Modified effective range analysis of electron scattering from krypton
NASA Astrophysics Data System (ADS)
Fedus, Kamil
2014-10-01
The elastic cross sections for electron scattering on krypton from zero energy up to 10 eV have been analyzed by the modified effective range method. A simple model based on the analytical solution of the Schrödinger equation with the polarization potential using explicitly determined scattering phase shifts for the three lowest partial waves describes the elastic differential, integral and momentum transfer cross sections up to the energy threshold of the first inelastic process well. In detail, the contribution of the long-range polarization potential to the scattering phase shift is exactly expressed, while the contribution of the short-range effects is modelled by simple quadratic expressions (the effective range expansions). The effective range parameters are determined empirically by comparison with the latest experimental differential cross sections. Presently, the calculated integral and momentum transfer cross sections are validated against numerous electron scattering experiments and the most recent quantum-mechanical theories. To complete the picture, the two-term Boltzmann analysis is employed to determine the electron transport coefficients; the agreement with the electron swarm experimental data is found to be very good.
Electron Scattering from Neon Via Effective Range Theory
NASA Astrophysics Data System (ADS)
Fedus, Kamil
2014-12-01
Elastic cross-sections for electron scattering on neon from 0 energy up to 16 eV are analyzed by an analytical approach to the modified effective range theory (MERT). It is shown that energy and angular variations of elastic differential, integral and momentum transfer cross-sections can be accurately parameterized by six MERT coefficients up to the energy threshold for the first Feshbach resonance. MERT parameters are determined empirically by numerical comparison with large collection of available experimental data of elastic total (integral) cross-sections. The present analysis is validated against numerous electron beams and swarm experiments. The comparison of derived MERT parameters with those found for other noble gases, helium, argon and krypton, is done. The derived scattering length (for the s-partial wave) in neon, 0.227 a 0, agrees well with recent theories; it is small but, differently from Ar and Kr, still positive. Analogue parameters for the p-wave and the d-wave are negative and positive respectively for all the four gases compared.
Ramsauer-Townsend minimum in methane — modified effective range analysis
NASA Astrophysics Data System (ADS)
Fedus, Kamil; Karwasz, Grzegorz P.
2014-04-01
Electron-scattering cross sections in methane are analysed in the very-low energy region. The correspondence between integral elastic, elastic differential and momentum transfer cross sections is checked via a novel approach to modified effective range theory, in order to determine the depth and position of the Ramsauer-Townsend minimum. Phase shifts of the two lowest partial waves are obtained explicitly and parameterized by four coefficients with the physical meaning of the scattering lengths and the effective ranges. Using recent experiments on vibrational cross sections performed over an extended (0-180°) angular range and comparing several theories, an agreement within 10% has been obtained between experimental total and present summed (elastic + vibrational) cross sections in the whole 0.1-2.0 eV energy range. An additional check for consistency is done using two-term Boltzmann analysis to derive electron diffusion coefficients. Calculated drift velocities and transversal diffusion coefficients at 0-10 Td reduced electric field agree within 5% with experiments.
NASA Astrophysics Data System (ADS)
Gross, Franz; Stadler, Alfred
2010-09-01
We present the effective range expansions for the 1S0 and 3S1 scattering phase shifts, and the relativistic deuteron wave functions that accompany our recent high precision fits (with χ2/Ndata≃1) to the 2007 world np data below 350 MeV. The wave functions are expanded in a series of analytical functions (with the correct asymptotic behavior at both large and small arguments) that can be Fourier-transformed from momentum to coordinate space and are convenient to use in any application. A fortran subroutine to compute these wave functions can be obtained from the authors.
Franz Gross, Alfred Stadler
2010-09-01
We present the effective range expansions for the 1S0 and 3S1 scattering phase shifts, and the relativistic deuteron wave functions that accompany our recent high precision fits (with \\chi^2/N{data} \\simeq 1) to the 2007 world np data below 350 MeV. The wave functions are expanded in a series of analytical functions (with the correct asymptotic behavior at both large and small arguments) that can be Fourier-transformed from momentum to coordinate space and are convenient to use in any application. A fortran subroutine to compute these wave functions can be obtained from the authors.
Gross, Franz; Stadler, Alfred
2010-09-15
We present the effective range expansions for the {sup 1}S{sub 0} and {sup 3}S{sub 1} scattering phase shifts, and the relativistic deuteron wave functions that accompany our recent high precision fits (with {chi}{sup 2}/N{sub data{approx_equal}}1) to the 2007 world np data below 350 MeV. The wave functions are expanded in a series of analytical functions (with the correct asymptotic behavior at both large and small arguments) that can be Fourier-transformed from momentum to coordinate space and are convenient to use in any application. A fortran subroutine to compute these wave functions can be obtained from the authors.
Modified Actions for Gravity: Theory and Phenomenology
NASA Astrophysics Data System (ADS)
Sotiriou, Thomas P.
2007-10-01
This thesis is devoted to the study of gravitational theories which can be seen as modifications or generalisations of General Relativity. The motivation for considering such theories, stemming from Cosmology, High Energy Physics and Astrophysics is thoroughly discussed (cosmological problems, dark energy and dark matter problems, the lack of success so far in obtaining a successful formulation for Quantum Gravity). The basic principles which a gravitational theory should follow, and their geometrical interpretation, are analysed in a broad perspective which highlights the basic assumptions of General Relativity and suggests possible modifications which might be made. A number of such possible modifications are presented, focusing on certain specific classes of theories: scalar-tensor theories, metric f(R) theories, Palatini f(R) theories, metric-affine f(R) theories and Gauss--Bonnet theories. The characteristics of these theories are fully explored and attention is payed to issues of dynamical equivalence between them. Also, cosmological phenomenology within the realm of each of the theories is discussed and it is shown that they can potentially address the well-known cosmological problems. A number of viability criteria are presented: cosmological observations, Solar System tests, stability criteria, existence of exact solutions for common vacuum or matter configurations etc. Finally, future perspectives in the field of modified gravity are discussed and the possibility for going beyond a trial-and-error approach to modified gravity is explored.
Modified Sigmund sputtering theory: isotopic puzzle
NASA Astrophysics Data System (ADS)
Zhang, Z. L.; Zhang, L.
2005-05-01
The theory of anisotropic sputtering proposed by Zhang [Z.L. Zhang, Phys. Rev. B 71 026101 (2005).] and [Z.L. Zhang and L. Zhang, Radiat. Eff. Defects Solids 159(5) 301 (2004).] has been generalized to sputtering of isotopic mixtures. The present theory (modified Sigmund theory) has been shown to fit numerous simulations and experimental measurements, including energy and angular distribution of sputtered atoms. In particular, the theory has successfully solved the isotope puzzle of sputtering induced by low energy and heavy ion bombardment.
Thermodynamic properties of modified gravity theories
NASA Astrophysics Data System (ADS)
Bamba, Kazuharu
2016-06-01
We review thermodynamic properties of modified gravity theories, such as F(R) gravity and f(T) gravity, where R is the scalar curvature and T is the torsion scalar in teleparallelism. In particular, we explore the equivalence between the equations of motion for modified gravity theories and the Clausius relation in thermodynamics. In addition, thermodynamics of the cosmological apparent horizon is investigated in f(T) gravity. We show both equilibrium and nonequilibrium descriptions of thermodynamics. It is demonstrated that the second law of thermodynamics in the universe can be met, when the temperature of the outside of the apparent horizon is equivalent to that of the inside of it.
Modified Iterative Extended Hueckel. 1: Theory
NASA Technical Reports Server (NTRS)
Aronowitz, S.
1980-01-01
Iterative Extended Huekel is modified by inclusion of explicit effective internuclear and electronic interactions. The one electron energies are shown to obey a variational principle because of the form of the effective electronic interactions. The modifications permit mimicking of aspects of valence bond theory with the additional feature that the energies associated with valence bond type structures are explicitly calculated. In turn, a hybrid molecular, orbital valence, bond scheme is introduced which incorporates variant total molecular electronic density distributions similar to the way that Iterative Extended Hueckel incorporates atoms.
Modified Interior Distance Functions (Theory and Methods)
NASA Technical Reports Server (NTRS)
Polyak, Roman A.
1995-01-01
In this paper we introduced and developed the theory of Modified Interior Distance Functions (MIDF's). The MIDF is a Classical Lagrangian (CL) for a constrained optimization problem which is equivalent to the initial one and can be obtained from the latter by monotone transformation both the objective function and constraints. In contrast to the Interior Distance Functions (IDF's), which played a fundamental role in Interior Point Methods (IPM's), the MIDF's are defined on an extended feasible set and along with center, have two extra tools, which control the computational process: the barrier parameter and the vector of Lagrange multipliers. The extra tools allow to attach to the MEDF's very important properties of Augmented Lagrangeans. One can consider the MIDFs as Interior Augmented Lagrangeans. It makes MIDF's similar in spirit to Modified Barrier Functions (MBF's), although there is a fundamental difference between them both in theory and methods. Based on MIDF's theory, Modified Center Methods (MCM's) have been developed and analyzed. The MCM's find an unconstrained minimizer in primal space and update the Lagrange multipliers, while both the center and the barrier parameter can be fixed or updated at each step. The MCM's convergence was investigated, and their rate of convergence was estimated. The extension of the feasible set and the special role of the Lagrange multipliers allow to develop MCM's, which produce, in case of nondegenerate constrained optimization, a primal and dual sequences that converge to the primal-dual solutions with linear rate, even when both the center and the barrier parameter are fixed. Moreover, every Lagrange multipliers update shrinks the distance to the primal dual solution by a factor 0 less than gamma less than 1 which can be made as small as one wants by choosing a fixed interior point as a 'center' and a fixed but large enough barrier parameter. The numericai realization of MCM leads to the Newton MCM (NMCM). The
Modified large number theory with constant G
Recami, E.
1983-03-01
The inspiring ''numerology'' uncovered by Dirac, Eddington, Weyl, et al. can be explained and derived when it is slightly modified so to connect the ''gravitational world'' (cosmos) with the ''strong world'' (hadron), rather than with the electromagnetic one. The aim of this note is to show the following. In the present approach to the ''Large Number Theory,'' cosmos and hadrons are considered to be (finite) similar systems, so that the ratio R-bar/r-bar of the cosmos typical length R-bar to the hadron typical length r-bar is constant in time (for instance, if both cosmos and hadrons undergo an expansion/contraction cycle: according to the ''cyclical big-bang'' hypothesis: then R-bar and r-bar can be chosen to be the maximum radii, or the average radii). As a consequence, then gravitational constant G results to be independent of time. The present note is based on work done in collaboration with P.Caldirola, G. D. Maccarrone, and M. Pavsic.
Equilibrium thermodynamics in modified gravitational theories
NASA Astrophysics Data System (ADS)
Bamba, Kazuharu; Geng, Chao-Qiang; Tsujikawa, Shinji
2010-04-01
We show that it is possible to obtain a picture of equilibrium thermodynamics on the apparent horizon in the expanding cosmological background for a wide class of modified gravity theories with the Lagrangian density f(R,ϕ,X), where R is the Ricci scalar and X is the kinetic energy of a scalar field ϕ. This comes from a suitable definition of an energy-momentum tensor of the “dark” component that respects to a local energy conservation in the Jordan frame. In this framework the horizon entropy S corresponding to equilibrium thermodynamics is equal to a quarter of the horizon area A in units of gravitational constant G, as in Einstein gravity. For a flat cosmological background with a decreasing Hubble parameter, S globally increases with time, as it happens for viable f(R) inflation and dark energy models. We also show that the equilibrium description in terms of the horizon entropy S is convenient because it takes into account the contribution of both the horizon entropy S' in non-equilibrium thermodynamics and an entropy production term.
Modified contour-improved perturbation theory
Cvetic, Gorazd; Loewe, Marcelo; Martinez, Cristian; Valenzuela, Cristian
2010-11-01
The semihadronic tau decay width allows a clean extraction of the strong coupling constant at low energies. We present a modification of the standard ''contour-improved'' method based on a derivative expansion of the Adler function. The new approach has some advantages compared to contour-improved perturbation theory. The renormalization scale dependence is weaker by more than a factor of 2 and the last term of the expansion is reduced by about 10%, while the renormalization scheme dependence remains approximately equal. The extracted QCD coupling at the tau mass scale is by 2% lower than the contour-improved value. We find {alpha}{sub s}(M{sub Z}{sup 2})=0.1211{+-}0.0010.
Density perturbations in general modified gravitational theories
De Felice, Antonio; Tsujikawa, Shinji; Mukohyama, Shinji
2010-07-15
We derive the equations of linear cosmological perturbations for the general Lagrangian density f(R,{phi},X)/2+L{sub c}, where R is a Ricci scalar, {phi} is a scalar field, and X=-{partial_derivative}{sup {mu}{phi}{partial_derivative}}{sub {mu}{phi}/}2 is a field kinetic energy. We take into account a nonlinear self-interaction term L{sub c}={xi}({phi}) {open_square}{phi}({partial_derivative}{sup {mu}{phi}{partial_derivative}}{sub {mu}{phi}}) recently studied in the context of ''Galileon'' cosmology, which keeps the field equations at second order. Taking into account a scalar-field mass explicitly, the equations of matter density perturbations and gravitational potentials are obtained under a quasistatic approximation on subhorizon scales. We also derive conditions for the avoidance of ghosts and Laplacian instabilities associated with propagation speeds. Our analysis includes most of modified gravity models of dark energy proposed in literature; and thus it is convenient to test the viability of such models from both theoretical and observational points of view.
Constraining modified gravitational theories by weak lensing with Euclid
Martinelli, Matteo; Calabrese, Erminia; De Bernardis, Francesco; Melchiorri, Alessandro; Pagano, Luca; Scaramella, Roberto
2011-01-15
Future proposed satellite missions such as Euclid can offer the opportunity to test general relativity on cosmic scales through mapping of the galaxy weak-lensing signal. In this paper we forecast the ability of these experiments to constrain modified gravity scenarios such as those predicted by scalar-tensor and f(R) theories. We find that Euclid will improve constraints expected from the Planck satellite on these modified theories of gravity by 2 orders of magnitude. We discuss parameter degeneracies and the possible biases introduced by modifications to gravity.
Microscopic and macroscopic behaviors of Palatini modified gravity theories
Li Baojiu; Mota, David F.; Shaw, Douglas J.
2008-09-15
We show that, within modified gravity, the nonlinear nature of the field equations implies that the usual naieve averaging procedure (replacing the microscopic energy-momentum by its cosmological average) is invalid. We discuss then how the averaging should be performed correctly and show that, as a consequence, at the classical level the physical masses and geodesics of particles, cosmology, and astrophysics in Palatini modified gravity theories are all indistinguishable from the results of general relativity plus a cosmological constant. Palatini gravity is, however, a different theory from general relativity and predicts different internal structures of particles from the latter. On the other hand, and in contrast to classical particles, the electromagnetic field permeates in the space, and hence a different averaging procedure should be applied here. We show that, in general, Palatini gravity theories would then affect the propagation of photons, thus changing the behavior of a Universe dominated by radiation. Finally, Palatini theories also predict alterations to particle physics laws. For example, they can lead to sensitive corrections to the hydrogen energy levels, the measurements of which could be used to place very strong constraints on the properties of viable Palatini gravity theories.
Fast route to nonlinear clustering statistics in modified gravity theories
NASA Astrophysics Data System (ADS)
Winther, Hans A.; Ferreira, Pedro G.
2015-06-01
We propose a simple and computationally fast method for performing N -body simulations for a large class of modified gravity theories with a screening mechanism such as chameleons, symmetrons, and Galileons. By combining the linear Klein-Gordon equation with a screening factor, calculated from analytical solutions of spherical symmetric configurations, we obtain a modified field equation of which the solution is exact in the linear regime while at the same time taking screening into account on nonlinear scales. The resulting modified field equation remains linear and can be solved just as quickly as the Poisson equation without any of the convergence problems that can arise when solving the full equation. We test our method with N -body simulations and find that it compares remarkably well with full simulations well into the nonlinear regime.
Lunar System Constraints on the Modified Theories of Gravity
NASA Astrophysics Data System (ADS)
Exirifard, Qasem
2013-07-01
The Modified Newtonian Dynamics (MOND) paradigm to the missing mass problem requires introducing a functional that is to be identified through observations and experiments. We consider the aquadratic Lagrangian theory as a realization of the MOND. We show that the accurate value of the Earth GM measured by the lunar laser ranging measurements and that by various artificial Earth satellites, including the accurate tracking of the LAGEOS satellites, constrain this functional such that some of the chosen/proposed functional are refuted.
Classifying linearly shielded modified gravity models in effective field theory.
Lombriser, Lucas; Taylor, Andy
2015-01-23
We study the model space generated by the time-dependent operator coefficients in the effective field theory of the cosmological background evolution and perturbations of modified gravity and dark energy models. We identify three classes of modified gravity models that reduce to Newtonian gravity on the small scales of linear theory. These general classes contain enough freedom to simultaneously admit a matching of the concordance model background expansion history. In particular, there exists a large model space that mimics the concordance model on all linear quasistatic subhorizon scales as well as in the background evolution. Such models also exist when restricting the theory space to operators introduced in Horndeski scalar-tensor gravity. We emphasize that whereas the partially shielded scenarios might be of interest to study in connection with tensions between large and small scale data, with conventional cosmological probes, the ability to distinguish the fully shielded scenarios from the concordance model on near-horizon scales will remain limited by cosmic variance. Novel tests of the large-scale structure remedying this deficiency and accounting for the full covariant nature of the alternative gravitational theories, however, might yield further insights on gravity in this regime. PMID:25658988
Wormhole geometries in f(R) modified theories of gravity
Lobo, Francisco S. N.; Oliveira, Miguel A.
2009-11-15
In this work, we construct traversable wormhole geometries in the context of f(R) modified theories of gravity. We impose that the matter threading the wormhole satisfies the energy conditions, so that it is the effective stress-energy tensor containing higher order curvature derivatives that is responsible for the null energy condition violation. Thus, the higher order curvature terms, interpreted as a gravitational fluid, sustain these nonstandard wormhole geometries, fundamentally different from their counterparts in general relativity. In particular, by considering specific shape functions and several equations of state, exact solutions for f(R) are found.
Applying modified Ginzburg-Landau theory to nuclei
NASA Astrophysics Data System (ADS)
Mohammadi, P.; Dehghani, V.; Mehmandoost-Khajeh-Dad, A. A.
2014-11-01
The Ginzburg-Landau theory of phase transitions is modified and used to investigate the heat capacity, energy, entropy, and order parameter of the paired phases of 208Pb,88Sr,48Ca, and 20Ne. We use the Fermi gas model to calculate the thermodynamic properties of the normal phase of the nucleons. Our results show that the total heat capacities of the studied nuclei have an S -shape behavior, which is in accordance with the semi-empirical data, and the order parameter does not approach zero at a specific critical temperature.
Relativistic gravitation theory for the modified Newtonian dynamics paradigm
Bekenstein, Jacob D.
2004-10-15
The modified Newtonian dynamics (MOND) paradigm of Milgrom can boast of a number of successful predictions regarding galactic dynamics; these are made without the assumption that dark matter plays a significant role. MOND requires gravitation to depart from Newtonian theory in the extragalactic regime where dynamical accelerations are small. So far relativistic gravitation theories proposed to underpin MOND have either clashed with the post-Newtonian tests of general relativity, or failed to provide significant gravitational lensing, or violated hallowed principles by exhibiting superluminal scalar waves or an a priori vector field. We develop a relativistic MOND inspired theory which resolves these problems. In it gravitation is mediated by metric, a scalar, and a 4-vector field, all three dynamical. For a simple choice of its free function, the theory has a Newtonian limit for nonrelativistic dynamics with significant acceleration, but a MOND limit when accelerations are small. We calculate the {beta} and {gamma} parameterized post-Newtonian coefficients showing them to agree with solar system measurements. The gravitational light deflection by nonrelativistic systems is governed by the same potential responsible for dynamics of particles. To the extent that MOND successfully describes dynamics of a system, the new theory's predictions for lensing by that system's visible matter will agree as well with observations as general relativity's predictions made with a dynamically successful dark halo model. Cosmological models based on the theory are quite similar to those based on general relativity; they predict slow evolution of the scalar field. For a range of initial conditions, this last result makes it easy to rule out superluminal propagation of metric, scalar, and vector waves.
Dark energy or modified gravity? An effective field theory approach
Bloomfield, Jolyon; Flanagan, Éanna É.; Park, Minjoon; Watson, Scott E-mail: eef3@cornell.edu E-mail: gswatson@syr.edu
2013-08-01
We take an Effective Field Theory (EFT) approach to unifying existing proposals for the origin of cosmic acceleration and its connection to cosmological observations. Building on earlier work where EFT methods were used with observations to constrain the background evolution, we extend this program to the level of the EFT of the cosmological perturbations — following the example from the EFT of Inflation. Within this framework, we construct the general theory around an assumed background which will typically be chosen to mimic ΛCDM, and identify the parameters of interest for constraining dark energy and modified gravity models with observations. We discuss the similarities to the EFT of Inflation, but we also identify a number of subtleties including the relationship between the scalar perturbations and the Goldstone boson of the spontaneously broken time translations. We present formulae that relate the parameters of the fundamental Lagrangian to the speed of sound, anisotropic shear stress, effective Newtonian constant, and Caldwell's varpi parameter, emphasizing the connection to observations. It is anticipated that this framework will be of use in constraining individual models, as well as for placing model-independent constraints on dark energy and modified gravity model building.
3D weak lensing: Modified theories of gravity
NASA Astrophysics Data System (ADS)
Pratten, Geraint; Munshi, Dipak; Valageas, Patrick; Brax, Philippe
2016-05-01
Weak lensing (WL) promises to be a particularly sensitive probe of both the growth of large-scale structure as well as the fundamental relation between matter density perturbations and metric perturbations, thus providing a powerful tool with which we may constrain modified theories of gravity (MG) on cosmological scales. Future deep, wide-field WL surveys will provide an unprecedented opportunity to constrain deviations from General Relativity. Employing a 3D analysis based on the spherical Fourier-Bessel expansion, we investigate the extent to which MG theories will be constrained by a typical 3D WL survey configuration including noise from the intrinsic ellipticity distribution σɛ of source galaxies. Here, we focus on two classes of screened theories of gravity: (i) f (R ) chameleon models and (ii) environmentally dependent dilaton models. We use one-loop perturbation theory combined with halo models in order to accurately model the evolution of the matter power spectrum with redshift in these theories. Using a χ2 analysis, we show that for an all-sky spectroscopic survey, the parameter fR0 can be constrained in the range fR0<5 ×10-6(9 ×10-6) for n =1 (2 ) with a 3 σ confidence level. This can be achieved by using relatively low-order angular harmonics ℓ<100 . Higher-order harmonics ℓ>100 could provide tighter constraints but are subject to nonlinear effects, such as baryonic feedback, that must be accounted for. We also employ a Principal Component Analysis in order to study the parameter degeneracies in the MG parameters. The confusion from intrinsic ellipticity correlation and modification of the matter power spectrum at a small scale due to feedback mechanisms is briefly discussed.
The 'X model': a modified version of the competition theory.
Scott, O C; Révész, L; Edgren, M
1993-10-01
In 1985, Edgren et al. proposed a modified version of the competition theory to explain the interaction of sensitizers and protectors with target molecules damaged by radiation, which was designated the 'X' model. This model incorporates concepts which have been considered previously, namely that a type of radiation damage exists which cannot be chemically repaired, and that cells may contain a naturally occurring sensitizer. The model leads to testable predictions, such as, e.g. the crossing of 'K curves' when the level of protection is varied. It can only be applied to the immediate effects of radiation, i.e. before enzymatic reactions play a part. The present paper is a summary of work carried out since 1985 to test the predictions of the 'X' model and an exposition of the related algebra. PMID:7901298
Kerr-Newman solution in modified teleparallel theory of gravity
NASA Astrophysics Data System (ADS)
Nashed, Gamal G. L.
2015-11-01
A nondiagonal tetrad field having six unknown functions plus an angle Φ, which is a function of the radial coordinate r, azimuthal angle θ and the polar angle ϕ, is applied to the charged field equations of modified teleparallel theory of gravity. A special nonvacuum solution is derived with three constants of integration. The tetrad field of this solution is axially symmetric and its scalar torsion is constant. The associated metric of the derived solution gives Kerr-Newman spacetime. We have shown that the derived solution can be described by a local Lorentz transformations plus a diagonal tetrad field that is the square root of the Kerr-Newman metric. We show that any solution of general relativity (GR) can be a solution in f(T) under certain conditions.
Gravitational Microlensing in Modified Gravity Theories - Inverse-Square Theorem
NASA Astrophysics Data System (ADS)
Asada, H.
2011-02-01
Microlensing studies are usually based on the lens equation that is valid only to the first order in the gravitational constant G and lens mass M. We consider corrections to the conventional lens equation in terms of differentiable functions, so that they can express not only the second-order effects of GM in general relativity but also modified gravity theories. As a generalization of Ebina et al. (Prog. Theor. Phys. 104 (2000), 1317), we show that, provided that the spacetime is static, spherically symmetric and asymptotically flat, the total amplification by microlensing remains unchanged at the linear order of the correction to the deflection angle, if and only if the correction takes a particular form as the inverse square of the impact parameter, whereas the magnification factor for each image is corrected. It is concluded that the light curve shape by microlensing is inevitably changed and will thus allow us to probe modified gravity, unless a modificati on to the deflection angle takes the particular form. No systematic deviation in microlensing observations has been reported. For instance, therefore, the Yukawa-type correction is constrained as the characteristic length > 10^{14} m.
Perturbations of single-field inflation in modified gravity theory
NASA Astrophysics Data System (ADS)
Qiu, Taotao; Xia, Jun-Qing
2015-05-01
In this paper, we study the case of single field inflation within the framework of modified gravity theory where the gravity part has an arbitrary form f (R). Via a conformal transformation, this case can be transformed into its Einstein frame where it looks like a two-field inflation model. However, due to the existence of the isocurvature modes in such a multi-degree-of-freedom (m.d.o.f.) system, the (curvature) perturbations are not equivalent in two frames, so despite of its convenience, it is illegal to treat the perturbations in its Einstein frame as the "real" ones as we always do for pure f (R) theory or single field with nonminimal coupling. Here by pulling the results of curvature perturbations back into its original Jordan frame, we show explicitly the power spectrum and spectral index of the perturbations in the Jordan frame, as well as how it differs from the Einstein frame. We also fit our results with the newest Planck data. Since there is large parameter space in these models, we show that it is easy to fit the data very well.
Galaxy clustering in 3D and modified gravity theories
NASA Astrophysics Data System (ADS)
Munshi, D.; Pratten, G.; Valageas, P.; Coles, P.; Brax, P.
2016-02-01
We study Modified Gravity (MG) theories by modelling the redshifted matter power spectrum in a spherical Fourier-Bessel basis. We use a fully non-linear description of the real-space matter power spectrum and include the lowest order redshift-space correction (Kaiser effect), taking into account some additional non-linear contributions. Ignoring relativistic corrections, which are not expected to play an important role for a shallow survey, we analyse two different MG scenarios, namely the generalized Dilaton scalar-tensor theories and the f (R) models in the large curvature regime. We compute the 3D power spectrum C^s_{ℓ}(k_1,k_2) for various such MG theories with and without redshift-space distortions, assuming precise knowledge of background cosmological parameters. Using an all-sky spectroscopic survey with Gaussian selection function \\varphi (r)∝ exp (-{r^2/r^2_0}), r_0=150h^{-1} Mpc, and number density of galaxies bar{N} =10^{-4}Mpc^{-3}, we use a χ2 analysis, and find that the lower order (ℓ ≤ 25) multipoles of C^s_ℓ (k,k^' }) (with radial modes restricted to k < 0.2 h Mpc-1) can constraint the parameter f_{R_0} at a level of 2 × 10-5(3 × 10-5) with 3σ confidence for n = 1(2). Combining constraints from higher ℓ > 25 modes can further reduce the error bars and thus in principle make cosmological gravity constraints competitive with Solar system tests. However this will require an accurate modelling of non-linear redshift-space distortions. Using a tomographic β(a)-m(a) parametrization we also derive constraints on specific parameters describing the Dilaton models of MG.
A modified large number theory with constant G
NASA Astrophysics Data System (ADS)
Recami, Erasmo
1983-03-01
The inspiring “numerology” uncovered by Dirac, Eddington, Weyl, et al. can be explained and derived when it is slightly modified so to connect the “gravitational world” (cosmos) with the “strong world” (hadron), rather than with the electromagnetic one. The aim of this note is to show the following. In the present approach to the “Large Number Theory,” cosmos and hadrons are considered to be (finite) similar systems, so that the ratio{{bar R} / {{bar R} {bar r}} of the cosmos typical lengthbar R to the hadron typical lengthbar r is constant in time (for instance, if both cosmos and hadrons undergo an expansion/contraction cycle—according to the “cyclical bigbang” hypothesis—thenbar R andbar r can be chosen to be the maximum radii, or the average radii). As a consequence, then gravitational constant G results to be independent of time. The present note is based on work done in collaboration with P. Caldirola, G. D. Maccarrone, and M. Pavšič.
A modified Lorentz theory as a test theory of special relativity
NASA Technical Reports Server (NTRS)
Chang, T.; Torr, D. G.; Gagnon, D. R.
1988-01-01
Attention has been given recently to a modified Lorentz theory (MLT) that is based on the generalized Galilean transformation. Some explicit formulas within the framework of MLT, dealing with the one-way velocity of light, slow-clock transport, and the Doppler effect are derived. A number of typical experiments are analyzed on this basis. Results indicate that the empirical equivalence between MLT and special relativity is still maintained to second order terms. The results of previous works that predict that the MLT might be distinguished from special relativity at the third order by Doppler centrifuge tests capable of a fractional frequency detection threshold of 10 to the -15th are confirmed.
Creation of wormholes by quantum tunnelling in modified gravity theories
NASA Astrophysics Data System (ADS)
Battarra, Lorenzo; Lavrelashvili, George; Lehners, Jean-Luc
2014-12-01
We study the process of quantum tunnelling in scalar-tensor theories in which the scalar field is nonminimally coupled to gravity. In these theories gravitational instantons can deviate substantially from sphericity and can in fact develop a neck—a feature prohibited in theories with minimal coupling. Such instantons with necks lead to the materialization of bubble geometries containing a wormhole region. We clarify the relationship of neck geometries to violations of the null energy condition, and also derive a bound on the size of the neck relative to that of the instanton.
Theory of nanoscale friction on chemically modified graphene
NASA Astrophysics Data System (ADS)
Ko, Jae-Hyeon; Kim, Yong-Hyun
2013-03-01
Recently, it is known from FFM experiments that friction force on graphene is significantly increased by chemical modification such as hydrogenation, oxidization, and fluorination, whereas adhesion properties are altered marginally. A novel nanotribological theory on two-dimensional materials is proposed on the basis of experimental results and first-principles density-functional theory (DFT) calculations. The proposed theory indicates that the total lateral stiffness that is the proportional constant of friction force is mostly associated with the out-of-plane bending stiffness of two-dimensional materials. This contrasts to the case of three-dimensional materials, in which the shear strength of materials determines nanoscale friction. We will discuss details of DFT calculations and how to generalize the current theory to three dimensional materials.
Effective field theory from modified gravity with massive modes
NASA Astrophysics Data System (ADS)
Capozziello, Salvatore; de Laurentis, Mariafelicia; Paolella, Mariacristina; Ricciardi, Giulia
2015-10-01
Massive gravitational modes in effective field theories can be recovered by extending General Relativity and taking into account generic functions of the curvature invariants, not necessarily linear in the Ricci scalar R. In particular, adopting the minimal extension of f(R) gravity, an effective field theory with massive modes is straightforwardly recovered. This approach allows to evade shortcomings like ghosts and discontinuities if a suitable choice of expansion parameters is performed.
Stability of spherically symmetric solutions in modified theories of gravity
Seifert, Michael D.
2007-09-15
In recent years, a number of alternative theories of gravity have been proposed as possible resolutions of certain cosmological problems or as toy models for possible but heretofore unobserved effects. However, the implications of such theories for the stability of structures such as stars have not been fully investigated. We use our 'generalized variational principle', described in a previous work [M. D. Seifert and R. M. Wald, Phys. Rev. D 75, 084029 (2007)], to analyze the stability of static spherically symmetric solutions to spherically symmetric perturbations in three such alternative theories: Carroll et al.'s f(R) gravity, Jacobson and Mattingly's 'Einstein-aether theory', and Bekenstein's TeVeS theory. We find that in the presence of matter, f(R) gravity is highly unstable; that the stability conditions for spherically symmetric curved vacuum Einstein-aether backgrounds are the same as those for linearized stability about flat spacetime, with one exceptional case; and that the 'kinetic terms' of vacuum TeVeS theory are indefinite in a curved background, leading to an instability.
Multicomponent solution in a modified theory of gravity in the early universe
Mohseni Sadjadi, H.
2008-05-15
We study the modified theory of gravity in the Friedmann-Robertson-Walker universe composed of several perfect fluids. We consider the power law inflation and determine the equation of state parameters in terms of the parameters of modified gravity's Lagrangian in the early universe. We also briefly discuss the gravitational baryogenesis in this model.
A modified Lax-Phillips scattering theory for quantum mechanics
NASA Astrophysics Data System (ADS)
Strauss, Y.
2015-07-01
The Lax-Phillips scattering theory is an appealing abstract framework for the analysis of scattering resonances. Quantum mechanical adaptations of the theory have been proposed. However, since these quantum adaptations essentially retain the original structure of the theory, assuming the existence of incoming and outgoing subspaces for the evolution and requiring the spectrum of the generator of evolution to be unbounded from below, their range of applications is rather limited. In this paper, it is shown that if we replace the assumption regarding the existence of incoming and outgoing subspaces by the assumption of the existence of Lyapunov operators for the quantum evolution (the existence of which has been proved for certain classes of quantum mechanical scattering problems), then it is possible to construct a structure analogous to the Lax-Phillips structure for scattering problems for which the spectrum of the generator of evolution is bounded from below.
A modified Lax-Phillips scattering theory for quantum mechanics
Strauss, Y.
2015-07-15
The Lax-Phillips scattering theory is an appealing abstract framework for the analysis of scattering resonances. Quantum mechanical adaptations of the theory have been proposed. However, since these quantum adaptations essentially retain the original structure of the theory, assuming the existence of incoming and outgoing subspaces for the evolution and requiring the spectrum of the generator of evolution to be unbounded from below, their range of applications is rather limited. In this paper, it is shown that if we replace the assumption regarding the existence of incoming and outgoing subspaces by the assumption of the existence of Lyapunov operators for the quantum evolution (the existence of which has been proved for certain classes of quantum mechanical scattering problems), then it is possible to construct a structure analogous to the Lax-Phillips structure for scattering problems for which the spectrum of the generator of evolution is bounded from below.
Lee, Myung W.
2008-01-01
Elastic velocities of water-saturated sandstones depend primarily on porosity, effective pressure, and the degree of consolidation. If the dry-frame moduli are known, from either measurements or theoretical calculations, the effect of pore water on velocities can be modeled using the Gassmann theory. Kuster and Toksoz developed a theory based on wave-scattering theory for a variety of inclusion shapes, which provides a means for calculating dry- or wet-frame moduli. In the Kuster-Toksoz theory, elastic wave velocities through different sediments can be predicted by using different aspect ratios of the sediment's pore space. Elastic velocities increase as the pore aspect ratio increases (larger pore aspect ratio describes a more spherical pore). On the basis of the velocity ratio, which is assumed to be a function of (1-0)n, and the Biot-Gassmann theory, Lee developed a semi-empirical equation for predicting elastic velocities, which is referred to as the modified Biot-Gassmann theory of Lee. In this formulation, the exponent n, which depends on the effective pressure and the degree of consolidation, controls elastic velocities; as n increases, elastic velocities decrease. Computationally, the role of exponent n in the modified Biot-Gassmann theory by Lee is similar to the role of pore aspect ratios in the Kuster-Toksoz theory. For consolidated sediments, either theory predicts accurate velocities. However, for unconsolidated sediments, the modified Biot-Gassmann theory by Lee performs better than the Kuster-Toksoz theory, particularly in predicting S-wave velocities.
Research on a Modified Framework of Implicit Personality Theories
ERIC Educational Resources Information Center
Ziegler, Albert; Stoeger, Heidrun
2010-01-01
There is ample evidence that labeled gifted students exhibit maladaptive behavior patterns. According to Carol Dweck those students who subscribe to a fixed view of their abilities are particularly at risk. In this contribution we extended Dweck's framework and distinguished two aspects of the implicit theory of one's own abilities. We…
Making School Reform Work: A "Mineralogical" Theory of School Modifiability. Fastback 467.
ERIC Educational Resources Information Center
Sternberg, Robert J.
This booklet proposes a different approach to understanding schools, school change, and why attempts at change run into so many difficulties. The text is divided into six parts. It examines issues in school reform and restructuring and offers what is called a Mineralogical Theory of school modifiability. This theory posits that there are eight…
Microscopic Theory of Modified Spontaneous Emission in a Dielectric
NASA Astrophysics Data System (ADS)
Berman, P. R.; Milonni, P. W.
2004-02-01
The modification of the radiative decay rate of a source atom embedded in a uniform, isotropic dielectric is calculated to first order in the density of the dielectric atoms using a microscopic approach. In contrast to the recent results of Crenshaw and Bowden [
Halo velocity profiles in screened modified gravity theories
NASA Astrophysics Data System (ADS)
Gronke, M.; Llinares, C.; Mota, D. F.; Winther, H. A.
2015-05-01
Screened modified gravity predicts potentially large signatures in the peculiar velocity field that makes it an interesting probe to test gravity on cosmological scales. We investigate the signatures induced by the Symmetron and a Chameleon f(R) model in the peculiar velocity field using N-body simulations. By studying fifth force and halo velocity profiles, we identify three general categories of effects found in screened modified gravity models: a fully screened regime where we recover Λ cold dark matter to high precision, an unscreened regime where the fifth force is in full operation, and, a partially screened regime where screening occurs in the inner part of a halo, but the fifth force is active at larger radii. These three regimes can be pointed out very clearly by analysing the deviation in the maximum cluster velocity. Observationally, the partially screened regime is of particular interest since an uniform increase of the gravitational force - as present in the unscreened regime - is degenerate with the (dynamical) halo mass estimate, and, thus, hard to detect.
Theory of room temperature ferromagnetism in Cr modified DNA nanowire
NASA Astrophysics Data System (ADS)
Paruğ Duru, Izzet; Değer, Caner; Eldem, Vahap; Kalayci, Taner; Aktaş, Şahin
2016-04-01
We investigated the magnetic properties of Cr3+ (J < 0) ion-modified DNA (M-DNA) nanowire (1000 base) at room temperature under a uniform magnetic field (˜100 Oe) for different doping concentrations. A Monte Carlo simulation method-based Metropolis algorithm is used to figure out the thermodynamic quantities of nanowire formed by Cr M-DNA followed by analysing the dependency of the ferromagnetic behaviour of the M-DNA to dopant concentration. It is understood that ion density/base and ion density/helical of Cr3+ ions can be a tuning parameter, herewith the dopant ratio has an actual importance on the magnetic characterization of M-DNA nanowire (3%-20%). We propose the source of magnetism as an exchange interaction between Cr and DNA helical atoms indicated in the Heisenberg Hamiltonian.
Modified gravity theories: Alternatives to the missing mass and missing energy problems
NASA Astrophysics Data System (ADS)
Soussa, Marc Edward
Modified theories of gravity are examined and shown to be alternative possibilities to the standard paradigms of dark matter and dark energy in explaining the currently observed cosmological phenomenology. Special consideration is given to the relativistic extension of Modified Newtonian Dynamics (MOND) in supplanting the need for dark matter. A specific modification of the Einstein-Hilbert action (whereby an inverse power of the Ricci scalar is added) is shown to serve as an alternative to dark energy.
NASA Astrophysics Data System (ADS)
Zhao, Hongsheng; Li, Baojiu; Bienaymé, Olivier
2010-11-01
We derive a simple analytical expression for the two-body force in a subclass of modified Newtonian dynamics (MOND) theories and make testable predictions in the modification to the two-body orbital period, shape, precession rate, escape speed, etc. We demonstrate the applications of the modified Kepler’s law in the timing of satellite orbits around the Milky Way, and checking the feasibility of MOND in the orbit of the large Magellanic cloud, the M31 galaxy, and the merging bullet clusters. MOND appears to be consistent with satellite orbits although with a tight margin. Our results on two-bodies are also generalized to restricted three-body, many-body problems, rings, and shells.
Modified Coulomb-Dipole Theory for 2e Photoionization
NASA Technical Reports Server (NTRS)
2004-01-01
In the light of recent experiment on 2e photoionization of Li near threshold, we have considered a modification of the Coulomb-dipole theory, retaining the basic assumption that the threshold is dominated by asymmetric events in phase space [implies r(sub 1), k(sub 1)) greater than or equal to 2(r(sub 2), k(sub )]. In this region [in a collinear model, 2/r(sub 12) approached + 2/(r(sub 1)+r(sub 2)] the interaction reduces to V(rIsub 1) is greater than or equal to 2r(sub 2) is identically equal to [(-Z/r(sub 2)-(A-1)/r(sub 1)] + [(-2r(sub 2)/r(sub 1 exp 2)] is identically equal to V(sub c)+[V(sub d)]. For two electron emission Z = 2, thus both electrons see a Coulomb potential (V(sub c)) asymptotically, albeit each seeing a different charge. The residual potential (V(sub d)) is dipole in character. Writing the total psi = psi (sub c) + psi(sub d) = delta psi, and noting that. (T+V(sub c)-E)psy(sub c) = 0 and (T+V(sub c))psi(sub d) = 0 can be solved exactly, we find, substituting psi into the complete Schrod. Eq., that delta psi = -(H-E)(exp -1)(V(sub d) psi(sub 0)+V(sub c psi (sub 1). Using the fact that the absolute value of V(sub c) is much more than the absolute value of V(sub d) in almost all of configuration space, we can replace H by H(sub 0) in 9H-E)(exp -1) to obtain an improved approximation psi (improved) = psi(sub c) + psi(sub d) -(H(sub 0)-E)(exp -1) (V(sub c) psi (sub 0) + V(sub c) psi(sub 1). Here's the Green's function (H(sub 0)-E)(exp -1), can be exhibited explicitly, but the last term in psi (improved) is small, compared to the first two terms. Inserting them into the transition matrix element, which one handles in the usual way, we obtain in the limit E approaches 0, the threshold law: Q(E) alpha E + M(E)E(exp 5/4) + higher order (Eq. 1a). The modulation function, M(E), is a well-defined (but very non-trivial integral, but it is expected to be well approximated by a sinusoidal function containing a dipole phase term (M(E) = c sin[alpha log (E
Effective-range approximations for resonant scattering of cold atoms
NASA Astrophysics Data System (ADS)
Blackley, Caroline L.; Julienne, Paul S.; Hutson, Jeremy M.
2014-04-01
Studies of cold atom collisions and few-body interactions often require the energy dependence of the scattering phase shift, which is usually expressed in terms of an effective-range expansion. We use accurate coupled-channel calculations on 6Li, 39K, and 133Cs to explore the behavior of the effective range in the vicinity of both broad and narrow Feshbach resonances. We show that commonly used expressions for the effective range break down dramatically for narrow resonances and near the zero crossings of broad resonances. We present an alternative parametrization of the effective range that is accurate through both the pole and the zero crossing for both broad and narrow resonances. However, the effective-range expansion can still fail at quite low collision energies, particularly around narrow resonances. We demonstrate that an analytical form of an energy and magnetic-field-dependent phase shift, based on multichannel quantum defect theory, gives accurate results for the energy-dependent scattering length.
Exploring the Role of Diagnosis in the Modified Labeling Theory of Mental Illness
ERIC Educational Resources Information Center
Kroska, Amy; Harkness, Sarah K.
2008-01-01
According to the modified labeling theory of mental illness, when an individual is diagnosed with a mental illness, cultural ideas associated with the mentally ill become personally relevant and foster negative self-feelings. We explore the way that psychiatric diagnosis shapes this process. Specifically, we examine if and how psychiatric…
Lensing-induced morphology changes in CMB temperature maps in modified gravity theories
NASA Astrophysics Data System (ADS)
Munshi, D.; Hu, B.; Matsubara, T.; Coles, P.; Heavens, A.
2016-04-01
Lensing of the Cosmic Microwave Background (CMB) changes the morphology of pattern of temperature fluctuations, so topological descriptors such as Minkowski Functionals can probe the gravity model responsible for the lensing. We show how the recently introduced two-to-two and three-to-one kurt-spectra (and their associated correlation functions), which depend on the power spectrum of the lensing potential, can be used to probe modified gravity theories such as f(R) theories of gravity and quintessence models. We also investigate models based on effective field theory, which include the constant-Ω model, and low-energy Hořava theories. Estimates of the cumulative signal-to-noise for detection of lensing-induced morphology changes, reaches Script O(103) for the future planned CMB polarization mission COrE+. Assuming foreground removal is possible to lmax=3000, we show that many modified gravity theories can be rejected with a high level of significance, making this technique comparable in power to galaxy weak lensing or redshift surveys. These topological estimators are also useful in distinguishing lensing from other scattering secondaries at the level of the four-point function or trispectrum. Examples include the kinetic Sunyaev-Zel'dovich (kSZ) effect which shares, with lensing, a lack of spectral distortion. We also discuss the complication of foreground contamination from unsubtracted point sources.
Supersymmetric inversion of effective-range expansions
NASA Astrophysics Data System (ADS)
Midya, Bikashkali; Evrard, Jérémie; Abramowicz, Sylvain; Ramírez Suárez, O. L.; Sparenberg, Jean-Marc
2015-05-01
A complete and consistent inversion technique is proposed to derive an accurate interaction potential from an effective-range function for a given partial wave in the neutral case. First, the effective-range function is Taylor or Padé expanded, which allows high precision fitting of the experimental scattering phase shifts with a minimal number of parameters on a large energy range. Second, the corresponding poles of the scattering matrix are extracted in the complex wave-number plane. Third, the interaction potential is constructed with supersymmetric transformations of the radial Schrödinger equation. As an illustration, the method is applied to the experimental phase shifts of the neutron-proton elastic scattering in the 1S0 and 1D2 channels on the [0 -350 ] MeV laboratory energy interval.
Yalçın, Uğur; Sarnık, Mücahit
2013-01-01
The uniform diffracted fields are calculated on PEC cylindrical reflector by Modified Theory of Physical Optics (MTPO). It is aimed to convert the noncontinuous solution to a continuous solution by finding a uniform equation which does not contain any expression converging to 0 in the denominator part. Three axioms of MTPO theory are used to construct the integral equations for the perfectly electrically conducting surface application. The "edge-point" technique is used to find the diffracted field, and uniform solution is to be found via "detour parameter(s)." Finally, the obtained results are to be compared with the nonuniform ones, numerically. PMID:23766679
Axisymmetric Distributions of Thick Circular Plate in a Modified Couple Stress Theory
NASA Astrophysics Data System (ADS)
Kumar, Rajneesh; Marin, Marin; Abbas, Ibrahim A.
2015-07-01
In this paper, the two-dimensional axisymmetric distributions of thick circular plate in modified couple stress theory with heat and mass diffusive sources is investigated. The problem is considered in the context of the theories of thermodiffusion elastic solid with one and two relaxation time developed by Sherief et al. [Int. J. Eng. Sci. 42, 591 (2004)] and Kumar and Kansal [Int. J. Solid Struct. 45, 5890 (2008)] by using Laplace and Hankel transforms technique. The displacements, stress components, temperature change and chemical potential are obtained in transformed domain. Particular cases of interest are also deduced.
Causality and the effective range expansion
Hammer, H.-W.; Lee, Dean
2010-10-15
We derive the generalization of Wigner's causality bounds and Bethe's integral formula for the effective range parameter to arbitrary dimension and arbitrary angular momentum. We also discuss the impact of these constraints on the separation of low- and high-momentum scales and universality in low-energy scattering. Some of our results were summarized earlier in a letter publication. In this work, we present full derivations and several detailed examples.
Constraining Modified Theories of Gravity with Gravitational-Wave Stochastic Backgrounds.
Maselli, Andrea; Marassi, Stefania; Ferrari, Valeria; Kokkotas, Kostas; Schneider, Raffaella
2016-08-26
The direct discovery of gravitational waves has finally opened a new observational window on our Universe, suggesting that the population of coalescing binary black holes is larger than previously expected. These sources produce an unresolved background of gravitational waves, potentially observable by ground-based interferometers. In this Letter we investigate how modified theories of gravity, modeled using the parametrized post-Einsteinian formalism, affect the expected signal, and analyze the detectability of the resulting stochastic background by current and future ground-based interferometers. We find the constraints that Advanced LIGO would be able to set on modified theories, showing that they may significantly improve the current bounds obtained from astrophysical observations of binary pulsars. PMID:27610838
Awuah, Joel B; Dzade, Nelson Y; Tia, Richard; Adei, Evans; Kwakye-Awuah, Bright; Richard A Catlow, C; de Leeuw, Nora H
2016-04-20
We present density functional theory calculations of the adsorption of arsenic acid (AsO(OH)3) and arsenous acid (As(OH)3) on the Al(iii)-modified natural zeolite clinoptilolite under anhydrous and hydrated conditions. From our calculated adsorption energies, we show that adsorption of both arsenic species is favorable (associative and exothermic) under anhydrous conditions. When the zeolite is hydrated, adsorption is less favourable, with the water molecules causing dissociation of the arsenic complexes, although exothermic adsorption is still observed for some sites. The strength of interaction of the arsenic complexes is shown to depend sensitively on the Si/Al ratio in the Al(iii)-modified clinoptilolite, which decreases as the Si/Al ratio increases. The calculated large adsorption energies indicate the potential of Al(iii)-modified clinoptilolite for arsenic immobilization. PMID:27052997
Chern-Simons modified gravity as a torsion theory and its interaction with fermions
Alexander, Stephon; Yunes, Nicolas
2008-06-15
We study the tetrad formulation of Chern-Simons (CS) modified gravity, which adds a Pontryagin term to the Einstein-Hilbert action with a spacetime-dependent coupling field. We first verify that CS modified gravity leads to a theory with torsion, where this tensor is given by an antisymmetric product of the Riemann tensor and derivatives of the CS coupling. We then calculate the torsion in the far field of a weakly gravitating source within the parameterized post-Newtonian formalism, and specialize the result to Earth. We find that CS torsion vanishes only if the coupling vanishes, thus generically leading to a modification of gyroscopic precession, irrespective of the coupling choice. Perhaps most interestingly, we couple fermions to CS modified gravity via the standard Dirac action and find that these further correct the torsion tensor. Such a correction leads to two new results: (i) a generic enhancement of CS modified gravity by the Dirac equation and axial fermion currents; (ii) a new two-fermion interaction, mediated by an axial current and the CS correction. We conclude with a discussion of the consequences of these results in particle detectors and realistic astrophysical systems.
Smoking guns of a bounce in modified theories of gravity through the spectrum of gravitational waves
NASA Astrophysics Data System (ADS)
Bouhmadi-López, Mariam; Morais, João; Henriques, Alfredo B.
2013-05-01
We present an inflationary model preceded by a bounce in a metric theory à la f(R), where R is the scalar curvature of the space-time. The model is asymptotically de Sitter such that the gravitational action tends asymptotically to an Einstein-Hilbert action with an effective cosmological constant; therefore, modified gravity affects only the early stages of the Universe. We then analyze the spectrum of the gravitational waves through the method of the Bogoliubov coefficients by two means: taking into account the gravitational perturbations due to the modified gravitational action in the f(R) setup and simply considering those perturbations inherent to the standard Einstein-Hilbert action. We show that there are distinctive (oscillatory) signals on the spectrum for very low frequencies; i.e., corresponding to modes that are currently entering the horizon.
Applicability of the Newman-Janis algorithm to black hole solutions of modified gravity theories
NASA Astrophysics Data System (ADS)
Hansen, Devin; Yunes, Nicolás
2013-11-01
The Newman-Janis algorithm has been widely used to construct rotating black hole solutions from nonrotating counterparts. While this algorithm was developed within general relativity (GR), it has more recently been applied to nonrotating solutions in modified gravity theories. We find that the application of the Newman-Janis algorithm to an arbitrary non-GR spherically symmetric solution introduces pathologies in the resulting axially symmetric metric. This then establishes that, in general, the Newman-Janis algorithm should not be used to construct rotating black hole solutions outside of General Relativity.
Modified Theories of Gravity with Nonminimal Coupling and the Faint Young Sun Paradox
NASA Astrophysics Data System (ADS)
Iorio, Lorenzo
2016-01-01
A certain general class of modified gravitational theories with nonminimal coupling predicts a "pressure"-type, non-geodesic acceleration for a non-rotating, massive test particle. The resulting orbital perturbations for a two-body system consist of secular rates of change of all the standard orbital elements. The resulting variation of the mutual distance yields a physical mechanism which has the potential capability to explain, in principle, the Faint Young Sun Paradox in terms of a recession of the Earth from the Sun during the Archean.
NASA Astrophysics Data System (ADS)
Sourki, R.; Hoseini, S. A. H.
2016-04-01
This paper investigates the analysis for free transverse vibration of a cracked microbeam based on the modified couple stress theory within the framework of Euler-Bernoulli beam theory. The governing equation and the related boundary conditions are derived by using Hamilton's principle. The cracked beam is modeled by dividing the beam into two segments connected by a rotational spring located at the cracked section. This model invokes the consideration of the additional strain energy caused by the crack and promotes a discontinuity in the bending slope. In this investigation, the influence of diverse crack position, crack severity, material length scale parameter as well as various Poisson's ratio on natural frequencies is studied. A comparison with the previously published studies is made, in which a good agreement is observed. The results illustrate that the aforementioned parameters are playing a significant role on the dynamic behavior of the microbeam.
One-body potential theory of molecules and solids modified semiempirically for electron correlation
NASA Astrophysics Data System (ADS)
March, N. H.
2010-10-01
The study of Cordero, March and Alonso (CMA) for four spherical atoms, Be, Ne, Mg and Ar, semiempirically fine-tunes the Hartree-Fock (HF) ground-state electron density by inserting the experimentally determined ionization potentials. The present Letter, first of all, relates this approach to the very recent work of Bartlett ‘towards an exact correlated orbital theory for electrons’. Both methods relax the requirement of standard DFT that a one-body potential shall generate the exact ground-state density, though both work with high quality approximations. Unlike DFT, the CMA theory uses a modified HF non-local potential. It is finally stressed that this potential generates also an idempotent Dirac density matrix. The CMA approach is thereby demonstrated to relate, albeit approximately, to the DFT exchange-correlation potential.
The black hole merger event GW150914 within a modified theory of General Relativity
NASA Astrophysics Data System (ADS)
Hess, P. O.
2016-08-01
In February 2016 the first observation of gravitational waves were reported. The source of this event, denoted as GW150914, was identified as the merger of two black holes with a about 30 solar masses each, at a distance of approximately 400Mpc. These data where deduced using the Theory of General Relativity. Since 2009 a modified theory was proposed which adds near massive objects phenomenologically the contribution of a dark energy, whose origin are vacuum fluctuations. The dark energy accumulates toward smaller distances, reducing effectively the gravitational constant. In this contribution we show that as a consequence the deduces chirping mass and the luminosity distance are larger. This result suggests that the black hole merger corresponds to two massive black holes near the center of primordial galaxies at large luminosity distance, i.e. large redshifts.
Criterion for DNA melting in the mean-field modified self-consistent phonon theory
NASA Astrophysics Data System (ADS)
Feng, Y.; Prohofsky, E. W.
1991-04-01
We have examined the validity of the first-order-perturbation method in calculating eigenfunctions and the criterion for helix melting of mean-field polymers in the modified self-consistent phonon approach (MSPA) theory. It is found that the instability in the self-consistent solution is due to the breakdown of the first-order perturbation. The instability as a criterion for helix melting is therefore techniquely inappropriate. However, the breakdown of the perturbation is due to facts that are directly related to the onset of softening. Previously predicted melting temperatures for various sequence DNA polymers may still represent good estimates to the actual melting temperatures. An alternative criterion is required to define the melting temperature of the polymer DNA double helix in the MSPA theory.
New two-sided bound on the isotropic Lorentz-violating parameter of modified Maxwell theory
Klinkhamer, F. R.; Schreck, M.
2008-10-15
There is a unique Lorentz-violating modification of the Maxwell theory of photons, which maintains gauge invariance, CPT, and renormalizability. Restricting the modified-Maxwell theory to the isotropic sector and adding a standard spin-(1/2) Dirac particle p{sup {+-}} with minimal coupling to the nonstandard photon {gamma}-tilde, the resulting modified-quantum-electrodynamics model involves a single dimensionless 'deformation parameter', {kappa}-tilde{sub tr}. The exact tree-level decay rates for two processes have been calculated: vacuum Cherenkov radiation p{sup {+-}}{yields}p{sup {+-}}{gamma}-tilde for the case of positive {kappa}-tilde{sub tr} and photon decay {gamma}-tilde{yields}p{sup +}p{sup -} for the case of negative {kappa}-tilde{sub tr}. From the inferred absence of these decays for a particular high-quality ultrahigh-energy-cosmic-ray event detected at the Pierre Auger Observatory and a well-established excess of TeV gamma-ray events observed by the High Energy Stereoscopic System telescopes, a two-sided bound on {kappa}-tilde{sub tr} is obtained, which improves by 8 orders of magnitude upon the best direct laboratory bound. The implications of this result are briefly discussed.
Probability of primordial black hole pair creation in a modified gravitational theory
Paul, B. C.; Paul, Dilip
2006-10-15
We compute the probability for quantum creation of an inflationary universe with and without a pair of black holes in a modified gravity. The action of the modified theory of gravity contains {alpha}R{sup 2} and {delta}R{sup -1} terms in addition to a cosmological constant ({lambda}) in the Einstein-Hilbert action. The probabilities for the creation of universe with a pair of black holes have been evaluated considering two different kinds of spatial sections, one which accommodates a pair of black holes and the other without black hole. We adopt a technique prescribed by Bousso and Hawking to calculate the above creation probability in a semiclassical approximation using the Hartle-Hawking boundary condition. We note a class of new and physically interesting instanton solutions characterized by the parameters in the action. These instantons may play an important role in the creation of the early universe. We also note that the probability of creation of a universe with a pair of black holes is strongly suppressed with a positive cosmological constant when {delta}=(4{lambda}{sup 2}/3) for {alpha}>0 but it is more probable for {alpha}<-(1/6{lambda}). In the modified gravity considered here instanton solutions are permitted even without a cosmological constant when one begins with a negative {delta}.
Modified Gauss-Bonnet gravity with the Lagrange multiplier constraint as mimetic theory
NASA Astrophysics Data System (ADS)
Astashenok, Artyom V.; Odintsov, Sergei D.; Oikonomou, V. K.
2015-09-01
In this paper we propose and extensively study mimetic f({G}) modified gravity models, with various scenarios of cosmological evolution, with or without extra matter fluids. The easiest formulation is based on the use of the Lagrange multiplier constraint. In certain versions of this theory, it is possible to realize accelerated expansion of the Universe or even unified evolution, which includes inflation with dark energy, and at the same time in the same theoretical framework, dark matter is described by the theory. This is achieved by the re-parametrization of the metric tensor, which introduces a new degree of freedom in the cosmological equations and leads to the appearance of the mimetic ‘dark matter’ component. In the context of the mimetic f({G}) theory, we also provide some quite general reconstruction schemes, which enable us to find which f({G}) gravity generates a specific cosmological evolution. In addition, we also provide the general reconstruction technique for the Lagrange multiplier f({G}) gravity. All our results are accompanied by illustrative examples, with special emphasis on bouncing cosmologies.
Bernoulli Euler beam model based on a modified couple stress theory
NASA Astrophysics Data System (ADS)
Park, S. K.; Gao, X.-L.
2006-11-01
A new model for the bending of a Bernoulli-Euler beam is developed using a modified couple stress theory. A variational formulation based on the principle of minimum total potential energy is employed. The new model contains an internal material length scale parameter and can capture the size effect, unlike the classical Bernoulli-Euler beam model. The former reduces to the latter in the absence of the material length scale parameter. As a direct application of the new model, a cantilever beam problem is solved. It is found that the bending rigidity of the cantilever beam predicted by the newly developed model is larger than that predicted by the classical beam model. The difference between the deflections predicted by the two models is very significant when the beam thickness is small, but is diminishing with the increase of the beam thickness. A comparison shows that the predicted size effect agrees fairly well with that observed experimentally.
Andersson, M P
2016-07-28
We have performed density functional theory calculations using our modified DFT-D2 dispersion correction for metals to investigate adsorption of a range of molecules on Pt(111). The agreement between our calculations and experimental adsorption energies ranging from 0 to 3 eV was excellent with a mean absolute deviation of 0.19 eV and a maximum deviation of 0.37 eV. Our results show that the DFT-D2 semiempirical dispersion correction can provide accurate results also for describing adsorption on metals, provided that relevant physical properties of the system are taken into account, such as shorter ranged dispersion because of screening by the conducting electrons and a lower polarizability of the core electrons in metals compared to isolated atoms. PMID:27357643
Covariant anomaly and Hawking radiation from the modified black hole in the rainbow gravity theory
NASA Astrophysics Data System (ADS)
Peng, Jun-Jin; Wu, Shuang-Qing
2008-12-01
Recently, Banerjee and Kulkarni (R. Banerjee, S. Kulkarni, arXiv: 0707. 2449 [hep-th]) suggested that it is conceptually clean and economical to use only the covariant anomaly to derive Hawking radiation from a black hole. Based upon this simplified formalism, we apply the covariant anomaly cancellation method to investigate Hawking radiation from a modified Schwarzschild black hole in the theory of rainbow gravity. Hawking temperature of the gravity’s rainbow black hole is derived from the energy-momentum flux by requiring it to cancel the covariant gravitational anomaly at the horizon. We stress that this temperature is exactly the same as that calculated by the method of cancelling the consistent anomaly.
Binary Mixture of Perfect Fluid and Dark Energy in Modified Theory of Gravity
NASA Astrophysics Data System (ADS)
Shaikh, A. Y.
2016-07-01
A self consistent system of Plane Symmetric gravitational field and a binary mixture of perfect fluid and dark energy in a modified theory of gravity are considered. The gravitational field plays crucial role in the formation of soliton-like solutions, i.e., solutions with limited total energy, spin, and charge. The perfect fluid is taken to be the one obeying the usual equation of state, i.e., p = γρ with γ∈ [0, 1] whereas, the dark energy is considered to be either the quintessence like equation of state or Chaplygin gas. The exact solutions to the corresponding field equations are obtained for power-law and exponential volumetric expansion. The geometrical and physical parameters for both the models are studied.
Park, Bong-Won; Lee, Kun Chang
2011-01-01
The aims of this article are (1) to propose a modified theory of consumption values (MTCV) for investigation of online gamer perceptions of the value of purchasable game items and (2) to apply the developed MTCV to multiple game genres and player age groups. To address these aims, 327 valid questionnaires were obtained and analyzed. The original theory of consumption values (TCV) was modified to apply to the specific characteristics of online games. The original TCV specifies five types of consumption values: functional value, social value, emotional value, conditional value, and epistemic value. After revising the TCV to apply to the examination of online games, we proposed that the MTCV be composed of character competency value, enjoyment value, visual authority value, and monetary value. The validity of the MTCV was proven by statistically analyzing the responses provided by the 327 valid questionnaires. To examine the second aim, experiments were conducted to examine the MTCV in three online game genres-massive multiplayer online role-playing games, first-person shooters games, and casual games. The second aim was also studied via questionnaires that examined the ages of online gamers. It was determined that massive multiplayer online role-playing games players regard visual authority value and monetary value as more important than do casual gamers. It was also determined that younger gamers tend to be more interested in visual authority, whereas older gamers tend to be more interested in character competency. This research provides a foundation for future studies to extend the MTCV to consider other user factors, such as cultural effects. PMID:21288134
Modeling gravity-driven fingering in rough-walled fractures using modified percolation theory
Glass, R.J.
1992-12-31
Pore scale invasion percolation theory is modified for imbibition of.wetting fluids into fractures. The effects of gravity, local aperture field geometry, and local in-plane air/water interfacial curvatureare included in the calculation of aperture filling potential which controls wetted structure growth within the fracture. The inclusion of gravity yields fingers oriented in the direction of the gravitational gradient. These fingers widen and tend to meander and branch more as the gravitational gradient decreases. In-plane interfacial curvature also greatly affects the wetted structure in both horizontal and nonhorizontal fractures causing the formation of macroscopic wetting fronts. The modified percolation model is used to simulate imbibition into an analogue rough-walled fracture where both fingering and horizontal imbibition experiments were previously conducted. Comparison of numerical and experimental results showed reasonably good agreement. This process oriented physical and numerical modeling is-a necessary step toward including gravity-driven fingering in models of flow and transport through unsaturated, fractured rock.
Density functional theory calculations of phenol-modified monolayer silicon nanosheets
NASA Astrophysics Data System (ADS)
Spencer, Michelle J. S.; Morishita, Tetsuya; Bassett, Michael R.
2013-12-01
Silicon nanosheets are one of most exciting recent discoveries, being a two-dimensional form of silicon that is only nanometers thick, with large lateral dimensions. A single atomic layer silicon nanosheet is known as silicene and can be grown with different surface terminations. It has been shown previously that organo-modified silicene can be synthesised with phenyl groups covalently bonded to both sides of the nanosheet, with hydrogen atoms terminating the undercoordinated silicon atoms. In this work, we use density functional theory calculations and ab initio molecular dynamics simulations to determine the effect of hydroxyl (OH) group substitutions on the phenyl-modified silicene. Different positions of the OH groups on the phenyl rings were modelled including ortho-, meta- and para- substituted positions. We found that the meta-substituted position was favoured, followed by the para- then ortho- substituted positions. Our ab initio MD simulations showed that the phenol groups will freely rotate on the nanosheet, aligning so as to form hydrogen bonds between adjacent phenol groups. The unique properties of this material could be useful for future electronic device applications.
Winskel, Heather; Perea, Manuel; Peart, Emma
2014-07-01
In the current study, we tested the generality of the modified receptive field (MRF) theory (Tydgat & Grainger, 2009) with English native speakers (Experiment 1) and Thai native speakers (Experiment 2). Thai has a distinctive alphabetic orthography with visually complex letters (ฝ ฟ or ผ พ) and nonlinear characteristics and lacks interword spaces. We used a two-alternative forced choice (2AFC) procedure to measure identification accuracy for all positions in a string of five characters, which consisted of Roman script letters, Thai letters, or symbols. For the English speakers, we found a similar pattern of results as in previous studies (i.e., a dissociation between letters and symbols). In contrast, for the Thai participants, we found that the pattern for Thai letters, Roman letters and symbols displayed a remarkably similar linear trend. Thus, while we observed qualified support for the MRF theory, in that we found an advantage for initial position, this effect also applied to symbols (i.e., our data revealed a language-specific effect). We propose that this pattern for letters and symbols in Thai has developed as a specialized adaptive mechanism for reading in this visually complex and crowded nonlinear script without interword spaces. PMID:24818534
Unified cosmic history in modified gravity: From F(R) theory to Lorentz non-invariant models
NASA Astrophysics Data System (ADS)
Nojiri, Shin'Ichi; Odintsov, Sergei D.
2011-08-01
The classical generalization of general relativity is considered as the gravitational alternative for a unified description of the early-time inflation with late-time cosmic acceleration. The structure and cosmological properties of a number of modified theories, including traditional F(R) and Hořava-Lifshitz F(R) gravity, scalar-tensor theory, string-inspired and Gauss-Bonnet theory, non-local gravity, non-minimally coupled models, and power-counting renormalizable covariant gravity are discussed. Different representations of and relations between such theories are investigated. It is shown that some versions of the above theories may be consistent with local tests and may provide a qualitatively reasonable unified description of inflation with the dark energy epoch. The cosmological reconstruction of different modified gravities is provided in great detail. It is demonstrated that eventually any given universe evolution may be reconstructed for the theories under consideration, and the explicit reconstruction is applied to an accelerating spatially flat Friedmann-Robertson-Walker (FRW) universe. Special attention is paid to Lagrange multiplier constrained and conventional F(R) gravities, for latter F(R) theory, the effective ΛCDM era and phantom divide crossing acceleration are obtained. The occurrences of the Big Rip and other finite-time future singularities in modified gravity are reviewed along with their solutions via the addition of higher-derivative gravitational invariants.
NASA Astrophysics Data System (ADS)
Kiani, M.; Alavianmehr, M. M.; Otoofat, M.; Mohsenipour, A. A.; Ghatee, A.
2015-11-01
In this work, we identify a simple method for predicting transport properties of fluids over wide ranges of temperatures and pressure. In this respect, the capability of several equations of state (EOS) and second virial coefficient correlations to predict transport properties of fluids including carbon dioxide, methane and argon using modified Enskog theory (MET) is investigated. The transport properties in question are viscosity and thermal conductivity. The results indicate that the SRK EOS employed in the modified Enskog theory outperforms other equations of state. The average absolute deviation was found to be 12.2 and 18.5% for, respectively, the calculated thermal conductivity and viscosity using the MET.
Estimation of thermodynamic properties of Cu-La binary alloy with modified Miedema's theory
NASA Astrophysics Data System (ADS)
Li, Hai-hong; Zhang, Shi-hong; Chen, Yan; Cheng, Ming; Song, Hong-wu; Liu, Jin-song
2016-01-01
According to modified Miedema's theory, mixing enthalpies (Δ H), excess entropies ( S E), excess Gibbs free energy ( G E), and component activities ( a) of Cu-La binary alloy were estimated using the basic thermodynamic principles and some simple physical parameters of Cu and La, such as electronegativity, atomic volume and electron density. Based on the Cu-La binary alloy phase diagram, the Gibbs free energy of the phase precipitation reactions of Cu6La and Cu5La was deduced. The results showed that the values of Δ H, S E, and G E of Cu-La binary alloy were all negative. Compared to the ideal solution, the activities of the components presented a large negative deviation from Raoult's law, which indicated that there was a strong interaction between Cu and La. The calculated data are well consistent with the experimental data. The Gibbs free energies of the phase precipitation reactions of Cu6La are lower than those for Cu5La, which means that Cu6La is thermodynamically more stable than Cu5La. Furthermore, the experimental results show that rareearth rich Cu6La phase particles in copper matrix are formed after La microalloying.
NASA Astrophysics Data System (ADS)
Bel, Julien; Brax, Philippe; Marinoni, Christian; Valageas, Patrick
2015-05-01
The clustering ratio η , a large-scale structure observable originally designed to constrain the shape of the power spectrum of matter density fluctuations, is shown to provide a sensitive probe of the nature of gravity in the cosmological regime. We apply this analysis to F (R ) theories of gravity using the luminous red galaxy sample extracted from the spectroscopic Sloan Digital Sky Survey (SDSS) data release 7 and 10 catalogs. We find that general relativity (GR), complemented with a Friedmann-Robertson-Walker (FRW) cosmological model with parameters fixed by the Planck satellite, describes extremely well the clustering of galaxies up to z ˜0.6 . On large cosmic scales, the absolute amplitude of deviations from GR, |fR 0|, is constrained to be smaller than 4.6 ×1 0-5 at the 95% confidence level. This bound makes cosmological probes of gravity almost competitive with the sensitivity of Solar System tests, although still one 1 order of magnitude less effective than astrophysical tests. We also extrapolate our results to future large surveys like Euclid and show that the astrophysical bound will certainly remain out of reach for such a class of modified-gravity models that only differ from Λ CDM at low redshifts.
Lee, Haw-Long; Chang, Win-Jin
2016-01-01
The modified couple stress theory is adopted to study the sensitivity of a rectangular atomic force microscope (AFM) cantilever immersed in acetone, water, carbon tetrachloride (CCl4), and 1-butanol. The theory contains a material length scale parameter and considers the size effect in the analysis. However, this parameter is difficult to obtain via experimental measurements. In this study, a conjugate gradient method for the parameter estimation of the frequency equation is presented. The optimal method provides a quantitative approach for estimating the material length scale parameter based on the modified couple stress theory. The results show that the material length scale parameter of the AFM cantilever immersed in acetone, CCl4, water, and 1-butanol is 0, 25, 116.3, and 471 nm, respectively. In addition, the vibration sensitivities of the AFM cantilever immersed in these liquids are investigated. The results are useful for the design of AFM cantilevers immersed in liquids. PMID:26402914
Vector-tensor nature of Bekenstein's relativistic theory of modified gravity
Zlosnik, T. G.; Ferreira, P. G.; Starkman, Glenn D.
2006-08-15
Bekenstein's theory of relativistic gravity is conventionally written as a bimetric theory. The two metrics are related by a disformal transformation defined by a dynamical vector field and a scalar field. In this paper we show that the theory can be rewritten as vector-tensor theory akin to Einstein-Aether theories with noncanonical kinetic terms. We discuss some of the implications of this equivalence.
Glass, Joseph E.; Mowbray, Orion P.; Link, Bruce G.; Kristjansson, Sean D.; Bucholz, Kathleen K.
2014-01-01
Background We sought to apply modified labeling theory in a cross-sectional study of alcohol use disorder (AUD) to investigate the mechanisms through which perceived alcohol stigma (PAS) may lead to the persistence of AUD and risk of psychiatric disorder. Methods We conducted structural equation modeling (SEM) including moderated mediation analyses of two waves (W1 and W2) of data from the National Epidemiologic Survey on Alcohol and Related Conditions. We analyzed validated measures of PAS, perceived social support, social network involvement, and psychiatric disorders among (n = 3608) adults with two or more DSM-5 AUD symptoms in the first two of the three years between the W1 and W2 survey. Cross-sectional analyses were conducted owing to the assessment of PAS only at W2. Results Per mediation analyses, lower levels of perceived social support explained the association of PAS with past-year AUD and past-year internalizing psychiatric disorder at W2. The size of the mediated relationship was significantly larger for those classified as labeled (i.e., alcoholic) per their prior alcohol treatment or perceived need (n = 938) as compared to unlabeled (n = 2634), confirming a hypothesis of moderated mediation. Unexpectedly, mediation was also present for unlabeled individuals. Conclusions Lower levels of social support may be an important intermediate outcome of alcohol stigma. Longitudinal data are needed to establish the temporal precedence of PAS and its hypothesized intermediate and distal outcomes. Research is needed to evaluate direct measures of labeling that could replace proxy measures (e.g., prior treatment status) commonly employed in studies of the stigma of psychiatric disorders. PMID:24071569
A Preliminary ZEUS Lightning Location Error Analysis Using a Modified Retrieval Theory
NASA Technical Reports Server (NTRS)
Elander, Valjean; Koshak, William; Phanord, Dieudonne
2004-01-01
The ZEUS long-range VLF arrival time difference lightning detection network now covers both Europe and Africa, and there are plans for further expansion into the western hemisphere. In order to fully optimize and assess ZEUS lightning location retrieval errors and to determine the best placement of future receivers expected to be added to the network, a software package is being developed jointly between the NASA Marshall Space Flight Center (MSFC) and the University of Nevada Las Vegas (UNLV). The software package, called the ZEUS Error Analysis for Lightning (ZEAL), will be used to obtain global scale lightning location retrieval error maps using both a Monte Carlo approach and chi-squared curvature matrix theory. At the core of ZEAL will be an implementation of an Iterative Oblate (IO) lightning location retrieval method recently developed at MSFC. The IO method will be appropriately modified to account for variable wave propagation speed, and the new retrieval results will be compared with the current ZEUS retrieval algorithm to assess potential improvements. In this preliminary ZEAL work effort, we defined 5000 source locations evenly distributed across the Earth. We then used the existing (as well as potential future ZEUS sites) to simulate arrival time data between source and ZEUS site. A total of 100 sources were considered at each of the 5000 locations, and timing errors were selected from a normal distribution having a mean of 0 seconds and a standard deviation of 20 microseconds. This simulated "noisy" dataset was analyzed using the IO algorithm to estimate source locations. The exact locations were compared with the retrieved locations, and the results are summarized via several color-coded "error maps."
NASA Astrophysics Data System (ADS)
Akbarzadeh Khorshidi, Majid; Shariati, Mahmoud
2016-04-01
This paper presents a new investigation for propagation of stress wave in a nanobeam based on modified couple stress theory. Using Euler-Bernoulli beam theory, Timoshenko beam theory, and Reddy beam theory, the effect of shear deformation is investigated. This nonclassical model contains a material length scale parameter to capture the size effect and the Poisson effect is incorporated in the current model. Governing equations of motion are obtained by Hamilton's principle and solved explicitly. This solution leads to obtain two phase velocities for shear deformable beams in different directions. Effects of shear deformation, material length scale parameter, and Poisson's ratio on the behavior of these phase velocities are investigated and discussed. The results also show a dual behavior for phase velocities against Poisson's ratio.
NASA Astrophysics Data System (ADS)
Poletto Rodrigues, Bruno; Deubener, Joachim; Wondraczek, Lothar
2016-05-01
Introducing an interaction parameter γ, we implement modifier interaction and the mixed-alkali effect into bond constraint theory, and apply this extension for simplistic property prediction on ternary phosphate glasses. The severity of the mixed alkali effect results from the interplay of two simultaneous contributions: Bond constraints on the modifier species soften or stiffen with decreasing or increasing γ, respectively. When the modifier size is not too dissimilar the decrease in γ reflects that the alkali ions can easily migrate between different sites, forcing the network to continuously re-accommodate for any subsequent distortions. With increasing size difference, migration becomes increasingly difficult without considerable network deformation. This holds even for smaller ions, where the sluggish dynamics of the larger constituent result in blocking of the fast ion movement, leading to the subsequent increase in γ. Beyond a certain size difference in the modifier pair, a value of γ exceeding unity may indicate the presence of steric hindrance due to the large surrounding modifiers impeding the phosphate network to re-accommodate deformation.
Modified Brans-Dicke theory with space-time anisotropic parameters
Moon, Taeyoon; Oh, Phillial E-mail: ploh@skku.edu
2014-03-01
We consider the ADM formalism of the Brans-Dicke theory and propose a space-time anisotropic extension of the theory by introducing five free parameters. We find that the resulting theory reveals many interesting aspects which are not present in the original BD theory. We first discuss the ghost instability and strong coupling problems which are present in the gravity theory without the full diffeomorphism symmetry and show that they can be avoided in a region of the parameter space. We also perform the post-Newtonian approximation and show that the constraint of the Brans-Dicke parameter ω{sub BD} being large to be consistent with the solar system observations could be evaded in the extended theory. We also discuss that accelerating Universe can be achieved without the need of the potential for the Brans-Dicke scalar.
A Modified Hansen's Theory as Applied to the Motion of Artificial Satellites
NASA Technical Reports Server (NTRS)
Musen, Peter
1960-01-01
This report presents a theory of oblateness perturbations of the orbits of artificial satellites based on Hansen's theory, with modification for adaptation to fast machine computation. The theory permits the easy inclusion of any gravitational terms and is suitable for the deduction of geo-physical and geodetic data from orbit observations on artificial satellites. The computations can be carried out to any desired order compatible with the accuracy of the geodetic parameters.
Dickman, D; Prieto, P
1987-10-01
A case is presented that shows the usefulness of integrating systems theory and attachment theory in the formulation and treatment of a clinical problem. The 5 year old son of East Indian immigrants presented with persistent psychogenic vomiting associated with pathological family attachments. It was evident that the precarious family equilibrium was stabilized by the child's psychogenic vomiting. The therapeutic team suggested to the family that their problems might be more satisfactorily resolved if the mother and child maintained their link by two-way radio. Three weeks later the vomiting had ceased, the child no longer felt that he needed the radio and both parents had established new patterns of relating to their child, whose attendance and peer socialization at school showed marked improvement. To some extent the rapid resolution of the problems was facilitated by the cultural strengths of the family. PMID:3676993
ERIC Educational Resources Information Center
Meng, Chan Ling; Othman, Jamilah; D'Silva, Jeffrey Lawrence; Omar, Zoharah
2014-01-01
This conceptual paper studies the application of the Theory of Planned Behavior (TBP) in academic dishonesty with the mediating variable of ethical ideologies. The study reviews literature on the Theory of Planned Behavior and past studies pertaining to academic dishonesty. The paper analyses the relationship of the variables of TPB on academic…
ERIC Educational Resources Information Center
Zeedick, Danielle Marie
2010-01-01
During the past several decades, the field of instructional design theory has experienced changes in what is mostly applied to traditional, on-ground education. While instructional design theory has been (and still is being) discussed, constructed, and deconstructed, there has been no agreement among prominent instructional design theory…
Abbasi, Mohammad; Afkhami, Seyed E
2014-12-01
The resonant frequency and sensitivity of an atomic force microscope (AFM) with an assembled cantilever probe (ACP) is analyzed utilizing strain gradient theory, and then the governing equation and boundary conditions are derived by a combination of the basic equations of strain gradient theory and Hamilton's principle. The resonant frequency and sensitivity of the proposed AFM microcantilever are then obtained numerically. The proposed ACP includes a horizontal cantilever, two vertical extensions, and two tips located at the free ends of the extensions that form a caliper. As one of the extensions is located between the clamped and free ends of the AFM microcantilever, the cantilever is modeled as two beams. The results of the current model are compared with those evaluated by both modified couple stress and classical beam theories. The difference in results evaluated by the strain gradient theory and those predicted by the couple stress and classical beam theories is significant, especially when the microcantilever thickness is approximately the same as the material length-scale parameters. The results also indicate that at the low values of contact stiffness, scanning in the higher cantilever modes decrease the accuracy of the proposed AFM ACP. PMID:25205330
Misra, Shikha; Mishra, S. K.; Sodha, M. S.
2013-01-15
The authors have modified Chow's theory of secondary electron emission (SEE) to take account of the fact that the path length of a primary electron in a spherical particle varies between zero to the diameter or x{sub m} the penetration depth depending on the distance of the path from the centre of the particle. Further by including this modified expression for SEE efficiency, the charging kinetics of spherical grains in a Maxwellian plasma has been developed; it is based on charge balance over dust particles and number balance of electrons and ionic species. It is seen that this effect is more pronounced for smaller particles and higher plasma temperatures. Desirable experimental work has also been discussed.
Applying Rasch Model and Generalizability Theory to Study Modified-Angoff Cut Scores
ERIC Educational Resources Information Center
Arce, Alvaro J.; Wang, Ze
2012-01-01
The traditional approach to scale modified-Angoff cut scores transfers the raw cuts to an existing raw-to-scale score conversion table. Under the traditional approach, cut scores and conversion table raw scores are not only seen as interchangeable but also as originating from a common scaling process. In this article, we propose an alternative…
Examination of the Korean Modified Checklist of Autism in Toddlers: Item Response Theory
ERIC Educational Resources Information Center
Seung, HyeKyeung; Ji, Juye; Kim, Soo-Jin; Sung, Inkyung; Youn, Young-Ah; Hong, Gyunghun; Lee, Hyeonjin; Lee, Young Hwan; Lee, Hyunsuk; Youm, Hyun Kyung
2015-01-01
The study examined the clinical utility and psychometric properties of the Korean Modified Checklist of Autism in Toddlers (K-M-CHAT)-2. A sample of 2300 parents of 16- to 36-month-old children was recruited across South Korea. A phone interview was utilized to follow up with participants who initially screened positive for autism spectrum…
An Improved Feature Selection Based on Effective Range for Classification
Zhou, Shuang
2014-01-01
Feature selection is a key issue in the domain of machine learning and related fields. The results of feature selection can directly affect the classifier's classification accuracy and generalization performance. Recently, a statistical feature selection method named effective range based gene selection (ERGS) is proposed. However, ERGS only considers the overlapping area (OA) among effective ranges of each class for every feature; it fails to handle the problem of the inclusion relation of effective ranges. In order to overcome this limitation, a novel efficient statistical feature selection approach called improved feature selection based on effective range (IFSER) is proposed in this paper. In IFSER, an including area (IA) is introduced to characterize the inclusion relation of effective ranges. Moreover, the samples' proportion for each feature of every class in both OA and IA is also taken into consideration. Therefore, IFSER outperforms the original ERGS and some other state-of-the-art algorithms. Experiments on several well-known databases are performed to demonstrate the effectiveness of the proposed method. PMID:24688449
Rastgoo, Abbas; Ahmadian, Mohammad Taghi
2013-01-01
Summary The paper presents the effects of fluid flow on the static and dynamic properties of carbon nanotubes that convey a viscous fluid. The mathematical model is based on the modified couple stress theory. The effects of various fluid parameters and boundary conditions on the pull-in voltages are investigated in detail. The applicability of the proposed system as nanovalves or nanosensors in nanoscale fluidic systems is elaborated. The results confirm that the nanoscale system studied in this paper can be properly applied for these purposes. PMID:24367746
NASA Astrophysics Data System (ADS)
Celi, Alessio; Grass, Tobias; Ferris, Andrew J.; Padhi, Bikash; Raventós, David; Simonet, Juliette; Sengstock, Klaus; Lewenstein, Maciej
2016-08-01
Ultracold bosons in a triangular lattice are a promising candidate for observing quantum spin liquid behavior. Here we investigate, for such system, the role of a harmonic trap giving rise to an inhomogeneous density. We construct a modified spin-wave theory for arbitrary filling and predict the breakdown of order for certain values of the lattice anisotropy. These regimes, identified with the spin liquid phases, are found to be quite robust upon changes in the filling factor. This result is backed by an exact diagonalization study on a small lattice.
NASA Astrophysics Data System (ADS)
Valkenburg, Wessel; Hu, Bin
2015-09-01
We present a description for setting initial particle displacements and field values for simulations of arbitrary metric theories of gravity, for perfect and imperfect fluids with arbitrary characteristics. We extend the Zel'dovich Approximation to nontrivial theories of gravity, and show how scale dependence implies curved particle paths, even in the entirely linear regime of perturbations. For a viable choice of Effective Field Theory of Modified Gravity, initial conditions set at high redshifts are affected at the level of up to 5% at Mpc scales, which exemplifies the importance of going beyond Λ-Cold Dark Matter initial conditions for modifications of gravity outside of the quasi-static approximation. In addition, we show initial conditions for a simulation where a scalar modification of gravity is modelled in a Lagrangian particle-like description. Our description paves the way for simulations and mock galaxy catalogs under theories of gravity beyond the standard model, crucial for progress towards precision tests of gravity and cosmology.
Schomber, P.R.
1995-03-01
An ion optics system utilizing a wein filter velocity selector has been modeled and characterized for use as an ion source for an instrument to measure high resolution angular distributions of sputtered neutral atoms. Laser induced fluorescence detection techniques are used to measure ground state and first excited state sputtering angular distributions on a polycrystalline zirconium foil using argon and nitrogen sputter gases. The incident ion beam impact angle has been varied from 15 deg to 75 deg as measured from surface normal and the wein filter velocity selector has been used to select N2+ and N+ ion beams from the nitrogen ion beam. The experimental data gathered are compared to Roosandaal Sanders analytical sputtering theory along with data on xenon and neon. Roosandaal Sanders theory reproduces the near surface normal sputtering behavior but rapidly breaks down as the incident ion beam impact angle moves toward the surface. Modifications to the Roosandaal Sanders equation to introduce adjustable fitting parameters and non-linear least squares fitting of the experimental data to these parameters has been accomplished. The results are discussed relating the fitting parameters to physical constants based in Roosandaal Sanders Theory. Discrepancies in the theory are addressed with extensive discussion on ion surface interaction.
ERIC Educational Resources Information Center
Croff, Julie M.; Clapp, John D.
2015-01-01
Screening, Brief Intervention, and Referral to Treatment (SBIRT) is a model program in the medical context, but it may be missing a large portion of the population with low access to healthcare services. Young adults have the lowest rates of insurance, low healthcare service utilization, and high rates of substance use. Theory driven Screening and…
NASA Technical Reports Server (NTRS)
Yamauchi, G.; Johnson, W.
1984-01-01
A computationally efficient body analysis designed to couple with a comprehensive helicopter analysis is developed in order to calculate the body-induced aerodynamic effects on rotor performance and loads. A modified slender body theory is used as the body model. With the objective of demonstrating the accuracy, efficiency, and application of the method, the analysis at this stage is restricted to axisymmetric bodies at zero angle of attack. By comparing with results from an exact analysis for simple body shapes, it is found that the modified slender body theory provides an accurate potential flow solution for moderately thick bodies, with only a 10%-20% increase in computational effort over that of an isolated rotor analysis. The computational ease of this method provides a means for routine assessment of body-induced effects on a rotor. Results are given for several configurations that typify those being used in the Ames 40- by 80-Foot Wind Tunnel and in the rotor-body aerodynamic interference tests being conducted at Ames. A rotor-hybrid airship configuration is also analyzed.
Theory of the modified two-stream instability in a magnetoplasmadynamic thruster
Hastings, D.E.; Niewood, E. )
1991-04-01
It is shown that for plasma parameters characteristic of those found in magnetoplasmadynamic (MPD) thrusters the modified two-stream instability may exist in the plasma. The critical parameter for triggering this instability is the ratio of the crossfield current to the ion saturation current. Once triggered, this instability greatly increases the plasma resistivity to the flow of the current and heats both ions and electrons. The anomalous momentum-exchange frequency and heating rates are calculated for characteristic MPD thruster parameters. 17 refs.
Long-range density-matrix-functional theory: Application to a modified homogeneous electron gas
Pernal, Katarzyna
2010-05-15
We propose a method that employs functionals of the one-electron reduced density matrix (density matrix) to capture long-range effects of electron correlation. The complementary short-range regime is treated with density functionals. In an effort to find approximations for the long-range density-matrix functional, a modified power functional is applied to the homogeneous electron gas with Coulomb interactions replaced by their corresponding long-range counterparts. For the power {beta}=1/2 and the range-separation parameter {omega}=1/r{sub s}, the functional reproduces the correlation and the kinetic correlation energies with a remarkable accuracy for intermediate and large values of r{sub s}. Analysis of the Euler equation corresponding to this functional reveals correct r{sub s} expansion of the correlation energy in the limit of large r{sub s}. The first expansion coefficient is in very good agreement with that obtained from the modified Wigner-Seitz model.
Lee, M.W.
2002-01-01
The classical Biot-Gassmann theory (BGT) generally overestimates shear-wave velocities of water-saturated sediments. To overcome this problem, a new theory is developed based on BGT and on the velocity ratio as a function of G(1 - ??)n, where ?? is porosity and n and G are constants. Based on laboratory data measured at ultrasonic frequencies, parameters for the new formulation are derived. This new theory is extended to include the effect of differential pressure and consolidation on the velocity ratio by making n a function of differential pressure and the rate of porosity reduction with respect to differential pressure. A scale G is introduced to compensate for discrepancies between measured and predicted velocities, mainly caused by the presence of clay in the matrix. As differential pressure increases and the rate of porosity reduction with respect to differential pressure decreases, the exponent n decreases and elastic velocities increase. Because velocity dispersion is not considered, this new formula is optimum for analyzing velocities measured at ultrasonic frequencies or for sediments having low dispersion characteristics such as clean sandstone with high permeability and lack of grain-scale local flow. The new formula is applied to predict velocities from porosity or from porosity and P-wave velocity and is in good agreement with laboratory and well log data. ?? 2004 Kluwer Academic Publishers. Printed in the Netherlands.
NASA Technical Reports Server (NTRS)
Horai, K.-I.
1981-01-01
A theory of the measurement of the thermal diffusivity of a sample by the modified Angstrom method is developed for the case in which radiative heat loss from the end surface of the sample is not negligible, and applied to measurements performed on lunar samples. Formulas allowing sample thermal diffusivity to be determined from the amplitude decay and phase lag of a temperature wave traveling through the sample are derived for a flat disk sample for which only heat loss from the end surface is important, and a sample of finite diameter and length for which heat loss through the end and side surfaces must be considered. It is noted that in the case of a flat disk, measurements at a single angular frequency of the temperature wave are sufficient, while the sample of finite diameter and length requires measurements at two discrete angular frequencies. Comparison of the values of the thermal diffusivities of two lunar samples of dimensions approximately 1 x 1 x 2 cm derived by the present methods and by the Angstrom theory for a finite bar reveals them to differ by not more than 5%, and indicates that more refined data are required as the measurement theory becomes more complicated.
A Modified Theory of Gravity with Torsion and Its Applications to Cosmology and Particle Physics
NASA Astrophysics Data System (ADS)
Fabbri, Luca; Vignolo, Stefano
2012-10-01
In this paper we consider the most general least-order derivative theory of gravity in which not only curvature but also torsion is explicitly present in the Lagrangian, and where all independent fields have their own coupling constant: we will apply this theory to the case of ELKO fields, which is the acronym of the German Eigenspinoren des LadungsKonjugationsOperators designating eigenspinors of the charge conjugation operator, and thus they are a Majorana-like special type of spinors; and to the Dirac fields, the most general type of spinors. We shall see that because torsion has a coupling constant that is still undetermined, the ELKO and Dirac field equations are endowed with self-interactions whose coupling constant is undetermined: we discuss different applications according to the value of the coupling constants and the different properties that consequently follow. We highlight that in this approach, the ELKO and Dirac field's self-interactions depend on the coupling constant as a parameter that may even make these non-linearities manifest at subatomic scales.
Benchmark of a modified iterated perturbation theory approach on the fcc lattice at strong coupling
NASA Astrophysics Data System (ADS)
Arsenault, Louis-François; Sémon, Patrick; Tremblay, A.-M. S.
2012-08-01
The dynamical mean-field theory approach to the Hubbard model requires a method to solve the problem of a quantum impurity in a bath of noninteracting electrons. Iterated perturbation theory (IPT) has proven its effectiveness as a solver in many cases of interest. Based on general principles and on comparisons with an essentially exact continuous-time quantum Monte Carlo (CTQMC) solver, here we show that the standard implementation of IPT fails away from half-filling when the interaction strength is much larger than the bandwidth. We propose a slight modification to the IPT algorithm that replaces one of the equations by the requirement that double occupancy calculated with IPT gives the correct value. We call this method IPT-D. We recover the Fermi liquid ground state away from half-filling. The Fermi liquid parameters, density of states, chemical potential, energy, and specific heat on the fcc lattice are calculated with both IPT-D and CTQMC as benchmark examples. We also calculated the resistivity and the optical conductivity within IPT-D. Particle-hole asymmetry persists even at coupling twice the bandwidth. A generalization to the multiorbital case is suggested. Several algorithms that speed up the calculations are described in appendixes.
Demján, Tamás; Vörös, Márton; Palummo, Maurizia; Gali, Adam
2014-08-14
Diamondoids are small diamond nanoparticles (NPs) that are built up from diamond cages. Unlike usual semiconductor NPs, their atomic structure is exactly known, thus they are ideal test-beds for benchmarking quantum chemical calculations. Their usage in spintronics and bioimaging applications requires a detailed knowledge of their electronic structure and optical properties. In this paper, we apply density functional theory (DFT) based methods to understand the electronic and optical properties of a few selected pure and modified diamondoids for which accurate experimental data exist. In particular, we use many-body perturbation theory methods, in the G0W0 and G0W0+BSE approximations, and time-dependent DFT in the adiabatic local density approximation. We find large quasiparticle gap corrections that can exceed thrice the DFT gap. The electron-hole binding energy can be as large as 4 eV but it is considerably smaller than the GW corrections and thus G0W0+BSE optical gaps are about 50% larger than the Kohn-Sham (KS) DFT gaps. We find significant differences between KS time-dependent DFT and GW+BSE optical spectra on the selected diamondoids. The calculated G0W0 quasiparticle levels agree well with the corresponding experimental vertical ionization energies. We show that nuclei dynamics in the ionization process can be significant and its contribution may reach about 0.5 eV in the adiabatic ionization energies. PMID:25134572
NASA Astrophysics Data System (ADS)
Wu, Shuang-Qing
2009-08-01
The aim of this paper is to investigate the separability of a spin-1/2 spinor field in a five-dimensional rotating, charged black hole constructed by Cvetič and Youm in string theory, in the case when three U(1) charges are set equal. This black hole solution represents a natural generalization of the famous four-dimensional Kerr-Newman solution to five dimensions with the inclusion of a Chern-Simons term to the Maxwell equation. It is shown that the usual Dirac equation cannot be separated by variables in this general spacetime with two independent angular momenta. However if one supplements an additional counterterm into the usual Dirac operator, then the modified Dirac equation for the spin-1/2 spinor particles is separable in this rotating, charged Einstein-Maxwell-Chern-Simons black hole background geometry. A first-order symmetry operator that commutes with the modified Dirac operator has exactly the same form as that previously found in the uncharged Myers-Perry black hole case. It is expressed in terms of a rank-three totally antisymmetric tensor and its covariant derivative. This tensor obeys a generalized Killing-Yano equation and its square is a second-order symmetric Stäckel-Killing tensor admitted by the five-dimensional rotating, charged black hole spacetime.
Wu Shuangqing
2009-08-15
The aim of this paper is to investigate the separability of a spin-1/2 spinor field in a five-dimensional rotating, charged black hole constructed by Cvetic and Youm in string theory, in the case when three U(1) charges are set equal. This black hole solution represents a natural generalization of the famous four-dimensional Kerr-Newman solution to five dimensions with the inclusion of a Chern-Simons term to the Maxwell equation. It is shown that the usual Dirac equation cannot be separated by variables in this general spacetime with two independent angular momenta. However if one supplements an additional counterterm into the usual Dirac operator, then the modified Dirac equation for the spin-1/2 spinor particles is separable in this rotating, charged Einstein-Maxwell-Chern-Simons black hole background geometry. A first-order symmetry operator that commutes with the modified Dirac operator has exactly the same form as that previously found in the uncharged Myers-Perry black hole case. It is expressed in terms of a rank-three totally antisymmetric tensor and its covariant derivative. This tensor obeys a generalized Killing-Yano equation and its square is a second-order symmetric Staeckel-Killing tensor admitted by the five-dimensional rotating, charged black hole spacetime.
Effective-range signatures in quasi-1D matter waves: sound velocity and solitons
NASA Astrophysics Data System (ADS)
Sgarlata, F.; Mazzarella, G.; Salasnich, L.
2015-06-01
We investigate ultracold and dilute bosonic atoms under strong transverse harmonic confinement using a 1D modified Gross-Pitaevskii equation (1D MGPE), which accounts for the energy dependence of the two-body scattering amplitude within an effective-range expansion. We study sound waves and solitons of the quasi-1D system, comparing the 1D MGPE results with the 1D GPE ones. We find that when the finite-size nature of the interaction is taken into account, the speed of sound and the density profiles of both dark and bright solitons show relevant quantitative changes with respect to predictions given by the standard 1D GPE.
O'Callaghan, Clare; Hiscock, Richard
2007-01-01
Following an investigation into oncologic patients' experiences of the helpfulness of music therapy (O'Callaghan & McDermott, 2004), it was considered that examining relationships between specific patient characteristics and their responses could yield further interesting understandings. "Interpretative subgroup analysis" is introduced, which adapts principles of subgroup analysis in quantitative research to textual data analysis. Anonymous written responses from 128 oncologic patients were analyzed to compare responses from (a) those that had one music therapy session with those who had more than one session, (b) males and females, and (c) middle and older aged respondents. The number of music therapy sessions had scant effect on reported music therapy experiences, and males were much more likely to return questionnaires but much less likely to participate. Unlike some females, males always described positive affective responses when experiencing both sad and positive memories. Variations in the middle and older aged subgroups were evident in type of affective response, and emphases in descriptions of memories and music therapy's effect. Implications of these findings for music therapy practice are considered. Interpretive subgroup analysis is recommended for extending understanding of subjective within group experiences in music therapy research incorporating a grounded theory approach and large enough samples. PMID:17645388
An Ontological Model of Behaviour Theory to Generate Personalized Action Plans to Modify Behaviours.
Baig, Wasif; Abidi, Samina; Abidi, Syed Sibte Raza
2016-01-01
Behavior change approaches aim to assist patients in achieving self-efficacy in managing their condition. Social cognitive theory (SCT) stipulates self-efficacy as a central element to behavior change and provides constructs to achieve self-efficacy guided by person-specific action plans. In our work, to administer behaviour change in patient with chronic conditions, our approach entails the computerization of SCT-based self-efficacy constructs in order to generate personalized action plans that are suitable to an individual's current care scenario. We have taken a knowledge management approach, whereby we have computerized the SCT-based self-efficacy constructs in terms of a high-level SCT knowledge model that can be operationalized to generate personalized behaviour change action plans. We have collected and computerized behavior change content targeting healthy living and physical activity. Semantic web technologies have been used to develop the SCT knowledge model, represented in terms of an ontology and SWRL rules. The ontological SCT model can inferred to generate personalized self-management action plans for a given patient profile. We present formative evaluation of the clinical correctness and relevance of the generated personalized action plans for a range of test patient profiles. PMID:27577412
Moment of inertia of neutron star crust in alternative and modified theories of gravity
NASA Astrophysics Data System (ADS)
Staykov, Kalin V.; Ekşi, K. Yavuz; Yazadjiev, Stoytcho S.; Türkoǧlu, M. Metehan; Arapoǧlu, A. Savaş
2016-07-01
The glitch activity of young pulsars arises from the exchange of angular momentum between the crust and the interior of the star. Recently, it was inferred that the moment of inertia of the crust of a neutron star is not sufficient to explain the observed glitches. Such estimates are presumed in Einstein's general relativity in describing the hydrostatic equilibrium of neutron stars. The crust of the neutron star has a spacetime curvature of 14 orders of magnitude larger than that probed in solar system tests. This makes gravity the weakest constrained physics input in the crust-related processes. We calculate the ratio of the crustal to the total moment of inertia of neutron stars in the scalar-tensor theory of gravity and the nonperturbative f (R )=R +a R2 gravity. We find for the former that the crust-to-core ratio of the moment of inertia does not change significantly from what is inferred in general relativity. For the latter, we find that the ratio increases significantly from what is inferred in general relativity in the case of high mass objects. Our results suggest that the glitch activity of pulsars may be used to probe gravity models, although the gravity models explored in this work are not appropriate candidates.
Demján, Tamás; Vörös, Márton; Palummo, Maurizia; Gali, Adam
2014-08-14
Diamondoids are small diamond nanoparticles (NPs) that are built up from diamond cages. Unlike usual semiconductor NPs, their atomic structure is exactly known, thus they are ideal test-beds for benchmarking quantum chemical calculations. Their usage in spintronics and bioimaging applications requires a detailed knowledge of their electronic structure and optical properties. In this paper, we apply density functional theory (DFT) based methods to understand the electronic and optical properties of a few selected pure and modified diamondoids for which accurate experimental data exist. In particular, we use many-body perturbation theory methods, in the G{sub 0}W{sub 0} and G{sub 0}W{sub 0}+BSE approximations, and time-dependent DFT in the adiabatic local density approximation. We find large quasiparticle gap corrections that can exceed thrice the DFT gap. The electron-hole binding energy can be as large as 4 eV but it is considerably smaller than the GW corrections and thus G{sub 0}W{sub 0}+BSE optical gaps are about 50% larger than the Kohn-Sham (KS) DFT gaps. We find significant differences between KS time-dependent DFT and GW+BSE optical spectra on the selected diamondoids. The calculated G{sub 0}W{sub 0} quasiparticle levels agree well with the corresponding experimental vertical ionization energies. We show that nuclei dynamics in the ionization process can be significant and its contribution may reach about 0.5 eV in the adiabatic ionization energies.
Yasuhara, Tomohisa; Sone, Tomomichi; Kohno, Takeyuki; Ogita, Kiyokazu
2015-01-01
A revised core curriculum model for pharmaceutical education, developed on the basis of the principles of outcome-based education, will be introduced in 2015. Inevitably, appropriate assessments of students' academic achievements will be required. Although evaluations of the cognitive domain can be carried out by paper tests, evaluation methods for the attitude domain and problem-solving abilities need to be established. From the viewpoint of quality assurance for graduates, pharmaceutical education reforms have become vital to evaluation as well as learning strategies. To evaluate student academic achievements on problem-solving abilities, authentic assessment is required. Authentic assessment is the evaluation that mimics the context tried in work and life. Specifically, direct evaluation of performances, demonstration or the learners' own work with integrated variety knowledge and skills, is required. To clarify the process of graduate research, we obtained qualitative data through focus group interviews with six teachers and analyzed the data using the modified grounded theory approach. Based on the results, we clarify the performance students should show in graduate research and create a rubric for evaluation of performance in graduate research. PMID:25743905
NASA Astrophysics Data System (ADS)
Ghadiri, Majid; Shafiei, Navvab
2016-04-01
In this study, thermal vibration of rotary functionally graded Timoshenko microbeam has been analyzed based on modified couple stress theory considering temperature change in four types of temperature distribution on thermal environment. Material properties of FG microbeam are supposed to be temperature dependent and vary continuously along the thickness according to the power-law form. The axial forces are also included in the model as the thermal and true spatial variation due to the rotation. Governing equations and boundary conditions have been derived by employing Hamiltonian's principle. The differential quadrature method is employed to solve the governing equations for cantilever and propped cantilever boundary conditions. Validations are done by comparing available literatures and obtained results which indicate accuracy of applied method. Results represent effects of temperature changes, different boundary conditions, nondimensional angular velocity, length scale parameter, different boundary conditions, FG index and beam thickness on fundamental, second and third nondimensional frequencies. Results determine critical values of temperature changes and other essential parameters which can be applicable to design micromachines like micromotor and microturbine.
Chang, I-Chiu; Hsu, Hui-Mei
2012-01-01
Barriers to report incident events using an online information system (IS) may be different from those of a paper-based reporting system. The nationwide online Patient-Safety Reporting System (PSRS) contains a value judgment behind use of the system, similar to the Value of Perceived Consequence (VPC), which is seldom discussed in ISs applications of other disciplines. This study developed a more adequate research framework by integrating the VPC construct into the well-known Unified Theory of Acceptance and Use of Technology (UTAUT) model as a theoretical base to explore the predictors of medical staff's intention to use online PSRS. The results showed that management support was an important factor to influence medical staff's intention of using PSRS. The effects of factors such as performance expectancy, perceived positive, and perceived negative consequence on medical staff's intention of using PSRS were moderated by gender, age, experience, and occupation. The results proved that the modified UTAUT model is significant and useful in predicting medical staff's intention of using the nationwide online PSRS. PMID:22150638
2012-01-01
Background Patients making important medical decisions need to evaluate complex information in the light of their own beliefs, attitudes and priorities. The process can be considered in terms of the theory of planned behaviour. Decision support technologies aim at helping patients making informed treatment choices. Instruments assessing informed choices need to include risk knowledge, attitude (towards therapy) and actual uptake. However, mechanisms by which decision support achieves its goals are poorly understood. Our aim was therefore to develop and validate an instrument modeling the process of multiple sclerosis (MS) patients’ decision making about whether to undergo disease modifying (immuno-)therapies (DMT). Methods We constructed a 30-item patient administered questionnaire to access the elaboration of decisions about DMT in MS according to the theory of planned behaviour. MS-patients’ belief composites regarding immunotherapy were classified according to the domains “attitude”, “subjective social norm” and “control beliefs” and within each domain to either “expectations” or “values” yielding 6 sub-domains. A randomized controlled trial (n = 192) evaluating an evidence based educational intervention tested the instrument’s predictive power regarding intention to use immunotherapy and its sensitivity to the intervention. Results The psychometric properties of the questionnaire were satisfactory (mean item difficulty 62, mean SD 0.9, range 0–3). Responses explain up to 68% of the variability in the intention to use DMT was explained by up to 68% in the total sample. Four weeks after an educational intervention, predictive power was higher in the intervention (IG) compared to the control group (CG) (intention estimate: CG 56% / IG 69%, p = .179; three domains CG 56% / IG 74%, p = .047; six sub-domains CG 64% / IG 78%, p = .073). The IG held more critical beliefs towards immunotherapy (p = .002) and were less
NASA Astrophysics Data System (ADS)
Cid, Antonella; Leon, Genly; Leyva, Yoelsy
2016-02-01
scale factor. Apart from some fine-tuned examples such as the linear, and quadratic potential U(Φ) in the Jordan frame, it is true that ``intermediate accelerated'' solutions are generic late-time attractors in a modified Jordan-Brans-Dicke theory.
NASA Technical Reports Server (NTRS)
Singh, J. J.; Smith, A. S.; Chan, L. Y.; Yue, G. K.
1982-01-01
Thomson's ion nucleation theory was modified to include the effects of curvature dependence of the microscopic surface tension of field dependent, nonlinear, dielectric properties of the liquid; and of sulfuric acid hydrate formation in binary mixtures of water and sulfuric acid vapors. The modified theory leads to a broadening of the ion cluster spectrum, and shifts it towards larger numbers of H2O and H2SO4 molecules. Whether there is more shifting towards larger numbers of H2O or H2SO4 molecules depends on the relative humidity and relative acidity of the mixture. Usually, a broadening of the spectrum is accompanied by a lowering of the mean cluster intensity. For fixed values of relative humidity and relative acidity, a similar broadening pattern is observed when the temperature is lowered. These features of the modified theory illustrate that a trace of sulfuric acid can facilitate the formation of ultrafine, stable, prenucleation ion clusters as well as the growth of the prenucleation ion clusters towards the critical saddle point conditions, even with low values of relative humidity and relative acidity.
NASA Astrophysics Data System (ADS)
Shreeman, Paul K.
The statistical dynamical diffraction theory, which has been initially developed by late Kato remained in obscurity for many years due to intense and difficult mathematical treatment that proved to be quite challenging to implement and apply. With assistance of many authors in past (including Bushuev, Pavlov, Pungeov, and among the others), it became possible to implement this unique x-ray diffraction theory that combines the kinematical (ideally imperfect) and dynamical (the characteristically perfect diffraction) into a single system of equations controlled by two factors determined by long range order and correlation function within the structure. The first stage is completed by the publication (Shreeman and Matyi, J. Appl. Cryst., 43, 550 (2010)) demonstrating the functionality of this theory with new modifications hence called modified statistical dynamical diffraction theory (mSDDT). The foundation of the theory is also incorporated into this dissertation, and the next stage of testing the model against several ion-implanted SiGe materials has been published: (Shreeman and Matyi, physica status solidi (a)208(11), 2533-2538, 2011). The dissertation with all the previous results summarized, dives into comprehensive analysis of HRXRD analyses complete with several different types of reflections (symmetrical, asymmetrical and skewed geometry). The dynamical results (with almost no defects) are compared with well-known commercial software. The defective materials, to which commercially available modeling software falls short, is then characterized and discussed in depth. The results will exemplify the power of the novel approach in the modified statistical dynamical diffraction theory: Ability to detect and measure defective structures qualitatively and quantitatively. The analysis will be compared alongside with TEM data analysis for verification and confirmation. The application of this theory will accelerate the ability to quickly characterize the relaxed
NEUTRON-PROTON EFFECTIVE RANGE PARAMETERS AND ZERO-ENERGY SHAPE DEPENDENCE.
HACKENBURG, R.W.
2005-06-01
A completely model-independent effective range theory fit to available, unpolarized, np scattering data below 3 MeV determines the zero-energy free proton cross section {sigma}{sub 0} = 20.4287 {+-} 0.0078 b, the singlet apparent effective range r{sub s} = 2.754 {+-} 0.018{sub stat} {+-} 0.056{sub syst} fm, and improves the error slightly on the parahydrogen coherent scattering length, a{sub c} = -3.7406 {+-} 0.0010 fm. The triplet and singlet scattering lengths and the triplet mixed effective range are calculated to be a{sub t} = 5.4114 {+-} 0.0015 fm, a{sub s} = -23.7153 {+-} 0.0043 fm, and {rho}{sub t}(0,-{epsilon}{sub t}) = 1.7468 {+-} 0.0019 fm. The model-independent analysis also determines the zero-energy effective ranges by treating them as separate fit parameters without the constraint from the deuteron binding energy {epsilon}{sub t}. These are determined to be {rho}{sub t}(0,0) = 1.705 {+-} 0.023 fm and {rho}{sub s}(0,0) = 2.665 {+-} 0.056 fm. This determination of {rho}{sub t}(0,0) and {rho}{sub s}(0,0) is most sensitive to the sparse data between about 20 and 600 keV, where the correlation between the determined values of {rho}{sub t}(0,0) and {rho}{sub s}(0,0) is at a minimum. This correlation is responsible for the large systematic error in r{sub s}. More precise data in this range are needed. The present data do not event determine (with confidence) that {rho}{sub t}(0,0) {ne} {rho}{sub t}(0, -{epsilon}{sub t}), referred to here as ''zero-energy shape dependence''. The widely used measurement of {sigma}{sub 0} = 20.491 {+-} 0.014 b from W. Dilg, Phys. Rev. C 11, 103 (1975), is argued to be in error.
Carloni, Sante; Chaichian, Masud; Tureanu, Anca; Nojiri, Shin'ichi; Odintsov, Sergei D.; Oksanen, Markku
2010-09-15
We propose the most general modified first-order Horava-Lifshitz gravity, whose action does not contain time derivatives higher than the second order. The Hamiltonian structure of this theory is studied in all the details in the case of the spatially-flat Friedmann-Robertson-Walker (FRW) space-time, demonstrating many of the features of the general theory. It is shown that, with some plausible assumptions, including the projectability of the lapse function, this model is consistent. As a large class of such theories, the modified Horava-Lifshitz F(R) gravity is introduced. The study of its ultraviolet properties shows that its z=3 version seems to be renormalizable in the same way as the original Horava-Lifshitz proposal. The Hamiltonian analysis of the modified Horava-Lifshitz F(R) gravity shows that it is in general a consistent theory. The F(R) gravity action is also studied in the fixed-gauge form, where the appearance of a scalar field is particularly illustrative. Then the spatially-flat FRW cosmology for this F(R) gravity is investigated. It is shown that a special choice of parameters for this theory leads to the same equations of motion as in the case of traditional F(R) gravity. Nevertheless, the cosmological structure of the modified Horava-Lifshitz F(R) gravity turns out to be much richer than for its traditional counterpart. The emergence of multiple de Sitter solutions indicates the possibility of unification of early-time inflation with late-time acceleration within the same model. Power-law F(R) theories are also investigated in detail. It is analytically shown that they have a quite rich cosmological structure: early-/late-time cosmic acceleration of quintessence, as well as of phantom types. Also it is demonstrated that all the four known types of finite-time future singularities may occur in the power-law Horava-Lifshitz F(R) gravity. Finally, a covariant proposal for (renormalizable) F(R) gravity within the Horava-Lifshitz spirit is presented.
NASA Astrophysics Data System (ADS)
Odintsov, S. D.; Oikonomou, V. K.; Saridakis, Emmanuel N.
2015-12-01
We investigate the realization of two bouncing paradigms, namely of the superbounce and the loop quantum cosmological ekpyrosis, in the framework of various modified gravities. In particular, we focus on the F(R) , F(G) and F(T) gravities, and we reconstruct their specific subclasses which lead to such universe evolutions. These subclasses constitute from power laws, polynomials, or hypergeometric ansatzes, which can be approximated by power laws. The qualitative similarity of the different effective gravities which realize the above two bouncing cosmologies, indicates that a universality might be lying behind the bounce. Finally, performing a linear perturbation analysis, we show that the obtained solutions are conditionally or fully stable.
Novoderezhkin, Vladimir I; Doust, Alexander B; Curutchet, Carles; Scholes, Gregory D; van Grondelle, Rienk
2010-07-21
We model the spectra and excitation dynamics in the phycobiliprotein antenna complex PE545 isolated from the unicellular photosynthetic cryptophyte algae Rhodomonas CS24. The excitonic couplings between the eight bilins are calculated using the CIS/6-31G method. The site energies are extracted from a simultaneous fit of the absorption, circular dichroism, fluorescence, and excitation anisotropy spectra together with the transient absorption kinetics using the modified Redfield approach. Quantitative fit of the data enables us to assign the eight exciton components of the spectra and build up the energy transfer picture including pathways and timescales of energy relaxation, thus allowing a visualization of excitation dynamics within the complex. PMID:20643051
NASA Astrophysics Data System (ADS)
Chubaryan, Edvard; Avagyan, Roland; Harutunyan, Gohar; Kotanjyan, Anna
2016-07-01
Early and late stages of the cosmological expansion are considered on the base of the modified Jordan-Brans-Dicke (JBD) theory, under the assumption φ(y)=αH ^{n} (H is the Hubble constant, n is a parameter equal to four in the inflationary stage and one or two at late stages of the Universe evolution). At late stages, dynamical pattern is obtained with uniformly accelerated expansion for different values of σ (σ is the coupling constant between the gravitational and scalar fields). It is remarkable that for the limiting allowed value of α=9/(2σ) and for large σ, this variant of the theory is equivalent to the de Sitter model in the framework of the Einstein theory in the presence of a scalar field φ(y)=αH ^{2}. Therefore, the quasi exponential growth of the scale factor in the limiting case becomes purely exponential. Note that in the previously considered models the behavior of α was a power law. We also consider the inflationary regime with φ(y)=αH ^{4}. It is shown that in this case a model with slow rolling can be constructed.
NASA Astrophysics Data System (ADS)
Arsenault, Louis-François; Sémon, Patrick; Shastry, B. Sriram; Tremblay, A.-M. S.
2012-02-01
The Dynamical Mean-Field theory(DMFT) approach to the Hubbard model requires a method to solve the problem of a quantum impurity in a bath of non-interacting electrons. Iterated Perturbation Theory(IPT)[1] has proven its effectiveness as a solver in many cases of interest. Based on general principles and on comparisons with an essentially exact Continuous-Time Quantum Monte Carlo (CTQMC)[2], here we show that the standard implementation of IPT fails when the interaction is much larger than the bandwidth. We propose a slight modification to the IPT algorithm by requiring that double occupancy calculated with IPT gives the correct value. We call this method IPT-D. We show how this approximate impurity solver compares with respect to CTQMC. We consider a face centered cubic lattice(FCC) in 3d for different physical properties. We also use IPT-D to study the thermopower using two recently proposed approximations[3]S^* and SKelvin that do not require analytical continuation and show how thermopower is essentially the entropy per particle in the incoherent regime but not in the coherent one.[1]H.Kajueter et al. Phys. Rev. Lett. 77, 131(1996)[2]P. Werner, et al. Phys. Rev. Lett. 97, 076405(2006)[3]B.S. Sriram Shastry Rep. Prog. Phys. 72 016501(2009)
NASA Astrophysics Data System (ADS)
Roy Choudhury, Kaushik; Hughes, S.
2015-08-01
We present a general theory for calculating the spontaneous emission (SE) rate and the photoluminescence intensity of a quantum dot (QD) exciton coupled to an arbitrary structured photonic reservoir and a bath of acoustic phonons. We describe a polaron master equation (ME) approach which includes phonon interaction nonperturbatively and assume a weak coupling with the photon reservoir which is valid in the Purcell coupling regime. As examples of structured photonic reservoirs, we choose the cases of a Lorentzian cavity and a slow-light coupled-cavity waveguide. In analogy with a simple atom, the SE rate of a QD is expected to be proportional to the local density of photon states (LDOS) of the structured reservoir at the resonant frequency of a QD exciton. However, using a polaron ME theory, we show how the phonon-dressed SE rate of a QD is determined by a broad bandwidth of the photonic LDOS, in violation of the well known Fermi's golden rule. This broadband frequency dependence results in rich spontaneous emission enhancement and suppression, manifesting in significant changes in the Purcell factor and photoluminescence intensity as a function of frequency.
Kellar, Joshua A.; Lin, Jui-Ching; Kim, Jun-Hyun; Yoder, Nathan L.; Bevan, Kirk H.; Stokes, Grace Y.; Geiger, Franz M.; Nguyen, SonBinh T.; Bedzyk, Michael J.; Hersam, Mark C.
2009-03-24
Highly conjugated molecules bound to silicon are promising candidates for organosilicon electronic devices and sensors. In this study, 1-bromo-4-ethynylbenzene was synthesized and reacted with a hydrogen-passivated Si(111) surface via ultraviolet irradiation. Through an array of characterization and modeling tools, the binding configuration and morphology of the reacted molecule were thoroughly analyzed. Atomic force microscopy confirmed an atomically flat surface morphology following reaction, while X-ray photoelectron spectroscopy verified reaction to the surface via the terminal alkyne moiety. In addition, synchrotron X-ray characterization, including X-ray reflectivity, X-ray fluorescence, and X-ray standing wave measurements, enabled sub-angstrom determination of the position of the bromine atom with respect to the silicon lattice. This structural characterization was quantitatively compared with density functional theory (DFT) calculations, thus enabling the {pi}-conjugation of the terminal carbon atoms to be deduced. The X-ray and DFT results were additionally corroborated with the vibrational spectrum of the organic adlayer, which was measured with sum frequency generation. Overall, these results illustrate that the terminal carbon atoms in 1-bromo-4-ethynylbenzene adlayers on Si(111) retain {pi}-conjugation, thus revealing alkyne molecules as promising candidates for organosilicon electronics and sensing.
Lyubimova, Olga; Stoyanov, Stanislav R; Gusarov, Sergey; Kovalenko, Andriy
2015-06-30
The X-ray crystal structure-based models of Iα cellulose nanocrystals (CNC), both pristine and containing surface sulfate groups with negative charge 0-0.34 e/nm(2) produced by sulfuric acid hydrolysis of softwood pulp, feature a highly polarized "crystal-like" charge distribution. We perform sampling using molecular dynamics (MD) of the structural relaxation of neutral pristine and negatively charged sulfated CNC of various lengths in explicit water solvent and then employ the statistical mechanical 3D-RISM-KH molecular theory of solvation to evaluate the solvation structure and thermodynamics of the relaxed CNC in ambient aqueous NaCl solution at a concentration of 0.0-0.25 mol/kg. The MD sampling induces a right-hand twist in CNC and rearranges its initially ordered structure with a macrodipole of high-density charges at the opposite faces into small local spots of alternating charge at each face. This surface charge rearrangement observed for both neutral and charged CNC significantly affects the distribution of ions around CNC in aqueous electrolyte solution. The solvation free energy (SFE) of charged sulfated CNC has a minimum at a particular electrolyte concentration depending on the surface charge density, whereas the SFE of neutral CNC increases linearly with NaCl concentration. The SFE contribution from Na(+) counterions exhibits behavior similar to the NaCl concentration dependence of the whole SFE. An analysis of the 3D maps of Na(+) density distributions shows that these model CNC particles exhibit the behavior of charged nanocolloids in aqueous electrolyte solution: an increase in electrolyte concentration shrinks the electric interfacial layer and weakens the effective repulsion between charged CNC particles. The 3D-RISM-KH method readily treats solvent and electrolyte of a given nature and concentration to predict effective interactions between CNC particles in electrolyte solution. We provide CNC structural models and a modeling procedure for
NASA Astrophysics Data System (ADS)
Jung, Timothy Paul
Commercial supersonic travel has strong business potential; however, in order for the Federal Aviation Administration to lift its ban on supersonic flight overland, designers must reduce aircraft sonic boom strength to an acceptable level. An efficient methodology and associated tools for designing aircraft for minimized sonic booms are presented. The computer-based preliminary design tool, RapidF, based on modified linear theory, enables quick assessment of an aircraft's sonic boom with run times less than 30 seconds on a desktop computer. A unique feature of RapidF is that it tracks where on the aircraft each segment of the of the sonic boom came from, enabling precise modifications, speeding the design process. Sonic booms from RapidF are compared to flight test data, showing that it is capability of predicting a sonic boom duration, overpressure, and interior shock locations. After the preliminary design is complete, scaled flight tests should be conducted to validate the low boom design. When conducting such tests, it is insufficient to just scale the length; thus, equations to scale the weight and propagation distance are derived. Using RapidF, a conceptual supersonic business jet design is presented that uses F-function lobe balancing to create a frozen sonic boom using lifting surfaces. The leading shock is reduced from 1.4 to 0.83 psf, and the trailing shock from 1.2 to 0.87 psf, 41% and 28% reductions respectfully. By changing the incidence angle of the surfaces, different sonic boom shapes can be created, and allowing the lobes to be re-balanced for new flight conditions. Computational fluid dynamics is conducted to validate the sonic boom predictions. Off-design analysis is presented that varies weight, altitude, Mach number, and propagation angle, demonstrating that lobe-balance is robust. Finally, the Perceived Level of Loudness metric is analyzed, resulting in a modified design that incorporates other boom minimization techniques to further reduce
NASA Astrophysics Data System (ADS)
Sumi, Tomonari; Maruyama, Yutaka; Mitsutake, Ayori; Koga, Kenichiro
2016-06-01
In the conventional classical density functional theory (DFT) for simple fluids, an ideal gas is usually chosen as the reference system because there is a one-to-one correspondence between the external field and the density distribution function, and the exact intrinsic free-energy functional is available for the ideal gas. In this case, the second-order density functional Taylor series expansion of the excess intrinsic free-energy functional provides the hypernetted-chain (HNC) approximation. Recently, it has been shown that the HNC approximation significantly overestimates the solvation free energy (SFE) for an infinitely dilute Lennard-Jones (LJ) solution, especially when the solute particles are several times larger than the solvent particles [T. Miyata and J. Thapa, Chem. Phys. Lett. 604, 122 (2014)]. In the present study, we propose a reference-modified density functional theory as a systematic approach to improve the SFE functional as well as the pair distribution functions. The second-order density functional Taylor series expansion for the excess part of the intrinsic free-energy functional in which a hard-sphere fluid is introduced as the reference system instead of an ideal gas is applied to the LJ pure and infinitely dilute solution systems and is proved to remarkably improve the drawbacks of the HNC approximation. Furthermore, the third-order density functional expansion approximation in which a factorization approximation is applied to the triplet direct correlation function is examined for the LJ systems. We also show that the third-order contribution can yield further refinements for both the pair distribution function and the excess chemical potential for the pure LJ liquids.
Daveson, Barbara; O'Callaghan, Clare
2011-01-01
Many references to time or temporality are located within music therapy literature, however little research has been completed regarding this phenomenon. Findings from a modified grounded theory study about clients' experiences and descriptions of time within the context of music therapy are presented here. The study was informed by the constructivist-interpretive paradigm and a grounded-descriptive statement finding resulted. A 2-staged research methodology was used, comprising a deductive-inductive content analysis of information from the public domain, followed by data-mining of information from a minimum of 160 clients and analysis of data from at least 43 of these 160 clients. Information regarding memory experiences, the duration of music therapy effects, recall and retrieval, and experiences of time are identified. Implications for practice are emphasized, in particular the following is stressed (a) the importance of time orientation and temporal connectedness in relation to identity development, (b) temporal strategies within music experience to assist integration, recall, and retrieval of information, and (c) the importance of and the elements involved in time modification. New explanations for music therapy phenomena are shared, and areas for research highlighted. Benefits of using time dynamically to aid therapeutic process are proposed, and it is concluded that temporal experience within the context of music therapy is important in relation to both practice and research. PMID:21866712
McNulty, Cliodna A M; Hogan, Angela H; Ricketts, Ellie J; Wallace, Louise; Oliver, Isabel; Campbell, Rona; Kalwij, Sebastian; O'Connell, Elaine; Charlett, Andre
2014-01-01
Objective To determine if a structured complex intervention increases opportunistic chlamydia screening testing of patients aged 15–24 years attending English general practitioner (GP) practices. Methods A prospective, Cluster Randomised Controlled Trial with a modified Zelen design involving 160 practices in South West England in 2010. The intervention was based on the Theory of Planned Behaviour (TPB). It comprised of practice-based education with up to two additional contacts to increase the importance of screening to GP staff and their confidence to offer tests through skill development (including videos). Practical resources (targets, posters, invitation cards, computer reminders, newsletters including feedback) aimed to actively influence social cognitions of staff, increasing their testing intention. Results Data from 76 intervention and 81 control practices were analysed. In intervention practices, chlamydia screening test rates were 2.43/100 15–24-year-olds registered preintervention, 4.34 during intervention and 3.46 postintervention; controls testing rates were 2.61/100 registered patients prior intervention, 3.0 during intervention and 2.82 postintervention. During the intervention period, testing in intervention practices was 1.76 times as great (CI 1.24 to 2.48) as controls; this persisted for 9 months postintervention (1.57 times as great, CI 1.27 to 2.30). Chlamydia infections detected increased in intervention practices from 2.1/1000 registered 15–24-year-olds prior intervention to 2.5 during the intervention compared with 2.0 and 2.3/1000 in controls (Estimated Rate Ratio intervention versus controls 1.4 (CI 1.01 to 1.93). Conclusions This complex intervention doubled chlamydia screening tests in fully engaged practices. The modified Zelen design gave realistic measures of practice full engagement (63%) and efficacy of this educational intervention in general practice; it should be used more often. Trial registration The trial was
Neutron-proton effective range parameters and zero-energy shape dependence
NASA Astrophysics Data System (ADS)
Hackenburg, R. W.
2006-04-01
The low-energy np elastic-scattering parameters, including the zero-energy free-proton cross section σ0, are determined with a substantially improved precision over previous values, using available np-scattering data below 3 MeV. The method includes a careful handling of a correlation between the singlet and triplet effective ranges which does not seem to have been previously treated. This correlation is responsible for a large systematic error in the singlet effective range and spoils a model-independent determination of the zero-energy triplet effective range. It is shown that improved cross section measurements between 20 and 600 keV (laboratory neutron energy) are needed to overcome the degrading effect of this correlation. The values obtained for the zero-energy cross section and the scattering lengths and effective ranges for the singlet and triplet are: σ0=20.4278(78) b, at=5.4112(15) fm, as=-23.7148(43) fm, rt=1.7436(19) fm, rs=2.750(18) fm (systematic error: -0.059 fm). The widely used measurement of the zero-energy free-proton elastic cross section from W. Dilg, Phys. Rev. C 11, 103 (1975), appears to be in error.
Low-energy parameters of neutron-neutron interaction in the effective-range approximation
Babenko, V. A.; Petrov, N. M.
2013-06-15
The effect of the mass difference between the charged and neutral pions on the low-energy parameters of nucleon-nucleon interaction in the {sup 1}S{sub 0} state is studied in the effective-range approximation. On the basis of experimental values of the singlet parameters of neutron-proton scattering and the experimental value of the virtual-state energy for the neutron-neutron systemin the {sup 1}S{sub 0} state, the following values were obtained for the neutron-neutron scattering length and effective range: a{sub nn} = -16.59(117) fm and r{sub nn} = 2.83(11) fm. The calculated values agree well with present-day experimental results.
NASA Astrophysics Data System (ADS)
Pamyatnykh, A. A.
The influence of the modified treatment of subphotospheric convection, as recommended by Deupree (1979) and by Deupree and Varner (1980), on the frequencies of solar five-minute oscillations of degree l = 1 - 100 is studied.
Vermaas, Willem F J.
2014-06-17
Disclosed is a modified photoautotrophic bacterium comprising genes of interest that are modified in terms of their expression and/or coding region sequence, wherein modification of the genes of interest increases production of a desired product in the bacterium relative to the amount of the desired product production in a photoautotrophic bacterium that is not modified with respect to the genes of interest.
Scattering length and effective range for scattering in a plane and in higher dimensions
Verhaar, B.J.; de Goey, L.P.H.; van den Eijnde, J.P.H.W.; Vredenbregt, E.J.D.
1985-09-01
It is shown how the concepts of scattering length and effective range, previously introduced for low-energy scattering from a potential V(r) in a plane, correspond to the well-known parameters in three dimensions. This is done by considering low-energy scattering in a general dimension n> or =2 and subsequently showing that both the n = 2 and n = 3 cases fit naturally in such a generalized treatment. Furthermore, our previous work is extended to long-range potentials, decreasing faster than 1/r/sup n/+1. The method used is based on the properties of a local scattering length a(r) for the potential V(r) cut off at radius r and an equivalent hard-sphere radius a(r,k) for knot =0. Some applications and illustrative examples are given.
Effective-range function for doublet nd scattering from an analysis of modern data
Orlov, Yu. V. Nikitina, L. I.
2006-04-15
The parameters of the generalized effective-range function K(k{sup 2}) having a pole are found by using the results that were obtained by calculating the S-wave phase shift {delta}(E) for doublet nd scattering and the triton binding energy on the basis of Faddeev equations and within the N/D method and which were presented in the literature. The convergence of the expansion of K(k{sup 2}) in powers of momentum is studied. The binding energy of the virtual triton and the residues of the partial-wave scattering amplitudes at the poles corresponding to the bound and virtual states are calculated. Correlations between the binding energies of the bound and virtual states of the triton, on one hand, and the doublet scattering length for nd interaction, on the other hand, are considered. The function K(k{sup 2}) is also calculated within a two-body model featuring various potentials.
Effective-range corrections to three-body recombination for atoms with large scattering length
Hammer, H.-W.; Laehde, Timo A.; Platter, L.
2007-03-15
Few-body systems with large scattering length a have universal properties that do not depend on the details of their interactions at short distances. The rate constant for three-body recombination of bosonic atoms of mass m into a shallow dimer scales as ({Dirac_h}/2{pi})a{sup 4}/m times a log-periodic function of the scattering length. We calculate the leading and subleading corrections to the rate constant, which are due to the effective range of the atoms, and study the correlation between the rate constant and the atom-dimer scattering length. Our results are applied to {sup 4}He atoms as a test case.
A model study on a pair of trapped particles interacting with an arbitrary effective range
NASA Astrophysics Data System (ADS)
Goswami, Partha; Deb, Bimalendu
2016-08-01
We study the effects of the effective range of interaction on the eigenvalues and eigenstates of two particles confined in a three-dimensional (3D) isotropic as well as one- or quasi-one dimensional harmonic (1D) traps. For this we employ model potentials which mimic finite-range s-wave interactions over a wide range of s-wave scattering length a s including the unitarity limits {a}s\\to +/- ∞ . Our results show that when the range is larger than the 3D or 1D harmonic oscillator length scale, the eigenvalues and eigenstates are nearly similar to those of noninteracting two particles in the 3D or 1D trap, respectively. In case of 3D, we find that when the range goes to zero, the results of contact potential as derived by Busch et al (1998 Foundations of Physics 28 549) are reproduced. However, in the case of 1D, such reproducibility does not occur as the range goes to zero. We have calculated the eigenvalues and eigenstates in a 1D harmonic trap taking one dimensional finite-range model potential. We have also calculated the bound state properties of two particles confined in a highly anisotropic quasi-1D trap taking three-dimensional finite-range model potential, and examined whether these quasi-1D results approach towards 1D ones as the aspect ratio η of the radial to axial frequency of the trap increases. We find that if the range is very small compared to the axial size of the trap, then one can reach 1D regime for η ≥slant 10000. However, for a large range, one can almost get 1D results for smaller values of η. This study will be important for the exploration of two-body or many body physics of trapped ultracold atoms interacting with narrow Feshbach resonance for which the effective range can be large.
ERIC Educational Resources Information Center
Kettler, Ryan J.; Elliott, Stephen N.; Beddow, Peter A.
2009-01-01
Federal regulations allow up to 2% of the student population of a state to achieve proficiency for adequate yearly progress by taking an alternate assessment based on modified academic achievement standards (AA-MAS). Such tests are likely to be easier, but as long as a test is considered a valid measure of grade level content, it is allowable as…
Petukhov, B. V.
2012-06-15
The statistical Kolmogorov-Mehl-Johnson theory of solidification is generalized with allowance for the effect of obstacles creating delays for the propagation of new-phase boundaries, as applied to one-dimensional systems. An equation is derived to describe the process kinetics and is used to calculate the time dependence of the fraction of a transformed substance. The modification of the kinetics caused by changes in the obstacle density and the obstacle-induced delay time is studied. The theory can be applied to the extended contacts in large-scale integration circuits, biological macromolecules, and many other systems.
ERIC Educational Resources Information Center
Ziegler, Albert; Fidelman, Marina; Reutlinger, Marold; Vialle, Wilma; Stoeger, Heidrun
2010-01-01
The attainment of exceptional accomplishments requires extremely long periods of time. It has yet to be explained, though, how individuals find the motivation for such protracted learning. Carol Dweck proposed that an incremental theory of an individual's abilities is an important factor in this process since it would account for the optimism…
Liu, Chien-Hao Neher, Joel D. Booske, John H. Behdad, Nader
2014-10-14
Metamaterials and periodic structures operating under high-power excitations are susceptible to breakdown. It was recently demonstrated that a localized breakdown created in a given region of a periodic structure can facilitate breakdown in other regions of the structure where the intensity of the incident electromagnetic fields may not be high enough to cause breakdown under normal circumstances. It was also demonstrated that this phenomenon is due to the generation of vacuum ultraviolet radiation at the location of the initial discharge, which propagates to the neighboring regions (e.g., other unit cells in a periodic structure) and facilitates the generation of a discharge at a lower incident power level. In this paper, we present the results of an experimental study conducted to determine the effective range of this physical phenomenon for periodic structures that operate in air and in pure nitrogen gas at atmospheric pressure levels. It is demonstrated that when breakdown is induced in a periodic structure using a high-power pulse with a frequency of 9.382 GHz, duration of 0.8 μs, and peak power level of 25 kW, this phenomenon is highly likely to happen in radii of approximately 16–17 mm from the location of the initial discharge under these test conditions. The results of this study are significant in designing metamaterials and periodic structures for high-power microwave applications as they suggest that a localized discharge created in such a periodic structure with a periodicity less than 16–17 mm can spread over a large surface and result in a distributed discharge.
NASA Astrophysics Data System (ADS)
Guo, San-Dong
2014-01-01
We investigate the electronic structures and optical dielectric functions of the high temperature phase of Sr2 CrOsO6 with cubic structure by using Tran and Blaha's modified Becke and Johnson exchange potential. In the absence of spin-orbit coupling, the total spin moment is 0μB. When spin-orbit coupling is included, the small total spin moment and an unquenched Os orbital moment appear, and the spin non-conservation gap becomes smaller. The calculated net magnetic moment is smaller than the popular generalized gradient approximation result, and the spin non-conservation gap is larger. The optical dielectric functions with spin-orbit coupling are not very different from the ones without spin-orbit coupling.
Buonocore, Francesco; Arcangeli, Caterina; Gala, Fabrizio; Zollo, Giuseppe; Celino, Massimo
2015-09-01
The interface of biological molecules with inorganic surfaces has been the subject of several recent studies. Experimentally some amino acids are evidenced to play a critical role in the adhesion and selectivity on oxide surfaces; however, detailed information on how the water molecules on the hydrated surface are able to mediate the adsorption is still missing. Accurate total energy ab initio calculations based on dispersion-corrected density functional theory have been performed to investigate the adsorption of selected amino acids on the hydrated ZnO(101̅0) surface, and the results are presented and discussed in this paper. We have also investigated the role played by water in the determination of the most energetically favorable adsorption configurations of the selected amino acids. We have found that for some amino acids the most energetically favorable configurations involve the deprotonation of the molecule if the water screening is not effective. PMID:26262824
Gala, Fabrizio; Zollo, Giuseppe; Celino, Massimo; Arcangeli, Caterina
2015-08-11
The interface of biological molecules with inorganic surfaces has been the subject of several recent studies. Experimentally some amino acids are evidenced to play a critical role in the adhesion and selectivity on oxide surfaces; however, detailed information on how the water molecules on the hydrated surface are able to mediate the adsorption is still missing. Accurate total energy ab initio calculations based on dispersion-corrected density functional theory have been performed to investigate the adsorption of selected amino acids on the hydrated ZnO(101¯0) surface, and the results are presented and discussed in this paper. We have also investigated the role played by water in the determination of the most energetically favorable adsorption configurations of the selected amino acids. As a result, we have found that for some amino acids the most energetically favorable configurations involve the deprotonation of the molecule if the water screening is not effective.
Gala, Fabrizio; Zollo, Giuseppe; Celino, Massimo; Buonocore, Francesco; Arcangeli, Caterina
2015-08-11
The interface of biological molecules with inorganic surfaces has been the subject of several recent studies. Experimentally some amino acids are evidenced to play a critical role in the adhesion and selectivity on oxide surfaces; however, detailed information on how the water molecules on the hydrated surface are able to mediate the adsorption is still missing. Accurate total energy ab initio calculations based on dispersion-corrected density functional theory have been performed to investigate the adsorption of selected amino acids on the hydrated ZnO(101¯0) surface, and the results are presented and discussed in this paper. We have also investigated the rolemore » played by water in the determination of the most energetically favorable adsorption configurations of the selected amino acids. As a result, we have found that for some amino acids the most energetically favorable configurations involve the deprotonation of the molecule if the water screening is not effective.« less
NASA Astrophysics Data System (ADS)
Cui, Xiao-Hong; Duan, Xiang-Mei
2016-03-01
Pt-Cu bimetallic alloys, as a key component in many heterogeneous catalysts, have the potential to be used in a range of industrially important reactions. The stability of platinum-modified Cu(1 1 0) and Cu(1 1 1) surfaces in the absence/presence of CO, NO and O has been investigated based on density-functional theory. We find that Pt alloyed in the second layer of the Cu (1 1 0) surface, rather than in the bulk, is the most favorable configuration. To relieve the strain, platinum tends to stay in the surface layer of close-packed Cu(1 1 1). Adsorbates can affect the stability of Pt-modified surfaces. Upon the adsorption of CO and NO, Pt segregation to the (1 1 0) surface becomes favorable, while on oxygen adsorption, no segregation occurs. Platinum only prefers to segregate on the Cu (1 1 1) surface when it is exposed to carbon monoxide, it tends to locate in the second layer for the other two adsorbates. Combining the position of d-band center, the d-bandwidth, and the separation between the bonding and antibonding states of the adsorbates, we interpret the results and correlate the relationship between the electronic properties of the substrate and the adsorption energy of the adsorbates, which could shed light on the prediction of bimetallic structures with desirable chemical properties.
Cui, Xiao-Hong; Duan, Xiang-Mei
2016-03-01
Pt-Cu bimetallic alloys, as a key component in many heterogeneous catalysts, have the potential to be used in a range of industrially important reactions. The stability of platinum-modified Cu(1 1 0) and Cu(1 1 1) surfaces in the absence/presence of CO, NO and O has been investigated based on density-functional theory. We find that Pt alloyed in the second layer of the Cu (1 1 0) surface, rather than in the bulk, is the most favorable configuration. To relieve the strain, platinum tends to stay in the surface layer of close-packed Cu(1 1 1). Adsorbates can affect the stability of Pt-modified surfaces. Upon the adsorption of CO and NO, Pt segregation to the (1 1 0) surface becomes favorable, while on oxygen adsorption, no segregation occurs. Platinum only prefers to segregate on the Cu (1 1 1) surface when it is exposed to carbon monoxide, it tends to locate in the second layer for the other two adsorbates. Combining the position of d-band center, the d-bandwidth, and the separation between the bonding and antibonding states of the adsorbates, we interpret the results and correlate the relationship between the electronic properties of the substrate and the adsorption energy of the adsorbates, which could shed light on the prediction of bimetallic structures with desirable chemical properties. PMID:26828639
Matter stability in modified teleparallel gravity
NASA Astrophysics Data System (ADS)
Behboodi, A.; Akhshabi, S.; Nozari, K.
2012-11-01
We study the matter stability in modified teleparallel gravity or f(T) theories. We show that there is no Dolgov-Kawasaki instability in these types of modified teleparallel gravity theories. This gives for the f(T) theories a great advantage over their f(R) counterparts because from the stability point of view there isn't any limit on the form of functions that can be chosen.
NASA Astrophysics Data System (ADS)
Blokhintsev, L. D.; Nikitina, L. I.; Orlov, Yu. V.; Savin, D. A.
2014-08-01
In the present work one- and two-channel approaches using the expansion of the effective-range function K( E) in powers of energy E are applied to obtain the asymptotic normalization coefficients (ANCs) and vertex constants (VCs) for the d + α system. The coefficients of the K( E) expansion are found by fitting the d α phase shifts. By analytic continuation of K( E) thus obtained to the corresponding poles the ANCs and VCs for D wave d α resonances with J π = 1+, 2+, 3+ are calculated for the first time. The 1+-resonance and the bound state of 6Li ( J π = 1+) are considered jointly in the two-channel ( S + D) effective-range approach and the ANCs and VCs for the ground 6Li state are found.
Stellar oscillations in modified gravity
NASA Astrophysics Data System (ADS)
Sakstein, Jeremy
2013-12-01
Starting from the equations of modified gravity hydrodynamics, we derive the equations of motion governing linear, adiabatic, radial perturbations of stars in scalar-tensor theories. There are two new features: first, the eigenvalue equation for the period of stellar oscillations is modified such that the eigenfrequencies are always larger than predicted by general relativity. Second, the general relativity condition for stellar instability is altered so that the adiabatic index can fall below 4/3 before unstable modes appear. Stars are more stable in modified gravity theories. Specializing to the case of chameleonlike theories, we investigate these effects numerically using both polytropic Lane-Emden stars and models coming from modified gravity stellar structure simulations. We find that the change in the oscillation period of Cepheid star models can be as large as 30% for order-one matter couplings and the change in the inferred distance using the period-luminosity relation can be up to three times larger than if one had only considered the modified equilibrium structure. We discuss the implications of these results for recent and upcoming astrophysical tests and estimate that previous methods can produce new constraints such that the modifications are screened in regions of Newtonian potential of O(10-8).
Gao Changjun
2010-04-15
The theory of statistical thermodynamics tells us the equipartition law of energy does not hold in the limit of very low temperatures. It is found the Debye model is very successful in explaining the experimental results for most of the solid objects. Motivated by this fact, we modify the entropic force formula which is proposed very recently. Since the Unruh temperature is proportional to the strength of the gravitational field, so the modified entropic force formula is an extension of the Newtonian gravity to the weak field. On the contrary, general relativity extends Newtonian gravity to the strong field case. Corresponding to Debye temperature, there exists a Debye acceleration g{sub D}. It is found the Debye acceleration is g{sub D}=10{sup -15} N kg{sup -1}. This acceleration is very much smaller than the gravitational acceleration 10{sup -4} N kg{sup -1} which is felt by Neptune and the gravitational acceleration 10{sup -10} N kg{sup -1} felt by the Sun. Therefore, the modified entropic force can be very well approximated by the Newtonian gravity in the Solar System and in the Galaxy. With this Debye acceleration, we find the current cosmic speeding up can be explained without invoking any kind of dark energy.
NASA Astrophysics Data System (ADS)
Sandeep; D, P. Rai; A, Shankar; M, P. Ghimire; Anup Pradhan, Sakhya; T, P. Sinha; R, Khenata; S, Bin Omran; R, K. Thapa
2016-06-01
The structural, electronic, and magnetic properties of the Nd-doped Rare earth aluminate, La1‑x Nd x AlO3 (x = 0% to 100%) alloys are studied using the full potential linearized augmented plane wave (FP-LAPW) method within the density functional theory. The effects of the Nd substitution in LaAlO3 are studied using the supercell calculations. The computed electronic structure with the modified Becke–Johnson (mBJ) potential based approximation indicates that the La1‑x Nd x AlO3 alloys may possess half-metallic (HM) behaviors when doped with Nd of a finite density of states at the Fermi level (E F). The direct and indirect band gaps are studied each as a function of x which is the concentration of Nd-doped LaAlO3. The calculated magnetic moments in the La1‑x Nd x AlO3 alloys are found to arise mainly from the Nd-4f state. A probable half-metallic nature is suggested for each of these systems with supportive integral magnetic moments and highly spin-polarized electronic structures in these doped systems at E F. The observed decrease of the band gap with the increase in the concentration of Nd doping in LaAlO3 is a suitable technique for harnessing useful spintronic and magnetic devices. Project supported by the DST-SERB, Dy (Grant No. SERB/3586/2013-14), the UGCBSR, FRPS (Grant No. F.30-52/2014), the UGC (New Delhi, India) Inspire Fellowship DST (India), and the Deanship of Scientific Research at King Saud University (Grant No. RPG-VPP-088). M P Ghimire thanks the Alexander von Humboldt Foundation, Germany for the financial support.
Balakrishna, A.; Rajesh, D.; Babu, S.; Ratnakaram, Y. C.
2015-06-24
Pr{sup 3+} (1.0 mol%) doped different modifier oxide based six lithium-fluoro-borate glasses with chemical composition of 49Li{sub 2}B{sub 4}O{sub 7}-20BaF{sub 2}-10NaF-20MO (where M= Mg, Ca, Cd and Pb), 49Li{sub 2}B{sub 4}O{sub 7}-20BaF{sub 2}-10NaF-10MgO-10CaO and 49Li{sub 2}B{sub 4}O{sub 7}-20BaF{sub 2}-10NaF-10CdO-10PbO were prepared by conventional melt quenching technique. Judd-Ofelt theory has been applied for evaluating the Judd-Ofelt intensity parameters for Pr{sup 3+} ion in these glass compositions and are in turn to used to predict radiative properties such as radiative transition probabilities (A{sub T}), branching ratios (β) and stimulated emission cross-section (σ{sub P}). Stimulated emission cross-section (σ{sub p}) of prominent emission transitions, {sup 3}P{sub 0}→{sup 3}H{sub 4} and {sup 1}D{sub 2}→{sup 3}H{sub 4} of Pr{sup 3+} ion in all lithium-fluoro-borate glasses were calculated. Among all the emission transitions, {sup 3}P{sub 0}→{sup 3}H{sub 4} posseses higher branching ratio and stimulated emission cross-section in Mg-Ca glass, which leads to the best laser excitation at 487 nm wavelength.
Verhaar, B.J.; de Goey, L.P.H.; Vredenbregt, E.J.D.
1985-09-01
The concepts of scattering length a and effective range r/sub e/ previously introduced for low-energy scattering from a potential V(r) in a plane and in higher dimensions are extended to include a 1/r potential (strength parameter ..gamma..). Both a and r/sub e/ have the physical significance of being equal to the radius of an equivalent hard sphere giving rise to the same O(k/sup 0/) and O(k/sup 2/) terms in the expression for the phase shift. The method used is based on the properties of the ''local scattering length'' a(r,..gamma..) for the potential V(r) cut off at radius r and an ''equivalent hard-sphere radius'' a(r,k,..gamma..) for wave number knot =0. It is shown that these quantities have a smooth behavior for ..gamma -->..0 and for dimension n..-->..2.
NASA Astrophysics Data System (ADS)
Efstratiou, P.
2013-09-01
This presentation will be based on my, undergraduate, thesis at Aristotle University of Thessoliniki with the same subject, supervised by Professor Demetrios Papadopoulos. I will first present the general mathematical formulation of the Chern-Simons (CS) modified gravity, which is split in a dynamical and a non-dynamical context, and the different physical theories which suggest this modification. Then proceed by examing the possibility that the CS theory shares solutions with General Relativity in both contexts. In the non-dynamical context I will present a new, undocumented solution as well as all the other possible solutions found to date. I will conclude by arguing that General Relativity and CS Theory share any solutions in the dynamical context.
Cosmological tests of modified gravity.
Koyama, Kazuya
2016-04-01
We review recent progress in the construction of modified gravity models as alternatives to dark energy as well as the development of cosmological tests of gravity. Einstein's theory of general relativity (GR) has been tested accurately within the local universe i.e. the Solar System, but this leaves the possibility open that it is not a good description of gravity at the largest scales in the Universe. This being said, the standard model of cosmology assumes GR on all scales. In 1998, astronomers made the surprising discovery that the expansion of the Universe is accelerating, not slowing down. This late-time acceleration of the Universe has become the most challenging problem in theoretical physics. Within the framework of GR, the acceleration would originate from an unknown dark energy. Alternatively, it could be that there is no dark energy and GR itself is in error on cosmological scales. In this review, we first give an overview of recent developments in modified gravity theories including f(R) gravity, braneworld gravity, Horndeski theory and massive/bigravity theory. We then focus on common properties these models share, such as screening mechanisms they use to evade the stringent Solar System tests. Once armed with a theoretical knowledge of modified gravity models, we move on to discuss how we can test modifications of gravity on cosmological scales. We present tests of gravity using linear cosmological perturbations and review the latest constraints on deviations from the standard [Formula: see text]CDM model. Since screening mechanisms leave distinct signatures in the non-linear structure formation, we also review novel astrophysical tests of gravity using clusters, dwarf galaxies and stars. The last decade has seen a number of new constraints placed on gravity from astrophysical to cosmological scales. Thanks to on-going and future surveys, cosmological tests of gravity will enjoy another, possibly even more, exciting ten years. PMID:27007681
Cosmological tests of modified gravity
NASA Astrophysics Data System (ADS)
Koyama, Kazuya
2016-04-01
We review recent progress in the construction of modified gravity models as alternatives to dark energy as well as the development of cosmological tests of gravity. Einstein’s theory of general relativity (GR) has been tested accurately within the local universe i.e. the Solar System, but this leaves the possibility open that it is not a good description of gravity at the largest scales in the Universe. This being said, the standard model of cosmology assumes GR on all scales. In 1998, astronomers made the surprising discovery that the expansion of the Universe is accelerating, not slowing down. This late-time acceleration of the Universe has become the most challenging problem in theoretical physics. Within the framework of GR, the acceleration would originate from an unknown dark energy. Alternatively, it could be that there is no dark energy and GR itself is in error on cosmological scales. In this review, we first give an overview of recent developments in modified gravity theories including f(R) gravity, braneworld gravity, Horndeski theory and massive/bigravity theory. We then focus on common properties these models share, such as screening mechanisms they use to evade the stringent Solar System tests. Once armed with a theoretical knowledge of modified gravity models, we move on to discuss how we can test modifications of gravity on cosmological scales. We present tests of gravity using linear cosmological perturbations and review the latest constraints on deviations from the standard Λ CDM model. Since screening mechanisms leave distinct signatures in the non-linear structure formation, we also review novel astrophysical tests of gravity using clusters, dwarf galaxies and stars. The last decade has seen a number of new constraints placed on gravity from astrophysical to cosmological scales. Thanks to on-going and future surveys, cosmological tests of gravity will enjoy another, possibly even more, exciting ten years.
Observational tests of modified gravity
Jain, Bhuvnesh; Zhang Pengjie
2008-09-15
Modifications of general relativity provide an alternative explanation to dark energy for the observed acceleration of the Universe. Modified gravity theories have richer observational consequences for large-scale structures than conventional dark energy models, in that different observables are not described by a single growth factor even in the linear regime. We examine the relationships between perturbations in the metric potentials, density and velocity fields, and discuss strategies for measuring them using gravitational lensing, galaxy cluster abundances, galaxy clustering/dynamics, and the integrated Sachs-Wolfe effect. We show how a broad class of gravity theories can be tested by combining these probes. A robust way to interpret observations is by constraining two key functions: the ratio of the two metric potentials, and the ratio of the gravitational 'constant' in the Poisson equation to Newton's constant. We also discuss quasilinear effects that carry signatures of gravity, such as through induced three-point correlations. Clustering of dark energy can mimic features of modified gravity theories and thus confuse the search for distinct signatures of such theories. It can produce pressure perturbations and anisotropic stresses, which break the equality between the two metric potentials even in general relativity. With these two extra degrees of freedom, can a clustered dark energy model mimic modified gravity models in all observational tests? We show with specific examples that observational constraints on both the metric potentials and density perturbations can in principle distinguish modifications of gravity from dark energy models. We compare our result with other recent studies that have slightly different assumptions (and apparently contradictory conclusions)
A fast route to modified gravitational growth
NASA Astrophysics Data System (ADS)
Baker, Tessa; Ferreira, Pedro; Skordis, Constantinos
2014-01-01
The growth rate of the large-scale structure of the Universe has been advocated as the observable par excellence for testing gravity on cosmological scales. By considering linear-order deviations from general relativity, we show that corrections to the growth rate, f, can be expressed as an integral over a "source" term, weighted by a theory-independent "response kernel." This leads to an efficient and accurate "plug-and-play" expression for generating growth rates in alternative gravity theories, bypassing lengthy theory-specific computations. We use this approach to explicitly show that f is sensitive to a degenerate combination of modified expansion and modified clustering effects. Hence the growth rate, when used in isolation, is not a straightforward diagnostic of modified gravity.
String Theory and Gauge Theories
Maldacena, Juan
2009-02-20
We will see how gauge theories, in the limit that the number of colors is large, give string theories. We will discuss some examples of particular gauge theories where the corresponding string theory is known precisely, starting with the case of the maximally supersymmetric theory in four dimensions which corresponds to ten dimensional string theory. We will discuss recent developments in this area.
Black hole thermodynamics in MOdified Gravity (MOG)
NASA Astrophysics Data System (ADS)
Mureika, Jonas R.; Moffat, John W.; Faizal, Mir
2016-06-01
We analyze the thermodynamical properties of black holes in a modified theory of gravity, which was initially proposed to obtain correct dynamics of galaxies and galaxy clusters without dark matter. The thermodynamics of non-rotating and rotating black hole solutions resembles similar solutions in Einstein-Maxwell theory with the electric charge being replaced by a new mass dependent gravitational charge Q =√{ αGN } M. This new mass dependent charge modifies the effective Newtonian constant from GN to G =GN (1 + α), and this in turn critically affects the thermodynamics of the black holes. We also investigate the thermodynamics of regular solutions, and explore the limiting case when no horizons forms. So, it is possible that the modified gravity can lead to the absence of black hole horizons in our universe. Finally, we analyze corrections to the thermodynamics of a non-rotating black hole and obtain the usual logarithmic correction term.
Hamiltonian formulation of the modified Hasegawa-Mima equation
NASA Astrophysics Data System (ADS)
Chandre, C.; Morrison, P. J.; Tassi, E.
2014-02-01
We derive the Hamiltonian structure of the modified Hasegawa-Mima equation from the ion fluid equations applying Dirac's theory of constraints. We discuss the Casimirs obtained from the corresponding Poisson structure.
Toward a Cultural Advancement of Tinto's Theory
ERIC Educational Resources Information Center
Guiffrida, Douglas A.
2006-01-01
Despite the broad appeal of Tinto's (1993) theory, it is not well supported by empirical research, especially when applied to minority students. While prior critiques of the theory indicate the need to modify Tinto's concept of "breaking away" when applying the theory to diverse students, research suggests a need for additional refinements. In…
Wave propagation in modified gravity
NASA Astrophysics Data System (ADS)
Lindroos, Jan Ø.; Llinares, Claudio; Mota, David F.
2016-02-01
We investigate the propagation of scalar waves induced by matter sources in the context of scalar-tensor theories of gravity which include screening mechanisms for the scalar degree of freedom. The usual approach when studying these theories in the nonlinear regime of cosmological perturbations is based on the assumption that scalar waves travel at the speed of light. Within general relativity this approximation is valid and leads to no loss of accuracy in the estimation of observables. We find, however, that mass terms and nonlinearities in the equations of motion lead to propagation and dispersion velocities significantly different from the speed of light. As the group velocity is the one associated with the propagation of signals, a reduction of its value has direct impact on the behavior and dynamics of nonlinear structures within modified gravity theories with screening. For instance, the internal dynamics of galaxies and satellites submerged in large dark matter halos could be affected by the fact that the group velocity is smaller than the speed of light. It is therefore important, within such a framework, to take into account the fact that different parts of a galaxy will see changes in the environment at different times. A full nonstatic analysis may be necessary under those conditions.
Vantage Theory and Linguistic Relativity
ERIC Educational Resources Information Center
Allan, Keith
2010-01-01
Rob MacLaury's Vantage Theory, VT, models the way in which a cognizer constructs, recalls, uses, and modifies a category in terms of point of view or vantage. Alongside of VT, there is place for the kind of semantic specification found in the lexicon. VT2 [Allan, Keith, 2002. "Vantage theory, VT2, and number." "Language Sciences" 24(5-6), 679-703…
Modified Mason number for charged paramagnetic colloidal suspensions
NASA Astrophysics Data System (ADS)
Du, Di; Hilou, Elaa; Biswal, Sibani Lisa
2016-06-01
The dynamics of magnetorheological fluids have typically been described by the Mason number, a governing parameter defined as the ratio between viscous and magnetic forces in the fluid. For most experimental suspensions of magnetic particles, surface forces, such as steric and electrostatic interactions, can significantly influence the dynamics. Here we propose a theory of a modified Mason number that accounts for surface forces and show that this modified Mason number is a function of interparticle distance. We demonstrate that this modified Mason number is accurate in describing the dynamics of a rotating pair of paramagnetic colloids of identical or mismatched sizes in either high or low salt solutions. The modified Mason number is confirmed to be pseudoconstant for particle pairs and particle chains undergoing a stable-metastable transition during rotation. The interparticle distance term can be calculated using theory or can be measured experimentally. This modified Mason number is more applicable to magnetorheological systems where surface forces are not negligible.
ERIC Educational Resources Information Center
Williams, Jeffrey
1994-01-01
Considers the recent flood of anthologies of literary criticism and theory as exemplifications of the confluence of pedagogical concerns, economics of publishing, and other historical factors. Looks specifically at how these anthologies present theory. Cites problems with their formatting theory and proposes alternative ways of organizing theory…
Weller, R.E.
1991-10-01
Much of what used to be called immunotherapy is now included in the term biological response modifiers. Biological response modifiers (BRMs) are defined as those agents or approaches that modify the relationship between the tumor and host by modifying the host's biological response to tumor cells with resultant therapeutic effects.'' Most of the early work with BRMs centered around observations of spontaneous tumor regression and the association of tumor regression with concurrent bacterial infections. The BRM can modify the host response in the following ways: Increase the host's antitumor responses through augmentation and/or restoration of effector mechanisms or mediators of the host's defense or decrease the deleterious component by the host's reaction; Increase the host's defenses by the administration of natural biologics (or the synthetic derivatives thereof) as effectors or mediators of an antitumor response; Augment the host's response to modified tumor cells or vaccines, which might stimulate a greater response by the host or increase tumor-cell sensitivity to an existing response; Decrease the transformation and/or increase differentiation (maturation) of tumor cells; or Increase the ability of the host to tolerate damage by cytotoxic modalities of cancer treatment.
Weller, R.E.
1988-10-01
Much of what used to be called immunotherapy is now included in the term biological response modifiers. Biological response modifiers (BRMs) are those agents or approaches that modify the relationship between the tumor and host by modifying the host's biological response to tumor cells with resultant therapeutic effects. Most of the early work with BRMs centered around observations of spontaneous tumor regression and the association of tumor regression with concurrent bacterial infections. The BRM can modify the host response by increasing the host's antitumor responses through augmentation and/or restoration of effector mechanisms or mediators of the host's defense or decrease the deleterious component by the host's reaction, increasing the host's defenses by the administration of natural biologics (or the synthetic derivatives thereof) as effectors or mediators of an antitumor response, augmenting the host's response to modified tumor cells or vaccines, which might stimulate a greater response by the host or increase tumor-cell sensitivity to an existing response, decreasing the transformation and/or increase differentiation (maturation) of tumor cells, or increasing the ability of the host to tolerate damage by cytotoxic modalities of cancer treatment.
Einstein spaces modeling nonminimal modified gravity
NASA Astrophysics Data System (ADS)
Elizalde, Emilio; Vacaru, Sergiu I.
2015-06-01
Off-diagonal vacuum and nonvacuum configurations in the Einstein gravity can mimic physical effects of modified gravitational theories of f( R, T, R μν T μν ) type. To prove this statement, exact and approximate solutions are constructed in the paper, which encode certain models of covariant Hořava-type gravity with dynamical Lorentz symmetry breaking. The corresponding FLRW cosmological dynamics with possible nonholonomic deformations and the reconstruction procedure of certain actions closely related with the standard ΛCDM universe are studied. Off-diagonal generalizations of de Sitter universes are constructed which are generated through nonlinear gravitational polarization of fundamental physical constants and which model interactions with nonconstant exotic fluids and effective matter. The problem of possible matter instability for such off-diagonal deformations in (modified) gravity theories is briefly discussed.
Nonderivative modified gravity: a classification
Comelli, D.; Nesti, F.; Pilo, L. E-mail: fabrizio.nesti@irb.hr
2014-11-01
We analyze the theories of gravity modified by a generic nonderivative potential built from the metric, under the minimal requirement of unbroken spatial rotations. Using the canonical analysis, we classify the potentials V according to the number of degrees of freedom (DoF) that propagate at the nonperturbative level. We then compare the nonperturbative results with the perturbative DoF propagating around Minkowski and FRW backgrounds. A generic V implies 6 propagating DoF at the non-perturbative level, with a ghost on Minkowski background. There exist potentials which propagate 5 DoF, as already studied in previous works. Here, no V with unbroken rotational invariance admitting 4 DoF is found. Theories with 3 DoF turn out to be strongly coupled on Minkowski background. Finally, potentials with only the 2 DoF of a massive graviton exist. Their effect on cosmology is simply equivalent to a cosmological constant. Potentials with 2 or 5 DoF and explicit time dependence appear to be a further viable possibility.
Theoretical priors on modified growth parametrisations
Song, Yong-Seon; Hollenstein, Lukas; Caldera-Cabral, Gabriela; Koyama, Kazuya E-mail: Lukas.Hollenstein@unige.ch E-mail: Kazuya.Koyama@port.ac.uk
2010-04-01
Next generation surveys will observe the large-scale structure of the Universe with unprecedented accuracy. This will enable us to test the relationships between matter over-densities, the curvature perturbation and the Newtonian potential. Any large-distance modification of gravity or exotic nature of dark energy modifies these relationships as compared to those predicted in the standard smooth dark energy model based on General Relativity. In linear theory of structure growth such modifications are often parameterised by virtue of two functions of space and time that enter the relation of the curvature perturbation to, first, the matter over- density, and second, the Newtonian potential. We investigate the predictions for these functions in Brans-Dicke theory, clustering dark energy models and interacting dark energy models. We find that each theory has a distinct path in the parameter space of modified growth. Understanding these theoretical priors on the parameterisations of modified growth is essential to reveal the nature of cosmic acceleration with the help of upcoming observations of structure formation.
ERIC Educational Resources Information Center
Kaplan, Martin F.
The application of Information Integration Theory (Anderson, 1981), a general model of social judgment, overcomes shortcomings in the evaluation of moral development by offering a clear distinction between moral values and reasoning. To test the applicability of Anderson's theory to moral development research, two experiments were conducted using…
Modified blank ammunition injuries.
Ogunc, Gokhan I; Ozer, M Tahir; Coskun, Kagan; Uzar, Ali Ihsan
2009-12-15
Blank firing weapons are designed only for discharging blank ammunition cartridges. Because they are cost-effective, are easily accessible and can be modified to live firearms plus their unclear legal situation in Turkish Law makes them very popular in Turkey. 2004 through 2008, a total of 1115 modified blank weapons were seized in Turkey. Blank firing weapons are easily modified by owners, making them suitable for discharging live firearm ammunition or modified blank ammunitions. Two common methods are used for modification of blank weapons. After the modification, these weapons can discharge the live ammunition. However, due to compositional durability problems with these types of weapons; the main trend is to use the modified blank ammunitions rather than live firearm ammunition fired from modified blank firing weapons. In this study, two types of modified blank weapons and two types of modified blank cartridges were tested on three different target models. Each of the models' shooting side was coated with 1.3+/-2 mm thickness chrome tanned cowhide as a skin simulant. The first model was only coated with skin simulant. The second model was coated with skin simulant and 100% cotton police shirt. The third model was coated with skin simulant and jean denim. After the literature evaluation four high risky anatomic locations (the neck area; the eyes; the thorax area and inguinal area) were pointed out for the steel and lead projectiles are discharged from the modified blank weapons especially in close range (0-50 cm). The target models were designed for these anatomic locations. For the target models six Transparent Ballistic Candle blocks (TCB) were prepared and divided into two test groups. The first group tests were performed with lead projectiles and second group with steel projectile. The shortest penetration depth (lead projectile: 4.358 cm; steel projectile 8.032 cm) was recorded in the skin simulant and jean denim coated block for both groups. In both groups
Aminoglycoside Modifying Enzymes
Ramirez, Maria S.; Tolmasky, Marcelo E.
2010-01-01
Aminoglycosides have been an essential component of the armamentarium in the treatment of life-threatening infections. Unfortunately, their efficacy has been reduced by the surge and dissemination of resistance. In some cases the levels of resistance reached the point that rendered them virtually useless. Among many known mechanisms of resistance to aminoglycosides, enzymatic modification is the most prevalent in the clinical setting. Aminoglycoside modifying enzymes catalyze the modification at different −OH or −NH2 groups of the 2-deoxystreptamine nucleus or the sugar moieties and can be nucleotidyltranferases, phosphotransferases, or acetyltransferases. The number of aminoglycoside modifying enzymes identified to date as well as the genetic environments where the coding genes are located is impressive and there is virtually no bacteria that is unable to support enzymatic resistance to aminoglycosides. Aside from the development of new aminoglycosides refractory to as many as possible modifying enzymes there are currently two main strategies being pursued to overcome the action of aminoglycoside modifying enzymes. Their successful development would extend the useful life of existing antibiotics that have proven effective in the treatment of infections. These strategies consist of the development of inhibitors of the enzymatic action or of the expression of the modifying enzymes. PMID:20833577
Aerodynamic design via control theory
NASA Technical Reports Server (NTRS)
Jameson, Antony
1988-01-01
The question of how to modify aerodynamic design in order to improve performance is addressed. Representative examples are given to demonstrate the computational feasibility of using control theory for such a purpose. An introduction and historical survey of the subject is included.
Generalized teleparallel theory
NASA Astrophysics Data System (ADS)
Junior, Ednaldo L. B.; Rodrigues, Manuel E.
2016-07-01
We construct a theory in which the gravitational interaction is described only by torsion, but that generalizes the teleparallel theory still keeping the invariance of local Lorentz transformations in one particular case. We show that our theory falls, in a certain limit of a real parameter, under f(bar{R}) gravity or, in another limit of the same real parameter, under modified f( T) gravity; on interpolating between these two theories it still can fall under several other theories. We explicitly show the equivalence with f(bar{R}) gravity for the cases of a Friedmann-Lemaître-Robertson-Walker flat metric for diagonal tetrads, and a metric with spherical symmetry for diagonal and non-diagonal tetrads. We study four applications, one in the reconstruction of the de Sitter universe cosmological model, for obtaining a static spherically symmetric solution of de Sitter type for a perfect fluid, for evolution of the state parameter ω _{DE}, and for the thermodynamics of the apparent horizon.
NASA Astrophysics Data System (ADS)
Blokhintsev, L. D.; Savin, D. A.
2014-03-01
The scattering function (effective-range function) for the two-channel elastic scattering of charged particles is used to analyze dα scattering at low energies. In order to construct this function, use is made of various sets of phase shifts and mixing parameter, both those that were obtained by solving Faddeev equations in the three-body ( n, p, α) model and those that were deduced from available phaseshift analyses. By means of an analytic continuation of the scattering function to the point of the pole corresponding to the bound state of the 6Li nucleus, the values of the vertex constants and asymptotic normalization coefficients are found for the process 6Li → α + d. Possible means for refining these results are discussed.
Sanfilippo, Antonio P.
2005-12-27
Graph theory is a branch of discrete combinatorial mathematics that studies the properties of graphs. The theory was pioneered by the Swiss mathematician Leonhard Euler in the 18th century, commenced its formal development during the second half of the 19th century, and has witnessed substantial growth during the last seventy years, with applications in areas as diverse as engineering, computer science, physics, sociology, chemistry and biology. Graph theory has also had a strong impact in computational linguistics by providing the foundations for the theory of features structures that has emerged as one of the most widely used frameworks for the representation of grammar formalisms.
NASA Astrophysics Data System (ADS)
Solari, Soren; Smith, Andrew; Minnett, Rupert; Hecht-Nielsen, Robert
2008-06-01
Confabulation Theory [Hecht-Nielsen R. Confabulation theory. Springer-Verlag; 2007] is the first comprehensive theory of human and animal cognition. Here, we briefly describe Confabulation Theory and discuss experimental results that suggest the theory is correct. Simply put, Confabulation Theory proposes that thinking is like moving. In humans, the theory postulates that there are roughly 4000 thalamocortical modules, the “muscles of thought”. Each module performs an internal competition ( confabulation) between its symbols, influenced by inputs delivered via learned axonal associations with symbols in other modules. In each module, this competition is controlled, as in an individual muscle, by a single graded (i.e., analog) thought control signal. The final result of this confabulation process is a single active symbol, the expression of which also results in launching of action commands that trigger and control subsequent movements and/or thought processes. Modules are manipulated in groups under coordinated, event-contingent control, in a similar manner to our 700 muscles. Confabulation Theory hypothesizes that the control of thinking is a direct evolutionary outgrowth of the control of movement. Establishing a complete understanding of Confabulation Theory will require launching and sustaining a massive new phalanx of confabulation neuroscience research.
Detecting modified gravity in the stars
NASA Astrophysics Data System (ADS)
Sakstein, Jeremy; Jain, Bhuvnesh; Vikram, Vinu
2014-07-01
Modified theories of gravity have received a renewed interest due to their ability to account for the cosmic acceleration. In order to satisfy the solar system tests of gravity, these theories need to include a screening mechanism that hides the modifications on small scales. One popular and well-studied theory is chameleon gravity. Our own galaxy is necessarily screened, but less dense dwarf galaxies may be unscreened and their constituent stars can exhibit novel features. In particular, unscreened stars are brighter, hotter and more ephemeral than screened stars in our own galaxy. They also pulsate with a shorter period. In this paper, we exploit these new features to constrain chameleon gravity to level three orders of magnitude lower the previous measurements. These constraints are currently the strongest in the literature.
Modified natural neighbor interpolant
NASA Astrophysics Data System (ADS)
Traversoni, Leonardo
1992-11-01
Based on the idea of Natural Neighbor Interpolant presented by Sibson in 1980, this paper shows how combining it with the concept of Covering Spheres, new and more practical algorithms can be made as well as a more complete theory.
The Dynamical Theory of X Ray Diffraction
ERIC Educational Resources Information Center
Balchin, A. A.; Whitehouse, C. R.
1974-01-01
Summarizes the Darwin theory of x-ray diffraction in thin crystals or crystals with a mosaic texture and its modified application to crystals with three-dimensional electrostatic dipoles. Indicates that the dynamical theory is brought into its present relevance by the improvement of single crystal growth techniques. (CC)
Energy Science and Technology Software Center (ESTSC)
2012-08-01
Interatomic force and energy calculation subroutine to be used with the molecular dynamics simulation code LAMMPS (Ref a.). The code evaluated the total energy and atomic forces (energy gradient) according to a cubic spline-based variant (Ref b.) of the Modified Embedded Atom Method (MEAM) with a additional Stillinger-Weber (SW) contribution.
Fleeson, William; Jayawickreme, Eranda
2014-01-01
Personality researchers should modify models of traits to include mechanisms of differential reaction to situations. Whole Trait Theory does so via five main points. First, the descriptive side of traits should be conceptualized as density distributions of states. Second, it is important to provide an explanatory account of the Big 5 traits. Third, adding an explanatory account to the Big 5 creates two parts to traits, an explanatory part and a descriptive part, and these two parts should be recognized as separate entities that are joined into whole traits. Fourth, Whole Trait Theory proposes that the explanatory side of traits consists of social-cognitive mechanisms. Fifth, social-cognitive mechanisms that produce Big-5 states should be identified. PMID:26097268
Duality symmetries in string theory
Nunez, Carmen A.
1999-10-25
The search for a unified theory of quantum gravity and gauge interactions leads naturally to string theory. This field of research has received a revival of interest after the discovery of duality symmetries in recent years. We present a self contained account of some non-perturbative aspects of string theory which have been recently understood. The spectrum and interactions of the five consistent superstring theories in ten dimensions are recollected and the fundamental principles underlying this initial stage in the construction of the theory are briefly reviewed. We next discuss some evidences that these apparently different superstrings are just different aspects of one unique theory. The key to this development is given by the non-perturbative duality symmetries which have modified and improved our understanding of string dynamics in many ways. In particular, by relating the fundamental objects of one theory to solitons of another theory, they have unraveled the presence of extended objects in the theory which stand on an equal footing with strings. We introduce these higher dimensional objects, named D-branes, and discuss applications of D-brane physics.
Conformal transformations in modified teleparallel theories of gravity revisited
NASA Astrophysics Data System (ADS)
Wright, Matthew
2016-05-01
It is well known that one cannot apply a conformal transformation to f (T ) gravity to obtain a minimally coupled scalar field model, and thus no Einstein frame exists for f (T ) gravity. Furthermore nonminimally coupled "teleparallel dark energy models" are not conformally equivalent to f (T ) gravity. However, it can be shown that f (T ) gravity is conformally equivalent to a teleparallel phantom scalar field model with a nonminimal coupling to a boundary term only. In this work, we extend this analysis by considering a recently studied extended class of models, known as f (T ,B ) gravity, where B is a boundary term related to the divergence of a contraction of the torsion tensor. We find that nonminimally coupled "teleparallel dark energy models" are conformally equivalent to either an f (T ,B ) or f (B ) gravity model. Finally conditions on the functional form of f (T ,B ) gravity are derived to allow it to be transformed to particular nonminimally coupled scalar field models.
Shear Strength Prediction By Modified Plasticity Theory For SFRC Beams
Colajanni, Piero; Recupero, Antonino; Spinella, Nino
2008-07-08
the plastic Crack Sliding Model (CSM) is extended for derivation of a physical model for the prediction of ultimate shear strength of SFRC beams, by assuming that the critical cracks is modeled by a yield lines. To this aim, the CSM is improved in order to take into account the strength increases due to the arch effect for deep beam. Then, the effectiveness factors for the concrete under biaxial stress are calibrated for fibrous concrete. The proposed model, able to provide the shear strength and the position of the critical cracks, is validate by a large set of test results collected in literature.
NASA Astrophysics Data System (ADS)
Hoffman, Johan; Jansson, Johan; Johnson, Claes
2016-06-01
We present a new mathematical theory explaining the fluid mechanics of subsonic flight, which is fundamentally different from the existing boundary layer-circulation theory by Prandtl-Kutta-Zhukovsky formed 100 year ago. The new theory is based on our new resolution of d'Alembert's paradox showing that slightly viscous bluff body flow can be viewed as zero-drag/lift potential flow modified by 3d rotational slip separation arising from a specific separation instability of potential flow, into turbulent flow with nonzero drag/lift. For a wing this separation mechanism maintains the large lift of potential flow generated at the leading edge at the price of small drag, resulting in a lift to drag quotient of size 15-20 for a small propeller plane at cruising speed with Reynolds number {Re≈ 107} and a jumbojet at take-off and landing with {Re≈ 108} , which allows flight at affordable power. The new mathematical theory is supported by computed turbulent solutions of the Navier-Stokes equations with a slip boundary condition as a model of observed small skin friction of a turbulent boundary layer always arising for {Re > 106} , in close accordance with experimental observations over the entire range of angle of attacks including stall using a few millions of mesh points for a full wing-body configuration.
Elmer, John W.; Teruya, Alan T.; O'Brien, Dennis W.
1996-01-01
A tomographic technique for measuring the current density distribution in electron beams using electron beam profile data acquired from a modified Faraday cup to create an image of the current density in high and low power beams. The modified Faraday cup includes a narrow slit and is rotated by a stepper motor and can be moved in the x, y and z directions. The beam is swept across the slit perpendicular thereto and controlled by deflection coils, and the slit rotated such that waveforms are taken every few degrees form 0.degree. to 360.degree. and the waveforms are recorded by a digitizing storage oscilloscope. Two-din-tensional and three-dimensional images of the current density distribution in the beam can be reconstructed by computer tomography from this information, providing quantitative information about the beam focus and alignment.
Elmer, J.W.; Teruya, A.T.; O`Brien, D.W.
1996-09-10
A tomographic technique for measuring the current density distribution in electron beams using electron beam profile data acquired from a modified Faraday cup to create an image of the current density in high and low power beams is disclosed. The modified Faraday cup includes a narrow slit and is rotated by a stepper motor and can be moved in the x, y and z directions. The beam is swept across the slit perpendicular thereto and controlled by deflection coils, and the slit rotated such that waveforms are taken every few degrees from 0{degree} to 360{degree} and the waveforms are recorded by a digitizing storage oscilloscope. Two-dimensional and three-dimensional images of the current density distribution in the beam can be reconstructed by computer tomography from this information, providing quantitative information about the beam focus and alignment. 12 figs.
Genetically modified bacteriophages.
Sagona, Antonia P; Grigonyte, Aurelija M; MacDonald, Paul R; Jaramillo, Alfonso
2016-04-18
Phages or bacteriophages, viruses that infect and replicate inside bacteria, are the most abundant microorganisms on earth. The realization that antibiotic resistance poses a substantial risk to the world's health and global economy is revitalizing phage therapy as a potential solution. The increasing ease by which phage genomes can be modified, owing to the influx of new technologies, has led to an expansion of their natural capabilities, and a reduced dependence on phage isolation from environmental sources. This review will discuss the way synthetic biology has accelerated the construction of genetically modified phages and will describe the wide range of their applications. It will further provide insight into the societal and economic benefits that derive from the use of recombinant phages in various sectors, from health to biodetection, biocontrol and the food industry. PMID:26906932
On the asymptotic distribution of block-modified random matrices
NASA Astrophysics Data System (ADS)
Arizmendi, Octavio; Nechita, Ion; Vargas, Carlos
2016-01-01
We study random matrices acting on tensor product spaces which have been transformed by a linear block operation. Using operator-valued free probability theory, under some mild assumptions on the linear map acting on the blocks, we compute the asymptotic eigenvalue distribution of the modified matrices in terms of the initial asymptotic distribution. Moreover, using recent results on operator-valued subordination, we present an algorithm that computes, numerically but in full generality, the limiting eigenvalue distribution of the modified matrices. Our analytical results cover many cases of interest in quantum information theory: we unify some known results and we obtain new distributions and various generalizations.
Effective Einstein cosmological spaces for non-minimal modified gravity
NASA Astrophysics Data System (ADS)
Elizalde, Emilio; Vacaru, Sergiu I.
2015-06-01
Certain off-diagonal vacuum and nonvacuum configurations in Einstein gravity can mimic physical effects of modified gravitational theories of type. We prove this statement by constructing exact and approximate solutions which encode certain models of covariant Hořava type gravity with dynamical Lorentz symmetry breaking. Off-diagonal generalizations of de Sitter and nonholonomic CDM universes are constructed which are generated through nonlinear gravitational polarization of fundamental physical constants and which model interactions with non-constant exotic fluids and effective matter. The problem of possible matter instability for such off-diagonal deformations in (modified) gravity theories is discussed.
Modified energy-momentum conservation laws and vacuum Cherenkov radiation
NASA Astrophysics Data System (ADS)
Carmona, J. M.; Cortés, J. L.; Romeo, B.
2015-12-01
We present a general parametrization for the leading order terms in a momentum power expansion of a non-universal Lorentz-violating, but rotational invariant, kinematics and its implications for two-body decay thresholds. The considered framework includes not only modified dispersion relations for particles, but also modified energy-momentum conservation laws, something which goes beyond effective field theory. As a particular and relevant example, bounds on the departures from special relativistic kinematics from the non-observation of vacuum Cherenkov radiation are discussed and compared with those obtained within the effective field theory scenario.
Regularization methods for Nuclear Lattice Effective Field Theory
NASA Astrophysics Data System (ADS)
Klein, Nico; Lee, Dean; Liu, Weitao; Meißner, Ulf-G.
2015-07-01
We investigate Nuclear Lattice Effective Field Theory for the two-body system for several lattice spacings at lowest order in the pionless as well as in the pionful theory. We discuss issues of regularizations and predictions for the effective range expansion. In the pionless case, a simple Gaussian smearing allows to demonstrate lattice spacing independence over a wide range of lattice spacings. We show that regularization methods known from the continuum formulation are necessary as well as feasible for the pionful approach.
NASA Astrophysics Data System (ADS)
Orlov, Yu. V.; Nikitina, L. I.
2014-04-01
The properties of the first excited state of the 8Be* nucleus (2+) are studied. This state corresponds to the resonance in αα scattering at the energy of E α = E 2 ≈ 3 MeV. Use is made of an expansion of the effective-range function K( k 2). The function K( k 2) is sensitive to the value of E 2. A fit to experimental data on the dependence of the Coulomb-nuclear phase shift δ {2/C} on the energy E α leads to an E 2 value that is smaller than the average value obtained from an analysis of various reactions. The experimental behavior of δ {2/C} ( E α) cannot be described satisfactorily by fixing the average value of E 2. The renormalized nuclear vertex function for the process α + α → 8Be*(2+) and the asymptotic normalization coefficient for the respectiveGamow wave function are calculated by using the set of parameter values found in the present study.
NASA Astrophysics Data System (ADS)
Susskind, Leonard
2013-01-01
After reviewing the original motivation for the formulation of string theory and what we learned from it, I discuss some of the implications of the holographic principle and of string dualities for the question of the building blocks of nature.
[Socio-economic theories of fertility].
Nohara, M
1979-07-01
This paper reviews, critically, major progress in theoretical considerations on fertility from the standpoint of sociology and economics. Malthusian population theory, demographic transition theory, Leibenstein's theory of fertility, and Becker's theory of fertility are discussed. The first 2 theories are mentioned briefly, for demonstrating the theoretical and empirical insufficiencies of the major classic ideas and showing the need for new theoretical orientations. The last 2 theories are traditional efforts to construct an economic theory of fertility which have stimulated sociologists and economists in formulating theories of fertility. The initial plan of this paper was to review not only various efforts for revising Becker's model with respect to its 4 components (income, taste, price, and supply side), but also theoretical arguments and empirical studies on fertility by sociologists. A subsequent issue of this journal will carry discussion of these subjects. (Author's Modified) PMID:12278268
NASA Astrophysics Data System (ADS)
Murdin, P.
2000-11-01
A theory based on the premise that, on the microscopic scale, physical quantities have discrete, rather than a continuous range of, values. The theory was devised in the early part of the twentieth century to account for certain phenomena that could not be explained by classical physics. In 1900, the German physicist, Max Planck (1858-1947), was able precisely to describe the previously unexplaine...
WELLFOCUS PPT: Modifying positive psychotherapy for psychosis.
Riches, Simon; Schrank, Beate; Rashid, Tayyab; Slade, Mike
2016-03-01
Positive psychotherapy (PPT) is an established psychological intervention initially validated with people experiencing symptoms of depression. PPT is a positive psychology intervention, an academic discipline that has developed somewhat separately from psychotherapy and focuses on amplifying well-being rather than ameliorating deficit. The processes targeted in PPT (e.g., strengths, forgiveness, gratitude, savoring) are not emphasized in traditional psychotherapy approaches to psychosis. The goal in modifying PPT is to develop a new clinical approach to helping people experiencing psychosis. An evidence-based theoretical framework was therefore used to modify 14-session standard PPT into a manualized intervention, called WELLFOCUS PPT, which aims to improve well-being for people with psychosis. Informed by a systematic review and qualitative research, modification was undertaken in 4 stages: qualitative study, expert consultation, manualization, and stake-holder review. The resulting WELLFOCUS PPT is a theory-based 11-session manualized group therapy. PMID:25961372
Reassessment of the theory of stimulated Raman scattering
NASA Technical Reports Server (NTRS)
Fralick, G. C.; Deck, R. T.
1985-01-01
A modification of the standard theory of stimulated Raman scattering (SRS) first proposed by Sparks (1974, 1975) is analyzed and shown to incorporate a possibly important physical effect; however, its original formulation is incorrect. The analysis is based on an exact numerical integration of the coupled equations of the modified theory, the results of which are compared with both the conventional theory of SRS and with one set of experimental data. A reformulation of the modified theory is suggested that leads to a gain which is in somewhat better agreement with the data than is the conventional theory.
Generalized Brans-Dicke theories
De Felice, Antonio; Tsujikawa, Shinji E-mail: shinji@rs.kagu.tus.ac.jp
2010-07-01
In Brans-Dicke theory a non-linear self interaction of a scalar field φ allows a possibility of realizing the late-time cosmic acceleration, while recovering the General Relativistic behavior at early cosmological epochs. We extend this to more general modified gravitational theories in which a de Sitter solution for dark energy exists without using a field potential. We derive a condition for the stability of the de Sitter point and study the background cosmological dynamics of such theories. We also restrict the allowed region of model parameters from the demand for the avoidance of ghosts and instabilities. A peculiar evolution of the field propagation speed allows us to distinguish those theories from the ΛCDM model.
A Nonvolume Preserving Plasticity Theory with Applications to Powder Metallurgy
NASA Technical Reports Server (NTRS)
Cassenti, B. N.
1983-01-01
A plasticity theory has been developed to predict the mechanical response of powder metals during hot isostatic pressing. The theory parameters were obtained through an experimental program consisting of hydrostatic pressure tests, uniaxial compression and uniaxial tension tests. A nonlinear finite element code was modified to include the theory and the results of themodified code compared favorably to the results from a verification experiment.
Confidentiality: a modified value.
Emson, H E
1988-01-01
In its original expression as a medical value confidentiality may have been absolute; this concept has become eroded by patient consent, legal actions and change in the climate of public opinion. In particular requirements arising out of legal statutes and common law judgements have greatly modified the confidentiality of the doctor-patient relationship in societies deriving their law from English origins. Despite this, confidentiality remains a value which the physician must strive to preserve. He cannot however do this without considering its effect upon possible innocent third parties. PMID:3392723
Cohen, Idan; Poręba, Elżbieta; Kamieniarz, Kinga; Schneider, Robert
2011-01-01
Covalent modifications of histones can regulate all DNA-dependent processes. In the last few years, it has become more and more evident that histone modifications are key players in the regulation of chromatin states and dynamics as well as in gene expression. Therefore, histone modifications and the enzymatic machineries that set them are crucial regulators that can control cellular proliferation, differentiation, plasticity, and malignancy processes. This review discusses the biology and biochemistry of covalent histone posttranslational modifications (PTMs) and evaluates the dual role of their modifiers in cancer: as oncogenes that can initiate and amplify tumorigenesis or as tumor suppressors. PMID:21941619
Surface modified aerogel monoliths
NASA Technical Reports Server (NTRS)
Leventis, Nicholas (Inventor); Johnston, James C. (Inventor); Kuczmarski, Maria A. (Inventor); Meador, Mary Ann B. (Inventor)
2013-01-01
This invention comprises reinforced aerogel monoliths such as silica aerogels having a polymer coating on its outer geometric surface boundary, and to the method of preparing said aerogel monoliths. The polymer coatings on the aerogel monoliths are derived from polymer precursors selected from the group consisting of isocyanates as a precursor, precursors of epoxies, and precursors of polyimides. The coated aerogel monoliths can be modified further by encapsulating the aerogel with the polymer precursor reinforced with fibers such as carbon or glass fibers to obtain mechanically reinforced composite encapsulated aerogel monoliths.
Effective theories of universal theories
NASA Astrophysics Data System (ADS)
Wells, James D.; Zhang, Zhengkang
2016-01-01
It is well-known but sometimes overlooked that constraints on the oblique parameters (most notably S and T parameters) are generally speaking only applicable to a special class of new physics scenarios known as universal theories. In the effective field theory (EFT) framework, the oblique parameters should not be associated with Wilson coefficients in a particular operator basis, unless restrictions have been imposed on the EFT so that it describes universal theories. We work out these restrictions, and present a detailed EFT analysis of universal theories. We find that at the dimension-6 level, universal theories are completely characterized by 16 parameters. They are conveniently chosen to be: 5 oblique parameters that agree with the commonly-adopted ones, 4 anomalous triple-gauge couplings, 3 rescaling factors for the h 3, hf f , hV V vertices, 3 parameters for hV V vertices absent in the Standard Model, and 1 four-fermion coupling of order y f 2 . All these parameters are defined in an unambiguous and basis-independent way, allowing for consistent constraints on the universal theories parameter space from precision electroweak and Higgs data.
Nonisentropic unsteady three dimensional small disturbance potential theory
NASA Technical Reports Server (NTRS)
Gibbons, M. D.; Williams, M. H.; Whitlow, W., Jr.
1986-01-01
Nonisentropic modifications to the three-dimensional transonic small disturbance (TSD) theory, which allows for more accurate modeling of transonic flow fields, are described. The modified flux equation and entropy corrections are presented; the Engquist-Osher differencing (1980) is added to the solution algorithm in order to eliminate the velocity overshoots upstream of shocks. The modified theory is tested in the XTRAN3S finite difference computer code. Steady flows over a rectangular NACA 0012 wing with an aspect ratio of 12 are calculated and compared to Euler equation solutions; good correlation is observed between the data and the modified TSD theory provides more accurate data, particularly for the lift curve slope. The nonisentropic theory is evaluated on an RAE tailplane model for steady and unsteady flows and the modified theory results agree well with the experimental data.
Kim, Kwanghee; McBride, William H.
2011-01-01
Radiation leaves a fairly characteristic footprint in biological materials, but this is rapidly all but obliterated by the canonical biological responses to the radiation damage. The innate immune recognition systems that sense “danger” through direct radiation damage and through associated collateral damage set in motion a chain of events that, in a tissue compromised by radiation, often unwittingly result in oscillating waves of molecular and cellular responses as tissues attempt to heal. Understanding “nature’s whispers” that inform on these processes will lead to novel forms of intervention targeted more precisely towards modifying them in an appropriate and timely fashion so as to improve the healing process and prevent or mitigate the development of acute and late effects of normal tissue radiation damage, whether it be accidental, as a result of a terrorist incident, or of therapeutic treatment of cancer. Here we attempt to discuss some of the non-free radical scavenging mechanisms that modify radiation responses and comment on where we see them within a conceptual framework of an evolving radiation-induced lesion. PMID:20583981
Modified Gravity and the origin of inertia
NASA Astrophysics Data System (ADS)
Moffat, J. W.; Toth, V. T.
2009-05-01
Modified gravity theory is known to violate Birkhoff's theorem. We explore a key consequence of this violation, the effect of distant matter in the Universe on the motion of test particles. We find that when a particle is accelerated, a force is experienced that is proportional to the particle's mass and acceleration and acts in the direction opposite to that of the acceleration. We identify this force with inertia. At very low accelerations, our inertial law deviates slightly from that of Newton, yielding a testable prediction that may be verified with relatively simple experiments. Our conclusions apply to all gravity theories that reduce to a Yukawa-like force in the weak-field approximation.
NASA Astrophysics Data System (ADS)
Moraru, Gheorghe; Mursa, Condrat
2006-12-01
In this book we present the basic concepts of the theory of elasticity: stress and deformation states (plane and three-dimensional) and generalized Hooke's law. We present a number of problems which have applications in strength analysis. The book includes a synthesis of the theory of elasticity and modern methods of applied mathematics. This book is designed for students, post graduate students and specialists in strength analysis. the book contains a number of appendixes which includes: elements of matrix-calculation, concepts of tensorial calculation, the Fourier transform, the notion of improper integrals,singular and hypersingular integrals, generalized functions, the Dirac Delta function
A modified conjugate gradient solver for very large systems
NASA Astrophysics Data System (ADS)
Barkai, D.; Moriarty, K. J. M.; Rebbi, C.
1985-03-01
A modified conjugate gradient method is derived which requires only one pass through the coefficients and the temporary vectors. The method is applicable to problems which may be complex and non-symmetric. The method is implemented on a vector processor (the CDC CYBER 205) and applied to a high-energy physics lattice gauge theory problem, though the implementation methodology is quite general.
Modified Elliptic Gamma Functions and 6d Superconformal Indices
NASA Astrophysics Data System (ADS)
Spiridonov, Vyacheslav P.
2014-04-01
We construct a modified double elliptic gamma function which is well defined when one of the base parameters lies on the unit circle. A model consisting of 6d hypermultiplets coupled to a gauge field theory living on a 4d defect is proposed whose superconformal index uses the double elliptic gamma function and obeys W( E 7)-group symmetry.
ERIC Educational Resources Information Center
Moorman, Thomas
1992-01-01
Students experience the distinction between observable fact and scientific theory by taking a critical look at how spaghetti can be sucked up into the mouth. A demonstration shows that air is needed to suck up the spaghetti but that the scientific explanation is not as simple. (MDH)
ERIC Educational Resources Information Center
Toso, Robert B.
2000-01-01
Inspired by William Glasser's Reality Therapy ideas, Control Theory (CT) is a disciplinary approach that stresses people's ability to control only their own behavior, based on internal motivations to satisfy five basic needs. At one North Dakota high school, CT-trained teachers are the program's best recruiters. (MLH)
NASA Astrophysics Data System (ADS)
Paschos, E. A.
2005-01-01
The electroweak theory unifies two basic forces of nature: the weak force and electromagnetism. This book is a concise introduction to the structure of the electroweak theory and its applications. It describes the structure and properties of field theories with global and local symmetries, leading to the construction of the standard model. It describes the new particles and processes predicted by the theory, and compares them with experimental results. It also covers neutral currents, the properties of W and Z bosons, the properties of quarks and mesons containing heavy quarks, neutrino oscillations, CP-asymmetries in K, D, and B meson decays, and the search for Higgs particles. Each chapter contains problems, stemming from the long teaching experience of the author, to supplement the text. This will be of great interest to graduate students and researchers in elementary particle physics. Password protected solutions are available to lecturers at www.cambridge.org/9780521860987. Each chapter has an introduction highlighting its contents and giving a historical perspective. Chapters are cross-referenced, interrelating concepts and sections of the book. Contains 49 exercises
Modified Composite Materials Workshop
NASA Technical Reports Server (NTRS)
Dicus, D. L. (Compiler)
1978-01-01
The reduction or elimination of the hazard which results from accidental release of graphite fibers from composite materials was studied at a workshop. At the workshop, groups were organized to consider six topics: epoxy modifications, epoxy replacement, fiber modifications, fiber coatings and new fibers, hybrids, and fiber release testing. Because of the time required to develop a new material and acquire a design data base, most of the workers concluded that a modified composite material would require about four to five years of development and testing before it could be applied to aircraft structures. The hybrid working group considered that some hybrid composites which reduce the risk of accidental fiber release might be put into service over the near term. The fiber release testing working group recommended a coordinated effort to define a suitable laboratory test.
Chemically modified polypyrrole
Inagaki, T.; Skotheim, T.A.; Lee, H.S.; Okamoto, Y.; Samuelson, L.; Tripathy, S.
1988-01-01
Polypyrrole (PPy) films have been systematically modified with electroactive groups in the ..beta..-position to design electrode materials with specific electrochemical and surface active properties. Electrochemical copolymerization of pyrrole and 3-(6-ferrocenyl,6-hydroxyhexyl)pyrrole (P-6-Fc) yields a ferrocene functionalized polypyrrole with a controlled amount to ferrocene functionalization. And also, copolymers of pyrrole and 3-(4-(2,5- dimethoxyphenyl)butyl)pyrrole (P-MP) can be made by electrochemical polymerization and converted to the copolymers containing pH dependent electroactive hydroquinone moieties. Derivatized pyrroles have also been incorporated into Langmuir-Blodgett film structures. The surface pressure-area isotherms of 3-(13-ferrocenyl,13-hydroxytridecy)pyrrole (P-13-Fc) and the mixed monolayer of P-13-Fc and 3-n-hexadecylpyrrole (HDP) are shown. 17 refs., 4 figs.
Fogler, H. Scott; Srinivasan, Keeran R.
1990-01-01
A novel modified clay sorbent and method of treating industrial effluents to remove trace pollutants, such as dioxins, biphenyls, and polyaromatics such as benzo(a)pyrene and pentachlorophenol. The novel clay sorbent has a composite structure in which the interlayer space of an expandable clay, such as smectite, is filled with polyvalent or multivalent inorganic cations which forces weaker surfactant cations to locate on the surface of the clay in such an orientation that the resulting composite is hydrophilic in nature. A specific example is cetylpyridinium-hydroxy aluminum-montmorillonite. In certain embodiments, a non-expanding clay, such as kaolinite, is used and surfactant cations are necessarily located on an external surface of the clay. A specific example is cetylpyridinium-kaolinite.
[The modified Lapidus arthrodesis].
Trnka, H-J; Hofstätter, S
2005-08-01
For the correction of hallux valgus, as one of the most common deformities of the lower limbs, a modified Lapidus arthrodesis is applied at the base of the hallux. After using a lateral tissue technique with medial capsular reefing, a general arthrodesis of the tarsometatarsal 1 joint is carried out. An unstable hallux is the indication for a classic Lapidus arthrodesis. Before determination of the indication, an exact clinical x-ray examination should be made in the dorsoplanar position as well as laterally standing. Complications associated with the Lapidus arthrodesis are postoperative metatarsalgia and pseudoarthrosis. Advantages of this technique are, for example, a high correction potential and better healing, although the surgical technique and post-operative care are more time consuming than for other methods. PMID:16028050
Numerical simulations of Modified Newtonian Dynamics
NASA Astrophysics Data System (ADS)
Candlish, G. N.; Smith, R.; Fellhauer, M.
2016-05-01
The ΛCDM standard cosmological model is strongly supported by multiple lines of evidence, particularly from observations at large scales such as the CMB and large scale structure. There are some indications, however, of problems at smaller scales. An alternative to the CDM approach is to modify the gravitational force, as exemplified by the MOdified Newtonian Dynamics (MOND) idea. While evidence suggests MOND cannot account for dynamics at all scales without dark matter, it has been successful at galactic scales. Due to the complexity of the theory, however, most tests of MOND have extended no further than using a simple scaling relation to determine rotation curves or velocity dispersions. Therefore, to test the concept more thoroughly we require numerical simulations. We discuss the development and testing of a new N-body solver, using two distinct formulations of MOND, that is incorporated into the RAMSES code. The theory of MOND as a modification of Newtonian gravity is briefly summarised. We then show how it is implemented in the code, providing an example of an idealised test case and future applications.
Situational theory of leadership.
Waller, D J; Smith, S R; Warnock, J T
1989-11-01
The situational theory of leadership and the LEAD instruments for determining leadership style are explained, and the application of the situational leadership theory to the process of planning for and implementing organizational change is described. Early studies of leadership style identified two basic leadership styles: the task-oriented autocratic style and the relationship-oriented democratic style. Subsequent research found that most leaders exhibited one of four combinations of task and relationship behaviors. The situational leadership theory holds that the difference between the effectiveness and ineffectiveness of the four leadership styles is the appropriateness of the leader's behavior to the particular situation in which it is used. The task maturity of the individual or group being led must also be accounted for; follower readiness is defined in terms of the capacity to set high but attainable goals, willingness or ability to accept responsibility, and possession of the necessary education or experience for a specific task. A person's leadership style, range, and adaptability can be determined from the LEADSelf and LEADOther questionnaires. By applying the principles of the situational leadership theory and adapting their managerial styles to specific tasks and levels of follower maturity, the authors were successful in implementing 24-hour pharmacokinetic dosing services provided by staff pharmacists with little previous experience in clinical services. The situational leadership model enables a leader to identify a task, set goals, determine the task maturity of the individual or group, select an appropriate leadership style, and modify the style as change occurs. Pharmacy managers can use this model when implementing clinical pharmacy services. PMID:2589352
Theory Survey or Survey Theory?
ERIC Educational Resources Information Center
Dean, Jodi
2010-01-01
Matthew Moore's survey of political theorists in U.S. American colleges and universities is an impressive contribution to political science (Moore 2010). It is the first such survey of political theory as a subfield, the response rate is very high, and the answers to the survey questions provide new information about how political theorists look…
Superbounce and loop quantum cosmology ekpyrosis from modified gravity
NASA Astrophysics Data System (ADS)
Oikonomou, V. K.
2015-09-01
As is known, in modified cosmological theories of gravity many of the cosmologies which could not be generated by standard Einstein gravity, can be consistently described by theories. Using known reconstruction techniques, we investigate which theories can lead to a Hubble parameter describing two types of cosmological bounces, the superbounce model, related to supergravity and non-supersymmetric models of contracting ekpyrosis and also the Loop Quantum Cosmology modified ekpyrotic model. Since our method is an approximate method, we investigate the problem at large and small curvatures. As we evince, both models yield power law reconstructed gravities, with the most interesting new feature being that both lead to accelerating cosmologies, in the large curvature approximation. The mathematical properties of the some Friedmann-Robertson-Walker spacetimes , that describe superbounce-like cosmologies are also pointed out, with regards to the group of curvature collineations.
NASA Technical Reports Server (NTRS)
Johnson, W.
1980-01-01
A comprehensive presentation is made of the engineering analysis methods used in the design, development and evaluation of helicopters. After an introduction covering the fundamentals of helicopter rotors, configuration and operation, rotary wing history, and the analytical notation used in the text, the following topics are discussed: (1) vertical flight, including momentum, blade element and vortex theories, induced power, vertical drag and ground effect; (2) forward flight, including in addition to momentum and vortex theory for this mode such phenomena as rotor flapping and its higher harmonics, tip loss and root cutout, compressibility and pitch-flap coupling; (3) hover and forward flight performance assessment; (4) helicopter rotor design; (5) rotary wing aerodynamics; (6) rotary wing structural dynamics, including flutter, flap-lag dynamics ground resonance and vibration and loads; (7) helicopter aeroelasticity; (8) stability and control (flying qualities); (9) stall; and (10) noise.
Exponentially modified QCD coupling
Cvetic, Gorazd; Valenzuela, Cristian
2008-04-01
We present a specific class of models for an infrared-finite analytic QCD coupling, such that at large spacelike energy scales the coupling differs from the perturbative one by less than any inverse power of the energy scale. This condition is motivated by the Institute for Theoretical and Experimental Physics operator product expansion philosophy. Allowed by the ambiguity in the analytization of the perturbative coupling, the proposed class of couplings has three parameters. In the intermediate energy region, the proposed coupling has low loop-level and renormalization scheme dependence. The present modification of perturbative QCD must be considered as a phenomenological attempt, with the aim of enlarging the applicability range of the theory of the strong interactions at low energies.
Structure parameters in molecular tunneling ionization theory
NASA Astrophysics Data System (ADS)
Wang, Jun-Ping; Li, Wei; Zhao, Song-Feng
2014-04-01
We extracted the accurate structure parameters in molecular tunneling ionization theory (so called MO-ADK theory) for 22 selected linear molecules including some inner orbitals. The molecular wave functions with the correct asymptotic behavior are obtained by solving the time-independent Schrödinger equation with B-spline functions and molecular potentials numerically constructed using the modified Leeuwen-Baerends (LBα) model.
Reiss, H.R.
2012-01-01
A modification of electrodynamics is proposed, motivated by previously unremarked paradoxes that can occur in the standard formulation. It is shown by specific examples that gauge transformations exist that radically alter the nature of a problem, even while maintaining the values of many measurable quantities. In one example, a system with energy conservation is transformed to a system where energy is not conserved. The second example possesses a ponderomotive potential in one gauge, but this important measurable quantity does not appear in the gauge-transformed system. A resolution of the paradoxes comes from noting that the change in total action arising from the interaction term in the Lagrangian density cannot always be neglected, contrary to the usual assumption. The problem arises from the information lost by employing an adiabatic cutoff of the field. This is not necessary. Its replacement by a requirement that the total action should not change with a gauge transformation amounts to a supplementary condition for gauge invariance that can be employed to preserve the physical character of the problem. It is shown that the adiabatic cutoff procedure can also be eliminated in the construction of quantum transition amplitudes, thus retaining consistency between the way in which asymptotic conditions are applied in electrodynamics and in quantum mechanics. The ‘gauge-invariant electrodynamics’ of Schwinger is shown to depend on an ansatz equivalent to the condition found here for maintenance of the ponderomotive potential in a gauge transformation. Among the altered viewpoints required by the modified electrodynamics, in addition to the rejection of the adiabatic cutoff, is the recognition that the electric and magnetic fields do not completely determine a physical problem, and that the electromagnetic potentials supply additional information that is required for completeness of electrodynamics. PMID:23105173
Nominal Modifiers in Mandarin Chinese.
ERIC Educational Resources Information Center
Hou, John Y.
In the surface structure of Chinese nominal modifiers (quantifiers, determiners, adjectives, measure phrase, relative clause, etc.) may occur either before or after a modified noun. In most of the transformational studies of Chinese syntax (e.g. Cheng 1966; Hashimoto 1966; Mei 1972; Tai 1973; Teng 1974), it has been assumed that such NP's have the…
Modifiers and Perceived Stress Scale.
ERIC Educational Resources Information Center
Linn, Margaret W.
1986-01-01
The Modifiers and Perceived Stress Scale measures stressful life events by number and amount of perceived stresses and provides scores for variables such as anticipation of events, responsibility for events, and amount of social support from family and friends in coping with each event that modify the way stress is perceived. (Author)
Information Theory - The Bridge Connecting Bounded Rational Game Theory and Statistical Physics
NASA Technical Reports Server (NTRS)
Wolpert, David H.
2005-01-01
A long-running difficulty with conventional game theory has been how to modify it to accommodate the bounded rationality of all red-world players. A recurring issue in statistical physics is how best to approximate joint probability distributions with decoupled (and therefore far more tractable) distributions. This paper shows that the same information theoretic mathematical structure, known as Product Distribution (PD) theory, addresses both issues. In this, PD theory not only provides a principle formulation of bounded rationality and a set of new types of mean field theory in statistical physics; it also shows that those topics are fundamentally one and the same.
Modified gravity in Arnowitt-Deser-Misner formalism
NASA Astrophysics Data System (ADS)
Gao, Changjun
2010-02-01
Motivated by Hořava-Lifshitz gravity theory, we propose and investigate two kinds of modified gravity theories, the f(R) kind and the K-essence kind, in the Arnowitt-Deser-Misner (ADM) formalism. The f(R) kind includes one ultraviolet (UV) term and one infrared (IR) term together with the Einstein-Hilbert action. We find that these two terms naturally present the ultraviolet and infrared modifications to the Friedmann equation. The UV and IR modifications can avoid the past Big-Bang singularity and the future Big-Rip singularity, respectively. Furthermore, the IR modification can naturally account for the current acceleration of the Universe. The Lagrangian of K-essence kind modified gravity is made up of the three-dimensional Ricci scalar and an arbitrary function of the extrinsic curvature term. We find the cosmic acceleration can also be naturally interpreted without invoking any kind of dark energy. The static, spherically symmetry and vacuum solutions of both theories are Schwarzschild or Schwarzschild-de Sitter solution. Thus these modified gravity theories are viable for solar system tests.
Nonisentropic unsteady three dimensional small disturbance potential theory
NASA Technical Reports Server (NTRS)
Gibbons, M. D.; Whitlow, W., Jr.; Williams, M. H.
1986-01-01
Modifications that allow for more accurate modeling of flow fields when strong shocks are present were made into three dimensional transonic small disturbance (TSD) potential theory. The Engquist-Osher type-dependent differencing was incorporated into the solution algorithm. The modified theory was implemented in the XTRAN3S computer code. Steady flows over a rectangular wing with a constant NACA 0012 airfoil section and an aspect ratio of 12 were calculated for freestream Mach numbers (M) of 0.82, 0.84, and 0.86. The obtained results are compared using the modified and unmodified TSD theories and the results from a three dimensional Euler code are presented. Nonunique solutions in three dimensions are shown to appear for the rectangular wing as aspect ratio increases. Steady and unsteady results are shown for the RAE tailplane model at M = 0.90. Calculations using unmodified theory, modified theory and experimental data are compared.
Modified gravity as dark energy
NASA Astrophysics Data System (ADS)
Sawicki, Ignacy
2007-08-01
We study the effects of introducing modifications to general relativity ("GR") at large scales as an alternative to exotic forms of matter required to replicate the observed cosmic acceleration. We survey the effects on cosmology and solar-system tests of Dvali-Gabadadze-Porrati ("DGP") gravity, f ( R ) he changes to the background expansion history of the universe, these modifications have substantial impact on structure formation and its observable predictions. For DGP, we develop a scaling approximation for the behaviour of perturbations off the brane, for which the predicted integrated Sachs-Wolf ("ISW") effect is much stronger than observed, requiring new physics at around horizon scale to bring it into agreement with data. We develop a test based on cross-correlating galaxies and the ISW effect which is independent of the initial power spectrum for perturbations and is a smoking-gun test for DGP gravity. For f ( R ) models, we find that, for the expansion history to resemble that of Lambda-CDM, it is required that the second derivative of f with respect to R be non-negative. We then find the conditions on f ( R ) which allow this subset of models to pass solar-system tests. Provided that gravity behave like GR in the galaxy, these constraints are weak. However, for a model to allow large deviations from GR in the cosmology, the galactic halo must differ significantly from that predicted by structure evolution in GR. We then discuss the effect that these models have on structure formation, and find that even in the most conservative of models, percent-level deviations in the matter power spectrum will exist and should be detectable in the future. Finally, for MSG, we investigate the cosmology of a theory of gravity with a modified constraint structure. The acceleration era can be replicated in these models; however, linear perturbations become unstable as the universe begins to accelerate. Once the perturbations become non-linear, the model reverts to GR
A Nonlinear Theory for Smart Composite Structures
NASA Technical Reports Server (NTRS)
Chattopadhyay, Aditi
2002-01-01
The paper discusses the following: (1) Development of a completely coupled thermo-piezoelectric-mechanical theory for the analysis of composite shells with segmented and distributed piezoelectric sensor/actuators and shape memory alloys. The higher order displacement theory will be used to capture the transverse shear effects in anisotropic composites. The original theory will be modified to satisfy the stress continuity at ply interfaces. (2) Development of a finite element technique to implement the mathematical model. (3) Investigation of the coupled structures/controls interaction problem to study the complex trade-offs associated with the coupled problem.
Modified Nanodiamonds for Detoxification
NASA Astrophysics Data System (ADS)
Gibson, Natalie Marie
essential for interacting with charged molecules, like OTA. Furthermore, the increased ZPs lead to improved colloidal stabilities over a wide range of pH, which is important for their interaction in the GI tract. While the dyes and OTA illustrated primarily electrostatic adsorption mechanisms, neutrally charged AfB1's adsorption was predominantly based upon the aggregate size of the ND substrate. In addition to mycotoxins, fluorescent dyes, including propidium iodide, pyranine and 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS), were initially utilized during methodological development. Fluorescent dye investigations helped assesses the adsorption mechanisms of NDs and demonstrated the significance of electrostatic interactions. Beyond electrostatic adsorption mechanisms, surface functional groups were also responsible for the amount of dye adsorbed, as was also true in OTA adsorption. Therefore, surface characterization was carried out for several ND samples by FTIR, TOF-SIMS and TDMS analysis. Final results of our studies show that our modified NDs perform better than yeast cells walls and other NDs but comparable to activated charcoal in the adsorption of AfB1, and outperform clay minerals in OTA studies. Moreover, it was demonstrated that adsorption can be maintained in a wide range of pH, thereby, increasing the possibility of NDs use in mycotoxins enterosorbent applications.
ERIC Educational Resources Information Center
Maleki, Zinat; Pazhakh, AbdolReza
2012-01-01
The present study was an attempt to investigate the effects of premodified input, interactionally modified input and modified output on 80 EFL learners' comprehension of new words. The subjects were randomly assigned into four groups of pre modified input, interactionally modified input, modified output and unmodified (control) groups. Each group…
Vector field models of modified gravity and the dark sector
Zuntz, J.; Ferreira, P. G.; Zlosnik, T. G; Bourliot, F.; Starkman, G. D.
2010-05-15
We present a comprehensive investigation of cosmological constraints on the class of vector field formulations of modified gravity called generalized Einstein-aether models. Using linear perturbation theory we generate cosmic microwave background and large-scale structure spectra for general parameters of the theory, and then constrain them in various ways. We investigate two parameter regimes: a dark matter candidate where the vector field sources structure formation, and a dark energy candidate where it causes late-time acceleration. We find that the dark matter candidate does not fit the data, and identify five physical problems that can restrict this and other theories of dark matter. The dark energy candidate does fit the data, and we constrain its fundamental parameters; most notably we find that the theory's kinetic index parameter n{sub ae} can differ significantly from its {Lambda}CDM value.
Dilaton cosmology and the modified uncertainty principle
NASA Astrophysics Data System (ADS)
Majumder, Barun
2011-09-01
Very recently Ali et al. (2009) proposed a new generalized uncertainty principle (with a linear term in Plank length which is consistent with doubly special relativity and string theory. The classical and quantum effects of this generalized uncertainty principle (termed as modified uncertainty principle or MUP) are investigated on the phase space of a dilatonic cosmological model with an exponential dilaton potential in a flat Friedmann-Robertson-Walker background. Interestingly, as a consequence of MUP, we found that it is possible to get a late time acceleration for this model. For the quantum mechanical description in both commutative and MUP framework, we found the analytical solutions of the Wheeler-DeWitt equation for the early universe and compare our results. We have used an approximation method in the case of MUP.
Modified polymers for gas chromatography
NASA Technical Reports Server (NTRS)
Woeller, F. H.; Christensen, W.; Mayer, L.
1979-01-01
Polymeric materials are modified to serve as stationary phase in chromatographic columns used for separation of atmospheric gases. Materials simplify and improve separation of atmospheric gases in terms of time, quantity of material needed, and sharpness of separation.
MS Disease-Modifying Medications
... Contents Injectable treatments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Oral treatments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Intravenous infusion treatments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Managing side effects of disease- modifying ... or subcutaneous), oral and intravenous (into the vein) infusion. INJECTABLE TREATMENTS Treatment (chemical name) Manufacturer Avonex ® (interferon ...
Topology of modified helical gears
NASA Technical Reports Server (NTRS)
Litvin, F. L.; Zhang, J.; Handschuh, R. F.; Coy, J. J.
1989-01-01
The topology of several types of modified surfaces of helical gears is proposed. The modified surfaces allow absorption of a linear or almost linear function of transmission errors. These errors are caused by gear misalignment and an improvement of the contact of gear tooth surfaces. Principles and corresponding programs for computer aided simulation of meshing and contact of gears have been developed. The results of this investigation are illustrated with numerical examples.