WorldWideScience

Sample records for ignores finite size

  1. Finite size scaling theory

    International Nuclear Information System (INIS)

    Rittenberg, V.

    1983-01-01

    Fischer's finite-size scaling describes the cross over from the singular behaviour of thermodynamic quantities at the critical point to the analytic behaviour of the finite system. Recent extensions of the method--transfer matrix technique, and the Hamiltonian formalism--are discussed in this paper. The method is presented, with equations deriving scaling function, critical temperature, and exponent v. As an application of the method, a 3-states Hamiltonian with Z 3 global symmetry is studied. Diagonalization of the Hamiltonian for finite chains allows one to estimate the critical exponents, and also to discover new phase transitions at lower temperatures. The critical points lambda, and indices v estimated for finite-scaling are given

  2. Quark bag coupling to finite size pions

    International Nuclear Information System (INIS)

    De Kam, J.; Pirner, H.J.

    1982-01-01

    A standard approximation in theories of quark bags coupled to a pion field is to treat the pion as an elementary field ignoring its substructure and finite size. A difficulty associated with these treatments in the lack of stability of the quark bag due to the rapid increase of the pion pressure on the bad as the bag size diminishes. We investigate the effects of the finite size of the qanti q pion on the pion quark bag coupling by means of a simple nonlocal pion quark interaction. With this amendment the pion pressure on the bag vanishes if the bag size goes to zero. No stability problems are encountered in this description. Furthermore, for extended pions, no longer a maximum is set to the bag parameter B. Therefore 'little bag' solutions may be found provided that B is large enough. We also discuss the possibility of a second minimum in the bag energy function. (orig.)

  3. Finite Size Scaling of Perceptron

    OpenAIRE

    Korutcheva, Elka; Tonchev, N.

    2000-01-01

    We study the first-order transition in the model of a simple perceptron with continuous weights and large, bit finite value of the inputs. Making the analogy with the usual finite-size physical systems, we calculate the shift and the rounding exponents near the transition point. In the case of a general perceptron with larger variety of inputs, the analysis only gives bounds for the exponents.

  4. Characterization of resonances using finite size effects

    International Nuclear Information System (INIS)

    Pozsgay, B.; Takacs, G.

    2006-01-01

    We develop methods to extract resonance widths from finite volume spectra of (1+1)-dimensional quantum field theories. Our two methods are based on Luscher's description of finite size corrections, and are dubbed the Breit-Wigner and the improved ''mini-Hamiltonian'' method, respectively. We establish a consistent framework for the finite volume description of sufficiently narrow resonances that takes into account the finite size corrections and mass shifts properly. Using predictions from form factor perturbation theory, we test the two methods against finite size data from truncated conformal space approach, and find excellent agreement which confirms both the theoretical framework and the numerical validity of the methods. Although our investigation is carried out in 1+1 dimensions, the extension to physical 3+1 space-time dimensions appears straightforward, given sufficiently accurate finite volume spectra

  5. Polyelectrolyte Bundles: Finite size at thermodynamic equilibrium?

    Science.gov (United States)

    Sayar, Mehmet

    2005-03-01

    Experimental observation of finite size aggregates formed by polyelectrolytes such as DNA and F-actin, as well as synthetic polymers like poly(p-phenylene), has created a lot of attention in recent years. Here, bundle formation in rigid rod-like polyelectrolytes is studied via computer simulations. For the case of hydrophobically modified polyelectrolytes finite size bundles are observed even in the presence of only monovalent counterions. Furthermore, in the absence of a hydrophobic backbone, we have also observed formation of finite size aggregates via multivalent counterion condensation. The size distribution of such aggregates and the stability is analyzed in this study.

  6. Finite size scaling and lattice gauge theory

    International Nuclear Information System (INIS)

    Berg, B.A.

    1986-01-01

    Finite size (Fisher) scaling is investigated for four dimensional SU(2) and SU(3) lattice gauge theories without quarks. It allows to disentangle violations of (asymptotic) scaling and finite volume corrections. Mass spectrum, string tension, deconfinement temperature and lattice β-function are considered. For appropriate volumes, Monte Carlo investigations seem to be able to control the finite volume continuum limit. Contact is made with Luescher's small volume expansion and possibly also with the asymptotic large volume behavior. 41 refs., 19 figs

  7. Stochastic synchronization in finite size spiking networks

    Science.gov (United States)

    Doiron, Brent; Rinzel, John; Reyes, Alex

    2006-09-01

    We study a stochastic synchronization of spiking activity in feedforward networks of integrate-and-fire model neurons. A stochastic mean field analysis shows that synchronization occurs only when the network size is sufficiently small. This gives evidence that the dynamics, and hence processing, of finite size populations can be drastically different from that observed in the infinite size limit. Our results agree with experimentally observed synchrony in cortical networks, and further strengthen the link between synchrony and propagation in cortical systems.

  8. Finite size scaling and spectral density studies

    International Nuclear Information System (INIS)

    Berg, B.A.

    1991-01-01

    Finite size scaling (FSS) and spectral density (SD) studies are reported for the deconfining phase transition. This talk concentrates on Monte Carlo (MC) results for pure SU(3) gauge theory, obtained in collaboration with Alves and Sanielevici, but the methods are expected to be useful for full QCD as well. (orig.)

  9. Finite size scaling and phenomenological renormalization

    International Nuclear Information System (INIS)

    Derrida, B.; Seze, L. de; Vannimenus, J.

    1981-05-01

    The basic equations of the phenomenological renormalization method are recalled. A simple derivation using finite-size scaling is presented. The convergence of the method is studied analytically for the Ising model. Using this method we give predictions for the 2d bond percolation. Finally we discuss how the method can be applied to random systems

  10. Finite-size analysis of continuous-variable measurement-device-independent quantum key distribution

    Science.gov (United States)

    Zhang, Xueying; Zhang, Yichen; Zhao, Yijia; Wang, Xiangyu; Yu, Song; Guo, Hong

    2017-10-01

    We study the impact of the finite-size effect on the continuous-variable measurement-device-independent quantum key distribution (CV-MDI QKD) protocol, mainly considering the finite-size effect on the parameter estimation procedure. The central-limit theorem and maximum likelihood estimation theorem are used to estimate the parameters. We also analyze the relationship between the number of exchanged signals and the optimal modulation variance in the protocol. It is proved that when Charlie's position is close to Bob, the CV-MDI QKD protocol has the farthest transmission distance in the finite-size scenario. Finally, we discuss the impact of finite-size effects related to the practical detection in the CV-MDI QKD protocol. The overall results indicate that the finite-size effect has a great influence on the secret-key rate of the CV-MDI QKD protocol and should not be ignored.

  11. Finite groups with three conjugacy class sizes of some elements

    Indian Academy of Sciences (India)

    Conjugacy class sizes; p-nilpotent groups; finite groups. 1. Introduction. All groups ... group G has exactly two conjugacy class sizes of elements of prime power order. .... [5] Huppert B, Character Theory of Finite Groups, de Gruyter Exp. Math.

  12. Finite size effects of a pion matrix element

    International Nuclear Information System (INIS)

    Guagnelli, M.; Jansen, K.; Palombi, F.; Petronzio, R.; Shindler, A.; Wetzorke, I.

    2004-01-01

    We investigate finite size effects of the pion matrix element of the non-singlet, twist-2 operator corresponding to the average momentum of non-singlet quark densities. Using the quenched approximation, they come out to be surprisingly large when compared to the finite size effects of the pion mass. As a consequence, simulations of corresponding nucleon matrix elements could be affected by finite size effects even stronger which could lead to serious systematic uncertainties in their evaluation

  13. Finite-size scaling of survival probability in branching processes

    OpenAIRE

    Garcia-Millan, Rosalba; Font-Clos, Francesc; Corral, Alvaro

    2014-01-01

    Branching processes pervade many models in statistical physics. We investigate the survival probability of a Galton-Watson branching process after a finite number of generations. We reveal the finite-size scaling law of the survival probability for a given branching process ruled by a probability distribution of the number of offspring per element whose standard deviation is finite, obtaining the exact scaling function as well as the critical exponents. Our findings prove the universal behavi...

  14. Multipartite geometric entanglement in finite size XY model

    Energy Technology Data Exchange (ETDEWEB)

    Blasone, Massimo; Dell' Anno, Fabio; De Siena, Silvio; Giampaolo, Salvatore Marco; Illuminati, Fabrizio, E-mail: blasone@sa.infn.i [Dipartimento di Matematica e Informatica, Universita degli Studi di Salerno, Via Ponte don Melillo, I-84084 Fisciano (Italy)

    2009-06-01

    We investigate the behavior of the multipartite entanglement in the finite size XY model by means of the hierarchical geometric measure of entanglement. By selecting specific components of the hierarchy, we study both global entanglement and genuinely multipartite entanglement.

  15. Finite-State Complexity and the Size of Transducers

    Directory of Open Access Journals (Sweden)

    Cristian Calude

    2010-08-01

    Full Text Available Finite-state complexity is a variant of algorithmic information theory obtained by replacing Turing machines with finite transducers. We consider the state-size of transducers needed for minimal descriptions of arbitrary strings and, as our main result, we show that the state-size hierarchy with respect to a standard encoding is infinite. We consider also hierarchies yielded by more general computable encodings.

  16. Finite size effects for giant magnons on physical strings

    International Nuclear Information System (INIS)

    Minahan, J.A.; Ohlsson Sax, O.

    2008-01-01

    Using finite gap methods, we find the leading order finite size corrections for an arbitrary number of giant magnons on physical strings, where the sum of the momenta is a multiple of 2π. Our results are valid for the Hofman-Maldacena fundamental giant magnons as well as their dyonic generalizations. The energy corrections turn out to be surprisingly simple, especially if all the magnons are fundamental, and at leading order are independent of the magnon flavors. We also show how to use the Bethe ansatz to find finite size corrections for dyonic giant magnons with large R-charges

  17. Dynamic properties of epidemic spreading on finite size complex networks

    Science.gov (United States)

    Li, Ying; Liu, Yang; Shan, Xiu-Ming; Ren, Yong; Jiao, Jian; Qiu, Ben

    2005-11-01

    The Internet presents a complex topological structure, on which computer viruses can easily spread. By using theoretical analysis and computer simulation methods, the dynamic process of disease spreading on finite size networks with complex topological structure is investigated. On the finite size networks, the spreading process of SIS (susceptible-infected-susceptible) model is a finite Markov chain with an absorbing state. Two parameters, the survival probability and the conditional infecting probability, are introduced to describe the dynamic properties of disease spreading on finite size networks. Our results can help understanding computer virus epidemics and other spreading phenomena on communication and social networks. Also, knowledge about the dynamic character of virus spreading is helpful for adopting immunity policy.

  18. Electrokinetic Flow in Microchannels with Finite Reservoir Size Effects

    International Nuclear Information System (INIS)

    Yan, D; Yang, C; Nguyen, N-T; Huang, X

    2006-01-01

    In electrokinetically-driven microfluidic applications, reservoirs are indispensable and have finite sizes. During operation processes, as the liquid level difference in reservoirs keeps changing as time elapses, the flow characteristics in a microchannel exhibit a combination of the electroosmotic flow and the time-dependent induced backpressure-driven flow. In this work, an assessment of the finite reservoir size effect on electroosmotic flows is presented theoretically and experimentally. A model is developed to describe the timedependent electrokinetic flow with finite reservoir size effects. The theoretical analysis shows that under certain conditions the finite reservoir size effect is significant. The important parameters that describe the effect of finite reservoir size on the flow characteristics are discussed. A new concept denoted as 'effective pumping period' is introduced to characterize the reservoir size effect. The proposed model clearly identifies the mechanisms of the finitereservoir size effects and is further confirmed by using micro-PIV technique. The results of this study can be used for facilitating the design of microfluidic devices

  19. Organizational Ignorance

    DEFF Research Database (Denmark)

    Lange, Ann-Christina

    2016-01-01

    This paper provides an analysis of strategic uses of ignorance or not-knowing in one of the most secretive industries within the financial sector. The focus of the paper is on the relation between imitation and ignorance within the organizational structure of high-frequency trading (HFT) firms...... and investigate the kinds of imitations that might be produced from structures of not-knowing (i.e. structures intended to divide, obscure and protect knowledge). This point is illustrated through ethnographic studies and interviews within five HFT firms. The data show how a black-box structure of ignorance...

  20. Finite-size scaling of survival probability in branching processes.

    Science.gov (United States)

    Garcia-Millan, Rosalba; Font-Clos, Francesc; Corral, Álvaro

    2015-04-01

    Branching processes pervade many models in statistical physics. We investigate the survival probability of a Galton-Watson branching process after a finite number of generations. We derive analytically the existence of finite-size scaling for the survival probability as a function of the control parameter and the maximum number of generations, obtaining the critical exponents as well as the exact scaling function, which is G(y)=2ye(y)/(e(y)-1), with y the rescaled distance to the critical point. Our findings are valid for any branching process of the Galton-Watson type, independently of the distribution of the number of offspring, provided its variance is finite. This proves the universal behavior of the finite-size effects in branching processes, including the universality of the metric factors. The direct relation to mean-field percolation is also discussed.

  1. Finite-size scaling a collection of reprints

    CERN Document Server

    1988-01-01

    Over the past few years, finite-size scaling has become an increasingly important tool in studies of critical systems. This is partly due to an increased understanding of finite-size effects by analytical means, and partly due to our ability to treat larger systems with large computers. The aim of this volume was to collect those papers which have been important for this progress and which illustrate novel applications of the method. The emphasis has been placed on relatively recent developments, including the use of the &egr;-expansion and of conformal methods.

  2. Simulation of finite size effects of the fiber bundle model

    Science.gov (United States)

    Hao, Da-Peng; Tang, Gang; Xun, Zhi-Peng; Xia, Hui; Han, Kui

    2018-01-01

    In theory, the macroscopic fracture of materials should correspond with the thermodynamic limit of the fiber bundle model. However, the simulation of a fiber bundle model with an infinite size is unrealistic. To study the finite size effects of the fiber bundle model, fiber bundle models of various size are simulated in detail. The effects of system size on the constitutive behavior, critical stress, maximum avalanche size, avalanche size distribution, and increased step number of external load are explored. The simulation results imply that there is no feature size or cut size for macroscopic mechanical and statistical properties of the model. The constitutive curves near the macroscopic failure for various system size can collapse well with a simple scaling relationship. Simultaneously, the introduction of a simple extrapolation method facilitates the acquisition of more accurate simulation results in a large-limit system, which is better for comparison with theoretical results.

  3. Distribution of quantum states in enclosures of finite size I

    International Nuclear Information System (INIS)

    Souto, J.H.; Chaba, A.N.

    1989-01-01

    The expression for the density of states of a particle in a three-dimensional rectangular box of finite size can be obtained directly by Poissons's Summation formula. The expression for the case of an enclosure in the form of an infinite rectangular slab is derived. (A.C.A.S.) [pt

  4. Finite-size effects for anisotropic bootstrap percolation : Logarithmic corrections

    NARCIS (Netherlands)

    van Enter, Aernout C. D.; Hulshof, Tim

    In this note we analyse an anisotropic, two-dimensional bootstrap percolation model introduced by Gravner and Griffeath. We present upper and lower bounds on the finite-size effects. We discuss the similarities with the semi-oriented model introduced by Duarte.

  5. Finite-size effects for anisotropic bootstrap percolation: logerithmic corrections

    NARCIS (Netherlands)

    Enter, van A.C.D.; Hulshof, T.

    2007-01-01

    In this note we analyse an anisotropic, two-dimensional bootstrap percolation model introduced by Gravner and Griffeath. We present upper and lower bounds on the finite-size effects. We discuss the similarities with the semi-oriented model introduced by Duarte.

  6. Finite-Size Effects for Some Bootstrap Percolation Models

    NARCIS (Netherlands)

    Enter, A.C.D. van; Adler, Joan; Duarte, J.A.M.S.

    The consequences of Schonmann's new proof that the critical threshold is unity for certain bootstrap percolation models are explored. It is shown that this proof provides an upper bound for the finite-size scaling in these systems. Comparison with data for one case demonstrates that this scaling

  7. Finite size effects in quark-gluon plasma formation

    International Nuclear Information System (INIS)

    Gopie, Andy; Ogilvie, Michael C.

    1999-01-01

    Using lattice simulations of quenched QCD we estimate the finite size effects present when a gluon plasma equilibrates in a slab geometry, i.e., finite width but large transverse dimensions. Significant differences are observed in the free energy density for the slab when compared with bulk behavior. A small shift in the critical temperature is also seen. The free energy required to liberate heavy quarks relative to bulk is measured using Polyakov loops; the additional free energy required is on the order of 30 - 40 MeV at 2 - 3 T c

  8. Finite size effects in simulations of protein aggregation.

    Directory of Open Access Journals (Sweden)

    Amol Pawar

    Full Text Available It is becoming increasingly clear that the soluble protofibrillar species that proceed amyloid fibril formation are associated with a range of neurodegenerative disorders such as Alzheimer's and Parkinson diseases. Computer simulations of the processes that lead to the formation of these oligomeric species are starting to make significant contributions to our understanding of the determinants of protein aggregation. We simulate different systems at constant concentration but with a different number of peptides and we study the how the finite number of proteins affects the underlying free energy of the system and therefore the relative stability of the species involved in the process. If not taken into account, this finite size effect can undermine the validity of theoretical predictions regarding the relative stability of the species involved and the rates of conversion from one to the other. We discuss the reasons that give rise to this finite size effect form both a probabilistic and energy fluctuations point of view and also how this problem can be dealt by a finite size scaling analysis.

  9. Chiral anomaly and anomalous finite-size conductivity in graphene

    Science.gov (United States)

    Shen, Shun-Qing; Li, Chang-An; Niu, Qian

    2017-09-01

    Graphene is a monolayer of carbon atoms packed into a hexagon lattice to host two spin degenerate pairs of massless two-dimensional Dirac fermions with different chirality. It is known that the existence of non-zero electric polarization in reduced momentum space which is associated with a hidden chiral symmetry will lead to the zero-energy flat band of a zigzag nanoribbon and some anomalous transport properties. Here it is proposed that the Adler-Bell-Jackiw chiral anomaly or non-conservation of chiral charges of Dirac fermions at different valleys can be realized in a confined ribbon of finite width, even in the absence of a magnetic field. In the laterally diffusive regime, the finite-size correction to conductivity is always positive and is inversely proportional to the square of the lateral dimension W, which is different from the finite-size correction inversely proportional to W from the boundary modes. This anomalous finite-size conductivity reveals the signature of the chiral anomaly in graphene, and it is measurable experimentally. This finding provides an alternative platform to explore the purely quantum mechanical effect in graphene.

  10. Finite-size modifications of the magnetic properties of clusters

    DEFF Research Database (Denmark)

    Hendriksen, Peter Vang; Linderoth, Søren; Lindgård, Per-Anker

    1993-01-01

    relative to the bulk, and the consequent neutron-scattering cross section exhibits discretely spaced wave-vector-broadened eigenstates. The implications of the finite size on thermodynamic properties, like the temperature dependence of the magnetization and the critical temperature, are also elucidated. We...... find the temperature dependence of the cluster magnetization to be well described by an effective power law, M(mean) is-proportional-to 1 - BT(alpha), with a size-dependent, but structure-independent, exponent larger than the bulk value. The critical temperature of the clusters is calculated from...... the spin-wave spectrum by a method based on the correlation theory and the spherical approximation generalized to the case of finite systems. A size-dependent reduction of the critical temperature by up to 50% for the smallest clusters is found. The trends found for the model clusters are extrapolated...

  11. Finite-size polyelectrolyte bundles at thermodynamic equilibrium

    Science.gov (United States)

    Sayar, M.; Holm, C.

    2007-01-01

    We present the results of extensive computer simulations performed on solutions of monodisperse charged rod-like polyelectrolytes in the presence of trivalent counterions. To overcome energy barriers we used a combination of parallel tempering and hybrid Monte Carlo techniques. Our results show that for small values of the electrostatic interaction the solution mostly consists of dispersed single rods. The potential of mean force between the polyelectrolyte monomers yields an attractive interaction at short distances. For a range of larger values of the Bjerrum length, we find finite-size polyelectrolyte bundles at thermodynamic equilibrium. Further increase of the Bjerrum length eventually leads to phase separation and precipitation. We discuss the origin of the observed thermodynamic stability of the finite-size aggregates.

  12. Finite size effects in neutron star and nuclear matter simulations

    Energy Technology Data Exchange (ETDEWEB)

    Giménez Molinelli, P.A., E-mail: pagm@df.uba.ar; Dorso, C.O.

    2015-01-15

    In this work we study molecular dynamics simulations of symmetric nuclear and neutron star matter using a semi-classical nucleon interaction model. Our aim is to gain insight on the nature of the so-called “finite size effects”, unavoidable in this kind of simulations, and to understand what they actually affect. To do so, we explore different geometries for the periodic boundary conditions imposed on the simulation cell: cube, hexagonal prism and truncated octahedron. For nuclear matter simulations we show that, at sub-saturation densities and low temperatures, the solutions are non-homogeneous structures reminiscent of the “nuclear pasta” phases expected in neutron star matter simulations, but only one structure per cell and shaped by specific artificial aspects of the simulations—for the same physical conditions (i.e. number density and temperature) different cells yield different solutions. The particular shape of the solution at low enough temperature and a given density can be predicted analytically by surface minimization. We also show that even if this behavior is due to the imposition of periodic boundary conditions on finite systems, this does not mean that it vanishes for very large systems, and it is actually independent of the system size. We conclude that, for nuclear matter simulations, the cells' size sets the only characteristic length scale for the inhomogeneities, and the geometry of the periodic cell determines the shape of those inhomogeneities. To model neutron star matter we add a screened Coulomb interaction between protons, and perform simulations in the three cell geometries. Our simulations indeed produce the well known nuclear pasta, with (in most cases) several structures per cell. However, we find that for systems not too large results are affected by finite size in different ways depending on the geometry of the cell. In particular, at the same certain physical conditions and system size, the hexagonal prism yields a

  13. Finite size effects on hydrogen bonds in confined water

    International Nuclear Information System (INIS)

    Musat, R.; Renault, J.P.; Le Caer, S.; Pommeret, S.; Candelaresi, M.; Palmer, D.J.; Righini, R.

    2008-01-01

    Femtosecond IR spectroscopy was used to study water confined in 1-50 nm pores. The results show that even large pores induce significant changes (for example excited-state lifetimes) to the hydrogen-bond network, which are independent of pore diameter between 1 and 50 nm. Thus, the changes are not surface-induced but rather finite size effects, and suggest a confinement-induced enhancement of the acidic character of water. (authors)

  14. fB from finite size effects in lattice QCD

    International Nuclear Information System (INIS)

    Guagnelli, M.; Palombi, F.; Petronzio, R.; Tantalo, N.

    2003-01-01

    We discuss a novel method to calculate f B on the lattice, introduced in [1], based on the study of the dependence of finite size effects upon the heavy quark mass of flavoured mesons and on a non-perturbative recursive finite size technique. This method avoids the systematic errors related to extrapolations from the static limit or to the tuning of the coefficients of effective Lagrangian and the results admit an extrapolation to the continuum limit. We show the results of a first estimate at finite lattice spacing, but close to the continuum limit, giving f B = 170(11)(5)(22) MeV. We also obtain f B s = 192(9)(5)(24)MeV. The first error is statistical, the second is our estimate of the systematic error from the method and the third the systematic error from the specific approximations adopted in this first exploratory calculation. The method can be generalized to two-scale problems in lattice QCD

  15. Finite-size scaling in two-dimensional superfluids

    International Nuclear Information System (INIS)

    Schultka, N.; Manousakis, E.

    1994-01-01

    Using the x-y model and a nonlocal updating scheme called cluster Monte Carlo, we calculate the superfluid density of a two-dimensional superfluid on large-size square lattices LxL up to 400x400. This technique allows us to approach temperatures close to the critical point, and by studying a wide range of L values and applying finite-size scaling theory we are able to extract the critical properties of the system. We calculate the superfluid density and from that we extract the renormalization-group beta function. We derive finite-size scaling expressions using the Kosterlitz-Thouless-Nelson renormalization group equations and show that they are in very good agreement with our numerical results. This allows us to extrapolate our results to the infinite-size limit. We also find that the universal discontinuity of the superfluid density at the critical temperature is in very good agreement with the Kosterlitz-Thouless-Nelson calculation and experiments

  16. Finite-size resonance dielectric cylinder in a rectangular waveguide

    International Nuclear Information System (INIS)

    Chuprina, V.N.; Khizhnyak, N.A.

    1988-01-01

    The problem on resonance spread of an electromagnetic wave by a dielectric circular cylinder of finite size in a rectangular waveguide is solved by a numerical-analytical method. The cylinder axes are parallel. The cylinder can be used as a resonance tuning element in accelerating SHF-sections. Problems on cutting off linear algebraic equation systems, to which relations of macroscopic electrodynamics in the integral differential form written for the concrete problem considered here are reduced by analytical transformations, are investigated in the stage of numerical analysis. Theoretical dependences of the insertion of the voltage standing wave coefficient on the generator wave length calculated for different values of problem parameters are constracted

  17. Asymmetric fluid criticality. II. Finite-size scaling for simulations.

    Science.gov (United States)

    Kim, Young C; Fisher, Michael E

    2003-10-01

    The vapor-liquid critical behavior of intrinsically asymmetric fluids is studied in finite systems of linear dimensions L focusing on periodic boundary conditions, as appropriate for simulations. The recently propounded "complete" thermodynamic (L--> infinity) scaling theory incorporating pressure mixing in the scaling fields as well as corrections to scaling [Phys. Rev. E 67, 061506 (2003)] is extended to finite L, initially in a grand canonical representation. The theory allows for a Yang-Yang anomaly in which, when L--> infinity, the second temperature derivative (d2musigma/dT2) of the chemical potential along the phase boundary musigmaT diverges when T-->Tc-. The finite-size behavior of various special critical loci in the temperature-density or (T,rho) plane, in particular, the k-inflection susceptibility loci and the Q-maximal loci--derived from QL(T,L) is identical with 2L/L where m is identical with rho-L--is carefully elucidated and shown to be of value in estimating Tc and rhoc. Concrete illustrations are presented for the hard-core square-well fluid and for the restricted primitive model electrolyte including an estimate of the correlation exponent nu that confirms Ising-type character. The treatment is extended to the canonical representation where further complications appear.

  18. The Varieties of Ignorance

    DEFF Research Database (Denmark)

    Nottelmann, Nikolaj

    2016-01-01

    This chapter discusses varieties of ignorance divided according to kind (what the subject is ignorant of), degree, and order (e.g. ignorance of ignorance equals second-order ignorance). It provides analyses of notions such as factual ignorance, erotetic ignorance (ignorance of answers to question...

  19. Finite-size effects on multibody neutrino exchange

    CERN Document Server

    Abada, A; Rodríguez-Quintero, J; Abada, As

    1998-01-01

    The effect of multibody massless neutrino exchanges between neutrons inside a finite-size neutron star is studied. We use an effective Lagrangian, which incorporates the effect of the neutrons on the neutrinos. Following Schwinger, it is shown that the total interaction energy density is computed by comparing the zero point energy of the neutrino sea with and without the star. It has already been shown that in an infinite-size star the total energy due to neutrino exchange vanishes exactly. The opposite claim that massless neutrino exchange would produce a huge energy is due to an improper summation of an infrared-divergent quantity. The same vanishing of the total energy has been proved exactly in the case of a finite star in a one-dimensional toy model. Here we study the three-dimensional case. We first consider the effect of a sharp star border, assumed to be a plane. We find that there is a non- vanishing of the zero point energy density difference between the inside and the outside due to the refraction ...

  20. Diffusion of Finite-Size Particles in Confined Geometries

    KAUST Repository

    Bruna, Maria

    2013-05-10

    The diffusion of finite-size hard-core interacting particles in two- or three-dimensional confined domains is considered in the limit that the confinement dimensions become comparable to the particle\\'s dimensions. The result is a nonlinear diffusion equation for the one-particle probability density function, with an overall collective diffusion that depends on both the excluded-volume and the narrow confinement. By including both these effects, the equation is able to interpolate between severe confinement (for example, single-file diffusion) and unconfined diffusion. Numerical solutions of both the effective nonlinear diffusion equation and the stochastic particle system are presented and compared. As an application, the case of diffusion under a ratchet potential is considered, and the change in transport properties due to excluded-volume and confinement effects is examined. © 2013 Society for Mathematical Biology.

  1. Diffusion of Finite-Size Particles in Confined Geometries

    KAUST Repository

    Bruna, Maria; Chapman, S. Jonathan

    2013-01-01

    The diffusion of finite-size hard-core interacting particles in two- or three-dimensional confined domains is considered in the limit that the confinement dimensions become comparable to the particle's dimensions. The result is a nonlinear diffusion equation for the one-particle probability density function, with an overall collective diffusion that depends on both the excluded-volume and the narrow confinement. By including both these effects, the equation is able to interpolate between severe confinement (for example, single-file diffusion) and unconfined diffusion. Numerical solutions of both the effective nonlinear diffusion equation and the stochastic particle system are presented and compared. As an application, the case of diffusion under a ratchet potential is considered, and the change in transport properties due to excluded-volume and confinement effects is examined. © 2013 Society for Mathematical Biology.

  2. Finite-size effect on optimal efficiency of heat engines.

    Science.gov (United States)

    Tajima, Hiroyasu; Hayashi, Masahito

    2017-07-01

    The optimal efficiency of quantum (or classical) heat engines whose heat baths are n-particle systems is given by the strong large deviation. We give the optimal work extraction process as a concrete energy-preserving unitary time evolution among the heat baths and the work storage. We show that our optimal work extraction turns the disordered energy of the heat baths to the ordered energy of the work storage, by evaluating the ratio of the entropy difference to the energy difference in the heat baths and the work storage, respectively. By comparing the statistical mechanical optimal efficiency with the macroscopic thermodynamic bound, we evaluate the accuracy of the macroscopic thermodynamics with finite-size heat baths from the statistical mechanical viewpoint. We also evaluate the quantum coherence effect on the optimal efficiency of the cycle processes without restricting their cycle time by comparing the classical and quantum optimal efficiencies.

  3. Finite-size effects on current correlation functions

    Science.gov (United States)

    Chen, Shunda; Zhang, Yong; Wang, Jiao; Zhao, Hong

    2014-02-01

    We study why the calculation of current correlation functions (CCFs) still suffers from finite-size effects even when the periodic boundary condition is taken. Two important one-dimensional, momentum-conserving systems are investigated as examples. Intriguingly, it is found that the state of a system recurs in the sense of microcanonical ensemble average, and such recurrence may result in oscillations in CCFs. Meanwhile, we find that the sound mode collisions induce an extra time decay in a current so that its correlation function decays faster (slower) in a smaller (larger) system. Based on these two unveiled mechanisms, a procedure for correctly evaluating the decay rate of a CCF is proposed, with which our analysis suggests that the global energy CCF decays as ˜t-2/3 in the diatomic hard-core gas model and in a manner close to ˜t-1/2 in the Fermi-Pasta-Ulam-β model.

  4. Finite-size corrections in simulation of dipolar fluids

    Science.gov (United States)

    Belloni, Luc; Puibasset, Joël

    2017-12-01

    Monte Carlo simulations of dipolar fluids are performed at different numbers of particles N = 100-4000. For each size of the cubic cell, the non-spherically symmetric pair distribution function g(r,Ω) is accumulated in terms of projections gmnl(r) onto rotational invariants. The observed N dependence is in very good agreement with the theoretical predictions for the finite-size corrections of different origins: the explicit corrections due to the absence of fluctuations in the number of particles within the canonical simulation and the implicit corrections due to the coupling between the environment around a given particle and that around its images in the neighboring cells. The latter dominates in fluids of strong dipolar coupling characterized by low compressibility and high dielectric constant. The ability to clean with great precision the simulation data from these corrections combined with the use of very powerful anisotropic integral equation techniques means that exact correlation functions both in real and Fourier spaces, Kirkwood-Buff integrals, and bridge functions can be derived from box sizes as small as N ≈ 100, even with existing long-range tails. In the presence of dielectric discontinuity with the external medium surrounding the central box and its replica within the Ewald treatment of the Coulombic interactions, the 1/N dependence of the gmnl(r) is shown to disagree with the, yet well-accepted, prediction of the literature.

  5. Mesh-size errors in diffusion-theory calculations using finite-difference and finite-element methods

    International Nuclear Information System (INIS)

    Baker, A.R.

    1982-07-01

    A study has been performed of mesh-size errors in diffusion-theory calculations using finite-difference and finite-element methods. As the objective was to illuminate the issues, the study was performed for a 1D slab model of a reactor with one neutron-energy group for which analytical solutions were possible. A computer code SLAB was specially written to perform the finite-difference and finite-element calculations and also to obtain the analytical solutions. The standard finite-difference equations were obtained by starting with an expansion of the neutron current in powers of the mesh size, h, and keeping terms as far as h 2 . It was confirmed that these equations led to the well-known result that the criticality parameter varied with the square of the mesh size. An improved form of the finite-difference equations was obtained by continuing the expansion for the neutron current as far as the term in h 4 . In this case, the critical parameter varied as the fourth power of the mesh size. The finite-element solutions for 2 and 3 nodes per element revealed that the criticality parameter varied as the square and fourth power of the mesh size, respectively. Numerical results are presented for a bare reactive core of uniform composition with 2 zones of different uniform mesh and for a reactive core with an absorptive reflector. (author)

  6. Holographic relaxation of finite size isolated quantum systems

    International Nuclear Information System (INIS)

    Abajo-Arrastia, Javier; Silva, Emilia da; Lopez, Esperanza; Mas, Javier; Serantes, Alexandre

    2014-01-01

    We study holographically the out of equilibrium dynamics of a finite size closed quantum system in 2+1 dimensions, modelled by the collapse of a shell of a massless scalar field in AdS_4. In global coordinates there exists a variety of evolutions towards final black hole formation which we relate with different patterns of relaxation in the dual field theory. For large scalar initial data rapid thermalization is achieved as a priori expected. Interesting phenomena appear for small enough amplitudes. Such shells do not generate a black hole by direct collapse, but quite generically, an apparent horizon emerges after enough bounces off the AdS boundary. We relate this bulk evolution with relaxation processes at strong coupling which delay in reaching an ergodic stage. Besides the dynamics of bulk fields, we monitor the entanglement entropy, finding that it oscillates quasi-periodically before final equilibration. The radial position of the travelling shell is brought in correspondence with the evolution of the pattern of entanglement in the dual field theory. We propose, thereafter, that the observed oscillations are the dual counterpart of the quantum revivals studied in the literature. The entanglement entropy is not only able to portrait the streaming of entangled excitations, but it is also a useful probe of interaction effects

  7. The Optimal Inhomogeneity for Superconductivity: Finite Size Studies

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, W-F.

    2010-04-06

    We report the results of exact diagonalization studies of Hubbard models on a 4 x 4 square lattice with periodic boundary conditions and various degrees and patterns of inhomogeneity, which are represented by inequivalent hopping integrals t and t{prime}. We focus primarily on two patterns, the checkerboard and the striped cases, for a large range of values of the on-site repulsion U and doped hole concentration, x. We present evidence that superconductivity is strongest for U of order the bandwidth, and intermediate inhomogeneity, 0 < t{prime} < t. The maximum value of the 'pair-binding energy' we have found with purely repulsive interactions is {Delta}{sub pb} = 0.32t for the checkerboard Hubbard model with U = 8t and t{prime} = 0.5t. Moreover, for near optimal values, our results are insensitive to changes in boundary conditions, suggesting that the correlation length is sufficiently short that finite size effects are already unimportant.

  8. Finite size scaling analysis of disordered electron systems

    International Nuclear Information System (INIS)

    Markos, P.

    2012-01-01

    We demonstrated the application of the finite size scaling method to the analysis of the transition of the disordered system from the metallic to the insulating regime. The method enables us to calculate the critical point and the critical exponent which determines the divergence of the correlation length in the vicinity of the critical point. The universality of the metal-insulator transition was verified by numerical analysis of various physical parameters and the critical exponent was calculated with high accuracy for different disordered models. Numerically obtained value of the critical exponent for the three dimensional disordered model (1) has been recently supported by the semi-analytical work and verified by experimental optical measurements equivalent to the three dimensional disordered model (1). Another unsolved problem of the localization is the disagreement between numerical results and predictions of the analytical theories. At present, no analytical theory confirms numerically obtained values of critical exponents. The reason for this disagreement lies in the statistical character of the process of localization. The theory must consider all possible scattering processes on randomly distributed impurities. All physical variables are statistical quantities with broad probability distributions. It is in general not know how to calculate analytically their mean values. We believe that detailed numerical analysis of various disordered systems bring inspiration for the formulation of analytical theory. (authors)

  9. Finite size effects in the intermittency analysis of the fragment-size correlations

    International Nuclear Information System (INIS)

    Bozek, P.; Ploszajczak, M.; Tucholski, A.

    1991-01-01

    An influence of the finite size effect on the fragment-size correlations in the nuclear multifragmentation is studied using the method of scaled factorial moments for a 1 - dim percolation model and for a statistical model of the fragmentation process, which for a certain value of a tuning parameter yields the power-law behaviour of the fragment-size distribution. It is shown that the statistical models of this type contain only repulsive correlations due to the conservation laws. The comparison of the results with those obtained in the non-critical 1 - dim percolation and in the 3 - dim percolation at around the critical point is presented. Correlations in the 1 - dim percolation model are analysed analytically and the mechanism of the attractive correlations in 1 - dim and 3 - dim is identified. (author) 30 refs., 7 figs

  10. Finite size effects in lattice QCD with dynamical Wilson fermions

    Energy Technology Data Exchange (ETDEWEB)

    Orth, B.

    2004-06-01

    Due to limited computing resources choosing the parameters for a full lattice QCD simulation always amounts to a compromise between the competing objectives of a lattice spacing as small, quarks as light, and a volume as large as possible. Aiming at pushing unquenched simulations with the standard Wilson action towards the computationally expensive regime of small quark masses, the GRAL project addresses the question whether computing time can be saved by sticking to lattices with rather modest numbers of grid sites and extrapolating the finite-volume results to the infinite volume (prior to the usual chiral and continuum extrapolations). In this context we investigate in this work finite-size effects in simulated light hadron masses. Understanding their systematic volume dependence may not only help saving computer time in light quark simulations with the Wilson action, but also guide future simulations with dynamical chiral fermions which for a foreseeable time will be restricted to rather small lattices. We analyze data from hybrid Monte Carlo simulations with the N{sub f} = 2 Wilson action at two values of the coupling parameter, {beta} = 5.6 (lattice spacing {alpha} {approx} 0.08 fm) and {beta} = 5.32144 ({alpha} {approx} 0.13 fm). The larger {beta} corresponds to the coupling used previously by SESAM/T{chi}L. The considered hopping parameters {kappa} = 0.1575, 0.158 (at the larger {beta}) and {kappa} = 0.1665 (at the smaller {beta}) correspond to quark masses of 85, 50 and 36% of the strange quark mass, respectively. At each quark mass we study at least three different lattice extents in the range from L = 10 to L = 24 (0.85-2.04 fm). Estimates of autocorrelation times in the stochastic updating process and of the computational cost of every run are given. For each simulated sea quark mass we calculate quark propagators and hadronic correlation functions in order to extract the pion, rho and nucleon masses as well as the pion decay constant and the quark mass

  11. Layout Optimization of Structures with Finite-size Features using Multiresolution Analysis

    DEFF Research Database (Denmark)

    Chellappa, S.; Diaz, A. R.; Bendsøe, Martin P.

    2004-01-01

    A scheme for layout optimization in structures with multiple finite-sized heterogeneities is presented. Multiresolution analysis is used to compute reduced operators (stiffness matrices) representing the elastic behavior of material distributions with heterogeneities of sizes that are comparable...

  12. Deconfinement phase transition and finite-size scaling in SU(2) lattice gauge theory

    International Nuclear Information System (INIS)

    Mogilevskij, O.A.

    1988-01-01

    Calculation technique for deconfinement phase transition parameters based on application of finite-size scaling theory is suggested. The essence of the technique lies in plotting of universal scaling function on the basis of numerical data obtained at different-size final lattices and discrimination of phase transition parameters for infinite lattice system. Finite-size scaling technique was developed as applied to spin system theory. β critical index for Polyakov loop and SU(2) deconfinement temperature of lattice gauge theory are calculated on the basis of finite-size scaling technique. The obtained value agrees with critical index of magnetization in Ising three-dimensional model

  13. Finite-size scaling theory and quantum hamiltonian Field theory: the transverse Ising model

    International Nuclear Information System (INIS)

    Hamer, C.J.; Barber, M.N.

    1979-01-01

    Exact results for the mass gap, specific heat and susceptibility of the one-dimensional transverse Ising model on a finite lattice are generated by constructing a finite matrix representation of the Hamiltonian using strong-coupling eigenstates. The critical behaviour of the limiting infinite chain is analysed using finite-size scaling theory. In this way, excellent estimates (to within 1/2% accuracy) are found for the critical coupling and the exponents α, ν and γ

  14. Isobaric expansion coefficient and isothermal compressibility for a finite-size ideal Fermi gas system

    International Nuclear Information System (INIS)

    Su, Guozhen; Chen, Liwei; Chen, Jincan

    2014-01-01

    Due to quantum size effects (QSEs), the isobaric thermal expansion coefficient and isothermal compressibility well defined for macroscopic systems are invalid for finite-size systems. The two parameters are redefined and calculated for a finite-size ideal Fermi gas confined in a rectangular container. It is found that the isobaric thermal expansion coefficient and isothermal compressibility are generally anisotropic, i.e., they are generally different in different directions. Moreover, it is found the thermal expansion coefficient may be negative in some directions under the condition that the pressures in all directions are kept constant. - Highlights: • Isobaric thermal expansion coefficient and isothermal compressibility are redefined. • The two parameters are calculated for a finite-size ideal Fermi gas. • The two parameters are generally anisotropic for a finite-size system. • Isobaric thermal expansion coefficient may be negative in some directions

  15. Theory of critical phenomena in finite-size systems scaling and quantum effects

    CERN Document Server

    Brankov, Jordan G; Tonchev, Nicholai S

    2000-01-01

    The aim of this book is to familiarise the reader with the rich collection of ideas, methods and results available in the theory of critical phenomena in systems with confined geometry. The existence of universal features of the finite-size effects arising due to highly correlated classical or quantum fluctuations is explained by the finite-size scaling theory. This theory (1) offers an interpretation of experimental results on finite-size effects in real systems; (2) gives the most reliable tool for extrapolation to the thermodynamic limit of data obtained by computer simulations; (3) reveals

  16. Finite size effects and chiral symmetry breaking in quenched three-dimensional QED

    International Nuclear Information System (INIS)

    Hands, S.; Kogut, J.B.

    1990-01-01

    Finite size effects and the chiral condensate are studied in three-dimensional QED by the Lanczos and the conjugate-gradient algorithms. Very substantial finite size effects are observed, but studies on L 3 lattices with L ranging from 8 to 80 indicate the development of a non-vanishing chiral condensate in the continuum limit of the theory. The systematics of the finite size effects and the fermion mass dependence in the conjugate-gradient algorithm are clarified in this extensive study. (orig.)

  17. The finite horizon economic lot sizing problem in job shops : the multiple cycle approach

    NARCIS (Netherlands)

    Ouenniche, J.; Bertrand, J.W.M.

    2001-01-01

    This paper addresses the multi-product, finite horizon, static demand, sequencing, lot sizing and scheduling problem in a job shop environment where the planning horizon length is finite and fixed by management. The objective pursued is to minimize the sum of setup costs, and work-in-process and

  18. Finite-size scaling for quantum chains with an oscillatory energy gap

    International Nuclear Information System (INIS)

    Hoeger, C.; Gehlen, G. von; Rittenberg, V.

    1984-07-01

    We show that the existence of zeroes of the energy gap for finite quantum chains is related to a nonvanishing wavevector. Finite-size scaling ansaetze are formulated for incommensurable and oscillatory structures. The ansaetze are verified in the one-dimensional XY model in a transverse field. (orig.)

  19. Ignorability for categorical data

    DEFF Research Database (Denmark)

    Jaeger, Manfred

    2005-01-01

    We study the problem of ignorability in likelihood-based inference from incomplete categorical data. Two versions of the coarsened at random assumption (car) are distinguished, their compatibility with the parameter distinctness assumption is investigated and several conditions for ignorability...

  20. Finite-size effects in the three-state quantum asymmetric clock model

    International Nuclear Information System (INIS)

    Gehlen, G. v.; Rittenberg, V.

    1983-04-01

    The one-dimensional quantum Hamiltonian of the asymmetric three-state clock model is studied using finite-size scaling. Various boundary conditions are considered on chains containing up to eight sites. We calculate the boundary of the commensurate phase and the mass gap index. The model shows an interesting finite-size dependence in connexion with the presence of the incommensurate phase indicating that for the infinite system there is no Lifshitz point. (orig.)

  1. Finite size effects and symmetry breaking in the evolution of networks of competing Boolean nodes

    International Nuclear Information System (INIS)

    Liu, M; Bassler, K E

    2011-01-01

    Finite size effects on the evolutionary dynamics of Boolean networks are analyzed. In the model considered, Boolean networks evolve via a competition between nodes that punishes those in the majority. Previous studies have found that large networks evolve to a statistical steady state that is both critical and highly canalized, and that the evolution of canalization, which is a form of robustness found in genetic regulatory networks, is associated with a particular symmetry of the evolutionary dynamics. Here, it is found that finite size networks evolve in a fundamentally different way than infinitely large networks do. The symmetry of the evolutionary dynamics of infinitely large networks that selects for canalizing Boolean functions is broken in the evolutionary dynamics of finite size networks. In finite size networks, there is an additional selection for input-inverting Boolean functions that output a value opposite to the majority of input values. The reason for the symmetry breaking in the evolutionary dynamics is found to be due to the need for nodes in finite size networks to behave differently in order to cooperate so that the system collectively performs as efficiently as possible. The results suggest that both finite size effects and symmetry are fundamental for understanding the evolution of real-world complex networks, including genetic regulatory networks.

  2. Density functional approach for pairing in finite size systems

    International Nuclear Information System (INIS)

    Hupin, G.

    2011-09-01

    The combination of functional theory where the energy is written as a functional of the density, and the configuration mixing method, provides an efficient description of nuclear ground and excited state properties. The specific pathologies that have been recently observed, show the lack of a clear underlying justification associated to the breaking and the restoration of symmetries within density functional theory. This thesis focuses on alternative treatments of pairing correlations in finite many body systems that consider the breaking and the restoration of the particle number conservation. The energy is written as a functional of a projected quasi-particle vacuum and can be linked to the one obtained within the configuration mixing framework. This approach has been applied to make the projection either before or after the application of the variational principle. It is more flexible than the usual configuration mixing method since it can handle more general effective interactions than the latter. The application to the Krypton isotopes shows the feasibility and the efficiency of the method to describe pairing near closed shell nuclei. Following a parallel path, a theory where the energy is written as a functional of the occupation number and natural orbitals is proposed. The new functional is benchmarked in an exactly solvable model, the pairing Hamiltonian. The efficiency and the applicability of the new theory have been tested for various pairing strengths, single particle energy spectra and numbers of particles. (author)

  3. The finite-size effect in thin liquid crystal systems

    Science.gov (United States)

    Śliwa, I.

    2018-05-01

    Effects of surface ordering in liquid crystal systems confined between cell plates are of great theoretical and experimental interest. Liquid crystals introduced in thin cells are known to be strongly stabilized and ordered by cell plates. We introduce a new theoretical method for analyzing the effect of surfaces on local molecular ordering in thin liquid crystal systems with planar geometry of the smectic layers. Our results show that, due to the interplay between pair long-range intermolecular forces and nonlocal, relatively short-range, surface interactions, both orientational and translational orders of liquid crystal molecules across confining cells are very complex. In particular, it is demonstrated that the SmA, nematic, and isotropic phases can coexist. The phase transitions from SmA to nematic, as well as from nematic to isotropic phases, occur not simultaneously in the whole volume of the system but begin to appear locally in some regions of the LC sample. Phase transition temperatures are demonstrated to be strongly affected by the thickness of the LC system. The dependence of the corresponding shifts of phase transition temperatures on the layer number is shown to exhibit a power law character. This new type of scaling behavior is concerned with the coexistence of local phases in finite systems. The influence of a specific character of interactions of molecules with surfaces and other molecules on values of the resulting critical exponents is also analyzed.

  4. Discrete and mesoscopic regimes of finite-size wave turbulence

    International Nuclear Information System (INIS)

    L'vov, V. S.; Nazarenko, S.

    2010-01-01

    Bounding volume results in discreteness of eigenmodes in wave systems. This leads to a depletion or complete loss of wave resonances (three-wave, four-wave, etc.), which has a strong effect on wave turbulence (WT) i.e., on the statistical behavior of broadband sets of weakly nonlinear waves. This paper describes three different regimes of WT realizable for different levels of the wave excitations: discrete, mesoscopic and kinetic WT. Discrete WT comprises chaotic dynamics of interacting wave 'clusters' consisting of discrete (often finite) number of connected resonant wave triads (or quarters). Kinetic WT refers to the infinite-box theory, described by well-known wave-kinetic equations. Mesoscopic WT is a regime in which either the discrete and the kinetic evolutions alternate or when none of these two types is purely realized. We argue that in mesoscopic systems the wave spectrum experiences a sandpile behavior. Importantly, the mesoscopic regime is realized for a broad range of wave amplitudes which typically spans over several orders on magnitude, and not just for a particular intermediate level.

  5. An improved Landauer principle with finite-size corrections

    International Nuclear Information System (INIS)

    Reeb, David; Wolf, Michael M

    2014-01-01

    Landauer's principle relates entropy decrease and heat dissipation during logically irreversible processes. Most theoretical justifications of Landauer's principle either use thermodynamic reasoning or rely on specific models based on arguable assumptions. Here, we aim at a general and minimal setup to formulate Landauer's principle in precise terms. We provide a simple and rigorous proof of an improved version of the principle, which is formulated in terms of an equality rather than an inequality. The proof is based on quantum statistical mechanics concepts rather than on thermodynamic argumentation. From this equality version, we obtain explicit improvements of Landauer's bound that depend on the effective size of the thermal reservoir and reduce to Landauer's bound only for infinite-sized reservoirs. (paper)

  6. Finite size melting of spherical solid-liquid aluminium interfaces

    DEFF Research Database (Denmark)

    Chang, J.; Johnson, Erik; Sakai, T.

    2009-01-01

    We have investigated the melting of nano-sized cone shaped aluminium needles coated with amorphous carbon using transmission electron microscopy. The interface between solid and liquid aluminium was found to have spherical topology. For needles with fixed apex angle, the depressed melting tempera...... to the conclusion that the depressed melting temperature is not controlled solely by the inverse radius 1/R. Instead, we found a direct relation between the depressed melting temperature and the ratio between the solid-liquid interface area and the molten volume.......We have investigated the melting of nano-sized cone shaped aluminium needles coated with amorphous carbon using transmission electron microscopy. The interface between solid and liquid aluminium was found to have spherical topology. For needles with fixed apex angle, the depressed melting...

  7. Pyroelectric properties of finite size ferroelectric thin films with structural transition zones

    International Nuclear Information System (INIS)

    Zhou Jing; Lue Tianquan; Sun Punan; Xie Wenguang; Cao Wenwu

    2009-01-01

    A Fermi-type Green's function is used to study pyroelectric properties of the thin film with finite sizes in three dimensions based on a modified transverse Ising model. The results demonstrate that a decrease in the lateral size of the film has a disadvantageous influence on the pyroelectric coefficient of the thin film.

  8. Point source atom interferometry with a cloud of finite size

    Energy Technology Data Exchange (ETDEWEB)

    Hoth, Gregory W., E-mail: gregory.hoth@nist.gov; Pelle, Bruno; Riedl, Stefan; Kitching, John; Donley, Elizabeth A. [National Institute of Standards and Technology, Boulder, Colorado 80305 (United States)

    2016-08-15

    We demonstrate a two axis gyroscope by the use of light pulse atom interferometry with an expanding cloud of atoms in the regime where the cloud has expanded by 1.1–5 times its initial size during the interrogation. Rotations are measured by analyzing spatial fringe patterns in the atom population obtained by imaging the final cloud. The fringes arise from a correlation between an atom's initial velocity and its final position. This correlation is naturally created by the expansion of the cloud, but it also depends on the initial atomic distribution. We show that the frequency and contrast of these spatial fringes depend on the details of the initial distribution and develop an analytical model to explain this dependence. We also discuss several challenges that must be overcome to realize a high-performance gyroscope with this technique.

  9. Geometric measures of multipartite entanglement in finite-size spin chains

    Energy Technology Data Exchange (ETDEWEB)

    Blasone, M; Dell' Anno, F; De Siena, S; Giampaolo, S M; Illuminati, F, E-mail: illuminati@sa.infn.i [Dipartimento di Matematica e Informatica, Universita degli Studi di Salerno, Via Ponte don Melillo, I-84084 Fisciano (Italy)

    2010-09-01

    We investigate the behaviour of multipartite entanglement in finite-size quantum spin systems, resorting to a hierarchy of geometric measures of multipartite entanglement recently introduced in the literature. In particular, we investigate the ground-state entanglement in the XY model defined on finite chains of N sites with periodic boundary conditions. We analyse the behaviour of the geometric measures of (N- 1)-partite and (N/2)-partite entanglement and compare them with the Wei-Goldbart geometric measure of global entanglement.

  10. Geometric measures of multipartite entanglement in finite-size spin chains

    International Nuclear Information System (INIS)

    Blasone, M; Dell'Anno, F; De Siena, S; Giampaolo, S M; Illuminati, F

    2010-01-01

    We investigate the behaviour of multipartite entanglement in finite-size quantum spin systems, resorting to a hierarchy of geometric measures of multipartite entanglement recently introduced in the literature. In particular, we investigate the ground-state entanglement in the XY model defined on finite chains of N sites with periodic boundary conditions. We analyse the behaviour of the geometric measures of (N- 1)-partite and (N/2)-partite entanglement and compare them with the Wei-Goldbart geometric measure of global entanglement.

  11. Ignore and Conquer.

    Science.gov (United States)

    Conroy, Mary

    1989-01-01

    Discusses how teachers can deal with student misbehavior by ignoring negative behavior that is motivated by a desire for attention. Practical techniques are described for pinpointing attention seekers, enlisting classmates to deal with misbehaving students, ignoring misbehavior, and distinguishing behavior that responds to this technique from…

  12. Coulomb systems seen as critical systems: Finite-size effects in two dimensions

    International Nuclear Information System (INIS)

    Jancovici, B.; Manificat, G.; Pisani, C.

    1994-01-01

    It is known that the free energy at criticality of a finite two-dimensional system of characteristic size L has in general a term which behaves like log L as L → ∞; the coefficient of this term is universal. There are solvable models of two-dimensional classical Coulomb systems which exhibit the same finite-size correction (except for its sign) although the particle correlations are short-ranged, i.e., noncritical. Actually, the electrical potential and electrical field correlations are critical at all temperatures (as long as the Coulomb system is a conductor), as a consequence of the perfect screening property of Coulomb systems. This is why Coulomb systems have to exhibit critical finite-size effects

  13. Simulation of the electron acoustic instability for a finite-size electron beam system

    International Nuclear Information System (INIS)

    Lin, C.S.; Winske, D.

    1987-01-01

    Satellite observations at midlatitudes (≅20,000 km) near the earth's dayside polar cusp boundary layer indicate that the upward electron beams have a narrow latitudinal width up to 0.1 0 . In the cusp boundary layer where the electron population consists of a finite-size electron beam in a background of uniform cold and hot electrons, the electron acoustic mode is unstable inside the electron beam but damped outside the electron beam. Simulations of the electron acoustic instability for a finite-size beam system are carried out with a particle-in-cell code to investigate the heating phenomena associated with the instability and the width of the heating region. The simulations show that the finite-size electron beam radiates electrostatic electron acoustic waves. The decay length of the electron acoustic waves outside the beam in the simulation agrees with the spatial decay length derived from the linear dispersion equation

  14. A stochastic-field description of finite-size spiking neural networks.

    Science.gov (United States)

    Dumont, Grégory; Payeur, Alexandre; Longtin, André

    2017-08-01

    Neural network dynamics are governed by the interaction of spiking neurons. Stochastic aspects of single-neuron dynamics propagate up to the network level and shape the dynamical and informational properties of the population. Mean-field models of population activity disregard the finite-size stochastic fluctuations of network dynamics and thus offer a deterministic description of the system. Here, we derive a stochastic partial differential equation (SPDE) describing the temporal evolution of the finite-size refractory density, which represents the proportion of neurons in a given refractory state at any given time. The population activity-the density of active neurons per unit time-is easily extracted from this refractory density. The SPDE includes finite-size effects through a two-dimensional Gaussian white noise that acts both in time and along the refractory dimension. For an infinite number of neurons the standard mean-field theory is recovered. A discretization of the SPDE along its characteristic curves allows direct simulations of the activity of large but finite spiking networks; this constitutes the main advantage of our approach. Linearizing the SPDE with respect to the deterministic asynchronous state allows the theoretical investigation of finite-size activity fluctuations. In particular, analytical expressions for the power spectrum and autocorrelation of activity fluctuations are obtained. Moreover, our approach can be adapted to incorporate multiple interacting populations and quasi-renewal single-neuron dynamics.

  15. Finite size and dynamical effects in pair production by an external field

    International Nuclear Information System (INIS)

    Martin, C.; Vautherin, D.

    1988-12-01

    We evaluate the rate of pair production in a uniform electric field confined into a bounded region in space. Using the Balian-Bloch expansion of Green's functions we obtain explicit expressions for finite size corrections to Schwinger's formula. The case of a time-dependent boundary, relevant to describe energy deposition by quark-antiquark pair production in ultrarelativistic collisions, is also investigated. We find that finite size effects are important in nuclear collisions. They decrease when the strength of the chromo-electric field between the nuclei is large. As a result, the rate of energy deposition increases sharply with the mass number A of the colliding nuclei

  16. Three-point correlation functions of giant magnons with finite size

    International Nuclear Information System (INIS)

    Ahn, Changrim; Bozhilov, Plamen

    2011-01-01

    We compute holographic three-point correlation functions or structure constants of a zero-momentum dilaton operator and two (dyonic) giant magnon string states with a finite-size length in the semiclassical approximation. We show that the semiclassical structure constants match exactly with the three-point functions between two su(2) magnon single trace operators with finite size and the Lagrangian in the large 't Hooft coupling constant limit. A special limit J>>√(λ) of our result is compared with the relevant result based on the Luescher corrections.

  17. Finite-size-scaling analysis of subsystem data in the dilute Ising model

    International Nuclear Information System (INIS)

    Hennecke, M.

    1993-01-01

    Monte Carlo simulation results for the magnetization of subsystems of finite lattices are used to determine the critical temperature and a critical exponent of the simple-cubic Ising model with quenched site dilution, at a concentration of p=40%. Particular attention is paid to the effect of the finite size of the systems from which the subsystem results are obtained. This finiteness of the lattices involved is shown to be a source of large deviations of critical temperatures and exponents estimated from subsystem data from their values in the thermodynamic limit. By the use of different lattice sizes, the results T c (40%)=1.209±0.002 and ν(40%)=0.78±0.01 could be extrapolated

  18. Strategic Self-Ignorance

    DEFF Research Database (Denmark)

    Thunström, Linda; Nordström, Leif Jonas; Shogren, Jason F.

    We examine strategic self-ignorance—the use of ignorance as an excuse to overindulge in pleasurable activities that may be harmful to one’s future self. Our model shows that guilt aversion provides a behavioral rationale for present-biased agents to avoid information about negative future impacts...... of such activities. We then confront our model with data from an experiment using prepared, restaurant-style meals — a good that is transparent in immediate pleasure (taste) but non-transparent in future harm (calories). Our results support the notion that strategic self-ignorance matters: nearly three of five...... subjects (58 percent) chose to ignore free information on calorie content, leading at-risk subjects to consume significantly more calories. We also find evidence consistent with our model on the determinants of strategic self-ignorance....

  19. Strategic self-ignorance

    DEFF Research Database (Denmark)

    Thunström, Linda; Nordström, Leif Jonas; Shogren, Jason F.

    2016-01-01

    We examine strategic self-ignorance—the use of ignorance as an excuse to over-indulge in pleasurable activities that may be harmful to one’s future self. Our model shows that guilt aversion provides a behavioral rationale for present-biased agents to avoid information about negative future impacts...... of such activities. We then confront our model with data from an experiment using prepared, restaurant-style meals—a good that is transparent in immediate pleasure (taste) but non-transparent in future harm (calories). Our results support the notion that strategic self-ignorance matters: nearly three of five...... subjects (58%) chose to ignore free information on calorie content, leading at-risk subjects to consume significantly more calories. We also find evidence consistent with our model on the determinants of strategic self-ignorance....

  20. Ignorance, information and autonomy

    OpenAIRE

    Harris, J.; Keywood, K.

    2001-01-01

    People have a powerful interest in genetic privacy and its associated claim to ignorance, and some equally powerful desires to be shielded from disturbing information are often voiced. We argue, however, that there is no such thing as a right to remain in ignorance, where a right is understood as an entitlement that trumps competing claims. This does not of course mean that information must always be forced upon unwilling recipients, only that there is no prima facie entitlement to be protect...

  1. Percolation through voids around overlapping spheres: A dynamically based finite-size scaling analysis

    Science.gov (United States)

    Priour, D. J.

    2014-01-01

    The percolation threshold for flow or conduction through voids surrounding randomly placed spheres is calculated. With large-scale Monte Carlo simulations, we give a rigorous continuum treatment to the geometry of the impenetrable spheres and the spaces between them. To properly exploit finite-size scaling, we examine multiple systems of differing sizes, with suitable averaging over disorder, and extrapolate to the thermodynamic limit. An order parameter based on the statistical sampling of stochastically driven dynamical excursions and amenable to finite-size scaling analysis is defined, calculated for various system sizes, and used to determine the critical volume fraction ϕc=0.0317±0.0004 and the correlation length exponent ν =0.92±0.05.

  2. Clash of Ignorance

    Directory of Open Access Journals (Sweden)

    Mahmoud Eid

    2012-06-01

    Full Text Available The clash of ignorance thesis presents a critique of the clash of civilizations theory. It challenges the assumptions that civilizations are monolithic entities that do not interact and that the Self and the Other are always opposed to each other. Despite some significantly different values and clashes between Western and Muslim civilizations, they overlap with each other in many ways and have historically demonstrated the capacity for fruitful engagement. The clash of ignorance thesis makes a significant contribution to the understanding of intercultural and international communication as well as to the study of inter-group relations in various other areas of scholarship. It does this by bringing forward for examination the key impediments to mutually beneficial interaction between groups. The thesis directly addresses the particular problem of ignorance that other epistemological approaches have not raised in a substantial manner. Whereas the critique of Orientalism deals with the hegemonic construction of knowledge, the clash of ignorance paradigm broadens the inquiry to include various actors whose respective distortions of knowledge symbiotically promote conflict with each other. It also augments the power-knowledge model to provide conceptual and analytical tools for understanding the exploitation of ignorance for the purposes of enhancing particular groups’ or individuals’ power. Whereas academics, policymakers, think tanks, and religious leaders have referred to the clash of ignorance concept, this essay contributes to its development as a theory that is able to provide a valid basis to explain the empirical evidence drawn from relevant cases.

  3. Finite-size corrections to the free energies of crystalline solids

    NARCIS (Netherlands)

    Polson, J.M.; Trizac, E.; Pronk, S.; Frenkel, D.

    2000-01-01

    We analyze the finite-size corrections to the free energy of crystals with a fixed center of mass. When we explicitly correct for the leading (ln N/N) corrections, the remaining free energy is found to depend linearly on 1/N. Extrapolating to the thermodynamic limit (N → ∞), we estimate the free

  4. Solving wave propagation within finite-sized composite media with linear embedding via Green's operators

    NARCIS (Netherlands)

    Lancellotti, V.; Tijhuis, A.G.

    2012-01-01

    The calculation of electromagnetic (EM) fields and waves inside finite-sized structures comprised of different media can benefit from a diakoptics method such as linear embedding via Green's operators (LEGO). Unlike scattering problems, the excitation of EM waves within the bulk dielectric requires

  5. A finite size scaling test of an SU(2) gauge-spin system

    International Nuclear Information System (INIS)

    Tomiya, M.; Hattori, T.

    1984-01-01

    We calculate the correlation functions in the SU(2) gauge-spin system with spins in the fundamental representation. We analyze the result making use of finite size scaling. There is a possibility that there are no second order phase transition lines in this model, contrary to previous assertions. (orig.)

  6. Exploiting finite-size-effects to simulate full QCD with light quarks - a progress report

    International Nuclear Information System (INIS)

    Orth, B.; Eicker, N.; Lippert, Th.; Schilling, K.; Schroers, W.; Sroczynski, Z.

    2002-01-01

    We present a report on the status of the GRAL project (Going Realistic And Light), which aims at simulating full QCD with two dynamical Wilson quarks below the vector meson decay threshold, m ps /m v < 0.5, making use of finite-size-scaling techniques

  7. Finite size effects in the evaporation rate of 3He clusters

    International Nuclear Information System (INIS)

    Guirao, A.; Pi, M.; Barranco, M.

    1991-01-01

    We have computed the density of states and the evaporation rate of 3 He clusters, paying special attention to finite size effects which modify the 3 He level density parameter and chemical potential from their bulk values. Ready-to-use liquid-drop expansions of these quantities are given. (orig.)

  8. Acceleration statistics of finite-sized particles in turbulent flow: the role of Faxen forces

    OpenAIRE

    Calzavarini, Enrico; Volk, Romain; Bourgoin, Mickael; Leveque, Emmanuel; Pinton, Jean-Francois; Toschi, Federico

    2008-01-01

    International audience; The dynamics of particles in turbulence when the particle size is larger than the dissipative scale of the carrier flow are studied. Recent experiments have highlighted signatures of particles' finiteness on their statistical properties, namely a decrease of their acceleration variance, an increase of correlation times (at increasing the particles size) and an independence of the probability density function of the acceleration once normalized to their variance. These ...

  9. Effects of diffraction and target finite size on coherent transition radiation spectra in bunch length measurements

    Energy Technology Data Exchange (ETDEWEB)

    Castellano, M.; Cianchi, A.; Verzilov, V.A. [Istituto Nazionale di Fisica Nucleare, Frascati, RM (Italy). Laboratori Nazionali di Frascati; Orlandi, G. [Istituto Nazionale di Fisica Nucleare, Rome (Italy)]|[Rome Univ., Tor Vergata, Rome (Italy)

    1999-07-01

    Effects of diffraction and the size of the target on TR in the context of CTR-based bunch length measurements are studied on the basis of Kirchhoff diffraction theory. Spectra of TR from the finite-size target for several schemes of measurements are calculated in the far-infrared region showing strong distortion at low frequencies. Influence of the effect on the accuracy of bunch length measurements is estimated.

  10. Transient hydrodynamic finite-size effects in simulations under periodic boundary conditions

    Science.gov (United States)

    Asta, Adelchi J.; Levesque, Maximilien; Vuilleumier, Rodolphe; Rotenberg, Benjamin

    2017-06-01

    We use lattice-Boltzmann and analytical calculations to investigate transient hydrodynamic finite-size effects induced by the use of periodic boundary conditions. These effects are inevitable in simulations at the molecular, mesoscopic, or continuum levels of description. We analyze the transient response to a local perturbation in the fluid and obtain the local velocity correlation function via linear response theory. This approach is validated by comparing the finite-size effects on the steady-state velocity with the known results for the diffusion coefficient. We next investigate the full time dependence of the local velocity autocorrelation function. We find at long times a crossover between the expected t-3 /2 hydrodynamic tail and an oscillatory exponential decay, and study the scaling with the system size of the crossover time, exponential rate and amplitude, and oscillation frequency. We interpret these results from the analytic solution of the compressible Navier-Stokes equation for the slowest modes, which are set by the system size. The present work not only provides a comprehensive analysis of hydrodynamic finite-size effects in bulk fluids, which arise regardless of the level of description and simulation algorithm, but also establishes the lattice-Boltzmann method as a suitable tool to investigate such effects in general.

  11. Finite size effects on the helical edge states on the Lieb lattice

    International Nuclear Information System (INIS)

    Chen Rui; Zhou Bin

    2016-01-01

    For a two-dimensional Lieb lattice, that is, a line-centered square lattice, the inclusion of the intrinsic spin–orbit (ISO) coupling opens a topologically nontrivial gap, and gives rise to the quantum spin Hall (QSH) effect characterized by two pairs of gapless helical edge states within the bulk gap. Generally, due to the finite size effect in QSH systems, the edge states on the two sides of a strip of finite width can couple together to open a gap in the spectrum. In this paper, we investigate the finite size effect of helical edge states on the Lieb lattice with ISO coupling under three different kinds of boundary conditions, i.e., the straight, bearded and asymmetry edges. The spectrum and wave function of edge modes are derived analytically for a tight-binding model on the Lieb lattice. For a strip Lieb lattice with two straight edges, the ISO coupling induces the Dirac-like bulk states to localize at the edges to become the helical edge states with the same Dirac-like spectrum. Moreover, it is found that in the case with two straight edges the gapless Dirac-like spectrum remains unchanged with decreasing the width of the strip Lieb lattice, and no gap is opened in the edge band. It is concluded that the finite size effect of QSH states is absent in the case with the straight edges. However, in the other two cases with the bearded and asymmetry edges, the energy gap induced by the finite size effect is still opened with decreasing the width of the strip. It is also proposed that the edge band dispersion can be controlled by applying an on-site potential energy on the outermost atoms. (paper)

  12. Finite-key-size effect in a commercial plug-and-play QKD system

    Science.gov (United States)

    Chaiwongkhot, Poompong; Sajeed, Shihan; Lydersen, Lars; Makarov, Vadim

    2017-12-01

    A security evaluation against the finite-key-size effect was performed for a commercial plug-and-play quantum key distribution (QKD) system. We demonstrate the ability of an eavesdropper to force the system to distill key from a smaller length of sifted-key. We also derive a key-rate equation that is specific for this system. This equation provides bounds above the upper bound of secure key under finite-key-size analysis. From this equation and our experimental data, we show that the keys that have been distilled from the smaller sifted-key size fall above our bound. Thus, their security is not covered by finite-key-size analysis. Experimentally, we could consistently force the system to generate the key outside of the bound. We also test manufacturer’s software update. Although all the keys after the patch fall under our bound, their security cannot be guaranteed under this analysis. Our methodology can be used for security certification and standardization of QKD systems.

  13. Ignorance, information and autonomy.

    Science.gov (United States)

    Harris, J; Keywood, K

    2001-09-01

    People have a powerful interest in genetic privacy and its associated claim to ignorance, and some equally powerful desires to be shielded from disturbing information are often voiced. We argue, however, that there is no such thing as a right to remain in ignorance, where a fight is understood as an entitlement that trumps competing claims. This does not of course mean that information must always be forced upon unwilling recipients, only that there is no prima facie entitlement to be protected from true or honest information about oneself. Any claims to be shielded from information about the self must compete on equal terms with claims based in the rights and interests of others. In balancing the weight and importance of rival considerations about giving or withholding information, if rights claims have any place, rights are more likely to be defensible on the side of honest communication of information rather than in defence of ignorance. The right to free speech and the right to decline to accept responsibility to take decisions for others imposed by those others seem to us more plausible candidates for fully fledged rights in this field than any purported right to ignorance. Finally, and most importantly, if the right to autonomy is invoked, a proper understanding of the distinction between claims to liberty and claims to autonomy show that the principle of autonomy, as it is understood in contemporary social ethics and English law, supports the giving rather than the withholding of information in most circumstances.

  14. Finite-time and finite-size scalings in the evaluation of large-deviation functions: Numerical approach in continuous time.

    Science.gov (United States)

    Guevara Hidalgo, Esteban; Nemoto, Takahiro; Lecomte, Vivien

    2017-06-01

    Rare trajectories of stochastic systems are important to understand because of their potential impact. However, their properties are by definition difficult to sample directly. Population dynamics provides a numerical tool allowing their study, by means of simulating a large number of copies of the system, which are subjected to selection rules that favor the rare trajectories of interest. Such algorithms are plagued by finite simulation time and finite population size, effects that can render their use delicate. In this paper, we present a numerical approach which uses the finite-time and finite-size scalings of estimators of the large deviation functions associated to the distribution of rare trajectories. The method we propose allows one to extract the infinite-time and infinite-size limit of these estimators, which-as shown on the contact process-provides a significant improvement of the large deviation function estimators compared to the standard one.

  15. Finite-time and finite-size scalings in the evaluation of large-deviation functions: Numerical approach in continuous time

    Science.gov (United States)

    Guevara Hidalgo, Esteban; Nemoto, Takahiro; Lecomte, Vivien

    2017-06-01

    Rare trajectories of stochastic systems are important to understand because of their potential impact. However, their properties are by definition difficult to sample directly. Population dynamics provides a numerical tool allowing their study, by means of simulating a large number of copies of the system, which are subjected to selection rules that favor the rare trajectories of interest. Such algorithms are plagued by finite simulation time and finite population size, effects that can render their use delicate. In this paper, we present a numerical approach which uses the finite-time and finite-size scalings of estimators of the large deviation functions associated to the distribution of rare trajectories. The method we propose allows one to extract the infinite-time and infinite-size limit of these estimators, which—as shown on the contact process—provides a significant improvement of the large deviation function estimators compared to the standard one.

  16. Asymptotic investigation of the nonlinear boundary value dynamic problem for the systems with finite sizes

    International Nuclear Information System (INIS)

    Andrianov, I.V.; Danishevsky, V.V.

    1994-01-01

    Asymptotic approaches for nonlinear dynamics of continual system are developed well for the infinite in spatial variables. For the systems with finite sizes we have an infinite number of resonance, and Poincare-Lighthill-Go method does riot work. Using of averaging procedure or method of multiple scales leads to the infinite systems of nonlinear algebraic or ordinary differential equations systems and then using truncation method. which does not gives possibility to obtain all important properties of the solutions

  17. The King model for electrons in a finite-size ultracold plasma

    Energy Technology Data Exchange (ETDEWEB)

    Vrinceanu, D; Collins, L A [Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Balaraman, G S [School of Physics, Georgia Institute of Technology, Atlanta, GA 30332 (United States)

    2008-10-24

    A self-consistent model for a finite-size non-neutral ultracold plasma is obtained by extending a conventional model of globular star clusters. This model describes the dynamics of electrons at quasi-equilibrium trapped within the potential created by a cloud of stationary ions. A random sample of electron positions and velocities can be generated with the statistical properties defined by this model.

  18. Many-body localization in disorder-free systems: The importance of finite-size constraints

    Energy Technology Data Exchange (ETDEWEB)

    Papić, Z., E-mail: zpapic@perimeterinstitute.ca [School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT (United Kingdom); Perimeter Institute for Theoretical Physics, Waterloo, ON N2L 2Y5 (Canada); Stoudenmire, E. Miles [Perimeter Institute for Theoretical Physics, Waterloo, ON N2L 2Y5 (Canada); Abanin, Dmitry A. [Department of Theoretical Physics, University of Geneva, 24 quai Ernest-Ansermet, 1211 Geneva (Switzerland); Perimeter Institute for Theoretical Physics, Waterloo, ON N2L 2Y5 (Canada)

    2015-11-15

    Recently it has been suggested that many-body localization (MBL) can occur in translation-invariant systems, and candidate 1D models have been proposed. We find that such models, in contrast to MBL systems with quenched disorder, typically exhibit much more severe finite-size effects due to the presence of two or more vastly different energy scales. In a finite system, this can artificially split the density of states (DOS) into bands separated by large gaps. We argue for such models to faithfully represent the thermodynamic limit behavior, the ratio of relevant coupling must exceed a certain system-size depedent cutoff, chosen such that various bands in the DOS overlap one another. Setting the parameters this way to minimize finite-size effects, we study several translation-invariant MBL candidate models using exact diagonalization. Based on diagnostics including entanglement and local observables, we observe thermal (ergodic), rather than MBL-like behavior. Our results suggest that MBL in translation-invariant systems with two or more very different energy scales is less robust than perturbative arguments suggest, possibly pointing to the importance of non-perturbative effects which induce delocalization in the thermodynamic limit.

  19. Towards a theory of cortical columns: From spiking neurons to interacting neural populations of finite size

    Science.gov (United States)

    Gerstner, Wulfram

    2017-01-01

    Neural population equations such as neural mass or field models are widely used to study brain activity on a large scale. However, the relation of these models to the properties of single neurons is unclear. Here we derive an equation for several interacting populations at the mesoscopic scale starting from a microscopic model of randomly connected generalized integrate-and-fire neuron models. Each population consists of 50–2000 neurons of the same type but different populations account for different neuron types. The stochastic population equations that we find reveal how spike-history effects in single-neuron dynamics such as refractoriness and adaptation interact with finite-size fluctuations on the population level. Efficient integration of the stochastic mesoscopic equations reproduces the statistical behavior of the population activities obtained from microscopic simulations of a full spiking neural network model. The theory describes nonlinear emergent dynamics such as finite-size-induced stochastic transitions in multistable networks and synchronization in balanced networks of excitatory and inhibitory neurons. The mesoscopic equations are employed to rapidly integrate a model of a cortical microcircuit consisting of eight neuron types, which allows us to predict spontaneous population activities as well as evoked responses to thalamic input. Our theory establishes a general framework for modeling finite-size neural population dynamics based on single cell and synapse parameters and offers an efficient approach to analyzing cortical circuits and computations. PMID:28422957

  20. Exchange bias in finite sized NiO nanoparticles with Ni clusters

    Energy Technology Data Exchange (ETDEWEB)

    Gandhi, Ashish Chhaganlal; Lin, Jauyn Grace, E-mail: jglin@ntu.edu.tw

    2017-02-15

    Structural and magnetic properties of finite sized NiO nanoparticles are investigated with synchrotron X-ray diffraction (XRD), transmission electron microscopy, magnetometer and ferromagnetic resonance (FMR) spectroscopy. A minor Ni phase is detected with synchrotron XRD, attributed to the oxygen defects in the NiO core. A considerable exchange bias of ~100 Oe is observed at 50 K and it drops abruptly and vanishes above 150 K, in association with the reduction of frozen spins. FMR data indicate a strong interaction between ferromagnetic (FM) and antiferromagnetic (AFM) phases below 150 K, consistent with the picture of isolated FM clusters in AFM matrix. - Highlights: • Structural and magnetic properties of finite sized NiO nanoparticles are systematically investigated with several advanced techniques. • A strong interaction between ferromagnetic and antiferromagnetic phases is found below 150 K. • Exchange bias field in finite sized NiO nanoparticles is due to anisotropy energy of Ni clusters over riding the domain wall energy of NiO.

  1. Towards a theory of cortical columns: From spiking neurons to interacting neural populations of finite size.

    Science.gov (United States)

    Schwalger, Tilo; Deger, Moritz; Gerstner, Wulfram

    2017-04-01

    Neural population equations such as neural mass or field models are widely used to study brain activity on a large scale. However, the relation of these models to the properties of single neurons is unclear. Here we derive an equation for several interacting populations at the mesoscopic scale starting from a microscopic model of randomly connected generalized integrate-and-fire neuron models. Each population consists of 50-2000 neurons of the same type but different populations account for different neuron types. The stochastic population equations that we find reveal how spike-history effects in single-neuron dynamics such as refractoriness and adaptation interact with finite-size fluctuations on the population level. Efficient integration of the stochastic mesoscopic equations reproduces the statistical behavior of the population activities obtained from microscopic simulations of a full spiking neural network model. The theory describes nonlinear emergent dynamics such as finite-size-induced stochastic transitions in multistable networks and synchronization in balanced networks of excitatory and inhibitory neurons. The mesoscopic equations are employed to rapidly integrate a model of a cortical microcircuit consisting of eight neuron types, which allows us to predict spontaneous population activities as well as evoked responses to thalamic input. Our theory establishes a general framework for modeling finite-size neural population dynamics based on single cell and synapse parameters and offers an efficient approach to analyzing cortical circuits and computations.

  2. Exchange bias in finite sized NiO nanoparticles with Ni clusters

    International Nuclear Information System (INIS)

    Gandhi, Ashish Chhaganlal; Lin, Jauyn Grace

    2017-01-01

    Structural and magnetic properties of finite sized NiO nanoparticles are investigated with synchrotron X-ray diffraction (XRD), transmission electron microscopy, magnetometer and ferromagnetic resonance (FMR) spectroscopy. A minor Ni phase is detected with synchrotron XRD, attributed to the oxygen defects in the NiO core. A considerable exchange bias of ~100 Oe is observed at 50 K and it drops abruptly and vanishes above 150 K, in association with the reduction of frozen spins. FMR data indicate a strong interaction between ferromagnetic (FM) and antiferromagnetic (AFM) phases below 150 K, consistent with the picture of isolated FM clusters in AFM matrix. - Highlights: • Structural and magnetic properties of finite sized NiO nanoparticles are systematically investigated with several advanced techniques. • A strong interaction between ferromagnetic and antiferromagnetic phases is found below 150 K. • Exchange bias field in finite sized NiO nanoparticles is due to anisotropy energy of Ni clusters over riding the domain wall energy of NiO.

  3. Finite-size scaling of clique percolation on two-dimensional Moore lattices

    Science.gov (United States)

    Dong, Jia-Qi; Shen, Zhou; Zhang, Yongwen; Huang, Zi-Gang; Huang, Liang; Chen, Xiaosong

    2018-05-01

    Clique percolation has attracted much attention due to its significance in understanding topological overlap among communities and dynamical instability of structured systems. Rich critical behavior has been observed in clique percolation on Erdős-Rényi (ER) random graphs, but few works have discussed clique percolation on finite dimensional systems. In this paper, we have defined a series of characteristic events, i.e., the historically largest size jumps of the clusters, in the percolating process of adding bonds and developed a new finite-size scaling scheme based on the interval of the characteristic events. Through the finite-size scaling analysis, we have found, interestingly, that, in contrast to the clique percolation on an ER graph where the critical exponents are parameter dependent, the two-dimensional (2D) clique percolation simply shares the same critical exponents with traditional site or bond percolation, independent of the clique percolation parameters. This has been corroborated by bridging two special types of clique percolation to site percolation on 2D lattices. Mechanisms for the difference of the critical behaviors between clique percolation on ER graphs and on 2D lattices are also discussed.

  4. Precision of quantization of the hall conductivity in a finite-size sample: Power law

    International Nuclear Information System (INIS)

    Greshnov, A. A.; Kolesnikova, E. N.; Zegrya, G. G.

    2006-01-01

    A microscopic calculation of the conductivity in the integer quantum Hall effect (IQHE) mode is carried out. The precision of quantization is analyzed for finite-size samples. The precision of quantization shows a power-law dependence on the sample size. A new scaling parameter describing this dependence is introduced. It is also demonstrated that the precision of quantization linearly depends on the ratio between the amplitude of the disorder potential and the cyclotron energy. The data obtained are compared with the results of magnetotransport measurements in mesoscopic samples

  5. The virtues of ignorance.

    Science.gov (United States)

    Son, Lisa K; Kornell, Nate

    2010-02-01

    Although ignorance and uncertainty are usually unwelcome feelings, they have unintuitive advantages for both human and non-human animals, which we review here. We begin with the perils of too much information: expertise and knowledge can come with illusions (and delusions) of knowing. We then describe how withholding information can counteract these perils: providing people with less information enables them to judge more precisely what they know and do not know, which in turn enhances long-term memory. Data are presented from a new experiment that illustrates how knowing what we do not know can result in helpful choices and enhanced learning. We conclude by showing that ignorance can be a virtue, as long as it is recognized and rectified. Copyright 2009 Elsevier B.V. All rights reserved.

  6. Evaluation of Kirkwood-Buff integrals via finite size scaling: a large scale molecular dynamics study

    Science.gov (United States)

    Dednam, W.; Botha, A. E.

    2015-01-01

    Solvation of bio-molecules in water is severely affected by the presence of co-solvent within the hydration shell of the solute structure. Furthermore, since solute molecules can range from small molecules, such as methane, to very large protein structures, it is imperative to understand the detailed structure-function relationship on the microscopic level. For example, it is useful know the conformational transitions that occur in protein structures. Although such an understanding can be obtained through large-scale molecular dynamic simulations, it is often the case that such simulations would require excessively large simulation times. In this context, Kirkwood-Buff theory, which connects the microscopic pair-wise molecular distributions to global thermodynamic properties, together with the recently developed technique, called finite size scaling, may provide a better method to reduce system sizes, and hence also the computational times. In this paper, we present molecular dynamics trial simulations of biologically relevant low-concentration solvents, solvated by aqueous co-solvent solutions. In particular we compare two different methods of calculating the relevant Kirkwood-Buff integrals. The first (traditional) method computes running integrals over the radial distribution functions, which must be obtained from large system-size NVT or NpT simulations. The second, newer method, employs finite size scaling to obtain the Kirkwood-Buff integrals directly by counting the particle number fluctuations in small, open sub-volumes embedded within a larger reservoir that can be well approximated by a much smaller simulation cell. In agreement with previous studies, which made a similar comparison for aqueous co-solvent solutions, without the additional solvent, we conclude that the finite size scaling method is also applicable to the present case, since it can produce computationally more efficient results which are equivalent to the more costly radial distribution

  7. Evaluation of Kirkwood-Buff integrals via finite size scaling: a large scale molecular dynamics study

    International Nuclear Information System (INIS)

    Dednam, W; Botha, A E

    2015-01-01

    Solvation of bio-molecules in water is severely affected by the presence of co-solvent within the hydration shell of the solute structure. Furthermore, since solute molecules can range from small molecules, such as methane, to very large protein structures, it is imperative to understand the detailed structure-function relationship on the microscopic level. For example, it is useful know the conformational transitions that occur in protein structures. Although such an understanding can be obtained through large-scale molecular dynamic simulations, it is often the case that such simulations would require excessively large simulation times. In this context, Kirkwood-Buff theory, which connects the microscopic pair-wise molecular distributions to global thermodynamic properties, together with the recently developed technique, called finite size scaling, may provide a better method to reduce system sizes, and hence also the computational times. In this paper, we present molecular dynamics trial simulations of biologically relevant low-concentration solvents, solvated by aqueous co-solvent solutions. In particular we compare two different methods of calculating the relevant Kirkwood-Buff integrals. The first (traditional) method computes running integrals over the radial distribution functions, which must be obtained from large system-size NVT or NpT simulations. The second, newer method, employs finite size scaling to obtain the Kirkwood-Buff integrals directly by counting the particle number fluctuations in small, open sub-volumes embedded within a larger reservoir that can be well approximated by a much smaller simulation cell. In agreement with previous studies, which made a similar comparison for aqueous co-solvent solutions, without the additional solvent, we conclude that the finite size scaling method is also applicable to the present case, since it can produce computationally more efficient results which are equivalent to the more costly radial distribution

  8. Finite-size effects on band structure of CdS nanocrystallites studied by positron annihilation

    International Nuclear Information System (INIS)

    Kar, Soumitra; Biswas, Subhajit; Chaudhuri, Subhadra; Nambissan, P.M.G.

    2005-01-01

    Quantum confinement effects in nanocrystalline CdS were studied using positrons as spectroscopic probes to explore the defect characteristics. The lifetime of positrons annihilating at the vacancy clusters on nanocrystalline grain surfaces increased remarkably consequent to the onset of such finite-size effects. The Doppler broadened line shape was also found to reflect rather sensitively such distinct changes in the electron momentum redistribution scanned by the positrons, owing to the widening of the band gap. The nanocrystalline sizes of the samples used were confirmed from x-ray diffraction and high resolution transmission electron microscopy and the optical absorption results supported the quantum size effects. Positron annihilation results indicated distinct qualitative changes between CdS nanorods and the bulk sample, notwithstanding the identical x-ray diffraction pattern and close resemblance of the optical absorption spectra. The results are promising in the event of positron annihilation being proved to be a very successful tool for the study of such finite-size effects in semiconductor nanoparticles

  9. Finite-size effects on two-particle production in continuous and discrete spectrum

    CERN Document Server

    Lednicky, R

    2005-01-01

    The effect of a finite space-time extent of particle production region on the lifetime measurement of hadronic atoms produced by a high energy beam in a thin target is discussed. Particularly, it is found that the neglect of this effect on the pionium lifetime measurement in the experiment DIRAC at CERN could lead to the lifetime overestimation on the level of the expected 10% statistical error. It is argued that the data on correlations of identical particles obtained in the same experimental conditions, together with transport code simulation, allow to diminish the systematic error in the extracted lifetime to an acceptable level. The theoretical systematic errors arising in the calculation of the finite-size effect due to the neglect of non-equal emission times in the pair c.m.s., the space-time coherence and the residual charge are shown to be negligible.

  10. Pairing mechanism in Bi-O superconductors: A finite-size chain calculation

    International Nuclear Information System (INIS)

    Aligia, A.A.; Nunez Regueiro, M.D.; Gagliano, E.R.

    1989-01-01

    We have studied the pairing mechanism in BiO 3 systems by calculating the binding energy of a pair of holes in finite Bi-O chains, for parameters that simulate three-dimensional behavior. In agreement with previous results using perturbation theory in the hopping t, for covalent Bi-O binding and parameters for which the parent compound has a disproportionate ground state, pairing induced by the presence of biexcitons is obtained for sufficiently large interatomic Coulomb repulsion. The analysis of appropriate correlation functions shows a rapid metallization of the system as t and the number of holes increase. This fact shrinks the region of parameters for which the finite-size calculations can be trusted without further study. The same model for other parameters yields pairing in two other regimes: bipolaronic and magnetic excitonic

  11. Investigating size effects of complex nanostructures through Young-Laplace equation and finite element analysis

    International Nuclear Information System (INIS)

    Lu, Dingjie; Xie, Yi Min; Huang, Xiaodong; Zhou, Shiwei; Li, Qing

    2015-01-01

    Analytical studies on the size effects of a simply-shaped beam fixed at both ends have successfully explained the sudden changes of effective Young's modulus as its diameter decreases below 100 nm. Yet they are invalid for complex nanostructures ubiquitously existing in nature. In accordance with a generalized Young-Laplace equation, one of the representative size effects is transferred to non-uniformly distributed pressure against an external surface due to the imbalance of inward and outward loads. Because the magnitude of pressure depends on the principal curvatures, iterative steps have to be adopted to gradually stabilize the structure in finite element analysis. Computational results are in good agreement with both experiment data and theoretical prediction. Furthermore, the investigation on strengthened and softened Young's modulus for two complex nanostructures demonstrates that the proposed computational method provides a general and effective approach to analyze the size effects for nanostructures in arbitrary shape

  12. Thermodynamic theory of intrinsic finite-size effects in PbTiO3 nanocrystals. I. Nanoparticle size-dependent tetragonal phase stability

    Science.gov (United States)

    Akdogan, E. K.; Safari, A.

    2007-03-01

    We propose a phenomenological intrinsic finite-size effect model for single domain, mechanically free, and surface charge compensated ΔG-P ⃗s-ξ space, which describes the decrease in tetragonal phase stability with decreasing ξ rigorously.

  13. Directional anisotropy, finite size effect and elastic properties of hexagonal boron nitride

    International Nuclear Information System (INIS)

    Thomas, Siby; Ajith, K M; Valsakumar, M C

    2016-01-01

    Classical molecular dynamics simulations have been performed to analyze the elastic and mechanical properties of two-dimensional (2D) hexagonal boron nitride (h-BN) using a Tersoff-type interatomic empirical potential. We present a systematic study of h-BN for various system sizes. Young’s modulus and Poisson’s ratio are found to be anisotropic for finite sheets whereas they are isotropic for the infinite sheet. Both of them increase with system size in accordance with a power law. It is concluded from the computed values of elastic constants that h-BN sheets, finite or infinite, satisfy Born’s criterion for mechanical stability. Due to the the strong in-plane sp 2 bonds and the small mass of boron and nitrogen atoms, h-BN possesses high longitudinal and shear velocities. The variation of bending rigidity with system size is calculated using the Foppl–von Karman approach by coupling the in-plane bending and out-of-plane stretching modes of the 2D h-BN. (paper)

  14. Finite-size effect and the components of multifractality in financial volatility

    International Nuclear Information System (INIS)

    Zhou Weixing

    2012-01-01

    Highlights: ► The apparent multifractality can be decomposed quantitatively. ► There is a marked finite-size effect in the detection of multifractality. ► The effective multifractality can be further decomposed into two components. ► A time series exhibits effective multifractality only if it possesses nonlinearity. ► The daily DJIA volatility is analyzed as an example. - Abstract: Many financial variables are found to exhibit multifractal nature, which is usually attributed to the influence of temporal correlations and fat-tailedness in the probability distribution (PDF). Based on the partition function approach of multifractal analysis, we show that there is a marked finite-size effect in the detection of multifractality, and the effective multifractality is the apparent multifractality after removing the finite-size effect. We find that the effective multifractality can be further decomposed into two components, the PDF component and the nonlinearity component. Referring to the normal distribution, we can determine the PDF component by comparing the effective multifractality of the original time series and the surrogate data that have a normal distribution and keep the same linear and nonlinear correlations as the original data. We demonstrate our method by taking the daily volatility data of Dow Jones Industrial Average from 26 May 1896 to 27 April 2007 as an example. Extensive numerical experiments show that a time series exhibits effective multifractality only if it possesses nonlinearity and the PDF has an impact on the effective multifractality only when the time series possesses nonlinearity. Our method can also be applied to judge the presence of multifractality and determine its components of multifractal time series in other complex systems.

  15. Fermi surface of the one-dimensional Hubbard model. Finite-size effects

    Energy Technology Data Exchange (ETDEWEB)

    Bourbonnais, C.; Nelisse, H.; Reid, A.; Tremblay, A.M.S. (Dept. de Physique and Centre de Recherche en Physique du Solide (C.R.P.S.), Univ. de Sherbrooke, Quebec (Canada))

    1989-12-01

    The results reported here, using a standard numerical algorithm and a simple low temperature extrapolation, appear consistent with numerical results of Sorella et al. for the one-dimensional Hubbard model in the half-filled and quarter-filled band cases. However, it is argued that the discontinuity at the Fermi level found in the quarter-filled case is likely to come from the zero-temperature finite-size dependence of the quasiparticle weight Z, which is also discussed here. (orig.).

  16. Finite-Size Effects in Single Chain Magnets: An Experimental and Theoretical Study

    Science.gov (United States)

    Bogani, L.; Caneschi, A.; Fedi, M.; Gatteschi, D.; Massi, M.; Novak, M. A.; Pini, M. G.; Rettori, A.; Sessoli, R.; Vindigni, A.

    2004-05-01

    The problem of finite-size effects in s=1/2 Ising systems showing slow dynamics of the magnetization is investigated introducing diamagnetic impurities in a Co2+-radical chain. The static magnetic properties have been measured and analyzed considering the peculiarities induced by the ferrimagnetic character of the compound. The dynamic susceptibility shows that an Arrhenius law is observed with the same energy barrier for the pure and the doped compounds while the prefactor decreases, as theoretically predicted. Multiple spin reversal has also been investigated.

  17. Finite-size effects and switching times for Moran process with mutation.

    Science.gov (United States)

    DeVille, Lee; Galiardi, Meghan

    2017-04-01

    We consider the Moran process with two populations competing under an iterated Prisoner's Dilemma in the presence of mutation, and concentrate on the case where there are multiple evolutionarily stable strategies. We perform a complete bifurcation analysis of the deterministic system which arises in the infinite population size. We also study the Master equation and obtain asymptotics for the invariant distribution and metastable switching times for the stochastic process in the case of large but finite population. We also show that the stochastic system has asymmetries in the form of a skew for parameter values where the deterministic limit is symmetric.

  18. Finite Size Effects in Submonolayer Catalysts Investigated by CO Electrosorption on PtsML/Pd(100).

    Science.gov (United States)

    Yuan, Qiuyi; Doan, Hieu A; Grabow, Lars C; Brankovic, Stanko R

    2017-10-04

    A combination of scanning tunneling microscopy, subtractively normalized interfacial Fourier transform infrared spectroscopy (SNIFTIRS), and density functional theory (DFT) is used to quantify the local strain in 2D Pt clusters on the 100 facet of Pd and its effect on CO chemisorption. Good agreement between SNIFTIRS experiments and DFT simulations provide strong evidence that, in the absence of coherent strain between Pt and Pd, finite size effects introduce local compressive strain, which alters the chemisorption properties of the surface. Though this effect has been widely neglected in prior studies, our results suggest that accurate control over cluster sizes in submonolayer catalyst systems can be an effective approach to fine-tune their catalytic properties.

  19. Wake-Driven Dynamics of Finite-Sized Buoyant Spheres in Turbulence

    Science.gov (United States)

    Mathai, Varghese; Prakash, Vivek N.; Brons, Jon; Sun, Chao; Lohse, Detlef

    2015-09-01

    Particles suspended in turbulent flows are affected by the turbulence and at the same time act back on the flow. The resulting coupling can give rise to rich variability in their dynamics. Here we report experimental results from an investigation of finite-sized buoyant spheres in turbulence. We find that even a marginal reduction in the particle's density from that of the fluid can result in strong modification of its dynamics. In contrast to classical spatial filtering arguments and predictions of particle models, we find that the particle acceleration variance increases with size. We trace this reversed trend back to the growing contribution from wake-induced forces, unaccounted for in current particle models in turbulence. Our findings highlight the need for improved multiphysics based models that account for particle wake effects for a faithful representation of buoyant-sphere dynamics in turbulence.

  20. Leading order finite size effects with spins for inspiralling compact binaries

    Energy Technology Data Exchange (ETDEWEB)

    Levi, Michele [Université Pierre et Marie Curie-Paris VI, CNRS-UMR 7095, Institut d’Astrophysique de Paris, 98 bis Boulevard Arago, 75014 Paris (France); Sorbonne Universités, Institut Lagrange de Paris, 98 bis Boulevard Arago, 75014 Paris (France); Steinhoff, Jan [Max-Planck-Institute for Gravitational Physics - Albert-Einstein-Institute,Am Mühlenberg 1, 14476 Potsdam-Golm (Germany); Centro Multidisciplinar de Astrofisica, Instituto Superior Tecnico, Universidade de Lisboa,Avenida Rovisco Pais 1, 1049-001 Lisboa (Portugal)

    2015-06-10

    The leading order finite size effects due to spin, namely that of the cubic and quartic in spin interactions, are derived for the first time for generic compact binaries via the effective field theory for gravitating spinning objects. These corrections enter at the third and a half and fourth post-Newtonian orders, respectively, for rapidly rotating compact objects. Hence, we complete the leading order finite size effects with spin up to the fourth post-Newtonian accuracy. We arrive at this by augmenting the point particle effective action with new higher dimensional nonminimal coupling worldline operators, involving higher-order derivatives of the gravitational field, and introducing new Wilson coefficients, corresponding to constants, which describe the octupole and hexadecapole deformations of the object due to spin. These Wilson coefficients are fixed to unity in the black hole case. The nonminimal coupling worldline operators enter the action with the electric and magnetic components of the Weyl tensor of even and odd parity, coupled to even and odd worldline spin tensors, respectively. Moreover, the non relativistic gravitational field decomposition, which we employ, demonstrates a coupling hierarchy of the gravito-magnetic vector and the Newtonian scalar, to the odd and even in spin operators, respectively, which extends that of minimal coupling. This observation is useful for the construction of the Feynman diagrams, and provides an instructive analogy between the leading order spin-orbit and cubic in spin interactions, and between the leading order quadratic and quartic in spin interactions.

  1. The square lattice Ising model on the rectangle II: finite-size scaling limit

    Science.gov (United States)

    Hucht, Alfred

    2017-06-01

    Based on the results published recently (Hucht 2017 J. Phys. A: Math. Theor. 50 065201), the universal finite-size contributions to the free energy of the square lattice Ising model on the L× M rectangle, with open boundary conditions in both directions, are calculated exactly in the finite-size scaling limit L, M\\to∞ , T\\to Tc , with fixed temperature scaling variable x\\propto(T/Tc-1)M and fixed aspect ratio ρ\\propto L/M . We derive exponentially fast converging series for the related Casimir potential and Casimir force scaling functions. At the critical point T=Tc we confirm predictions from conformal field theory (Cardy and Peschel 1988 Nucl. Phys. B 300 377, Kleban and Vassileva 1991 J. Phys. A: Math. Gen. 24 3407). The presence of corners and the related corner free energy has dramatic impact on the Casimir scaling functions and leads to a logarithmic divergence of the Casimir potential scaling function at criticality.

  2. Finite size and Coulomb corrections: from nuclei to nuclear liquid vapor phase diagram

    International Nuclear Information System (INIS)

    Moretto, L.G.; Elliott, J.B.; Phair, L.

    2003-01-01

    In this paper we consider the problem of obtaining the infinite symmetric uncharged nuclear matter phase diagram from a thermal nuclear reaction. In the first part we shall consider the Coulomb interaction which, because of its long range makes the definition of phases problematic. This Coulomb effect seems truly devastating since it does not allow one to define nuclear phase transitions much above A ∼ 30. However there may be a solution to this difficulty. If we consider the emission of particles with a sizable charge, we notice that a large Coulomb barrier Bc is present. For T << Bc these channels may be considered effectively closed. Consequently the unbound channels may not play a role on a suitably short time scale. Then a phase transition may still be definable in an approximate way. In the second part of the article we shall deal with the finite size problem by means of a new method, the complement method, which shall permit a straightforward extrapolation to the infinite system. The complement approach consists of evaluating the change in free energy occurring when a particle or cluster is moved from one (finite) phase to another. In the case of a liquid drop in equilibrium with its vapor, this is done by extracting a vapor particle of any given size from the drop and evaluating the energy and entropy changes associated with both the vapor particle and the residual liquid drop (complement)

  3. Surface and finite size effect on fluctuations dynamics in nanoparticles with long-range order

    Science.gov (United States)

    Morozovska, A. N.; Eliseev, E. A.

    2010-02-01

    The influence of surface and finite size on the dynamics of the order parameter fluctuations and critical phenomena in the three-dimensional (3D)-confined systems with long-range order was not considered theoretically. In this paper, we study the influence of surface and finite size on the dynamics of the order parameter fluctuations in the particles of arbitrary shape. We consider concrete examples of the spherical and cylindrical ferroic nanoparticles within Landau-Ginzburg-Devonshire phenomenological approach. Allowing for the strong surface energy contribution in micro and nanoparticles, the analytical expressions derived for the Ornstein-Zernike correlator of the long-range order parameter spatial-temporal fluctuations, dynamic generalized susceptibility, relaxation times, and correlation radii discrete spectra are different from those known for bulk systems. Obtained analytical expressions for the correlation function of the order parameter spatial-temporal fluctuations in micro and nanosized systems can be useful for the quantitative analysis of the dynamical structural factors determined from magnetic resonance diffraction and scattering spectra. Besides the practical importance of the correlation function for the analysis of the experimental data, derived expressions for the fluctuations strength determine the fundamental limits of phenomenological theories applicability for 3D-confined systems.

  4. Charge and finite size corrections for virtual photon spectra in second order Born approximation

    International Nuclear Information System (INIS)

    Durgapal, P.

    1982-01-01

    The purpose of this work is to investigate the effects of finite nuclear size and charge on the spectrum of virtual photons emitted when a relativistic electron is scattered in the field of an atomic nucleus. The method consisted in expanding the scattering cross section in terms of integrals over the nuclear inelastic form factor with a kernel which was evaluated in second order Born approximation and was derived from the elastic-electron scattering form factor. The kernel could be evaluated analytically provided the elastic form factor contained only poles. For this reason the author used a Yukawa form factor. Before calculating the second order term the author studied the first order term containing finite size effects in the inelastic form factor. The author observed that the virtual photon spectrum is insensitive to the details of the inelastic distribution over a large range of energies and depends only on the transition radius. This gave the author the freedom of choosing an inelastic distribution for which the form factor has only poles and the author chose a modified form of the exponential distribution, which enabled the author to evaluate the matrix element analytically. The remaining integral over the physical momentum transfer was performed numerically. The author evaluated the virtual photon spectra for E1 and M1 transitions for a variety of electron energies using several nuclei and compared the results with the distorted wave calculations. Except for low energy and high Z, the second order results compared well with the distorted wave calculations

  5. Finite-size anomalies of the Drude weight: Role of symmetries and ensembles

    Science.gov (United States)

    Sánchez, R. J.; Varma, V. K.

    2017-12-01

    We revisit the numerical problem of computing the high temperature spin stiffness, or Drude weight, D of the spin-1 /2 X X Z chain using exact diagonalization to systematically analyze its dependence on system symmetries and ensemble. Within the canonical ensemble and for states with zero total magnetization, we find D vanishes exactly due to spin-inversion symmetry for all but the anisotropies Δ˜M N=cos(π M /N ) with N ,M ∈Z+ coprimes and N >M , provided system sizes L ≥2 N , for which states with different spin-inversion signature become degenerate due to the underlying s l2 loop algebra symmetry. All these loop-algebra degenerate states carry finite currents which we conjecture [based on data from the system sizes and anisotropies Δ˜M N (with N magnetic flux not only breaks spin-inversion in the zero magnetization sector but also lifts the loop-algebra degeneracies in all symmetry sectors—this effect is more pertinent at smaller Δ due to the larger contributions to D coming from the low-magnetization sectors which are more sensitive to the system's symmetries. Thus we generically find a finite D for fluxed rings and arbitrary 0 lifted.

  6. Effects of the finite particle size in turbulent wall-bounded flows of dense suspensions

    Science.gov (United States)

    Costa, Pedro; Picano, Francesco; Brandt, Luca; Breugem, Wim-Paul

    2018-05-01

    We use interface-resolved simulations to study finite-size effects in turbulent channel flow of neutrally-buoyant spheres. Two cases with particle sizes differing by a factor of 2, at the same solid volume fraction of 20% and bulk Reynolds number are considered. These are complemented with two reference single-phase flows: the unladen case, and the flow of a Newtonian fluid with the effective suspension viscosity of the same mixture in the laminar regime. As recently highlighted in Costa et al. (PRL 117, 134501), a particle-wall layer is responsible for deviations of the statistics from what is observed in the continuum limit where the suspension is modeled as a Newtonian fluid with an effective viscosity. Here we investigate the fluid and particle dynamics in this layer and in the bulk. In the particle-wall layer, the near wall inhomogeneity has an influence on the suspension micro-structure over a distance proportional to the particle size. In this layer, particles have a significant (apparent) slip velocity that is reflected in the distribution of wall shear stresses. This is characterized by extreme events (both much higher and much lower than the mean). Based on these observations we provide a scaling for the particle-to-fluid apparent slip velocity as a function of the flow parameters. We also extend the flow scaling laws in to second-order Eulerian statistics in the homogeneous suspension region away from the wall. Finite-size effects in the bulk of the channel become important for larger particles, while negligible for lower-order statistics and smaller particles. Finally, we study the particle dynamics along the wall-normal direction. Our results suggest that 1-point dispersion is dominated by particle-turbulence (and not particle-particle) interactions, while differences in 2-point dispersion and collisional dynamics are consistent with a picture of shear-driven interactions.

  7. Finite

    Directory of Open Access Journals (Sweden)

    W.R. Azzam

    2015-08-01

    Full Text Available This paper reports the application of using a skirted foundation system to study the behavior of foundations with structural skirts adjacent to a sand slope and subjected to earthquake loading. The effect of the adopted skirts to safeguard foundation and slope from collapse is studied. The skirts effect on controlling horizontal soil movement and decreasing pore water pressure beneath foundations and beside the slopes during earthquake is investigated. This technique is investigated numerically using finite element analysis. A four story reinforced concrete building that rests on a raft foundation is idealized as a two-dimensional model with and without skirts. A two dimensional plain strain program PLAXIS, (dynamic version is adopted. A series of models for the problem under investigation were run under different skirt depths and lactation from the slope crest. The effect of subgrade relative density and skirts thickness is also discussed. Nodal displacement and element strains were analyzed for the foundation with and without skirts and at different studied parameters. The research results showed a great effectiveness in increasing the overall stability of the slope and foundation. The confined soil footing system by such skirts reduced the foundation acceleration therefore it can be tended to damping element and relieved the transmitted disturbance to the adjacent slope. This technique can be considered as a good method to control the slope deformation and decrease the slope acceleration during earthquakes.

  8. A Markov model for the temporal dynamics of balanced random networks of finite size

    Science.gov (United States)

    Lagzi, Fereshteh; Rotter, Stefan

    2014-01-01

    The balanced state of recurrent networks of excitatory and inhibitory spiking neurons is characterized by fluctuations of population activity about an attractive fixed point. Numerical simulations show that these dynamics are essentially nonlinear, and the intrinsic noise (self-generated fluctuations) in networks of finite size is state-dependent. Therefore, stochastic differential equations with additive noise of fixed amplitude cannot provide an adequate description of the stochastic dynamics. The noise model should, rather, result from a self-consistent description of the network dynamics. Here, we consider a two-state Markovian neuron model, where spikes correspond to transitions from the active state to the refractory state. Excitatory and inhibitory input to this neuron affects the transition rates between the two states. The corresponding nonlinear dependencies can be identified directly from numerical simulations of networks of leaky integrate-and-fire neurons, discretized at a time resolution in the sub-millisecond range. Deterministic mean-field equations, and a noise component that depends on the dynamic state of the network, are obtained from this model. The resulting stochastic model reflects the behavior observed in numerical simulations quite well, irrespective of the size of the network. In particular, a strong temporal correlation between the two populations, a hallmark of the balanced state in random recurrent networks, are well represented by our model. Numerical simulations of such networks show that a log-normal distribution of short-term spike counts is a property of balanced random networks with fixed in-degree that has not been considered before, and our model shares this statistical property. Furthermore, the reconstruction of the flow from simulated time series suggests that the mean-field dynamics of finite-size networks are essentially of Wilson-Cowan type. We expect that this novel nonlinear stochastic model of the interaction between

  9. Mechanisms of self-organization and finite size effects in a minimal agent based model

    International Nuclear Information System (INIS)

    Alfi, V; Cristelli, M; Pietronero, L; Zaccaria, A

    2009-01-01

    We present a detailed analysis of the self-organization phenomenon in which the stylized facts originate from finite size effects with respect to the number of agents considered and disappear in the limit of an infinite population. By introducing the possibility that agents can enter or leave the market depending on the behavior of the price, it is possible to show that the system self-organizes in a regime with a finite number of agents which corresponds to the stylized facts. The mechanism for entering or leaving the market is based on the idea that a too stable market is unappealing for traders, while the presence of price movements attracts agents to enter and speculate on the market. We show that this mechanism is also compatible with the idea that agents are scared by a noisy and risky market at shorter timescales. We also show that the mechanism for self-organization is robust with respect to variations of the exit/entry rules and that the attempt to trigger the system to self-organize in a region without stylized facts leads to an unrealistic dynamics. We study the self-organization in a specific agent based model but we believe that the basic ideas should be of general validity

  10. Neutron density decay constant in a non-multiplying lattice of finite size

    International Nuclear Information System (INIS)

    Deniz, V.C.

    1965-01-01

    This report presents a general theory, using the integral transport method, for obtaining the neutron density decay constant in a finite non-multiplying lattice. The theory is applied to obtain the expression for the diffusion coefficient. The case of a homogeneous medium with 1/v absorption and of finite size in all directions is treated in detail, assuming an isotropic scattering law. The decay constant is obtained up to the B 6 term. The expressions for the diffusion coefficient and for the diffusion cooling coefficient are the same as those obtained for a slab geometry by Nelkin, using the expansion in spherical harmonics of the Fourier transform in the spatial variable. Furthermore, explicit forms are obtained for the flux and the current. It is shown that the deviation of the actual flux from a Maxwellian is the flux generated in the medium, extended to infinity and deprived of its absorbing power, by various sources, each of which has a zero integral over all velocities. The study of the current permits the generalization of Fick's law. An independent integral method, valid for homogeneous media, is also presented. (author) [fr

  11. Synchronization of finite-size particles by a traveling wave in a cylindrical flow

    Science.gov (United States)

    Melnikov, D. E.; Pushkin, D. O.; Shevtsova, V. M.

    2013-09-01

    Motion of small finite-size particles suspended in a cylindrical thermocapillary flow with an azimuthally traveling wave is studied experimentally and numerically. At certain flow regimes the particles spontaneously align in dynamic accumulation structures (PAS) of spiral shape. We find that long-time trajectories of individual particles in this flow fall into three basic categories that can be described, borrowing the dynamical systems terminology, as the stable periodic, the quasiperiodic, and the quasistable periodic orbits. Besides these basic types of orbits, we observe the "doubled" periodic orbits and shuttle-like particle trajectories. We find that ensembles of particles having periodic orbits give rise to one-dimensional spiral PAS, while ensembles of particles having quasiperiodic orbits form two-dimensional PAS of toroidal shape. We expound the reasons why these types of orbits and the emergence of the corresponding accumulation structures should naturally be anticipated based on the phase locking theory of PAS formation. We give a further discussion of PAS features, such as the finite thickness of PAS spirals and the probable scenarios of the spiral PAS destruction. Finally, in numerical simulations of inertial particles we observe formation of the spiral structures corresponding to the 3:1 "resonance" between the particle turnover frequency and the wave oscillations frequency, thus confirming another prediction of the phase locking theory. In view of the generality of the arguments involved, we expect the importance of this structure-forming mechanism to go far beyond the realm of the laboratory-friendly thermocapillary flows.

  12. Dependence of exponents on text length versus finite-size scaling for word-frequency distributions

    Science.gov (United States)

    Corral, Álvaro; Font-Clos, Francesc

    2017-08-01

    Some authors have recently argued that a finite-size scaling law for the text-length dependence of word-frequency distributions cannot be conceptually valid. Here we give solid quantitative evidence for the validity of this scaling law, using both careful statistical tests and analytical arguments based on the generalized central-limit theorem applied to the moments of the distribution (and obtaining a novel derivation of Heaps' law as a by-product). We also find that the picture of word-frequency distributions with power-law exponents that decrease with text length [X. Yan and P. Minnhagen, Physica A 444, 828 (2016), 10.1016/j.physa.2015.10.082] does not stand with rigorous statistical analysis. Instead, we show that the distributions are perfectly described by power-law tails with stable exponents, whose values are close to 2, in agreement with the classical Zipf's law. Some misconceptions about scaling are also clarified.

  13. Finite-size effects in the spectrum of the OSp (3 | 2) superspin chain

    Science.gov (United States)

    Frahm, Holger; Martins, Márcio J.

    2015-05-01

    The low energy spectrum of a spin chain with OSp (3 | 2) supergroup symmetry is studied based on the Bethe ansatz solution of the related vertex model. This model is a lattice realization of intersecting loops in two dimensions with loop fugacity z = 1 which provides a framework to study the critical properties of the unusual low temperature Goldstone phase of the O (N) sigma model for N = 1 in the context of an integrable model. Our finite-size analysis provides strong evidence for the existence of continua of scaling dimensions, the lowest of them starting at the ground state. Based on our data we conjecture that the so-called watermelon correlation functions decay logarithmically with exponents related to the quadratic Casimir operator of OSp (3 | 2). The presence of a continuous spectrum is not affected by a change to the boundary conditions although the density of states in the continua appears to be modified.

  14. Finite-size effects in the spectrum of the OSp(3|2 superspin chain

    Directory of Open Access Journals (Sweden)

    Holger Frahm

    2015-05-01

    Full Text Available The low energy spectrum of a spin chain with OSp(3|2 supergroup symmetry is studied based on the Bethe ansatz solution of the related vertex model. This model is a lattice realization of intersecting loops in two dimensions with loop fugacity z=1 which provides a framework to study the critical properties of the unusual low temperature Goldstone phase of the O(N sigma model for N=1 in the context of an integrable model. Our finite-size analysis provides strong evidence for the existence of continua of scaling dimensions, the lowest of them starting at the ground state. Based on our data we conjecture that the so-called watermelon correlation functions decay logarithmically with exponents related to the quadratic Casimir operator of OSp(3|2. The presence of a continuous spectrum is not affected by a change to the boundary conditions although the density of states in the continua appears to be modified.

  15. Generic finite size scaling for discontinuous nonequilibrium phase transitions into absorbing states

    Science.gov (United States)

    de Oliveira, M. M.; da Luz, M. G. E.; Fiore, C. E.

    2015-12-01

    Based on quasistationary distribution ideas, a general finite size scaling theory is proposed for discontinuous nonequilibrium phase transitions into absorbing states. Analogously to the equilibrium case, we show that quantities such as response functions, cumulants, and equal area probability distributions all scale with the volume, thus allowing proper estimates for the thermodynamic limit. To illustrate these results, five very distinct lattice models displaying nonequilibrium transitions—to single and infinitely many absorbing states—are investigated. The innate difficulties in analyzing absorbing phase transitions are circumvented through quasistationary simulation methods. Our findings (allied to numerical studies in the literature) strongly point to a unifying discontinuous phase transition scaling behavior for equilibrium and this important class of nonequilibrium systems.

  16. Finite size scaling of the Higgs-Yukawa model near the Gaussian fixed point

    Energy Technology Data Exchange (ETDEWEB)

    Chu, David Y.J.; Lin, C.J. David [National Chiao-Tung Univ., Hsinchu, Taiwan (China); Jansen, Karl [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Knippschild, Bastian [HISKP, Bonn (Germany); Nagy, Attila [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Humboldt-Univ. Berlin (Germany)

    2016-12-15

    We study the scaling properties of Higgs-Yukawa models. Using the technique of Finite-Size Scaling, we are able to derive scaling functions that describe the observables of the model in the vicinity of a Gaussian fixed point. A feasibility study of our strategy is performed for the pure scalar theory in the weak-coupling regime. Choosing the on-shell renormalisation scheme gives us an advantage to fit the scaling functions against lattice data with only a small number of fit parameters. These formulae can be used to determine the universality of the observed phase transitions, and thus play an essential role in future investigations of Higgs-Yukawa models, in particular in the strong Yukawa coupling region.

  17. Finite size scaling analysis on Nagel-Schreckenberg model for traffic flow

    Science.gov (United States)

    Balouchi, Ashkan; Browne, Dana

    2015-03-01

    The traffic flow problem as a many-particle non-equilibrium system has caught the interest of physicists for decades. Understanding the traffic flow properties and though obtaining the ability to control the transition from the free-flow phase to the jammed phase plays a critical role in the future world of urging self-driven cars technology. We have studied phase transitions in one-lane traffic flow through the mean velocity, distributions of car spacing, dynamic susceptibility and jam persistence -as candidates for an order parameter- using the Nagel-Schreckenberg model to simulate traffic flow. The length dependent transition has been observed for a range of maximum velocities greater than a certain value. Finite size scaling analysis indicates power-law scaling of these quantities at the onset of the jammed phase.

  18. 1/ f noise from the laws of thermodynamics for finite-size fluctuations.

    Science.gov (United States)

    Chamberlin, Ralph V; Nasir, Derek M

    2014-07-01

    Computer simulations of the Ising model exhibit white noise if thermal fluctuations are governed by Boltzmann's factor alone; whereas we find that the same model exhibits 1/f noise if Boltzmann's factor is extended to include local alignment entropy to all orders. We show that this nonlinear correction maintains maximum entropy during equilibrium fluctuations. Indeed, as with the usual way to resolve Gibbs' paradox that avoids entropy reduction during reversible processes, the correction yields the statistics of indistinguishable particles. The correction also ensures conservation of energy if an instantaneous contribution from local entropy is included. Thus, a common mechanism for 1/f noise comes from assuming that finite-size fluctuations strictly obey the laws of thermodynamics, even in small parts of a large system. Empirical evidence for the model comes from its ability to match the measured temperature dependence of the spectral-density exponents in several metals and to show non-Gaussian fluctuations characteristic of nanoscale systems.

  19. Modeling of finite-size droplets and particles in multiphase flows

    Directory of Open Access Journals (Sweden)

    Prashant Khare

    2015-08-01

    Full Text Available The conventional point-particle approach for treating the dispersed phase in a continuous flowfield is extended by taking into account the effect of finite particle size, using a Gaussian interpolation from Lagrangian points to the Eulerian field. The inter-phase exchange terms in the conservation equations are distributed over the volume encompassing the particle size, as opposed to the Dirac delta function generally used in the point-particle approach. The proposed approach is benchmarked against three different flow configurations in a numerical framework based on large eddy simulation (LES turbulence closure. First, the flow over a circular cylinder is simulated for a Reynolds number of 3900 at 1 atm pressure. Results show good agreement with experimental data for the mean streamwise velocity and the vortex shedding frequency in the wake region. The calculated flowfield exhibits correct physics, which the conventional point-particle approach fails to capture. The second case deals with diesel jet injection in quiescent environment over a pressure range of 1.1–5.0 MPa. The calculated jet penetration depth closely matches measurements. It decreases with increasing chamber pressure, due to enhanced drag force in a denser fluid environment. Finally, water and acetone jet injection normal to air crossflow is studied at 1 atm. The calculated jet penetration and Sauter mean diameter of liquid droplets compare very well with measurements.

  20. Finite-size giant magnons on η-deformed AdS{sub 5}×S{sup 5}

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Changrim, E-mail: ahn@ewha.ac.kr; Bozhilov, Plamen, E-mail: bozhilov@inrne.bas.bg

    2014-10-07

    We consider strings moving in the R{sub t}×S{sub η}{sup 3} subspace of the η-deformed AdS{sub 5}×S{sup 5} and obtain a class of solutions depending on several parameters. They are characterized by the string energy and two angular momenta. Finite-size dyonic giant magnon belongs to this class of solutions. Further on, we restrict ourselves to the case of giant magnon with one nonzero angular momentum, and obtain the leading finite-size correction to the dispersion relation.

  1. Finite-size giant magnons on η-deformed AdS5×S5

    Directory of Open Access Journals (Sweden)

    Changrim Ahn

    2014-10-01

    Full Text Available We consider strings moving in the Rt×Sη3 subspace of the η-deformed AdS5×S5 and obtain a class of solutions depending on several parameters. They are characterized by the string energy and two angular momenta. Finite-size dyonic giant magnon belongs to this class of solutions. Further on, we restrict ourselves to the case of giant magnon with one nonzero angular momentum, and obtain the leading finite-size correction to the dispersion relation.

  2. Finite-size scaling method for the Berezinskii–Kosterlitz–Thouless transition

    International Nuclear Information System (INIS)

    Hsieh, Yun-Da; Kao, Ying-Jer; Sandvik, Anders W

    2013-01-01

    We test an improved finite-size scaling method for reliably extracting the critical temperature T BKT of a Berezinskii–Kosterlitz–Thouless (BKT) transition. Using known single-parameter logarithmic corrections to the spin stiffness ρ s at T BKT in combination with the Kosterlitz–Nelson relation between the transition temperature and the stiffness, ρ s (T BKT ) = 2T BKT /π, we define a size-dependent transition temperature T BKT (L 1 ,L 2 ) based on a pair of system sizes L 1 ,L 2 , e.g., L 2 = 2L 1 . We use Monte Carlo data for the standard two-dimensional classical XY model to demonstrate that this quantity is well behaved and can be reliably extrapolated to the thermodynamic limit using the next expected logarithmic correction beyond the ones included in defining T BKT (L 1 ,L 2 ). For the Monte Carlo calculations we use GPU (graphical processing unit) computing to obtain high-precision data for L up to 512. We find that the sub-leading logarithmic corrections have significant effects on the extrapolation. Our result T BKT = 0.8935(1) is several error bars above the previously best estimates of the transition temperature, T BKT ≈ 0.8929. If only the leading log-correction is used, the result is, however, consistent with the lower value, suggesting that previous works have underestimated T BKT because of the neglect of sub-leading logarithms. Our method is easy to implement in practice and should be applicable to generic BKT transitions. (paper)

  3. Finite-size scaling of the entanglement entropy of the quantum Ising chain with homogeneous, periodically modulated and random couplings

    International Nuclear Information System (INIS)

    Iglói, Ferenc; Lin, Yu-Cheng

    2008-01-01

    Using free-fermionic techniques we study the entanglement entropy of a block of contiguous spins in a large finite quantum Ising chain in a transverse field, with couplings of different types: homogeneous, periodically modulated and random. We carry out a systematic study of finite-size effects at the quantum critical point, and evaluate subleading corrections both for open and for periodic boundary conditions. For a block corresponding to a half of a finite chain, the position of the maximum of the entropy as a function of the control parameter (e.g. the transverse field) can define the effective critical point in the finite sample. On the basis of homogeneous chains, we demonstrate that the scaling behavior of the entropy near the quantum phase transition is in agreement with the universality hypothesis, and calculate the shift of the effective critical point, which has different scaling behaviors for open and for periodic boundary conditions

  4. Extreme value statistics and finite-size scaling at the ecological extinction/laminar-turbulence transition

    Science.gov (United States)

    Shih, Hong-Yan; Goldenfeld, Nigel

    Experiments on transitional turbulence in pipe flow seem to show that turbulence is a transient metastable state since the measured mean lifetime of turbulence puffs does not diverge asymptotically at a critical Reynolds number. Yet measurements reveal that the lifetime scales with Reynolds number in a super-exponential way reminiscent of extreme value statistics, and simulations and experiments in Couette and channel flow exhibit directed percolation type scaling phenomena near a well-defined transition. This universality class arises from the interplay between small-scale turbulence and a large-scale collective zonal flow, which exhibit predator-prey behavior. Why is asymptotically divergent behavior not observed? Using directed percolation and a stochastic individual level model of predator-prey dynamics related to transitional turbulence, we investigate the relation between extreme value statistics and power law critical behavior, and show that the paradox is resolved by carefully defining what is measured in the experiments. We theoretically derive the super-exponential scaling law, and using finite-size scaling, show how the same data can give both super-exponential behavior and power-law critical scaling.

  5. Finite nuclear size and Lamb shift of p-wave atomic states

    International Nuclear Information System (INIS)

    Milstein, A.I.; Sushkov, O.P.; Terekhov, I.S.

    2003-01-01

    We consider corrections to the Lamb shift of the p-wave atomic states due to the finite nuclear size (FNS). In other words, these are radiative corrections to the atomic isotope shift related to the FNS. It is shown that the structure of the corrections is qualitatively different to that for the s-wave states. The perturbation theory expansion for the relative correction for a p 1/2 state starts with a α ln(1/Zα) term, while for the s 1/2 states it starts with a Zα 2 term. Here, α is the fine-structure constant and Z is the nuclear charge. In the present work, we calculate the α terms for that 2p states, the result for the 2p 1/2 state reads (8α/9π){ln[1/(Zα) 2 ]+0.710}. Even more interesting are the p 3/2 states. In this case the 'correction' is several orders of magnitude larger than the 'leading' FNS shift. However, absolute values of energy shifts related to these corrections are very small

  6. Length and temperature dependence of the mechanical properties of finite-size carbyne

    Science.gov (United States)

    Yang, Xueming; Huang, Yanhui; Cao, Bingyang; To, Albert C.

    2017-09-01

    Carbyne is an ideal one-dimensional conductor and the thinnest interconnection in an ultimate nano-device and it requires an understanding of the mechanical properties that affect device performance and reliability. Here, we report the mechanical properties of finite-size carbyne, obtained by a molecular dynamics simulation study based on the adaptive intermolecular reactive empirical bond order potential. To avoid confusion in assigning the effective cross-sectional area of carbyne, the value of the effective cross-sectional area of carbyne (4.148 Å2) was deduced via experiment and adopted in our study. Ends-constraints effects on the ultimate stress (maximum force) of the carbyne chains are investigated, revealing that the molecular dynamics simulation results agree very well with the experimental results. The ultimate strength, Young's Modulus and maximum strain of carbyne are rather sensitive to the temperature and all decrease with the temperature. Opposite tendencies of the length dependence of the overall ultimate strength and maximum strain of carbyne at room temperature and very low temperature have been found, and analyses show that this originates in the ends effect of carbyne.

  7. Evaluation of cavity size, kind, and filling technique of composite shrinkage by finite element.

    Science.gov (United States)

    Jafari, Toloo; Alaghehmad, Homayoon; Moodi, Ehsan

    2018-01-01

    Cavity preparation reduces the rigidity of tooth and its resistance to deformation. The purpose of this study was to evaluate the dimensional changes of the repaired teeth using two types of light cure composite and two methods of incremental and bulk filling by the use of finite element method. In this computerized in vitro experimental study, an intact maxillary premolar was scanned using cone beam computed tomography instrument (SCANORA, Switzerland), then each section of tooth image was transmitted to Ansys software using AUTOCAD. Then, eight sizes of cavity preparations and two methods of restoration (bulk and incremental) using two different types of composite resin materials (Heliomolar, Brilliant) were proposed on software and analysis was completed with Ansys software. Dimensional change increased by widening and deepening of the cavities. It was also increased using Brilliant composite resin and incremental filling technique. Increase in depth and type of filling technique has the greatest role of dimensional change after curing, but the type of composite resin does not have a significant role.

  8. An exact solution to the extended Hubbard model in 2D for finite size system

    Science.gov (United States)

    Harir, S.; Bennai, M.; Boughaleb, Y.

    2008-08-01

    An exact analytical diagonalization is used to solve the two-dimensional extended Hubbard model (EHM) for a system with finite size. We have considered an EHM including on-site and off-site interactions with interaction energies U and V, respectively, for a square lattice containing 4×4 sites at one-eighth filling with periodic boundary conditions, recently treated by Kovacs and Gulacsi (2006 Phil. Mag. 86 2073). Taking into account the symmetric properties of this square lattice and using a translation linear operator, we have constructed a r-space basis only with 85 state-vectors which describe all possible distributions for four electrons in the 4×4 square lattice. The diagonalization of the 85×85 matrix energy allows us to study the local properties of the above system as a function of the on-site and off-site interactions energies, where we have shown that the off-site interaction encourages the existence of the double occupancies at the first excited state and induces a supplementary conductivity of the system.

  9. Finite-size behaviour of generalized susceptibilities in the whole phase plane of the Potts model

    Science.gov (United States)

    Pan, Xue; Zhang, Yanhua; Chen, Lizhu; Xu, Mingmei; Wu, Yuanfang

    2018-01-01

    We study the sign distribution of generalized magnetic susceptibilities in the temperature-external magnetic field plane using the three-dimensional three-state Potts model. We find that the sign of odd-order susceptibility is opposite in the symmetric (disorder) and broken (order) phases, but that of the even-order one remains positive when it is far away from the phase boundary. When the critical point is approached from the crossover side, negative fourth-order magnetic susceptibility is observable. It is also demonstrated that non-monotonic behavior occurs in the temperature dependence of the generalized susceptibilities of the energy. The finite-size scaling behavior of the specific heat in this model is mainly controlled by the critical exponent of the magnetic susceptibility in the three-dimensional Ising universality class. Supported by Fund Project of National Natural Science Foundation of China (11647093, 11405088, 11521064), Fund Project of Sichuan Provincial Department of Education (16ZB0339), Fund Project of Chengdu Technological University (2016RC004) and the Major State Basic Research Development Program of China (2014CB845402)

  10. Avalanching Systems with Longer Range Connectivity: Occurrence of a Crossover Phenomenon and Multifractal Finite Size Scaling

    Directory of Open Access Journals (Sweden)

    Simone Benella

    2017-07-01

    Full Text Available Many out-of-equilibrium systems respond to external driving with nonlinear and self-similar dynamics. This near scale-invariant behavior of relaxation events has been modeled through sand pile cellular automata. However, a common feature of these models is the assumption of a local connectivity, while in many real systems, we have evidence for longer range connectivity and a complex topology of the interacting structures. Here, we investigate the role that longer range connectivity might play in near scale-invariant systems, by analyzing the results of a sand pile cellular automaton model on a Newman–Watts network. The analysis clearly indicates the occurrence of a crossover phenomenon in the statistics of the relaxation events as a function of the percentage of longer range links and the breaking of the simple Finite Size Scaling (FSS. The more complex nature of the dynamics in the presence of long-range connectivity is investigated in terms of multi-scaling features and analyzed by the Rank-Ordered Multifractal Analysis (ROMA.

  11. Importance of elastic finite-size effects: Neutral defects in ionic compounds

    Science.gov (United States)

    Burr, P. A.; Cooper, M. W. D.

    2017-09-01

    Small system sizes are a well-known source of error in density functional theory (DFT) calculations, yet computational constraints frequently dictate the use of small supercells, often as small as 96 atoms in oxides and compound semiconductors. In ionic compounds, electrostatic finite-size effects have been well characterized, but self-interaction of charge-neutral defects is often discounted or assumed to follow an asymptotic behavior and thus easily corrected with linear elastic theory. Here we show that elastic effects are also important in the description of defects in ionic compounds and can lead to qualitatively incorrect conclusions if inadequately small supercells are used; moreover, the spurious self-interaction does not follow the behavior predicted by linear elastic theory. Considering the exemplar cases of metal oxides with fluorite structure, we show that numerous previous studies, employing 96-atom supercells, misidentify the ground-state structure of (charge-neutral) Schottky defects. We show that the error is eliminated by employing larger cells (324, 768, and 1500 atoms), and careful analysis determines that elastic, not electrostatic, effects are responsible. The spurious self-interaction was also observed in nonoxide ionic compounds irrespective of the computational method used, thereby resolving long-standing discrepancies between DFT and force-field methods, previously attributed to the level of theory. The surprising magnitude of the elastic effects is a cautionary tale for defect calculations in ionic materials, particularly when employing computationally expensive methods (e.g., hybrid functionals) or when modeling large defect clusters. We propose two computationally practicable methods to test the magnitude of the elastic self-interaction in any ionic system. In commonly studied oxides, where electrostatic effects would be expected to be dominant, it is the elastic effects that dictate the need for larger supercells: greater than 96 atoms.

  12. Non-conventional screening of the Coulomb interaction in low-dimensional and finite-size systems

    NARCIS (Netherlands)

    van den Brink, J.; Sawatzky, G.A.

    2000-01-01

    We study the screening of the Coulomb interaction in non-polar systems by polarizable atoms. We show that in low dimensions and small finite-size systems this screening deviates strongly from that conventionally assumed. In fact in one dimension the short-range interaction is strongly screened and

  13. Ruin probabilities with compounding assets for discrete time finite horizon problem, independent period claim sizes and general premium structure

    NARCIS (Netherlands)

    Kok, de A.G.

    2003-01-01

    In this paper, we present fast and accurate approximations for the probability of ruin over a finite number of periods, assuming inhomogeneous independent claim size distributions and arbitrary premium income in subsequent periods. We develop exact recursive expressions for the non-ruin

  14. Ruin probabilities with compounding assets for discrete time finite horizon problems, independent period claim sizes and general premium structure

    NARCIS (Netherlands)

    Kok, de A.G.

    2003-01-01

    In this paper we present fast and accurate approximations for the probability of ruin over a finite number of periods, assuming inhomogeneous independent claim size distributions and arbitrary premium income in subsequent periods. We develop exact recursive expressions for the non-ruin probabilities

  15. Fluctuations, Finite-Size Effects and the Thermodynamic Limit in Computer Simulations: Revisiting the Spatial Block Analysis Method

    Directory of Open Access Journals (Sweden)

    Maziar Heidari

    2018-03-01

    Full Text Available The spatial block analysis (SBA method has been introduced to efficiently extrapolate thermodynamic quantities from finite-size computer simulations of a large variety of physical systems. In the particular case of simple liquids and liquid mixtures, by subdividing the simulation box into blocks of increasing size and calculating volume-dependent fluctuations of the number of particles, it is possible to extrapolate the bulk isothermal compressibility and Kirkwood–Buff integrals in the thermodynamic limit. Only by explicitly including finite-size effects, ubiquitous in computer simulations, into the SBA method, the extrapolation to the thermodynamic limit can be achieved. In this review, we discuss two of these finite-size effects in the context of the SBA method due to (i the statistical ensemble and (ii the finite integration domains used in computer simulations. To illustrate the method, we consider prototypical liquids and liquid mixtures described by truncated and shifted Lennard–Jones (TSLJ potentials. Furthermore, we show some of the most recent developments of the SBA method, in particular its use to calculate chemical potentials of liquids in a wide range of density/concentration conditions.

  16. Proposal for element size and time increment selection guideline by 3-D finite element method for elastic waves propagation analysis

    International Nuclear Information System (INIS)

    Ishida, Hitoshi; Meshii, Toshiyuki

    2008-01-01

    This paper proposes a guideline for selection of element size and time increment by 3-D finite element method, which is applied to elastic wave propagation analysis for a long distance of a large structure. An element size and a time increment are determined by quantitative evaluation of strain, which must be 0 on the analysis model with a uniform motion, caused by spatial and time discretization. (author)

  17. The logic of strategic ignorance.

    Science.gov (United States)

    McGoey, Linsey

    2012-09-01

    Ignorance and knowledge are often thought of as opposite phenomena. Knowledge is seen as a source of power, and ignorance as a barrier to consolidating authority in political and corporate arenas. This article disputes this, exploring the ways that ignorance serves as a productive asset, helping individuals and institutions to command resources, deny liability in the aftermath of crises, and to assert expertise in the face of unpredictable outcomes. Through a focus on the Food and Drug Administration's licensing of Ketek, an antibiotic drug manufactured by Sanofi-Aventis and linked to liver failure, I suggest that in drug regulation, different actors, from physicians to regulators to manufacturers, often battle over who can attest to the least knowledge of the efficacy and safety of different drugs - a finding that raises new insights about the value of ignorance as an organizational resource. © London School of Economics and Political Science 2012.

  18. Ignoring Ignorance: Notes on Pedagogical Relationships in Citizen Science

    Directory of Open Access Journals (Sweden)

    Michael Scroggins

    2017-04-01

    Full Text Available Theoretically, this article seeks to broaden the conceptualization of ignorance within STS by drawing on a line of theory developed in the philosophy and anthropology of education to argue that ignorance can be productively conceptualized as a state of possibility and that doing so can enable more democratic forms of citizen science. In contrast to conceptualizations of ignorance as a lack, lag, or manufactured product, ignorance is developed here as both the opening move in scientific inquiry and the common ground over which that inquiry proceeds. Empirically, the argument is developed through an ethnographic description of Scroggins' participation in a failed citizen science project at a DIYbio laboratory. Supporting the empirical case are a review of the STS literature on expertise and a critical examination of the structures of participation within two canonical citizen science projects. Though onerous, through close attention to how people transform one another during inquiry, increasingly democratic forms of citizen science, grounded in the commonness of ignorance, can be put into practice.

  19. Finite-size, chemical-potential and magnetic effects on the phase transition in a four-fermion interacting model

    Energy Technology Data Exchange (ETDEWEB)

    Correa, E.B.S. [Universidade Federal do Sul e Sudeste do Para, Instituto de Ciencias Exatas, Maraba (Brazil); Centro Brasileiro de Pesquisas Fisicas-CBPF/MCTI, Rio de Janeiro (Brazil); Linhares, C.A. [Universidade do Estado do Rio de Janeiro, Instituto de Fisica, Rio de Janeiro (Brazil); Malbouisson, A.P.C. [Centro Brasileiro de Pesquisas Fisicas-CBPF/MCTI, Rio de Janeiro (Brazil); Malbouisson, J.M.C. [Universidade Federal da Bahia, Instituto de Fisica, Salvador (Brazil); Santana, A.E. [Universidade de Brasilia, Instituto de Fisica, Brasilia, DF (Brazil)

    2017-04-15

    We study effects coming from finite size, chemical potential and from a magnetic background on a massive version of a four-fermion interacting model. This is performed in four dimensions as an application of recent developments for dealing with field theories defined on toroidal spaces. We study effects of the magnetic field and chemical potential on the size-dependent phase structure of the model, in particular, how the applied magnetic field affects the size-dependent critical temperature. A connection with some aspects of the hadronic phase transition is established. (orig.)

  20. Finite size effects in liquid-gas phase transition of asymmetric nuclear matter

    International Nuclear Information System (INIS)

    Pawlowski, P.

    2001-01-01

    Full text: Since the nuclear equation of state has been studied in astrophysical context as an element of neutron star or super-nova theories - a call for an evidence was produced in experimental nuclear physics. Heavy-ion collisions became a tool of study on thermodynamic properties of nuclear matter. A particular interest has been inspired here by critical behavior of nuclear systems, as a phase transition of liquid-gas type. A lot of efforts was put to obtain an experimental evidence of such a phenomenon in heavy-ion collisions. With the use of radioactive beams and high performance identification systems in a near future it will be possible to extend experimental investigation to asymmetric nuclear systems, where neutron-to-proton ratio is far from the stability line. This experimental development needs a corresponding extension of theoretical studies. To obtain a complete theory of the liquid-gas phase transition in small nuclear systems, produced in violent heavy-ion collisions, one should take into account two facts. First, that the nuclear matter forming nuclei is composed of protons and neutrons; this complicates the formalism of phase transitions because one has to deal with two separate, proton and neutron, densities and chemical potentials. The second and more important is that the surface effects are very strong in a system composed of a few hundreds of nucleons. This point is especially difficult to hold, because surface becomes an additional, independent state parameter, depending strongly on the geometrical configuration of the system, and introducing a non-local term in the equation of state. In this presentation we follow the recent calculation by Lee and Mekjian on the finite-size effects in small (A = 10 2 -10 3 ) asymmetric nuclear systems. A zero-range isospin-dependent Skyrme force is used to obtain a density and isospin dependent potential. The potential is then completed by additional terms giving contributions from surface and Coulomb

  1. Theoretical studies of finite size effects and screening effects caused by a STM tip in Luettinger liquids

    International Nuclear Information System (INIS)

    Guigou, Marine

    2009-01-01

    This thesis takes place in the field of condensed matter. More precisely, we focus on the finite size effects and the screening effects caused by a STM tip in a quantum wire. For that, we use, first, the Luettinger liquid theory, which allows to describe strongly correlated systems and secondly, the Keldysh formalism, which is necessary to treat the out-of-equilibrium systems. For these studies, we consider, the currant, the noise and the conductance. The noise presents a non-Poissonian behaviour, when finite size effects appear. Through the photo-assisted transport, it is shown that those effects hide the effects of the Coulomb interactions. Considering the proximity between the STM tip, used as a probe or as an injector, and a quantum wire, screening effects appear. We can conclude that they play a similar role to those of Coulomb interactions. (author) [fr

  2. Exact solution for the inhomogeneous Dicke model in the canonical ensemble: Thermodynamical limit and finite-size corrections

    Energy Technology Data Exchange (ETDEWEB)

    Pogosov, W.V., E-mail: walter.pogosov@gmail.com [N.L. Dukhov All-Russia Research Institute of Automatics, Moscow (Russian Federation); Institute for Theoretical and Applied Electrodynamics, Russian Academy of Sciences, Moscow (Russian Federation); Moscow Institute of Physics and Technology, Dolgoprudny (Russian Federation); Shapiro, D.S. [N.L. Dukhov All-Russia Research Institute of Automatics, Moscow (Russian Federation); Moscow Institute of Physics and Technology, Dolgoprudny (Russian Federation); V.A. Kotel' nikov Institute of Radio Engineering and Electronics, Russian Academy of Sciences, Moscow (Russian Federation); National University of Science and Technology MISIS, Moscow (Russian Federation); Bork, L.V. [N.L. Dukhov All-Russia Research Institute of Automatics, Moscow (Russian Federation); Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Onishchenko, A.I. [Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, Dubna (Russian Federation); Moscow Institute of Physics and Technology, Dolgoprudny (Russian Federation); Skobeltsyn Institute of Nuclear Physics, Moscow State University, Moscow (Russian Federation)

    2017-06-15

    We consider an exactly solvable inhomogeneous Dicke model which describes an interaction between a disordered ensemble of two-level systems with single mode boson field. The existing method for evaluation of Richardson–Gaudin equations in the thermodynamical limit is extended to the case of Bethe equations in Dicke model. Using this extension, we present expressions both for the ground state and lowest excited states energies as well as leading-order finite-size corrections to these quantities for an arbitrary distribution of individual spin energies. We then evaluate these quantities for an equally-spaced distribution (constant density of states). In particular, we study evolution of the spectral gap and other related quantities. We also reveal regions on the phase diagram, where finite-size corrections are of particular importance.

  3. Analytical realization of finite-size scaling for Anderson localization. Does the band of critical states exist for d > 2?

    International Nuclear Information System (INIS)

    Suslov, I. M.

    2006-01-01

    An analytical realization is suggested for the finite-size scaling algorithm based on the consideration of auxiliary quasi-1D systems. Comparison of the obtained analytical results with the results of numerical calculations indicates that the Anderson transition point splits into the band of critical states. This conclusion is supported by direct numerical evidence (Edwards, Thouless, 1972; Last, Thouless, 1974; Schreiber, 1985). The possibility of restoring the conventional picture still exists but requires a radical reinterpretation of the raw numerical data

  4. Excited-state quantum phase transitions in systems with two degrees of freedom: II. Finite-size effects

    Energy Technology Data Exchange (ETDEWEB)

    Stránský, Pavel [Institute of Particle and Nuclear Physics, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, 18000 Prague (Czech Republic); Macek, Michal [Institute of Particle and Nuclear Physics, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, 18000 Prague (Czech Republic); Center for Theoretical Physics, Sloane Physics Laboratory, Yale University, New Haven, CT 06520-8120 (United States); Leviatan, Amiram [Racah Institute of Physics, The Hebrew University, 91904 Jerusalem (Israel); Cejnar, Pavel, E-mail: pavel.cejnar@mff.cuni.cz [Institute of Particle and Nuclear Physics, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, 18000 Prague (Czech Republic)

    2015-05-15

    This article extends our previous analysis Stránský et al. (2014) of Excited-State Quantum Phase Transitions (ESQPTs) in systems of dimension two. We focus on the oscillatory component of the quantum state density in connection with ESQPT structures accompanying a first-order ground-state transition. It is shown that a separable (integrable) system can develop rather strong finite-size precursors of ESQPT expressed as singularities in the oscillatory component of the state density. The singularities originate in effectively 1-dimensional dynamics and in some cases appear in multiple replicas with increasing excitation energy. Using a specific model example, we demonstrate that these precursors are rather resistant to proliferation of chaotic dynamics. - Highlights: • Oscillatory components of state density and spectral flow studied near ESQPTs. • Enhanced finite-size precursors of ESQPT caused by fully/partly separable dynamics. • These precursors appear due to criticality of a subsystem with lower dimension. • Separability-induced finite-size effects disappear in case of fully chaotic dynamics.

  5. Thermodynamic theory of intrinsic finite size effects in PbTiO3 nanocrystals. II. Dielectric and piezoelectric properties

    Science.gov (United States)

    Akdogan, E. K.; Safari, A.

    2007-03-01

    We compute the intrinsic dielectric and piezoelectric properties of single domain, mechanically free, and surface charge compensated PbTiO3 nanocrystals (n-Pt) with no depolarization fields, undergoing a finite size induced first order tetragonal→cubic ferrodistortive phase transition. By using a Landau-Devonshire type free energy functional, in which Landau coefficients are a function of nanoparticle size, we demonstrate substantial deviations from bulk properties in the range <150 nm. We find a decrease in dielectric susceptibility at the transition temperature with decreasing particle size, which we verify to be in conformity with predictions of lattice dynamics considerations. We also find an anomalous increase in piezocharge coefficients near ˜15 nm , the critical size for n-Pt.

  6. Electronic states in crystals of finite size quantum confinement of bloch waves

    CERN Document Server

    Ren, Shang Yuan

    2017-01-01

    This book presents an analytical theory of the electronic states in ideal low dimensional systems and finite crystals based on a differential equation theory approach. It provides precise and fundamental understandings on the electronic states in ideal low-dimensional systems and finite crystals, and offers new insights into some of the basic problems in low-dimensional systems, such as the surface states and quantum confinement effects, etc., some of which are quite different from what is traditionally believed in the solid state physics community. Many previous predictions have been confirmed in subsequent investigations by other authors on various relevant problems. In this new edition, the theory is further extended to one-dimensional photonic crystals and phononic crystals, and a general theoretical formalism for investigating the existence and properties of surface states/modes in semi-infinite one-dimensional crystals is developed. In addition, there are various revisions and improvements, including us...

  7. Modeling and Analysis of Size-Dependent Structural Problems by Using Low- Order Finite Elements with Strain Gradient Plasticity

    International Nuclear Information System (INIS)

    Park, Moon Shik; Suh, Yeong Sung; Song, Seung

    2011-01-01

    An elasto-plastic finite element method using the theory of strain gradient plasticity is proposed to evaluate the size dependency of structural plasticity that occurs when the configuration size decreases to micron scale. For this method, we suggest a low-order plane and three-dimensional displacement-based elements, eliminating the need for a high order, many degrees of freedom, a mixed element, or super elements, which have been considered necessary in previous researches. The proposed method can be performed in the framework of nonlinear incremental analysis in which plastic strains are calculated and averaged at nodes. These strains are then interpolated and differentiated for gradient calculation. We adopted a strain-gradient-hardening constitutive equation from the Taylor dislocation model, which requires the plastic strain gradient. The developed finite elements are tested numerically on the basis of typical size-effect problems such as micro-bending, micro-torsion, and micro-voids. With respect to the strain gradient plasticity, i.e., the size effects, the results obtained by using the proposed method, which are simple in their calculation, are in good agreement with the experimental results cited in previously published papers

  8. Insights on finite size effects in ab initio study of CO adsorption and dissociation on Fe 110 surface

    International Nuclear Information System (INIS)

    Chakrabarty, Aurab; Bouhali, Othmane; Mousseau, Normand; Becquart, Charlotte S.; El-Mellouhi, Fedwa

    2016-01-01

    Adsorption and dissociation of hydrocarbons on metallic surfaces represent crucial steps on the path to carburization, eventually leading to dusting corrosion. While adsorption of CO molecules on Fe surface is a barrier-less exothermic process, this is not the case for the dissociation of CO into C and O adatoms and the diffusion of C beneath the surface that are found to be associated with large energy barriers. In practice, these barriers can be affected by numerous factors that combine to favour the CO-Fe reaction such as the abundance of CO and other hydrocarbons as well as the presence of structural defects. From a numerical point of view, studying these factors is challenging and a step-by-step approach is necessary to assess, in particular, the influence of the finite box size on the reaction parameters for adsorption and dissociation of CO on metal surfaces. Here, we use density functional theory (DFT) total energy calculations with the climbing-image nudged elastic band method to estimate the adsorption energies and dissociation barriers for different CO coverages with surface supercells of different sizes. We further compute the effect of periodic boundary condition for DFT calculations and find that the contribution from van der Waals interaction in the computation of adsorption parameters is important as they contribute to correcting the finite-size error in small systems. The dissociation process involves carbon insertion into the Fe surface causing a lattice deformation that requires a larger surface system for unrestricted relaxation. We show that, in the larger surface systems associated with dilute CO-coverages, C-insertion is energetically more favourable, leading to a significant decrease in the dissociation barrier. This observation suggests that a large surface system with dilute coverage is necessary for all similar metal-hydrocarbon reactions in order to study their fundamental electronic mechanisms, as an isolated phenomenon, free from

  9. Insights on finite size effects in ab initio study of CO adsorption and dissociation on Fe 110 surface

    Energy Technology Data Exchange (ETDEWEB)

    Chakrabarty, Aurab, E-mail: aurab.chakrabarty@qatar.tamu.edu; Bouhali, Othmane [Texas A& M University at Qatar, P.O. Box 23874, Doha (Qatar); Mousseau, Normand [Département de Physique and RQMP, Université de Montréal, Case Postale 6128, Succursale Centre-ville, Montréal, Québec H3C 3J7 (Canada); Becquart, Charlotte S. [UMET, UMR CNRS 8207, ENSCL, Université Lille I, 59655 Villeneuve d' Ascq Cédex (France); El-Mellouhi, Fedwa [Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, P.O. Box 5825, Doha (Qatar)

    2016-08-07

    Adsorption and dissociation of hydrocarbons on metallic surfaces represent crucial steps on the path to carburization, eventually leading to dusting corrosion. While adsorption of CO molecules on Fe surface is a barrier-less exothermic process, this is not the case for the dissociation of CO into C and O adatoms and the diffusion of C beneath the surface that are found to be associated with large energy barriers. In practice, these barriers can be affected by numerous factors that combine to favour the CO-Fe reaction such as the abundance of CO and other hydrocarbons as well as the presence of structural defects. From a numerical point of view, studying these factors is challenging and a step-by-step approach is necessary to assess, in particular, the influence of the finite box size on the reaction parameters for adsorption and dissociation of CO on metal surfaces. Here, we use density functional theory (DFT) total energy calculations with the climbing-image nudged elastic band method to estimate the adsorption energies and dissociation barriers for different CO coverages with surface supercells of different sizes. We further compute the effect of periodic boundary condition for DFT calculations and find that the contribution from van der Waals interaction in the computation of adsorption parameters is important as they contribute to correcting the finite-size error in small systems. The dissociation process involves carbon insertion into the Fe surface causing a lattice deformation that requires a larger surface system for unrestricted relaxation. We show that, in the larger surface systems associated with dilute CO-coverages, C-insertion is energetically more favourable, leading to a significant decrease in the dissociation barrier. This observation suggests that a large surface system with dilute coverage is necessary for all similar metal-hydrocarbon reactions in order to study their fundamental electronic mechanisms, as an isolated phenomenon, free from

  10. Size validity of plasma-metamaterial cloaking monitored by scattering wave in finite-difference time-domain method

    Directory of Open Access Journals (Sweden)

    Alexandre Bambina

    2018-01-01

    Full Text Available Limitation of the cloak-size reduction is investigated numerically by a finite-difference time-domain (FDTD method. A metallic pole that imitates an antenna is cloaked with an anisotropic and parameter-gradient medium against electromagnetic-wave propagation in microwave range. The cloaking structure is a metamaterial submerged in a plasma confined in a vacuum chamber made of glass. The smooth-permittivity plasma can be compressed in the radial direction, which enables us to decrease the size of the cloak. Theoretical analysis is performed numerically by comparing scattering waves in various cases; there exists a high reduction of the scattering wave when the radius of the cloak is larger than a quarter of one wavelength. This result indicates that the required size of the cloaking layer is more than an object scale in the Rayleigh scattering regime.

  11. Synchronization of oscillators with long range interaction: Phase transition and anomalous finite size effects

    DEFF Research Database (Denmark)

    Marodi, M.; D'ovidio, Francesco; Vicsek, T.

    2002-01-01

    of elements. For large number of oscillators and small coupling constant, numerical simulations and analytical arguments indicate that a phase transition separating synchronization from incoherence appears at a decay exponent value equal to the number of dimensions of the lattice. In contrast with earlier......Synchronization in a lattice of a finite population of phase oscillators with algebraically decaying, non-normalized coupling is studied by numerical simulations. A critical level of decay is found, below which full locking takes place if the population contains a sufficiently large number...

  12. Finite size effects on the experimental observables of the Glauber model: a theoretical and experimental investigation

    International Nuclear Information System (INIS)

    Vindigni, A.; Bogani, L.; Gatteschi, D.; Sessoli, R.; Rettori, A.; Novak, M.A.

    2004-01-01

    We investigate the relaxation time, τ, of a dilute Glauber kinetic Ising chain obtained by ac susceptibility and SQUID magnetometry on a Co(II)-organic radical Ising 1D ferrimagnet doped with Zn(II). Theoretically we predicted a crossover in the temperature-dependence of τ, when the average segment is of the same order of the correlation length. Comparing the experimental results with theory we conclude that in the investigated temperature range the correlation length exceeds the finite length also in the pure sample

  13. Finite size effects on the experimental observables of the Glauber model: a theoretical and experimental investigation

    Energy Technology Data Exchange (ETDEWEB)

    Vindigni, A. E-mail: alessandro.vindigni@unifi.it; Bogani, L.; Gatteschi, D.; Sessoli, R.; Rettori, A.; Novak, M.A

    2004-05-01

    We investigate the relaxation time, {tau}, of a dilute Glauber kinetic Ising chain obtained by ac susceptibility and SQUID magnetometry on a Co(II)-organic radical Ising 1D ferrimagnet doped with Zn(II). Theoretically we predicted a crossover in the temperature-dependence of {tau}, when the average segment is of the same order of the correlation length. Comparing the experimental results with theory we conclude that in the investigated temperature range the correlation length exceeds the finite length also in the pure sample.

  14. Finite size effects on the experimental observables of the Glauber model: a theoretical and experimental investigation

    Science.gov (United States)

    Vindigni, A.; Bogani, L.; Gatteschi, D.; Sessoli, R.; Rettori, A.; Novak, M. A.

    2004-05-01

    We investigate the relaxation time, τ, of a dilute Glauber kinetic Ising chain obtained by ac susceptibility and SQUID magnetometry on a Co(II)-organic radical Ising 1D ferrimagnet doped with Zn(II). Theoretically we predicted a crossover in the temperature-dependence of τ, when the average segment is of the same order of the correlation length. Comparing the experimental results with theory we conclude that in the investigted temperature range the correlation length exceeds the finite length also in the pure sample.

  15. Finite-size effect on the dynamic and sensing performances of graphene resonators: the role of edge stress.

    Science.gov (United States)

    Kim, Chang-Wan; Dai, Mai Duc; Eom, Kilho

    2016-01-01

    We have studied the finite-size effect on the dynamic behavior of graphene resonators and their applications in atomic mass detection using a continuum elastic model such as modified plate theory. In particular, we developed a model based on von Karman plate theory with including the edge stress, which arises from the imbalance between the coordination numbers of bulk atoms and edge atoms of graphene. It is shown that as the size of a graphene resonator decreases, the edge stress depending on the edge structure of a graphene resonator plays a critical role on both its dynamic and sensing performances. We found that the resonance behavior of graphene can be tuned not only through edge stress but also through nonlinear vibration, and that the detection sensitivity of a graphene resonator can be controlled by using the edge stress. Our study sheds light on the important role of the finite-size effect in the effective design of graphene resonators for their mass sensing applications.

  16. Effect of Finite Particle Size on Convergence of Point Particle Models in Euler-Lagrange Multiphase Dispersed Flow

    Science.gov (United States)

    Nili, Samaun; Park, Chanyoung; Haftka, Raphael T.; Kim, Nam H.; Balachandar, S.

    2017-11-01

    Point particle methods are extensively used in simulating Euler-Lagrange multiphase dispersed flow. When particles are much smaller than the Eulerian grid the point particle model is on firm theoretical ground. However, this standard approach of evaluating the gas-particle coupling at the particle center fails to converge as the Eulerian grid is reduced below particle size. We present an approach to model the interaction between particles and fluid for finite size particles that permits convergence. We use the generalized Faxen form to compute the force on a particle and compare the results against traditional point particle method. We apportion the different force components on the particle to fluid cells based on the fraction of particle volume or surface in the cell. The application is to a one-dimensional model of shock propagation through a particle-laden field at moderate volume fraction, where the convergence is achieved for a well-formulated force model and back coupling for finite size particles. Comparison with 3D direct fully resolved numerical simulations will be used to check if the approach also improves accuracy compared to the point particle model. Work supported by the U.S. Department of Energy, National Nuclear Security Administration, Advanced Simulation and Computing Program, as a Cooperative Agreement under the Predictive Science Academic Alliance Program, under Contract No. DE-NA0002378.

  17. SMPBS: Web server for computing biomolecular electrostatics using finite element solvers of size modified Poisson-Boltzmann equation.

    Science.gov (United States)

    Xie, Yang; Ying, Jinyong; Xie, Dexuan

    2017-03-30

    SMPBS (Size Modified Poisson-Boltzmann Solvers) is a web server for computing biomolecular electrostatics using finite element solvers of the size modified Poisson-Boltzmann equation (SMPBE). SMPBE not only reflects ionic size effects but also includes the classic Poisson-Boltzmann equation (PBE) as a special case. Thus, its web server is expected to have a broader range of applications than a PBE web server. SMPBS is designed with a dynamic, mobile-friendly user interface, and features easily accessible help text, asynchronous data submission, and an interactive, hardware-accelerated molecular visualization viewer based on the 3Dmol.js library. In particular, the viewer allows computed electrostatics to be directly mapped onto an irregular triangular mesh of a molecular surface. Due to this functionality and the fast SMPBE finite element solvers, the web server is very efficient in the calculation and visualization of electrostatics. In addition, SMPBE is reconstructed using a new objective electrostatic free energy, clearly showing that the electrostatics and ionic concentrations predicted by SMPBE are optimal in the sense of minimizing the objective electrostatic free energy. SMPBS is available at the URL: smpbs.math.uwm.edu © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  18. Finite-size effect of the dyonic giant magnons in N=6 super Chern-Simons theory

    International Nuclear Information System (INIS)

    Ahn, Changrim; Bozhilov, P.

    2009-01-01

    We consider finite-size effects for the dyonic giant magnon of the type IIA string theory on AdS 4 xCP 3 by applying the Luescher μ-term formula which is derived from a recently proposed S matrix for the N=6 super Chern-Simons theory. We compute explicitly the effect for the case of a symmetric configuration where the two external bound states, each of A and B particles, have the same momentum p and spin J 2 . We compare this with the classical string theory result which we computed by reducing it to the Neumann-Rosochatius system. The two results match perfectly.

  19. Radiative nonrecoil nuclear finite size corrections of order α(Zα)5 to the Lamb shift in light muonic atoms

    Science.gov (United States)

    Faustov, R. N.; Martynenko, A. P.; Martynenko, F. A.; Sorokin, V. V.

    2017-12-01

    On the basis of quasipotential method in quantum electrodynamics we calculate nuclear finite size radiative corrections of order α(Zα) 5 to the Lamb shift in muonic hydrogen and helium. To construct the interaction potential of particles, which gives the necessary contributions to the energy spectrum, we use the method of projection operators to states with a definite spin. Separate analytic expressions for the contributions of the muon self-energy, the muon vertex operator and the amplitude with spanning photon are obtained. We present also numerical results for these contributions using modern experimental data on the electromagnetic form factors of light nuclei.

  20. The exact solution and the finite-size behaviour of the Osp(1vertical stroke 2)-invariant spin chain

    International Nuclear Information System (INIS)

    Martins, M.J.

    1995-01-01

    We have solved exactly the Osp(1vertical stroke 2) spin chain by the Bethe ansatz approach. Our solution is based on an equivalence between the Osp(1vertical stroke 2) chain and a certain special limit of the Izergin-Korepin vertex model. The completeness of the Bethe ansatz equations is discussed for a system with four sites and the appearance of special string structures is noted. The Bethe ansatz presents an important phase factor which distinguishes the even and odd sectors of the theory. The finite-size properties are governed by a conformal field theory with central charge c=1. (orig.)

  1. Suppression of bottomonia states in finite size quark gluon plasma in PbPb collisions at LHC

    International Nuclear Information System (INIS)

    Shukla, P.; Abdulsalam, Abdulla; Kumar, Vineet

    2012-01-01

    The paper estimated the suppression of bottomonium states in an expanding QGP of finite lifetime and size with the conditions relevant for PbPb collisions at LHC. The recent results on the properties of ϒ states have been used as ingredient in the study. The nuclear modification factor and the ratios of yields of ϒ states are then obtained as a function of transverse momentum and centrality. The study has compared the calculations with the bottomonia yields measured in Pb+Pb collisions at √S NN = 2.76 TeV

  2. Finite size giant magnons in the SU(2) x SU(2) sector of AdS4 x CP3

    International Nuclear Information System (INIS)

    Lukowski, Tomasz; Sax, Olof Ohlsson

    2008-01-01

    We use the algebraic curve and Luescher's μ-term to calculate the leading order finite size corrections to the dispersion relation of giant magnons in the SU(2) x SU(2) sector of AdS 4 x CP 3 . We consider a single magnon as well as one magnon in each SU(2). In addition the algebraic curve computation is generalized to give the leading order correction for an arbitrary multi-magnon state in the SU(2) x SU(2) sector.

  3. Finite-size effect of η-deformed AdS5×S5 at strong coupling

    Directory of Open Access Journals (Sweden)

    Changrim Ahn

    2017-04-01

    Full Text Available We compute Lüscher corrections for a giant magnon in the η-deformed (AdS5×S5η using the su(2|2q-invariant S-matrix at strong coupling and compare with the finite-size effect of the corresponding string state, derived previously. We find that these two results match and confirm that the su(2|2q-invariant S-matrix is describing world-sheet excitations of the η-deformed background.

  4. Finite size effects in the thermodynamics of a free neutral scalar field

    Science.gov (United States)

    Parvan, A. S.

    2018-04-01

    The exact analytical lattice results for the partition function of the free neutral scalar field in one spatial dimension in both the configuration and the momentum space were obtained in the framework of the path integral method. The symmetric square matrices of the bilinear forms on the vector space of fields in both configuration space and momentum space were found explicitly. The exact lattice results for the partition function were generalized to the three-dimensional spatial momentum space and the main thermodynamic quantities were derived both on the lattice and in the continuum limit. The thermodynamic properties and the finite volume corrections to the thermodynamic quantities of the free real scalar field were studied. We found that on the finite lattice the exact lattice results for the free massive neutral scalar field agree with the continuum limit only in the region of small values of temperature and volume. However, at these temperatures and volumes the continuum physical quantities for both massive and massless scalar field deviate essentially from their thermodynamic limit values and recover them only at high temperatures or/and large volumes in the thermodynamic limit.

  5. Elastodynamic models for extending GTD to penumbra and finite size flaws

    International Nuclear Information System (INIS)

    Djakou, A Kamta; Darmon, M; Potel, C

    2016-01-01

    The scattering of elastic waves from an obstacle is of great interest in ultrasonic Non Destructive Evaluation (NDE). There exist two main scattering phenomena: specular reflection and diffraction. This paper is especially focused on possible improvements of the Geometrical Theory of Diffraction (GTD), one classical method used for modelling diffraction from scatterer edges. GTD notably presents two important drawbacks: it is theoretically valid for a canonical infinite edge and not for a finite one and presents discontinuities around the direction of specular reflection. In order to address the first drawback, a 3D hybrid method using both GTD and Huygens secondary sources has been developed to deal with finite flaws. ITD (Incremental Theory of Diffraction), a method developed in electromagnetism, has also been developed in elastodynamics to deal with small flaws. Experimental validation of these methods has been performed. As to the second drawback, a GTD uniform correction, the UTD (Uniform Theory of Diffraction) has been developed in the view of designing a generic model able to correctly simulate both specular reflection and diffraction. A comparison has been done between UTD numerical results and UAT (Uniform Asymptotic Theory of Diffraction) which is another uniform solution of GTD. (paper)

  6. Finite-size effects in thermodynamics: Negative compressibility and global instability in two-phase systems

    Science.gov (United States)

    Todoshchenko, I.

    2018-04-01

    We have measured the equilibrium melting pressure of helium-4 as a function of the crystal size. Negative compressibility of a liquid with an inclusion of solid seed is predicted theoretically and verified experimentally with helium-4 crystal-superfluid system at 0.15 K. This two-phase system is shown to be stable if the crystal size is large enough, which is proven by the experiment. Crystal seeds that are too small spontaneously either melt completely or grow to a large enough size.

  7. Fault-ignorant quantum search

    International Nuclear Information System (INIS)

    Vrana, Péter; Reeb, David; Reitzner, Daniel; Wolf, Michael M

    2014-01-01

    We investigate the problem of quantum searching on a noisy quantum computer. Taking a fault-ignorant approach, we analyze quantum algorithms that solve the task for various different noise strengths, which are possibly unknown beforehand. We prove lower bounds on the runtime of such algorithms and thereby find that the quadratic speedup is necessarily lost (in our noise models). However, for low but constant noise levels the algorithms we provide (based on Grover's algorithm) still outperform the best noiseless classical search algorithm. (paper)

  8. Renormalization group and finite size effects in scalar lattice field theories

    International Nuclear Information System (INIS)

    Bernreuther, W.; Goeckeler, M.

    1988-01-01

    Binder's phenomenological renormalization group is studied in the context of the O(N)-symmetric euclidean lattice φ 4 theory in dimensions d ≤ 4. By means of the field theoretical formulation of the renormalization group we analyse suitable ratios of Green functions on finite lattices in the limit where the dimensionless lattice length L >> 1 and where the dimensionless bare mass approaches the critical point of the corresponding infinite volume model. If the infrared-stable fixed point which controls this limit is a simple zero of the β-function we are led to formulae which allow the extraction of the critical exponents ν and η. For the gaussian fixed point in four dimensions, discussed as a known example for a multiple zero of the β-function, we derive for these ratios the leading logarithmic corrections to mean field scaling. (orig.)

  9. Phase transition in the rich-get-richer mechanism due to finite-size effects

    International Nuclear Information System (INIS)

    Bagrow, James P; Ben-Avraham, Daniel; Sun Jie

    2008-01-01

    The rich-get-richer mechanism (agents increase their 'wealth' randomly at a rate proportional to their holdings) is often invoked to explain the Pareto power-law distribution observed in many physical situations, such as the degree distribution of growing scale-free nets. We use two different analytical approaches, as well as numerical simulations, to study the case where the number of agents is fixed and finite (but large), and the rich-get-richer mechanism is invoked a fraction r of the time (the remainder of the time wealth is disbursed by a homogeneous process). At short times, we recover the Pareto law observed for an unbounded number of agents. In later times, the (moving) distribution can be scaled to reveal a phase transition with a Gaussian asymptotic form for r<1/2, and a Pareto-like tail (on the positive side) and a novel stretched exponential decay (on the negative side) for r<1/2

  10. Three-dimensional simulation of diamagnetic cavity formation by a finite-sized plasma beam

    International Nuclear Information System (INIS)

    Thomas, V.A.

    1989-01-01

    The problem of collisionless coupling between a plasma beam and a background plasma is examined using a three-dimensional hybrid code. The beam is assumed to be moving parallel to an ambient magnetic field at a speed greater than the local Alfven speed. In addition, the beam has a finite spatial extent in the directions perpendicular to the magnetic field and is uniform and infinite in the direction parallel to the ambient magnetic field. Such a system is susceptible to coupling of the beam ions with the background ions via an electromagnetic ion beam instability. This instability isotropizes the beam and energizes the background plasma. A large-amplitude Alfven wave traveling radially away from the interaction region is associated with the energized background plasma. The process described here is one which may be responsible for the formation of diamagnetic cavities observed in the solar wind. copyright American Geophysical Union 1989

  11. Element size and other restrictions in finite-element modeling of reinforced concrete at elevated temperatures

    DEFF Research Database (Denmark)

    Carstensen, Josephine Voigt; Jomaas, Grunde; Pankaj, Pankaj

    2013-01-01

    to extend this approach for RC at elevated temperatures. Prior to the extension, the approach is investigated for associated modeling issues and a set of limits of application are formulated. The available models of the behavior of plain concrete at elevated temperatures were used to derive inherent......One of the accepted approaches for postpeak finite-element modeling of RC comprises combining plain concrete, reinforcement, and interaction behaviors. In these, the postpeak strain-softening behavior of plain concrete is incorporated by the use of fracture energy concepts. This study attempts...... fracture energy variation with temperature. It is found that the currently used tensile elevated temperature model assumes that the fracture energy decays with temperature. The existing models in compression also show significant decay of fracture energy at higher temperatures (>400°) and a considerable...

  12. Finite element method calculations of GMI in thin films and sandwiched structures: Size and edge effects

    International Nuclear Information System (INIS)

    Garcia-Arribas, A.; Barandiaran, J.M.; Cos, D. de

    2008-01-01

    The impedance values of magnetic thin films and magnetic/conductor/magnetic sandwiched structures with different widths are computed using the finite element method (FEM). The giant magneto-impedance (GMI) is calculated from the difference of the impedance values obtained with high and low permeability of the magnetic material. The results depend considerably on the width of the sample, demonstrating that edge effects are decisive for the GMI performance. It is shown that, besides the usual skin effect that is responsible for GMI, an 'unexpected' increase of the current density takes place at the lateral edge of the sample. In magnetic thin films this effect is dominant when the permeability is low. In the trilayers, it is combined with the lack of shielding of the central conductor at the edge. The resulting effects on GMI are shown to be large for both kinds of samples. The conclusions of this study are of great importance for the successful design of miniaturized GMI devices

  13. Finite-size and asymptotic behaviors of the gyration radius of knotted cylindrical self-avoiding polygons.

    Science.gov (United States)

    Shimamura, Miyuki K; Deguchi, Tetsuo

    2002-05-01

    Several nontrivial properties are shown for the mean-square radius of gyration R2(K) of ring polymers with a fixed knot type K. Through computer simulation, we discuss both finite size and asymptotic behaviors of the gyration radius under the topological constraint for self-avoiding polygons consisting of N cylindrical segments with radius r. We find that the average size of ring polymers with the knot K can be much larger than that of no topological constraint. The effective expansion due to the topological constraint depends strongly on the parameter r that is related to the excluded volume. The topological expansion is particularly significant for the small r case, where the simulation result is associated with that of random polygons with the knot K.

  14. Diffusion of finite-sized hard-core interacting particles in a one-dimensional box: Tagged particle dynamics.

    Science.gov (United States)

    Lizana, L; Ambjörnsson, T

    2009-11-01

    We solve a nonequilibrium statistical-mechanics problem exactly, namely, the single-file dynamics of N hard-core interacting particles (the particles cannot pass each other) of size Delta diffusing in a one-dimensional system of finite length L with reflecting boundaries at the ends. We obtain an exact expression for the conditional probability density function rhoT(yT,t|yT,0) that a tagged particle T (T=1,...,N) is at position yT at time t given that it at time t=0 was at position yT,0. Using a Bethe ansatz we obtain the N -particle probability density function and, by integrating out the coordinates (and averaging over initial positions) of all particles but particle T , we arrive at an exact expression for rhoT(yT,t|yT,0) in terms of Jacobi polynomials or hypergeometric functions. Going beyond previous studies, we consider the asymptotic limit of large N , maintaining L finite, using a nonstandard asymptotic technique. We derive an exact expression for rhoT(yT,t|yT,0) for a tagged particle located roughly in the middle of the system, from which we find that there are three time regimes of interest for finite-sized systems: (A) for times much smaller than the collision time tparticle concentration and D is the diffusion constant for each particle, the tagged particle undergoes a normal diffusion; (B) for times much larger than the collision time t >taucoll but times smaller than the equilibrium time ttaue , rhoT(yT,t|yT,0) approaches a polynomial-type equilibrium probability density function. Notably, only regimes (A) and (B) are found in the previously considered infinite systems.

  15. Adaptive beamlet-based finite-size pencil beam dose calculation for independent verification of IMRT and VMAT.

    Science.gov (United States)

    Park, Justin C; Li, Jonathan G; Arhjoul, Lahcen; Yan, Guanghua; Lu, Bo; Fan, Qiyong; Liu, Chihray

    2015-04-01

    The use of sophisticated dose calculation procedure in modern radiation therapy treatment planning is inevitable in order to account for complex treatment fields created by multileaf collimators (MLCs). As a consequence, independent volumetric dose verification is time consuming, which affects the efficiency of clinical workflow. In this study, the authors present an efficient adaptive beamlet-based finite-size pencil beam (AB-FSPB) dose calculation algorithm that minimizes the computational procedure while preserving the accuracy. The computational time of finite-size pencil beam (FSPB) algorithm is proportional to the number of infinitesimal and identical beamlets that constitute an arbitrary field shape. In AB-FSPB, dose distribution from each beamlet is mathematically modeled such that the sizes of beamlets to represent an arbitrary field shape no longer need to be infinitesimal nor identical. As a result, it is possible to represent an arbitrary field shape with combinations of different sized and minimal number of beamlets. In addition, the authors included the model parameters to consider MLC for its rounded edge and transmission. Root mean square error (RMSE) between treatment planning system and conventional FSPB on a 10 × 10 cm(2) square field using 10 × 10, 2.5 × 2.5, and 0.5 × 0.5 cm(2) beamlet sizes were 4.90%, 3.19%, and 2.87%, respectively, compared with RMSE of 1.10%, 1.11%, and 1.14% for AB-FSPB. This finding holds true for a larger square field size of 25 × 25 cm(2), where RMSE for 25 × 25, 2.5 × 2.5, and 0.5 × 0.5 cm(2) beamlet sizes were 5.41%, 4.76%, and 3.54% in FSPB, respectively, compared with RMSE of 0.86%, 0.83%, and 0.88% for AB-FSPB. It was found that AB-FSPB could successfully account for the MLC transmissions without major discrepancy. The algorithm was also graphical processing unit (GPU) compatible to maximize its computational speed. For an intensity modulated radiation therapy (∼12 segments) and a volumetric modulated arc

  16. Overcoming time scale and finite size limitations to compute nucleation rates from small scale well tempered metadynamics simulations

    Science.gov (United States)

    Salvalaglio, Matteo; Tiwary, Pratyush; Maggioni, Giovanni Maria; Mazzotti, Marco; Parrinello, Michele

    2016-12-01

    Condensation of a liquid droplet from a supersaturated vapour phase is initiated by a prototypical nucleation event. As such it is challenging to compute its rate from atomistic molecular dynamics simulations. In fact at realistic supersaturation conditions condensation occurs on time scales that far exceed what can be reached with conventional molecular dynamics methods. Another known problem in this context is the distortion of the free energy profile associated to nucleation due to the small, finite size of typical simulation boxes. In this work the problem of time scale is addressed with a recently developed enhanced sampling method while contextually correcting for finite size effects. We demonstrate our approach by studying the condensation of argon, and showing that characteristic nucleation times of the order of magnitude of hours can be reliably calculated. Nucleation rates spanning a range of 10 orders of magnitude are computed at moderate supersaturation levels, thus bridging the gap between what standard molecular dynamics simulations can do and real physical systems.

  17. The critical behaviour of self-dual Z(N) spin systems - Finite size scaling and conformal invariance

    International Nuclear Information System (INIS)

    Alcaraz, F.C.

    1986-01-01

    Critical properties of a family of self-dual two dimensional Z(N) models whose bulk free energy is exacly known at the self-dual point are studied. The analysis is performed by studing the finite size behaviour of the corresponding one dimensional quantum Hamiltonians which also possess an exact solution at their self-dual point. By exploring finite size scaling ideas and the conformal invariance of the critical infinite system the critical temperature and critical exponents as well as the central charge associated with the underlying conformal algebra are calculated for N up to 8. The results strongly suggest that the recently constructed Z(N) quantum field theory of Zamolodchikov and Fateev (1985) is the underlying field theory associated with these statistical mechanical systems. It is also tested, for the Z(5) case, the conjecture that these models correspond to the bifurcation points, in the phase diagram of the general Z(N) spin model, where a massless phase originates. (Author) [pt

  18. Hierarchical finite element modeling of SiCp/Al2124 T4 composites with dislocation plasticity and size dependent failure

    International Nuclear Information System (INIS)

    Suh, Yeong Sung; Kim, Yong Bae

    2012-01-01

    The strength of particle reinforced metal matrix composites is, in general, known to be increased by the geometrically necessary dislocations punched around a particle that form during cooling after consolidation because of coefficient of thermal expansion (CTE) mismatch between the particle and the matrix. An additional strength increase may also be observed, since another type of geometrically necessary dislocation can be formed during extensive deformation as a result of the strain gradient plasticity due to the elastic plastic mismatch between the particle and the matrix. In this paper, the magnitudes of these two types of dislocations are calculated based on the dislocation plasticity. The dislocations are then converted to the respective strengths and allocated hierarchically to the matrix around the particle in the axisymmetric finite element unit cell model. the proposed method is shown to be very effective by performing finite element strength analysis of SiC p /Al2124 T4 composites that included ductile in the matrix and particle matrix decohesion. The predicted results for different particle sizes and volume fractions show that the length scale effect of the particle size obviously affects the strength and failure behavior of the particle reinforced metal matrix composites

  19. Forced sound transmission through a finite-sized single leaf panel subject to a point source excitation.

    Science.gov (United States)

    Wang, Chong

    2018-03-01

    In the case of a point source in front of a panel, the wavefront of the incident wave is spherical. This paper discusses spherical sound waves transmitting through a finite sized panel. The forced sound transmission performance that predominates in the frequency range below the coincidence frequency is the focus. Given the point source located along the centerline of the panel, forced sound transmission coefficient is derived through introducing the sound radiation impedance for spherical incident waves. It is found that in addition to the panel mass, forced sound transmission loss also depends on the distance from the source to the panel as determined by the radiation impedance. Unlike the case of plane incident waves, sound transmission performance of a finite sized panel does not necessarily converge to that of an infinite panel, especially when the source is away from the panel. For practical applications, the normal incidence sound transmission loss expression of plane incident waves can be used if the distance between the source and panel d and the panel surface area S satisfy d/S>0.5. When d/S ≈0.1, the diffuse field sound transmission loss expression may be a good approximation. An empirical expression for d/S=0  is also given.

  20. Guided wave radiation in a finite-sized metallic or composite plate-like structure for its nondestructive testing

    International Nuclear Information System (INIS)

    Stevenin, Mathilde

    2016-01-01

    Different models are developed to provide generic tools for simulating nondestructive methods relying on elastic guided waves applied to metallic or composite plates. Various inspection methods of these structures exist or are under study. Most of them make use of ultrasonic sources of finite size; all are sensitive to reflection phenomena resulting from the finite size of the monitored objects. The developed models deal with transducer diffraction effects and edge reflection. As the interpretation of signals measured in guided wave inspection often uses the concept of modes, the models themselves are explicitly modal. The case of isotropic plates (metal) and anisotropic (multilayer composites) are considered; a general approach under the stationary phase approximation allows us to consider all the cases of interest. For the first, the validity of a Fraunhofer-like approximation leads to a very efficient computation of the direct and reflected fields radiated by a source. For the second, special attention is paid to the treatment of caustics. The stationary phase approximation being difficult to generalize, a model (so-called 'pencil model') of more geometrical nature is proposed with a high degree of genericity. It chains terms of isotropic or anisotropic propagation and terms of interaction with a boundary. The equivalence of the stationary phase approximation and the pencil model is demonstrated in the case of the radiation and reflection in an isotropic plate, for which an experimental validation is proceeded. (author) [fr

  1. Numerical simulation of temperature distribution using finite difference equations and estimation of the grain size during friction stir processing

    International Nuclear Information System (INIS)

    Arora, H.S.; Singh, H.; Dhindaw, B.K.

    2012-01-01

    Highlights: ► Magnesium alloy AE42 was friction stir processed under different cooling conditions. ► Heat flow model was developed using finite difference heat equations. ► Generalized MATLAB code was developed for solving heat flow model. ► Regression equation for estimation of grain size was developed. - Abstract: The present investigation is aimed at developing a heat flow model to simulate temperature history during friction stir processing (FSP). A new approach of developing implicit form of finite difference heat equations solved using MATLAB code was used. A magnesium based alloy AE42 was friction stir processed (FSPed) at different FSP parameters and cooling conditions. Temperature history was continuously recorded in the nugget zone during FSP using data acquisition system and k type thermocouples. The developed code was validated at different FSP parameters and cooling conditions during FSP experimentation. The temperature history at different locations in the nugget zone at different instants of time was further utilized for the estimation of grain growth rate and final average grain size of the FSPed specimen. A regression equation relating the final grain size, maximum temperature during FSP and the cooling rate was developed. The metallurgical characterization was done using optical microscopy, SEM, and FIB-SIM analysis. The simulated temperature profiles and final average grain size were found to be in good agreement with the experimental results. The presence of fine precipitate particles generated in situ in the investigated magnesium alloy also contributed in the evolution of fine grain structure through Zener pining effect at the grain boundaries.

  2. Simultaneous Topology, Shape, and Sizing Optimisation of Plane Trusses with Adaptive Ground Finite Elements Using MOEAs

    Directory of Open Access Journals (Sweden)

    Norapat Noilublao

    2013-01-01

    Full Text Available This paper proposes a novel integrated design strategy to accomplish simultaneous topology shape and sizing optimisation of a two-dimensional (2D truss. An optimisation problem is posed to find a structural topology, shape, and element sizes of the truss such that two objective functions, mass and compliance, are minimised. Design constraints include stress, buckling, and compliance. The procedure for an adaptive ground elements approach is proposed and its encoding/decoding process is detailed. Two sets of design variables defining truss layout, shape, and element sizes at the same time are applied. A number of multiobjective evolutionary algorithms (MOEAs are implemented to solve the design problem. Comparative performance based on a hypervolume indicator shows that multiobjective population-based incremental learning (PBIL is the best performer. Optimising three design variable types simultaneously is more efficient and effective.

  3. Finite Size Effects in Chemical Bonding: From Small Clusters to Solids

    DEFF Research Database (Denmark)

    Kleis, Jesper; Greeley, Jeffrey Philip; Romero, N. A.

    2011-01-01

    We address the fundamental question of which size a metallic nano-particle needs to have before its surface chemical properties can be considered to be those of a solid, rather than those of a large molecule. Calculations of adsorption energies for carbon monoxide and oxygen on a series of gold...

  4. Reflection of sound from finite-size plane and curved surfaces

    DEFF Research Database (Denmark)

    Rindel, Jens Holger

    2005-01-01

    of a reflector array can improve if the size of the panels is decreased. The same design frequency applies to a single reflector and a reflector array, but with different meaning; in the latter case the design frequency is the upper limit for useful reflections. This design rule was first used...

  5. Finite size effects in a model for platicity of amorphous composites

    DEFF Research Database (Denmark)

    Tyukodi, Botond; Lemarchand, Claire A.; Hansen, Jesper Schmidt

    2016-01-01

    We discuss the plastic behavior of an amorphous matrix reinforced by hard particles. A mesoscopic depinning-like model accounting for Eshelby elastic interactions is implemented. Only the effect of a plastic disorder is considered. Numerical results show a complex size dependence of the effective...

  6. Two-dimensional quantum-corrected black hole in a finite size cavity

    International Nuclear Information System (INIS)

    Zaslavskii, O.B.

    2004-01-01

    We consider the gravitation-dilaton theory (not necessarily exactly solvable), whose potentials represent a generic linear combination of an exponential and linear functions of the dilaton. A black hole, arising in such theories, is supposed to be enclosed in a cavity, where it attains thermal equilibrium, whereas outside the cavity the field is in the Boulware state. We calculate quantum corrections to the Hawking temperature T H , with the contribution from the boundary taken into account. Vacuum polarization outside the shell tends to cool the system. We find that, for the shell to be in thermal equilibrium, it cannot be placed too close to the horizon. The quantum corrections to the mass due to vacuum polarization vanish in spite of nonzero quantum stresses. We discuss also the canonical boundary conditions and show that accounting for the finiteness of the system plays a crucial role in some theories (e.g., Callan-Giddings-Harvey-Strominger), where it enables us to define the stable canonical ensemble, whereas consideration in an infinite space would predict instability

  7. Finite size effects in phase transformation kinetics in thin films and surface layers

    International Nuclear Information System (INIS)

    Trofimov, Vladimir I.; Trofimov, Ilya V.; Kim, Jong-Il

    2004-01-01

    In studies of phase transformation kinetics in thin films, e.g. crystallization of amorphous films, until recent time is widely used familiar Kolmogorov-Johnson-Mehl-Avrami (KJMA) statistical model of crystallization despite it is applicable only to an infinite medium. In this paper a model of transformation kinetics in thin films based on a concept of the survival probability for randomly chosen point during transformation process is presented. Two model versions: volume induced transformation (VIT) when the second-phase grains nucleate over a whole film volume and surface induced transformation (SIT) when they form on an interface with two nucleation mode: instantaneous nucleation at transformation onset and continuous one during all the process are studied. At VIT-process due to the finite film thickness effects the transformation profile has a maximum in a film middle, whereas that of the grains population reaches a minimum inhere, the grains density is always higher than in a volume material, and the thinner film the slower it transforms. The transformation kinetics in a thin film obeys a generalized KJMA equation with parameters depending on a film thickness and in limiting cases of extremely thin and thick film it reduces to classical KJMA equation for 2D- and 3D-system, respectively

  8. Finite-size scaling functions for directed polymers confined between attracting walls

    Energy Technology Data Exchange (ETDEWEB)

    Owczarek, A L [Department of Mathematics and Statistics, University of Melbourne, Parkville, Victoria 3052 (Australia); Prellberg, T [School of Mathematical Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS (United Kingdom); Rechnitzer, A [Department of Mathematics, University of British Columbia, Vancouver, BC V6T 1Z2 (Canada)

    2008-01-25

    The exact solution of directed self-avoiding walks confined to a slit of finite width and interacting with the walls of the slit via an attractive potential has been recently calculated. The walks can be considered to model the polymer-induced steric stabilization and sensitized flocculation of colloidal dispersions. The large-width asymptotics led to a phase diagram different to that of a polymer attached to, and attracted to, a single wall. The question that arises is: Can one interpolate between the single wall and two wall cases? In this paper, we calculate the exact scaling functions for the partition function by considering the two variable asymptotics of the partition function for simultaneous large length and large width. Consequently, we find the scaling functions for the force induced by the polymer on the walls. We find that these scaling functions are given by elliptic {theta} functions. In some parts of the phase diagram there is more a complex crossover between the single wall and two wall cases and we elucidate how this happens.

  9. Molecular finite-size effects in stochastic models of equilibrium chemical systems.

    Science.gov (United States)

    Cianci, Claudia; Smith, Stephen; Grima, Ramon

    2016-02-28

    The reaction-diffusion master equation (RDME) is a standard modelling approach for understanding stochastic and spatial chemical kinetics. An inherent assumption is that molecules are point-like. Here, we introduce the excluded volume reaction-diffusion master equation (vRDME) which takes into account volume exclusion effects on stochastic kinetics due to a finite molecular radius. We obtain an exact closed form solution of the RDME and of the vRDME for a general chemical system in equilibrium conditions. The difference between the two solutions increases with the ratio of molecular diameter to the compartment length scale. We show that an increase in the fraction of excluded space can (i) lead to deviations from the classical inverse square root law for the noise-strength, (ii) flip the skewness of the probability distribution from right to left-skewed, (iii) shift the equilibrium of bimolecular reactions so that more product molecules are formed, and (iv) strongly modulate the Fano factors and coefficients of variation. These volume exclusion effects are found to be particularly pronounced for chemical species not involved in chemical conservation laws. Finally, we show that statistics obtained using the vRDME are in good agreement with those obtained from Brownian dynamics with excluded volume interactions.

  10. Reducing Data Size Inequality during Finite Element Model Separation into Superelements

    Directory of Open Access Journals (Sweden)

    Yu. V. Berchun

    2015-01-01

    Full Text Available The work considers two methods of automatic separation of final element model into super-elements to decrease computing resource demand when solving the linearly - elastic problems of solid mechanics. The first method represents an algorithm to separate a final element grid into simply connected sub-regions according to the set specific number of nodes in the super-element. The second method is based on the generation of a super-element with the set specific data size of the coefficient matrix of the system of equations of the internal nodes balance, which are eliminated during super-element transformation. Both methods are based on the theory of graphs. The data size of a matrix of coefficients is assessed on the assumption that the further solution of a task will use Holetsky’s method. Before assessment of data size, a KatkhillaMackey's (Cuthill-McKee algorithm renumbers the internal nodes of a super-element both to decrease a profile width of the appropriate matrix of the system of equations of balance and to reduce the number of nonzero elements. Test examples show work results of abovementioned methods compared in terms of inequality of generated super-element separation according to the number of nodes and data size of the coefficient matrix of the system of equations of the internal nodes balance. It is shown that the offered approach provides smaller inequality of data size of super-element matrixes, with slightly increasing inequality by the number of tops.

  11. Effect of dislocation pile-up on size-dependent yield strength in finite single-crystal micro-samples

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Bo; Shibutani, Yoji, E-mail: sibutani@mech.eng.osaka-u.ac.jp [Department of Mechanical Engineering, Osaka University, Suita 565-0871 (Japan); Zhang, Xu [State Key Laboratory for Strength and Vibration of Mechanical Structures, School of Aerospace, Xi' an Jiaotong University, Xi' an 710049 (China); School of Mechanics and Engineering Science, Zhengzhou University, Zhengzhou 450001 (China); Shang, Fulin [State Key Laboratory for Strength and Vibration of Mechanical Structures, School of Aerospace, Xi' an Jiaotong University, Xi' an 710049 (China)

    2015-07-07

    Recent research has explained that the steeply increasing yield strength in metals depends on decreasing sample size. In this work, we derive a statistical physical model of the yield strength of finite single-crystal micro-pillars that depends on single-ended dislocation pile-up inside the micro-pillars. We show that this size effect can be explained almost completely by considering the stochastic lengths of the dislocation source and the dislocation pile-up length in the single-crystal micro-pillars. The Hall–Petch-type relation holds even in a microscale single-crystal, which is characterized by its dislocation source lengths. Our quantitative conclusions suggest that the number of dislocation sources and pile-ups are significant factors for the size effect. They also indicate that starvation of dislocation sources is another reason for the size effect. Moreover, we investigated the explicit relationship between the stacking fault energy and the dislocation “pile-up” effect inside the sample: materials with low stacking fault energy exhibit an obvious dislocation pile-up effect. Our proposed physical model predicts a sample strength that agrees well with experimental data, and our model can give a more precise prediction than the current single arm source model, especially for materials with low stacking fault energy.

  12. A review of finite size effects in quasi-zero dimensional superconductors.

    Science.gov (United States)

    Bose, Sangita; Ayyub, Pushan

    2014-11-01

    Quantum confinement and surface effects (SEs) dramatically modify most solid state phenomena as one approaches the nanometer scale, and superconductivity is no exception. Though we may expect significant modifications from bulk superconducting properties when the system dimensions become smaller than the characteristic length scales for bulk superconductors-such as the coherence length or the penetration depth-it is now established that there is a third length scale which ultimately determines the critical size at which Cooper pairing is destroyed. In quasi-zero-dimensional (0D) superconductors (e.g. nanocrystalline materials, isolated or embedded nanoparticles), one may define a critical particle diameter below which the mean energy level spacing arising from quantum confinement becomes equal to the bulk superconducting energy gap. The so-called Anderson criterion provides a remarkably accurate estimate of the limiting size for the destabilization of superconductivity in nanosystems. This review of size effects in quasi-0D superconductors is organized as follows. A general summary of size effects in nanostructured superconductors (section 1) is followed by a brief overview of their synthesis (section 2) and characterization using a variety of techniques (section 3). Section 4 reviews the size-evolution of important superconducting parameters-the transition temperature, critical fields and critical current-as the Anderson limit is approached from above. We then discuss the effect of thermodynamic fluctuations (section 5), which become significant in confined systems. Improvements in fabrication methods and the increasing feasibility of addressing individual nanoparticles using scanning probe techniques have lately opened up new directions in the study of nanoscale superconductivity. Section 6 reviews both experimental and theoretical aspects of the recently discovered phenomena of 'parity effect' and 'shell effect' that lead to a strong, non-monotonic size

  13. A review of finite size effects in quasi-zero dimensional superconductors

    International Nuclear Information System (INIS)

    Bose, Sangita; Ayyub, Pushan

    2014-01-01

    Quantum confinement and surface effects (SEs) dramatically modify most solid state phenomena as one approaches the nanometer scale, and superconductivity is no exception. Though we may expect significant modifications from bulk superconducting properties when the system dimensions become smaller than the characteristic length scales for bulk superconductors—such as the coherence length or the penetration depth—it is now established that there is a third length scale which ultimately determines the critical size at which Cooper pairing is destroyed. In quasi-zero-dimensional (0D) superconductors (e.g. nanocrystalline materials, isolated or embedded nanoparticles), one may define a critical particle diameter below which the mean energy level spacing arising from quantum confinement becomes equal to the bulk superconducting energy gap. The so-called Anderson criterion provides a remarkably accurate estimate of the limiting size for the destabilization of superconductivity in nanosystems. This review of size effects in quasi-0D superconductors is organized as follows. A general summary of size effects in nanostructured superconductors (section 1) is followed by a brief overview of their synthesis (section 2) and characterization using a variety of techniques (section 3). Section 4 reviews the size-evolution of important superconducting parameters—the transition temperature, critical fields and critical current—as the Anderson limit is approached from above. We then discuss the effect of thermodynamic fluctuations (section 5), which become significant in confined systems. Improvements in fabrication methods and the increasing feasibility of addressing individual nanoparticles using scanning probe techniques have lately opened up new directions in the study of nanoscale superconductivity. Section 6 reviews both experimental and theoretical aspects of the recently discovered phenomena of ‘parity effect’ and ‘shell effect’ that lead to a strong, non

  14. Traffic forecasts ignoring induced demand

    DEFF Research Database (Denmark)

    Næss, Petter; Nicolaisen, Morten Skou; Strand, Arvid

    2012-01-01

    the model calculations included only a part of the induced traffic, the difference in cost-benefit results compared to the model excluding all induced traffic was substantial. The results show lower travel time savings, more adverse environmental impacts and a considerably lower benefitcost ratio when...... induced traffic is partly accounted for than when it is ignored. By exaggerating the economic benefits of road capacity increase and underestimating its negative effects, omission of induced traffic can result in over-allocation of public money on road construction and correspondingly less focus on other...... performance of a proposed road project in Copenhagen with and without short-term induced traffic included in the transport model. The available transport model was not able to include long-term induced traffic resulting from changes in land use and in the level of service of public transport. Even though...

  15. Nonlinear dynamics of a vapor bubble expanding in a superheated region of finite size

    Energy Technology Data Exchange (ETDEWEB)

    Annenkova, E. A., E-mail: a-a-annenkova@yandex.ru [Physics Faculty, Moscow State University, Leninskie Gory, 119991 Moscow (Russian Federation); Kreider, W. [Center for Industrial and Medical Ultrasound, Applied Physics Laboratory, University of Washington, 1013 NE 40th St., Seattle, WA 98105 (United States); Sapozhnikov, O. A. [Physics Faculty, Moscow State University, Leninskie Gory, 119991 Moscow (Russian Federation); Center for Industrial and Medical Ultrasound, Applied Physics Laboratory, University of Washington, 1013 NE 40th St., Seattle, WA 98105 (United States)

    2015-10-28

    Growth of a vapor bubble in a superheated liquid is studied theoretically. Contrary to the typical situation of boiling, when bubbles grow in a uniformly heated liquid, here the superheated region is considered in the form of a millimeter-sized spherical hot spot. An initial micron-sized bubble is positioned at the hot spot center and a theoretical model is developed that is capable of studying bubble growth caused by vapor pressure inside the bubble and corresponding hydrodynamic and thermal processes in the surrounding liquid. Such a situation is relevant to the dynamics of vapor cavities that are created in soft biological tissue in the focal region of a high-intensity focused ultrasound beam with a shocked pressure waveform. Such beams are used in the recently proposed treatment called boiling histotripsy. Knowing the typical behavior of vapor cavities during boiling histotripsy could help to optimize the therapeutic procedure.

  16. Synchronization in scale-free networks: The role of finite-size effects

    Science.gov (United States)

    Torres, D.; Di Muro, M. A.; La Rocca, C. E.; Braunstein, L. A.

    2015-06-01

    Synchronization problems in complex networks are very often studied by researchers due to their many applications to various fields such as neurobiology, e-commerce and completion of tasks. In particular, scale-free networks with degree distribution P(k)∼ k-λ , are widely used in research since they are ubiquitous in Nature and other real systems. In this paper we focus on the surface relaxation growth model in scale-free networks with 2.5< λ <3 , and study the scaling behavior of the fluctuations, in the steady state, with the system size N. We find a novel behavior of the fluctuations characterized by a crossover between two regimes at a value of N=N* that depends on λ: a logarithmic regime, found in previous research, and a constant regime. We propose a function that describes this crossover, which is in very good agreement with the simulations. We also find that, for a system size above N* , the fluctuations decrease with λ, which means that the synchronization of the system improves as λ increases. We explain this crossover analyzing the role of the network's heterogeneity produced by the system size N and the exponent of the degree distribution.

  17. 3D finite element modeling of epiretinal stimulation: Impact of prosthetic electrode size and distance from the retina.

    Science.gov (United States)

    Sui, Xiaohong; Huang, Yu; Feng, Fuchen; Huang, Chenhui; Chan, Leanne Lai Hang; Wang, Guoxing

    2015-05-01

    A novel 3-dimensional (3D) finite element model was established to systematically investigate the impact of the diameter (Φ) of disc electrodes and the electrode-to-retina distance on the effectiveness of stimulation. The 3D finite element model was established based on a disc platinum stimulating electrode and a 6-layered retinal structure. The ground electrode was placed in the extraocular space in direct attachment with sclera and treated as a distant return electrode. An established criterion of electric-field strength of 1000 Vm-1 was adopted as the activation threshold for RGCs. The threshold current (TC) increased linearly with increasing Φ and electrode-to-retina distance and remained almost unchanged with further increases in diameter. However, the threshold charge density (TCD) increased dramatically with decreasing electrode diameter. TCD exceeded the electrode safety limit for an electrode diameter of 50 µm at an electrode-to-retina distance of 50 to 200 μm. The electric field distributions illustrated that smaller electrode diameters and shorter electrode-to-retina distances were preferred due to more localized excitation of RGC area under stimulation of different threshold currents in terms of varied electrode size and electrode-to-retina distances. Under the condition of same-amplitude current stimulation, a large electrode exhibited an improved potential spatial selectivity at large electrode-to-retina distances. Modeling results were consistent with those reported in animal electrophysiological experiments and clinical trials, validating the 3D finite element model of epiretinal stimulation. The computational model proved to be useful in optimizing the design of an epiretinal stimulating electrode for prosthesis.

  18. Probabilistic finite-size transport models for fusion: Anomalous transport and scaling laws

    International Nuclear Information System (INIS)

    Milligen, B.Ph. van; Sanchez, R.; Carreras, B.A.

    2004-01-01

    Transport in fusion plasmas in the low confinement mode is characterized by several remarkable properties: the anomalous scaling of transport with system size, stiff (or 'canonical') profiles, power degradation, and rapid transport phenomena. The present article explores the possibilities of constructing a unified transport model, based on the continuous-time random walk, in which all these phenomena are handled adequately. The resulting formalism appears to be sufficiently general to provide a sound starting point for the development of a full-blown plasma transport code, capable of incorporating the relevant microscopic transport mechanisms, and allowing predictions of confinement properties

  19. Finite-size effects on the vortex-glass transition in thin YBa2Cu3O7-δ films

    International Nuclear Information System (INIS)

    Woeltgens, P.J.M.; Dekker, C.; Koch, R.H.; Hussey, B.W.; Gupta, A.

    1995-01-01

    Nonlinear current-voltage characteristics have been measured at high magnetic fields in YBa 2 Cu 3 O 7-δ films of a thickness t ranging from 3000 down to 16 A. Critical-scaling analyses of the data for the thinner films (t≤400 A) reveal deviations from the vortex-glass critical scaling appropriate for three-dimensional (3D) systems. This is argued to be a finite-size effect. At large current densities J, the vortices are probed at length scales smaller than the film thickness, i.e., 3D vortex-glass behavior is observed. At low J by contrast, the vortex excitations involve typical length scales exceeding the film thickness, resulting in 2D behavior. Further evidence for this picture is found directly from the 3D vortex-glass correlation length, which, upon approach of the glass transition temperature, appears to level off at the film thickness. The results indicate that a vortex-glass phase transition does occur at finite temperature in 3D systems, but not in 2D systems. In the latter an onset of 2D correlations occurs towards zero temperature. This is demonstrated in our thinnest film (16 A), which, in a magnetic field, displays a 2D vortex-glass correlation length which critically diverges at zero temperature

  20. The Power of Ignorance | Code | Philosophical Papers

    African Journals Online (AJOL)

    Taking my point of entry from George Eliot's reference to 'the power of Ignorance', I analyse some manifestations of that power as she portrays it in the life of a young woman of affluence, in her novel Daniel Deronda. Comparing and contrasting this kind of ignorance with James Mill's avowed ignorance of local tradition and ...

  1. Transient queue-size distribution in a finite-capacity queueing system with server breakdowns and Bernoulli feedback

    Science.gov (United States)

    Kempa, Wojciech M.

    2017-12-01

    A finite-capacity queueing system with server breakdowns is investigated, in which successive exponentially distributed failure-free times are followed by repair periods. After the processing a customer may either rejoin the queue (feedback) with probability q, or definitely leave the system with probability 1 - q. The system of integral equations for transient queue-size distribution, conditioned by the initial level of buffer saturation, is build. The solution of the corresponding system written for Laplace transforms is found using the linear algebraic approach. The considered queueing system can be successfully used in modelling production lines with machine failures, in which the parameter q may be considered as a typical fraction of items demanding corrections. Morever, this queueing model can be applied in the analysis of real TCP/IP performance, where q stands for the fraction of packets requiring retransmission.

  2. Static and high-frequency magnetic properties of stripe domain structure in a plate of finite sizes

    International Nuclear Information System (INIS)

    Mal'ginova, S.D.; Doroshenko, R.A.; Shul'ga, N.V.

    2006-01-01

    A model that enables to carry out self-consistent calculations of the main parameters of stripe domain structure (DS) and at the same time those of properties of domain walls (DW) of a multiple-axis finite (in all directions) ferromagnet depending on the sizes of a sample, material parameters and intensity of a magnetic field is offered. The calculations of the properties of DS (direction of magnetization in domains, widths, ferromagnetic resonance, etc.) are carried out on a computer for plates (1 1 0), rectangular shapes of a cubic ferromagnet with axes of light magnetization along trigonal directions in a magnetic field [-1 1 0]. It is shown, that in plates of different shapes there can be a structure with Neel DW alongside with DS with Bloch DW. Their features are noticeably exhibited, in particular, in different dependence of the number of domains, and also frequencies of a ferromagnetic resonance from a magnetic field

  3. Finite-size fluctuations and photon statistics near the polariton condensation transition in a single-mode microcavity

    International Nuclear Information System (INIS)

    Eastham, P. R.; Littlewood, P. B.

    2006-01-01

    We consider polariton condensation in a generalized Dicke model, describing a single-mode cavity containing quantum dots, and extend our previous mean-field theory to allow for finite-size fluctuations. Within the fluctuation-dominated regime the correlation functions differ from their (trivial) mean-field values. We argue that the low-energy physics of the model, which determines the photon statistics in this fluctuation-dominated crossover regime, is that of the (quantum) anharmonic oscillator. The photon statistics at the crossover are different in the high-temperature and low-temperature limits. When the temperature is high enough for quantum effects to be neglected we recover behavior similar to that of a conventional laser. At low enough temperatures, however, we find qualitatively different behavior due to quantum effects

  4. Finite element analysis of the three different posterior malleolus fixation strategies in relation to different fracture sizes.

    Science.gov (United States)

    Anwar, Adeel; Lv, Decheng; Zhao, Zhi; Zhang, Zhen; Lu, Ming; Nazir, Muhammad Umar; Qasim, Wasim

    2017-04-01

    Appropriate fixation method for the posterior malleolar fractures (PMF) according to the fracture size is still not clear. Aim of this study was to evaluate the outcomes of the different fixation methods used for fixation of PMF by finite element analysis (FEA) and to compare the effect of fixation constructs on the size of the fracture computationally. Three dimensional model of the tibia was reconstructed from computed tomography (CT) images. PMF of 30%, 40% and 50% fragment sizes were simulated through computational processing. Two antero-posterior (AP) lag screws, two postero-anterior (PA) lag screws and posterior buttress plate were analysed for three different fracture volumes. The simulated loads of 350N and 700N were applied to the proximal tibial end. Models were fixed distally in all degrees of freedom. In single limb standing condition, the posterior plate group produced the lowest relative displacement (RD) among all the groups (0.01, 0.03 and 0.06mm). Further nodal analysis of the highest RD fracture group showed a higher mean displacement of 4.77mm and 4.23mm in AP and PA lag screws model (p=0.000). The amounts of stress subjected to these implants, 134.36MPa and 140.75MPa were also significantly lower (p=0.000). There was a negative correlation (p=0.021) between implant stress and the displacement which signifies a less stable fixation using AP and PA lag screws. Progressively increasing fracture size demands more stable fixation construct because RD increases significantly. Posterior buttress plate produces superior stability and lowest RD in PMF models irrespective of the fragment size. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Nonstandard scaling law of fluctuations in finite-size systems of globally coupled oscillators.

    Science.gov (United States)

    Nishikawa, Isao; Tanaka, Gouhei; Aihara, Kazuyuki

    2013-08-01

    Universal scaling laws form one of the central issues in physics. A nonstandard scaling law or a breakdown of a standard scaling law, on the other hand, can often lead to the finding of a new universality class in physical systems. Recently, we found that a statistical quantity related to fluctuations follows a nonstandard scaling law with respect to the system size in a synchronized state of globally coupled nonidentical phase oscillators [I. Nishikawa et al., Chaos 22, 013133 (2012)]. However, it is still unclear how widely this nonstandard scaling law is observed. In the present paper, we discuss the conditions required for the unusual scaling law in globally coupled oscillator systems and validate the conditions by numerical simulations of several different models.

  6. Fracture Mechanics Assessment for Different Notch Sizes Using Finite Element Analysis Based on Ductile Failure Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Keun Hyung; Jeon, Jun Young; Han, Jae Jun; Nam, Hyun Suk; Lee, Dae Young; Kim, Yun Jae [Korea Univ., Seoul (Korea, Republic of)

    2016-08-15

    In this study, notch defects are evaluated using fracture mechanics. To understand the effects of notch defects, FE analysis is conducted to predict the limit load and J-integral for middle-cracked and single-edge cracked plates with various sizes of notch under tension and bending. As the radius of the notch increases, the energy release rate also increases, although the limit load remains constant. The values of fracture toughness(J{sub IC}) of SM490A are determined for various notch radii through FE simulation instead of conducting an experiment. As the radius of the notch increases, the energy release rate also increases, together with a more significant increase in fracture toughness. To conclude, as the notch radius increases, the resistance to crack propagation also increases.

  7. GIFFT: A Fast Solver for Modeling Sources in a Metamaterial Environment of Finite Size

    International Nuclear Information System (INIS)

    Capolino, F; Basilio, L; Fasenfest, B J; Wilton, D R

    2006-01-01

    Due to the recent explosion of interest in studying the electromagnetic behavior of large (truncated) periodic structures such as phased arrays, frequency-selective surfaces, and metamaterials, there has been a renewed interest in efficiently modeling such structures. Since straightforward numerical analyses of large, finite structures (i.e., explicitly meshing and computing interactions between all mesh elements of the entire structure) involve significant memory storage and computation times, much effort is currently being expended on developing techniques that minimize the high demand on computer resources. One such technique that belongs to the class of fast solvers for large periodic structures is the GIFFT algorithm (Green's function interpolation and FFT), which is first discussed in [1]. This method is a modification of the adaptive integral method (AIM) [2], a technique based on the projection of subdomain basis functions onto a rectangular grid. Like the methods presented in [3]-[4], the GIFFT algorithm is an extension of the AIM method in that it uses basis-function projections onto a rectangular grid through Lagrange interpolating polynomials. The use of a rectangular grid results in a matrix-vector product that is convolutional in form and can thus be evaluated using FFTs. Although our method differs from [3]-[6] in various respects, the primary differences between the AIM approach [2] and the GIFFT method [1] is the latter's use of interpolation to represent the Green's function (GF) and its specialization to periodic structures by taking into account the reusability properties of matrices that arise from interactions between identical cell elements. The present work extends the GIFFT algorithm to allow for a complete numerical analysis of a periodic structure excited by dipole source, as shown in Fig 1. Although GIFFT [1] was originally developed to handle strictly periodic structures, the technique has now been extended to efficiently handle a small

  8. Random sequential adsorption with two components: asymptotic analysis and finite size effects

    International Nuclear Information System (INIS)

    Reeve, Louise; Wattis, Jonathan A D

    2015-01-01

    We consider the model of random sequential adsorption (RSA) in which two lengths of rod-like polymer compete for binding on a long straight rigid one-dimensional substrate. We take all lengths to be discrete, assume that binding is irreversible, and short or long polymers are chosen at random with some probability. We consider both the cases where the polymers have similar lengths and when the lengths are vastly different. We use a combination of numerical simulations, computation and asymptotic analysis to study the adsorption process, specifically, analysing how competition between the two polymer lengths affects the final coverage, and how the coverage depends on the relative sizes of the two species and their relative binding rates. We find that the final coverage is always higher than in the one-species RSA, and that the highest coverage is achieved when the rate of binding of the longer polymer is higher. We find that for many binding rates and relative lengths of binding species, the coverage due to the shorter species decreases with increasing substrate length, although there is a small region of parameter space in which all coverages increase with substrate length. (paper)

  9. Does the Finite Size of Electrons Affect Quantum Noise in Electronic Devices?

    International Nuclear Information System (INIS)

    Colomés, E; Marian, D; Oriols, X

    2015-01-01

    Quantum transport is commonly studied with the use of quasi-particle infinite- extended states. This leads to a powerful formalism, the scattering-states theory, able to capture in compact formulas quantities of interest, such as average current, noise, etc.. However, when investigating the spatial size-dependence of quasi-particle wave packets in quantum noise with exchange and tunneling, unexpected new terms appear in the quantum noise expression. For this purpose, the two particle transmission and reflection probabilities for two initial one-particle wave packets (with opposite central momentums) spatially localized at each side of a potential barrier are studied. After the interaction, each wave packet splits into a transmitted and a reflected component. It can be shown that the probability of detecting two (identically injected) electrons at the same side of the barrier is different from zero in very common (single or double barrier) scenarios. This originates an increase of quantum noise which cannot be obtained through the scattering states formalism. (paper)

  10. Adaptive beamlet-based finite-size pencil beam dose calculation for independent verification of IMRT and VMAT

    International Nuclear Information System (INIS)

    Park, Justin C.; Li, Jonathan G.; Arhjoul, Lahcen; Yan, Guanghua; Lu, Bo; Fan, Qiyong; Liu, Chihray

    2015-01-01

    Purpose: The use of sophisticated dose calculation procedure in modern radiation therapy treatment planning is inevitable in order to account for complex treatment fields created by multileaf collimators (MLCs). As a consequence, independent volumetric dose verification is time consuming, which affects the efficiency of clinical workflow. In this study, the authors present an efficient adaptive beamlet-based finite-size pencil beam (AB-FSPB) dose calculation algorithm that minimizes the computational procedure while preserving the accuracy. Methods: The computational time of finite-size pencil beam (FSPB) algorithm is proportional to the number of infinitesimal and identical beamlets that constitute an arbitrary field shape. In AB-FSPB, dose distribution from each beamlet is mathematically modeled such that the sizes of beamlets to represent an arbitrary field shape no longer need to be infinitesimal nor identical. As a result, it is possible to represent an arbitrary field shape with combinations of different sized and minimal number of beamlets. In addition, the authors included the model parameters to consider MLC for its rounded edge and transmission. Results: Root mean square error (RMSE) between treatment planning system and conventional FSPB on a 10 × 10 cm 2 square field using 10 × 10, 2.5 × 2.5, and 0.5 × 0.5 cm 2 beamlet sizes were 4.90%, 3.19%, and 2.87%, respectively, compared with RMSE of 1.10%, 1.11%, and 1.14% for AB-FSPB. This finding holds true for a larger square field size of 25 × 25 cm 2 , where RMSE for 25 × 25, 2.5 × 2.5, and 0.5 × 0.5 cm 2 beamlet sizes were 5.41%, 4.76%, and 3.54% in FSPB, respectively, compared with RMSE of 0.86%, 0.83%, and 0.88% for AB-FSPB. It was found that AB-FSPB could successfully account for the MLC transmissions without major discrepancy. The algorithm was also graphical processing unit (GPU) compatible to maximize its computational speed. For an intensity modulated radiation therapy (∼12 segments) and a

  11. Influence of surface and finite size effects on the structural and magnetic properties of nanocrystalline lanthanum strontium perovskite manganites

    Energy Technology Data Exchange (ETDEWEB)

    Žvátora, Pavel [Department of Analytical Chemistry, Institute of Chemical Technology Prague, Technická 5, 166 28 Prague (Czech Republic); Veverka, Miroslav; Veverka, Pavel; Knížek, Karel; Závěta, Karel; Pollert, Emil [Department of Magnetism and Superconductors, Institute of Physics AS CR, Cukrovarnická 10/112, 162 00 Prague (Czech Republic); Král, Vladimír [Department of Analytical Chemistry, Institute of Chemical Technology Prague, Technická 5, 166 28 Prague (Czech Republic); Zentiva Development (Part of Sanofi Group), U Kabelovny 130, 102 37 Prague (Czech Republic); Goglio, Graziella; Duguet, Etienne [CNRS, University of Bordeaux, ICMCB, UPR 9048, 33600 Pessac (France); Kaman, Ondřej, E-mail: kamano@seznam.cz [Department of Magnetism and Superconductors, Institute of Physics AS CR, Cukrovarnická 10/112, 162 00 Prague (Czech Republic); Department of Cell Biology, Faculty of Science, Charles University, Viničná 7, 128 40 Prague (Czech Republic)

    2013-08-15

    Syntheses of nanocrystalline perovskite phases of the general formula La{sub 1−x}Sr{sub x}MnO{sub 3+δ} were carried out employing sol–gel technique followed by thermal treatment at 700–900 °C under oxygen flow. The prepared samples exhibit a rhombohedral structure with space group R3{sup ¯}c in the whole investigated range of composition 0.20≤x≤0.45. The studies were aimed at the chemical composition including oxygen stoichiometry and extrinsic properties, i.e. size of the particles, both influencing the resulting structural and magnetic properties. The oxygen stoichiometry was determined by chemical analysis revealing oxygen excess in most of the studied phases. The excess was particularly high for the samples with the smallest crystallites (12–28 nm) while comparative bulk materials showed moderate non-stoichiometry. These differences are tentatively attributed to the surface effects in view of the volume fraction occupied by the upper layer whose atomic composition does not comply with the ideal bulk stoichiometry. - Graphical abstract: Evolution of the particle size with annealing temperature in the nanocrystalline La{sub 0.70}Sr{sub 0.30}MnO{sub 3+δ} phase. Display Omitted - Highlights: • The magnetic behaviour of nanocrystalline La{sub 1−x}Sr{sub x}MnO{sub 3+δ} phases was analyzed on the basis of their crystal structure, chemical composition and size of the particles. • Their Curie temperature and magnetization are markedly affected by finite size and surface effects. • The oxygen excess observed in the La{sub 1−x}Sr{sub x}MnO{sub 3+δ} nanoparticles might be generated by the surface layer with deviated oxygen stoichiometry.

  12. Migration of finite sized particles in a laminar square channel flow from low to high Reynolds numbers

    Energy Technology Data Exchange (ETDEWEB)

    Abbas, M., E-mail: micheline.abbas@ensiacet.fr [Laboratoire de Génie Chimique, Université de Toulouse INPT-UPS, 31030, Toulouse (France); CNRS, Fédération de recherche FERMaT, CNRS, 31400, Toulouse (France); Magaud, P. [CNRS, Fédération de recherche FERMaT, CNRS, 31400, Toulouse (France); Institut Clément Ader, Université de Toulouse UPS-INSA-ISAE-Mines Albi, 31400, Toulouse (France); Gao, Y. [Institut Clément Ader, Université de Toulouse UPS-INSA-ISAE-Mines Albi, 31400, Toulouse (France); Geoffroy, S. [CNRS, Fédération de recherche FERMaT, CNRS, 31400, Toulouse (France); Laboratoire Matériaux et Durabilité des Constructions, Université de Toulouse (France); UPS, INSA, 31077, Toulouse (France)

    2014-12-15

    The migration of neutrally buoyant finite sized particles in a Newtonian square channel flow is investigated in the limit of very low solid volumetric concentration, within a wide range of channel Reynolds numbers Re = [0.07-120]. In situ microscope measurements of particle distributions, taken far from the channel inlet (at a distance several thousand times the channel height), revealed that particles are preferentially located near the channel walls at Re > 10 and near the channel center at Re < 1. Whereas the cross-streamline particle motion is governed by inertia-induced lift forces at high inertia, it seems to be controlled by shear-induced particle interactions at low (but finite) Reynolds numbers, despite the low solid volume fraction (<1%). The transition between both regimes is observed in the range Re = [1-10]. In order to exclude the effect of multi-body interactions, the trajectories of single freely moving particles are calculated thanks to numerical simulations based on the force coupling method. With the deployed numerical tool, the complete particle trajectories are accessible within a reasonable computational time only in the inertial regime (Re > 10). In this regime, we show that (i) the particle undergoes cross-streamline migration followed by a cross-lateral migration (parallel to the wall) in agreement with previous observations, and (ii) the stable equilibrium positions are located at the midline of the channel faces while the diagonal equilibrium positions are unstable. At low flow inertia, the first instants of the numerical simulations (carried at Re = O(1)) reveal that the cross-streamline migration of a single particle is oriented towards the channel wall, suggesting that the particle preferential positions around the channel center, observed in the experiments, are rather due to multi-body interactions.

  13. Migration of finite sized particles in a laminar square channel flow from low to high Reynolds numbers

    International Nuclear Information System (INIS)

    Abbas, M.; Magaud, P.; Gao, Y.; Geoffroy, S.

    2014-01-01

    The migration of neutrally buoyant finite sized particles in a Newtonian square channel flow is investigated in the limit of very low solid volumetric concentration, within a wide range of channel Reynolds numbers Re = [0.07-120]. In situ microscope measurements of particle distributions, taken far from the channel inlet (at a distance several thousand times the channel height), revealed that particles are preferentially located near the channel walls at Re > 10 and near the channel center at Re < 1. Whereas the cross-streamline particle motion is governed by inertia-induced lift forces at high inertia, it seems to be controlled by shear-induced particle interactions at low (but finite) Reynolds numbers, despite the low solid volume fraction (<1%). The transition between both regimes is observed in the range Re = [1-10]. In order to exclude the effect of multi-body interactions, the trajectories of single freely moving particles are calculated thanks to numerical simulations based on the force coupling method. With the deployed numerical tool, the complete particle trajectories are accessible within a reasonable computational time only in the inertial regime (Re > 10). In this regime, we show that (i) the particle undergoes cross-streamline migration followed by a cross-lateral migration (parallel to the wall) in agreement with previous observations, and (ii) the stable equilibrium positions are located at the midline of the channel faces while the diagonal equilibrium positions are unstable. At low flow inertia, the first instants of the numerical simulations (carried at Re = O(1)) reveal that the cross-streamline migration of a single particle is oriented towards the channel wall, suggesting that the particle preferential positions around the channel center, observed in the experiments, are rather due to multi-body interactions

  14. Finite size and geometrical non-linear effects during crack pinning by heterogeneities: An analytical and experimental study

    Science.gov (United States)

    Vasoya, Manish; Unni, Aparna Beena; Leblond, Jean-Baptiste; Lazarus, Veronique; Ponson, Laurent

    2016-04-01

    Crack pinning by heterogeneities is a central toughening mechanism in the failure of brittle materials. So far, most analytical explorations of the crack front deformation arising from spatial variations of fracture properties have been restricted to weak toughness contrasts using first order approximation and to defects of small dimensions with respect to the sample size. In this work, we investigate the non-linear effects arising from larger toughness contrasts by extending the approximation to the second order, while taking into account the finite sample thickness. Our calculations predict the evolution of a planar crack lying on the mid-plane of a plate as a function of material parameters and loading conditions, especially in the case of a single infinitely elongated obstacle. Peeling experiments are presented which validate the approach and evidence that the second order term broadens its range of validity in terms of toughness contrast values. The work highlights the non-linear response of the crack front to strong defects and the central role played by the thickness of the specimen on the pinning process.

  15. Finite element modelling to assess the effect of surface mounted piezoelectric patch size on vibration response of a hybrid beam

    Science.gov (United States)

    Rahman, N.; Alam, M. N.

    2018-02-01

    Vibration response analysis of a hybrid beam with surface mounted patch piezoelectric layer is presented in this work. A one dimensional finite element (1D-FE) model based on efficient layerwise (zigzag) theory is used for the analysis. The beam element has eight mechanical and a variable number of electrical degrees of freedom. The beams are also modelled in 2D-FE (ABAQUS) using a plane stress piezoelectric quadrilateral element for piezo layers and a plane stress quadrilateral element for the elastic layers of hybrid beams. Results are presented to assess the effect of size of piezoelectric patch layer on the free and forced vibration responses of thin and moderately thick beams under clamped-free and clamped-clamped configurations. The beams are subjected to unit step loading and harmonic loading to obtain the forced vibration responses. The vibration control using in phase actuation potential on piezoelectric patches is also studied. The 1D-FE results are compared with the 2D-FE results.

  16. A GPU-based finite-size pencil beam algorithm with 3D-density correction for radiotherapy dose calculation

    International Nuclear Information System (INIS)

    Gu Xuejun; Jia Xun; Jiang, Steve B; Jelen, Urszula; Li Jinsheng

    2011-01-01

    Targeting at the development of an accurate and efficient dose calculation engine for online adaptive radiotherapy, we have implemented a finite-size pencil beam (FSPB) algorithm with a 3D-density correction method on graphics processing unit (GPU). This new GPU-based dose engine is built on our previously published ultrafast FSPB computational framework (Gu et al 2009 Phys. Med. Biol. 54 6287-97). Dosimetric evaluations against Monte Carlo dose calculations are conducted on ten IMRT treatment plans (five head-and-neck cases and five lung cases). For all cases, there is improvement with the 3D-density correction over the conventional FSPB algorithm and for most cases the improvement is significant. Regarding the efficiency, because of the appropriate arrangement of memory access and the usage of GPU intrinsic functions, the dose calculation for an IMRT plan can be accomplished well within 1 s (except for one case) with this new GPU-based FSPB algorithm. Compared to the previous GPU-based FSPB algorithm without 3D-density correction, this new algorithm, though slightly sacrificing the computational efficiency (∼5-15% lower), has significantly improved the dose calculation accuracy, making it more suitable for online IMRT replanning.

  17. Impact of high-frequency pumping on anomalous finite-size effects in three-dimensional topological insulators

    Science.gov (United States)

    Pervishko, Anastasiia A.; Yudin, Dmitry; Shelykh, Ivan A.

    2018-02-01

    Lowering of the thickness of a thin-film three-dimensional topological insulator down to a few nanometers results in the gap opening in the spectrum of topologically protected two-dimensional surface states. This phenomenon, which is referred to as the anomalous finite-size effect, originates from hybridization between the states propagating along the opposite boundaries. In this work, we consider a bismuth-based topological insulator and show how the coupling to an intense high-frequency linearly polarized pumping can further be used to manipulate the value of a gap. We address this effect within recently proposed Brillouin-Wigner perturbation theory that allows us to map a time-dependent problem into a stationary one. Our analysis reveals that both the gap and the components of the group velocity of the surface states can be tuned in a controllable fashion by adjusting the intensity of the driving field within an experimentally accessible range and demonstrate the effect of light-induced band inversion in the spectrum of the surface states for high enough values of the pump.

  18. Confidence intervals for population allele frequencies: the general case of sampling from a finite diploid population of any size.

    Science.gov (United States)

    Fung, Tak; Keenan, Kevin

    2014-01-01

    The estimation of population allele frequencies using sample data forms a central component of studies in population genetics. These estimates can be used to test hypotheses on the evolutionary processes governing changes in genetic variation among populations. However, existing studies frequently do not account for sampling uncertainty in these estimates, thus compromising their utility. Incorporation of this uncertainty has been hindered by the lack of a method for constructing confidence intervals containing the population allele frequencies, for the general case of sampling from a finite diploid population of any size. In this study, we address this important knowledge gap by presenting a rigorous mathematical method to construct such confidence intervals. For a range of scenarios, the method is used to demonstrate that for a particular allele, in order to obtain accurate estimates within 0.05 of the population allele frequency with high probability (> or = 95%), a sample size of > 30 is often required. This analysis is augmented by an application of the method to empirical sample allele frequency data for two populations of the checkerspot butterfly (Melitaea cinxia L.), occupying meadows in Finland. For each population, the method is used to derive > or = 98.3% confidence intervals for the population frequencies of three alleles. These intervals are then used to construct two joint > or = 95% confidence regions, one for the set of three frequencies for each population. These regions are then used to derive a > or = 95%% confidence interval for Jost's D, a measure of genetic differentiation between the two populations. Overall, the results demonstrate the practical utility of the method with respect to informing sampling design and accounting for sampling uncertainty in studies of population genetics, important for scientific hypothesis-testing and also for risk-based natural resource management.

  19. Confidence intervals for population allele frequencies: the general case of sampling from a finite diploid population of any size.

    Directory of Open Access Journals (Sweden)

    Tak Fung

    Full Text Available The estimation of population allele frequencies using sample data forms a central component of studies in population genetics. These estimates can be used to test hypotheses on the evolutionary processes governing changes in genetic variation among populations. However, existing studies frequently do not account for sampling uncertainty in these estimates, thus compromising their utility. Incorporation of this uncertainty has been hindered by the lack of a method for constructing confidence intervals containing the population allele frequencies, for the general case of sampling from a finite diploid population of any size. In this study, we address this important knowledge gap by presenting a rigorous mathematical method to construct such confidence intervals. For a range of scenarios, the method is used to demonstrate that for a particular allele, in order to obtain accurate estimates within 0.05 of the population allele frequency with high probability (> or = 95%, a sample size of > 30 is often required. This analysis is augmented by an application of the method to empirical sample allele frequency data for two populations of the checkerspot butterfly (Melitaea cinxia L., occupying meadows in Finland. For each population, the method is used to derive > or = 98.3% confidence intervals for the population frequencies of three alleles. These intervals are then used to construct two joint > or = 95% confidence regions, one for the set of three frequencies for each population. These regions are then used to derive a > or = 95%% confidence interval for Jost's D, a measure of genetic differentiation between the two populations. Overall, the results demonstrate the practical utility of the method with respect to informing sampling design and accounting for sampling uncertainty in studies of population genetics, important for scientific hypothesis-testing and also for risk-based natural resource management.

  20. SU-F-T-428: An Optimization-Based Commissioning Tool for Finite Size Pencil Beam Dose Calculations

    Energy Technology Data Exchange (ETDEWEB)

    Li, Y; Tian, Z; Song, T; Jia, X; Gu, X; Jiang, S [UT Southwestern Medical Center, Dallas, TX (United States)

    2016-06-15

    Purpose: Finite size pencil beam (FSPB) algorithms are commonly used to pre-calculate the beamlet dose distribution for IMRT treatment planning. FSPB commissioning, which usually requires fine tuning of the FSPB kernel parameters, is crucial to the dose calculation accuracy and hence the plan quality. Yet due to the large number of beamlets, FSPB commissioning could be very tedious. This abstract reports an optimization-based FSPB commissioning tool we have developed in MatLab to facilitate the commissioning. Methods: A FSPB dose kernel generally contains two types of parameters: the profile parameters determining the dose kernel shape, and a 2D scaling factors accounting for the longitudinal and off-axis corrections. The former were fitted using the penumbra of a reference broad beam’s dose profile with Levenberg-Marquardt algorithm. Since the dose distribution of a broad beam is simply a linear superposition of the dose kernel of each beamlet calculated with the fitted profile parameters and scaled using the scaling factors, these factors could be determined by solving an optimization problem which minimizes the discrepancies between the calculated dose of broad beams and the reference dose. Results: We have commissioned a FSPB algorithm for three linac photon beams (6MV, 15MV and 6MVFFF). Dose of four field sizes (6*6cm2, 10*10cm2, 15*15cm2 and 20*20cm2) were calculated and compared with the reference dose exported from Eclipse TPS system. For depth dose curves, the differences are less than 1% of maximum dose after maximum dose depth for most cases. For lateral dose profiles, the differences are less than 2% of central dose at inner-beam regions. The differences of the output factors are within 1% for all the three beams. Conclusion: We have developed an optimization-based commissioning tool for FSPB algorithms to facilitate the commissioning, providing sufficient accuracy of beamlet dose calculation for IMRT optimization.

  1. Unexpected finite size effects in interfacial systems: Why bigger is not always better—Increase in uncertainty of surface tension with bulk phase width

    Science.gov (United States)

    Longford, Francis G. J.; Essex, Jonathan W.; Skylaris, Chris-Kriton; Frey, Jeremy G.

    2018-06-01

    We present an unexpected finite size effect affecting interfacial molecular simulations that is proportional to the width-to-surface-area ratio of the bulk phase Ll/A. This finite size effect has a significant impact on the variance of surface tension values calculated using the virial summation method. A theoretical derivation of the origin of the effect is proposed, giving a new insight into the importance of optimising system dimensions in interfacial simulations. We demonstrate the consequences of this finite size effect via a new way to estimate the surface energetic and entropic properties of simulated air-liquid interfaces. Our method is based on macroscopic thermodynamic theory and involves comparing the internal energies of systems with varying dimensions. We present the testing of these methods using simulations of the TIP4P/2005 water forcefield and a Lennard-Jones fluid model of argon. Finally, we provide suggestions of additional situations, in which this finite size effect is expected to be significant, as well as possible ways to avoid its impact.

  2. From dissecting ignorance to solving algebraic problems

    International Nuclear Information System (INIS)

    Ayyub, Bilal M.

    2004-01-01

    Engineers and scientists are increasingly required to design, test, and validate new complex systems in simulation environments and/or with limited experimental results due to international and/or budgetary restrictions. Dealing with complex systems requires assessing knowledge and information by critically evaluating them in terms relevance, completeness, non-distortion, coherence, and other key measures. Using the concepts and definitions from evolutionary knowledge and epistemology, ignorance is examined and classified in the paper. Two ignorance states for a knowledge agent are identified: (1) non-reflective (or blind) state, i.e. the person does not know of self-ignorance, a case of ignorance of ignorance; and (2) reflective state, i.e. the person knows and recognizes self-ignorance. Ignorance can be viewed to have a hierarchal classification based on its sources and nature as provided in the paper. The paper also explores limits on knowledge construction, closed and open world assumptions, and fundamentals of evidential reasoning using belief revision and diagnostics within the framework of ignorance analysis for knowledge construction. The paper also examines an algebraic problem set as identified by Sandia National Laboratories to be a basic building block for uncertainty propagation in computational mechanics. Solution algorithms are provided for the problem set for various assumptions about the state of knowledge about its parameters

  3. On the Rationality of Pluralistic Ignorance

    DEFF Research Database (Denmark)

    Bjerring, Jens Christian Krarup; Hansen, Jens Ulrik; Pedersen, Nikolaj Jang Lee Linding

    2014-01-01

    Pluralistic ignorance is a socio-psychological phenomenon that involves a systematic discrepancy between people’s private beliefs and public behavior in cer- tain social contexts. Recently, pluralistic ignorance has gained increased attention in formal and social epistemology. But to get clear...

  4. From dissecting ignorance to solving algebraic problems

    Energy Technology Data Exchange (ETDEWEB)

    Ayyub, Bilal M

    2004-09-01

    Engineers and scientists are increasingly required to design, test, and validate new complex systems in simulation environments and/or with limited experimental results due to international and/or budgetary restrictions. Dealing with complex systems requires assessing knowledge and information by critically evaluating them in terms relevance, completeness, non-distortion, coherence, and other key measures. Using the concepts and definitions from evolutionary knowledge and epistemology, ignorance is examined and classified in the paper. Two ignorance states for a knowledge agent are identified: (1) non-reflective (or blind) state, i.e. the person does not know of self-ignorance, a case of ignorance of ignorance; and (2) reflective state, i.e. the person knows and recognizes self-ignorance. Ignorance can be viewed to have a hierarchal classification based on its sources and nature as provided in the paper. The paper also explores limits on knowledge construction, closed and open world assumptions, and fundamentals of evidential reasoning using belief revision and diagnostics within the framework of ignorance analysis for knowledge construction. The paper also examines an algebraic problem set as identified by Sandia National Laboratories to be a basic building block for uncertainty propagation in computational mechanics. Solution algorithms are provided for the problem set for various assumptions about the state of knowledge about its parameters.

  5. Capillary condensation in cylindrical pores: Monte Carlo study of the interplay of surface and finite size effects.

    Science.gov (United States)

    Winkler, A; Wilms, D; Virnau, P; Binder, K

    2010-10-28

    When a fluid that undergoes a vapor to liquid transition in the bulk is confined to a long cylindrical pore, the phase transition is shifted (mostly due to surface effects at the walls of the pore) and rounded (due to finite size effects). The nature of the phase coexistence at the transition depends on the length of the pore: for very long pores, the system is axially homogeneous at low temperatures. At the chemical potential where the transition takes place, fluctuations occur between vapor- and liquidlike states of the cylinder as a whole. At somewhat higher temperatures (but still far below bulk criticality), the system at phase coexistence is in an axially inhomogeneous multidomain state, where long cylindrical liquid- and vaporlike domains alternate. Using Monte Carlo simulations for the Ising/lattice gas model and the Asakura-Oosawa model of colloid-polymer mixtures, the transition between these two different scenarios is characterized. It is shown that the density distribution changes gradually from a double-peak structure to a triple-peak shape, and the correlation length in the axial direction (measuring the equilibrium domain length) becomes much smaller than the cylinder length. The (rounded) transition to the disordered phase of the fluid occurs when the axial correlation length has decreased to a value comparable to the cylinder diameter. It is also suggested that adsorption hysteresis vanishes when the transition from the simple domain state to the multidomain state of the cylindrical pore occurs. We predict that the difference between the pore critical temperature and the hysteresis critical temperature should increase logarithmically with the length of the pore.

  6. Characterization of coherent structures in three-dimensional turbulent flows using the finite-size Lyapunov exponent

    International Nuclear Information System (INIS)

    Bettencourt, João H; López, Cristóbal; Hernández-García, Emilio

    2013-01-01

    In this paper, we use the finite-size Lyapunov exponent (FSLE) to characterize Lagrangian coherent structures in three-dimensional (3D) turbulent flows. Lagrangian coherent structures act as the organizers of transport in fluid flows and are crucial to understand their stirring and mixing properties. Generalized maxima (ridges) of the FSLE fields are used to locate these coherent structures. 3D FSLE fields are calculated in two phenomenologically distinct turbulent flows: a wall-bounded flow (channel flow) and a regional oceanic flow obtained by the numerical solution of the primitive equations where two-dimensional (2D) turbulence dominates. In the channel flow, autocorrelations of the FSLE field show that the structure is substantially different from the near wall to the mid-channel region and relates well to the more widely studied Eulerian coherent structure of the turbulent channel flow. The ridges of the FSLE field have complex shapes due to the 3D character of the turbulent fluctuations. In the oceanic flow, strong horizontal stirring is present and the flow regime is similar to that of 2D turbulence where the domain is populated by coherent eddies that interact strongly. This in turn results in the presence of high FSLE lines throughout the domain leading to strong non-local mixing. The ridges of the FSLE field are quasi-vertical surfaces, indicating that the horizontal dynamics dominates the flow. Indeed, due to rotation and stratification, vertical motions in the ocean are much less intense than horizontal ones. This suppression is absent in the channel flow, as the 3D character of the FSLE ridges shows. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Lyapunov analysis: from dynamical systems theory to applications’. (paper)

  7. Ignorance-Based Instruction in Higher Education.

    Science.gov (United States)

    Stocking, S. Holly

    1992-01-01

    Describes how three groups of educators (in a medical school, a psychology department, and a journalism school) are helping instructors and students to recognize, manage, and use ignorance to promote learning. (SR)

  8. Is Ignorance of Climate Change Culpable?

    Science.gov (United States)

    Robichaud, Philip

    2017-10-01

    Sometimes ignorance is an excuse. If an agent did not know and could not have known that her action would realize some bad outcome, then it is plausible to maintain that she is not to blame for realizing that outcome, even when the act that leads to this outcome is wrong. This general thought can be brought to bear in the context of climate change insofar as we think (a) that the actions of individual agents play some role in realizing climate harms and (b) that these actions are apt targets for being considered right or wrong. Are agents who are ignorant about climate change and the way their actions contribute to it excused because of their ignorance, or is their ignorance culpable? In this paper I examine these questions from the perspective of recent developments in the theories of responsibility for ignorant action and characterize their verdicts. After developing some objections to existing attempts to explore these questions, I characterize two influential theories of moral responsibility and discuss their implications for three different types of ignorance about climate change. I conclude with some recommendations for how we should react to the face of the theories' conflicting verdicts. The answer to the question posed in the title, then, is: "Well, it's complicated."

  9. Using the volumetric effect of a finite-sized detector for routine quality assurance of multileaf collimator leaf positioning

    International Nuclear Information System (INIS)

    Yang Yong; Xing Lei

    2003-01-01

    Intensity modulated radiation therapy (IMRT) is an advanced form of radiation therapy and promises to improve dose conformation while reducing the irradiation to the sensitive structures. The modality is, however, more complicated than conventional treatment and requires much more stringent quality assurance (QA) to ensure what has been planned can be achieved accurately. One of the main QA tasks is the assurance of positioning accuracy of multileaf collimator (MLC) leaves during IMRT delivery. Currently, the routine quality assurance of MLC in most clinics is being done using radiographic films with specially designed MLC leaf sequences. Besides being time consuming, the results of film measurements are difficult to quantify and interpret. In this work, we propose a new and effective technique for routine MLC leaf positioning QA. The technique utilizes the fact that, when a finite-sized detector is placed under a leaf, the relative output of the detector will depend on the relative fractional volume irradiated. A small error in leaf positioning would change the fractional volume irradiated and lead to a deviation of the relative output from the normal reading. For a given MLC and detector system, the relation between the relative output and the leaf displacement can be easily established through experimental measurements and used subsequently as a quantitative means for detecting possible leaf positional errors. The method was tested using a linear accelerator with an 80-leaf MLC. Three different locations, including two locations on central plane (X1=X2=0) and one point on an off-central plane location (X1=-7.5, X=7.5), were studied. Our results indicated that the method could accurately detect a leaf positional change of ∼0.1 mm. The method was also used to monitor the stability of MLC leaf positioning for five consecutive weeks. In this test, we intentionally introduced two positional errors in the testing MLC leaf sequences: -0.2 mm and 1.2 mm. The technique

  10. Radiative nonrecoil nuclear finite size corrections of order $\\alpha(Z \\alpha)^5$ to the Lamb shift in light muonic atoms

    OpenAIRE

    Faustov, R. N.; Martynenko, A. P.; Martynenko, F. A.; Sorokin, V. V.

    2017-01-01

    On the basis of quasipotential method in quantum electrodynamics we calculate nuclear finite size radiative corrections of order α(Zα)5 to the Lamb shift in muonic hydrogen and helium. To construct the interaction potential of particles, which gives the necessary contributions to the energy spectrum, we use the method of projection operators to states with a definite spin. Separate analytic expressions for the contributions of the muon self-energy, the muon vertex operator and the amplitude...

  11. Finite size vertex correction to the strong decay of ηc and χc states and a determination of αs(mc)

    International Nuclear Information System (INIS)

    Ping Ronggang; Jiang Huanqing; Zou Bingsong

    2002-01-01

    In previous calculations of the strong decay of a charmonium, the first-order momentum dependence of the quark propagator is kept. It was found that the finite-size vertex correction to the Γ(J/ψ→3g) process is large. The authors calculate the two-gluon decay widths of η e , χ c0 and χ c2 by including the full momentum dependence of the quark propagator. Comparing to the zero-order calculation the authors find that the finite-size vertex correction factor to the two-gluon decay widths of η c is 1.32, and for the two-gluon decays of χ c0 and χ c2 , the vertex correction factors are 1.45 and 1.26, respectively. With the corrected decay widths Γ(η c →2g) authors extract the value as α s (m c ) = 0.28 +- 0.05 which agrees with that calculated from the Γ(J/ψ→3g) process with the same correction. The finite-size vertex correction to the process Γ(η c →3g) is not as large as that to the process Γ(J/ψ→3g)

  12. Finite-size corrections for quantum strings on AdS4 x CP3

    DEFF Research Database (Denmark)

    Astolfi, D.; Puletti, V.G.M.; Grignani, G.

    2011-01-01

    the one for light modes. With this prescription the strong-weak coupling interpolating function h(¿), entering the magnon dispersion relation, does not receive a one-loop correction, in agreement with the algebraic curve spectrum. However, the single magnon dispersion relation exhibits finite...

  13. Knowledge, responsibility, decision making and ignorance

    DEFF Research Database (Denmark)

    Huniche, Lotte

    2001-01-01

    of and ignoring) seems to be commonly applicable to describing persons living at risk for Huntington´s Disease (HD). So what does everyday conduct of life look like from an "ignorance" perspective? And how can we discuss and argue about morality and ethics taking these seemingly diverse ways of living at risk...... into account? Posing this question, I hope to contribute to new reflections on possibilities and constraints in people´s lives with HD as well as in research and to open up new ways of discussing "right and wrong"....

  14. DMPD: TLR ignores methylated RNA? [Dynamic Macrophage Pathway CSML Database

    Lifescience Database Archive (English)

    Full Text Available 16111629 TLR ignores methylated RNA? Ishii KJ, Akira S. Immunity. 2005 Aug;23(2):11...1-3. (.png) (.svg) (.html) (.csml) Show TLR ignores methylated RNA? PubmedID 16111629 Title TLR ignores methylated

  15. Radiative nonrecoil nuclear finite size corrections of order α(Zα){sup 5} to the hyperfine splitting of S-states in muonic hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Faustov, R.N. [Dorodnicyn Computing Centre, Russian Academy of Science, Vavilov Str. 40, 119991 Moscow (Russian Federation); Martynenko, A.P. [Samara State University, Pavlov Str. 1, 443011 Samara (Russian Federation); Samara State Aerospace University named after S.P. Korolyov, Moskovskoye Shosse 34, 443086 Samara (Russian Federation); Martynenko, G.A.; Sorokin, V.V. [Samara State University, Pavlov Str. 1, 443011 Samara (Russian Federation)

    2014-06-02

    On the basis of quasipotential method in quantum electrodynamics we calculate nuclear finite size radiative corrections of order α(Zα){sup 5} to the hyperfine structure of S-wave energy levels in muonic hydrogen and muonic deuterium. For the construction of the particle interaction operator we employ the projection operators on the particle bound states with definite spins. The calculation is performed in the infrared safe Fried–Yennie gauge. Modern experimental data on the electromagnetic form factors of the proton and deuteron are used.

  16. Radiative nonrecoil nuclear finite size corrections of order α(Zα)5 to the hyperfine splitting of S-states in muonic hydrogen

    International Nuclear Information System (INIS)

    Faustov, R.N.; Martynenko, A.P.; Martynenko, G.A.; Sorokin, V.V.

    2014-01-01

    On the basis of quasipotential method in quantum electrodynamics we calculate nuclear finite size radiative corrections of order α(Zα) 5 to the hyperfine structure of S-wave energy levels in muonic hydrogen and muonic deuterium. For the construction of the particle interaction operator we employ the projection operators on the particle bound states with definite spins. The calculation is performed in the infrared safe Fried–Yennie gauge. Modern experimental data on the electromagnetic form factors of the proton and deuteron are used.

  17. Friction tensor for a pair of Brownian particles: Spurious finite-size effects and molecular dynamics estimates

    International Nuclear Information System (INIS)

    Bocquet, L.; Hansen, J.P.; Piasecki, J.

    1997-01-01

    In this work, we show that in any finite system, the binary friction tenser for two Brownian particles cannot be directly estimated from an evaluation of the microscopic Green Kubo formula, involving the time integral of force-force autocorrelation functions. This pitfall is associated with a subtle inversion of the thermodynamic and long-time limits and leads to spurious results for the estimates of the friction matrix based on molecular dynamics simulations. Starting from a careful analysis of the coupled Langevin equations for two interacting Brownian particles, we derive a method to circumvent these effects and extract the binary friction tenser from the correlation function matrix of the instantaneous forces exerted by the bath particles on the fixed Brownian particles, and from the relaxation of the total momentum of the bath in a finite system. The general methodology is applied to the case of two hard or soft Brownian spheres in a bath of light particles. Numerical estimates of the relevant correlation functions and of the resulting self and mutual components of the matrix of friction tensors are obtained by molecular dynamics simulations for various spacings between the Brownian particles

  18. Fast mean and variance computation of the diffuse sound transmission through finite-sized thick and layered wall and floor systems

    Science.gov (United States)

    Decraene, Carolina; Dijckmans, Arne; Reynders, Edwin P. B.

    2018-05-01

    A method is developed for computing the mean and variance of the diffuse field sound transmission loss of finite-sized layered wall and floor systems that consist of solid, fluid and/or poroelastic layers. This is achieved by coupling a transfer matrix model of the wall or floor to statistical energy analysis subsystem models of the adjacent room volumes. The modal behavior of the wall is approximately accounted for by projecting the wall displacement onto a set of sinusoidal lateral basis functions. This hybrid modal transfer matrix-statistical energy analysis method is validated on multiple wall systems: a thin steel plate, a polymethyl methacrylate panel, a thick brick wall, a sandwich panel, a double-leaf wall with poro-elastic material in the cavity, and a double glazing. The predictions are compared with experimental data and with results obtained using alternative prediction methods such as the transfer matrix method with spatial windowing, the hybrid wave based-transfer matrix method, and the hybrid finite element-statistical energy analysis method. These comparisons confirm the prediction accuracy of the proposed method and the computational efficiency against the conventional hybrid finite element-statistical energy analysis method.

  19. Should general psychiatry ignore somatization and hypochondriasis?

    Science.gov (United States)

    Creed, Francis

    2006-10-01

    This paper examines the tendency for general psychiatry to ignore somatization and hypochondriasis. These disorders are rarely included in national surveys of mental health and are not usually regarded as a concern of general psychiatrists; yet primary care doctors and other physicians often feel let down by psychiatry's failure to offer help in this area of medical practice. Many psychiatrists are unaware of the suffering, impaired function and high costs that can result from these disorders, because these occur mainly within primary care and secondary medical services. Difficulties in diagnosis and a tendency to regard them as purely secondary phenomena of depression, anxiety and related disorders mean that general psychiatry may continue to ignore somatization and hypochondriasis. If general psychiatry embraced these disorders more fully, however, it might lead to better prevention and treatment of depression as well as helping to prevent the severe disability that may arise in association with these disorders.

  20. Should general psychiatry ignore somatization and hypochondriasis?

    OpenAIRE

    CREED, FRANCIS

    2006-01-01

    This paper examines the tendency for general psychiatry to ignore somatization and hypochondriasis. These disorders are rarely included in national surveys of mental health and are not usually regarded as a concern of general psychiatrists; yet primary care doctors and other physicians often feel let down by psychiatry's failure to offer help in this area of medical practice. Many psychiatrists are unaware of the suffering, impaired function and high costs that can result fr...

  1. Power-law correlations and finite-size effects in silica particle aggregates studied by small-angle neutron scattering

    DEFF Research Database (Denmark)

    Freltoft, T.; Kjems, Jørgen; Sinha, S. K.

    1986-01-01

    Small-angle neutron scattering from normal, compressed, and water-suspended powders of aggregates of fine silica particles has been studied. The samples possessed average densities ranging from 0.008 to 0.45 g/cm3. Assuming power-law correlations between particles and a finite correlation length ξ......, the authors derive the scattering function S(q) from specific models for particle-particle correlation in these systems. S(q) was found to provide a satisfactory fit to the data for all samples studied. The fractal dimension df corresponding to the power-law correlation was 2.61±0.1 for all dry samples, and 2...

  2. Finite-size effects in transcript sequencing count distribution: its power-law correction necessarily precedes downstream normalization and comparative analysis.

    Science.gov (United States)

    Wong, Wing-Cheong; Ng, Hong-Kiat; Tantoso, Erwin; Soong, Richie; Eisenhaber, Frank

    2018-02-12

    Though earlier works on modelling transcript abundance from vertebrates to lower eukaroytes have specifically singled out the Zip's law, the observed distributions often deviate from a single power-law slope. In hindsight, while power-laws of critical phenomena are derived asymptotically under the conditions of infinite observations, real world observations are finite where the finite-size effects will set in to force a power-law distribution into an exponential decay and consequently, manifests as a curvature (i.e., varying exponent values) in a log-log plot. If transcript abundance is truly power-law distributed, the varying exponent signifies changing mathematical moments (e.g., mean, variance) and creates heteroskedasticity which compromises statistical rigor in analysis. The impact of this deviation from the asymptotic power-law on sequencing count data has never truly been examined and quantified. The anecdotal description of transcript abundance being almost Zipf's law-like distributed can be conceptualized as the imperfect mathematical rendition of the Pareto power-law distribution when subjected to the finite-size effects in the real world; This is regardless of the advancement in sequencing technology since sampling is finite in practice. Our conceptualization agrees well with our empirical analysis of two modern day NGS (Next-generation sequencing) datasets: an in-house generated dilution miRNA study of two gastric cancer cell lines (NUGC3 and AGS) and a publicly available spike-in miRNA data; Firstly, the finite-size effects causes the deviations of sequencing count data from Zipf's law and issues of reproducibility in sequencing experiments. Secondly, it manifests as heteroskedasticity among experimental replicates to bring about statistical woes. Surprisingly, a straightforward power-law correction that restores the distribution distortion to a single exponent value can dramatically reduce data heteroskedasticity to invoke an instant increase in

  3. Artificial Leaks in Container Closure Integrity Testing: Nonlinear Finite Element Simulation of Aperture Size Originated by a Copper Wire Sandwiched between the Stopper and the Glass Vial.

    Science.gov (United States)

    Nieto, Alejandra; Roehl, Holger; Brown, Helen; Adler, Michael; Chalus, Pascal; Mahler, Hanns-Christian

    2016-01-01

    Container closure integrity (CCI) testing is required by different regulatory authorities in order to provide assurance of tightness of the container closure system against possible contamination, for example, by microorganisms. Microbial ingress CCI testing is performed by incubation of the container closure system with microorganisms under specified testing conditions. Physical CCI uses surrogate endpoints, such as coloration by dye solution ingress or gas flow (helium leakage testing). In order to correlate microbial CCI and physical CCI test methods and to evaluate the methods' capability to detect a given leak, artificial leaks are being introduced into the container closure system in a variety of different ways. In our study, artificial leaks were generated using inserted copper wires between the glass vial opening and rubber stopper. However, the insertion of copper wires introduces leaks of unknown size and shape. With nonlinear finite element simulations, the aperture size between the rubber stopper and the glass vial was calculated, depending on wire diameter and capping force. The dependency of the aperture size on the copper wire diameter was quadratic. With the data obtained, we were able to calculate the leak size and model leak shape. Our results suggest that the size as well as the shape of the artificial leaks should be taken into account when evaluating critical leak sizes, as flow rate does not, independently, correlate to hole size. Capping force also affected leak size. An increase in the capping force from 30 to 70 N resulted in a reduction of the aperture (leak size) by approximately 50% for all wire diameters. From 30 to 50 N, the reduction was approximately 33%. Container closure integrity (CCI) testing is required by different regulatory authorities in order to provide assurance of tightness of the container closure system against contamination, for example, by microorganisms. Microbial ingress CCI testing is performed by incubation of the

  4. Pore-scale simulations of drainage in granular materials: Finite size effects and the representative elementary volume

    Science.gov (United States)

    Yuan, Chao; Chareyre, Bruno; Darve, Félix

    2016-09-01

    A pore-scale model is introduced for two-phase flow in dense packings of polydisperse spheres. The model is developed as a component of a more general hydromechanical coupling framework based on the discrete element method, which will be elaborated in future papers and will apply to various processes of interest in soil science, in geomechanics and in oil and gas production. Here the emphasis is on the generation of a network of pores mapping the void space between spherical grains, and the definition of local criteria governing the primary drainage process. The pore space is decomposed by Regular Triangulation, from which a set of pores connected by throats are identified. A local entry capillary pressure is evaluated for each throat, based on the balance of capillary pressure and surface tension at equilibrium. The model reflects the possible entrapment of disconnected patches of the receding wetting phase. It is validated by a comparison with drainage experiments. In the last part of the paper, a series of simulations are reported to illustrate size and boundary effects, key questions when studying small samples made of spherical particles be it in simulations or experiments. Repeated tests on samples of different sizes give evolution of water content which are not only scattered but also strongly biased for small sample sizes. More than 20,000 spheres are needed to reduce the bias on saturation below 0.02. Additional statistics are generated by subsampling a large sample of 64,000 spheres. They suggest that the minimal sampling volume for evaluating saturation is one hundred times greater that the sampling volume needed for measuring porosity with the same accuracy. This requirement in terms of sample size induces a need for efficient computer codes. The method described herein has a low algorithmic complexity in order to satisfy this requirement. It will be well suited to further developments toward coupled flow-deformation problems in which evolution of the

  5. On sets of vectors of a finite vector space in which every subset of basis size is a basis II

    OpenAIRE

    Ball, Simeon; De Beule, Jan

    2012-01-01

    This article contains a proof of the MDS conjecture for k a parts per thousand currency sign 2p - 2. That is, that if S is a set of vectors of in which every subset of S of size k is a basis, where q = p (h) , p is prime and q is not and k a parts per thousand currency sign 2p - 2, then |S| a parts per thousand currency sign q + 1. It also contains a short proof of the same fact for k a parts per thousand currency sign p, for all q.

  6. Radiative nonrecoil nuclear finite size corrections of order α(Zα5 to the Lamb shift in light muonic atoms

    Directory of Open Access Journals (Sweden)

    R.N. Faustov

    2017-12-01

    Full Text Available On the basis of quasipotential method in quantum electrodynamics we calculate nuclear finite size radiative corrections of order α(Zα5 to the Lamb shift in muonic hydrogen and helium. To construct the interaction potential of particles, which gives the necessary contributions to the energy spectrum, we use the method of projection operators to states with a definite spin. Separate analytic expressions for the contributions of the muon self-energy, the muon vertex operator and the amplitude with spanning photon are obtained. We present also numerical results for these contributions using modern experimental data on the electromagnetic form factors of light nuclei. Keywords: Lamb shift, Muonic atoms, Quantum electrodynamics

  7. Universal Signatures of Quantum Critical Points from Finite-Size Torus Spectra: A Window into the Operator Content of Higher-Dimensional Conformal Field Theories.

    Science.gov (United States)

    Schuler, Michael; Whitsitt, Seth; Henry, Louis-Paul; Sachdev, Subir; Läuchli, Andreas M

    2016-11-18

    The low-energy spectra of many body systems on a torus, of finite size L, are well understood in magnetically ordered and gapped topological phases. However, the spectra at quantum critical points separating such phases are largely unexplored for (2+1)D systems. Using a combination of analytical and numerical techniques, we accurately calculate and analyze the low-energy torus spectrum at an Ising critical point which provides a universal fingerprint of the underlying quantum field theory, with the energy levels given by universal numbers times 1/L. We highlight the implications of a neighboring topological phase on the spectrum by studying the Ising* transition (i.e. the transition between a Z_{2} topological phase and a trivial paramagnet), in the example of the toric code in a longitudinal field, and advocate a phenomenological picture that provides qualitative insight into the operator content of the critical field theory.

  8. Effects of heater location and heater size on the natural convection heat transfer in a square cavity using finite element method

    Energy Technology Data Exchange (ETDEWEB)

    Ngo, Ich Long; Byon, Chan [Yeungnam University, Gyeongsan (Korea, Republic of)

    2015-07-15

    Finite element method was used to investigate the effects of heater location and heater size on the natural convection heat transfer in a 2D square cavity heated partially or fully from below and cooled from above. Rayleigh number (5 X 10{sup 2} ≤ Ra ≤ 5X10{sup 5}), heater size (0.1 ≤ D/L ≤ 1.0), and heater location (0.1 ≤ x{sub h}/L ≤ 0.5) were considered. Numerical results indicated that the average Nusselt number (Nu{sub m}) increases as the heater size decreases. In addition, when x{sub h}/L is less than 0.4, Nu{sub m} increases as x{sub h}/L increases, and Num decreases again for a larger value of x{sub h}/L. However, this trend changes when Ra is less than 10{sup 4}, suggesting that Nu{sub m} attains its maximum value at the region close to the bottom surface center. This study aims to gain insight into the behaviors of natural convection in order to potentially improve internal natural convection heat transfer.

  9. Finite-size effects on the dynamic susceptibility of CoPhOMe single-chain molecular magnets in presence of a static magnetic field

    Science.gov (United States)

    Pini, M. G.; Rettori, A.; Bogani, L.; Lascialfari, A.; Mariani, M.; Caneschi, A.; Sessoli, R.

    2011-09-01

    The static and dynamic properties of the single-chain molecular magnet Co(hfac)2NITPhOMe (CoPhOMe) (hfac = hexafluoroacetylacetonate, NITPhOMe = 4'-methoxy-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) are investigated in the framework of the Ising model with Glauber dynamics, in order to take into account both the effect of an applied magnetic field and a finite size of the chains. For static fields of moderate intensity and short chain lengths, the approximation of a monoexponential decay of the magnetization fluctuations is found to be valid at low temperatures; for strong fields and long chains, a multiexponential decay should rather be assumed. The effect of an oscillating magnetic field, with intensity much smaller than that of the static one, is included in the theory in order to obtain the dynamic susceptibility χ(ω). We find that, for an open chain with N spins, χ(ω) can be written as a weighted sum of N frequency contributions, with a sum rule relating the frequency weights to the static susceptibility of the chain. Very good agreement is found between the theoretical dynamic susceptibility and the ac susceptibility measured in moderate static fields (Hdc≤2 kOe), where the approximation of a single dominating frequency for each segment length turns out to be valid. For static fields in this range, data for the relaxation time, τ versus Hdc, of the magnetization of CoPhOMe at low temperature are also qualitatively reproduced by theory, provided that finite-size effects are included.

  10. Issues ignored in laboratory quality surveillance

    International Nuclear Information System (INIS)

    Zeng Jing; Li Xingyuan; Zhang Tingsheng

    2008-01-01

    According to the work requirement of the related laboratory quality surveillance in ISO17025, this paper analyzed and discussed the issued ignored in the laboratory quality surveillance. In order to solve the present problem, it is required to understand the work responsibility in the quality surveillance correctly, to establish the effective working routine in the quality surveillance, and to conduct, the quality surveillance work. The object in the quality surveillance shall be 'the operator' who engaged in the examination/calibration directly in the laboratory, especially the personnel in training (who is engaged in the examination/calibration). The quality supervisors shall be fully authorized, so that they can correctly understand the work responsibility in quality surveillance, and are with the rights for 'full supervision'. The laboratory also shall arrange necessary training to the quality supervisor, so that they can obtain sufficient guide in time and are with required qualification or occupation prerequisites. (authors)

  11. Exploitation of commercial remote sensing images: reality ignored?

    Science.gov (United States)

    Allen, Paul C.

    1999-12-01

    The remote sensing market is on the verge of being awash in commercial high-resolution images. Market estimates are based on the growing numbers of planned commercial remote sensing electro-optical, radar, and hyperspectral satellites and aircraft. EarthWatch, Space Imaging, SPOT, and RDL among others are all working towards launch and service of one to five meter panchromatic or radar-imaging satellites. Additionally, new advances in digital air surveillance and reconnaissance systems, both manned and unmanned, are also expected to expand the geospatial customer base. Regardless of platform, image type, or location, each system promises images with some combination of increased resolution, greater spectral coverage, reduced turn-around time (request-to- delivery), and/or reduced image cost. For the most part, however, market estimates for these new sources focus on the raw digital images (from collection to the ground station) while ignoring the requirements for a processing and exploitation infrastructure comprised of exploitation tools, exploitation training, library systems, and image management systems. From this it would appear the commercial imaging community has failed to learn the hard lessons of national government experience choosing instead to ignore reality and replicate the bias of collection over processing and exploitation. While this trend may be not impact the small quantity users that exist today it will certainly adversely affect the mid- to large-sized users of the future.

  12. Finite-size effects on electronic structure and local properties in passivated AA -stacked bilayer armchair-edge graphene nanoribbons

    International Nuclear Information System (INIS)

    Chen, Xiongwen; Shi, Zhengang; Xiang, Shaohua; Song, Kehui; Zhou, Guanghui

    2017-01-01

    Based on the tight-binding model and dual-probe scanning tunneling microscopy technology, we theoretically investigate the electronic structure and local property in the passivated AA -stacked bilayer armchair-edge graphene nanoribbons (AABLAGNRs). We show that they are highly sensitive to the size of the ribbons, which is evidently different from the single-layer armchair-edge graphene nanoribbons. The ‘3 p ’ rule only applies to the narrow AABLGNRs. Namely, in the passivated 3 p - and (3 p   +  1)-AABLGNRs, the narrow ribbons are semiconducting while the medium and wide ribbons are metallic. Although the passivated (3 p   +  2)-AABLGNRs are metallic, the ‘3 j ’ rule only applies to the narrow and medium ribbons. Namely, electrons are in the semiconducting states at sites of line 3 j while they are in the metallic states at other sites. This induces a series of parallel and discrete metallic channels, consisting of lines 3 j   −  1 and 3 j   −  2, for the low-energy electronic transports. In the passivated wide (3 p   +  2)-AABLGNRs, all electrons are in the metallic states. Additionally, the ‘3 p ’ and ‘3 j ’ rules are controllable to disappear and reappear by applying an external perpendicular electric field. Resultantly, an electric filed-driven current switch can be realized in the passivated narrow and medium (3 p   +  2)-AABLGNRs. (paper)

  13. Ignorance of electrosurgery among obstetricians and gynaecologists.

    Science.gov (United States)

    Mayooran, Zorana; Pearce, Scott; Tsaltas, Jim; Rombauts, Luk; Brown, T Ian H; Lawrence, Anthony S; Fraser, Kym; Healy, David L

    2004-12-01

    The purpose of this study was to assess the level of skill of laparoscopic surgeons in electrosurgery. Subjects were asked to complete a practical diathermy station and a written test of electrosurgical knowledge. Tests were held in teaching and non-teaching hospitals. Twenty specialists in obstetrics and gynaecology were randomly selected and tested on the Monash University gynaecological laparoscopic pelvi-trainer. Twelve candidates were consultants with 9-28 years of practice in operative laparoscopy, and 8 were registrars with up to six years of practice in operative laparoscopy. Seven consultants and one registrar were from rural Australia, and three consultants were from New Zealand. Candidates were marked with checklist criteria resulting in a pass/fail score, as well as a weighted scoring system. We retested 11 candidates one year later with the same stations. No improvement in electrosurgery skill in one year of obstetric and gynaecological practice. No candidate successfully completed the written electrosurgery station in the initial test. A slight improvement in the pass rate to 18% was observed in the second test. The pass rate of the diathermy station dropped from 50% to 36% in the second test. The study found ignorance of electrosurgery/diathermy among gynaecological surgeons. One year later, skills were no better.

  14. Aspiring to Spectral Ignorance in Earth Observation

    Science.gov (United States)

    Oliver, S. A.

    2016-12-01

    Enabling robust, defensible and integrated decision making in the Era of Big Earth Data requires the fusion of data from multiple and diverse sensor platforms and networks. While the application of standardised global grid systems provides a common spatial analytics framework that facilitates the computationally efficient and statistically valid integration and analysis of these various data sources across multiple scales, there remains the challenge of sensor equivalency; particularly when combining data from different earth observation satellite sensors (e.g. combining Landsat and Sentinel-2 observations). To realise the vision of a sensor ignorant analytics platform for earth observation we require automation of spectral matching across the available sensors. Ultimately, the aim is to remove the requirement for the user to possess any sensor knowledge in order to undertake analysis. This paper introduces the concept of spectral equivalence and proposes a methodology through which equivalent bands may be sourced from a set of potential target sensors through application of equivalence metrics and thresholds. A number of parameters can be used to determine whether a pair of spectra are equivalent for the purposes of analysis. A baseline set of thresholds for these parameters and how to apply them systematically to enable relation of spectral bands amongst numerous different sensors is proposed. The base unit for comparison in this work is the relative spectral response. From this input, determination of a what may constitute equivalence can be related by a user, based on their own conceptualisation of equivalence.

  15. Stochastic delocalization of finite populations

    International Nuclear Information System (INIS)

    Geyrhofer, Lukas; Hallatschek, Oskar

    2013-01-01

    The localization of populations of replicating bacteria, viruses or autocatalytic chemicals arises in various contexts, such as ecology, evolution, medicine or chemistry. Several deterministic mathematical models have been used to characterize the conditions under which localized states can form, and how they break down due to convective driving forces. It has been repeatedly found that populations remain localized unless the bias exceeds a critical threshold value, and that close to the transition the population is characterized by a diverging length scale. These results, however, have been obtained upon ignoring number fluctuations (‘genetic drift’), which are inevitable given the discreteness of the replicating entities. Here, we study the localization/delocalization of a finite population in the presence of genetic drift. The population is modeled by a linear chain of subpopulations, or demes, which exchange migrants at a constant rate. Individuals in one particular deme, called ‘oasis’, receive a growth rate benefit, and the total population is regulated to have constant size N. In this ecological setting, we find that any finite population delocalizes on sufficiently long time scales. Depending on parameters, however, populations may remain localized for a very long time. The typical waiting time to delocalization increases exponentially with both population size and distance to the critical wind speed of the deterministic approximation. We augment these simulation results by a mathematical analysis that treats the reproduction and migration of individuals as branching random walks subject to global constraints. For a particular constraint, different from a fixed population size constraint, this model yields a solvable first moment equation. We find that this solvable model approximates very well the fixed population size model for large populations, but starts to deviate as population sizes are small. Nevertheless, the qualitative behavior of the

  16. Benford analysis of quantum critical phenomena: First digit provides high finite-size scaling exponent while first two and further are not much better

    Science.gov (United States)

    Bera, Anindita; Mishra, Utkarsh; Singha Roy, Sudipto; Biswas, Anindya; Sen(De), Aditi; Sen, Ujjwal

    2018-06-01

    Benford's law is an empirical edict stating that the lower digits appear more often than higher ones as the first few significant digits in statistics of natural phenomena and mathematical tables. A marked proportion of such analyses is restricted to the first significant digit. We employ violation of Benford's law, up to the first four significant digits, for investigating magnetization and correlation data of paradigmatic quantum many-body systems to detect cooperative phenomena, focusing on the finite-size scaling exponents thereof. We find that for the transverse field quantum XY model, behavior of the very first significant digit of an observable, at an arbitrary point of the parameter space, is enough to capture the quantum phase transition in the model with a relatively high scaling exponent. A higher number of significant digits do not provide an appreciable further advantage, in particular, in terms of an increase in scaling exponents. Since the first significant digit of a physical quantity is relatively simple to obtain in experiments, the results have potential implications for laboratory observations in noisy environments.

  17. Beyond duplicity and ignorance in global fisheries

    Directory of Open Access Journals (Sweden)

    Daniel Pauly

    2009-06-01

    Full Text Available The three decades following World War II were a period of rapidly increasing fishing effort and landings, but also of spectacular collapses, particularly in small pelagic fish stocks. This is also the period in which a toxic triad of catch underreporting, ignoring scientific advice and blaming the environment emerged as standard response to ongoing fisheries collapses, which became increasingly more frequent, finally engulfing major North Atlantic fisheries. The response to the depletion of traditional fishing grounds was an expansion of North Atlantic (and generally of northern hemisphere fisheries in three dimensions: southward, into deeper waters and into new taxa, i.e. catching and marketing species of fish and invertebrates previously spurned, and usually lower in the food web. This expansion provided many opportunities for mischief, as illustrated by the European Union’s negotiated ‘agreements’ for access to the fish resources of Northwest Africa, China’s agreement-fee exploitation of the same, and Japan blaming the resulting resource declines on the whales. Also, this expansion provided new opportunities for mislabelling seafood unfamiliar to North Americans and Europeans, and misleading consumers, thus reducing the impact of seafood guides and similar effort toward sustainability. With fisheries catches declining, aquaculture—despite all public relation efforts—not being able to pick up the slack, and rapidly increasing fuel prices, structural changes are to be expected in both the fishing industry and the scientific disciplines that study it and influence its governance. Notably, fisheries biology, now predominantly concerned with the welfare of the fishing industry, will have to be converted into fisheries conservation science, whose goal will be to resolve the toxic triad alluded to above, and thus maintain the marine biodiversity and ecosystems that provide existential services to fisheries. Similarly, fisheries

  18. Learning to ignore: acquisition of sustained attentional suppression.

    Science.gov (United States)

    Dixon, Matthew L; Ruppel, Justin; Pratt, Jay; De Rosa, Eve

    2009-04-01

    We examined whether the selection mechanisms committed to the suppression of ignored stimuli can be modified by experience to produce a sustained, rather than transient, change in behavior. Subjects repeatedly ignored the shape of stimuli, while attending to their color. On subsequent attention to shape, there was a robust and sustained decrement in performance that was selective to when shape was ignored across multiple-color-target contexts, relative to a single-color-target context. Thus, amount of time ignored was not sufficient to induce a sustained performance decrement. Moreover, in this group, individual differences in initial color target selection were associated with the subsequent performance decrement when attending to previously ignored stimuli. Accompanying this sustained decrement in performance was a transfer in the locus of suppression from an exemplar (e.g., a circle) to a feature (i.e., shape) level of representation. These data suggest that learning can influence attentional selection by sustained attentional suppression of ignored stimuli.

  19. On strategic ignorance of environmental harm and social norms

    DEFF Research Database (Denmark)

    Thunström, Linda; van 't Veld, Klaas; Shogren, Jason

    , and that they use ignorance as an excuse to engage in less pro-environmental behavior. It also predicts that the cost of ignorance increases if people can learn about the social norm from the information. We test the model predictions empirically with an experiment that involves an imaginary long- distance flight...... and an option to buy offsets for the flight’s carbon footprint. More than half (53 percent) of the subjects choose to ignore information on the carbon footprint alone before deciding their offset purchase, but ignorance significantly decreases (to 29 percent) when the information additionally reveals the social...

  20. On strategic ignorance of environmental harm and social norms

    DEFF Research Database (Denmark)

    Thunström, Linda; van’t Veld, Klaas; Shogren, Jason. F.

    2014-01-01

    decreases (to 29 percent) when the information additionally reveals the share of air travelers who buy carbon offsets. We find evidence that some people use ignorance as an excuse to reduce pro-environmental behavior—ignorance significantly decreases the probability of buying carbon offsets.......Are people strategically ignorant of the negative externalities their activities cause the environment? Herein we examine if people avoid costless information on those externalities and use ignorance as an excuse to reduce pro-environmental behavior. We develop a theoretical framework in which...... people feel internal pressure (“guilt”) from causing harm to the environment (e.g., emitting carbon dioxide) as well as external pressure to conform to the social norm for pro-environmental behavior (e.g., offsetting carbon emissions). Our model predicts that people may benefit from avoiding information...

  1. Calculating the binding free energies of charged species based on explicit-solvent simulations employing lattice-sum methods: an accurate correction scheme for electrostatic finite-size effects.

    Science.gov (United States)

    Rocklin, Gabriel J; Mobley, David L; Dill, Ken A; Hünenberger, Philippe H

    2013-11-14

    The calculation of a protein-ligand binding free energy based on molecular dynamics (MD) simulations generally relies on a thermodynamic cycle in which the ligand is alchemically inserted into the system, both in the solvated protein and free in solution. The corresponding ligand-insertion free energies are typically calculated in nanoscale computational boxes simulated under periodic boundary conditions and considering electrostatic interactions defined by a periodic lattice-sum. This is distinct from the ideal bulk situation of a system of macroscopic size simulated under non-periodic boundary conditions with Coulombic electrostatic interactions. This discrepancy results in finite-size effects, which affect primarily the charging component of the insertion free energy, are dependent on the box size, and can be large when the ligand bears a net charge, especially if the protein is charged as well. This article investigates finite-size effects on calculated charging free energies using as a test case the binding of the ligand 2-amino-5-methylthiazole (net charge +1 e) to a mutant form of yeast cytochrome c peroxidase in water. Considering different charge isoforms of the protein (net charges -5, 0, +3, or +9 e), either in the absence or the presence of neutralizing counter-ions, and sizes of the cubic computational box (edges ranging from 7.42 to 11.02 nm), the potentially large magnitude of finite-size effects on the raw charging free energies (up to 17.1 kJ mol(-1)) is demonstrated. Two correction schemes are then proposed to eliminate these effects, a numerical and an analytical one. Both schemes are based on a continuum-electrostatics analysis and require performing Poisson-Boltzmann (PB) calculations on the protein-ligand system. While the numerical scheme requires PB calculations under both non-periodic and periodic boundary conditions, the latter at the box size considered in the MD simulations, the analytical scheme only requires three non-periodic PB

  2. Calculating the binding free energies of charged species based on explicit-solvent simulations employing lattice-sum methods: An accurate correction scheme for electrostatic finite-size effects

    Energy Technology Data Exchange (ETDEWEB)

    Rocklin, Gabriel J. [Department of Pharmaceutical Chemistry, University of California San Francisco, 1700 4th St., San Francisco, California 94143-2550, USA and Biophysics Graduate Program, University of California San Francisco, 1700 4th St., San Francisco, California 94143-2550 (United States); Mobley, David L. [Departments of Pharmaceutical Sciences and Chemistry, University of California Irvine, 147 Bison Modular, Building 515, Irvine, California 92697-0001, USA and Department of Chemistry, University of New Orleans, 2000 Lakeshore Drive, New Orleans, Louisiana 70148 (United States); Dill, Ken A. [Laufer Center for Physical and Quantitative Biology, 5252 Stony Brook University, Stony Brook, New York 11794-0001 (United States); Hünenberger, Philippe H., E-mail: phil@igc.phys.chem.ethz.ch [Laboratory of Physical Chemistry, Swiss Federal Institute of Technology, ETH, 8093 Zürich (Switzerland)

    2013-11-14

    The calculation of a protein-ligand binding free energy based on molecular dynamics (MD) simulations generally relies on a thermodynamic cycle in which the ligand is alchemically inserted into the system, both in the solvated protein and free in solution. The corresponding ligand-insertion free energies are typically calculated in nanoscale computational boxes simulated under periodic boundary conditions and considering electrostatic interactions defined by a periodic lattice-sum. This is distinct from the ideal bulk situation of a system of macroscopic size simulated under non-periodic boundary conditions with Coulombic electrostatic interactions. This discrepancy results in finite-size effects, which affect primarily the charging component of the insertion free energy, are dependent on the box size, and can be large when the ligand bears a net charge, especially if the protein is charged as well. This article investigates finite-size effects on calculated charging free energies using as a test case the binding of the ligand 2-amino-5-methylthiazole (net charge +1 e) to a mutant form of yeast cytochrome c peroxidase in water. Considering different charge isoforms of the protein (net charges −5, 0, +3, or +9 e), either in the absence or the presence of neutralizing counter-ions, and sizes of the cubic computational box (edges ranging from 7.42 to 11.02 nm), the potentially large magnitude of finite-size effects on the raw charging free energies (up to 17.1 kJ mol{sup −1}) is demonstrated. Two correction schemes are then proposed to eliminate these effects, a numerical and an analytical one. Both schemes are based on a continuum-electrostatics analysis and require performing Poisson-Boltzmann (PB) calculations on the protein-ligand system. While the numerical scheme requires PB calculations under both non-periodic and periodic boundary conditions, the latter at the box size considered in the MD simulations, the analytical scheme only requires three non

  3. Calculating the binding free energies of charged species based on explicit-solvent simulations employing lattice-sum methods: An accurate correction scheme for electrostatic finite-size effects

    Science.gov (United States)

    Rocklin, Gabriel J.; Mobley, David L.; Dill, Ken A.; Hünenberger, Philippe H.

    2013-11-01

    The calculation of a protein-ligand binding free energy based on molecular dynamics (MD) simulations generally relies on a thermodynamic cycle in which the ligand is alchemically inserted into the system, both in the solvated protein and free in solution. The corresponding ligand-insertion free energies are typically calculated in nanoscale computational boxes simulated under periodic boundary conditions and considering electrostatic interactions defined by a periodic lattice-sum. This is distinct from the ideal bulk situation of a system of macroscopic size simulated under non-periodic boundary conditions with Coulombic electrostatic interactions. This discrepancy results in finite-size effects, which affect primarily the charging component of the insertion free energy, are dependent on the box size, and can be large when the ligand bears a net charge, especially if the protein is charged as well. This article investigates finite-size effects on calculated charging free energies using as a test case the binding of the ligand 2-amino-5-methylthiazole (net charge +1 e) to a mutant form of yeast cytochrome c peroxidase in water. Considering different charge isoforms of the protein (net charges -5, 0, +3, or +9 e), either in the absence or the presence of neutralizing counter-ions, and sizes of the cubic computational box (edges ranging from 7.42 to 11.02 nm), the potentially large magnitude of finite-size effects on the raw charging free energies (up to 17.1 kJ mol-1) is demonstrated. Two correction schemes are then proposed to eliminate these effects, a numerical and an analytical one. Both schemes are based on a continuum-electrostatics analysis and require performing Poisson-Boltzmann (PB) calculations on the protein-ligand system. While the numerical scheme requires PB calculations under both non-periodic and periodic boundary conditions, the latter at the box size considered in the MD simulations, the analytical scheme only requires three non-periodic PB

  4. Willful Ignorance and the Death Knell of Critical Thought

    Science.gov (United States)

    Rubin, Daniel Ian

    2018-01-01

    Independent, critical thought has never been more important in the United States. In the Age of Trump, political officials spout falsehoods called "alternative facts" as if they were on equal footing with researchable, scientific data. At the same time, an unquestioning populace engages in acts of "willful ignorance" on a daily…

  5. Tunnel Vision: New England Higher Education Ignores Demographic Peril

    Science.gov (United States)

    Hodgkinson, Harold L.

    2004-01-01

    This author states that American higher education ignores about 90 percent of the environment in which it operates. Colleges change admissions requirements without even informing high schools in their service areas. Community college graduates are denied access to four-year programs because of policy changes made only after it was too late for the…

  6. Conformationally averaged vertical detachment energy of finite size NO3(-)·nH2O clusters: a route connecting few to many.

    Science.gov (United States)

    Pathak, Arup Kumar; Samanta, Alok Kumar; Maity, Dilip Kumar

    2011-04-07

    We report conformationally averaged VDEs (VDE(w)(n)) for different sizes of NO(3)(-)·nH(2)O clusters calculated by using uncorrelated HF, correlated hybrid density functional (B3LYP, BHHLYP) and correlated ab intio (MP2 and CCSD(T)) theory. It is observed that the VDE(w)(n) at the B3LYP/6-311++G(d,p), B3LYP/Aug-cc-Pvtz and CCSD(T)/6-311++G(d,p) levels is very close to the experimentally measured VDE. It is shown that the use of calculated results of the conformationally averaged VDE for small-sized solvated negatively-charged clusters and a microscopic theory-based general expression for the same provides a route to obtain the VDE for a wide range of cluster sizes, including bulk.

  7. Sound radiation from finite surfaces

    DEFF Research Database (Denmark)

    Brunskog, Jonas

    2013-01-01

    A method to account for the effect of finite size in acoustic power radiation problem of planar surfaces using spatial windowing is developed. Cremer and Heckl presents a very useful formula for the power radiating from a structure using the spatially Fourier transformed velocity, which combined...... with spatially windowing of a plane waves can be used to take into account the finite size. In the present paper, this is developed by means of a radiation impedance for finite surfaces, that is used instead of the radiation impedance for infinite surfaces. In this way, the spatial windowing is included...

  8. Professional orientation and pluralistic ignorance among jail correctional officers.

    Science.gov (United States)

    Cook, Carrie L; Lane, Jodi

    2014-06-01

    Research about the attitudes and beliefs of correctional officers has historically been conducted in prison facilities while ignoring jail settings. This study contributes to our understanding of correctional officers by examining the perceptions of those who work in jails, specifically measuring professional orientations about counseling roles, punitiveness, corruption of authority by inmates, and social distance from inmates. The study also examines whether officers are accurate in estimating these same perceptions of their peers, a line of inquiry that has been relatively ignored. Findings indicate that the sample was concerned about various aspects of their job and the management of inmates. Specifically, officers were uncertain about adopting counseling roles, were somewhat punitive, and were concerned both with maintaining social distance from inmates and with an inmate's ability to corrupt their authority. Officers also misperceived the professional orientation of their fellow officers and assumed their peer group to be less progressive than they actually were.

  9. 'More is less'. The tax effects of ignoring flow externalities

    International Nuclear Information System (INIS)

    Sandal, Leif K.; Steinshamn, Stein Ivar; Grafton, R. Quentin

    2003-01-01

    Using a model of non-linear, non-monotone decay of the stock pollutant, and starting from the same initial conditions, the paper shows that an optimal tax that corrects for both stock and flow externalities may result in a lower tax, fewer cumulative emissions (less decay in emissions) and higher output at the steady state than a corrective tax that ignores the flow externality. This 'more is less' result emphasizes that setting a corrective tax that ignores the flow externality, or imposing a corrective tax at too low a level where there exists only a stock externality, may affect both transitory and steady-state output, tax payments and cumulative emissions. The result has important policy implications for decision makers setting optimal corrective taxes and targeted emission limits whenever stock externalities exist

  10. Learning maximum entropy models from finite-size data sets: A fast data-driven algorithm allows sampling from the posterior distribution.

    Science.gov (United States)

    Ferrari, Ulisse

    2016-08-01

    Maximum entropy models provide the least constrained probability distributions that reproduce statistical properties of experimental datasets. In this work we characterize the learning dynamics that maximizes the log-likelihood in the case of large but finite datasets. We first show how the steepest descent dynamics is not optimal as it is slowed down by the inhomogeneous curvature of the model parameters' space. We then provide a way for rectifying this space which relies only on dataset properties and does not require large computational efforts. We conclude by solving the long-time limit of the parameters' dynamics including the randomness generated by the systematic use of Gibbs sampling. In this stochastic framework, rather than converging to a fixed point, the dynamics reaches a stationary distribution, which for the rectified dynamics reproduces the posterior distribution of the parameters. We sum up all these insights in a "rectified" data-driven algorithm that is fast and by sampling from the parameters' posterior avoids both under- and overfitting along all the directions of the parameters' space. Through the learning of pairwise Ising models from the recording of a large population of retina neurons, we show how our algorithm outperforms the steepest descent method.

  11. Egoism, ignorance and choice : on society's lethal infection

    OpenAIRE

    Camilleri, Jonathan

    2015-01-01

    The ability to choose and our innate selfish, or rather, self-preservative urges are a recipe for disaster. Combining this with man's ignorance by definition and especially his general refusal to accept it, inevitably leads to Man's demise as a species. It is our false notion of freedom which contributes directly to our collective death, and therefore, man's trying to escape death is, in the largest of ways, counterproductive.

  12. The importance of ignoring: Alpha oscillations protect selectivity

    OpenAIRE

    Payne, Lisa; Sekuler, Robert

    2014-01-01

    Selective attention is often thought to entail an enhancement of some task-relevant stimulus or attribute. We discuss the perspective that ignoring irrelevant, distracting information plays a complementary role in information processing. Cortical oscillations within the alpha (8–14 Hz) frequency band have emerged as a marker of sensory suppression. This suppression is linked to selective attention for visual, auditory, somatic, and verbal stimuli. Inhibiting processing of irrelevant input mak...

  13. Maggots in the Brain: Sequelae of Ignored Scalp Wound.

    Science.gov (United States)

    Aggarwal, Ashish; Maskara, Prasant

    2018-01-01

    A 26-year-old male had suffered a burn injury to his scalp in childhood and ignored it. He presented with a complaint of something crawling on his head. Inspection of his scalp revealed multiple maggots on the brain surface with erosion of overlying bone and scalp. He was successfully managed by surgical debridement and regular dressing. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. On uncertainty in information and ignorance in knowledge

    Science.gov (United States)

    Ayyub, Bilal M.

    2010-05-01

    This paper provides an overview of working definitions of knowledge, ignorance, information and uncertainty and summarises formalised philosophical and mathematical framework for their analyses. It provides a comparative examination of the generalised information theory and the generalised theory of uncertainty. It summarises foundational bases for assessing the reliability of knowledge constructed as a collective set of justified true beliefs. It discusses system complexity for ancestor simulation potentials. It offers value-driven communication means of knowledge and contrarian knowledge using memes and memetics.

  15. Gender, smoking, body size, and aneurysm geometry influence the biomechanical rupture risk of abdominal aortic aneurysms as estimated by finite element analysis.

    Science.gov (United States)

    Lindquist Liljeqvist, Moritz; Hultgren, Rebecka; Siika, Antti; Gasser, T Christian; Roy, Joy

    2017-04-01

    Finite element analysis (FEA) has been suggested to be superior to maximal diameter measurements in predicting rupture of abdominal aortic aneurysms (AAAs). Our objective was to investigate to what extent previously described rupture risk factors were associated with FEA-estimated rupture risk. One hundred forty-six patients with an asymptomatic AAA of a 40- to 60-mm diameter were retrospectively identified and consecutively included. The patients' computed tomography angiograms were analyzed by FEA without (neutral) and with (specific) input of patient-specific mean arterial pressure (MAP), gender, family history, and age. The maximal wall stress/wall strength ratio was described as a rupture risk equivalent diameter (RRED), which translated this ratio into an average aneurysm diameter of corresponding rupture risk. In multivariate linear regression, RRED neutral increased with female gender (3.7 mm; 95% confidence interval [CI], 0.13-7.3) and correlated with patient height (0.27 mm/cm; 95% CI, 0.11-0.43) and body surface area (BSA, 16 mm/m 2 ; 95% CI, 8.3-24) and inversely with body mass index (BMI, -0.40 mm/kg m -2 ; 95% CI, -0.75 to -0.054) in a wall stress-dependent manner. Wall stress-adjusted RRED neutral was raised if the patient was currently smoking (1.1 mm; 95% CI, 0.21-1.9). Age, MAP, family history, and patient weight were unrelated to RRED neutral . In specific FEA, RRED specific increased with female gender, MAP, family history positive for AAA, height, and BSA, whereas it was inversely related to BMI. All results were independent of aneurysm diameter. Peak wall stress and RRED correlated with aneurysm diameter and lumen volume. Female gender, current smoking, increased patient height and BSA, and low BMI were found to increase the mechanical rupture risk of AAAs. Previously described rupture risk factors may in part be explained by patient characteristic-dependent variations in aneurysm biomechanics. Copyright © 2016 Society for Vascular

  16. Can Strategic Ignorance Explain the Evolution of Love?

    Science.gov (United States)

    Bear, Adam; Rand, David G

    2018-04-24

    People's devotion to, and love for, their romantic partners poses an evolutionary puzzle: Why is it better to stop your search for other partners once you enter a serious relationship when you could continue to search for somebody better? A recent formal model based on "strategic ignorance" suggests that such behavior can be adaptive and favored by natural selection, so long as you can signal your unwillingness to "look" for other potential mates to your current partner. Here, we re-examine this conclusion with a more detailed model designed to capture specific features of romantic relationships. We find, surprisingly, that devotion does not typically evolve in our model: Selection favors agents who choose to "look" while in relationships and who allow their partners to do the same. Non-looking is only expected to evolve if there is an extremely large cost associated with being left by your partner. Our results therefore raise questions about the role of strategic ignorance in explaining the evolution of love. Copyright © 2018 Cognitive Science Society, Inc.

  17. The Marley hypothesis: denial of racism reflects ignorance of history.

    Science.gov (United States)

    Nelson, Jessica C; Adams, Glenn; Salter, Phia S

    2013-02-01

    This study used a signal detection paradigm to explore the Marley hypothesis--that group differences in perception of racism reflect dominant-group denial of and ignorance about the extent of past racism. White American students from a midwestern university and Black American students from two historically Black universities completed surveys about their historical knowledge and perception of racism. Relative to Black participants, White participants perceived less racism in both isolated incidents and systemic manifestations of racism. They also performed worse on a measure of historical knowledge (i.e., they did not discriminate historical fact from fiction), and this group difference in historical knowledge mediated the differences in perception of racism. Racial identity relevance moderated group differences in perception of systemic manifestations of racism (but not isolated incidents), such that group differences were stronger among participants who scored higher on a measure of racial identity relevance. The results help illuminate the importance of epistemologies of ignorance: cultural-psychological tools that afford denial of and inaction about injustice.

  18. The end of ignorance multiplying our human potential

    CERN Document Server

    Mighton, John

    2008-01-01

    A revolutionary call for a new understanding of how people learn. The End of Ignorance conceives of a world in which no child is left behind – a world based on the assumption that each child has the potential to be successful in every subject. John Mighton argues that by recognizing the barriers that we have experienced in our own educational development, by identifying the moment that we became disenchanted with a certain subject and forever closed ourselves off to it, we will be able to eliminate these same barriers from standing in the way of our children. A passionate examination of our present education system, The End of Ignorance shows how we all can work together to reinvent the way that we are taught. John Mighton, the author of The Myth of Ability, is the founder of JUMP Math, a system of learning based on the fostering of emergent intelligence. The program has proved so successful an entire class of Grade 3 students, including so-called slow learners, scored over 90% on a Grade 6 math test. A ...

  19. Lessons in Equality: From Ignorant Schoolmaster to Chinese Aesthetics

    Directory of Open Access Journals (Sweden)

    Ernest Ženko

    2017-09-01

    Full Text Available The postponement of equality is not only a recurring topic in Jacques Rancière’s writings, but also the most defining feature of modern Chinese aesthetics. Particularly in the period after 1980’s, when the country opened its doors to Western ideas, Chinese aesthetics extensively played a subordinate role in an imbalanced knowledge transfer, in which structural inequality was only reinforced. Aesthetics in China plays an important role and is expected not only to interpret literature and art, but also to help building a harmonious society within globalized world. This is the reason why some commentators – Wang Jianjiang being one of them – point out that it is of utmost importance to eliminate this imbalance and develop proper Chinese aesthetics. Since the key issue in this development is the problem of inequality, an approach developed by Jacques Rancière, “the philosopher of equality”, is proposed. Even though Rancière wrote extensively about literature, art and aesthetics, in order to confront the problem of Chinese aesthetics, it seems that a different approach, found in his repertoire, could prove to be more fruitful. In 1987, he published a book titled The Ignorant Schoolmaster, which contributed to his ongoing philosophical emancipatory project, and focused on inequality and its conditions in the realm of education. The Ignorant Schoolmaster, nonetheless, stretches far beyond the walls of classroom or even educational system, and brings to the fore political implications that cluster around the fundamental core of Rancière's political philosophy: the definition of politics as the verification of the presupposition of the equality of intelligence. Equality cannot be postponed as a goal to be only attained in the future and, therefore, has to be considered as a premise of egalitarian politics that needs to operate as a presupposition.   Article received: May 21, 2017; Article accepted: May 28, 2017; Published online

  20. The importance of ignoring: Alpha oscillations protect selectivity.

    Science.gov (United States)

    Payne, Lisa; Sekuler, Robert

    2014-06-01

    Selective attention is often thought to entail an enhancement of some task-relevant stimulus or attribute. We discuss the perspective that ignoring irrelevant, distracting information plays a complementary role in information processing. Cortical oscillations within the alpha (8-14 Hz) frequency band have emerged as a marker of sensory suppression. This suppression is linked to selective attention for visual, auditory, somatic, and verbal stimuli. Inhibiting processing of irrelevant input makes responses more accurate and timely. It also helps protect material held in short-term memory against disruption. Furthermore, this selective process keeps irrelevant information from distorting the fidelity of memories. Memory is only as good as the perceptual representations on which it is based, and on whose maintenance it depends. Modulation of alpha oscillations can be exploited as an active, purposeful mechanism to help people pay attention and remember the things that matter.

  1. What Is Hospitality in the Academy? Epistemic Ignorance and the (Im)possible Gift

    Science.gov (United States)

    Kuokkanen, Rauna

    2008-01-01

    The academy is considered by many as the major Western institution of knowledge. This article, however, argues that the academy is characterized by prevalent "epistemic ignorance"--a concept informed by Spivak's discussion of "sanctioned ignorance." Epistemic ignorance refers to academic practices and discourses that enable the continued exclusion…

  2. Experiences of Being Ignored by Peers during Late Adolescence: Linkages to Psychological Maladjustment

    Science.gov (United States)

    Bowker, Julie C.; Adams, Ryan E.; Fredstrom, Bridget K.; Gilman, Rich

    2014-01-01

    In this study on being ignored by peers, 934 twelfth-grade students reported on their experiences of being ignored, victimized, and socially withdrawn, and completed measures of friendship and psychological adjustment (depression, self-esteem, and global satisfaction). Peer nominations of being ignored, victimized, and accepted by peers were also…

  3. Diffusion to finite-size traps

    International Nuclear Information System (INIS)

    Richards, P.M.

    1986-01-01

    The survival probability of a random-walking particle is derived for hopping in a random distribution of traps of arbitrary radius and concentration. The single-center approximation is shown to be valid for times of physical interest even when the fraction of volume occupied by traps approaches unity. The theory is based on computation of the number of different potential trap regions sampled in a random walk and is confirmed by simulations on a simple-cubic lattice

  4. Automated Traffic and the Finite Size Resonance

    Science.gov (United States)

    Veerman, J. J. P.; Stošić, B. D.; Tangerman, F. M.

    2009-10-01

    We investigate in detail what one might call the canonical (automated) traffic problem: A long string of N+1 cars (numbered from 0 to N) moves along a one-lane road "in formation" at a constant velocity and with a unit distance between successive cars. Each car monitors the relative velocity and position of only its neighboring cars. This information is then fed back to its own engine which decelerates (brakes) or accelerates according to the information it receives. The question is: What happens when due to an external influence—a traffic light turning green—the `zero'th' car (the "leader") accelerates? As a first approximation, we analyze linear(ized) equations and show that in this scenario the traffic flow has a tendency to be stop-and-go. We give approximate solutions for the global traffic as function of all the relevant parameters (the feed back parameters as well as cruise velocity and so on). We discuss general design principles for these algorithms, that is: how does the choice of parameters influence the performance.

  5. Local field in finite-size metamaterials

    DEFF Research Database (Denmark)

    Bordo, Vladimir

    2018-01-01

    The theory of the optical response of a metamaterial slab which is represented by metal nanoparticles embedded in a dielectric matrix is developed. It is demonstrated that the account of the reflections from the slab boundaries essentially modifies the local field in the slab and leads...

  6. Hooking up: Gender Differences, Evolution, and Pluralistic Ignorance

    Directory of Open Access Journals (Sweden)

    Chris Reiber

    2010-07-01

    Full Text Available “Hooking-up” – engaging in no-strings-attached sexual behaviors with uncommitted partners - has become a norm on college campuses, and raises the potential for disease, unintended pregnancy, and physical and psychological trauma. The primacy of sex in the evolutionary process suggests that predictions derived from evolutionary theory may be a useful first step toward understanding these contemporary behaviors. This study assessed the hook-up behaviors and attitudes of 507 college students. As predicted by behavioral-evolutionary theory: men were more comfortable than women with all types of sexual behaviors; women correctly attributed higher comfort levels to men, but overestimated men's actual comfort levels; and men correctly attributed lower comfort levels to women, but still overestimated women's actual comfort levels. Both genders attributed higher comfort levels to same-gendered others, reinforcing a pluralistic ignorance effect that might contribute to the high frequency of hook-up behaviors in spite of the low comfort levels reported and suggesting that hooking up may be a modern form of intrasexual competition between females for potential mates.

  7. Sarajevo: Politics and Cultures of Remembrance and Ignorance

    Directory of Open Access Journals (Sweden)

    Adla Isanović

    2017-10-01

    Full Text Available This text critically reflects on cultural events organized to mark the 100th anniversary of the start of the First World War in Sarajevo and Bosnia & Herzegovina. It elaborates on disputes which showed that culture is in the centre of identity politics and struggles (which can also take a fascist nationalist form, accept the colonizer’s perspective, etc., on how commemorations ‘swallowed’ the past and present, but primarily contextualizes, historicizes and politicizes Sarajevo 2014 and its politics of visibility. This case is approached as an example and symptomatic of the effects of the current state of capitalism, coloniality, racialization and subjugation, as central to Europe today. Article received: June 2, 2017; Article accepted: June 8, 2017; Published online: October 15, 2017; Original scholarly paper How to cite this article: Isanović, Adla. "Sarajevo: Politics and Cultures of Remembrance and Ignorance." AM Journal of Art and Media Studies 14 (2017: 133-144. doi: 10.25038/am.v0i14.199

  8. Technology trends in econometric energy models: Ignorance or information?

    International Nuclear Information System (INIS)

    Boyd, G.; Kokkelenberg, E.; State Univ., of New York, Binghamton, NY; Ross, M.; Michigan Univ., Ann Arbor, MI

    1991-01-01

    Simple time trend variables in factor demand models can be statistically powerful variables, but may tell the researcher very little. Even more complex specification of technical change, e.g. factor biased, are still the economentrician's ''measure of ignorance'' about the shifts that occur in the underlying production process. Furthermore, in periods of rapid technology change the parameters based on time trends may be too large for long run forecasting. When there is clearly identifiable engineering information about new technology adoption that changes the factor input mix, data for the technology adoption may be included in the traditional factor demand model to economically model specific factor biased technical change and econometrically test their contribution. The adoption of thermomechanical pulping (TMP) and electric are furnaces (EAF) are two electricity intensive technology trends in the Paper and Steel industries, respectively. This paper presents the results of including these variables in a tradition econometric factor demand model, which is based on the Generalized Leontief. The coefficients obtained for this ''engineering based'' technical change compares quite favorably to engineering estimates of the impact of TMP and EAF on electricity intensities, improves the estimates of the other price coefficients, and yields a more believable long run electricity forecast. 6 refs., 1 fig

  9. Neutron density decay constant in a non-multiplying lattice of finite size; Constante de decroissance de la densite neutronique dans un reseau non-multiplicateur de dimensions finies

    Energy Technology Data Exchange (ETDEWEB)

    Deniz, V C [Commissariat a l' Energie Atomique, Cadarache (France). Centre d' Etudes Nucleaires

    1965-07-01

    This report presents a general theory, using the integral transport method, for obtaining the neutron density decay constant in a finite non-multiplying lattice. The theory is applied to obtain the expression for the diffusion coefficient. The case of a homogeneous medium with 1/v absorption and of finite size in all directions is treated in detail, assuming an isotropic scattering law. The decay constant is obtained up to the B{sup 6} term. The expressions for the diffusion coefficient and for the diffusion cooling coefficient are the same as those obtained for a slab geometry by Nelkin, using the expansion in spherical harmonics of the Fourier transform in the spatial variable. Furthermore, explicit forms are obtained for the flux and the current. It is shown that the deviation of the actual flux from a Maxwellian is the flux generated in the medium, extended to infinity and deprived of its absorbing power, by various sources, each of which has a zero integral over all velocities. The study of the current permits the generalization of Fick's law. An independent integral method, valid for homogeneous media, is also presented. (author) [French] Ce rapport presente une theorie generale, par methode integrale du transport, pour determiner la constante de decroissance de la densite neutronique dans un reseau non-multiplicateur de dimensions finies. La theorie est appliquee pour obtenir l'expression du coefficient de diffusion. Le cas d'un milieu homogene avec absorption en 1/v et de dimensions finies dans toutes les directions est etudie en detail, en admettant une loi de choc isotrope. La constante de decroissance est obtenue jusqu'au terme en B{sup 6}. Les expressions pour le coefficient de diffusion et pour le coefficient de refroidissement par diffusion sont les memes que celles obtenues pour une geometrie 'plaque' par NELKIN qui utilise le developpement en harmoniques spheriques de la transformee de Fourier dans la variable d'espace. De plus, on obtient les

  10. Groebner Finite Path Algebras

    OpenAIRE

    Leamer, Micah J.

    2004-01-01

    Let K be a field and Q a finite directed multi-graph. In this paper I classify all path algebras KQ and admissible orders with the property that all of their finitely generated ideals have finite Groebner bases. MS

  11. Locally Finite Root Supersystems

    OpenAIRE

    Yousofzadeh, Malihe

    2013-01-01

    We introduce the notion of locally finite root supersystems as a generalization of both locally finite root systems and generalized root systems. We classify irreducible locally finite root supersystems.

  12. Should we ignore U-235 series contribution to dose?

    International Nuclear Information System (INIS)

    Beaugelin-Seiller, Karine; Goulet, Richard; Mihok, Steve; Beresford, Nicholas A.

    2016-01-01

    Environmental Risk Assessment (ERA) methodology for radioactive substances is an important regulatory tool for assessing the safety of licensed nuclear facilities for wildlife, and the environment as a whole. ERAs are therefore expected to be both fit for purpose and conservative. When uranium isotopes are assessed, there are many radioactive decay products which could be considered. However, risk assessors usually assume 235 U and its daughters contribute negligibly to radiological dose. The validity of this assumption has not been tested: what might the 235 U family contribution be and how does the estimate depend on the assumptions applied? In this paper we address this question by considering aquatic wildlife in Canadian lakes exposed to historic uranium mining practices. A full theoretical approach was used, in parallel to a more realistic assessment based on measurements of several elements of the U decay chains. The 235 U family contribution varied between about 4% and 75% of the total dose rate depending on the assumptions of the equilibrium state of the decay chains. Hence, ignoring the 235 U series will not result in conservative dose assessments for wildlife. These arguments provide a strong case for more in situ measurements of the important members of the 235 U chain and for its consideration in dose assessments. - Highlights: • Realistic ecological risk assessment infers a complete inventory of radionuclides. • U-235 family may not be minor when assessing total dose rates experienced by biota. • There is a need to investigate the real state of equilibrium decay of U chains. • There is a need to improve the capacity to measure all elements of the U decay chains.

  13. That Escalated Quickly—Planning to Ignore RPE Can Backfire

    Directory of Open Access Journals (Sweden)

    Maik Bieleke

    2017-09-01

    Full Text Available Ratings of perceived exertion (RPE are routinely assessed in exercise science and RPE is substantially associated with physiological criterion measures. According to the psychobiological model of endurance, RPE is a central limiting factor in performance. While RPE is known to be affected by psychological manipulations, it remains to be examined whether RPE can be self-regulated during static muscular endurance exercises to enhance performance. In this experiment, we investigate the effectiveness of the widely used and recommended self-regulation strategy of if-then planning (i.e., implementation intentions in down-regulating RPE and improving performance in a static muscular endurance task. 62 female students (age: M = 23.7 years, SD = 4.0 were randomly assigned to an implementation intention or a control condition and performed a static muscular endurance task. They held two intertwined rings as long as possible while avoiding contacts between the rings. In the implementation intention condition, participants had an if-then plan: “If the task becomes too strenuous for me, then I ignore the strain and tell myself: Keep going!” Every 25 ± 10 s participants reported their RPE along with their perceived pain. Endurance performance was measured as time to failure, along with contact errors as a measure of performance quality. No differences emerged between implementation intention and control participants regarding time to failure and performance quality. However, mixed-effects model analyses revealed a significant Time-to-Failure × Condition interaction for RPE. Compared to the control condition, participants in the implementation intention condition reported substantially greater increases in RPE during the second half of the task and reached higher total values of RPE before task termination. A similar but weaker pattern evinced for perceived pain. Our results demonstrate that RPE during an endurance task can be self-regulated with if

  14. The Mathematical Miseducation of America's Youth: Ignoring Research and Scientific Study in Education.

    Science.gov (United States)

    Battista, Michael T.

    1999-01-01

    Because traditional instruction ignores students' personal construction of mathematical meaning, mathematical thought development is not properly nurtured. Several issues must be addressed, including adults' ignorance of math- and student-learning processes, identification of math-education research specialists, the myth of coverage, testing…

  15. Persistence of Memory for Ignored Lists of Digits: Areas of Developmental Constancy and Change.

    Science.gov (United States)

    Cowan, Nelson; Nugent, Lara D.; Elliott, Emily M.; Saults, J. Scott

    2000-01-01

    Examined persistence of sensory memory by studying developmental differences in recall of attended and ignored lists of digits for second-graders, fifth-graders, and adults. Found developmental increase in the persistence of memory only for the final item in an ignored list, which is the item for which sensory memory is thought to be the most…

  16. Modelling non-ignorable missing data mechanisms with item response theory models

    NARCIS (Netherlands)

    Holman, Rebecca; Glas, Cornelis A.W.

    2005-01-01

    A model-based procedure for assessing the extent to which missing data can be ignored and handling non-ignorable missing data is presented. The procedure is based on item response theory modelling. As an example, the approach is worked out in detail in conjunction with item response data modelled

  17. Modelling non-ignorable missing-data mechanisms with item response theory models

    NARCIS (Netherlands)

    Holman, Rebecca; Glas, Cees A. W.

    2005-01-01

    A model-based procedure for assessing the extent to which missing data can be ignored and handling non-ignorable missing data is presented. The procedure is based on item response theory modelling. As an example, the approach is worked out in detail in conjunction with item response data modelled

  18. Is There Such a Thing as 'White Ignorance' in British Education?

    Science.gov (United States)

    Bain, Zara

    2018-01-01

    I argue that political philosopher Charles W. Mills' twin concepts of 'the epistemology of ignorance' and 'white ignorance' are useful tools for thinking through racial injustice in the British education system. While anti-racist work in British education has a long history, racism persists in British primary, secondary and tertiary education. For…

  19. The concept of ignorance in a risk assessment and risk management context

    International Nuclear Information System (INIS)

    Aven, T.; Steen, R.

    2010-01-01

    There are many definitions of ignorance in the context of risk assessment and risk management. Most refer to situations in which there are lack of knowledge, poor basis for probability assignments and possible outcomes not (fully) known. The purpose of this paper is to discuss the ignorance concept in this setting. Based on a set of risk and uncertainty features, we establish conceptual structures characterising the level of ignorance. These features include the definition of chances (relative frequency-interpreted probabilities) and the existence of scientific uncertainties. Based on these structures, we suggest a definition of ignorance linked to scientific uncertainties, i.e. the lack of understanding of how consequences of the activity are influenced by the underlying factors. In this way, ignorance can be viewed as a condition for applying the precautionary principle. The discussion is also linked to the use and boundaries of risk assessments in the case of large uncertainties, and the methods for classifying risk and uncertainty problems.

  20. A finite landscape?

    International Nuclear Information System (INIS)

    Acharya, B.S.; Douglas, M.R.

    2006-06-01

    We present evidence that the number of string/M theory vacua consistent with experiments is finite. We do this both by explicit analysis of infinite sequences of vacua and by applying various mathematical finiteness theorems. (author)

  1. Nilpotent -local finite groups

    Science.gov (United States)

    Cantarero, José; Scherer, Jérôme; Viruel, Antonio

    2014-10-01

    We provide characterizations of -nilpotency for fusion systems and -local finite groups that are inspired by known result for finite groups. In particular, we generalize criteria by Atiyah, Brunetti, Frobenius, Quillen, Stammbach and Tate.

  2. Basic Finite Element Method

    International Nuclear Information System (INIS)

    Lee, Byeong Hae

    1992-02-01

    This book gives descriptions of basic finite element method, which includes basic finite element method and data, black box, writing of data, definition of VECTOR, definition of matrix, matrix and multiplication of matrix, addition of matrix, and unit matrix, conception of hardness matrix like spring power and displacement, governed equation of an elastic body, finite element method, Fortran method and programming such as composition of computer, order of programming and data card and Fortran card, finite element program and application of nonelastic problem.

  3. Composite Finite Sums

    KAUST Repository

    Alabdulmohsin, Ibrahim M.

    2018-01-01

    In this chapter, we extend the previous results of Chap. 2 to the more general case of composite finite sums. We describe what composite finite sums are and how their analysis can be reduced to the analysis of simple finite sums using the chain rule. We apply these techniques, next, on numerical integration and on some identities of Ramanujan.

  4. Composite Finite Sums

    KAUST Repository

    Alabdulmohsin, Ibrahim M.

    2018-03-07

    In this chapter, we extend the previous results of Chap. 2 to the more general case of composite finite sums. We describe what composite finite sums are and how their analysis can be reduced to the analysis of simple finite sums using the chain rule. We apply these techniques, next, on numerical integration and on some identities of Ramanujan.

  5. Ignoring imperfect detection in biological surveys is dangerous: a response to 'fitting and interpreting occupancy models'.

    Directory of Open Access Journals (Sweden)

    Gurutzeta Guillera-Arroita

    Full Text Available In a recent paper, Welsh, Lindenmayer and Donnelly (WLD question the usefulness of models that estimate species occupancy while accounting for detectability. WLD claim that these models are difficult to fit and argue that disregarding detectability can be better than trying to adjust for it. We think that this conclusion and subsequent recommendations are not well founded and may negatively impact the quality of statistical inference in ecology and related management decisions. Here we respond to WLD's claims, evaluating in detail their arguments, using simulations and/or theory to support our points. In particular, WLD argue that both disregarding and accounting for imperfect detection lead to the same estimator performance regardless of sample size when detectability is a function of abundance. We show that this, the key result of their paper, only holds for cases of extreme heterogeneity like the single scenario they considered. Our results illustrate the dangers of disregarding imperfect detection. When ignored, occupancy and detection are confounded: the same naïve occupancy estimates can be obtained for very different true levels of occupancy so the size of the bias is unknowable. Hierarchical occupancy models separate occupancy and detection, and imprecise estimates simply indicate that more data are required for robust inference about the system in question. As for any statistical method, when underlying assumptions of simple hierarchical models are violated, their reliability is reduced. Resorting in those instances where hierarchical occupancy models do no perform well to the naïve occupancy estimator does not provide a satisfactory solution. The aim should instead be to achieve better estimation, by minimizing the effect of these issues during design, data collection and analysis, ensuring that the right amount of data is collected and model assumptions are met, considering model extensions where appropriate.

  6. Ignoring the Obvious: Combined Arms and Fire and Maneuver Tactics Prior to World War I

    National Research Council Canada - National Science Library

    Bruno, Thomas

    2002-01-01

    The armies that entered WWI ignored many pre-war lessons though WWI armies later developed revolutionary tactical-level advances, scholars claim that this tactical evolution followed an earlier period...

  7. Passionate ignorance

    DEFF Research Database (Denmark)

    Hyldgaard, Kirsten

    2006-01-01

    Psychoanalysis has nothing to say about education. Psychoanalysis has something to say about pedagogy; psychoanalysis has pedagogical-philosophical implications. Pedagogy, in distinction to education, addresses the question of the subject. This implies that pedagogical theory is and cannot be a s...

  8. Fatal ignorance.

    Science.gov (United States)

    1996-01-01

    The Rajiv Gandhi Foundation (RGF), together with the AIMS-affiliated NGO AIDS Cell, Delhi, held a workshop as part of an effort to raise a 90-doctor RGF AIDS workforce which will work together with nongovernmental organizations on AIDS prevention, control, and management. 25 general practitioners registered with the Indian Medical Council, who have practiced medicine in Delhi for the past 10-20 years, responded to a pre-program questionnaire on HIV-related knowledge and attitudes. 6 out of the 25 physicians did not know what the acronym AIDS stands for, extremely low awareness of the clinical aspects of the disease was revealed, 9 believed in the conspiracy theory of HIV development and accidental release by the US Central Intelligence Agency, 8 believed that AIDS is a problem of only the promiscuous, 18 did not know that the mode of HIV transmission is similar to that of the hepatitis B virus, 12 were unaware that HIV-infected people will test HIV-seronegative during the first three months after initial infection and that they will develop symptoms of full-blown AIDS only after 10 years, 10 did not know the name of even one drug used to treat the disease, 3 believed aspirin to be an effective drug against AIDS, many believed fantastic theories about the modes of HIV transmission, and many were acutely homophobic. Efforts were made to clear misconceptions about HIV during the workshop. It is hoped that participating doctors' attitudes about AIDS and the high-risk groups affected by it were also improved.

  9. On the practice of ignoring center-patient interactions in evaluating hospital performance.

    Science.gov (United States)

    Varewyck, Machteld; Vansteelandt, Stijn; Eriksson, Marie; Goetghebeur, Els

    2016-01-30

    We evaluate the performance of medical centers based on a continuous or binary patient outcome (e.g., 30-day mortality). Common practice adjusts for differences in patient mix through outcome regression models, which include patient-specific baseline covariates (e.g., age and disease stage) besides center effects. Because a large number of centers may need to be evaluated, the typical model postulates that the effect of a center on outcome is constant over patient characteristics. This may be violated, for example, when some centers are specialized in children or geriatric patients. Including interactions between certain patient characteristics and the many fixed center effects in the model increases the risk for overfitting, however, and could imply a loss of power for detecting centers with deviating mortality. Therefore, we assess how the common practice of ignoring such interactions impacts the bias and precision of directly and indirectly standardized risks. The reassuring conclusion is that the common practice of working with the main effects of a center has minor impact on hospital evaluation, unless some centers actually perform substantially better on a specific group of patients and there is strong confounding through the corresponding patient characteristic. The bias is then driven by an interplay of the relative center size, the overlap between covariate distributions, and the magnitude of the interaction effect. Interestingly, the bias on indirectly standardized risks is smaller than on directly standardized risks. We illustrate our findings by simulation and in an analysis of 30-day mortality on Riksstroke. © 2015 The Authors. Statistics in Medicine published by John Wiley & Sons Ltd.

  10. Fractional finite Fourier transform.

    Science.gov (United States)

    Khare, Kedar; George, Nicholas

    2004-07-01

    We show that a fractional version of the finite Fourier transform may be defined by using prolate spheroidal wave functions of order zero. The transform is linear and additive in its index and asymptotically goes over to Namias's definition of the fractional Fourier transform. As a special case of this definition, it is shown that the finite Fourier transform may be inverted by using information over a finite range of frequencies in Fourier space, the inversion being sensitive to noise. Numerical illustrations for both forward (fractional) and inverse finite transforms are provided.

  11. Finite quantum field theories

    International Nuclear Information System (INIS)

    Lucha, W.; Neufeld, H.

    1986-01-01

    We investigate the relation between finiteness of a four-dimensional quantum field theory and global supersymmetry. To this end we consider the most general quantum field theory and analyse the finiteness conditions resulting from the requirement of the absence of divergent contributions to the renormalizations of the parameters of the theory. In addition to the gauge bosons, both fermions and scalar bosons turn out to be a necessary ingredient in a non-trivial finite gauge theory. In all cases discussed, the supersymmetric theory restricted by two well-known constraints on the dimensionless couplings proves to be the unique solution of the finiteness conditions. (Author)

  12. Mid-adolescent neurocognitive development of ignoring and attending emotional stimuli

    Directory of Open Access Journals (Sweden)

    Nora C. Vetter

    2015-08-01

    Full Text Available Appropriate reactions toward emotional stimuli depend on the distribution of prefrontal attentional resources. In mid-adolescence, prefrontal top-down control systems are less engaged, while subcortical bottom-up emotional systems are more engaged. We used functional magnetic resonance imaging to follow the neural development of attentional distribution, i.e. attending versus ignoring emotional stimuli, in adolescence. 144 healthy adolescents were studied longitudinally at age 14 and 16 while performing a perceptual discrimination task. Participants viewed two pairs of stimuli – one emotional, one abstract – and reported on one pair whether the items were the same or different, while ignoring the other pair. Hence, two experimental conditions were created: “attending emotion/ignoring abstract” and “ignoring emotion/attending abstract”. Emotional valence varied between negative, positive, and neutral. Across conditions, reaction times and error rates decreased and activation in the anterior cingulate and inferior frontal gyrus increased from age 14 to 16. In contrast, subcortical regions showed no developmental effect. Activation of the anterior insula increased across ages for attending positive and ignoring negative emotions. Results suggest an ongoing development of prefrontal top-down resources elicited by emotional attention from age 14 to 16 while activity of subcortical regions representing bottom-up processing remains stable.

  13. Investigating Deviance Distraction and the Impact of the Modality of the To-Be-Ignored Stimuli.

    Science.gov (United States)

    Marsja, Erik; Neely, Gregory; Ljungberg, Jessica K

    2018-03-01

    It has been suggested that deviance distraction is caused by unexpected sensory events in the to-be-ignored stimuli violating the cognitive system's predictions of incoming stimuli. The majority of research has used methods where the to-be-ignored expected (standards) and the unexpected (deviants) stimuli are presented within the same modality. Less is known about the behavioral impact of deviance distraction when the to-be-ignored stimuli are presented in different modalities (e.g., standard and deviants presented in different modalities). In three experiments using cross-modal oddball tasks with mixed-modality to-be-ignored stimuli, we examined the distractive role of unexpected auditory deviants presented in a continuous stream of expected standard vibrations. The results showed that deviance distraction seems to be dependent upon the to-be-ignored stimuli being presented within the same modality, and that the simplest omission of something expected; in this case, a standard vibration may be enough to capture attention and distract performance.

  14. Non-ignorable missingness item response theory models for choice effects in examinee-selected items.

    Science.gov (United States)

    Liu, Chen-Wei; Wang, Wen-Chung

    2017-11-01

    Examinee-selected item (ESI) design, in which examinees are required to respond to a fixed number of items in a given set, always yields incomplete data (i.e., when only the selected items are answered, data are missing for the others) that are likely non-ignorable in likelihood inference. Standard item response theory (IRT) models become infeasible when ESI data are missing not at random (MNAR). To solve this problem, the authors propose a two-dimensional IRT model that posits one unidimensional IRT model for observed data and another for nominal selection patterns. The two latent variables are assumed to follow a bivariate normal distribution. In this study, the mirt freeware package was adopted to estimate parameters. The authors conduct an experiment to demonstrate that ESI data are often non-ignorable and to determine how to apply the new model to the data collected. Two follow-up simulation studies are conducted to assess the parameter recovery of the new model and the consequences for parameter estimation of ignoring MNAR data. The results of the two simulation studies indicate good parameter recovery of the new model and poor parameter recovery when non-ignorable missing data were mistakenly treated as ignorable. © 2017 The British Psychological Society.

  15. Finite Boltzmann schemes

    NARCIS (Netherlands)

    Sman, van der R.G.M.

    2006-01-01

    In the special case of relaxation parameter = 1 lattice Boltzmann schemes for (convection) diffusion and fluid flow are equivalent to finite difference/volume (FD) schemes, and are thus coined finite Boltzmann (FB) schemes. We show that the equivalence is inherent to the homology of the

  16. Designs and finite geometries

    CERN Document Server

    1996-01-01

    Designs and Finite Geometries brings together in one place important contributions and up-to-date research results in this important area of mathematics. Designs and Finite Geometries serves as an excellent reference, providing insight into some of the most important research issues in the field.

  17. Supersymmetric theories and finiteness

    International Nuclear Information System (INIS)

    Helayel-Neto, J.A.

    1989-01-01

    We attempt here to present a short survey of the all-order finite Lagrangian field theories known at present in four-and two-dimensional space-times. The question of the possible relevance of these ultraviolet finite models in the formulation of consistent unified frameworks for the fundamental forces is also addressed to. (author)

  18. Simple Finite Sums

    KAUST Repository

    Alabdulmohsin, Ibrahim M.

    2018-03-07

    We will begin our treatment of summability calculus by analyzing what will be referred to, throughout this book, as simple finite sums. Even though the results of this chapter are particular cases of the more general results presented in later chapters, they are important to start with for a few reasons. First, this chapter serves as an excellent introduction to what summability calculus can markedly accomplish. Second, simple finite sums are encountered more often and, hence, they deserve special treatment. Third, the results presented in this chapter for simple finite sums will, themselves, be used as building blocks for deriving the most general results in subsequent chapters. Among others, we establish that fractional finite sums are well-defined mathematical objects and show how various identities related to the Euler constant as well as the Riemann zeta function can actually be derived in an elementary manner using fractional finite sums.

  19. Simple Finite Sums

    KAUST Repository

    Alabdulmohsin, Ibrahim M.

    2018-01-01

    We will begin our treatment of summability calculus by analyzing what will be referred to, throughout this book, as simple finite sums. Even though the results of this chapter are particular cases of the more general results presented in later chapters, they are important to start with for a few reasons. First, this chapter serves as an excellent introduction to what summability calculus can markedly accomplish. Second, simple finite sums are encountered more often and, hence, they deserve special treatment. Third, the results presented in this chapter for simple finite sums will, themselves, be used as building blocks for deriving the most general results in subsequent chapters. Among others, we establish that fractional finite sums are well-defined mathematical objects and show how various identities related to the Euler constant as well as the Riemann zeta function can actually be derived in an elementary manner using fractional finite sums.

  20. Finite fields and applications

    CERN Document Server

    Mullen, Gary L

    2007-01-01

    This book provides a brief and accessible introduction to the theory of finite fields and to some of their many fascinating and practical applications. The first chapter is devoted to the theory of finite fields. After covering their construction and elementary properties, the authors discuss the trace and norm functions, bases for finite fields, and properties of polynomials over finite fields. Each of the remaining chapters details applications. Chapter 2 deals with combinatorial topics such as the construction of sets of orthogonal latin squares, affine and projective planes, block designs, and Hadamard matrices. Chapters 3 and 4 provide a number of constructions and basic properties of error-correcting codes and cryptographic systems using finite fields. Each chapter includes a set of exercises of varying levels of difficulty which help to further explain and motivate the material. Appendix A provides a brief review of the basic number theory and abstract algebra used in the text, as well as exercises rel...

  1. Chiral crossover transition in a finite volume

    Science.gov (United States)

    Shi, Chao; Jia, Wenbao; Sun, An; Zhang, Liping; Zong, Hongshi

    2018-02-01

    Finite volume effects on the chiral crossover transition of strong interactions at finite temperature are studied by solving the quark gap equation within a cubic volume of finite size L. With the anti-periodic boundary condition, our calculation shows the chiral quark condensate, which characterizes the strength of dynamical chiral symmetry breaking, decreases as L decreases below 2.5 fm. We further study the finite volume effects on the pseudo-transition temperature {T}{{c}} of the crossover, showing a significant decrease in {T}{{c}} as L decreases below 3 fm. Supported by National Natural Science Foundation of China (11475085, 11535005, 11690030, 51405027), the Fundamental Research Funds for the Central Universities (020414380074), China Postdoctoral Science Foundation (2016M591808) and Open Research Foundation of State Key Lab. of Digital Manufacturing Equipment & Technology in Huazhong University of Science & Technology (DMETKF2015015)

  2. Ignorance Is Bliss, But for Whom? The Persistent Effect of Good Will on Cooperation

    Directory of Open Access Journals (Sweden)

    Mike Farjam

    2016-10-01

    Full Text Available Who benefits from the ignorance of others? We address this question from the point of view of a policy maker who can induce some ignorance into a system of agents competing for resources. Evolutionary game theory shows that when unconditional cooperators or ignorant agents compete with defectors in two-strategy settings, unconditional cooperators get exploited and are rendered extinct. In contrast, conditional cooperators, by utilizing some kind of reciprocity, are able to survive and sustain cooperation when competing with defectors. We study how cooperation thrives in a three-strategy setting where there are unconditional cooperators, conditional cooperators and defectors. By means of simulation on various kinds of graphs, we show that conditional cooperators benefit from the existence of unconditional cooperators in the majority of cases. However, in worlds that make cooperation hard to evolve, defectors benefit.

  3. Ignoring correlation in uncertainty and sensitivity analysis in life cycle assessment: what is the risk?

    Energy Technology Data Exchange (ETDEWEB)

    Groen, E.A., E-mail: Evelyne.Groen@gmail.com [Wageningen University, P.O. Box 338, Wageningen 6700 AH (Netherlands); Heijungs, R. [Vrije Universiteit Amsterdam, De Boelelaan 1105, Amsterdam 1081 HV (Netherlands); Leiden University, Einsteinweg 2, Leiden 2333 CC (Netherlands)

    2017-01-15

    Life cycle assessment (LCA) is an established tool to quantify the environmental impact of a product. A good assessment of uncertainty is important for making well-informed decisions in comparative LCA, as well as for correctly prioritising data collection efforts. Under- or overestimation of output uncertainty (e.g. output variance) will lead to incorrect decisions in such matters. The presence of correlations between input parameters during uncertainty propagation, can increase or decrease the the output variance. However, most LCA studies that include uncertainty analysis, ignore correlations between input parameters during uncertainty propagation, which may lead to incorrect conclusions. Two approaches to include correlations between input parameters during uncertainty propagation and global sensitivity analysis were studied: an analytical approach and a sampling approach. The use of both approaches is illustrated for an artificial case study of electricity production. Results demonstrate that both approaches yield approximately the same output variance and sensitivity indices for this specific case study. Furthermore, we demonstrate that the analytical approach can be used to quantify the risk of ignoring correlations between input parameters during uncertainty propagation in LCA. We demonstrate that: (1) we can predict if including correlations among input parameters in uncertainty propagation will increase or decrease output variance; (2) we can quantify the risk of ignoring correlations on the output variance and the global sensitivity indices. Moreover, this procedure requires only little data. - Highlights: • Ignoring correlation leads to under- or overestimation of the output variance. • We demonstrated that the risk of ignoring correlation can be quantified. • The procedure proposed is generally applicable in life cycle assessment. • In some cases, ignoring correlation has a minimal effect on decision-making tools.

  4. Flow Applications of the Least Squares Finite Element Method

    Science.gov (United States)

    Jiang, Bo-Nan

    1998-01-01

    The main thrust of the effort has been towards the development, analysis and implementation of the least-squares finite element method (LSFEM) for fluid dynamics and electromagnetics applications. In the past year, there were four major accomplishments: 1) special treatments in computational fluid dynamics and computational electromagnetics, such as upwinding, numerical dissipation, staggered grid, non-equal order elements, operator splitting and preconditioning, edge elements, and vector potential are unnecessary; 2) the analysis of the LSFEM for most partial differential equations can be based on the bounded inverse theorem; 3) the finite difference and finite volume algorithms solve only two Maxwell equations and ignore the divergence equations; and 4) the first numerical simulation of three-dimensional Marangoni-Benard convection was performed using the LSFEM.

  5. Roles of dark energy perturbations in dynamical dark energy models: can we ignore them?

    Science.gov (United States)

    Park, Chan-Gyung; Hwang, Jai-chan; Lee, Jae-heon; Noh, Hyerim

    2009-10-09

    We show the importance of properly including the perturbations of the dark energy component in the dynamical dark energy models based on a scalar field and modified gravity theories in order to meet with present and future observational precisions. Based on a simple scaling scalar field dark energy model, we show that observationally distinguishable substantial differences appear by ignoring the dark energy perturbation. By ignoring it the perturbed system of equations becomes inconsistent and deviations in (gauge-invariant) power spectra depend on the gauge choice.

  6. Finite elements and approximation

    CERN Document Server

    Zienkiewicz, O C

    2006-01-01

    A powerful tool for the approximate solution of differential equations, the finite element is extensively used in industry and research. This book offers students of engineering and physics a comprehensive view of the principles involved, with numerous illustrative examples and exercises.Starting with continuum boundary value problems and the need for numerical discretization, the text examines finite difference methods, weighted residual methods in the context of continuous trial functions, and piecewise defined trial functions and the finite element method. Additional topics include higher o

  7. Stretching and jamming of finite automata

    NARCIS (Netherlands)

    Beijer, de N.; Kourie, D.G.; Watson, B.W.; Cleophas, L.G.W.A.; Watson, B.W.

    2004-01-01

    In this paper we present two transformations on automata, called stretching and jamming. These transformations will, under certain conditions, reduce the size of the transition table, and under other conditions reduce the string processing time. Given a finite automaton, we can stretch it by

  8. Forgotten and Ignored: Special Education in First Nations Schools in Canada

    Science.gov (United States)

    Phillips, Ron

    2010-01-01

    Usually reviews of special education in Canada describe the special education programs, services, policies, and legislation that are provided by the provinces and territories. The reviews consistently ignore the special education programs, services, policies, and legislation that are provided by federal government of Canada. The federal government…

  9. The Capital Costs Conundrum: Why Are Capital Costs Ignored and What Are the Consequences?

    Science.gov (United States)

    Winston, Gordon C.

    1993-01-01

    Colleges and universities historically have ignored the capital costs associated with institutional administration in their estimates of overall and per-student costs. This neglect leads to distortion of data, misunderstandings, and uninformed decision making. The real costs should be recognized in institutional accounting. (MSE)

  10. Monitoring your friends, not your foes: strategic ignorance and the delegation of real authority

    NARCIS (Netherlands)

    Dominguez-Martinez, S.; Sloof, R.; von Siemens, F.

    2010-01-01

    In this laboratory experiment we study the use of strategic ignorance to delegate real authority within a firm. A worker can gather information on investment projects, while a manager makes the implementation decision. The manager can monitor the worker. This allows her to better exploit the

  11. Monitored by your friends, not your foes: Strategic ignorance and the delegation of real authority

    NARCIS (Netherlands)

    Dominguez-Martinez, S.; Sloof, R.; von Siemens, F.

    2012-01-01

    In this laboratory experiment we study the use of strategic ignorance to delegate real authority within a firm. A worker can gather information on investment projects, while a manager makes the implementation decision. The manager can monitor the worker. This allows her to exploit any information

  12. Mathematical Practice as Sculpture of Utopia: Models, Ignorance, and the Emancipated Spectator

    Science.gov (United States)

    Appelbaum, Peter

    2012-01-01

    This article uses Ranciere's notion of the ignorant schoolmaster and McElheny's differentiation of artist's models from those of the architect and scientist to propose the reconceptualization of mathematics education as the support of emancipated spectators and sculptors of utopia.

  13. The effects of systemic crises when investors can be crisis ignorant

    NARCIS (Netherlands)

    H.J.W.G. Kole (Erik); C.G. Koedijk (Kees); M.J.C.M. Verbeek (Marno)

    2004-01-01

    textabstractSystemic crises can largely affect asset allocations due to the rapid deterioration of the risk-return trade-off. We investigate the effects of systemic crises, interpreted as global simultaneous shocks to financial markets, by introducing an investor adopting a crisis ignorant or crisis

  14. Geographies of knowing, geographies of ignorance: jumping scale in Southeast Asia

    NARCIS (Netherlands)

    van Schendel, W.

    2002-01-01

    'Area studies' use a geographical metaphor to visualise and naturalise particular social spaces as well as a particular scale of analysis. They produce specific geographies of knowing but also create geographies of ignorance. Taking Southeast Asia as an example, in this paper I explore how areas are

  15. The Trust Game Behind the Veil of Ignorance : A Note on Gender Differences

    NARCIS (Netherlands)

    Vyrastekova, J.; Onderstal, A.M.

    2005-01-01

    We analyse gender differences in the trust game in a "behind the veil of ignorance" design.This method yields strategies that are consistent with actions observed in the classical trust game experiments.We observe that, on averge, men and women do not differ in "trust", and that women are slightly

  16. The trust game behind the veil of ignorance: A note on gender differences

    NARCIS (Netherlands)

    Vyrastekova, J.; Onderstal, S.

    2008-01-01

    We analyze gender differences in the trust game in a "behind the veil of ignorance" design. This method yields strategies that are consistent with actions observed in the classical trust game experiments. We observe that, on average, men and women do not differ in "trust", and that women are

  17. The Ignorant Facilitator: Education, Politics and Theatre in Co-Communities

    Science.gov (United States)

    Lev-Aladgem, Shulamith

    2015-01-01

    This article discusses the book "The Ignorant Schoolmaster: Five Lessons in Intellectual Emancipation" by the French philosopher, Jacques Rancière. Its intention is to study the potential contribution of this text to the discourse of applied theatre (theatre in co-communities) in general, and the role of the facilitator in particular. It…

  18. Ignoring Memory Hints: The Stubborn Influence of Environmental Cues on Recognition Memory

    Science.gov (United States)

    Selmeczy, Diana; Dobbins, Ian G.

    2017-01-01

    Recognition judgments can benefit from the use of environmental cues that signal the general likelihood of encountering familiar versus unfamiliar stimuli. While incorporating such cues is often adaptive, there are circumstances (e.g., eyewitness testimony) in which observers should fully ignore environmental cues in order to preserve memory…

  19. Uncertain Climate Forecasts From Multimodel Ensembles: When to Use Them and When to Ignore Them

    OpenAIRE

    Jewson, Stephen; Rowlands, Dan

    2010-01-01

    Uncertainty around multimodel ensemble forecasts of changes in future climate reduces the accuracy of those forecasts. For very uncertain forecasts this effect may mean that the forecasts should not be used. We investigate the use of the well-known Bayesian Information Criterion (BIC) to make the decision as to whether a forecast should be used or ignored.

  20. Inattentional blindness for ignored words: comparison of explicit and implicit memory tasks.

    Science.gov (United States)

    Butler, Beverly C; Klein, Raymond

    2009-09-01

    Inattentional blindness is described as the failure to perceive a supra-threshold stimulus when attention is directed away from that stimulus. Based on performance on an explicit recognition memory test and concurrent functional imaging data Rees, Russell, Frith, and Driver [Rees, G., Russell, C., Frith, C. D., & Driver, J. (1999). Inattentional blindness versus inattentional amnesia for fixated but ignored words. Science, 286, 2504-2507] reported inattentional blindness for word stimuli that were fixated but ignored. The present study examined both explicit and implicit memory for fixated but ignored words using a selective-attention task in which overlapping picture/word stimuli were presented at fixation. No explicit awareness of the unattended words was apparent on a recognition memory test. Analysis of an implicit memory task, however, indicated that unattended words were perceived at a perceptual level. Thus, the selective-attention task did not result in perfect filtering as suggested by Rees et al. While there was no evidence of conscious perception, subjects were not blind to the implicit perceptual properties of fixated but ignored words.

  1. Finite Amplitude Ocean Waves

    Indian Academy of Sciences (India)

    IAS Admin

    wavelength, they are called shallow water waves. In the ... Deep and intermediate water waves are dispersive as the velocity of these depends on wavelength. This is not the ..... generation processes, the finite amplitude wave theories are very ...

  2. Finite Discrete Gabor Analysis

    DEFF Research Database (Denmark)

    Søndergaard, Peter Lempel

    2007-01-01

    frequency bands at certain times. Gabor theory can be formulated for both functions on the real line and for discrete signals of finite length. The two theories are largely the same because many aspects come from the same underlying theory of locally compact Abelian groups. The two types of Gabor systems...... can also be related by sampling and periodization. This thesis extends on this theory by showing new results for window construction. It also provides a discussion of the problems associated to discrete Gabor bases. The sampling and periodization connection is handy because it allows Gabor systems...... on the real line to be well approximated by finite and discrete Gabor frames. This method of approximation is especially attractive because efficient numerical methods exists for doing computations with finite, discrete Gabor systems. This thesis presents new algorithms for the efficient computation of finite...

  3. Supersymmetry at finite temperature

    International Nuclear Information System (INIS)

    Clark, T.E.; Love, S.T.

    1983-01-01

    Finite-temperature supersymmetry (SUSY) is characterized by unbroken Ward identities for SUSY variations of ensemble averages of Klein-operator inserted imaginary time-ordered products of fields. Path-integral representations of these products are defined and the Feynman rules in superspace are given. The finite-temperature no-renormalization theorem is derived. Spontaneously broken SUSY at zero temperature is shown not to be restored at high temperature. (orig.)

  4. Olber's Paradox Revisited in a Static and Finite Universe

    Science.gov (United States)

    Couture, Gilles

    2012-01-01

    Building a Universe populated by stars identical to our Sun and taking into consideration the wave-particle duality of light, the biological limits of the human eye, the finite size of stars and the finiteness of our Universe, we conclude that the sky could very well be dark at night. Besides the human eye, the dominant parameter is the finite…

  5. Sample size methodology

    CERN Document Server

    Desu, M M

    2012-01-01

    One of the most important problems in designing an experiment or a survey is sample size determination and this book presents the currently available methodology. It includes both random sampling from standard probability distributions and from finite populations. Also discussed is sample size determination for estimating parameters in a Bayesian setting by considering the posterior distribution of the parameter and specifying the necessary requirements. The determination of the sample size is considered for ranking and selection problems as well as for the design of clinical trials. Appropria

  6. Double jeopardy, the equal value of lives and the veil of ignorance: a rejoinder to Harris.

    Science.gov (United States)

    McKie, J; Kuhse, H; Richardson, J; Singer, P

    1996-08-01

    Harris levels two main criticisms against our original defence of QALYs (Quality Adjusted Life Years). First, he rejects the assumption implicit in the QALY approach that not all lives are of equal value. Second, he rejects our appeal to Rawls's veil of ignorance test in support of the QALY method. In the present article we defend QALYs against Harris's criticisms. We argue that some of the conclusions Harris draws from our view that resources should be allocated on the basis of potential improvements in quality of life and quantity of life are erroneous, and that others lack the moral implications Harris claims for them. On the other hand, we defend our claim that a rational egoist, behind a veil of ignorance, could consistently choose to allocate life-saving resources in accordance with the QALY method, despite Harris's claim that a rational egoist would allocate randomly if there is no better than a 50% chance of being the recipient.

  7. Crimes commited by indigeno us people in ignorance of the law

    Directory of Open Access Journals (Sweden)

    Diego Fernando Chimbo Villacorte

    2017-07-01

    Full Text Available This analysis focuses specifically When the Indian commits crimes in ignorance of the law, not only because it ignores absolutely the unlawfulness of their conduct but when he believes he is acting in strict accordance with their beliefs and ancestral customs which –in squabble some cases– with positive law. Likewise the impossibility of imposing a penalty –when the offense is committed outside the community– or indigenous purification –when it marks an act that disturbs social peace within the indigenous– community is committed but mainly focuses on the impossibility to impose a security measure when it has committed a crime outside their community, because doing so is as unimpeachable and returns to his community, generating a discriminating treatment that prevents the culturally different self-determination.

  8. Finite-dimensional calculus

    International Nuclear Information System (INIS)

    Feinsilver, Philip; Schott, Rene

    2009-01-01

    We discuss topics related to finite-dimensional calculus in the context of finite-dimensional quantum mechanics. The truncated Heisenberg-Weyl algebra is called a TAA algebra after Tekin, Aydin and Arik who formulated it in terms of orthofermions. It is shown how to use a matrix approach to implement analytic representations of the Heisenberg-Weyl algebra in univariate and multivariate settings. We provide examples for the univariate case. Krawtchouk polynomials are presented in detail, including a review of Krawtchouk polynomials that illustrates some curious properties of the Heisenberg-Weyl algebra, as well as presenting an approach to computing Krawtchouk expansions. From a mathematical perspective, we are providing indications as to how to implement infinite terms Rota's 'finite operator calculus'.

  9. The Insider Threat to Cybersecurity: How Group Process and Ignorance Affect Analyst Accuracy and Promptitude

    Science.gov (United States)

    2017-09-01

    McCarthy, J. (1980). Circumscription - A Form of Nonmonotonic Reasoning. Artificial Intelligence , 13, 27–39. McClure, S., Scambray, J., & Kurtz, G. (2012...THREAT TO CYBERSECURITY : HOW GROUP PROCESS AND IGNORANCE AFFECT ANALYST ACCURACY AND PROMPTITUDE by Ryan F. Kelly September 2017...September 2017 3. REPORT TYPE AND DATES COVERED Dissertation 4. TITLE AND SUBTITLE THE INSIDER THREAT TO CYBERSECURITY : HOW GROUP PROCESS AND

  10. Geographies of knowing, geographies of ignorance: jumping scale in Southeast Asia

    OpenAIRE

    van Schendel, W.

    2002-01-01

    'Area studies' use a geographical metaphor to visualise and naturalise particular social spaces as well as a particular scale of analysis. They produce specific geographies of knowing but also create geographies of ignorance. Taking Southeast Asia as an example, in this paper I explore how areas are imagined and how area knowledge is structured to construct area 'heartlands' as well as area `borderlands'. This is illustrated by considering a large region of Asia (here named Zomiatf) that did ...

  11. Early humans' egalitarian politics: runaway synergistic competition under an adapted veil of ignorance.

    Science.gov (United States)

    Harvey, Marc

    2014-09-01

    This paper proposes a model of human uniqueness based on an unusual distinction between two contrasted kinds of political competition and political status: (1) antagonistic competition, in quest of dominance (antagonistic status), a zero-sum, self-limiting game whose stake--who takes what, when, how--summarizes a classical definition of politics (Lasswell 1936), and (2) synergistic competition, in quest of merit (synergistic status), a positive-sum, self-reinforcing game whose stake becomes "who brings what to a team's common good." In this view, Rawls's (1971) famous virtual "veil of ignorance" mainly conceals politics' antagonistic stakes so as to devise the principles of a just, egalitarian society, yet without providing any means to enforce these ideals (Sen 2009). Instead, this paper proposes that human uniqueness flourished under a real "adapted veil of ignorance" concealing the steady inflation of synergistic politics which resulted from early humans' sturdy egalitarianism. This proposition divides into four parts: (1) early humans first stumbled on a purely cultural means to enforce a unique kind of within-team antagonistic equality--dyadic balanced deterrence thanks to handheld weapons (Chapais 2008); (2) this cultural innovation is thus closely tied to humans' darkest side, but it also launched the cumulative evolution of humans' brightest qualities--egalitarian team synergy and solidarity, together with the associated synergistic intelligence, culture, and communications; (3) runaway synergistic competition for differential merit among antagonistically equal obligate teammates is the single politically selective mechanism behind the cumulative evolution of all these brighter qualities, but numerous factors to be clarified here conceal this mighty evolutionary driver; (4) this veil of ignorance persists today, which explains why humans' unique prosocial capacities are still not clearly understood by science. The purpose of this paper is to start lifting

  12. On the perpetuation of ignorance: system dependence, system justification, and the motivated avoidance of sociopolitical information.

    Science.gov (United States)

    Shepherd, Steven; Kay, Aaron C

    2012-02-01

    How do people cope when they feel uninformed or unable to understand important social issues, such as the environment, energy concerns, or the economy? Do they seek out information, or do they simply ignore the threatening issue at hand? One would intuitively expect that a lack of knowledge would motivate an increased, unbiased search for information, thereby facilitating participation and engagement in these issues-especially when they are consequential, pressing, and self-relevant. However, there appears to be a discrepancy between the importance/self-relevance of social issues and people's willingness to engage with and learn about them. Leveraging the literature on system justification theory (Jost & Banaji, 1994), the authors hypothesized that, rather than motivating an increased search for information, a lack of knowledge about a specific sociopolitical issue will (a) foster feelings of dependence on the government, which will (b) increase system justification and government trust, which will (c) increase desires to avoid learning about the relevant issue when information is negative or when information valence is unknown. In other words, the authors suggest that ignorance-as a function of the system justifying tendencies it may activate-may, ironically, breed more ignorance. In the contexts of energy, environmental, and economic issues, the authors present 5 studies that (a) provide evidence for this specific psychological chain (i.e., ignorance about an issue → dependence → government trust → avoidance of information about that issue); (b) shed light on the role of threat and motivation in driving the second and third links in this chain; and (c) illustrate the unfortunate consequences of this process for individual action in those contexts that may need it most.

  13. Ignoring versus updating in working memory reveal differential roles of attention and feature binding

    OpenAIRE

    Fallon, SJ; Mattiesing, RM; Dolfen, N; Manohar, SGM; Husain, M

    2017-01-01

    Ignoring distracting information and updating current contents are essential components of working memory (WM). Yet, although both require controlling irrelevant information, it is unclear whether they have the same effects on recall and produce the same level of misbinding errors (incorrectly joining the features of different memoranda). Moreover, the likelihood of misbinding may be affected by the feature similarity between the items already encoded into memory and the information that has ...

  14. Maximum likelihood estimation of finite mixture model for economic data

    Science.gov (United States)

    Phoong, Seuk-Yen; Ismail, Mohd Tahir

    2014-06-01

    Finite mixture model is a mixture model with finite-dimension. This models are provides a natural representation of heterogeneity in a finite number of latent classes. In addition, finite mixture models also known as latent class models or unsupervised learning models. Recently, maximum likelihood estimation fitted finite mixture models has greatly drawn statistician's attention. The main reason is because maximum likelihood estimation is a powerful statistical method which provides consistent findings as the sample sizes increases to infinity. Thus, the application of maximum likelihood estimation is used to fit finite mixture model in the present paper in order to explore the relationship between nonlinear economic data. In this paper, a two-component normal mixture model is fitted by maximum likelihood estimation in order to investigate the relationship among stock market price and rubber price for sampled countries. Results described that there is a negative effect among rubber price and stock market price for Malaysia, Thailand, Philippines and Indonesia.

  15. Ignoring alarming news brings indifference: Learning about the world and the self.

    Science.gov (United States)

    Paluck, Elizabeth Levy; Shafir, Eldar; Wu, Sherry Jueyu

    2017-10-01

    The broadcast of media reports about moral crises such as famine can subtly depress rather than activate moral concern. Whereas much research has examined the effects of media reports that people attend to, social psychological analysis suggests that what goes unattended can also have an impact. We test the idea that when vivid news accounts of human suffering are broadcast in the background but ignored, people infer from their choice to ignore these accounts that they care less about the issue, compared to those who pay attention and even to those who were not exposed. Consistent with research on self-perception and attribution, three experiments demonstrate that participants who were nudged to distract themselves in front of a television news program about famine in Niger (Study 1), or to skip an online promotional video for the Niger famine program (Study 2), or who chose to ignore the famine in Niger television program in more naturalistic settings (Study 3) all assigned lower importance to poverty and to hunger reduction compared to participants who watched with no distraction or opportunity to skip the program, or to those who did not watch at all. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Finite temperature field theory

    CERN Document Server

    Das, Ashok

    1997-01-01

    This book discusses all three formalisms used in the study of finite temperature field theory, namely the imaginary time formalism, the closed time formalism and thermofield dynamics. Applications of the formalisms are worked out in detail. Gauge field theories and symmetry restoration at finite temperature are among the practical examples discussed in depth. The question of gauge dependence of the effective potential and the Nielsen identities are explained. The nonrestoration of some symmetries at high temperature (such as supersymmetry) and theories on nonsimply connected space-times are al

  17. Generalized finite elements

    International Nuclear Information System (INIS)

    Wachspress, E.

    2009-01-01

    Triangles and rectangles are the ubiquitous elements in finite element studies. Only these elements admit polynomial basis functions. Rational functions provide a basis for elements having any number of straight and curved sides. Numerical complexities initially associated with rational bases precluded extensive use. Recent analysis has reduced these difficulties and programs have been written to illustrate effectiveness. Although incorporation in major finite element software requires considerable effort, there are advantages in some applications which warrant implementation. An outline of the basic theory and of recent innovations is presented here. (authors)

  18. Analytic structure of ρ meson propagator at finite temperature

    International Nuclear Information System (INIS)

    Ghosh, Sabyasachi; Sarkar, Sourav; Mallik, S.

    2010-01-01

    We analyse the structure of one-loop self-energy graphs for the ρ meson in real time formulation of finite temperature field theory. We find the discontinuities of these graphs across the unitary and the Landau cuts. These contributions are identified with different sources of medium modification discussed in the literature. We also calculate numerically the imaginary and the real parts of the self-energies and construct the spectral function of the ρ meson, which are compared with an earlier determination. A significant contribution arises from the unitary cut of the πω loop, that was ignored so far in the literature. (orig.)

  19. Beneficiation and agglomeration of manganese ore fines (an area so important and yet so ignored)

    Science.gov (United States)

    Sane, R.

    2018-01-01

    Unpredictable changes in demand and prices varying from very attractive to depressing levels have thrown all Manganese ore mines out of normal operating gear. The supply has to be in time-bound fashion, of dependable quality and continuous. With setting-up of numerous small units and with existing ferro-alloy units, ore supply has become extremely sensitive issue. Due to unpredictable swing in price of Mn ore lumps, furnace operators found it economic and convenient to use fines, even at great risks to furnace equipment and operating persons and therefore risks & damages were conveniently & comfortably ignored. Beneficiation Cost(Operating) approx. - (ferruginous ore) - Roast reduction followed by magnetic separation route-particulars - Water 20/-, Power 490/-, Coal fines-675/-, OH-250/-totaling to Rs.1435/T. (Figures are based on actual data from investigations on Orissa & Karnataka sector ores). Feed Grade Mn- 28 to 32 %, Fe - 14 to 25 %, Concentrate (Beneficiated ore fines)- - Mn- 45 to 48 %, Fe - 6 to 8 %., Recovery - 35 %, Price of 28-30 % Mn ore fines = Rs. 2400/T, Cost of Concentrated fines (45/48% Mn grade) = Rs. 8300/T, Price of 47-48 % Mn Lumpy ore = Rs.11,000/T. Sintering Cost (Operating) - Approx-Rs.1195=00/T Sinter. Therefore cost of Sinter produced from beneficiated concentrate is 9130+1195 = Rs. 10325. The difference in cost of 48%Mn ore Lumps & 48%Mn sintered concentrate = 11000-10325 = Rs.675/T. The main purpose of this paper is to show that establishment of beneficiation unit & Sintering unit is economically feasible. There are many misconcepts, still prevailing, about use of Mn ore sinters. Few of the main misconcepts are- 1)Sinters bring no benefit - technical or economical.2) Sinters are very friable and disintegrate easily into high fines during handling/transportation. 3) Fines below 100 mesh cannot be sintered. 4) Silica increases to high level during sintering, resulting in to high slag volume thereby higher power consumption. All are false

  20. Finite element simulation of piezoelectric transformers.

    Science.gov (United States)

    Tsuchiya, T; Kagawa, Y; Wakatsuki, N; Okamura, H

    2001-07-01

    Piezoelectric transformers are nothing but ultrasonic resonators with two pairs of electrodes provided on the surface of a piezoelectric substrate in which electrical energy is carried in the mechanical form. The input and output electrodes are arranged to provide the impedance transformation, which results in the voltage transformation. As they are operated at a resonance, the electrical equivalent circuit approach has traditionally been developed in a rather empirical way and has been used for analysis and design. The present paper deals with the analysis of the piezoelectric transformers based on the three-dimensional finite element modelling. The PIEZO3D code that we have developed is modified to include the external loading conditions. The finite element approach is now available for a wide variety of the electrical boundary conditions. The equivalent circuit of lumped parameters can also be derived from the finite element method (FEM) solution if required. The simulation of the present transformers is made for the low intensity operation and compared with the experimental results. Demonstration is made for basic Rosen-type transformers in which the longitudinal mode of a plate plays an important role; in which the equivalent circuit of lumped constants has been used. However, there are many modes of vibration associated with the plate, the effect of which cannot always be ignored. In the experiment, the double resonances are sometimes observed in the vicinity of the operating frequency. The simulation demonstrates that this is due to the coupling of the longitudinal mode with the flexural mode. Thus, the simulation provides an invaluable guideline to the transformer design.

  1. A finite quantum gravity

    International Nuclear Information System (INIS)

    Meszaros, A.

    1984-05-01

    In case the graviton has a very small non-zero mass, the existence of six additional massive gravitons with very big masses leads to a finite quantum gravity. There is an acausal behaviour on the scales that is determined by the masses of additional gravitons. (author)

  2. Finite lattice extrapolation algorithms

    International Nuclear Information System (INIS)

    Henkel, M.; Schuetz, G.

    1987-08-01

    Two algorithms for sequence extrapolation, due to von den Broeck and Schwartz and Bulirsch and Stoer are reviewed and critically compared. Applications to three states and six states quantum chains and to the (2+1)D Ising model show that the algorithm of Bulirsch and Stoer is superior, in particular if only very few finite lattice data are available. (orig.)

  3. Finite unified models

    Energy Technology Data Exchange (ETDEWEB)

    Kapetanakis, D. (Technische Univ. Muenchen, Garching (Germany). Physik Dept.); Mondragon, M. (Technische Univ. Muenchen, Garching (Germany). Physik Dept.); Zoupanos, G. (National Technical Univ., Athens (Greece). Physics Dept.)

    1993-09-01

    We present phenomenologically viable SU(5) unified models which are finite to all orders before the spontaneous symmetry breaking. In the case of two models with three families the top quark mass is predicted to be 178.8 GeV. (orig.)

  4. Finite unified models

    International Nuclear Information System (INIS)

    Kapetanakis, D.; Mondragon, M.; Zoupanos, G.

    1993-01-01

    We present phenomenologically viable SU(5) unified models which are finite to all orders before the spontaneous symmetry breaking. In the case of two models with three families the top quark mass is predicted to be 178.8 GeV. (orig.)

  5. Finiteness and GUTs

    International Nuclear Information System (INIS)

    Kapetanakis, D.; Mondragon, M.

    1993-01-01

    It is shown how to obtain phenomenologically viable SU(5) unified models which are finite to all orders before the spontaneous symmetry breaking. A very interesting feature of the models with three families is that they predict the top quark mass to be around 178 GeV. 16 refs

  6. Robust RBF Finite Automata

    Czech Academy of Sciences Publication Activity Database

    Šorel, Michal; Šíma, Jiří

    2004-01-01

    Roč. 62, - (2004), s. 93-110 ISSN 0925-2312 R&D Projects: GA AV ČR IAB2030007; GA MŠk LN00A056 Keywords : radial basis function * neural network * finite automaton * Boolean circuit * computational power Subject RIV: BA - General Mathematics Impact factor: 0.641, year: 2004

  7. Inside finite elements

    CERN Document Server

    Weiser, Martin

    2016-01-01

    All relevant implementation aspects of finite element methods are discussed in this book. The focus is on algorithms and data structures as well as on their concrete implementation. Theory is covered as far as it gives insight into the construction of algorithms. Throughout the exercises a complete FE-solver for scalar 2D problems will be implemented in Matlab/Octave.

  8. Early auditory change detection implicitly facilitated by ignored concurrent visual change during a Braille reading task.

    Science.gov (United States)

    Aoyama, Atsushi; Haruyama, Tomohiro; Kuriki, Shinya

    2013-09-01

    Unconscious monitoring of multimodal stimulus changes enables humans to effectively sense the external environment. Such automatic change detection is thought to be reflected in auditory and visual mismatch negativity (MMN) and mismatch negativity fields (MMFs). These are event-related potentials and magnetic fields, respectively, evoked by deviant stimuli within a sequence of standard stimuli, and both are typically studied during irrelevant visual tasks that cause the stimuli to be ignored. Due to the sensitivity of MMN/MMF to potential effects of explicit attention to vision, however, it is unclear whether multisensory co-occurring changes can purely facilitate early sensory change detection reciprocally across modalities. We adopted a tactile task involving the reading of Braille patterns as a neutral ignore condition, while measuring magnetoencephalographic responses to concurrent audiovisual stimuli that were infrequently deviated either in auditory, visual, or audiovisual dimensions; 1000-Hz standard tones were switched to 1050-Hz deviant tones and/or two-by-two standard check patterns displayed on both sides of visual fields were switched to deviant reversed patterns. The check patterns were set to be faint enough so that the reversals could be easily ignored even during Braille reading. While visual MMFs were virtually undetectable even for visual and audiovisual deviants, significant auditory MMFs were observed for auditory and audiovisual deviants, originating from bilateral supratemporal auditory areas. Notably, auditory MMFs were significantly enhanced for audiovisual deviants from about 100 ms post-stimulus, as compared with the summation responses for auditory and visual deviants or for each of the unisensory deviants recorded in separate sessions. Evidenced by high tactile task performance with unawareness of visual changes, we conclude that Braille reading can successfully suppress explicit attention and that simultaneous multisensory changes can

  9. Growth Modeling with Non-Ignorable Dropout: Alternative Analyses of the STAR*D Antidepressant Trial

    Science.gov (United States)

    Muthén, Bengt; Asparouhov, Tihomir; Hunter, Aimee; Leuchter, Andrew

    2011-01-01

    This paper uses a general latent variable framework to study a series of models for non-ignorable missingness due to dropout. Non-ignorable missing data modeling acknowledges that missingness may depend on not only covariates and observed outcomes at previous time points as with the standard missing at random (MAR) assumption, but also on latent variables such as values that would have been observed (missing outcomes), developmental trends (growth factors), and qualitatively different types of development (latent trajectory classes). These alternative predictors of missing data can be explored in a general latent variable framework using the Mplus program. A flexible new model uses an extended pattern-mixture approach where missingness is a function of latent dropout classes in combination with growth mixture modeling using latent trajectory classes. A new selection model allows not only an influence of the outcomes on missingness, but allows this influence to vary across latent trajectory classes. Recommendations are given for choosing models. The missing data models are applied to longitudinal data from STAR*D, the largest antidepressant clinical trial in the U.S. to date. Despite the importance of this trial, STAR*D growth model analyses using non-ignorable missing data techniques have not been explored until now. The STAR*D data are shown to feature distinct trajectory classes, including a low class corresponding to substantial improvement in depression, a minority class with a U-shaped curve corresponding to transient improvement, and a high class corresponding to no improvement. The analyses provide a new way to assess drug efficiency in the presence of dropout. PMID:21381817

  10. Burden of Circulatory System Diseases and Ignored Barriers ofKnowledge Translation

    Directory of Open Access Journals (Sweden)

    Hamed-Basir Ghafouri

    2012-10-01

    Full Text Available Circulatory system disease raise third highest disability-adjusted life years among Iranians and ischemic cardiac diseases are main causes for such burden. Despite available evidences on risk factors of the disease, no effective intervention was implemented to control and prevent the disease. This paper non-systematically reviews available literature on the problem, solutions, and barriers of implementation of knowledge translation in Iran. It seems that there are ignored factors such as cultural and motivational issues in knowledge translation interventions but there are hopes for implementation of started projects and preparation of students as next generation of knowledge transferors.

  11. Mes chers collègues, les moines, ou le partage de l’ignorance

    Directory of Open Access Journals (Sweden)

    Laurence Caillet

    2009-03-01

    Full Text Available Mes chers collègues, les moines, ou le partage de l’ignorance. Aucun statut ne m’a autant étonnée que celui de collègue qui me fut conféré par les moines du Grand monastère de l’Est, à Nara. Après avoir testé mes connaissances en matière de rituel, ces moines fort savants manifestèrent en effet, avec ostentation, leur ignorance. Pointant pour moi des détails liturgiques qu’ils tenaient pour incompréhensibles, ils prirent un plaisir évident à bavarder histoire et théologie, comme si je pouvais apporter quoi que ce soit. Cette mise en scène du caractère incompréhensible du rituel soulignait le caractère ineffable de cérémonies jadis accomplies au ciel par des entités supérieures. Je fournissais prétexte à décrire la vanité de l’érudition face à l’accomplissement des mystères et aussi l’importance de cette érudition pour renouer avec un sens originel irrémédiablement inconnaissable.My dear colleagues the monks, or the sharing of ignorance. No status has ever surprised me as much as that of “colleague” conferred on me by the monks of the Great Eastern Monastery of Nara. After testing my knowledge of ritual, these very learned monks made great show of their ignorance. Drawing my attention to liturgical details that they held to be incomprehensible, they took obvious pleasure in chatting about history and theology, as if I were capable of making the slightest contribution. This staging of the impenetrable nature of the ritual highlighted the ineffable character of the ceremonies performed in heaven long ago by superior beings. I provided a convenient pretext for describing the vanity of erudition in the face of the accomplishment of the mysteries, and also the importance of this erudition for renewing an original, irreparably unknowable meaning.

  12. Strong interaction at finite temperature

    Indian Academy of Sciences (India)

    Quantum chromodynamics; finite temperature; chiral perturbation theory; QCD sum rules. PACS Nos 11.10. ..... at finite temperature. The self-energy diagrams of figure 2 modify it to ..... method of determination at present. Acknowledgement.

  13. Robust weak measurements on finite samples

    International Nuclear Information System (INIS)

    Tollaksen, Jeff

    2007-01-01

    A new weak measurement procedure is introduced for finite samples which yields accurate weak values that are outside the range of eigenvalues and which do not require an exponentially rare ensemble. This procedure provides a unique advantage in the amplification of small nonrandom signals by minimizing uncertainties in determining the weak value and by minimizing sample size. This procedure can also extend the strength of the coupling between the system and measuring device to a new regime

  14. Supersymmetry at finite temperature

    International Nuclear Information System (INIS)

    Oliveira, M.W. de.

    1986-01-01

    The consequences of the incorporation of finite temperature effects in fields theories are investigated. Particularly, we consider the sypersymmetric non-linear sigma model, calculating the effective potencial in the large N limit. Initially, we present the 1/N expantion formalism and, for the O(N) model of scalar field, we show the impossibility of spontaneous symmetry breaking. Next, we study the same model at finite temperature and in the presence of conserved charges (the O(N) symmetry's generator). We conclude that these conserved charges explicitly break the symmetry. We introduce a calculation method for the thermodynamic potential of the theory in the presence of chemical potentials. We present an introduction to Supersymmetry in the aim of describing some important concepts for the treatment at T>0. We show that Suppersymmetry is broken for any T>0, in opposition to what one expects, by the solution of the Hierachy Problem. (author) [pt

  15. Using Finite Element Method

    Directory of Open Access Journals (Sweden)

    M.H.R. Ghoreishy

    2008-02-01

    Full Text Available This research work is devoted to the footprint analysis of a steel-belted radial tyre (185/65R14 under vertical static load using finite element method. Two models have been developed in which in the first model the tread patterns were replaced by simple ribs while the second model was consisted of details of the tread blocks. Linear elastic and hyper elastic (Arruda-Boyce material models were selected to describe the mechanical behavior of the reinforcing and rubbery parts, respectively. The above two finite element models of the tyre were analyzed under inflation pressure and vertical static loads. The second model (with detailed tread patterns was analyzed with and without friction effect between tread and contact surfaces. In every stage of the analysis, the results were compared with the experimental data to confirm the accuracy and applicability of the model. Results showed that neglecting the tread pattern design not only reduces the computational cost and effort but also the differences between computed deformations do not show significant changes. However, more complicated variables such as shape and area of the footprint zone and contact pressure are affected considerably by the finite element model selected for the tread blocks. In addition, inclusion of friction even in static state changes these variables significantly.

  16. Probabilistic finite elements

    Science.gov (United States)

    Belytschko, Ted; Wing, Kam Liu

    1987-01-01

    In the Probabilistic Finite Element Method (PFEM), finite element methods have been efficiently combined with second-order perturbation techniques to provide an effective method for informing the designer of the range of response which is likely in a given problem. The designer must provide as input the statistical character of the input variables, such as yield strength, load magnitude, and Young's modulus, by specifying their mean values and their variances. The output then consists of the mean response and the variance in the response. Thus the designer is given a much broader picture of the predicted performance than with simply a single response curve. These methods are applicable to a wide class of problems, provided that the scale of randomness is not too large and the probabilistic density functions possess decaying tails. By incorporating the computational techniques we have developed in the past 3 years for efficiency, the probabilistic finite element methods are capable of handling large systems with many sources of uncertainties. Sample results for an elastic-plastic ten-bar structure and an elastic-plastic plane continuum with a circular hole subject to cyclic loadings with the yield stress on the random field are given.

  17. Allocating health care: cost-utility analysis, informed democratic decision making, or the veil of ignorance?

    Science.gov (United States)

    Goold, S D

    1996-01-01

    Assuming that rationing health care is unavoidable, and that it requires moral reasoning, how should we allocate limited health care resources? This question is difficult because our pluralistic, liberal society has no consensus on a conception of distributive justice. In this article I focus on an alternative: Who shall decide how to ration health care, and how shall this be done to respect autonomy, pluralism, liberalism, and fairness? I explore three processes for making rationing decisions: cost-utility analysis, informed democratic decision making, and applications of the veil of ignorance. I evaluate these processes as examples of procedural justice, assuming that there is no outcome considered the most just. I use consent as a criterion to judge competing processes so that rationing decisions are, to some extent, self-imposed. I also examine the processes' feasibility in our current health care system. Cost-utility analysis does not meet criteria for actual or presumed consent, even if costs and health-related utility could be measured perfectly. Existing structures of government cannot creditably assimilate the information required for sound rationing decisions, and grassroots efforts are not representative. Applications of the veil of ignorance are more useful for identifying principles relevant to health care rationing than for making concrete rationing decisions. I outline a process of decision making, specifically for health care, that relies on substantive, selected representation, respects pluralism, liberalism, and deliberative democracy, and could be implemented at the community or organizational level.

  18. Excitatory and inhibitory priming by attended and ignored non-recycled words with monolinguals and bilinguals.

    Science.gov (United States)

    Neumann, Ewald; Nkrumah, Ivy K; Chen, Zhe

    2018-03-03

    Experiments examining identity priming from attended and ignored novel words (words that are used only once except when repetition is required due to experimental manipulation) in a lexical decision task are reported. Experiment 1 tested English monolinguals whereas Experiment 2 tested Twi (a native language of Ghana, Africa)-English bilinguals. Participants were presented with sequential pairs of stimuli composed of a prime followed by a probe, with each containing two items. The participants were required to name the target word in the prime display, and to make a lexical decision to the target item in the probe display. On attended repetition (AR) trials the probe target item was identical to the target word on the preceding attentional display. On ignored repetition (IR) trials the probe target item was the same as the distractor word in the preceding attentional display. The experiments produced facilitated (positive) priming in the AR trials and delayed (negative) priming in the IR trials. Significantly, the positive and negative priming effects also replicated across both monolingual and bilingual groups of participants, despite the fact that the bilinguals were responding to the task in their non-dominant language.

  19. Illiteracy, Ignorance, and Willingness to Quit Smoking among Villagers in India

    Science.gov (United States)

    Gorty, Prasad V. S. N. R.; Allam, Apparao

    1992-01-01

    During the field work to control oral cancer, difficulty in communication was encountered with illiterates. A study to define the role of illiteracy, ignorance and willingness to quit smoking among the villagers was undertaken in a rural area surrounding Doddipatla Village, A.P., India. Out of a total population of 3,550, 272 (7.7%) persons, mostly in the age range of 21–50 years, attended a cancer detection camp. There were 173 (63.6%) females and 99 (36.4%) males, among whom 66 (M53 + F13) were smokers; 36.4% of males and 63% of females were illiterate. Among the illiterates, it was observed that smoking rate was high (56%) and 47.7% were ignorant of health effects of smoking. The attitude of illiterate smokers was encouraging, as 83.6% were willing to quit smoking. Further research is necessary to design health education material for 413.5 million illiterates living in India (1991 Indian Census). A community health worker, trained in the use of mass media coupled with a person‐to‐person approach, may help the smoker to quit smoking. PMID:1506267

  20. Optical Finite Element Processor

    Science.gov (United States)

    Casasent, David; Taylor, Bradley K.

    1986-01-01

    A new high-accuracy optical linear algebra processor (OLAP) with many advantageous features is described. It achieves floating point accuracy, handles bipolar data by sign-magnitude representation, performs LU decomposition using only one channel, easily partitions and considers data flow. A new application (finite element (FE) structural analysis) for OLAPs is introduced and the results of a case study presented. Error sources in encoded OLAPs are addressed for the first time. Their modeling and simulation are discussed and quantitative data are presented. Dominant error sources and the effects of composite error sources are analyzed.

  1. Combinatorics of finite sets

    CERN Document Server

    Anderson, Ian

    2011-01-01

    Coherent treatment provides comprehensive view of basic methods and results of the combinatorial study of finite set systems. The Clements-Lindstrom extension of the Kruskal-Katona theorem to multisets is explored, as is the Greene-Kleitman result concerning k-saturated chain partitions of general partially ordered sets. Connections with Dilworth's theorem, the marriage problem, and probability are also discussed. Each chapter ends with a helpful series of exercises and outline solutions appear at the end. ""An excellent text for a topics course in discrete mathematics."" - Bulletin of the Ame

  2. Mechanical and chemical spinodal instabilities in finite quantum systems

    International Nuclear Information System (INIS)

    Colonna, M.; Chomaz, Ph.; Ayik, S.

    2001-01-01

    Self consistent quantum approaches are used to study the instabilities of finite nuclear systems. The frequencies of multipole density fluctuations are determined as a function of dilution and temperature, for several isotopes. The spinodal region of the phase diagrams is determined and it appears reduced by finite size effects. The role of surface and volume instabilities is discussed. Important chemical effects are associated with mechanical disruption and may lead to isospin fractionation. (authors)

  3. Size-dependent homogenized diffusion parameters for a finite lattice

    International Nuclear Information System (INIS)

    Premuda, F.

    1980-01-01

    A numerical technique is reported for solving the transcendental equation for unknown Ysub(n+1). The solution is expressed in terms of quantities related to Ysub(n). This is an iterative reversion technique which has already been proven to converge rapidly in the homogeneous slab problem considered herein. (author)

  4. Addendum to "Finite-size effects on multibody neutrino exchange"

    CERN Document Server

    Abada, A; Rodríguez-Quintero, J

    1999-01-01

    The interaction energy of the neutrons due to massless neutrino exchange in a neutron star has recently been proved, using an effective theory, to be extremely small and infrared-safe. Our comment here is of conceptual order: two approaches to compute the total interaction energy density have recently been proposed. Here, we study the connection between these two approaches. From CP invariance, we argue that the resulting interaction energy has to be even in the parameter $b=-G_F n_n /\\sqrt{2}$, which expresses the static neutrino potential created by a neutron medium of density $n_n$.

  5. Effects of finite size on spin glass dynamics

    Science.gov (United States)

    Sato, Tetsuya; Komatsu, Katsuyoshi

    2010-12-01

    In spite of comprehensive studies to clarify a variety of interesting phenomena of spin glasses, their understanding has been insufficiently established. To overcome such a problem, fabrication of a mesoscopic spin glass system, whose dynamics can be observed over the entire range to the equilibrium, is useful. In this review the challenges of research that has been performed up to now in this direction and our recent related studies are introduced. We have established to study the spin glass behaviour in terms of droplet picture using nanofabricated mesoscopic samples to some extent, but some problems that should be clarified have been left. Finally, the direction of some new studies is proposed to solve the problems.

  6. Dynamic response in a finite size composite multiferroic thin film

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zidong, E-mail: Zidong.Wang@auckland.ac.nz; Grimson, Malcolm J. [Department of Physics, The University of Auckland, Auckland 1010 (New Zealand)

    2016-03-28

    Composite multiferroics, heterostructures of ferromagnetic and ferroelectric materials, are characterized by a remarkable magnetoelectric effect at the interface. Previous work has supported the ferromagnetic structure with magnetic spins and the ferroelectric with pseudospins which act as electric dipoles in a microscopic model, coupled with a magnetoelectric interaction [Wang and Grimson, J. Appl. Phys. 118, 124109 (2015)]. In this work, by solving the stochastic Landau-Lifshitz-Gilbert equation, the electric-field-induced magnetization switching in a twisted boundary condition has been studied, and a behavior of domain wall in the ferromagnetic structure is discussed.

  7. Spin masters how the media ignored the real news and helped reelect Barack Obama

    CERN Document Server

    Freddoso, David

    2013-01-01

    The biggest story of the election was how the media ignored the biggest story of the election.Amid all the breathless coverage of a non-existent War on Women, there was little or no coverage of Obama's war on the economy?how, for instance, part-time work is replacing full-time work; how low-wage jobs are replacing high-wage ones; how for Americans between the ages of 25 and 54 there are fewer jobs today than there were when the recession officially ended in 2009, and fewer, in fact, than at any time since mid-1997.The downsizing of the American economy wasn't the only stor

  8. On Moderator Detection in Anchoring Research: Implications of Ignoring Estimate Direction

    Directory of Open Access Journals (Sweden)

    Nathan N. Cheek

    2018-05-01

    Full Text Available Anchoring, whereby judgments assimilate to previously considered standards, is one of the most reliable effects in psychology. In the last decade, researchers have become increasingly interested in identifying moderators of anchoring effects. We argue that a drawback of traditional moderator analyses in the standard anchoring paradigm is that they ignore estimate direction—whether participants’ estimates are higher or lower than the anchor value. We suggest that failing to consider estimate direction can sometimes obscure moderation in anchoring tasks, and discuss three potential analytic solutions that take estimate direction into account. Understanding moderators of anchoring effects is essential for a basic understanding of anchoring and for applied research on reducing the influence of anchoring in real-world judgments. Considering estimate direction reduces the risk of failing to detect moderation.

  9. Effects of ignoring baseline on modeling transitions from intact cognition to dementia.

    Science.gov (United States)

    Yu, Lei; Tyas, Suzanne L; Snowdon, David A; Kryscio, Richard J

    2009-07-01

    This paper evaluates the effect of ignoring baseline when modeling transitions from intact cognition to dementia with mild cognitive impairment (MCI) and global impairment (GI) as intervening cognitive states. Transitions among states are modeled by a discrete-time Markov chain having three transient (intact cognition, MCI, and GI) and two competing absorbing states (death and dementia). Transition probabilities depend on two covariates, age and the presence/absence of an apolipoprotein E-epsilon4 allele, through a multinomial logistic model with shared random effects. Results are illustrated with an application to the Nun Study, a cohort of 678 participants 75+ years of age at baseline and followed longitudinally with up to ten cognitive assessments per nun.

  10. The wisdom of ignorant crowds: Predicting sport outcomes by mere recognition

    Directory of Open Access Journals (Sweden)

    Stefan M. Herzog

    2011-02-01

    Full Text Available that bets on the fact that people's recognition knowledge of names is a proxy for their competitiveness: In sports, it predicts that the better-known team or player wins a game. We present two studies on the predictive power of recognition in forecasting soccer games (World Cup 2006 and UEFA Euro 2008 and analyze previously published results. The performance of the collective recognition heuristic is compared to two benchmarks: predictions based on official rankings and aggregated betting odds. Across three soccer and two tennis tournaments, the predictions based on recognition performed similar to those based on rankings; when compared with betting odds, the heuristic fared reasonably well. Forecasts based on rankings---but not on betting odds---were improved by incorporating collective recognition information. We discuss the use of recognition for forecasting in sports and conclude that aggregating across individual ignorance spawns collective wisdom.

  11. Finiteness of corner vortices

    Science.gov (United States)

    Kalita, Jiten C.; Biswas, Sougata; Panda, Swapnendu

    2018-04-01

    Till date, the sequence of vortices present in the solid corners of steady internal viscous incompressible flows was thought to be infinite. However, the already existing and most recent geometric theories on incompressible viscous flows that express vortical structures in terms of critical points in bounded domains indicate a strong opposition to this notion of infiniteness. In this study, we endeavor to bridge the gap between the two opposing stream of thoughts by diagnosing the assumptions of the existing theorems on such vortices. We provide our own set of proofs for establishing the finiteness of the sequence of corner vortices by making use of the continuum hypothesis and Kolmogorov scale, which guarantee a nonzero scale for the smallest vortex structure possible in incompressible viscous flows. We point out that the notion of infiniteness resulting from discrete self-similarity of the vortex structures is not physically feasible. Making use of some elementary concepts of mathematical analysis and our own construction of diametric disks, we conclude that the sequence of corner vortices is finite.

  12. Portion size me : Plate-size induced consumption norms and education futility

    NARCIS (Netherlands)

    Wansink, B.; van Ittersum, Koert

    2013-01-01

    Research on the self-serving of food has empirically ignored the role that visual consumption norms play in determining how much food we serve on different sized dinnerware. We contend that dinnerware provides a visual anchor of an appropriate fill-level, which in turn, serves as a consumption norm

  13. Food Quality Certificates and Research on Effect of Food Quality Certificates to Determinate Ignored Level of Buying Behavioral: A Case Study in Hitit University Feas Business Department

    Directory of Open Access Journals (Sweden)

    Hulya CAGIRAN KENDIRLI

    2014-12-01

    According to result of research, there is no relationship between demographic specialties of students and ignored of food and quality legislation. But there is relationship between sexuality and ignored of food and quality legislation.

  14. Thermoelectric properties of finite graphene antidot lattices

    DEFF Research Database (Denmark)

    Gunst, Tue; Markussen, Troels; Jauho, Antti-Pekka

    2011-01-01

    We present calculations of the electronic and thermal transport properties of graphene antidot lattices with a finite length along the transport direction. The calculations are based on the π-tight-binding model and the Brenner potential. We show that both electronic and thermal transport...... properties converge fast toward the bulk limit with increasing length of the lattice: only a few repetitions (≃6) of the fundamental unit cell are required to recover the electronic band gap of the infinite lattice as a transport gap for the finite lattice. We investigate how different antidot shapes...... and sizes affect the thermoelectric properties. The resulting thermoelectric figure of merit, ZT, can exceed 0.25, and it is highly sensitive to the atomic arrangement of the antidot edges. Specifically, hexagonal holes with pure armchair edges lead to an order-of-magnitude larger ZT as compared to pure...

  15. Meson spectral functions at finite temperature

    International Nuclear Information System (INIS)

    Wetzorke, I.; Karsch, F.; Laermann, E.; Petreczky, P.; Stickan, S.

    2001-10-01

    The Maximum Entropy Method provides a Bayesian approach to reconstruct the spectral functions from discrete points in Euclidean time. The applicability of the approach at finite temperature is probed with the thermal meson correlation function. Furthermore the influence of fuzzing/smearing techniques on the spectral shape is investigated. We present first results for meson spectral functions at several temperatures below and above T c . The correlation functions were obtained from quenched calculations with Clover fermions on large isotropic lattices of the size (24 - 64) 3 x 16. We compare the resulting pole masses with the ones obtained from standard 2-exponential fits of spatial and temporal correlation functions at finite temperature and in the vacuum. The deviation of the meson spectral functions from free spectral functions is examined above the critical temperature. (orig.)

  16. Meson spectral functions at finite temperature

    International Nuclear Information System (INIS)

    Wetzorke, I.; Karsch, F.; Laermann, E.; Petreczky, P.; Stickan, S.

    2002-01-01

    The Maximum Entropy Method provides a Bayesian approach to reconstruct the spectral functions from discrete points in Euclidean time. The applicability of the approach at finite temperature is probed with the thermal meson correlation function. Furthermore the influence of fuzzing/smearing techniques on the spectral shape is investigated. We present first results for meson spectral functions at several temperatures below and above T c . The correlation functions were obtained from quenched calculations with Clover fermions on large isotropic lattices of the size (24 - 64) 3 x 16. We compare the resulting pole masses with the ones obtained from standard 2-exponential fits of spatial and temporal correlation functions at finite temperature and in the vacuum. The deviation of the meson spectral functions from free spectral functions is examined above the critical temperature

  17. Tearing mode saturation with finite pressure

    International Nuclear Information System (INIS)

    Lee, J.K.

    1988-01-01

    With finite pressure, the saturation of the current-driven tearing mode is obtained in three-dimensional nonlinear resistive magnetohydrodynamic simulations for Tokamak plasmas. To effectively focus on the tearing modes, the perturbed pressure effects are excluded while the finite equilibrium pressure effects are retained. With this model, the linear growth rates of the tearing modes are found to be very insensitive to the equilibrium pressure increase. The nonlinear aspects of the tearing modes, however, are found to be very sensitive to the pressure increase in that the saturation level of the nonlinear harmonics of the tearing modes increases monotonically with the pressure rise. The increased level is associated with enhanced tearing island sizes or increased stochastic magnetic field region. (author)

  18. Finite element analysis of ARPS structures

    International Nuclear Information System (INIS)

    Ruhkamp, J.D.; McDougal, J.R.; Kramer, D.P.

    1998-01-01

    Algor finite element software was used to determine the stresses and deflections in the metallic walls of Advanced Radioisotope Power Systems (ARPS) designs. The preliminary design review of these systems often neglects the structural integrity of the design which can effect fabrication and the end use of the design. Before finite element analysis (FEA) was run on the canister walls of the thermophotovoltaic (TPV) generator, hand calculations were used to approximate the stresses and deflections in a flat plate. These results compared favorably to the FEA results of a similar size flat plate. The AMTEC (Alkali Metal Thermal-to-Electric Conversion) cells were analyzed by FEA and the results compared to two cells that were mechanically tested. The mechanically tested cells buckled in the thin sections, one at the top and one in the lower section. The FEA predicted similar stress and shape results but the critical buckling load was found to be very shape dependent

  19. Meson spectral functions at finite temperature

    Energy Technology Data Exchange (ETDEWEB)

    Wetzorke, I.; Karsch, F.; Laermann, E.; Petreczky, P.; Stickan, S

    2002-03-01

    The Maximum Entropy Method provides a Bayesian approach to reconstruct the spectral functions from discrete points in Euclidean time. The applicability of the approach at finite temperature is probed with the thermal meson correlation function. Furthermore the influence of fuzzing/smearing techniques on the spectral shape is investigated. We present first results for meson spectral functions at several temperatures below and above T{sub c}. The correlation functions were obtained from quenched calculations with Clover fermions on large isotropic lattices of the size (24 - 64){sup 3} x 16. We compare the resulting pole masses with the ones obtained from standard 2-exponential fits of spatial and temporal correlation functions at finite temperature and in the vacuum. The deviation of the meson spectral functions from free spectral functions is examined above the critical temperature.

  20. Meson spectral functions at finite temperature

    Energy Technology Data Exchange (ETDEWEB)

    Wetzorke, I.; Karsch, F.; Laermann, E.; Petreczky, P.; Stickan, S. [Bielefeld Univ. (Germany). Fakultaet fuer Physik

    2001-10-01

    The Maximum Entropy Method provides a Bayesian approach to reconstruct the spectral functions from discrete points in Euclidean time. The applicability of the approach at finite temperature is probed with the thermal meson correlation function. Furthermore the influence of fuzzing/smearing techniques on the spectral shape is investigated. We present first results for meson spectral functions at several temperatures below and above T{sub c}. The correlation functions were obtained from quenched calculations with Clover fermions on large isotropic lattices of the size (24 - 64){sup 3} x 16. We compare the resulting pole masses with the ones obtained from standard 2-exponential fits of spatial and temporal correlation functions at finite temperature and in the vacuum. The deviation of the meson spectral functions from free spectral functions is examined above the critical temperature. (orig.)

  1. Dense QCD in a Finite Volume

    International Nuclear Information System (INIS)

    Yamamoto, Naoki; Kanazawa, Takuya

    2009-01-01

    We study the properties of QCD at high baryon density in a finite volume where color superconductivity occurs. We derive exact sum rules for complex eigenvalues of the Dirac operator at a finite chemical potential, and show that the Dirac spectrum is directly related to the color superconducting gap Δ. Also, we find a characteristic signature of color superconductivity: an X-shaped spectrum of partition function zeros in the complex quark mass plane near the origin, reflecting the Z(2) L xZ(2) R symmetry of the diquark pairing. Our results are universal in the domain Δ -1 π -1 where L is the linear size of the system and m π is the pion mass at high density.

  2. Leak-Before-Break assessment of a welded piping based on 3D finite element method

    International Nuclear Information System (INIS)

    Chen, Mingya; Yu, Weiwei; Chen, Zhilin; Qian, Guian; Lu, Feng; Xue, Fei

    2017-01-01

    Highlights: • The effects of load reduction, strength match, welding width, load level, crack size and constraint are studied. • The results show that the LBB margin is dependent on the load level. • The results show that higher strength-match of WPJs will have higher crack-front constraints. • The results show that the engineering method has a high precision only if the width of weld is comparable to the crack depth. - Abstract: The paper studies the effects of the load reduction (discrepancy between designing and real loadings), strength match of the welded piping joint (WPJ), welding width, crack size and crack tip constraint on the Leak-Before-Break (LBB) assessment of a welded piping. The 3D finite element (FE) method is used in the study of a surge line of the steam generator in a nuclear power plant. It is demonstrated that the LBB margin is dependent on the loading level and the load reduction effect should be considered. When the loading is high enough, there is a quite large deviation between the J-integral calculated based on the real material property of WPJ and that calculated based on the engineering method, e.g. Zahoor handbook of Electric Power Research Institute (EPRI). The engineering method assumes that the whole piping is made of the unique welding material in the calculation. As the influence of the strength matching and welding width is ignored in the engineering method for J-integral calculation, the engineering method has a sufficient precision only if the width of welding is comparable to the crack depth. Narrower welding width leads to higher constraint of the plastic deformation in the welding and larger high stress areas in the base for the low strength-match WPJ. Higher strength matching of WPJs has higher crack-front constraints.

  3. The Determining Finite Automata Process

    Directory of Open Access Journals (Sweden)

    M. S. Vinogradova

    2017-01-01

    Full Text Available The theory of formal languages widely uses finite state automata both in implementation of automata-based approach to programming, and in synthesis of logical control algorithms.To ensure unambiguous operation of the algorithms, the synthesized finite state automata must be deterministic. Within the approach to the synthesis of the mobile robot controls, for example, based on the theory of formal languages, there are problems concerning the construction of various finite automata, but such finite automata, as a rule, will not be deterministic. The algorithm of determinization can be applied to the finite automata, as specified, in various ways. The basic ideas of the algorithm of determinization can be most simply explained using the representations of a finite automaton in the form of a weighted directed graph.The paper deals with finite automata represented as weighted directed graphs, and discusses in detail the procedure for determining the finite automata represented in this way. Gives a detailed description of the algorithm for determining finite automata. A large number of examples illustrate a capability of the determinization algorithm.

  4. Finite energy electroweak dyon

    Energy Technology Data Exchange (ETDEWEB)

    Kimm, Kyoungtae [Seoul National University, Faculty of Liberal Education, Seoul (Korea, Republic of); Yoon, J.H. [Konkuk University, Department of Physics, College of Natural Sciences, Seoul (Korea, Republic of); Cho, Y.M. [Konkuk University, Administration Building 310-4, Seoul (Korea, Republic of); Seoul National University, School of Physics and Astronomy, Seoul (Korea, Republic of)

    2015-02-01

    The latest MoEDAL experiment at LHC to detect the electroweak monopole makes the theoretical prediction of the monopole mass an urgent issue. We discuss three different ways to estimate the mass of the electroweak monopole. We first present the dimensional and scaling arguments which indicate the monopole mass to be around 4 to 10 TeV. To justify this we construct finite energy analytic dyon solutions which could be viewed as the regularized Cho-Maison dyon, modifying the coupling strength at short distance. Our result demonstrates that a genuine electroweak monopole whose mass scale is much smaller than the grand unification scale can exist, which can actually be detected at the present LHC. (orig.)

  5. Probabilistic fracture finite elements

    Science.gov (United States)

    Liu, W. K.; Belytschko, T.; Lua, Y. J.

    1991-05-01

    The Probabilistic Fracture Mechanics (PFM) is a promising method for estimating the fatigue life and inspection cycles for mechanical and structural components. The Probability Finite Element Method (PFEM), which is based on second moment analysis, has proved to be a promising, practical approach to handle problems with uncertainties. As the PFEM provides a powerful computational tool to determine first and second moment of random parameters, the second moment reliability method can be easily combined with PFEM to obtain measures of the reliability of the structural system. The method is also being applied to fatigue crack growth. Uncertainties in the material properties of advanced materials such as polycrystalline alloys, ceramics, and composites are commonly observed from experimental tests. This is mainly attributed to intrinsic microcracks, which are randomly distributed as a result of the applied load and the residual stress.

  6. Finite element modelling

    International Nuclear Information System (INIS)

    Tonks, M.R.; Williamson, R.; Masson, R.

    2015-01-01

    The Finite Element Method (FEM) is a numerical technique for finding approximate solutions to boundary value problems. While FEM is commonly used to solve solid mechanics equations, it can be applied to a large range of BVPs from many different fields. FEM has been used for reactor fuels modelling for many years. It is most often used for fuel performance modelling at the pellet and pin scale, however, it has also been used to investigate properties of the fuel material, such as thermal conductivity and fission gas release. Recently, the United Stated Department Nuclear Energy Advanced Modelling and Simulation Program has begun using FEM as the basis of the MOOSE-BISON-MARMOT Project that is developing a multi-dimensional, multi-physics fuel performance capability that is massively parallel and will use multi-scale material models to provide a truly predictive modelling capability. (authors)

  7. Axial anomaly at finite temperature and finite density

    International Nuclear Information System (INIS)

    Qian Zhixin; Su Rukeng; Yu, P.K.N.

    1994-01-01

    The U(1) axial anomaly in a hot fermion medium is investigated by using the real time Green's function method. After calculating the lowest order triangle diagrams, we find that finite temperature as well as finite fermion density does not affect the axial anomaly. The higher order corrections for the axial anomaly are discussed. (orig.)

  8. Modelling of Size Effect with Regularised Continua

    Directory of Open Access Journals (Sweden)

    H. Askes

    2004-01-01

    Full Text Available A nonlocal damage continuum and a viscoplastic damage continuum are used to model size effects. Three-point bending specimens are analysed, whereby a distinction is made between unnotched specimens, specimens with a constant notch and specimens with a proportionally scaled notch. Numerical finite element simulations have been performed for specimen sizes in a range of 1:64. Size effects are established in terms of nominal strength and compared to existing size effect models from the literature. 

  9. Axial anomaly at finite temperature

    International Nuclear Information System (INIS)

    Chaturvedi, S.; Gupte, Neelima; Srinivasan, V.

    1985-01-01

    The Jackiw-Bardeen-Adler anomaly for QED 4 and QED 2 are calculated at finite temperature. It is found that the anomaly is independent of temperature. Ishikawa's method [1984, Phys. Rev. Lett. vol. 53 1615] for calculating the quantised Hall effect is extended to finite temperature. (author)

  10. Skull Defects in Finite Element Head Models for Source Reconstruction from Magnetoencephalography Signals

    Science.gov (United States)

    Lau, Stephan; Güllmar, Daniel; Flemming, Lars; Grayden, David B.; Cook, Mark J.; Wolters, Carsten H.; Haueisen, Jens

    2016-01-01

    Magnetoencephalography (MEG) signals are influenced by skull defects. However, there is a lack of evidence of this influence during source reconstruction. Our objectives are to characterize errors in source reconstruction from MEG signals due to ignoring skull defects and to assess the ability of an exact finite element head model to eliminate such errors. A detailed finite element model of the head of a rabbit used in a physical experiment was constructed from magnetic resonance and co-registered computer tomography imaging that differentiated nine tissue types. Sources of the MEG measurements above intact skull and above skull defects respectively were reconstructed using a finite element model with the intact skull and one incorporating the skull defects. The forward simulation of the MEG signals reproduced the experimentally observed characteristic magnitude and topography changes due to skull defects. Sources reconstructed from measured MEG signals above intact skull matched the known physical locations and orientations. Ignoring skull defects in the head model during reconstruction displaced sources under a skull defect away from that defect. Sources next to a defect were reoriented. When skull defects, with their physical conductivity, were incorporated in the head model, the location and orientation errors were mostly eliminated. The conductivity of the skull defect material non-uniformly modulated the influence on MEG signals. We propose concrete guidelines for taking into account conducting skull defects during MEG coil placement and modeling. Exact finite element head models can improve localization of brain function, specifically after surgery. PMID:27092044

  11. Phonological processing of ignored distractor pictures, an fMRI investigation.

    Science.gov (United States)

    Bles, Mart; Jansma, Bernadette M

    2008-02-11

    Neuroimaging studies of attention often focus on interactions between stimulus representations and top-down selection mechanisms in visual cortex. Less is known about the neural representation of distractor stimuli beyond visual areas, and the interactions between stimuli in linguistic processing areas. In the present study, participants viewed simultaneously presented line drawings at peripheral locations, while in the MRI scanner. The names of the objects depicted in these pictures were either phonologically related (i.e. shared the same consonant-vowel onset construction), or unrelated. Attention was directed either at the linguistic properties of one of these pictures, or at the fixation point (i.e. away from the pictures). Phonological representations of unattended pictures could be detected in the posterior superior temporal gyrus, the inferior frontal gyrus, and the insula. Under some circumstances, the name of ignored distractor pictures is retrieved by linguistic areas. This implies that selective attention to a specific location does not completely filter out the representations of distractor stimuli at early perceptual stages.

  12. Tobacco Usage in Uttarakhand: A Dangerous Combination of High Prevalence, Widespread Ignorance, and Resistance to Quitting

    Directory of Open Access Journals (Sweden)

    Nathan John Grills

    2015-01-01

    Full Text Available Background. Nearly one-third of adults in India use tobacco, resulting in 1.2 million deaths. However, little is known about knowledge, attitudes, and practices (KAP related to smoking in the impoverished state of Uttarakhand. Methods. A cross-sectional epidemiological prevalence survey was undertaken. Multistage cluster sampling selected 20 villages and 50 households to survey from which 1853 people were interviewed. Tobacco prevalence and KAP were analyzed by income level, occupation, age, and sex. 95% confidence intervals were calculated using standard formulas and incorporating assumptions in relation to the clustering effect. Results. The overall prevalence of tobacco usage, defined using WHO criteria, was 38.9%. 93% of smokers and 86% of tobacco chewers were male. Prevalence of tobacco use, controlling for other factors, was associated with lower education, older age, and male sex. 97.6% of users and 98.1% of nonusers wanted less tobacco. Except for lung cancer (89% awareness, awareness of diseases caused by tobacco usage was low (cardiac: 67%; infertility: 32.5%; stroke: 40.5%. Conclusion. A dangerous combination of high tobacco usage prevalence, ignorance about its dangers, and few quit attempts being made suggests the need to develop effective and evidence based interventions to prevent a health and development disaster in Uttarakhand.

  13. Reassessing insurers' access to genetic information: genetic privacy, ignorance, and injustice.

    Science.gov (United States)

    Feiring, Eli

    2009-06-01

    Many countries have imposed strict regulations on the genetic information to which insurers have access. Commentators have warned against the emerging body of legislation for different reasons. This paper demonstrates that, when confronted with the argument that genetic information should be available to insurers for health insurance underwriting purposes, one should avoid appeals to rights of genetic privacy and genetic ignorance. The principle of equality of opportunity may nevertheless warrant restrictions. A choice-based account of this principle implies that it is unfair to hold people responsible for the consequences of the genetic lottery, since we have no choice in selecting our genotype or the expression of it. However appealing, this view does not take us all the way to an adequate justification of inaccessibility of genetic information. A contractarian account, suggesting that health is a condition of opportunity and that healthcare is an essential good, seems more promising. I conclude that if or when predictive medical tests (such as genetic tests) are developed with significant actuarial value, individuals have less reason to accept as fair institutions that limit access to healthcare on the grounds of risk status. Given the assumption that a division of risk pools in accordance with a rough estimate of people's level of (genetic) risk will occur, fairness and justice favour universal health insurance based on solidarity.

  14. Phonological processing of ignored distractor pictures, an fMRI investigation

    Directory of Open Access Journals (Sweden)

    Bles Mart

    2008-02-01

    Full Text Available Abstract Background Neuroimaging studies of attention often focus on interactions between stimulus representations and top-down selection mechanisms in visual cortex. Less is known about the neural representation of distractor stimuli beyond visual areas, and the interactions between stimuli in linguistic processing areas. In the present study, participants viewed simultaneously presented line drawings at peripheral locations, while in the MRI scanner. The names of the objects depicted in these pictures were either phonologically related (i.e. shared the same consonant-vowel onset construction, or unrelated. Attention was directed either at the linguistic properties of one of these pictures, or at the fixation point (i.e. away from the pictures. Results Phonological representations of unattended pictures could be detected in the posterior superior temporal gyrus, the inferior frontal gyrus, and the insula. Conclusion Under some circumstances, the name of ignored distractor pictures is retrieved by linguistic areas. This implies that selective attention to a specific location does not completely filter out the representations of distractor stimuli at early perceptual stages.

  15. IGNORING CHILDREN'S BEDTIME CRYING: THE POWER OF WESTERN-ORIENTED BELIEFS.

    Science.gov (United States)

    Maute, Monique; Perren, Sonja

    2018-03-01

    Ignoring children's bedtime crying (ICBC) is an issue that polarizes parents as well as pediatricians. While most studies have focused on the effectiveness of sleep interventions, no study has yet questioned which parents use ICBC. Parents often find children's sleep difficulties to be very challenging, but factors such as the influence of Western approaches to infant care, stress, and sensitivity have not been analyzed in terms of ICBC. A sample of 586 parents completed a questionnaire to investigate the relationships between parental factors and the method of ICBC. Data were analyzed using structural equation modeling. Latent variables were used to measure parental stress (Parental Stress Scale; J.O. Berry & W.H. Jones, 1995), sensitivity (Situation-Reaction-Questionnaire; Y. Hänggi, K. Schweinberger, N. Gugger, & M. Perrez, 2010), Western-oriented parental beliefs (Rigidity), and children's temperament (Parenting Stress Index; H. Tröster & R.R. Abidin). ICBC was used by 32.6% (n = 191) of parents in this study. Parents' Western-oriented beliefs predicted ICBC. Attitudes such as feeding a child on a time schedule and not carrying it out to prevent dependence were associated with letting the child cry to fall asleep. Low-sensitivity parents as well as parents of children with a difficult temperament used ICBC more frequently. Path analysis shows that parental stress did not predict ICBC. The results suggest that ICBC has become part of Western childrearing tradition. © 2018 Michigan Association for Infant Mental Health.

  16. Behavioural responses to human-induced change: Why fishing should not be ignored.

    Science.gov (United States)

    Diaz Pauli, Beatriz; Sih, Andrew

    2017-03-01

    Change in behaviour is usually the first response to human-induced environmental change and key for determining whether a species adapts to environmental change or becomes maladapted. Thus, understanding the behavioural response to human-induced changes is crucial in the interplay between ecology, evolution, conservation and management. Yet the behavioural response to fishing activities has been largely ignored. We review studies contrasting how fish behaviour affects catch by passive (e.g., long lines, angling) versus active gears (e.g., trawls, seines). We show that fishing not only targets certain behaviours, but it leads to a multitrait response including behavioural, physiological and life-history traits with population, community and ecosystem consequences. Fisheries-driven change (plastic or evolutionary) of fish behaviour and its correlated traits could impact fish populations well beyond their survival per se , affecting predation risk, foraging behaviour, dispersal, parental care, etc., and hence numerous ecological issues including population dynamics and trophic cascades . In particular, we discuss implications of behavioural responses to fishing for fisheries management and population resilience. More research on these topics, however, is needed to draw general conclusions, and we suggest fruitful directions for future studies.

  17. Experimental amplification of an entangled photon: what if the detection loophole is ignored?

    International Nuclear Information System (INIS)

    Pomarico, Enrico; Sanguinetti, Bruno; Sekatski, Pavel; Zbinden, Hugo; Gisin, Nicolas

    2011-01-01

    The experimental verification of quantum features, such as entanglement, at large scales is extremely challenging because of environment-induced decoherence. Indeed, measurement techniques for demonstrating the quantumness of multiparticle systems in the presence of losses are difficult to define, and if they are not sufficiently accurate they can provide wrong conclusions. We present a Bell test where one photon of an entangled pair is amplified and then detected by threshold detectors, whose signals undergo postselection. The amplification is performed by a classical machine, which produces a fully separable micro-macro state. However, by adopting such a technique one can surprisingly observe a violation of the Clauser-Horne-Shimony-Holt inequality. This is due to the fact that ignoring the detection loophole opened by the postselection and the system losses can lead to misinterpretations, such as claiming micro-macro entanglement in a setup where evidently it is not present. By using threshold detectors and postselection, one can only infer the entanglement of the initial pair of photons, and so micro-micro entanglement, as is further confirmed by the violation of a nonseparability criterion for bipartite systems. How to detect photonic micro-macro entanglement in the presence of losses with the currently available technology remains an open question.

  18. Commentary: Ignorance as Bias: Radiolab, Yellow Rain, and “The Fact of the Matter”

    Directory of Open Access Journals (Sweden)

    Paul Hillmer

    2017-12-01

    Full Text Available In 2012 the National Public Radio show “Radiolab” released a podcast (later broadcast on air essentially asserting that Hmong victims of a suspected chemical agent known as “yellow rain” were ignorant of their surroundings and the facts, and were merely victims of exposure, dysentery, tainted water, and other natural causes. Relying heavily on the work of Dr. Matthew Meselson, Dr. Thomas Seeley, and former CIA officer Merle Pribbenow, Radiolab asserted that Hmong victims mistook bee droppings, defecated en masse from flying Asian honey bees, as “yellow rain.” They brought their foregone conclusions to an interview with Eng Yang, a self-described yellow rain survivor, and his niece, memoirist Kao Kalia Yang, who served as translator. The interview went horribly wrong when their dogged belief in the “bee dung hypothesis” was met with stiff and ultimately impassioned opposition. Radiolab’s confirmation bias led them to dismiss contradictory scientific evidence and mislead their audience. While the authors remain agnostic about the potential use of yellow rain in Southeast Asia, they believe the evidence shows that further study is needed before a final conclusion can be reached.

  19. Relativistic finite-temperature Thomas-Fermi model

    Science.gov (United States)

    Faussurier, Gérald

    2017-11-01

    We investigate the relativistic finite-temperature Thomas-Fermi model, which has been proposed recently in an astrophysical context. Assuming a constant distribution of protons inside the nucleus of finite size avoids severe divergence of the electron density with respect to a point-like nucleus. A formula for the nuclear radius is chosen to treat any element. The relativistic finite-temperature Thomas-Fermi model matches the two asymptotic regimes, i.e., the non-relativistic and the ultra-relativistic finite-temperature Thomas-Fermi models. The equation of state is considered in detail. For each version of the finite-temperature Thomas-Fermi model, the pressure, the kinetic energy, and the entropy are calculated. The internal energy and free energy are also considered. The thermodynamic consistency of the three models is considered by working from the free energy. The virial question is also studied in the three cases as well as the relationship with the density functional theory. The relativistic finite-temperature Thomas-Fermi model is far more involved than the non-relativistic and ultra-relativistic finite-temperature Thomas-Fermi models that are very close to each other from a mathematical point of view.

  20. Finite flavour groups of fermions

    International Nuclear Information System (INIS)

    Grimus, Walter; Ludl, Patrick Otto

    2012-01-01

    We present an overview of the theory of finite groups, with regard to their application as flavour symmetries in particle physics. In a general part, we discuss useful theorems concerning group structure, conjugacy classes, representations and character tables. In a specialized part, we attempt to give a fairly comprehensive review of finite subgroups of SO(3) and SU(3), in which we apply and illustrate the general theory. Moreover, we also provide a concise description of the symmetric and alternating groups and comment on the relationship between finite subgroups of U(3) and finite subgroups of SU(3). Although in this review we give a detailed description of a wide range of finite groups, the main focus is on the methods which allow the exploration of their different aspects. (topical review)

  1. On finite quantum field theories

    International Nuclear Information System (INIS)

    Rajpoot, S.; Taylor, J.G.

    1984-01-01

    The properties that make massless versions of N = 4 super Yang-Mills theory and a class of N = 2 supersymmetric theories finite are: (I) a universal coupling for the gauge and matter interactions, (II) anomaly-free representations to which the bosonic and fermionic matter belong, and (III) no charge renormalisation, i.e. β(g) = 0. It was conjectured that field theories constructed out of N = 1 matter multiplets are also finite if they too share the above properties. Explicit calculations have verified these theories to be finite up to two loops. The implications of the finiteness conditions for N = 1 finite field theories with SU(M) gauge symmetry are discussed. (orig.)

  2. Massively Parallel Finite Element Programming

    KAUST Repository

    Heister, Timo

    2010-01-01

    Today\\'s large finite element simulations require parallel algorithms to scale on clusters with thousands or tens of thousands of processor cores. We present data structures and algorithms to take advantage of the power of high performance computers in generic finite element codes. Existing generic finite element libraries often restrict the parallelization to parallel linear algebra routines. This is a limiting factor when solving on more than a few hundreds of cores. We describe routines for distributed storage of all major components coupled with efficient, scalable algorithms. We give an overview of our effort to enable the modern and generic finite element library deal.II to take advantage of the power of large clusters. In particular, we describe the construction of a distributed mesh and develop algorithms to fully parallelize the finite element calculation. Numerical results demonstrate good scalability. © 2010 Springer-Verlag.

  3. Massively Parallel Finite Element Programming

    KAUST Repository

    Heister, Timo; Kronbichler, Martin; Bangerth, Wolfgang

    2010-01-01

    Today's large finite element simulations require parallel algorithms to scale on clusters with thousands or tens of thousands of processor cores. We present data structures and algorithms to take advantage of the power of high performance computers in generic finite element codes. Existing generic finite element libraries often restrict the parallelization to parallel linear algebra routines. This is a limiting factor when solving on more than a few hundreds of cores. We describe routines for distributed storage of all major components coupled with efficient, scalable algorithms. We give an overview of our effort to enable the modern and generic finite element library deal.II to take advantage of the power of large clusters. In particular, we describe the construction of a distributed mesh and develop algorithms to fully parallelize the finite element calculation. Numerical results demonstrate good scalability. © 2010 Springer-Verlag.

  4. Finite discrete field theory

    International Nuclear Information System (INIS)

    Souza, Manoelito M. de

    1997-01-01

    We discuss the physical meaning and the geometric interpretation of implementation in classical field theories. The origin of infinities and other inconsistencies in field theories is traced to fields defined with support on the light cone; a finite and consistent field theory requires a light-cone generator as the field support. Then, we introduce a classical field theory with support on the light cone generators. It results on a description of discrete (point-like) interactions in terms of localized particle-like fields. We find the propagators of these particle-like fields and discuss their physical meaning, properties and consequences. They are conformally invariant, singularity-free, and describing a manifestly covariant (1 + 1)-dimensional dynamics in a (3 = 1) spacetime. Remarkably this conformal symmetry remains even for the propagation of a massive field in four spacetime dimensions. We apply this formalism to Classical electrodynamics and to the General Relativity Theory. The standard formalism with its distributed fields is retrieved in terms of spacetime average of the discrete field. Singularities are the by-products of the averaging process. This new formalism enlighten the meaning and the problem of field theory, and may allow a softer transition to a quantum theory. (author)

  5. Mimetic finite difference method

    Science.gov (United States)

    Lipnikov, Konstantin; Manzini, Gianmarco; Shashkov, Mikhail

    2014-01-01

    The mimetic finite difference (MFD) method mimics fundamental properties of mathematical and physical systems including conservation laws, symmetry and positivity of solutions, duality and self-adjointness of differential operators, and exact mathematical identities of the vector and tensor calculus. This article is the first comprehensive review of the 50-year long history of the mimetic methodology and describes in a systematic way the major mimetic ideas and their relevance to academic and real-life problems. The supporting applications include diffusion, electromagnetics, fluid flow, and Lagrangian hydrodynamics problems. The article provides enough details to build various discrete operators on unstructured polygonal and polyhedral meshes and summarizes the major convergence results for the mimetic approximations. Most of these theoretical results, which are presented here as lemmas, propositions and theorems, are either original or an extension of existing results to a more general formulation using polyhedral meshes. Finally, flexibility and extensibility of the mimetic methodology are shown by deriving higher-order approximations, enforcing discrete maximum principles for diffusion problems, and ensuring the numerical stability for saddle-point systems.

  6. Finite element and finite difference methods in electromagnetic scattering

    CERN Document Server

    Morgan, MA

    2013-01-01

    This second volume in the Progress in Electromagnetic Research series examines recent advances in computational electromagnetics, with emphasis on scattering, as brought about by new formulations and algorithms which use finite element or finite difference techniques. Containing contributions by some of the world's leading experts, the papers thoroughly review and analyze this rapidly evolving area of computational electromagnetics. Covering topics ranging from the new finite-element based formulation for representing time-harmonic vector fields in 3-D inhomogeneous media using two coupled sca

  7. Size Matters: Individual Variation in Ectotherm Growth and Asymptotic Size.

    Directory of Open Access Journals (Sweden)

    Richard B King

    Full Text Available Body size, and, by extension, growth has impacts on physiology, survival, attainment of sexual maturity, fecundity, generation time, and population dynamics, especially in ectotherm animals that often exhibit extensive growth following attainment of sexual maturity. Frequently, growth is analyzed at the population level, providing useful population mean growth parameters but ignoring individual variation that is also of ecological and evolutionary significance. Our long-term study of Lake Erie Watersnakes, Nerodia sipedon insularum, provides data sufficient for a detailed analysis of population and individual growth. We describe population mean growth separately for males and females based on size of known age individuals (847 captures of 769 males, 748 captures of 684 females and annual growth increments of individuals of unknown age (1,152 males, 730 females. We characterize individual variation in asymptotic size based on repeated measurements of 69 males and 71 females that were each captured in five to nine different years. The most striking result of our analyses is that asymptotic size varies dramatically among individuals, ranging from 631-820 mm snout-vent length in males and from 835-1125 mm in females. Because female fecundity increases with increasing body size, we explore the impact of individual variation in asymptotic size on lifetime reproductive success using a range of realistic estimates of annual survival. When all females commence reproduction at the same age, lifetime reproductive success is greatest for females with greater asymptotic size regardless of annual survival. But when reproduction is delayed in females with greater asymptotic size, lifetime reproductive success is greatest for females with lower asymptotic size when annual survival is low. Possible causes of individual variation in asymptotic size, including individual- and cohort-specific variation in size at birth and early growth, warrant further

  8. Size Matters: Individual Variation in Ectotherm Growth and Asymptotic Size

    Science.gov (United States)

    King, Richard B.

    2016-01-01

    Body size, and, by extension, growth has impacts on physiology, survival, attainment of sexual maturity, fecundity, generation time, and population dynamics, especially in ectotherm animals that often exhibit extensive growth following attainment of sexual maturity. Frequently, growth is analyzed at the population level, providing useful population mean growth parameters but ignoring individual variation that is also of ecological and evolutionary significance. Our long-term study of Lake Erie Watersnakes, Nerodia sipedon insularum, provides data sufficient for a detailed analysis of population and individual growth. We describe population mean growth separately for males and females based on size of known age individuals (847 captures of 769 males, 748 captures of 684 females) and annual growth increments of individuals of unknown age (1,152 males, 730 females). We characterize individual variation in asymptotic size based on repeated measurements of 69 males and 71 females that were each captured in five to nine different years. The most striking result of our analyses is that asymptotic size varies dramatically among individuals, ranging from 631–820 mm snout-vent length in males and from 835–1125 mm in females. Because female fecundity increases with increasing body size, we explore the impact of individual variation in asymptotic size on lifetime reproductive success using a range of realistic estimates of annual survival. When all females commence reproduction at the same age, lifetime reproductive success is greatest for females with greater asymptotic size regardless of annual survival. But when reproduction is delayed in females with greater asymptotic size, lifetime reproductive success is greatest for females with lower asymptotic size when annual survival is low. Possible causes of individual variation in asymptotic size, including individual- and cohort-specific variation in size at birth and early growth, warrant further investigation. PMID

  9. A simple approach to ignoring irrelevant variables by population decoding based on multisensory neurons

    Science.gov (United States)

    Kim, HyungGoo R.; Pitkow, Xaq; Angelaki, Dora E.

    2016-01-01

    Sensory input reflects events that occur in the environment, but multiple events may be confounded in sensory signals. For example, under many natural viewing conditions, retinal image motion reflects some combination of self-motion and movement of objects in the world. To estimate one stimulus event and ignore others, the brain can perform marginalization operations, but the neural bases of these operations are poorly understood. Using computational modeling, we examine how multisensory signals may be processed to estimate the direction of self-motion (i.e., heading) and to marginalize out effects of object motion. Multisensory neurons represent heading based on both visual and vestibular inputs and come in two basic types: “congruent” and “opposite” cells. Congruent cells have matched heading tuning for visual and vestibular cues and have been linked to perceptual benefits of cue integration during heading discrimination. Opposite cells have mismatched visual and vestibular heading preferences and are ill-suited for cue integration. We show that decoding a mixed population of congruent and opposite cells substantially reduces errors in heading estimation caused by object motion. In addition, we present a general formulation of an optimal linear decoding scheme that approximates marginalization and can be implemented biologically by simple reinforcement learning mechanisms. We also show that neural response correlations induced by task-irrelevant variables may greatly exceed intrinsic noise correlations. Overall, our findings suggest a general computational strategy by which neurons with mismatched tuning for two different sensory cues may be decoded to perform marginalization operations that dissociate possible causes of sensory inputs. PMID:27334948

  10. Ignorance is no excuse for directors minimizing information asymmetry affecting boards

    Directory of Open Access Journals (Sweden)

    Eythor Ivar Jonsson

    2006-11-01

    Full Text Available This paper looks at information asymmetry at the board level and how lack of information has played a part in undermining the power of the board of directors. Information is power, and at board level, information is essential to keep the board knowledgeable about the failures and successes of the organization that it is supposed to govern. Although lack of information has become a popular excuse for boards, the mantra could –and should –be changing to, “Ignorance is no excuse” (Mueller, 1993. This paper explores some of these information system solutions that have the aim of resolving some of the problems of information asymmetry. Furthermore, three case studies are used to explore the problem of asymmetric information at board level and the how the boards are trying to solve the problem. The focus of the discussion is to a describe how directors experience the information asymmetry and if they find it troublesome, b how important information is for the control and strategy role of the board and c find out how boards can minimize the problem of asymmetric information. The research is conducted through semi-structured interviews with directors, managers and accountants. This paper offers an interesting exploration into information, or the lack of information, at board level. It describes both from a theoretical and practical viewpoint the problem of information asymmetry at board level and how companies are trying to solve this problem. It is an issue that has only been lightly touched upon in the corporate governance literature but is likely to attract more attention and research in the future.

  11. Ignoring detailed fast-changing dynamics of land use overestimates regional terrestrial carbon sequestration

    Directory of Open Access Journals (Sweden)

    S. Q. Zhao

    2009-08-01

    Full Text Available Land use change is critical in determining the distribution, magnitude and mechanisms of terrestrial carbon budgets at the local to global scales. To date, almost all regional to global carbon cycle studies are driven by a static land use map or land use change statistics with decadal time intervals. The biases in quantifying carbon exchange between the terrestrial ecosystems and the atmosphere caused by using such land use change information have not been investigated. Here, we used the General Ensemble biogeochemical Modeling System (GEMS, along with consistent and spatially explicit land use change scenarios with different intervals (1 yr, 5 yrs, 10 yrs and static, respectively, to evaluate the impacts of land use change data frequency on estimating regional carbon sequestration in the southeastern United States. Our results indicate that ignoring the detailed fast-changing dynamics of land use can lead to a significant overestimation of carbon uptake by the terrestrial ecosystem. Regional carbon sequestration increased from 0.27 to 0.69, 0.80 and 0.97 Mg C ha−1 yr−1 when land use change data frequency shifting from 1 year to 5 years, 10 years interval and static land use information, respectively. Carbon removal by forest harvesting and prolonged cumulative impacts of historical land use change on carbon cycle accounted for the differences in carbon sequestration between static and dynamic land use change scenarios. The results suggest that it is critical to incorporate the detailed dynamics of land use change into local to global carbon cycle studies. Otherwise, it is impossible to accurately quantify the geographic distributions, magnitudes, and mechanisms of terrestrial carbon sequestration at the local to global scales.

  12. Alternating-time temporal logic with finite-memory strategies

    DEFF Research Database (Denmark)

    Vester, Steen

    2013-01-01

    on finite-memory strategies. One where the memory size allowed is bounded and one where the memory size is unbounded (but must be finite). This is motivated by the high complexity of model-checking with perfect recall semantics and the severe limitations of memoryless strategies. We show that both types...... of semantics introduced are different from perfect recall and memoryless semantics and next focus on the decidability and complexity of model-checking in both complete and incomplete information games for ATL/ATL*. In particular, we show that the complexity of model-checking with bounded-memory semantics...... is Delta_2p-complete for ATL and PSPACE-complete for ATL* in incomplete information games just as in the memoryless case. We also present a proof that ATL and ATL* model-checking is undecidable for n >= 3 players with finite-memory semantics in incomplete information games....

  13. Finite dipolar hexagonal columns on piled layers of triangular lattice

    International Nuclear Information System (INIS)

    Matsushita, Katsuyoshi; Sugano, Ryoko; Kuroda, Akiyoshi; Tomita, Yusuke; Takayama, Hajime

    2007-01-01

    We have investigated, by the Monte Carlo simulation, spin systems which represent moments of arrayed magnetic nanoparticles interacting with each other only by the dipole-dipole interaction. In the present paper we aim the understanding of finite size effects on the magnetic nanoparticles arrayed in hexagonal columns cut out from the close-packing structures or from those with uniaxial compression. In columns with the genuine close-packing structures, we observe a single vortex state which is also observed previously in finite two-dimensional systems. On the other hand in the system with the inter-layer distance set 1/2 times of the close-packing one, we found ground states which depend on the number of layers. The dependence is induced by a finite size effect and is related to a orientation transition in the corresponding bulk system

  14. Finite spatial volume approach to finite temperature field theory

    International Nuclear Information System (INIS)

    Weiss, Nathan

    1981-01-01

    A relativistic quantum field theory at finite temperature T=β -1 is equivalent to the same field theory at zero temperature but with one spatial dimension of finite length β. This equivalence is discussed for scalars, for fermions, and for gauge theories. The relationship is checked for free field theory. The translation of correlation functions between the two formulations is described with special emphasis on the nonlocal order parameters of gauge theories. Possible applications are mentioned. (auth)

  15. Automatic Construction of Finite Algebras

    Institute of Scientific and Technical Information of China (English)

    张健

    1995-01-01

    This paper deals with model generation for equational theories,i.e.,automatically generating (finite)models of a given set of (logical) equations.Our method of finite model generation and a tool for automatic construction of finite algebras is described.Some examples are given to show the applications of our program.We argue that,the combination of model generators and theorem provers enables us to get a better understanding of logical theories.A brief comparison betwween our tool and other similar tools is also presented.

  16. Photon propagators at finite temperature

    International Nuclear Information System (INIS)

    Yee, J.H.

    1982-07-01

    We have used the real time formalism to compute the one-loop finite temperature corrections to the photon self energies in spinor and scalar QED. We show that, for a real photon, only the transverse components develop the temperature-dependent masses, while, for an external static electromagnetic field applied to the finite temperature system, only the static electric field is screened by thermal fluctuations. After showing how to compute systematically the imaginary parts of the finite temperature Green functions, we have attempted to give a microscopic interpretation of the imaginary parts of the self energies. (author)

  17. Observations on finite quantum mechanics

    International Nuclear Information System (INIS)

    Balian, R.; Itzykson, C.

    1986-01-01

    We study the canonical transformations of the quantum mechanics on a finite phase space. For simplicity we assume that the configuration variable takes an odd prime number 4 K±1 of distinct values. We show that the canonical group is unitarily implemented. It admits a maximal abelian subgroup of order 4 K, commuting with the finite Fourier transform F, a finite analogue of the harmonic oscillator group. This provides a natural construction of F 1/K and of an orthogonal basis of eigenstates of F [fr

  18. Sophisticated Approval Voting, Ignorance Priors, and Plurality Heuristics: A Behavioral Social Choice Analysis in a Thurstonian Framework

    Science.gov (United States)

    Regenwetter, Michel; Ho, Moon-Ho R.; Tsetlin, Ilia

    2007-01-01

    This project reconciles historically distinct paradigms at the interface between individual and social choice theory, as well as between rational and behavioral decision theory. The authors combine a utility-maximizing prescriptive rule for sophisticated approval voting with the ignorance prior heuristic from behavioral decision research and two…

  19. Learning to Ignore: A Modeling Study of a Decremental Cholinergic Pathway and Its Influence on Attention and Learning

    Science.gov (United States)

    Oros, Nicolas; Chiba, Andrea A.; Nitz, Douglas A.; Krichmar, Jeffrey L.

    2014-01-01

    Learning to ignore irrelevant stimuli is essential to achieving efficient and fluid attention, and serves as the complement to increasing attention to relevant stimuli. The different cholinergic (ACh) subsystems within the basal forebrain regulate attention in distinct but complementary ways. ACh projections from the substantia innominata/nucleus…

  20. Settlers Unsettled: Using Field Schools and Digital Stories to Transform Geographies of Ignorance about Indigenous Peoples in Canada

    Science.gov (United States)

    Castleden, Heather; Daley, Kiley; Sloan Morgan, Vanessa; Sylvestre, Paul

    2013-01-01

    Geography is a product of colonial processes, and in Canada, the exclusion from educational curricula of Indigenous worldviews and their lived realities has produced "geographies of ignorance". Transformative learning is an approach geographers can use to initiate changes in non-Indigenous student attitudes about Indigenous…

  1. The Ignorant Environmental Education Teacher: Students Get Empowered and Teach Philosophy of Nature Inspired by Ancient Greek Philosophy

    Science.gov (United States)

    Tsevreni, Irida

    2018-01-01

    This paper presents an attempt to apply Jacques Rancière's emancipatory pedagogy of "the ignorant schoolmaster" to environmental education, which emphasises environmental ethics. The paper tells the story of a philosophy of nature project in the framework of an environmental adult education course at a Second Chance School in Greece,…

  2. Customer-oriented finite perturbation analysis for queueing networks

    NARCIS (Netherlands)

    Heidergott, B.F.

    2000-01-01

    We consider queueing networks for which the performance measureJ ( ) depends on a parameter , which can be a service time parameter or a buffer size, and we are interested in sensitivity analysis of J ( ) with respect to . We introduce a new method, called customer-oriented finite perturbation

  3. Using a satisfiability solver to identify deterministic finite state automata

    NARCIS (Netherlands)

    Heule, M.J.H.; Verwer, S.

    2009-01-01

    We present an exact algorithm for identification of deterministic finite automata (DFA) which is based on satisfiability (SAT) solvers. Despite the size of the low level SAT representation, our approach seems to be competitive with alternative techniques. Our contributions are threefold: First, we

  4. Finite element computational fluid mechanics

    International Nuclear Information System (INIS)

    Baker, A.J.

    1983-01-01

    This book analyzes finite element theory as applied to computational fluid mechanics. It includes a chapter on using the heat conduction equation to expose the essence of finite element theory, including higher-order accuracy and convergence in a common knowledge framework. Another chapter generalizes the algorithm to extend application to the nonlinearity of the Navier-Stokes equations. Other chapters are concerned with the analysis of a specific fluids mechanics problem class, including theory and applications. Some of the topics covered include finite element theory for linear mechanics; potential flow; weighted residuals/galerkin finite element theory; inviscid and convection dominated flows; boundary layers; parabolic three-dimensional flows; and viscous and rotational flows

  5. Programming the finite element method

    CERN Document Server

    Smith, I M; Margetts, L

    2013-01-01

    Many students, engineers, scientists and researchers have benefited from the practical, programming-oriented style of the previous editions of Programming the Finite Element Method, learning how to develop computer programs to solve specific engineering problems using the finite element method. This new fifth edition offers timely revisions that include programs and subroutine libraries fully updated to Fortran 2003, which are freely available online, and provides updated material on advances in parallel computing, thermal stress analysis, plasticity return algorithms, convection boundary c

  6. Incompleteness in the finite domain

    Czech Academy of Sciences Publication Activity Database

    Pudlák, Pavel

    2017-01-01

    Roč. 23, č. 4 (2017), s. 405-441 ISSN 1079-8986 EU Projects: European Commission(XE) 339691 - FEALORA Institutional support: RVO:67985840 Keywords : finite domain Subject RIV: BA - General Mathematics OBOR OECD: Pure mathematics Impact factor: 0.742, year: 2016 https://www.cambridge.org/core/journals/bulletin-of-symbolic-logic/article/incompleteness-in-the-finite-domain/D239B1761A73DCA534A4805A76D81C76

  7. Symbolic computation with finite biquandles

    OpenAIRE

    Creel, Conrad; Nelson, Sam

    2007-01-01

    A method of computing a basis for the second Yang-Baxter cohomology of a finite biquandle with coefficients in Q and Z_p from a matrix presentation of the finite biquandle is described. We also describe a method for computing the Yang-Baxter cocycle invariants of an oriented knot or link represented as a signed Gauss code. We provide a URL for our Maple implementations of these algorithms.

  8. Ignorance, Vulnerability and the Occurrence of "Radical Surprises": Theoretical Reflections and Empirical Findings

    Science.gov (United States)

    Kuhlicke, C.

    2009-04-01

    By definition natural disasters always contain a moment of surprise. Their occurrence is mostly unforeseen and unexpected. They hit people unprepared, overwhelm them and expose their helplessness. Yet, there is surprisingly little known on the reasons for their being surprised. Aren't natural disasters expectable and foreseeable after all? Aren't the return rates of most hazards well known and shouldn't people be better prepared? The central question of this presentation is hence: Why do natural disasters so often radically surprise people at all (and how can we explain this being surprised)? In the first part of the presentation, it is argued that most approaches to vulnerability are not able to grasp this moment of surprise. On the contrary, they have their strength in unravelling the expectable: A person who is marginalized or even oppressed in everyday life is also vulnerable during times of crisis and stress, at least this is the central assumption of most vulnerability studies. In the second part, an understanding of vulnerability is developed, which allows taking into account such radical surprises. First, two forms of the unknown are differentiated: An area of the unknown an actor is more or less aware of (ignorance), and an area, which is not even known to be not known (nescience). The discovery of the latter is mostly associated with a "radical surprise", since it is per definition impossible to prepare for it. Second, a definition of vulnerability is proposed, which allows capturing the dynamics of surprises: People are vulnerable when they discover their nescience exceeding by definition previously established routines, stocks of knowledge and resources—in a general sense their capacities—to deal with their physical and/or social environment. This definition explicitly takes the view of different actors serious and departs from their being surprised. In the third part findings of a case study are presented, the 2002 flood in Germany. It is shown

  9. Finite nucleus Dirac mean field theory and random phase approximation using finite B splines

    International Nuclear Information System (INIS)

    McNeil, J.A.; Furnstahl, R.J.; Rost, E.; Shepard, J.R.; Department of Physics, University of Maryland, College Park, Maryland 20742; Department of Physics, University of Colorado, Boulder, Colorado 80309)

    1989-01-01

    We calculate the finite nucleus Dirac mean field spectrum in a Galerkin approach using finite basis splines. We review the method and present results for the relativistic σ-ω model for the closed-shell nuclei 16 O and 40 Ca. We study the convergence of the method as a function of the size of the basis and the closure properties of the spectrum using an energy-weighted dipole sum rule. We apply the method to the Dirac random-phase-approximation response and present results for the isoscalar 1/sup -/ and 3/sup -/ longitudinal form factors of 16 O and 40 Ca. We also use a B-spline spectral representation of the positive-energy projector to evaluate partial energy-weighted sum rules and compare with nonrelativistic sum rule results

  10. Portion size

    Science.gov (United States)

    ... of cards One 3-ounce (84 grams) serving of fish is a checkbook One-half cup (40 grams) ... for the smallest size. By eating a small hamburger instead of a large, you will save about 150 calories. ...

  11. Investigation of faulted tunnel models by combined photoelasticity and finite element analysis

    International Nuclear Information System (INIS)

    Ladkany, S.G.; Huang, Yuping

    1994-01-01

    Models of square and circular tunnels with short faults cutting through their surfaces are investigated by photoelasticity. These models, when duplicated by finite element analysis can predict the stress states of square or circular faulted tunnels adequately. Finite element analysis, using gap elements, may be used to investigate full size faulted tunnel system

  12. Firm-size distribution and price-cost margins in Dutch manufacturing

    NARCIS (Netherlands)

    Y.M. Prince (Yvonne); A.R. Thurik (Roy)

    1993-01-01

    textabstractIndustrial economists surmise a relation between the size distribution of firms and performance. Usually, attention is focused on the high end of the size distribution. The widely used 4-firm seller concentration, C4, ignores what happens at the low end of the size distribution. An

  13. Probabilistic Estimation of Critical Flaw Sizes in the Primary Structure Welds of the Ares I-X Launch Vehicle

    Science.gov (United States)

    Pai, Shantaram S.; Hoge, Peter A.; Patel, B. M.; Nagpal, Vinod K.

    2009-01-01

    The primary structure of the Ares I-X Upper Stage Simulator (USS) launch vehicle is constructed of welded mild steel plates. There is some concern over the possibility of structural failure due to welding flaws. It was considered critical to quantify the impact of uncertainties in residual stress, material porosity, applied loads, and material and crack growth properties on the reliability of the welds during its pre-flight and flight. A criterion--an existing maximum size crack at the weld toe must be smaller than the maximum allowable flaw size--was established to estimate the reliability of the welds. A spectrum of maximum allowable flaw sizes was developed for different possible combinations of all of the above listed variables by performing probabilistic crack growth analyses using the ANSYS finite element analysis code in conjunction with the NASGRO crack growth code. Two alternative methods were used to account for residual stresses: (1) The mean residual stress was assumed to be 41 ksi and a limit was set on the net section flow stress during crack propagation. The critical flaw size was determined by parametrically increasing the initial flaw size and detecting if this limit was exceeded during four complete flight cycles, and (2) The mean residual stress was assumed to be 49.6 ksi (the parent material s yield strength) and the net section flow stress limit was ignored. The critical flaw size was determined by parametrically increasing the initial flaw size and detecting if catastrophic crack growth occurred during four complete flight cycles. Both surface-crack models and through-crack models were utilized to characterize cracks in the weld toe.

  14. Do Not ignore pulmonary hypertension any longer. It’s time to deal with it!

    Directory of Open Access Journals (Sweden)

    Ahmad Mirdamadi

    2011-08-01

    tromboembolic attacks in check.Then,It was time of revolution in pulmonary hypertension management,With the emergence of Advanced PH treatment science of medicine became able to seriously deal with  PH.This new strategy were showed to be able preventing mortality in PH patients’(5,Figure1Prostacycline showed that it is possible to enhance PH patients’ chance of survival. Phosphodiasterase inhibitor drugs, which were used for treating impotency for a long time, were demonstrated to be effective for reducing pulmonary pressure. Eventually, endotheline receptors were targeted.By the advent of endothelin receptor blockers such as Brosentan, physicians’ chances of helping PH patients were further improved.Today, with advanced PH treatment, PH is not counted as before and the science of medicine as a failed discipline.It is important to not forgetting PH in patients,especially ill patients or intractable to traditional treatment, in surgery wards or obstetric,pediatric,internal medicine,ICU or CCU wards of hospitals. By timely diagnosis, it will be possible to control  PH patients in an effective way and to enhance their chance of survival.So,It is time now to pay more attention to PH,Don’t ignore it any longer and it’s time to deal with it

  15. Optimization of thermal systems based on finite-time thermodynamics and thermoeconomics

    Energy Technology Data Exchange (ETDEWEB)

    Durmayaz, A. [Istanbul Technical University (Turkey). Department of Mechanical Engineering; Sogut, O.S. [Istanbul Technical University, Maslak (Turkey). Department of Naval Architecture and Ocean Engineering; Sahin, B. [Yildiz Technical University, Besiktas, Istanbul (Turkey). Department of Naval Architecture; Yavuz, H. [Istanbul Technical University, Maslak (Turkey). Institute of Energy

    2004-07-01

    The irreversibilities originating from finite-time and finite-size constraints are important in the real thermal system optimization. Since classical thermodynamic analysis based on thermodynamic equilibrium do not consider these constraints directly, it is necessary to consider the energy transfer between the system and its surroundings in the rate form. Finite-time thermodynamics provides a fundamental starting point for the optimization of real thermal systems including the fundamental concepts of heat transfer and fluid mechanics to classical thermodynamics. In this study, optimization studies of thermal systems, that consider various objective functions, based on finite-time thermodynamics and thermoeconomics are reviewed. (author)

  16. Ignoring 'Best Practice': why Irish software SMEs are rejecting CMMI and ISO 9000

    OpenAIRE

    O'Connor, Rory V.; Coleman, Gerry

    2009-01-01

    peer-reviewed Software Process Improvement (SPI) "best practice" models such as ISO 9000 and the Capability Maturity Model Integrated (CMMI) have been developed to assist software development organisations by harnessing their experience and providing them with support so that they can produce software products on time, within budget and to a high level of quality. However there is increasing evidence that these models are not being adopted by Small and Medium sized Enterprises ...

  17. Preconditioning for Mixed Finite Element Formulations of Elliptic Problems

    KAUST Repository

    Wildey, Tim; Xue, Guangri

    2013-01-01

    In this paper, we discuss a preconditioning technique for mixed finite element discretizations of elliptic equations. The technique is based on a block-diagonal approximation of the mass matrix which maintains the sparsity and positive definiteness of the corresponding Schur complement. This preconditioner arises from the multipoint flux mixed finite element method and is robust with respect to mesh size and is better conditioned for full permeability tensors than a preconditioner based on a diagonal approximation of the mass matrix. © Springer-Verlag Berlin Heidelberg 2013.

  18. Different radiation impedance models for finite porous materials

    DEFF Research Database (Denmark)

    Nolan, Melanie; Jeong, Cheol-Ho; Brunskog, Jonas

    2015-01-01

    The Sabine absorption coefficients of finite absorbers are measured in a reverberation chamber according to the international standard ISO 354. They vary with the specimen size essentially due to diffraction at the specimen edges, which can be seen as the radiation impedance differing from...... the infinite case. Thus, in order to predict the Sabine absorption coefficients of finite porous samples, one can incorporate models of the radiation impedance. In this study, different radiation impedance models are compared with two experimental examples. Thomasson’s model is compared to Rhazi’s method when...

  19. Sustainable Sizing.

    Science.gov (United States)

    Robinette, Kathleen M; Veitch, Daisy

    2016-08-01

    To provide a review of sustainable sizing practices that reduce waste, increase sales, and simultaneously produce safer, better fitting, accommodating products. Sustainable sizing involves a set of methods good for both the environment (sustainable environment) and business (sustainable business). Sustainable sizing methods reduce (1) materials used, (2) the number of sizes or adjustments, and (3) the amount of product unsold or marked down for sale. This reduces waste and cost. The methods can also increase sales by fitting more people in the target market and produce happier, loyal customers with better fitting products. This is a mini-review of methods that result in more sustainable sizing practices. It also reviews and contrasts current statistical and modeling practices that lead to poor fit and sizing. Fit-mapping and the use of cases are two excellent methods suited for creating sustainable sizing, when real people (vs. virtual people) are used. These methods are described and reviewed. Evidence presented supports the view that virtual fitting with simulated people and products is not yet effective. Fit-mapping and cases with real people and actual products result in good design and products that are fit for person, fit for purpose, with good accommodation and comfortable, optimized sizing. While virtual models have been shown to be ineffective for predicting or representing fit, there is an opportunity to improve them by adding fit-mapping data to the models. This will require saving fit data, product data, anthropometry, and demographics in a standardized manner. For this success to extend to the wider design community, the development of a standardized method of data collection for fit-mapping with a globally shared fit-map database is needed. It will enable the world community to build knowledge of fit and accommodation and generate effective virtual fitting for the future. A standardized method of data collection that tests products' fit methodically

  20. Size matter!

    DEFF Research Database (Denmark)

    Hansen, Pelle Guldborg; Jespersen, Andreas Maaløe; Skov, Laurits Rhoden

    2015-01-01

    trash bags according to size of plates and weighed in bulk. Results Those eating from smaller plates (n=145) left significantly less food to waste (aver. 14,8g) than participants eating from standard plates (n=75) (aver. 20g) amounting to a reduction of 25,8%. Conclusions Our field experiment tests...... the hypothesis that a decrease in the size of food plates may lead to significant reductions in food waste from buffets. It supports and extends the set of circumstances in which a recent experiment found that reduced dinner plates in a hotel chain lead to reduced quantities of leftovers....

  1. Finiteness of quantum field theories and supersymmetry

    International Nuclear Information System (INIS)

    Lucha, W.; Neufeld, H.

    1986-01-01

    We study the consequences of finiteness for a general renormalizable quantum field theory by analysing the finiteness conditions resulting from the requirement of absence of divergent contributions to the renormalizations of the parameters of an arbitrary gauge theory. In all cases considered, the well-known two-loop finite supersymmetric theories prove to be the unique solution of the finiteness criterion. (Author)

  2. Toward finite quantum field theories

    International Nuclear Information System (INIS)

    Rajpoot, S.; Taylor, J.G.

    1986-01-01

    The properties that make the N=4 super Yang-Mills theory free from ultraviolet divergences are (i) a universal coupling for gauge and matter interactions, (ii) anomaly-free representations, (iii) no charge renormalization, and (iv) if masses are explicitly introduced into the theory, then these are required to satisfy the mass-squared supertrace sum rule Σsub(s=0.1/2)(-1)sup(2s+1)(2s+1)M 2 sub(s)=O. Finite N=2 theories are found to satisfy the above criteria. The missing member in this class of field theories are finite field theories consisting of N=1 superfields. These theories are discussed in the light of the above finiteness properties. In particular, the representations of all simple classical groups satisfying the anomaly-free and no-charge renormalization conditions for finite N=1 field theories are discussed. A consequence of these restrictions on the allowed representations is that an N=1 finite SU(5)-based model of strong and electroweak interactions can contain at most five conventional families of quarks and leptons, a constraint almost compatible with the one deduced from cosmological arguments. (author)

  3. Intranasal oxytocin impedes the ability to ignore task-irrelevant facial expressions of sadness in students with depressive symptoms.

    Science.gov (United States)

    Ellenbogen, Mark A; Linnen, Anne-Marie; Cardoso, Christopher; Joober, Ridha

    2013-03-01

    The administration of oxytocin promotes prosocial behavior in humans. The mechanism by which this occurs is unknown, but it likely involves changes in social information processing. In a randomized placebo-controlled study, we examined the influence of intranasal oxytocin and placebo on the interference control component of inhibition (i.e. ability to ignore task-irrelevant information) in 102 participants using a negative affective priming task with sad, angry, and happy faces. In this task, participants are instructed to respond to a facial expression of emotion while simultaneously ignoring another emotional face. On the subsequent trial, the previously-ignored emotional valence may become the emotional valence of the target face. Inhibition is operationalized as the differential delay between responding to a previously-ignored emotional valence and responding to an emotional valence unrelated to the previous one. Although no main effect of drug administration on inhibition was observed, a drug × depressive symptom interaction (β = -0.25; t = -2.6, p < 0.05) predicted the inhibition of sad faces. Relative to placebo, participants with high depression scores who were administered oxytocin were unable to inhibit the processing of sad faces. There was no relationship between drug administration and inhibition among those with low depression scores. These findings are consistent with increasing evidence that oxytocin alters social information processing in ways that have both positive and negative social outcomes. Because elevated depression scores are associated with an increased risk for major depressive disorder, difficulties inhibiting mood-congruent stimuli following oxytocin administration may be associated with risk for depression. Copyright © 2012 Elsevier Ltd. All rights reserved.

  4. Cross-modal selective attention: on the difficulty of ignoring sounds at the locus of visual attention.

    Science.gov (United States)

    Spence, C; Ranson, J; Driver, J

    2000-02-01

    In three experiments, we investigated whether the ease with which distracting sounds can be ignored depends on their distance from fixation and from attended visual events. In the first experiment, participants shadowed an auditory stream of words presented behind their heads, while simultaneously fixating visual lip-read information consistent with the relevant auditory stream, or meaningless "chewing" lip movements. An irrelevant auditory stream of words, which participants had to ignore, was presented either from the same side as the fixated visual stream or from the opposite side. Selective shadowing was less accurate in the former condition, implying that distracting sounds are harder to ignore when fixated. Furthermore, the impairment when fixating toward distractor sounds was greater when speaking lips were fixated than when chewing lips were fixated, suggesting that people find it particularly difficult to ignore sounds at locations that are actively attended for visual lipreading rather than merely passively fixated. Experiments 2 and 3 tested whether these results are specific to cross-modal links in speech perception by replacing the visual lip movements with a rapidly changing stream of meaningless visual shapes. The auditory task was again shadowing, but the active visual task was now monitoring for a specific visual shape at one location. A decrement in shadowing was again observed when participants passively fixated toward the irrelevant auditory stream. This decrement was larger when participants performed a difficult active visual task there versus fixating, but not for a less demanding visual task versus fixation. The implications for cross-modal links in spatial attention are discussed.

  5. Exploring Size.

    Science.gov (United States)

    Brand, Judith, Ed.

    1995-01-01

    "Exploring" is a magazine of science, art, and human perception that communicates ideas museum exhibits cannot demonstrate easily by using experiments and activities for the classroom. This issue concentrates on size, examining it from a variety of viewpoints. The focus allows students to investigate and discuss interconnections among…

  6. Research on injury compensation and health outcomes: ignoring the problem of reverse causality led to a biased conclusion.

    Science.gov (United States)

    Spearing, Natalie M; Connelly, Luke B; Nghiem, Hong S; Pobereskin, Louis

    2012-11-01

    This study highlights the serious consequences of ignoring reverse causality bias in studies on compensation-related factors and health outcomes and demonstrates a technique for resolving this problem of observational data. Data from an English longitudinal study on factors, including claims for compensation, associated with recovery from neck pain (whiplash) after rear-end collisions are used to demonstrate the potential for reverse causality bias. Although it is commonly believed that claiming compensation leads to worse recovery, it is also possible that poor recovery may lead to compensation claims--a point that is seldom considered and never addressed empirically. This pedagogical study compares the association between compensation claiming and recovery when reverse causality bias is ignored and when it is addressed, controlling for the same observable factors. When reverse causality is ignored, claimants appear to have a worse recovery than nonclaimants; however, when reverse causality bias is addressed, claiming compensation appears to have a beneficial effect on recovery, ceteris paribus. To avert biased policy and judicial decisions that might inadvertently disadvantage people with compensable injuries, there is an urgent need for researchers to address reverse causality bias in studies on compensation-related factors and health. Copyright © 2012 Elsevier Inc. All rights reserved.

  7. On characters of finite groups

    CERN Document Server

    Broué, Michel

    2017-01-01

    This book explores the classical and beautiful character theory of finite groups. It does it by using some rudiments of the language of categories. Originally emerging from two courses offered at Peking University (PKU), primarily for third-year students, it is now better suited for graduate courses, and provides broader coverage than books that focus almost exclusively on groups. The book presents the basic tools, notions and theorems of character theory (including a new treatment of the control of fusion and isometries), and introduces readers to the categorical language at several levels. It includes and proves the major results on characteristic zero representations without any assumptions about the base field. The book includes a dedicated chapter on graded representations and applications of polynomial invariants of finite groups, and its closing chapter addresses the more recent notion of the Drinfeld double of a finite group and the corresponding representation of GL_2(Z).

  8. Finite and profinite quantum systems

    CERN Document Server

    Vourdas, Apostolos

    2017-01-01

    This monograph provides an introduction to finite quantum systems, a field at the interface between quantum information and number theory, with applications in quantum computation and condensed matter physics. The first major part of this monograph studies the so-called `qubits' and `qudits', systems with periodic finite lattice as position space. It also discusses the so-called mutually unbiased bases, which have applications in quantum information and quantum cryptography. Quantum logic and its applications to quantum gates is also studied. The second part studies finite quantum systems, where the position takes values in a Galois field. This combines quantum mechanics with Galois theory. The third part extends the discussion to quantum systems with variables in profinite groups, considering the limit where the dimension of the system becomes very large. It uses the concepts of inverse and direct limit and studies quantum mechanics on p-adic numbers. Applications of the formalism include quantum optics and ...

  9. Preservation theorems on finite structures

    International Nuclear Information System (INIS)

    Hebert, M.

    1994-09-01

    This paper concerns classical Preservation results applied to finite structures. We consider binary relations for which a strong form of preservation theorem (called strong interpolation) exists in the usual case. This includes most classical cases: embeddings, extensions, homomorphisms into and onto, sandwiches, etc. We establish necessary and sufficient syntactic conditions for the preservation theorems for sentences and for theories to hold in the restricted context of finite structures. We deduce that for all relations above, the restricted theorem for theories hold provided the language is finite. For the sentences the restricted version fails in most cases; in fact the ''homomorphism into'' case seems to be the only possible one, but the efforts to show that have failed. We hope our results may help to solve this frustrating problem; in the meantime, they are used to put a lower bound on the level of complexity of potential counterexamples. (author). 8 refs

  10. Generalized prolate spheroidal wave functions for optical finite fractional Fourier and linear canonical transforms.

    Science.gov (United States)

    Pei, Soo-Chang; Ding, Jian-Jiun

    2005-03-01

    Prolate spheroidal wave functions (PSWFs) are known to be useful for analyzing the properties of the finite-extension Fourier transform (fi-FT). We extend the theory of PSWFs for the finite-extension fractional Fourier transform, the finite-extension linear canonical transform, and the finite-extension offset linear canonical transform. These finite transforms are more flexible than the fi-FT and can model much more generalized optical systems. We also illustrate how to use the generalized prolate spheroidal functions we derive to analyze the energy-preservation ratio, the self-imaging phenomenon, and the resonance phenomenon of the finite-sized one-stage or multiple-stage optical systems.

  11. Finite element analysis of a finite-strain plasticity problem

    International Nuclear Information System (INIS)

    Crose, J.G.; Fong, H.H.

    1984-01-01

    A finite-strain plasticity analysis was performed of an engraving process in a plastic rotating band during the firing of a gun projectile. The aim was to verify a nonlinear feature of the NIFDI/RB code: plastic large deformation analysis of nearly incompressible materials using a deformation theory of plasticity approach and a total Lagrangian scheme. (orig.)

  12. FINITE ELEMENT ANALYSIS OF STRUCTURES

    Directory of Open Access Journals (Sweden)

    PECINGINA OLIMPIA-MIOARA

    2015-05-01

    Full Text Available The application of finite element method is analytical when solutions can not be applied for deeper study analyzes static, dynamic or other types of requirements in different points of the structures .In practice it is necessary to know the behavior of the structure or certain parts components of the machine under the influence of certain factors static and dynamic . The application of finite element in the optimization of components leads to economic growth , to increase reliability and durability organs studied, thus the machine itself.

  13. Variational collocation on finite intervals

    International Nuclear Information System (INIS)

    Amore, Paolo; Cervantes, Mayra; Fernandez, Francisco M

    2007-01-01

    In this paper, we study a set of functions, defined on an interval of finite width, which are orthogonal and which reduce to the sinc functions when the appropriate limit is taken. We show that these functions can be used within a variational approach to obtain accurate results for a variety of problems. We have applied them to the interpolation of functions on finite domains and to the solution of the Schroedinger equation, and we have compared the performance of the present approach with others

  14. Finite elements of nonlinear continua

    CERN Document Server

    Oden, John Tinsley

    1972-01-01

    Geared toward undergraduate and graduate students, this text extends applications of the finite element method from linear problems in elastic structures to a broad class of practical, nonlinear problems in continuum mechanics. It treats both theory and applications from a general and unifying point of view.The text reviews the thermomechanical principles of continuous media and the properties of the finite element method, and then brings them together to produce discrete physical models of nonlinear continua. The mathematical properties of these models are analyzed, along with the numerical s

  15. Finite connectivity attractor neural networks

    International Nuclear Information System (INIS)

    Wemmenhove, B; Coolen, A C C

    2003-01-01

    We study a family of diluted attractor neural networks with a finite average number of (symmetric) connections per neuron. As in finite connectivity spin glasses, their equilibrium properties are described by order parameter functions, for which we derive an integral equation in replica symmetric approximation. A bifurcation analysis of this equation reveals the locations of the paramagnetic to recall and paramagnetic to spin-glass transition lines in the phase diagram. The line separating the retrieval phase from the spin-glass phase is calculated at zero temperature. All phase transitions are found to be continuous

  16. Brightness Variations of Sun-like Stars: The Mystery Deepens - Astronomers facing Socratic "ignorance"

    Science.gov (United States)

    2009-12-01

    ], achieving an impressive collection of the properties of these variable stars. Outstanding sets of data like the one collected by Nicholls and her colleagues often offer guidance on how to solve a cosmic puzzle by narrowing down the plethora of possible explanations proposed by the theoreticians. In this case, however, the observations are incompatible with all the previously conceived models and re-open an issue that has been thoroughly debated. Thanks to this study, astronomers are now aware of their own "ignorance" - a genuine driver of the knowledge-seeking process, as the ancient Greek philosopher Socrates is said to have taught. "The newly gathered data show that pulsations are an extremely unlikely explanation for the additional variation," says team leader Peter Wood. "Another possible mechanism for producing luminosity variations in a star is to have the star itself move in a binary system. However, our observations are strongly incompatible with this hypothesis too." The team found from further analysis that whatever the cause of these unexplained variations is, it also causes the giant stars to eject mass either in clumps or as an expanding disc. "A Sherlock Holmes is needed to solve this very frustrating mystery," concludes Nicholls. Notes [1] Precise brightness measurements were made by the MACHO and OGLE collaborations, running on telescopes in Australia and Chile, respectively. The OGLE observations were made at the same time as the VLT observations. More information This research was presented in two papers: one appeared in the November issue of the Monthly Notices of the Royal Astronomical Society ("Long Secondary Periods in Variable Red Giants", by C. P. Nicholls et al.), and the other has just been published in the Astrophysical Journal ("Evidence for mass ejection associated with long secondary periods in red giants", by P. R. Wood and C. P. Nicholls). The team is composed of Christine P. Nicholls and Peter R. Wood (Research School of Astronomy and

  17. Nonstandard Finite Difference Method Applied to a Linear Pharmacokinetics Model

    Directory of Open Access Journals (Sweden)

    Oluwaseun Egbelowo

    2017-05-01

    Full Text Available We extend the nonstandard finite difference method of solution to the study of pharmacokinetic–pharmacodynamic models. Pharmacokinetic (PK models are commonly used to predict drug concentrations that drive controlled intravenous (I.V. transfers (or infusion and oral transfers while pharmacokinetic and pharmacodynamic (PD interaction models are used to provide predictions of drug concentrations affecting the response of these clinical drugs. We structure a nonstandard finite difference (NSFD scheme for the relevant system of equations which models this pharamcokinetic process. We compare the results obtained to standard methods. The scheme is dynamically consistent and reliable in replicating complex dynamic properties of the relevant continuous models for varying step sizes. This study provides assistance in understanding the long-term behavior of the drug in the system, and validation of the efficiency of the nonstandard finite difference scheme as the method of choice.

  18. Size matters

    Energy Technology Data Exchange (ETDEWEB)

    Forst, Michael

    2012-11-01

    The shakeout in the solar cell and module industry is in full swing. While the number of companies and production locations shutting down in the Western world is increasing, the capacity expansion in the Far East seems to be unbroken. Size in combination with a good sales network has become the key to success for surviving in the current storm. The trade war with China already looming on the horizon is adding to the uncertainties. (orig.)

  19. Ignoring "Best Practice": Why Irish Software SMEs are Rejecting CMMI and ISO 9000

    Directory of Open Access Journals (Sweden)

    Rory V. O’Connor

    2009-08-01

    Full Text Available Software Process Improvement (SPI "best practice" models such as ISO 9000 and the Capability Maturity Model Integrated (CMMI have been developed to assist software development organisations by harnessing their experience and providing them with support so that they can produce software products on time, within budget and to a high level of quality. However there is increasing evidence that these models are not being adopted by Small and Medium sized Enterprises (SMEs and primarily remain the remit of large organisations. This paper presents the results of a Grounded Theory study into why Irish SME software product companies are not using these SPI models. The key inhibiting factor found was the issue of cost. We discuss the findings in relation to cost of process and the factors affecting it, including bureaucracy, documentation, communication, tacit knowledge and organisational creativity and flexibility, and the associated impact on the adoption of SPI best practice models.

  20. Group-invariant finite Fourier transforms

    International Nuclear Information System (INIS)

    Shenefelt, M.H.

    1988-01-01

    The computation of the finite Fourier transform of functions is one of the most used computations in crystallography. Since the Fourier transform involved in 3-dimensional, the size of the computation becomes very large even for relatively few sample points along each edge. In this thesis, there is a family of algorithms that reduce the computation of Fourier transform of functions respecting the symmetries. Some properties of these algorithms are: (1) The algorithms make full use of the group of symmetries of a crystal. (2) The algorithms can be factored and combined according to the prime factorization of the number of points in the sample space. (3) The algorithms are organized into a family using the group structure of the crystallographic groups to make iterative procedures possible