pgSPT phases with Cn v point group symmetry.
Structure, Agency, Complexity Theory and Interdisciplinary Research in Education Studies
Smith, John A.
2013-01-01
This article argues that Education Studies needs to develop its existing interdisciplinarity understanding of structures and agencies by giving greater attention to the modern process theories of self-organisation in the physical, biological, psychological and social sciences, sometimes given the umbrella term "complexity theory". The…
A scrapbook of complex curve theory
Clemens, C Herbert
1980-01-01
This is a book of "impressions" of a journey through the theory of com plex algebraic curves. It is neither self-contained, balanced, nor particularly tightly organized. As with any notebook made on a journey, what appears is that which strikes the writer's fancy. Some topics appear because of their compelling intrinsic beauty. Others are left out because, for all their impor tance, the traveler found them boring or was too dull or lazy to give them their due. Looking back at the end of the journey, one can see that a common theme in fact does emerge, as is so often the case; that theme is the theory of theta functions. In fact very much of the material in the book is prepara tion for our study of the final topic, the so-called Schottky problem. More than once, in fact, we tear ourselves away from interesting topics leading elsewhere and return to our main route.
Complexity Theory and CALL Curriculum in Foreign Language Learning
Directory of Open Access Journals (Sweden)
Hassan Soleimani
2014-05-01
Full Text Available Complexity theory literally indicates the complexity of a system, behavior, or a process. Its connotative meaning, while, implies dynamism, openness, sensitivity to initial conditions and feedback, and adaptation properties of a system. Regarding English as a Foreign/ Second Language (EFL/ESL this theory emphasizes on the complexity of the process of teaching and learning, including all the properties of a complex system. The purpose of the current study is to discuss the role of CALL as a modern technology in simplifying the process of teaching and learning a new language while integrating into the complexity theory. Nonetheless, the findings obtained from reviewing previously conducted studies in this field confirmed the usefulness of CALL curriculum in EFL/ESL contexts. These findings can also provide pedagogical implications for employing computer as an effective teaching and learning tool.
Ecosystemic Complexity Theory of Conflict: Understanding the Fog of Conflict
Brack, Greg; Lassiter, Pamela S.; Hill, Michele B.; Moore, Sarah A.
2011-01-01
Counselors often engage in conflict mediation in professional practice. A model for understanding the complex and subtle nature of conflict resolution is presented. The ecosystemic complexity theory of conflict is offered to assist practitioners in navigating the fog of conflict. Theoretical assumptions are discussed with implications for clinical…
Time evolution of complexity in Abelian gauge theories
Hashimoto, Koji; Iizuka, Norihiro; Sugishita, Sotaro
2017-12-01
Quantum complexity is conjectured to probe inside of black hole horizons (or wormholes) via gauge gravity correspondence. In order to have a better understanding of this correspondence, we study time evolutions of complexities for Abelian pure gauge theories. For this purpose, we discretize the U (1 ) gauge group as ZN and also the continuum spacetime as lattice spacetime, and this enables us to define a universal gate set for these gauge theories and to evaluate time evolutions of the complexities explicitly. We find that to achieve a large complexity ˜exp (entropy), which is one of the conjectured criteria necessary to have a dual black hole, the Abelian gauge theory needs to be maximally nonlocal.
Complexity of visual icons studied via signal detection theory.
Repperger, Daniel W; Aleva, Denise L; Thomas, Gina; Miller, Janet E; Fullenkamp, Stephen C
2007-08-01
Two investigations on how humans perceive information from visually rendered complex objects, such as military icons (glyphs) were conducted. A signal detection theory framework was employed to evaluate the sensitivity and specificity of human subject performance. The 6 adults tested showed that as complexity increased, their accuracy in performance decreased. Study 1 showed that complex dimensions (features) could not be assigned arbitrarily. Study 2 developed a rank ordering for features of an iconic object.
Theory and experiments on surface diffusion
Energy Technology Data Exchange (ETDEWEB)
Silvestri, W.L.
1998-11-01
The following topics were dealt with: adatom formation and self-diffusion on the Ni(100) surface, helium atom scattering measurements, surface-diffusion parameter measurements, embedded atom method calculations.
Representations of Complexity: How Nature Appears in Our Theories.
McDowell, J J
2013-01-01
In science we study processes in the material world. The way these processes operate can be discovered by conducting experiments that activate them, and findings from such experiments can lead to functional complexity theories of how the material processes work. The results of a good functional theory will agree with experimental measurements, but the theory may not incorporate in its algorithmic workings a representation of the material processes themselves. Nevertheless, the algorithmic operation of a good functional theory may be said to make contact with material reality by incorporating the emergent computations the material processes carry out. These points are illustrated in the experimental analysis of behavior by considering an evolutionary theory of behavior dynamics, the algorithmic operation of which does not correspond to material features of the physical world, but the functional output of which agrees quantitatively and qualitatively with findings from a large body of research with live organisms.
Energy-momentum complex in Moeller's tetrad theory of gravitation
International Nuclear Information System (INIS)
Mikhail, F.I.; Lashin, E.I.
1991-08-01
Moeller's tetrad theory of gravitation is examined with regard to the energy-momentum complex. The energy-momentum complex as well as the superpotential associated with Moeller's theory are derived. Moeller's field equations are solved in the case of ''general'' spherical symmetry. Two different solutions, giving rise to the same metric, are obtained. The energy associated with one solution is found to be twice the energy associated with the other. An avenue out of this inconsistency is suggested. (author). 20 refs, 1 tab
Nodal surface semimetals: Theory and material realization
Wu, Weikang; Liu, Ying; Li, Si; Zhong, Chengyong; Yu, Zhi-Ming; Sheng, Xian-Lei; Zhao, Y. X.; Yang, Shengyuan A.
2018-03-01
We theoretically study the three-dimensional topological semimetals with nodal surfaces protected by crystalline symmetries. Different from the well-known nodal-point and nodal-line semimetals, in these materials, the conduction and valence bands cross on closed nodal surfaces in the Brillouin zone. We propose different classes of nodal surfaces, both in the absence and in the presence of spin-orbit coupling (SOC). In the absence of SOC, a class of nodal surfaces can be protected by space-time inversion symmetry and sublattice symmetry and characterized by a Z2 index, while another class of nodal surfaces are guaranteed by a combination of nonsymmorphic twofold screw-rotational symmetry and time-reversal symmetry. We show that the inclusion of SOC will destroy the former class of nodal surfaces but may preserve the latter provided that the inversion symmetry is broken. We further generalize the result to magnetically ordered systems and show that protected nodal surfaces can also exist in magnetic materials without and with SOC, given that certain magnetic group symmetry requirements are satisfied. Several concrete nodal-surface material examples are predicted via the first-principles calculations. The possibility of multi-nodal-surface materials is discussed.
Methods of information theory and algorithmic complexity for network biology.
Zenil, Hector; Kiani, Narsis A; Tegnér, Jesper
2016-03-01
We survey and introduce concepts and tools located at the intersection of information theory and network biology. We show that Shannon's information entropy, compressibility and algorithmic complexity quantify different local and global aspects of synthetic and biological data. We show examples such as the emergence of giant components in Erdös-Rényi random graphs, and the recovery of topological properties from numerical kinetic properties simulating gene expression data. We provide exact theoretical calculations, numerical approximations and error estimations of entropy, algorithmic probability and Kolmogorov complexity for different types of graphs, characterizing their variant and invariant properties. We introduce formal definitions of complexity for both labeled and unlabeled graphs and prove that the Kolmogorov complexity of a labeled graph is a good approximation of its unlabeled Kolmogorov complexity and thus a robust definition of graph complexity. Copyright © 2016 Elsevier Ltd. All rights reserved.
Classical theory of atom-surface scattering: The rainbow effect
Miret-Artés, Salvador; Pollak, Eli
2012-07-01
The scattering of heavy atoms and molecules from surfaces is oftentimes dominated by classical mechanics. A large body of experiments have gathered data on the angular distributions of the scattered species, their energy loss distribution, sticking probability, dependence on surface temperature and more. For many years these phenomena have been considered theoretically in the framework of the “washboard model” in which the interaction of the incident particle with the surface is described in terms of hard wall potentials. Although this class of models has helped in elucidating some of the features it left open many questions such as: true potentials are clearly not hard wall potentials, it does not provide a realistic framework for phonon scattering, and it cannot explain the incident angle and incident energy dependence of rainbow scattering, nor can it provide a consistent theory for sticking. In recent years we have been developing a classical perturbation theory approach which has provided new insight into the dynamics of atom-surface scattering. The theory includes both surface corrugation as well as interaction with surface phonons in terms of harmonic baths which are linearly coupled to the system coordinates. This model has been successful in elucidating many new features of rainbow scattering in terms of frictions and bath fluctuations or noise. It has also given new insight into the origins of asymmetry in atomic scattering from surfaces. New phenomena deduced from the theory include friction induced rainbows, energy loss rainbows, a theory of super-rainbows, and more. In this review we present the classical theory of atom-surface scattering as well as extensions and implications for semiclassical scattering and the further development of a quantum theory of surface scattering. Special emphasis is given to the inversion of scattering data into information on the particle-surface interactions.
Graphs on Surfaces and the Partition Function of String Theory
Garcia-Islas, J. Manuel
2007-01-01
Graphs on surfaces is an active topic of pure mathematics belonging to graph theory. It has also been applied to physics and relates discrete and continuous mathematics. In this paper we present a formal mathematical description of the relation between graph theory and the mathematical physics of discrete string theory. In this description we present problems of the combinatorial world of real importance for graph theorists. The mathematical details of the paper are as follows: There is a com...
On the invariant theory of Weingarten surfaces in Euclidean space
International Nuclear Information System (INIS)
Ganchev, Georgi; Mihova, Vesselka
2010-01-01
On any Weingarten surface in Euclidean space (strongly regular or rotational), we introduce locally geometric principal parameters and prove that such a surface is determined uniquely up to a motion by a special invariant function, which satisfies a natural nonlinear partial differential equation. This result can be interpreted as a solution to the Lund-Regge reduction problem for Weingarten surfaces in Euclidean space. We apply this theory to fractional-linear Weingarten surfaces and obtain the nonlinear partial differential equations describing them.
Geometric invariant theory over the real and complex numbers
Wallach, Nolan R
2017-01-01
Geometric Invariant Theory (GIT) is developed in this text within the context of algebraic geometry over the real and complex numbers. This sophisticated topic is elegantly presented with enough background theory included to make the text accessible to advanced graduate students in mathematics and physics with diverse backgrounds in algebraic and differential geometry. Throughout the book, examples are emphasized. Exercises add to the reader’s understanding of the material; most are enhanced with hints. The exposition is divided into two parts. The first part, ‘Background Theory’, is organized as a reference for the rest of the book. It contains two chapters developing material in complex and real algebraic geometry and algebraic groups that are difficult to find in the literature. Chapter 1 emphasizes the relationship between the Zariski topology and the canonical Hausdorff topology of an algebraic variety over the complex numbers. Chapter 2 develops the interaction between Lie groups and algebraic ...
Complex Time-Delay Systems Theory and Applications
Atay, Fatihcan M
2010-01-01
Time delays in dynamical systems arise as an inevitable consequence of finite speeds of information transmission. Realistic models increasingly demand the inclusion of delays in order to properly understand, analyze, design, and control real-life systems. The goal of this book is to present the state-of-the-art in research on time-delay dynamics in the framework of complex systems and networks. While the mathematical theory of delay equations is quite mature, its application to the particular problems of complex systems and complexity is a newly emerging field, and the present volume aims to play a pioneering role in this perspective. The chapters in this volume are authored by renowned experts and cover both theory and applications in a wide range of fields, with examples extending from neuroscience and biology to laser physics and vehicle traffic. Furthermore, all chapters include sufficient introductory material and extensive bibliographies, making the book a self-contained reference for both students and ...
Surface effect theory in binary alloys: surfaces with cut-off
International Nuclear Information System (INIS)
Kumar, V.; Silva, C.E.T.G. da; Moran-Lopez, J.L.
1981-01-01
A surface effect theory in binary alloys which ore ordered with surfaces with cut-off is presented. This theory is based in a model of pair interaction between first neighbours and includes long and short range effects. The (120) surface with sup(-) (110) monoatomic cut-off and terrace in the (110) planes of an alloy with body centered cubic structure is presented as example. Results for the concentrations in all the different surface sites are given. (L.C.) [pt
A curvature theory for discrete surfaces based on mesh parallelity
Bobenko, Alexander Ivanovich
2009-12-18
We consider a general theory of curvatures of discrete surfaces equipped with edgewise parallel Gauss images, and where mean and Gaussian curvatures of faces are derived from the faces\\' areas and mixed areas. Remarkably these notions are capable of unifying notable previously defined classes of surfaces, such as discrete isothermic minimal surfaces and surfaces of constant mean curvature. We discuss various types of natural Gauss images, the existence of principal curvatures, constant curvature surfaces, Christoffel duality, Koenigs nets, contact element nets, s-isothermic nets, and interesting special cases such as discrete Delaunay surfaces derived from elliptic billiards. © 2009 Springer-Verlag.
Linear response theory of activated surface diffusion with interacting adsorbates
Energy Technology Data Exchange (ETDEWEB)
Marti' nez-Casado, R. [Department of Chemistry, Imperial College London, South Kensington, London SW7 2AZ (United Kingdom); Sanz, A.S.; Vega, J.L. [Instituto de Fi' sica Fundamental, Consejo Superior de Investigaciones Cientificas, Serrano 123, 28006 Madrid (Spain); Rojas-Lorenzo, G. [Instituto Superior de Tecnologi' as y Ciencias Aplicadas, Ave. Salvador Allende, esq. Luaces, 10400 La Habana (Cuba); Instituto de Fi' sica Fundamental, Consejo Superior de Investigaciones Cienti' ficas, Serrano 123, 28006 Madrid (Spain); Miret-Artes, S., E-mail: s.miret@imaff.cfmac.csic.es [Instituto de Fi' sica Fundamental, Consejo Superior de Investigaciones Cienti' ficas, Serrano 123, 28006 Madrid (Spain)
2010-05-12
Graphical abstract: Activated surface diffusion with interacting adsorbates is analyzed within the Linear Response Theory framework. The so-called interacting single adsorbate model is justified by means of a two-bath model, where one harmonic bath takes into account the interaction with the surface phonons, while the other one describes the surface coverage, this leading to defining a collisional friction. Here, the corresponding theory is applied to simple systems, such as diffusion on flat surfaces and the frustrated translational motion in a harmonic potential. Classical and quantum closed formulas are obtained. Furthermore, a more realistic problem, such as atomic Na diffusion on the corrugated Cu(0 0 1) surface, is presented and discussed within the classical context as well as within the framework of Kramer's theory. Quantum corrections to the classical results are also analyzed and discussed. - Abstract: Activated surface diffusion with interacting adsorbates is analyzed within the Linear Response Theory framework. The so-called interacting single adsorbate model is justified by means of a two-bath model, where one harmonic bath takes into account the interaction with the surface phonons, while the other one describes the surface coverage, this leading to defining a collisional friction. Here, the corresponding theory is applied to simple systems, such as diffusion on flat surfaces and the frustrated translational motion in a harmonic potential. Classical and quantum closed formulas are obtained. Furthermore, a more realistic problem, such as atomic Na diffusion on the corrugated Cu(0 0 1) surface, is presented and discussed within the classical context as well as within the framework of Kramer's theory. Quantum corrections to the classical results are also analyzed and discussed.
Some Basic Information on Information-Based Complexity Theory
1989-07-01
field. Another way to model some aspects of scientific computing was intro- duced in 1988 by L. Blum , M. Shub and S. Smale, [B1,Sh&Sm,1988]; Algebraic...331-346. [BI,Shu,&Sm,1988] Blum L., Shub M., Smale S., On a Theory of Computation over the Real Numbers; NP Completness, Recursive Functions, and Turing...COMPLEXITY THEORY Beresford Parlett Department of Mathematics ULrIve-• * y o’ Ca’,f,:’rnia , . Berkeley, California 94720 @J:TUo19920 92-27745 -- July 1989
Kinetic theory of nonlinear transport phenomena in complex plasmas
Energy Technology Data Exchange (ETDEWEB)
Mishra, S. K. [Institute for Plasma Research (IPR), Gandhinagar 382428 (India); Sodha, M. S. [Centre for Energy Studies (CES), Indian Institute of Technology Delhi (IITD), New Delhi 110016 (India)
2013-03-15
In contrast to the prevalent use of the phenomenological theory of transport phenomena, a number of transport properties of complex plasmas have been evaluated by using appropriate expressions, available from the kinetic theory, which are based on Boltzmann's transfer equation; in particular, the energy dependence of the electron collision frequency has been taken into account. Following the recent trend, the number and energy balance of all the constituents of the complex plasma and the charge balance on the particles is accounted for; the Ohmic loss has also been included in the energy balance of the electrons. The charging kinetics for the complex plasma comprising of uniformly dispersed dust particles, characterized by (i) uniform size and (ii) the Mathis, Rumpl, and Nordsieck power law of size distribution has been developed. Using appropriate expressions for the transport parameters based on the kinetic theory, the system of equations has been solved to investigate the parametric dependence of the complex plasma transport properties on the applied electric field and other plasma parameters; the results are graphically illustrated.
Spectral theory of infinite-area hyperbolic surfaces
Borthwick, David
2016-01-01
This text introduces geometric spectral theory in the context of infinite-area Riemann surfaces, providing a comprehensive account of the most recent developments in the field. For the second edition the context has been extended to general surfaces with hyperbolic ends, which provides a natural setting for development of the spectral theory while still keeping technical difficulties to a minimum. All of the material from the first edition is included and updated, and new sections have been added. Topics covered include an introduction to the geometry of hyperbolic surfaces, analysis of the resolvent of the Laplacian, scattering theory, resonances and scattering poles, the Selberg zeta function, the Poisson formula, distribution of resonances, the inverse scattering problem, Patterson-Sullivan theory, and the dynamical approach to the zeta function. The new sections cover the latest developments in the field, including the spectral gap, resonance asymptotics near the critical line, and sharp geometric constan...
Quantum Yang-Mills theory on arbitrary surfaces
International Nuclear Information System (INIS)
Blau, Matthias; Thompson, George
1991-05-01
Quantum Yang-Mills theory on 2-dimensional surfaces is studied. Using path integral methods general and explicit expressions are derived for the partition function and expectation values of homologically trivial and non-trivial Wilson loops on closed surfaces of any genus, as well as for the kernels on manifolds with handles and boundaries. (author). 15 refs
2017-06-09
With this in mind , Complexity Theory has been analyzed to identify concepts and techniques that would benefit the joint intelligence analyst during...greater than the sum of the parts. With this in mind , Complexity Theory has been analyzed to identify concepts and techniques that would benefit the...as a complex adaptive system. In the effort to understand complex systems, Chaos and Complexity Theories have been developed. As Complexity Theory
COPD self-management supportive care: chaos and complexity theory.
Cornforth, Amber
This paper uses the emergent theories of chaos and complexity to explore the self-management supportive care of chronic obstructive pulmonary disease (COPD) patients within the evolving primary care setting. It discusses the concept of self-management support, the complexity of the primary care context and consultations, smoking cessation, and the impact of acute exacerbations and action planning. The author hopes that this paper will enable the acquisition of new insight and better understanding in this clinical area, as well as support meaningful learning and facilitate more thoughtful, effective and high quality patient-centred care within the context of primary care.
A New Approach to Formal Language Theory by Kolmogorov Complexity
Li, Ming; Vitanyi, Paul
2001-01-01
We present a new approach to formal language theory using Kolmogorov complexity. The main results presented here are an alternative for pumping lemma(s), a new characterization for regular languages, and a new method to separate deterministic context-free languages and nondeterministic context-free languages. The use of the new `incompressibility arguments' is illustrated by many examples. The approach is also successful at the high end of the Chomsky hierarchy since one can quantify nonrecur...
Integrated manufacturing of complex freeform surfaces
Niehaus, Frank; Huttenhuis, Stephan; Pisarski, Alex
2013-09-01
Innovative freeform optical systems such as head-up displays or LED headlights often require high quality and high volume optics. Injection molded polymer optics offer a cost effective solution. However, mold manufacturing for this process is extremely challenging as the machining of freeform surfaces is currently characterized by several independent production steps which can limit surface accuracy. By integrating diamond turning, milling, and metrology onto a single platform, the UPC 400 improves surface accuracy. Advanced software for machining and measurement data further reduces surface inaccuracies. This combination makes the UPC 400 efficient for prototyping free-form optics and manufacturing high precision molds.
Theory of inelastic effects in resonant atom-surface scattering
International Nuclear Information System (INIS)
Evans, D.K.
1983-01-01
The progress of theoretical and experimental developments in atom-surface scattering is briefly reviewed. The formal theory of atom-surface resonant scattering is reviewed and expanded, with both S and T matrix approaches being explained. The two-potential formalism is shown to be useful for dealing with the problem in question. A detailed theory based on the S-matrix and the two-potential formalism is presented. This theory takes account of interactions between the incident atoms and the surface phonons, with resonant effects being displayed explicitly. The Debye-Waller attenuation is also studied. The case in which the atom-surface potential is divided into an attractive part V/sub a/ and a repulsive part V/sub r/ is considered at length. Several techniques are presented for handling the scattering due to V/sub r/, for the case in which V/sub r/ is taken to be the hard corrugated surface potential. The theory is used to calculate the scattered intensities for the system 4 He/LiF(001). A detailed comparison with experiment is made, with polar scans, azimuthal scans, and time-of-flight measurements being considered. The theory is seen to explain the location and signature of resonant features, and to provide reasonable overall agreement with the experimental results
Complexity Theory, School Leadership and Management: Questions for Theory and Practice
Morrison, Keith
2010-01-01
Complexity theory (CT) has had a meteoric rise in management literature and the social sciences. Its fledgling importation into school leadership and management raises several questions and concerns. This article takes one view of CT and argues that, though its key elements have much to offer school leadership and management, caution has to be…
2010-12-02
will face in an uncertain future. Complexity Theory , History, Practice, Military Theory , Leadership 14. SUBJECT TERMS 70 15. NUMBER OF PAGES...complexity theory : scale, adaptive leadership , and bottom up feedback from the agents (the soldiers in the field). These are all key sub components of...Uhl-Bien, “Complexity v. Transformation: The New Leadership Revisited” (Ft. Meyers, Florida, Presented at Managing the Complex IV--Conference on
Theory of positrons in solids and on solid surfaces
International Nuclear Information System (INIS)
Puska, M.J.; Nieminen, R.M.
1994-01-01
Various experimental methods based on positron annihilation have evolved into important tools for researching the structure and properties of condensed matter. In particular, positron techniques are useful for the investigation of defects in solids and for the investigation of solid surfaces. Experimental methods need a comprehensive theory for a deep, quantitative understanding of the results. In the case of positron annihilation, the relevant theory includes models needed to describe the positron states as well as the different interaction processes in matter. In this review the present status of the theory of positrons in solids and on solid surfaces is given. The review consists of three main parts describing (a) the interaction processes, (b) the theory and methods for calculating positron states, and (c) selected recent results of positron studies of condensed matter
Teichmüller Theory of Bordered Surfaces
Directory of Open Access Journals (Sweden)
Leonid O. Chekhov
2007-05-01
Full Text Available We propose the graph description of Teichmüller theory of surfaces with marked points on boundary components (bordered surfaces. Introducing new parameters, we formulate this theory in terms of hyperbolic geometry. We can then describe both classical and quantum theories having the proper number of Thurston variables (foliation-shear coordinates, mapping-class group invariance (both classical and quantum, Poisson and quantum algebra of geodesic functions, and classical and quantum braid-group relations. These new algebras can be defined on the double of the corresponding graph related (in a novel way to a double of the Riemann surface (which is a Riemann surface with holes, not a smooth Riemann surface. We enlarge the mapping class group allowing transformations relating different Teichmüller spaces of bordered surfaces of the same genus, same number of boundary components, and same total number of marked points but with arbitrary distributions of marked points among the boundary components. We describe the classical and quantum algebras and braid group relations for particular sets of geodesic functions corresponding to $A_n$ and $D_n$ algebras and discuss briefly the relation to the Thurston theory.
DESIGNING OF DEVELOPED SURFACES OF COMPLEX PARTS
Directory of Open Access Journals (Sweden)
S. S. Tyshchenko
2017-04-01
Full Text Available Purpose. The paper focuses on ensuring the rational choice of parameters of the mating surfaces of parts when designing process equipment based on the methods of artificial intelligence. Methodology. The paper considers the geometric model of a ruled developed surface, the conditions of existence of such a surface and provides a generalized algorithm for surface plotting regardless of the type of the working element or the machine-building product. One of the most common technical surfaces are the ruled ones, among which a special position is occupied by developed surfaces (thanks to their differential-parametric properties: surface tangent plane is n contact along the rectilinear generator and does not change its position in space when changing the point of contact; surfaces can be produced by bending sheet metal. These provisions enable a product manufacturer to save significant material and energy means, therefore, the development of geometric models of such surfaces is an important task. Findings. We analyzed the geometrical model of the developed surface which is incident to two guides. Experimental studies have shown the applicationprospectivity of semi-digger moldboards on moldboard plows, particularly on the double-deck ones. Taking into account the operating speed of the plow 2.8 m/s, the plant residues plowing percentage for plow with semi-digger moldboards is 98.9%, and with the digger ones – 96.1%. Originality. According to results: 1 the approaches to solving the problem of recognition of wear conditions of the tested interface, depicted by its conceptual model, were elaborated; 2 the corresponding algorithms of the computational procedures were built; 3 the mathematical model that determines the effect of the parameters of the contacting surfaces on their performance properties – linear wear rate during the normal wear and tear was developed; 4 for this model the theoretical prerequisite of use for the random mating study were
Quantum field theory on higher-genus Riemann surfaces, 2
International Nuclear Information System (INIS)
Kubo, Reijiro; Ojima, Shuichi.
1990-08-01
Quantum field theory for closed bosonic string systems is formulated on arbitrary higher-genus Riemann surfaces in global operator formalism. Canonical commutation relations between bosonic string field X μ and their conjugate momenta P ν are derived in the framework of conventional quantum field theory. Problems arising in quantizing bosonic systems are considered in detail. Applying the method exploited in the preceding paper we calculate Ward-Takahashi identities. (author)
Density functional theory in surface science and heterogeneous catalysis
DEFF Research Database (Denmark)
Nørskov, Jens Kehlet; Scheffler, M.; Toulhoat, H.
2006-01-01
Solid surfaces are used extensively as catalysts throughout the chemical industry, in the energy sector, and in environmental protection. Recently, density functional theory has started providing new insight into the atomic-scale mechanisms of heterogeneous catalysis, helping to interpret the large...... amount of experimental data gathered during the last decades. This article shows how density functional theory can be used to describe the state of the surface during reactions and the rate of catalytic reactions. It will also show how we are beginning to understand the variation in catalytic activity...
Theory of magnetic transition metal nanoclusters on surfaces
Energy Technology Data Exchange (ETDEWEB)
Lounis, S.
2007-04-17
This thesis is motivated by the quest for the understanding and the exploration of complex magnetism provided by atomic scale magnetic clusters deposited on surfaces or embedded in the bulk. Use is made of the density functional theory (DFT). Acting within this framework, we have developed and implemented the treatment of non-collinear magnetism into the Juelich version of the full-potential Korringa-Kohn-Rostoker Green Function (KKR-GF) method. Firstly, the method was applied to 3d transition-metal clusters on different ferromagnetic surfaces. Different types of magnetic clusters where selected. In order to investigate magnetic frustration due to competing interactions within the ad-cluster we considered a (001) oriented surface of fcc metals, a topology which usually does not lead to non-collinear magnetism. We tuned the strength of the magnetic coupling between the ad-clusters and the ferromagnetic surface by varying the substrate from the case of Ni(001) with a rather weak hybridization of the Ni d-states with the adatom d-states to the case of Fe{sub 3ML}/Cu(001) with a much stronger hybridization due to the larger extend of the Fe wavefunctions. On Ni(001), the interaction between the Cr- as well as the Mn-dimer adatoms is of antiferromagnetic nature, which is in competition with the interaction with the substrate atoms. After performing total energy calculations we find that for Cr-dimer the ground state is collinear whereas the Mn-dimer prefers the non-collinear configuration as ground state. Bigger clusters are found to be magnetically collinear. These calculations were extended to 3d multimers on Fe{sub 3ML}/Cu(001). All neighboring Cr(Mn) moments in the compact tetramer are antiferromagnetically aligned in-plane, with the directions slightly tilted towards (outwards from) the substrate to gain some exchange interaction energy. The second type of frustration was investigated employing a Ni(111) surface, a surface with a triangular lattice of atoms, were
Surface nucleation in complex rheological systems
Herfurth, J.; Ulrich, J.
2017-07-01
Forced nucleation induced by suitable foreign seeds is an important tool to control the production of defined crystalline products. The quality of a surface provided by seed materials represents an important variable in the production of crystallizing layers that means for the nucleation process. Parameters like shape and surface structure, size and size distribution of the seed particles as well as the ability to hold up the moisture (the solvent), can have an influence on the nucleation process of different viscous supersaturated solutions. Here the properties of different starch powders as seeds obtained from corn, potato, rice, tapioca and wheat were tested. It could be found, that the best nucleation behavior of a sugar solution could be reached with the use of corn starch as seed material. Here the surface of the crystallized sugar layer is smooth, crystallization time is short (<3 h) and the shape of the product is easily reproducible. Beneficial properties of seed materials are therefore an edged, uneven surface, small particle sizes as well as low moisture content at ambient conditions within the seed materials.
Surface and interfacial tension measurement, theory, and applications
Hartland, Stanley
2004-01-01
This edited volume offers complete coverage of the latest theoretical, experimental, and computer-based data as summarized by leading international researchers. It promotes full understanding of the physical phenomena and mechanisms at work in surface and interfacial tensions and gradients, their direct impact on interface shape and movement, and their significance to numerous applications. Assessing methods for the accurate measurement of surface tension, interfacial tension, and contact angles, Surface and Interfacial Tension presents modern simulations of complex interfacial motions, such a
Density functional theory calculations of Rh-β-diketonato complexes.
Conradie, J
2015-01-28
Density functional theory (DFT) results on the geometry, energies and charges of selected Rh-β-diketonato reactants, products and transition states are discussed. Various DFT techniques are used to increase our understanding of the orientation of ligands coordinated to Rh, to identify the lowest energy geometry of possible geometrical isomers and to get a molecular orbital understanding of ground and transition states. Trends and relationships obtained between DFT calculated energies and charges, experimentally measured values and electronic parameters describing the electron donating power of groups and ligands, enable the design of ligands and complexes of specific reactivity.
The structure of complex networks theory and applications
Estrada, Ernesto
2012-01-01
This book deals with the analysis of the structure of complex networks by combining results from graph theory, physics, and pattern recognition. The book is divided into two parts. 11 chapters are dedicated to the development of theoretical tools for the structural analysis of networks, and 7 chapters are illustrating, in a critical way, applications of these tools to real-world scenarios. The first chapters provide detailed coverage of adjacency and metric and topologicalproperties of networks, followed by chapters devoted to the analysis of individual fragments and fragment-based global inva
Density functional theory in surface chemistry and catalysis
Nørskov, Jens K.; Abild-Pedersen, Frank; Studt, Felix; Bligaard, Thomas
2011-01-01
Recent advances in the understanding of reactivity trends for chemistry at transition-metal surfaces have enabled in silico design of heterogeneous catalysts in a few cases. The current status of the field is discussed with an emphasis on the role of coupling theory and experiment and future challenges. PMID:21220337
Density functional theory in surface chemistry and catalysis
DEFF Research Database (Denmark)
Nørskov, Jens Kehlet; Abild-Pedersen, Frank; Studt, Felix
2011-01-01
Recent advances in the understanding of reactivity trends for chemistry at transition-metal surfaces have enabled in silico design of heterogeneous catalysts in a few cases. The current status of the field is discussed with an emphasis on the role of coupling theory and experiment and future...
Density Functional Theory in Surface Chemistry and Catalysis
Energy Technology Data Exchange (ETDEWEB)
Norskov, Jens
2011-05-19
Recent advances in the understanding of reactivity trends for chemistry at transition metal surfaces have enabled in silico design of heterogeneous catalysts in a few cases. Current status of the field is discussed with an emphasis on the role of coupling between theory and experiment and future challenges.
Chern-Simons theory and three-dimensional surfaces
International Nuclear Information System (INIS)
Guven, Jemal
2007-01-01
There are two natural Chern-Simons theories associated with the embedding of a three-dimensional surface in Euclidean space: one is constructed using the induced metric connection and involves only the intrinsic geometry? the other is extrinsic and uses the connection associated with the gauging of normal rotations. As such, the two theories appear to describe very different aspects of the surface geometry. Remarkably, at a classical level, they are equivalent. In particular, it will be shown that their stress tensors differ only by a null contribution. Their Euler-Lagrange equations provide identical constraints on the normal curvature. A new identity for the Cotton tensor is associated with the triviality of the Chern-Simons theory for embedded hypersurfaces implied by this equivalence
Proton adsorption onto alumina: extension of multisite complexation (MUSIC) theory
Energy Technology Data Exchange (ETDEWEB)
Nagashima, K.; Blum, F.D.
1999-09-01
The adsorption isotherm of protons onto a commercial {gamma}-alumina sample was determined in aqueous nitric acid with sodium nitrate as a background electrolyte. Three discrete regions could be discerned in the log-log plots of the proton isotherm determined at the solution pH 5 to 2. The multisite complexation (MUSIC) model was modified to analyze the simultaneous adsorption of protons onto various kinds of surface species.
Analyzing complex networks evolution through Information Theory quantifiers
International Nuclear Information System (INIS)
Carpi, Laura C.; Rosso, Osvaldo A.; Saco, Patricia M.; Ravetti, Martin Gomez
2011-01-01
A methodology to analyze dynamical changes in complex networks based on Information Theory quantifiers is proposed. The square root of the Jensen-Shannon divergence, a measure of dissimilarity between two probability distributions, and the MPR Statistical Complexity are used to quantify states in the network evolution process. Three cases are analyzed, the Watts-Strogatz model, a gene network during the progression of Alzheimer's disease and a climate network for the Tropical Pacific region to study the El Nino/Southern Oscillation (ENSO) dynamic. We find that the proposed quantifiers are able not only to capture changes in the dynamics of the processes but also to quantify and compare states in their evolution.
Complex adaptive systems and game theory: An unlikely union
Hadzikadic, M.; Carmichael, T.; Curtin, C.
2010-01-01
A Complex Adaptive System is a collection of autonomous, heterogeneous agents, whose behavior is defined with a limited number of rules. A Game Theory is a mathematical construct that assumes a small number of rational players who have a limited number of actions or strategies available to them. The CAS method has the potential to alleviate some of the shortcomings of GT. On the other hand, CAS researchers are always looking for a realistic way to define interactions among agents. GT offers an attractive option for defining the rules of such interactions in a way that is both potentially consistent with observed real-world behavior and subject to mathematical interpretation. This article reports on the results of an effort to build a CAS system that utilizes GT for determining the actions of individual agents. ?? 2009 Wiley Periodicals, Inc. Complexity, 16,24-42, 2010.
Analyzing complex networks evolution through Information Theory quantifiers
Energy Technology Data Exchange (ETDEWEB)
Carpi, Laura C., E-mail: Laura.Carpi@studentmail.newcastle.edu.a [Civil, Surveying and Environmental Engineering, University of Newcastle, University Drive, Callaghan NSW 2308 (Australia); Departamento de Fisica, Instituto de Ciencias Exatas, Universidade Federal de Minas Gerais, Av. Antonio Carlos 6627, Belo Horizonte (31270-901), MG (Brazil); Rosso, Osvaldo A., E-mail: rosso@fisica.ufmg.b [Departamento de Fisica, Instituto de Ciencias Exatas, Universidade Federal de Minas Gerais, Av. Antonio Carlos 6627, Belo Horizonte (31270-901), MG (Brazil); Chaos and Biology Group, Instituto de Calculo, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellon II, Ciudad Universitaria, 1428 Ciudad de Buenos Aires (Argentina); Saco, Patricia M., E-mail: Patricia.Saco@newcastle.edu.a [Civil, Surveying and Environmental Engineering, University of Newcastle, University Drive, Callaghan NSW 2308 (Australia); Departamento de Hidraulica, Facultad de Ciencias Exactas, Ingenieria y Agrimensura, Universidad Nacional de Rosario, Avenida Pellegrini 250, Rosario (Argentina); Ravetti, Martin Gomez, E-mail: martin.ravetti@dep.ufmg.b [Departamento de Engenharia de Producao, Universidade Federal de Minas Gerais, Av. Antonio Carlos, 6627, Belo Horizonte (31270-901), MG (Brazil)
2011-01-24
A methodology to analyze dynamical changes in complex networks based on Information Theory quantifiers is proposed. The square root of the Jensen-Shannon divergence, a measure of dissimilarity between two probability distributions, and the MPR Statistical Complexity are used to quantify states in the network evolution process. Three cases are analyzed, the Watts-Strogatz model, a gene network during the progression of Alzheimer's disease and a climate network for the Tropical Pacific region to study the El Nino/Southern Oscillation (ENSO) dynamic. We find that the proposed quantifiers are able not only to capture changes in the dynamics of the processes but also to quantify and compare states in their evolution.
Hamieh, Ali Imad
2017-02-01
The aim of this thesis is to explore new simpler and efficient routes for the preparation of surface organometallic complexes (SOMC) for the transformation of small organic molecules to valuable products. The key element in this new route relies on surface alkylation of various halogenated surface coordination complexes or organometallic fragments (SOMF).
Design of structurally colored surfaces based on scalar diffraction theory
DEFF Research Database (Denmark)
Johansen, Villads Egede; Andkjær, Jacob Anders; Sigmund, Ole
2014-01-01
In this paper we investigate the possibility of controlling the color and appearance of surfaces simply by modifying the height profile of the surface on a nanoscale level. The applications for such methods are numerous: new design possibilities for high-end products, color engraving on any highly...... reflective surface, paint-free text and coloration, UV-resistant coloring, etc. In this initial study, the main focus is on finding a systematic way to obtain these results. For now the simulation and optimization is based on a simple scalar diffraction theory model. From the results, several design issues...
Khattar, Randa
What do the new sciences of complex relationality offer education? This work draws on complexity theory, neurological understandings of biology and phenomenology, and attentiveness to study what the new sciences might offer education and the possibilities of a pedagogical understanding of embodied knowing. Complexity theory provides understandings of local-global relationality, self-organization, far-from-equilibrium conditions, and emergent dynamics that are important for describing pedagogical relationality. In itself, however, complexity theory is lacking an attention to issues of embodiment that respond directly to an ethical understanding of relationality. Phenomenology provides important views on the human experience of perception, for example, Merleau-Ponty's, whose research opens up possibilities for embodiment and attentiveness. At the level of pedagogical practice, I will pose, following biologists Humberto Maturana and Francisco Varela's autopoietic self-making understanding of life, that attentiveness perspectives, which have been largely absent from western pedagogical theory and practice, are crucial to promoting embodied knowing for education. Maturana and Varela's autopoietic perspective offers an embodied understanding of living---and therefore education---which opens up necessary attentive spaces to listen to one another in non judgmental awareness in the present moment of experience. I offer insights into a relationally complex conception of education drawing on this biological and autopoietically-grounded framework. These insights are framed in the context of five clusters of relations: (1) emergence, far-from-equilibrium, and local-global relationality; (2) autopoietic autonomy, structural determination and sensory-motor coupling; (3) triggering perturbations, structural plasticity, and autopoietic organization; (4) knowing as adequate action, domains of interaction, and blind spots; and (5) attentiveness and responsive relationality. Four
Multiagent model and mean field theory of complex auction dynamics
Chen, Qinghua; Huang, Zi-Gang; Wang, Yougui; Lai, Ying-Cheng
2015-09-01
Recent years have witnessed a growing interest in analyzing a variety of socio-economic phenomena using methods from statistical and nonlinear physics. We study a class of complex systems arising from economics, the lowest unique bid auction (LUBA) systems, which is a recently emerged class of online auction game systems. Through analyzing large, empirical data sets of LUBA, we identify a general feature of the bid price distribution: an inverted J-shaped function with exponential decay in the large bid price region. To account for the distribution, we propose a multi-agent model in which each agent bids stochastically in the field of winner’s attractiveness, and develop a theoretical framework to obtain analytic solutions of the model based on mean field analysis. The theory produces bid-price distributions that are in excellent agreement with those from the real data. Our model and theory capture the essential features of human behaviors in the competitive environment as exemplified by LUBA, and may provide significant quantitative insights into complex socio-economic phenomena.
Jain, Amber; Herman, Michael F; Ouyang, Wenjun; Subotnik, Joseph E
2015-10-07
We provide an in-depth investigation of transmission coefficients as computed using the augmented-fewest switches surface hopping algorithm in the low energy regime. Empirically, microscopic reversibility is shown to hold approximately. Furthermore, we show that, in some circumstances, including decoherence on top of surface hopping calculations can help recover (as opposed to destroy) oscillations in the transmission coefficient as a function of energy; these oscillations can be studied analytically with semiclassical scattering theory. Finally, in the spirit of transition state theory, we also show that transmission coefficients can be calculated rather accurately starting from the curve crossing point and running trajectories forwards and backwards.
Nonabelian Jacobian of projective surfaces geometry and representation theory
Reider, Igor
2013-01-01
The Jacobian of a smooth projective curve is undoubtedly one of the most remarkable and beautiful objects in algebraic geometry. This work is an attempt to develop an analogous theory for smooth projective surfaces - a theory of the nonabelian Jacobian of smooth projective surfaces. Just like its classical counterpart, our nonabelian Jacobian relates to vector bundles (of rank 2) on a surface as well as its Hilbert scheme of points. But it also comes equipped with the variation of Hodge-like structures, which produces a sheaf of reductive Lie algebras naturally attached to our Jacobian. This constitutes a nonabelian analogue of the (abelian) Lie algebra structure of the classical Jacobian. This feature naturally relates geometry of surfaces with the representation theory of reductive Lie algebras/groups. This work’s main focus is on providing an in-depth study of various aspects of this relation. It presents a substantial body of evidence that the sheaf of Lie algebras on the nonabelian Jacobian is an effic...
Surface wave propagation over sinusoidally varying topography: Theory and observation
Davies, A. G.; Heathershaw, A. D.
Linear perturbation theory is used to show that the reflection coefficient of a patch of sinusoidal ripples on an otherwise flat bed is oscillatory in the quotient of the length of the patch and the surface wave length, and strongly dependent upon the quotient of the surface and bed wave numbers. Resonant interaction between the surface waves and the ripples if the surface wavenumber is half the ripple wavenumber is demonstrated. Few ripples, of relatively small steepness, are required to produce a substantial reflected wave. In resonant cases, the partially standing wave on the up-wave side of the ripple patch gives way, in an almost linear manner over the the ripple patch itself, to a progressive (transmitted) wave on the down-wave side. Wave tank data agree well with predictions, and suggest coupling between wave reflection and ripple growth on an erodible bed.
Surface charge algebra in gauge theories and thermodynamic integrability
International Nuclear Information System (INIS)
Barnich, Glenn; Compere, Geoffrey
2008-01-01
Surface charges and their algebra in interacting Lagrangian gauge field theories are constructed out of the underlying linearized theory using techniques from the variational calculus. In the case of exact solutions and symmetries, the surface charges are interpreted as a Pfaff system. Integrability is governed by Frobenius' theorem and the charges associated with the derived symmetry algebra are shown to vanish. In the asymptotic context, we provide a generalized covariant derivation of the result that the representation of the asymptotic symmetry algebra through charges may be centrally extended. Comparison with Hamiltonian and covariant phase space methods is made. All approaches are shown to agree for exact solutions and symmetries while there are differences in the asymptotic context
Surface mapping of magnetic hot stars. Theories versus observations
Kochukhov, O.
2018-01-01
This review summarises results of recent magnetic and chemical abundance surface mapping studies of early-type stars. We discuss main trends uncovered by observational investigations and consider reliability of spectropolarimetric inversion techniques used to infer these results. A critical assessment of theoretical attempts to interpret empirical magnetic and chemical maps in the framework of, respectively, the fossil field and atomic diffusion theories is also presented. This confrontation of theory and observations demonstrates that 3D MHD models of fossil field relaxation are successful in matching the observed range of surface magnetic field geometries. At the same time, even the most recent time-dependent atomic diffusion calculations fail to reproduce diverse horizontal abundance distributions found in real magnetic hot stars.
Formation of oxygen complexes in controlled atmosphere at surface ...
Indian Academy of Sciences (India)
The effects of boron and phosphorus incorporation in phenolic resin precursor to the oxidation resistance of glassy carbon have been studied. In order to reveal the nature and composition of the oxygen complexes formed at the surface of doped glassy carbon, under controlled atmosphere, the surface of the samples was ...
Formation of oxygen complexes in controlled atmosphere at surface ...
Indian Academy of Sciences (India)
Abstract. The effects of boron and phosphorus incorporation in phenolic resin precursor to the oxidation resistance of glassy carbon have been studied. In order to reveal the nature and composition of the oxygen complexes formed at the surface of doped glassy carbon, under controlled atmosphere, the surface of the ...
Impact assessment procedures for sustainable development: A complexity theory perspective
International Nuclear Information System (INIS)
Nooteboom, Sibout
2007-01-01
The author assumes that effective Impact Assessment procedures should somehow contribute to sustainable development. There is no widely agreed framework for evaluating such effectiveness. The author suggests that complexity theories may offer criteria. The relevant question is 'do Impact Assessment Procedures contribute to the 'requisite variety' of a social system for it to deal with changing circumstances?' Requisite variety theoretically relates to the capability of a system to deal with changes in its environment. The author reconstructs how thinking about achieving sustainable development has developed in a sequence of discourses in The Netherlands since the 1970s. Each new discourse built on the previous ones, and is supposed to have added to 'requisite variety'. The author asserts that Impact Assessment procedures may be a necessary component in such sequences and derives possible criteria for effectiveness
Complex analysis fundamentals of the classical theory of functions
Stalker, John
1998-01-01
This clear, concise introduction to the classical theory of one complex variable is based on the premise that "anything worth doing is worth doing with interesting examples." The content is driven by techniques and examples rather than definitions and theorems. This self-contained monograph is an excellent resource for a self-study guide and should appeal to a broad audience. The only prerequisite is a standard calculus course. The first chapter deals with a beautiful presentation of special functions. . . . The third chapter covers elliptic and modular functions. . . in much more detail, and from a different point of view, than one can find in standard introductory books. . . . For [the] subjects that are omitted, the author has suggested some excellent references for the reader who wants to go through these topics. The book is read easily and with great interest. It can be recommended to both students as a textbook and to mathematicians and physicists as a useful reference. ---Mathematical Reviews Mainly or...
Complex space source theory of partially coherent light wave.
Seshadri, S R
2010-07-01
The complex space source theory is used to derive a general integral expression for the vector potential that generates the extended full Gaussian wave in terms of the input value of the vector potential of the corresponding paraxial beam. The vector potential and the fields are assumed to fluctuate on a time scale that is large compared to the wave period. The Poynting vector in the propagation direction averaged over a wave period is expressed in terms of the cross-spectral density of the fluctuating vector potential across the input plane. The Schell model is assumed for the cross-spectral density. The radiation intensity distribution and the power radiated are determined. The effect of spatial coherence on the radiation intensity distribution and the radiated power are investigated for different values of the physical parameters. Illustrative numerical results are provided to bring out the effect of spatial coherence on the propagation characteristics of the fluctuating light wave.
Murayama, Shogo; Kinugawa, Hikaru; Tokuda, Isao T.; Gotoda, Hiroshi
2018-02-01
We present an experimental study on the characterization of dynamic behavior of flow velocity field during thermoacoustic combustion oscillations in a turbulent confined combustor from the viewpoints of statistical complexity and complex-network theory, involving detection of a precursor of thermoacoustic combustion oscillations. The multiscale complexity-entropy causality plane clearly shows the possible presence of two dynamics, noisy periodic oscillations and noisy chaos, in the shear layer regions (1) between the outer recirculation region in the dump plate and a recirculation flow in the wake of the centerbody and (2) between the outer recirculation region in the dump plate and a vortex breakdown bubble away from the centerbody. The vertex strength in the turbulence network and the community structure of the vorticity field can identify the vortical interactions during thermoacoustic combustion oscillations. Sequential horizontal visibility graph motifs are useful for capturing a precursor of themoacoustic combustion oscillations.
On the Complexity of Item Response Theory Models.
Bonifay, Wes; Cai, Li
2017-01-01
Complexity in item response theory (IRT) has traditionally been quantified by simply counting the number of freely estimated parameters in the model. However, complexity is also contingent upon the functional form of the model. We examined four popular IRT models-exploratory factor analytic, bifactor, DINA, and DINO-with different functional forms but the same number of free parameters. In comparison, a simpler (unidimensional 3PL) model was specified such that it had 1 more parameter than the previous models. All models were then evaluated according to the minimum description length principle. Specifically, each model was fit to 1,000 data sets that were randomly and uniformly sampled from the complete data space and then assessed using global and item-level fit and diagnostic measures. The findings revealed that the factor analytic and bifactor models possess a strong tendency to fit any possible data. The unidimensional 3PL model displayed minimal fitting propensity, despite the fact that it included an additional free parameter. The DINA and DINO models did not demonstrate a proclivity to fit any possible data, but they did fit well to distinct data patterns. Applied researchers and psychometricians should therefore consider functional form-and not goodness-of-fit alone-when selecting an IRT model.
Nonlinear mean field theory for nuclear matter and surface properties
International Nuclear Information System (INIS)
Boguta, J.; Moszkowski, S.A.
1983-01-01
Nuclear matter properties are studied in a nonlinear relativistic mean field theory. We determine the parameters of the model from bulk properties of symmetric nuclear matter and a reasonable value of the effective mass. In this work, we stress the nonrelativistic limit of the theory which is essentially equivalent to a Skyrme hamiltonian, and we show that most of the results can be obtained, to a good approximation, analytically. The strength of the required parameters is determined from the binding energy and density of nuclear matter and the effective nucleon mass. For realistic values of the parameters, the nonrelativistic approximation turns out to be quite satisfactory. Using reasonable values of the parameters, we can account for other key properties of nuclei, such as the spin-orbit coupling, surface energy, and diffuseness of the nuclear surface. Also the energy dependence of the nucleon-nucleus optical model is accounted for reasonably well except near the Fermi surface. It is found, in agreement with empirical results, that the Landau parameter F 0 is quite small in normal nuclear matter. Both density dependence and momentum dependence of the NN interaction, but especially the former, are important for nuclear saturation. The required scalar and vector coupling constants agree fairly well with those obtained from analyses of NN scattering phase shifts with one-boson-exchange models. The mean field theory provides a semiquantitative justification for the weak Skyrme interaction in odd states. The strength of the required nonlinear term is roughly consistent with that derived using a new version of the chiral mean field theory in which the vector mass as well as the nucleon mass is generated by the sigma-field. (orig.)
Removal of arsenate by ferrihydrite via surface complexation and surface precipitation
International Nuclear Information System (INIS)
Jiang, Xiuli; Peng, Changjun; Fu, Dun; Chen, Zheng; Shen, Liang; Li, Qingbiao; Ouyang, Tong; Wang, Yuanpeng
2015-01-01
Graphical abstract: - Highlights: • Surface complexation and surface precipitation of As on ferrihydrite happen at pH 3–6. • The formation of surface precipitation enhanced As(V) adsorption. • The dissolved Fe 3+ had a good linear relationship with the amount of arsenate re-adsorption. - Abstract: In this study, macroscopic and spectroscopic experimental methods accurately modeled the sorption process of arsenate on ferrihydrite. EXAFS, X-ray diffraction and infrared (IR) spectroscopy indicated that the behavior of As(V) adsorption onto ferrihydrite took place mainly via surface complexation and surface precipitation at acidic pH (3.0–6.0), while the surface precipitation was dominated at longer time intervals and higher Fe 3+ concentration. The macroscopic competitive adsorption experiment between arsenate with phosphate indicated two types of adsorption sites existing on the surface of ferrihydrite, i.e., non-exchangeable sites, which are responsible for a rapid surface complex formation; and exchangeable sites for a slow build-up of surface precipitates. In the slow build-up precipitates, the As(V) surface coverage (mmol/g) exhibited a good linear relationship (R 2 = 0.952) with the amount of dissolved Fe 3+ . Three steps are involved during the process of surface precipitation, i.e., (1) an initial uptake of As(V) via surface complexation; (2) re-adsorption of Fe 3+ leaching from ferrihydrite on the surface complex; and (3) As(V) adsorption via surface complexation again and finally forming the surface precipitate.
Complexity and Control: Towards a Rigorous Behavioral Theory of Complex Dynamical Systems
Ivancevic, Vladimir G.; Reid, Darryn J.
We introduce our motive for writing this book on complexity and control with a popular "complexity myth," which seems to be quite wide spread among chaos and complexity theory fashionistas: quote>Low-dimensional systems usually exhibit complex behaviours (which we know fromMay's studies of the Logisticmap), while high-dimensional systems usually exhibit simple behaviours (which we know from synchronisation studies of the Kuramoto model)...quote> We admit that this naive view on complex (e.g., human) systems versus simple (e.g., physical) systems might seem compelling to various technocratic managers and politicians; indeed, the idea makes for appealing sound-bites. However, it is enough to see both in the equations and computer simulations of pendula of various degree - (i) a single pendulum, (ii) a double pendulum, and (iii) a triple pendulum - that this popular myth is plain nonsense. The only thing that we can learn from it is what every tyrant already knows: by using force as a strong means of control, it is possible to effectively synchronise even hundreds of millions of people, at least for a while.
Turbulent lubrication theory considering the surface roughness effects, 2
International Nuclear Information System (INIS)
Hashimoto, Hiromu; Wada, Sanae; Kobayashi, Toshinobu.
1990-01-01
This second paper describes an application of the generalized turbulent lubrication theory considering the surface roughness effects, which is developed in the previous paper, to the finite-width journal bearings. In the numerical analysis, the nonlinear equations for the modified turbulence coefficients are simplified to save a computation time within a satisfactory accuracy under the assumption that the shear flow is superior to the pressure flow in the turbulent lubrication films. The numerical results of pressure distribution, Sommerfeld number, attitude angle, friction coefficient and flow rate for the Reynolds number of Re=2000, 5000 and 10000 are indicated in graphic form for various values of relative roughness, and the effects of surface roughness on these static performance characteristics are discussed. Moreover, the eccentricity ratio and attitude angle of the journal bearings with homogeneous rough surface are obtained experimentally for a wide range of Sommerfeld number, and the experimental results are compared with theoretical results. (author)
Kuhn, John R., Jr.
2009-01-01
Drawing upon the theories of complexity and complex adaptive systems and the Singerian Inquiring System from C. West Churchman's seminal work "The Design of Inquiring Systems" the dissertation herein develops a systems design theory for continuous auditing systems. The dissertation consists of discussion of the two foundational theories,…
Applicability of surface complexation modelling in TVO's studies on sorption of radionuclides
International Nuclear Information System (INIS)
Carlsson, T.
1994-03-01
The report focuses on the possibility of applying surface complexation theories to the conditions at a potential repository site in Finland and of doing proper experimental work in order to determine necessary constants for the models. The report provides background information on: (1) what type experiments should be carried out in order to produce data for surface complexation modelling of sorption phenomena under potential Finnish repository conditions, and (2) how to design and perform properly such experiments, in order to gather data, develop models or both. The report does not describe in detail how proper surface complexation experiments or modelling should be carried out. The work contains several examples of information that may be valuable in both modelling and experimental work. (51 refs., 6 figs., 4 tabs.)
Compact complex surfaces with geometric structures related to split quaternions
International Nuclear Information System (INIS)
Davidov, Johann; Grantcharov, Gueo; Mushkarov, Oleg; Yotov, Miroslav
2012-01-01
We study the problem of existence of geometric structures on compact complex surfaces that are related to split quaternions. These structures, called para-hypercomplex, para-hyperhermitian and para-hyperkähler, are analogs of the hypercomplex, hyperhermitian and hyperkähler structures in the definite case. We show that a compact 4-manifold carries a para-hyperkähler structure iff it has a metric of split signature together with two parallel, null, orthogonal, pointwise linearly independent vector fields. Every compact complex surface admitting a para-hyperhermitian structure has vanishing first Chern class and we show that, unlike the definite case, many of these surfaces carry infinite-dimensional families of such structures. We provide also compact examples of complex surfaces with para-hyperhermitian structures which are not locally conformally para-hyperkähler. Finally, we discuss the problem of non-existence of para-hyperhermitian structures on Inoue surfaces of type S 0 and provide a list of compact complex surfaces which could carry para-hypercomplex structures.
Compact complex surfaces with geometric structures related to split quaternions
Energy Technology Data Exchange (ETDEWEB)
Davidov, Johann, E-mail: jtd@math.bas.bg [Institute of Mathematics and Informatics, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria); ' L. Karavelov' Civil Engineering Higher School, 175 Suhodolska Str., 1373 Sofia (Bulgaria); Grantcharov, Gueo, E-mail: grantchg@fiu.edu [Department of Mathematics and Statistics, Florida International University, Miami, FL 33199 (United States); Mushkarov, Oleg, E-mail: muskarov@math.bas.bg [Institute of Mathematics and Informatics, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria); Yotov, Miroslav, E-mail: yotovm@fiu.edu [Department of Mathematics and Statistics, Florida International University, Miami, FL 33199 (United States)
2012-12-11
We study the problem of existence of geometric structures on compact complex surfaces that are related to split quaternions. These structures, called para-hypercomplex, para-hyperhermitian and para-hyperkaehler, are analogs of the hypercomplex, hyperhermitian and hyperkaehler structures in the definite case. We show that a compact 4-manifold carries a para-hyperkaehler structure iff it has a metric of split signature together with two parallel, null, orthogonal, pointwise linearly independent vector fields. Every compact complex surface admitting a para-hyperhermitian structure has vanishing first Chern class and we show that, unlike the definite case, many of these surfaces carry infinite-dimensional families of such structures. We provide also compact examples of complex surfaces with para-hyperhermitian structures which are not locally conformally para-hyperkaehler. Finally, we discuss the problem of non-existence of para-hyperhermitian structures on Inoue surfaces of type S{sup 0} and provide a list of compact complex surfaces which could carry para-hypercomplex structures.
Eom, Namsoon; Parsons, Drew F; Craig, Vincent S J
2017-07-06
The interaction between colloidal particles is commonly viewed through the lens of DLVO theory, whereby the interaction is described as the sum of the electrostatic and dispersion forces. For similar materials acting across a medium at pH values remote from the isoelectric point the theory typically involves an electrostatic repulsion that is overcome by dispersion forces at very small separations. However, the dominance of the dispersion forces at short separations is generally not seen in force measurements, with the exception of the interaction between mica surfaces. The discrepancy for silica surfaces has been attributed to hydration forces, but this does not explain the situation for titania surfaces where the dispersion forces are very much larger. Here, the interaction forces between very smooth hafnia surfaces have been measured using the colloid probe technique and the forces evaluated within the DLVO framework, including both hydration forces and the influence of roughness. The measured forces across a wide range of pH at different salt concentrations are well described with a single parameter for the surface roughness. These findings show that even small degrees of surface roughness significantly alter the form of the interaction force and therefore indicate that surface roughness needs to be included in the evaluation of surface forces between all surfaces that are not ideally smooth.
Semiclassical perturbation theory for diffraction in heavy atom surface scattering.
Miret-Artés, Salvador; Daon, Shauli; Pollak, Eli
2012-05-28
The semiclassical perturbation theory formalism of Hubbard and Miller [J. Chem. Phys. 78, 1801 (1983)] for atom surface scattering is used to explore the possibility of observation of heavy atom diffractive scattering. In the limit of vanishing ℏ the semiclassical theory is shown to reduce to the classical perturbation theory. The quantum diffraction pattern is sensitive to the characteristics of the beam of incoming particles. Necessary conditions for observation of quantum diffraction are derived for the angular width of the incoming beam. An analytic expression for the angular distribution as a function of the angular and momentum variance of the incoming beam is obtained. We show both analytically and through some numerical results that increasing the angular width of the incident beam leads to decoherence of the quantum diffraction peaks and one approaches the classical limit. However, the incoherence of the beam in the parallel direction does not destroy the diffraction pattern. We consider the specific example of Ar atoms scattered from a rigid LiF(100) surface.
Nanodrop on a nanorough solid surface: Density functional theory considerations
Berim, Gersh O.; Ruckenstein, Eli
2008-07-01
The density distributions and contact angles of liquid nanodrops on nanorough solid surfaces are determined on the basis of a nonlocal density functional theory. Two kinds of roughness, chemical and physical, are examined. The former considers the substrate as a sequence of two kinds of semi-infinite vertical plates of equal thicknesses but of different natures with different strengths for the liquid-solid interactions. The physical roughness involves an ordered set of pillars on a flat homogeneous surface. Both hydrophobic and hydrophilic surfaces were considered. For the chemical roughness, the contact angle which the drop makes with the flat surface increases when the strength of the liquid-solid interaction for one kind of plates decreases with respect to the fixed value of the other kind of plates. Such a behavior is in agreement with the Cassie-Baxter expression derived from macroscopic considerations. For the physical roughness on a hydrophobic surface, the contact angle which a drop makes with the plane containing the tops of the pillars increases with increasing roughness. Such a behavior is consistent with the Wenzel formula developed for macroscopic drops. For hydrophilic surfaces, as the roughness increases the contact angle first increases, in contradiction with the Wenzel formula, which predicts for hydrophilic surfaces a decrease of the contact angle with increasing roughness. However, a further increase in roughness changes nonmonotonously the contact angle, and at some roughness, the drop disappears and only a liquid film is present on the surface. It was also found that the contact angle has a periodic dependence on the volume of the drop.
Embedding research in health systems: lessons from complexity theory.
Caffrey, Louise; Wolfe, Charles; McKevitt, Christopher
2016-07-22
Internationally, there has been increasing focus on creating health research systems. This article aims to investigate the challenges of implementing apparently simple strategies to support the development of a health research system. We focus on a case study of an English National Health Service Hospital Trust that sought to implement the national recommendation that health organisations should introduce a statement about research on all patient admission letters. We apply core concepts from complexity theory to the case study and undertake a documentary analysis of the email dialogue between staff involved in implementing this initiative. The process of implementing a research statement in patient admission letters in one clinical service took 1 year and 21 days. The length of time needed was influenced firstly by adaptive self-organisation, underpinned by competing interests. Secondly, it was influenced by the relationship between systems, rather than simply being a product of issues within those systems. The relationship between the health system and the research system was weaker than might have been expected. Responsibilities were unclear, leading to confusion and delayed action. Conventional ways of thinking about organisations suggest that change happens when leaders and managers change the strategic vision, structure or procedures in an organisation and then persuade others to rationally implement the strategy. However, health research systems are complex adaptive systems characterised by high levels of unpredictability due to self-organisation and systemic interactions, which give rise to 'emergent' properties. We argue for the need to study how micro-processes of organisational dynamics may give rise to macro patterns of behaviour and strategic organisational direction and for the use of systems approaches to investigate the emergent properties of health research systems.
Surface Complexation of Calcium Minerals in Aqueous Solution.
Wu; Forsling; Holmgren
2000-04-15
The complexation of Alizarin Red S (ARS) at the surface of hydrous fluorite particles has been investigated by means of potentiometric titrations, adsorption experiments, and zeta-potential measurements in 0.1 mol dm(-3) KCl ionic medium at 25.0 degrees C, as well as by UV/visible specular reflectance, FT-IR, and FT-Raman spectroscopy. Chemical reaction models describing the equilibria of ARS (HA(2-)) at the aqueous fluorite surfaces ( identical withX) have been established as follows: Experimental data were evaluated using the computer program FITEQL on the basis of a constant capacitance model for the electric double layer. Surface complexation mechanisms involving the R-SO(3)(-), R-beta-OH, and R-alpha-OH active groups of the ARS molecule are proposed to describe coordination to the fluorite surface. Copyright 2000 Academic Press.
Surface complexation modeling of americium sorption onto volcanic tuff.
Ding, M; Kelkar, S; Meijer, A
2014-10-01
Results of a surface complexation model (SCM) for americium sorption on volcanic rocks (devitrified and zeolitic tuff) are presented. The model was developed using PHREEQC and based on laboratory data for americium sorption on quartz. Available data for sorption of americium on quartz as a function of pH in dilute groundwater can be modeled with two surface reactions involving an americium sulfate and an americium carbonate complex. It was assumed in applying the model to volcanic rocks from Yucca Mountain, that the surface properties of volcanic rocks can be represented by a quartz surface. Using groundwaters compositionally representative of Yucca Mountain, americium sorption distribution coefficient (Kd, L/Kg) values were calculated as function of pH. These Kd values are close to the experimentally determined Kd values for americium sorption on volcanic rocks, decreasing with increasing pH in the pH range from 7 to 9. The surface complexation constants, derived in this study, allow prediction of sorption of americium in a natural complex system, taking into account the inherent uncertainty associated with geochemical conditions that occur along transport pathways. Published by Elsevier Ltd.
Kreitner, Christoph; Heinze, Katja
2016-09-21
Deactivation pathways of the triplet metal-to-ligand charge transfer ((3)MLCT) excited state of cyclometalated polypyridine ruthenium complexes with [RuN5C](+) coordination are discussed on the basis of the available experimental data and a series of density functional theory calculations. Three different complex classes are considered, namely with [Ru(N^N)2(N^C)](+), [Ru(N^N^N)(N^C^N)](+) and [Ru(N^N^N)(N^N^C)](+) coordination modes. Excited state deactivation in these complex types proceeds via five distinct decay channels. Vibronic coupling of the (3)MLCT state to high-energy oscillators of the singlet ground state ((1)GS) allows tunneling to the ground state followed by vibrational relaxation (path A). A ligand field excited state ((3)MC) is thermally accessible via a (3)MLCT →(3)MC transition state with the (3)MC state being strongly coupled to the (1)GS surface via a low-energy minimum energy crossing point (path B). Furthermore, a (3)MLCT →(1)GS surface crossing point directly couples the triplet and singlet potential energy surfaces (path C). Charge transfer states either with higher singlet character or with different orbital parentage and intrinsic symmetry restrictions are thermally populated which promote non-radiative decay via tunneling to the (1)GS state (path D). Finally, the excited state can decay via phosphorescence (path E). The dominant deactivation pathways differ for the three individual complex classes. The implications of these findings for isoelectronic iridium(iii) or iron(ii) complexes are discussed. Ultimately, strategies for optimizing the emission efficiencies of cyclometalated polypyridine complexes of d(6)-metal ions, especially Ru(II), are suggested.
Security Inequalities in North America: Reassessing Regional Security Complex Theory
Directory of Open Access Journals (Sweden)
Richard Kilroy
2017-12-01
Full Text Available This article re-evaluates earlier work done by the authors on Regional Security Complex Theory (RSCT in North America, using sectoral analysis initially developed by Buzan and Waever, but also adding the variables of institutions, identity, and interests. These variables are assessed qualitatively in the contemporary context on how they currently impress upon the process of securitization within sectoral relations between Canada, Mexico, and the United States. The article reviews the movement from bilateral security relations between these states to the development of a trilateral response to regional security challenges post- 9/11. It further addresses the present period and what appears to be a security process derailed by recent political changes and security inequalities, heightened by the election of Donald Trump in 2016. The article argues that while these three states initially evinced a convergence of regional security interests after 9/11, which did create new institutional responses, under the current conditions, divergence in political interests and security inequalities have reduced the explanatory power of RSCT in North America. Relations between states in North American are becoming less characterized by the role of institutions and interests and more by identity politics in the region.
Research on Evolutionary Mechanism of Agile Supply Chain Network via Complex Network Theory
Directory of Open Access Journals (Sweden)
Nai-Ru Xu
2016-01-01
Full Text Available The paper establishes the evolutionary mechanism model of agile supply chain network by means of complex network theory which can be used to describe the growth process of the agile supply chain network and analyze the complexity of the agile supply chain network. After introducing the process and the suitability of taking complex network theory into supply chain network research, the paper applies complex network theory into the agile supply chain network research, analyzes the complexity of agile supply chain network, presents the evolutionary mechanism of agile supply chain network based on complex network theory, and uses Matlab to simulate degree distribution, average path length, clustering coefficient, and node betweenness. Simulation results show that the evolution result displays the scale-free property. It lays the foundations of further research on agile supply chain network based on complex network theory.
Surface Complexation Model for Strontium Sorption to Amorphous Silica and Goethite
Energy Technology Data Exchange (ETDEWEB)
Carroll, S; Robers, S; Criscenti, L; O' Day, P
2007-11-30
Strontium sorption to amorphous silica and goethite was measured as a function of pH and dissolved strontium and carbonate concentrations at 25 C. Strontium sorption gradually increases from 0 to 100% from pH 6 to 10 for both phases and requires multiple outer-sphere surface complexes to fit the data. All data are modeled using the triple layer model and the site-occupancy standard state; unless stated otherwise all strontium complexes are mononuclear. Strontium sorption to amorphous silica in the presence and absence of dissolved carbonate can be fit with tetradentate Sr{sup 2+} and SrOH{sup +} complexes on the {beta}-plane and a monodentate Sr{sup 2+} complex on the diffuse plane to account for strontium sorption at low ionic strength. Strontium sorption to goethite in the absence of dissolved carbonate can be fit with monodentate and tetradentate SrOH{sup +} complexes and a tetradentate binuclear Sr{sup 2+} species on the {beta}-plane. The binuclear complex is needed to account for enhanced sorption at high strontium surface loadings. In the presence of dissolved carbonate additional monodentate Sr{sup 2+} and SrOH{sup +} carbonate surface complexes on the {beta}-plane are needed to fit strontium sorption to goethite. Modeling strontium sorption as outer-sphere complexes is consistent with quantitative analysis of extended X-ray absorption fine structure (EXAFS) on selected sorption samples that show a single first shell of oxygen atoms around strontium indicating hydrated surface complexes at the amorphous silica and goethite surfaces. Strontium surface complexation equilibrium constants determined in this study combined with other alkaline earth surface complexation constants are used to recalibrate a predictive model based on Born solvation and crystal-chemistry theory. The model is accurate to about 0.7 log K units. More studies are needed to determine the dependence of alkaline earth sorption on ionic strength and dissolved carbonate and sulfate
Surface complexation model for strontium sorption to amorphous silica and goethite
Directory of Open Access Journals (Sweden)
Criscenti Louise J
2008-01-01
Full Text Available Abstract Strontium sorption to amorphous silica and goethite was measured as a function of pH and dissolved strontium and carbonate concentrations at 25°C. Strontium sorption gradually increases from 0 to 100% from pH 6 to 10 for both phases and requires multiple outer-sphere surface complexes to fit the data. All data are modeled using the triple layer model and the site-occupancy standard state; unless stated otherwise all strontium complexes are mononuclear. Strontium sorption to amorphous silica in the presence and absence of dissolved carbonate can be fit with tetradentate Sr2+ and SrOH+ complexes on the β-plane and a monodentate Sr2+complex on the diffuse plane to account for strontium sorption at low ionic strength. Strontium sorption to goethite in the absence of dissolved carbonate can be fit with monodentate and tetradentate SrOH+ complexes and a tetradentate binuclear Sr2+ species on the β-plane. The binuclear complex is needed to account for enhanced sorption at hgh strontium surface loadings. In the presence of dissolved carbonate additional monodentate Sr2+ and SrOH+ carbonate surface complexes on the β-plane are needed to fit strontium sorption to goethite. Modeling strontium sorption as outer-sphere complexes is consistent with quantitative analysis of extended X-ray absorption fine structure (EXAFS on selected sorption samples that show a single first shell of oxygen atoms around strontium indicating hydrated surface complexes at the amorphous silica and goethite surfaces. Strontium surface complexation equilibrium constants determined in this study combined with other alkaline earth surface complexation constants are used to recalibrate a predictive model based on Born solvation and crystal-chemistry theory. The model is accurate to about 0.7 log K units. More studies are needed to determine the dependence of alkaline earth sorption on ionic strength and dissolved carbonate and sulfate concentrations for the development of
Worldsheet theory of light-cone gauge noncritical strings on higher genus Riemann surfaces
Ishibashi, Nobuyuki; Murakami, Koichi
2016-01-01
It is possible to formulate light-cone gauge string field theory in noncritical dimensions. Such a theory corresponds to conformal gauge worldsheet theory with nonstandard longitudinal part. We study the longitudinal part of the worldsheet theory on higher genus Riemann surfaces. The results in this paper shall be used to study the dimensional regularization of light-cone gauge string field theory.
Surface-complexation modelling for describing adsorption of ...
African Journals Online (AJOL)
2013-06-08
Jun 8, 2013 ... Adsorption of dissolved phosphate onto synthetic hydrous ferric oxide (HFO) was measured in the laboratory as a function of pH, ionic strength, and phosphate relative concentration. Experimental data were used to constrain optimal values of surface complexation reactions using a geochemical modeling ...
Hirshfeld surface analysis of new organotin(IV)-phosphoramide complexes
Czech Academy of Sciences Publication Activity Database
Pourayoubi, M.; Bayraq, S.S.; Tarahhomi, A.; Nečas, M.; Fejfarová, Karla; Dušek, Michal
2014-01-01
Roč. 751, SI (2014), s. 508-518 ISSN 0022-328X R&D Projects: GA ČR(CZ) GAP204/11/0809 Institutional support: RVO:68378271 Keywords : organotin(IV)-phosphoramide complexes * Hirshfeld surfaces * two-dimensional fingerprint plots * crystal packing Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.173, year: 2014
On the quantisation of complex higher derivative theories and avoiding the Ostrogradsky ghost
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Martti Raidal
2017-03-01
Full Text Available Generic higher derivative theories are believed to be fundamentally unphysical because they contain Ostrogradsky ghosts. We show that within complex classical mechanics it is possible to construct higher derivative theories that circumvent the Ostrogradsky theorem and have a real energy spectrum that is bounded from below. The complex theory can be canonically quantised. The resulting quantum theory does not suffer from the kinetic instability and maintains the usual probabilistic interpretation without violating the correspondence principle. As a proof of concept, we construct a class of stable interacting complex higher derivative theories and present a concrete example. This consistent and canonical framework allows us to analyse the previous attempts to avoid ghosts that use non-canonical quantisation schemes, such as the Lee–Wick theories, Dirac–Pauli quantisation or PT-symmetric quantum mechanics. The key to understand the would-be ghosts in any kinetically stable higher derivative theory is to accept the complex system behind it.
Photoelectrochemical etching of gallium nitride surface by complexation dissolution mechanism
Energy Technology Data Exchange (ETDEWEB)
Zhang, Miao-Rong [Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, 215123 Suzhou (China); University of Chinese Academy of Sciences, 100049 Beijing (China); Hou, Fei; Wang, Zu-Gang; Zhang, Shao-Hui [Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, 215123 Suzhou (China); Changchun University of Science and Technology, 130022 Changchun (China); Pan, Ge-Bo, E-mail: gbpan2008@sinano.ac.cn [Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, 215123 Suzhou (China)
2017-07-15
Graphical abstract: GaN surface was etched by 0.3 M EDTA-2Na. The proposed complexation dissolution mechanism can be applicable to almost all neutral etchants under the prerequisite of strong light and electric field. - Highlights: • GaN surface was etched by EDTA-2Na. • GaN may be dissolved into EDTA-2Na by forming Ga–EDTA complex. • We propose the complexation dissolution mechanism for the first time. - Abstract: Gallium nitride (GaN) surface was etched by 0.3 M ethylenediamine tetraacetic acid disodium (EDTA-2Na) via photoelectrochemical etching technique. SEM images reveal the etched GaN surface becomes rough and irregular. The pore density is up to 1.9 × 10{sup 9} per square centimeter after simple acid post-treatment. The difference of XPS spectra of Ga 3d, N 1s and O 1s between the non-etched and freshly etched GaN surfaces can be attributed to the formation of Ga–EDTA complex at the etching interface between GaN and EDTA-2Na. The proposed complexation dissolution mechanism can be broadly applicable to almost all neutral etchants under the prerequisite of strong light and electric field. From the point of view of environment, safety and energy, EDTA-2Na has obvious advantages over conventionally corrosive etchants. Moreover, as the further and deeper study of such nearly neutral etchants, GaN etching technology has better application prospect in photoelectric micro-device fabrication.
Photoelectrochemical etching of gallium nitride surface by complexation dissolution mechanism
International Nuclear Information System (INIS)
Zhang, Miao-Rong; Hou, Fei; Wang, Zu-Gang; Zhang, Shao-Hui; Pan, Ge-Bo
2017-01-01
Graphical abstract: GaN surface was etched by 0.3 M EDTA-2Na. The proposed complexation dissolution mechanism can be applicable to almost all neutral etchants under the prerequisite of strong light and electric field. - Highlights: • GaN surface was etched by EDTA-2Na. • GaN may be dissolved into EDTA-2Na by forming Ga–EDTA complex. • We propose the complexation dissolution mechanism for the first time. - Abstract: Gallium nitride (GaN) surface was etched by 0.3 M ethylenediamine tetraacetic acid disodium (EDTA-2Na) via photoelectrochemical etching technique. SEM images reveal the etched GaN surface becomes rough and irregular. The pore density is up to 1.9 × 10 9 per square centimeter after simple acid post-treatment. The difference of XPS spectra of Ga 3d, N 1s and O 1s between the non-etched and freshly etched GaN surfaces can be attributed to the formation of Ga–EDTA complex at the etching interface between GaN and EDTA-2Na. The proposed complexation dissolution mechanism can be broadly applicable to almost all neutral etchants under the prerequisite of strong light and electric field. From the point of view of environment, safety and energy, EDTA-2Na has obvious advantages over conventionally corrosive etchants. Moreover, as the further and deeper study of such nearly neutral etchants, GaN etching technology has better application prospect in photoelectric micro-device fabrication.
Using Theory Integration to Explore Complex Health Problems.
Quinn, Brenna L
2016-01-01
Although nursing leaders call for theory utilization in research, use remains low within the discipline. The purpose of this article is to explore the application of interdisciplinary integration of models and theories to nursing research. An example of theory integration for the purposes of guiding a study relevant to school nursing is described. A conceptual-theoretical-empirical structure based on the Neuman's systems model, a nursing theory, integrated with the social communication model of pain, a psychology model, was developed to guide the study to examine pain assessment for schoolchildren with intellectual and developmental disabilities.
Surface active complexes formed between keratin polypeptides and ionic surfactants.
Pan, Fang; Lu, Zhiming; Tucker, Ian; Hosking, Sarah; Petkov, Jordan; Lu, Jian R
2016-12-15
Keratins are a group of important proteins in skin and hair and as biomaterials they can provide desirable properties such as strength, biocompatibility, and moisture regaining and retaining. The aim of this work is to develop water-soluble keratin polypeptides from sheep wool and then explore how their surface adsorption behaves with and without surfactants. Successful preparation of keratin samples was demonstrated by identification of the key components from gel electrophoresis and the reproducible production of gram scale samples with and without SDS (sodium dodecylsulphate) during wool fibre dissolution. SDS micelles could reduce the formation of disulphide bonds between keratins during extraction, reducing inter-molecular crosslinking and improving keratin polypeptide solubility. However, Zeta potential measurements of the two polypeptide batches demonstrated almost identical pH dependent surface charge distributions with isoelectric points around pH 3.5, showing complete removal of SDS during purification by dialysis. In spite of different solubility from the two batches of keratin samples prepared, very similar adsorption and aggregation behavior was revealed from surface tension measurements and dynamic light scattering. Mixing of keratin polypeptides with SDS and C 12 TAB (dodecyltrimethylammonium bromide) led to the formation of keratin-surfactant complexes that were substantially more effective at reducing surface tension than the polypeptides alone, showing great promise in the delivery of keratin polypeptides via the surface active complexes. Neutron reflection measurements revealed the coexistence of surfactant and keratin polypeptides at the interface, thus providing the structural support to the observed surface tension changes associated with the formation of the surface active complexes. Copyright © 2016. Published by Elsevier Inc.
Assessment of WRF Surface Layer Formulations Over a Complex Terrain
Srivastava, P.; Sharan, M.
2017-12-01
The accurate and efficient estimation of surface turbulent fluxes is crucial to predict an adequate atmospheric evolution by atmospheric models. The Monin-Obukhov similarity theory, which is used to compute these fluxes in numerical models, utilizes the empirical stability correction functions. In the present study, impact of various functional forms of similarity functions on the computation of the surface fluxes under both unstable and stable stratification is analyzed. In addition, this study compares two surface layer parametrization schemes in the Weather Research and Forecasting model over Ranchi (India). The model is run with three nested domains at a high resolution (1 Km) for `five' 4-day periods covering 15 days of Premonsoon season. The two surface layer schemes chosen for the analysis includes MM5 surface layer scheme having Businger-Dyer similarity functions, and revised MM5 scheme utilizing the functions those are valid for full ranges of atmospheric stabilities. The five planetary boundary layer (PBL) schemes are selected to assess the influence of the surface layer schemes on the structure of the boundary layer. The schemes are- Asymmetric Convective Model Version 2 (ACM2), Bougeault-Lacarrere (Boulac), Medium Range Forecast (MRF), Mellor-Yamada-Nakanishi-Niino (MYNN), and Yonsei University (YSU) PBL schemes. The impact of surface layer parametrizations on the near surface diagnostic variables is analyzed and results are compared with the observations.The bias in the 2 m temperature (T2) and 10 m wind speed (U) across the PBL schemes is very small and each PBL scheme is able to reproduce the diurnal variation of T2 irrespective of the surface layer scheme used for the simulations. A relatively higher value nocturnal T2 is predicted with the revised MM5 surface layer scheme as compared to that obtained with the old MM5 scheme, while both the surface layer schemes reproduce almost similar T2 during convective conditions. However, compare to the
Neutrality Versus Materiality: A Thermodynamic Theory of Neutral Surfaces
Directory of Open Access Journals (Sweden)
Rémi Tailleux
2016-09-01
Full Text Available In this paper, a theory for constructing quasi-neutral density variables γ directly in thermodynamic space is formulated, which is based on minimising the absolute value of a purely thermodynamic quantity J n . Physically, J n has a dual dynamic/thermodynamic interpretation as the quantity controlling the energy cost of adiabatic and isohaline parcel exchanges on material surfaces, as well as the dependence of in-situ density on spiciness, in a description of water masses based on γ, spiciness and pressure. Mathematically, minimising | J n | in thermodynamic space is showed to be equivalent to maximising neutrality in physical space. The physics of epineutral dispersion is also reviewed and discussed. It is argued, in particular, that epineutral dispersion is best understood as the aggregate effect of many individual non-neutral stirring events (being understood here as adiabatic and isohaline events with non-zero buoyancy, so that it is only the net displacement aggregated over many events that is approximately neutral. This new view resolves an apparent paradox between the focus in neutral density theory on zero-buoyancy motions and the overwhelming evidence that lateral dispersion in the ocean is primarily caused by non-zero buoyancy processes such as tides, residual currents and sheared internal waves. The efficiency by which a physical process contributes to lateral dispersion can be characterised by its energy signature, with those processes releasing available potential energy (negative energy cost being more efficient than purely neutral processes with zero energy cost. The latter mechanism occurs in the wedge of instability, and its source of energy is the coupling between baroclinicity, thermobaricity, and density compensated temperature/salinity anomalies. Such a mechanism, which can only exist in a salty ocean, is speculated to be important for dissipating spiciness anomalies and neutral helicity. The paper also discusses potential
Antisoiling technology: Theories of surface soiling and performance of antisoiling surface coatings
Cuddihy, E. F.; Willis, P. B.
1984-11-01
Physical examination of surfaces undergoing natural outdoor soiling suggests that soil matter accumulates in up to three distinct layers. The first layer involves strong chemical attachment or strong chemisorption of soil matter on the primary surface. The second layer is physical, consisting of a highly organized arrangement of soil creating a gradation in surface energy from a high associated with the energetic first layer to the lowest possible state on the outer surfce of the second layer. The lowest possible energy state is dictated by the physical nature of the regional atmospheric soiling materials. These first two layers are resistant to removal by rain. The third layer constitutes a settling of loose soil matter, accumulating in dry periods and being removed during rainy periods. Theories and evidence suggest that surfaces that should be naturally resistant to the formation of the first two-resistant layers should be hard, smooth, hydrophobic, free of first-period elements, and have the lowest possible surface energy. These characteristics, evolving as requirements for low-soiling surfaces, suggest that surfaces or surface coatings should be of fluorocarbon chemistry. Evidence for the three-soil-layer concept, and data on the positive performance of candidate fluorocarbon coatings on glass and transparent plastic films after 28 months of outdoor exposure, are presented.
Fluid Mechanics and Complex Variable Theory: Getting Past the 19th Century
Newton, Paul K.
2017-01-01
The subject of fluid mechanics is a rich, vibrant, and rapidly developing branch of applied mathematics. Historically, it has developed hand-in-hand with the elegant subject of complex variable theory. The Westmont College NSF-sponsored workshop on the revitalization of complex variable theory in the undergraduate curriculum focused partly on…
Ab initio theory of magnetic interactions at surfaces
International Nuclear Information System (INIS)
Sousa, C; Graaf, C de; Lopez, N; Harrison, N M; Illas, F
2004-01-01
The low to high spin energy transition of Ni adsorbed on regular and defective sites of MgO(100) and the relative strengths of bulk and surface magnetic coupling constants of first row transition metal oxides (MnO, FeO, CoO, NiO and CuO) are taken as examples to illustrate some deficiencies of density functional theory (DFT). For these ionic systems a cluster/periodic comparison within the same computational method (either DFT or Hartree-Fock) is used to establish that embedded cluster models provide an adequate representation. The cluster model approach is then used to obtain accurate values for the magnetic properties of interest by using explicitly correlated wavefunction methods which handle the electronic open shell rigorously as spin eigenfunctions
Mrugalla, Florian; Kast, Stefan M.
2016-09-01
Complex formation between molecules in solution is the key process by which molecular interactions are translated into functional systems. These processes are governed by the binding or free energy of association which depends on both direct molecular interactions and the solvation contribution. A design goal frequently addressed in pharmaceutical sciences is the optimization of chemical properties of the complex partners in the sense of minimizing their binding free energy with respect to a change in chemical structure. Here, we demonstrate that liquid-state theory in the form of the solute-solute equation of the reference interaction site model provides all necessary information for such a task with high efficiency. In particular, computing derivatives of the potential of mean force (PMF), which defines the free-energy surface of complex formation, with respect to potential parameters can be viewed as a means to define a direction in chemical space toward better binders. We illustrate the methodology in the benchmark case of alkali ion binding to the crown ether 18-crown-6 in aqueous solution. In order to examine the validity of the underlying solute-solute theory, we first compare PMFs computed by different approaches, including explicit free-energy molecular dynamics simulations as a reference. Predictions of an optimally binding ion radius based on free-energy derivatives are then shown to yield consistent results for different ion parameter sets and to compare well with earlier, orders-of-magnitude more costly explicit simulation results. This proof-of-principle study, therefore, demonstrates the potential of liquid-state theory for molecular design problems.
International Nuclear Information System (INIS)
Mrugalla, Florian; Kast, Stefan M
2016-01-01
Complex formation between molecules in solution is the key process by which molecular interactions are translated into functional systems. These processes are governed by the binding or free energy of association which depends on both direct molecular interactions and the solvation contribution. A design goal frequently addressed in pharmaceutical sciences is the optimization of chemical properties of the complex partners in the sense of minimizing their binding free energy with respect to a change in chemical structure. Here, we demonstrate that liquid-state theory in the form of the solute–solute equation of the reference interaction site model provides all necessary information for such a task with high efficiency. In particular, computing derivatives of the potential of mean force (PMF), which defines the free-energy surface of complex formation, with respect to potential parameters can be viewed as a means to define a direction in chemical space toward better binders. We illustrate the methodology in the benchmark case of alkali ion binding to the crown ether 18-crown-6 in aqueous solution. In order to examine the validity of the underlying solute–solute theory, we first compare PMFs computed by different approaches, including explicit free-energy molecular dynamics simulations as a reference. Predictions of an optimally binding ion radius based on free-energy derivatives are then shown to yield consistent results for different ion parameter sets and to compare well with earlier, orders-of-magnitude more costly explicit simulation results. This proof-of-principle study, therefore, demonstrates the potential of liquid-state theory for molecular design problems. (paper)
Turing’s algorithmic lens: From computability to complexity theory
Directory of Open Access Journals (Sweden)
Díaz, Josep
2013-12-01
Full Text Available The decidability question, i.e., whether any mathematical statement could be computationally proven true or false, was raised by Hilbert and remained open until Turing answered it in the negative. Then, most efforts in theoretical computer science turned to complexity theory and the need to classify decidable problems according to their difficulty. Among others, the classes P (problems solvable in polynomial time and NP (problems solvable in non-deterministic polynomial time were defined, and one of the most challenging scientific quests of our days arose: whether P = NP. This still open question has implications not only in computer science, mathematics and physics, but also in biology, sociology and economics, and it can be seen as a direct consequence of Turing’s way of looking through the algorithmic lens at different disciplines to discover how pervasive computation is.La cuestión de la decidibilidad, es decir, si es posible demostrar computacionalmente que una expresión matemática es verdadera o falsa, fue planteada por Hilbert y permaneció abierta hasta que Turing la respondió de forma negativa. Establecida la no-decidibilidad de las matemáticas, los esfuerzos en informática teórica se centraron en el estudio de la complejidad computacional de los problemas decidibles. En este artículo presentamos una breve introducción a las clases P (problemas resolubles en tiempo polinómico y NP (problemas resolubles de manera no determinista en tiempo polinómico, al tiempo que exponemos la dificultad de establecer si P = NP y las consecuencias que se derivarían de que ambas clases de problemas fueran iguales. Esta cuestión tiene implicaciones no solo en los campos de la informática, las matemáticas y la física, sino también para la biología, la sociología y la economía. La idea seminal del estudio de la complejidad computacional es consecuencia directa del modo en que Turing abordaba problemas en diferentes ámbitos mediante lo
Exponential complexity and ontological theories of quantum mechanics
International Nuclear Information System (INIS)
Montina, A.
2008-01-01
Ontological theories of quantum mechanics describe a single system by means of well-defined classical variables and attribute the quantum uncertainties to our ignorance about the underlying reality represented by these variables. We consider the general class of ontological theories describing a quantum system by a set of variables with Markovian (either deterministic or stochastic) evolution. We provide proof that the number of continuous variables cannot be smaller than 2N-2, N being the Hilbert-space dimension. Thus, any ontological Markovian theory of quantum mechanics requires a number of variables which grows exponentially with the physical size. This result is relevant also in the framework of quantum Monte Carlo methods
Complexity theory in the management of communicable diseases.
Simmons, Mike
2003-06-01
In nature, apparently complex behavioural patterns are the result of repetitive simple rules. Complexity science studies the application of these rules and looks for applications in society. Complexity management opportunities have developed from this science and are providing a revolutionary approach in the constantly changing workplace. This article discusses how complexity management techniques have already been applied to communicable disease management in Wales and suggests further developments. A similar approach is recommended to others in the field, while complexity management probably has wider applications in the NHS, not least in relation to the developing managed clinical networks.
Retrieving complex surface impedances from statistical absorption coefficients
DEFF Research Database (Denmark)
Mondet, Boris Jean-Francois; Brunskog, Jonas; Jeong, Cheol-Ho
2017-01-01
coefficients, prior information about the absorber of interest can be used as constraints, which is shown to help determine the correct impedance from absorption coefficient. Further stability and sensitivity investigations indicate that the method presented constitutes an efficient solution to convert sound......In room acoustic simulations the surface materials are commonly represented with energy parameters, such as the absorption and scattering coefficients, which do not carry phase information. This paper presents a method to transform statistical absorption coefficients into complex surface impedances...... that the impedance found has a physical meaning and respects causality in the time domain. Known material models, such as Miki’s and Maa’s models, are taken as references to assess the validity of the suggested model. Due to the non-uniqueness of retrieving complex-valued impedances from real-valued absorption...
Rodriguez, Ernesto; Kim, Yunjin; Durden, Stephen L.
1992-01-01
A numerical evaluation is presented of the regime of validity for various rough surface scattering theories against numerical results obtained by employing the method of moments. The contribution of each theory is considered up to second order in the perturbation expansion for the surface current. Considering both vertical and horizontal polarizations, the unified perturbation method provides best results among all theories weighed.
Self-Organization during Friction in Complex Surface Engineered Tribosystems
Directory of Open Access Journals (Sweden)
Ben D. Beake
2010-02-01
Full Text Available Self-organization during friction in complex surface engineered tribosystems is investigated. The probability of self-organization in these complex tribosystems is studied on the basis of the theoretical concepts of irreversible thermodynamics. It is shown that a higher number of interrelated processes within the system result in an increased probability of self-organization. The results of this thermodynamic model are confirmed by the investigation of the wear performance of a novel Ti0.2Al0.55Cr0.2Si0.03Y0.02N/Ti0.25Al0.65Cr0.1N (PVD coating with complex nano-multilayered structure under extreme tribological conditions of dry high-speed end milling of hardened H13 tool steel.
Exploring complex networks via topological embedding on surfaces.
Aste, Tomaso; Gramatica, Ruggero; Di Matteo, T
2012-09-01
We demonstrate that graphs embedded on surfaces are a powerful and practical tool to generate, to characterize, and to simulate networks with a broad range of properties. Any network can be embedded on a surface with sufficiently high genus and therefore the study of topologically embedded graphs is non-restrictive. We show that the local properties of the network are affected by the surface genus which determines the average degree, which influences the degree distribution, and which controls the clustering coefficient. The global properties of the graph are also strongly affected by the surface genus which is constraining the degree of interwovenness, changing the scaling properties of the network from large-world kind (small genus) to small- and ultrasmall-world kind (large genus). Two elementary moves allow the exploration of all networks embeddable on a given surface and naturally introduce a tool to develop a statistical mechanics description for these networks. Within such a framework, we study the properties of topologically embedded graphs which dynamically tend to lower their energy towards a ground state with a given reference degree distribution. We show that the cooling dynamics between high and low "temperatures" is strongly affected by the surface genus with the manifestation of a glass-like transition occurring when the distance from the reference distribution is low. We prove, with examples, that topologically embedded graphs can be built in a way to contain arbitrary complex networks as subgraphs. This method opens a new avenue to build geometrically embedded networks on hyperbolic manifolds.
Surface Complexation Modelling in Metal-Mineral-Bacteria Systems
Johnson, K. J.; Fein, J. B.
2002-12-01
The reactive surfaces of bacteria and minerals can determine the fate, transport, and bioavailability of aqueous heavy metal cations. Geochemical models are instrumental in accurately accounting for the partitioning of the metals between mineral surfaces and bacteria cell walls. Previous research has shown that surface complexation modelling (SCM) is accurate in two-component systems (metal:mineral and metal:bacteria); however, the ability of SCMs to account for metal distribution in mixed metal-mineral-bacteria systems has not been tested. In this study, we measure aqueous Cd distributions in water-bacteria-mineral systems, and compare these observations with predicted distributions based on a surface complexation modelling approach. We measured Cd adsorption in 2- and 3-component batch adsorption experiments. In the 2-component experiments, we measured the extent of adsorption of 10 ppm aqueous Cd onto either a bacterial or hydrous ferric oxide sorbent. The metal:bacteria experiments contained 1 g/L (wet wt.) of B. subtilis, and were conducted as a function of pH; the metal:mineral experiments were conducted as a function of both pH and HFO content. Two types of 3-component Cd adsorption experiments were also conducted in which both mineral powder and bacteria were present as sorbents: 1) one in which the HFO was physically but not chemically isolated from the system using sealed dialysis tubing, and 2) others where the HFO, Cd and B. subtilis were all in physical contact. The dialysis tubing approach enabled the direct determination of the concentration of Cd on each sorbing surface, after separation and acidification of each sorbent. The experiments indicate that both bacteria and mineral surfaces can dominate adsorption in the system, depending on pH and bacteria:mineral ratio. The stability constants, determined using the data from the 2-component systems, along with those for other surface and aqueous species in the systems, were used with FITEQL to
A 2-D model for friction of complex anisotropic surfaces
Costagliola, Gianluca; Bosia, Federico; Pugno, Nicola M.
2018-03-01
The friction force observed at macroscale is the result of interactions at various lower length scales that are difficult to model in a combined manner. For this reason, simplified approaches are required, depending on the specific aspect to be investigated. In particular, the dimensionality of the system is often reduced, especially in models designed to provide a qualitative description of frictional properties of elastic materials, e.g. the spring-block model. In this paper, we implement for the first time a two dimensional extension of the spring-block model, applying it to structured surfaces and investigating by means of numerical simulations the frictional behaviour of a surface in the presence of features like cavities, pillars or complex anisotropic structures. We show how friction can be effectively tuned by appropriate design of such surface features.
Murrinh-Patha Complex Verbs : Syntactic Theory and Computational Implementation
Seiss, Melanie
2013-01-01
Murrinh-Patha is a non-Pama-Nyungan language spoken in and around Wadeye in the Northern Territory of Australia. It is a highly polysynthetic language with a complex verbal structure. The Murrinh-Patha verb morphology is not only complex due to the large number of morphemes that a verb may consist of, but also due to a high degree of syncretism that these morphemes display. Additionally, complex interdependencies exist between the morphemes. The system is further complicated by a complex inte...
Methods of Approximation Theory in Complex Analysis and Mathematical Physics
Saff, Edward
1993-01-01
The book incorporates research papers and surveys written by participants ofan International Scientific Programme on Approximation Theory jointly supervised by Institute for Constructive Mathematics of University of South Florida at Tampa, USA and the Euler International Mathematical Instituteat St. Petersburg, Russia. The aim of the Programme was to present new developments in Constructive Approximation Theory. The topics of the papers are: asymptotic behaviour of orthogonal polynomials, rational approximation of classical functions, quadrature formulas, theory of n-widths, nonlinear approximation in Hardy algebras,numerical results on best polynomial approximations, wavelet analysis. FROM THE CONTENTS: E.A. Rakhmanov: Strong asymptotics for orthogonal polynomials associated with exponential weights on R.- A.L. Levin, E.B. Saff: Exact Convergence Rates for Best Lp Rational Approximation to the Signum Function and for Optimal Quadrature in Hp.- H. Stahl: Uniform Rational Approximation of x .- M. Rahman, S.K. ...
Smart modeling and simulation for complex systems practice and theory
Ren, Fenghui; Zhang, Minjie; Ito, Takayuki; Tang, Xijin
2015-01-01
This book aims to provide a description of these new Artificial Intelligence technologies and approaches to the modeling and simulation of complex systems, as well as an overview of the latest scientific efforts in this field such as the platforms and/or the software tools for smart modeling and simulating complex systems. These tasks are difficult to accomplish using traditional computational approaches due to the complex relationships of components and distributed features of resources, as well as the dynamic work environments. In order to effectively model the complex systems, intelligent technologies such as multi-agent systems and smart grids are employed to model and simulate the complex systems in the areas of ecosystem, social and economic organization, web-based grid service, transportation systems, power systems and evacuation systems.
Complex fluids in biological systems experiment, theory, and computation
2015-01-01
This book serves as an introduction to the continuum mechanics and mathematical modeling of complex fluids in living systems. The form and function of living systems are intimately tied to the nature of surrounding fluid environments, which commonly exhibit nonlinear and history dependent responses to forces and displacements. With ever-increasing capabilities in the visualization and manipulation of biological systems, research on the fundamental phenomena, models, measurements, and analysis of complex fluids has taken a number of exciting directions. In this book, many of the world’s foremost experts explore key topics such as: Macro- and micro-rheological techniques for measuring the material properties of complex biofluids and the subtleties of data interpretation Experimental observations and rheology of complex biological materials, including mucus, cell membranes, the cytoskeleton, and blood The motility of microorganisms in complex fluids and the dynamics of active suspensions Challenges and solut...
Krywonos, Andrey; Harvey, James E; Choi, Narak
2011-06-01
Scattering effects from microtopographic surface roughness are merely nonparaxial diffraction phenomena resulting from random phase variations in the reflected or transmitted wavefront. Rayleigh-Rice, Beckmann-Kirchhoff. or Harvey-Shack surface scatter theories are commonly used to predict surface scatter effects. Smooth-surface and/or paraxial approximations have severely limited the range of applicability of each of the above theoretical treatments. A recent linear systems formulation of nonparaxial scalar diffraction theory applied to surface scatter phenomena resulted first in an empirically modified Beckmann-Kirchhoff surface scatter model, then a generalized Harvey-Shack theory that produces accurate results for rougher surfaces than the Rayleigh-Rice theory and for larger incident and scattered angles than the classical Beckmann-Kirchhoff and the original Harvey-Shack theories. These new developments simplify the analysis and understanding of nonintuitive scattering behavior from rough surfaces illuminated at arbitrary incident angles.
Bulk and boundary invariants for complex topological insulators from K-theory to physics
Prodan, Emil
2016-01-01
This monograph offers an overview of rigorous results on fermionic topological insulators from the complex classes, namely, those without symmetries or with just a chiral symmetry. Particular focus is on the stability of the topological invariants in the presence of strong disorder, on the interplay between the bulk and boundary invariants and on their dependence on magnetic fields. The first part presents motivating examples and the conjectures put forward by the physics community, together with a brief review of the experimental achievements. The second part develops an operator algebraic approach for the study of disordered topological insulators. This leads naturally to use analysis tools from K-theory and non-commutative geometry, such as cyclic cohomology, quantized calculus with Fredholm modules and index pairings. New results include a generalized Streda formula and a proof of the delocalized nature of surface states in topological insulators with non-trivial invariants. The concluding chapter connect...
Differential topology of complex surfaces elliptic surfaces with p g=1 smooth classification
Morgan, John W
1993-01-01
This book is about the smooth classification of a certain class of algebraicsurfaces, namely regular elliptic surfaces of geometric genus one, i.e. elliptic surfaces with b1 = 0 and b2+ = 3. The authors give a complete classification of these surfaces up to diffeomorphism. They achieve this result by partially computing one of Donalson's polynomial invariants. The computation is carried out using techniques from algebraic geometry. In these computations both thebasic facts about the Donaldson invariants and the relationship of the moduli space of ASD connections with the moduli space of stable bundles are assumed known. Some familiarity with the basic facts of the theory of moduliof sheaves and bundles on a surface is also assumed. This work gives a good and fairly comprehensive indication of how the methods of algebraic geometry can be used to compute Donaldson invariants.
Complexity Leadership Theory: A United States Marine Corps Historical Overlay
2017-05-25
and decision-making, organizational theory, history, and psychology each provide unique challenges for empirical-analytical research, the...service’s ability to innovate across the gap between organizational resources and an “uncertain” and “complex” future operating environment. As the...Aggregation – A process that occurs when agents bond into aggregates, then meta-aggregates, and potentially organizational transition. Linking-up
Energetic Surface Smoothing of Complex Metal-Oxide Thin Films
International Nuclear Information System (INIS)
Willmott, P.R.; Herger, R.; Schlepuetz, C.M.; Martoccia, D.; Patterson, B.D.
2006-01-01
A novel energetic smoothing mechanism in the growth of complex metal-oxide thin films is reported from in situ kinetic studies of pulsed laser deposition of La 1-x Sr x MnO 3 on SrTiO 3 , using x-ray reflectivity. Below 50% monolayer coverage, prompt insertion of energetic impinging species into small-diameter islands causes them to break up to form daughter islands. This smoothing mechanism therefore inhibits the formation of large-diameter 2D islands and the seeding of 3D growth. Above 50% coverage, islands begin to coalesce and their breakup is thereby suppressed. The energy of the incident flux is instead rechanneled into enhanced surface diffusion, which leads to an increase in the effective surface temperature of ΔT≅500 K. These results have important implications on optimal conditions for nanoscale device fabrication using these materials
Directory of Open Access Journals (Sweden)
Krishnamoorthy Arumugam
2014-04-01
Full Text Available Applications of redox processes range over a number of scientific fields. This review article summarizes the theory behind the calculation of redox potentials in solution for species such as organic compounds, inorganic complexes, actinides, battery materials, and mineral surface-bound-species. Different computational approaches to predict and determine redox potentials of electron transitions are discussed along with their respective pros and cons for the prediction of redox potentials. Subsequently, recommendations are made for certain necessary computational settings required for accurate calculation of redox potentials. This article reviews the importance of computational parameters, such as basis sets, density functional theory (DFT functionals, and relativistic approaches and the role that physicochemical processes play on the shift of redox potentials, such as hydration or spin orbit coupling, and will aid in finding suitable combinations of approaches for different chemical and geochemical applications. Identifying cost-effective and credible computational approaches is essential to benchmark redox potential calculations against experiments. Once a good theoretical approach is found to model the chemistry and thermodynamics of the redox and electron transfer process, this knowledge can be incorporated into models of more complex reaction mechanisms that include diffusion in the solute, surface diffusion, and dehydration, to name a few. This knowledge is important to fully understand the nature of redox processes be it a geochemical process that dictates natural redox reactions or one that is being used for the optimization of a chemical process in industry. In addition, it will help identify materials that will be useful to design catalytic redox agents, to come up with materials to be used for batteries and photovoltaic processes, and to identify new and improved remediation strategies in environmental engineering, for example the
Economic Decision Making: Application of the Theory of Complex Systems
Kitt, Robert
In this chapter the complex systems are discussed in the context of economic and business policy and decision making. It will be showed and motivated that social systems are typically chaotic, non-linear and/or non-equilibrium and therefore complex systems. It is discussed that the rapid change in global consumer behaviour is underway, that further increases the complexity in business and management. For policy making under complexity, following principles are offered: openness and international competition, tolerance and variety of ideas, self-reliability and low dependence on external help. The chapter contains four applications that build on the theoretical motivation of complexity in social systems. The first application demonstrates that small economies have good prospects to gain from the global processes underway, if they can demonstrate production flexibility, reliable business ethics and good risk management. The second application elaborates on and discusses the opportunities and challenges in decision making under complexity from macro and micro economic perspective. In this environment, the challenges for corporate management are being also permanently changed: the balance between short term noise and long term chaos whose attractor includes customers, shareholders and employees must be found. The emergence of chaos in economic relationships is demonstrated by a simple system of differential equations that relate the stakeholders described above. The chapter concludes with two financial applications: about debt and risk management. The non-equilibrium economic establishment leads to additional problems by using excessive borrowing; unexpected downturns in economy can more easily kill companies. Finally, the demand for quantitative improvements in risk management is postulated. Development of the financial markets has triggered non-linearity to spike in prices of various production articles such as agricultural and other commodities that has added market
Complex Psychological Trauma and Self-Dysregulation: A Theory Synthesis for Nursing.
Choi, Kristen R
2016-01-01
Complex psychological trauma is a phenomenon resulting from severe interpersonal trauma that can negatively affect how individuals experience health care. However, few theories conceptualizing complex trauma exist, and it has received only limited attention in the nursing literature. The purpose of this theory synthesis was to organize two theories of (a) self-regulation and (b) self-dysregulation following complex psychological trauma into a single conceptual framework for use in nursing practice. This article used the theory synthesis approach described by Walker and Avant. The theory has potential to advance nursing science by helping nurses and other health professionals understand how trauma can alter self-regulatory processes and result in unique challenges in care delivery. It also has potential to prevent retraumatization of trauma survivors at the hands of health care providers.
Impossibility of Independence Amplification in Kolmogorov Complexity Theory
Zimand, Marius
The paper studies randomness extraction from sources with bounded independence and the issue of independence amplification of sources, using the framework of Kolmogorov complexity. The dependency of strings x and y is dep(x,y) = max {C(x) - C(x |y), C(y) - C( y|x)}, where C(·) denotes the Kolmogorov complexity. It is shown that there exists a computable Kolmogorov extractor f such that, for any two n-bit strings with complexity s(n) and dependency α(n), it outputs a string of length s(n) with complexity s(n) - α(n) conditioned by any one of the input strings. It is proven that the above are the optimal parameters a Kolmogorov extractor can achieve. It is shown that independence amplification cannot be effectively realized. Specifically, if (after excluding a trivial case) there exist computable functions f 1 and f 2 such that dep(f 1(x,y), f 2(x,y)) ≤ β(n) for all n-bit strings x and y with dep(x,y) ≤ α(n), then β(n) ≥ α(n) - O(logn).
Practical ethical theory for nurses responding to complexity in care.
Fairchild, Roseanne Moody
2010-05-01
In the context of health care system complexity, nurses need responsive leadership and organizational support to maintain intrinsic motivation, moral sensitivity and a caring stance in the delivery of patient care. The current complexity of nurses' work environment promotes decreases in work motivation and moral satisfaction, thus creating motivational and ethical dissonance in practice. These and other work-related factors increase emotional stress and burnout for nurses, prompting both new and seasoned nurse professionals to leave their current position, or even the profession. This article presents a theoretical conceptual model for professional nurses to review and make sense of the ethical reasoning skills needed to maintain a caring stance in relation to the competing values that must coexist among nurses, health care administrators, patients and families in the context of the complex health care work environments in which nurses are expected to practice. A model, Nurses' Ethical Reasoning Skills, is presented as a framework for nurses' thinking through and problem solving ethical issues in clinical practice in the context of complexity in health care.
Complexity theory and genetics: The computational power of crossing over
Czech Academy of Sciences Publication Activity Database
Pudlák, Pavel
2001-01-01
Roč. 171, č. 1 (2001), s. 201-223 ISSN 0890-5401 R&D Projects: GA AV ČR IAA1019901 Institutional research plan: CEZ:AV0Z1019905; CEZ:AV0Z1019905 Keywords : complexity * genetics * croning over Subject RIV: BA - General Mathematics Impact factor: 0.571, year: 2001
Molecular Analyzer for Complex Refractory Organic-Rich Surfaces (MACROS)
Getty, Stephanie A.; Cook, Jamie E.; Balvin, Manuel; Brinckerhoff, William B.; Li, Xiang; Grubisic, Andrej; Cornish, Timothy; Ferrance, Jerome; Southard, Adrian
2017-01-01
The Molecular Analyzer for Complex Refractory Organic-rich Surfaces, MACROS, is a novel instrument package being developed at NASA Goddard Space Flight Center. MACROS enables the in situ characterization of a sample's composition by coupling two powerful techniques into one compact instrument package: (1) laser desorption/ionization time-of-flight mass spectrometry (LDMS) for broad detection of inorganic mineral composition and non-volatile organics, and (2) liquid-phase extraction methods to gently isolate the soluble organic and inorganic fraction of a planetary powder for enrichment and detailed analysis by liquid chromatographic separation coupled to LDMS. The LDMS is capable of positive and negative ion detection, precision mass selection, and fragment analysis. Two modes are included for LDMS: single laser LDMS as the broad survey mode and two step laser mass spectrometry (L2MS). The liquid-phase extraction will be done in a newly designed extraction module (EM) prototype, providing selectivity in the analysis of a complex sample. For the sample collection, a diamond drill front end will be used to collect rock/icy powder. With all these components and capabilities together, MACROS offers a versatile analytical instrument for a mission targeting an icy moon, carbonaceous asteroid, or comet, to fully characterize the surface composition and advance our understanding of the chemical inventory present on that body.
Dai, David Yun
2017-01-01
This article presents a new theory of talent development, evolving complexity theory (ECT), in the context of the changing theoretical directions as well as the landscape of gifted education. I argue that gifted education needs a new foundation that provides a broad psychosocial basis than what the notion of giftedness can afford. A focus on…
Battiston, S.; Farmer, J.D.; Flache, A.; Garlaschelli, D.; Haldane, A.G.; Heesterbeek, H.; Hommes, C.; Jaeger, C.; May, R.; Scheffer, M.
2016-01-01
Traditional economic theory could not explain, much less predict, the near collapse of the financial system and its long-lasting effects on the global economy. Since the 2008 crisis, there has been increasing interest in using ideas from complexity theory to make sense of economic and financial
Periodic density functional theory calculations of bulk and the (010 surface of goethite
Directory of Open Access Journals (Sweden)
Sparks Donald L
2008-05-01
Full Text Available Abstract Background Goethite is a common and reactive mineral in the environment. The transport of contaminants and anaerobic respiration of microbes are significantly affected by adsorption and reduction reactions involving goethite. An understanding of the mineral-water interface of goethite is critical for determining the molecular-scale mechanisms of adsorption and reduction reactions. In this study, periodic density functional theory (DFT calculations were performed on the mineral goethite and its (010 surface, using the Vienna Ab Initio Simulation Package (VASP. Results Calculations of the bulk mineral structure accurately reproduced the observed crystal structure and vibrational frequencies, suggesting that this computational methodology was suitable for modeling the goethite-water interface. Energy-minimized structures of bare, hydrated (one H2O layer and solvated (three H2O layers (010 surfaces were calculated for 1 × 1 and 3 × 3 unit cell slabs. A good correlation between the calculated and observed vibrational frequencies was found for the 1 × 1 solvated surface. However, differences between the 1 × 1 and 3 × 3 slab calculations indicated that larger models may be necessary to simulate the relaxation of water at the interface. Comparison of two hydrated surfaces with molecularly and dissociatively adsorbed H2O showed a significantly lower potential energy for the former. Conclusion Surface Fe-O and (FeO-H bond lengths are reported that may be useful in surface complexation models (SCM of the goethite (010 surface. These bond lengths were found to change significantly as a function of solvation (i.e., addition of two extra H2O layers above the surface, indicating that this parameter should be carefully considered in future SCM studies of metal oxide-water interfaces.
Plane answers to complex questions the theory of linear models
Christensen, Ronald
1987-01-01
This book was written to rigorously illustrate the practical application of the projective approach to linear models. To some, this may seem contradictory. I contend that it is possible to be both rigorous and illustrative and that it is possible to use the projective approach in practical applications. Therefore, unlike many other books on linear models, the use of projections and sub spaces does not stop after the general theory. They are used wherever I could figure out how to do it. Solving normal equations and using calculus (outside of maximum likelihood theory) are anathema to me. This is because I do not believe that they contribute to the understanding of linear models. I have similar feelings about the use of side conditions. Such topics are mentioned when appropriate and thenceforward avoided like the plague. On the other side of the coin, I just as strenuously reject teaching linear models with a coordinate free approach. Although Joe Eaton assures me that the issues in complicated problems freq...
Electromagnetic theories of surface-enhanced Raman spectroscopy.
Ding, Song-Yuan; You, En-Ming; Tian, Zhong-Qun; Moskovits, Martin
2017-07-07
Surface-enhanced Raman spectroscopy (SERS) and related spectroscopies are powered primarily by the concentration of the electromagnetic (EM) fields associated with light in or near appropriately nanostructured electrically-conducting materials, most prominently, but not exclusively high-conductivity metals such as silver and gold. This field concentration takes place on account of the excitation of surface-plasmon (SP) resonances in the nanostructured conductor. Optimizing nanostructures for SERS, therefore, implies optimizing the ability of plasmonic nanostructures to concentrate EM optical fields at locations where molecules of interest reside, and to enhance the radiation efficiency of the oscillating dipoles associated with these molecules and nanostructures. This review summarizes the development of theories over the past four decades pertinent to SERS, especially those contributing to our current understanding of SP-related SERS. Special emphasis is given to the salient strategies and theoretical approaches for optimizing nanostructures with hotspots as efficient EM near-field concentrating and far-field radiating substrates for SERS. A simple model is described in terms of which the upper limit of the SERS enhancement can be estimated. Several experimental strategies that may allow one to approach, or possibly exceed this limit, such as cascading the enhancement of the local and radiated EM field by the multiscale EM coupling of hierarchical structures, and generating hotspots by hybridizing an antenna mode with a plasmonic waveguide cavity mode, which would result in an increased local field enhancement, are discussed. Aiming to significantly broaden the application of SERS to other fields, and especially to material science, we consider hybrid structures of plasmonic nanostructures and other material phases and strategies for producing strong local EM fields at desired locations in such hybrid structures. In this vein, we consider some of the numerical
Spin Propensities of Octahedral Complexes From Density Functional Theory
DEFF Research Database (Denmark)
Mortensen, Sara R.; Kepp, Kasper Planeta
2015-01-01
The fundamental balance between high- and low-spin states of transition metal systems depends on both the metal ion and the ligands surrounding it, as often visualized by the spectrochemical series. Most density functionals do not reproduce this balance, and real spin state propensities depend...... on orbital pairing and vibrational entropies absent in the spectrochemical series. Thus, we systematically computed the tendency toward high or low spin of "text-book" octahedral metal complexes versus ligand and metal type, using eight density functionals. Dispersion effects were generally ... assessment of spin state propensities versus ligand and metal type and reveal, e.g., that CN- is consistently weaker than CO for M(II) but stronger than CO for M(III) and SCN- and NCS- change order in M(II) versus M(III) complexes. Contrary to expectation based on the spectrochemical series, Cl- and Br...
Sinnott, Jan D.
This paper discusses the utility of a general systems theory paradigm for psychology. The paradigm can be used for conceptualizing such complex phenomena as change over time in living systems, person-society interactions, and the epistemology of multiply determined changes. Consideration is also given to applications of the approach to…
Towards socio-material approaches in simulation-based education: lessons from complexity theory.
Fenwick, Tara; Dahlgren, Madeleine Abrandt
2015-04-01
Review studies of simulation-based education (SBE) consistently point out that theory-driven research is lacking. The literature to date is dominated by discourses of fidelity and authenticity - creating the 'real' - with a strong focus on the developing of clinical procedural skills. Little of this writing incorporates the theory and research proliferating in professional studies more broadly, which show how professional learning is embodied, relational and situated in social - material relations. A key concern for medical educators concerns how to better prepare students for the unpredictable and dynamic ambiguity of professional practice; this has stimulated the movement towards socio-material theories in education that address precisely this question. Among the various socio-material theories that are informing new developments in professional education, complexity theory has been of particular importance for medical educators interested in updating current practices. This paper outlines key elements of complexity theory, illustrated with examples from empirical study, to argue its particular relevance for improving SBE. Complexity theory can make visible important material dynamics, and their problematic consequences, that are not often noticed in simulated experiences in medical training. It also offers conceptual tools that can be put to practical use. This paper focuses on concepts of emergence, attunement, disturbance and experimentation. These suggest useful new approaches for designing simulated settings and scenarios, and for effective pedagogies before, during and following simulation sessions. Socio-material approaches such as complexity theory are spreading through research and practice in many aspects of professional education across disciplines. Here, we argue for the transformative potential of complexity theory in medical education using simulation as our focus. Complexity tools open questions about the socio-material contradictions inherent in
Aniagyei, Albert; Tia, Richard; Adei, Evans
2013-08-14
The oxo complexes of group VII B are of great interest for their potential toward epoxidation and dihydroxylation. In this work, the mechanisms of oxidation of ethylene by rhenium-oxo complexes of the type LReO3 (L = O(-), Cl, CH3, OCH3, Cp, NPH3) have been explored at the B3LYP/LACVP* level of theory. The activation barriers and reaction energies for the stepwise and concerted addition pathways involving multiple spin states have been computed. In the reaction of LReO3 (L = O(-), Cl, CH3, OCH3, Cp, NPH3) with ethylene, it was found that the concerted [3 + 2] addition pathway on the singlet potential energy surfaces leading to the formation of a dioxylate intermediate is favored over the [2 + 2] addition pathway leading to the formation of a metallaoxetane intermediate and its re-arrangement to form the dioxylate. The activation barrier for the formation of the dioxylate on the singlet PES for the ligands studied is found to follow the order O(-) > CH3 > NPH3 > CH3O(-) > Cl(-) > Cp and the reaction energies follow the order CH3 > O(-) > NPH3 > CH3O(-) > Cl(-) > Cp. On the doublet PES, the [2 + 2] addition leading to the formation the metallaoxetane intermediate is favored over dioxylate formation for the ligands L = CH3, CH3O(-), Cl(-). The activation barriers for the formation of the metallaoxetane intermediate are found to increase for the ligands in the order CH3 < Cl(-) < CH3O(-) while the reaction energies follow the order Cl(-) < CH3O(-) < CH3. The subsequent re-arrangement of the metallaoxetane intermediate to the dioxylate is only feasible in the case of ReO3(OCH3). Of all the complexes studied, the best dioxylating catalyst is ReO3Cp (singlet surface); the best epoxidation catalyst is ReO3Cl (singlet surface); and the best metallaoxetane formation catalyst is ReO3(NPH3) (triplet surface).
On topological approach to local theory of surfaces in Calabi-Yau threefolds
DEFF Research Database (Denmark)
Gukov, Sergei; Liu, Chiu-Chu Melissa; Sheshmani, Artan
2017-01-01
We study the web of dualities relating various enumerative invariants, notably Gromov-Witten invariants and invariants that arise in topological gauge theory. In particular, we study Donaldson-Thomas gauge theory and its reductions to D=4 and D=2 which are relevant to the local theory of surfaces...
Theory of periodically specified problems: Complexity and approximability
Energy Technology Data Exchange (ETDEWEB)
Marathe, M.V. [Los Alamos National Lab., NM (United States); Hunt, H.B. III; Stearns, R.E.; Rosenkrantz, D.J. [Univ. at Albany - SUNY, NY (United States). Dept. of Computer Science
1997-12-05
We study the complexity and the efficient approximability of graph and satisfiability problems when specified using various kinds of periodic specifications studied. The general results obtained include the following: (1) We characterize the complexities of several basic generalized CNF satisfiability problems SAT(S) [Sc78], when instances are specified using various kinds of 1- and 2-dimensional periodic specifications. We outline how this characterization can be used to prove a number of new hardness results for the complexity classes DSPACE(n), NSPACE(n), DEXPTIME, NEXPTIME, EXPSPACE etc. These results can be used to prove in a unified way the hardness of a number of combinatorial problems when instances are specified succinctly using various succient specifications considered in the literature. As one corollary, we show that a number of basic NP-hard problems because EXPSPACE-hard when inputs are represented using 1-dimensional infinite periodic wide specifications. This answers a long standing open question posed by Orlin. (2) We outline a simple yet a general technique to devise approximation algorithms with provable worst case performance guarantees for a number of combinatorial problems specified periodically. Our efficient approximation algorithms and schemes are based on extensions of the ideas and represent the first non-trivial characterization of a class of problems having an {epsilon}-approximation (or PTAS) for periodically specified NEXPTIME-hard problems. Two of properties of our results are: (i) For the first time, efficient approximation algorithms and schemes have been developed for natural NEXPTIME-complete problems. (ii) Our results are the first polynomial time approximation algorithms with good performance guarantees for hard problems specified using various kinds of periodic specifications considered in this paper.
Simple and Multi-collision of an Ellipsoid with Planar Surfaces. Part I: Theory
Directory of Open Access Journals (Sweden)
Nicolae–Doru Stănescu
2017-11-01
Full Text Available This paper discusses the problem of simultaneous collisions between an ellipsoid and some planar surfaces. The approach is one based on the theory of screws and uses the notion of inertance. The authors consider that the coefficients of restitution are different for each planar surface and they obtain the velocities after the collision. An example concludes the theory.
De Silva, Mary J; Breuer, Erica; Lee, Lucy; Asher, Laura; Chowdhary, Neerja; Lund, Crick; Patel, Vikram
2014-07-05
The Medical Research Councils' framework for complex interventions has been criticized for not including theory-driven approaches to evaluation. Although the framework does include broad guidance on the use of theory, it contains little practical guidance for implementers and there have been calls to develop a more comprehensive approach. A prospective, theory-driven process of intervention design and evaluation is required to develop complex healthcare interventions which are more likely to be effective, sustainable and scalable. We propose a theory-driven approach to the design and evaluation of complex interventions by adapting and integrating a programmatic design and evaluation tool, Theory of Change (ToC), into the MRC framework for complex interventions. We provide a guide to what ToC is, how to construct one, and how to integrate its use into research projects seeking to design, implement and evaluate complex interventions using the MRC framework. We test this approach by using ToC within two randomized controlled trials and one non-randomized evaluation of complex interventions. Our application of ToC in three research projects has shown that ToC can strengthen key stages of the MRC framework. It can aid the development of interventions by providing a framework for enhanced stakeholder engagement and by explicitly designing an intervention that is embedded in the local context. For the feasibility and piloting stage, ToC enables the systematic identification of knowledge gaps to generate research questions that strengthen intervention design. ToC may improve the evaluation of interventions by providing a comprehensive set of indicators to evaluate all stages of the causal pathway through which an intervention achieves impact, combining evaluations of intervention effectiveness with detailed process evaluations into one theoretical framework. Incorporating a ToC approach into the MRC framework holds promise for improving the design and evaluation of complex
Exchange coupling interactions in a Fe6 complex: A theoretical study using density functional theory
International Nuclear Information System (INIS)
Cauchy, Thomas; Ruiz, Eliseo; Alvarez, Santiago
2006-01-01
Theoretical methods based on density functional theory have been employed to analyze the exchange interactions in an Fe 6 complex. The calculated exchange coupling constants are consistent with an S=5 ground state and agree well with those reported previously for other Fe III polynuclear complexes. Ferromagnetic interactions may appear through exchange pathways formed by two bridging hydroxo or oxo ligands
Martin, Susan D.; Dismuke, Sherry
2018-01-01
How to prepare teachers to be effective in our nations' classrooms seems to get increasingly complex, yet the links between teacher education and teachers' eventual practices are little understood. Using complexity theory as a theoretical framework, this mixed-methods study investigated writing teacher practices of 23 elementary teachers. Twelve…
Sine-Gordon quantum mechanics on the complex plane and N=2 gauge theory
International Nuclear Information System (INIS)
He Wei
2010-01-01
We study the relation between the N=2 gauge theory in the Ω background and the quantized integral system recently proposed by Nekrasov and Shatashvili. We focus on the simplest case, the pure Yang-Mills theory with the SU(2) gauge group and the corresponding sine-Gordon integral model on the complex plane. We analyze the periodic wave function and the corresponding energy spectrum of the sine-Gordon quantum mechanics, and find this model contains information of the low energy effective theory of the gauge theory.
Energy Technology Data Exchange (ETDEWEB)
Wanninger, Andreas; Ceuca, Sabin Cristian; Macian-Juan, Rafael [Technische Univ. Muenchen, Garching (Germany). Dept. of Nuclear Engineering
2013-07-01
Different approaches for the calculation of Direct Contact Condensation (DCC) using Heat Transfer Coefficients (HTC) based on the Surface Renewal Theory (SRT) are tested using the CFD simulation tool ANSYS CFX. The present work constitutes a preliminary study of the flow patterns and conditions observed using different HTC models. A complex 3D flow pattern will be observed in the CFD simulations as well as a strong coupling between the condensation rate and the two-phase flow dynamics. (orig.)
Reliability of surface EMG measurements from the suprahyoid muscle complex
DEFF Research Database (Denmark)
Kothari, Mohit; Stubbs, Peter William; Pedersen, Asger Roer
2017-01-01
of using the suprahyoid muscle complex (SMC) using surface electromyography (sEMG) to assess changes to neural pathways by determining the reliability of measurements in healthy participants over days. Methods: Seventeen healthy participants were recruited. Measurements were performed twice with one week...... between sessions. Single pulse (at 120% and 140% of the resting motor threshold (rMT)) and paired pulse (2 ms and 15 ms paired pulse) transcranial magnetic stimulation (TMS) were used to elicit MEPs in the SMC which were recorded using sEMG. Results: ≈50% of participants (range: 42%-58%; depending...... on stimulus type/intensity) had significantly different MEP values between day 1 and day 2 for single pulse and paired pulse TMS. A large stimulus artefact resulted in MEP responses that could not be assessed in four participants. Conclusions: The assessment of the SMC using sEMG following TMS was poorly...
Trenholm, Susan; Ferlie, Ewan
2013-09-01
We employ complexity theory to analyse the English National Health Service (NHS)'s organisational response to resurgent tuberculosis across London. Tennison (2002) suggests that complexity theory could fruitfully explore a healthcare system's response to this complex and emergent phenomenon: we explore this claim here. We also bring in established New Public Management principles to enhance our empirical analysis, which is based on data collected between late 2009 and mid-2011. We find that the operation of complexity theory based features, especially self-organisation, are significantly impacted by the macro context of a New Public Management-based regime which values control, measurement and risk management more than innovation, flexibility and lateral system building. We finally explore limitations and suggest perspectives for further research. Copyright © 2012 Elsevier Ltd. All rights reserved.
Generalization of the Activated Complex Theory of Reaction Rates. I. Quantum Mechanical Treatment
Marcus, R. A.
1964-01-01
In its usual form activated complex theory assumes a quasi-equilibrium between reactants and activated complex, a separable reaction coordinate, a Cartesian reaction coordinate, and an absence of interaction of rotation with internal motion in the complex. In the present paper a rate expression is derived without introducing the Cartesian assumption. The expression bears a formal resemblance to the usual one and reduces to it when the added assumptions of the latter are introduced.
Surface complexation model of uranyl sorption on Georgia kaolinite
Payne, T.E.; Davis, J.A.; Lumpkin, G.R.; Chisari, R.; Waite, T.D.
2004-01-01
The adsorption of uranyl on standard Georgia kaolinites (KGa-1 and KGa-1B) was studied as a function of pH (3-10), total U (1 and 10 ??mol/l), and mass loading of clay (4 and 40 g/l). The uptake of uranyl in air-equilibrated systems increased with pH and reached a maximum in the near-neutral pH range. At higher pH values, the sorption decreased due to the presence of aqueous uranyl carbonate complexes. One kaolinite sample was examined after the uranyl uptake experiments by transmission electron microscopy (TEM), using energy dispersive X-ray spectroscopy (EDS) to determine the U content. It was found that uranium was preferentially adsorbed by Ti-rich impurity phases (predominantly anatase), which are present in the kaolinite samples. Uranyl sorption on the Georgia kaolinites was simulated with U sorption reactions on both titanol and aluminol sites, using a simple non-electrostatic surface complexation model (SCM). The relative amounts of U-binding >TiOH and >AlOH sites were estimated from the TEM/EDS results. A ternary uranyl carbonate complex on the titanol site improved the fit to the experimental data in the higher pH range. The final model contained only three optimised log K values, and was able to simulate adsorption data across a wide range of experimental conditions. The >TiOH (anatase) sites appear to play an important role in retaining U at low uranyl concentrations. As kaolinite often contains trace TiO2, its presence may need to be taken into account when modelling the results of sorption experiments with radionuclides or trace metals on kaolinite. ?? 2004 Elsevier B.V. All rights reserved.
Ternary Complexation on Bacterial Surfaces: Implications for Subsurface Anion Transport
Maclean, L. C.; Higginbottom, C. M.; Fowle, D. A.
2002-12-01
The physical, chemical, and biological controls on contaminant mobilities in aquatic ecosystems must be determined to establish the threat that contamination poses to the environment. Quantitative models of contaminant mobilities are required as a prerequisite to guide remediation efforts and to prioritize the potential hazard to the ecosystem of each contaminated site. It is well established that mineral surface adsorption is an important control on contaminant mobilities, and many studies have utilized thermodynamics to quantify metal/organic adsorption in order to yield predictive models of contaminant transport. However, these models of contaminant transport may not be representative of the reactions which control contaminant mobilities as most mineral surfaces are coated with organic acids, bacteria, and extracellular polymers. Numerous laboratory studies have demonstrated that bacterial cell walls have a high affinity for binding metal cations, and field studies indicate that a significant proportion of bacteria cells and associated extracellular matrices are coated with small scale hydrous metal oxides. The small size of bacteria, and in many cases the nanoscale of their associated mineral phases, suggests these bacteria-mineral composites may represent a large proportion of surface area exposed to fluid flow. Therefore, due to the affinity of bacterial cell walls for cations and biominerals, bacteria may also have a significant impact on anionic contaminant mobility in many natural systems. The extent of metal-bacteria adsorption reactions varies drastically as a function of pH and solution chemistry. Current adsorption models have focused on the interactions of positively charged metal cations with bacterial surfaces, however in many oxidizing environments metals such as Cr exist as anions or anionic complexes. We have studied the ability of non-metabolizing cells of the bacterial species Bacillus subtilis and Shewanella putrifaciens to adsorb aqueous Cr
The Implication of Chaos/Complexity Theory into Second Language Acquisition
Directory of Open Access Journals (Sweden)
Minoo Alemi
2011-05-01
Full Text Available With the advances in Quantum physics and meteorology, science has moved towards more uncertainty and unpredictability (Larsen-Freeman, 2002 [12]. This has resulted in the emergence of Chaos/Complexity Science (Valle, 2000 [20], or Theory (Larsen-Freeman, 1997 [11], and Dynamic System Theory (De Bot, Lowie, & Verspoor, 2007 [3]. As Larsen-Freeman (1997 [11] states the name of chaos/complexity science is paradoxical terminology in that the word science means order as well as complexity but in Ch/C this complexity is achieved through chaotic situation. In science we are searching for cause and effect connection while in Ch/C such a connection is not that much straightforward. Efforts have been invested to apply the concept into Second Language Acquisition (SLA (Larsen-Freeman, 1997 [11] due to incommensurable issues in SLA Larsen-Freeman (1997 [11], especially, introduced the concept into SLA in detail, however, we think more works and speculations on the topic are required on all aspects which are related to SLA. To this end, this article is a critical review of the implication of Chaos/Complexity theory into SLA from three perspectives: the Nature of Language Complexity, SLA Incommensurable Theories, and the Complex Nature of Classroom.
Self-similarity and scaling theory of complex networks
Song, Chaoming
Scale-free networks have been studied extensively due to their relevance to many real systems as diverse as the World Wide Web (WWW), the Internet, biological and social networks. We present a novel approach to the analysis of scale-free networks, revealing that their structure is self-similar. This result is achieved by the application of a renormalization procedure which coarse-grains the system into boxes containing nodes within a given "size". Concurrently, we identify a power-law relation between the number of boxes needed to cover the network and the size of the box defining a self-similar exponent, which classifies fractal and non-fractal networks. By using the concept of renormalization as a mechanism for the growth of fractal and non-fractal modular networks, we show that the key principle that gives rise to the fractal architecture of networks is a strong effective "repulsion" between the most connected nodes (hubs) on all length scales, rendering them very dispersed. We show that a robust network comprised of functional modules, such as a cellular network, necessitates a fractal topology, suggestive of a evolutionary drive for their existence. These fundamental properties help to understand the emergence of the scale-free property in complex networks.
General contact mechanics theory for randomly rough surfaces with application to rubber friction
Scaraggi, Michele; Persson, Bo N. J.
2015-01-01
We generalize the Persson contact mechanics and rubber friction theory to the case where both surfaces have surface roughness. The solids can be rigid, elastic or viscoelastic, and can be homogeneous or layered. We calculate the contact area, the viscoelastic contribution to the friction force, and the average interfacial separation as a function of the sliding speed and the nominal contact pressure. We illustrate the theory with numerical results for a rubber block sliding on a road surface....
Directory of Open Access Journals (Sweden)
Valentin Adrian Jean BUTOESCU
2014-03-01
Full Text Available This is the second article of a series that deals with the calculation of the aerodynamic unsteady forces on lifting surfaces. It presents some new important details on the lifting surface theory that performs oscillations in subsonic flow. These features will be applied to the aerodynamic response to certain kind of gusts and to the flapping wing calculations.
DEFF Research Database (Denmark)
Barini, Emanuele Modesto; Tosello, Guido; De Chiffre, Leonardo
2010-01-01
The paper describes a study concerning point-by-point sampling of complex surfaces using tactile CMMs. A four factor, two level completely randomized factorial experiment was carried out, involving measurements on a complex surface configuration item comprising a sphere, a cylinder and a cone, co...
The pervasive reach of resource-bounded Kolmogorov complexity in computational complexity theory
Czech Academy of Sciences Publication Activity Database
Allender, E.; Koucký, Michal; Ronneburger, D.; Roy, S.
2011-01-01
Roč. 77, č. 1 (2011), s. 14-40 ISSN 0022-0000 R&D Projects: GA ČR GAP202/10/0854; GA MŠk(CZ) 1M0545; GA AV ČR IAA100190902 Institutional research plan: CEZ:AV0Z10190503 Keywords : Circuit complexity * Distinguishing complexity * FewEXP * Formula size * Kolmogorov complexity Subject RIV: BA - General Mathematics Impact factor: 1.157, year: 2011 http://www.sciencedirect.com/science/article/pii/S0022000010000887
Golibrzuch, Kai; Bartels, Nils; Auerbach, Daniel J; Wodtke, Alec M
2015-04-01
We review studies of molecular interactions and chemical reactions at metal surfaces, emphasizing progress toward a predictive theory of surface chemistry and catalysis. For chemistry at metal surfaces, a small number of central approximations are typically made: (a) the Born-Oppenheimer approximation of electronic adiabaticity, (b) the use of density functional theory at the generalized gradient approximation level, (c) the classical approximation for nuclear motion, and (d) various reduced-dimensionality approximations. Together, these approximations constitute a provisional model for surface chemical reactivity. We review work on some carefully studied examples of molecules interacting at metal surfaces that probe the validity of various aspects of the provisional model.
Adaptive Surface Modeling of Soil Properties in Complex Landforms
Directory of Open Access Journals (Sweden)
Wei Liu
2017-06-01
Full Text Available Abstract: Spatial discontinuity often causes poor accuracy when a single model is used for the surface modeling of soil properties in complex geomorphic areas. Here we present a method for adaptive surface modeling of combined secondary variables to improve prediction accuracy during the interpolation of soil properties (ASM-SP. Using various secondary variables and multiple base interpolation models, ASM-SP was used to interpolate soil K+ in a typical complex geomorphic area (Qinghai Lake Basin, China. Five methods, including inverse distance weighting (IDW, ordinary kriging (OK, and OK combined with different secondary variables (e.g., OK-Landuse, OK-Geology, and OK-Soil, were used to validate the proposed method. The mean error (ME, mean absolute error (MAE, root mean square error (RMSE, mean relative error (MRE, and accuracy (AC were used as evaluation indicators. Results showed that: (1 The OK interpolation result is spatially smooth and has a weak bull's-eye effect, and the IDW has a stronger ‘bull’s-eye’ effect, relatively. They both have obvious deficiencies in depicting spatial variability of soil K+. (2 The methods incorporating combinations of different secondary variables (e.g., ASM-SP, OK-Landuse, OK-Geology, and OK-Soil were associated with lower estimation bias. Compared with IDW, OK, OK-Landuse, OK-Geology, and OK-Soil, the accuracy of ASM-SP increased by 13.63%, 10.85%, 9.98%, 8.32%, and 7.66%, respectively. Furthermore, ASM-SP was more stable, with lower MEs, MAEs, RMSEs, and MREs. (3 ASM-SP presents more details than others in the abrupt boundary, which can render the result consistent with the true secondary variables. In conclusion, ASM-SP can not only consider the nonlinear relationship between secondary variables and soil properties, but can also adaptively combine the advantages of multiple models, which contributes to making the spatial interpolation of soil K+ more reasonable.
Energy Technology Data Exchange (ETDEWEB)
Carter, G.; Nobes, M.J. (Salford Univ. (UK). Thin Film and Surface Research Centre)
1984-03-01
A general theory of the development of surface topography of three-dimensional systems as a result of sputtering erosion and related processes is given. The theory is based upon a treatment of the surface as an advancing wavefront with spatio-temporally variable wavefront velocity appropriate to anisotropic, inhomogeneous media. The relevance of the theory to cases of stratified substrates, including polycrystals, dislocated crystals and contaminated surfaces, and to spatially scanned ion fluxes or substrates and rotated substrates is shown and a specific example of erosion at a grain boundary explored in detail.
Lectures on a theory of computation and complexity over the reals (or an arbitrary ring)
International Nuclear Information System (INIS)
Blum, L.
1990-01-01
These lectures will discuss a new theory of computation and complexity which attempts to integrate key ideas from the classical theory in a setting more amenable to problems defined over continuous domains. The approach taken here is both algebraic and concrete; the underlying space is an arbitrary ring (or field) and the basic operations are polynominal (or rational) maps and tests. This approach yields results in the continuous setting analogous to the pivotal classical results of undecidability and NP-completeness over the integers, yet reflecting the special mathematical character of the underlying space. The goal of these lectures is to highlight key aspects of the new theory as well as to give exposition, in this setting, of classical ideas and results. Indeed, since this new theory is more mathematical, perhaps less dependent on logic than the classical theory, a number of key results have more straightforward and transparent proofs in this setting. One of our themes will be the comparison of results over the integers with results over the reals and complex numbers. Contrasting one theory with the other will help illuminate each, and give deeper understanding to such basic concepts as decidability, definability, computability, and complexity. 53 refs
Complexity in Surfaces of Densest Packings for Families of Polyhedra
Directory of Open Access Journals (Sweden)
Elizabeth R. Chen
2014-02-01
Full Text Available Packings of hard polyhedra have been studied for centuries due to their mathematical aesthetic and more recently for their applications in fields such as nanoscience, granular and colloidal matter, and biology. In all these fields, particle shape is important for structure and properties, especially upon crowding. Here, we explore packing as a function of shape. By combining simulations and analytic calculations, we study three two-parameter families of hard polyhedra and report an extensive and systematic analysis of the densest known packings of more than 55 000 convex shapes. The three families have the symmetries of triangle groups (icosahedral, octahedral, tetrahedral and interpolate between various symmetric solids (Platonic, Archimedean, Catalan. We find optimal (maximum packing-density surfaces that reveal unexpected richness and complexity, containing as many as 132 different structures within a single family. Our results demonstrate the importance of thinking about shape not as a static property of an object, in the context of packings, but rather as but one point in a higher-dimensional shape space whose neighbors in that space may have identical or markedly different packings. Finally, we present and interpret our packing results in a consistent and generally applicable way by proposing a method to distinguish regions of packings and classify types of transitions between them.
LOCALIZATION OF PATHOLOGY ON COMPLEX ARCHITECTURE BUILDING SURFACES
Directory of Open Access Journals (Sweden)
A. A. Sidiropoulos
2017-02-01
Full Text Available The technology of 3D laser scanning is considered as one of the most common methods for heritage documentation. The point clouds that are being produced provide information of high detail, both geometric and thematic. There are various studies that examine techniques of the best exploitation of this information. In this study, an algorithm of pathology localization, such as cracks and fissures, on complex building surfaces is being tested. The algorithm makes use of the points’ position in the point cloud and tries to distinguish them in two groups-patterns; pathology and non-pathology. The extraction of the geometric information that is being used for recognizing the pattern of the points is being accomplished via Principal Component Analysis (PCA in user-specified neighborhoods in the whole point cloud. The implementation of PCA leads to the definition of the normal vector at each point of the cloud. Two tests that operate separately examine both local and global geometric criteria among the points and conclude which of them should be categorized as pathology. The proposed algorithm was tested on parts of the Gazi Evrenos Baths masonry, which are located at the city of Giannitsa at Northern Greece.
Single-photon test of hyper-complex quantum theories using a metamaterial.
Procopio, Lorenzo M; Rozema, Lee A; Wong, Zi Jing; Hamel, Deny R; O'Brien, Kevin; Zhang, Xiang; Dakić, Borivoje; Walther, Philip
2017-04-21
In standard quantum mechanics, complex numbers are used to describe the wavefunction. Although this has so far proven sufficient to predict experimental results, there is no theoretical reason to choose them over real numbers or generalizations of complex numbers, that is, hyper-complex numbers. Experiments performed to date have proven that real numbers are insufficient, but the need for hyper-complex numbers remains an open question. Here we experimentally probe hyper-complex quantum theories, studying one of their deviations from complex quantum theory: the non-commutativity of phases. We do so by passing single photons through a Sagnac interferometer containing both a metamaterial with a negative refractive index, and a positive phase shifter. To accomplish this we engineered a fishnet metamaterial to have a negative refractive index at 780 nm. We show that the metamaterial phase commutes with other phases with high precision, allowing us to place limits on a particular prediction of hyper-complex quantum theories.
Selected topics in the classical theory of functions of a complex variable
Heins, Maurice
2014-01-01
Elegant and concise, this text is geared toward advanced undergraduate students acquainted with the theory of functions of a complex variable. The treatment presents such students with a number of important topics from the theory of analytic functions that may be addressed without erecting an elaborate superstructure. These include some of the theory's most celebrated results, which seldom find their way into a first course. After a series of preliminaries, the text discusses properties of meromorphic functions, the Picard theorem, and harmonic and subharmonic functions. Subsequent topics incl
Complexity-action duality of the shock wave geometry in a massive gravity theory
Miao, Yan-Gang; Zhao, Long
2018-01-01
On the holographic complexity dual to the bulk action, we investigate the action growth for a shock wave geometry in a massive gravity theory within the Wheeler-DeWitt (WDW) patch at the late time limit. For a global shock wave, the graviton mass does not affect the action growth in the bulk, i.e., the complexity on the boundary, showing that the action growth (complexity) is the same for both the Einstein gravity and the massive gravity. Nevertheless, for a local shock wave that depends on transverse coordinates, the action growth (complexity) caused by the boundary disturbance (perturbation) is proportional to the butterfly velocity for the two gravity theories, but the butterfly velocity of the massive gravity theory is smaller than that of the Einstein gravity theory, indicating that the action growth (complexity) of the massive gravity is depressed by the graviton mass. In addition, we extend the black hole thermodynamics of the massive gravity and obtain the right Smarr formula.
Non-perturbative string theories and singular surfaces
International Nuclear Information System (INIS)
Bochicchio, M.
1990-01-01
Singular surfaces are shown to be dense in the Teichmueller space of all Riemann surfaces and in the grasmannian. This happens because a regular surface of genus h, obtained identifying 2h disks in pairs, can be approximated by a very large genus singular surface with punctures dense in the 2h disks. A scale ε is introduced and the approximate genus is defined as half the number of connected regions covered by punctures of radius ε. The non-perturbative partition function is proposed to be a scaling limit of the partition function on such infinite genus singular surfaces with a weight which is the coupling constant g raised to the approximate genus. For a gaussian model in any space-time dimension the regularized partition function on singular surfaces of infinite genus is the partition function of a two-dimensional lattice gas of charges and monopoles. It is shown that modular invariance of the partition function implies a version of the Dirac quantization condition for the values of the e/m charges. Before the scaling limit the phases of the lattice gas may be classified according to the 't Hooft criteria for the condensation of e/m operators. (orig.)
Horvat, Ana; Filipovic, Jovan
2018-02-01
This research focuses on Complexity Leadership Theory and the relationship between leadership-examined through the lens of Complexity Leadership Theory-and organizational maturity as an indicator of the performance of health organizations. The research adopts a perspective that conceptualizes organizations as complex adaptive systems and draws upon a survey of opinion of 189 managers working in Serbian health organizations. As the results indicate a dependency between functions of leadership and levels of the maturity of health organizations, we propose a model that connects the two. The study broadens our understanding of the implications of complexity thinking and its reflection on leadership functions and overall organizational performance. The correlations between leadership functions and maturity could have practical applications in policy processing, thus improving the quality of outcomes and the overall level of service quality. © 2017 John Wiley & Sons, Ltd.
Surface complexation models for uranium adsorption in the sub-surface environment
International Nuclear Information System (INIS)
Payne, T.E.
2007-01-01
Adsorption experiments with soil component minerals under a range of conditions are being used to develop models of uranium(VI) uptake in the sub-surface environment. The results show that adsorption of U on iron oxides and clay minerals is influenced by chemical factors including the pH, partial pressure of CO 2 , and the presence of ligands such as phosphate. Surface complexation models (SCMs) can be used to simulate U adsorption on these minerals. The SCMs are based on plausible mechanistic assumptions and describe the experimental data more adequately than Kd values or sorption isotherms. It is conceptually possible to simulate U sorption data on complex natural samples by combining SCMs for individual component minerals. This approach was used to develop a SCM for U adsorption to mineral assemblages from Koongarra (Australia), and produced a reasonable description of U uptake. In order to assess the applicability of experimental data to the field situation, in-situ measurements of U distributions between solid and liquid phases were undertaken at the Koongarra U deposit. This field partitioning data showed a satisfactory agreement with laboratory sorption data obtained under comparable conditions. (author)
Reza Kalantari; Javad Gholami
2017-01-01
This longitudinal case study explored Iranian EFL learners’ lexical complexity (LC) through the lenses of Dynamic Systems Theory (DST). Fifty independent essays written by five intermediate to advanced female EFL learners in a TOEFL iBT preparation course over six months constituted the corpus of this study. Three Coh-Metrix indices (Graesser, McNamara, Louwerse, & Cai, 2004; McNamara & Graesser, 2012), three Lexical Complexity Analyzer indices (Lu, 2010, 2012; Lu & Ai, 2011...
Complex source point theory of paraxial and nonparaxial cosine-Gauss and Bessel-Gauss beams.
Sheppard, Colin J R
2013-02-15
It shown how cosine-Gauss and Bessel-Gauss beams can be generated using the complex source point theory. Paraxial beams are treated first. An analytic expression is derived for the nonparaxial cosine-Gaussian beam, based on the complex source point approach, and numerical results are presented to illustrate its behavior. A way to generate nonparaxial Bessel-Gauss beams is also indicated.
Localization of four-dimensional super-Yang-Mills theories compactified on Riemann surface
Nagasaki, Koichi
2016-12-01
We consider the partition function of super-Yang-Mills theories defined on 𝕋2 × Σ g. This path integral can be computed by the localization. The one-loop determinant is evaluated by the elliptic genus. This elliptic genus gives trivial result in our calculation. As a result, we obtain a theory defined on the Riemann surface.
Martin, E. Dale
1989-01-01
The paper introduces a new theory of N-dimensional complex variables and analytic functions which, for N greater than 2, is both a direct generalization and a close analog of the theory of ordinary complex variables. The algebra in the present theory is a commutative ring, not a field. Functions of a three-dimensional variable were defined and the definition of the derivative then led to analytic functions.
High intensity surface plasma waves, theory and PIC simulations
Raynaud, M.; Héron, A.; Adam, J.-C.
2018-01-01
With the development of intense (>1019 W cm‑2) short pulses (≤25 fs) laser with very high contrast, surface plasma wave (SPW) can be explored in the relativistic regime. As the SPW propagates with a phase velocity close to the speed of light it may results in a strong acceleration of electron bunches along the surface permitting them to reach relativistic energies. This may be important e.g. for applications in the field of plasma-based accelerators. We investigate in this work the excitation of SPWs on grating preformed over-dense plasmas for laser intensities ranging from 1019 up to 1021 W cm‑2. We discuss the nature of the interaction with respect to the solid case in which surface plasmon can be resonantly excited with weak laser intensity. In particular, we show the importance of the pulse duration and focalization of the laser beam on the amplitude of the SPW.
Dunn, Karen S; Riley-Doucet, Cheryl K
Nurse educators use a variety of clinical simulation strategies to promote cognitive, psychomotor, and affective learning. Statistically significant increases in self-confidence levels were found among senior-level nursing students in the assessment and management of medical and psychiatric symptoms after participating in strategically designed, complex, student-led clinical simulations. Having students role play simulation scenarios that are developed from real-life clinical experiences is a cost-effective interactive strategy that enhances their communication and technical skills.
2016-06-03
of Arsenic-Water Complexes Using Density Functional Theory June 3, 2016 Approved for public release; distribution is unlimited. L. Huang S.g... Density Functional Theory L. Huang, S.G. Lambrakos, A. Shabaev,1 and L. Massa2 Naval Research Laboratory, Code 6394 4555 Overlook Avenue, SW...absorption spectra for As-H2O complexes using density functional theory (DFT) and time-dependent density functional theory (TD-DFT). DFT and TD-DFT can
Noyes, Jane; Brenner, Maria; Fox, Patricia; Guerin, Ashleigh
2014-05-01
To report a novel review to develop a health systems model of successful transition of children with complex healthcare needs from hospital to home. Children with complex healthcare needs commonly experience an expensive, ineffectual and prolonged nurse-led discharge process. Children gain no benefit from prolonged hospitalization and are exposed to significant harm. Research to enable intervention development and process evaluation across the entire health system is lacking. Novel mixed-method integrative review informed by health systems theory. DATA CINAHL, PsychInfo, EMBASE, PubMed, citation searching, personal contact. REVIEW Informed by consultation with experts. English language studies, opinion/discussion papers reporting research, best practice and experiences of children, parents and healthcare professionals and purposively selected policies/guidelines from 2002-December 2012 were abstracted using Framework synthesis, followed by iterative theory development. Seven critical factors derived from thirty-four sources across five health system levels explained successful discharge (new programme theory). All seven factors are required in an integrated care pathway, with a dynamic communication loop to facilitate effective discharge (new programme logic). Current health system responses were frequently static and critical success factors were commonly absent, thereby explaining ineffectual discharge. The novel evidence-based model, which reconceptualizes 'discharge' as a highly complex longitudinal health system intervention, makes a significant contribution to global knowledge to drive practice development. Research is required to develop process and outcome measures at different time points in the discharge process and future trials are needed to determine the effectiveness of integrated health system discharge models. © 2013 John Wiley & Sons Ltd.
International Nuclear Information System (INIS)
Hammond, Glenn E.; Cygan, Randall Timothy
2007-01-01
Within reactive geochemical transport, several conceptual models exist for simulating sorption processes in the subsurface. Historically, the K D approach has been the method of choice due to ease of implementation within a reactive transport model and straightforward comparison with experimental data. However, for modeling complex sorption phenomenon (e.g. sorption of radionuclides onto mineral surfaces), this approach does not systematically account for variations in location, time, or chemical conditions, and more sophisticated methods such as a surface complexation model (SCM) must be utilized. It is critical to determine which conceptual model to use; that is, when the material variation becomes important to regulatory decisions. The geochemical transport tool GEOQUIMICO has been developed to assist in this decision-making process. GEOQUIMICO provides a user-friendly framework for comparing the accuracy and performance of sorption conceptual models. The model currently supports the K D and SCM conceptual models. The code is written in the object-oriented Java programming language to facilitate model development and improve code portability. The basic theory underlying geochemical transport and the sorption conceptual models noted above is presented in this report. Explanations are provided of how these physicochemical processes are instrumented in GEOQUIMICO and a brief verification study comparing GEOQUIMICO results to data found in the literature is given
Surface complexation at calcium mineral-water interfaces
Wu, Liuming
1994-01-01
Surface reactions occurring at solid-water interfaces in calcium mineral-ligands systems have been studied. Both hydrous apatite and fluorite surfaces show clear amphoteric properties. An ion exchange process between lattice ions of F- on fluorite and OH- ions in bulk solution is discovered. The surface adsorption of Alizarin Red S and sodium oleate are determined. Surface chemical reaction models are established based on acidbase potentiometric titrations, solubility, adsorption and zeta-pot...
Understanding colloidal charge renormalization from surface chemistry: Experiment and theory
Gisler, T.; Schulz, S. F.; Borkovec, M.; Sticher, H.; Schurtenberger, P.; D'Aguanno, B.; Klein, R.
1994-12-01
In this paper we report on the charging behavior of latex particles in aqueous suspensions. We use static light scattering and acid-base titrations as complementary techniques to observe both effective and bare particle charges. Acid-base titrations at various ionic strengths provide the pH dependent charging curves. The surface chemical parameters (dissociation constant of the acidic carboxylic groups, total density of ionizable sites and Stern capacitance) are determined from fits of a Stern layer model to the titration data. We find strong evidence that the dissociation of protons is the only specific adsorption process. Effective particle charges are determined by fits of integral equation calculations of the polydisperse static structure factor to the static light scattering data. A generalization of the Poisson-Boltzmann cell model including the dissociation of the acidic surface groups and the autodissociation of water is used to predict effective particle charges from the surface chemical parameters determined by the titration experiments. We find that the light scattering data are best described by a model where a small fraction of the ionizable surface sites are sulfate groups which are completely dissociated at moderate pH. These effective charges are comparable to the predictions by a basic cell model where charge regulation is absent.
Quantum theory of spontaneous and stimulated emission of surface plasmons
International Nuclear Information System (INIS)
Archambault, Alexandre; Marquier, Francois; Greffet, Jean-Jacques; Arnold, Christophe
2010-01-01
We introduce a quantization scheme that can be applied to surface waves propagating along a plane interface. An important result is the derivation of the energy of the surface wave for dispersive nonlossy media without invoking any specific model for the dielectric constant. Working in Coulomb's gauge, we use a modal representation of the fields. Each mode can be associated with a quantum harmonic oscillator. We have applied the formalism to derive quantum mechanically the spontaneous emission rate of surface plasmon by a two-level system. The result is in very good agreement with Green's tensor approach in the nonlossy case. Green's approach allows also to account for losses, so that the limitations of a quantum approach of surface plasmons are clearly defined. Finally, the issue of stimulated versus spontaneous emission has been addressed. Because of the increasing density of states near the asymptote of the dispersion relation, it is quantitatively shown that the stimulated emission probability is too small to obtain gain in this frequency region.
Leidenfrost drops cooling surfaces: theory and interferometric measurement
Van Limbeek, Michiel A. J.; Klein Schaarsberg, Martin H.; Sobac, Benjamin; Rednikov, Alexey; Sun, Chao; Colinet, Pierre; Lohse, Detlef
2017-01-01
When a liquid drop is placed on a highly superheated surface, it can be levitated by its own vapour. This remarkable phenomenon is referred to as the Leidenfrost effect. The thermally insulating vapour film results in a severe reduction of the heat transfer rate compared to experiments at lower
Organizational Change at the Edge of Chaos: A Complexity Theory Perspective of Autopoietic Systems
Susini, Domenico, III.
2010-01-01
This qualitative phenomenological study includes explorations of organizational change phenomena from the vantage point of complexity theory as experienced through the lived experiences of eight senior level managers and executives based in Northern N.J. who have experienced crisis situations in their organizations. Concepts from the natural…
Kalantari, Reza; Gholami, Javad
2017-01-01
This longitudinal case study explored Iranian EFL learners' lexical complexity (LC) through the lenses of Dynamic Systems Theory (DST). Fifty independent essays written by five intermediate to advanced female EFL learners in a TOEFL iBT preparation course over six months constituted the corpus of this study. Three Coh-Metrix indices (Graesser,…
Generalization of the Activated Complex Theory of Reaction Rates. II. Classical Mechanical Treatment
Marcus, R. A.
1964-01-01
In its usual classical form activated complex theory assumes a particular expression for the kinetic energy of the reacting system -- one associated with a rectilinear motion along the reaction coordinate. The derivation of the rate expression given in the present paper is based on the general kinetic energy expression.
Logical strength of complexity theory and a formalization of the PCP theorem in bounded arithmetic
Pich, Ján
2014-01-01
We present several known formalizations of theorems from computational complexity in bounded arithmetic and formalize the PCP theorem in the theory PV1 (no formalization of this theorem was known). This includes a formalization of the existence and of some properties of the (n,d,{\\lambda})-graphs in PV1.
Energy Technology Data Exchange (ETDEWEB)
Llave, Ezequiel de la; Herrera, Santiago E.; Adam, Catherine; Méndez De Leo, Lucila P.; Calvo, Ernesto J.; Williams, Federico J., E-mail: fwilliams@qi.fcen.uba.ar [INQUIMAE-CONICET, Departamento de Química Inorgánica, Analítica y Química-Física, Facultad Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón 2, Buenos Aires C1428EHA (Argentina)
2015-11-14
The molecular and electronic structure of Os(II) complexes covalently bonded to self-assembled monolayers (SAMs) on Au(111) surfaces was studied by means of polarization modulation infrared reflection absorption spectroscopy, photoelectron spectroscopies, scanning tunneling microscopy, scanning tunneling spectroscopy, and density functional theory calculations. Attachment of the Os complex to the SAM proceeds via an amide covalent bond with the SAM alkyl chain 40° tilted with respect to the surface normal and a total thickness of 26 Å. The highest occupied molecular orbital of the Os complex is mainly based on the Os(II) center located 2.2 eV below the Fermi edge and the LUMO molecular orbital is mainly based on the bipyridine ligands located 1.5 eV above the Fermi edge.
Complex Path Integrals and Saddles in Two-Dimensional Gauge Theory.
Buividovich, P V; Dunne, Gerald V; Valgushev, S N
2016-04-01
We study numerically the saddle point structure of two-dimensional lattice gauge theory, represented by the Gross-Witten-Wadia unitary matrix model. The saddle points are, in general, complex valued, even though the original integration variables and action are real. We confirm the trans-series and instanton gas structure in the weak-coupling phase, and we identify a new complex-saddle interpretation of nonperturbative effects in the strong-coupling phase. In both phases, eigenvalue tunneling refers to eigenvalues moving off the real interval, into the complex plane, and the weak-to-strong coupling phase transition is driven by saddle condensation.
Kou, Jisheng
2014-01-01
The gradient theory for the surface tension of simple fluids and mixtures is rigorously analyzed based on mathematical theory. The finite element approximation of surface tension is developed and analyzed, and moreover, an adaptive finite element method based on a physical-based estimator is proposed and it can be coupled efficiently with Newton\\'s method as well. The numerical tests are carried out both to verify the proposed theory and to demonstrate the efficiency of the proposed method. © 2013 Elsevier B.V. All rights reserved.
Understanding colloidal charge renormilization from surface chemistry : experiment and theory
Gisler, Thomas; Schulz, S. F.; Borkovec, Michal; Sticher, Hans; Schurtenberger, Peter; D'Aguanno, Bruno; Klein, Rudolf
1994-01-01
In this paper we report on the charging behavior of latex particles in aqueous suspensions. We use static light scattering and acid-base titrations as complementary techniques to observe both effective and bare particle charges. Acid-base titrations at various ionic strengths provide the pH dependent charging curves. The surface chemical parameters (dissociation constant of the acidic carboxylic groups, total density of ionizable sites and Stem capacitance) are determined from tits of a Stem ...
Cryptographic applications of analytic number theory complexity lower bounds and pseudorandomness
2003-01-01
The book introduces new ways of using analytic number theory in cryptography and related areas, such as complexity theory and pseudorandom number generation. Key topics and features: - various lower bounds on the complexity of some number theoretic and cryptographic problems, associated with classical schemes such as RSA, Diffie-Hellman, DSA as well as with relatively new schemes like XTR and NTRU - a series of very recent results about certain important characteristics (period, distribution, linear complexity) of several commonly used pseudorandom number generators, such as the RSA generator, Blum-Blum-Shub generator, Naor-Reingold generator, inversive generator, and others - one of the principal tools is bounds of exponential sums, which are combined with other number theoretic methods such as lattice reduction and sieving - a number of open problems of different level of difficulty and proposals for further research - an extensive and up-to-date bibliography Cryptographers and number theorists will find th...
Semiclassical multi-phonon theory for atom-surface scattering: Application to the Cu(111) system.
Daon, Shauli; Pollak, Eli
2015-05-07
The semiclassical perturbation theory of Hubbard and Miller [J. Chem. Phys. 80, 5827 (1984)] is further developed to include the full multi-phonon transitions in atom-surface scattering. A practically applicable expression is developed for the angular scattering distribution by utilising a discretized bath of oscillators, instead of the continuum limit. At sufficiently low surface temperature good agreement is found between the present multi-phonon theory and the previous one-, and two-phonon theory derived in the continuum limit in our previous study [Daon, Pollak, and Miret-Artés, J. Chem. Phys. 137, 201103 (2012)]. The theory is applied to the measured angular distributions of Ne, Ar, and Kr scattered from a Cu(111) surface. We find that the present multi-phonon theory substantially improves the agreement between experiment and theory, especially at the higher surface temperatures. This provides evidence for the importance of multi-phonon transitions in determining the angular distribution as the surface temperature is increased.
A review of the findings and theories on surface size effects on visual attention
DEFF Research Database (Denmark)
Peschel, Anne Odile; Orquin, Jacob Lund
2013-01-01
in the literature: a linear model based on the assumption of random fixations (Lohse, 1997), a theory of surface size as visual saliency (Pieters et al., 2007), and a theory based on competition for attention (CA; Janiszewski, 1998). We furthermore suggest a fourth model – demand for attention – which we derive...... from the theory of CA by revising the underlying model assumptions. In order to test the models against each other, we reanalyze data from an eye tracking study investigating surface size and saliency effects on attention. The reanalysis revealed little support for the first three theories while...... the demand for attention model showed a much better alignment with the data. We conclude that surface size effects may best be explained as an increase in object signal strength which depends on object size, number of objects in the visual scene, and object distance to the center of the scene. Our findings...
DEFF Research Database (Denmark)
Schmidt, Per Simmendefeldt; Thygesen, Kristian Sommer
2018-01-01
We present an extensive set of surface and chemisorption energies calculated using state of the art many body perturbation theory. In the first part of the paper we consider 10 surface reactions in the low coverage regime where experimental data is available. Here the random phase approximation...
Extended KN algebras and extended conformal field theories over higher genus Riemann surfaces
International Nuclear Information System (INIS)
Ceresole, A.; Huang Chaoshang
1990-01-01
A global operator formalism for extended conformal field theories over higher genus Riemann surfaces is introduced and extended KN algebra are obtained by means of the KN bases. The BBSS construction of the spin-3 operator is carried out for Kac-Moody algebra A 2 over a Riemann surface of arbitrary genus. (orig.)
Surface wave scattering theory : with applications to forward and inverse problems in seismology
Snieder, R.K.
1987-01-01
Scattering of surface waves in a three dimensional layered elastic medium with embedded heterogeneities is described in this thesis with the Born approximation. The dyadic decomposition of the surface wave Green's function provides the crucial element for an efficient application of Born theory to
Surface wave scattering theory : with applications to forward and inverse problems in seismology
Snieder, R.K.
1987-01-01
Scattering of surface waves in a three dimensional layered elastic medium with embedded heterogeneities is described in this thesis with the Born approximation. The dyadic decomposition of the surface wave Green's function provides the crucial element for an efficient application of Born theory
Jouypazadeh, Hamidreza; Farrokhpour, Hossein; Solimannejad, Mohammad
2017-05-01
This work evaluated the reliability of the one-dimensional potential energy surface for calculating the spectroscopic properties (rovibrational constants and rotational line energies) of hydrogen bonds in linear bonded complexes by comparing theoretical results with the corresponding experimental results. For this purpose, two hydrogen bonded complexes were selected: the HCN···HCN homodimer and the HCN···HF heterodimer. The one-dimensional potential energy surfaces related to the hydrogen bonds in these complexes were calculated using different computational methods and basis sets. The calculated potential curve of each complex was fitted to an analytical one-dimensional potential function to obtain the potential parameters. The obtained analytical potential function of each complex was used in a two-particle Schrödinger equation to obtain the rovibrational energy levels of the hydrogen bond. Using the calculated rovibrational levels, the rovibrational spectra and constants of each complex were calculated and compared with experimental data available from the literature. Compared with experimental data, the calculated one-dimensional potential energy surface at the QCISD/aug-cc-pVDZ level of theory was found to predict the spectroscopic properties of hydrogen bonds better than the potential curves obtained using other computational methods, especially for the HCN···HCN homodimer complex. Generally, the results obtained for the HCN···HCN homodimer complex were closer to experimental data than those obtained for the HCN···HF heterodimer complex. The investigation performed in this work showed that the one-dimensional potential curve related to the hydrogen bond between two linear molecules can be used to predict the spectroscopic constants of hydrogen bonds. Graphical abstract Potential energy curves of HCN···HCN and HCN···HF complexes calculated at the different computational levels.
Algebra of Complex Vectors and Applications in Electromagnetic Theory and Quantum Mechanics
Directory of Open Access Journals (Sweden)
Kundeti Muralidhar
2015-08-01
Full Text Available A complex vector is a sum of a vector and a bivector and forms a natural extension of a vector. The complex vectors have certain special geometric properties and considered as algebraic entities. These represent rotations along with specified orientation and direction in space. It has been shown that the association of complex vector with its conjugate generates complex vector space and the corresponding basis elements defined from the complex vector and its conjugate form a closed complex four dimensional linear space. The complexification process in complex vector space allows the generation of higher n-dimensional geometric algebra from (n — 1-dimensional algebra by considering the unit pseudoscalar identification with square root of minus one. The spacetime algebra can be generated from the geometric algebra by considering a vector equal to square root of plus one. The applications of complex vector algebra are discussed mainly in the electromagnetic theory and in the dynamics of an elementary particle with extended structure. Complex vector formalism simplifies the expressions and elucidates geometrical understanding of the basic concepts. The analysis shows that the existence of spin transforms a classical oscillator into a quantum oscillator. In conclusion the classical mechanics combined with zeropoint field leads to quantum mechanics.
Directory of Open Access Journals (Sweden)
Joshua Rodewald
2016-10-01
Full Text Available Supply networks existing today in many industries can behave as complex adaptive systems making them more difficult to analyze and assess. Being able to fully understand both the complex static and dynamic structures of a complex adaptive supply network (CASN are key to being able to make more informed management decisions and prioritize resources and production throughout the network. Previous efforts to model and analyze CASN have been impeded by the complex, dynamic nature of the systems. However, drawing from other complex adaptive systems sciences, information theory provides a model-free methodology removing many of those barriers, especially concerning complex network structure and dynamics. With minimal information about the network nodes, transfer entropy can be used to reverse engineer the network structure while local transfer entropy can be used to analyze the network structure’s dynamics. Both simulated and real-world networks were analyzed using this methodology. Applying the methodology to CASNs allows the practitioner to capitalize on observations from the highly multidisciplinary field of information theory which provides insights into CASN’s self-organization, emergence, stability/instability, and distributed computation. This not only provides managers with a more thorough understanding of a system’s structure and dynamics for management purposes, but also opens up research opportunities into eventual strategies to monitor and manage emergence and adaption within the environment.
Get a grip on chaos: Tailored measures for complex systems on surfaces
Firle, Sascha Oliver
Complex systems are ubiquitous in physics, biology and mathematics. This thesis is concerned with describing and understanding complex systems. Some new concepts about how large systems can be viewed in a lower dimensional framework are proposed. The systems presented are examples from ecology and chemistry. In both cases we have a large amount of interacting units that can be understood by The predator-prey system investigated consists of ground beetles, Pterostichus cuprens L. (Coleoptera: Carabidae), that feeds on bird-cherry oat aphids. The beetles' movement can consistently be described by a combined model of surface diffusion and biased random walk. This allows conclusions about how fast and in which fashion the beetle covers its habitat. Movement is dependent on aphid densities and predation, in turn modifies aphid distributions locally. The presented generalized functional response theory describes predation rates in the presence of spatial heterogeneity. A single measure for fragmentation captures all essential features of the prey aggregation and allows the estimation of outbreak densities and distributions. The chemical example is the catalytic oxidation of CO on a Pt(110) single crystal surface. Unstable periodic orbits reconstructed from experimental data are used to reveal the topology of the attractor, underlying the time series dynamics. The found braid supports an orbit which implies that the time series is chaotic. The system is simulated numerically by a set of partial differential equations for surface coverage in one space dimension. The bifurcation diagram of the corresponding traveling wave ODE reveals the homoclinic and heteroclinic orbits that organize the phase space and mediate the transition to chaos. Studies in the PDE- framework relate this to the stability and to the interaction of pulse-like solutions.
Structure and energetics of high index Fe, Al, Cu and Ni surfaces using equivalent crystal theory
Rodriguez, Agustin M.; Bozzolo, Guillermo; Ferrante, John
1993-01-01
Equivalent crystal theory (ECT) is applied to the study of multilayer relaxations and surface energies of high-index faces of Fe, Al, Ni, and Cu. Changes in interplanar spacing as well as registry of planes close to the surface and the ensuing surface energies changes are discussed in reference to available experimental data and other theoretical calculations. Since ECT is a semiempirical method, the dependence of the results on the variation of the input used was investigated.
Transition State Theory for solvated reactions beyond recrossing-free dividing surfaces
Revuelta, F.; Bartsch, Thomas; Garcia-Muller, P. L.; Hernandez, Rigoberto; Benito, R. M.; Borondo, F.
2016-01-01
The accuracy of rate constants calculated using transition state theory depends crucially on the correct identification of a recrossing--free dividing surface. We show here that it is possible to define such optimal dividing surface in systems with non--Markovian friction. However, a more direct approach to rate calculation is based on invariant manifolds and avoids the use of a dividing surface altogether, Using that method we obtain an explicit expression for the rate of crossing an anharmo...
Directory of Open Access Journals (Sweden)
S. Lowe
2016-09-01
Carlo Markov Chain (MCMC approach to constraining parametric uncertainties.A complete treatment of bulk–surface partitioning is shown to predict CCN spectra similar to those calculated using classical Köhler theory with the surface tension of a pure water drop, as found in previous studies. In addition, model sensitivity to perturbations in the partitioning parameters was found to be negligible. As a result, this study supports previously held recommendations that complex surfactant effects might be neglected, and the continued use of classical Köhler theory in global climate models (GCMs is recommended to avoid an additional computational burden. The framework developed is suitable for application to many additional composition-dependent processes that might impact CCN activation potential. However, the focus of this study is to demonstrate the efficacy of the applied sensitivity analysis to identify important parameters in those processes and will be extended to facilitate a global sensitivity analysis and inverse aerosol–CCN closure analysis.
Bayoumi, A
2003-01-01
All the existing books in Infinite Dimensional Complex Analysis focus on the problems of locally convex spaces. However, the theory without convexity condition is covered for the first time in this book. This shows that we are really working with a new, important and interesting field. Theory of functions and nonlinear analysis problems are widespread in the mathematical modeling of real world systems in a very broad range of applications. During the past three decades many new results from the author have helped to solve multiextreme problems arising from important situations, non-convex and
Resistive-force theory for mesh-like superhydrophobic surfaces
Schnitzer, Ory; Yariv, Ehud
2018-03-01
A common realization of superhydrophobic surfaces makes use of a mesh-like geometry, where pockets of air are trapped in a periodic array of holes in a no-slip solid substrate. We consider the small-solid-fraction limit where the ribs of the mesh are narrow. In this limit, we obtain a simple leading-order approximation for the slip-length tensor of an arbitrary mesh geometry. This approximation scales as the solid-fraction logarithm, as anticipated by Ybert et al. [Phys. Fluids 19, 123601 (2007), 10.1063/1.2815730]; in the special case of a square mesh it agrees with the analytical results obtained by Davis and Lauga [Phys. Fluids 21, 113101 (2009), 10.1063/1.3250947].
Photoemission from Coated Surfaces A Comparison of Theory to Experiment
Jensen, K
2005-01-01
Photocathodes for FELs and accelerators will benefit from rugged and self-rejuvenating photocathodes with high QE at the longest possible wavelength. The needs of a high power FEL are not met at present by existing photocathode-drive laser combinations: requirements generally necessitate barrier-lowering coatings which are degraded by operation. We seek to develop a controlled porosity dispenser cathode, and shall report on our coordinated experimental and theoretical studies. Our models account for field, thermal, and surface effects of cesium monolayers on photoemission, and compare well with concurrent experiments examining the QE, patchiness, and evolution of the coatings. Field enhancement, thermal variation of specific heat and electron relaxation rates and their relation to high laser intensity and/or short pulse-to-pulse separation, variations in work function effects due to coating non-uniformity, and the dependence on the wavelength of the incident light are included. The status of methods by which ...
Non-supersymmetric matrix strings from generalized Yang-Mills theory on arbitrary Riemann surfaces
Billó, M.; D'Adda, A.; Provero, P.
2000-06-01
We quantize pure 2d Yang-Mills theory on an arbitrary Riemann surface in the gauge where the field strength is diagonal. Twisted sectors originate, as in Matrix string theory, from permutations of the eigenvalues around homotopically non-trivial loops. These sectors, that must be discarded in the usual quantization due to divergences occurring when two eigenvalues coincide, can be consistently kept if one modifies the action by introducing a coupling of the field strength to the space-time curvature. This leads to a generalized Yang-Mills theory whose action reduces to the usual one in the limit of zero curvature. After integrating over the non-diagonal components of the gauge fields, the theory becomes a free string theory (sum over unbranched coverings) with a U (1) gauge theory on the world-sheet. This is shown to be equivalent to a lattice theory with a gauge group which is the semi-direct product of S N and U (1) N. By using well known results on the statistics of coverings, the partition function on arbitrary Riemann surfaces and the kernel functions on surfaces with boundaries are calculated. Extensions to include branch points and non-abelian groups on the world-sheet are briefly commented upon.
DEFF Research Database (Denmark)
O'Boyle, N.M.; Albrecht, Tim; Murgida, D.H.
2007-01-01
We present a density functional theory (DFT) study of an osmium polypyridyl complex adsorbed on Au(111). The osmium polypyridyl complex [Os(bpy)(2)(P0P)Cl](n+) [bpy is 2,2'-bipyridine, P0P is 4,4'-bipyridine, n = 1 for osmium(II), and n = 2 for osmium(III)] is bound to the surface through the free...... with crystallographic structures reported in the literature. Oxidation of the complex has little effect on these structural features, but there is a substantial reordering of the electronic energy levels with corresponding changes in the electron density. Significantly, the highest occupied molecular orbital shifts...
Nonperturbative theory of atom-surface interaction: corrections at short separations.
Bordag, M; Klimchitskaya, G L; Mostepanenko, V M
2018-02-07
The nonperturbative expressions for the free energy and force of interaction between a ground-state atom and a real-material surface at any temperature are presented. The transition to the Matsubara representation is performed, whereupon the comparison is made with the commonly used perturbative results based on the standard Lifshitz theory. It is shown that the Lifshitz formulas for the free energy and force of an atom-surface interaction follow from the nonperturbative ones in the lowest order of the small parameter. Numerical computations of the free energy and force for the atoms of He[Formula: see text] and Na interacting with a surface of an Au plate have been performed using the frequency-dependent dielectric permittivity of Au and highly accurate dynamic atomic polarizabilities in the framework of both the nonperturbative and perturbative theories. According to our results, the maximum deviations between the two theories are reached at the shortest atom-surface separations of about 1 nm. Simple analytic expressions for the atom-surface free energy are derived in the classical limit and for an ideal-metal plane. In the lowest order of the small parameter, they are found in agreement with the perturbative ones following from the standard Lifshitz theory. Possible applications of the obtained results in the theory of van der Waals adsorption are discussed.
Immuno-targeting of Staphylococcus aureus via surface remodeling complexes.
Sabulski, Mary J; Pidgeon, Sean E; Pires, Marcos M
2017-10-01
Agents with novel mechanisms of action are needed to complement traditional antibiotics. Towards these goals, we have exploited the surface-homing properties of vancomycin to tag the surface of Gram-positive pathogens with immune cell attractants in two unique modes. First, vancomycin was conjugated to the small molecule hapten 2,4-dinitrophenol (DNP) to promote bacterial opsonization. Second, we built on these results by improving the tagging specificity and mechanism of incorporation by coupling it to a sortase A substrate peptide. We demonstrated, for the first time, that the surface of Staphylococcus aureus ( S. aureus ) can be metabolically labeled in live Caenorhabditis elegans hosts. These constructs represent a class of promising narrow-spectrum agents that target S. aureus for opsonization and establish a new surface labeling modality in live host organisms, which should be a powerful tool in dissecting features of host-pathogen interactions.
Complex leadership competency in health care: towards framing a theory of practice.
Ford, Randal
2009-08-01
Many analysts characterize the health-care industry and health-care systems as complex adaptive organizations. New hybrid organizational forms are emerging that exhibit diverse relational-structural alliances between physicians, hospitals and/or insurers, over which administrators have limited control and restricted ability to predict or direct. Meeting the challenges in leading and managing health-care systems as complex adaptive organizations calls for additional competency in what theorists determine as 'complex leadership'. This research study presents findings on complex leadership principles that augment those competencies that health-care administration education scholars recognize and recommend as necessary for future leaders in health care to master. The findings from this study make two contributions: first, they ground complex leader theory, derived from complexity science, in empirical data; and second, the findings add to a growing body of literature investigating the underlying logics of the complex adaptive organization and the innovative ways complex leaders are developing practices and principles in leading and managing these new, emerging organizations.
Jiang, T.; Yue, Y.
2017-12-01
It is well known that the mono-frequency directional seismic wave technology can concentrate seismic waves into a beam. However, little work on the method and effect of variable frequency directional seismic wave under complex geological conditions have been done .We studied the variable frequency directional wave theory in several aspects. Firstly, we studied the relation between directional parameters and the direction of the main beam. Secondly, we analyzed the parameters that affect the beam width of main beam significantly, such as spacing of vibrator, wavelet dominant frequency, and number of vibrator. In addition, we will study different characteristics of variable frequency directional seismic wave in typical velocity models. In order to examine the propagation characteristics of directional seismic wave, we designed appropriate parameters according to the character of direction parameters, which is capable to enhance the energy of the main beam direction. Further study on directional seismic wave was discussed in the viewpoint of power spectral. The results indicate that the energy intensity of main beam direction increased 2 to 6 times for a multi-ore body velocity model. It showed us that the variable frequency directional seismic technology provided an effective way to strengthen the target signals under complex geological conditions. For concave interface model, we introduced complicated directional seismic technology which supports multiple main beams to obtain high quality data. Finally, we applied the 9-element variable frequency directional seismic wave technology to process the raw data acquired in a oil-shale exploration area. The results show that the depth of exploration increased 4 times with directional seismic wave method. Based on the above analysis, we draw the conclusion that the variable frequency directional seismic wave technology can improve the target signals of different geologic conditions and increase exploration depth with little
Directory of Open Access Journals (Sweden)
Ward Paul R
2011-08-01
Full Text Available Abstract Background In order to improve the health of the most vulnerable groups in society, the WHO Commission on Social Determinants of Health (CSDH called for multi-sectoral action, which requires research and policy on the multiple and inter-linking factors shaping health outcomes. Most conceptual tools available to researchers tend to focus on singular and specific social determinants of health (SDH (e.g. social capital, empowerment, social inclusion. However, a new and innovative conceptual framework, known as social quality theory, facilitates a more complex and complete understanding of the SDH, with its focus on four domains: social cohesion, social inclusion, social empowerment and socioeconomic security, all within the same conceptual framework. This paper provides both an overview of social quality theory in addition to findings from a national survey of social quality in Australia, as a means of demonstrating the operationalisation of the theory. Methods Data were collected using a national random postal survey of 1044 respondents in September, 2009. Multivariate logistic regression analysis was conducted. Results Statistical analysis revealed that people on lower incomes (less than $45000 experience worse social quality across all of the four domains: lower socio-economic security, lower levels of membership of organisations (lower social cohesion, higher levels of discrimination and less political action (lower social inclusion and lower social empowerment. The findings were mixed in terms of age, with people over 65 years experiencing lower socio-economic security, but having higher levels of social cohesion, experiencing lower levels of discrimination (higher social inclusion and engaging in more political action (higher social empowerment. In terms of gender, women had higher social cohesion than men, although also experienced more discrimination (lower social inclusion. Conclusions Applying social quality theory allows
Ward, Paul R; Meyer, Samantha B; Verity, Fiona; Gill, Tiffany K; Luong, Tini C N
2011-08-05
In order to improve the health of the most vulnerable groups in society, the WHO Commission on Social Determinants of Health (CSDH) called for multi-sectoral action, which requires research and policy on the multiple and inter-linking factors shaping health outcomes. Most conceptual tools available to researchers tend to focus on singular and specific social determinants of health (SDH) (e.g. social capital, empowerment, social inclusion). However, a new and innovative conceptual framework, known as social quality theory, facilitates a more complex and complete understanding of the SDH, with its focus on four domains: social cohesion, social inclusion, social empowerment and socioeconomic security, all within the same conceptual framework. This paper provides both an overview of social quality theory in addition to findings from a national survey of social quality in Australia, as a means of demonstrating the operationalisation of the theory. Data were collected using a national random postal survey of 1044 respondents in September, 2009. Multivariate logistic regression analysis was conducted. Statistical analysis revealed that people on lower incomes (less than $45000) experience worse social quality across all of the four domains: lower socio-economic security, lower levels of membership of organisations (lower social cohesion), higher levels of discrimination and less political action (lower social inclusion) and lower social empowerment. The findings were mixed in terms of age, with people over 65 years experiencing lower socio-economic security, but having higher levels of social cohesion, experiencing lower levels of discrimination (higher social inclusion) and engaging in more political action (higher social empowerment). In terms of gender, women had higher social cohesion than men, although also experienced more discrimination (lower social inclusion). Applying social quality theory allows researchers and policy makers to measure and respond to the
Nagata, Takahiro; Fukushi, Keisuke; Takahashi, Yoshio
2009-04-15
A deficiency in environmental iodine can cause a number of health problems. Understanding how iodine is sequestered by materials is helpful for evaluating and developing methods for minimizing human health effects related to iodine. In addition, (129)I is considered to be strategically important for safety assessment of underground radioactive waste disposal. To assess the long-term stability of disposed radioactive waste, an understanding of (129)I adsorption on geologic materials is essential. Therefore, the adsorption of I(-) on naturally occurring oxides is of environmental concern. The surface charges of hydrous ferric oxide (HFO) in NaI electrolyte solutions were measured by potentiometric acid-base titration. The surface charge data were analyzed by means of an extended triple-layer model (ETLM) for surface complexation modeling to obtain the I(-) adsorption reaction and its equilibrium constant. The adsorption of I(-) was determined to be an outer-sphere process from ETLM analysis, which was consistent with independent X-ray absorption near-edge structure (XANES) observation of I(-) adsorbed on HFO. The adsorption equilibrium constants for I(-) on beta-TiO(2) and gamma-Al(2)O(3) were also evaluated by analyzing the surface charge data of these oxides in NaI solution as reported in the literature. Comparison of these adsorption equilibrium constants for HFO, beta-TiO(2), and gamma-Al(2)O(3) based on site-occupancy standard states permitted prediction of I(-) adsorption equilibrium constants for all oxides by means of the Born solvation theory. The batch adsorption data for I(-) on HFO and amorphous aluminum oxide were reasonably reproduced by ETLM with the predicted equilibrium constants, confirming the validity of the present approach. Using the predicted adsorption equilibrium constants, we calculated distribution coefficient (K(d)) values for I(-) adsorption on common soil minerals as a function of pH and ionic strength.
Uncertainty analysis of point by point sampling complex surfaces using touch probe CMMs
DEFF Research Database (Denmark)
Barini, Emanuele; Tosello, Guido; De Chiffre, Leonardo
2007-01-01
The paper describes a study concerning point by point scanning of complex surfaces using tactile CMMs. A four factors-two level full factorial experiment was carried out, involving measurements on a complex surface configuration item comprising a sphere, a cylinder and a cone, combined in a singl...
Caring as emancipatory nursing praxis: the theory of relational caring complexity.
Ray, Marilyn A; Turkel, Marian C
2014-01-01
In the culture of health care, nurses are challenged to understand their values and beliefs as humanistic within complex technical and economically driven bureaucratic systems. This article outlines the language of social justice and human rights and the advance of a Theory of Relational Caring Complexity, which offers insights into caring as emancipatory nursing praxis. Recommendations provide knowledge of the struggle to balance economics, technology, and caring. As nurses practice from a value-driven, philosophical, and ethical social justice framework, they will find "their voice" and realize the full potential that the power of caring has on patient and organizational outcomes.
Function theory on planar domains a second course in complex analysis
Fisher, Stephen D
2007-01-01
A high-level treatment of complex analysis, this text focuses on function theory on a finitely connected planar domain. Clear and complete, it emphasizes domains bounded by a finite number of disjoint analytic simple closed curves.The first chapter and parts of Chapters 2 and 3 offer background material, all of it classical and important in its own right. The remainder of the text presents results in complex analysis from the far, middle, and recent past, all selected for their interest and merit as substantive mathematics. Suitable for upper-level undergraduates and graduate students, this te
The Modeling and Complexity of Dynamical Systems by Means of Computation and Information Theories
Directory of Open Access Journals (Sweden)
Robert Logozar
2011-12-01
Full Text Available We present the modeling of dynamical systems and finding of their complexity indicators by the use of concepts from computation and information theories, within the framework of J. P. Crutchfield's theory of ε-machines. A short formal outline of the ε-machines is given. In this approach, dynamical systems are analyzed directly from the time series that is received from a properly adjusted measuring instrument. The binary strings are parsed through the parse tree, within which morphologically and probabilistically unique subtrees or morphs are recognized as system states. The outline and precise interrelation of the information-theoretic entropies and complexities emanating from the model is given. The paper serves also as a theoretical foundation for the future presentation of the DSA program that implements the ε-machines modeling up to the stochastic finite automata level.
Understanding the dimensions of intensive care: transpersonal caring and complexity theories.
do Nascimento, Keyla Cristiane; Erdmann, Alacoque Lorenzini
2009-01-01
This is a descriptive, interpretive and qualitative study carried out at the ICU of a Brazilian teaching hospital. It aimed to understand the dimensions of human caring experienced by health care professionals, clients and their family members at an ICU, based on human caring complexity. The Transpersonal Caring and Complexity theories support theory and data analysis. The following dimensions of care emerged from the themes analyzed according to Ricoeur: self-care, care as an individual value, professional vs. informal care, care as supportive relationship, affective care, humanized care, care as act/attitude, care practice; educative care, dialogical relationship, care coupled to technology, loving care, interactive care, non-care, care ambience, the essence of life and profession, and meaning/purpose of care. We believe in care that encompasses several dimensions presented here, based on the relationship with the other, on the empathetic, sensitive, affectionate, creative, dynamic and understanding being in the totality of the human being.
Zhou, Yun; Pollak, Eli; Miret-Artés, Salvador
2014-01-14
A second order classical perturbation theory is developed and applied to elastic atom corrugated surface scattering. The resulting theory accounts for experimentally observed asymmetry in the final angular distributions. These include qualitative features, such as reduction of the asymmetry in the intensity of the rainbow peaks with increased incidence energy as well as the asymmetry in the location of the rainbow peaks with respect to the specular scattering angle. The theory is especially applicable to "soft" corrugated potentials. Expressions for the angular distribution are derived for the exponential repulsive and Morse potential models. The theory is implemented numerically to a simplified model of the scattering of an Ar atom from a LiF(100) surface.
ADSORPTION OF ASSOCIATING FLUIDS AT ACTIVE SURFACES: A DENSITY FUNCTIONAL THEORY
Directory of Open Access Journals (Sweden)
S.Tripathi
2003-01-01
Full Text Available We present a density functional theory (DFT to describe adsorption in systems where molecules of associating fluids can bond (or associate with discrete, localized functional groups attached to the surfaces, in addition to other fluid molecules. For such systems as water adsorbing on activated carbon, silica, clay minerals etc. this is a realistic model to account for surface heterogeneity rather than using a continuous smeared surface-fluid potential employed in most of the theoretical works on adsorption on heterogeneous surfaces. Association is modelled within the framework of first order thermodynamic perturbation theory (TPT1. The new theory accurately predicts the distribution of bonded and non-bonded species and adsorption behavior under various conditions of bulk pressure, surface-fluid and fluid-fluid association strengths. Competition between the surface-fluid and fluid-fluid association is analyzed for fluids with multiple association sites and its impact on adsorption is discussed. The theory, supported by simulations demonstrates that the extent and the nature of adsorption (e.g. monolayer vary with the number of association sites on the fluid molecules.
A Study of Theory U and Its Application to a Complex Japanese Maritime Self-Defense Force Problem
2014-06-01
AND DATES COVERED Master’s Thesis 4. TITLE AND SUBTITLE A STUDY OF “THEORY U” AND ITS APPLICATION TO A COMPLEX JAPANESE MARITIME SELF-DEFENSE...INTENTIONALLY LEFT BLANK iii Approved for public release; distribution is unlimited A STUDY OF “THEORY U” AND ITS APPLICATION TO A COMPLEX...solving concept that focuses on the necessary elements of human nature, and attempts to study and transform human nature itself. Theory U, on the other
Dynamics of Defects and Dopants in Complex Systems: Si and Oxide Surfaces and Interfaces
Kirichenko, Taras; Yu, Decai; Banarjee, Sanjay; Hwang, Gyeong
2004-10-01
Fabrication of forthcoming nanometer scale electronic devices faces many difficulties including formation of extremely shallow and highly doped junctions. At present, ultra-low-energy ion implantation followed by high-temperature thermal annealing is most widely used to fabricate such ultra-shallow junctions. In the process, a great challenge lies in achieving precise control of redistribution and electrical activation of dopant impurities. Native defects (such as vacancies and interstitials) generated during implantation are known to be mainly responsible for the TED and also influence significantly the electrical activation/deactivation. Defect-dopant dynamics is rather well understood in crystalline Si and SiO2. However, little is known about their diffusion and annihilation (or precipitation) at the surfaces and interfaces, despite its growing importance in determining junction profiles as device dimensions get smaller. In this talk, we will present our density functional theory calculation results on the atomic and electronic structure and dynamical behavior of native defects and dopant-defect complexes in disordered/strained Si and oxide systems, such as i) clean and absorbent-modified Si(100) surface and subsurface layers, ii) amorphous-crystalline Si interfaces and iii) amorphous SiO2/Si interfaces. The fundamental understanding and data is essential in developing a comprehensive kinetic model for junction formation, which would contribute greatly in improving current process technologies.
The Advancement of Family Therapy Theory Based on the Science of Self-Organizing Complex Systems.
Ramsey-Kemper, Valerie Ann
1995-01-01
Problem. The purpose of this study was to review the literature which presents the latest advancements in the field of family therapy theory. Since such advancement has relied on the scientific developments in the study of autopoietic self-organizing complex systems, then the review began with an historical overview of the development of these natural scientific concepts. The study then examined how the latest scientific concepts have been integrated with family therapy practice. The document is built on the theory that individuals are living, complex, self-organizing, autopoietic systems. When individual systems interact with other individual systems (such as in family interaction, or in interaction between therapist and client), then a third system emerges, which is the relationship. It is through interaction in the relationship that transformation of an individual system can occur. Method. The historical antecedents of the field of family therapy were outlined. It was demonstrated, via literature review, that the field of family therapy has traditionally paralleled developments in the hard sciences. Further, it was demonstrated via literature review that the newest understandings of the development of individuals, family systems, and therapeutic systems also parallel recent natural science developments, namely those developments based on the science of self-organizing complex systems. Outcome. The results of the study are twofold. First, the study articulates an expanded theory of the therapist, individual, and family as autopoietic self-organizing complex systems. Second, the study provides an expanded hypothesis which concerns recommendations for future research which will further advance the latest theories of family therapy. More precisely, the expanded hypothesis suggests that qualitative research, rather than quantitative research, is the method of choice for studying the effectiveness of phenomenological therapy.
What can complexity do for diabetes management? Linking theory to practice.
Cooper, Helen C; Geyer, Robert
2009-08-01
Diabetes presents a multifaceted picture with its rapidly rising prevalence associated with changing demographics and increasing levels of obesity in the developed world. Deaths from diabetes are predicted to rise by 25% over the next 10 years. The enormity of this public health challenge has been recognized the world over, but little attention has been paid to the theoretical frameworks underpinning practical management. This paper aims to introduce complexity theory and discuss its practical application to diabetes, focusing on a single 'tool' to provide an example of how theory can be linked to practice. Critics have questioned the all inclusive nature of complexity seeing it as an intangible concept that fails to offer anything new to health care. However, few have appraised its practical application to a chronic disease that is currently managed using an outdated, linear, reduce and resolve model which fails to address the multiple interacting systems inherent within this condition. This article proposes that complexity theory provides an interprofessional perspective for describing and understanding the processes involved, and provides working 'tools' for patients, carers and practitioners that capture the reality of managing this chronic disease in modern life.
Strategies and Rubrics for Teaching Complex Systems Theory to Novices (Invited)
Fichter, L. S.
2010-12-01
Bifurcation. Self-similarity. Fractal. Sensitive dependent. Agents. Self-organized criticality. Avalanche behavior. Power laws. Strange attractors. Emergence. The language of complexity is fundamentally different from the language of equilibrium. If students do not know these phenomena, and what they tell us about the pulse of dynamic systems, complex systems will be opaque. A complex system is a group of agents. (individual interacting units, like birds in a flock, sand grains in a ripple, or individual friction units along a fault zone), existing far from equilibrium, interacting through positive and negative feedbacks, following simple rules, forming interdependent, dynamic, evolutionary networks. Complex systems produce behaviors that cannot be predicted deductively from knowledge of the behaviors of the individual components themselves; they must be experienced. What complexity theory demonstrates is that, by following simple rules, all the agents end up coordinating their behavior—self organizing—so that what emerges is not chaos, but meaningful patterns. How can we introduce Freshman, non-science, general education students to complex systems theories, in 3 to 5 classes; in a way they really get it, and can use the principles to understand real systems? Complex systems theories are not a series of unconnected or disconnected equations or models; they are developed as narratives that makes sense of how all the pieces and properties are interrelated. The principles of complex systems must be taught as deliberately and systematically as the equilibrium principles normally taught; as, say, the systematic training from pre-algebra and geometry to algebra. We have developed a sequence of logically connected narratives (strategies and rubrics) that introduce complex systems principles using models that can be simulated in a computer, in class, in real time. The learning progression has a series of 12 models (e.g. logistic system, bifurcation diagrams, genetic
Symplectic geometry on moduli spaces of holomorphic bundles over complex surfaces
Khesin, Boris; Rosly, Alexei
2000-01-01
We give a comparative description of the Poisson structures on the moduli spaces of flat connections on real surfaces and holomorphic Poisson structures on the moduli spaces of holomorphic bundles on complex surfaces. The symplectic leaves of the latter are classified by restrictions of the bundles to certain divisors. This can be regarded as fixing a "complex analogue of the holonomy" of a connection along a "complex analogue of the boundary" in analogy with the real case.
DEFF Research Database (Denmark)
Gavnholt, Jeppe; Rubio, Angel; Olsen, Thomas
2009-01-01
Using time-evolution time-dependent density functional theory (TDDFT) within the adiabatic local-density approximation, we study the interactions between single electrons and molecular resonances at surfaces. Our system is a nitrogen molecule adsorbed on a ruthenium surface. The surface is modeled...... at two levels of approximation, first as a simple external potential and later as a 20-atom cluster. We perform a number of calculations on an electron hitting the adsorbed molecule from inside the surface and establish a picture, where the resonance is being probed by the hot electron. This enables us...
Complexity in quantum field theory and physics beyond the standard model
International Nuclear Information System (INIS)
Goldfain, Ervin
2006-01-01
Complex quantum field theory (abbreviated c-QFT) is introduced in this paper as an alternative framework for the description of physics beyond the energy range of the standard model. The mathematics of c-QFT is based on fractal differential operators that generalize the momentum operators of conventional quantum field theory (QFT). The underlying premise of our approach is that c-QFT contains the right analytical tools for dealing with the asymptotic regime of QFT. Canonical quantization of c-QFT leads to the following findings: (i) the Fock space of c-QFT includes fractional numbers of particles and antiparticles per state (ii) c-QFT represents a generalization of topological field theory and (iii) classical limit of c-QFT is equivalent to field theory in curved space-time. The first finding provides a field-theoretic motivation for the transfinite discretization approach of El-Naschie's ε (∞) theory. The second and third findings suggest the dynamic unification of boson and fermion fields as particles with fractional spin, as well as the close connection between spin and space-time topology beyond the conventional physics of the standard model
Theory for computing the field scattered from a smooth inflected surface
Barger, R. L.; Dominek, A. K.
1986-01-01
A theory is described for computing the reflected or scattered field from a smooth body with inflection points. These inflections occur in certain directions at each surface point for which the total (Gaussian) curvature is zero or negative. For surface illumination in one of these critical directions, the usual reflection formulas obtained by the high-frequency approximation are inapplicable, and a shadow zone exists in the reflected field. Scattering into the shadow zone is treated, as well as specular reflection. This theory should have a variety of applications such as for certain optics problems, computer graphics modeling of three-dimensional shapes, and the design and analysis of specialized microwave reflector antennas.
Graph Complexes and the Moduli Space of Riemann Surfaces
DEFF Research Database (Denmark)
Egas Santander, Daniela
In this thesis we compare several combinatorial models for the moduli space of open-closed cobordisms and their compactifications. More precisely, we study Godin's category of admissible fat graphs, Costello's chain complex of black and white graphs, and Bödigheimer's space of radial slit......, that the complex of black and white graphs is a homological model of this mapping class group. Beyond giving new proofs of these results, the methods used give a new interpretation of Costello's model in terms of admissible fat graphs, which is a more classical model of moduli space. This connection could...... potentially allow to transfer constructions in fat graphs to the black and white model. Moreover, we compare Bödigheimer's radial slit configurations and the space of metric admissible fat graphs, producing an explicit homotopy equivalence using a "critical graph" map. This critical graph map descends...
International Nuclear Information System (INIS)
Geroyannis, V.S.
1988-01-01
In this paper, a numerical method is developed for determining the structure distortion of a polytropic star which rotates either uniformly or differentially. This method carries out the required numerical integrations in the complex plane. The method is implemented to compute indicative quantities, such as the critical perturbation parameter which represents an upper limit in the rotational behavior of the star. From such indicative results, it is inferred that this method achieves impressive improvement against other relevant methods; most important, it is comparable to some of the most elaborate and accurate techniques on the subject. It is also shown that the use of this method with Chandrasekhar's first-order perturbation theory yields an immediate drastic improvement of the results. Thus, there is no neeed - for most applications concerning rotating polytropic models - to proceed to the further use of the method with higher order techniques, unless the maximum accuracy of the method is required. 31 references
Adsorption of polymer/solvent complexes on silica surfaces
Czech Academy of Sciences Publication Activity Database
Grohens, Y.; Carriere, P.; Hamon, L.; Castelein, O.; Holl, Y.; Spěváček, Jiří
2001-01-01
Roč. 166, - (2001), s. 59-70 ISSN 1022-1360. [International Conference on Polymer-solvent Complexes and Intercalates /3./. Besancon, 28.08.2000-30.08.2000] R&D Projects: GA AV ČR KSK4050111 Institutional research plan: CEZ:AV0Z4050913 Keywords : polymer/solvent interactions * stereocomplexes Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.634, year: 2001
DEFF Research Database (Denmark)
Esfahania, M. Nasr; Sonne, Mads Rostgaard; Hattel, J. Henri
2016-01-01
on Surface Cauchy-Born theory is developed, where surface energy is accounted for in the prediction of the thermomechanical response. This is achieved by using a temperature-dependent interatomic potential in the standard Cauchy-Born theory with a surface energy contribution. Simultaneous calculation...
Theory of aberration fields for general optical systems with freeform surfaces.
Fuerschbach, Kyle; Rolland, Jannick P; Thompson, Kevin P
2014-11-03
This paper utilizes the framework of nodal aberration theory to describe the aberration field behavior that emerges in optical systems with freeform optical surfaces, particularly φ-polynomial surfaces, including Zernike polynomial surfaces, that lie anywhere in the optical system. If the freeform surface is located at the stop or pupil, the net aberration contribution of the freeform surface is field constant. As the freeform optical surface is displaced longitudinally away from the stop or pupil of the optical system, the net aberration contribution becomes field dependent. It is demonstrated that there are no new aberration types when describing the aberration fields that arise with the introduction of freeform optical surfaces. Significantly it is shown that the aberration fields that emerge with the inclusion of freeform surfaces in an optical system are exactly those that have been described by nodal aberration theory for tilted and decentered optical systems. The key contribution here lies in establishing the field dependence and nodal behavior of each freeform term that is essential knowledge for effective application to optical system design. With this development, the nodes that are distributed throughout the field of view for each aberration type can be anticipated and targeted during optimization for the correction or control of the aberrations in an optical system with freeform surfaces. This work does not place any symmetry constraints on the optical system, which could be packaged in a fully three dimensional geometry, without fold mirrors.
Chandler, Jacqueline; Rycroft-Malone, Jo; Hawkes, Claire; Noyes, Jane
2016-02-01
To examine the application of core concepts from Complexity Theory to explain the findings from a process evaluation undertaken in a trial evaluating implementation strategies for recommendations about reducing surgical fasting times. The proliferation of evidence-based guidance requires a greater focus on its implementation. Theory is required to explain the complex processes across the multiple healthcare organizational levels. This social healthcare context involves the interaction between professionals, patients and the organizational systems in care delivery. Complexity Theory may provide an explanatory framework to explain the complexities inherent in implementation in social healthcare contexts. A secondary thematic analysis of qualitative process evaluation data informed by Complexity Theory. Seminal texts applying Complexity Theory to the social context were annotated, key concepts extracted and core Complexity Theory concepts identified. These core concepts were applied as a theoretical lens to provide an explanation of themes from a process evaluation of a trial evaluating the implementation of strategies to reduce surgical fasting times. Sampled substantive texts provided a representative spread of theoretical development and application of Complexity Theory from late 1990's-2013 in social science, healthcare, management and philosophy. Five Complexity Theory core concepts extracted were 'self-organization', 'interaction', 'emergence', 'system history' and 'temporality'. Application of these concepts suggests routine surgical fasting practice is habituated in the social healthcare system and therefore it cannot easily be reversed. A reduction to fasting times requires an incentivised new approach to emerge in the surgical system's priority of completing the operating list. The application of Complexity Theory provides a useful explanation for resistance to change fasting practice. Its utility in implementation research warrants further attention and
Visualization of pool boiling from complex surfaces with internal tunnels
Directory of Open Access Journals (Sweden)
Pastuszko Robert
2012-04-01
Full Text Available The paper presents experimental investigations of boiling heat transfer for a system of connected narrow horizontal and vertical tunnels. These extended surfaces, named narrow tunnel structure (NTS, can be applied to electronic element cooling. The experiments were carried out with ethanol at atmospheric pressure. The tunnel external covers were manufactured out of 0.1 mm thick perforated copper foil (hole diameters 0.5 mm, sintered with the mini-fins, formed on the vertical side of the 10 mm high rectangular fins and horizontal inter-fin surface. Visualization studies were conducted with a transparent structured model of joined narrow tunnels limited with the perforated foil. The visualization investigations aimed to formulate assumptions for the boiling model through distinguishing boiling types and defining all phases of bubble growth.
Time Factor in the Theory of Anthropogenic Risk Prediction in Complex Dynamic Systems
Ostreikovsky, V. A.; Shevchenko, Ye N.; Yurkov, N. K.; Kochegarov, I. I.; Grishko, A. K.
2018-01-01
The article overviews the anthropogenic risk models that take into consideration the development of different factors in time that influence the complex system. Three classes of mathematical models have been analyzed for the use in assessing the anthropogenic risk of complex dynamic systems. These models take into consideration time factor in determining the prospect of safety change of critical systems. The originality of the study is in the analysis of five time postulates in the theory of anthropogenic risk and the safety of highly important objects. It has to be stressed that the given postulates are still rarely used in practical assessment of equipment service life of critically important systems. That is why, the results of study presented in the article can be used in safety engineering and analysis of critically important complex technical systems.
Theory of the surface dipole layer and of surface tension in liquids of charged particles
International Nuclear Information System (INIS)
Senatore, G.; Tosi, M.P.
1980-01-01
The problem of the surface density profiles and of the surface tension of a two-component liquid of charged particles in equilibrium with its vapour is examined. The exact equilibrium conditions for the profiles are given in terms of the inverse response functions of the inhomogeneous fluid, and alternative exact expressions for the surface tension are derived. The use of a density gradient expansion reduces the problem to knowledge of properties of a homogeneous charged fluid on a uniform neutralizing background, in which the total particle density and the charge density are independent variables. Additional simplifications are discussed for special cases for which a perturbative treatment of the surface charge density profile can be developed, and in particular for nearly symmetric ionic liquids and for simple liquid metals. (author)
Copper complexation capacity in surface waters of the Venice Lagoon.
Delgadillo-Hinojosa, Francisco; Zirino, Alberto; Nasci, Cristina
2008-10-01
Total copper (Cu(T)), copper ion activity (pCu) and the copper complexation capacity (CuCC) were determined in samples of seawater collected in July 2003 from the Venice Lagoon. Cu(T) and CuCC showed considerable spatial variability: Cu(T) ranged from 1.8 to 70.0nM, whereas the CuCC varied from 195 to 573nM. pCu values varied from 11.6 to 12.6 and are consistent with those previously reported in estuarine and coastal areas (10.9-14.1). The range of Cu(T) values compares well with those reported in the past in the lagoon and in the adjacent Adriatic Sea. The highest concentrations of Cu(T) were found in samples collected near the industrial area of Porto Marghera, whereas the lowest were measured near the Chioggia and Malamocco inlets, where an intense tidally-driven renewal of seawater takes place. Although CuCC showed a high degree of spatial variability, the values recorded in the Venice Lagoon are comparable to those reported in other estuarine systems. In addition, CuCC was positively correlated with dissolved organic carbon (DOC), suggesting that organic ligands responsible for Cu complexation are part of the bulk organic matter pool in the lagoon. The CuCC:Cu(T) molar ratio was, on average 55:1, indicating that a large excess of complexation capacity exists in the Venice Lagoon. The high levels of CuCC and the narrow range of pCu indicates the importance of the role played by organic ligands in controlling the free ion Cu concentrations in the lagoon, and as a consequence, regulating its availability and/or toxicity.
Complex Surface Concentration Gradients by Stenciled "Electro Click Chemistry"
DEFF Research Database (Denmark)
Hansen, Thomas Steen; Lind, Johan Ulrik; Daugaard, Anders Egede
2010-01-01
Complex one- or two-dimensional concentration gradients of alkynated molecules are produced on azidized conducting polymer substrates by stenciled "electro click chemistry". The latter describes the local electrochemical generation of catalytically active Cu(I) required to complete a "click...... reaction" between alkynes and azides at room temperature. A stencil on the counter electrode defines the shape and multiplicity of the gradient(s) on the conducting polymer substrate, while the specific reaction conditions control gradient steepness and the maximum concentration deposited. Biologically...
Cembran, Alessandro; Song, Lingchun; Mo, Yirong; Gao, Jiali
2010-01-01
A multistate density functional theory in the framework of the valence bond model is described. The method is based on a block-localized density functional theory (BLDFT) for the construction of valence-bond-like diabatic electronic states and is suitable for the study of electron transfer reactions and for the representation of reactive potential energy surfaces. The method is equivalent to a valence bond theory with the treatment of the localized configurations by using density functional theory (VBDFT). In VBDFT, the electron densities and energies of the valence bond states are determined by BLDFT. A functional estimate of the off-diagonal matrix elements of the VB Hamiltonian is proposed, making use of the overlap integral between Kohn–Sham determinants and the exchange-correlation functional for the ground state substituted with the transition (exchange) density. In addition, we describe an approximate approach, in which the off-diagonal matrix element is computed by wave function theory using block-localized Kohn–Sham orbitals. The key feature is that the electron density of the adiabatic ground state is not directly computed nor used to obtain the ground-state energy; the energy is determined by diagonalization of the multistate valence bond Hamiltonian. This represents a departure from the standard single-determinant Kohn–Sham density functional theory. The multistate VBDFT method is illustrated by the bond dissociation of H2+ and a set of three nucleophilic substitution reactions in the DBH24 database. In the dissociation of H2+, the VBDFT method yields the correct asymptotic behavior as the two protons stretch to infinity, whereas approximate functionals fail badly. For the SN2 nucleophilic substitution reactions, the hybrid functional B3LYP severely underestimates the barrier heights, while the approximate two-state VBDFT method overcomes the self-interaction error, and overestimates the barrier heights. Inclusion of the ionic state in a three
Fractal zeta functions and fractal drums higher-dimensional theory of complex dimensions
Lapidus, Michel L; Žubrinić, Darko
2017-01-01
This monograph gives a state-of-the-art and accessible treatment of a new general higher-dimensional theory of complex dimensions, valid for arbitrary bounded subsets of Euclidean spaces, as well as for their natural generalization, relative fractal drums. It provides a significant extension of the existing theory of zeta functions for fractal strings to fractal sets and arbitrary bounded sets in Euclidean spaces of any dimension. Two new classes of fractal zeta functions are introduced, namely, the distance and tube zeta functions of bounded sets, and their key properties are investigated. The theory is developed step-by-step at a slow pace, and every step is well motivated by numerous examples, historical remarks and comments, relating the objects under investigation to other concepts. Special emphasis is placed on the study of complex dimensions of bounded sets and their connections with the notions of Minkowski content and Minkowski measurability, as well as on fractal tube formulas. It is shown for the f...
Time-dependent--S-matrix Hartree-Fock theory of complex reactions
International Nuclear Information System (INIS)
Griffin, J.J.; Lichtner, P.C.; Dworzecka, M.
1980-01-01
Some limitations of the conventional time-dependent Hartree-Fock method for describing complex reactions are noted, and one particular ubiquitous defect is discussed in detail: the post-breakup spurious cross channel correlations which arise whenever several asymptotic reaction channels must be simultaneously described by a single determinant. A reformulated time-dependent--S-matrix Hartree-Fock theory is proposed, which obviates this difficulty. Axiomatic requirements minimal to assure that the time-dependent--S-matrix Hartree-Fock theory represents an unambiguous and physically interpretable asymptotic reaction theory are utilized to prescribe conditions upon the definition of acceptable asymptotic channels. That definition, in turn, defines the physical range of the time-dependent--S-matrix Hartree-Fock theory to encompass the collisions of mathematically well-defined ''time-dependent Hartree-Fock droplets.'' The physical properties of these objects then circumscribe the content of the Hartree-Fock single determinantal description. If their periodic vibrations occur for continuous ranges of energy then the resulting ''classical'' time-dependent Hartree-Fock droplets are seen to be intrinsically dissipative, and the single determinantal description of their collisions reduces to a ''trajectory'' theory which can describe the masses and relative motions of the fragments but can provide no information about specific asymptotic excited states beyond their constants of motion, or the average properties of the limit, if it exists, of their equilibrization process. If, on the other hand, the periodic vibrations of the time-dependent Hartree-Fock droplets are discrete in energy, then the time-dependent--S-matrix Hartree-Fock theory can describe asymptotically the time-average properties of the whole spectrum of such periodic vibrations
Energy Technology Data Exchange (ETDEWEB)
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.
Self-consistent field theory of block copolymers on a general curved surface.
Li, Jianfeng; Zhang, Hongdong; Qiu, Feng
2014-03-01
In this work, we propose a theoretical framework based on the self-consistent field theory (SCFT) for the study of self-assembling block copolymers on a general curved surface. Relevant numerical algorithms are also developed. To demonstrate the power of the approach, we calculate the self-assembled patterns of diblock copolymers on three distinct curved surfaces with different genus. We specially study the geometrical effects of curved surfaces on the conformation of polymer chains as well as on the pattern formation of block copolymers. By carefully examining the diffusion equation of the propagator on curved surfaces, it is predicted that Gaussian chains are completely unaware of the extrinsic curvature but that they will respond to the intrinsic curvature of the surface. This theoretical assertion is consistent with our SCFT simulations of block copolymers on general curved surfaces.
International Nuclear Information System (INIS)
Scripsick, R.C.; Rothenberg, S.J.
1986-01-01
Specific surface area (Sp) measurements were made on two uranium oxide aerosol materials before and after in vitro dissolution studies were performed on the materials. The results of these Sp measurements were evaluated relative to predictions made from extending Mercer dissolution theory to describe the Sp behavior of a dissolving population of particles
Calculation of Surface Tensions of Polar Mixtures with a Simplified Gradient Theory Model
DEFF Research Database (Denmark)
Zuo, You-Xiang; Stenby, Erling Halfdan
1996-01-01
Key Words: Thermodynamics, Simplified Gradient Theory, Surface Tension, Equation of state, Influence Parameter.In this work, assuming that the number densities of each component in a mixture across the interface between the coexisting vapor and liquid phases are linearly distributed, we developed...
Graph Complexes and the Moduli Space of Riemann Surfaces
DEFF Research Database (Denmark)
Egas Santander, Daniela
potentially allow to transfer constructions in fat graphs to the black and white model. Moreover, we compare Bödigheimer's radial slit configurations and the space of metric admissible fat graphs, producing an explicit homotopy equivalence using a "critical graph" map. This critical graph map descends...... to a homeomorphism between the Unimodular Harmonic compactification and the space of Sullivan diagrams, which are natural compactifications of the space of radial slit configurations and the space of metric admissible fat graphs, respectively. Finally, we use experimental methods to compute the homology of the chain......In this thesis we compare several combinatorial models for the moduli space of open-closed cobordisms and their compactifications. More precisely, we study Godin's category of admissible fat graphs, Costello's chain complex of black and white graphs, and Bödigheimer's space of radial slit...
K-complexes, spindles, and ERPs as impulse responses: unification via neural field theory.
Zobaer, M S; Anderson, R M; Kerr, C C; Robinson, P A; Wong, K K H; D'Rozario, A L
2017-04-01
To interrelate K-complexes, spindles, evoked response potentials (ERPs), and spontaneous electroencephalography (EEG) using neural field theory (NFT), physiology-based NFT of the corticothalamic system is used to model cortical excitatory and inhibitory populations and thalamic relay and reticular nuclei. The impulse response function of the model is used to predict the responses to impulses, which are compared with transient waveforms in sleep studies. Fits to empirical data then allow underlying brain physiology to be inferred and compared with other waves. Spontaneous K-complexes, spindles, and other transient waveforms can be reproduced using NFT by treating them as evoked responses to impulsive stimuli with brain parameters appropriate to spontaneous EEG in sleep stage 2. Using this approach, spontaneous K-complexes and sleep spindles can be analyzed using the same single theory as previously been used to account for waking ERPs and other EEG phenomena. As a result, NFT can explain a wide variety of transient waveforms that have only been phenomenologically classified to date. This enables noninvasive fitting to be used to infer underlying physiological parameters. This physiology-based model reproduces the time series of different transient EEG waveforms; it has previously reproduced experimental EEG spectra, and waking ERPs, and many other observations, thereby unifying transient sleep waveforms with these phenomena.
LENUS (Irish Health Repository)
Murray, Elizabeth
2010-10-20
Abstract Background The past decade has seen considerable interest in the development and evaluation of complex interventions to improve health. Such interventions can only have a significant impact on health and health care if they are shown to be effective when tested, are capable of being widely implemented and can be normalised into routine practice. To date, there is still a problematic gap between research and implementation. The Normalisation Process Theory (NPT) addresses the factors needed for successful implementation and integration of interventions into routine work (normalisation). Discussion In this paper, we suggest that the NPT can act as a sensitising tool, enabling researchers to think through issues of implementation while designing a complex intervention and its evaluation. The need to ensure trial procedures that are feasible and compatible with clinical practice is not limited to trials of complex interventions, and NPT may improve trial design by highlighting potential problems with recruitment or data collection, as well as ensuring the intervention has good implementation potential. Summary The NPT is a new theory which offers trialists a consistent framework that can be used to describe, assess and enhance implementation potential. We encourage trialists to consider using it in their next trial.
Directory of Open Access Journals (Sweden)
Ong Bie
2010-10-01
Full Text Available Abstract Background The past decade has seen considerable interest in the development and evaluation of complex interventions to improve health. Such interventions can only have a significant impact on health and health care if they are shown to be effective when tested, are capable of being widely implemented and can be normalised into routine practice. To date, there is still a problematic gap between research and implementation. The Normalisation Process Theory (NPT addresses the factors needed for successful implementation and integration of interventions into routine work (normalisation. Discussion In this paper, we suggest that the NPT can act as a sensitising tool, enabling researchers to think through issues of implementation while designing a complex intervention and its evaluation. The need to ensure trial procedures that are feasible and compatible with clinical practice is not limited to trials of complex interventions, and NPT may improve trial design by highlighting potential problems with recruitment or data collection, as well as ensuring the intervention has good implementation potential. Summary The NPT is a new theory which offers trialists a consistent framework that can be used to describe, assess and enhance implementation potential. We encourage trialists to consider using it in their next trial.
The theory of the interaction of atmospheric aerosol with underlying surface
International Nuclear Information System (INIS)
Buikov, M.V.
1993-01-01
The interaction of wind with underlying surfaces through resuspension makes a great contribution to the total amount of atmospheric aerosols. The dry deposition process results in cleaning of the atmosphere and contamination of near-surface air layers of soil and vegetation. This paper examines the theory leading to an exact solution of the problem of turbulent transportation of pollution taking into account resuspension and dry-deposition. This may be useful for the interpretation of observational data and for the improvement of calculation methods to describe aerosol exchange at surfaces in air. (author)
Transition state theory for solvated reactions beyond recrossing-free dividing surfaces.
Revuelta, F; Bartsch, Thomas; Garcia-Muller, P L; Hernandez, Rigoberto; Benito, R M; Borondo, F
2016-06-01
The accuracy of rate constants calculated using transition state theory depends crucially on the correct identification of a recrossing-free dividing surface. We show here that it is possible to define such optimal dividing surface in systems with non-Markovian friction. However, a more direct approach to rate calculation is based on invariant manifolds and avoids the use of a dividing surface altogether, Using that method we obtain an explicit expression for the rate of crossing an anharmonic potential barrier. The excellent performance of our method is illustrated with an application to a realistic model for LiNC⇌LiCN isomerization.
Scattering Theory on Surface Majorana Fermions by an Impurity in ^{3}He-B.
Tsutsumi, Yasumasa
2017-04-07
We have formulated the scattering theory on Majorana fermions emerging in the surface bound state of the superfluid ^{3}He B phase (^{3}He-B) by an impurity. By applying the theory to the electron bubble, which is regarded as the impurity, trapped below a free surface of ^{3}He-B, the observed mobility of the electron bubble [J. Phys. Soc. Jpn. 82, 124607 (2013)JUPSAU0031-901510.7566/JPSJ.82.124607] is quantitatively reproduced. The mobility is suppressed in low temperatures from the expected value in the bulk ^{3}He-B by the contribution from the surface Majorana fermions. By contrast, the mobility does not depend on the trapped depth of the electron bubble in spite of the spatial variation of the wave function of the surface Majorana fermions. Our formulated theory demonstrates the depth-independent mobility by considering intermediate states in the scattering process. Therefore, we conclude that the experiment has succeeded in observing Majorana fermions in the surface bound state.
General contact mechanics theory for randomly rough surfaces with application to rubber friction
Scaraggi, M.; Persson, B. N. J.
2015-12-01
We generalize the Persson contact mechanics and rubber friction theory to the case where both surfaces have surface roughness. The solids can be rigid, elastic, or viscoelastic and can be homogeneous or layered. We calculate the contact area, the viscoelastic contribution to the friction force, and the average interface separation as a function of the sliding speed and the nominal contact pressure. We illustrate the theory with numerical results for the classical case of a rubber block sliding on a road surface. We find that with increasing sliding speed, the influence of the roughness on the rubber block decreases to the extent that only the roughness of the stiff counter face needs to be considered.
Mechanisms for SAR imaging of ocean surface phenomena: Theory and experiment
Vesecky, J. F.
1983-01-01
Understanding the SAR response to surface wave is a central issue in the analysis of SAR ocean images. The imaging mechanism for gravity waves and the practical question of just which characteristics of the ocean wave field can be measured remotely using SAR were examined. Assessments of wave imaging theory are based primarily on comparisons of the directional wave height variance spectrum psi (K) measured by in situ buoys with estimates from SAR images. Other criteria are also recommended, e.g., the effects of focus adjustments. It is assumed that fluctuations in SAR image intensity are proportional to fluctuations in ocean surface height. If this were true, the Fourier power spectrum of a SAR image and corresponding surface measurements of psi would coincide. Differences between SAR estimates based on this hypothesis and buoy measurements of psi are then used to begin the assessment of rival wave imaging theories.
Ebrahimi, Farzad; Reza Barati, Mohammad
2017-01-01
In this research, vibration characteristics of a flexoelectric nanobeam in contact with Winkler-Pasternak foundation is investigated based on the nonlocal elasticity theory considering surface effects. This nonclassical nanobeam model contains flexoelectric effect to capture coupling of strain gradients and electrical polarizations. Moreover, the nonlocal elasticity theory is employed to study the nonlocal and long-range interactions between the particles. The present model can degenerate into the classical model if the nonlocal parameter, flexoelectric and surface effects are omitted. Hamilton's principle is employed to derive the governing equations and the related boundary conditions which are solved applying a Galerkin-based solution. Natural frequencies are verified with those of previous papers on nanobeams. It is illustrated that flexoelectricity, nonlocality, surface stresses, elastic foundation and boundary conditions affects considerably the vibration frequencies of piezoelectric nanobeams.
Coupled-Mode Theory for Complex-Index, Corrugated Multilayer Stacks
DEFF Research Database (Denmark)
Lüder, Hannes; Gerken, Martina; Adam, Jost
We present a coupled-mode theory (CMT) approach for modelling the modal behaviour of multi- layer thinfilm devices with complex material parameters and periodic corrugations. Our method provides fast computation and extended physical insight as compared to standard numerical methods. Nanostructur....... Express 22, A1363-A1371, 2014 [2] L. T. Neustock et al., Journal of Sensors, ArticleID 6174527, 2016 [3] J. Adam, H. Lüder, and M. Gerken, OWTNM 2015 [4] W.-P. Huang and J. Mu, Opt. Express 17, 19134-19152, 2009...
Three dimensional classical theory of rainbow scattering of atoms from surfaces
Energy Technology Data Exchange (ETDEWEB)
Pollak, Eli, E-mail: eli.pollak@weizmann.ac.il [Chemical Physics Department, Weizmann Institute of Science, 76100 Rehovoth (Israel); Miret-Artes, Salvador [Instituto de Fisica Fundamental, Consejo Superior de Investigaciones Cientificas, Serrano 123, 28006 Madrid (Spain)
2010-10-05
Graphical abstract: In this work, we extend to three dimensions our previous stochastic classical theory on surface rainbow scattering. The stochastic phonon bath is modeled in terms of linear coupling of the phonon modes to the motion of the scattered particle. We take into account the three polarizations of the phonons. Closed formulae are derived for the angular and energy loss distributions. They are readily implemented when assuming that the vertical interaction with the surface is described by a Morse potential. The hard wall limit of the theory is derived and applied to some model corrugated potentials. We find that rainbow structure of the scattered angular distribution reflects the underlying symmetries of the surface. We also distinguish between 'normal rainbows' and 'super rainbows'. The latter occur when the two eigenvalues of the Hessian of the corrugation function vanish simultaneously. - Abstract: In this work, we extend to three dimensions our previous stochastic classical theory on surface rainbow scattering. The stochastic phonon bath is modeled in terms of linear coupling of the phonon modes to the motion of the scattered particle. We take into account the three polarizations of the phonons. Closed formulae are derived for the angular and energy loss distributions. They are readily implemented when assuming that the vertical interaction with the surface is described by a Morse potential. The hard wall limit of the theory is derived and applied to some model corrugated potentials. We find that rainbow structure of the scattered angular distribution reflects the underlying symmetries of the surface. We also distinguish between 'normal rainbows' and 'super rainbows'. The latter occur when the two eigenvalues of the Hessian of the corrugation function vanish simultaneously.
Czech Academy of Sciences Publication Activity Database
Veselská, V.; Fajgar, Radek; Číhalová, S.; Bolanz, R.M.; Göttlicher, J.; Steininger, R.; Siddique, J.A.; Komárek, M.
2016-01-01
Roč. 318, NOV 15 (2016), s. 433-442 ISSN 0304-3894 Institutional support: RVO:67985858 Keywords : surface complexation modeling * chromate * soil minerals Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 6.065, year: 2016
Technology of magnetic abrasive finishing in machining of difficult-to-machine alloy complex surface
Directory of Open Access Journals (Sweden)
Fujian MA
2016-10-01
Full Text Available The technology of magnetic abrasive finishing is one of the important finishing technologies. Combining with low-frequency vibration and ultrasonic vibration, it can attain higher precision, quality and efficiency. The characteristics and the related current research of magnetic abrasive finishing, vibration assisted magnetic abrasive finishing and ultrasonic assisted magnetic abrasive finishing are introduced. According to the characteristics of the difficult-to-machine alloy's complex surface, the important problems for further study are presented to realize the finishing of complex surface with the technology of magnetic abrasive finishing, such as increasing the machining efficiency by enhancing the magnetic flux density of machining gap and compounding of magnetic energy and others, establishing of the control function during machining and the process planning method for magnetic abrasive finishing of complex surface under the space geometry restraint of complex surface on magnetic pole, etc.
Directory of Open Access Journals (Sweden)
Roger Bruce Mason
2013-05-01
Full Text Available This article proposes that the external environment influences the choice of distribution tactics. Since businesses and markets are complex adaptive systems, using complexity theory to understand such environments is necessary, but it has not been widely researched. A qualitative case method using in-depth interviews investigated four successful, versus less successful, companies in turbulent versus stable environments. The results tentatively confirmed that the more successful company, in a turbulent market, sees distribution activities as less important than other aspects of the marketing mix, but uses them to stabilise customer relationships and to maintain distribution processes. These findings can benefit marketers by emphasising a new way to consider place activities. How marketers can be assisted, and suggestions for further research, are provided.
Directory of Open Access Journals (Sweden)
Roger Bruce Mason
2013-11-01
Full Text Available This article proposes that the external environment influences the choice of distribution tactics. Since businesses and markets are complex adaptive systems, using complexity theory to understand such environments is necessary, but it has not been widely researched. A qualitative case method using in-depth interviews investigated four successful, versus less successful, companies in turbulent versus stable environments. The results tentatively confirmed that the more successful company, in a turbulent market, sees distribution activities as less important than other aspects of the marketing mix, but uses them to stabilise customer relationships and to maintain distribution processes. These findings can benefit marketers by emphasising a new way to consider place activities. How marketers can be assisted, and suggestions for further research, are provided.
Game theory and extremal optimization for community detection in complex dynamic networks.
Lung, Rodica Ioana; Chira, Camelia; Andreica, Anca
2014-01-01
The detection of evolving communities in dynamic complex networks is a challenging problem that recently received attention from the research community. Dynamics clearly add another complexity dimension to the difficult task of community detection. Methods should be able to detect changes in the network structure and produce a set of community structures corresponding to different timestamps and reflecting the evolution in time of network data. We propose a novel approach based on game theory elements and extremal optimization to address dynamic communities detection. Thus, the problem is formulated as a mathematical game in which nodes take the role of players that seek to choose a community that maximizes their profit viewed as a fitness function. Numerical results obtained for both synthetic and real-world networks illustrate the competitive performance of this game theoretical approach.
Rosso, Osvaldo A.; Craig, Hugh; Moscato, Pablo
2009-03-01
We introduce novel Information Theory quantifiers in a computational linguistic study that involves a large corpus of English Renaissance literature. The 185 texts studied (136 plays and 49 poems in total), with first editions that range from 1580 to 1640, form a representative set of its period. Our data set includes 30 texts unquestionably attributed to Shakespeare; in addition we also included A Lover’s Complaint, a poem which generally appears in Shakespeare collected editions but whose authorship is currently in dispute. Our statistical complexity quantifiers combine the power of Jensen-Shannon’s divergence with the entropy variations as computed from a probability distribution function of the observed word use frequencies. Our results show, among other things, that for a given entropy poems display higher complexity than plays, that Shakespeare’s work falls into two distinct clusters in entropy, and that his work is remarkable for its homogeneity and for its closeness to overall means.
Surface-Enhanced Raman Scattering of the Complexes of Silver with Adenine and dAMP
Otto, Cornelis; Hoeben, F.P.; Hoeben, F.P.; Greve, Jan
1991-01-01
The behaviour of adenine and 2'-deoxyadenosine-5'-monophosphate (dAMP) at positive surface potentials of a silver working electrode was investigated using surface-enhanced Raman scattering (SERS). The use of positive potentials in the presence of adenine or dAMP leads to a rapid accumulation of an intense spectrum. It is proposed that complexes of adenine (dAMP) with silver generate the observed spectra. Adenine and dAMP can be distinguished spectroscopically due to various different complexe...
Czech Academy of Sciences Publication Activity Database
Schwarz, H. H.; Lukáš, Jaromír; Richau, K.
2003-01-01
Roč. 218, 1-2 (2003), s. 1-9 ISSN 0376-7388 R&D Projects: GA AV ČR KSK4050111 Keywords : polyelectrolyte complex membranes * pervaporation * dehydration of organics Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.081, year: 2003
Sung, Dia; You, Yeongmahn; Song, Ji Hoon
2008-01-01
The purpose of this research is to explore the possibility of viable learning organizations based on identifying viable organizational learning mechanisms. Two theoretical foundations, complex system theory and viable system theory, have been integrated to provide the rationale for building the sustainable organizational learning mechanism. The…
Study of chemical bonding in the interhalogen complexes based on density functional theory
Energy Technology Data Exchange (ETDEWEB)
Poleshchuk, O. Kh., E-mail: poleshch@tspu.edu.ru [National Research Tomsk Polytechnic University (Russian Federation); Fateev, A. V.; Yarkova, A. G. [Tomsk State Pedagogical University (Russian Federation); Ermakhanov, M. N.; Saidakhmetov, P. A. [M. Auezov South Kazakhstan State University (Kazakhstan)
2016-12-15
The density functional theory analysis was used for a number XYL complexes (XY is a dihalogen molecule and L is a Lewis base), formed between molecules I{sub 2}, ICl, IBr and pyridine. The calculated geometrical parameters, IR spectra and nuclear quadrupole interaction constants of iodine are consistent with the data of microwave spectroscopy and nuclear quadrupole resonance. The good correlation between the experimental and calculated binding energies of the inner electrons of iodine, chlorine and nitrogen atoms were found with the calculation using both Gaussian and Slater functions. The comparison of experimental and calculated changes in the electron density on the atoms upon complex formation suggested the choice of scheme for calculating the effective charge on the atoms, which allow us to interpret the experimental spectra. It is shown that the use of both calculated schemes allows us to predict the enthalpy of complex formation in close agreement with the experimental values. The energy analysis shows that in the complexes the electrostatic binding energy dominates that of covalent binding.
Syntactic Parameters and a Coding Theory Perspective on Entropy and Complexity of Language Families
Directory of Open Access Journals (Sweden)
Matilde Marcolli
2016-04-01
Full Text Available We present a simple computational approach to assigning a measure of complexity and information/entropy to families of natural languages, based on syntactic parameters and the theory of error correcting codes. We associate to each language a binary string of syntactic parameters and to a language family a binary code, with code words the binary string associated to each language. We then evaluate the code parameters (rate and relative minimum distance and the position of the parameters with respect to the asymptotic bound of error correcting codes and the Gilbert–Varshamov bound. These bounds are, respectively, related to the Kolmogorov complexity and the Shannon entropy of the code and this gives us a computationally simple way to obtain estimates on the complexity and information, not of individual languages but of language families. This notion of complexity is related, from the linguistic point of view to the degree of variability of syntactic parameter across languages belonging to the same (historical family.
Uranium (VI)Bis(imido) chalcogenate complexes:synthesis and density functional theory analysis
Energy Technology Data Exchange (ETDEWEB)
Spencer, Liam P [Los Alamos National Laboratory; Batista, Enrique R [Los Alamos National Laboratory; Boncella, James M [Los Alamos National Laboratory; Yang, Ping [Los Alamos National Laboratory; Scott, Brian L [Los Alamos National Laboratory
2009-01-01
Bis(imido) uranium(VI) trans- and cis-dichalcogenate complexes with the general formula U(NtBu)2(EAr)2(OPPh3)2 (EAr = O-2-tBuC6H4, SPh, SePh, TePh) and U(NtBu)2(EAr)2(R2bpy) (EAr = SPh, SePh, TePh) (R2bpy = 4,4'-disubstituted-2,2'-bipyridyl, R = Me, tBu) have been prepared. This family of complexes includes the first reported monodentate selenolate and tellurolate complexes of uranium(VI). Density functional theory calculations show that covalent interactions in the U-E bond increase in the trans-dichalcogenate series U(NtBu)2(EAr)2(OPPh3)2 as the size of the chalcogenate donor increases and that both 5f and 6d orbital participation is important in the M-E bonds of U-S, U-Se, and U-Te complexes.
What item response theory can tell us about the complex span tasks.
Draheim, Christopher; Harrison, Tyler L; Embretson, Susan E; Engle, Randall W
2018-01-01
Working memory capacity is an important construct in psychology because of its relationship with many higher-order cognitive abilities and psychopathologies. Working memory capacity is often measured using a type of paradigm known as complex span. Some recent work has focused on shortening the administration time of the complex span tasks, resulting in different versions of these tasks being used (Foster et al., 2015; Oswald, McAbee, Redick, & Hambrick, 2015). Variations in the complex span tasks, such as the number of set sizes, can lead to varying power to discriminate individuals at different ability levels. Thus, research findings may be inconsistent across populations due to differing appropriateness for the ability levels. The present study uses a combination of item response theory and correlational analyses to better understand the psychometric properties of the operation span, symmetry span, and rotation span. The findings show that the typical administration of these tasks, particularly the operation span, is not suitable for above average ability samples (Study 1; n = 573). When larger set sizes are added to the tasks (Study 2; n = 351), predictive validity and discriminability is improved for all complex span tasks, however the operation span is still inferior to the spatial tasks. The authors make several conclusions about which tasks and set sizes should be used depending on the intended population, and further suggest avoiding the standard-length operation span for average or higher ability populations. (PsycINFO Database Record (c) 2018 APA, all rights reserved).
The spectral curve theory for (k, l)-symmetric CMC surfaces
Heller, Lynn; Heller, Sebastian; Schmitt, Nicholas
2015-12-01
Constant mean curvature surfaces in S3 can be studied via their associated family of flat connections. In the case of tori this approach has led to a deep understanding of the moduli space of all CMC tori. For compact CMC surfaces of higher genus the theory is far more involved due to the non abelian nature of their fundamental group. In this paper we extend the spectral curve theory for tori developed in Hitchin (1990), Pinkall and Sterling (1989) and for genus 2 surfaces (Heller, 2014) to CMC surfaces in S3 of genus g = k ṡ l with commuting Zk+1 and Zl+1 symmetries. We determine their associated family of flat connections via certain flat line bundle connections parametrized by the spectral curve. We generalize the flow on spectral data introduced in Heller (2015) and prove the short time existence of this flow for certain families of initial surfaces. In this way we obtain countably many 1 -parameter families of new CMC surfaces of higher genus with prescribed branch points and prescribed umbilics.
Rossberg, A.; Ulrich, K.U.; Weiss, S.; Tsushima, S.; Hiemstra, T.; Scheinost, A.C.
2009-01-01
Previous spectroscopic research suggested that uranium(VI) adsorption to iron oxides is dominated by ternary uranyl-carbonato surface complexes across an unexpectedly wide pH range. Formation of such complexes would have a significant impact on the sorption behavior and mobility of uranium in
Risk Modeling of Interdependent Complex Systems of Systems: Theory and Practice.
Haimes, Yacov Y
2018-01-01
The emergence of the complexity characterizing our systems of systems (SoS) requires a reevaluation of the way we model, assess, manage, communicate, and analyze the risk thereto. Current models for risk analysis of emergent complex SoS are insufficient because too often they rely on the same risk functions and models used for single systems. These models commonly fail to incorporate the complexity derived from the networks of interdependencies and interconnectedness (I-I) characterizing SoS. There is a need to reevaluate currently practiced risk analysis to respond to this reality by examining, and thus comprehending, what makes emergent SoS complex. The key to evaluating the risk to SoS lies in understanding the genesis of characterizing I-I of systems manifested through shared states and other essential entities within and among the systems that constitute SoS. The term "essential entities" includes shared decisions, resources, functions, policies, decisionmakers, stakeholders, organizational setups, and others. This undertaking can be accomplished by building on state-space theory, which is fundamental to systems engineering and process control. This article presents a theoretical and analytical framework for modeling the risk to SoS with two case studies performed with the MITRE Corporation and demonstrates the pivotal contributions made by shared states and other essential entities to modeling and analysis of the risk to complex SoS. A third case study highlights the multifarious representations of SoS, which require harmonizing the risk analysis process currently applied to single systems when applied to complex SoS. © 2017 Society for Risk Analysis.
Surface complexation of carbonate on goethite: IR spectroscopy, structure & charge distribution
Hiemstra, T.; Rahnemaie, R.; Riemsdijk, van W.H.
2004-01-01
The adsorption of carbonate on goethite has been evaluated, focussing on the relation between the structure of the surface complex and corresponding adsorption characteristics, like pH dependency and proton co-adsorption. The surface structure of adsorbed CO3-2 has been assessed with (1) a
Zhu, Yihan
2012-03-19
On the surface: The surface reconstruction of an MoVTeO complex metal oxide catalyst was observed directly by various electron microscopic techniques and the results explain the puzzling catalytic behavior. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
International Nuclear Information System (INIS)
Cao, Guangxi; Zhang, Qi; Li, Qingchen
2017-01-01
Highlights: • Mutual information is used as the edge weights of nodes instead of PCC, which overcomes the shortcomings of linear correlation functions. • SGD turns into a new cluster center and gradually becomes a point connecting the Asian and European clusters during and after the US sub-prime crisis. • Liang's entropy theory, which has not been adopted before in the global foreign exchange market, is considered. - Abstract: The foreign exchange (FX) market is a typical complex dynamic system under the background of exchange rate marketization reform and is an important part of the financial market. This study aims to generate an international FX network based on complex network theory. This study employs the mutual information method to judge the nonlinear characteristics of 54 major currencies in international FX markets. Through this method, we find that the FX network possesses a small average path length and a large clustering coefficient under different thresholds and that it exhibits small-world characteristics as a whole. Results show that the relationship between FX rates is close. Volatility can quickly transfer in the whole market, and the FX volatility of influential individual states transfers at a fast pace and a large scale. The period from July 21, 2005 to March 31, 2015 is subdivided into three sub-periods (i.e., before, during, and after the US sub-prime crisis) to analyze the topology evolution of FX markets using the maximum spanning tree approach. Results show that the USD gradually lost its core position, EUR remained a stable center, and the center of the Asian cluster became unstable. Liang's entropy theory is used to analyze the causal relationship between the four large clusters of the world.
Pump, Eva
2016-08-15
Dynamic Nuclear Polarization Surface Enhanced NMR Spectroscopy (DNP SENS) is an emerging technique that allows access to high-sensitivity NMR spectra from surfaces. However, DNP SENS usually requires the use of radicals as an exogenous source of polarization, which has so far limited applications for organometallic surface species to those that do not react with the radicals. Here we show that reactive surface species can be studied if they are immobilized inside porous materials with suitably small windows, and if bulky nitroxide bi-radicals (here TEKPol) are used as the polarization source and which cannot enter the pores. The method is demonstrated by obtaining significant DNP enhancements from highly reactive complelxes [(equivalent to Si-O-)W(Me)(5)] supported on MCM-41, and effects of pore size (6.0, 3.0 and 2.5 nm) on the performance are discussed.
Directory of Open Access Journals (Sweden)
Kinga K Hosszu
2012-03-01
Full Text Available The synthesis of the subunits of the C1 complex (C1q, C1s, C1r, and its regulator C1 inhibitor (C1-Inh by human monocytes has been previously established. However, surface expression of these molecules by monocytes has not been shown. Using flow cytometry and antigen-capture ELISA, we show here for the first time that, in addition to C1q, PB monocytes and the monocyte-derived U937 cells express C1s and C1r, as well as Factor B and C1-Inh on their surface. C1s and C1r immunoprecipitated with C1q, suggesting that at least some of the C1q on these cells is part of the C1 complex. Furthermore, the C1 complex on U937 cells was able to trigger complement activation via the classical pathway. The presence of C1-Inh may ensure that an unwarranted autoactivation of the C1 complex does not take place. Since C1-Inh closely monitors the activation of the C1 complex in a sterile or infectious inflammatory environment, further elucidation of the role of C1 complex is crucial to dissect its function in monocyte, DC and T cell activities, and its implications in host defense and tolerance.
Kim, Sang Bok; Pike, Robert D; Sweigart, Dwight A
2013-11-19
Quinonoid metal complexes have potential applications in surface chemistry, coordination polymers, and catalysts. Although quinonoid manganese tricarbonyl complexes have been used as secondary building units (SBUs) in the formation of novel metal-organometallic coordination networks and polymers, the potentially wider applications of these versatile linkers have not yet been recognized. In this Account, we focus on these diverse new applications of quinonoid metal complexes, and report on the variety of quinonoid metal complexes that we have synthesized. Through the use of [(η(6)-hydroquinone)Mn(CO)3](+), we are able to modify the surface of Fe3O4 and FePt nanoparticles (NPs). This process occurs either by the replacement of oleylamine with neutral [(η(5)-semiquinone)Mn(CO)3] at the NP surface, or by the binding of anionic [(η(4)-quinone)Mn(CO)3](-) upon further deprotonation of [(η(5)-semiquinone)Mn(CO)3] at the NP surface. We have demonstrated chemistry at the intersection of surface-modified NPs and coordination polymers through the growth of organometallic coordination polymers onto the surface modified Fe3O4 NPs. The resulting magnetic NP/organometallic coordination polymer hybrid material exhibited both the unique superparamagnetic behavior associated with Fe3O4 NPs and the paramagnetism attributable to the metal nodes, depending upon the magnetic range examined. By the use of functionalized [(η(5)-semiquinone)Mn(CO)3] complexes, we attained the formation of an organometallic monolayer on the surface of highly ordered pyrolitic graphite (HOPG). The resulting organometallic monolayer was not simply a random array of manganese atoms on the surface, but rather consisted of an alternating "up and down" spatial arrangement of Mn atoms extending from the HOPG surface due to hydrogen bonding of the quinonoid complexes. We also showed that the topology of metal atoms on the surface could be controlled through the use of quinonoid metal complexes. A quinonoid
DEFF Research Database (Denmark)
Snabe, Torben; Røder, Gustav Andreas; Neves-Petersen, Maria Teresa
2005-01-01
histocompatibility complex (MHC class I) to a sensor surface is presented. The coupling was performed using light assisted immobilisation--a novel immobilisation technology which allows specific opening of particular disulphide bridges in proteins which then is used for covalent bonding to thiol-derivatised surfaces...... via a new disulphide bond. Light assisted immobilisation specifically targets the disulphide bridge in the MHC-I molecule alpha(3)-domain which ensures oriented linking of the complex with the peptide binding site exposed away from the sensor surface. Structural analysis reveals that a similar...
Riemann surfaces and algebraic curves a first course in Hurwitz theory
Cavalieri, Renzo
2016-01-01
Hurwitz theory, the study of analytic functions among Riemann surfaces, is a classical field and active research area in algebraic geometry. The subject's interplay between algebra, geometry, topology and analysis is a beautiful example of the interconnectedness of mathematics. This book introduces students to this increasingly important field, covering key topics such as manifolds, monodromy representations and the Hurwitz potential. Designed for undergraduate study, this classroom-tested text includes over 100 exercises to provide motivation for the reader. Also included are short essays by guest writers on how they use Hurwitz theory in their work, which ranges from string theory to non-Archimedean geometry. Whether used in a course or as a self-contained reference for graduate students, this book will provide an exciting glimpse at mathematics beyond the standard university classes.
Sabadini, Irene; Struppa, Daniele; Vajiac, Mihaela
2017-01-01
This book gathers contributions written by Daniel Alpay’s friends and collaborators. Several of the papers were presented at the International Conference on Complex Analysis and Operator Theory held in honor of Professor Alpay’s 60th birthday at Chapman University in November 2016. The main topics covered are complex analysis, operator theory and other areas of mathematics close to Alpay’s primary research interests. The book is recommended for mathematicians from the graduate level on, working in various areas of mathematical analysis, operator theory, infinite dimensional analysis, linear systems, and stochastic processes.
Comparative Research to Surface Aeration and Blasting Aeration System Based on LCC Theory
Liai, CHEN; Hongxun, HOU; Weibiao, FEI; Eryan, ZHAO
2017-05-01
It is difficult to select the suitable aeration system for the designers of wastewater treatment plant (WWTP). In this paper, taking two WWTPs with surface aeration systems and blasting aeration respectively for an example, LCC theory was adapted to analysis the cost of consumption and the environmental impact, which caused by the different aeration system. Research results showed that: (1) In the 20-year life cycle, the LCC mainly depended on the cost of energy consumption whatever blasting aeration system or surface aeration, while the LCC of blasting aeration system affected by the equipment maintenance cost, maintenance cost, economic losses caused by wastewater loss and environmental load in maintenance period. (2) The LCC of blasting aeration system was lower than the surface aeration in general, on the premise of the standard discharge; (3) the blasting aeration system estimated a saving of 60,0000RMB annually in costs compared with the surface aeration.
Rubber friction on road surfaces: Experiment and theory for low sliding speeds
Energy Technology Data Exchange (ETDEWEB)
Lorenz, B.; Persson, B. N. J. [PGI, FZ Jülich, 52425 Jülich (Germany); Oh, Y. R.; Nam, S. K.; Jeon, S. H. [Hankook Tire Co. LTD., 112 Gajeongbuk-ro, Yuseong-gu, Daejeon 305-725 (Korea, Republic of)
2015-05-21
We study rubber friction for tire tread compounds on asphalt road surfaces. The road surface topographies are measured using a stylus instrument and atomic force microscopy, and the surface roughness power spectra are calculated. The rubber viscoelastic modulus mastercurves are obtained from dynamic mechanical analysis measurements and the large-strain effective modulus is obtained from strain sweep data. The rubber friction is measured at different temperatures and sliding velocities, and is compared to the calculated data obtained using the Persson contact mechanics theory. We conclude that in addition to the viscoelastic deformations of the rubber surface by the road asperities, there is an important contribution to the rubber friction from shear processes in the area of contact. The analysis shows that the latter contribution may arise from rubber molecules (or patches of rubber) undergoing bonding-stretching-debonding cycles as discussed in a classic paper by Schallamach.
Applying complexity theory: A primer for identifying and modeling firm anomalies
Directory of Open Access Journals (Sweden)
Arch G. Woodside
2018-01-01
Full Text Available This essay elaborates on the usefulness of embracing complexity theory, modeling outcomes rather than directionality, and modeling complex rather than simple outcomes in strategic management. Complexity theory includes the tenet that most antecedent conditions are neither sufficient nor necessary for the occurrence of a specific outcome. Identifying a firm by individual antecedents (i.e., non-innovative versus highly innovative, small versus large size in sales or number of employees, or serving local versus international markets provides shallow information in modeling specific outcomes (e.g., high sales growth or high profitability—even if directional analyses (e.g., regression analysis, including structural equation modeling indicates that the independent (main effects of the individual antecedents relate to outcomes directionally—because firm (case anomalies almost always occur to main effects. Examples: a number of highly innovative firms have low sales while others have high sales and a number of non-innovative firms have low sales while others have high sales. Breaking-away from the current dominant logic of directionality testing—null hypotheses statistic testing (NHST—to embrace somewhat precise outcome testing (SPOT is necessary for extracting highly useful information about the causes of anomalies—associations opposite to expected and “statistically significant” main effects. The study of anomalies extends to identifying the occurrences of four-corner strategy outcomes: firms doing well in favorable circumstances, firms doing badly in favorable circumstances, firms doing well in unfavorable circumstances, and firms doing badly in unfavorable circumstances. Models of four-corner strategy outcomes advances strategic management beyond the current dominant logic of directional modeling of single outcomes.
Modeling butadiene adsorption on oxidized graphene surface using density functional theory
Akimenko, Ju. Y.; Akimenko, S. S.; Gorbunov, V. A.
2017-08-01
In this paper, the process of chemisorption of cis-butadiene rubber on the surface of oxidized graphene was studied using the density functional theory. The polymer is interacting to a quinone group, an oxygen bridge, and an OH group which was differently located on the surface of the graphene sheet. Based on the calculated value of ΔG298, the possibility of spontaneous formation of the bond between butadiene rubber and these functional groups was estimated. The features of the temperature dependence of the change in free Gibbs energy for thermodynamically possible coupled systems are considered.
Asymptotic theory of dissipative trapped electron mode overlapping many rational surfaces
International Nuclear Information System (INIS)
Rogister, A.; Hasselberg, G.
1978-01-01
The two dimensional eigenvalue equation describing the dissipative trapped electron mode is solved exactly in the limit of the mode overlapping many rational surfaces using the Pogutse model for the magnetic field and the pitch angle collision operator. The trapped electron contribution to the growth rate decreases, with respect to the standard theory, by a factor of order Δ/chi sub(T) << 1 where chi sub(T) is the position of the turning point and Δ the distance between rational surfaces
Khlyupin, Aleksey; Aslyamov, Timur
2017-06-01
Realistic fluid-solid interaction potentials are essential in description of confined fluids especially in the case of geometric heterogeneous surfaces. Correlated random field is considered as a model of random surface with high geometric roughness. We provide the general theory of effective coarse-grained fluid-solid potential by proper averaging of the free energy of fluid molecules which interact with the solid media. This procedure is largely based on the theory of random processes. We apply first passage time probability problem and assume the local Markov properties of random surfaces. General expression of effective fluid-solid potential is obtained. In the case of small surface irregularities analytical approximation for effective potential is proposed. Both amorphous materials with large surface roughness and crystalline solids with several types of fcc lattices are considered. It is shown that the wider the lattice spacing in terms of molecular diameter of the fluid, the more obtained potentials differ from classical ones. A comparison with published Monte-Carlo simulations was discussed. The work provides a promising approach to explore how the random geometric heterogeneity affects on thermodynamic properties of the fluids.
International Nuclear Information System (INIS)
Sugioka, Yuji; Takayanagi, Toshiyuki
2012-01-01
Highlights: ► Dissociative electron attachment cross sections for polyatomic molecules are calculated by a simple theoretical approach. ► Temperature effects can be reasonably reproduced with the present model. ► All the degrees-of-freedom are taken into account in the present dynamics approach. -- Abstract: We propose a practical computational scheme to obtain temperature dependence of dissociative electron attachment cross sections to polyatomic molecules within a local complex potential theory formalism. First we perform quantum path-integral molecular dynamics simulations on the potential energy surface for the neutral molecule in order to sample initial nuclear configurations as well as momenta. Classical trajectories are subsequently integrated on the potential energy surface for the anionic state and survival probabilities are simultaneously calculated along the obtained trajectories. We have applied this simple scheme to dissociative electron attachment processes to H 2 O and CF 3 Cl, for which several previous studies are available from both the experimental and theoretical sides.
Medan, R. T.; Ray, K. S.
1974-01-01
A description of and users manual are presented for a U.S.A. FORTRAN 4 computer program which evaluates spanwise and chordwise loading distributions, lift coefficient, pitching moment coefficient, and other stability derivatives for thin wings in linearized, steady, subsonic flow. The program is based on a kernel function method lifting surface theory and is applicable to a large class of planforms including asymmetrical ones and ones with mixed straight and curved edges.
International Nuclear Information System (INIS)
Toppan, Francesco
2004-01-01
Relying upon the division-algebra classification of Clifford algebras and spinors, a classification of generalized supersymmetries (or, with a slight abuse of language,'generalized supertranslations') is provided. In each given space-time the maximal, saturated, generalized supersymmetry, compatible with the division-algebra constraint that can be consistently imposed on spinors and on superalgebra generators, is furnished. Constraining the superalgebra generators in both the complex and the quaternionic cases gives rise to the two classes of constrained hermitean and holomorphic generalized supersymmetries. In the complex case these two classes of generalized supersymmetries can be regarded as complementary. The quaternionic holomorphic supersymmetry only exists in certain space-time dimensions and can admit at most a single bosonic scalar central charge. The results here presented pave the way for a better understanding of the various M algebra-type of structures which can be introduced in different space-time signatures and in association with different division algebras, as well as their mutual relations. In a previous work, e.g., the introduction of a complex holomorphic generalized supersymmetry was shown to be necessary in order to perform the analytic continuation of the standard M-theory to the 11-dimensional euclidean space. As an application of the present results, it is shown that the above algebra also admits a 12-dimensional, euclidean, F-algebra presentation. (author)
Directory of Open Access Journals (Sweden)
Reza Kalantari
2017-10-01
Full Text Available This longitudinal case study explored Iranian EFL learners’ lexical complexity (LC through the lenses of Dynamic Systems Theory (DST. Fifty independent essays written by five intermediate to advanced female EFL learners in a TOEFL iBT preparation course over six months constituted the corpus of this study. Three Coh-Metrix indices (Graesser, McNamara, Louwerse, & Cai, 2004; McNamara & Graesser, 2012, three Lexical Complexity Analyzer indices (Lu, 2010, 2012; Lu & Ai, 2011, and four Vocabprofile indices (Cobb, 2000 were selected to measure different dimensions of LC. Results of repeated measures analysis of variance (RM ANOVA indicated an improvement with regard to only lexical sophistication. Positive and significant relationships were found between time and mean values in Academic Word List and Beyond-2000 as indicators of lexical sophistication. The remaining seven indices of LC, falling short of significance, tended to flatten over the course of this writing program. Correlation analyses among LC indices indicated that lexical density enjoyed positive correlations with lexical sophistication. However, lexical diversity revealed no significant correlations with both lexical density and lexical sophistication. This study suggests that DST perspective specifies a viable foundation for analyzing lexical complexity
Identifying driving gene clusters in complex diseases through critical transition theory
Wolanyk, Nathaniel; Wang, Xujing; Hessner, Martin; Gao, Shouguo; Chen, Ye; Jia, Shuang
A novel approach of looking at the human body using critical transition theory has yielded positive results: clusters of genes that act in tandem to drive complex disease progression. This cluster of genes can be thought of as the first part of a large genetic force that pushes the body from a curable, but sick, point to an incurable diseased point through a catastrophic bifurcation. The data analyzed is time course microarray blood assay data of 7 high risk individuals for Type 1 Diabetes who progressed into a clinical onset, with an additional larger study requested to be presented at the conference. The normalized data is 25,000 genes strong, which were narrowed down based on statistical metrics, and finally a machine learning algorithm using critical transition metrics found the driving network. This approach was created to be repeatable across multiple complex diseases with only progression time course data needed so that it would be applicable to identifying when an individual is at risk of developing a complex disease. Thusly, preventative measures can be enacted, and in the longer term, offers a possible solution to prevent all Type 1 Diabetes.
International Nuclear Information System (INIS)
Toppan, Francesco
2004-06-01
Relying upon the division-algebra classification of Clifford algebras and spinors, a classification of generalized supersymmetries (or, with a slight abuse of language, 'generalized super translations') is provided. In each given space-time the maximal, saturated, generalized supersymmetry, compatible with the division-algebra constraint that can be consistently imposed on spinors and on superalgebra generators, is furnished. Constraining the superalgebra generators in both the complex and the quaternionic cases gives rise to the two classes of constrained hermitian and holomorphic generalized supersymmetries. In the complex case these two classes of generalized supersymmetries can be regarded as complementary. The quaternionic holomorphic supersymmetry only exists in certain space-time dimensions and can admit at most a single bosonic scalar central charge. The results here presented pave the way for a better understanding of the various M algebra-type of structures which can be introduced in different space-time signatures and in association with different division algebras, as well as their mutual relations. In a previous work, e.g., the introduction of a complex holomorphic generalized supersymmetry was shown to be necessary in order to perform the analytic continuation of the standard M-theory to the 11-dimensional Euclidean space. As an application of the present results, it is shown that the above algebra also admits a 12-dimensional, Euclidean, F-algebra presentation. (author)
Saffari, Shahab; Hashemian, Mohammad; Toghraie, Davood
2017-09-01
Based on nonlocal Timoshenko beam theory, dynamic stability of functionally graded (FG) nanobeam under axial and thermal loading was investigated. Surface stress effects were implemented according to Gurtin-Murdoch continuum theory. Using power law distribution for FGM and von Karman geometric nonlinearity, governing equations were derived based on Hamilton's principle. The developed nonlocal models have the capability of interpreting small scale effects. Pasternak elastic medium was employed to represent the interaction of the FG nanobeam and the surrounding elastic medium. A parametric study was conducted to focus influences of the static load factor, temperature change, gradient index, nonlocal parameter, slenderness ratio, surface effect and springs constants of the elastic medium on the dynamic instability region (DIR) of the FG beam with simply-supported boundary conditions. It was found that differences between DIRs predicted by local and nonlocal beam theories are significant for beams with lower aspect ratio. Moreover, it was observed that in contrast to high temperature environments, at low temperatures, increasing the temperature change moves the origin of the DIR to higher excitation frequency zone and leads to further stability. Considering surface stress effects shifts the DIR of FG beam to higher frequency zone, also increasing the gradient index enhances the frequency of DIR.
The applications of Complexity Theory and Tsallis Non-extensive Statistics at Solar Plasma Dynamics
Pavlos, George
2015-04-01
As the solar plasma lives far from equilibrium it is an excellent laboratory for testing complexity theory and non-equilibrium statistical mechanics. In this study, we present the highlights of complexity theory and Tsallis non extensive statistical mechanics as concerns their applications at solar plasma dynamics, especially at sunspot, solar flare and solar wind phenomena. Generally, when a physical system is driven far from equilibrium states some novel characteristics can be observed related to the nonlinear character of dynamics. Generally, the nonlinearity in space plasma dynamics can generate intermittent turbulence with the typical characteristics of the anomalous diffusion process and strange topologies of stochastic space plasma fields (velocity and magnetic fields) caused by the strange dynamics and strange kinetics (Zaslavsky, 2002). In addition, according to Zelenyi and Milovanov (2004) the complex character of the space plasma system includes the existence of non-equilibrium (quasi)-stationary states (NESS) having the topology of a percolating fractal set. The stabilization of a system near the NESS is perceived as a transition into a turbulent state determined by self-organization processes. The long-range correlation effects manifest themselves as a strange non-Gaussian behavior of kinetic processes near the NESS plasma state. The complex character of space plasma can also be described by the non-extensive statistical thermodynamics pioneered by Tsallis, which offers a consistent and effective theoretical framework, based on a generalization of Boltzmann - Gibbs (BG) entropy, to describe far from equilibrium nonlinear complex dynamics (Tsallis, 2009). In a series of recent papers, the hypothesis of Tsallis non-extensive statistics in magnetosphere, sunspot dynamics, solar flares, solar wind and space plasma in general, was tested and verified (Karakatsanis et al., 2013; Pavlos et al., 2014; 2015). Our study includes the analysis of solar plasma time
Borowski, Susan C.; Biswakarma, Jagannath; Kang, Kyounglim; Schenkeveld, Walter D. C.; Hering, Janet G.; Kubicki, James D.; Kraemer, Stephan M.; Hug, Stephan J.
2018-04-01
Oxalate, together with other ligands, plays an important role in the dissolution of iron(hdyr)oxides and the bio-availability of iron. The formation and properties of oxalate surface complexes on lepidocrocite were studied with a combination of infrared spectroscopy (IR), density functional theory (DFT) calculations, dissolution, and photochemical experiments. IR spectra measured as a function of time, concentration, and pH (50-200 μM oxalate, pH 3-7) showed that several surface complexes are formed at different rates and in different proportions. Measured spectra could be separated into three contributions described by Gaussian line shapes, with frequencies that agreed well with the theoretical frequencies of three different surface complexes: an outer-sphere complex (OS), an inner-sphere monodentate mononuclear complex (MM), and a bidentate mononuclear complex (BM) involving one O atom from each carboxylate group. At pH 6, OS was formed at the highest rate. The contribution of BM increased with decreasing pH. In dissolution experiments, lepidocrocite was dissolved at rates proportional to the surface concentration of BM, rather than to the total adsorbed concentration. Under UV-light (365 nm), BM was photolyzed at a higher rate than MM and OS. Although the comparison of measured spectra with calculated frequencies cannot exclude additional possible structures, the combined results allowed the assignment of three main structures with different reactivities consistent with experiments. The results illustrate the importance of the surface speciation of adsorbed ligands in dissolution and photochemical reactions.
International Nuclear Information System (INIS)
Bertolino, María Candelaria; Granados, Alejandro Manuel
2016-01-01
Highlights: • Fischer carbene 1-W reacts via cycloaddition without Cu(I) with azide terminal surface. • This reaction on the surface is regioselective to internal triple bond of 1-W. • 1-W bound to glass surface produce AuNps in situ fixed to the surface. • This ability is independent of how 1-W is bonded to the surface. • This hybrid surface can be valuable as SERS substrate or in heterogeneous catalysis. - Abstract: In this work we present a detailed study of classic reactions such as “click reaction” and nucleophilic substitution reaction but on glass solid surface (slides). We used different reactive center of a dialkynylalcoxy Fischer carbene complex of tungsten(0) to be anchored to modified glass surface with amine, to obtain aminocarbene, and azide terminal groups. These cycloaddition reaction showed regioselectivity to internal triple bond of dialkynyl Fischer carbene complex without Cu(I) as catalyst. Anyway the carbene anchored was able to act as a reducing agent to produce in situ very stable gold nanoparticles fixed on surface. We showed the characterization of modified glasses by contact angle measurements and XPS. Synthesized nanoparticles were characterized by SEM, XPS, EDS and UV–vis. The modified glasses showed an important enhancement Raman-SERS. This simple, fast and robust method to create a polifunctional and hybrid surfaces can be valuable in a wide range of applications such as Raman-SERS substrates and other optical fields.
The significance of surface complexation reactions in hydrologic systems: a geochemist's perspective
Koretsky, C.
2000-05-01
Complexation reactions at the mineral-water interface affect the transport and transformation of metals and organic contaminants, nutrient availability in soils, formation of ore deposits, acidification of watersheds and the global cycling of elements. Such reactions can be understood by quantifying speciation reactions in homogeneous aqueous solutions, characterizing reactive sites at mineral surfaces and developing models of the interactions between aqueous species at solid surfaces. In this paper, the application of thermodynamic principles to quantify aqueous complexation reactions is described. This is followed by a brief overview of a few of the methods that have been used to characterize reactive sites on mineral surfaces. Next, the application of empirical and semi-empirical models of adsorption at the mineral-water interface, including distribution coefficients, simple ion exchange models, and Langmuir and Freundlich isotherms is discussed. Emphasis is placed on the limitations of such models in providing an adequate representation of adsorption in hydrological systems. These limitations arise because isotherms do not account for the structure of adsorbed species, nor do they account for the development of surface charge with adsorption. This is contrasted with more sophisticated models of adsorption, termed 'surface complexation models', which include the constant capacitance model, the diffuse layer model, the triple layer model and the MUSIC model. In these models, speciation reactions between surface functional groups and dissolved species control the variable surface charge build-up and the specific adsorption properties of minerals in aqueous solutions. Next, the influence of mineral surface speciation on the reactivity of adsorbed species and on far from equilibrium dissolution rates of minerals is discussed. Finally, the applicability of microscopic models of surface complexation to field-scale systems is explored and the need to integrate
Effects of electric field on a copper–dioxolene complex adsorbed on a gold surface
Energy Technology Data Exchange (ETDEWEB)
Kostyrko, T., E-mail: tkos@amu.edu.pl; Ślusarski, T.
2016-06-15
Highlights: • Cu–dioxolene complex at Au(1 1 1) surface in electric field was studied with a DFT+U method. • Two valence tautomers of the adsorbed Cu–dioxolene complex were described. • Coulomb correlations on Cu make driving force for valence tautomeric transitions. • Electric field of strength of 0.5 V/Å can almost fully ionize the adsorbed complex. - Abstract: A model of a copper–dioxolene complex linked to Au(1 1 1) surface with butanethiol linker is investigated using first-principles methods. It is shown that the complex adsorbed at the surface may appear in various locally stable structural forms differing in electron charge and spin density distribution, the symmetric high spin (HS) one and the twisted low spin (LS) structure. The electric field directed perpendicular to the surface controls the amount of the charge transfer between the complex and the substrate, starting from the zero-field value of Q = +0.18 |e| up to the value of Q = +0.94 |e| for the field strength of E = 0.5 V/Å. The field modifies also the mutual stability of the two structural forms, reducing the energy gap between the more energetically stable LS twisted form and the symmetrical HS one, from a value of Δ ∼ 0.29 eV in absence of the field to Δ ∼ 0.11 eV for the field strength of E = 0.35 V/Å.
The contribution of process tracing to theory-based evaluations of complex aid instruments
DEFF Research Database (Denmark)
Beach, Derek; Schmitt, Johannes
2015-01-01
studies in demanding settings. For the specific task of evaluating the governance effectiveness of budget support interventions, we developed a more fine-grained causal mechanism for a subset of the comprehensive program theory of budget support. Moreover, based on the informal use of Bayesian logic, we...... have elaborated on how to increase the conclusiveness of empirical evidence for one part of the theorized causal mechanism. We argue that by establishing an explicit theorized mechanism prior to empirical research and by critically judging our evidence according to an informal Bayesian logic we can...... remedy some of the problems at hand in much case-study research and increase the inferential leverage in complex within-case evaluation studies....
Shi, Xizhi; He, Chaoyu; Pickard, Chris J.; Tang, Chao; Zhong, Jianxin
2018-01-01
A method is introduced to stochastically generate crystal structures with defined structural characteristics. Reasonable quotient graphs for symmetric crystals are constructed using a random strategy combined with space group and graph theory. Our algorithm enables the search for large-size and complex crystal structures with a specified connectivity, such as threefold sp2 carbons, fourfold sp3 carbons, as well as mixed sp2-sp3 carbons. To demonstrate the method, we randomly construct initial structures adhering to space groups from 75 to 230 and a range of lattice constants, and we identify 281 new sp3 carbon crystals. First-principles optimization of these structures show that most of them are dynamically and mechanically stable and are energetically comparable to those previously proposed. Some of the new structures can be considered as candidates to explain the experimental cold compression of graphite.
DEFF Research Database (Denmark)
Abbasi, Maisam
identify, classify, and tackle the challenges that can hinder the execution of such strategies. To develop innovative strategies, the patterns of current trends and themes need to be learned and the missing ones need to be identified. The purpose of this research was to explore themes and challenges......To develop sustainable supply chains in a way that their negative environmental and social effects are minimized, shortand long-term targets should be set. The transformation of supply chains towards these targets calls for the development of innovative strategies and the need to continuously...... freight transport (RS3), one, urban freight distribution (RS4), and one, logistical services (RS5) in particular. RS6 explored a complexity theory perspective (CTP) on managing, governing, and developing sustainable supply chains activities. A CTP was chosen because of its applicability and ability...
A Statistical Test of Walrasian Equilibrium by Means of Complex Networks Theory
Bargigli, Leonardo; Viaggiu, Stefano; Lionetto, Andrea
2016-10-01
We represent an exchange economy in terms of statistical ensembles for complex networks by introducing the concept of market configuration. This is defined as a sequence of nonnegative discrete random variables {w_{ij}} describing the flow of a given commodity from agent i to agent j. This sequence can be arranged in a nonnegative matrix W which we can regard as the representation of a weighted and directed network or digraph G. Our main result consists in showing that general equilibrium theory imposes highly restrictive conditions upon market configurations, which are in most cases not fulfilled by real markets. An explicit example with reference to the e-MID interbank credit market is provided.
International Nuclear Information System (INIS)
Evans, R.; Kumaravadivel, R.
1976-01-01
A simple scheme for determining the ion density profile and the surface tension of a liquid metal is described. Assuming that the interaction between metallic pseudo-ions is of the form introduced by Evans, an approximate expression for the excess free energy of the system is derived using the thermodynamic perturbation theory of Weeks, Chandler and Anderson. This excess free energy is then minimized with respect to a parameter which specifies the ion density profile, and the surface tension is given directly. From a consideration of the dependence of the interionic forces on the electron density it is predicted that the ions should take up a very steep density profile at the liquid metal surface. This behaviour is contrasted with that to be expected for rare-gas fluids in which the interatomic forces are density-independent. The values of the surface tension calculated for liquid Na, K and Al from a simplified version of the theory are in reasonable agreement with experiment. (author)
Perdigão, Rui A. P.; Hall, Julia; Pires, Carlos A. L.; Blöschl, Günter
2017-04-01
Classical and stochastic dynamical system theories assume structural coherence and dynamic recurrence with invariants of motion that are not necessarily so. These are grounded on the unproven assumption of universality in the dynamic laws derived from statistical kinematic evaluation of non-representative empirical records. As a consequence, the associated formulations revolve around a restrictive set of configurations and intermittencies e.g. in an ergodic setting, beyond which any predictability is essentially elusive. Moreover, dynamical systems are fundamentally framed around dynamic codependence among intervening processes, i.e. entail essentially redundant interactions such as couplings and feedbacks. That precludes synergistic cooperation among processes that, whilst independent from each other, jointly produce emerging dynamic behaviour not present in any of the intervening parties. In order to overcome these fundamental limitations, we introduce a broad class of non-recursive dynamical systems that formulate dynamic emergence of unprecedented states in a fundamental synergistic manner, with fundamental principles in mind. The overall theory enables innovations to be predicted from the internal system dynamics before any a priori information is provided about the associated dynamical properties. The theory is then illustrated to anticipate, from non-emergent records, the spatiotemporal emergence of multiscale hyper chaotic regimes, critical transitions and structural coevolutionary changes in synthetic and real-world complex systems. Example applications are provided within the hydro-climatic context, formulating and dynamically forecasting evolving hydro-climatic distributions, including the emergence of extreme precipitation and flooding in a structurally changing hydro-climate system. Validation is then conducted with a posteriori verification of the simulated dynamics against observational records. Agreement between simulations and observations is
Universal dynamics of complex adaptive systems: Gauge theory of things alive
International Nuclear Information System (INIS)
Mack, G.
1994-04-01
A universal dynamics of objects and their relations - a kind of ''universal chemistry'' - is discussed which satisfies general principles of locality and relativity. Einsteins theory of gravitation and the gauge theory of elementary particles are prototypes, but complex adaptive systems - anything that is alive in the widest sense - fall under the same paradigma. Frustration and gauge symmetry arise naturally in this context. Besides a nondissipative deterministic dynamics, which is thought to operate at a fundamental levle, a Thermo-Dynamics in sense of Prigogine is introduced by adding a diffusion process. It introduces irreversibility and entropy production. It equilibrates the chaotic local model of the time development (only) and is designed to be undetectable under continued observation with given finite measuring accuracy. Compositeness and the development of structure can be described in this framework. The existence of a critical equilibrium state may be postulated which is invariant under the dynamics. But it is usually not reached in a finite time from a given starting configuration, because local dynamics suffers from critical slowing down, especially in the presence of frustration. (orig.)
Methyl Butanoate Adsorption on MoS2 Surface: A Density Functional Theory Investigation
Directory of Open Access Journals (Sweden)
Prabowo Wahyu Aji Eko
2018-01-01
Full Text Available Methyl butanoate is one of the compound which is obtained from triglyceride molecule. It has hydrocarbon components and hence may produce hydrocarbon through hydrodeoxygenation (HDO or decarbonylation (DCO processes. The first step to uncover the underlying mechanism of HDO or DCO is to find the active site of methyl butanoate adsorption over the catalyst. This study attempts to investigate the active site of methyl butanoate adsorption on MoS2 surface. Stable bonding configuration for methyl butanoate adsorption on MoS2 is investigated by using density functional theory (DFT. This investigation consists of geometry optimisation and adsorption energy calculations. The stable configuration of methyl butanoate adsorption on MoS2 surface is found to be on top of Mo atom in Mo-edge surface.
Moore, Graham F; Evans, Rhiannon E
2017-12-01
Recent years have seen a growing emphasis on the value of building and testing middle range theory throughout the development and evaluation of complex population health interventions. We agree that a coherent theoretical basis for intervention development, and use of evaluation to test key causal assumptions and build theory, are crucial. However, in this editorial, we argue that such recommendations have often been operationalised in somewhat simplistic terms with potentially perverse consequences, and that an uncritical assumption that an intervention explicitly based on theory is inherently superior carries significant risks. We first argue that the drive for theory-based approaches may have exacerbated a propensity to select 'off-the-shelf' theories, leading to the selection of inappropriate theories which distract attention from the mechanisms through which a problem is actually sustained. Second, we discuss a tendency toward over-reliance on individual-level theorising. Finally, we discuss the relatively slow progress of population health intervention research in attending to issues of context, and the ecological fit of interventions with the systems whose functioning they attempt to change. We argue that while researchers should consider a broad range of potential theoretical perspectives on a given population health problem, citing a popular off-the-shelf theory as having informed an intervention and its evaluation does not inherently make for better science. Before identifying or developing a theory of change, researchers should develop a clear understanding of how the problem under consideration is created and sustained in context. A broader conceptualisation of theory that reaches across disciplines is vital if theory is to enhance, rather than constrain, the contribution of intervention research. Finally, intervention researchers need to move away from viewing interventions as discrete packages of components which can be described in isolation from
Hydrogen atom addition to the surface of graphene nanoflakes: A density functional theory study
International Nuclear Information System (INIS)
Tachikawa, Hiroto
2017-01-01
Highlights: • The reaction pathway of the hydrogen addition to graphene surface was determined by the DFT method. • Binding energies of atomic hydrogen to graphene surface were determined. • Absorption spectrum of hydrogenated graphene was theoretically predicted. • Hyperfine coupling constant of hydrogenated graphene was theoretically predicted. - Abstract: Polycyclic aromatic hydrocarbons (PAHs) provide a 2-dimensional (2D) reaction surface in 3-dimensional (3D) interstellar space and have been utilized as a model of graphene surfaces. In the present study, the reaction of PAHs with atomic hydrogen was investigated by means of density functional theory (DFT) to systematically elucidate the binding nature of atomic hydrogen to graphene nanoflakes. PAHs with n = 4–37 were chosen, where n indicates the number of benzene rings. Activation energies of hydrogen addition to the graphene surface were calculated to be 5.2–7.0 kcal/mol at the CAM-B3LYP/6-311G(d,p) level, which is almost constant for all PAHs. The binding energies of hydrogen atom were slightly dependent on the size (n): 14.8–28.5 kcal/mol. The absorption spectra showed that a long tail is generated at the low-energy region after hydrogen addition to the graphene surface. The electronic states of hydrogenated graphenes were discussed on the basis of theoretical results.
Hydrogen atom addition to the surface of graphene nanoflakes: A density functional theory study
Energy Technology Data Exchange (ETDEWEB)
Tachikawa, Hiroto, E-mail: hiroto@eng.hokudai.ac.jp
2017-02-28
Highlights: • The reaction pathway of the hydrogen addition to graphene surface was determined by the DFT method. • Binding energies of atomic hydrogen to graphene surface were determined. • Absorption spectrum of hydrogenated graphene was theoretically predicted. • Hyperfine coupling constant of hydrogenated graphene was theoretically predicted. - Abstract: Polycyclic aromatic hydrocarbons (PAHs) provide a 2-dimensional (2D) reaction surface in 3-dimensional (3D) interstellar space and have been utilized as a model of graphene surfaces. In the present study, the reaction of PAHs with atomic hydrogen was investigated by means of density functional theory (DFT) to systematically elucidate the binding nature of atomic hydrogen to graphene nanoflakes. PAHs with n = 4–37 were chosen, where n indicates the number of benzene rings. Activation energies of hydrogen addition to the graphene surface were calculated to be 5.2–7.0 kcal/mol at the CAM-B3LYP/6-311G(d,p) level, which is almost constant for all PAHs. The binding energies of hydrogen atom were slightly dependent on the size (n): 14.8–28.5 kcal/mol. The absorption spectra showed that a long tail is generated at the low-energy region after hydrogen addition to the graphene surface. The electronic states of hydrogenated graphenes were discussed on the basis of theoretical results.
Near Surface Stoichiometry in UO2: A Density Functional Theory Study
Directory of Open Access Journals (Sweden)
Jianguo Yu
2015-01-01
Full Text Available The mechanisms of oxygen stoichiometry variation in UO2 at different temperature and oxygen partial pressure are important for understanding the dynamics of microstructure in these crystals. However, very limited experimental studies have been performed to understand the atomic structure of UO2 near surface and defect effects of near surface on stoichiometry in which the system can exchange atoms with the external reservoir. In this study, the near (110 surface relaxation and stoichiometry in UO2 have been studied with density functional theory (DFT calculations. On the basis of the point-defect model (PDM, a general expression for the near surface stoichiometric variation is derived by using DFT total-energy calculations and atomistic thermodynamics, in an attempt to pin down the mechanisms of oxygen exchange between the gas environment and defected UO2. By using the derived expression, it is observed that, under poor oxygen conditions, the stoichiometry of near surface is switched from hyperstoichiometric at 300 K with a depth around 3 nm to near-stoichiometric at 1000 K and hypostoichiometric at 2000 K. Furthermore, at very poor oxygen concentrations and high temperatures, our results also suggest that the bulk of the UO2 prefers to be hypostoichiometric, although the surface is near-stoichiometric.
Density functional theory formulation for fluid adsorption on correlated random surfaces
Aslyamov, Timur; Khlyupin, Aleksey
2017-10-01
We provide novel random surface density functional theory (RSDFT) formulation in the case of geometric heterogeneous surfaces of solid media which is essential for the description of thermodynamic properties of confined fluids. The major difference of our theoretical approach from the existing ones is a stochastic model of solid surfaces which takes into account the correlation properties of geometry. The main building blocks are effective fluid-solid potentials developed in the work of Khlyupin and Aslyamov [J. Stat. Phys. 167, 1519 (2017)] and geometry-based modification of the Helmholtz free energy for Lennard-Jones fluids. The efficiency of RSDFT is demonstrated in the calculation of argon and nitrogen low temperature adsorption on real heterogeneous surfaces (BP280 carbon black). These results are in good agreement with experimental data published in the literature. Also several models of corrugated materials are developed in the framework of RSDFT. Numerical analysis demonstrates a strong influence of surface roughness characteristics on adsorption isotherms. Thus the developed formalism provides a connection between a rigorous description of the stochastic surface and confined fluid thermodynamics.
Catalytic water dissociation by greigite Fe3S4 surfaces: density functional theory study
Roldan, A.; de Leeuw, N. H.
2016-01-01
The iron sulfide mineral greigite, Fe3S4, has shown promising capability as a hydrogenating catalyst, in particular in the reduction of carbon dioxide to produce small organic molecules under mild conditions. We employed density functional theory calculations to investigate the {001},{011} and {111} surfaces of this iron thiospinel material, as well as the production of hydrogen ad-atoms from the dissociation of water molecules on the surfaces. We systematically analysed the adsorption geometries and the electronic structure of both bare and hydroxylated surfaces. The sulfide surfaces presented a higher flexibility than the isomorphic oxide magnetite, Fe3O4, allowing perpendicular movement of the cations above or below the top atomic sulfur layer. We considered both molecular and dissociative water adsorption processes, and have shown that molecular adsorption is the predominant state on these surfaces from both a thermodynamic and kinetic point of view. We considered a second molecule of water which stabilizes the system mainly by H-bonds, although the dissociation process remains thermodynamically unfavourable. We noted, however, synergistic adsorption effects on the Fe3S4{001} owing to the presence of hydroxyl groups. We concluded that, in contrast to Fe3O4, molecular adsorption of water is clearly preferred on greigite surfaces. PMID:27274698
Origin of synergistic effect over Ni-based bimetallic surfaces: A density functional theory study
Fan, Chen; Zhu, Yi-An; Xu, Yue; Zhou, Yan; Zhou, Xing-Gui; Chen, De
2012-07-01
Density functional theory calculations have been conducted to explore the physical origin of the synergistic effect over Ni-based surface alloys using methane dissociation as a probe reaction. Some late transition metal atoms (M = Cu, Ru, Rh, Pd, Ag, Pt, and Au) are substituted for surface Ni atoms to examine the variation in electronic structure and adsorption property of Ni(111). Two types of threefold hollow sites, namely, the Ni2M and Ni3 sites, are taken into account. The calculated results indicate that the variation in the CHx adsorption energy at the Ni2M and Ni3 sites is dominated by the ensemble and ligand effect, respectively, and the other factors such as surface and adsorbate distortion and electrostatic interaction affect the catalytic properties of the bimetallic surfaces to a smaller extent. Both the Brønsted-Evans-Polanyi relationship and the scaling correlation hold true on the Ni-based bimetallic surfaces. With the combination of these two linear energy relations, the corrected binding energy of atomic C is found to be a good descriptor for representing the catalytic activity of the alloyed surfaces. Considering the compromise between the catalytic activity and catalyst stability, we suggest that the Rh/Ni catalyst is a good candidate for methane dissociation.
Research on the Structural Characteristics of Transmission Grid Based on Complex Network Theory
Directory of Open Access Journals (Sweden)
Jinli Zhao
2014-01-01
Full Text Available Reasonable and strong structure is an important foundation for the smart transmission grid. For vigorously promoting construction of the smart grid, it is of great significance to have a thorough understanding of the complex structural characteristics of the power grid. The structural characteristics of several actual large-scale power grids of China are studied in this paper based on the complex network theory. Firstly, the topology-based network model of power grid is recalled for analyzing the statistical characteristic parameters. The result demonstrated that although some statistical characteristic parameters could reflect the topological characteristics of power grid from different ways, they have certain limitation in representing the electrical characteristics of power grid. Subsequently, the network model based on the electrical distance is established considering the limitation of topology-based model, which reflects that current and voltage distribution in the power grid are subject to Ohm's Law and Kirchhoff's Law. Comparing with the topology-based model, the electrical distance-based model performs better in reflecting the natural electrical characteristic structure of power grid, especially intuitive and effective in analyzing clustering characteristics and agglomeration characteristics of power grid. These two models could complement each other.
Theory Meets Experiment: Metal Ion Effects in HCV Genomic RNA Kissing Complex Formation.
Sun, Li-Zhen; Heng, Xiao; Chen, Shi-Jie
2017-01-01
The long-range base pairing between the 5BSL3. 2 and 3'X domains in hepatitis C virus (HCV) genomic RNA is essential for viral replication. Experimental evidence points to the critical role of metal ions, especially Mg 2+ ions, in the formation of the 5BSL3.2:3'X kissing complex. Furthermore, NMR studies suggested an important ion-dependent conformational switch in the kissing process. However, for a long time, mechanistic understanding of the ion effects for the process has been unclear. Recently, computational modeling based on the Vfold RNA folding model and the partial charge-based tightly bound ion (PCTBI) model, in combination with the NMR data, revealed novel physical insights into the role of metal ions in the 5BSL3.2-3'X system. The use of the PCTBI model, which accounts for the ion correlation and fluctuation, gives reliable predictions for the ion-dependent electrostatic free energy landscape and ion-induced population shift of the 5BSL3.2:3'X kissing complex. Furthermore, the predicted ion binding sites offer insights about how ion-RNA interactions shift the conformational equilibrium. The integrated theory-experiment study shows that Mg 2+ ions may be essential for HCV viral replication. Moreover, the observed Mg 2+ -dependent conformational equilibrium may be an adaptive property of the HCV genomic RNA such that the equilibrium is optimized to the intracellular Mg 2+ concentration in liver cells for efficient viral replication.
Energy Technology Data Exchange (ETDEWEB)
Romanchuk, Anna Y.; Kalmykov, Stephan N. [Lomonosov Moscow State Univ., Moscow (Russian Federation). Dept. of Chemistry
2014-07-01
The sorption of actinides in different valence states - Am(III), Th(IV), Np(V) and U(VI) onto hematite have been revisited with the special emphasis on the equilibrium constants of formation of surface species. The experimental sorption data have been treated using surface complexation modeling from which the set of new values of equilibrium constants were obtained. Formation of inner sphere monodentate surface species adequately describes the pH-sorption edges for actinide ions indicative the ionic electrostatic nature of bonding with small or no covalency contribution. The linear free energy relationship representing the correlation between the hydrolysis constants and surface complexation constants has been developed for various cations including K(I), Li(I), Na(I), Ag(I), Tl(I), Sr(II), Cu(II), Co(II), La(III), Eu(III), Ga(III), Am(III), Th(IV), Np(V), U(VI). (orig.)
Cooper, Rachel J; Camp, Philip J; Gordon, Ross J; Henderson, David K; Henry, Dorothy C R; McNab, Hamish; De Silva, Sonali S; Tackley, Daniel; Tasker, Peter A; Wight, Paul
2006-06-21
Simple azo-dyes carrying phosphonic acid and arsonic acid substituents such as 4-(4-hydroxyphenyl azo)phenylphosphonic acid (5) and 4-(4-hydroxyphenylazo)phenylarsonic acid (6) bind more strongly to high surface area oxides such as aluminium trihydroxide and goethite than their carboxylic and sulfonic acid analogues and the phosphonate-functionalized dyes have been shown to have greater humidity fastness when printed onto commercial alumina-coated papers. Adsorption isotherm measurements provide evidence for the formation of ternary dye/cyclodextrin/surface complexes. Dyes which form such ternary complexes show higher light fastness when printed onto alumina coated papers in an ink formulation containing alpha-cyclodextrin.
Muscle fatigue and contraction intensity modulates the complexity of surface electromyography.
Cashaback, Joshua G A; Cluff, Tyler; Potvin, Jim R
2013-02-01
Nonlinear dynamical techniques offer a powerful approach for the investigation of physiological time series. Multiscale entropy analyses have shown that pathological and aging systems are less complex than healthy systems and this finding has been attributed to degraded physiological control processes. A similar phenomenon may arise during fatiguing muscle contractions where surface electromyography signals undergo temporal and spectral changes that arise from the impaired regulation of muscle force production. Here we examine the affect of fatigue and contraction intensity on the short and long-term complexity of biceps brachii surface electromyography. To investigate, we used an isometric muscle fatigue protocol (parsed into three windows) and three contraction intensities (% of maximal elbow joint moment: 40%, 70% and 100%). We found that fatigue reduced the short-term complexity of biceps brachii activity during the last third of the fatiguing contraction. We also found that the complexity of surface electromyography is dependent on contraction intensity. Our results show that multiscale entropy is sensitive to muscle fatigue and contraction intensity and we argue it is imperative that both factors be considered when evaluating the complexity of surface electromyography signals. Our data contribute to a converging body of evidence showing that multiscale entropy can quantify subtle information content in physiological time series. Copyright © 2012 Elsevier Ltd. All rights reserved.
Toroidal surface complexes of bacteriophage φ12 are responsible for host-cell attachment
International Nuclear Information System (INIS)
Leo-Macias, Alejandra; Katz, Garrett; Wei Hui; Alimova, Alexandra; Katz, A.; Rice, William J.; Diaz-Avalos, Ruben; Hu Guobin; Stokes, David L.; Gottlieb, Paul
2011-01-01
Cryo-electron tomography and subtomogram averaging are utilized to determine that the bacteriophage φ12, a member of the Cystoviridae family, contains surface complexes that are toroidal in shape, are composed of six globular domains with six-fold symmetry, and have a discrete density connecting them to the virus membrane-envelope surface. The lack of this kind of spike in a reassortant of φ12 demonstrates that the gene for the hexameric spike is located in φ12's medium length genome segment, likely to the P3 open reading frames which are the proteins involved in viral-host cell attachment. Based on this and on protein mass estimates derived from the obtained averaged structure, it is suggested that each of the globular domains is most likely composed of a total of four copies of P3a and/or P3c proteins. Our findings may have implications in the study of the evolution of the cystovirus species in regard to their host specificity. - Research Highlights: → Subtomogram averaging reveals enhanced detail of a φ12 cystovirus surface protein complex. → The surface protein complex has a toroidal shape and six-fold symmetry. → It is encoded by the medium-size genome segment. → The proteins of the surface complex most likely are one copy of P3a and three copies of P3c.
Jorm, Christine; Nisbet, Gillian; Roberts, Chris; Gordon, Christopher; Gentilcore, Stacey; Chen, Timothy F
2016-08-08
More and better interprofessional practice is predicated to be necessary to deliver good care to the patients of the future. However, universities struggle to create authentic learning activities that enable students to experience the dynamic interprofessional interactions common in healthcare and that can accommodate large interprofessional student cohorts. We investigated a large-scale mandatory interprofessional learning (IPL) activity for health professional students designed to promote social learning. A mixed methods research approach determined feasibility, acceptability and the extent to which student IPL outcomes were met. We developed an IPL activity founded in complexity theory to prepare students for future practice by engaging them in a self-directed (self-organised) learning activity with a diverse team, whose assessable products would be emergent creations. Complicated but authentic clinical cases (n = 12) were developed to challenge student teams (n = 5 or 6). Assessment consisted of a written management plan (academically marked) and a five-minute video (peer marked) designed to assess creative collaboration as well as provide evidence of integrated collective knowledge; the cohesive patient-centred management plan. All students (including the disciplines of diagnostic radiology, exercise physiology, medicine, nursing, occupational therapy, pharmacy, physiotherapy and speech pathology), completed all tasks successfully. Of the 26 % of students who completed the evaluation survey, 70 % agreed or strongly agreed that the IPL activity was worthwhile, and 87 % agreed or strongly agreed that their case study was relevant. Thematic analysis found overarching themes of engagement and collaboration-in-action suggesting that the IPL activity enabled students to achieve the intended learning objectives. Students recognised the contribution of others and described negotiation, collaboration and creation of new collective knowledge after working
Modeling and dynamical topology properties of VANET based on complex networks theory
Directory of Open Access Journals (Sweden)
Hong Zhang
2015-01-01
Full Text Available Vehicular Ad hoc Network (VANET is a special subset of multi-hop Mobile Ad hoc Networks in which vehicles can not only communicate with each other but also with the fixed equipments along the roads through wireless interfaces. Recently, it has been discovered that essential systems in real world share similar properties. When they are regarded as networks, among which the dynamic topology structure of VANET system is an important issue. Many real world networks are actually growing with preferential attachment like Internet, transportation system and telephone network. Those phenomena have brought great possibility in finding a strategy to calibrate and control the topology parameters which can help find VANET topology change regulation to relieve traffic jam, prevent traffic accident and improve traffic safety. VANET is a typical complex network which has its basic characteristics. In this paper, we focus on the macroscopic Vehicle-to-Infrastructure (V2I and Vehicle-to-Vehicle (V2V inter-vehicle communication network with complex network theory. In particular, this paper is the first one to propose a method analyzing the topological structure and performance of VANET and present the communications in VANET from a new perspective. Accordingly, we propose degree distribution, clustering coefficient and the short path length of complex network to implement our strategy by numerical example and simulation. All the results demonstrate that VANET shows small world network features and is characterized by a truncated scale-free degree distribution with power-law degree distribution. The average path length of the network is simulated numerically, which indicates that the network shows small-world property and is rarely affected by the randomness. What’s more, we carry out extensive simulations of information propagation and mathematically prove the power law property when γ > 2. The results of this study provide useful information for VANET
Modeling and dynamical topology properties of VANET based on complex networks theory
Zhang, Hong; Li, Jie
2015-01-01
Vehicular Ad hoc Network (VANET) is a special subset of multi-hop Mobile Ad hoc Networks in which vehicles can not only communicate with each other but also with the fixed equipments along the roads through wireless interfaces. Recently, it has been discovered that essential systems in real world share similar properties. When they are regarded as networks, among which the dynamic topology structure of VANET system is an important issue. Many real world networks are actually growing with preferential attachment like Internet, transportation system and telephone network. Those phenomena have brought great possibility in finding a strategy to calibrate and control the topology parameters which can help find VANET topology change regulation to relieve traffic jam, prevent traffic accident and improve traffic safety. VANET is a typical complex network which has its basic characteristics. In this paper, we focus on the macroscopic Vehicle-to-Infrastructure (V2I) and Vehicle-to-Vehicle (V2V) inter-vehicle communication network with complex network theory. In particular, this paper is the first one to propose a method analyzing the topological structure and performance of VANET and present the communications in VANET from a new perspective. Accordingly, we propose degree distribution, clustering coefficient and the short path length of complex network to implement our strategy by numerical example and simulation. All the results demonstrate that VANET shows small world network features and is characterized by a truncated scale-free degree distribution with power-law degree distribution. The average path length of the network is simulated numerically, which indicates that the network shows small-world property and is rarely affected by the randomness. What's more, we carry out extensive simulations of information propagation and mathematically prove the power law property when γ > 2. The results of this study provide useful information for VANET optimization from a
Modeling and dynamical topology properties of VANET based on complex networks theory
Energy Technology Data Exchange (ETDEWEB)
Zhang, Hong; Li, Jie, E-mail: prof.li@foxmail.com [School of Civil Engineering and Mechanics, Huazhong University of Science and Technology, Wuhan, 430074 (China)
2015-01-15
Vehicular Ad hoc Network (VANET) is a special subset of multi-hop Mobile Ad hoc Networks in which vehicles can not only communicate with each other but also with the fixed equipments along the roads through wireless interfaces. Recently, it has been discovered that essential systems in real world share similar properties. When they are regarded as networks, among which the dynamic topology structure of VANET system is an important issue. Many real world networks are actually growing with preferential attachment like Internet, transportation system and telephone network. Those phenomena have brought great possibility in finding a strategy to calibrate and control the topology parameters which can help find VANET topology change regulation to relieve traffic jam, prevent traffic accident and improve traffic safety. VANET is a typical complex network which has its basic characteristics. In this paper, we focus on the macroscopic Vehicle-to-Infrastructure (V2I) and Vehicle-to-Vehicle (V2V) inter-vehicle communication network with complex network theory. In particular, this paper is the first one to propose a method analyzing the topological structure and performance of VANET and present the communications in VANET from a new perspective. Accordingly, we propose degree distribution, clustering coefficient and the short path length of complex network to implement our strategy by numerical example and simulation. All the results demonstrate that VANET shows small world network features and is characterized by a truncated scale-free degree distribution with power-law degree distribution. The average path length of the network is simulated numerically, which indicates that the network shows small-world property and is rarely affected by the randomness. What’s more, we carry out extensive simulations of information propagation and mathematically prove the power law property when γ > 2. The results of this study provide useful information for VANET optimization from a
Experimental test of proximity effect theories by surface impedance measurements on the Pb-Sn system
International Nuclear Information System (INIS)
Hook, J.R.; Battilana, J.A.
1976-01-01
The proximity effect in the Pb-Sn system in zero magnetic field has been studied by measuring the surface impedance at 3 GHz of a thin film of tin evaporated on to a bulk lead substrate. The results are compared with the predictions of theories of the proximity effect. It is found that good agreement can be obtained by using a theory due to Hook and Waldram of the spatial variation of the superconducting order parameter Δ inside each metal together with suitable boundary conditions on Δ at the interface between the metals. The required boundary conditions are a generalization to the case of non-zero electron reflection at the interface of the boundary conditions given by Zaitsev for the Ginsburg-Landau equation. (author)
Coupled wave equations theory of surface-enhanced femtosecond stimulated Raman scattering.
McAnally, Michael O; McMahon, Jeffrey M; Van Duyne, Richard P; Schatz, George C
2016-09-07
We present a coupled wave semiclassical theory to describe plasmonic enhancement effects in surface-enhanced femtosecond stimulated Raman scattering (SE-FSRS). A key result is that the plasmon enhanced fields which drive the vibrational equation of motion for each normal mode results in dispersive lineshapes in the SE-FSRS spectrum. This result, which reproduces experimental lineshapes, demonstrates that plasmon-enhanced stimulated Raman methods provide unique sensitivity to a plasmonic response. Our derived SE-FSRS theory shows a plasmonic enhancement of |gpu|(2)ImχR(ω)gst (2)/ImχR(ω), where |gpu|(2) is the absolute square of the plasmonic enhancement from the Raman pump, χR(ω) is the Raman susceptibility, and gst is the plasmonic enhancement of the Stokes field in SE-FSRS. We conclude with a discussion on potential future experimental and theoretical directions for the field of plasmonically enhanced coherent Raman scattering.
National Research Council Canada - National Science Library
Johnson, Joseph E; Gudkov, Vladimir
2005-01-01
... as continuous group theory and Markov processes. Based upon this research he has proposed that entropy metrics, and the associated cluster analysis of the network so measured by these metrics, can be useful indicators of aberrant processes and behavior. Other team members have obtained important connections using higher order Renyi entropy metrics, and complexity theory to both monitor real networks and to study networks by simulation.
Nanodrop on a smooth solid surface with hidden roughness. Density functional theory considerations
Berim, Gersh O.; Ruckenstein, Eli
2015-04-01
A nanodrop of a test fluid placed on a smooth surface of a solid material of nonuniform density which covers a rough solid surface (hidden roughness) is examined, on the basis of the density functional theory (DFT), in the presence of an external perturbative force parallel to the surface. The contact angles which the drop profile makes with the surface at the leading edges of the drop are determined as functions of drop size and perturbative external force. A critical sticking force, defined as the largest value of the perturbative force for which the drop remains at equilibrium, is determined and its dependence on the size of the drop is explained on the basis of the shape of the interaction potential generated by the solid in vicinity of the leading edges of the drop. For even larger values of the perturbative force no drop-like solution of the Euler-Lagrange equation of the DFT was found. The upper bound of the inclination angle of a surface containing a macroscopic drop is estimated on the basis of results obtained for nanodrops and some experimental results are interpreted. The main conclusion is that the hidden roughness has a similar effect on the drop features as the traditionally considered physical and chemical roughnesses.
Colour interceptions, thermal stability and surface morphology of polyester metal complexes
International Nuclear Information System (INIS)
Zohdy, M.H.
2005-01-01
Chelating copolymers via grafting of acrylic acid (AAc) and acrylamide (AAm/AAc) comonomer mixture onto polyester micro fiber fabrics (PETMF) using gamma-radiation technique were prepared. The prepared graft chains (PETMF-g-AAc) and (PETMF-g-PAAc/PAAm) acted as chelating sites for some selected transition metal ions. The prepared graft copolymers and their metal complexes were characterized using thermogravimetric analysis (TGA), colour parameters and surface morphology measurements. The colour interception and strength measurements showed that the metal complexation is homogeneously distributed. The results showed that the thermal stability of PETMF was improved after graft copolymerization and metal complexes. Moreover, the degree of grafting enhanced the thermal stability values of the grafted and complexed copolymers up to 25% of magnitude, on the other hand the activation energy of the grafted-copolymer with acrylic acid increased up to 80%. The SEM observation gives further supports to the homogenous distribution of grafting and metal complexation
Directory of Open Access Journals (Sweden)
Vincenzo Penteriani
2010-01-01
Full Text Available The outstanding levels of knowledge attained today in the research on animal communication, and the new available technologies to study visual, vocal and chemical signalling, allow an ever increasing use of information theory as a sophisticated tool to improve our knowledge of the complexity of animal communication. Some considerations on the way information theory and intraspecific communication can be linked are presented here. Specifically, information theory may help us to explore interindividual variations in different environmental constraints and social scenarios, as well as the communicative features of social vs. solitary species.
International Nuclear Information System (INIS)
Khawaja, Z; Mazeran, P-E; Bigerelle, M; Guillemot, G; Mansori, M El
2011-01-01
This article presents a multi-scale theory based on wavelet decomposition to characterize the evolution of roughness in relation with a finishing process or an observed surface property. To verify this approach in production conditions, analyses were developed for the finishing process of the hardened steel by abrasive belts. These conditions are described by seven parameters considered in the Tagushi experimental design. The main objective of this work is to identify the most relevant roughness parameter and characteristic length allowing to assess the influence of finishing process, and to test the relevance of the measurement scale. Results show that wavelet approach allows finding this scale.
Theory of alkali-metal-induced reconstructions of fcc(100) surfaces
DEFF Research Database (Denmark)
Christensen, Ole Bøssing; Jacobsen, Karsten Wedel
1992-01-01
Calculations of missing-row reconstruction energies of the fcc(100) surfaces of the metals Al, Ni, Pd, Pt, Cu, Ag, and Au have been performed with the effective-medium theory with and without the presence of a potassium overlayer. It is shown that the tendency to reconstruct in the presence...... of adsorbed K is largest for Ag. This is in accordance with recent experiments indicating a potassium-induced missing-row reconstruction for Ag, but not for other metals. The tendency is shown to be related to the relatively low bulk modulus of silver. Differences from the well-known alkali...
Theory and Monte-Carlo simulation of adsorbates on corrugated surfaces
DEFF Research Database (Denmark)
Vives, E.; Lindgård, P.-A.
1993-01-01
-phase between the commensurate and incommensurate phase stabilized by defects. Special attention has been given to the study of the epitaxial rotation angles of the different phases. Available experimental data is in agreement with the simulations and with a general theory for the epitaxial rotation which takes......Phase transitions in systems of adsorbed molecules on corrugated surfaces are studied by means of Monte Carlo simulation. Particularly, we have studied the phase diagram of D2 on graphite as a function of coverage and temperature. We have demonstrated the existence of an intermediate gamma...
String theory flux vacua on twisted tori and generalized complex geometry
International Nuclear Information System (INIS)
Andriot, David
2010-01-01
This thesis is devoted to the study of flux vacua of string theory, with the ten-dimensional space-time split into a four-dimensional maximally symmetric space-time, and a six-dimensional internal manifold M, taken to be a solv-manifold (twisted torus). Such vacua are of particular interest when trying to relate string theory to supersymmetric (SUSY) extensions of the standard model of particles, or to cosmological models. For SUSY solutions of type II supergravities, allowing for fluxes on M helps to solve the moduli problem. Then, a broader class of manifolds than just the Calabi-Yau can be considered for M, and a general characterization is given in terms of Generalized Complex Geometry: M has to be a Generalized Calabi-Yau (GCY). A subclass of solv-manifolds have been proven to be GCY, so we look for solutions with such M. To do so, we use an algorithmic resolution method. Then we focus on specific new solutions: those admitting an intermediate SU(2) structure. A transformation named the twist is then discussed. It relates solutions on torus to solutions on solv-manifolds. Working out constraints on the twist to generate solutions, we can relate known solutions, and find a new one. We also use the twist to relate flux vacua of heterotic string. Finally we consider ten-dimensional de Sitter solutions. Looking for such solutions is difficult, because of several problems among which the breaking of SUSY. We propose an Ansatz for SUSY breaking sources which helps to overcome these difficulties. We give an explicit solution on a solv-manifold, and discuss partially its four-dimensional stability. (author)
Theory of the reaction dynamics of small molecules on metal surfaces
Energy Technology Data Exchange (ETDEWEB)
Jackson, Bret [Univ. of Massachusetts, Amherst, MA (United States)
2016-09-09
The objective of this project has been to develop realistic theoretical models for gas-surface interactions, with a focus on processes important in heterogeneous catalysis. The dissociative chemisorption of a molecule on a metal is a key step in many catalyzed reactions, and is often the rate-limiting step. We have explored the dissociative chemisorption of H_{2}, H_{2}O and CH_{4} on a variety of metal surfaces. Most recently, our extensive studies of methane dissociation on Ni and Pt surfaces have fully elucidated its dependence on translational energy, vibrational state and surface temperature, providing the first accurate comparisons with experimental data. We have explored Eley-Rideal and hot atom reactions of H atoms with H- and C-covered metal surfaces. H atom interactions with graphite have also been explored, including both sticking and Eley-Rideal recombination processes. Again, our methods made it possible to explain several experiments studying these reactions. The sticking of atoms on metal surfaces has also been studied. To help elucidate the experiments that study these processes, we examine how the reaction dynamics depend upon the nature of the molecule-metal interaction, as well as experimental variables such as substrate temperature, beam energy, angle of impact, and the internal states of the molecules. Electronic structure methods based on Density Functional Theory are used to compute each molecule-metal potential energy surface. Both time-dependent quantum scattering techniques and quasi-classical methods are used to examine the reaction or scattering dynamics. Much of our effort has been directed towards developing improved quantum methods that can accurately describe reactions, as well as include the effects of substrate temperature (lattice vibration).
International Nuclear Information System (INIS)
Bonten, Luc T.C.; Groenenberg, Jan E.; Meesenburg, Henning; Vries, Wim de
2011-01-01
Various dynamic soil chemistry models have been developed to gain insight into impacts of atmospheric deposition of sulphur, nitrogen and other elements on soil and soil solution chemistry. Sorption parameters for anions and cations are generally calibrated for each site, which hampers extrapolation in space and time. On the other hand, recently developed surface complexation models (SCMs) have been successful in predicting ion sorption for static systems using generic parameter sets. This study reports the inclusion of an assemblage of these SCMs in the dynamic soil chemistry model SMARTml and applies this model to a spruce forest site in Solling Germany. Parameters for SCMs were taken from generic datasets and not calibrated. Nevertheless, modelling results for major elements matched observations well. Further, trace metals were included in the model, also using the existing framework of SCMs. The model predicted sorption for most trace elements well. - Highlights: → Surface complexation models can be well applied in field studies. → Soil chemistry under a forest site is adequately modelled using generic parameters. → The model is easily extended with extra elements within the existing framework. → Surface complexation models can show the linkages between major soil chemistry and trace element behaviour. - Surface complexation models with generic parameters make calibration of sorption superfluous in dynamic modelling of deposition impacts on soil chemistry under nature areas.
Jiménez, P.A.; González-Rouco, J.F.; García-Bustamante, E.; Navarro, J.; Montávez, J.P.; Vilà-Guerau de Arellano, J.; Dudhia, J.; Muñoz-Roldan, A.
2010-01-01
This study analyzes the daily-mean surface wind variability over an area characterized by complex topography through comparing observations and a 2-km-spatial-resolution simulation performed with the Weather Research and Forecasting (WRF) model for the period 1992–2005. The evaluation focuses on the
Two new organotin(IV) phosphoryl complexes: crystal structure and Hirshfeld surface analysis.
Czech Academy of Sciences Publication Activity Database
Pourayoubi, M.; Saneei, A.; Dušek, Michal; Rostami, S.A.; Crochet, A.; Kučeráková, Monika
2015-01-01
Roč. 12, č. 12 (2015), s. 2093-2103 ISSN 1735-2428 R&D Projects: GA ČR(CZ) GA14-03276S Institutional support: RVO:68378271 Keywords : Hirshfeld surfaces * tin * organotin(IV)-phosphoryl complex * crystal structure Subject RIV: BM - Solid Matter Physics ; Magnetism
Ab initio potential-energy surface and rovibrational states of the HCN-HCl complex
Avoird, A. van der; Pedersen, T.B.; Dhont, G.S.F.; Fernandez, B.; Koch, H.
2006-01-01
A four-dimensional intermolecular potential-energy surface has been calculated for the HCN-HCl complex, with the use of the coupled cluster method with single and double excitations and noniterative inclusion of triples. Data for more than 13 000 geometries were represented by an angular expansion
International Nuclear Information System (INIS)
Stout, R B
2001-01-01
A theoretical expression is developed for the dissolution rate response for multi-component radioactive materials that have surface adsorption kinetics and radiolysis kinetics when wetted by a multi-component aqueous solution. An application for this type of dissolution response is the performance evaluation of multi-component spent nuclear fuels (SNFs) for long term interim storage and for geological disposition. Typically, SNF compositions depend on initial composition, uranium oxide and metal alloys being most common, and on reactor burnup which results in a wide range of fission product and actinide concentrations that decay by alpha, beta, and gamma radiation. These compositional/burnup ranges of SNFs, whether placed in interim storage or emplaced in a geologic repository, will potentially be wetted by multi-component aqueous solutions, and these solutions may be further altered by radiolytic aqueous species due to three radiation fields. The solid states of the SNFs are not thermodynamically stable when wetted and will dissolve, with or without radiolysis. The following development of a dissolution theory is based on a non-equilibrium thermodynamic analysis of energy reactions and energy transport across a solid-liquid phase change discontinuity that propagates at a quasi-steady, dissolution velocity. The integral form of the energy balance equation is used for this spatial surface discontinuity analysis. The integral formulation contains internal energy functional of classical thermodynamics for both the SNFs' solid state and surface adsorption species, and the adjacent liquid state, which includes radiolytic chemical species. The steady-state concentrations of radiolytic chemical species are expressed by an approximate analysis of the decay radiation transport equation. For purposes of illustration a modified Temkin adsorption isotherm was assumed for the surface adsorption kinetics on an arbitrary, finite area of the solid-liquid dissolution interface. For
Quantum Hall states and conformal field theory on a singular surface
Can, T.; Wiegmann, P.
2017-12-01
In Can et al (2016 Phys. Rev. Lett. 117), quantum Hall states on singular surfaces were shown to possess an emergent conformal symmetry. In this paper, we develop this idea further and flesh out details on the emergent conformal symmetry in holomorphic adiabatic states, which we define in the paper. We highlight the connection between the universal features of geometric transport of quantum Hall states and holomorphic dimension of primary fields in conformal field theory. In parallel we compute the universal finite-size corrections to the free energy of a critical system on a hyperbolic sphere with conical and cusp singularities, thus extending the result of Cardy and Peschel for critical systems on a flat cone (Cardy and Peschel 1988 Nucl. Phys. B 300 377–92), and the known results for critical systems on polyhedra and flat branched Riemann surfaces.
Surface complexation of neptunium (V) onto whole cells and cell componets of Shewanella alga
Energy Technology Data Exchange (ETDEWEB)
Reed, Donald Timothy [Los Alamos National Laboratory; Deo, Randhir P [ASU; Rittmann, Bruce E [ASU; Songkasiri, Warinthorn [UNAFFILIATED
2008-01-01
We systematically quantified surface complexation of neptunium(V) onto whole cells of Shewanella alga strain BrY and onto cell wall and extracellular polymeric substances (EPS) of S. alga. We first performed acid and base titrations and used the mathematical model FITEQL with constant-capacitance surface-complexation to determine the concentrations and deprotonation constants of specific surface functional groups. Deprotonation constants most likely corresponded to a carboxyl site associated with amino acids (pK{sub a} {approx} 2.4), a carboxyl group not associated with amino acids (pK{sub a} {approx} 5), a phosphoryl site (pK{sub a} {approx} 7.2), and an amine site (pK{sub a} > 10). We then carried out batch sorption experiments with Np(V) and each of the S. alga components at different pHs. Results show that solution pH influenced the speciation of Np(V) and each of the surface functional groups. We used the speciation sub-model of the biogeochemical model CCBATCH to compute the stability constants for Np(V) complexation to each surface functional group. The stability constants were similar for each functional group on S. alga bacterial whole cells, cell walls, and EPS, and they explain the complicated sorption patterns when they are combined with the aqueous-phase speciation of Np(V). For pH < 8, NpO{sub 2}{sup +} was the dominant form of Np(V), and its log K values for the low-pK{sub a} carboxyl, other carboxyl, and phosphoryl groups were 1.75, 1.75, and 2.5 to 3.1, respectively. For pH greater than 8, the key surface ligand was amine >XNH3+, which complexed with NpO{sub 2}(CO{sub 3}){sub 3}{sup 5-}. The log K for NpO{sub 2}(CO{sub 3}){sub 3}{sup 5-} complexed onto the amine groups was 3.1 to 3.6. All of the log K values are similar to those of Np(V) complexes with aqueous carboxyl and N-containing carboxyl ligands. These results point towards the important role of surface complexation in defining key actinide-microbiological interactions in the subsurface.
Kozlovskaya, E. N.; Doroshenko, I. Yu.; Pogorelov, V. E.; Vaskivskyi, Ye. V.; Pitsevich, G. A.
2018-01-01
Previously calculated multidimensional potential-energy surfaces of the MeOH monomer and dimer, water dimer, malonaldehyde, formic acid dimer, free pyridine-N-oxide/trichloroacetic acid complex, and protonated water dimer were analyzed. The corresponding harmonic potential-energy surfaces near the global minima were constructed for series of clusters and complexes with hydrogen bonds of different strengths based on the behavior of the calculated multidimensional potential-energy surfaces. This enabled the introduction of an obvious anharmonicity parameter for the calculated potential-energy surfaces. The anharmonicity parameter was analyzed as functions of the size of the analyzed area near the energy minimum, the number of points over which energies were compared, and the dimensionality of the solved vibrational problem. Anharmonicity parameters for potential-energy surfaces in complexes with strong, medium, and weak H-bonds were calculated under identical conditions. The obtained anharmonicity parameters were compared with the corresponding diagonal anharmonicity constants for stretching vibrations of the bridging protons and the lengths of the hydrogen bridges.
Infrared spectroscopy of the Ar-C2HD complex: Potential energy surfaces
International Nuclear Information System (INIS)
Bemish, R.J.; Miller, R.E.
1996-01-01
The argon-acetylene complex has been studied by a number of experimental and theoretical groups, with the aim in mind of determining an accurate potential energy surface for this system. Both microwave and infrared spectroscopy have provided detailed rotational and vibrational constants for this system. In addition, scattering experiments have been reported and ab initio calculation performed. Even with all of this, there are still some fundamental questions that remain unanswered with regards to the shape of the potential surface. The authors will review some of this work to outline the current situation. In the present study, the authors have obtained high resolution infrared spectra of the Ar-C 2 HD complex with the aim of providing additional molecular constants that could be used to help constrain the potential. Collocation calculations are reported, using a number of potential surfaces, for this and the normal isotopomer. This additional data helps to answer some of these open questions
Finch, Tracy L; Rapley, Tim; Girling, Melissa; Mair, Frances S; Murray, Elizabeth; Treweek, Shaun; McColl, Elaine; Steen, Ian Nicholas; May, Carl R
2013-01-01
Background Understanding implementation processes is key to ensuring that complex interventions in healthcare are taken up in practice and thus maximize intended benefits for service provision and (ultimately) care to patients. Normalization Process Theory (NPT) provides a framework for understanding how a new intervention becomes part of normal practice. This study aims to develop and validate simple generic tools derived from NPT, to be used to improve the implementation of complex healthca...
The complexity of managing COPD exacerbations: a grounded theory study of European general practice.
Risør, Mette Bech; Spigt, Mark; Iversen, R; Godycki-Cwirko, M; Francis, N; Altiner, A; Andreeva, E; Kung, K; Melbye, H
2013-12-05
To understand the concerns and challenges faced by general practitioners (GPs) and respiratory physicians about primary care management of acute exacerbations in patients with chronic obstructive pulmonary disease (COPD). 21 focus group discussions (FGDs) were performed in seven countries with a Grounded Theory approach. Each country performed three rounds of FGDs. Primary and secondary care in Norway, Germany, Wales, Poland, Russia, The Netherlands, China (Hong Kong). 142 GPs and respiratory physicians were chosen to include urban and rural GPs as well as hospital-based and out patient-clinic respiratory physicians. Management of acute COPD exacerbations is dealt with within a scope of concerns. These concerns range from 'dealing with comorbidity' through 'having difficult patients' to 'confronting a hopeless disease'. The first concern displays medical uncertainty regarding diagnosis, medication and hospitalisation. These clinical processes become blurred by comorbidity and the social context of the patient. The second concern shows how patients receive the label 'difficult' exactly because they need complex attention, but even more because they are time consuming, do not take responsibility and are non-compliant. The third concern relates to the emotional reactions by the physicians when confronted with 'a hopeless disease' due to the fact that most of the patients do not improve and the treatment slows down the process at best. GPs and respiratory physicians balance these concerns with medical knowledge and practical, situational knowledge, trying to encompass the complexity of a medical condition. Knowing the patient is essential when dealing with comorbidities as well as with difficult relations in the consultations on exacerbations. This study suggests that it is crucial to improve the collaboration between primary and secondary care, in terms of, for example, shared consultations and defined work tasks, which may enhance shared knowledge of patients
Theory Meets Experiment: Metal Ion Effects in HCV Genomic RNA Kissing Complex Formation
Directory of Open Access Journals (Sweden)
Li-Zhen Sun
2017-12-01
Full Text Available The long-range base pairing between the 5BSL3. 2 and 3′X domains in hepatitis C virus (HCV genomic RNA is essential for viral replication. Experimental evidence points to the critical role of metal ions, especially Mg2+ ions, in the formation of the 5BSL3.2:3′X kissing complex. Furthermore, NMR studies suggested an important ion-dependent conformational switch in the kissing process. However, for a long time, mechanistic understanding of the ion effects for the process has been unclear. Recently, computational modeling based on the Vfold RNA folding model and the partial charge-based tightly bound ion (PCTBI model, in combination with the NMR data, revealed novel physical insights into the role of metal ions in the 5BSL3.2-3′X system. The use of the PCTBI model, which accounts for the ion correlation and fluctuation, gives reliable predictions for the ion-dependent electrostatic free energy landscape and ion-induced population shift of the 5BSL3.2:3′X kissing complex. Furthermore, the predicted ion binding sites offer insights about how ion-RNA interactions shift the conformational equilibrium. The integrated theory-experiment study shows that Mg2+ ions may be essential for HCV viral replication. Moreover, the observed Mg2+-dependent conformational equilibrium may be an adaptive property of the HCV genomic RNA such that the equilibrium is optimized to the intracellular Mg2+ concentration in liver cells for efficient viral replication.
Complex Network Theory Applied to the Growth of Kuala Lumpur's Public Urban Rail Transit Network.
Directory of Open Access Journals (Sweden)
Rui Ding
Full Text Available Recently, the number of studies involving complex network applications in transportation has increased steadily as scholars from various fields analyze traffic networks. Nonetheless, research on rail network growth is relatively rare. This research examines the evolution of the Public Urban Rail Transit Networks of Kuala Lumpur (PURTNoKL based on complex network theory and covers both the topological structure of the rail system and future trends in network growth. In addition, network performance when facing different attack strategies is also assessed. Three topological network characteristics are considered: connections, clustering and centrality. In PURTNoKL, we found that the total number of nodes and edges exhibit a linear relationship and that the average degree stays within the interval [2.0488, 2.6774] with heavy-tailed distributions. The evolutionary process shows that the cumulative probability distribution (CPD of degree and the average shortest path length show good fit with exponential distribution and normal distribution, respectively. Moreover, PURTNoKL exhibits clear cluster characteristics; most of the nodes have a 2-core value, and the CPDs of the centrality's closeness and betweenness follow a normal distribution function and an exponential distribution, respectively. Finally, we discuss four different types of network growth styles and the line extension process, which reveal that the rail network's growth is likely based on the nodes with the biggest lengths of the shortest path and that network protection should emphasize those nodes with the largest degrees and the highest betweenness values. This research may enhance the networkability of the rail system and better shape the future growth of public rail networks.
Complex Network Theory Applied to the Growth of Kuala Lumpur's Public Urban Rail Transit Network.
Ding, Rui; Ujang, Norsidah; Hamid, Hussain Bin; Wu, Jianjun
2015-01-01
Recently, the number of studies involving complex network applications in transportation has increased steadily as scholars from various fields analyze traffic networks. Nonetheless, research on rail network growth is relatively rare. This research examines the evolution of the Public Urban Rail Transit Networks of Kuala Lumpur (PURTNoKL) based on complex network theory and covers both the topological structure of the rail system and future trends in network growth. In addition, network performance when facing different attack strategies is also assessed. Three topological network characteristics are considered: connections, clustering and centrality. In PURTNoKL, we found that the total number of nodes and edges exhibit a linear relationship and that the average degree stays within the interval [2.0488, 2.6774] with heavy-tailed distributions. The evolutionary process shows that the cumulative probability distribution (CPD) of degree and the average shortest path length show good fit with exponential distribution and normal distribution, respectively. Moreover, PURTNoKL exhibits clear cluster characteristics; most of the nodes have a 2-core value, and the CPDs of the centrality's closeness and betweenness follow a normal distribution function and an exponential distribution, respectively. Finally, we discuss four different types of network growth styles and the line extension process, which reveal that the rail network's growth is likely based on the nodes with the biggest lengths of the shortest path and that network protection should emphasize those nodes with the largest degrees and the highest betweenness values. This research may enhance the networkability of the rail system and better shape the future growth of public rail networks.
International Nuclear Information System (INIS)
Grizzi, Fabio; Russo, Carlo; Colombo, Piergiuseppe; Franceschini, Barbara; Frezza, Eldo E; Cobos, Everardo; Chiriva-Internati, Maurizio
2005-01-01
Modeling the complex development and growth of tumor angiogenesis using mathematics and biological data is a burgeoning area of cancer research. Architectural complexity is the main feature of every anatomical system, including organs, tissues, cells and sub-cellular entities. The vascular system is a complex network whose geometrical characteristics cannot be properly defined using the principles of Euclidean geometry, which is only capable of interpreting regular and smooth objects that are almost impossible to find in Nature. However, fractal geometry is a more powerful means of quantifying the spatial complexity of real objects. This paper introduces the surface fractal dimension (D s ) as a numerical index of the two-dimensional (2-D) geometrical complexity of tumor vascular networks, and their behavior during computer-simulated changes in vessel density and distribution. We show that D s significantly depends on the number of vessels and their pattern of distribution. This demonstrates that the quantitative evaluation of the 2-D geometrical complexity of tumor vascular systems can be useful not only to measure its complex architecture, but also to model its development and growth. Studying the fractal properties of neovascularity induces reflections upon the real significance of the complex form of branched anatomical structures, in an attempt to define more appropriate methods of describing them quantitatively. This knowledge can be used to predict the aggressiveness of malignant tumors and design compounds that can halt the process of angiogenesis and influence tumor growth
Surface-illuminant ambiguity and color constancy: effects of scene complexity and depth cues.
Kraft, James M; Maloney, Shannon I; Brainard, David H
2002-01-01
Two experiments were conducted to study how scene complexity and cues to depth affect human color constancy. Specifically, two levels of scene complexity were compared. The low-complexity scene contained two walls with the same surface reflectance and a test patch which provided no information about the illuminant. In addition to the surfaces visible in the low-complexity scene, the high-complexity scene contained two rectangular solid objects and 24 paper samples with diverse surface reflectances. Observers viewed illuminated objects in an experimental chamber and adjusted the test patch until it appeared achromatic. Achromatic settings made tinder two different illuminants were used to compute an index that quantified the degree of constancy. Two experiments were conducted: one in which observers viewed the stimuli directly, and one in which they viewed the scenes through an optical system that reduced cues to depth. In each experiment, constancy was assessed for two conditions. In the valid-cue condition, many cues provided valid information about the illuminant change. In the invalid-cue condition, some image cues provided invalid information. Four broad conclusions are drawn from the data: (a) constancy is generally better in the valid-cue condition than in the invalid-cue condition: (b) for the stimulus configuration used, increasing image complexity has little effect in the valid-cue condition but leads to increased constancy in the invalid-cue condition; (c) for the stimulus configuration used, reducing cues to depth has little effect for either constancy condition: and (d) there is moderate individual variation in the degree of constancy exhibited, particularly in the degree to which the complexity manipulation affects performance.
Analysing human mobility patterns of hiking activities through complex network theory.
Lera, Isaac; Pérez, Toni; Guerrero, Carlos; Eguíluz, Víctor M; Juiz, Carlos
2017-01-01
The exploitation of high volume of geolocalized data from social sport tracking applications of outdoor activities can be useful for natural resource planning and to understand the human mobility patterns during leisure activities. This geolocalized data represents the selection of hike activities according to subjective and objective factors such as personal goals, personal abilities, trail conditions or weather conditions. In our approach, human mobility patterns are analysed from trajectories which are generated by hikers. We propose the generation of the trail network identifying special points in the overlap of trajectories. Trail crossings and trailheads define our network and shape topological features. We analyse the trail network of Balearic Islands, as a case of study, using complex weighted network theory. The analysis is divided into the four seasons of the year to observe the impact of weather conditions on the network topology. The number of visited places does not decrease despite the large difference in the number of samples of the two seasons with larger and lower activity. It is in summer season where it is produced the most significant variation in the frequency and localization of activities from inland regions to coastal areas. Finally, we compare our model with other related studies where the network possesses a different purpose. One finding of our approach is the detection of regions with relevant importance where landscape interventions can be applied in function of the communities.
Analysing human mobility patterns of hiking activities through complex network theory.
Directory of Open Access Journals (Sweden)
Isaac Lera
Full Text Available The exploitation of high volume of geolocalized data from social sport tracking applications of outdoor activities can be useful for natural resource planning and to understand the human mobility patterns during leisure activities. This geolocalized data represents the selection of hike activities according to subjective and objective factors such as personal goals, personal abilities, trail conditions or weather conditions. In our approach, human mobility patterns are analysed from trajectories which are generated by hikers. We propose the generation of the trail network identifying special points in the overlap of trajectories. Trail crossings and trailheads define our network and shape topological features. We analyse the trail network of Balearic Islands, as a case of study, using complex weighted network theory. The analysis is divided into the four seasons of the year to observe the impact of weather conditions on the network topology. The number of visited places does not decrease despite the large difference in the number of samples of the two seasons with larger and lower activity. It is in summer season where it is produced the most significant variation in the frequency and localization of activities from inland regions to coastal areas. Finally, we compare our model with other related studies where the network possesses a different purpose. One finding of our approach is the detection of regions with relevant importance where landscape interventions can be applied in function of the communities.
Huang, Xuan; An, Haizhong; Gao, Xiangyun; Hao, Xiaoqing; Liu, Pengpeng
2015-06-01
This study introduces an approach to study the multiscale transmission characteristics of the correlation modes between bivariate time series. The correlation between the bivariate time series fluctuates over time. The transmission among the correlation modes exhibits a multiscale phenomenon, which provides richer information. To investigate the multiscale transmission of the correlation modes, this paper describes a hybrid model integrating wavelet analysis and complex network theory to decompose and reconstruct the original bivariate time series into sequences in a joint time-frequency domain and defined the correlation modes at each time-frequency domain. We chose the crude oil spot and futures prices as the sample data. The empirical results indicate that the main duration of volatility (32-64 days) for the strongly positive correlation between the crude oil spot price and the futures price provides more useful information for investors. Moreover, the weighted degree, weighted indegree and weighted outdegree of the correlation modes follow power-law distributions. The correlation fluctuation strengthens the extent of persistence over the long term, whereas persistence weakens over the short and medium term. The primary correlation modes dominating the transmission process and the major intermediary modes in the transmission process are clustered both in the short and long term.
Analysing human mobility patterns of hiking activities through complex network theory
Pérez, Toni; Guerrero, Carlos; Eguíluz, Víctor M.; Juiz, Carlos
2017-01-01
The exploitation of high volume of geolocalized data from social sport tracking applications of outdoor activities can be useful for natural resource planning and to understand the human mobility patterns during leisure activities. This geolocalized data represents the selection of hike activities according to subjective and objective factors such as personal goals, personal abilities, trail conditions or weather conditions. In our approach, human mobility patterns are analysed from trajectories which are generated by hikers. We propose the generation of the trail network identifying special points in the overlap of trajectories. Trail crossings and trailheads define our network and shape topological features. We analyse the trail network of Balearic Islands, as a case of study, using complex weighted network theory. The analysis is divided into the four seasons of the year to observe the impact of weather conditions on the network topology. The number of visited places does not decrease despite the large difference in the number of samples of the two seasons with larger and lower activity. It is in summer season where it is produced the most significant variation in the frequency and localization of activities from inland regions to coastal areas. Finally, we compare our model with other related studies where the network possesses a different purpose. One finding of our approach is the detection of regions with relevant importance where landscape interventions can be applied in function of the communities. PMID:28542280
Hydration of gas-phase ytterbium ion complexes studied by experiment and theory
Energy Technology Data Exchange (ETDEWEB)
Rutkowski, Philip X; Michelini, Maria C.; Bray, Travis H.; Russo, Nino; Marcalo, Joaquim; Gibson, John K.
2011-02-11
Hydration of ytterbium (III) halide/hydroxide ions produced by electrospray ionization was studied in a quadrupole ion trap mass spectrometer and by density functional theory (DFT). Gas-phase YbX{sub 2}{sup +} and YbX(OH){sup +} (X = OH, Cl, Br, or I) were found to coordinate from one to four water molecules, depending on the ion residence time in the trap. From the time dependence of the hydration steps, relative reaction rates were obtained. It was determined that the second hydration was faster than both the first and third hydrations, and the fourth hydration was the slowest; this ordering reflects a combination of insufficient degrees of freedom for cooling the hot monohydrate ion and decreasing binding energies with increasing hydration number. Hydration energetics and hydrate structures were computed using two approaches of DFT. The relativistic scalar ZORA approach was used with the PBE functional and all-electron TZ2P basis sets; the B3LYP functional was used with the Stuttgart relativistic small-core ANO/ECP basis sets. The parallel experimental and computational results illuminate fundamental aspects of hydration of f-element ion complexes. The experimental observations - kinetics and extent of hydration - are discussed in relationship to the computed structures and energetics of the hydrates. The absence of pentahydrates is in accord with the DFT results, which indicate that the lowest energy structures have the fifth water molecule in the second shell.
González-Navarrete, Patricio; Sensato, Fabricio R; Andrés, Juan; Longo, Elson
2014-08-07
In this research, a comprehensive theoretical investigation has been conducted on oxygen atom transfer (OAT) reactions from Mimoun complexes to sulfides and sulfoxides. The joint use of the electron localization function (ELF) and Thom's catastrophe theory (CT) provides a powerful tool to analyze the evolution of chemical events along a reaction pathway. The progress of the reaction has been monitored by structural stability domains from ELF topology while the changes between them are controlled by turning points derived from CT which reveal that the reaction mechanism can be separated in several steps: first, a rupture of the peroxo O1-O2 bond, then a rearrangement of lone pairs of the sulfur atom occurs and subsequently the formation of S-O1 bond. The OAT process involving the oxidation of sulfides and sulfoxides is found to be an asynchronous process where O1-O2 bond breaking and S-O1 bond formation processes do not occur simultaneously. Nucleophilic/electrophilic characters of both dimethyl sulfide and dimethyl sulfoxide, respectively, are sufficiently described by our results, which hold the key to unprecedented insight into the mapping of electrons that compose the bonds while the bonds change.
Townsend, G C; Kim, M; Sankey, D
2012-02-01
Although problem-based learning (PBL) was introduced into dental education some 20 years ago, there have been relatively few well-designed studies carried out to clarify whether, how or why it works in a dental context. This paper introduces the Dynamic Systems (Complexity) theory as a new and potentially productive theoretical framework for researching PBL in dental education. This framework emphasises the importance of emergent self-organisation, perception and brain plasticity in learning. In this paper, a brief overview of the history of PBL in dentistry is presented and then the fundamentals of a Dynamic Systems Approach (DSA) are explained, drawing on two recently published papers advocating the DSA in medical education and teacher education. We focus on three key points related to this new approach: emergent self-organisation rather than simple construction of knowledge; the notion that perception drives the learning process; and the brain as the substrate of all learning. The paper also suggests how the DSA can help us move forward, both in terms of the future application of PBL in dental education and also in relation to posing new types of research questions. © 2011 John Wiley & Sons A/S.
A hybrid 3D SEM reconstruction method optimized for complex geologic material surfaces.
Yan, Shang; Adegbule, Aderonke; Kibbey, Tohren C G
2017-08-01
Reconstruction methods are widely used to extract three-dimensional information from scanning electron microscope (SEM) images. This paper presents a new hybrid reconstruction method that combines stereoscopic reconstruction with shape-from-shading calculations to generate highly-detailed elevation maps from SEM image pairs. The method makes use of an imaged glass sphere to determine the quantitative relationship between observed intensity and angles between the beam and surface normal, and the detector and surface normal. Two specific equations are derived to make use of image intensity information in creating the final elevation map. The equations are used together, one making use of intensities in the two images, the other making use of intensities within a single image. The method is specifically designed for SEM images captured with a single secondary electron detector, and is optimized to capture maximum detail from complex natural surfaces. The method is illustrated with a complex structured abrasive material, and a rough natural sand grain. Results show that the method is capable of capturing details such as angular surface features, varying surface roughness, and surface striations. Copyright © 2017 Elsevier Ltd. All rights reserved.
International Nuclear Information System (INIS)
Kabdyrakova, A.M.; Artem'ev, O.I.; Protskij, A.V.; Bimendina, L.A.; Yashkarova, M.G.; Orazzhanova, L.K.
2005-01-01
Pentifylline of betaine structure was synthesised on the basis of 3-aminocrotonate and acrylic acid. Polyamfolit composition and its complexes with anionic surface-active material (lauryl sulfate of sodium) were determined. It is revealed that complex formation occurs with [polyamfolit]:[surface active material]=1:1 ratio and is accompanied by significant reduce of system characteristics viscosity. The paper presents results of [polyamfolit]:[surface active material] complex apply experimental investigation for radionuclide directed migration in soil. (author)
Surface glycosylation of polysulfone membrane towards a novel complexing membrane for boron removal.
Meng, Jianqiang; Yuan, Jing; Kang, Yinlin; Zhang, Yufeng; Du, Qiyun
2012-02-15
In this study, a novel complexing membrane was synthesized for boron removal from aqueous solution. A glycopolymer, poly(2-gluconamidoethyl methacrylate) (PGAMA), was grafted onto the chloromethylated polysulfone (CMPSF) microporous membrane via surface-initiated ATRP (SIATRP). The glycosylated PSF (GlyPSF) membrane was characterized by attenuated total refection-Flourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), and field emission scanning electron microscopy (FESEM). It was demonstrated that PGAMA was successfully anchored onto the membrane surface and the grafting yield can be tuned in a wide range up to 5.9 mg/cm(2) by varying the polymerization time. The complexing membrane can adsorb boron rapidly with the equilibrium reached within 2h and has a remarkable high boron adsorption capacity higher than 2.0 mmol/g at optimized conditions. Freundlich, Langmuir, and Dubinin-Radushkevich adsorption isotherms were applied, and the data were best described by Langmuir model. Kinetic data were analyzed, and the data fitted very well to the pseudo-second-order rate expression. The optimal pH for boron uptake is in a wide range of 6-9, and the optimal initial boron concentration is over 300 mg/L. Studies of ionic strength effects indicated the formation of inner-sphere surface complexes. The complexed boron can be leached quantitatively under acid condition. Copyright © 2011 Elsevier Inc. All rights reserved.
Directory of Open Access Journals (Sweden)
Mikdam Jamal
2017-12-01
Full Text Available Metal additive manufacturing (AM is increasingly used to create complex 3D components at near net shape. However, the surface finish (SF of the metal AM part is uneven, with surface roughness being variable over the facets of the design. Standard post-processing methods such as grinding and linishing often meet with major challenges in finishing parts of complex shape. This paper reports on research that demonstrated that mass finishing (MF processes are able to deliver high-quality surface finishes (Ra and Sa on AM-generated parts of a relatively complex geometry (both internal features and external facets under select conditions. Four processes were studied in this work: stream finishing, high-energy (HE centrifuge, drag finishing and disc finishing. Optimisation of the drag finishing process was then studied using a structured design of experiments (DOE. The effects of a range of finishing parameters were evaluated and optimal parameters and conditions were determined. The study established that the proposed method can be successfully applied in drag finishing to optimise the surface roughness in an industrial application and that it is an economical way of obtaining the maximum amount of information in a short period of time with a small number of tests. The study has also provided an important step in helping understand the requirements of MF to deliver AM-generated parts to a target quality finish and cycle time.
Murray, P J; Spithill, T W; Handman, E
1989-12-15
Polyclonal rabbit antiserum to the Triton X-114 phase material of Leishmania major, which comprises the surface and internal integral membrane proteins of the parasite, was used to screen a lambda gt11 genomic expression library. A recombinant clone producing a Mr 123,000 beta-galactosidase fusion protein was isolated. Antibodies affinity-purified on this fusion protein recognized a complex of three surface-oriented proteins of promastigotes of L. major of Mr 94,000, 90,000, and 80,000 that we have termed the promastigote surface Ag 2 (PSA-2) complex. The DNA sequence of the insert in this clone predicted the 3' end of an open reading frame encoding a hydrophobic C-terminus. The inferred C-terminal sequence was suggestive of a glycosylphosphatidyl-inositol membrane anchoring mechanism. Phosphatidylinositol-specific phospholipase C treatment of the native PSA-2 proteins caused a shift in their electrophoretic mobility with an apparent reduction in the molecular weight of the PSA-2 complex. After phospholipase C treatment these proteins also displayed the cryptic cross-reacting determinant recognized by antibodies to the Trypanosoma brucei variant surface Ag. Moreover, PSA-2, which previously partitioned in the detergent phase after Triton X-114 phase separation, became water-soluble after phospholipase C treatment. Immunoprecipitation of the PSA-2 proteins with sera directed to lectin-binding proteins indicated that these polypeptides may be differentially glycosylated. Finally, these PSA-2 proteins were recognized by sera from some patients with cutaneous leishmaniasis.
International Nuclear Information System (INIS)
Kulik, D.A.
2005-01-01
Full text of publication follows: Computer-aided surface complexation models (SCM) tend to replace the classic adsorption isotherm (AI) analysis in describing mineral-water interface reactions such as radionuclide sorption onto (hydr) oxides and clays. Any site-binding SCM based on the mole balance of surface sites, in fact, reproduces the (competitive) Langmuir isotherm, optionally amended with electrostatic Coulomb's non-ideal term. In most SCM implementations, it is difficult to incorporate real-surface phenomena (site heterogeneity, lateral interactions, surface condensation) described in classic AI approaches other than Langmuir's. Thermodynamic relations between SCMs and AIs that remained obscure in the past have been recently clarified using new definitions of standard and reference states of surface species [1,2]. On this basis, a method for separating the Langmuir AI into ideal (linear) and non-ideal parts [2] was applied to multi-dentate Langmuir, Frumkin, and BET isotherms. The aim of this work was to obtain the surface activity coefficient terms that make the SCM site mole balance constraints obsolete and, in this way, extend thermodynamic SCMs to cover sorption phenomena described by the respective AIs. The multi-dentate Langmuir term accounts for the site saturation with n-dentate surface species, as illustrated on modeling bi-dentate U VI complexes on goethite or SiO 2 surfaces. The Frumkin term corrects for the lateral interactions of the mono-dentate surface species; in particular, it has the same form as the Coulombic term of the constant-capacitance EDL combined with the Langmuir term. The BET term (three parameters) accounts for more than a monolayer adsorption up to the surface condensation; it can potentially describe the surface precipitation of nickel and other cations on hydroxides and clay minerals. All three non-ideal terms (in GEM SCMs implementation [1,2]) by now are used for non-competing surface species only. Upon 'surface dilution
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Veselská, Veronika, E-mail: veselskav@fzp.czu.cz [Department of Environmental Geosciences, Faculty of Environmental Sciences, Czech University of Life Sciences Prague, Kamýcka 129, CZ-16521, Prague (Czech Republic); Fajgar, Radek [Department of Analytical and Material Chemistry, Institute of Chemical Process Fundamentals of the CAS, v.v.i., Rozvojová 135/1, CZ-16502, Prague (Czech Republic); Číhalová, Sylva [Department of Environmental Geosciences, Faculty of Environmental Sciences, Czech University of Life Sciences Prague, Kamýcka 129, CZ-16521, Prague (Czech Republic); Bolanz, Ralph M. [Institute of Geosciences, Friedrich-Schiller-University Jena, Carl-Zeiss-Promenade 10, DE-07745, Jena (Germany); Göttlicher, Jörg; Steininger, Ralph [ANKA Synchrotron Radiation Facility, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, DE-76344, Eggenstein-Leopoldshafen (Germany); Siddique, Jamal A.; Komárek, Michael [Department of Environmental Geosciences, Faculty of Environmental Sciences, Czech University of Life Sciences Prague, Kamýcka 129, CZ-16521, Prague (Czech Republic)
2016-11-15
Highlights: • Study of Cr(VI) adsorption on soil minerals over a large range of conditions. • Combined surface complexation modeling and spectroscopic techniques. • Diffuse-layer and triple-layer models used to obtain fits to experimental data. • Speciation of Cr(VI) and Cr(III) was assessed. - Abstract: This study investigates the mechanisms of Cr(VI) adsorption on natural clay (illite and kaolinite) and synthetic (birnessite and ferrihydrite) minerals, including its speciation changes, and combining quantitative thermodynamically based mechanistic surface complexation models (SCMs) with spectroscopic measurements. Series of adsorption experiments have been performed at different pH values (3–10), ionic strengths (0.001–0.1 M KNO{sub 3}), sorbate concentrations (10{sup −4}, 10{sup −5}, and 10{sup −6} M Cr(VI)), and sorbate/sorbent ratios (50–500). Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy were used to determine the surface complexes, including surface reactions. Adsorption of Cr(VI) is strongly ionic strength dependent. For ferrihydrite at pH <7, a simple diffuse-layer model provides a reasonable prediction of adsorption. For birnessite, bidentate inner-sphere complexes of chromate and dichromate resulted in a better diffuse-layer model fit. For kaolinite, outer-sphere complexation prevails mainly at lower Cr(VI) loadings. Dissolution of solid phases needs to be considered for better SCMs fits. The coupled SCM and spectroscopic approach is thus useful for investigating individual minerals responsible for Cr(VI) retention in soils, and improving the handling and remediation processes.
Surface complexation modeling of Cu(II adsorption on mixtures of hydrous ferric oxide and kaolinite
Directory of Open Access Journals (Sweden)
Schaller Melinda S
2008-09-01
Full Text Available Abstract Background The application of surface complexation models (SCMs to natural sediments and soils is hindered by a lack of consistent models and data for large suites of metals and minerals of interest. Furthermore, the surface complexation approach has mostly been developed and tested for single solid systems. Few studies have extended the SCM approach to systems containing multiple solids. Results Cu adsorption was measured on pure hydrous ferric oxide (HFO, pure kaolinite (from two sources and in systems containing mixtures of HFO and kaolinite over a wide range of pH, ionic strength, sorbate/sorbent ratios and, for the mixed solid systems, using a range of kaolinite/HFO ratios. Cu adsorption data measured for the HFO and kaolinite systems was used to derive diffuse layer surface complexation models (DLMs describing Cu adsorption. Cu adsorption on HFO is reasonably well described using a 1-site or 2-site DLM. Adsorption of Cu on kaolinite could be described using a simple 1-site DLM with formation of a monodentate Cu complex on a variable charge surface site. However, for consistency with models derived for weaker sorbing cations, a 2-site DLM with a variable charge and a permanent charge site was also developed. Conclusion Component additivity predictions of speciation in mixed mineral systems based on DLM parameters derived for the pure mineral systems were in good agreement with measured data. Discrepancies between the model predictions and measured data were similar to those observed for the calibrated pure mineral systems. The results suggest that quantifying specific interactions between HFO and kaolinite in speciation models may not be necessary. However, before the component additivity approach can be applied to natural sediments and soils, the effects of aging must be further studied and methods must be developed to estimate reactive surface areas of solid constituents in natural samples.
A general rough-surface inversion algorithm: Theory and application to SAR data
Moghaddam, M.
1993-01-01
Rough-surface inversion has significant applications in interpretation of SAR data obtained over bare soil surfaces and agricultural lands. Due to the sparsity of data and the large pixel size in SAR applications, it is not feasible to carry out inversions based on numerical scattering models. The alternative is to use parameter estimation techniques based on approximate analytical or empirical models. Hence, there are two issues to be addressed, namely, what model to choose and what estimation algorithm to apply. Here, a small perturbation model (SPM) is used to express the backscattering coefficients of the rough surface in terms of three surface parameters. The algorithm used to estimate these parameters is based on a nonlinear least-squares criterion. The least-squares optimization methods are widely used in estimation theory, but the distinguishing factor for SAR applications is incorporating the stochastic nature of both the unknown parameters and the data into formulation, which will be discussed in detail. The algorithm is tested with synthetic data, and several Newton-type least-squares minimization methods are discussed to compare their convergence characteristics. Finally, the algorithm is applied to multifrequency polarimetric SAR data obtained over some bare soil and agricultural fields. Results will be shown and compared to ground-truth measurements obtained from these areas. The strength of this general approach to inversion of SAR data is that it can be easily modified for use with any scattering model without changing any of the inversion steps. Note also that, for the same reason it is not limited to inversion of rough surfaces, and can be applied to any parameterized scattering process.
Surface complexation modeling calculation of Pb(II) adsorption onto the calcined diatomite
Ma, Shu-Cui; Zhang, Ji-Lin; Sun, De-Hui; Liu, Gui-Xia
2015-12-01
Removal of noxious heavy metal ions (e.g. Pb(II)) by surface adsorption of minerals (e.g. diatomite) is an important means in the environmental aqueous pollution control. Thus, it is very essential to understand the surface adsorptive behavior and mechanism. In this work, the Pb(II) apparent surface complexation reaction equilibrium constants on the calcined diatomite and distributions of Pb(II) surface species were investigated through modeling calculations of Pb(II) based on diffuse double layer model (DLM) with three amphoteric sites. Batch experiments were used to study the adsorption of Pb(II) onto the calcined diatomite as a function of pH (3.0-7.0) and different ionic strengths (0.05 and 0.1 mol L-1 NaCl) under ambient atmosphere. Adsorption of Pb(II) can be well described by Freundlich isotherm models. The apparent surface complexation equilibrium constants (log K) were obtained by fitting the batch experimental data using the PEST 13.0 together with PHREEQC 3.1.2 codes and there is good agreement between measured and predicted data. Distribution of Pb(II) surface species on the diatomite calculated by PHREEQC 3.1.2 program indicates that the impurity cations (e.g. Al3+, Fe3+, etc.) in the diatomite play a leading role in the Pb(II) adsorption and dominant formation of complexes and additional electrostatic interaction are the main adsorption mechanism of Pb(II) on the diatomite under weak acidic conditions.
Harada, Hiromitsu; Mouchet, Amaury; Shudo, Akira
2017-10-01
The topology of complex classical paths is investigated to discuss quantum tunnelling splittings in one-dimensional systems. Here the Hamiltonian is assumed to be given as polynomial functions, so the fundamental group for the Riemann surface provides complete information on the topology of complex paths, which allows us to enumerate all the possible candidates contributing to the semiclassical sum formula for tunnelling splittings. This naturally leads to action relations among classically disjoined regions, revealing entirely non-local nature in the quantization condition. The importance of the proper treatment of Stokes phenomena is also discussed in Hamiltonians in the normal form.
Surface Structures Formed by a Copper(II Complex of Alkyl-Derivatized Indigo
Directory of Open Access Journals (Sweden)
Akinori Honda
2016-10-01
Full Text Available Assembled structures of dyes have great influence on their coloring function. For example, metal ions added in the dyeing process are known to prevent fading of color. Thus, we have investigated the influence of an addition of copper(II ion on the surface structure of alkyl-derivatized indigo. Scanning tunneling microscope (STM analysis revealed that the copper(II complexes of indigo formed orderly lamellar structures on a HOPG substrate. These lamellar structures of the complexes are found to be more stable than those of alkyl-derivatized indigos alone. Furthermore, 2D chirality was observed.
Evaluating polymer degradation with complex mixtures using a simplified surface area method.
Steele, Kandace M; Pelham, Todd; Phalen, Robert N
2017-09-01
Chemical-resistant gloves, designed to protect workers from chemical hazards, are made from a variety of polymer materials such as plastic, rubber, and synthetic rubber. One material does not provide protection against all chemicals, thus proper polymer selection is critical. Standardized testing, such as chemical degradation tests, are used to aid in the selection process. The current methods of degradation ratings based on changes in weight or tensile properties can be expensive and data often do not exist for complex chemical mixtures. There are hundreds of thousands of chemical products on the market that do not have chemical resistance data for polymer selection. The method described in this study provides an inexpensive alternative to gravimetric analysis. This method uses surface area change to evaluate degradation of a polymer material. Degradation tests for 5 polymer types against 50 complex mixtures were conducted using both gravimetric and surface area methods. The percent change data were compared between the two methods. The resulting regression line was y = 0.48x + 0.019, in units of percent, and the Pearson correlation coefficient was r = 0.9537 (p ≤ 0.05), which indicated a strong correlation between percent weight change and percent surface area change. On average, the percent change for surface area was about half that of the weight change. Using this information, an equivalent rating system was developed for determining the chemical degradation of polymer gloves using surface area.
Surface tension of a Yukawa fluid according to mean-field theory.
Bossa, Guilherme Volpe; Norris, Joseph; May, Sylvio
2017-04-07
Yukawa fluids consist of particles that interact through a repulsive or attractive Yukawa potential. A surface tension arises at the walls of the container that encloses the fluid or at the interface between two coexisting phases. We calculate that surface tension on the level of mean-field theory, thereby either ignoring the particle size (ideal Yukawa fluid) or accounting for a non-vanishing particle size through a nonideal contribution to the free energy, exemplified either on the level of a lattice gas (lattice Yukawa fluid) or based on the Carnahan-Starling equation of state (Carnahan-Starling Yukawa fluid). Our mean-field results, which do not rely on assuming small gradients of the particle concentrations, become exact in the limit of large temperature and large screening length. They are calculated numerically in the general case and analytically in the two limits of small particle concentration and close to the critical point for a phase-separating system. For a sufficiently small particle concentration, our predicted surface tension is accurate whereas for a phase boundary, we expect good agreement with exact calculations in the limit of a large screening length and if the mean-field model employs the Carnahan-Starling equation of state.
Effect of liquid surface tension on circular and linear hydraulic jumps; theory and experiments
Bhagat, Rajesh Kumar; Jha, Narsing Kumar; Linden, Paul F.; Wilson, David Ian
2017-11-01
The hydraulic jump has attracted considerable attention since Rayleigh published his account in 1914. Watson (1964) proposed the first satisfactory explanation of the circular hydraulic jump by balancing the momentum and hydrostatic pressure across the jump, but this solution did not explain what actually causes the jump to form. Bohr et al. (1992) showed that the hydraulic jump happens close to the point where the local Froude number equals to one, suggesting a balance between inertial and hydrostatic contributions. Bush & Aristoff (2003) subsequently incorporated the effect of surface tension and showed that this is important when the jump radius is small. In this study, we propose a new account to explain the formation and evolution of hydraulic jumps under conditions where the jump radius is strongly influenced by the liquid surface tension. The theory is compared with experiments employing liquids of different surface tension and different viscosity, in circular and linear configurations. The model predictions and the experimental results show excellent agreement. Commonwealth Scholarship Commission, St. John's college, University of Cambridge.
Density functional theory study of carbon dioxide electrochemical reduction on the Fe(100) surface.
Bernstein, Nicole J; Akhade, Sneha A; Janik, Michael J
2014-07-21
Carbon dioxide electroreduction offers the possibility of producing hydrocarbon fuels using energy from renewable sources. Herein, we use density functional theory to analyze the feasibility of CO2 electroreduction on a Fe(100) surface. Experimentally, iron is nonselective for hydrocarbon formation. A simplistic analysis of low-coverage reaction intermediate energies for the paths to produce CH4 and CH3OH from CO2 suggests Fe(100) could be more active than Cu(111), currently the only metallic catalyst to show selectivity towards hydrocarbon formation. We consider a series of impediments to CO2 electroreduction on Fe(100) including O*/OH* (* denotes surface bound species) blockage of active surface sites; competitive adsorption effects of H*, CO* and C*; and iron carbide formation. Our results indicate that under CO2 electroreduction conditions, Fe(100) is predicted to be covered in C* or CO* species, blocking any C-H bond formation. Further, bulk Fe is predicted to be unstable relative to FeCx formation at potentials relevant to CO2 electroreduction conditions.
Energy Technology Data Exchange (ETDEWEB)
Lorquet, J. C., E-mail: jc.lorquet@ulg.ac.be [Department of Chemistry, University of Liège, Sart-Tilman (Bâtiment B6), B-4000 Liège 1 (Belgium)
2015-09-14
The purpose of the present work is to determine initial conditions that generate reacting, recrossing-free trajectories that cross the conventional dividing surface of transition state theory (i.e., the plane in configuration space passing through a saddle point of the potential energy surface and perpendicular to the reaction coordinate) without ever returning to it. Local analytical equations of motion valid in the neighborhood of this planar surface have been derived as an expansion in Poisson brackets. We show that the mere presence of a saddle point implies that reactivity criteria can be quite simply formulated in terms of elements of this series, irrespective of the shape of the potential energy function. Some of these elements are demonstrated to be equal to a sum of squares and thus to be necessarily positive, which has a profound impact on the dynamics. The method is then applied to a three-dimensional model describing an atom-diatom interaction. A particular relation between initial conditions is shown to generate a bundle of reactive trajectories that form reactive cylinders (or conduits) in phase space. This relation considerably reduces the phase space volume of initial conditions that generate recrossing-free trajectories. Loci in phase space of reactive initial conditions are presented. Reactivity is influenced by symmetry, as shown by a comparative study of collinear and bent transition states. Finally, it is argued that the rules that have been derived to generate reactive trajectories in classical mechanics are also useful to build up a reactive wave packet.
Schäfer, Sascha; Liang, Wenxi; Zewail, Ahmed H
2011-12-07
Recent studies in ultrafast electron crystallography (UEC) using a reflection diffraction geometry have enabled the investigation of a wide range of phenomena on the femtosecond and picosecond time scales. In all these studies, the analysis of the diffraction patterns and their temporal change after excitation was performed within the kinematical scattering theory. In this contribution, we address the question, to what extent dynamical scattering effects have to be included in order to obtain quantitative information about structural dynamics. We discuss different scattering regimes and provide diffraction maps that describe all essential features of scatterings and observables. The effects are quantified by dynamical scattering simulations and examined by direct comparison to the results of ultrafast electron diffraction experiments on an in situ prepared Ni(100) surface, for which structural dynamics can be well described by a two-temperature model. We also report calculations for graphite surfaces. The theoretical framework provided here allows for further UEC studies of surfaces especially at larger penetration depths and for those of heavy-atom materials. © 2011 American Institute of Physics
Application of the complex cepstrum to the location of acoustic sources near reflective surfaces
Fuller, C. R.; Tavakkoli, S.; Elliott, K. B.; Hurst, C. J.; Obrien, W. F.
1987-01-01
The complex cepstrum is used to correct bearing estimations of acoustic sources in the presence of a reflective surface. An automated liftering procedure is used which zeros out a block portion of the cepstrum including the echo information. The problem of the resulting distortion is alleviated by applying a coherence criterion to the recovered direct signals at each microphone. Thus to a large degree the interactive nature of cepstral processing is overcome for this application. For the test signals and geometries considered the cepstrum is shown to accurately correct for bearing errors in acoustic signals contaminated with reflections from nearby surfaces.
Ormandy, Paula
2011-03-01
Key policy drivers worldwide include optimizing patients' roles in managing their care; focusing services around patients' needs and preferences; and providing information to support patients' contributions and choices. The term information need penetrates many policy documents. Information need is espoused as the foundation from which to develop patient-centred or patient-led services. Yet there is no clear definition as to what the term means or how patients' information needs inform and shape information provision and patient care. The assimilation of complex theories originating from information science has much to offer considerations of patient information need within the context of health care. Health-related research often focuses on the content of information patients prefer, not why they need information. This paper extends and applies knowledge of information behaviour to considerations of information need in health, exposing a working definition for patient information need that reiterates the importance of considering the patient's goals and understanding the patient's context/situation. A patient information need is defined as 'recognition that their knowledge is inadequate to satisfy a goal, within the context/situation that they find themselves at a specific point in the time'. This typifies the key concepts of national/international health policy, the centrality and importance of the patient. The proposed definition of patient information need provides a conceptual framework to guide health-care practitioners on what to consider and why when meeting the information needs of patients in practice. This creates a solid foundation from which to inform future research. © 2010 The Author. Health Expectations © 2010 Blackwell Publishing Ltd.
Modeling and simulation for fewer-axis grinding of complex surface
Li, Zhengjian; Peng, Xiaoqiang; Song, Ci
2017-10-01
As the basis of fewer-axis grinding of complex surface, the grinding mathematical model is of great importance. A mathematical model of the grinding wheel was established, and then coordinate and normal vector of the wheel profile could be calculated. Through normal vector matching at the cutter contact point and the coordinate system transformation, the grinding mathematical model was established to work out the coordinate of the cutter location point. Based on the model, interference analysis was simulated to find out the right position and posture of workpiece for grinding. Then positioning errors of the workpiece including the translation positioning error and the rotation positioning error were analyzed respectively, and the main locating datum was obtained. According to the analysis results, the grinding tool path was planned and generated to grind the complex surface, and good form accuracy was obtained. The grinding mathematical model is simple, feasible and can be widely applied.
Schindler, Michael
2017-08-02
The classification of effects caused by mixtures of agents as synergistic, antagonistic or additive depends critically on the reference model of 'null interaction'. Two main approaches are currently in use, the Additive Dose (ADM) or concentration addition (CA) and the Multiplicative Survival (MSM) or independent action (IA) models. We compare several response surface models to a newly developed Hill response surface, obtained by solving a logistic partial differential equation (PDE). Assuming that a mixture of chemicals with individual Hill-type dose-response curves can be described by an n-dimensional logistic function, Hill's differential equation for pure agents is replaced by a PDE for mixtures whose solution provides Hill surfaces as 'null-interaction' models and relies neither on Bliss independence or Loewe additivity nor uses Chou's unified general theory. An n-dimensional logistic PDE decribing the Hill-type response of n-component mixtures is solved. Appropriate boundary conditions ensure the correct asymptotic behaviour. Mathematica 11 (Wolfram, Mathematica Version 11.0, 2016) is used for the mathematics and graphics presented in this article. The Hill response surface ansatz can be applied to mixtures of compounds with arbitrary Hill parameters. Restrictions which are required when deriving analytical expressions for response surfaces from other principles, are unnecessary. Many approaches based on Loewe additivity turn out be special cases of the Hill approach whose increased flexibility permits a better description of 'null-effect' responses. Missing sham-compliance of Bliss IA, known as Colby's model in agrochemistry, leads to incompatibility with the Hill surface ansatz. Examples of binary and ternary mixtures illustrate the differences between the approaches. For Hill-slopes close to one and doses below the half-maximum effect doses MSM (Colby, Bliss, Finney, Abbott) predicts synergistic effects where the Hill model indicates 'null
Wen, Jiayi; Zhou, Shenggao; Xu, Zhenli; Li, Bo
2012-04-01
Competitive adsorption of counterions of multiple species to charged surfaces is studied by a size-effect-included mean-field theory and Monte Carlo (MC) simulations. The mean-field electrostatic free-energy functional of ionic concentrations, constrained by Poisson's equation, is numerically minimized by an augmented Lagrangian multiplier method. Unrestricted primitive models and canonical ensemble MC simulations with the Metropolis criterion are used to predict the ionic distributions around a charged surface. It is found that, for a low surface charge density, the adsorption of ions with a higher valence is preferable, agreeing with existing studies. For a highly charged surface, both the mean-field theory and the MC simulations demonstrate that the counterions bind tightly around the charged surface, resulting in a stratification of counterions of different species. The competition between mixed entropy and electrostatic energetics leads to a compromise that the ionic species with a higher valence-to-volume ratio has a larger probability to form the first layer of stratification. In particular, the MC simulations confirm the crucial role of ionic valence-to-volume ratios in the competitive adsorption to charged surfaces that had been previously predicted by the mean-field theory. The charge inversion for ionic systems with salt is predicted by the MC simulations but not by the mean-field theory. This work provides a better understanding of competitive adsorption of counterions to charged surfaces and calls for further studies on the ionic size effect with application to large-scale biomolecular modeling.
International Nuclear Information System (INIS)
Karimzadeh, Lotfallah; Barthen, Robert; Gruendig, Marion; Franke, Karsten; Lippmann-Pipke, Johanna; Stockmann, Madlen
2017-01-01
In this work, we study the mobility behavior of Cu(II) under conditions related to an alternative, neutrophile biohydrometallurgical Cu(II) leaching approach. Sorption of copper onto kaolinite influenced by glutamic acid (Glu) was investigated in the presence of 0.01 M NaClO 4 by means of binary and ternary batch adsorption measurements over a pH range of 4 to 9 and surface complexation modeling.
Integrating Sound Scattering Measurements in the Design of Complex Architectural Surfaces
DEFF Research Database (Denmark)
Peters, Brady
2010-01-01
Digital tools present the opportunity for incorporating performance analysis into the architectural design process. Acoustic performance is an important criterion for architectural design. There is much known about sound absorption but little about sound scattering, even though scattering...... is recognized to be one of the most important factors in predicting the computational prediction of acoustic performance. This paper proposes a workflow for the design of complex architectural surfaces and the prediction of their sound scattering properties. This workflow includes the development...
Energy Technology Data Exchange (ETDEWEB)
Karimzadeh, Lotfallah; Barthen, Robert; Gruendig, Marion; Franke, Karsten; Lippmann-Pipke, Johanna [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Reactive Transport; Stockmann, Madlen [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Surface Processes
2017-06-01
In this work, we study the mobility behavior of Cu(II) under conditions related to an alternative, neutrophile biohydrometallurgical Cu(II) leaching approach. Sorption of copper onto kaolinite influenced by glutamic acid (Glu) was investigated in the presence of 0.01 M NaClO{sub 4} by means of binary and ternary batch adsorption measurements over a pH range of 4 to 9 and surface complexation modeling.
A novel Pfs38 protein complex on the surface of Plasmodium falciparum blood-stage merozoites
DEFF Research Database (Denmark)
Paul, Gourab; Deshmukh, Arunaditya; Kaur, Inderjeet
2017-01-01
BACKGROUND: The Plasmodium genome encodes for a number of 6-Cys proteins that contain a module of six cysteine residues forming three intramolecular disulphide bonds. These proteins have been well characterized at transmission as well as hepatic stages of the parasite life cycle. In the present...... the development of a multi-sub-unit malaria vaccine based on some of these protein complexes on merozoite surface....
Potential energy surface and rovibrational energy levels of the H2-CS van der Waals complex.
Denis-Alpizar, Otoniel; Stoecklin, Thierry; Halvick, Philippe; Dubernet, Marie-Lise; Marinakis, Sarantos
2012-12-21
Owing to its large dipole, astrophysicists use carbon monosulfide (CS) as a tracer of molecular gas in the interstellar medium, often in regions where H(2) is the most abundant collider. Predictions of the rovibrational energy levels of the weakly bound complex CS-H(2) (not yet observed) and also of rate coefficients for rotational transitions of CS in collision with H(2) should help to interpret the observed spectra. This paper deals with the first goal, i.e., the calculation of the rovibrational energy levels. A new four-dimensional intermolecular potential energy surface for the H(2)-CS complex is presented. Ab initio potential energy calculations were carried out at the coupled-cluster level with single and double excitations and a perturbative treatment of triple excitations, using a quadruple-zeta basis set and midbond functions. The potential energy surface was obtained by an analytic fit of the ab initio data. The equilibrium structure of the H(2)-CS complex is found to be linear with the carbon pointing toward H(2) at the intermolecular separation of 8.6 a(o). The corresponding well depth is -173 cm(-1). The potential was used to calculate the rovibrational energy levels of the para-H(2)-CS and ortho-H(2)-CS complexes. The present work provides the first theoretical predictions of these levels. The calculated dissociation energies are found to be 35.9 cm(-1) and 49.9 cm(-1), respectively, for the para and ortho complexes. The second virial coefficient for the H(2)-CS pair has also been calculated for a large range of temperature. These results could be used to assign future experimental spectra and to check the accuracy of the potential energy surface.
Pototzky, Anthony S; Murphy, Patrick C.
2014-01-01
Improving aerodynamic models for adverse loss-of-control conditions in flight is an area being researched under the NASA Aviation Safety Program. Aerodynamic models appropriate for loss of control conditions require a more general mathematical representation to predict nonlinear unsteady behaviors. As more general aerodynamic models are studied that include nonlinear higher order effects, the possibility of measurements that confound aerodynamic and structural responses are probable. In this study an initial step is taken to look at including structural flexibility in analysis of rigid-body forced-oscillation testing that accounts for dynamic rig, sting and balance flexibility. Because of the significant testing required and associated costs in a general study, it makes sense to capitalize on low cost analytical methods where possible, especially where structural flexibility can be accounted for by a low cost method. This paper provides an initial look at using linear lifting surface theory applied to rigid-body aircraft roll forced-oscillation tests.
International Nuclear Information System (INIS)
Park, Sang-Won; Leckie, J.O.; Siegel, M.D.
1995-09-01
Corrensite is the dominant clay mineral in the Culebra Dolomite at the Waste Isolation Pilot Plant. The surface characteristics of corrensite, a mixed chlorite/smectite clay mineral, have been studied. Zeta potential measurements and titration experiments suggest that the corrensite surface contains a mixture of permanent charge sites on the basal plane and SiOH and AlOH sites with a net pH-dependent charge at the edge of the clay platelets. Triple-layer model parameters were determined by the double extrapolation technique for use in chemical speciation calculations of adsorption reactions using the computer program HYDRAQL. Batch adsorption studies showed that corrensite is an effective adsorbent for uranyl. The pH-dependent adsorption behavior indicates that adsorption occurs at the edge sites. Adsorption studies were also conducted in the presence of competing cations and complexing ligands. The cations did not affect uranyl adsorption in the range studied. This observation lends support to the hypothesis that uranyl adsorption occurs at the edge sites. Uranyl adsorption was significantly hindered by carbonate. It is proposed that the formation of carbonate uranyl complexes inhibits uranyl adsorption and that only the carbonate-free species adsorb to the corrensite surface. The presence of the organic complexing agents EDTA and oxine also inhibits uranyl sorption
Pressure and surface tension of soild-liquid interface using Tarazona density functional theory
Directory of Open Access Journals (Sweden)
M. M.
2000-12-01
Full Text Available The weighted density functional theory proposed by Tarazona is applied to study the solid-liquid interface. In the last two decades the weighted density functional became a useful tool to consider the properties of inhomogeneous liquids. In this theory, the role of the size of molecules or the particles of which the matter is composed, was found to be important. In this resarch we study a hard sphere fluid beside a hard wall. For this study the liquid is an inhomogeneous system. We use the definition of the direct correlation function as a second derivative of free energy with respect to the density. We use this definition and the definition of the weighting function, then we minimize the grand potential with respect to the density to get the Euler Lagrange equation and we obtain an integral equation to find the inhomogeneous density profile. The obtained density profile as a function of the distance from the wall, for different bulk density is plotted in three dimensions. We also calculate the pressure and compare it with the Carnahan-starling results, and finally we obtained the surface tension at liquid-solid interface and compared it with the results of Monte Carlo simulation.
Directory of Open Access Journals (Sweden)
Leila Moradi
2014-06-01
Full Text Available Chemically attachment of Schiff base complexes on multiwalled carbon nanotubes (MWCNTs surfaces through a convenient and simple method was studied. In the first step of this method, we present a new method for preparation of aminated MWCNTs in order to attachment of (new chlorinated salen Schiff bases. Amination of multiwalled carbon nanotubes performed under microwave (MW irradiation through a one pot two step reaction. The chemically attachment of salen Schiff bases on functionalized MWCNTs (salen@MWCNTs performed under a facile simple nucleophilic substitution reaction and complexation of attached salen Schiff bases (salen complex@MWCNTs in last step, have been occurred with reaction of transition metal salts and salen@MWCNTs. The obtained products were characterized in detail, using FTIR, XRD, UV-Vis absorption, SEM and EDX methods.
Brodsky, Yu. I.
2015-01-01
The work is devoted to the application of Bourbaki's structure theory to substantiate the synthesis of simulation models of complex multicomponent systems, where every component may be a complex system itself. An application of the Bourbaki's structure theory offers a new approach to the design and computer implementation of simulation models of complex multicomponent systems—model synthesis and model-oriented programming. It differs from the traditional object-oriented approach. The central concept of this new approach and at the same time, the basic building block for the construction of more complex structures is the concept of models-components. A model-component endowed with a more complicated structure than, for example, the object in the object-oriented analysis. This structure provides to the model-component an independent behavior-the ability of standard responds to standard requests of its internal and external environment. At the same time, the computer implementation of model-component's behavior is invariant under the integration of models-components into complexes. This fact allows one firstly to construct fractal models of any complexity, and secondly to implement a computational process of such constructions uniformly-by a single universal program. In addition, the proposed paradigm allows one to exclude imperative programming and to generate computer code with a high degree of parallelism.
Padhi, S.; Tokunaga, T.
2017-12-01
Adsorption of fluoride (F) on soil can control the mobility of F and subsequent contamination of groundwater. Hence, accurate evaluation of adsorption equilibrium is a prerequisite for understanding transport and fate of F in the subsurface. While there have been studies for the adsorption behavior of F with respect to single mineral constituents based on surface complexation models (SCM), F adsorption to natural soil in the presence of complexing agents needs much investigation. We evaluated the adsorption processes of F on a natural granitic soil from Tsukuba, Japan, as a function of initial F concentration, ionic strength, and initial pH. A SCM was developed to model F adsorption behavior. Four possible surface complexation reactions were postulated with and without including dissolved aluminum (Al) and Al-F complex sorption. Decrease in F adsorption with the increase in initial pH was observed in between the initial pH range of 4 to 9, and a decrease in the rate of the reduction of adsorbed F with respect to the increase in the initial pH was observed in the initial pH range of 5 to 7. Ionic strength variation in the range of 0 to 100mM had insignificant effect on F removal. Changes in solution pH were observed by comparing the solution before and after F adsorption experiments. At acidic pH, the solution pH increased, whereas at alkaline pH, the solution pH decreased after equilibrium. The SCM including dissolved Al and the adsorption of Al-F complex can simulate the experimental results quite successfully. Also, including dissolved Al and the adsorption of Al-F complex to the model explained the change in solution pH after F adsorption.
Bertolino, María Candelaria; Granados, Alejandro Manuel
2016-10-01
In this work we present a detailed study of classic reactions such as ;click reaction; and nucleophilic substitution reaction but on glass solid surface (slides). We used different reactive center of a dialkynylalcoxy Fischer carbene complex of tungsten(0) to be anchored to modified glass surface with amine, to obtain aminocarbene, and azide terminal groups. These cycloaddition reaction showed regioselectivity to internal triple bond of dialkynyl Fischer carbene complex without Cu(I) as catalyst. Anyway the carbene anchored was able to act as a reducing agent to produce in situ very stable gold nanoparticles fixed on surface. We showed the characterization of modified glasses by contact angle measurements and XPS. Synthesized nanoparticles were characterized by SEM, XPS, EDS and UV-vis. The modified glasses showed an important enhancement Raman-SERS. This simple, fast and robust method to create a polifunctional and hybrid surfaces can be valuable in a wide range of applications such as Raman-SERS substrates and other optical fields.
Progress in approximation theory and applicable complex analysis in memory of Q.I. Rahman
Mohapatra, Ram; Qazi, Mohammed; Schmeisser, Gerhard
2017-01-01
Current and historical research methods in approximation theory are presented in this book beginning with the 1800s and following the evolution of approximation theory via the refinement and extension of classical methods and ending with recent techniques and methodologies. Graduate students, postdocs, and researchers in mathematics, specifically those working in the theory of functions, approximation theory, geometric function theory, and optimization will find new insights as well as a guide to advanced topics. The chapters in this book are grouped into four themes; the first, polynomials (Chapters 1 –8), includes inequalities for polynomials and rational functions, orthogonal polynomials, and location of zeros. The second, inequalities and extremal problems are discussed in Chapters 9 –13. The third, approximation of functions, involves the approximants being polynomials, rational functions, and other types of functions and are covered in Chapters 14 –19. The last theme, quadrature, cubature and appl...
Bussotti, Paolo
2015-01-01
This book presents new insights into Leibniz’s research on planetary theory and his system of pre-established harmony. Although some aspects of this theory have been explored in the literature, others are less well known. In particular, the book offers new contributions on the connection between the planetary theory and the theory of gravitation. It also provides an in-depth discussion of Kepler’s influence on Leibniz’s planetary theory and, more generally, on Leibniz’s concept of pre-established harmony. Three initial chapters presenting the mathematical and physical details of Leibniz’s works provide a frame of reference. The book then goes on to discuss research on Leibniz’s conception of gravity and the connection between Leibniz and Kepler. .
Directory of Open Access Journals (Sweden)
Saeed Farzin
2017-06-01
Full Text Available Introduction: Dynamic nature of hydrological phenomena and the limited availability of appropriate mathematical tools caused the most previous studies in this field led to the random and the probabilistic approach. So selection the best model for evaluation of these phenomena is essential and complex. Nowadays different models are used for evaluation and prediction of hydrological phenomena. Damle and Yalcin (2007 estimated river runoff by chaos theory. khatibi et al (2012 used artificial neural network and gene expression programming to predict relative humidity. Zounemat and Kisi (2015 evaluated chaotic behavior of marine wind-wave system of Caspian sea. One of the important hydrological phenomena is evaporation, especially in lakes. The investigation of deterministic and stochastic behavior of water evaporation values in the lakes in order to select the best simulation approach and capable of prediction is an important and controversial issue that has been studied in this research. Materials and Methods: In the present paper, monthly values of evaporation are evaluated by two different models. Chaos theory and artificial neural network are used for the analysis of stochastic behavior and capability of prediction of water evaporation values in the Urmia Lake in northwestern of Iran. In recent years, Urmia Lake has unpleasant changes and drop in water level due to inappropriate management and climate change. One of the important factors related to climate change, is evaporation. Urmia Lake is a salt lake, and because of existence valuable ecology, environmental issues and maintenance of ecosystems of this lake are very important. So evaporation can have an essential role in the salinity, environmental and the hydrological cycle of the lake. In this regard, according to the ability of chaos theory and artificial neural network to analysis nonlinear dynamic systems; monthly values of evaporation, during a 40-year period, are investigated and then
Bruni, P.; Fino, V.; Pisani, M.; Tosi, G.; Stipa, P.; Ferraris, P.; Francescangeli, O.
2009-02-01
The new lipid 1,2- O-dioleyl-3- O-{2-[(12-crown-4)-methoxy]-ethyl}- sn-glycerol, 12C4L, has been synthesized. This molecule can coordinate different cations that should make the corresponding liposome a good candidate as vector of genetic material for possible applications in gene therapy. An important feature of the molecule is the possibility to modulate the net surface charge of their complexes with metal cations, which is important to provide efficient DNA transfections. The molecule and its complexes with some metal cations (Mg 2+, Ca 2+, Mn 2+) have been characterized by FT-IR spectroscopy and band attributions confirmed by Density Functional Theory calculations. The net surface charge has been determined by Z potential determinations.
International Nuclear Information System (INIS)
Mirigian, Stephen; Schweizer, Kenneth S.
2015-01-01
We have constructed a quantitative, force level, statistical mechanical theory for how confinement in free standing thin films introduces a spatial mobility gradient of the alpha relaxation time as a function of temperature, film thickness, and location in the film. The crucial idea is that relaxation speeds up due to the reduction of both near-surface barriers associated with the loss of neighbors in the local cage and the spatial cutoff and dynamical softening near the vapor interface of the spatially longer range collective elasticity cost for large amplitude hopping. These two effects are fundamentally coupled. Quantitative predictions are made for how an apparent glass temperature depends on the film thickness and experimental probe technique, the emergence of a two-step decay and mobile layers in time domain measurements, signatures of confinement in frequency-domain dielectric loss experiments, the dependence of film-averaged relaxation times and dynamic fragility on temperature and film thickness, surface diffusion, and the relationship between kinetic experiments and pseudo-thermodynamic measurements such as ellipsometry
Energy Technology Data Exchange (ETDEWEB)
Mirigian, Stephen, E-mail: kschweiz@illinois.edu, E-mail: smirigian@gmail.com; Schweizer, Kenneth S., E-mail: kschweiz@illinois.edu, E-mail: smirigian@gmail.com [Departments of Materials Science and Chemistry, University of Illinois, Urbana, Illinois 61801 (United States)
2015-12-28
We have constructed a quantitative, force level, statistical mechanical theory for how confinement in free standing thin films introduces a spatial mobility gradient of the alpha relaxation time as a function of temperature, film thickness, and location in the film. The crucial idea is that relaxation speeds up due to the reduction of both near-surface barriers associated with the loss of neighbors in the local cage and the spatial cutoff and dynamical softening near the vapor interface of the spatially longer range collective elasticity cost for large amplitude hopping. These two effects are fundamentally coupled. Quantitative predictions are made for how an apparent glass temperature depends on the film thickness and experimental probe technique, the emergence of a two-step decay and mobile layers in time domain measurements, signatures of confinement in frequency-domain dielectric loss experiments, the dependence of film-averaged relaxation times and dynamic fragility on temperature and film thickness, surface diffusion, and the relationship between kinetic experiments and pseudo-thermodynamic measurements such as ellipsometry.
Ma, Xin; Zhou, Mowei; Wysocki, Vicki H.
2014-03-01
Ion mobility (IM) and tandem mass spectrometry (MS/MS) coupled with native MS are useful for studying noncovalent protein complexes. Collision induced dissociation (CID) is the most common MS/MS dissociation method. However, some protein complexes, including glycogen phosphorylase B kinase (PHB) and L-glutamate dehydrogenase (GDH) examined in this study, are resistant to dissociation by CID at the maximum collision energy available in the instrument. Surface induced dissociation (SID) was applied to dissociate the two refractory protein complexes. Different charge state precursor ions of the two complexes were examined by CID and SID. The PHB dimer was successfully dissociated to monomers and the GDH hexamer formed trimeric subcomplexes that are informative of its quaternary structure. The unfolding of the precursor and the percentages of the distinct products suggest that the dissociation pathways vary for different charge states. The precursors at lower charge states (+21 for PHB dimer and +27 for GDH hexamer) produce a higher percentage of folded fragments and dissociate more symmetrically than the precusors at higher charge states (+29 for PHB dimer and +39 for GDH hexamer). The precursors at lower charge state may be more native-like than the higher charge state because a higher percentage of folded fragments and a lower percentage of highly charged unfolded fragments are detected. The combination of SID and charge reduction is shown to be a powerful tool for quaternary structure analysis of refractory noncovalent protein complexes, as illustrated by the data for PHB dimer and GDH hexamer.
Arnold, Rachelle M; Patton, Derek L; Popik, Vladimir V; Locklin, Jason
2014-10-21
Advances in key 21st century technologies such as biosensors, biomedical implants, and organic light-emitting diodes rely heavily on our ability to imagine, design, and understand spatially complex interfaces. Polymer-based thin films provide many advantages in this regard, but the direct synthesis of polymers with incompatible functional groups is extremely difficult. Using postpolymerization modification in conjunction with click chemistry can circumvent this limitation and result in multicomponent surfaces that are otherwise unattainable. The two methods used to form polymer thin films include physisorption and chemisorption. Physisorbed polymers suffer from instability because of the weak intermolecular forces between the film and the substrate, which can lead to dewetting, delamination, desorption, or displacement. Covalent immobilization of polymers to surfaces through either a "grafting to" or "grafting from" approach provides thin films that are more robust and less prone to degradation. The grafting to technique consists of adsorbing a polymer containing at least one reactive group along the backbone to form a covalent bond with a complementary surface functionality. Grafting from involves polymerization directly from the surface, in which the polymer chains deviate from their native conformation in solution and stretch away from the surface because of the high density of chains. Postpolymerization modification (PPM) is a strategy used by our groups over the past several years to immobilize two or more different chemical functionalities onto substrates that contain covalently grafted polymer films. PPM exploits monomers with reactive pendant groups that are stable under the polymerization conditions but are readily modified via covalent attachment of the desired functionality. "Click-like" reactions are the most common type of reactions used for PPM because they are orthogonal, high-yielding, and rapid. Some of these reactions include thiol-based additions
Dyke, John; Levason, William; Light, Mark E; Pugh, David; Reid, Gillian; Bhakhoa, Hanusha; Ramasami, Ponnadurai; Rhyman, Lydia
2015-08-21
The Group 1 complexes, [M(Me6[18]aneN6)][BAr(F)] (M = Li-Cs; Me6[18]aneN6 = 1,4,7,10,13,16-hexamethyl-1,4,7,10,13,16-hexaazacyclooctadecane; BAr(F) = tetrakis{3,5-bis(trifluoromethyl)-phenyl}borate), are obtained in high yield by reaction of the macrocycle with M[BAr(F)] in anhydrous CH2Cl2 solution, and characterised spectroscopically ((1)H, (13)C{(1)H}, (7)Li, (23)Na, and (133)Cs NMR), by microanalysis and, for M = Li, K, and Rb, by single crystal X-ray analysis. The structures show N6-coordination to the metal ion; the small ionic radius for Li(+) leads to a puckered conformation. In contrast, the K(+) ion fits well into the N6 plane, with the [BAr(F)](-) anions above and below, leading to two K(+) species in the asymmetric unit (a hexagonal planar [K(Me6[18]aneN6)](+) cation and a '[K(Me6[18]aneN6)(κ(1)-BAr(F))2](-) anion', with long axial KF interactions). The Rb(+) ion sits above the N6 plane, with two long axial RbF interactions in one cation and two long, mutually cis RbF interactions in the other. The unusual sandwich cations, [M(Me3tacn)2](+) (M = Na, K; distorted octahedral, N6 donor set) and half-sandwich cations [Li(Me3tacn)(thf)](+) (distorted tetrahedron, N3O donor set), [Li(Me4cyclen)(OH2)](+), and [Na(Me4cyclen)(thf)](+) (both distorted square pyramids with N4O donor sets) were also prepared (Me3tacn = 1,4,7-trimethyl-1,4,7-triazacyclononane, Me4cyclen = 1,4,7,10-tetramethyl-1,4,7,10-tetraazacyclododecane). Density functional theory (DFT) calculations, using the BP86 and B3LYP functionals, show that the accessibility of the [M(Me3tacn)2](+) sandwich cations depends strongly on the M(+) ionic radius, such that it is sufficiently large to avoid steric clashing between the Me groups of the two rings, and small enough to avoid very acute N-M-N chelate angles. The calculations also show that coordination to the Group 1 cation involves significant donation of electron density from the p-orbitals on the N atoms of the macrocycle, rather than purely
DEFF Research Database (Denmark)
Vojvodic, Aleksandra; Ruberto, C.; Lundqvist, Bengt
2010-01-01
This study explores atomic and molecular adsorption on a number of early transition-metal carbides (TMCs) in NaCl structure by means of density-functional theory calculations. The investigated substrates are the TM-terminated TMC(111) surfaces, of interest because of the presence of different types......, surface relaxations, Bader charges, and surface-localized densities of states (DOSs). Detailed comparisons between surface and bulk DOSs reveal the existence of transition-metal localized SRs (TMSRs) in the pseudogap and of several C-localized SRs (CSRs) in the upper valence band on all considered TMC(111......) surfaces. The spatial extent and the dangling bond nature of these SRs are supported by real-space analyses of the calculated Kohn-Sham wavefunctions. Then, atomic and molecular adsorption energies, geometries, and charge transfers are presented. An analysis of the adsorbate-induced changes in surface DOSs...
Directory of Open Access Journals (Sweden)
A. M. Abd-Alla
2013-01-01
Full Text Available Estimation is done to investigate the gravitational and rotational parameters effects on surface waves in fibre-reinforced thermoelastic media. The theory of generalized surface waves has been firstly developed and then it has been employed to investigate particular cases of waves, namely, Stoneley waves, Rayleigh waves, and Love waves. The analytical expressions for surface waves velocity and attenuation coefficient are obtained in the physical domain by using the harmonic vibrations and four thermoelastic theories. The wave velocity equations have been obtained in different cases. The numerical results are given for equation of coupled thermoelastic theory (C-T, Lord-Shulman theory (L-S, Green-Lindsay theory (G-L, and the linearized (G-N theory of type II. Comparison was made with the results obtained in the presence and absence of gravity, rotation, and parameters for fibre-reinforced of the material media. The results obtained are displayed by graphs to clear the phenomena physical meaning. The results indicate that the effect of gravity, rotation, relaxation times, and parameters of fibre-reinforced of the material medium is very pronounced.
Irfan, Ahmad; Abbas, Ghulam
2018-03-01
The synthesis and characterisation of mononuclear Fe complexes were carried out by using bipyridine (Compound 1) at ambient conditions. Additionally, three more derivatives were designed by substituting the central Fe metal with Zn, Cr, and Ru (Compound 2, Compound 3, and Compound 4), respectively. The ground state geometry calculations were carried out by using density functional theory (DFT) at B3LYP/6-31G** (LANL2DZ) level of theory. We shed light on the frontier molecular orbitals, electronic properties, photovoltaic parameters, and structure-property relationship. The open-circuit voltage is a promising parameter that considerably affects the photovoltaic performance; thus, we have estimated its value by considering the complexes as donors whereas TiO2 and/or Si were used as acceptors. The solar cell performance behaviour was also studied by shedding light on the band alignment and energy level offset.
2007-03-01
optimal decision. Game theory has been used in many facets since John von Neuman and Oskar Morgenstern published Theory of Games and Economic Behavior in...be a 25 x 25 matrix of payoffs. 2.3 Game Theory in Literature Nash [15] builds on Von Neumann and Morgensterns ’ [28] theory of two-person zero-sum...and Morgenstern , O. (1944). Theory of Games and Economic Behavior. Science Editions, 3, 1964. 29. Whittaker, G. M. (2000). Asymmetric Wargaming: Toward
Spectroscopic evidence for ternary surface complexes in the lead(II)-malonic acid-hematite system
Lenhart, J.J.; Bargar, J.R.; Davis, J.A.
2001-01-01
Using extended X-ray absorption fine structure (EXAFS) and attenuated total reflectance Fourier-transform infrared (ATR-FTIR) measurements, we examined the sorption of Pb(II) to hematite in the presence of malonic acid. Pb LIII-edge EXAFS measurements performed in the presence of malonate indicate the presence of both Fe and C neighbors, suggesting that a major fraction of surface-bound malonate is bonded to adsorbed Pb(II). In the absence of Pb(II), ATR-FTIR measurements of sorbed malonate suggest the formation of more than one malonate surface complex. The dissimilarity of the IR spectrum of malonate sorbed on hematite to those for aqueous malonate suggest at least one of the sorbed malonate species is directly coordinated to surface Fe atoms in an inner-sphere mode. In the presence of Pb, little change is seen in the IR spectrum for sorbed malonate, indicating that geometry of malonate as it coordinates to sorbed Pb(II) adions is similar to the geometry of malonate as it coordinates to Fe in the hematite surface. Fits of the raw EXAFS spectra collected from pH 4 to pH 8 result in average Pb-C distances of 2.98 to 3.14 A??, suggesting the presence of both four- and six-membered Pb-malonate rings. The IR results are consistent with this interpretation. Thus, our results suggest that malonate binds to sorbed Pb(II) adions, forming ternary metal-bridging surface complexes. ?? 2001 Academic Press.
Procopio, Lorenzo M.; Rozema, Lee A.; Dakić, Borivoje; Walther, Philip
2016-01-01
In his recent article [arXiv:1604.04950], Adler questions the usefulness of the bound found in our experimental search for genuine effects of hyper-complex quantum mechanics [arXiv:1602.01624]. Our experiment was performed using a black-box (instrumentalist) approach to generalized probabilistic theories; therefore, it does not assume a priori any particular underlying mechanism. From that point of view our experimental results do indeed place meaningful bounds on possible effects of "post-qu...
DEFF Research Database (Denmark)
Andersson, Martin Peter; Hem, Caroline Piper; Schultz, Logan Nicholas
2014-01-01
broadening from macroscopic dielectric effects. We detect water adsorbed on the high surface area synthetic calcite, which permits observation of the chemistry of thin liquid films on calcite using transmission infrared spectroscopy. The combination of infrared spectroscopy and density functional theory also...... asymmetric for the coccoliths and the synthetic calcite prepared using the carbonation method. It can be very well fitted by two peaks: a narrow Lorenzian at lower frequency and a broader Gaussian at higher frequency. These two samples both have a high specific surface area. Density functional theory...
International Nuclear Information System (INIS)
Rama Mohana Rao, D.; Rawat, Neetika; Manna, D.; Sawant, R.M.; Ghanty, T.K.; Tomar, B.S.
2013-01-01
Highlights: ► The thermodynamic parameters have been determined for the first time. ► The Th-picolinate complexation was exothermic in nature. ► The complexation of Th(IV) with the other two isomers was endothermic process. ► Isonicotinate forms stronger complexes than nicotinate with Th(IV). ► The theoretically calculated values are in line with the experimental results. -- Abstract: Complexation of thorium with pyridine monocarboxylates namely picolinic acid (pyridine-2-carboxylic acid), nicotinic acid (pyridine-3-carboxylic acid) and isonicotinic acid (pyridine-4-carboxylic acid) has been studied by potentiometry and calorimetry to determine the thermodynamic parameters (log K, ΔG, ΔH and ΔS) of complexation. All the studies were carried out at 1.0 M ionic strength adjusted by NaClO 4 and at a temperature of 298 K. The detailed analysis of potentiometric data by Hyperquad confirmed the formation of four complexes, ML i (i = 1–4) in case of picolinate but only one complex (ML) in case of nicotinate and isonicotinate. The stepwise formation constant for ML complex (log K ML ) of thorium-picolinate is higher than those of thorium-nicotinate and thorium-isonicotinate complexes. Further the changes in enthalpy during formation of thorium-picolinate complexes are negative whereas the same for the complexes of thorium with the other two isomers was positive. This difference in the complexation process is attributed to chelate formation in case of thorium-picolinate complexes in which the thorium ion is bound to the picolinate through both the nitrogen in the pyridyl ring and one of the carboxylate oxygen atoms. The complexation process of thorium-nicotinate and thorium-isonicotinate are found to be endothermic in nature and are entropy driven confirming the similar binding nature as in simple carboxylate complexes of thorium. The complexation energies, bond lengths and charges on each atom in the complexes of various possible geometries were calculated
Walloth, Christian
2016-01-01
This book presents a theory as well as methods to understand and to purposively influence complex systems. It suggests a theory of complex systems as nested systems, i. e. systems that enclose other systems and that are simultaneously enclosed by even other systems. According to the theory presented, each enclosing system emerges through time from the generative activities of the systems they enclose. Systems are nested and often emerge unplanned, and every system of high dynamics is enclosed by a system of slower dynamics. An understanding of systems with faster dynamics, which are always guided by systems of slower dynamics, opens up not only new ways to understanding systems, but also to effectively influence them. The aim and subject of this book is to lay out these thoughts and explain their relevance to the purposive development of complex systems, which are exemplified in case studies from an urban system. The interested reader, who is not required to be familiar with system-theoretical concepts or wit...
Energy Technology Data Exchange (ETDEWEB)
Buecking, N.
2007-11-05
In this work a new theoretical formalism is introduced in order to simulate the phononinduced relaxation of a non-equilibrium distribution to equilibrium at a semiconductor surface numerically. The non-equilibrium distribution is effected by an optical excitation. The approach in this thesis is to link two conventional, but approved methods to a new, more global description: while semiconductor surfaces can be investigated accurately by density-functional theory, the dynamical processes in semiconductor heterostructures are successfully described by density matrix theory. In this work, the parameters for density-matrix theory are determined from the results of density-functional calculations. This work is organized in two parts. In Part I, the general fundamentals of the theory are elaborated, covering the fundamentals of canonical quantizations as well as the theory of density-functional and density-matrix theory in 2{sup nd} order Born approximation. While the formalism of density functional theory for structure investigation has been established for a long time and many different codes exist, the requirements for density matrix formalism concerning the geometry and the number of implemented bands exceed the usual possibilities of the existing code in this field. A special attention is therefore attributed to the development of extensions to existing formulations of this theory, where geometrical and fundamental symmetries of the structure and the equations are used. In Part II, the newly developed formalism is applied to a silicon (001)surface in a 2 x 1 reconstruction. As first step, density-functional calculations using the LDA functional are completed, from which the Kohn-Sham-wave functions and eigenvalues are used to calculate interaction matrix elements for the electron-phonon-coupling an the optical excitation. These matrix elements are determined for the optical transitions from valence to conduction bands and for electron-phonon processes inside the
Wolthers, M.; Charlet, L.; Van Cappellen, P.
2008-01-01
The Charge Distribution MUltiSite Ion Complexation or CD–MUSIC modeling approach is used to describe the chemical structure of carbonate mineralaqueous solution interfaces. The new model extends existing surface complexation models of carbonate minerals, by including atomic scale information on
Stability of nano-metric colloidal dispersions of titanium: effect of surface complexation
International Nuclear Information System (INIS)
Peyre, Veronique
1996-01-01
This research thesis reports the study of the adsorption of small organic molecules at the surface of nano-particles of mineral oxides (zirconia), and of its effects on the stability of the colloidal dispersion. Adsorption has been quantified by adsorption isotherms and surface titrations. Processes and mechanisms are thus discussed with respect to pH. The influence of various protecting molecules (acetyl acetone, but also acetic acid, citric acid and diethanolamine) has been studied, and notably highlighted the role of the outer face of the complexing agent in the assessment of reactions between particles which govern the compression and re-dispersability properties of protected dispersions. This study is performed by osmotic pressure measurements and by X-ray diffusion at small angles, completed by statistical mechanics calculations [fr
Ultrasonic detection technology based on joint robot on composite component with complex surface
Energy Technology Data Exchange (ETDEWEB)
Hao, Juan; Xu, Chunguang; Zhang, Lan [School of Mechanical Engineering, Beijing Institute of Technology, Beijing (China)
2014-02-18
Some components have complex surface, such as the airplane wing and the shell of a pressure vessel etc. The quality of these components determines the reliability and safety of related equipment. Ultrasonic nondestructive detection is one of the main methods used for testing material defects at present. In order to improve the testing precision, the acoustic axis of the ultrasonic transducer should be consistent with the normal direction of the measured points. When we use joint robots, automatic ultrasonic scan along the component surface normal direction can be realized by motion trajectory planning and coordinate transformation etc. In order to express the defects accurately and truly, the robot position and the signal of the ultrasonic transducer should be synchronized.
Formal Killing fields for minimal Lagrangian surfaces in complex space forms
Wang, Joe S.
2017-04-01
The differential system for minimal Lagrangian surfaces in a 2C-dimensional, non-flat, complex space form is an elliptic integrable system defined on the Grassmann bundle of oriented Lagrangian 2-planes. This is a 6-symmetric space associated with the Lie group SL(3 , C) , and the minimal Lagrangian surfaces arise as the primitive maps. Utilizing this property, we derive the inductive differential algebraic formulas for a pair of the formal loop algebra sl(3 , C) [ [ λ ] ] -valued canonical formal Killing fields. For applications, (a) we give a complete classification of the (pseudo) Jacobi fields for the minimal Lagrangian system, (b) we obtain an infinite sequence of conservation laws from the components of the canonical formal Killing fields.
Surface Complexation Modeling in Variable Charge Soils: Prediction of Cadmium Adsorption
Directory of Open Access Journals (Sweden)
Giuliano Marchi
2015-10-01
Full Text Available ABSTRACT Intrinsic equilibrium constants for 22 representative Brazilian Oxisols were estimated from a cadmium adsorption experiment. Equilibrium constants were fitted to two surface complexation models: diffuse layer and constant capacitance. Intrinsic equilibrium constants were optimized by FITEQL and by hand calculation using Visual MINTEQ in sweep mode, and Excel spreadsheets. Data from both models were incorporated into Visual MINTEQ. Constants estimated by FITEQL and incorporated in Visual MINTEQ software failed to predict observed data accurately. However, FITEQL raw output data rendered good results when predicted values were directly compared with observed values, instead of incorporating the estimated constants into Visual MINTEQ. Intrinsic equilibrium constants optimized by hand calculation and incorporated in Visual MINTEQ reliably predicted Cd adsorption reactions on soil surfaces under changing environmental conditions.
Kulik, Dmitrii A.; Aja, Stephen U.; Sinitsyn, Vasilii A.; Wood, Scott A.
2000-01-01
The surface reactivity and sorption of Nd and Eu onto K +-saturated Marblehead illite at 25°C, measured in aqueous 0.01, 0.1, and 1.0 M KCl solutions, were interpreted with a multi-site-surface complexation model. Model potentiometric titration and sorption curves (computed using the Gibbs free energy minimization code, Selektor-A) resolve into reactions on variable-charge amphoteric sites on edge surfaces and on permanent-charge siloxane surfaces (φ x). Standard partial molal Gibbs free energy of formation from elements (g 2980) for surface complexes were derived from oxide (SiO 2,am and γ-Al 2O 3) surface deprotonation KA10, KA20 and electrolyte adsorption constants KCl0, KNa0. Because surface complexation reactions on siloxane basal surfaces are negligible in 1 M KCl, models of surface charge and adsorption edges of Nd and Eu presumed that C 1 is equal to 1.6 Fm -2 for amphoteric site types, and a maximum site density of 1.2 ± 0.2 sites nm -2 for the outer-sphere species, (Al>OH 2+Cl -). To obtain values of g 2980 for exchangeable cations and charged X ˜REE complexes, ion exchange sites were assumed to be fully deprotonated in 1.0 M KCl solutions (pH > 2.7). Proton release and REE 3+ uptake on ion exchange sites were then simulated (pH 4.0) from initial values of 20 to 48%. The application of Gibbs free energy minimization to sorption processes is innovative in that simultaneous treatment of surface complexation reactions and minerals stability is feasible in any system without introducing mass-balance constraints particular to surface species.
Towards a theory of chaos explained as travel on Riemann surfaces
Energy Technology Data Exchange (ETDEWEB)
Calogero, F; Santini, P M [Dipartimento di Fisica, Universita di Roma ' La Sapienza' , Roma (Italy); Gomez-Ullate, D [Departamento de Fisica Teorica II, Universidad Complutense, Madrid (Spain); Sommacal, M [Dipartimento di Matematica e Informatica, Universita degli Studi di Perugia, Perugia (Italy)], E-mail: francesco.calogero@roma1.infn.it, E-mail: david.gomez-ullate@fis.ucm.es, E-mail: paolo.santini@roma1.infn.it, E-mail: matteo.sommacal@pg.infn.it
2009-01-09
We investigate the dynamics defined by a set of three coupled first-order ODEs. It is shown that the system can be reduced to quadratures which can be expressed in terms of elementary functions. Despite the integrable character of the model, the general solution is a multiple-valued function of time (considered as a complex variable), and we investigate the position and nature of its branch points. In the semi-symmetric case (g{sub 1} = g{sub 2} {ne} g{sub 3}), for rational values of the coupling constants the system is isochronous and explicit formulae for the period of the solutions can be given. For irrational values, the motions are confined but feature aperiodic motion with sensitive dependence on initial conditions. The system shows a rich dynamical behaviour that can be understood in quantitative detail since a global description of the Riemann surface associated with the solutions can be achieved. The details of the description of the Riemann surface are postponed to a forthcoming publication. This toy model is meant to provide a paradigmatic first step towards understanding a certain novel kind of chaotic behaviour.
A Simple and Universal Aerosol Retrieval Algorithm for Landsat Series Images Over Complex Surfaces
Wei, Jing; Huang, Bo; Sun, Lin; Zhang, Zhaoyang; Wang, Lunche; Bilal, Muhammad
2017-12-01
Operational aerosol optical depth (AOD) products are available at coarse spatial resolutions from several to tens of kilometers. These resolutions limit the application of these products for monitoring atmospheric pollutants at the city level. Therefore, a simple, universal, and high-resolution (30 m) Landsat aerosol retrieval algorithm over complex urban surfaces is developed. The surface reflectance is estimated from a combination of top of atmosphere reflectance at short-wave infrared (2.22 μm) and Landsat 4-7 surface reflectance climate data records over densely vegetated areas and bright areas. The aerosol type is determined using the historical aerosol optical properties derived from the local urban Aerosol Robotic Network (AERONET) site (Beijing). AERONET ground-based sun photometer AOD measurements from five sites located in urban and rural areas are obtained to validate the AOD retrievals. Terra MODerate resolution Imaging Spectrometer Collection (C) 6 AOD products (MOD04) including the dark target (DT), the deep blue (DB), and the combined DT and DB (DT&DB) retrievals at 10 km spatial resolution are obtained for comparison purposes. Validation results show that the Landsat AOD retrievals at a 30 m resolution are well correlated with the AERONET AOD measurements (R2 = 0.932) and that approximately 77.46% of the retrievals fall within the expected error with a low mean absolute error of 0.090 and a root-mean-square error of 0.126. Comparison results show that Landsat AOD retrievals are overall better and less biased than MOD04 AOD products, indicating that the new algorithm is robust and performs well in AOD retrieval over complex surfaces. The new algorithm can provide continuous and detailed spatial distributions of AOD during both low and high aerosol loadings.
Song, J.; Zeng, Y.; Biswal, S. L.; Hirasaki, G. J.
2017-12-01
We presents zeta potential measurements and surface complexation modeling (SCM) of synthetic calcite in various conditions. The systematic zeta potential measurement and the proposed SCM provide insight into the role of four potential determining cations (Mg2+, SO42- , Ca2+ and CO32-) and CO2 partial pressure in calcite surface charge formation and facilitate the revealing of calcite wettability alteration induced by brines with designed ionic composition ("smart water"). Brines with varying potential determining ions (PDI) concentration in two different CO2 partial pressure (PCO2) are investigated in experiments. Then, a double layer SCM is developed to model the zeta potential measurements. Moreover, we propose a definition for contribution of charged surface species and quantitatively analyze the variation of charged species contribution when changing brine composition. After showing our model can accurately predict calcite zeta potential in brines containing mixed PDIs, we apply it to predict zeta potential in ultra-low and pressurized CO2 environments for potential applications in carbonate enhanced oil recovery including miscible CO2 flooding and CO2 sequestration in carbonate reservoirs. Model prediction reveals that pure calcite surface will be positively charged in all investigated brines in pressurized CO2 environment (>1atm). Moreover, the sensitivity of calcite zeta potential to CO2 partial pressure in the various brine is found to be in the sequence of Na2CO3 > Na2SO4 > NaCl > MgCl2 > CaCl2 (Ionic strength=0.1M).
Effects of complex terrain on net surface longwave radiation in China
Zhu, Xiaochen; Qiu, Xinfa; Zeng, Yan; Ren, Wei; Tao, Bo; Gao, Jiaqi; Liu, Haobo; Tan, Yunjuan
2017-09-01
Net surface longwave radiation (NSLR) is one of key meteorological factors and is strongly influenced by cloud cover, surface temperature, humidity, and local micrometeorological conditions as well as terrain conditions. Realistically estimating NSLR is vitally important for understanding surface radiation balance and investigating micrometeorological factors of air pollution dispersion, especially in regions with complicated terrain. In this study, we proposed a distributed model for estimating NSLR by considering effects of complex local terrain conditions in China. Meteorological data (including mean temperature, relative humidity, and sunshine percentage) and observed NSLR data from 1993 to 2001 together with the digital elevation model data were used to parametrize the model and account for the effects of atmospheric factors and surface terrain factors according to the isotropic principle. The monthly NSLR during 1961-2000 was estimated at a spatial resolution of 1 km. Topographic analysis suggests that the distribution characteristics of NSLR with elevation or slope are consistent with those of field observations. In particular, the estimated NSLR is favorably comparable with site-level observations on the Tibetan Plateau (average relative error < 11%). Our results indicate that this model can describe microscale distribution features in mountainous areas in detail and that this improved approach can be used for NSLR spatial estimation in other regions with complicated terrain.
Moretti, Valter; Oppio, Marco
As earlier conjectured by several authors and much later established by Solèr (relying on partial results by Piron, Maeda-Maeda and other authors), from the lattice theory point of view, Quantum Mechanics may be formulated in real, complex or quaternionic Hilbert spaces only. Stückelberg provided some physical, but not mathematically rigorous, reasons for ruling out the real Hilbert space formulation, assuming that any formulation should encompass a statement of Heisenberg principle. Focusing on this issue from another — in our opinion, deeper — viewpoint, we argue that there is a general fundamental reason why elementary quantum systems are not described in real Hilbert spaces. It is their basic symmetry group. In the first part of the paper, we consider an elementary relativistic system within Wigner’s approach defined as a locally-faithful irreducible strongly-continuous unitary representation of the Poincaré group in a real Hilbert space. We prove that, if the squared-mass operator is non-negative, the system admits a natural, Poincaré invariant and unique up to sign, complex structure which commutes with the whole algebra of observables generated by the representation itself. This complex structure leads to a physically equivalent reformulation of the theory in a complex Hilbert space. Within this complex formulation, differently from what happens in the real one, all selfadjoint operators represent observables in accordance with Solèr’s thesis, and the standard quantum version of Noether theorem may be formulated. In the second part of this work, we focus on the physical hypotheses adopted to define a quantum elementary relativistic system relaxing them on the one hand, and making our model physically more general on the other hand. We use a physically more accurate notion of irreducibility regarding the algebra of observables only, we describe the symmetries in terms of automorphisms of the restricted lattice of elementary propositions of the
Surfacing the Iceberg of Leadership: A New Taxonomy of Leadership Concepts and Theories
Kaufman, EK; Cletzer, DA
2017-01-01
Leadership scholars have long sought to impose order on the numerous theories in leadership literature. While mid-level theories abound, no taxonomy exists to provide hierarchy and a mechanism for explaining how theories interrelate. This poster offers a new taxonomy for organizing leadership theories and concepts based on the metaphor of an iceberg. It invites leadership scholars to vet their own leadership courses and undergraduate leadership programs to determine the depth to which they ex...
Complex Dynamic Systems Theory and L2 pedagogy : Lessons to be learned
Verspoor, Marjolijn; Ortega, Lourdes; Han, ZhaoHong
2017-01-01
If we assume that language is a complex dynamic system, the learner is a complex dynamic system, and both the teaching and learning are dynamic processes—in which all relevant cognitive, physical and social systems interact over time—we must attend to all these systems and their relevant sub-systems
Before or beyond narrative? Towards a complex systems theory of contemporary films
Poulaki, M.
2011-01-01
This book puts into focus the tendency for increasingly complex forms of narration in post-1990s cinema. The author argues that, because of the fragmentation and nonlinearity that contemporary complex films display in all three narrative dimensions of time, causality and space it is not enough to
Unpacking the Complexity of Linear Equations from a Cognitive Load Theory Perspective
Ngu, Bing Hiong; Phan, Huy P.
2016-01-01
The degree of element interactivity determines the complexity and therefore the intrinsic cognitive load of linear equations. The unpacking of linear equations at the level of operational and relational lines allows the classification of linear equations in a hierarchical level of complexity. Mapping similar operational and relational lines across…
R.J.M. van Tulder (Rob); Keen, N. (Nienke)
2018-01-01
textabstractSystems change requires complex interventions. Cross-sector partnerships (CSPs) face the daunting task of addressing complex societal problems by aligning different backgrounds, values, ideas and resources. A major challenge for CSPs is how to link the type of partnership to the
Investigations of surface-tension effects due to small-scale complex boundaries
Feng, Jiansheng
these two different types of surfaces differed by about 50° ˜ 60°, with the low-adhesion surfaces at about 120° ˜ 130° and the high-adhesion surfaces at about 70° ˜ 80°. Characterizations of both the microscopic structures and macroscopic wetting properties of these product surfaces allowed us to pinpoint the structural features responsible for specific wetting properties. It is found that the advancing contact angle was mainly determined by the primary structures while the receding contact angle is largely affected by the side-wall slope of the secondary features. This study established a platform for further exploration of the structure aspects of surface wettability. In the third and final project (Chapter 4), we demonstrated a new type of microfluidic channel that enable asymmetric wicking of wetting fluids based on structure-induced direction-dependent surface-tension effect. By decorating the side-walls of open microfluidic channels with tilted fins, we were able to experimentally demonstrate preferential wicking behaviors of various IPA-water mixtures with a range of contact angles in these channels. A simplified 2D model was established to explain the wicking asymmetry, and a complete 3D model was developed to provide more accurate quantitative predictions. The design principles developed in this study provide an additional scheme for controlling the spreading of fluids. The research presented in this dissertation spreads out across a wide range of physical phenomena (wicking, wetting, and capillarity), and involves a number of computational and experimental techniques, yet all of these projects are intrinsically united under a common theme: we want to better understand how simple fluids respond to small-scale complex surface structures as manifestations of surface-tension effects. We hope our findings can serve as building blocks for a larger scale endeavor of scientific research and engineering development. After all, the pursue of knowledge is most
Qin, Wu; Li, Xin; Bian, Wen-Wen; Fan, Xiu-Juan; Qi, Jing-Yao
2010-02-01
There is increasing attention in the unique biological and medical properties of graphene, and it is expected that biomaterials incorporating graphene will be developed for the graphene-based drug delivery systems and biomedical devices. Despite the importance of biomolecules-graphene interactions, a detailed understanding of the adsorption mechanism and features of biomolecules onto the surfaces of graphene is lacking. To address this, we have performed density functional theory (DFT) and molecular dynamics (MD) methods exploring the adsorption geometries, adsorption energies, electronic band structures, adsorption isotherms, and adsorption dynamics of l-leucine (model biomolecule)/graphene composite system. DFT calculations confirmed the energetic stability of adsorption model and revealed that electronic structure of graphene can be controlled by the adsorption direction of l-leucine. MD simulations further investigate the potential energy and van der Waals energy for the interaction processes of l-leucine/graphene system at different temperatures and pressures. We find that the van der Waals interaction between the l-leucine and the graphene play a dominant role in the adsorption process under a certain range of temperature and pressure, and the l-leucine molecule could be adsorbed onto graphene spontaneously in aqueous solution.
Dynamics of two-phase interfaces and surface tensions: A density-functional theory perspective
Yatsyshin, Petr; Sibley, David N.; Duran-Olivencia, Miguel A.; Kalliadasis, Serafim
2016-11-01
Classical density functional theory (DFT) is a statistical mechanical framework for the description of fluids at the nanoscale, where the inhomogeneity of the fluid structure needs to be carefully accounted for. By expressing the grand free-energy of the fluid as a functional of the one-body density, DFT offers a theoretically consistent and computationally accessible way to obtain two-phase interfaces and respective interfacial tensions in a ternary solid-liquid-gas system. The dynamic version of DFT (DDFT) can be rigorously derived from the Smoluchowsky picture of the dynamics of colloidal particles in a solvent. It is generally agreed that DDFT can capture the diffusion-driven evolution of many soft-matter systems. In this context, we use DDFT to investigate the dynamic behaviour of two-phase interfaces in both equilibrium and dynamic wetting and discuss the possibility of defining a time-dependent surface tension, which still remains in debate. We acknowledge financial support from the European Research Council via Advanced Grant No. 247031 and from the Engineering and Physical Sciences Research Council of the UK via Grants No. EP/L027186 and EP/L020564.
Primes of the form x2+ny2 Fermat, class field theory, and complex multiplication
Cox, David A
2014-01-01
An exciting approach to the history and mathematics of number theory ". . . the author's style is totally lucid and very easy to read . . .the result is indeed a wonderful story." -Mathematical ReviewsWritten in a unique and accessible style for readers of varied mathematical backgrounds, the Second Edition of Primes of the Form p = x2+ ny2 details the history behind how Pierre de Fermat's work ultimately gave birth to quadratic reciprocity and the genus theory of quadratic forms. The book also illustrates how results of Euler and Gauss can be fully understood only in the context of class fi
Soriano, Miguel C.; Zunino, Luciano; Rosso, Osvaldo A.; Mirasso, Claudio R.
2010-04-01
The time evolution of the output of a semiconductor laser subject to optical feedback can exhibit high-dimensional chaotic fluctuations. In this contribution, our aim is to quantify the complexity of the chaotic time-trace generated by a semiconductor laser subject to delayed optical feedback. To that end, we discuss the properties of two recently introduced complexity measures based on information theory, namely the permutation entropy (PE) and the statistical complexity measure (SCM). The PE and SCM are defined as a functional of a symbolic probability distribution, evaluated using the Bandt-Pompe recipe to assign a probability distribution function to the time series generated by the chaotic system. In order to evaluate the performance of these novel complexity quantifiers, we compare them to a more standard chaos quantifier, namely the Kolmogorov-Sinai entropy. Here, we present numerical results showing that the statistical complexity and the permutation entropy, evaluated at the different time-scales involved in the chaotic regime of the laser subject to optical feedback, give valuable information about the complexity of the laser dynamics.
International Nuclear Information System (INIS)
Morgen, P.
1977-10-01
The physics and chemistry of ambient gases interacting with solid surfaces are discussed. The necessary theory and experimental techniques and apparatus used are described in detail. Results are presented for two semiconductor materials, silicon and zinc oxide. (W.D.L.)
Formation mechanism of a silane-PVA/PVAc complex film on a glass fiber surface.
Repovsky, Daniel; Jane, Eduard; Palszegi, Tibor; Slobodnik, Marek; Velic, Dusan
2013-10-21
Mechanical properties of glass fiber reinforced composite materials are affected by fiber sizing. A complex film formation, based on a silane film and PVA/PVAc (polyvinyl alcohol/polyvinyl acetate) microspheres on a glass fiber surface is determined at 1) the nanoscale by using atomic force microscopy (AFM), and 2) the macroscale by using the zeta potential. Silane groups strongly bind through the Si-O-Si bond to the glass surface, which provides the attachment mechanism as a coupling agent. The silane groups form islands, a homogeneous film, as well as empty sites. The average roughness of the silanized surface is 6.5 nm, whereas it is only 0.6 nm for the non-silanized surface. The silane film vertically penetrates in a honeycomb fashion from the glass surface through the deposited PVA/PVAc microspheres to form a hexagonal close pack structure. The silane film not only penetrates, but also deforms the PVA/PVAc microspheres from the spherical shape in a dispersion to a ellipsoidal shape on the surface with average dimensions of 300/600 nm. The surface area value Sa represents an area of PVA/PVAc microspheres that are not affected by the silane penetration. The areas are found to be 0.2, 0.08, and 0.03 μm(2) if the ellipsoid sizes are 320/570, 300/610, and 270/620 nm for silane concentrations of 0, 3.8, and 7.2 μg mL(-1), respectively. The silane film also moves PVA/PVAc microspheres in the process of complex film formation, from the low silane concentration areas to the complex film area providing enough silane groups to stabilize the structure. The values for the residual silane honeycomb structure heights (Ha ) are 6.5, 7, and 12 nm for silane concentrations of 3.8, 7.2, and 14.3 μg mL(-1), respectively. The pH-dependent zeta-potential results suggest a specific role of the silane groups with effects on the glass fiber surface and also on the PVA/PVAc microspheres. The non-silanized glass fiber surface and the silane film have similar zeta potentials ranging
Learner-Centred Pedagogy for Swim Coaching: A Complex Learning Theory-Informed Approach
Light, Richard
2014-01-01
While constructivist theories of learning have been widely drawn on to understand and explain learning in games when using game-based approaches their use to inform pedagogy beyond games is limited. In particular, there has been little interest in applying constructivist perspectives on learning to sports in which technique is of prime importance.…
Droop Control with an Adjustable Complex Virtual Impedance Loop based on Cloud Model Theory
DEFF Research Database (Denmark)
Li, Yan; Shuai, Zhikang; Xu, Qinming
2016-01-01
Droop control framework with an adjustable virtual impedance loop is proposed in this paper, which is based on the cloud model theory. The proposed virtual impedance loop includes two terms: a negative virtual resistor and an adjustable virtual inductance. The negative virtual resistor term...
Chaos and Complexities Theories. Superposition and Standardized Testing: Are We Coming or Going?
Erwin, Susan
2005-01-01
The purpose of this paper is to explore the possibility of using the principle of "superposition of states" (commonly illustrated by Schrodinger's Cat experiment) to understand the process of using standardized testing to measure a student's learning. Comparisons from literature, neuroscience, and Schema Theory will be used to expound upon the…
Activity Theory, Complexity and Sports Coaching: An Epistemology for a Discipline
Jones, Robyn L.; Edwards, Christian; Filho, I. A. Tuim Viotto
2016-01-01
The aim of this article is twofold. First, it is to advance the case for activity theory (AT) as a credible and alternative lens to view and research sports coaching. Second, it is to position this assertion within the wider debate about the epistemology of coaching. Following a framing introduction, a more comprehensive review of the development…
Cognitive Load Theory and Complex Learning: Recent Developments and Future Directions
Van Merriënboer, Jeroen; Sweller, J.
2007-01-01
Traditionally, Cognitive Load Theory (CLT) has focused on instructional methods to decrease extraneous cognitive load so that available cognitive resources can be fully devoted to learning. This article strengthens the cognitive base of CLT by linking cognitive processes to the processes used by