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Sample records for double exponential transform

  1. Double Exponential Relativity Theory Coupled Theoretically with Quantum Theory?

    SciTech Connect

    Montero Garcia, Jose de la Luz; Novoa Blanco, Jesus Francisco

    2007-04-28

    Here the problem of special relativity is analyzed into the context of a new theoretical formulation: the Double Exponential Theory of Special Relativity with respect to which the current Special or Restricted Theory of Relativity (STR) turns to be a particular case only.

  2. Weight Factor Selection in Double Exponential Smoothing Enrollment Forecasts.

    ERIC Educational Resources Information Center

    Gardner, Don E.

    1981-01-01

    The merits of double exponential smoothing are discussed relative to other types of pattern-based enrollment forecasting methods. The basic assumptions and formulas for its use are outlined. The difficulties associated with selecting an appropriate weight factor are discussed, and the potential effect on prediction results is illustrated.…

  3. Fourier Transforms of Pulses Containing Exponential Leading and Trailing Profiles

    SciTech Connect

    Warshaw, S I

    2001-07-15

    In this monograph we discuss a class of pulse shapes that have exponential rise and fall profiles, and evaluate their Fourier transforms. Such pulses can be used as models for time-varying processes that produce an initial exponential rise and end with the exponential decay of a specified physical quantity. Unipolar examples of such processes include the voltage record of an increasingly rapid charge followed by a damped discharge of a capacitor bank, and the amplitude of an electromagnetic pulse produced by a nuclear explosion. Bipolar examples include acoustic N waves propagating for long distances in the atmosphere that have resulted from explosions in the air, and sonic booms generated by supersonic aircraft. These bipolar pulses have leading and trailing edges that appear to be exponential in character. To the author's knowledge the Fourier transforms of such pulses are not generally well-known or tabulated in Fourier transform compendia, and it is the purpose of this monograph to derive and present these transforms. These Fourier transforms are related to a definite integral of a ratio of exponential functions, whose evaluation we carry out in considerable detail. From this result we derive the Fourier transforms of other related functions. In all Figures showing plots of calculated curves, the actual numbers used for the function parameter values and dependent variables are arbitrary and non-dimensional, and are not identified with any particular physical phenomenon or model.

  4. A double exponential model for biochemical oxygen demand.

    PubMed

    Mason, Ian G; McLachlan, Robert I; Gérard, Daniel T

    2006-01-01

    Biochemical oxygen demand (BOD) exertion patterns in anaerobically treated farm dairy wastewater were investigated on a laboratory scale. Oxygen uptake was typically characterised by a period of rapid oxygen exertion, a transitional "shoulder" phase and a period of slower activity. A multi-species model, involving rapidly degradable and slowly degradable material, was developed, leading to a double exponential model of BOD exertion as follows:where t is time, BOD(u1)(') and BOD(u2)(') are apparent ultimate BOD (BOD(u)) values, and k(1) and k(2) are rate constants. The model provided an improved description of BOD exertion patterns in anaerobically treated farm dairy wastewater in comparison to a conventional single exponential model, with rapidly degradable rate constant values (k(1)) ranging from 2.74 to 17.36d(-1), whilst slowly degradable rate constant values (k(2)) averaged 0.25d(-1) (range 0.20-0.29). Rapidly and slowly degradable apparent BOD(u) estimates ranged from 20 to 140g/m(3) and 225 to 500g/m(3), respectively, giving total BOD(u) levels of 265-620g/m(3). The mean square error in the curve fitting procedure ranged between 20 and 60g(2)/m(6), with values on average 70% lower (range 31-91%) than those obtained for the single exponential model. When applied to existing data for a range of other wastewaters, the double exponential model demonstrated a superior fit to the conventional single exponential model and provided a marginally better fit than a mixed order model. It is proposed that the presence of rapidly degradable material may be indicated from the value of the first rate constant (k1) and the time to 95% saturation of the first exponential function. Further model development is required to describe observed transitional and lag phases.

  5. Exponentials and Laplace transforms on nonuniform time scales

    NASA Astrophysics Data System (ADS)

    Ortigueira, Manuel D.; Torres, Delfim F. M.; Trujillo, Juan J.

    2016-10-01

    We formulate a coherent approach to signals and systems theory on time scales. The two derivatives from the time-scale calculus are used, i.e., nabla (forward) and delta (backward), and the corresponding eigenfunctions, the so-called nabla and delta exponentials, computed. With these exponentials, two generalised discrete-time Laplace transforms are deduced and their properties studied. These transforms are compatible with the standard Laplace and Z transforms. They are used to study discrete-time linear systems defined by difference equations. These equations mimic the usual continuous-time equations that are uniformly approximated when the sampling interval becomes small. Impulse response and transfer function notions are introduced. This implies a unified mathematical framework that allows us to approximate the classic continuous-time case when the sampling rate is high or to obtain the standard discrete-time case, based on difference equations, when the time grid becomes uniform.

  6. A note on large gauge transformations in double field theory

    DOE PAGES

    Naseer, Usman

    2015-06-01

    We give a detailed proof of the conjecture by Hohm and Zwiebach in double field theory. This result implies that their proposal for large gauge transformations in terms of the Jacobian matrix for coordinate transformations is, as required, equivalent to the standard exponential map associated with the generalized Lie derivative along a suitable parameter.

  7. The double-assignment method for the exponential chaotic tabu search in quadratic assignment problems

    NASA Astrophysics Data System (ADS)

    Shibata, Kazuaki; Horio, Yoshihiko; Aihara, Kazuyuki

    The quadratic assignment problem (QAP) is one of the NP-hard combinatorial optimization problems. An exponential chaotic tabu search using a 2-opt algorithm driven by chaotic neuro-dynamics has been proposed as one heuristic method for solving QAPs. In this paper we first propose a new local search, the double-assignment method, suitable for the exponential chaotic tabu search, which adopts features of the Lin-Kernighan algorithm. We then introduce chaotic neuro-dynamics into the double-assignment method to propose a novel exponential chaotic tabu search. We further improve the proposed exponential chaotic tabu search with the double-assignment method by enhancing the effect of chaotic neuro-dynamics.

  8. Terahertz double-exponential model for adsorption of volatile organic compounds in active carbon

    NASA Astrophysics Data System (ADS)

    Zhu, Jing; Zhan, Honglei; Miao, Xinyang; Zhao, Kun; Zhou, Qiong

    2017-06-01

    In terms of the evaluation of the diffusion-controlled adsorption and diffused rate, a mathematical model was built on the basis of the double-exponential kinetics model and terahertz amplitude in this letter. The double-exponential-THz model described the two-step mechanism controlled by diffusion. A rapid step involves external and internal diffusion, followed by a slow step controlled by intraparticle diffusion. The concentration gradient of the molecules promoted the organic molecules rapidly diffusing to the external surface of adsorbent. The solute molecules then transferred across the liquid film. Intraparticle diffusion began and was determined by the molecular sizes, as well as affinities between organics and activated carbon.

  9. The mechanism of double-exponential growth in hyper-inflation

    NASA Astrophysics Data System (ADS)

    Mizuno, T.; Takayasu, M.; Takayasu, H.

    2002-05-01

    Analyzing historical data of price indices, we find an extraordinary growth phenomenon in several examples of hyper-inflation in which, price changes are approximated nicely by double-exponential functions of time. In order to explain such behavior we introduce the general coarse-graining technique in physics, the Monte Carlo renormalization group method, to the price dynamics. Starting from a microscopic stochastic equation describing dealers’ actions in open markets, we obtain a macroscopic noiseless equation of price consistent with the observation. The effect of auto-catalytic shortening of characteristic time caused by mob psychology is shown to be responsible for the double-exponential behavior.

  10. Double slip effects of Magnetohydrodynamic (MHD) boundary layer flow over an exponentially stretching sheet with radiation, heat source and chemical reaction

    NASA Astrophysics Data System (ADS)

    Shaharuz Zaman, Azmanira; Aziz, Ahmad Sukri Abd; Ali, Zaileha Md

    2017-09-01

    The double slips effect on the magnetohydrodynamic boundary layer flow over an exponentially stretching sheet with suction/blowing, radiation, chemical reaction and heat source is presented in this analysis. By using the similarity transformation, the governing partial differential equations of momentum, energy and concentration are transformed into the non-linear ordinary equations. These equations are solved using Runge-Kutta-Fehlberg method with shooting technique in MAPLE software environment. The effects of the various parameter on the velocity, temperature and concentration profiles are graphically presented and discussed.

  11. Research on Copy-Move Image Forgery Detection Using Features of Discrete Polar Complex Exponential Transform

    NASA Astrophysics Data System (ADS)

    Gan, Yanfen; Zhong, Junliu

    2015-12-01

    With the aid of sophisticated photo-editing software, such as Photoshop, copy-move image forgery operation has been widely applied and has become a major concern in the field of information security in the modern society. A lot of work on detecting this kind of forgery has gained great achievements, but the detection results of geometrical transformations of copy-move regions are not so satisfactory. In this paper, a new method based on the Polar Complex Exponential Transform is proposed. This method addresses issues in image geometric moment, focusing on constructing rotation invariant moment and extracting features of the rotation invariant moment. In order to reduce rounding errors of the transform from the Polar coordinate system to the Cartesian coordinate system, a new transformation method is presented and discussed in detail at the same time. The new method constructs a 9 × 9 shrunk template to transform the Cartesian coordinate system back to the Polar coordinate system. It can reduce transform errors to a much greater degree. Forgery detection, such as copy-move image forgery detection, is a difficult procedure, but experiments prove our method is a great improvement in detecting and identifying forgery images affected by the rotated transform.

  12. Nuclear counting filter based on a centered Skellam test and a double exponential smoothing

    SciTech Connect

    Coulon, Romain; Kondrasovs, Vladimir; Dumazert, Jonathan; Rohee, Emmanuel; Normand Stephane

    2015-07-01

    Online nuclear counting represents a challenge due to the stochastic nature of radioactivity. The count data have to be filtered in order to provide a precise and accurate estimation of the count rate, this with a response time compatible with the application in view. An innovative filter is presented in this paper addressing this issue. It is a nonlinear filter based on a Centered Skellam Test (CST) giving a local maximum likelihood estimation of the signal based on a Poisson distribution assumption. This nonlinear approach allows to smooth the counting signal while maintaining a fast response when brutal change activity occur. The filter has been improved by the implementation of a Brown's double Exponential Smoothing (BES). The filter has been validated and compared to other state of the art smoothing filters. The CST-BES filter shows a significant improvement compared to all tested smoothing filters. (authors)

  13. Modeling of Single Event Transients With Dual Double-Exponential Current Sources: Implications for Logic Cell Characterization

    NASA Astrophysics Data System (ADS)

    Black, Dolores A.; Robinson, William H.; Wilcox, Ian Z.; Limbrick, Daniel B.; Black, Jeffrey D.

    2015-08-01

    Single event effects (SEE) are a reliability concern for modern microelectronics. Bit corruptions can be caused by single event upsets (SEUs) in the storage cells or by sampling single event transients (SETs) from a logic path. An accurate prediction of soft error susceptibility from SETs requires good models to convert collected charge into compact descriptions of the current injection process. This paper describes a simple, yet effective, method to model the current waveform resulting from a charge collection event for SET circuit simulations. The model uses two double-exponential current sources in parallel, and the results illustrate why a conventional model based on one double-exponential source can be incomplete. A small set of logic cells with varying input conditions, drive strength, and output loading are simulated to extract the parameters for the dual double-exponential current sources. The parameters are based upon both the node capacitance and the restoring current (i.e., drive strength) of the logic cell.

  14. A kinetic theory for nonanalog Monte Carlo algorithms: Exponential transform with angular biasing

    SciTech Connect

    Ueki, T.; Larsen, E.W.

    1998-11-01

    A new Boltzmann Monte Carlo (BMC) equation is proposed to describe the transport of Monte Carlo particles governed by a set of nonanalog rules for the transition of space, velocity, and weight. The BMC equation is a kinetic equation that includes weight as an extra independent variable. The solution of the BMC equation is the pointwise distribution of velocity and weight throughout the physical system. The BMC equation is derived for the simulation of a transmitted current, utilizing the exponential transform with angular biasing. The weight moments of the solution of the BMC equation are used to predict the score moments of the transmission current. (Also, it is shown that an adjoint BMC equation can be used for this purpose.) Integrating the solution of the forward BMC equation over space, velocity, and weight, the mean number of flights per history is obtained. This is used to determine theoretically the figure of merit for any choice of biasing parameters. Also, a maximum safe value of the exponential transform parameter is proposed, which ensure the finite variance of variance estimate (sample variance) for any penetration distance. Finally, numerical results that validate the new theory are provided.

  15. Enrollment Forecasting with Double Exponential Smoothing: Two Methods for Objective Weight Factor Selection. AIR Forum 1980 Paper.

    ERIC Educational Resources Information Center

    Gardner, Don E.

    The merits of double exponential smoothing are discussed relative to other types of pattern-based enrollment forecasting methods. The difficulties associated with selecting an appropriate weight factor are discussed, and their potential effects on prediction results are illustrated. Two methods for objectively selecting the "best" weight…

  16. (q,μ) and (p,q,ζ)-exponential functions: Rogers-Szego˝ polynomials and Fourier-Gauss transform

    NASA Astrophysics Data System (ADS)

    Hounkonnou, Mahouton Norbert; Nkouankam, Elvis Benzo Ngompe

    2010-10-01

    From the realization of q-oscillator algebra in terms of generalized derivative, we compute the matrix elements from deformed exponential functions and deduce generating functions associated with Rogers-Szegő polynomials as well as their relevant properties. We also compute the matrix elements associated with the (p,q)-oscillator algebra (a generalization of the q-one) and perform the Fourier-Gauss transform of a generalization of the deformed exponential functions.

  17. (q,{mu}) and (p,q,{zeta})-exponential functions: Rogers-Szego'' polynomials and Fourier-Gauss transform

    SciTech Connect

    Hounkonnou, Mahouton Norbert; Nkouankam, Elvis Benzo Ngompe

    2010-10-15

    From the realization of q-oscillator algebra in terms of generalized derivative, we compute the matrix elements from deformed exponential functions and deduce generating functions associated with Rogers-Szego polynomials as well as their relevant properties. We also compute the matrix elements associated with the (p,q)-oscillator algebra (a generalization of the q-one) and perform the Fourier-Gauss transform of a generalization of the deformed exponential functions.

  18. Analysis of Reflected Diffusions via an Exponential Time-Based Transformation

    NASA Astrophysics Data System (ADS)

    Di Crescenzo, Antonio; Giorno, Virginia; Nobile, Amelia G.

    2016-06-01

    Let X( t) be a time-homogeneous diffusion process with state-space [0,+∞ ), where 0 is a reflecting or entrance endpoint, and let Z denote a random variable that describes the process X( t) evaluated at an exponentially distributed random time. We propose a method to obtain closed-form expressions for the conditional density and the mean of a new diffusion process Y( t), with the same state-space and with the same infinitesimal variance, whose drift depends on the infinitesimal moments of X( t) and on the hazard rate function of Z. This method also allows us to obtain the Laplace transform of the first-passage-time density of Y( t) through a lower constant boundary. We then discuss the relation between Y( t) and the process X( t) subject to catastrophes, as well as the interpretation of Y( t) as a diffusion in a decreasing potential. We study in detail some special cases concerning diffusion processes obtained when X( t) is the Wiener, Ornstein-Uhlenbeck, Bessel and Rayleigh process.

  19. Modeling of single event transients with dual double-exponential current sources: Implications for logic cell characterization

    DOE PAGES

    Black, Dolores Archuleta; Robinson, William H.; Wilcox, Ian Zachary; ...

    2015-08-07

    Single event effects (SEE) are a reliability concern for modern microelectronics. Bit corruptions can be caused by single event upsets (SEUs) in the storage cells or by sampling single event transients (SETs) from a logic path. Likewise, an accurate prediction of soft error susceptibility from SETs requires good models to convert collected charge into compact descriptions of the current injection process. This paper describes a simple, yet effective, method to model the current waveform resulting from a charge collection event for SET circuit simulations. The model uses two double-exponential current sources in parallel, and the results illustrate why a conventionalmore » model based on one double-exponential source can be incomplete. Furthermore, a small set of logic cells with varying input conditions, drive strength, and output loading are simulated to extract the parameters for the dual double-exponential current sources. As a result, the parameters are based upon both the node capacitance and the restoring current (i.e., drive strength) of the logic cell.« less

  20. Modeling of single event transients with dual double-exponential current sources: Implications for logic cell characterization

    SciTech Connect

    Black, Dolores Archuleta; Robinson, William H.; Wilcox, Ian Zachary; Limbrick, Daniel B.; Black, Jeffrey D.

    2015-08-07

    Single event effects (SEE) are a reliability concern for modern microelectronics. Bit corruptions can be caused by single event upsets (SEUs) in the storage cells or by sampling single event transients (SETs) from a logic path. Likewise, an accurate prediction of soft error susceptibility from SETs requires good models to convert collected charge into compact descriptions of the current injection process. This paper describes a simple, yet effective, method to model the current waveform resulting from a charge collection event for SET circuit simulations. The model uses two double-exponential current sources in parallel, and the results illustrate why a conventional model based on one double-exponential source can be incomplete. Furthermore, a small set of logic cells with varying input conditions, drive strength, and output loading are simulated to extract the parameters for the dual double-exponential current sources. As a result, the parameters are based upon both the node capacitance and the restoring current (i.e., drive strength) of the logic cell.

  1. W-transform for exponential stability of second order delay differential equations without damping terms.

    PubMed

    Domoshnitsky, Alexander; Maghakyan, Abraham; Berezansky, Leonid

    2017-01-01

    In this paper a method for studying stability of the equation [Formula: see text] not including explicitly the first derivative is proposed. We demonstrate that although the corresponding ordinary differential equation [Formula: see text] is not exponentially stable, the delay equation can be exponentially stable.

  2. Investigation of the double exponential in the current-voltage characteristics of silicon solar cells

    NASA Technical Reports Server (NTRS)

    Wolf, M.; Noel, G. T.; Stirn, R. J.

    1976-01-01

    A theoretical analysis is presented of certain peculiarities of the current-voltage characteristics of silicon solar cells, involving high values of the empirical constant A in the diode equation for a p-n junction. An attempt was made in a lab experiment to demonstrate that the saturation current which is associated with the exponential term qV/A2kT of the I-V characteristic, with A2 roughly equal to 2, originates in the space charge region and that it can be increased, as observed on ATS-1 cells, by the introduction of additional defects through low energy proton irradiation. It was shown that the proton irradiation introduces defects into the space charge region which give rise to a recombination current from this region, although the I-V characteristic is, in this case, dominated by an exponential term which has A = 1.

  3. Recognizing Physisorption and Chemisorption in Carbon Nanotubes Gas Sensors by Double Exponential Fitting of the Response

    PubMed Central

    Calvi, Andrea; Ferrari, Alberto; Sbuelz, Luca; Goldoni, Andrea; Modesti, Silvio

    2016-01-01

    Multi-walled carbon nanotubes (CNTs) have been grown in situ on a SiO2 substrate and used as gas sensors. For this purpose, the voltage response of the CNTs as a function of time has been used to detect H2 and CO2 at various concentrations by supplying a constant current to the system. The analysis of both adsorptions and desorptions curves has revealed two different exponential behaviours for each curve. The study of the characteristic times, obtained from the fitting of the data, has allowed us to identify separately chemisorption and physisorption processes on the CNTs. PMID:27213387

  4. A passive technique for detecting copy-move forgery with rotation based on polar complex exponential transform

    NASA Astrophysics Data System (ADS)

    Emam, Mahmoud; Han, Qi; Yu, Liyang; Zhang, Ye; Niu, Xiamu

    2015-07-01

    Copy-move is one of the most common methods for image manipulation. Several methods have been proposed to detect and locate the tampered regions, while many methods failed when the copied regions are rotated before being pasted. A rotational invariant detecting method using Polar Complex Exponential Transform (PCET) is proposed in this paper. Firstly, the original image is divided into overlapping circular blocks, and PCET is employed to each block to extract the rotation-invariant robust features. Secondly, the Approximate Nearest Neighbors (ANN) of each feature vector are collected by Locality Sensitive Hashing (LSH). Experimental results show that the proposed technique is robust to rotation.

  5. Normalization method of highly forward-peaked scattering phase function using the double exponential formula for radiative transfer

    NASA Astrophysics Data System (ADS)

    Fujii, Hiroyuki; Okawa, Shinpei; Yamada, Yukio; Hoshi, Yoko; Watanabe, Masao

    2016-12-01

    Numerical calculation of photon migration in biological tissue using the radiative transfer equation (RTE) has attracted great interests in biomedical optics and imaging. Because biological tissue is a highly forward-peaked scattering medium, a normalization of scattering phase function in the RTE is crucial. This paper proposes a simple way of normalizing the phase function by the double exponential formula, which is heuristically modified from the original one. The proposed method is validated by the agreement between the numerical solution of the RTE with the proposed method and analytical solution of the RTE for the case of a highly forward-peaked scattering medium, while the numerical solutions with conventional normalization methods disagree with the analytical solution. This result suggests the proposed method is accurate in numerical calculation of the RTE.

  6. 15-digit accuracy calculations of Chandrasekhar's H-function for isotropic scattering by means of the double exponential formula

    NASA Astrophysics Data System (ADS)

    Kawabata, Kiyoshi

    2016-12-01

    This work shows that it is possible to calculate numerical values of the Chandrasekhar H-function for isotropic scattering at least with 15-digit accuracy by making use of the double exponential formula (DE-formula) of Takahashi and Mori (Publ. RIMS, Kyoto Univ. 9:721, 1974) instead of the Gauss-Legendre quadrature employed in the numerical scheme of Kawabata and Limaye (Astrophys. Space Sci. 332:365, 2011) and simultaneously taking a precautionary measure to minimize the effects due to loss of significant digits particularly in the cases of near-conservative scattering and/or errors involved in returned values of library functions supplied by compilers in use. The results of our calculations are presented for 18 selected values of single scattering albedo π0 and 22 values of an angular variable μ, the cosine of zenith angle θ specifying the direction of radiation incident on or emergent from semi-infinite media.

  7. Characteristics of Double Exponentially Tapered Slot Antenna (DETSA) Conformed in the Longitudinal Direction Around a Cylindrical Structure

    NASA Technical Reports Server (NTRS)

    Ponchak, George E.; Jordan, Jennifer L.; Chevalier, Christine T.

    2006-01-01

    The characteristics of a double exponentially tapered slot antenna (DETSA) as a function of the radius that the DETSA is conformed to in the longitudinal direction is presented. It is shown through measurements and simulations that the radiation pattern of the conformed antenna rotates in the direction through which the antenna is curved, and that diffraction affects the radiation pattern if the radius of curvature is too small or the frequency too high. The gain of the antenna degrades by only 1 dB if the radius of curvature is large and more than 2 dB for smaller radii. The main effect due to curving the antenna is an increased cross-polarization in the E-plane.

  8. Innovation in Pediatric Cardiac Intensive Care: An Exponential Convergence Toward Transformation of Care.

    PubMed

    Maher, Kevin O; Chang, Anthony C; Shin, Andrew; Hunt, Juliette; Wong, Hector R

    2015-10-01

    The word innovation is derived from the Latin noun innovatus, meaning renewal or change. Although companies such as Google and Apple are nearly synonymous with innovation, virtually all sectors in our current lives are imbued with yearn for innovation. This has led to organizational focus on innovative strategies as well as recruitment of chief innovation officers and teams in a myriad of organizations. At times, however, the word innovation seems like an overused cliché, as there are now more than 5,000 books in print with the word "innovation" in the title. More recently, innovation has garnered significant attention in health care. The future of health care is expected to innovate on a large scale in order to deliver sustained value for an overall transformative care. To date, there are no published reports on the state of the art in innovation in pediatric health care and in particular, pediatric cardiac intensive care. This report will address the issue of innovation in pediatric medicine with relevance to cardiac intensive care and delineate possible future directions and strategies in pediatric cardiac intensive care.

  9. Beam hardening correction for interior tomography based on exponential formed model and radon inversion transform

    NASA Astrophysics Data System (ADS)

    Chen, Siyu; Zhang, Hanming; Li, Lei; Xi, Xiaoqi; Han, Yu; Yan, Bin

    2016-10-01

    X-ray computed tomography (CT) has been extensively applied in industrial non-destructive testing (NDT). However, in practical applications, the X-ray beam polychromaticity often results in beam hardening problems for image reconstruction. The beam hardening artifacts, which manifested as cupping, streaks and flares, not only debase the image quality, but also disturb the subsequent analyses. Unfortunately, conventional CT scanning requires that the scanned object is completely covered by the field of view (FOV), the state-of-art beam hardening correction methods only consider the ideal scanning configuration, and often suffer problems for interior tomography due to the projection truncation. Aiming at this problem, this paper proposed a beam hardening correction method based on radon inversion transform for interior tomography. Experimental results show that, compared to the conventional correction algorithms, the proposed approach has achieved excellent performance in both beam hardening artifacts reduction and truncation artifacts suppression. Therefore, the presented method has vitally theoretic and practicable meaning in artifacts correction of industrial CT.

  10. Double Stage Heat Transformer Controlled by Flow Ratio

    NASA Astrophysics Data System (ADS)

    Silva-Sotelo, S.; Romero, R. J.; Rodríguez – Martínez, A.

    this paper shows the values of Flow ratio (FR) for control of an absorption double stage heat transformer. The main parameters for the heat pump system are defined as COP, FR and GTL. The control of the entire system is based in a new definition of FR. The heat balance of the Double Stage Heat Transformer (DSHT) is used for the control. The mass flow is calculated for a HPVEE program and a second program control the mass flow. The mass flow is controlled by gear pumps connected to LabView program. The results show an increment in the fraction of the recovery energy. An example of oil distillation is used for the calculation. The waste heat energy is added at the system at 70 °C. Water ™ - Carrol mixture is used in the DSHT. The recover energy is obtained in a second absorber at 128 °C with two scenarios.

  11. Practical aspects of the maximum entropy inversion of the laplace transform for the quantitative analysis of multi-exponential data.

    PubMed

    Lórenz-Fonfría, Víctor A; Kandori, Hideki

    2007-01-01

    The number, position, area, and width of the bands in a lifetime distribution give the number of exponentials present in time-resolved data and their time constants, amplitudes, and heterogeneities. The maximum entropy inversion of the Laplace transform (MaxEnt-iLT) provides a lifetime distribution from time-resolved data, which is very helpful in the analysis of the relaxation of complex systems. In some applications both positive and negative values for the lifetime distribution amplitudes are physical, but most studies to date have focused on positive-constrained solutions. In this work, we first discuss optimal conditions to obtain a sign-unrestricted maximum entropy lifetime distribution, i.e., the selection of the entropy function and the regularization value. For the selection of the regularization value we compared four methods: the chi2 criterion and Bayesian inference (already used in sign-restricted MaxEnt-iLT), and the L-curve and the generalized cross-validation methods (not yet used in MaxEnt-iLT to our knowledge). Except for the frequently used chi2 criterion, these methods recommended similar regularization values, providing close to optimum solutions. However, even when an optimal entropy function and regularization value are used, a MaxEnt lifetime distribution will contain noise-induced errors, as well as systematic distortions induced by the entropy maximization (regularization-induced errors). We introduce the concept of the apparent resolution function in MaxEnt, which allows both the noise and regularization-induced errors to be estimated. We show the capability of this newly introduced concept in both synthetic and experimental time-resolved Fourier transform infrared (FT-IR) data from the bacteriorhodopsin photocycle.

  12. Exponential-type basis functions: Single- and double-zeta B function basis sets for the ground states of neutral atoms from Z = 2 to Z = 36

    SciTech Connect

    Ema, I.; Vega, J.M.G. de la; Miguel, B.; Dotterweich, J.; Meissner, H.; Steinborn, E.O.

    1999-05-01

    Roothaan-Hartree-Fock (RHF) calculations have been carried out for the ground states of the atoms from helium to krypton using certain exponential-type functions, the B functions. The authors report a compilation of single- and double-zeta (SZ and DZ) wave functions. A comparison with the conventional SZ and DZ RHF wave functions is also presented. For each atom, the total energy, kinetic energy, potential energy, virial ratio, orbital energies, and orbital expansion coefficients and exponents are tabulated.

  13. Generation of Doubled Haploid Transgenic Wheat Lines by Microspore Transformation

    PubMed Central

    Liu, Weiguo; Konzak, Calvin F.; von Wettstein, Diter; Rustgi, Sachin

    2013-01-01

    Microspores can be induced to develop homozygous doubled haploid plants in a single generation. In the present experiments androgenic microspores of wheat have been genetically transformed and developed into mature homozygous transgenic plants. Two different transformation techniques were investigated, one employing electroporation and the other co-cultivation with Agrobacterium tumefaciens. Different tissue culture and transfection conditions were tested on nine different wheat cultivars using four different constructs. A total of 19 fertile transformants in five genotypes from four market classes of common wheat were recovered by the two procedures. PCR followed by DNA sequencing of the products, Southern blot analyses and bio/histo-chemical and histological assays of the recombinant enzymes confirmed the presence of the transgenes in the T0 transformants and their stable inheritance in homozygous T1∶2 doubled haploid progenies. Several decisive factors determining the transformation and regeneration efficiency with the two procedures were determined: (i) pretreatment of immature spikes with CuSO4 solution (500 mg/L) at 4°C for 10 days; (ii) electroporation of plasmid DNA in enlarged microspores by a single pulse of ∼375 V; (iii) induction of microspores after transfection at 28°C in NPB-99 medium and regeneration at 26°C in MMS5 medium; (iv) co-cultivation with Agrobacterium AGL-1 cells for transfer of plasmid T-DNA into microspores at day 0 for <24 hours; and (v) elimination of AGL-1 cells after co-cultivation with timentin (200–400 mg/L). PMID:24260351

  14. Double passing the Kitt Peak 1-m Fourier transform spectrometer

    NASA Technical Reports Server (NTRS)

    Jennings, D. E.; Hubbard, R.; Brault, J. W.

    1985-01-01

    Attention is given to a simple technique for performing the conversion of the Kitt Peak 1-m Fourier transform spectrometer's dual input/output optical configuration to a double pass configuration that improves spectral resolution by a factor of 2. The modification is made by placing a flat mirror in the output beam from each cat's eye, retroreflecting the beams back through the cat's eyes to the first beam splitter. A single detector is placed at the second input port, which then becomes the instrument's output.

  15. Double wavelet transform of frequency-modulated nonstationary signal

    NASA Astrophysics Data System (ADS)

    Bozhokin, S. V.; Suslova, I. M.

    2013-12-01

    A mathematical model is proposed for a frequency-modulated signal in the form of a system of Gaussian peaks randomly distributed in time. An analytic expression is obtained for continuous wavelet transform (CWT) of the model signal. For signals with time-varying sequence of peaks, the main ridge of the skeleton characterized by frequency ν{max/MFB} ( t) is analyzed. The value of ν{max/MFB} ( t) is determined for any instant t from the condition of the CWT maximum in the spectral range of the main frequency band (MFB). Double CWT of function ν{max/MFB} ( t) is calculated for a frequency-modulated signal with a transition regions of smooth frequency variation (trend) as well as with varying frequency oscillations relative to the trend. The duration of transition periods of the signal is determined using spectral integrals E ν( t). The instants of emergence and decay of low-frequency spectral components of the signal are determined. The double CWT method can be used for analyzing cardiac rhythms and neural activity, as well as nonstationary processes in quantum radio physics and astronomy.

  16. Quantum Fourier Transforms and the Complexity of Link Invariants for Quantum Doubles of Finite Groups

    NASA Astrophysics Data System (ADS)

    Krovi, Hari; Russell, Alexander

    2015-03-01

    Knot and link invariants naturally arise from any braided Hopf algebra. We consider the computational complexity of the invariants arising from an elementary family of finite-dimensional Hopf algebras: quantum doubles of finite groups [denoted , for a group G]. These induce a rich family of knot invariants and, additionally, are directly related to topological quantum computation. Regarding algorithms for these invariants, we develop quantum circuits for the quantum Fourier transform over ; in general, we show that when one can uniformly and efficiently carry out the quantum Fourier transform over the centralizers Z( g) of the elements of G, one can efficiently carry out the quantum Fourier transform over . We apply these results to the symmetric groups to yield efficient circuits for the quantum Fourier transform over . With such a Fourier transform, it is straightforward to obtain additive approximation algorithms for the related link invariant. As for hardness results, first we note that in contrast to those concerning the Jones polynomial—where the images of the braid group representations are dense in the unitary group—the images of the representations arising from are finite. This important difference appears to be directly reflected in the complexity of these invariants. While additively approximating "dense" invariants is -complete and multiplicatively approximating them is -complete, we show that certain invariants (such as invariants) are -hard to additively approximate, -hard to multiplicatively approximate, and -hard to exactly evaluate. To show this, we prove that, for groups (such as A n ) which satisfy certain properties, the probability of success of any randomized computation can be approximated to within any by the plat closure. Finally, we make partial progress on the question of simulating anyonic computation in groups uniformly as a function of the group size. In this direction, we provide efficient quantum circuits for the Clebsch

  17. Ammonium Removal from Aqueous Solutions by Clinoptilolite: Determination of Isotherm and Thermodynamic Parameters and Comparison of Kinetics by the Double Exponential Model and Conventional Kinetic Models

    PubMed Central

    Tosun, İsmail

    2012-01-01

    The adsorption isotherm, the adsorption kinetics, and the thermodynamic parameters of ammonium removal from aqueous solution by using clinoptilolite in aqueous solution was investigated in this study. Experimental data obtained from batch equilibrium tests have been analyzed by four two-parameter (Freundlich, Langmuir, Tempkin and Dubinin-Radushkevich (D-R)) and four three-parameter (Redlich-Peterson (R-P), Sips, Toth and Khan) isotherm models. D-R and R-P isotherms were the models that best fitted to experimental data over the other two- and three-parameter models applied. The adsorption energy (E) from the D-R isotherm was found to be approximately 7 kJ/mol for the ammonium-clinoptilolite system, thereby indicating that ammonium is adsorbed on clinoptilolite by physisorption. Kinetic parameters were determined by analyzing the nth-order kinetic model, the modified second-order model and the double exponential model, and each model resulted in a coefficient of determination (R2) of above 0.989 with an average relative error lower than 5%. A Double Exponential Model (DEM) showed that the adsorption process develops in two stages as rapid and slow phase. Changes in standard free energy (∆G°), enthalpy (∆H°) and entropy (∆S°) of ammonium-clinoptilolite system were estimated by using the thermodynamic equilibrium coefficients. PMID:22690177

  18. Ammonium removal from aqueous solutions by clinoptilolite: determination of isotherm and thermodynamic parameters and comparison of kinetics by the double exponential model and conventional kinetic models.

    PubMed

    Tosun, Ismail

    2012-03-01

    The adsorption isotherm, the adsorption kinetics, and the thermodynamic parameters of ammonium removal from aqueous solution by using clinoptilolite in aqueous solution was investigated in this study. Experimental data obtained from batch equilibrium tests have been analyzed by four two-parameter (Freundlich, Langmuir, Tempkin and Dubinin-Radushkevich (D-R)) and four three-parameter (Redlich-Peterson (R-P), Sips, Toth and Khan) isotherm models. D-R and R-P isotherms were the models that best fitted to experimental data over the other two- and three-parameter models applied. The adsorption energy (E) from the D-R isotherm was found to be approximately 7 kJ/mol for the ammonium-clinoptilolite system, thereby indicating that ammonium is adsorbed on clinoptilolite by physisorption. Kinetic parameters were determined by analyzing the nth-order kinetic model, the modified second-order model and the double exponential model, and each model resulted in a coefficient of determination (R(2)) of above 0.989 with an average relative error lower than 5%. A Double Exponential Model (DEM) showed that the adsorption process develops in two stages as rapid and slow phase. Changes in standard free energy (∆G°), enthalpy (∆H°) and entropy (∆S°) of ammonium-clinoptilolite system were estimated by using the thermodynamic equilibrium coefficients.

  19. Investigation of the double exponential in the current-voltage characteristics of silicon solar cells. [proton irradiation effects on ATS 1 cells

    NASA Technical Reports Server (NTRS)

    Wolf, M.; Noel, G. T.; Stirn, R. J.

    1977-01-01

    Difficulties in relating observed current-voltage characteristics of individual silicon solar cells to their physical and material parameters were underscored by the unexpected large changes in the current-voltage characteristics telemetered back from solar cells on the ATS-1 spacecraft during their first year in synchronous orbit. Depletion region recombination was studied in cells exhibiting a clear double-exponential dark characteristic by subjecting the cells to proton irradiation. A significant change in the saturation current, an effect included in the Sah, Noyce, Shockley formulation of diode current resulting from recombination in the depletion region, was caused by the introduction of shallow levels in the depletion region by the proton irradiation. This saturation current is not attributable only to diffusion current from outside the depletion region and only its temperature dependence can clarify its origin. The current associated with the introduction of deep-lying levels did not change significantly in these experiments.

  20. Three-dimensional measurements by using deflectometry and the double Hilbert transform

    NASA Astrophysics Data System (ADS)

    Na, Silin; Yu, Younghun; Shin, Sanghoon

    2016-08-01

    An improved phase retrieval method based the Hilbert transform is introduced to quantitatively calculate the phase distribution from the distorted fringe pattern. Also phase measurement deflectomety is widely used in specular-type samples. The background noise or background should be suppressed prior to applying Hilbert transform. In this process, a method for suppressing the background noise the double Hilbert transform, fast, automated, which requires only one image, is presented. The method is easy to implement, and measurements can be conducted. We used the double Hilbert transform method to retrieve the phase and suppressed the background in computer simulations and experiments involving the phase measuring deflectometry method.

  1. Novel double phase transforming organogel based on β-cyclodextrin in 1,2-propylene glycol.

    PubMed

    Liu, Wenqi; Xing, Pengyao; Xin, Feifei; Hou, Yuehui; Sun, Tao; Hao, Jingcheng; Hao, Aiyou

    2012-11-01

    This paper describes a novel double phase transforming organogel (gel-sol-gel') composed of nontoxic β-cyclodextrin, potassium carbonate, and 1,2-propylene glycol. The gel-sol-gel' transforming processes are followed by a reversible gel-sol transforming process and an irreversible sol-gel' transforming process based on heating. The gel-sol-gel' transformation is accompanied by microstructure changes from nanospheres to nanorods. K(2)CO(3) plays a key role in associating supramolecular architectures of β-cyclodextrin into a three-dimensional network. This work may bring further applications in the areas of smart materials, drug delivery systems, and biomaterials.

  2. Quantum image encryption based on generalized Arnold transform and double random-phase encoding

    NASA Astrophysics Data System (ADS)

    Zhou, Nan Run; Hua, Tian Xiang; Gong, Li Hua; Pei, Dong Ju; Liao, Qing Hong

    2015-04-01

    A quantum realization of the generalized Arnold transform is designed. A novel quantum image encryption algorithm based on generalized Arnold transform and double random-phase encoding is proposed. The pixels are scrambled by the generalized Arnold transform, and the gray-level information of images is encoded by the double random-phase operations. The keys of the encryption algorithm include the independent parameters of coefficients matrix, iterative times and classical binary sequences, and thus, the key space is extremely large. Numerical simulations and theoretical analyses demonstrate that the proposed algorithm with good feasibility and effectiveness has lower computational complexity than its classical counterpart.

  3. [A two-dimensional double dispersed hadamard transform spectrometer].

    PubMed

    Liu, Jia; Shi, Lei; Li, Kai; Zheng, Xin-Wen; Zeng, Li-Bo; Wu, Qiong-Shui

    2012-06-01

    A kind of two-dimensional hadamard transform spectrometer was developed. A grating was used for chromatic dispersion of orders and a prism was used for spectral dispersion. Quite different from traditional CCD detection method, a digital micromirror device (DMD) was applied for optical modulation, and a simple point detector was used as the sensor. Compared with traditional two-dimensional spectrometer, it has the advantage of high resolution and signal-noise-ratio, which was proved by theoretical calculation and computer simulation.

  4. Exponential Increase in Relative Biological Effectiveness Along Distal Edge of a Proton Bragg Peak as Measured by Deoxyribonucleic Acid Double-Strand Breaks

    PubMed Central

    Cuaron, John J.; Chang, Chang; Lovelock, Michael; Higginson, Daniel S.; Mah, Dennis; Cahlon, Oren; Powell, Simon

    2016-01-01

    Purpose To quantify the relative biological effectiveness (RBE) of the distal edge of the proton Bragg peak, using an in vitro assay of DNA double-strand breaks (DSBs). Methods and Materials U2OS cells were irradiated within the plateau of a spread-out Bragg peak and at each millimeter position along the distal edge using a custom slide holder, allowing for simultaneous measurement of physical dose. A reference radiation signal was generated using photons. The DNA DSBs at 3 hours (to assess for early damage) and at 24 hours (to assess for residual damage and repair) after irradiation were measured using the γH2AX assay and quantified via flow cytometry. Results were confirmed with clonogenic survival assays. A detailed map of the RBE as a function of depth along the Bragg peak was generated using γH2AX measurements as a biological endpoint. Results At 3 hours after irradiation, DNA DSBs were higher with protons at every point along the distal edge compared with samples irradiated with photons to similar doses. This effect was even more pronounced after 24 hours, indicating that the impact of DNA repair is less after proton irradiation relative to photons. The RBE demonstrated an exponential increase as a function of depth and was measured to be as high as 4.0 after 3 hours and as high as 6.0 after 24 hours. When the RBE-corrected dose was plotted as a function of depth, the peak effective dose was extended 2-3 mm beyond what would be expected with physical measurement. Conclusions We generated a highly comprehensive map of the RBE of the distal edge of the Bragg peak, using a direct assay of DNA DSBs in vitro. Our data show that the RBE of the distal edge increases with depth and is significantly higher than previously reported estimates. PMID:27084629

  5. The transformation dynamics towards equilibrium in non-equilibrium w/w/o double emulsions

    NASA Astrophysics Data System (ADS)

    Chao, Youchuang; Mak, Sze Yi; Shum, Ho Cheung

    2016-10-01

    We use a glass-based microfluidic device to generate non-equilibrium water-in-water-in-oil (w/w/o) double emulsions and study how they transform into equilibrium configurations. The method relies on using three immiscible liquids, with two of them from the phase-separated aqueous two-phase systems. We find that the transformation is accompanied by an expansion rim, while the characteristic transformation speed of the rim mainly depends on the interfacial tension between the innermost and middle phases, as well as the viscosity of the innermost phase when the middle phase is non-viscous. Remarkably, the viscosity of the outermost phase has little effect on the transformation speed. Our results account for the dynamics of non-equilibrium double emulsions towards their equilibrium structure and suggest a possibility to utilize the non-equilibrium drops to synthesize functional particles.

  6. Exponentiating Higgs

    NASA Astrophysics Data System (ADS)

    Matone, Marco

    2017-09-01

    We consider two related formulations for mass generation in the U (1) Higgs-Kibble model and in the Standard Model (SM). In the first formulation there are no scalar self-interactions and, in the case of the SM, the formulation is related to the normal subgroup of G = SU (3) × SU (2) × U (1), generated by (e 2 πi / 3 I , - I ,e πi / 3) ∈ G, that acts trivially on all the fields of the SM. The key step of our construction is to relax the non-negative definiteness condition for the Higgs field due to the polar decomposition. This solves several stringent problems, that we will shortly review, both at the non-perturbative and perturbative level. We will show that the usual polar decomposition of the complex scalar doublet Φ should be done with U ∈ SU (2) /Z2 ≃ SO (3), where Z2 is the group generated by -I, and with the Higgs field ϕ ∈ R rather than ϕ ∈R≥0. As a byproduct, the investigation shows how Elitzur theorem may be avoided in the usual formulation of the SM. It follows that the simplest lagrangian density for the Higgs mechanism has the standard kinetic term in addition to the mass term, with the right sign, and to a linear term in ϕ. The other model concerns the scalar theories with normal ordered exponential interactions. The remarkable property of these theories is that for D > 2 the purely scalar sector corresponds to a free theory.

  7. Task-based detectability comparison of exponential transformation of free-response operating characteristic (EFROC) curve and channelized Hotelling observer (CHO)

    NASA Astrophysics Data System (ADS)

    Khobragade, P.; Fan, Jiahua; Rupcich, Franco; Crotty, Dominic J.; Gilat Schmidt, Taly

    2016-03-01

    This study quantitatively evaluated the performance of the exponential transformation of the free-response operating characteristic curve (EFROC) metric, with the Channelized Hotelling Observer (CHO) as a reference. The CHO has been used for image quality assessment of reconstruction algorithms and imaging systems and often it is applied to study the signal-location-known cases. The CHO also requires a large set of images to estimate the covariance matrix. In terms of clinical applications, this assumption and requirement may be unrealistic. The newly developed location-unknown EFROC detectability metric is estimated from the confidence scores reported by a model observer. Unlike the CHO, EFROC does not require a channelization step and is a non-parametric detectability metric. There are few quantitative studies available on application of the EFROC metric, most of which are based on simulation data. This study investigated the EFROC metric using experimental CT data. A phantom with four low contrast objects: 3mm (14 HU), 5mm (7HU), 7mm (5 HU) and 10 mm (3 HU) was scanned at dose levels ranging from 25 mAs to 270 mAs and reconstructed using filtered backprojection. The area under the curve values for CHO (AUC) and EFROC (AFE) were plotted with respect to different dose levels. The number of images required to estimate the non-parametric AFE metric was calculated for varying tasks and found to be less than the number of images required for parametric CHO estimation. The AFE metric was found to be more sensitive to changes in dose than the CHO metric. This increased sensitivity and the assumption of unknown signal location may be useful for investigating and optimizing CT imaging methods. Future work is required to validate the AFE metric against human observers.

  8. Color image security system using double random-structured phase encoding in gyrator transform domain.

    PubMed

    Abuturab, Muhammad Rafiq

    2012-05-20

    A novel method for encoding color information based on a double random phase mask and a double structured phase mask in a gyrator transform domain is proposed. The amplitude transmittance of the Fresnel zone plate is used as structured phase-mask encoding. A color image is first segregated into red, green, and blue component images. Each of these component images are then independently encrypted using first a random phase mask placed at the image plane and transmitted through the first structured phase mask. They are then encoded by the first gyrator transform. The resulting information is again encrypted by a second random phase mask placed at the gyrator transform plane and transmitted through the second structured phase mask, and then encoded by the second gyrator transform. The system parameters of the structured phase mask and gyrator transform in each channel serve as additional encryption keys and enlarge the key space. The encryption process can be realized with an electro-optical hybrid system. The proposed system avoids problems arising from misalignment and benefits of a higher space-bandwidth product. Numerical simulations are presented to confirm the security, validity, and possibility of the proposed idea.

  9. Speech signal filtration using double-density dual-tree complex wavelet transform

    NASA Astrophysics Data System (ADS)

    Yasin, A. S.; Pavlova, O. N.; Pavlov, A. N.

    2016-08-01

    We consider the task of increasing the quality of speech signal cleaning from additive noise by means of double-density dual-tree complex wavelet transform (DDCWT) as compared to the standard method of wavelet filtration based on a multiscale analysis using discrete wavelet transform (DWT) with real basis set functions such as Daubechies wavelets. It is shown that the use of DDCWT instead of DWT provides a significant increase in the mean opinion score (MOS) rating at a high additive noise and makes it possible to reduce the number of expansion levels for the subsequent correction of wavelet coefficients.

  10. Double Langmuir frequency radiation due to transformation processes in turbulent plasma

    NASA Astrophysics Data System (ADS)

    Pavlenko, V. N.; Panchenko, V. G.; Beloshenko, N. A.

    2015-04-01

    We investigate the transformation process of longitudinal Langmuir wave into the transverse electromagnetic wave in turbulent plasma subjected to an upper hybrid pump. The case, when upper hybrid pump wave decays into daughter and ion - sound waves is considered. The transformation of the Langmuir wave into electromagnetic one is considered as the possible mechanism of energy radiation from the plasma. It is shown that the frequency of such radiation is chosen to be near double electron Langmuir frequency 2ωpe . These results give us the possibility to explain the nature of radiation from the laboratory and cosmic plasmas (particularly, from the solar crown).

  11. Homologous recombination and double-strand break repair in the transformation of Rhizopus oryzae.

    PubMed

    Skory, C D

    2002-11-01

    Genetic transformation of the Mucorales fungi has been problematic, since DNA transformed into the host rarely integrates and usually is mitotically unstable in the absence of selective pressure. In this study, transformation of Rhizopus oryzae was investigated to determine if the fate of introduced DNA could be predicted based on double-strand break repair and recombination mechanisms found in other fungi. A transformation system was developed with uracil auxotrophs of Rhizopus oryzae that could be complemented with the pyrG gene isolated in this work. DNA transformed as circular plasmids was maintained extrachromosomally in high-molecular-weight (>23 kb) concatenated arrangement. Type-I crossover integration into the pyrG locus and type-III pyrG gene replacement events occurred in approximately 1-5% of transformants. Linearization of the plasmid pPyr225 with a single restriction enzyme that cleaves within the vector sequence almost always resulted in isolates with replicating concatenated plasmids that had been repaired by end-joining recombination that restored the restriction site. The addition of a 40-bp direct repeat on either side of this cleavage site led to repair by homologous recombination between the repeated sequences on the plasmid, resulting in loss of the restriction site. When plasmid pPyr225 was digested with two different enzymes that cleave within the vector sequence to release the pyrG containing fragment, only pyrG gene replacement recombination occurred in transformants. Linearization of plasmid pPyr225 within the pyrG gene itself gave the highest percentage (20%) of type-I integration at the pyrG locus. However, end-joining repair and gene replacement events were still the predominant types of recombination found in transformations with this plasmid topology.

  12. Double Fault Detection of Cone-Shaped Redundant IMUs Using Wavelet Transformation and EPSA

    PubMed Central

    Lee, Wonhee; Park, Chan Gook

    2014-01-01

    A model-free hybrid fault diagnosis technique is proposed to improve the performance of single and double fault detection and isolation. This is a model-free hybrid method which combines the extended parity space approach (EPSA) with a multi-resolution signal decomposition by using a discrete wavelet transform (DWT). Conventional EPSA can detect and isolate single and double faults. The performance of fault detection and isolation is influenced by the relative size of noise and fault. In this paper; the DWT helps to cancel the high frequency sensor noise. The proposed technique can improve low fault detection and isolation probability by utilizing the EPSA with DWT. To verify the effectiveness of the proposed fault detection method Monte Carlo numerical simulations are performed for a redundant inertial measurement unit (RIMU). PMID:24556675

  13. Double fault detection of cone-shaped redundant IMUs using wavelet transformation and EPSA.

    PubMed

    Lee, Wonhee; Park, Chan Gook

    2014-02-19

    A model-free hybrid fault diagnosis technique is proposed to improve the performance of single and double fault detection and isolation. This is a model-free hybrid method which combines the extended parity space approach (EPSA) with a multi-resolution signal decomposition by using a discrete wavelet transform (DWT). Conventional EPSA can detect and isolate single and double faults. The performance of fault detection and isolation is influenced by the relative size of noise and fault. In this paper; the DWT helps to cancel the high frequency sensor noise. The proposed technique can improve low fault detection and isolation probability by utilizing the EPSA with DWT. To verify the effectiveness of the proposed fault detection method Monte Carlo numerical simulations are performed for a redundant inertial measurement unit (RIMU).

  14. Double-resolution electron holography with simple Fourier transform of fringe-shifted holograms.

    PubMed

    Volkov, V V; Han, M G; Zhu, Y

    2013-11-01

    We propose a fringe-shifting holographic method with an appropriate image wave recovery algorithm leading to exact solution of holographic equations. With this new method the complex object image wave recovered from holograms appears to have much less traditional artifacts caused by the autocorrelation band present practically in all Fourier transformed holograms. The new analytical solutions make possible a double-resolution electron holography free from autocorrelation band artifacts and thus push the limits for phase resolution. The new image wave recovery algorithm uses a popular Fourier solution of the side band-pass filter technique, while the fringe-shifting holographic method is simple to implement in practice.

  15. Gyrator transform based double random phase encoding with sparse representation for information authentication

    NASA Astrophysics Data System (ADS)

    Chen, Jun-xin; Zhu, Zhi-liang; Fu, Chong; Yu, Hai; Zhang, Li-bo

    2015-07-01

    Optical information security systems have drawn long-term concerns. In this paper, an optical information authentication approach using gyrator transform based double random phase encoding with sparse representation is proposed. Different from traditional optical encryption schemes, only sparse version of the ciphertext is preserved, and hence the decrypted result is completely unrecognizable and shows no similarity to the plaintext. However, we demonstrate that the noise-like decipher result can be effectively authenticated by means of optical correlation approach. Simulations prove that the proposed method is feasible and effective, and can provide additional protection for optical security systems.

  16. Image multiplexing and authentication based on double phase retrieval in fresnel transform domain

    NASA Astrophysics Data System (ADS)

    Chang, Hsuan-Ting; Lin, Che-Hsian; Chen, Chien-Yue

    2017-04-01

    An image multiplexing and authentication method based on the double-phase retrieval algorithm (DPRA) with the manipulations of wavelength and position in the Fresnel transform (FrT) domain is proposed in this study. The DPRA generates two matched phase-only functions (POFs) in the different planes so that the corresponding image can be reconstructed at the output plane. Given a number of target images, all the sets of matched POFs are used to generate the phase-locked system through the phase modulation and synthesis to achieve the multiplexing purpose. To reconstruct a target image, the corresponding phase key and all the correct parameters in the FrT are required. Therefore, the authentication system with high-level security can be achieved. The computer simulation verifies the validity of the proposed method and also shows good resistance to the crosstalk among the reconstructed images.

  17. Voice activity detection in noisy environments based on double-combined fourier transform and line fitting.

    PubMed

    Park, Jinsoo; Kim, Wooil; Han, David K; Ko, Hanseok

    2014-01-01

    A new voice activity detector for noisy environments is proposed. In conventional algorithms, the endpoint of speech is found by applying an edge detection filter that finds the abrupt changing point in a feature domain. However, since the frame energy feature is unstable in noisy environments, it is difficult to accurately find the endpoint of speech. Therefore, a novel feature extraction algorithm based on the double-combined Fourier transform and envelope line fitting is proposed. It is combined with an edge detection filter for effective detection of endpoints. Effectiveness of the proposed algorithm is evaluated and compared to other VAD algorithms using two different databases, which are AURORA 2.0 database and SITEC database. Experimental results show that the proposed algorithm performs well under a variety of noisy conditions.

  18. Optical image encryption based on a joint Fresnel transform correlator with double optical wedges.

    PubMed

    Shen, Xueju; Dou, Shuaifeng; Lei, Ming; Chen, Yudan

    2016-10-20

    An optical cryptosystem based on the joint Fresnel transform correlator (JFTC) with double optical wedges is designed. The designed cryptosystem retains the two major advantages of JTC-based optical cryptosystems. First, the encrypted image is real-valued and therefore is easier to record and transmit. Second, the encryption process is simplified, since it doesn't require accurate alignment of optical elements or the generation of the complex conjugate of the key. Also, the designed optical cryptosystem can produce a decrypted image with higher quality than a JTC-based optical cryptosystem, because the original encrypted image is divided by the Fresnel transform power distribution of the key mask to generate the new encrypted image, which significantly reduces the noise during the decryption process. Simulation results showed that the correlation coefficient of the decrypted image and the original image can reach as large as 0.9819 after denoising and adequately selecting half-central interval a and encrypted image width w. Another improvement relative to JTC-based optical cryptosystems is that the attack resistibility gets enhanced due to the nonlinearity of the encryption process as well as the additional key parameter a, which enlarges the key space.

  19. Asymmetric double-image encryption based on cascaded discrete fractional random transform and logistic maps.

    PubMed

    Sui, Liansheng; Duan, Kuaikuai; Liang, Junli; Hei, Xinhong

    2014-05-05

    A double-image encryption is proposed based on the discrete fractional random transform and logistic maps. First, an enlarged image is composited from two original images and scrambled in the confusion process which consists of a number of rounds. In each round, the pixel positions of the enlarged image are relocated by using cat maps which are generated based on two logistic maps. Then the scrambled enlarged image is decomposed into two components. Second, one of two components is directly separated into two phase masks and the other component is used to derive the ciphertext image with stationary white noise distribution by using the cascaded discrete fractional random transforms generated based on the logistic map. The cryptosystem is asymmetric and has high resistance against to the potential attacks such as chosen plaintext attack, in which the initial values of logistic maps and the fractional orders are considered as the encryption keys while two decryption keys are produced in the encryption process and directly related to the original images. Simulation results and security analysis verify the feasibility and effectiveness of the proposed encryption scheme.

  20. Double-image encryption using discrete fractional random transform and logistic maps

    NASA Astrophysics Data System (ADS)

    Sui, Liansheng; Lu, Haiwei; Wang, Zhanmin; Sun, Qindong

    2014-05-01

    A double-image encryption is proposed based on the discrete fractional random transform and logistic maps. Firstly, an enlarged image is composited from two original plaintexts, in which the pixel positions are relocated and the intensity values are changed by a chaotic confusion-diffusion process, and then two scrambled plaintexts are recovered from the enlarged image. Secondly, the two scrambled plaintexts are encoded into the phase and amplitude part of a complex function which is encrypted into a ciphertext with stationary white noise distribution by using the discrete fractional random transform generated based on logistic map. Not only the initial values of the logistic maps used in the cryptosystem but also the phase distribution produced in the encryption process can be used as private keys, which makes the proposed scheme has the characteristic of asymmetric encryption technique and high resistance against to the conventional attacks such as chosen plaintext attack, ciphertext-only attack. Simulation results and security analysis verify the feasibility and effectiveness of the proposed method.

  1. An Exceptional Exponential Function

    ERIC Educational Resources Information Center

    Curgus, Branko

    2006-01-01

    We show that there is a link between a standard calculus problem of finding the best view of a painting and special tangent lines to the graphs of exponential functions. Surprisingly, the exponential function with the "best view" is not the one with the base "e." A similar link is established for families of functions obtained by composing…

  2. How exponential are FREDs?

    NASA Astrophysics Data System (ADS)

    Schaefer, Bradley E.; Dyson, Samuel E.

    1996-08-01

    A common Gamma-Ray Burst-light curve shape is the ``FRED'' or ``fast-rise exponential-decay.'' But how exponential is the tail? Are they merely decaying with some smoothly decreasing decline rate, or is the functional form an exponential to within the uncertainties? If the shape really is an exponential, then it would be reasonable to assign some physically significant time scale to the burst. That is, there would have to be some specific mechanism that produces the characteristic decay profile. So if an exponential is found, then we will know that the decay light curve profile is governed by one mechanism (at least for simple FREDs) instead of by complex/multiple mechanisms. As such, a specific number amenable to theory can be derived for each FRED. We report on the fitting of exponentials (and two other shapes) to the tails of ten bright BATSE bursts. The BATSE trigger numbers are 105, 257, 451, 907, 1406, 1578, 1883, 1885, 1989, and 2193. Our technique was to perform a least square fit to the tail from some time after peak until the light curve approaches background. We find that most FREDs are not exponentials, although a few come close. But since the other candidate shapes come close just as often, we conclude that the FREDs are misnamed.

  3. Exponential splines: A survey

    SciTech Connect

    McCartin, B.J.

    1996-12-31

    Herein, we discuss a generalization of the semiclassical cubic spline known in the literature as the exponential spline. In actuality, the exponential spline represents a continuum of interpolants ranging from the cubic spline to the linear spline. A particular member of this family is uniquely specified by the choice of certain {open_quotes}tension{close_quotes} parameters. We first outline the theoretical underpinnings of the exponential spline. This development roughly parallels the existing theory for cubic splines. The primary extension lies in the ability of the exponential spline to preserve convexity and monotonicity present in the data. We next discuss the numerical computation of the exponential spline. A variety of numerical devices are employed to produce a stable and robust algorithm. An algorithm for the selection of tension parameters that will produce a shape preserving approximant is developed. A sequence of selected curve-fitting examples are presented which clearly demonstrate the advantages of exponential splines over cubic splines. We conclude with a consideration of the broad spectrum of possible uses of exponential splines in the applications. Our primary emphasis is on computational fluid dynamics although the imaginative reader will recognize the wider generality of the techniques developed.

  4. Retinal optical coherence tomography image enhancement via shrinkage denoising using double-density dual-tree complex wavelet transform.

    PubMed

    Chitchian, Shahab; Mayer, Markus A; Boretsky, Adam R; van Kuijk, Frederik J; Motamedi, Massoud

    2012-11-01

    ABSTRACT. Image enhancement of retinal structures, in optical coherence tomography (OCT) scans through denoising, has the potential to aid in the diagnosis of several eye diseases. In this paper, a locally adaptive denoising algorithm using double-density dual-tree complex wavelet transform, a combination of the double-density wavelet transform and the dual-tree complex wavelet transform, is applied to reduce speckle noise in OCT images of the retina. The algorithm overcomes the limitations of commonly used multiple frame averaging technique, namely the limited number of frames that can be recorded due to eye movements, by providing a comparable image quality in significantly less acquisition time equal to an order of magnitude less time compared to the averaging method. In addition, improvements of image quality metrics and 5 dB increase in the signal-to-noise ratio are attained.

  5. Retinal optical coherence tomography image enhancement via shrinkage denoising using double-density dual-tree complex wavelet transform

    PubMed Central

    Mayer, Markus A.; Boretsky, Adam R.; van Kuijk, Frederik J.; Motamedi, Massoud

    2012-01-01

    Abstract. Image enhancement of retinal structures, in optical coherence tomography (OCT) scans through denoising, has the potential to aid in the diagnosis of several eye diseases. In this paper, a locally adaptive denoising algorithm using double-density dual-tree complex wavelet transform, a combination of the double-density wavelet transform and the dual-tree complex wavelet transform, is applied to reduce speckle noise in OCT images of the retina. The algorithm overcomes the limitations of commonly used multiple frame averaging technique, namely the limited number of frames that can be recorded due to eye movements, by providing a comparable image quality in significantly less acquisition time equal to an order of magnitude less time compared to the averaging method. In addition, improvements of image quality metrics and 5 dB increase in the signal-to-noise ratio are attained. PMID:23117804

  6. An Unusual Exponential Graph

    ERIC Educational Resources Information Center

    Syed, M. Qasim; Lovatt, Ian

    2014-01-01

    This paper is an addition to the series of papers on the exponential function begun by Albert Bartlett. In particular, we ask how the graph of the exponential function y = e[superscript -t/t] would appear if y were plotted versus ln t rather than the normal practice of plotting ln y versus t. In answering this question, we find a new way to…

  7. An Unusual Exponential Graph

    ERIC Educational Resources Information Center

    Syed, M. Qasim; Lovatt, Ian

    2014-01-01

    This paper is an addition to the series of papers on the exponential function begun by Albert Bartlett. In particular, we ask how the graph of the exponential function y = e[superscript -t/t] would appear if y were plotted versus ln t rather than the normal practice of plotting ln y versus t. In answering this question, we find a new way to…

  8. Morphometric and biochemical characterization of red beet (Beta vulgaris L.) hairy roots obtained after single and double transformations.

    PubMed

    Thimmaraju, R; Venkatachalam, L; Bhagyalakshmi, N

    2008-06-01

    It is known that T-DNA of Agrobacterium rhizogenes affects processes of plant development and activates the synthesis of secondary metabolites in transformed plant cells. In the present investigation, we provide evidence that different strains of A. rhizogenes significantly affect morphometric, morphological and functional characteristics of hairy roots of red beet (Beta vulgaris L.). Infection with four strains of A. rhizogenes (A4, A 2/83, A 20/83 and LMG-150) resulted in ten clones of hairy roots, which were named accordingly as A4(1), A4(2), A4(3), A 2/83(1), A 2/83(2), A 2/83(3), A 20/83(1), A 20/83(2), A 20/83(3) and LMG-150. Their growth characteristics, pigment content, levels of endogenous auxin and T-DNA copy number showed significant differences probably due to the physiological status of the host cell rather than the T-DNA copy number. Although A 2/83 showed highest hairy root induction capacity, the best hairy root clone was obtained with strain LMG-150 that produced highest biomass and pigments. In this root clone, the enzyme peroxidase was found involved in altering the endogenous auxin pool. When root clone LMG-150 was re-transformed to insert additional individual rol genes, two double transformed clones were obtained, one for rolABC and the other for rolC gene where the former produced higher biomass and betalaine than the latter. Despite the established fact that rol genes of T-DNA influence endogenous phytohormones, no direct correlation among the single transformants and the double transformants was found. This is the first report, in our knowledge, where a hairy root clone has been used to obtain double transformants.

  9. Cooperation of Gata3, c-Myc and Notch in malignant transformation of double positive thymocytes.

    PubMed

    van Hamburg, Jan Piet; de Bruijn, Marjolein J W; Dingjan, Gemma M; Beverloo, H Berna; Diepstraten, Hans; Ling, Kam-Wing; Hendriks, Rudi W

    2008-06-01

    Gata transcription factors are critical regulators of proliferation and differentiation implicated in various human cancers, but specific genes activated by Gata proteins remain to be identified. We previously reported that enforced expression of Gata3 during T cell development in CD2-Gata3 transgenic mice induced CD4(+)CD8(+) double-positive (DP) T cell lymphoma. Here, we show that the presence of the DO11.10 T-cell receptor transgene, which directs DP cells towards the CD4 lineage, resulted in enhanced lymphoma development and a dramatic increase in thymocyte cell size in CD2-Gata3 transgenic mice. CD2-Gata3 DP cells expressed high levels of the proto-oncogene c-Myc but the Notch1 signaling pathway, which is known to induce c-Myc, was not activated. Gene expression profiling showed that in CD2-Gata3 lymphoma cells transcription of c-Myc and its target genes was further increased. A substantial fraction of CD2-Gata3 lymphomas had trisomy of chromosome 15, leading to an increased c-Myc gene dose. Interestingly, most lymphomas showed high expression of the Notch targets Deltex1 and Hes1, often due to activating Notch1 PEST domain mutations. Therefore, we conclude that enforced Gata3 expression converts DP thymocytes into a pre-malignant state, characterized by high c-Myc expression, whereby subsequent induction of Notch1 signaling cooperates to establish malignant transformation. The finding that Gata3 regulates c-Myc expression levels, in a direct or indirect fashion, may explain the parallel phenotypes of mice with overexpression or deficiency of either of the two transcription factors.

  10. Composition driven monolayer to bilayer transformation in a surfactant intercalated Mg-Al layered double hydroxide.

    PubMed

    Naik, Vikrant V; Chalasani, Rajesh; Vasudevan, S

    2011-03-15

    The structure and organization of dodecyl sulfate (DDS) surfactant chains intercalated in an Mg-Al layered double hydroxide (LDH), Mg(1-x)Alx(OH)2, with differing Al/Mg ratios has been investigated. The Mg-Al LDHs can be prepared over a range of compositions with x varying from 0.167 to 0.37 and therefore provides a simple system to study how the organization of the alkyl chains of the intercalated DDS anions change with packing density; the Al/Mg ratio or x providing a convenient handle to do so. Powder X-ray diffraction measurements showed that at high packing densities (x ≥ 0.3) the alkyl chains of the intercalated dodecyl sulfate ions are anchored on opposing LDH sheets and arranged as bilayers with an interlayer spacing of ∼27 Å. At lower packing densities (x < 0.2) the surfactant chains form a monolayer with the alkyl chains oriented flat in the galleries with an interlayer spacing of ∼8 Å. For the in between compositions, 0.2 ≤ x < 0.3, the material is biphasic. MD simulations were performed to understand how the anchoring density of the intercalated surfactant chains in the Mg-Al LDH-DDS affects the organization of the chains and the interlayer spacing. The simulations are able to reproduce the composition driven monolayer to bilayer transformation in the arrangement of the intercalated surfactant chains and in addition provide insights into the factors that decide the arrangement of the surfactant chains in the two situations. In the bilayer arrangement, it is the dispersive van der Waals interactions between chains in opposing layers of the anchored bilayer that is responsible for the cohesive energy of the solid whereas at lower packing densities, where a monolayer arrangement is favored, Coulomb interactions between the positively charged Mg-Al LDH sheets and the negatively charged headgroup of the DDS anion dominate.

  11. Exponentially fitted symplectic integrator

    NASA Astrophysics Data System (ADS)

    Simos, T. E.; Vigo-Aguiar, Jesus

    2003-01-01

    In this paper a procedure for constructing efficient symplectic integrators for Hamiltonian problems is introduced. This procedure is based on the combination of the exponential fitting technique and symplecticness conditions. Based on this procedure, a simple modified Runge-Kutta-Nyström second-order algebraic exponentially fitted method is developed. We give explicitly the symplecticness conditions for the modified Runge-Kutta-Nyström method. We also give the exponential fitting and trigonometric fitting conditions. Numerical results indicate that the present method is much more efficient than the “classical” symplectic Runge-Kutta-Nyström second-order algebraic method introduced by M.P. Calvo and J.M. Sanz-Serna [J. Sci. Comput. (USA) 14, 1237 (1993)]. We note that the present procedure is appropriate for all near-unimodal systems.

  12. Double-image encryption using chaotic maps and nonlinear non-DC joint fractional Fourier transform correlator

    NASA Astrophysics Data System (ADS)

    Zhao, Hongjie; Zhong, Zhi; Fang, Weiwei; Xie, Hong; Zhang, Yabin; Shan, Mingguang

    2016-09-01

    A double-image encryption method is reported using chaotic maps, nonlinear non-DC joint transform correlator (JTC), and fractional Fourier transform (FrFT). The double images are converted into the amplitude and phase of a synthesized function through the application of chaotic pixel scrambling. The synthesized function bonded with a chaotic random phase mask (CRPM) and another different CRPM serve as the input signal of the JTC architecture in the fractional Fourier domain to obtain a real-valued encrypted image. The nonlinear and non-DC operation is also done to improve the security and decrypted image quality. The parameters in joint FrFT correlator and chaotic map serve as the encrypted keys. Numerical simulations have been done to demonstrate the feasibility and validity of this algorithm.

  13. Exponential Localization of Photons

    NASA Astrophysics Data System (ADS)

    Bialynicki-Birula, Iwo

    1998-06-01

    It is shown that photons can be localized in space with an exponential falloff of the energy density and photodetection rates. The limits of localization are determined by the fundamental Paley-Wiener theorem. A direct mathematical connection between the spatial localization of photons and the decay in time of quantum mechanical systems is established.

  14. Exponential examples of solving parity games

    NASA Astrophysics Data System (ADS)

    Lebedev, V. N.

    2016-04-01

    This paper is devoted to solving certain problems on the computational complexity of deciding the winner in cyclic games. The main result is the proof of the fact that the nondeterministic potential transformation algorithm designed for solving parity games is exponential in terms of computation time.

  15. Double exponential I-V characteristics and double Gaussian distribution of barrier heights in (Au/Ti)/Al2O3/ n-GaAs (MIS)-type Schottky barrier diodes in wide temperature range

    NASA Astrophysics Data System (ADS)

    Güçlü, Çiğdem Ş.; Özdemir, Ahmet Faruk; Altindal, Şemsettin

    2016-12-01

    In this study, current conduction mechanisms of the sample (Au/Ti)/Al2O3/ n-GaAs were investigated in detail using current-voltage (I-V) measurements in the temperature range of 80-380 K. The semilogarithmic I-V plots reveal two distinct linear regions with different slopes between 0.07-0.30 and 0.30-0.69 V which are called as Region I (RI) and Region II (RII), respectively. The ideality factor ( n) and zero-bias barrier height (Φ_{{bo}}) were found to be strong functions of temperature and voltage. In both regions, as the temperature increases, Φ_{{bo}} increases, whereas the value of n decreases. The high value of n at low temperatures is an evidence of deviation from thermionic emission, and it cannot be explained solely by tunneling mechanism, the existence of surface states and interfacial layer. Therefore, the Φ_{{bo}} versus q/kT plots were drawn for two linear regions of lnI-V plots, and these plots also revealed two distinct linear regions with different slopes between two temperature regions of 80-170 and 200-380 K which are called as low- and high-temperature range (LTR and HTR), respectively. Such behavior of these plots confirmed the existence of double Gaussian distribution (DGD) in the samples which in turn has mean barrier heights bar{Φ}_{{bo}} and standard deviations ( σ s). These values were obtained from the intercept and slope of these plots as 0.38 eV and 0.061 V for LTR and as 0.88 eV and 0.142 V for HTR (in RI), whereas they were obtained as 0.37 eV and 0.061 V for LTR and as 0.92 eV and 0.148 V for HTR (in RII), respectively. Thus, the modified ln( I s/ T 2)- q 2 σ s 2 /2 k 2 T 2 versus q/ kT plots were drawn, and the values of (bar{Φ}_{{bo}}) and effective Richardson constant ( A *) were extracted from the intercept and slope of these plots as 0.39 eV and 7.07 A/cm2 K2 for LTR and as 0.92 eV and 8.158 A/cm2 K2 for HTR (in RI), whereas they were extracted as 0.38 eV and 7.92 A/cm2 K2 for LTR and as 0.94 eV and 4.66 A/cm2 K2 for HTR

  16. Formation and transformation of metastable double salts from the crystallization of mixed ammonium nitrate and ammonium sulfate particles.

    PubMed

    Ling, Tsz Yan; Chan, Chak K

    2007-12-01

    Ammonium nitrate (AN) and ammonium sulfate (AS) are ubiquitous components of atmospheric aerosols. Thermodynamic models predict formation of pure (AN and AS) and double salts (3AN. AS and 2AN. AS) for the AN/AS system. Because of the high supersaturation at which a droplet crystallizes, metastable crystal formation is possible. In this study, the identity of the crystals formed from the crystallization of equimolar AN/AS mixed droplets was investigated in an electrodynamic balance coupled with a Raman spectroscopic system. Raman spectra of bulk AN/AS double salts possibly formed in this system are first reported for comparison with the single particle Raman results. The double-salt 3AN. AS, not predicted from thermodynamics, was observed in the freshly crystallized single particles. The degree of metastability can be different among several crystallization processes of the same particles. The metastable salt 3AN. AS gradually transformed into stable 2AN. AS, and the rate of such transformation increased with increasing relative humidity. This study illustrates the possibility of occurrence of metastable salts in atmospheric aerosols.

  17. Transformation between surface spherical harmonic expansion of arbitrary high degree and order and double Fourier series on sphere

    NASA Astrophysics Data System (ADS)

    Fukushima, Toshio

    2017-07-01

    In order to accelerate the spherical harmonic synthesis and/or analysis of arbitrary function on the unit sphere, we developed a pair of procedures to transform between a truncated spherical harmonic expansion and the corresponding two-dimensional Fourier series. First, we obtained an analytic expression of the sine/cosine series coefficient of the 4 π fully normalized associated Legendre function in terms of the rectangle values of the Wigner d function. Then, we elaborated the existing method to transform the coefficients of the surface spherical harmonic expansion to those of the double Fourier series so as to be capable with arbitrary high degree and order. Next, we created a new method to transform inversely a given double Fourier series to the corresponding surface spherical harmonic expansion. The key of the new method is a couple of new recurrence formulas to compute the inverse transformation coefficients: a decreasing-order, fixed-degree, and fixed-wavenumber three-term formula for general terms, and an increasing-degree-and-order and fixed-wavenumber two-term formula for diagonal terms. Meanwhile, the two seed values are analytically prepared. Both of the forward and inverse transformation procedures are confirmed to be sufficiently accurate and applicable to an extremely high degree/order/wavenumber as 2^{30} {≈ } 10^9 . The developed procedures will be useful not only in the synthesis and analysis of the spherical harmonic expansion of arbitrary high degree and order, but also in the evaluation of the derivatives and integrals of the spherical harmonic expansion.

  18. Double images hiding by using joint transform correlator architecture adopting two-step phase-shifting digital holography

    NASA Astrophysics Data System (ADS)

    Shi, Xiaoyan; Zhao, Daomu; Huang, Yinbo

    2013-06-01

    Based on the joint Fresnel transform correlator, a new system for double images hiding is presented. By this security system, the dual secret images are encrypted and recorded as intensity patterns employing phase-shifting interference technology. To improve the system security, a dual images hiding method is used. By digital means, the deduced encryption complex distribution is divided into two subparts. For each image, only one subpart is reserved and modulated by a phase factor. Then these modified results are combined together and embedded into the host image. With all correct keys, by inverse Fresnel transform, the secret images can be extracted. By the phase modulation, the cross talk caused by images superposition can be reduced for their spatial parallel separation. Theoretical analyses have shown the system's feasibility. Computer simulations are performed to show the encryption capacity of the proposed system. Numerical results are presented to verify the validity and the efficiency of the proposed method.

  19. Exponentiated power Lindley distribution

    PubMed Central

    Ashour, Samir K.; Eltehiwy, Mahmoud A.

    2014-01-01

    A new generalization of the Lindley distribution is recently proposed by Ghitany et al. [1], called as the power Lindley distribution. Another generalization of the Lindley distribution was introduced by Nadarajah et al. [2], named as the generalized Lindley distribution. This paper proposes a more generalization of the Lindley distribution which generalizes the two. We refer to this new generalization as the exponentiated power Lindley distribution. The new distribution is important since it contains as special sub-models some widely well-known distributions in addition to the above two models, such as the Lindley distribution among many others. It also provides more flexibility to analyze complex real data sets. We study some statistical properties for the new distribution. We discuss maximum likelihood estimation of the distribution parameters. Least square estimation is used to evaluate the parameters. Three algorithms are proposed for generating random data from the proposed distribution. An application of the model to a real data set is analyzed using the new distribution, which shows that the exponentiated power Lindley distribution can be used quite effectively in analyzing real lifetime data. PMID:26644927

  20. Exponentiated power Lindley distribution.

    PubMed

    Ashour, Samir K; Eltehiwy, Mahmoud A

    2015-11-01

    A new generalization of the Lindley distribution is recently proposed by Ghitany et al. [1], called as the power Lindley distribution. Another generalization of the Lindley distribution was introduced by Nadarajah et al. [2], named as the generalized Lindley distribution. This paper proposes a more generalization of the Lindley distribution which generalizes the two. We refer to this new generalization as the exponentiated power Lindley distribution. The new distribution is important since it contains as special sub-models some widely well-known distributions in addition to the above two models, such as the Lindley distribution among many others. It also provides more flexibility to analyze complex real data sets. We study some statistical properties for the new distribution. We discuss maximum likelihood estimation of the distribution parameters. Least square estimation is used to evaluate the parameters. Three algorithms are proposed for generating random data from the proposed distribution. An application of the model to a real data set is analyzed using the new distribution, which shows that the exponentiated power Lindley distribution can be used quite effectively in analyzing real lifetime data.

  1. Noise in Exponential Growth

    NASA Astrophysics Data System (ADS)

    Iyer-Biswas, Srividya; Wright, Charles; Henry, Jon; Burov, Stas; Lin, Yihan; Crosson, Sean; Dinner, Aaron; Scherer, Norbert

    2013-03-01

    The interplay between growth and division of cells is has been studied in the context of exponential growth of bacterial cells (in suitable conditions) for decades. However, bulk culture studies obscure phenomena that manifest in single cells over many generations. We introduce a unique technology combining microfluidics, single-cell imaging, and quantitative analysis. This enables us to track the growth of single Caulobacter crescentus stalked cells over hundreds of generations. The statistics that we extract indicate a size thresholding mechanism for cell division and a non-trivial scaling collapse of division time distributions at different temperatures. In this talk I shall discuss these observations and a stochastic model of growth and division that captures all our observations with no free parameters.

  2. Comment on: Novel image encryption/decryption based on quantum fourier transform and double phase encoding

    NASA Astrophysics Data System (ADS)

    Song, Xian-Hua; Niu, Xia-Mu

    2014-06-01

    In this letter, we have pointed out some problems existed in (Yang et al. in Quantum Inf Process 12(11):3477-3493, 2013). Then, a new restricted quantum image color transformation method is proposed.

  3. Forecasting exponential growth and exponential decline: similarities and differences.

    PubMed

    Ebersbach, Mirjam; Lehner, Mirjam; Resing, Wilma C M; Wilkening, Friedrich

    2008-02-01

    Previous research has demonstrated adults' difficulties with explicitly forecasting exponential processes. Exponential growth is usually grossly underestimated, whereas exponential decline is forecast more accurately. By contrast, the present study examined implicit knowledge about exponential processes and how it is affected by function type (growth versus decline) in samples of 7-, 10-, 14-year-olds, and adults (N=80). Different indicators of the quality of forecasts were investigated. As opposed to previous findings, participants of all age groups estimated exponential decline less adequately than exponential growth. This effect could be attributed mainly to the fact that, in relation to fitted exponential functions, the starting value, or intercept, of the function was approximated well for exponential growth but badly with regard to exponential decline. The accuracy of the non-linear component in forecast functions barely differed between function types within the same age group. Furthermore, even 7-year-olds appeared to have a preliminary understanding of exponential processes, while both intercepts and exponents of forecasts became more accurate with age. Theoretical and practical implications are discussed.

  4. Ultra-Wideband Indoor Double-Directional Channel Estimation Using Transformation between Frequency and Time Domain Signals

    NASA Astrophysics Data System (ADS)

    Iwakiri, Naohiko; Kobayashi, Takehiko

    This paper proposes an ultra-wideband double-directional spatio-temporal channel sounding technique using transformation between frequency- and time-domain (FD and TD) signals. Virtual antenna arrays, composed of omnidirectional antennas and scanners, are used for transmission and reception in the FD. After Fourier transforming the received FD signals to TD ones, time of arrival (TOA) is estimated using a peak search over the TD signals, and then angle of arrivals (AOA) and angle of departure (AOD) are estimated using a weighted angle histogram with a multiple signal classification (MUSIC) algorithm applied to the FD signals, inverse-Fourier transformed from the TD signals divided into subregions. Indoor channel sounding results validated that an appropriate weighting reduced a spurious level in the angle histogram by a factor of 0.1 to 0.2 in comparison with that of non-weighting. The proposed technique successfully resolved dominant multipath components, including a direct path, a single reflection, and a single diffraction, in line-of-sight (LOS) and non-LOS environments. Joint TOA and AOA/AOD spectra were also derived from the sounding signals. The spectra illustrated the dominant multipath components (agreed with the prediction by ray tracing) as clusters.

  5. K300 Fourier transform spectrometer: environmental applications of the double-pendulum interferometer

    NASA Astrophysics Data System (ADS)

    Bittner, Hermann; Erhard, Markus; Neureither, I.; Mosebach, Herbert W.; Rippel, Harald

    1992-03-01

    The described double pendulum interferometer is a newly designed FTIR spectrometer based on the Michelson interferometer type. The unique optical layout allows a compact design in spite of high resolution and offers a very high stability. The presented device K300 is constructed as a stable instrument for field measurements. Apart from absorption measurements of trace gases, an innovation in the field of environmental measurements is the monitoring of smoke stack pollution by remote sensing. First results of emission as well as absorption measurements are presented.

  6. Test Exponential Pile

    NASA Astrophysics Data System (ADS)

    Fermi, Enrico

    The Patent contains an extremely detailed description of an atomic pile employing natural uranium as fissile material and graphite as moderator. It starts with the discussion of the theory of the intervening phenomena, in particular the evaluation of the reproduction or multiplication factor, K, that is the ratio of the number of fast neutrons produced in one generation by the fissions to the original number of fast neutrons, in a system of infinite size. The possibility of having a self-maintaining chain reaction in a system of finite size depends both on the facts that K is greater than unity and the overall size of the system is sufficiently large to minimize the percentage of neutrons escaping from the system. After the description of a possible realization of such a pile (with many detailed drawings), the various kinds of neutron losses in a pile are depicted. Particularly relevant is the reported "invention" of the exponential experiment: since theoretical calculations can determine whether or not a chain reaction will occur in a give system, but can be invalidated by uncertainties in the parameters of the problem, an experimental test of the pile is proposed, aimed at ascertaining if the pile under construction would be divergent (i.e. with a neutron multiplication factor K greater than 1) by making measurements on a smaller pile. The idea is to measure, by a detector containing an indium foil, the exponential decrease of the neutron density along the length of a column of uranium-graphite lattice, where a neutron source is placed near its base. Such an exponential decrease is greater or less than that expected due to leakage, according to whether the K factor is less or greater than 1, so that this experiment is able to test the criticality of the pile, its accuracy increasing with the size of the column. In order to perform this measure a mathematical description of the effect of neutron production, diffusion, and absorption on the neutron density in the

  7. Exponential lifetime improvement in topological quantum memories

    NASA Astrophysics Data System (ADS)

    Bardyn, Charles-Edouard; Karzig, Torsten

    2016-09-01

    We propose a simple yet efficient mechanism for passive error correction in topological quantum memories. Our scheme relies on driven-dissipative ancilla systems which couple to local excitations (anyons) and make them "sink" in energy, with no required interaction among ancillae or anyons. Through this process, anyons created by some thermal environment end up trapped in potential "trenches" that they themselves generate, which can be interpreted as a "memory foam" for anyons. This self-trapping mechanism provides an energy barrier for anyon propagation and removes entropy from the memory by favoring anyon recombination over anyon separation (responsible for memory errors). We demonstrate that our scheme leads to an exponential increase of the memory-coherence time with system size L , up to an upper bound Lmax, which can increase exponentially with Δ /T , where T is the temperature and Δ is some energy scale defined by potential trenches. This results in a double exponential increase of the memory time with Δ /T , which greatly improves over the Arrhenius (single-exponential) scaling found in typical quantum memories.

  8. TRANSFORMATION

    SciTech Connect

    LACKS,S.A.

    2003-10-09

    Transformation, which alters the genetic makeup of an individual, is a concept that intrigues the human imagination. In Streptococcus pneumoniae such transformation was first demonstrated. Perhaps our fascination with genetics derived from our ancestors observing their own progeny, with its retention and assortment of parental traits, but such interest must have been accelerated after the dawn of agriculture. It was in pea plants that Gregor Mendel in the late 1800s examined inherited traits and found them to be determined by physical elements, or genes, passed from parents to progeny. In our day, the material basis of these genetic determinants was revealed to be DNA by the lowly bacteria, in particular, the pneumococcus. For this species, transformation by free DNA is a sexual process that enables cells to sport new combinations of genes and traits. Genetic transformation of the type found in S. pneumoniae occurs naturally in many species of bacteria (70), but, initially only a few other transformable species were found, namely, Haemophilus influenzae, Neisseria meningitides, Neisseria gonorrheae, and Bacillus subtilis (96). Natural transformation, which requires a set of genes evolved for the purpose, contrasts with artificial transformation, which is accomplished by shocking cells either electrically, as in electroporation, or by ionic and temperature shifts. Although such artificial treatments can introduce very small amounts of DNA into virtually any type of cell, the amounts introduced by natural transformation are a million-fold greater, and S. pneumoniae can take up as much as 10% of its cellular DNA content (40).

  9. OPINION: Safe exponential manufacturing

    NASA Astrophysics Data System (ADS)

    Phoenix, Chris; Drexler, Eric

    2004-08-01

    In 1959, Richard Feynman pointed out that nanometre-scale machines could be built and operated, and that the precision inherent in molecular construction would make it easy to build multiple identical copies. This raised the possibility of exponential manufacturing, in which production systems could rapidly and cheaply increase their productive capacity, which in turn suggested the possibility of destructive runaway self-replication. Early proposals for artificial nanomachinery focused on small self-replicating machines, discussing their potential productivity and their potential destructiveness if abused. In the light of controversy regarding scenarios based on runaway replication (so-called 'grey goo'), a review of current thinking regarding nanotechnology-based manufacturing is in order. Nanotechnology-based fabrication can be thoroughly non-biological and inherently safe: such systems need have no ability to move about, use natural resources, or undergo incremental mutation. Moreover, self-replication is unnecessary: the development and use of highly productive systems of nanomachinery (nanofactories) need not involve the construction of autonomous self-replicating nanomachines. Accordingly, the construction of anything resembling a dangerous self-replicating nanomachine can and should be prohibited. Although advanced nanotechnologies could (with great difficulty and little incentive) be used to build such devices, other concerns present greater problems. Since weapon systems will be both easier to build and more likely to draw investment, the potential for dangerous systems is best considered in the context of military competition and arms control.

  10. Double image encryption based on phase-amplitude mixed encoding and multistage phase encoding in gyrator transform domains

    NASA Astrophysics Data System (ADS)

    Wang, Qu; Guo, Qing; Lei, Liang

    2013-06-01

    We present a novel method for double image encryption that is based on amplitude-phase mixed encoding and multistage random phase encoding in gyrator transform (GT) domains. In the amplitude-phase mixed encoding operation, a random binary distribution matrix is defined to mixed encode two primitive images to a single complex-valued image, which is then encrypted into a stationary white noise distribution by the multistage phase encoding with GTs. Compared with the earlier methods that uses fully phase encoding, the proposed method reduces the difference between two primitive images in key space and sensitivity to the GT orders. The primitive images can be recovered exactly by applying correct keys with initial conditions of chaotic system, the GT orders and the pixel scrambling operation. Numerical simulations demonstrate that the proposed scheme has considerably high security level and certain robustness against data loss and noise disturbance.

  11. TRANSFORMER

    DOEpatents

    Baker, W.R.

    1959-08-25

    Transformers of a type adapted for use with extreme high power vacuum tubes where current requirements may be of the order of 2,000 to 200,000 amperes are described. The transformer casing has the form of a re-entrant section being extended through an opening in one end of the cylinder to form a coaxial terminal arrangement. A toroidal multi-turn primary winding is disposed within the casing in coaxial relationship therein. In a second embodiment, means are provided for forming the casing as a multi-turn secondary. The transformer is characterized by minimized resistance heating, minimized external magnetic flux, and an economical construction.

  12. DFT-Based Simulation and Experimental Validation of the Topotactic Transformation of MgAl Layered Double Hydroxides.

    PubMed

    Zhang, Shi-Tong; Dou, Yibo; Zhou, Junyao; Pu, Min; Yan, Hong; Wei, Min; Evans, David G; Duan, Xue

    2016-09-05

    The thermal topotactic transformation mechanism of MgAl layered double hydroxides (LDHs) is investigated by a combined theoretical and experimental study. Thermogravimetric differential thermal analysis (TG-DTA) results reveal that the LDH phase undergoes four key endothermic events at 230, 330, 450, and 800 °C. DFT calculations show that the LDH decomposes into CO2 and residual O atoms via a monodentate intermediate at 330 °C. At 450 °C, the metal cations almost maintain their original distribution within the LDH(001) facet during the thermal dehydration process, but migrate substantially along the c-axis direction perpendicular to the (001) facet; this indicates that the metal arrangement/dispersion in the LDH matrix is maintained two-dimensionally. A complete collapse of the layered structure occurs at 800 °C, which results in a totally disordered cation distribution and many holes in the final product. The structures of the simulated intermediates are highly consistent with the observed in situ powder XRD data for the MgAl LDH sample calcined at the corresponding temperatures. Understanding the structural topotactic transformation process of LDHs would provide helpful information for the design and preparation of metal/metal oxides functional materials derived from LDH precursors.

  13. In Situ Transformation of MOFs into Layered Double Hydroxide Embedded Metal Sulfides for Improved Electrocatalytic and Supercapacitive Performance.

    PubMed

    Yilmaz, Gamze; Yam, Kah Meng; Zhang, Chun; Fan, Hong Jin; Ho, Ghim Wei

    2017-07-01

    Direct adoption of metal-organic frameworks (MOFs) as electrode materials shows impoverished electrochemical performance owing to low electrical conductivity and poor chemical stability. In this study, we demonstrate self-templated pseudomorphic transformation of MOF into surface chemistry rich hollow framework that delivers highly reactive, durable, and universal electrochemically active energy conversion and storage functionalities. In situ pseudomorphic transformation of MOF-derived hollow rhombic dodecahedron template and sulfurization of nickel cobalt layered double hydroxides (NiCo-LDHs) lead to the construction of interlayered metal sulfides (NiCo-LDH/Co9 S8 ) system. The embedment of metal sulfide species (Co9 S8 ) at the LDH intergalleries offers optimal interfacing of the hybrid constituent elements and materials stability. The hybrid NiCo-LDH/Co9 S8 system collectively presents an ideal porous structure, rich redox chemistry, and high electrical conductivity matrix. This leads to a significant enhancement in its complementary electrocatalytic hydrogen evolution and supercapacitive energy storage properties. This work establishes the potential of MOF derived scaffold for designing of novel class hybrid inorganic-organic functional materials for electrochemical applications and beyond. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. On the Matrix Exponential Function

    ERIC Educational Resources Information Center

    Hou, Shui-Hung; Hou, Edwin; Pang, Wan-Kai

    2006-01-01

    A novel and simple formula for computing the matrix exponential function is presented. Specifically, it can be used to derive explicit formulas for the matrix exponential of a general matrix A satisfying p(A) = 0 for a polynomial p(s). It is ready for use in a classroom and suitable for both hand as well as symbolic computation.

  15. On the Matrix Exponential Function

    ERIC Educational Resources Information Center

    Hou, Shui-Hung; Hou, Edwin; Pang, Wan-Kai

    2006-01-01

    A novel and simple formula for computing the matrix exponential function is presented. Specifically, it can be used to derive explicit formulas for the matrix exponential of a general matrix A satisfying p(A) = 0 for a polynomial p(s). It is ready for use in a classroom and suitable for both hand as well as symbolic computation.

  16. Digital signal processing for step-scan phase and electrochemical potential double-modulation Fourier transform infrared spectrometry.

    PubMed

    Brevnov, Dmitri A; Hutter, Eliza; Fendler, Janos H

    2004-02-01

    Step-scan double-modulation (phase and electrochemical potential) Fourier transform infrared (FT-IR) spectrometry provides both spectroscopic and dynamic information about faradaic reactions. Recently introduced digital signal processing (DSP) can be used, instead of two lock-in amplifiers, for the optical signal demodulation at two modulation frequencies. In order to establish the merits of double-modulation FT-IR spectrometry with DSP, spectro-electrochemical experiments are performed in the attenuated total reflection configuration and with the commonly used ferri/ferrocyanide redox couple. Because of a large potential drop associated with the uncompensated resistance, a satisfactory signal-to-noise ratio for the alternating current (ac) optical measurements is obtained only with the employment of positive feedback compensation. In this arrangement, the amplitude of electrochemical modulation is sufficiently large to convert a significant fraction of the reduced form to the oxidized form and back to the reduced form. Large amplitude ac voltammetry demonstrates that the phase of faradaic admittance at the formal potential is approximately 45 degrees at 2.00 Hz. In addition, these experiments allow for calculation of the interfacial ac potential. This variable is needed for the normalization of the in-phase and the quadrature spectra in order to overcome the problem associated with the iR(u) drop. Because of the integral relationship between the faradaic current and the electromodulation reflectance coefficient, the phases of electromodulation reflectance coefficient with respect to the interfacial ac potential are expected to be -45 degrees and 135 degrees for the reduced and oxidized forms, respectively. However, dynamic information from double-modulation FT-IR spectrometry is available only if demodulation at the electrochemical potential modulation frequency is performed with respect to a defined phase. Because of an undefined demodulation phase implemented in

  17. Exponential Boundary Observers for Pressurized Water Pipe

    NASA Astrophysics Data System (ADS)

    Hermine Som, Idellette Judith; Cocquempot, Vincent; Aitouche, Abdel

    2015-11-01

    This paper deals with state estimation on a pressurized water pipe modeled by nonlinear coupled distributed hyperbolic equations for non-conservative laws with three known boundary measures. Our objective is to estimate the fourth boundary variable, which will be useful for leakage detection. Two approaches are studied. Firstly, the distributed hyperbolic equations are discretized through a finite-difference scheme. By using the Lipschitz property of the nonlinear term and a Lyapunov function, the exponential stability of the estimation error is proven by solving Linear Matrix Inequalities (LMIs). Secondly, the distributed hyperbolic system is preserved for state estimation. After state transformations, a Luenberger-like PDE boundary observer based on backstepping mathematical tools is proposed. An exponential Lyapunov function is used to prove the stability of the resulted estimation error. The performance of the two observers are shown on a water pipe prototype simulated example.

  18. Double-stranded RNA-mediated interference of dumpy genes in Bursaphelenchus xylophilus by feeding on filamentous fungal transformants.

    PubMed

    Wang, Meng; Wang, Diandong; Zhang, Xi; Wang, Xu; Liu, Wencui; Hou, Xiaomeng; Huang, Xiaoyin; Xie, Bingyan; Cheng, Xinyue

    2016-05-01

    RNA interference (RNAi) is a valuable tool for studying gene function in vivo and provides a functional genomics platform in a wide variety of organisms. The pinewood nematode, Bursaphelenchus xylophilus, is a prominent invasive plant-parasitic nematode and has become a serious worldwide threat to forest ecosystems. Presently, the complete genome sequence of B. xylophilus has been published, and research involving genome-wide functional analyses is likely to increase. In this study, we describe the construction of an effective silencing vector, pDH-RH, which contains a transcriptional unit for a hairpin loop structure. Utilising this vector, double-stranded (ds)RNAs with sequences homologous to the target genes can be expressed in a transformed filamentous fungus via Agrobacterium tumefaciens-mediated transformation technology, and can subsequently induce the knockdown of target gene mRNA expression in B. xylophilus by allowing the nematode to feed on the fungal transformants. Four dumpy genes (Bx-dpy-2, 4, 10 and 11) were used as targets to detect RNAi efficiency. By allowing the nematode to feed on target gene-transformed Fusarium oxysporum strains, target transcripts were knocked down 34-87% compared with those feeding on the wild-type strain as determined by real-time quantitative PCR (RT-qPCR). Morphological RNAi phenotypes were observed, displaying obviously reduced body length; weak dumpy or small (short and thin) body size; or general abnormalities. Moreover, compensatory regulation and non-specific silencing of dpy genes were found in B. xylophilus. Our results indicate that RNAi delivery by feeding in B. xylophilus is a successful technique. This platform may provide a new opportunity for undertaking RNAi-based, genome-wide gene functional studies in vitro in B. xylophilus. Moreover, as B. xylophilus feeds on endophytic fungi when a host has died, RNAi feeding technology will offer the prospect for developing a novel control strategy for the nematode

  19. Photocatalytic organic transformation by layered double hydroxides: highly efficient and selective oxidation of primary aromatic amines to their imines under ambient aerobic conditions.

    PubMed

    Yang, Xiu-Jie; Chen, Bin; Li, Xu-Bing; Zheng, Li-Qiang; Wu, Li-Zhu; Tung, Chen-Ho

    2014-06-25

    We report the first application of layered double hydroxide as a photocatalyst in the transformation of primary aromatic amines to their corresponding imines with high efficiency and selectivity by using oxygen in an air atmosphere as a terminal oxidant under light irradiation.

  20. Literacy Is Transformative. The Thirty-Fifth Yearbook A Doubled Peer Reviewed Publication of the Association of Literacy Educators and Researchers

    ERIC Educational Resources Information Center

    Szabo, Susan, Ed.; Martin, Linda, Ed.; Haas, Leslie, Ed.; Garza-Garcia, Lizabeth, Ed.

    2013-01-01

    For their 56th annual meeting, the Association of Educators and Researchers (ALER) met in Grand Rapids, Michigan at the Amway Grand Hotel. This year's conference theme was Literacy Is Transformative, which was also used as the title for this year's Yearbook, Volume 35. Included are double-peer reviewed papers, the presidential address,…

  1. Research on the dq coordinate transform in the six-phase double star windings shifted by 30° synchronous generators with axial magnetic field

    NASA Astrophysics Data System (ADS)

    Bian, Xiangnan; Ma, Qishuang

    2006-11-01

    As an intermediate frequency power source, the double star windings shifted by 30° synchronous generator with axial magnetic field (DSWAMF) is widely used in the different areas. Using the generalized inverse, the transformation matrix of double windings synchronous generators with two Y-connected 3-phase symmetrical windings displaced in turn by 30° from rotating to stationary axes is proposed. With the transformation matrix, the state-space model of the generators is established. Obtained the relation of interconnection, and optimize the parameter. The kind of machine is simulated by finite element method (FEM), mutual inductance of the simulation is similar to theory. The generator mathematical model is established, the internal parameter of this kind of generator can be obtained easily with transformation matrix.

  2. Exponential approximations in optimal design

    NASA Technical Reports Server (NTRS)

    Belegundu, A. D.; Rajan, S. D.; Rajgopal, J.

    1990-01-01

    One-point and two-point exponential functions have been developed and proved to be very effective approximations of structural response. The exponential has been compared to the linear, reciprocal and quadratic fit methods. Four test problems in structural analysis have been selected. The use of such approximations is attractive in structural optimization to reduce the numbers of exact analyses which involve computationally expensive finite element analysis.

  3. Toward artifact-free data in Hadamard transform-based double multiplexing of ion mobility-Orbitrap mass spectrometry

    SciTech Connect

    Tummalacherla, Meghasyam; Garimella, Sandilya V. B.; Prost, Spencer A.; Ibrahim, Yehia M.

    2017-01-01

    The integration of ion mobility spectrometry (IMS) with trap-based mass spectrometer (MS) such as Orbitrap using the dual gate approach suffers from low duty cycle. Efforts to improve the duty cycle involve the utilization of Hadamard transform based double multiplexing which significantly improve the signal to noise ratio and duty cycle of the ion mobility – Orbitrap mass spectrometry (IM – Orbitrap MS) platform. However, significant fluctuations in ion intensity and the temporal shifts in the encoded data give rise to artifacts and noise in the demultiplexed data which significantly reduce the data quality and negate the benefits of multiplexing. We propose a new approach that identifies the true IM peaks and helps in eliminating the artifacts in the demultiplexed data leading to a decrease in false positives in subsequent data processing. The algorithm takes an analytical approach to first identify the position of the IM peak in the temporal domain, and then demultiplex and identify the true data making it easier for subsequent data processing. After the application of the algorithm, the quality of the IM-Orbitrap MS measurements was greatly improved because of the reduction in artifacts.

  4. Is radioactive decay really exponential?

    NASA Astrophysics Data System (ADS)

    Aston, P. J.

    2012-03-01

    Radioactive decay of an unstable isotope is widely believed to be exponential. This view is supported by experiments on rapidly decaying isotopes but is more difficult to verify for slowly decaying isotopes. The decay of 14C can be calibrated over a period of 12550 years by comparing radiocarbon dates with dates obtained from dendrochronology. It is well known that this approach shows that radiocarbon dates of over 3000 years are in error, which is generally attributed to past variation in atmospheric levels of 14C. We note that predicted atmospheric variation (assuming exponential decay) does not agree with results from modelling, and that theoretical quantum mechanics does not predict exact exponential decay. We give mathematical arguments that non-exponential decay should be expected for slowly decaying isotopes and explore the consequences of non-exponential decay. We propose an experimental test of this prediction of non-exponential decay for 14C. If confirmed, a foundation stone of current dating methods will have been removed, requiring a radical reappraisal both of radioisotope dating methods and of currently predicted dates obtained using these methods.

  5. Study of the {alpha}{double_prime} phase texture obtained by martensitic {beta}-{alpha}{double_prime} phase transformation induced by tensile test in a sheet of Ti5Al2Sn4Zr4Mo2Cr1Fe

    SciTech Connect

    Pionnier, D.; Humbert, M.; Philippe, M.J.; Combres, Y.

    1998-10-09

    The purpose was to investigate the texture development of the {alpha}{double_prime} orthorhombic martensite phase induced by stress within a commercial sheet of Ti5Al2Sn4Zr4Mo2Cr1Fe. First, the experimental textures of the initial b.c.c. phase, then of the b.c.c. phase and the {alpha}{double_prime} martensite phase after a uniaxial deformation were determined from pole figures. Comparison of the {alpha}{double_prime} experimental texture with a {alpha}{double_prime} texture, simulated with no variant selection from the b.c.c. texture of the initial {beta} matrix clearly shows that a strong variant selection was induced by stress. In order to better understand the formation of this {alpha}{double_prime} orthorhombic texture, texture transformations were simulated according to different variant selection assumptions. As a result, it was shown that the {alpha}{double_prime} orthorhombic texture is formed by the variants favorably oriented with respect to stresses induced during tensile test.

  6. Universality in Stochastic Exponential Growth

    NASA Astrophysics Data System (ADS)

    Iyer-Biswas, Srividya; Crooks, Gavin E.; Scherer, Norbert F.; Dinner, Aaron R.

    2014-07-01

    Recent imaging data for single bacterial cells reveal that their mean sizes grow exponentially in time and that their size distributions collapse to a single curve when rescaled by their means. An analogous result holds for the division-time distributions. A model is needed to delineate the minimal requirements for these scaling behaviors. We formulate a microscopic theory of stochastic exponential growth as a Master Equation that accounts for these observations, in contrast to existing quantitative models of stochastic exponential growth (e.g., the Black-Scholes equation or geometric Brownian motion). Our model, the stochastic Hinshelwood cycle (SHC), is an autocatalytic reaction cycle in which each molecular species catalyzes the production of the next. By finding exact analytical solutions to the SHC and the corresponding first passage time problem, we uncover universal signatures of fluctuations in exponential growth and division. The model makes minimal assumptions, and we describe how more complex reaction networks can reduce to such a cycle. We thus expect similar scalings to be discovered in stochastic processes resulting in exponential growth that appear in diverse contexts such as cosmology, finance, technology, and population growth.

  7. Universality in stochastic exponential growth.

    PubMed

    Iyer-Biswas, Srividya; Crooks, Gavin E; Scherer, Norbert F; Dinner, Aaron R

    2014-07-11

    Recent imaging data for single bacterial cells reveal that their mean sizes grow exponentially in time and that their size distributions collapse to a single curve when rescaled by their means. An analogous result holds for the division-time distributions. A model is needed to delineate the minimal requirements for these scaling behaviors. We formulate a microscopic theory of stochastic exponential growth as a Master Equation that accounts for these observations, in contrast to existing quantitative models of stochastic exponential growth (e.g., the Black-Scholes equation or geometric Brownian motion). Our model, the stochastic Hinshelwood cycle (SHC), is an autocatalytic reaction cycle in which each molecular species catalyzes the production of the next. By finding exact analytical solutions to the SHC and the corresponding first passage time problem, we uncover universal signatures of fluctuations in exponential growth and division. The model makes minimal assumptions, and we describe how more complex reaction networks can reduce to such a cycle. We thus expect similar scalings to be discovered in stochastic processes resulting in exponential growth that appear in diverse contexts such as cosmology, finance, technology, and population growth.

  8. Enigma of earthquakes at ridge-transform-fault plate boundaries - Distribution of non-double couple parameter of Harvard CMT solutions. [Centroid Moment Tensors

    SciTech Connect

    Kawakatsu, Hitoshi )

    1991-06-01

    The distribution of the non-double couple parameter of shallow earthquakes reported in the Harvard CMT catalogue shows systematic characteristics depending on the epicentral locations and types of fault mechanisms. The authors suggest that they can be explained by the presence of subevents with different double couple mechanisms in a single rupture sequence. The earthquakes at the ridge-transform-fault plate boundaries show a particularly interesting pattern. It is suggested that two types of faulting expected in the area (i.e., normal faults at ridges and strike slip faults at transform-faults) tend to occur almost simultaneously, although this hypothesis needs to be delineated by careful analyses using bodywave waveforms.

  9. Approximating Functions with Exponential Functions

    ERIC Educational Resources Information Center

    Gordon, Sheldon P.

    2005-01-01

    The possibility of approximating a function with a linear combination of exponential functions of the form e[superscript x], e[superscript 2x], ... is considered as a parallel development to the notion of Taylor polynomials which approximate a function with a linear combination of power function terms. The sinusoidal functions sin "x" and cos "x"…

  10. Linear or Exponential Number Lines

    ERIC Educational Resources Information Center

    Stafford, Pat

    2011-01-01

    Having decided to spend some time looking at one's understanding of numbers, the author was inspired by "Alex's Adventures in Numberland," by Alex Bellos to look at one's innate appreciation of number. Bellos quotes research studies suggesting that an individual's natural appreciation of numbers is more likely to be exponential rather…

  11. Quantum properties of exponential states

    SciTech Connect

    Luis, Alfredo

    2007-05-15

    The use of Renyi entropy as an uncertainty measure alternative to variance leads to the study of states with quantum fluctuations below the levels established by Gaussian states, which are the position-momentum minimum uncertainty states according to variance. We examine the quantum properties of states with exponential wave functions, which combine reduced fluctuations with practical feasibility.

  12. Phenomenology of stochastic exponential growth

    NASA Astrophysics Data System (ADS)

    Pirjol, Dan; Jafarpour, Farshid; Iyer-Biswas, Srividya

    2017-06-01

    Stochastic exponential growth is observed in a variety of contexts, including molecular autocatalysis, nuclear fission, population growth, inflation of the universe, viral social media posts, and financial markets. Yet literature on modeling the phenomenology of these stochastic dynamics has predominantly focused on one model, geometric Brownian motion (GBM), which can be described as the solution of a Langevin equation with linear drift and linear multiplicative noise. Using recent experimental results on stochastic exponential growth of individual bacterial cell sizes, we motivate the need for a more general class of phenomenological models of stochastic exponential growth, which are consistent with the observation that the mean-rescaled distributions are approximately stationary at long times. We show that this behavior is not consistent with GBM, instead it is consistent with power-law multiplicative noise with positive fractional powers. Therefore, we consider this general class of phenomenological models for stochastic exponential growth, provide analytical solutions, and identify the important dimensionless combination of model parameters, which determines the shape of the mean-rescaled distribution. We also provide a prescription for robustly inferring model parameters from experimentally observed stochastic growth trajectories.

  13. Linear or Exponential Number Lines

    ERIC Educational Resources Information Center

    Stafford, Pat

    2011-01-01

    Having decided to spend some time looking at one's understanding of numbers, the author was inspired by "Alex's Adventures in Numberland," by Alex Bellos to look at one's innate appreciation of number. Bellos quotes research studies suggesting that an individual's natural appreciation of numbers is more likely to be exponential rather…

  14. On double exponential forward bias current-voltage (I-V) characteristics of Au/Ca3Co4Ga0.001Ox/n-Si/Au (MIS) type structures in temperature range of 80-340 K

    NASA Astrophysics Data System (ADS)

    Marıl, E.; Altındal, Ş.; Kaya, A.; Koçyiğit, S.; Uslu, İ.

    2015-04-01

    Current transport mechanisms (CTMs) of Au/Ca3Co4Ga0.001Ox/n-Si/Au (MIS) type structures were investigated using current-voltage (I-V) characteristics in the temperature range of 80-340 K. Semilogarithmic I-V plots show two linear regions corresponding to low (0.075-0.250 V) and moderate (0.27-0.70 V) biases, respectively. Zero-bias barrier height (ΦB0) was observed to increase with increase in the temperature, whereas opposite behaviour was observed for ideality factor (n). ΦB0 and (n-1-1) vesus q/2kT and ΦB0 versus n plots were drawn to get an evidence of Gaussian distribution (GD) of the barrier heights. These plots, too, show two linear regions corresponding to low (80-160 K) and high (200-340 K) temperature ranges (LTR and HTR), respectively. Mean value of barrier height (?B0) and standard deviation (σs) were extracted from the intercept and slope of ΦB0 versus q/2kT plots for two linear regions as 0.382 eV, 0.0060 V for LTR and 0.850 eV, 0.135 V for HTR at low biases and 0.364 eV, 0.0059 V for LTR and 0.806 eV, 0.132 V for HTR at high biases, respectively. ?B0 and Richardson constant (A*) values were also obtained from the intercept and slope of the modified Richardson (Ln(Io/T2)-(q2σs2/2k2T2) versus q/kT) plots as 131.81 Acm-2 K-2, 0.381 eV for LTR and 129.35 Acm-2 K-2, 0. 854 eV for HTR at low biases and 148.01 Acm-2 K-2, 0.377 eV for LTR and 143.77 Acm-2 K-2, 0.812 eV for HTR at high biases, respectively. In conclusion, CTM in the structure can be successfully explained in terms of thermionic emission theory with the double GD of barrier heights.

  15. Exponentially Stabilizing Robot Control Laws

    NASA Technical Reports Server (NTRS)

    Wen, John T.; Bayard, David S.

    1990-01-01

    New class of exponentially stabilizing laws for joint-level control of robotic manipulators introduced. In case of set-point control, approach offers simplicity of proportion/derivative control architecture. In case of tracking control, approach provides several important alternatives to completed-torque method, as far as computational requirements and convergence. New control laws modified in simple fashion to obtain asymptotically stable adaptive control, when robot model and/or payload mass properties unknown.

  16. A Transformed Bacterium Expressing Double-Stranded RNA Specific to Integrin β1 Enhances Bt Toxin Efficacy against a Polyphagous Insect Pest, Spodoptera exigua

    PubMed Central

    Kim, Eunseong; Park, Youngjin; Kim, Yonggyun

    2015-01-01

    Background Oral toxicity of double-stranded RNA (dsRNA) specific to integrin β1 subunit (SeINT) was known in a polyphagous insect pest, Spodoptera exigua. For an application of the dsRNA to control the insect pest, this study prepared a transformed Escherichia coli expressing dsRNA specific to SeINT. Principal Findings The dsRNA expression was driven by T7 RNA polymerase overexpressed by an inducer in the transformed E. coli. The produced dsRNA amount was proportional to the number of the cultured bacteria. The transformed bacteria gave a significant oral toxicity to S. exigua larvae with a significant reduction of the SeINT expression. The resulting insect mortality increased with the fed number of the bacteria. Pretreatment with an ultra-sonication to disrupt bacterial cell wall/membrane significantly increased the insecticidal activity of the transformed bacteria. The larvae treated with the transformed bacteria suffered tissue damage in the midgut epithelium, which exhibited a marked loss of cell-cell contacts and underwent a remarkable cell death. Moreover, these treated larvae became significantly susceptible to a Cry toxin derived from Bacillus thuringiensis (Bt). Conclusions This study provides a novel and highly efficient application technique to use dsRNA specific to an integrin gene by mixing with a biopesticide, Bt. PMID:26171783

  17. Synthesis of double-layered rotavirus-like particles using internal ribosome entry site vector system in stably-transformed Drosophila melanogaster.

    PubMed

    Lee, Jong Min; Chung, Ha Young; Kim, Kyung Il; Yoo, Ki Hyun; Hwang-Bo, Jeon; Chung, In Sik; Park, Jong-Hwa

    2011-01-01

    We established a bicistronic expression system using an encephalomyocarditis virus (EMCV)-derived internal ribosomal entry site (IRES) element to generate stably transformed Drosophila melanogaster Schneider 2 (S2) cells expressing human rotavirus Wa capsid proteins, VP2 and VP6, for the synthesis of VP2/6 double-layered virus-like particle (DVLP). The EMCV-derived IRES permitted bicistronic translation of recombinant VP6. Recombinant VP2 and VP6 were detected in extracellular fractions of stably transformed S2 cells. A wheel-like DVLP (diam ~ 50-55 nm) with short spikes was produced from the extracellular fraction of stably transformed S2 cells. A bicistronic expression system using an EMCV-derived IRES element can thus be used to express two proteins of interest in stably transformed S2 cells. The bi-or tri-cistronic expression of recombinant VP2/6/7 using stably transformed S2 cells can also be used to produce rotavirus VLPs.

  18. Application of exponential homotopy algorithm in the inverter harmonic elimination

    NASA Astrophysics Data System (ADS)

    Zhang, Li

    2017-02-01

    Eliminating harmonic pollution and improving power factor are the quite important task in the field of power electronics. From the mathematical point of view, harmonic elimination problems can be translated into nonlinear equations. But it is difficult to directly solve the nonlinear equations because of complexity. For this reason, exponential homotopy method is proposed based on homotopy method in this paper. It has focused on built up homotopy equations by modifying the singularities of Jacobian matrix, and on this basis homotopy equations are transformed into the differential initial value problems. Numerical results show that the new exponential homotopy method has higher precision than other algorithms, and the singularity is improved.

  19. Communication: An effective linear-scaling atomic-orbital reformulation of the random-phase approximation using a contracted double-Laplace transformation

    SciTech Connect

    Schurkus, Henry F.; Ochsenfeld, Christian

    2016-01-21

    An atomic-orbital (AO) reformulation of the random-phase approximation (RPA) correlation energy is presented allowing to reduce the steep computational scaling to linear, so that large systems can be studied on simple desktop computers with fully numerically controlled accuracy. Our AO-RPA formulation introduces a contracted double-Laplace transform and employs the overlap-metric resolution-of-the-identity. First timings of our pilot code illustrate the reduced scaling with systems comprising up to 1262 atoms and 10 090 basis functions. .

  20. Exponential Formulae and Effective Operations

    NASA Technical Reports Server (NTRS)

    Mielnik, Bogdan; Fernandez, David J. C.

    1996-01-01

    One of standard methods to predict the phenomena of squeezing consists in splitting the unitary evolution operator into the product of simpler operations. The technique, while mathematically general, is not so simple in applications and leaves some pragmatic problems open. We report an extended class of exponential formulae, which yield a quicker insight into the laboratory details for a class of squeezing operations, and moreover, can be alternatively used to programme different type of operations, as: (1) the free evolution inversion; and (2) the soft simulations of the sharp kicks (so that all abstract results involving the kicks of the oscillator potential, become realistic laboratory prescriptions).

  1. Teaching about Exponential Growth in Social Studies.

    ERIC Educational Resources Information Center

    Allen, Rodney F.; LaHart, David E.

    1984-01-01

    Characteristics of exponential growth which should be taught in social studies classes are listed, and learning activities dealing with exponential growth which can be used in secondary social studies classes are provided. (RM)

  2. Optical security system using jigsaw transforms of the second random phase mask and the encrypted image in a double random phase encoding system

    NASA Astrophysics Data System (ADS)

    Singh, Madan; Kumar, Arvind; Singh, Kehar

    2008-10-01

    In this paper, we have described a simple and secure double random phase encoding and decoding system to encrypt and decrypt a two-dimensional gray scale image. We have used jigsaw transforms of the second random phase mask and the encrypted image. The random phase mask placed in the Fourier plane is broken into independent non-overlapping segments by applying the jigsaw transform. To make the system more secure, a jigsaw transform on the encrypted image is also carried out. The encrypted image is also broken into independent non-overlapping segments. The jigsaw transform indices of random phase code and the encrypted image form the keys for the successful retrieval of the data. Encrypting with this technique makes it almost impossible to retrieve the image without using both the right keys. Results of computer simulation have been presented in support of the proposed idea. Mean square error (MSE) between the decrypted and the original image has also been calculated in support of the technique.

  3. Doubling an investment

    NASA Astrophysics Data System (ADS)

    Eliazar, Iddo

    2004-01-01

    We study the issue of optimal long-term portfolio management in continuous time multi-asset financial markets. Rather than following the abstract notion of ‘utility’ and its implied paradigm of ‘maximization of expected utility’ we suggest a different approach: The investor sets a goal-such as reaching a desired fortune level, or doubling the initial investment-and then operates to minimize the expected time-to-goal, i.e., achieving the goal as quick as possible. We assume the ‘standard model’ of multi-asset financial markets where assets are governed by correlated Geometric Brownian motion dynamics, and study optimality under the criteria of ‘minimization of the expected time-to-goal’. We explicitly compute: (i) the optimal holding strategies; (ii) the dynamics and behavior of the optimal investment portfolios; and, (iii) the statistics-mean, variance, and Laplace transform-of the time-to-goal (under the optimal investment strategy). Also, an investment paradox arising in this context-in which some portfolios have exponential mean growth but have a positive probability of never doubling their initial value-is discussed and explained.

  4. N-fold Darboux transformation and double-Wronskian-typed solitonic structures for a variable-coefficient modified Kortweg-de Vries equation

    SciTech Connect

    Wang, Lei; Gao, Yi-Tian; Qi, Feng-Hua

    2012-08-15

    Under investigation in this paper is a variable-coefficient modified Kortweg-de Vries (vc-mKdV) model describing certain situations from the fluid mechanics, ocean dynamics and plasma physics. N-fold Darboux transformation (DT) of a variable-coefficient Ablowitz-Kaup-Newell-Segur spectral problem is constructed via a gauge transformation. Multi-solitonic solutions in terms of the double Wronskian for the vc-mKdV model are derived by the reduction of the N-fold DT. Three types of the solitonic interactions are discussed through figures: (1) Overtaking collision; (2) Head-on collision; (3) Parallel solitons. Nonlinear, dispersive and dissipative terms have the effects on the velocities of the solitonic waves while the amplitudes of the waves depend on the perturbation term. - Highlights: Black-Right-Pointing-Pointer N-fold DT is firstly applied to a vc-AKNS spectral problem. Black-Right-Pointing-Pointer Seeking a double Wronskian solution is changed into solving two systems. Black-Right-Pointing-Pointer Effects of the variable coefficients on the multi-solitonic waves are discussed in detail. Black-Right-Pointing-Pointer This work solves the problem from Yi Zhang [Ann. Phys. 323 (2008) 3059].

  5. Perturbation-minimized triangular bunch for high-transformer ratio using a double dogleg emittance exchange beam line

    NASA Astrophysics Data System (ADS)

    Ha, G.; Cho, M. H.; Gai, W.; Kim, K.-J.; Namkung, W.; Power, J. G.

    2016-12-01

    The longitudinal shape, i.e., the current profile, of an electron bunch determines the transformer ratio in a collinear wakefield accelerator and thus methods are sought to control the longitudinal bunch shape. The emittance exchange (EEX) appears to be promising for creating a precisely controlled longitudinal bunch shapes. The longitudinal shape is perturbed by two sources: higher-order terms in the beam line optics and collective effects and these perturbations can lead to a significant drop of the transformer ratio. In this paper, we analytically and numerically investigate the perturbation to an ideal triangular longitudinal bunch shape and propose methods to minimize it.

  6. Observational constraints on exponential gravity

    SciTech Connect

    Yang, Louis; Lee, Chung-Chi; Luo, Ling-Wei; Geng, Chao-Qiang

    2010-11-15

    We study the observational constraints on the exponential gravity model of f(R)=-{beta}R{sub s}(1-e{sup -R/R}{sub s}). We use the latest observational data including Supernova Cosmology Project Union2 compilation, Two-Degree Field Galaxy Redshift Survey, Sloan Digital Sky Survey Data Release 7, and Seven-Year Wilkinson Microwave Anisotropy Probe in our analysis. From these observations, we obtain a lower bound on the model parameter {beta} at 1.27 (95% C.L.) but no appreciable upper bound. The constraint on the present matter density parameter is 0.245<{Omega}{sub m}{sup 0}<0.311 (95% C.L.). We also find out the best-fit value of model parameters on several cases.

  7. Transformation of cytogenetically normal chronic myelomonocytic leukaemia to an acute myeloid leukaemia and the emergence of a novel +13, +15 double trisomy resulting in an adverse outcome.

    PubMed

    McGrattan, Peter; Humphreys, Mervyn; Hull, Donald; McMullin, Mary F

    2007-09-01

    A 58-year-old man was admitted with symptoms of lethargy and easy bruising for four months duration. Peripheral blood (PB) analysis revealed a white blood cell count (WBC) of 15.9 x 10(9)/l with monocytes 5.4 x 10(9)/l. Bone marrow (BM) was hypercellular with 15% blasts, monocytosis and trilineage dysplasia. Conventional cytogenetic analysis (G-banding) detected an apparently normal male karyotype (46,XY). A diagnosis of chronic myelomonocytic leukaemia (CMML) was made. After 3 years, PB analysis revealed a WBC count of 22 x 10(9)/l and a predominance of blasts. BM aspirate analysis also revealed 89% myeloid blasts and G-banding detected the emergence of an abnormal clone harbouring an extra copy of chromosomes 13 and 15. A diagnosis of disease transformation to acute myeloid leukaemia (AML) was made. Post chemotherapy BM aspirate was very hypocellular and the abnormal +13, +15 clone was still present suggesting primary refractory disease. A second course of chemotherapy was only administered for 24 hours due to complications. The abnormal +13, +15 clone was still present and it was decided that no further treatment apart from palliative care could be offered. The patient died 11 weeks later, five months after AML transformation. This is the first description of a cytogenetically normal CMML patient transforming to AML with the emergence of a unique +13, +15 double trisomy resulting in an adverse outcome.

  8. Polar exponential sensor arrays unify iconic and Hough space representation

    NASA Technical Reports Server (NTRS)

    Weiman, Carl F. R.

    1990-01-01

    The log-polar coordinate system, inherent in both polar exponential sensor arrays and log-polar remapped video imagery, is identical to the coordinate system of its corresponding Hough transform parameter space. The resulting unification of iconic and Hough domains simplifies computation for line recognition and eliminates the slope quantization problems inherent in the classical Cartesian Hough transform. The geometric organization of the algorithm is more amenable to massively parallel architectures than that of the Cartesian version. The neural architecture of the human visual cortex meets the geometric requirements to execute 'in-place' log-Hough algorithms of the kind described here.

  9. EXPONENTIAL GALAXY DISKS FROM STELLAR SCATTERING

    SciTech Connect

    Elmegreen, Bruce G.; Struck, Curtis E-mail: curt@iastate.edu

    2013-10-01

    Stellar scattering off of orbiting or transient clumps is shown to lead to the formation of exponential profiles in both surface density and velocity dispersion in a two-dimensional non-self gravitating stellar disk with a fixed halo potential. The exponential forms for both nearly flat rotation curves and near-solid-body rotation curves. The exponential does not depend on initial conditions, spiral arms, bars, viscosity, star formation, or strong shear. After a rapid initial development, the exponential saturates to an approximately fixed scale length. The inner exponential in a two-component profile has a break radius comparable to the initial disk radius; the outer exponential is primarily scattered stars.

  10. Theory, computation, and application of exponential splines

    SciTech Connect

    McCartin, B.J.

    1981-10-01

    A generalization of the semiclassical cubic spline known in the literature as the exponential spline is discussed. In actuality, the exponential spline represents a continuum of interpolants ranging from the cubic spline to the linear spline. A particular member of this family is uniquely specified by the choice of certain tension parameters. The theoretical underpinnings of the exponential spline are outlined. This development roughly parallels the existing theory for cubic splines. The primary extension lies in the ability of the exponential spline to preserve convexity and monotonicity present in the data. Next, the numerical computation of the exponential spline is discussed. A variety of numerical devices are employed to produce a stable and robust algorithm. An algorithm for the selection of tension parameters that will produce a shape preserving approximant is developed. A sequence of selected curve-fitting examples are presented which clearly demonstrate the advantages of exponential splines over cubic splines.

  11. Theory, computation, and application of exponential splines

    NASA Technical Reports Server (NTRS)

    Mccartin, B. J.

    1981-01-01

    A generalization of the semiclassical cubic spline known in the literature as the exponential spline is discussed. In actuality, the exponential spline represents a continuum of interpolants ranging from the cubic spline to the linear spline. A particular member of this family is uniquely specified by the choice of certain tension parameters. The theoretical underpinnings of the exponential spline are outlined. This development roughly parallels the existing theory for cubic splines. The primary extension lies in the ability of the exponential spline to preserve convexity and monotonicity present in the data. Next, the numerical computation of the exponential spline is discussed. A variety of numerical devices are employed to produce a stable and robust algorithm. An algorithm for the selection of tension parameters that will produce a shape preserving approximant is developed. A sequence of selected curve-fitting examples are presented which clearly demonstrate the advantages of exponential splines over cubic splines.

  12. Comparison of Exponential Smoothing Methods in Forecasting Palm Oil Real Production

    NASA Astrophysics Data System (ADS)

    Siregar, B.; Butar-Butar, I. A.; Rahmat, RF; Andayani, U.; Fahmi, F.

    2017-01-01

    Palm oil has important role for the plantation subsector. Forecasting of the real palm oil production in certain period is needed by plantation companies to maintain their strategic management. This study compared several methods based on exponential smoothing (ES) technique such as single ES, double exponential smoothing holt, triple exponential smoothing, triple exponential smoothing additive and multiplicative to predict the palm oil production. We examined the accuracy of forecasting models of production data and analyzed the characteristics of the models. Programming language R was used with selected constants for double ES (α and β) and triple ES (α, β, and γ) evaluated by the technique of minimizing the root mean squared prediction error (RMSE). Our result showed that triple ES additives had lowest error rate compared to the other models with RMSE of 0.10 with a combination of parameters α = 0.6, β = 0.02, and γ = 0.02.

  13. Equivalences between nonuniform exponential dichotomy and admissibility

    NASA Astrophysics Data System (ADS)

    Zhou, Linfeng; Lu, Kening; Zhang, Weinian

    2017-01-01

    Relationship between exponential dichotomies and admissibility of function classes is a significant problem for hyperbolic dynamical systems. It was proved that a nonuniform exponential dichotomy implies several admissible pairs of function classes and conversely some admissible pairs were found to imply a nonuniform exponential dichotomy. In this paper we find an appropriate admissible pair of classes of Lyapunov bounded functions which is equivalent to the existence of nonuniform exponential dichotomy on half-lines R± separately, on both half-lines R± simultaneously, and on the whole line R. Additionally, the maximal admissibility is proved in the case on both half-lines R± simultaneously.

  14. β-Catenin stabilization stalls the transition from double-positive to single-positive stage and predisposes thymocytes to malignant transformation

    PubMed Central

    Guo, Zhuyan; Dose, Marei; Kovalovsky, Damian; Chang, Rui; O'Neil, Jennifer; Look, A. Thomas; von Boehmer, Harald; Khazaie, Khashayarsha

    2007-01-01

    Activation of β-catenin has been causatively linked to the etiology of colon cancer. Conditional stabilization of this molecule in pro-T cells promotes thymocyte development without the requirement for pre-TCR signaling. We show here that activated β-catenin stalls the developmental transition from the double-positive (DP) to the single-positive (SP) thymocyte stage and predisposes DP thymocytes to transformation. β-Catenin–induced thymic lymphomas have a leukemic arrest at the early DP stage. Lymphomagenesis requires Rag activity, which peaks at this developmental stage, as well as additional secondary genetic events. A consistent secondary event is the transcriptional up-regulation of c-Myc, whose activity is required for transformation because its conditional ablation abrogates lymphomagenesis. In contrast, the expression of Notch receptors as well as targets is reduced in DP thymocytes with stabilized β-catenin and remains low in the lymphomas, indicating that Notch activation is not required or selected for in β-catenin–induced lymphomas. Thus, β-catenin activation may provide a mechanism for the induction of T-cell–acute lymphoblastic leukemia (T-ALL) that does not depend on Notch activation. PMID:17317856

  15. MHD effects on a thermo-solutal stratified nanofluid flow on an exponentially radiating stretching sheet

    NASA Astrophysics Data System (ADS)

    Hayat, T.; Rashid, M.; Imtiaz, M.; Alsaedi, A.

    2017-03-01

    This study is focused on the heat and mass transfer effects in a magnetohydrodynamic (MHD) flow of a viscous nanofluid saturating a porous medium past an exponentially radiating stretching sheet. The governing differential equations are transformed to a system of nonlinear ordinary differential equations by suitable transformations. It is noted that stratification affects the local Nusselt and Sherwood numbers.

  16. The Laguerre Transform.

    DTIC Science & Technology

    1980-05-01

    equations. - , Part 2 of this paper deals with functions having support on (-oO) via a bilateral Laguerre transform which is an extension of the...the Laguerre Transform to Non- Integrable Functions Via Exponential Trans- formation 22 6. The Rate of Convergence of the Laguerre Coefficients 23 7...analy- tically via Laplace transformation , and full answers may be obtained when the Laplace transforms are invertible. More often than not, such

  17. Rotating flow of a nanofluid due to an exponentially stretching surface with suction

    NASA Astrophysics Data System (ADS)

    Salleh, Siti Nur Alwani; Bachok, Norfifah; Arifin, Norihan Md

    2017-08-01

    An analysis of the rotating nanofluid flow past an exponentially stretched surface with the presence of suction is studied in this work. Three different types of nanoparticles, namely, copper, titania and alumina are considered. The system of ordinary differential equations is computed numerically using a shooting method in Maple software after being transformed from the partial differential equations. This transformation has considered the similarity transformations in exponential form. The physical effect of the rotation, suction and nanoparticle volume fraction parameters on the rotating flow and heat transfer phenomena is investigated and has been described in detail through graphs. The dual solutions are found to appear when the governing parameters reach a certain range.

  18. Giving Exponential Functions a Fair Shake

    ERIC Educational Resources Information Center

    Wanko, Jeffrey J.

    2005-01-01

    This article details an exploration of exponential decay and growth relationships using M&M's and dice. Students collect data for mathematical models and use graphing calculators to make sense of the general form of the exponential functions. (Contains 10 figures and 2 tables.)

  19. The matrix exponential in transient structural analysis

    NASA Technical Reports Server (NTRS)

    Minnetyan, Levon

    1987-01-01

    The primary usefulness of the presented theory is in the ability to represent the effects of high frequency linear response with accuracy, without requiring very small time steps in the analysis of dynamic response. The matrix exponential contains a series approximation to the dynamic model. However, unlike the usual analysis procedure which truncates the high frequency response, the approximation in the exponential matrix solution is in the time domain. By truncating the series solution to the matrix exponential short, the solution is made inaccurate after a certain time. Yet, up to that time the solution is extremely accurate, including all high frequency effects. By taking finite time increments, the exponential matrix solution can compute the response very accurately. Use of the exponential matrix in structural dynamics is demonstrated by simulating the free vibration response of multi degree of freedom models of cantilever beams.

  20. Historical remarks on exponential product and quantum analysis

    SciTech Connect

    Suzuki, Masuo

    2015-03-10

    The exponential product formula [1, 2] was substantially introduced in physics by the present author [2]. Its systematic applications to quantum Monte Carlo Methods [3] were preformed [4, 5] first in 1977. Many interesting applications [6] of the quantum-classical correspondence (namely S-T transformation) have been reported. Systematic higher-order decomposition formulae were also discovered by the present author [7-11], using the recursion scheme [7, 9]. Physically speaking, these exponential product formulae play a conceptual role of separation of procedures [3,14]. Mathematical aspects of these formulae have been integrated in quantum analysis [15], in which non-commutative differential calculus is formulated and a general quantum Taylor expansion formula is given. This yields many useful operator expansion formulae such as the Feynman expansion formula and the resolvent expansion. Irreversibility and entropy production are also studied using quantum analysis [15].

  1. An Exponential Finite Difference Technique for Solving Partial Differential Equations.

    DTIC Science & Technology

    1987-06-01

    density , kg/N 3 (lbm/ft 3) 91.*,e separation variables (At dimensionless timelAX) 2 vi -W sNiv W- NiW.4%1 1. INTRODUCTION Partial differential equations...competing numerical analysis were run in double precision on either the IBM-3033 or the Cray X-MP mainframes. The computer codes developed for the...is increased. - R P~p~ 15 Effect of Initial and Boundary Conditions on the Exponential Finite Difference Method In this section the effect of

  2. High-performance compression and double cryptography based on compressive ghost imaging with the fast Fourier transform

    NASA Astrophysics Data System (ADS)

    Leihong, Zhang; Zilan, Pan; Luying, Wu; Xiuhua, Ma

    2016-11-01

    To solve the problem that large images can hardly be retrieved for stringent hardware restrictions and the security level is low, a method based on compressive ghost imaging (CGI) with Fast Fourier Transform (FFT) is proposed, named FFT-CGI. Initially, the information is encrypted by the sender with FFT, and the FFT-coded image is encrypted by the system of CGI with a secret key. Then the receiver decrypts the image with the aid of compressive sensing (CS) and FFT. Simulation results are given to verify the feasibility, security, and compression of the proposed encryption scheme. The experiment suggests the method can improve the quality of large images compared with conventional ghost imaging and achieve the imaging for large-sized images, further the amount of data transmitted largely reduced because of the combination of compressive sensing and FFT, and improve the security level of ghost images through ciphertext-only attack (COA), chosen-plaintext attack (CPA), and noise attack. This technique can be immediately applied to encryption and data storage with the advantages of high security, fast transmission, and high quality of reconstructed information.

  3. Comparing exponential and exponentiated models of drug demand in cocaine users.

    PubMed

    Strickland, Justin C; Lile, Joshua A; Rush, Craig R; Stoops, William W

    2016-12-01

    Drug purchase tasks provide rapid and efficient measurement of drug demand. Zero values (i.e., prices with zero consumption) present a quantitative challenge when using exponential demand models that exponentiated models may resolve. We aimed to replicate and advance the utility of using an exponentiated model by demonstrating construct validity (i.e., association with real-world drug use) and generalizability across drug commodities. Participants (N = 40 cocaine-using adults) completed Cocaine, Alcohol, and Cigarette Purchase Tasks evaluating hypothetical consumption across changes in price. Exponentiated and exponential models were fit to these data using different treatments of zero consumption values, including retaining zeros or replacing them with 0.1, 0.01, or 0.001. Excellent model fits were observed with the exponentiated model. Means and precision fluctuated with different replacement values when using the exponential model but were consistent for the exponentiated model. The exponentiated model provided the strongest correlation between derived demand intensity (Q0) and self-reported free consumption in all instances (Cocaine r = .88; Alcohol r = .97; Cigarette r = .91). Cocaine demand elasticity was positively correlated with alcohol and cigarette elasticity. Exponentiated parameters were associated with real-world drug use (e.g., weekly cocaine use) whereas these correlations were less consistent for exponential parameters. Our findings show that selection of zero replacement values affects demand parameters and their association with drug-use outcomes when using the exponential model but not the exponentiated model. This work supports the adoption of the exponentiated demand model by replicating improved fit and consistency and demonstrating construct validity and generalizability. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

  4. Bacterial Infection of Smad3/Rag2 Double-Null Mice with Transforming Growth Factor-β Dysregulation as a Model for Studying Inflammation-Associated Colon Cancer

    PubMed Central

    Maggio-Price, Lillian; Treuting, Piper; Bielefeldt-Ohmann, Helle; Seamons, Audrey; Drivdahl, Rolf; Zeng, Weiping; Lai, LapHin; Huycke, Mark; Phelps, Susan; Brabb, Thea; Iritani, Brian M.

    2009-01-01

    Alterations in genes encoding transforming growth factor-β-signaling components contribute to colon cancer in humans. Similarly, mice deficient in the transforming growth factor-β signaling molecule, Smad3, develop colon cancer, but only after a bacterial trigger occurs, resulting in chronic inflammation. To determine whether Smad3-null lymphocytes contribute to increased cancer susceptibility, we crossed Smad3-null mice with mice deficient in both B and T lymphocytes (Rag2−/− mice). Helicobacter-infected Smad3/Rag2-double knockout (DKO) mice had more diffuse inflammation and increased incidence of adenocarcinoma compared with Helicobacter-infected Smad3−/− or Rag2−/− mice alone. Adoptive transfer of WT CD4+CD25+ T-regulatory cells provided significant protection of Smad3/Rag2-DKO from bacterial-induced typhlocolitis, dysplasia, and tumor development, whereas Smad3−/− T-regulatory cells provided no protection. Immunohistochemistry, real-time reverse transcriptase-polymerase chain reaction, and Western blot analyses of colonic tissues from Smad3/Rag2-DKO mice 1 week after Helicobacter infection revealed an influx of macrophages, enhanced nuclear factor-κB activation, increased BclXL/Bcl-2 expression, increased c-Myc expression, accentuated epithelial cell proliferation, and up-regulated IFN-γ, IL-1α, TNF-α, IL-1β, and IL-6 transcription levels. These results suggest that the loss of Smad3 increases susceptibility to colon cancer by at least two mechanisms: deficient T-regulatory cell function, which leads to excessive inflammation after a bacterial trigger; and increased expression of proinflammatory cytokines, enhanced nuclear factor-κB activation, and increased expression of both pro-oncogenic and anti-apoptotic proteins that result in increased cell proliferation/survival of epithelial cells in colonic tissues. PMID:19119184

  5. A Simulation To Model Exponential Growth.

    ERIC Educational Resources Information Center

    Appelbaum, Elizabeth Berman

    2000-01-01

    Describes a simulation using dice-tossing students in a population cluster to model the growth of cancer cells. This growth is recorded in a scatterplot and compared to an exponential function graph. (KHR)

  6. A Simulation To Model Exponential Growth.

    ERIC Educational Resources Information Center

    Appelbaum, Elizabeth Berman

    2000-01-01

    Describes a simulation using dice-tossing students in a population cluster to model the growth of cancer cells. This growth is recorded in a scatterplot and compared to an exponential function graph. (KHR)

  7. Understanding Exponential Growth: As Simple as a Drop in a Bucket.

    ERIC Educational Resources Information Center

    Goldberg, Fred; Shuman, James

    1984-01-01

    Provides procedures for a simple laboratory activity on exponential growth and its characteristic doubling time. The equipment needed consists of a large plastic bucket, an eyedropper, a stopwatch, an assortment of containers and graduated cylinders, and a supply of water. (JN)

  8. Methods for the rapid solution of the pricing PIDEs in exponential and Merton models

    NASA Astrophysics Data System (ADS)

    Mayo, Anita

    2008-12-01

    The pricing equations for options on assets that follow jump-diffusion processes contain integrals in addition to the usual differential terms. These integrals usually make such equations expensive to solve numerically. Although Fast Fourier Transform methods can be used to to evaluate the integrals at all mesh points simultaneously, they are costly since the computational region must be extended in order to avoid problems with wrap around. Other numerical difficulties arise when the density function for the jump size is not smooth, as in the Kou double exponential model. We present new solution methods which are based on the fact that even when the problems contain time-dependent parameters the integrals often satisfy easily solved ordinary or parabolic partial differential equations. In particular, we show that by using the operator splitting method proposed by Andersen and Andreasen it is possible to reduce the solution of the pricing equation in the Kou and similar models to a sequence of ordinary differential equations at each time step. We discuss the methods and present results of numerical experiments.

  9. Double helix formation of poly(m-phenylene)s bearing achiral oligo(ethylene oxide) pendants and transformation into an excess of one-handed single helix through cholate binding in water.

    PubMed

    Ben, Teng; Furusho, Yoshio; Goto, Hidetoshi; Miwa, Kazuhiro; Yashima, Eiji

    2009-06-21

    A water-soluble poly(m-phenylene) bearing an achiral oligo(ethylene oxide) chain at the 5-position was synthesized by the Ni(0)-mediated homo-coupling polycondensation of a 3,5-dibromophenol monomer. The poly(m-phenylene) adopted a single helical conformation in protic media and self-assembled into a double helix in water through aromatic interaction, while it took a random-coil conformation in chloroform. Upon the addition of sodium cholate in water, the double helical poly(m-phenylene) was transformed into single strands, which bound the cholate molecules to form an excess of one-handed single helix.

  10. Phylogenetic Stochastic Mapping Without Matrix Exponentiation

    PubMed Central

    Irvahn, Jan; Minin, Vladimir N.

    2014-01-01

    Abstract Phylogenetic stochastic mapping is a method for reconstructing the history of trait changes on a phylogenetic tree relating species/organism carrying the trait. State-of-the-art methods assume that the trait evolves according to a continuous-time Markov chain (CTMC) and works well for small state spaces. The computations slow down considerably for larger state spaces (e.g., space of codons), because current methodology relies on exponentiating CTMC infinitesimal rate matrices—an operation whose computational complexity grows as the size of the CTMC state space cubed. In this work, we introduce a new approach, based on a CTMC technique called uniformization, which does not use matrix exponentiation for phylogenetic stochastic mapping. Our method is based on a new Markov chain Monte Carlo (MCMC) algorithm that targets the distribution of trait histories conditional on the trait data observed at the tips of the tree. The computational complexity of our MCMC method grows as the size of the CTMC state space squared. Moreover, in contrast to competing matrix exponentiation methods, if the rate matrix is sparse, we can leverage this sparsity and increase the computational efficiency of our algorithm further. Using simulated data, we illustrate advantages of our MCMC algorithm and investigate how large the state space needs to be for our method to outperform matrix exponentiation approaches. We show that even on the moderately large state space of codons our MCMC method can be significantly faster than currently used matrix exponentiation methods. PMID:24918812

  11. Template-free synthesis of amorphous double-shelled zinc-cobalt citrate hollow microspheres and their transformation to crystalline ZnCo2O4 microspheres.

    PubMed

    Xie, Qingshui; Li, Feng; Guo, Huizhang; Wang, Laisen; Chen, Yuanzhi; Yue, Guanghui; Peng, Dong-Liang

    2013-06-26

    A novel and facile approach was developed for the fabrication of amorphous double-shelled zinc-cobalt citrate hollow microspheres and crystalline double-shelled ZnCo2O4 hollow microspheres. In this approach, amorphous double-shelled zinc-cobalt citrate hollow microspheres were prepared through a simple route and with an aging process at 70 °C. The combining inward and outward Ostwald ripening processes are adopted to account for the formation of these double-shelled architectures. The double-shelled ZnCo2O4 hollow microspheres can be prepared via the perfect morphology inheritance of the double-shelled zinc-cobalt citrate hollow microspheres, by calcination at 500 °C for 2 h. The resultant double-shelled ZnCo2O4 hollow microspheres manifest a large reversible capacity, superior cycling stability, and good rate capability.

  12. Decoherence and Exponential Law: A Solvable Model

    NASA Technical Reports Server (NTRS)

    Pascazio, Saverio; Namiki, Mikio

    1996-01-01

    We analyze a modified version of the 'AgBr' Hamiltonian, solve exactly the equations of motion in terms of SU(2) coherent states, and study the weak-coupling, macroscopic limit of the model, obtaining an exponential behavior at all times. The asymptotic dominance of the exponential behavior is representative of a purely stochastic evolution and can be derived quantum mechanically in the so-called van Hove's limit (which is a weak-coupling, macroscopic limit). At the same time, a temporal behavior of the exponential type, yielding a 'probability dissipation' is closely related to dephasing ('decoherence') effects and one can expect a close connection with a dissipative and irreversible behavior. We stress the central relevance of the problem of dissipation to the quantum measurement theory and to the general topic of decoherence.

  13. Exponential energy growth in a Fermi accelerator.

    PubMed

    Shah, Kushal; Turaev, Dmitry; Rom-Kedar, Vered

    2010-05-01

    An unbounded energy growth of particles bouncing off two-dimensional (2D) smoothly oscillating polygons is observed. Notably, such billiards have zero Lyapunov exponents in the static case. For a special 2D polygon geometry--a rectangle with a vertically oscillating horizontal bar--we show that this energy growth is not only unbounded but also exponential in time. For the energy averaged over an ensemble of initial conditions, we derive an a priori expression for the rate of the exponential growth as a function of the geometry and the ensemble type. We demonstrate numerically that the ensemble averaged energy indeed grows exponentially, at a close to the analytically predicted rate-namely, the process is controllable.

  14. Modeling aftershocks as a stretched exponential relaxation

    NASA Astrophysics Data System (ADS)

    Mignan, A.

    2015-11-01

    The decay rate of aftershocks has been modeled as a power law since the pioneering work of Omori in the late nineteenth century. Although other expressions have been proposed in recent decades to describe the temporal behavior of aftershocks, the number of model comparisons remains limited. After reviewing the aftershock models published from the late nineteenth century until today, I solely compare the power law, pure exponential and stretched exponential expressions defined in their simplest forms. By applying statistical methods recommended recently in applied mathematics, I show that all aftershock sequences tested in three regional earthquake catalogs (Southern and Northern California, Taiwan) and with three declustering techniques (nearest-neighbor, second-order moment, window methods) follow a stretched exponential instead of a power law. These results infer that aftershocks are due to a simple relaxation process, in accordance with most other relaxation processes observed in Nature.

  15. Exponential fitting BDF Runge Kutta algorithms

    NASA Astrophysics Data System (ADS)

    Vigo-Aguiar, J.; Martín-Vaquero, J.; Ramos, H.

    2008-01-01

    In other papers, the authors presented exponential fitting methods of BDF type. Now, these methods are used to derive some BDF-Runge-Kutta type formulas (of second-, third- and fourth-order), capable of the exact integration (with only round-off errors) of differential equations whose solutions are linear combinations of an exponential with parameter A and ordinary polynomials. Theorems of the truncation error reveal the good behavior of the new methods for stiff problems. Plots of their absolute stability regions that include the whole of the negative real axis are provided. Different procedures to find the parameter of the method are proposed, using these techniques there will not be necessary to compute the exponential matrix at each step, even when nonlinear problems are integrated. Numerical examples underscore the efficiency of the proposed codes, especially when they are integrating stiff problems.

  16. Method for exponentiating in cryptographic systems

    DOEpatents

    Brickell, Ernest F.; Gordon, Daniel M.; McCurley, Kevin S.

    1994-01-01

    An improved cryptographic method utilizing exponentiation is provided which has the advantage of reducing the number of multiplications required to determine the legitimacy of a message or user. The basic method comprises the steps of selecting a key from a preapproved group of integer keys g; exponentiating the key by an integer value e, where e represents a digital signature, to generate a value g.sup.e ; transmitting the value g.sup.e to a remote facility by a communications network; receiving the value g.sup.e at the remote facility; and verifying the digital signature as originating from the legitimate user. The exponentiating step comprises the steps of initializing a plurality of memory locations with a plurality of values g.sup.xi ; computi The United States Government has rights in this invention pursuant to Contract No. DE-AC04-76DP00789 between the Department of Energy and AT&T Company.

  17. In situ platelets formation into aqueous polymer colloids: The topochemical transformation from single to double layered hydroxide (LSH-LDH) uncovered.

    PubMed

    Stimpfling, Thomas; Langry, Arthur; Hintze-Bruening, Horst; Leroux, Fabrice

    2016-01-15

    Layered Single Hydroxide (LSH) of chemical composition Zn5(OH)8(acetate)2·nH2O is synthesized under in situ condition in an aqueous dispersion of an amphiphilic, carboxylate bearing polyester via a modified polyol route. The one-pot LSH generation yields agglomerates of well intercalated platelets, 9-10nm separated from each other. However the corresponding Layered Double Hydroxide (LDH) of formal composition Zn2Al(OH)6 (acetate)·nH2O is found to proceed via the formation of crystallized, similarly spaced LSH sheets in the neighborhood of amorphous Al rich domains as evidenced by X-ray diffraction and transmission electron micrographs. The initial phase segregation effaces over time while LSH platelets convert into the LDH phase. Fingerprinted by the change of in-plane cation accommodation, the associated topochemical reaction of the edge-sharing octahedral LSH platelets involves the transformation of metal lacunae, adjacently covered by one tetrahedral coordinated cation on each side to balance the negative surcharge, into fully occupied and monolayered platelets of edge-sharing octahedral LDH, the former voids being occupied by trivalent cations. This replenishing process of empty sites, coupled with the dissolution of tetrahedral sites is likely to be observed for the first time due to the presence of well separated, polymer intercalated platelets. TEM pictures vision crystal growth arising from the zone of the LSH edge-slab and by using solid state kinetics formalism the associated high activation energy of the first-order reaction agrees well with a plausible dissolution re-precipitation mechanism. The conversion of LSH into LDH platelets may be extended to others cations as Co(2+), Cu(2+), as well as the aluminum source (AlCl3) and the water-soluble polymer (NVP), thus indicating it is a new prevalent facet of LDH. Copyright © 2015 Elsevier Inc. All rights reserved.

  18. Attenuated Total Reflectance Fourier transform infrared spectroscopy for determination of Long Chain Free Fatty Acid concentration in oily wastewater using the double wavenumber extrapolation technique.

    PubMed

    Hao, Zisu; Malyala, Divya; Dean, Lisa; Ducoste, Joel

    2017-04-01

    Long Chain Free Fatty Acids (LCFFAs) from the hydrolysis of fat, oil and grease (FOG) are major components in the formation of insoluble saponified solids known as FOG deposits that accumulate in sewer pipes and lead to sanitary sewer overflows (SSOs). A Double Wavenumber Extrapolative Technique (DWET) was developed to simultaneously measure LCFFAs and FOG concentrations in oily wastewater suspensions. This method is based on the analysis of the Attenuated Total Reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) spectrum, in which the absorbance of carboxyl bond (1710cm(-1)) and triglyceride bond (1745cm(-1)) were selected as the characteristic wavenumbers for total LCFFAs and FOG, respectively. A series of experiments using pure organic samples (Oleic acid/Palmitic acid in Canola oil) were performed that showed a linear relationship between the absorption at these two wavenumbers and the total LCFFA. In addition, the DWET method was validated using GC analyses, which displayed a high degree of agreement between the two methods for simulated oily wastewater suspensions (1-35% Oleic acid in Canola oil/Peanut oil). The average determination error of the DWET approach was ~5% when the LCFFA fraction was above 10wt%, indicating that the DWET could be applied as an experimental method for the determination of both LCFFAs and FOG concentrations in oily wastewater suspensions. Potential applications of this DWET approach includes: (1) monitoring the LCFFAs and FOG concentrations in grease interceptor (GI) effluents for regulatory compliance; (2) evaluating alternative LCFFAs/FOG removal technologies; and (3) quantifying potential FOG deposit high accumulation zones in the sewer collection system.

  19. Nonuniform exponential dichotomies and Lyapunov functions

    NASA Astrophysics Data System (ADS)

    Barreira, Luis; Dragičević, Davor; Valls, Claudia

    2017-05-01

    For the nonautonomous dynamics defined by a sequence of bounded linear operators acting on an arbitrary Hilbert space, we obtain a characterization of the notion of a nonuniform exponential dichotomy in terms of quadratic Lyapunov sequences. We emphasize that, in sharp contrast with previous results, we consider the general case of possibly noninvertible linear operators, thus requiring only the invertibility along the unstable direction. As an application, we give a simple proof of the robustness of a nonuniform exponential dichotomy under sufficiently small linear perturbations.

  20. Designing efficient exponential integrators with EPIRK framework

    NASA Astrophysics Data System (ADS)

    Rainwater, Greg; Tokman, Mayya

    2017-07-01

    Exponential propagation iterative methods of Runge-Kutta type (EPIRK) provide a flexible framework to derive efficient exponential integrators for different types of ODE systems. Different classes of EPIRK methods can be constructed depending on the properties of the equations to be solved. Both classically and stiffly accurate EPIRK schemes can be derived. Flexibility of the order conditions allows to optimize coefficients to construct more efficient schemes. Particularly well-performing fourth-order stiffly accurate methods have been derived and applied to a number of problems. A new efficient three-stage fourth order method is presented and tested here using numerical examples.

  1. A method for nonlinear exponential regression analysis

    NASA Technical Reports Server (NTRS)

    Junkin, B. G.

    1971-01-01

    A computer-oriented technique is presented for performing a nonlinear exponential regression analysis on decay-type experimental data. The technique involves the least squares procedure wherein the nonlinear problem is linearized by expansion in a Taylor series. A linear curve fitting procedure for determining the initial nominal estimates for the unknown exponential model parameters is included as an integral part of the technique. A correction matrix was derived and then applied to the nominal estimate to produce an improved set of model parameters. The solution cycle is repeated until some predetermined criterion is satisfied.

  2. An Exponential Growth Learning Trajectory: Students' Emerging Understanding of Exponential Growth through Covariation

    ERIC Educational Resources Information Center

    Ellis, Amy B.; Ozgur, Zekiye; Kulow, Torrey; Dogan, Muhammed F.; Amidon, Joel

    2016-01-01

    This article presents an Exponential Growth Learning Trajectory (EGLT), a trajectory identifying and characterizing middle grade students' initial and developing understanding of exponential growth as a result of an instructional emphasis on covariation. The EGLT explicates students' thinking and learning over time in relation to a set of tasks…

  3. An Exponential Growth Learning Trajectory: Students' Emerging Understanding of Exponential Growth through Covariation

    ERIC Educational Resources Information Center

    Ellis, Amy B.; Ozgur, Zekiye; Kulow, Torrey; Dogan, Muhammed F.; Amidon, Joel

    2016-01-01

    This article presents an Exponential Growth Learning Trajectory (EGLT), a trajectory identifying and characterizing middle grade students' initial and developing understanding of exponential growth as a result of an instructional emphasis on covariation. The EGLT explicates students' thinking and learning over time in relation to a set of tasks…

  4. A secure double-image sharing scheme based on Shamir's three-pass protocol and 2D Sine Logistic modulation map in discrete multiple-parameter fractional angular transform domain

    NASA Astrophysics Data System (ADS)

    Sui, Liansheng; Duan, Kuaikuai; Liang, Junli

    2016-05-01

    A secure double-image sharing scheme is proposed by using the Shamir's three-pass protocol in the discrete multiple-parameter fractional angular transform domain. First, an enlarged image is formed by assembling two plain images successively in the horizontal direction and scrambled in the chaotic permutation process, in which the sequences of chaotic pairs are generated by the two-dimensional Sine Logistic modulation map. Second, the scrambled image is divided into two components which are used to constitute a complex image. One component is normalized and regarded as the phase part of the complex image as well as other is considered as the amplitude part. Finally, the complex image is shared between the sender and the receiver by using the Shamir's three-pass protocol, in which the discrete multiple-parameter fractional angular transform is used as the encryption function due to its commutative property. The proposed double-image sharing scheme has an obvious advantage that the key management is convenient without distributing the random phase mask keys in advance. Moreover, the security of the image sharing scheme is enhanced with the help of extra parameters of the discrete multiple-parameter fractional angular transform. To the best of our knowledge, this is the first report on integrating the Shamir's three-pass protocol with double-image sharing scheme in the information security field. Simulation results and security analysis verify the feasibility and effectiveness of the proposed scheme.

  5. Sparse Exponential Family Principal Component Analysis.

    PubMed

    Lu, Meng; Huang, Jianhua Z; Qian, Xiaoning

    2016-12-01

    We propose a Sparse exponential family Principal Component Analysis (SePCA) method suitable for any type of data following exponential family distributions, to achieve simultaneous dimension reduction and variable selection for better interpretation of the results. Because of the generality of exponential family distributions, the method can be applied to a wide range of applications, in particular when analyzing high dimensional next-generation sequencing data and genetic mutation data in genomics. The use of sparsity-inducing penalty helps produce sparse principal component loading vectors such that the principal components can focus on informative variables. By using an equivalent dual form of the formulated optimization problem for SePCA, we derive optimal solutions with efficient iterative closed-form updating rules. The results from both simulation experiments and real-world applications have demonstrated the superiority of our SePCA in reconstruction accuracy and computational efficiency over traditional exponential family PCA (ePCA), the existing Sparse PCA (SPCA) and Sparse Logistic PCA (SLPCA) algorithms.

  6. A Simple Mechanical Experiment on Exponential Growth

    ERIC Educational Resources Information Center

    McGrew, Ralph

    2015-01-01

    With a rod, cord, pulleys, and slotted masses, students can observe and graph exponential growth in the cord tension over a factor of increase as large as several hundred. This experiment is adaptable for use either in algebra-based or calculus-based physics courses, fitting naturally with the study of sliding friction. Significant parts of the…

  7. A note on the Jackson exponentiality test

    NASA Astrophysics Data System (ADS)

    Caeiro, Frederico; Marques, Filipe J.; Mateus, Ayana; Atal, Serra

    2016-12-01

    In this paper we revisit the Jackson exponentiality test. We study and provide functions in R language to compute theoretical moments, the distribution function and quantiles of the statistic test. Approximations to the exact distribution function and quantiles are also provided and their precision discussed. In addition, we provide an application of the Jackson test to real data.

  8. Graphical Models via Univariate Exponential Family Distributions

    PubMed Central

    Yang, Eunho; Ravikumar, Pradeep; Allen, Genevera I.; Liu, Zhandong

    2016-01-01

    Undirected graphical models, or Markov networks, are a popular class of statistical models, used in a wide variety of applications. Popular instances of this class include Gaussian graphical models and Ising models. In many settings, however, it might not be clear which subclass of graphical models to use, particularly for non-Gaussian and non-categorical data. In this paper, we consider a general sub-class of graphical models where the node-wise conditional distributions arise from exponential families. This allows us to derive multivariate graphical model distributions from univariate exponential family distributions, such as the Poisson, negative binomial, and exponential distributions. Our key contributions include a class of M-estimators to fit these graphical model distributions; and rigorous statistical analysis showing that these M-estimators recover the true graphical model structure exactly, with high probability. We provide examples of genomic and proteomic networks learned via instances of our class of graphical models derived from Poisson and exponential distributions. PMID:27570498

  9. A Simple Mechanical Experiment on Exponential Growth

    ERIC Educational Resources Information Center

    McGrew, Ralph

    2015-01-01

    With a rod, cord, pulleys, and slotted masses, students can observe and graph exponential growth in the cord tension over a factor of increase as large as several hundred. This experiment is adaptable for use either in algebra-based or calculus-based physics courses, fitting naturally with the study of sliding friction. Significant parts of the…

  10. Non-uniform exponential tension splines

    NASA Astrophysics Data System (ADS)

    Bosner, Tina; Rogina, Mladen

    2007-11-01

    We describe explicitly each stage of a numerically stable algorithm for calculating with exponential tension B-splines with non-uniform choice of tension parameters. These splines are piecewisely in the kernel of D 2(D 2?p 2), where D stands for ordinary derivative, defined on arbitrary meshes, with a different choice of the tension parameter p on each interval. The algorithm provides values of the associated B-splines and their generalized and ordinary derivatives by performing positive linear combinations of positive quantities, described as lower-order exponential tension splines. We show that nothing else but the knot insertion algorithm and good approximation of a few elementary functions is needed to achieve machine accuracy. The underlying theory is that of splines based on Chebyshev canonical systems which are not smooth enough to be ECC-systems. First, by de Boor algorithm we construct exponential tension spline of class C 1, and then we use quasi-Oslo type algorithms to evaluate classical non-uniform C 2 tension exponential splines.

  11. Intersection of the Exponential and Logarithmic Curves

    ERIC Educational Resources Information Center

    Boukas, Andreas; Valahas, Theodoros

    2009-01-01

    The study of the number of intersection points of y = a[superscript x] and y = log[subscript a]x can be an interesting topic to present in a single-variable calculus class. In this article, the authors present a classroom presentation outline involving the basic algebra and the elementary calculus of the exponential and logarithmic functions. The…

  12. Simple exponential functions describing the absorbance bands of visual pigment spectra.

    PubMed

    Stavenga, D G; Smits, R P; Hoenders, B J

    1993-05-01

    Literature data for visual pigment spectra are formally treated by assuming that the spectra consist of a summation of absorbance bands, that the shape of the bands is invariant according to the Mansfield-MacNichol transform and that this shape is described by simple exponential functions. A new template for constructing visual pigment spectra from peak wavelengths is derived.

  13. An approximation theorem for entire functions of exponential type and stability of zero sequences

    SciTech Connect

    Khabibullin, B N

    2004-02-28

    Let L be an entire function of exponential type in C with indicator function h{sub L}; let {lambda}={l_brace}{lambda}{sub n}{r_brace}, n=1,2,..., be a subsequence of zeros of the entire function of exponential type L{ne}0; let {gamma}={l_brace}{gamma}{sub n}{r_brace} be a complex number sequence and assume that {sigma}{sub n}|1/{lambda}{sub n} - 1/{gamma}{sub n}|<{infinity}. A simple construction of a sequence of entire functions of exponential type {l_brace}L{sub n}{r_brace} transforming {lambda} into a subsequence {gamma} of zeros of an entire function of exponential type G{ne}0 such that h{sub G}=h{sub L} is put forward (an approximation theorem). This result is applied to stability problems of zero sequences and non-uniqueness sequences for spaces of entire functions of exponential type with constraints on the indicators and to the problem of the stability of the completeness property of exponential systems in the space of germs of analytic functions on a compact convex set.

  14. Perturbing Misiurewicz Parameters in the Exponential Family

    NASA Astrophysics Data System (ADS)

    Dobbs, Neil

    2015-04-01

    In one-dimensional real and complex dynamics, a map whose post-singular (or post-critical) set is bounded and uniformly repelling is often called a Misiurewicz map. In results hitherto, perturbing a Misiurewicz map is likely to give a non-hyperbolic map, as per Jakobson's Theorem for unimodal interval maps. This is despite genericity of hyperbolic parameters (at least in the interval setting). We show the contrary holds in the complex exponential family Misiurewicz maps are Lebesgue density points for hyperbolic parameters. As a by-product, we also show that Lyapunov exponents almost never exist for exponential Misiurewicz maps. The lower Lyapunov exponent is -∞ almost everywhere. The upper Lyapunov exponent is non-negative and depends on the choice of metric.

  15. Likelihood Estimation for Generalized Mixed Exponential Distributions.

    DTIC Science & Technology

    1984-07-01

    specified beforehand. 23 S. . ... .- ~T§777 ~"~𔄁~ 7’.7 . -- ." F0 * 0 REFERENCES L. Armijo, "Minimization of Functions Having Lipschitz Continuous...and F. W. Fairman, Exponential Approximation via a Closed Form Gauss-Newton Method, IEEE Trans. Circuit Theory, CT-20 (1973), pp. 361-369. A. R...engineering disciplines of Chemical, Civil, Electrical , and Mechanical and Aerospace to newer, more specialized fields of Biomedical Engineering

  16. Exponential integration algorithms applied to viscoplasticity

    NASA Technical Reports Server (NTRS)

    Freed, Alan D.; Walker, Kevin P.

    1991-01-01

    Four, linear, exponential, integration algorithms (two implicit, one explicit, and one predictor/corrector) are applied to a viscoplastic model to assess their capabilities. Viscoplasticity comprises a system of coupled, nonlinear, stiff, first order, ordinary differential equations which are a challenge to integrate by any means. Two of the algorithms (the predictor/corrector and one of the implicits) give outstanding results, even for very large time steps.

  17. A Simple Mechanical Experiment on Exponential Growth

    NASA Astrophysics Data System (ADS)

    McGrew, Ralph

    2015-04-01

    With a rod, cord, pulleys, and slotted masses, students can observe and graph exponential growth in the cord tension over a factor of increase as large as several hundred. This experiment is adaptable for use either in algebra-based or calculus-based physics courses, fitting naturally with the study of sliding friction. Significant parts of the activity are accessible to students in physical science and environmental science courses.

  18. Exponential DNA Replication by Laminar Convection

    NASA Astrophysics Data System (ADS)

    Braun, Dieter; Goddard, Noel L.; Libchaber, Albert

    2003-10-01

    It is shown that laminar thermal convection can drive a chain reaction of DNA replication. The convection is triggered by a constant horizontal temperature gradient, moving molecules along stationary paths between hot and cold regions. This implements the temperature cycling for the classical polymerase chain reaction (PCR). The amplification is shown to be exponential and reaches 100 000-fold gains within 25min. Besides direct applications, the mechanism might have implications for the molecular evolution of life.

  19. Method for exponentiating in cryptographic systems

    SciTech Connect

    Brickell, E.F.; Gordon, D.M.; McCurley, K.S.

    1992-12-31

    An improved cryptographic method utilizing exponentiation is provided which has the advantage of reducing the number of multiplications required to determine the legitimacy of a message or user. The basic method comprises the steps of selecting a key from a pre-approved group of integer keys g; exponentiating the key by an integer value e, where e represents a digital signature, to generate a value g{sup e}; transmitting the value g{sup e} to a remote facility by a communications network; receiving the value g{sup e} at the remote facility; and verifying the digital signature as originating from the legitimate user. The exponentiating step comprises the steps of initializing a plurality of memory locations with a plurality of values g{sup xi}, computing a{sub i} representations for a integer base b, where a{sub i} represents the weighing factor of the ith digit of the integer e; computing the individual values of c{sub d} according to the rule: c{sub d}={product}a{sub i}=d g{sup x {sub i}}; and computing the product of {product}{sup h}/{sub d=1} c{sub d}{sup d} from the stored values of from the plurality of memory locations so as to determine a value for g{sup e}.

  20. Dynamo theory, vorticity generation, and exponential stretching.

    PubMed

    Friedlander, Susan; Vishik, Misha M.

    1991-08-01

    A discussion is given of the analogy between the dynamo equation for the generation of a magnetic field by the motion of an electrically conducting fluid and the equation for the evolution of vorticity of a viscous fluid. In both cases exponential stretching is an important feature of the underlying instability problem. For the "fast" dynamo problem, the existence of exponential stretching (i.e., the positivity of the Lyapunov exponent) somewhere in the flow is a necessary condition when the flow is smooth. An example is presented of a flow with exponential stretching (an Anosov flow) that supports fast dynamo action. A parallel treatment is described for the linearized Navier-Stokes equations for the motion of a viscous fluid. In this problem the analogous necessary condition for "fast vorticity generation" is the existence of some instability in the corresponding Euler (i.e., inviscid) equation. Dynamo theory methods give a second related result, namely a universal geometric estimate from below on the growth rate of a small perturbation in an inviscid fluid. This bound gives an effective sufficient condition for local instability for Eulers equations. In particular, it is proved that a steady flow with a hyperbolic stagnation point is unstable. The growth rate of an infinitesimal perturbation in a metric with derivatives depends on this metric. This dependence is completely described.

  1. Determining the parameters of the fractional exponential heredity kernels of linear viscoelastic materials

    NASA Astrophysics Data System (ADS)

    Golub, V. P.; Fernati, P. V.; Lyashenko, Ya. G.

    2008-09-01

    The parameters of the fractional exponential creep and relaxation kernels of linear viscoelastic materials are determined. Methods that approximate the kernel by using the Mittag-Leffler function, the Laplace-Carson transform, and direct approximation of the creep function by the original equation are analyzed. The parameters of fractional exponential kernels are determined for aramid fibers, parapolyamide fibers, glass-reinforced plastic, and polymer concrete. It is shown that the kernel parameters calculated through the direct approximation of the creep function provide the best agreement between theory and experiment. The methods are experimentally validated for constant-stress and variable-stress loading in the modes of additional loading and complete unloading

  2. Exponential quantum spreading in a class of kicked rotor systems near high-order resonances

    NASA Astrophysics Data System (ADS)

    Wang, Hailong; Wang, Jiao; Guarneri, Italo; Casati, Giulio; Gong, Jiangbin

    2013-11-01

    Long-lasting exponential quantum spreading was recently found in a simple but very rich dynamical model, namely, an on-resonance double-kicked rotor model [J. Wang, I. Guarneri, G. Casati, and J. B. Gong, Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.107.234104 107, 234104 (2011)]. The underlying mechanism, unrelated to the chaotic motion in the classical limit but resting on quasi-integrable motion in a pseudoclassical limit, is identified for one special case. By presenting a detailed study of the same model, this work offers a framework to explain long-lasting exponential quantum spreading under much more general conditions. In particular, we adopt the so-called “spinor” representation to treat the kicked-rotor dynamics under high-order resonance conditions and then exploit the Born-Oppenheimer approximation to understand the dynamical evolution. It is found that the existence of a flat band (or an effectively flat band) is one important feature behind why and how the exponential dynamics emerges. It is also found that a quantitative prediction of the exponential spreading rate based on an interesting and simple pseudoclassical map may be inaccurate. In addition to general interests regarding the question of how exponential behavior in quantum systems may persist for a long time scale, our results should motivate further studies toward a better understanding of high-order resonance behavior in δ-kicked quantum systems.

  3. Exponentially small dependence of the Q-function on quantum coherence

    NASA Astrophysics Data System (ADS)

    Brewster, R. A.; Franson, J. D.

    We show that the Huisimi Q-function has an exponentially small dependence on the relative phase of a Schrodinger cat state, as might be expected from its definition. This raises the question as to whether or not the Q-function provides a complete description of the coherence of quantum states. We calculate the Q-function for a cat state and then invert it by first calculating the Glauber-Sudarshan P-function using a Fourier transform, which can then be used to calculate the state itself. This process is shown to multiply the small phase-dependent terms in the Q-function by an exponentially large factor as needed in order to obtain the original state once again. This exponential factor is strongly degraded by decoherence, such as by amplification of the original state. Funded by the Office of Naval Research.

  4. Applications of an exponential finite difference technique

    NASA Technical Reports Server (NTRS)

    Handschuh, Robert F.; Keith, Theo G., Jr.

    1988-01-01

    An exponential finite difference scheme first presented by Bhattacharya for one dimensional unsteady heat conduction problems in Cartesian coordinates was extended. The finite difference algorithm developed was used to solve the unsteady diffusion equation in one dimensional cylindrical coordinates and was applied to two and three dimensional conduction problems in Cartesian coordinates. Heat conduction involving variable thermal conductivity was also investigated. The method was used to solve nonlinear partial differential equations in one and two dimensional Cartesian coordinates. Predicted results are compared to exact solutions where available or to results obtained by other numerical methods.

  5. Exponential expansion: galactic destiny or technological hubris?

    NASA Astrophysics Data System (ADS)

    Finney, B. R.

    Is it our destiny to expand exponentially to populate the galaxy, or is such a vision but an extreme example of technological hubris? The overall record of human evolution and dispersion over the Earth can be cited to support the view that we are a uniquely expansionary and technological animal bound for the stars, yet an examination of the fate of individual migrations and exploratory initiatives raises doubts. Although it may be in keeping with our hubristic nature to predict ultimate galactic expansion, there is no way to specify how far expansionary urges may drive our spacefaring descendants.

  6. Mixtures of multivariate power exponential distributions.

    PubMed

    Dang, Utkarsh J; Browne, Ryan P; McNicholas, Paul D

    2015-12-01

    An expanded family of mixtures of multivariate power exponential distributions is introduced. While fitting heavy-tails and skewness have received much attention in the model-based clustering literature recently, we investigate the use of a distribution that can deal with both varying tail-weight and peakedness of data. A family of parsimonious models is proposed using an eigen-decomposition of the scale matrix. A generalized expectation-maximization algorithm is presented that combines convex optimization via a minorization-maximization approach and optimization based on accelerated line search algorithms on the Stiefel manifold. Lastly, the utility of this family of models is illustrated using both toy and benchmark data.

  7. Preconditioned implicit-exponential integrators (IMEXP) for stiff PDEs

    NASA Astrophysics Data System (ADS)

    Luan, Vu Thai; Tokman, Mayya; Rainwater, Greg

    2017-04-01

    We propose two new classes of time integrators for stiff DEs: the implicit exponential (IMEXP) and the hybrid exponential methods. In contrast to the existing exponential schemes, the new methods offer significant computational advantages when used with preconditioners. Any preconditioner can be used with any of these new schemes. This leads to a broader applicability of exponential methods. The proof of convergence of these integrators and numerical demonstration of their efficiency are presented.

  8. The LEM exponential integrator for advection-diffusion-reaction equations

    NASA Astrophysics Data System (ADS)

    Caliari, Marco; Vianello, Marco; Bergamaschi, Luca

    2007-12-01

    We implement a second-order exponential integrator for semidiscretized advection-diffusion-reaction equations, obtained by coupling exponential-like Euler and Midpoint integrators, and computing the relevant matrix exponentials by polynomial interpolation at Leja points. Numerical tests on 2D models discretized in space by finite differences or finite elements, show that the Leja-Euler-Midpoint (LEM) exponential integrator can be up to 5 times faster than a classical second-order implicit solver.

  9. Exponential Size Distribution of von Willebrand Factor

    PubMed Central

    Lippok, Svenja; Obser, Tobias; Müller, Jochen P.; Stierle, Valentin K.; Benoit, Martin; Budde, Ulrich; Schneppenheim, Reinhard; Rädler, Joachim O.

    2013-01-01

    Von Willebrand Factor (VWF) is a multimeric protein crucial for hemostasis. Under shear flow, it acts as a mechanosensor responding with a size-dependent globule-stretch transition to increasing shear rates. Here, we quantify for the first time, to our knowledge, the size distribution of recombinant VWF and VWF-eGFP using a multilateral approach that involves quantitative gel analysis, fluorescence correlation spectroscopy, and total internal reflection fluorescence microscopy. We find an exponentially decaying size distribution of multimers for recombinant VWF as well as for VWF derived from blood samples in accordance with the notion of a step-growth polymerization process during VWF biosynthesis. The distribution is solely described by the extent of polymerization, which was found to be reduced in the case of the pathologically relevant mutant VWF-IIC. The VWF-specific protease ADAMTS13 systematically shifts the VWF size distribution toward smaller sizes. This dynamic evolution is monitored using fluorescence correlation spectroscopy and compared to a computer simulation of a random cleavage process relating ADAMTS13 concentration to the degree of VWF breakdown. Quantitative assessment of VWF size distribution in terms of an exponential might prove to be useful both as a valuable biophysical characterization and as a possible disease indicator for clinical applications. PMID:24010664

  10. Are Urban-Canopy Velocity Profiles Exponential?

    NASA Astrophysics Data System (ADS)

    Castro, Ian P.

    2017-09-01

    Using analyses of data from extant direct numerical simulations and large-eddy simulations of boundary-layer and channel flows over and within urban-type canopies, sectional drag forces, Reynolds and dispersive shear stresses are examined for a range of roughness densities. Using the spatially-averaged mean velocity profiles these quantities allow deduction of the canopy mixing length and sectional drag coefficient. It is shown that the common assumptions about the behaviour of these quantities, needed to produce an analytical model for the canopy velocity profile, are usually invalid, in contrast to what is found in typical vegetative (e.g. forest) canopies. The consequence is that an exponential shape of the spatially-averaged mean velocity profile within the canopy cannot normally be expected, as indeed the data demonstrate. Nonetheless, recent canopy models that allow prediction of the roughness length appropriate for the inertial layer's logarithmic profile above the canopy do not seem to depend crucially on their (invalid) assumption of an exponential profile within the canopy.

  11. Prion disease: exponential growth requires membrane binding.

    PubMed

    Cox, Daniel L; Sing, Rajiv R P; Yang, Sichun

    2006-06-01

    A hallmark feature of prions, whether in mammals or yeast and fungi, is exponential growth associated with fission or autocatalysis of protein aggregates. We have employed a rigorous kinetic analysis to recent data from transgenic mice lacking a glycosylphosphatidylinositol membrane anchor to the normal cellular PrP(C) protein, which show that toxicity requires the membrane binding. We find as well that the membrane is necessary for exponential growth of prion aggregates; without it, the kinetics is simply the quadratic-in-time growth characteristic of linear elongation as observed frequently in in vitro amyloid growth experiments with other proteins. This requires both: i), a substantial intercellular concentration of anchorless PrP(C), and ii), a concentration of small scrapies seeding aggregates from the inoculum, which remains relatively constant with time and exceeds the concentration of large polymeric aggregates. We also can explain via this analysis why mice heterozygous for the anchor-full/anchor-free PrP(C) proteins have more rapid incubation than mice heterozygous for anchor-full/null PrP(C), and contrast the mammalian membrane associated fission or autocatalysis with the membrane free fission of yeast and fungal prions.

  12. Measuring Entanglement Spectrum via Density Matrix Exponentiation

    NASA Astrophysics Data System (ADS)

    Zhu, Guanyu; Seif, Alireza; Pichler, Hannes; Zoller, Peter; Hafezi, Mohammad

    Entanglement spectrum (ES), the eigenvalues of the reduced density matrix of a subsystem, serves as a powerful theoretical tool to study many-body systems. For example, the gap and degeneracies of the entanglement spectrum have been used to identify various topological phases. However, the usefulness of such a concept in real experiments has been debated, since it is believed that obtaining the ES requires full state tomography, at a cost which exponentially grows with the systems size. Inspired by a recent density matrix exponentiation technique, we propose a scheme to measure ES by evolving the system with a Hamiltonian that is the subsystem's own reduced density matrix. Such a time evolution can be induced by an ancilla photon that is coupled to multiple qubits at the same time. The phase associated with the time evolution can be detected and converted into ES through either a digital or an analogue scheme. The digital scheme involves a modified quantum phase estimation algorithm based on random time evolution, while the analogue scheme is in the spirit of Ramsey interferometry. Both schemes are not limited by the size of the system, and are especially sensitive to the gap and degeneracies. We also discuss the implementation in cavity/circuit-QED and ion trap systems.

  13. Are Urban-Canopy Velocity Profiles Exponential?

    NASA Astrophysics Data System (ADS)

    Castro, Ian P.

    2017-06-01

    Using analyses of data from extant direct numerical simulations and large-eddy simulations of boundary-layer and channel flows over and within urban-type canopies, sectional drag forces, Reynolds and dispersive shear stresses are examined for a range of roughness densities. Using the spatially-averaged mean velocity profiles these quantities allow deduction of the canopy mixing length and sectional drag coefficient. It is shown that the common assumptions about the behaviour of these quantities, needed to produce an analytical model for the canopy velocity profile, are usually invalid, in contrast to what is found in typical vegetative (e.g. forest) canopies. The consequence is that an exponential shape of the spatially-averaged mean velocity profile within the canopy cannot normally be expected, as indeed the data demonstrate. Nonetheless, recent canopy models that allow prediction of the roughness length appropriate for the inertial layer's logarithmic profile above the canopy do not seem to depend crucially on their (invalid) assumption of an exponential profile within the canopy.

  14. Human-chimpanzee alignment: ortholog exponentials and paralog power laws.

    PubMed

    Gao, Kun; Miller, Jonathan

    2014-12-01

    Genomic subsequences conserved between closely related species such as human and chimpanzee exhibit an exponential length distribution, in contrast to the algebraic length distribution observed for sequences shared between distantly related genomes. We find that the former exponential can be further decomposed into an exponential component primarily composed of orthologous sequences, and a truncated algebraic component primarily composed of paralogous sequences.

  15. Exponential-Krylov methods for ordinary differential equations

    NASA Astrophysics Data System (ADS)

    Tranquilli, Paul; Sandu, Adrian

    2014-12-01

    This paper develops a new family of exponential time discretization methods called exponential-Krylov (EXPK). The new schemes treat the time discretization and the Krylov-based approximation of exponential matrix-vector products as a single computational process. The classical order conditions theory developed herein accounts for both the temporal and the Krylov approximation errors. Unlike traditional exponential schemes, EXPK methods require the construction of only a single Krylov space at each timestep. The number of basis vectors that guarantee the temporal order of accuracy does not depend on the application at hand. Numerical results show favorable properties of EXPK methods when compared to current exponential schemes.

  16. Boundary layer stagnation-point flow and heat transfer past a permeable exponentially shrinking sheet

    NASA Astrophysics Data System (ADS)

    Kasmuri, Juliana; Bachok, Norfifah; Ishak, Anuar

    2013-09-01

    An analysis is carried out to investigate the steady two-dimensional stagnation-point flow past a permeable exponentially stretching/shrinking sheet in its own plane. Using a similarity transformation, the governing mathematical equations are transformed into coupled, nonlinear ordinary differential equations which are then solved numerically. Effects of uniform suction and injection on the flow field and heat transfer characteristics are thoroughly examined. Different from a stretching sheet, it is found that the solutions for a shrinking sheet are non-unique. The range of the stretching/shrinking parameter where the similarity solution exists is larger for the exponentially stretching/shrinking case compared to the linearly stretching/shrinking case. The results indicate that suction delays the boundary layer separation, while injection accelerates it.

  17. Seislet-based morphological component analysis using scale-dependent exponential shrinkage

    NASA Astrophysics Data System (ADS)

    Yang, Pengliang; Fomel, Sergey

    2015-07-01

    Morphological component analysis (MCA) is a powerful tool used in image processing to separate different geometrical components (cartoons and textures, curves and points etc.). MCA is based on the observation that many complex signals may not be sparsely represented using only one dictionary/transform, however can have sparse representation by combining several over-complete dictionaries/transforms. In this paper we propose seislet-based MCA for seismic data processing. MCA algorithm is reformulated in the shaping-regularization framework. Successful seislet-based MCA depends on reliable slope estimation of seismic events, which is done by plane-wave destruction (PWD) filters. An exponential shrinkage operator unifies many existing thresholding operators and is adopted in scale-dependent shaping regularization to promote sparsity. Numerical examples demonstrate a superior performance of the proposed exponential shrinkage operator and the potential of seislet-based MCA in application to trace interpolation and multiple removal.

  18. Generalized exponential function and discrete growth models

    NASA Astrophysics Data System (ADS)

    Souto Martinez, Alexandre; Silva González, Rodrigo; Lauri Espíndola, Aquino

    2009-07-01

    Here we show that a particular one-parameter generalization of the exponential function is suitable to unify most of the popular one-species discrete population dynamic models into a simple formula. A physical interpretation is given to this new introduced parameter in the context of the continuous Richards model, which remains valid for the discrete case. From the discretization of the continuous Richards’ model (generalization of the Gompertz and Verhulst models), one obtains a generalized logistic map and we briefly study its properties. Notice, however that the physical interpretation for the introduced parameter persists valid for the discrete case. Next, we generalize the (scramble competition) θ-Ricker discrete model and analytically calculate the fixed points as well as their stabilities. In contrast to previous generalizations, from the generalized θ-Ricker model one is able to retrieve either scramble or contest models.

  19. Poissonian renormalizations, exponentials, and power laws.

    PubMed

    Eliazar, Iddo

    2013-05-01

    This paper presents a comprehensive "renormalization study" of Poisson processes governed by exponential and power-law intensities. These Poisson processes are of fundamental importance, as they constitute the very bedrock of the universal extreme-value laws of Gumbel, Fréchet, and Weibull. Applying the method of Poissonian renormalization we analyze the emergence of these Poisson processes, unveil their intrinsic dynamical structures, determine their domains of attraction, and characterize their structural phase transitions. These structural phase transitions are shown to be governed by uniform and harmonic intensities, to have universal domains of attraction, to uniquely display intrinsic invariance, and to be intimately connected to "white noise" and to "1/f noise." Thus, we establish a Poissonian explanation to the omnipresence of white and 1/f noises.

  20. An exponentiation method for XML element retrieval.

    PubMed

    Wichaiwong, Tanakorn

    2014-01-01

    XML document is now widely used for modelling and storing structured documents. The structure is very rich and carries important information about contents and their relationships, for example, e-Commerce. XML data-centric collections require query terms allowing users to specify constraints on the document structure; mapping structure queries and assigning the weight are significant for the set of possibly relevant documents with respect to structural conditions. In this paper, we present an extension to the MEXIR search system that supports the combination of structural and content queries in the form of content-and-structure queries, which we call the Exponentiation function. It has been shown the structural information improve the effectiveness of the search system up to 52.60% over the baseline BM25 at MAP.

  1. Exponential networks and representations of quivers

    NASA Astrophysics Data System (ADS)

    Eager, Richard; Selmani, Sam Alexandre; Walcher, Johannes

    2017-08-01

    We study the geometric description of BPS states in supersymmetric theories with eight supercharges in terms of geodesic networks on suitable spectral curves. We lift and extend several constructions of Gaiotto-Moore-Neitzke from gauge theory to local Calabi-Yau threefolds and related models. The differential is multi-valued on the covering curve and features a new type of logarithmic singularity in order to account for D0-branes and non-compact D4-branes, respectively. We describe local rules for the three-way junctions of BPS trajectories relative to a particular framing of the curve. We reproduce BPS quivers of local geometries and illustrate the wall-crossing of finite-mass bound states in several new examples. We describe first steps toward understanding the spectrum of framed BPS states in terms of such "exponential networks".

  2. An exponential multireference wave-function Ansatz

    SciTech Connect

    Hanrath, Michael

    2005-08-22

    An exponential multireference wave-function Ansatz is formulated. In accordance with the state universal coupled-cluster Ansatz of Jeziorski and Monkhorst [Phys. Rev. A 24, 1668 (1981)] the approach uses a reference specific cluster operator. In order to achieve state selectiveness the excitation- and reference-related amplitude indexing of the state universal Ansatz is replaced by an indexing which is based on excited determinants. There is no reference determinant playing a particular role. The approach is size consistent, coincides with traditional single-reference coupled cluster if applied to a single-reference, and converges to full configuration interaction with an increasing cluster operator excitation level. Initial applications on BeH{sub 2}, CH{sub 2}, Li{sub 2}, and nH{sub 2} are reported.

  3. Fluctuation Bounds in the Exponential Bricklayers Process

    NASA Astrophysics Data System (ADS)

    Balázs, Márton; Komjáthy, Júlia; Seppäläinen, Timo

    2012-04-01

    This paper is the continuation of our earlier paper (Balázs et al. in Ann. Inst. Henri Poincaré Probab. Stat. 48(1):151-187, 2012), where we proved t 1/3-order of current fluctuations across the characteristics in a class of one dimensional interacting systems with one conserved quantity. We also claimed two models with concave hydrodynamic flux which satisfied the assumptions which made our proof work. In the present note we show that the totally asymmetric exponential bricklayers process also satisfies these assumptions. Hence this is the first example with convex hydrodynamics of a model with t 1/3-order current fluctuations across the characteristics. As such, it further supports the idea of universality regarding this scaling.

  4. Arsenic for the fool: an exponential connection.

    PubMed

    Dani, Sergio U

    2010-03-15

    Anthropogenic arsenic is insidiously building up together with natural arsenic to a level unprecedented in the history of mankind. Arsenopyrite (FeAsS) is the principal ore of arsenic and gold in hard rock mines; it is formed by a coupled substitution of sulphur by arsenic in the structure of pyrite (FeS(2)) - nicknamed "fool's gold". Other important sources of anthropogenic arsenic are fossil fuels such as coal and oil. Here I report on the first indication that the environmental concentration of total arsenic in topsoils - in the 7-18ppm range - is exponentially related to the prevalence and mortality of Alzheimer's disease and other dementias in European countries. This evidence defies the imputed absence of verified cases of human morbidity or mortality resulting from exposure to low-level arsenic in topsoils.

  5. Exponential Approximations Using Fourier Series Partial Sums

    NASA Technical Reports Server (NTRS)

    Banerjee, Nana S.; Geer, James F.

    1997-01-01

    The problem of accurately reconstructing a piece-wise smooth, 2(pi)-periodic function f and its first few derivatives, given only a truncated Fourier series representation of f, is studied and solved. The reconstruction process is divided into two steps. In the first step, the first 2N + 1 Fourier coefficients of f are used to approximate the locations and magnitudes of the discontinuities in f and its first M derivatives. This is accomplished by first finding initial estimates of these quantities based on certain properties of Gibbs phenomenon, and then refining these estimates by fitting the asymptotic form of the Fourier coefficients to the given coefficients using a least-squares approach. It is conjectured that the locations of the singularities are approximated to within O(N(sup -M-2), and the associated jump of the k(sup th) derivative of f is approximated to within O(N(sup -M-l+k), as N approaches infinity, and the method is robust. These estimates are then used with a class of singular basis functions, which have certain 'built-in' singularities, to construct a new sequence of approximations to f. Each of these new approximations is the sum of a piecewise smooth function and a new Fourier series partial sum. When N is proportional to M, it is shown that these new approximations, and their derivatives, converge exponentially in the maximum norm to f, and its corresponding derivatives, except in the union of a finite number of small open intervals containing the points of singularity of f. The total measure of these intervals decreases exponentially to zero as M approaches infinity. The technique is illustrated with several examples.

  6. An exponential modeling algorithm for protein structure completion by X-ray crystallography.

    PubMed

    Shneerson, V L; Wild, D L; Saldin, D K

    2001-03-01

    An exponential modeling algorithm is developed for protein structure completion by X-ray crystallography and tested on experimental data from a 59-residue protein. An initial noisy difference Fourier map of missing residues of up to half of the protein is transformed by the algorithm into one that allows easy identification of the continuous tube of electron density associated with that polypeptide chain. The method incorporates the paradigm of phase hypothesis generation and cross validation within an automated scheme.

  7. Stretched exponential relaxation of piezovoltages in wet bovine bone.

    PubMed

    Xu, Lianyun; Hou, Zhende; Fu, Donghui; Qin, Qing-Hua; Wang, Yihan

    2015-01-01

    It is important to determine the amplitude and variation characteristics of piezovoltage in wet bone, which can, in turn, be taken as a basis for studying whether electrical signals induced by external forces can affect the growth of bone cells. This work measured the characteristics of piezoelectric effects under dynamic and static loading. The results show that the variations of piezovoltage in wet bone in both loading and load holding periods follow a stretched exponential relaxation law, and the relaxation time constants of the piezovoltages are much larger than those of dry bone. This finding means that the active time of piezovoltage in wet bone is much longer than that of dry bone. Regardless of the loading and load holding processes, continuously increasing deformation in wet bone caused piezoelectric charges to be continuously induced and increased the dielectric constant of wet bone along with the deformation process. In general, compared with piezovoltage in dry bone, that in wet bone had lower amplitude and could exist for a longer duration. It can be inferred, therefore, that piezoelectricity might create coupling with the streaming potential in bone by changing the thickness of the double electrode layer. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Stagnation-point flow and heat transfer over an exponentially shrinking sheet: A stability analysis

    NASA Astrophysics Data System (ADS)

    Ismail, Nurul Syuhada; Arifin, Norihan Md.; Bachok, Norfifah; Mahiddin, Norhasimah

    2016-06-01

    Numerical solutions for the stagnation-point flow and heat transfer over an exponentially shrinking sheet have been investigated. The governing boundary layer equations are transformed into an ordinary differential equation using a non-similar transformation. By using the bvp4c solver in MATLAB, the results of the equations can be solved numerically. Numerical results indicate that in certain parameter, the non-unique solutions for the velocity and the temperature do exist. A linear stability analysis shows that only one solution is linearly stable otherwise is unstable. Then, the stability analysis is performed to identify which solution is stable between the two non-unique solutions.

  9. Global exponential periodicity and stability of recurrent neural networks with multi-proportional delays.

    PubMed

    Zhou, Liqun; Zhang, Yanyan

    2016-01-01

    In this paper, a class of recurrent neural networks with multi-proportional delays is studied. The nonlinear transformation transforms a class of recurrent neural networks with multi-proportional delays into a class of recurrent neural networks with constant delays and time-varying coefficients. By constructing Lyapunov functional and establishing the delay differential inequality, several delay-dependent and delay-independent sufficient conditions are derived to ensure global exponential periodicity and stability of the system. And several examples and their simulations are given to illustrate the effectiveness of obtained results.

  10. [Comparative study of the replication difference of HearNPV in infected exponential and stationary host cells].

    PubMed

    Dai, Wen-Tao; Han, Xiao; Wang, Hua-Lin; Hu, Zhi-Hong; Deng, Fei

    2007-09-01

    Real-time quantitative PCR was used to characterize HearNPV DNA replication in exponential and stationary phases of HzAM1 cells. Results showed that the doubling time of HzAM1 cells was 22 h in exponential phases. Most of the exponential cells were in S phase (48.6%), and most of the stationary cells in G2/M phase (72.6%). The replication of viral DNA was completed within 60 h post infection (h p. i.) in different phases of HzAM1 cells. During 14 to 20 h p. i., the doubling time of HearNPV replica-tion was 1.8 h in exponential cells and 1.9 h in stationary cells, and no significant difference was found between them. But the amounts of BV entering and releasing, the final progeny virions and viral protein products in the infected exponential phase cells were obviously higher than that in the stationary phase cells. 25% of the total synthesized viral DNAs were released from infected exponential phase cells, but on-ly 13% from the infected stationary phase cells. Viral DNA started to be replicated from 7-8 h p. i. both in infected exponential phase and in stationary phase cells. But in infected exponential phase cells, BVs were started to release from 18-20 h p. i., and BVs were started to release from 22-25 h p. i. from infected sta-tionary phase cells. During 30-60 h p. i., the BV releasing rate was about 483 copies/cell/h in the expo-nential phase cells, but was 100 copies/cell/h in the stationary-phase cells. The initial viral DNA entering into exponential phase cells was much more than that entered into the stationary phase cells. The data of cell membrane fluidity at exponential and stationary phases suggested that the fluidity of cell membrane played an important role during virus entry.

  11. Transformation of light double cones in the human retina: the origin of trichromatism, of 4D-spatiotemporal vision, and of patchwise 4D Fourier transformation in Talbot imaging

    NASA Astrophysics Data System (ADS)

    Lauinger, Norbert

    1997-09-01

    The interpretation of the 'inverted' retina of primates as an 'optoretina' (a light cones transforming diffractive cellular 3D-phase grating) integrates the functional, structural, and oscillatory aspects of a cortical layer. It is therefore relevant to consider prenatal developments as a basis of the macro- and micro-geometry of the inner eye. This geometry becomes relevant for the postnatal trichromatic synchrony organization (TSO) as well as the adaptive levels of human vision. It is shown that the functional performances, the trichromatism in photopic vision, the monocular spatiotemporal 3D- and 4D-motion detection, as well as the Fourier optical image transformation with extraction of invariances all become possible. To transform light cones into reciprocal gratings especially the spectral phase conditions in the eikonal of the geometrical optical imaging before the retinal 3D-grating become relevant first, then in the von Laue resp. reciprocal von Laue equation for 3D-grating optics inside the grating and finally in the periodicity of Talbot-2/Fresnel-planes in the near-field behind the grating. It is becoming possible to technically realize -- at least in some specific aspects -- such a cortical optoretina sensor element with its typical hexagonal-concentric structure which leads to these visual functions.

  12. Exponentiated exponential model (Gompertz kinetics) of Na+ and K+ conductance changes in squid giant axon.

    PubMed Central

    Easton, D M

    1978-01-01

    The conductance changes, gK(t) and gNa(t), of squid giant axon under voltage clamp (Hodgkin and Huxley, 1952) may be modeled by exponentiated exponential functions (Gompertz kinetics) from any holding potential VO to any membrane clamp potential V. The equation constants are set by the membrane potential V, and include, for any voltage step in the case of gK, the initial conductance, gO, the asymptote conductance g, and rate constant k: gK = g exp(-be-kt) where b = 1n g/gO. Equations of similar form relate g and k to the voltage V, and govern the corresponding parameters of the gNa system. For the gNa, the fast phase y = y exp (-be-kt) is cut down in proportion to a slow process p = (1 - p)e-k't + p, and thus gNa = py. The expo-exponential functions involve fewer constants than the Hodgkin-Huxley model. In particular, the role of the n, m, h parameters appears to be filled largely by 1n (g/gO) in the case of gK and by 1n (y/yO) in the case of gNa. Membrane action potentials during current clamp may be computed from the conductances generated by use of the appropriate differential forms of the equations; diverse other membrane behaviors may be predicted. PMID:638223

  13. Boundary layer flow and heat transfer over a permeable surface moving with exponentially decreasing velocities in a parallel free stream

    NASA Astrophysics Data System (ADS)

    Ramli, Norshafira; Ahmad, Syakila; Pop, Ioan

    2014-07-01

    In this paper, we investigate the problem of steady boundary layer flow and heat transfer of a viscous and incompressible fluid over a permeable semi-infinite flat plate moving with exponentially decreasing velocities in a parallel free stream. The velocities of the moving flat plate and the free stream as well as the temperature of the moving plate are assumed to have a specific exponential decreasing function forms. The governing equations are first transformed to the similarity equations using an appropriate similarity transformation. Then, the resulting equations are solved by using shooting technique which is done with the aid of shootlib function in Maple software. The effects of the mass flux for suction and lateral injection, and the parameter that controls the exponential increment of the temperature on the flow characteristics are analysed and discussed. It is observed that there exist dual solutions for this present study.

  14. Stretched Exponential relaxation in pure Se glass

    NASA Astrophysics Data System (ADS)

    Dash, S.; Ravindren, S.; Boolchand, P.

    A universal feature of glasses is the stretched exponential relaxation, f (t) = exp[ - t / τ ] β . The model of diffusion of excitations to randomly distributed traps in a glass by Phillips1 yields the stretched exponent β = d[d +2] where d, the effective dimensionality. We have measured the enthalpy of relaxation ΔHnr (tw) at Tg of Se glass in modulated DSC experiments as glasses age at 300K and find β = 0.43(2) for tw in the 0

  15. An exponential decay model for mediation.

    PubMed

    Fritz, Matthew S

    2014-10-01

    Mediation analysis is often used to investigate mechanisms of change in prevention research. Results finding mediation are strengthened when longitudinal data are used because of the need for temporal precedence. Current longitudinal mediation models have focused mainly on linear change, but many variables in prevention change nonlinearly across time. The most common solution to nonlinearity is to add a quadratic term to the linear model, but this can lead to the use of the quadratic function to explain all nonlinearity, regardless of theory and the characteristics of the variables in the model. The current study describes the problems that arise when quadratic functions are used to describe all nonlinearity and how the use of nonlinear functions, such as exponential decay, address many of these problems. In addition, nonlinear models provide several advantages over polynomial models including usefulness of parameters, parsimony, and generalizability. The effects of using nonlinear functions for mediation analysis are then discussed and a nonlinear growth curve model for mediation is presented. An empirical example using data from a randomized intervention study is then provided to illustrate the estimation and interpretation of the model. Implications, limitations, and future directions are also discussed.

  16. An Exponential Decay Model for Mediation

    PubMed Central

    Fritz, Matthew S.

    2013-01-01

    Mediation analysis is often used to investigate mechanisms of change in prevention research. Results finding mediation are strengthened when longitudinal data are used because of the need for temporal precedence. Current longitudinal mediation models have focused mainly on linear change, but many variables in prevention change nonlinearly across time. The most common solution to nonlinearity is to add a quadratic term to the linear model, but this can lead to the use of the quadratic function to explain all nonlinearity, regardless of theory and the characteristics of the variables in the model. The current study describes the problems that arise when quadratic functions are used to describe all nonlinearity and how the use of nonlinear functions, such as exponential decay, addresses many of these problems. In addition, nonlinear models provide several advantages over polynomial models including usefulness of parameters, parsimony, and generalizability. The effects of using nonlinear functions for mediation analysis are then discussed and a nonlinear growth curve model for mediation is presented. An empirical example using data from a randomized intervention study is then provided to illustrate the estimation and interpretation of the model. Implications, limitations, and future directions are also discussed. PMID:23625557

  17. Density Estimation of Simulation Output Using Exponential EPI-Splines

    DTIC Science & Technology

    2013-12-01

    ak+1,1, k = 1, 2, ..., N − 1. Pointwise Fisher information. We define the pointwise Fisher information of an exponential epi-spline density h at x to...are required to obtain meaningful results. All exponential epi-splines are computed under the assumptions of continuity, smoothness, pointwise Fisher...Kernel 0.4310 0.3536 In the exponential epi-spline estimates, we include continuity, differentiability, and pointwise Fisher information constraints with

  18. Exponential convergence rates for weighted sums in noncommutative probability space

    NASA Astrophysics Data System (ADS)

    Choi, Byoung Jin; Ji, Un Cig

    2016-11-01

    We study exponential convergence rates for weighted sums of successive independent random variables in a noncommutative probability space of which the weights are in a von Neumann algebra. Then we prove a noncommutative extension of the result for the exponential convergence rate by Baum, Katz and Read. As applications, we first study a large deviation type inequality for weighted sums in a noncommutative probability space, and secondly we study exponential convergence rates for weighted free additive convolution sums of probability measures.

  19. Alternative method for diagnosis of two polymorphisms in the human transforming growth factor-beta1 by PCR-mediated double site-directed mutagenesis.

    PubMed

    Hubacek, J A; Lacha, J

    2000-05-01

    Cytokine transforming growth factor-beta1 plays an important role in physiological processes during ontogenesis, cell differentiation, immune responses, carcinogenesis, inflammation, wound healing, fibroproduction, progression of renal insufficiency and arteriosclerotic lesion development. Its biological function is influenced through the two signal peptide polymorphisms. We describe a new, economical, easy and fast alternative method which allows detection of both polymorphisms from one PCR product with subsequent restriction analysis with two different restriction enzymes. This method could facilitate further research on the role of this cytokine in human disease.

  20. Limit Lognormal Multifractal as an Exponential Functional

    NASA Astrophysics Data System (ADS)

    Ostrovsky, Dmitry

    2004-09-01

    The limiting distribution of the limit lognormal multifractal, first introduced by Mandelbrot ( Statistical Models and Turbulence, M. Rosenblatt and C. Van Atta, eds., Lecture Notes in Physics 12, Springer, New York, 1972, p. 333) and constructed explicitly by Bacry et al. (Phys. Rev. E 64, 026103 (2001)), is investigated using its Laplace transform. A partial differential equation for the Laplace transform is derived and it is shown that multifractality alone does not determine the limiting distribution. The increments of the limit multifractal process are strongly stochastically dependent. The precise nature of this stochastic dependence structure of increments (SDSI) is the determining characteristic of the limiting distribution. The SDSI of the limit process is quantified by means of two integro-differential relations obtained by renormalization in the sense of Leipnik (J. Aust. Math. Soc. B 32, 327-347 (1991)). One is interpreted as a counterpart of the star equation of Mandelbrot and the other is shown to be an analogue of the classical Girsanov theorem. In the weak intermittency limit an approximate single-variable equation for the Laplace transform is obtained and successfully tested numerically by simulation.

  1. Global exponential stability and dissipativity of generalized neural networks with time-varying delay signals.

    PubMed

    Manivannan, R; Samidurai, R; Cao, Jinde; Alsaedi, Ahmed; Alsaadi, Fuad E

    2017-03-01

    This paper investigates the problems of exponential stability and dissipativity of generalized neural networks (GNNs) with time-varying delay signals. By constructing a novel Lyapunov-Krasovskii functionals (LKFs) with triple integral terms that contain more advantages of the state vectors of the neural networks, and the upper bound on the time-varying delay signals are formulated. We employ a new integral inequality technique (IIT), free-matrix-based (FMB) integral inequality approach, and Wirtinger double integral inequality (WDII) technique together with the reciprocally convex combination (RCC) approach to bound the time derivative of the LKFs. An improved exponential stability and strictly (Q,S,R)-γ-dissipative conditions of the addressed systems are represented by the linear matrix inequalities (LMIs). Finally, four interesting numerical examples are developed to verify the usefulness of the proposed method with a practical application to a biological network. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Using Differentials to Differentiate Trigonometric and Exponential Functions

    ERIC Educational Resources Information Center

    Dray, Tevian

    2013-01-01

    Starting from geometric definitions, we show how differentials can be used to differentiate trigonometric and exponential functions without limits, numerical estimates, solutions of differential equations, or integration.

  3. Using Differentials to Differentiate Trigonometric and Exponential Functions

    ERIC Educational Resources Information Center

    Dray, Tevian

    2013-01-01

    Starting from geometric definitions, we show how differentials can be used to differentiate trigonometric and exponential functions without limits, numerical estimates, solutions of differential equations, or integration.

  4. Numerical computation of exponential matrices using the Cayley-Hamilton theorem

    NASA Technical Reports Server (NTRS)

    Walden, H.; Roelof, E. C.

    1982-01-01

    A method for computing exponential matrices, which often arise naturally in the solution of systems of linear differential equations, is developed. An exponential matrix is generated as a linear combination of a finite number (equal to the matrix order) of matrices, the coefficients of which are scalar infinite sums. The method can be generalized to apply to any formal power series of matrices. Attention is focused upon the exponential function, and the matrix exponent is assumed tri-diagonal in form. In such cases, the terms in the coefficient infinite sums can be extracted, as recursion relations, from the characteristic polynomial of the matrix exponent. Two numerical examples are presented in some detail: (1) the three dimensional infinitesimal rotation rate matrix, which is skew symmetric, and (2) an N-dimensional tri-diagonal and symmetric finite difference matrix which arises in the numerical solution of the heat conduction partial differential equation. In the second example, the known eigenvalues and eigenvectors of the finite difference matrix permit an analytical solution for the exponential matrix, through the theory of diagonalization and similarity transformations, which is used for independent verification. The convergence properties of the scalar infinite summations are investigated for finite difference matrices of various orders up to ten, and it is found that the number of terms required for convergence increases slowly with the order of the matrix.

  5. A Lower Bound on Blowup Rates for the 3D Incompressible Euler Equation and a Single Exponential Beale-Kato-Majda Type Estimate

    NASA Astrophysics Data System (ADS)

    Chen, Thomas; Pavlović, Nataša

    2012-08-01

    We prove a Beale-Kato-Majda type criterion for the loss of regularity for solutions of the incompressible Euler equations in {Hs({R}^3)} , for {s>5/2} . Instead of double exponential estimates of Beale-Kato-Majda type, we obtain a single exponential bound on {|u(t)|_{H^s}} involving the length parameter introduced by Constantin in (SIAM Rev. 36(1):73-98, 1994). In particular, we derive lower bounds on the blowup rate of such solutions.

  6. Robust Variable Selection with Exponential Squared Loss.

    PubMed

    Wang, Xueqin; Jiang, Yunlu; Huang, Mian; Zhang, Heping

    2013-04-01

    Robust variable selection procedures through penalized regression have been gaining increased attention in the literature. They can be used to perform variable selection and are expected to yield robust estimates. However, to the best of our knowledge, the robustness of those penalized regression procedures has not been well characterized. In this paper, we propose a class of penalized robust regression estimators based on exponential squared loss. The motivation for this new procedure is that it enables us to characterize its robustness that has not been done for the existing procedures, while its performance is near optimal and superior to some recently developed methods. Specifically, under defined regularity conditions, our estimators are [Formula: see text] and possess the oracle property. Importantly, we show that our estimators can achieve the highest asymptotic breakdown point of 1/2 and that their influence functions are bounded with respect to the outliers in either the response or the covariate domain. We performed simulation studies to compare our proposed method with some recent methods, using the oracle method as the benchmark. We consider common sources of influential points. Our simulation studies reveal that our proposed method performs similarly to the oracle method in terms of the model error and the positive selection rate even in the presence of influential points. In contrast, other existing procedures have a much lower non-causal selection rate. Furthermore, we re-analyze the Boston Housing Price Dataset and the Plasma Beta-Carotene Level Dataset that are commonly used examples for regression diagnostics of influential points. Our analysis unravels the discrepancies of using our robust method versus the other penalized regression method, underscoring the importance of developing and applying robust penalized regression methods.

  7. An exponential filter model predicts lightness illusions

    PubMed Central

    Zeman, Astrid; Brooks, Kevin R.; Ghebreab, Sennay

    2015-01-01

    Lightness, or perceived reflectance of a surface, is influenced by surrounding context. This is demonstrated by the Simultaneous Contrast Illusion (SCI), where a gray patch is perceived lighter against a black background and vice versa. Conversely, assimilation is where the lightness of the target patch moves toward that of the bounding areas and can be demonstrated in White's effect. Blakeslee and McCourt (1999) introduced an oriented difference-of-Gaussian (ODOG) model that is able to account for both contrast and assimilation in a number of lightness illusions and that has been subsequently improved using localized normalization techniques. We introduce a model inspired by image statistics that is based on a family of exponential filters, with kernels spanning across multiple sizes and shapes. We include an optional second stage of normalization based on contrast gain control. Our model was tested on a well-known set of lightness illusions that have previously been used to evaluate ODOG and its variants, and model lightness values were compared with typical human data. We investigate whether predictive success depends on filters of a particular size or shape and whether pooling information across filters can improve performance. The best single filter correctly predicted the direction of lightness effects for 21 out of 27 illusions. Combining two filters together increased the best performance to 23, with asymptotic performance at 24 for an arbitrarily large combination of filter outputs. While normalization improved prediction magnitudes, it only slightly improved overall scores in direction predictions. The prediction performance of 24 out of 27 illusions equals that of the best performing ODOG variant, with greater parsimony. Our model shows that V1-style orientation-selectivity is not necessary to account for lightness illusions and that a low-level model based on image statistics is able to account for a wide range of both contrast and assimilation effects

  8. Design for Double Rainbow

    ERIC Educational Resources Information Center

    Thomas, Lisa Carlucci

    2011-01-01

    Rare is the inspirational, spontaneous, transformative moment shared among 20 million people. In the summer of 2010, people around the world were moved by the sighting of a double rainbow--almost a triple rainbow--"all the way across the sky" in Yosemite National Park. Caught on video and posted to by YouTube by Paul Vasquez in January 2010, the…

  9. Design for Double Rainbow

    ERIC Educational Resources Information Center

    Thomas, Lisa Carlucci

    2011-01-01

    Rare is the inspirational, spontaneous, transformative moment shared among 20 million people. In the summer of 2010, people around the world were moved by the sighting of a double rainbow--almost a triple rainbow--"all the way across the sky" in Yosemite National Park. Caught on video and posted to by YouTube by Paul Vasquez in January 2010, the…

  10. Transformational Learners: Transformational Teachers

    ERIC Educational Resources Information Center

    Jones, Marguerite

    2009-01-01

    Transformational learning, according to Mezirow (1981), involves transforming taken-for-granted frames of reference into more discriminating, flexible "habits of mind". In teacher education, transformative learning impacts on the development of students' action theories, self-efficacy and professional attributes. Although considered…

  11. The Transformations of Transformations.

    ERIC Educational Resources Information Center

    Lin, Francis Y.

    2000-01-01

    Harris's original idea of transformations has been changed several times in Chomsky's work. This article explicates these transformations, arguing that though their motivations are highly understandable, these transformations are not necessary for understanding the workings of natural languages. (Author/VWL)

  12. Simultaneous Gaussian and exponential inversion for improved analysis of shales by NMR relaxometry

    USGS Publications Warehouse

    Washburn, Kathryn E.; Anderssen, Endre; Vogt, Sarah J.; Seymour, Joseph D.; Birdwell, Justin E.; Kirkland, Catherine M.; Codd, Sarah L.

    2014-01-01

    Nuclear magnetic resonance (NMR) relaxometry is commonly used to provide lithology-independent porosity and pore-size estimates for petroleum resource evaluation based on fluid-phase signals. However in shales, substantial hydrogen content is associated with solid and fluid signals and both may be detected. Depending on the motional regime, the signal from the solids may be best described using either exponential or Gaussian decay functions. When the inverse Laplace transform, the standard method for analysis of NMR relaxometry results, is applied to data containing Gaussian decays, this can lead to physically unrealistic responses such as signal or porosity overcall and relaxation times that are too short to be determined using the applied instrument settings. We apply a new simultaneous Gaussian-Exponential (SGE) inversion method to simulated data and measured results obtained on a variety of oil shale samples. The SGE inversion produces more physically realistic results than the inverse Laplace transform and displays more consistent relaxation behavior at high magnetic field strengths. Residuals for the SGE inversion are consistently lower than for the inverse Laplace method and signal overcall at short T2 times is mitigated. Beyond geological samples, the method can also be applied in other fields where the sample relaxation consists of both Gaussian and exponential decays, for example in material, medical and food sciences.

  13. Simultaneous Gaussian and exponential inversion for improved analysis of shales by NMR relaxometry.

    PubMed

    Washburn, Kathryn E; Anderssen, Endre; Vogt, Sarah J; Seymour, Joseph D; Birdwell, Justin E; Kirkland, Catherine M; Codd, Sarah L

    2015-01-01

    Nuclear magnetic resonance (NMR) relaxometry is commonly used to provide lithology-independent porosity and pore-size estimates for petroleum resource evaluation based on fluid-phase signals. However in shales, substantial hydrogen content is associated with solid and fluid signals and both may be detected. Depending on the motional regime, the signal from the solids may be best described using either exponential or Gaussian decay functions. When the inverse Laplace transform, the standard method for analysis of NMR relaxometry results, is applied to data containing Gaussian decays, this can lead to physically unrealistic responses such as signal or porosity overcall and relaxation times that are too short to be determined using the applied instrument settings. We apply a new simultaneous Gaussian-Exponential (SGE) inversion method to simulated data and measured results obtained on a variety of oil shale samples. The SGE inversion produces more physically realistic results than the inverse Laplace transform and displays more consistent relaxation behavior at high magnetic field strengths. Residuals for the SGE inversion are consistently lower than for the inverse Laplace method and signal overcall at short T2 times is mitigated. Beyond geological samples, the method can also be applied in other fields where the sample relaxation consists of both Gaussian and exponential decays, for example in material, medical and food sciences.

  14. Determination of plasma pinch time and effective current radius of double planar wire array implosions from current measurements on a 1-MA linear transformer driver

    NASA Astrophysics Data System (ADS)

    Steiner, Adam M.; Yager-Elorriaga, David A.; Patel, Sonal G.; Jordan, Nicholas M.; Gilgenbach, Ronald M.; Safronova, Alla S.; Kantsyrev, Victor L.; Shlyaptseva, Veronica V.; Shrestha, Ishor; Schmidt-Petersen, Maximillian T.

    2016-10-01

    Implosions of planar wire arrays were performed on the Michigan Accelerator for Inductive Z-pinch Experiments, a linear transformer driver (LTD) at the University of Michigan. These experiments were characterized by lower than expected peak currents and significantly longer risetimes compared to studies performed on higher impedance machines. A circuit analysis showed that the load inductance has a significant impact on the current output due to the comparatively low impedance of the driver; the long risetimes were also attributed to high variability in LTD switch closing times. A circuit model accounting for these effects was employed to measure changes in load inductance as a function of time to determine plasma pinch timing and calculate a minimum effective current-carrying radius. These calculations showed good agreement with available shadowgraphy and x-ray diode measurements.

  15. Surface properties and exponential stress relaxations of mammalian meibum films.

    PubMed

    Eftimov, Petar; Yokoi, Norihiko; Tonchev, Vesselin; Nencheva, Yana; Georgiev, Georgi As

    2017-03-01

    The surface properties of meibomian secretion (MGS), the major constituent of the tear film (TF) lipid layer, are of key importance for TF stability. The interfacial properties of canine, cMGS, and feline, fMGS, meibum films were studied using a Langmuir surface balance. These species were selected because they have blinking frequency and TF stability similar to those of humans. The sample's performance during dynamic area changes was evaluated by surface pressure (π)-area (A) isocycles and the layer structure was monitored with Brewster angle microscopy. The films' dilatational rheology was probed via the stress-relaxation technique. The animal MGS showed similar behavior both between each other and with human MGS (studied previously). They form reversible, non-collapsible, multilayer thick films. The relaxations of canine, feline, and human MGS films were well described by double exponential decay reflecting the presence of two processes: (1) fast elastic process, with characteristic time τ < 10 s and (2) slow viscous process, with τ > 100 s-emphasizing the meibum layers viscoelasticity. The temperature decrease from 35 to 25 °C resulted in decreased thickness and lateral expansion of all MGS layers accompanied with increase of the π/A hysteresis and of the elastic process contribution to π relaxation transients. Thus, MGS films of mammals with similar blinking frequency and TF stability have similar surface properties and stress relaxations unaltered by the interspecies MGS compositional variations. Such knowledge may impact the selection of animal mimics of human MGS and on a better understanding of lipid classes' impact on meibum functionality.

  16. A Learning Cycle on Exponential Growth and the Energy Crises.

    ERIC Educational Resources Information Center

    Dykstra, D. I., Jr.

    1982-01-01

    Describes nature and logistics of a learning cycle approach to teaching exponential growth and the energy crisis. Used with both science and nonscience majors, the cycle uses no algebra, never mentions the terms exponential or logarithmic, and requires a calculator. Instructions for obtaining student and instructor materials are provided.…

  17. Exponential Correlation of IQ and the Wealth of Nations

    ERIC Educational Resources Information Center

    Dickerson, Richard E.

    2006-01-01

    Plots of mean IQ and per capita real Gross Domestic Product for groups of 81 and 185 nations, as collected by Lynn and Vanhanen, are best fitted by an exponential function of the form: GDP = "a" * 10["b"*(IQ)], where "a" and "b" are empirical constants. Exponential fitting yields markedly higher correlation coefficients than either linear or…

  18. Modeling of magnitude distributions by the generalized truncated exponential distribution

    NASA Astrophysics Data System (ADS)

    Raschke, Mathias

    2015-01-01

    The probability distribution of the magnitude can be modeled by an exponential distribution according to the Gutenberg-Richter relation. Two alternatives are the truncated exponential distribution (TED) and the cutoff exponential distribution (CED). The TED is frequently used in seismic hazard analysis although it has a weak point: when two TEDs with equal parameters except the upper bound magnitude are mixed, then the resulting distribution is not a TED. Inversely, it is also not possible to split a TED of a seismic region into TEDs of subregions with equal parameters except the upper bound magnitude. This weakness is a principal problem as seismic regions are constructed scientific objects and not natural units. We overcome it by the generalization of the abovementioned exponential distributions: the generalized truncated exponential distribution (GTED). Therein, identical exponential distributions are mixed by the probability distribution of the correct cutoff points. This distribution model is flexible in the vicinity of the upper bound magnitude and is equal to the exponential distribution for smaller magnitudes. Additionally, the exponential distributions TED and CED are special cases of the GTED. We discuss the possible ways of estimating its parameters and introduce the normalized spacing for this purpose. Furthermore, we present methods for geographic aggregation and differentiation of the GTED and demonstrate the potential and universality of our simple approach by applying it to empirical data. The considerable improvement by the GTED in contrast to the TED is indicated by a large difference between the corresponding values of the Akaike information criterion.

  19. Exponential Correlation of IQ and the Wealth of Nations

    ERIC Educational Resources Information Center

    Dickerson, Richard E.

    2006-01-01

    Plots of mean IQ and per capita real Gross Domestic Product for groups of 81 and 185 nations, as collected by Lynn and Vanhanen, are best fitted by an exponential function of the form: GDP = "a" * 10["b"*(IQ)], where "a" and "b" are empirical constants. Exponential fitting yields markedly higher correlation coefficients than either linear or…

  20. Review of "Going Exponential: Growing the Charter School Sector's Best"

    ERIC Educational Resources Information Center

    Garcia, David

    2011-01-01

    This Progressive Policy Institute report argues that charter schools should be expanded rapidly and exponentially. Citing exponential growth organizations, such as Starbucks and Apple, as well as the rapid growth of molds, viruses and cancers, the report advocates for similar growth models for charter schools. However, there is no explanation of…

  1. Flows induced by exponential stretching and shearing plate motions

    NASA Astrophysics Data System (ADS)

    Weidman, Patrick

    2016-11-01

    Boundary-layer solutions for the flow induced by an exponentially stretching surface also sheared in its own plane are given. Prior to this study no similarity solutions have been reported for flows generated by exponentially sheared surfaces concomitant with surface stretching in any form. The method of solution is self-similarity. The results found here are intimately related to those of Magyari and Keller ["Heat and mass transfer in the boundary layers on an exponentially stretching continuous surface," J. Phys. D: Appl. Phys. 32, 577-585 (1999)] who studied the motion and heat transfer induced by an exponentially stretching plate. In addition to two particular cases reported here, a third situation is found where an exponentially stretching surface admits a concomitant arbitrary streamwise shearing motion.

  2. Exponential synchronization of memristive Cohen-Grossberg neural networks with mixed delays.

    PubMed

    Yang, Xinsong; Cao, Jinde; Yu, Wenwu

    2014-06-01

    This paper concerns the problem of global exponential synchronization for a class of memristor-based Cohen-Grossberg neural networks with time-varying discrete delays and unbounded distributed delays. The drive-response set is discussed. A novel controller is designed such that the response (slave) system can be controlled to synchronize with the drive (master) system. Through a nonlinear transformation, we get an alternative system from the considered memristor-based Cohen-Grossberg neural networks. By investigating the global exponential synchronization of the alternative system, we obtain the corresponding synchronization criteria of the considered memristor-based Cohen-Grossberg neural networks. Moreover, the conditions established in this paper are easy to be verified and improve the conditions derived in most of existing papers concerning stability and synchronization for memristor-based neural networks. Numerical simulations are given to show the effectiveness of the theoretical results.

  3. Numerical study of MHD nanofluid flow and heat transfer past a bidirectional exponentially stretching sheet

    NASA Astrophysics Data System (ADS)

    Ahmad, Rida; Mustafa, M.; Hayat, T.; Alsaedi, A.

    2016-06-01

    Recent advancements in nanotechnology have led to the discovery of new generation coolants known as nanofluids. Nanofluids possess novel and unique characteristics which are fruitful in numerous cooling applications. Current work is undertaken to address the heat transfer in MHD three-dimensional flow of magnetic nanofluid (ferrofluid) over a bidirectional exponentially stretching sheet. The base fluid is considered as water which consists of magnetite-Fe3O4 nanoparticles. Exponentially varying surface temperature distribution is accounted. Problem formulation is presented through the Maxwell models for effective electrical conductivity and effective thermal conductivity of nanofluid. Similarity transformations give rise to a coupled non-linear differential system which is solved numerically. Appreciable growth in the convective heat transfer coefficient is observed when nanoparticle volume fraction is augmented. Temperature exponent parameter serves to enhance the heat transfer from the surface. Moreover the skin friction coefficient is directly proportional to both magnetic field strength and nanoparticle volume fraction.

  4. Assessment of antitumor activity for tumor xenograft studies using exponential growth models.

    PubMed

    Wu, Jianrong

    2011-05-01

    In preclinical tumor xenograft experiments, the antitumor activity of the tested agents is often assessed by endpoints such as tumor doubling time, tumor growth delay (TGD), and log10 cell kill (LCK). In tumor xenograft literature, the values of these endpoints are presented without any statistical inference, which ignores the noise in the experimental data. However, using exponential growth models, these endpoints can be quantified by their growth curve parameters, thus allowing parametric inference, such as an interval estimate, to be used to assess the antitumor activity of the treatment.

  5. Tracing changes in soil N transformations to explain the doubling of N2O emissions under elevated CO2 in the Giessen FACE

    NASA Astrophysics Data System (ADS)

    Moser, Gerald; Brenzinger, Kristof; Gorenflo, Andre; Clough, Tim; Braker, Gesche; Müller, Christoph

    2017-04-01

    To reduce the emissions of greenhouse gases (CO2, CH4 & N2O) it is important to quantify main sources and identify the respective ecosystem processes. While the main sources of N2O emissions in agro-ecosystems under current conditions are well known, the influence of a projected higher level of CO2 on the main ecosystem processes responsible for N2O emissions has not been investigated in detail. A major result of the Giessen FACE in a managed temperate grassland was that a +20% CO2 level caused a positive feedback due to increased emissions of N2O to 221% related to control condition. To be able to trace the sources of additional N2O emissions a 15N tracing study was conducted. We measured the N2O emission and its 15N signature, together with the 15N signature of soil and plant samples. The results were analyzed using a 15N tracing model which quantified the main changes in N transformation rates under elevated CO2. Directly after 15N fertilizer application a much higher dynamic of N transformations was observed than in the long run. Absolute mineralisation and DNRA rates were lower under elevated CO2 in the short term but higher in the long term. During the one year study period beginning with the 15N labelling a 1.8-fold increase of N2O emissions occurred under elevated CO2. The source of increased N2O was associated with NO3- in the first weeks after 15N application. Elevated CO2 affected denitrification rates, which resulted in increased N2O emissions due to a change of gene transcription rates (nosZ/(nirK+nirS)) and resulting enzyme activity (see: Brenzinger et al.). Here we show that the reported enhanced N2O emissions for the first 8 FACE years do prevail even in the long-term (> 15 years). The effect of elevated CO2 on N2O production/emission can be explained by altered activity ratios within a stable microbial community.

  6. Generalized Exponential Distribution in Flood Frequency Analysis for Polish Rivers

    PubMed Central

    Markiewicz, Iwona; Strupczewski, Witold G.; Bogdanowicz, Ewa; Kochanek, Krzysztof

    2015-01-01

    Many distributions have been used in flood frequency analysis (FFA) for fitting the flood extremes data. However, as shown in the paper, the scatter of Polish data plotted on the moment ratio diagram shows that there is still room for a new model. In the paper, we study the usefulness of the generalized exponential (GE) distribution in flood frequency analysis for Polish Rivers. We investigate the fit of GE distribution to the Polish data of the maximum flows in comparison with the inverse Gaussian (IG) distribution, which in our previous studies showed the best fitting among several models commonly used in FFA. Since the use of a discrimination procedure without the knowledge of its performance for the considered probability density functions may lead to erroneous conclusions, we compare the probability of correct selection for the GE and IG distributions along with the analysis of the asymptotic model error in respect to the upper quantile values. As an application, both GE and IG distributions are alternatively assumed for describing the annual peak flows for several gauging stations of Polish Rivers. To find the best fitting model, four discrimination procedures are used. In turn, they are based on the maximized logarithm of the likelihood function (K procedure), on the density function of the scale transformation maximal invariant (QK procedure), on the Kolmogorov-Smirnov statistics (KS procedure) and the fourth procedure based on the differences between the ML estimate of 1% quantile and its value assessed by the method of moments and linear moments, in sequence (R procedure). Due to the uncertainty of choosing the best model, the method of aggregation is applied to estimate of the maximum flow quantiles. PMID:26657239

  7. Generalized Exponential Distribution in Flood Frequency Analysis for Polish Rivers.

    PubMed

    Markiewicz, Iwona; Strupczewski, Witold G; Bogdanowicz, Ewa; Kochanek, Krzysztof

    2015-01-01

    Many distributions have been used in flood frequency analysis (FFA) for fitting the flood extremes data. However, as shown in the paper, the scatter of Polish data plotted on the moment ratio diagram shows that there is still room for a new model. In the paper, we study the usefulness of the generalized exponential (GE) distribution in flood frequency analysis for Polish Rivers. We investigate the fit of GE distribution to the Polish data of the maximum flows in comparison with the inverse Gaussian (IG) distribution, which in our previous studies showed the best fitting among several models commonly used in FFA. Since the use of a discrimination procedure without the knowledge of its performance for the considered probability density functions may lead to erroneous conclusions, we compare the probability of correct selection for the GE and IG distributions along with the analysis of the asymptotic model error in respect to the upper quantile values. As an application, both GE and IG distributions are alternatively assumed for describing the annual peak flows for several gauging stations of Polish Rivers. To find the best fitting model, four discrimination procedures are used. In turn, they are based on the maximized logarithm of the likelihood function (K procedure), on the density function of the scale transformation maximal invariant (QK procedure), on the Kolmogorov-Smirnov statistics (KS procedure) and the fourth procedure based on the differences between the ML estimate of 1% quantile and its value assessed by the method of moments and linear moments, in sequence (R procedure). Due to the uncertainty of choosing the best model, the method of aggregation is applied to estimate of the maximum flow quantiles.

  8. Derivation of stretched exponential tap density equations of granular powders.

    PubMed

    Hao, Tian

    2015-04-21

    The tap density of granular powders was found to be better fitted with the stretched exponential law. In our previous work, the stretched exponential tap density equations were derived with the rate process theory and free volume concept, under the assumption that the particle packing rate during the tapping process obeys the stretched Arrhenius equation, which, however, has an empirical origin. In this article, the above assumption is eliminated and attempts are made to obtain the stretched exponential tap density equations from very fundamental bases. In a vertical tapping process, the probability of particles attaining certain energy states is assumed to obey the Boltzmann distribution and particles traveling from one site to another are assumed to follow a very common memoryless random exponential law. The stretched exponential tap density equations are thus derived and all parameters acquire clear physical meanings. The most important parameter, the stretched exponential, is demonstrated to correlate with the interparticle forces: a small value may indicate a strong adhesive or cohesive interaction. Therefore, the stretched exponential could be a better indicator for powder flowability correlated with particle interactions as well.

  9. Numerically stable formulas for a particle-based explicit exponential integrator

    NASA Astrophysics Data System (ADS)

    Nadukandi, Prashanth

    2015-05-01

    Numerically stable formulas are presented for the closed-form analytical solution of the X-IVAS scheme in 3D. This scheme is a state-of-the-art particle-based explicit exponential integrator developed for the particle finite element method. Algebraically, this scheme involves two steps: (1) the solution of tangent curves for piecewise linear vector fields defined on simplicial meshes and (2) the solution of line integrals of piecewise linear vector-valued functions along these tangent curves. Hence, the stable formulas presented here have general applicability, e.g. exact integration of trajectories in particle-based (Lagrangian-type) methods, flow visualization and computer graphics. The Newton form of the polynomial interpolation definition is used to express exponential functions of matrices which appear in the analytical solution of the X-IVAS scheme. The divided difference coefficients in these expressions are defined in a piecewise manner, i.e. in a prescribed neighbourhood of removable singularities their series approximations are computed. An optimal series approximation of divided differences is presented which plays a critical role in this methodology. At least ten significant decimal digits in the formula computations are guaranteed to be exact using double-precision floating-point arithmetic. The worst case scenarios occur in the neighbourhood of removable singularities found in fourth-order divided differences of the exponential function.

  10. Double-helix stellarator

    SciTech Connect

    Moroz, P.E.

    1997-09-01

    A new stellarator configuration, the Double-Helix Stellarator (DHS), is introduced. This novel configuration features a double-helix center post as the only helical element of the stellarator coil system. The DHS configuration has many unique characteristics. One of them is the extreme low plasma aspect ratio, A {approx} 1--1.2. Other advantages include a high enclosed volume, appreciable rotational transform, and a possibility of extreme-high-{beta} MHD equilibria. Moreover, the DHS features improved transport characteristics caused by the absence of the magnetic field ripple on the outboard of the torus. Compactness, simplicity and modularity of the coil system add to the DHS advantages for fusion applications.

  11. First-order analytic propagation of satellites in the exponential atmosphere of an oblate planet

    NASA Astrophysics Data System (ADS)

    Martinusi, Vladimir; Dell'Elce, Lamberto; Kerschen, Gaëtan

    2017-04-01

    The paper offers the fully analytic solution to the motion of a satellite orbiting under the influence of the two major perturbations, due to the oblateness and the atmospheric drag. The solution is presented in a time-explicit form, and takes into account an exponential distribution of the atmospheric density, an assumption that is reasonably close to reality. The approach involves two essential steps. The first one concerns a new approximate mathematical model that admits a closed-form solution with respect to a set of new variables. The second step is the determination of an infinitesimal contact transformation that allows to navigate between the new and the original variables. This contact transformation is obtained in exact form, and afterwards a Taylor series approximation is proposed in order to make all the computations explicit. The aforementioned transformation accommodates both perturbations, improving the accuracy of the orbit predictions by one order of magnitude with respect to the case when the atmospheric drag is absent from the transformation. Numerical simulations are performed for a low Earth orbit starting at an altitude of 350 km, and they show that the incorporation of drag terms into the contact transformation generates an error reduction by a factor of 7 in the position vector. The proposed method aims at improving the accuracy of analytic orbit propagation and transforming it into a viable alternative to the computationally intensive numerical methods.

  12. MHD Flow with Hall current and Joule Heating Effects over an Exponentially Stretching Sheet

    NASA Astrophysics Data System (ADS)

    Srinivasacharya, D.; Jagadeeshwar, P.

    2017-06-01

    The aim of the present paper is to study the influence of Hall current and Joule heating on flow, heat and mass transfer over an exponentially stretching sheet in a viscous fluid. Using similarity transformations the governing nonlinear coupled equations are converted into ordinary differential equations. These equations are linearized using the successive linearization method and then solved using the Chebyshev pseudo spectral method. The influence of magnetic parameter, Hall parameter, suction/injection parameter and slip parameter on the physical quantities are presented graphically. The obtained results are compared with the previously published results for special cases.

  13. Study on Biodegradation Process of Polyethylene Glycol with Exponential Glowth of Microbial Population

    NASA Astrophysics Data System (ADS)

    Watanabe, Masaji; Kawai, Fusako

    Biodegradation of polyethylene glycol is studied mathematically. A mathematical model for depolymerization process of exogenous type is described. When a degradation rate is a product of a time factor and a molecular factor, a time dependent model can be transformed into a time independent model, and techniques developed in previous studies can be applied to the time independent model to determine the molecular factor. The time factor can be determined assuming the exponential growth of the microbial population. Those techniques are described, and numerical results are presented. A comparison between a numerical result and an experimental result shows that the mathematical method is appropriate for practical applications.

  14. Exponential rational function method for space-time fractional differential equations

    NASA Astrophysics Data System (ADS)

    Aksoy, Esin; Kaplan, Melike; Bekir, Ahmet

    2016-04-01

    In this paper, exponential rational function method is applied to obtain analytical solutions of the space-time fractional Fokas equation, the space-time fractional Zakharov Kuznetsov Benjamin Bona Mahony, and the space-time fractional coupled Burgers' equations. As a result, some exact solutions for them are successfully established. These solutions are constructed in fractional complex transform to convert fractional differential equations into ordinary differential equations. The fractional derivatives are described in Jumarie's modified Riemann-Liouville sense. The exact solutions obtained by the proposed method indicate that the approach is easy to implement and effective.

  15. The deinococcal DdrB protein is involved in an early step of DNA double strand break repair and in plasmid transformation through its single-strand annealing activity

    PubMed Central

    de la Tour, Claire Bouthier; Boisnard, Stéphanie; Norais, Cédric; Toueille, Magali; Bentchikou, Esma; Vannier, Françoise; Cox, Michael M.; Sommer, Suzanne; Servant, Pascale

    2012-01-01

    The Deinococcus radiodurans bacterium exhibits an extreme resistance to ionizing radiation. Here, we investigated the in vivo role of DdrB, a radiation-induced Deinococcus specific protein that was previously shown to exhibit some in vitro properties akin to those of SSB protein from E. coli but also to promote annealing of single stranded DNA. First we report that the deletion of the C-terminal motif of the DdrB protein, which is similar to the SSB C-terminal motif involved in recruitment to DNA of repair proteins, did neither affect cell radioresistance nor DNA binding properties of purified DdrB protein. We show that, in spite of their different quaternary structure, DdrB and SSB occlude the same amount of ssDNA in vitro. We also showed that DdrB is recruited early and transiently after irradiation into the nucleoid to form discrete foci. Absence of DdrB increased the lag phase of the extended synthesis-dependent strand annealing (ESDSA) process, affecting neither the rate of DNA synthesis nor the efficiency of fragment reassembly, as indicated by monitoring DNA synthesis and genome reconstitution in cells exposed to a sub-lethal ionizing radiation dose. Moreover, cells devoid of DdrB were affected in the establishment of plasmid DNA during natural transformation, a process that requires pairing of internalized plasmid single stranded DNA fragments, whereas they were proficient in transformation by a chromosomal DNA marker that integrates into the host chromosome through homologous recombination. Our data are consistent with a model in which DdrB participates in an early step of DNA double strand break repair in cells exposed to very high radiation doses. DdrB might facilitate the accurate assembly of the myriad of small fragments generated by extreme radiation exposure through a single strand annealing (SSA) process to generate suitable substrates for subsequent ESDSA-promoted genome reconstitution. PMID:21968057

  16. Asymptotic expansions of Feynman integrals of exponentials with polynomial exponent

    NASA Astrophysics Data System (ADS)

    Kravtseva, A. K.; Smolyanov, O. G.; Shavgulidze, E. T.

    2016-10-01

    In the paper, an asymptotic expansion of path integrals of functionals having exponential form with polynomials in the exponent is constructed. The definition of the path integral in the sense of analytic continuation is considered.

  17. Exponential Functions, Rates of Change, and the Multiplicative Unit.

    ERIC Educational Resources Information Center

    Confrey, Jere; Smith, Erick

    1994-01-01

    Describes a covariational, rather than correspondence, approach to functions that emphasizes rate of change. Proposes three ways of understanding rate of change in relation to exponential functions. (Contains 41 references.) (Author/MKR)

  18. On the role of exponential splines in image interpolation.

    PubMed

    Kirshner, Hagai; Porat, Moshe

    2009-10-01

    A Sobolev reproducing-kernel Hilbert space approach to image interpolation is introduced. The underlying kernels are exponential functions and are related to stochastic autoregressive image modeling. The corresponding image interpolants can be implemented effectively using compactly-supported exponential B-splines. A tight l(2) upper-bound on the interpolation error is then derived, suggesting that the proposed exponential functions are optimal in this regard. Experimental results indicate that the proposed interpolation approach with properly-tuned, signal-dependent weights outperforms currently available polynomial B-spline models of comparable order. Furthermore, a unified approach to image interpolation by ideal and nonideal sampling procedures is derived, suggesting that the proposed exponential kernels may have a significant role in image modeling as well. Our conclusion is that the proposed Sobolev-based approach could be instrumental and a preferred alternative in many interpolation tasks.

  19. True quantum face of the "exponential" decay law

    NASA Astrophysics Data System (ADS)

    Urbanowski, Krzysztof

    2017-05-01

    Results of theoretical studies of the quantum unstable systems caused that there are rather widespread belief that a universal feature of the quantum decay process is the presence of three time regimes of the decay process: the early time (initial) leading to the Quantum Zeno (or Anti Zeno) Effects, "exponential" (or "canonical") described by the decay law of the exponential form, and late time characterized by the decay law having inverse-power law form. Based on the fundamental principles of the quantum theory we give the proof that there is no time interval in which the survival probability (decay law) could be a decreasing function of time of the purely exponential form but even at the "exponential" regime the decay curve is oscillatory modulated with a smaller or a large amplitude of oscillations depending on parameters of the model considered.

  20. Fast Modular Exponentiation and Elliptic Curve Group Operation in Maple

    ERIC Educational Resources Information Center

    Yan, S. Y.; James, G.

    2006-01-01

    The modular exponentiation, y[equivalent to]x[superscript k](mod n) with x,y,k,n integers and n [greater than] 1; is the most fundamental operation in RSA and ElGamal public-key cryptographic systems. Thus the efficiency of RSA and ElGamal depends entirely on the efficiency of the modular exponentiation. The same situation arises also in elliptic…

  1. Dynamic controller design for exponential synchronization of Chen chaotic system

    NASA Astrophysics Data System (ADS)

    Park, Ju H.; Lee, S. M.; Kwon, O. M.

    2007-07-01

    The Letter considers synchronization of Chen chaotic system. The problems of determining the exponential stability and estimating the exponential convergence rate for the synchronization are investigated by employing the Lyapunov functional method and linear matrix inequality (LMI) technique. For this end, a dynamic controller is proposed for the first time and a criterion for existence of the controller is given in terms of LMIs. Finally, numerical simulations are presented to show the effectiveness of the proposed chaos synchronization scheme.

  2. Confronting quasi-exponential inflation with WMAP seven

    SciTech Connect

    Pal, Barun Kumar; Pal, Supratik; Basu, B. E-mail: pal@th.physik.uni-bonn.de

    2012-04-01

    We confront quasi-exponential models of inflation with WMAP seven years dataset using Hamilton Jacobi formalism. With a phenomenological Hubble parameter, representing quasi exponential inflation, we develop the formalism and subject the analysis to confrontation with WMAP seven using the publicly available code CAMB. The observable parameters are found to fair extremely well with WMAP seven. We also obtain a ratio of tensor to scalar amplitudes which may be detectable in PLANCK.

  3. Skewed exponential pairwise velocities from Gaussian initial conditions

    SciTech Connect

    Juszkiewicz, R.; Fisher, K. B.; Szapudi, I.

    1998-09-01

    Using an Eulerian perturbative calculation, we show that the distribution of relative pairwise velocities which arises from gravitational instability of Gaussian density fluctuations has asymmetric (skewed) exponential tails. The negative skewness is induced by the negative mean streaming velocity of pairs (the infall prevails over expansion), while the exponential tails arise because the relative pairwise velocity is a number, not volume weighted statistic. The derived probability distribution is compared with N-body simulations and shown to provide a reasonable fit.

  4. Exponential order statistic models of software reliability growth

    NASA Technical Reports Server (NTRS)

    Miller, D. R.

    1985-01-01

    Failure times of a software reliabilty growth process are modeled as order statistics of independent, nonidentically distributed exponential random variables. The Jelinsky-Moranda, Goel-Okumoto, Littlewood, Musa-Okumoto Logarithmic, and Power Law models are all special cases of Exponential Order Statistic Models, but there are many additional examples also. Various characterizations, properties and examples of this class of models are developed and presented.

  5. Exponential order statistic models of software reliability growth

    NASA Technical Reports Server (NTRS)

    Miller, D. R.

    1986-01-01

    Failure times of a software reliability growth process are modeled as order statistics of independent, nonidentically distributed exponential random variables. The Jelinsky-Moranda, Goel-Okumoto, Littlewood, Musa-Okumoto Logarithmic, and Power Law models are all special cases of Exponential Order Statistic Models, but there are many additional examples also. Various characterizations, properties and examples of this class of models are developed and presented.

  6. Demonstration of the exponential decay law using beer froth

    NASA Astrophysics Data System (ADS)

    Leike, A.

    2002-01-01

    The volume of beer froth decays exponentially with time. This property is used to demonstrate the exponential decay law in the classroom. The decay constant depends on the type of beer and can be used to differentiate between different beers. The analysis shows in a transparent way the techniques of data analysis commonly used in science - consistency checks of theoretical models with the data, parameter estimation and determination of confidence intervals.

  7. Fast Modular Exponentiation and Elliptic Curve Group Operation in Maple

    ERIC Educational Resources Information Center

    Yan, S. Y.; James, G.

    2006-01-01

    The modular exponentiation, y[equivalent to]x[superscript k](mod n) with x,y,k,n integers and n [greater than] 1; is the most fundamental operation in RSA and ElGamal public-key cryptographic systems. Thus the efficiency of RSA and ElGamal depends entirely on the efficiency of the modular exponentiation. The same situation arises also in elliptic…

  8. Exponential series expansion for correlation functions of many-body systems.

    PubMed

    Barocchi, Fabrizio; Guarini, Eleonora; Bafile, Ubaldo

    2014-09-01

    We demonstrate that in Hamiltonian many-body systems at equilibrium, any kind of time dependent correlation function c(t) can always be expanded in a series of (complex) exponential functions of time when its Laplace transform C̃(z) has single poles. The characteristic frequencies can be identified as the eigenfrequencies of the correlation. This is done without introducing the concepts of fluctuating forces and memory functions, due to Mori and Zwanzig and extensively used in the literature in the last decades. Our method is based on a different projection technique in the Hilbert space S of the system and shows that appropriate approximations of the exponential series are related to the contraction of S to a finite, usually small, number of dimensions. The time dependence of correlation functions is always described in detail by a multiple-exponential functionality also at long times. This result is therefore also valid for correlation functions of many-body Hamiltonian systems for which a power-law dependence, observed in restricted time ranges and predicted to be the asymptotic one, can be considered at most as a useful approximate modeling of long-time behavior.

  9. An improved parameter estimation and comparison for soft tissue constitutive models containing an exponential function.

    PubMed

    Aggarwal, Ankush

    2017-03-01

    Motivated by the well-known result that stiffness of soft tissue is proportional to the stress, many of the constitutive laws for soft tissues contain an exponential function. In this work, we analyze properties of the exponential function and how it affects the estimation and comparison of elastic parameters for soft tissues. In particular, we find that as a consequence of the exponential function there are lines of high covariance in the elastic parameter space. As a result, one can have widely varying mechanical parameters defining the tissue stiffness but similar effective stress-strain responses. Drawing from elementary algebra, we propose simple changes in the norm and the parameter space, which significantly improve the convergence of parameter estimation and robustness in the presence of noise. More importantly, we demonstrate that these changes improve the conditioning of the problem and provide a more robust solution in the case of heterogeneous material by reducing the chances of getting trapped in a local minima. Based upon the new insight, we also propose a transformed parameter space which will allow for rational parameter comparison and avoid misleading conclusions regarding soft tissue mechanics.

  10. Laplace transform and the Mittag-Leffler function

    NASA Astrophysics Data System (ADS)

    Sales Teodoro, G.; Capelas de Oliveira, E.

    2014-05-01

    The exponential function is solution of a linear differential equation with constant coefficients, and the Mittag-Leffler function is solution of a fractional linear differential equation with constant coefficients. Using infinite series and Laplace transform, we introduce the Mittag-Leffler function as a generalization of the exponential function. Particular cases are recovered.

  11. One-way transformation of information

    DOEpatents

    Cooper, James A.

    1989-01-01

    Method and apparatus are provided for one-way transformation of data according to multiplication and/or exponentiation modulo a prime number. An implementation of the invention permits the one way residue transformation, useful in encryption and similar applications, to be implemented by n-bit computers substantially with no increase in difficulty or complexity over a natural transformation thereby, using a modulus which is a power of two.

  12. Exponential growth combined with exponential decline explains lifetime performance evolution in individual and human species.

    PubMed

    Berthelot, Geoffroy; Len, Stéphane; Hellard, Philippe; Tafflet, Muriel; Guillaume, Marion; Vollmer, Jean-Claude; Gager, Bruno; Quinquis, Laurent; Marc, Andy; Toussaint, Jean-François

    2012-08-01

    The physiological parameters characterizing human capacities (the ability to move, reproduce or perform tasks) evolve with ageing: performance is limited at birth, increases to a maximum and then decreases back to zero at the day of death. Physical and intellectual skills follow such a pattern. Here, we investigate the development of sport and chess performances during the lifetime at two different scales: the individual athletes' careers and the world record by age class in 25 Olympic sports events and in grandmaster chess players. For all data sets, a biphasic development of growth and decline is described by a simple model that accounts for 91.7% of the variance at the individual level and 98.5% of the variance at the species one. The age of performance peak is computed at 26.1 years old for the events studied (26.0 years old for track and field, 21.0 years old for swimming and 31.4 years old for chess). The two processes (growth and decline) are exponential and start at age zero. Both were previously demonstrated to happen in other human and non-human biological functions that evolve with age. They occur at the individual and species levels with a similar pattern, suggesting a scale invariance property.

  13. Application of the stretched exponential function to fluorescence lifetime imaging.

    PubMed

    Lee, K C; Siegel, J; Webb, S E; Lévêque-Fort, S; Cole, M J; Jones, R; Dowling, K; Lever, M J; French, P M

    2001-09-01

    Conventional analyses of fluorescence lifetime measurements resolve the fluorescence decay profile in terms of discrete exponential components with distinct lifetimes. In complex, heterogeneous biological samples such as tissue, multi-exponential decay functions can appear to provide a better fit to fluorescence decay data than the assumption of a mono-exponential decay, but the assumption of multiple discrete components is essentially arbitrary and is often erroneous. Moreover, interactions, both between fluorophores and with their environment, can result in complex fluorescence decay profiles that represent a continuous distribution of lifetimes. Such continuous distributions have been reported for tryptophan, which is one of the main fluorophores in tissue. This situation is better represented by the stretched-exponential function (StrEF). In this work, we have applied, for the first time to our knowledge, the StrEF to time-domain whole-field fluorescence lifetime imaging (FLIM), yielding both excellent tissue contrast and goodness of fit using data from rat tissue. We note that for many biological samples for which there is no a priori knowledge of multiple discrete exponential fluorescence decay profiles, the StrEF is likely to provide a truer representation of the underlying fluorescence dynamics. Furthermore, fitting to a StrEF significantly decreases the required processing time, compared with a multi-exponential component fit and typically provides improved contrast and signal/noise in the resulting FLIM images. In addition, the stretched-exponential decay model can provide a direct measure of the heterogeneity of the sample, and the resulting heterogeneity map can reveal subtle tissue differences that other models fail to show.

  14. New methods for accelerating the convergence of molecular electronic integrals over exponential type orbitals

    NASA Astrophysics Data System (ADS)

    Safouhi, Hassan; Hoggan, Philip

    2003-01-01

    This review on molecular integrals for large electronic systems (MILES) places the problem of analytical integration over exponential-type orbitals (ETOs) in a historical context. After reference to the pioneering work, particularly by Barnett, Shavitt and Yoshimine, it focuses on recent progress towards rapid and accurate analytic solutions of MILES over ETOs. Software such as the hydrogenlike wavefunction package Alchemy by Yoshimine and collaborators is described. The review focuses on convergence acceleration of these highly oscillatory integrals and in particular it highlights suitable nonlinear transformations. Work by Levin and Sidi is described and applied to MILES. A step by step description of progress in the use of nonlinear transformation methods to obtain efficient codes is provided. The recent approach developed by Safouhi is also presented. The current state of the art in this field is summarized to show that ab initio analytical work over ETOs is now a viable option.

  15. Stagnation point flow and heat transfer behavior of Cu-water nanofluid towards horizontal and exponentially stretching/shrinking cylinders

    NASA Astrophysics Data System (ADS)

    Sulochana, C.; Sandeep, N.

    2016-03-01

    In this study we analyzed the stagnation point flow and heat transfer behavior of Cu-water nanofluid towards horizontal and exponentially permeable stretching/shrinking cylinders in presence of suction/injection, heat source and shape of nanoparticles. The governing boundary layer equations are transformed to nonlinear ordinary differential equations using similarity transformation which are then solved numerically using bvp4c Matlab package. The influence of non-dimensional governing parameters on the flow field and heat transfer characteristics are discussed and presented through graphs and tables. The study indicates that the solutions for the horizontal and exponential cylinders are non-unique and shape of nanoparticles also influences the rate of heat transfer. Comparisons of the present results with existed studies are presented. Present study has an excellent agreement with the existed studies under some special conditions.

  16. Assortment and the evolution of cooperation in a Moran process with exponential fitness.

    PubMed

    Cooney, Daniel; Allen, Benjamin; Veller, Carl

    2016-11-21

    We study the evolution of cooperation in a finite population interacting according to a simple model of like-with-like assortment. Evolution proceeds as a Moran process, and payoffs from the underlying cooperator-defector game are translated to positive fitnesses by an exponential transformation. These evolutionary dynamics can arise, for example, in a nest-structured population with rare migration. The use of the exponential transformation, rather than the usual linear one, is appropriate when interactions have multiplicative fitness effects, and allows for a tractable characterisation of the effect of assortment on the evolution of cooperation. We define two senses in which a greater degree of assortment can favour the evolution of cooperation, the first stronger than the second: (i) greater assortment increases, at all population states, the probability that the number of cooperators increases, relative to the probability that the number of defectors increases; and (ii) greater assortment increases the fixation probability of cooperation, relative to that of defection. We show that, by the stronger definition, greater assortment favours the evolution of cooperation for a subset of cooperative dilemmas: prisoners' dilemmas, snowdrift games, stag-hunt games, and some prisoners' delight games. For other cooperative dilemmas, greater assortment favours cooperation by the weak definition, but not by the strong definition. We also show that increasing assortment expands the set of games in which cooperation dominates the evolutionary dynamics. Our results hold for any strength of selection. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Non-exponential and oscillatory decays in quantum mechanics

    SciTech Connect

    Peshkin, Murray; Volya, Alexander; Zelevinsky, Vladimir

    2014-08-07

    The quantum-mechanical theory of the decay of unstable states is revisited. We show that the decay is non-exponential both in the short-time and long-time limits using a more physical definition of the decay rate than the one usually used. We report results of numerical studies based on Winter's model that may elucidate qualitative features of exponential and non-exponential decay more generally. The main exponential stage is related to the formation of a radiating state that maintains the shape of its wave function with exponentially diminishing normalization. We discuss situations where the radioactive decay displays several exponents. The transient stages between different regimes are typically accompanied by interference of various contributions and resulting oscillations in the decay curve. The decay curve can be fully oscillatory in a two-flavor generalization of Winter's model with some values of the parameters. We consider the implications of that result for models of the oscillations reported by GSI.

  18. Non-exponential and oscillatory decays in quantum mechanics

    NASA Astrophysics Data System (ADS)

    Peshkin, Murray; Volya, Alexander; Zelevinsky, Vladimir

    2014-08-01

    The quantum-mechanical theory of the decay of unstable states is revisited. We show that the decay is non-exponential both in the short-time and long-time limits using a more physical definition of the decay rate than the one usually used. We report results of numerical studies based on Winter's model that may elucidate qualitative features of exponential and non-exponential decay more generally. The main exponential stage is related to the formation of a radiating state that maintains the shape of its wave function with exponentially diminishing normalization. We discuss situations where the radioactive decay displays several exponents. The transient stages between different regimes are typically accompanied by interference of various contributions and resulting oscillations in the decay curve. The decay curve can be fully oscillatory in a two-flavor generalization of Winter's model with some values of the parameters. We consider the implications of that result for models of the oscillations reported by GSI.

  19. Bayesian estimation of generalized exponential distribution under noninformative priors

    NASA Astrophysics Data System (ADS)

    Moala, Fernando Antonio; Achcar, Jorge Alberto; Tomazella, Vera Lúcia Damasceno

    2012-10-01

    The generalized exponential distribution, proposed by Gupta and Kundu (1999), is a good alternative to standard lifetime distributions as exponential, Weibull or gamma. Several authors have considered the problem of Bayesian estimation of the parameters of generalized exponential distribution, assuming independent gamma priors and other informative priors. In this paper, we consider a Bayesian analysis of the generalized exponential distribution by assuming the conventional noninformative prior distributions, as Jeffreys and reference prior, to estimate the parameters. These priors are compared with independent gamma priors for both parameters. The comparison is carried out by examining the frequentist coverage probabilities of Bayesian credible intervals. We shown that maximal data information prior implies in an improper posterior distribution for the parameters of a generalized exponential distribution. It is also shown that the choice of a parameter of interest is very important for the reference prior. The different choices lead to different reference priors in this case. Numerical inference is illustrated for the parameters by considering data set of different sizes and using MCMC (Markov Chain Monte Carlo) methods.

  20. High-frequency broadband transformers

    NASA Astrophysics Data System (ADS)

    London, S. E.; Tomashevich, S. V.

    1981-05-01

    A systematic review of the theory and design principles of high-frequency broadband transformers is presented. It is shown that the transformers of highest performance are those whose coils consist of strips of double-wire and multiwire transmission lines. Such devices are characterized by a wide operating frequency range, and make possible operation at microwave frequencies at high levels of transmitted power.

  1. κ-deformed Fourier transform

    NASA Astrophysics Data System (ADS)

    Scarfone, A. M.

    2017-08-01

    We present a new formulation of Fourier transform in the picture of the κ-algebra derived in the framework of the κ-generalized statistical mechanics. The κ-Fourier transform is obtained from a κ-Fourier series recently introduced by Scarfone (2013). The kernel of this transform, that reduces to the usual exponential phase in the κ → 0 limit, is composed by a κ-deformed phase and a damping factor that gives a wavelet-like behaviour. We show that the κ-Fourier transform is isomorph to the standard Fourier transform through a changing of time and frequency variables. Nevertheless, the new formalism is useful to study, according to Fourier analysis, those functions defined in the realm of the κ-algebra. As a relevant application, we discuss the central limit theorem for the κ-sum of n-iterate statistically independent random variables.

  2. Exponential Sensitivity and its Cost in Quantum Physics.

    PubMed

    Gilyén, András; Kiss, Tamás; Jex, Igor

    2016-02-10

    State selective protocols, like entanglement purification, lead to an essentially non-linear quantum evolution, unusual in naturally occurring quantum processes. Sensitivity to initial states in quantum systems, stemming from such non-linear dynamics, is a promising perspective for applications. Here we demonstrate that chaotic behaviour is a rather generic feature in state selective protocols: exponential sensitivity can exist for all initial states in an experimentally realisable optical scheme. Moreover, any complex rational polynomial map, including the example of the Mandelbrot set, can be directly realised. In state selective protocols, one needs an ensemble of initial states, the size of which decreases with each iteration. We prove that exponential sensitivity to initial states in any quantum system has to be related to downsizing the initial ensemble also exponentially. Our results show that magnifying initial differences of quantum states (a Schrödinger microscope) is possible; however, there is a strict bound on the number of copies needed.

  3. Design of a 9-loop quasi-exponential waveform generator.

    PubMed

    Banerjee, Partha; Shukla, Rohit; Shyam, Anurag

    2015-12-01

    We know in an under-damped L-C-R series circuit, current follows a damped sinusoidal waveform. But if a number of sinusoidal waveforms of decreasing time period, generated in an L-C-R circuit, be combined in first quarter cycle of time period, then a quasi-exponential nature of output current waveform can be achieved. In an L-C-R series circuit, quasi-exponential current waveform shows a rising current derivative and thereby finds many applications in pulsed power. Here, we have described design and experiment details of a 9-loop quasi-exponential waveform generator. In that, design details of magnetic switches have also been described. In the experiment, output current of 26 kA has been achieved. It has been shown that how well the experimentally obtained output current profile matches with the numerically computed output.

  4. Exponential rise of dynamical complexity in quantum computing through projections

    PubMed Central

    Burgarth, Daniel Klaus; Facchi, Paolo; Giovannetti, Vittorio; Nakazato, Hiromichi; Pascazio, Saverio; Yuasa, Kazuya

    2014-01-01

    The ability of quantum systems to host exponentially complex dynamics has the potential to revolutionize science and technology. Therefore, much effort has been devoted to developing of protocols for computation, communication and metrology, which exploit this scaling, despite formidable technical difficulties. Here we show that the mere frequent observation of a small part of a quantum system can turn its dynamics from a very simple one into an exponentially complex one, capable of universal quantum computation. After discussing examples, we go on to show that this effect is generally to be expected: almost any quantum dynamics becomes universal once ‘observed’ as outlined above. Conversely, we show that any complex quantum dynamics can be ‘purified’ into a simpler one in larger dimensions. We conclude by demonstrating that even local noise can lead to an exponentially complex dynamics. PMID:25300692

  5. Exponential Sensitivity and its Cost in Quantum Physics

    NASA Astrophysics Data System (ADS)

    Gilyén, András; Kiss, Tamás; Jex, Igor

    2016-02-01

    State selective protocols, like entanglement purification, lead to an essentially non-linear quantum evolution, unusual in naturally occurring quantum processes. Sensitivity to initial states in quantum systems, stemming from such non-linear dynamics, is a promising perspective for applications. Here we demonstrate that chaotic behaviour is a rather generic feature in state selective protocols: exponential sensitivity can exist for all initial states in an experimentally realisable optical scheme. Moreover, any complex rational polynomial map, including the example of the Mandelbrot set, can be directly realised. In state selective protocols, one needs an ensemble of initial states, the size of which decreases with each iteration. We prove that exponential sensitivity to initial states in any quantum system has to be related to downsizing the initial ensemble also exponentially. Our results show that magnifying initial differences of quantum states (a Schrödinger microscope) is possible; however, there is a strict bound on the number of copies needed.

  6. Rotational stretched exponential relaxation in random trap-barrier model

    NASA Astrophysics Data System (ADS)

    Aydiner, Ekrem

    2015-07-01

    The relaxation behavior of complex-disordered systems, such as spin glasses, polymers, colloidal suspensions, structural glasses,and granular media, has not been clarified. Theoretical studies show that relaxation in these systems has a topological origin. In this paper, we focus on the rotational stretched exponential relaxation behavior in complex-disordered systems and introduce a simple phase space model to understand the mechanism of the non-exponential relaxation of these systems. By employing the Monte Carlo simulation method to the model, we obtain the rotational relaxation function as a function of temperature. We show that the relaxation function has a stretched exponential form under the critical temperature while it obeys the Debye law above the critical temperature. Project supported by Istanbul University (Grant Nos. 28432 and 45662).

  7. Exponential Sensitivity and its Cost in Quantum Physics

    PubMed Central

    Gilyén, András; Kiss, Tamás; Jex, Igor

    2016-01-01

    State selective protocols, like entanglement purification, lead to an essentially non-linear quantum evolution, unusual in naturally occurring quantum processes. Sensitivity to initial states in quantum systems, stemming from such non-linear dynamics, is a promising perspective for applications. Here we demonstrate that chaotic behaviour is a rather generic feature in state selective protocols: exponential sensitivity can exist for all initial states in an experimentally realisable optical scheme. Moreover, any complex rational polynomial map, including the example of the Mandelbrot set, can be directly realised. In state selective protocols, one needs an ensemble of initial states, the size of which decreases with each iteration. We prove that exponential sensitivity to initial states in any quantum system has to be related to downsizing the initial ensemble also exponentially. Our results show that magnifying initial differences of quantum states (a Schrödinger microscope) is possible; however, there is a strict bound on the number of copies needed. PMID:26861076

  8. Exponential rise of dynamical complexity in quantum computing through projections.

    PubMed

    Burgarth, Daniel Klaus; Facchi, Paolo; Giovannetti, Vittorio; Nakazato, Hiromichi; Pascazio, Saverio; Yuasa, Kazuya

    2014-10-10

    The ability of quantum systems to host exponentially complex dynamics has the potential to revolutionize science and technology. Therefore, much effort has been devoted to developing of protocols for computation, communication and metrology, which exploit this scaling, despite formidable technical difficulties. Here we show that the mere frequent observation of a small part of a quantum system can turn its dynamics from a very simple one into an exponentially complex one, capable of universal quantum computation. After discussing examples, we go on to show that this effect is generally to be expected: almost any quantum dynamics becomes universal once 'observed' as outlined above. Conversely, we show that any complex quantum dynamics can be 'purified' into a simpler one in larger dimensions. We conclude by demonstrating that even local noise can lead to an exponentially complex dynamics.

  9. On the performance of exponential integrators for problems in magnetohydrodynamics

    NASA Astrophysics Data System (ADS)

    Einkemmer, Lukas; Tokman, Mayya; Loffeld, John

    2017-02-01

    Exponential integrators have been introduced as an efficient alternative to explicit and implicit methods for integrating large stiff systems of differential equations. Over the past decades these methods have been studied theoretically and their performance was evaluated using a range of test problems. While the results of these investigations showed that exponential integrators can provide significant computational savings, the research on validating this hypothesis for large scale systems and understanding what classes of problems can particularly benefit from the use of the new techniques is in its initial stages. Resistive magnetohydrodynamic (MHD) modeling is widely used in studying large scale behavior of laboratory and astrophysical plasmas. In many problems numerical solution of MHD equations is a challenging task due to the temporal stiffness of this system in the parameter regimes of interest. In this paper we evaluate the performance of exponential integrators on large MHD problems and compare them to a state-of-the-art implicit time integrator. Both the variable and constant time step exponential methods of EPIRK-type are used to simulate magnetic reconnection and the Kevin-Helmholtz instability in plasma. Performance of these methods, which are part of the EPIC software package, is compared to the variable time step variable order BDF scheme included in the CVODE (part of SUNDIALS) library. We study performance of the methods on parallel architectures and with respect to magnitudes of important parameters such as Reynolds, Lundquist, and Prandtl numbers. We find that the exponential integrators provide superior or equal performance in most circumstances and conclude that further development of exponential methods for MHD problems is warranted and can lead to significant computational advantages for large scale stiff systems of differential equations such as MHD.

  10. Is it growing exponentially fast? -- Impact of assuming exponential growth for characterizing and forecasting epidemics with initial near-exponential growth dynamics.

    PubMed

    Chowell, Gerardo; Viboud, Cécile

    2016-10-01

    The increasing use of mathematical models for epidemic forecasting has highlighted the importance of designing models that capture the baseline transmission characteristics in order to generate reliable epidemic forecasts. Improved models for epidemic forecasting could be achieved by identifying signature features of epidemic growth, which could inform the design of models of disease spread and reveal important characteristics of the transmission process. In particular, it is often taken for granted that the early growth phase of different growth processes in nature follow early exponential growth dynamics. In the context of infectious disease spread, this assumption is often convenient to describe a transmission process with mass action kinetics using differential equations and generate analytic expressions and estimates of the reproduction number. In this article, we carry out a simulation study to illustrate the impact of incorrectly assuming an exponential-growth model to characterize the early phase (e.g., 3-5 disease generation intervals) of an infectious disease outbreak that follows near-exponential growth dynamics. Specifically, we assess the impact on: 1) goodness of fit, 2) bias on the growth parameter, and 3) the impact on short-term epidemic forecasts. Designing transmission models and statistical approaches that more flexibly capture the profile of epidemic growth could lead to enhanced model fit, improved estimates of key transmission parameters, and more realistic epidemic forecasts.

  11. Exponential velocity profile of granular flows down a confined heap.

    PubMed

    Martínez, E; González-Lezcano, A; Batista-Leyva, A J; Altshuler, E

    2016-06-01

    Thick granular flows are essential to many natural and industrial phenomena. Experimentally, it has been well established that the grain velocity profile is linear from the free surface to a certain depth, after which it decreases exponentially in the so-called "creep region". In this paper we obtain an exponential velocity profile based on the force balance of a grain near a wall, where the Janssen effect and the non-locality of interactions between grains are considered. When experimental parameters such as flow angles and friction coefficients are introduced in our model, it is able to reproduce experimental creep velocity profiles previously reported in the literature.

  12. New results on robust exponential stability of integral delay systems

    NASA Astrophysics Data System (ADS)

    Melchor-Aguilar, Daniel

    2016-06-01

    The robust exponential stability of integral delay systems with exponential kernels is investigated. Sufficient delay-dependent robust conditions expressed in terms of linear matrix inequalities and matrix norms are derived by using the Lyapunov-Krasovskii functional approach. The results are combined with a new result on quadratic stabilisability of the state-feedback synthesis problem in order to derive a new linear matrix inequality methodology of designing a robust non-fragile controller for the finite spectrum assignment of input delay systems that guarantees simultaneously a numerically safe implementation and also the robustness to uncertainty in the system matrices and to perturbation in the feedback gain.

  13. Application of Krylov exponential propagation to fluid dynamics equations

    NASA Technical Reports Server (NTRS)

    Saad, Youcef; Semeraro, David

    1991-01-01

    An application of matrix exponentiation via Krylov subspace projection to the solution of fluid dynamics problems is presented. The main idea is to approximate the operation exp(A)v by means of a projection-like process onto a krylov subspace. This results in a computation of an exponential matrix vector product similar to the one above but of a much smaller size. Time integration schemes can then be devised to exploit this basic computational kernel. The motivation of this approach is to provide time-integration schemes that are essentially of an explicit nature but which have good stability properties.

  14. Real-Time Exponential Curve Fits Using Discrete Calculus

    NASA Technical Reports Server (NTRS)

    Rowe, Geoffrey

    2010-01-01

    An improved solution for curve fitting data to an exponential equation (y = Ae(exp Bt) + C) has been developed. This improvement is in four areas -- speed, stability, determinant processing time, and the removal of limits. The solution presented avoids iterative techniques and their stability errors by using three mathematical ideas: discrete calculus, a special relationship (be tween exponential curves and the Mean Value Theorem for Derivatives), and a simple linear curve fit algorithm. This method can also be applied to fitting data to the general power law equation y = Ax(exp B) + C and the general geometric growth equation y = Ak(exp Bt) + C.

  15. Circuit design and exponential stabilization of memristive neural networks.

    PubMed

    Wen, Shiping; Huang, Tingwen; Zeng, Zhigang; Chen, Yiran; Li, Peng

    2015-03-01

    This paper addresses the problem of circuit design and global exponential stabilization of memristive neural networks with time-varying delays and general activation functions. Based on the Lyapunov-Krasovskii functional method and free weighting matrix technique, a delay-dependent criteria for the global exponential stability and stabilization of memristive neural networks are derived in form of linear matrix inequalities (LMIs). Two numerical examples are elaborated to illustrate the characteristics of the results. It is noteworthy that the traditional assumptions on the boundness of the derivative of the time-varying delays are removed.

  16. Exponential sensitivity of noise-driven switching in genetic networks

    NASA Astrophysics Data System (ADS)

    Mehta, Pankaj; Mukhopadhyay, Ranjan; Wingreen, Ned

    2008-03-01

    Cells are known to utilize biochemical noise to probabilistically switch between distinct gene expression states. We demonstrate that such noise-driven switching is dominated by tails of probability distributions and is therefore exponentially sensitive to changes in physiological parameters such as transcription and translation rates. However, provided mRNA lifetimes are short, switching can still be accurately simulated using protein-only models of gene expression. Exponential sensitivity limits the robustness of noise-driven switching, suggesting cells may use other mechanisms in order to switch reliably.

  17. Exponential sensitivity of noise-driven switching in genetic networks

    NASA Astrophysics Data System (ADS)

    Mehta, Pankaj; Mukhopadhyay, Ranjan; Wingreen, Ned S.

    2008-06-01

    There is increasing experimental evidence that cells can utilize biochemical noise to switch probabilistically between distinct gene-expression states. In this paper, we demonstrate that such noise-driven switching is dominated by tails of probability distributions and is therefore exponentially sensitive to changes in physiological parameters such as transcription and translation rates. Exponential sensitivity limits the robustness of noise-driven switching, suggesting cells may use other mechanisms in order to switch reliably. We discuss our results in the context of competence in the bacterium Bacillus subtilis.

  18. Numerical Studies of Non-Exponential Decay of Wavefunctions

    NASA Astrophysics Data System (ADS)

    Vermedahl, Jon; Petridis, Athanasios; Luban, Marshall; Staunton, Lawrence

    2002-04-01

    We use the staggered-leap-frog algorithm to numerically solve the time-dependent Schrödinger equation. This algorithm is particularly accurate and stable as demonstrated in a number of cases whose solutions are analytically known. Deviations from exponential decay have been established for short times for a wavefunction initially set within finite depth potential wells. The survival probability has been fit with analytical functions that reproduce exponential decay at long times. Various time scales characterizing the decay are thus extracted.

  19. Exponential model for option prices: Application to the Brazilian market

    NASA Astrophysics Data System (ADS)

    Ramos, Antônio M. T.; Carvalho, J. A.; Vasconcelos, G. L.

    2016-03-01

    In this paper we report an empirical analysis of the Ibovespa index of the São Paulo Stock Exchange and its respective option contracts. We compare the empirical data on the Ibovespa options with two option pricing models, namely the standard Black-Scholes model and an empirical model that assumes that the returns are exponentially distributed. It is found that at times near the option expiration date the exponential model performs better than the Black-Scholes model, in the sense that it fits the empirical data better than does the latter model.

  20. Stretched-exponential Doppler spectra in underwater acoustic communication channels.

    PubMed

    van Walree, P A; Jenserud, T; Otnes, R

    2010-11-01

    The theory of underwater sound interacting with the sea surface predicts a Gaussian-spread frequency spectrum in the case of a large Rayleigh parameter. However, recent channel soundings reveal more sharply peaked spectra with heavier tails. The measured Doppler spread increases with the frequency and differs between multipath arrivals. The overall Doppler spectrum of a broadband waveform is the sum of the spectra of all constituent paths and frequencies, and is phenomenologically described by a stretched or compressed exponential. The stretched exponential also fits well to the broadband spectrum of a single propagation path, and narrowband spectra summed over all paths.

  1. Robust exponential acceleration in time-dependent billiards.

    PubMed

    Gelfreich, Vassili; Rom-Kedar, Vered; Shah, Kushal; Turaev, Dmitry

    2011-02-18

    A class of nonrelativistic particle accelerators in which the majority of particles gain energy at an exponential rate is constructed. The class includes ergodic billiards with a piston that moves adiabatically and is removed adiabatically in a periodic fashion. The phenomenon is robust: deformations that keep the chaotic character of the billiard retain the exponential energy growth. The growth rate is found analytically and is, thus, controllable. Numerical simulations corroborate the analytic predictions with good precision. The acceleration mechanism has a natural thermodynamical interpretation and is applied to a hot dilute gas of repelling particles.

  2. Single-pool exponential decomposition models: potential pitfalls in their use in ecological studies.

    PubMed

    Adair, E Carol; Hobbie, Sarah E; Hobbie, Russell K

    2010-04-01

    The importance of litter decomposition to carbon and nutrient cycling has motivated substantial research. Commonly, researchers fit a single-pool negative exponential model to data to estimate a decomposition rate (k). We review recent decomposition research, use data simulations, and analyze real data to show that this practice has several potential pitfalls. Specifically, two common decisions regarding model form (how to model initial mass) and data transformation (log-transformed vs. untransformed data) can lead to erroneous estimates of k. Allowing initial mass to differ from its true, measured value resulted in substantial over- or underestimation of k. Log-transforming data to estimate k using linear regression led to inaccurate estimates unless errors were lognormally distributed, while nonlinear regression of untransformed data accurately estimated k regardless of error structure. Therefore, we recommend fixing initial mass at the measured value and estimating k with nonlinear regression (untransformed data) unless errors are demonstrably lognormal. If data are log-transformed for linear regression, zero values should be treated as missing data; replacing zero values with an arbitrarily small value yielded poor k estimates. These recommendations will lead to more accurate k estimates and allow cross-study comparison of k values, increasing understanding of this important ecosystem process.

  3. From Exponential to Polynomial-Time Security Typing via Principal Types

    NASA Astrophysics Data System (ADS)

    Hunt, Sebastian; Sands, David

    Hunt and Sands (POPL'06) studied a flow sensitive type (FST) system for multi-level security, parametric in the choice of lattice of security levels. Choosing the powerset of program variables as the security lattice yields a system which was shown to be equivalent to Amtoft and Banerjee's Hoare-style independence logic (SAS'04). Moreover, using the powerset lattice, it was shown how to derive a principal type from which all other types (for all choices of lattice) can be simply derived.Both of these earlier works gave "algorithmic" formulations of the type system/program logic, but both algorithms are of exponential complexity due to the iterative typing of While loops. Later work by Hunt and Sands (ESOP'08) adapted the FST system to provide an erasure type system which determines whether some input is correctly erased at a designated time. This type system is inherently exponential, requiring a double typing of the erasure-labelled input command. In this paper we start by developing the FST work in two key ways: (1) We specialise the FST system to a form which only derives principal types; the resulting type system has a simple algorithmic reading, yielding principal security types in polynomial time. (2) We show how the FST system can be simply extended to check for various degrees of termination sensitivity (the original FST system is completely termination insensitive, while the erasure type system is fully termination sensitive). We go on to demonstrate the power of these techniques by combining them to develop a type system which is shown to correctly implement erasure typing in polynomial time. Principality is used in an essential way to reduce type derivation size from exponential to linear.

  4. Double helicenes

    NASA Astrophysics Data System (ADS)

    Bachrach, Steven M.

    2016-12-01

    The even double helicenes with 4-12 phenyl groups in each helix were examined at B3LYP-D3/6-311G(d). The double helicenes with 4-10 phenyl rings are less than twice as strained as their component helicenes; the strain results from twisting about the shared naphthyl moiety, with accompanying loss of aromaticity. These compounds should be reasonable synthetic targets, and computed NMR shifts are provided to aid in their characterization.

  5. Approximating Exponential and Logarithmic Functions Using Polynomial Interpolation

    ERIC Educational Resources Information Center

    Gordon, Sheldon P.; Yang, Yajun

    2017-01-01

    This article takes a closer look at the problem of approximating the exponential and logarithmic functions using polynomials. Either as an alternative to or a precursor to Taylor polynomial approximations at the precalculus level, interpolating polynomials are considered. A measure of error is given and the behaviour of the error function is…

  6. Approximating Exponential and Logarithmic Functions Using Polynomial Interpolation

    ERIC Educational Resources Information Center

    Gordon, Sheldon P.; Yang, Yajun

    2017-01-01

    This article takes a closer look at the problem of approximating the exponential and logarithmic functions using polynomials. Either as an alternative to or a precursor to Taylor polynomial approximations at the precalculus level, interpolating polynomials are considered. A measure of error is given and the behaviour of the error function is…

  7. Concept of the Exponential Law Prior to 1900

    ERIC Educational Resources Information Center

    Curtis, Lorenzo J.

    1978-01-01

    Presents the historical development of perceptions and applications of the exponential law, tracing it from its ancient origins until the year 1900. Shows that many concepts such as mean life and half life and their relationships to differential equations were known long before their application to nuclear radioactivity. (GA)

  8. Extreme rainfall distribution tails: Exponential, subexponential or hyperexponential?

    NASA Astrophysics Data System (ADS)

    Nerantzaki, Sofia; Papalexiou, Simon Michael; Koutsoyiannis, Demetris

    2013-04-01

    The upper tail of a probability distribution controls the behavior of both the magnitude and the frequency of extreme events. In general, based on their tail behavior, probability distributions can be categorized into two families (with reference to the exponential distribution): subexponential and hyperexponential. The latter corresponds to milder and less frequent extremes. In order to evaluate the behavior of rainfall extremes, we examine data from 3 477 stations from all over the world with sample size over 100 years. We apply the Mean Excess Function (MEF) which is a common graphical method that results in a zero slope line when applied to exponentially distributed data and in a positive slope in the case of subexponential distributions. To implement the method, we constructed confidence intervals for the slope of the Exponential distribution as functions of the sample size. The validation of the method using Monte Carlo techniques reveals that it performs well especially for large samples. The analysis shows that subexponential distributions are generally in better agreement with rainfall extremes compared to the commonly used exponential ones.

  9. Teaching Exponential Growth and Decay: Examples from Medicine

    ERIC Educational Resources Information Center

    Hobbie, Russell K.

    1973-01-01

    A treatment of exponential growth and decay is sketched which does not require knowledge of calculus, and hence, it can be applied to many cases in the biological and medical sciences. Some examples are bacterial growth, sterilization, clearance, and drug absorption. (DF)

  10. Modelling income data using two extensions of the exponential distribution

    NASA Astrophysics Data System (ADS)

    Calderín-Ojeda, Enrique; Azpitarte, Francisco; Gómez-Déniz, Emilio

    2016-11-01

    In this paper we propose two extensions of the Exponential model to describe income distributions. The Exponential ArcTan (EAT) and the composite EAT-Lognormal models discussed in this paper preserve key properties of the Exponential model including its capacity to model distributions with zero incomes. This is an important feature as the presence of zeros conditions the modelling of income distributions as it rules out the possibility of using many parametric models commonly used in the literature. Many researchers opt for excluding the zeros from the analysis, however, this may not be a sensible approach especially when the number of zeros is large or if one is interested in accurately describing the lower part of the distribution. We apply the EAT and the EAT-Lognormal models to study the distribution of incomes in Australia for the period 2001-2012. We find that these models in general outperform the Gamma and Exponential models while preserving the capacity of the latter to model zeros.

  11. Teaching Exponential Growth and Decay: Examples from Medicine

    ERIC Educational Resources Information Center

    Hobbie, Russell K.

    1973-01-01

    A treatment of exponential growth and decay is sketched which does not require knowledge of calculus, and hence, it can be applied to many cases in the biological and medical sciences. Some examples are bacterial growth, sterilization, clearance, and drug absorption. (DF)

  12. Exponential dichotomy for hyperbolic systems with periodic boundary conditions

    NASA Astrophysics Data System (ADS)

    Klyuchnyk, R.; Kmit, I.; Recke, L.

    2017-02-01

    We investigate evolution families generated by general linear first-order hyperbolic systems in one space dimension with periodic boundary conditions. We state explicit conditions on the coefficient functions that are sufficient for the existence of exponential dichotomies on R in the space of continuous periodic functions.

  13. Min and Max Exponential Extreme Interval Values and Statistics

    ERIC Educational Resources Information Center

    Jance, Marsha; Thomopoulos, Nick

    2009-01-01

    The extreme interval values and statistics (expected value, median, mode, standard deviation, and coefficient of variation) for the smallest (min) and largest (max) values of exponentially distributed variables with parameter ? = 1 are examined for different observation (sample) sizes. An extreme interval value g[subscript a] is defined as a…

  14. Exponentially Fitted Variants of Euler's Method for ODEs

    ERIC Educational Resources Information Center

    Kanwar, V.; Tomar, S. K.

    2008-01-01

    A new class of Euler's method for the numerical solution of ordinary differential equations is presented in this article. The methods are iterative in nature and admit their geometric derivation from an exponentially fitted osculating straight line. They are single-step methods and do not require evaluation of any derivatives. The accuracy and…

  15. Exponential Values for the Species-Area Relation.

    PubMed

    Kilburn, P D

    1963-09-27

    Data on vegetation types in six 900-m(2) plots in the Midwest reveal that the species-area curves are not logarithmic but more nearly approach an exponential equation of the form y = kx(2) for areas less than 100 m(2). For larger areas the curve appears to be sigmoid.

  16. Looking for Connections between Linear and Exponential Functions

    ERIC Educational Resources Information Center

    Lo, Jane-Jane; Kratky, James L.

    2012-01-01

    Students frequently have difficulty determining whether a given real-life situation is best modeled as a linear relationship or as an exponential relationship. One root of such difficulty is the lack of deep understanding of the very concept of "rate of change." The authors will provide a lesson that allows students to reveal their misconceptions…

  17. Concept of the Exponential Law Prior to 1900

    ERIC Educational Resources Information Center

    Curtis, Lorenzo J.

    1978-01-01

    Presents the historical development of perceptions and applications of the exponential law, tracing it from its ancient origins until the year 1900. Shows that many concepts such as mean life and half life and their relationships to differential equations were known long before their application to nuclear radioactivity. (GA)

  18. Looking for Connections between Linear and Exponential Functions

    ERIC Educational Resources Information Center

    Lo, Jane-Jane; Kratky, James L.

    2012-01-01

    Students frequently have difficulty determining whether a given real-life situation is best modeled as a linear relationship or as an exponential relationship. One root of such difficulty is the lack of deep understanding of the very concept of "rate of change." The authors will provide a lesson that allows students to reveal their misconceptions…

  19. Exponential passivity for output feedback stabilisation of nonlinear uncertain systems

    NASA Astrophysics Data System (ADS)

    Benabdallah, Amel

    2010-11-01

    In this article, we address the problem of stabilisation by output feedback for a class of uncertain systems. We consider uncertain systems with a nominal part which is affine in the control and an uncertain part which is norm bounded by a known function. We propose an output feedback such that the closed loop system is globally exponentially stable.

  20. On Fractional Derivatives with Exponential Kernel and their Discrete Versions

    NASA Astrophysics Data System (ADS)

    Abdeljawad, Thabet; Baleanu, Dumitru

    2017-08-01

    In this paper we define the right fractional derivative and its corresponding right fractional integral with exponential kernel. We provide the integration by parts formula and we use the Q-operator to confirm our results. The related Euler-Lagrange equations are obtained and one example is reported. Moreover, we formulate and discuss the discrete counterparts of our results.

  1. Clinical proteomics in kidney disease as an exponential technology: heading towards the disruptive phase.

    PubMed

    Sanchez-Niño, Maria Dolores; Sanz, Ana B; Ramos, Adrian M; Fernandez-Fernandez, Beatriz; Ortiz, Alberto

    2017-04-01

    Exponential technologies double in power or processing speed every year, whereas their cost halves. Deception and disruption are two key stages in the development of exponential technologies. Deception occurs when, after initial introduction, technologies are dismissed as irrelevant, while they continue to progress, perhaps not as fast or with so many immediate practical applications as initially thought. Twenty years after the first publications, clinical proteomics is still not available in most hospitals and some clinicians have felt deception at unfulfilled promises. However, there are indications that clinical proteomics may be entering the disruptive phase, where, once refined, technologies disrupt established industries or procedures. In this regard, recent manuscripts in CKJ illustrate how proteomics is entering the clinical realm, with applications ranging from the identification of amyloid proteins in the pathology lab, to a new generation of urinary biomarkers for chronic kidney disease (CKD) assessment and outcome prediction. Indeed, one such panel of urinary peptidomics biomarkers, CKD273, recently received a Food and Drug Administration letter of support, the first ever in the CKD field. In addition, a must-read resource providing information on kidney disease-related proteomics and systems biology databases and how to access and use them in clinical decision-making was also recently published in CKJ.

  2. Clinical proteomics in kidney disease as an exponential technology: heading towards the disruptive phase

    PubMed Central

    Sanchez-Niño, Maria Dolores; Sanz, Ana B.; Ramos, Adrian M.; Fernandez-Fernandez, Beatriz

    2017-01-01

    Abstract Exponential technologies double in power or processing speed every year, whereas their cost halves. Deception and disruption are two key stages in the development of exponential technologies. Deception occurs when, after initial introduction, technologies are dismissed as irrelevant, while they continue to progress, perhaps not as fast or with so many immediate practical applications as initially thought. Twenty years after the first publications, clinical proteomics is still not available in most hospitals and some clinicians have felt deception at unfulfilled promises. However, there are indications that clinical proteomics may be entering the disruptive phase, where, once refined, technologies disrupt established industries or procedures. In this regard, recent manuscripts in CKJ illustrate how proteomics is entering the clinical realm, with applications ranging from the identification of amyloid proteins in the pathology lab, to a new generation of urinary biomarkers for chronic kidney disease (CKD) assessment and outcome prediction. Indeed, one such panel of urinary peptidomics biomarkers, CKD273, recently received a Food and Drug Administration letter of support, the first ever in the CKD field. In addition, a must-read resource providing information on kidney disease-related proteomics and systems biology databases and how to access and use them in clinical decision-making was also recently published in CKJ. PMID:28396735

  3. Stability analysis of boundary layer flow and heat transfer over a permeable exponentially shrinking sheet in the presence of thermal radiation and partial slip

    NASA Astrophysics Data System (ADS)

    Adnan, N. S. M.; Arifin, N. M.

    2017-09-01

    In this paper, the steady boundary layer fluid flow with heat transfer over an exponentially shrinking sheet with thermal radiation, partial slip and suction is studied. The similarity transformation was applied to the governing partial differential equations to transform into a set of ordinary differential equations which are then solved numerically using bvp4c function in Matlab. It is reveal that dual solutions exist in our observations. A stability analysis is performed to determine which solution is linearly stable and physically realizable.

  4. Exponentially localized Wannier functions in periodic zero flux magnetic fields

    NASA Astrophysics Data System (ADS)

    De Nittis, G.; Lein, M.

    2011-11-01

    In this work, we investigate conditions which ensure the existence of an exponentially localized Wannier basis for a given periodic hamiltonian. We extend previous results [Panati, G., Ann. Henri Poincare 8, 995-1011 (2007), 10.1007/s00023-007-0326-8] to include periodic zero flux magnetic fields which is the setting also investigated by Kuchment [J. Phys. A: Math. Theor. 42, 025203 (2009), 10.1088/1751-8113/42/2/025203]. The new notion of magnetic symmetry plays a crucial rôle; to a large class of symmetries for a non-magnetic system, one can associate "magnetic" symmetries of the related magnetic system. Observing that the existence of an exponentially localized Wannier basis is equivalent to the triviality of the so-called Bloch bundle, a rank m hermitian vector bundle over the Brillouin zone, we prove that magnetic time-reversal symmetry is sufficient to ensure the triviality of the Bloch bundle in spatial dimension d = 1, 2, 3. For d = 4, an exponentially localized Wannier basis exists provided that the trace per unit volume of a suitable function of the Fermi projection vanishes. For d > 4 and d ⩽ 2m (stable rank regime) only the exponential localization of a subset of Wannier functions is shown; this improves part of the analysis of Kuchment [J. Phys. A: Math. Theor. 42, 025203 (2009), 10.1088/1751-8113/42/2/025203]. Finally, for d > 4 and d > 2m (unstable rank regime) we show that the mere analysis of Chern classes does not suffice in order to prove triviality and thus exponential localization.

  5. Hierarchy in a double braneworld

    SciTech Connect

    Guerrero, Rommel; Rodriguez, R. Omar; Melfo, Alejandra; Pantoja, Nelson

    2006-10-15

    We show that the hierarchy between the Planck and the weak scales can follow from the tendency of gravitons and fermions to localize at different edges of a thick double wall embedded in an AdS{sub 5} spacetime without reflection symmetry. This double wall is a stable BPS thick-wall solution with two subwalls located at its edges; fermions are coupled to the scalar field through Yukawa interactions, but the lack of reflection symmetry forces them to be localized in one of the subwalls. We show that the graviton zero-mode wave function is suppressed in the fermion edge by an exponential function of the distance between the subwalls, and that the massive modes decouple so that Newtonian gravity is recuperated.

  6. [Double responses].

    PubMed

    Motté, G; Dinanian, S; Sebag, C; Drieu, L; Slama, M

    1995-12-01

    Double response is a rare electrocardiographic phenomenon requiring two atrioventricular conduction pathways with very different electrophysiological properties. Double ventricular responses are the usual manifestation: an atrial depolarisation (spontaneous or provoked, anticipated or not) is followed by a first ventricular response dependent on an accessory pathway or a rapid nodal pathway and then a second response resulting from sufficiently delayed transmission through a nodal pathway for the ventricles to have recovered their excitability when the second wave of activation reaches them. A simple curiosity when isolated and occurring under unusual conditions, particularly during electrophysiological investigation of the Wolff-Parkinson-White syndrome, the double response may initiate symptomatic non-reentrant junctional tachycardia when associated with nodal duality and repeating from atria in sinus rhythm. The functional incapacity and resistance to antiarrhythmic therapy may require referral for ablation of the slow pathway.

  7. Magnetohydrodynamic stagnation-point flow and heat transfer over an exponentially stretching/shrinking sheet

    NASA Astrophysics Data System (ADS)

    Jafar, Khamisah; Nazar, Roslinda; Ishak, Anuar; Hamzah, Firdaus Mohamad

    2015-09-01

    This paper considers a numerical investigation on the steady laminar two-dimensional MHD stagnation-point flow and heat transfer of an incompressible viscous fluid impinging normal to an exponentially stretching/shrinking flat sheet in the presence of a non-uniform magnetic field applied in a direction normal to the flat sheet. The sheet surface temperature is assumed to also vary exponentially with the distance from the stagnation-point. The governing system of partial differential equations is first transformed into ordinary differential equations, and solved numerically using an implicit finite-difference scheme known as the Keller-box method. The effects of the stretching/shrinking parameter ɛ and the magnetic parameter on the flow field and heat transfer characteristics are discussed. It is found that the magnitude of the skin friction coefficient |f″(o ) | , and the local Nusselt number -θ'(0 ) increase with both the magnetic parameter M and the stretching/shrinking parameter ɛ. For the shrinking case, it is found that there is a minimum value ɛc of the shrinking parameter ɛ for which solution exists, and its value is dependent on the value of M, and dual solutions exist for some range of values of the shrinking parameter ɛ.

  8. On the use of the exponential window method in the space domain

    NASA Astrophysics Data System (ADS)

    Liu, Li

    Wave propagation in unbounded media is a topic widely studied in different science and engineering fields. Global and local absorbing boundary conditions combined with the finite element method or the finite difference method are the usual numerical treatments. In this dissertation, an alternative is investigated based on the dynamic stiffness and the exponential window method in the space-wave number domain. Applying the exponential window in the space-wave number domain is equivalent to introducing fictitious damping into the system. The Discrete Fourier Transform employed in the dynamic stiffness can be properly performed in a damped system. An open boundary in space is thus created. Since the equation is solved by the finite difference formula in the time domain, this approach is in the time-wave number domain, which provides a complement for the original dynamic stiffness method, which is in the frequency-wave number domain. The approach is tested through different elasto-dynamic models that cover one-, two- and three-dimensional problems. The results from the proposed approach are compared with those from either analytical solutions or the finite element method. The comparison demonstrates the effectiveness of the approach. The incident waves can be efficiently absorbed regardless of incident angles and frequency contents. The approach proposed in this dissertation can be widely applied to the dynamics of railways, dams, tunnels, building and machine foundations, layered soil and composite materials.

  9. Doubling Time for Nonexponential Families of Functions

    ERIC Educational Resources Information Center

    Gordon, Sheldon P.

    2010-01-01

    One special characteristic of any exponential growth or decay function f(t) = Ab[superscript t] is its unique doubling time or half-life, each of which depends only on the base "b". The half-life is used to characterize the rate of decay of any radioactive substance or the rate at which the level of a medication in the bloodstream decays as it is…

  10. Doubling Time for Nonexponential Families of Functions

    ERIC Educational Resources Information Center

    Gordon, Sheldon P.

    2010-01-01

    One special characteristic of any exponential growth or decay function f(t) = Ab[superscript t] is its unique doubling time or half-life, each of which depends only on the base "b". The half-life is used to characterize the rate of decay of any radioactive substance or the rate at which the level of a medication in the bloodstream decays as it is…

  11. Gabor transform in texture analysis

    NASA Astrophysics Data System (ADS)

    Chen, Chien-Chang; Chen, Chaur-Chin

    1994-10-01

    Gabor transform has recently been exploited to do texture analysis, including texture edge detection, texture segmentation/discrimination, and texture synthesis. For most of the applications using Gabor transform, people convolve the given texture image with a set of Gabor filters with some user specified parameters. Although the mathematical formulation of applications involve the Fourier transform, few have investigated mathematical properties of the relationship between Gabor filters and their Fourier transform. This paper mainly studies mathematical properties of real Gabor filters and their corresponding Fourier transform. The goal is to select a set of `interesting' Gabor filters, or say, a set of parameters for Gabor filters to do texture analysis. We demonstrate, by means of 3-D graphical displays, that a Gabor filter or its corresponding Fourier transform may have a single peak or double peaks according to different parameters. Experiments for texture discrimination are given to demonstrate the applications of Gabor transform.

  12. Exponential growth of bacteria: Constant multiplication through division

    NASA Astrophysics Data System (ADS)

    Hagen, Stephen J.

    2010-12-01

    The growth of a bacterial culture is one of the most familiar examples of exponential growth, with important consequences in biology and medicine. Bacterial growth involves more than just a rate constant. To sustain exponential growth, the cell must carefully coordinate the accumulation of mass, constant replication of the chromosome, and physical division. Hence, the growth rate is centrally important in any physical and chemical description of a bacterial cell. These aspects of bacterial growth can be described by empirical laws that suggest simple and intuitive models. Therefore, a quantitative discussion of bacterial growth could be a part of any undergraduate biophysics course. We present a general overview of some classic experimental studies and mathematical models of bacterial growth from a mostly physical perspective.

  13. Predicting Escherichia coli's chemotactic drift under exponential gradient

    NASA Astrophysics Data System (ADS)

    Samanta, Sibendu; Layek, Ritwik; Kar, Shantimoy; Raj, M. Kiran; Mukhopadhyay, Sudipta; Chakraborty, Suman

    2017-09-01

    Bacterial species are known to show chemotaxis, i.e., the directed motions in the presence of certain chemicals, whereas the motion is random in the absence of those chemicals. The bacteria modulate their run time to induce chemotactic drift towards the attractant chemicals and away from the repellent chemicals. However, the existing theoretical knowledge does not exhibit a proper match with experimental validation, and hence there is a need for developing alternate models and validating experimentally. In this paper a more robust theoretical model is proposed to investigate chemotactic drift of peritrichous Escherichia coli under an exponential nutrient gradient. An exponential gradient is used to understand the steady state behavior of drift because of the logarithmic functionality of the chemosensory receptors. Our theoretical estimations are validated through the experimentation and simulation results. Thus, the developed model successfully delineates the run time, run trajectory, and drift velocity as measured from the experiments.

  14. Exponentially fitted explicit Runge-Kutta-Nystrom methods

    NASA Astrophysics Data System (ADS)

    Franco, J. M.

    2004-05-01

    Exponentially fitted Runge-Kutta-Nystrom (EFRKN) methods for the numerical integration of second-order IVPs with oscillatory solutions are derived. These methods integrate exactly differential systems whose solutions can be expressed as linear combinations of the set of functions {exp(λt),exp(-λt)}, , or equivalently {sin(ωt),cos(ωt)} when λ=iω, . Explicit EFRKN methods with two and three stages and algebraic orders 3 and 4 are constructed. In addition, a 4(3) embedded pair of explicit EFRKN methods based on the FSAL technique is obtained, which permits to introduce an error and step length control with a small cost added. Some numerical experiments show the efficiency of our explicit EFRKN methods when they are compared with other exponential fitting type codes proposed in the scientific literature.

  15. On exponential convergence conditions of an extended projection neural network.

    PubMed

    Xia, Youshen; Ye, Dongyi

    2008-09-01

    Recently the extended projection neural network was proposed to solve constrained monotone variational inequality problems and a class of constrained nonmonotontic variational inequality problems. Its exponential convergence was developed under the positive definiteness condition of the Jacobian matrix of the nonlinear mapping. This note proposes new results on the exponential convergence of the output trajectory of the extended projection neural network under the weak conditions that the Jacobian matrix of the nonlinear mapping may be positive semidefinite or not. Therefore, new results further demonstrate that the extended projection neural network has a fast convergence rate when solving a class of constrained monotone variational inequality problems and nonmonotonic variational inequality problems. Illustrative examples show the significance of the obtained results.

  16. Exponential fitted Gauss, Radau and Lobatto methods of low order

    NASA Astrophysics Data System (ADS)

    Martín-Vaquero, J.; Vigo-Aguiar, J.

    2008-08-01

    Several exponential fitting Runge-Kutta methods of collocation type are derived as a generalization of the Gauss, Radau and Lobatto traditional methods of two steps. The new methods are capable of the exact integration (with only round-off errors) of differential equations whose solutions are linear combinations of an exponential and ordinary polynomials. Theorems of the truncation error reveal the good behavior of the new methods for stiff problems. Plots of their absolute stability regions that include the whole of the negative real axis are provided. A different procedure to find the parameter of the method is proposed. The variable step Radau method of two stages is derived. Finally, numerical examples underscore the efficiency of the proposed codes, especially when they are integrating stiff problems.

  17. Exponential time-dependent perturbation theory in rotationally inelastic scattering

    NASA Astrophysics Data System (ADS)

    Cross, R. J.

    1983-08-01

    An exponential form of time-dependent perturbation theory (the Magnus approximation) is developed for rotationally inelastic scattering. A phase-shift matrix is calculated as an integral in time over the anisotropic part of the potential. The trajectory used for this integral is specified by the diagonal part of the potential matrix and the arithmetic average of the initial and final velocities and the average orbital angular momentum. The exponential of the phase-shift matrix gives the scattering matrix and the various cross sections. A special representation is used where the orbital angular momentum is either treated classically or may be frozen out to yield the orbital sudden approximation. Calculations on Ar+N2 and Ar+TIF show that the theory generally gives very good agreement with accurate calculations, even where the orbital sudden approximation (coupled-states) results are seriously in error.

  18. The scaling of human mobility by taxis is exponential

    NASA Astrophysics Data System (ADS)

    Liang, Xiao; Zheng, Xudong; Lv, Weifeng; Zhu, Tongyu; Xu, Ke

    2012-03-01

    As a significant factor in urban planning, traffic forecasting and prediction of epidemics, modeling patterns of human mobility draws intensive attention from researchers for decades. Power-law distribution and its variations are observed from quite a few real-world human mobility datasets such as the movements of banking notes, trackings of cell phone users' locations and trajectories of vehicles. In this paper, we build models for 20 million trajectories with fine granularity collected from more than 10 thousand taxis in Beijing. In contrast to most models observed in human mobility data, the taxis' traveling displacements in urban areas tend to follow an exponential distribution instead of a power-law. Similarly, the elapsed time can also be well approximated by an exponential distribution. Worth mentioning, analysis of the interevent time indicates the bursty nature of human mobility, similar to many other human activities.

  19. Superballistic wavepacket spreading in double kicked rotors

    NASA Astrophysics Data System (ADS)

    Fang, Ping; Wang, Jiao

    2016-08-01

    We investigate possible ways in which a quantum wavepacket spreads. We show that in a general class of double kicked rotor system, a wavepacket may undergo superballistic spreading; i.e., its variance increases as the cubic of time. The conditions for the observed superballistic spreading and two related characteristic time scales are studied. Our results suggest that the symmetry of the studied model and whether it is a Kolmogorov-Arnold-Moser system are crucial to its wavepacket spreading behavior. Our study also sheds new light on the exponential wavepacket spreading phenomenon previously observed in the double kicked rotor system.

  20. Radiative Hydromagnetic Flow of Jeffrey Nanofluid by an Exponentially Stretching Sheet

    PubMed Central

    Hussain, Tariq; Shehzad, Sabir Ali; Hayat, Tasawar; Alsaedi, Ahmed; Al-Solamy, Falleh; Ramzan, Muhammad

    2014-01-01

    Two-dimensional hydromagnetic flow of an incompressible Jeffrey nanofluid over an exponentially stretching surface is examined in the present article. Heat and mass transfer analysis is performed in the presence of thermal radiation, viscous dissipation, and Brownian motion and thermophoresis effects. Mathematical modelling of considered flow problem is developed under boundary layer and Rosseland’s approximations. The governing nonlinear partial differential equations are converted into ordinary differential equations via transformations. Solution expressions of velocity, temperature and concentration are presented in the series forms. Impacts of physical parameters on the dimensionless temperature and concentration are shown and discussed. Skin-friction coefficients are analyzed numerically. A comparison in a limiting sense is provided to validate the present series solutions. PMID:25084096

  1. Plate/shell topological optimization subjected to linear buckling constraints by adopting composite exponential filtering function

    NASA Astrophysics Data System (ADS)

    Ye, Hong-Ling; Wang, Wei-Wei; Chen, Ning; Sui, Yun-Kang

    2016-08-01

    In this paper, a model of topology optimization with linear buckling constraints is established based on an independent and continuous mapping method to minimize the plate/shell structure weight. A composite exponential function (CEF) is selected as filtering functions for element weight, the element stiffness matrix and the element geometric stiffness matrix, which recognize the design variables, and to implement the changing process of design variables from "discrete" to "continuous" and back to "discrete". The buckling constraints are approximated as explicit formulations based on the Taylor expansion and the filtering function. The optimization model is transformed to dual programming and solved by the dual sequence quadratic programming algorithm. Finally, three numerical examples with power function and CEF as filter function are analyzed and discussed to demonstrate the feasibility and efficiency of the proposed method.

  2. Numerical and series solutions for stagnation-point flow of nanofluid over an exponentially stretching sheet.

    PubMed

    Mustafa, Meraj; Farooq, Muhammad A; Hayat, Tasawar; Alsaedi, Ahmed

    2013-01-01

    This investigation is concerned with the stagnation-point flow of nanofluid past an exponentially stretching sheet. The presence of Brownian motion and thermophoretic effects yields a coupled nonlinear boundary-value problem (BVP). Similarity transformations are invoked to reduce the partial differential equations into ordinary ones. Local similarity solutions are obtained by homotopy analysis method (HAM), which enables us to investigate the effects of parameters at a fixed location above the sheet. The numerical solutions are also derived using the built-in solver bvp4c of the software MATLAB. The results indicate that temperature and the thermal boundary layer thickness appreciably increase when the Brownian motion and thermophoresis effects are strengthened. Moreover the nanoparticles volume fraction is found to increase when the thermophoretic effect intensifies.

  3. A Spectral Lyapunov Function for Exponentially Stable LTV Systems

    NASA Technical Reports Server (NTRS)

    Zhu, J. Jim; Liu, Yong; Hang, Rui

    2010-01-01

    This paper presents the formulation of a Lyapunov function for an exponentially stable linear timevarying (LTV) system using a well-defined PD-spectrum and the associated PD-eigenvectors. It provides a bridge between the first and second methods of Lyapunov for stability assessment, and will find significant applications in the analysis and control law design for LTV systems and linearizable nonlinear time-varying systems.

  4. An exponential polynomial observer for synchronization of chaotic systems

    NASA Astrophysics Data System (ADS)

    Mata-Machuca, J. L.; Martínez-Guerra, R.; Aguilar-López, R.

    2010-12-01

    In this paper, we consider the synchronization problem via nonlinear observer design. A new exponential polynomial observer for a class of nonlinear oscillators is proposed, which is robust against output noises. A sufficient condition for synchronization is derived analytically with the help of Lyapunov stability theory. The proposed technique has been applied to synchronize chaotic systems (Rikitake and Rössler systems) by means of numerical simulation.

  5. Muscle contraction history: modified Hill versus an exponential decay model.

    PubMed

    Ettema, G J; Meijer, K

    2000-12-01

    In recent years, it has been recognised that improvements to classic models of muscle mechanical behaviour are often necessary for properly modelling coordinated multi-joint actions. In this respect, the purpose of the present study was to improve on modelling stretch-induced force enhancement and shortening-induced force depression of muscle contraction. For this purpose, two models were used: a modified Hill model and a model based loosely on mechano-chemistry of the cross-bridge cycle (exponential decay model). The models were compared with a classic Hill modeland experimental data. Parameter values were based, as much as possible, on experimental findings in the literature, and tested with new experiments on the gastrocnemius of the rat. Both models describe many features of slow-ramp movements well during short contractions (300-500 ms), but long-duration behaviour is described only partly. The exponential decay model does not incorporate a force-velocity curve. Therefore, its good performance indicates that the status ofthe classic force-velocity characteristic may have to be reconsidered. Like movement-induced force depression and enhancement, it seems a particular manifestation of time-dependent force behaviour of muscle, rather than a fundamental property of muscle (like the length-tension curve). It is argued that a combination of the exponential decay model (or other models based on the mechano-chemistry of contraction) and structurally based models may be fruitful in explaining this time-dependent contraction behaviour. Furthermore, not in the least because of its relative simplicity, the exponential decay model may prove more suitable for modelling multi-joint movements than the Hill model.

  6. Exponentiated Weibull regression for time-to-event data.

    PubMed

    Khan, Shahedul A

    2017-03-27

    The Weibull, log-logistic and log-normal distributions are extensively used to model time-to-event data. The Weibull family accommodates only monotone hazard rates, whereas the log-logistic and log-normal are widely used to model unimodal hazard functions. The increasing availability of lifetime data with a wide range of characteristics motivate us to develop more flexible models that accommodate both monotone and nonmonotone hazard functions. One such model is the exponentiated Weibull distribution which not only accommodates monotone hazard functions but also allows for unimodal and bathtub shape hazard rates. This distribution has demonstrated considerable potential in univariate analysis of time-to-event data. However, the primary focus of many studies is rather on understanding the relationship between the time to the occurrence of an event and one or more covariates. This leads to a consideration of regression models that can be formulated in different ways in survival analysis. One such strategy involves formulating models for the accelerated failure time family of distributions. The most commonly used distributions serving this purpose are the Weibull, log-logistic and log-normal distributions. In this study, we show that the exponentiated Weibull distribution is closed under the accelerated failure time family. We then formulate a regression model based on the exponentiated Weibull distribution, and develop large sample theory for statistical inference. We also describe a Bayesian approach for inference. Two comparative studies based on real and simulated data sets reveal that the exponentiated Weibull regression can be valuable in adequately describing different types of time-to-event data.

  7. Tachyonic matter cosmology with exponential and hyperbolic potentials

    NASA Astrophysics Data System (ADS)

    Pourhassan, B.; Naji, J.

    In this paper, we consider tachyonic matter in spatially flat Friedmann-Robertson-Walker (FRW) universe, and obtain behavior of some important cosmological parameters for two special cases of potentials. First, we assume the exponential potential and then consider hyperbolic cosine type potential. In both cases, we obtain behavior of the Hubble, deceleration and EoS parameters. Comparison with observational data suggest the model with hyperbolic cosine type scalar field potentials has good model to describe universe.

  8. Smith-Purcell oscillator in an exponential gain regime

    NASA Astrophysics Data System (ADS)

    Schachter, Levi; Ron, Amiram

    1989-04-01

    The threshold conditions of an oscillator based on the Smith-Purcell (SP) effect are analyzed in its exponential gain regime, and a self-consistent theory of a SP oscillator is formulated. A general expression for the dispersion relation of the oscillator is obtained in terms of the parameters of the electron beam, the grating, and the feedback loop. The threshold current for self-sustained oscillations is calculated to be less than 1 A for the radiation of 1-mm wavelength.

  9. Exponential Stability of Complex-Valued Memristive Recurrent Neural Networks.

    PubMed

    Wang, Huamin; Duan, Shukai; Huang, Tingwen; Wang, Lidan; Li, Chuandong

    2017-03-01

    In this brief, we establish a novel complex-valued memristive recurrent neural network (CVMRNN) to study its stability. As a generalization of real-valued memristive neural networks, CVMRNN can be separated into real and imaginary parts. By means of M -matrix and Lyapunov function, the existence, uniqueness, and exponential stability of the equilibrium point for CVMRNNs are investigated, and sufficient conditions are presented. Finally, the effectiveness of obtained results is illustrated by two numerical examples.

  10. Master-slave exponential synchronization of delayed complex-valued memristor-based neural networks via impulsive control.

    PubMed

    Li, Xiaofan; Fang, Jian-An; Li, Huiyuan

    2017-09-01

    This paper investigates master-slave exponential synchronization for a class of complex-valued memristor-based neural networks with time-varying delays via discontinuous impulsive control. Firstly, the master and slave complex-valued memristor-based neural networks with time-varying delays are translated to two real-valued memristor-based neural networks. Secondly, an impulsive control law is constructed and utilized to guarantee master-slave exponential synchronization of the neural networks. Thirdly, the master-slave synchronization problems are transformed into the stability problems of the master-slave error system. By employing linear matrix inequality (LMI) technique and constructing an appropriate Lyapunov-Krasovskii functional, some sufficient synchronization criteria are derived. Finally, a numerical simulation is provided to illustrate the effectiveness of the obtained theoretical results. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Femtosecond laser pulse driven melting in gold nanorod aqueous colloidal suspension: Identification of a transition from stretched to exponential kinetics

    SciTech Connect

    Li, Yuelin; Jiang, Zhang; Lin, Xiao -Min; Wen, Haidan; Walko, Donald A.; Deshmukh, Sanket A.; Subbaraman, Ram; Sankaranarayanan, Subramanian K. R. S.; Gray, Stephen K.; Ho, Phay

    2015-01-30

    Many potential industrial, medical, and environmental applications of metal nanorods rely on the physics and resultant kinetics and dynamics of the interaction of these particles with light. We report a surprising kinetics transition in the global melting of femtosecond laser-driven gold nanorod aqueous colloidal suspension. At low laser intensity, the melting exhibits a stretched exponential kinetics, which abruptly transforms into a compressed exponential kinetics when the laser intensity is raised. It is found the relative formation and reduction rate of intermediate shapes play a key role in the transition. Supported by both molecular dynamics simulations and a kinetic model, the behavior is traced back to the persistent heterogeneous nature of the shape dependence of the energy uptake, dissipation and melting of individual nanoparticles. These results could have significant implications for various applications such as water purification and electrolytes for energy storage that involve heat transport between metal nanorod ensembles and surrounding solvents.

  12. A Novel Compressed Sensing Method for Magnetic Resonance Imaging: Exponential Wavelet Iterative Shrinkage-Thresholding Algorithm with Random Shift

    PubMed Central

    Zhang, Yudong; Yang, Jiquan; Yang, Jianfei; Liu, Aijun; Sun, Ping

    2016-01-01

    Aim. It can help improve the hospital throughput to accelerate magnetic resonance imaging (MRI) scanning. Patients will benefit from less waiting time. Task. In the last decade, various rapid MRI techniques on the basis of compressed sensing (CS) were proposed. However, both computation time and reconstruction quality of traditional CS-MRI did not meet the requirement of clinical use. Method. In this study, a novel method was proposed with the name of exponential wavelet iterative shrinkage-thresholding algorithm with random shift (abbreviated as EWISTARS). It is composed of three successful components: (i) exponential wavelet transform, (ii) iterative shrinkage-thresholding algorithm, and (iii) random shift. Results. Experimental results validated that, compared to state-of-the-art approaches, EWISTARS obtained the least mean absolute error, the least mean-squared error, and the highest peak signal-to-noise ratio. Conclusion. EWISTARS is superior to state-of-the-art approaches. PMID:27066068

  13. Femtosecond laser pulse driven melting in gold nanorod aqueous colloidal suspension: Identification of a transition from stretched to exponential kinetics

    DOE PAGES

    Li, Yuelin; Jiang, Zhang; Lin, Xiao -Min; ...

    2015-01-30

    Many potential industrial, medical, and environmental applications of metal nanorods rely on the physics and resultant kinetics and dynamics of the interaction of these particles with light. We report a surprising kinetics transition in the global melting of femtosecond laser-driven gold nanorod aqueous colloidal suspension. At low laser intensity, the melting exhibits a stretched exponential kinetics, which abruptly transforms into a compressed exponential kinetics when the laser intensity is raised. It is found the relative formation and reduction rate of intermediate shapes play a key role in the transition. Supported by both molecular dynamics simulations and a kinetic model, themore » behavior is traced back to the persistent heterogeneous nature of the shape dependence of the energy uptake, dissipation and melting of individual nanoparticles. These results could have significant implications for various applications such as water purification and electrolytes for energy storage that involve heat transport between metal nanorod ensembles and surrounding solvents.« less

  14. The Exponential Function, the Human Race, and Scientists

    NASA Astrophysics Data System (ADS)

    Bartlett, Albert A.

    2004-05-01

    "The greatest shortcoming of the human race is our inability to understand the exponential function." This is the opening line of a talk I have given over 1500 times since 1969. In this context, the exponential function is used to give a quantitative description of steady growth of, for example, a population. As we all know, quantities that grow steadily, at even modest rates, quickly become impossibly large. Yet non-scientists in the business and government communities continue to fight for "sustainable growth" of the U.S. economy and population. What are scientists doing to increase public comprehension of the impossibility of "sustainable growth?" The main role of scientists seems to be to avoid calling attention to the impossibility of continued growth of populations and of rates of consumption of resources and, instead, to focus on minor aspects of the related problems. In so doing, we are complicit in making the problems worse. For scientists, this opening line should be revised to read: "The greatest shortcoming of scientists is our unwillingness to apply our knowledge of the exponential function to the great problems that are facing the human race."

  15. The Exponential Decay Law, Bell's Inequality, and Nonlinear Dynamics

    NASA Astrophysics Data System (ADS)

    McHarris, Wm. C.

    2002-10-01

    What do the exponential decay law and Bell's inequality have in common? And with nonlinear dynamics? Simply that they both are among the puzzles at the heart of quantum mechanics, puzzles which can have parallel explanations in terms of chaos or nonlinear dynamics. The statistical nature of the exponential decay law, which at first glance is incompatible with the quantum mechanical concept of indistinguishabe particles, can be mocked up by the extreme sensitivity of chaotic systems to initial conditions. In accord with Ockham's Razor, iteration of a simple unimodal (e.g., quadratic) map in its chaotic region and keeping track of the number of iterations required for a trajectory starting from a point chosen at random within a small interval to escape into another small small interval reproduces the observed exponential behavior. Similarly, Bell's inequality derived using classical mechanics (with an underlying assumption of classical statistics) places an upper limit on numbers derived from measurements on entangled states, whereas quantum mechanics implies that this upper limit no longer holds. Experiments have shown the inequality to be violated, upholding quantum mechanics. However, nonlinear dynamics, with its correlated statistics, can yield results overlapping with the quantum mechanical predictions. Whether or not the experiments rule out "local realism" is thus a moot point. Nonlinear determinism just might exist within quantum mechanics.

  16. A kernel representation for exponential splines with global tension

    NASA Astrophysics Data System (ADS)

    Barendt, Sven; Fischer, Bernd; Modersitzki, Jan

    2009-02-01

    Interpolation is a key ingredient in many imaging routines. In this note, we present a thorough evaluation of an interpolation method based on exponential splines in tension. They are based on so-called tension parameters, which allow for a tuning of their properties. As it turns out, these interpolants have very many nice features, which are, however, not born out in the literature. We intend to close this gap. We present for the first time an analytic representation of their kernel which enables one to come up with a space and frequency domain analysis. It is shown that the exponential splines in tension, as a function of the tension parameter, bridging the gap between linear and cubic B-Spline interpolation. For example, with a certain tension parameter, one is able to suppress ringing artefacts in the interpolant. On the other hand, the analysis in the frequency domain shows that one derives a superior signal reconstruction quality as known from the cubic B-Spline interpolation, which, however, suffers from ringing artifacts. With the ability to offer a trade-off between opposing features of interpolation methods we advocate the use of the exponential spline in tension from a practical point of view and use the new kernel representation to qualify the trade-off.

  17. Double Crater

    NASA Image and Video Library

    2012-03-23

    A double crater, called a crater doublet, is seen in the bottom right part of this image from NASA Dawn spacecraft of asteroid Vesta. This crater doublet was likely formed by the simultaneous impact of two fragments of a split projectile.

  18. Non-deformed singular and non-singular exponential-type potentials.

    PubMed

    Pe Na, J J; Ovando, G; Morales, J; García-Ravelo, J

    2017-08-18

    The canonical transformation method applied to the Schrödinger equation to transform it into a second-order differential equation of hypergeometric-type is presented. Starting from there, those exactly solvable multiparameter exponential-type (ME-T) potentials with hypergeometric wavefunctions that belong to the families of radial (singular) and one-dimensional (non-singular) potentials, are obtained. Furthermore, we show how the choice of the involved parameters leads, as particular cases, to different deformed or non-deformed potential models already used in the study of electronic properties of diatomic molecules. Also, the analysis of parameters lets us identify the couple of potential partners (singular/non-singular) that correspond to each choice of the parameters appearing in the ME-T potential. As a useful application of the proposal, the most important non-deformed exponential potential models are considered for which it can be viewed as a unified treatment with the following advantages: (1) It is not necessary to use a special method to solve the Schrödinger equation for a specific potential model because solution is obtained as particular case by the simple choice of the involved parameters; (2) The families of singular and non-singular potentials are straightforward identified; (3) The corresponding associated partners, between radial and one-dimensional non-deformed potentials, are found; (4) New potentials, as interesting alternatives for quantum applications, are obtained. In addition, from the conditions that parameters must meet to have physically acceptable solutions, we establish the requirements for the existence or not of singular/non-singular potential partners.

  19. Exponential processes in human auditory excitation and adaptation.

    PubMed

    Formby, C; Rutledge, J C; Sherlock, L P

    2002-02-01

    Peripheral auditory adaptation has been studied extensively in animal models, and multiple exponential components have been identified. This study explores the feasibility of estimating these component processes for human listeners with a peripheral model of adaptation. The processes were estimated from off-frequency masked detection data that probed temporal masking responses to a gated narrowband masker. The resulting response patterns reflected step-like onset and offset features with characteristically little evidence of confounding backward and forward masking. The model was implemented with linear combinations of exponential functions to represent the unadapted excitation response to gating the masker on and then off and the opposing effects of adaptation in each instance. The onset and offset of the temporal masking response were assumed to be approximately inverse operations and were modeled independently in this scheme. The unadapted excitation response at masker onset and the reversed excitation response at masker offset were each represented in the model by a single exponential function. The adaptation processes were modeled by three independent exponential functions, which were reversed at masker offset. Each adaptation component was subtractive and partially negated the unadapted excitation response to the dynamic masker. This scheme allowed for quantification of the response amplitude, action latency, and time constant for the unadapted excitation component and for each adaptation component. The results reveal that (1) the amplitudes of the unadapted excitation and reversed excitation components grow nonlinearly with masker level and mirror the 'compressive' input-output velocity response of the basilar membrane; (2) the time constants for the unadapted excitation and reversed excitation components are related inversely to masker intensity, which is compatible with neural synchrony increasing at masker onset (or offset) with increasing masker strength

  20. Exponentially and non-exponentially small splitting of separatrices for the pendulum with a fast meromorphic perturbation

    NASA Astrophysics Data System (ADS)

    Guardia, Marcel; Seara, Tere M.

    2012-05-01

    In this paper, we study the splitting of separatrices phenomenon which arises when one considers a Hamiltonian system of one degree of freedom with a fast periodic or quasiperiodic and meromorphic in the state variables perturbation. The obtained results are different from the previous ones in the literature, which mainly assume algebraic or trigonometric polynomial dependence on the state variables. As a model, we consider the pendulum equation with several meromorphic perturbations and we show the sensitivity of the size of the splitting on the width of the analyticity strip of the perturbation with respect to the state variables. We show that the size of the splitting is exponentially small if the strip of analyticity is wide enough. Furthermore, we see that the splitting grows as the width of the analyticity strip shrinks, even becoming non-exponentially small for very narrow strips. Our results prevent use of polynomial truncations of the meromorphic perturbation to compute the size of the splitting of separatrices.

  1. Double Layers in Astrophysics

    NASA Technical Reports Server (NTRS)

    Williams, Alton C. (Editor); Moorehead, Tauna W. (Editor)

    1987-01-01

    Topics addressed include: laboratory double layers; ion-acoustic double layers; pumping potential wells; ion phase-space vortices; weak double layers; electric fields and double layers in plasmas; auroral double layers; double layer formation in a plasma; beamed emission from gamma-ray burst source; double layers and extragalactic jets; and electric potential between plasma sheet clouds.

  2. Transformed Lymphoma.

    PubMed

    Anderson, Mary Ann; Blombery, Piers; Seymour, John F

    2016-12-01

    Transformed lymphoma is a complex syndrome that encompasses an array of different underlying low-grade lymphoproliferative conditions transforming into more aggressive disease as manifest by morphologic, clinical, and genetic features. Over the last decade, advances in chemoimmunotherapy have led to new options. Knowledge surrounding the genetic changes driving the process of transformation is leading to novel targeted therapies. This article focuses on the transformation of chronic lymphocytic leukemia and follicular lymphoma into diffuse large B-cell lymphoma.

  3. On new non-modal hydrodynamic stability modes and resulting non-exponential growth rates - a Lie symmetry approach

    NASA Astrophysics Data System (ADS)

    Oberlack, Martin; Nold, Andreas; Sanjon, Cedric Wilfried; Wang, Yongqi; Hau, Jan

    2016-11-01

    Classical hydrodynamic stability theory for laminar shear flows, no matter if considering long-term stability or transient growth, is based on the normal-mode ansatz, or, in other words, on an exponential function in space (stream-wise direction) and time. Recently, it became clear that the normal mode ansatz and the resulting Orr-Sommerfeld equation is based on essentially three fundamental symmetries of the linearized Euler and Navier-Stokes equations: translation in space and time and scaling of the dependent variable. Further, Kelvin-mode of linear shear flows seemed to be an exception in this context as it admits a fourth symmetry resulting in the classical Kelvin mode which is rather different from normal-mode. However, very recently it was discovered that most of the classical canonical shear flows such as linear shear, Couette, plane and round Poiseuille, Taylor-Couette, Lamb-Ossen vortex or asymptotic suction boundary layer admit more symmetries. This, in turn, led to new problem specific non-modal ansatz functions. In contrast to the exponential growth rate in time of the modal-ansatz, the new non-modal ansatz functions usually lead to an algebraic growth or decay rate, while for the asymptotic suction boundary layer a double-exponential growth or decay is observed.

  4. Double screening

    SciTech Connect

    Gratia, Pierre; Hu, Wayne; Joyce, Austin; Ribeiro, Raquel H.

    2016-06-15

    Attempts to modify gravity in the infrared typically require a screening mechanism to ensure consistency with local tests of gravity. These screening mechanisms fit into three broad classes; we investigate theories which are capable of exhibiting more than one type of screening. Specifically, we focus on a simple model which exhibits both Vainshtein and kinetic screening. We point out that due to the two characteristic length scales in the problem, the type of screening that dominates depends on the mass of the sourcing object, allowing for different phenomenology at different scales. We consider embedding this double screening phenomenology in a broader cosmological scenario and show that the simplest examples that exhibit double screening are radiatively stable.

  5. Plastid transformation in eggplant.

    PubMed

    Bansal, Kailash C; Singh, Ajay K

    2014-01-01

    Eggplant (Solanum melongena L.) is an important vegetable crop of tropical and temperate regions of the world. Here we describe a procedure for eggplant plastid transformation, which involves preparation of explants, biolistic delivery of plastid transformation vector into green stem segments, selection procedure, and identification of the transplastomic plants. Shoot buds appear from cut ends of the stem explants following 5-6 weeks of spectinomycin selection after bombardment with the plastid transformation vector containing aadA gene as selectable marker. Transplastomic lines are obtained after the regenerated shoots are subjected to several rounds of spectinomycin selection over a period of 9 weeks. Homoplasmic transplastomic lines are further confirmed by spectinomycin and streptomycin double selection. The transplastomic technology development in this plant species will open up exciting possibilities for improving crop performance, metabolic engineering, and the use of plants as factories for producing biopharmaceuticals.

  6. Exponential frequency spectrum and Lorentzian pulses in magnetized plasmas

    SciTech Connect

    Pace, D. C.; Shi, M.; Maggs, J. E.; Morales, G. J.; Carter, T. A.

    2008-12-15

    Two different experiments involving pressure gradients across the confinement magnetic field in a large plasma column are found to exhibit a broadband turbulence that displays an exponential frequency spectrum for frequencies below the ion cyclotron frequency. The exponential feature has been traced to the presence of solitary pulses having a Lorentzian temporal signature. These pulses arise from nonlinear interactions of drift-Alfven waves driven by the pressure gradients. In both experiments the width of the pulses is narrowly distributed resulting in exponential spectra with a single characteristic time scale. The temporal width of the pulses is measured to be a fraction of a period of the drift-Alfven waves. The experiments are performed in the Large Plasma Device (LAPD-U) [W. Gekelman et al., Rev. Sci. Instrum. 62, 2875 (1991)] operated by the Basic Plasma Science Facility at the University of California, Los Angeles. One experiment involves a controlled, pure electron temperature gradient associated with a microscopic (6 mm gradient length) hot electron temperature filament created by the injection a small electron beam embedded in the center of a large, cold magnetized plasma. The other experiment is a macroscopic (3.5 cm gradient length) limiter-edge experiment in which a density gradient is established by inserting a metallic plate at the edge of the nominal plasma column of the LAPD-U. The temperature filament experiment permits a detailed study of the transition from coherent to turbulent behavior and the concomitant change from classical to anomalous transport. In the limiter experiment the turbulence sampled is always fully developed. The similarity of the results in the two experiments strongly suggests a universal feature of pressure-gradient driven turbulence in magnetized plasmas that results in nondiffusive cross-field transport. This may explain previous observations in helical confinement devices, research tokamaks, and arc plasmas.

  7. Exponential complexity and ontological theories of quantum mechanics

    SciTech Connect

    Montina, A.

    2008-02-15

    Ontological theories of quantum mechanics describe a single system by means of well-defined classical variables and attribute the quantum uncertainties to our ignorance about the underlying reality represented by these variables. We consider the general class of ontological theories describing a quantum system by a set of variables with Markovian (either deterministic or stochastic) evolution. We provide proof that the number of continuous variables cannot be smaller than 2N-2, N being the Hilbert-space dimension. Thus, any ontological Markovian theory of quantum mechanics requires a number of variables which grows exponentially with the physical size. This result is relevant also in the framework of quantum Monte Carlo methods.

  8. Stretched exponential survival statistics for microorganisms in radiation field

    NASA Astrophysics Data System (ADS)

    Plonka, Andrzej; Bogus, Wlodzimierz

    1999-11-01

    The so-called concave or tailed survival curves are reported both for multi and single species bacterial populations. Taking as an example Bacillus pumilus, frequently encountered in decontamination studies, it is shown that the tailed survival curves are adequately described by stretched (0< α<1) exponential SF=exp[-( D/ D0) α], where SF denotes the fraction of species surviving the irradiation dose D, D0 is the effective dose, and α is the dispersion parameter interpreted phenomenologically in terms of radiation sensivity distribution for single species population under the given experimental conditions.

  9. Curve fitting of aeroelastic transient response data with exponential functions

    NASA Technical Reports Server (NTRS)

    Bennett, R. M.; Desmarais, R. N.

    1976-01-01

    The extraction of frequency, damping, amplitude, and phase information from unforced transient response data is considered. These quantities are obtained from the parameters determined by fitting the digitized time-history data in a least-squares sense with complex exponential functions. The highlights of the method are described, and the results of several test cases are presented. The effects of noise are considered both by using analytical examples with random noise and by estimating the standard deviation of the parameters from maximum-likelihood theory.

  10. Exponential integrators for the incompressible Navier-Stokes equations.

    SciTech Connect

    Newman, Christopher K.

    2004-07-01

    We provide an algorithm and analysis of a high order projection scheme for time integration of the incompressible Navier-Stokes equations (NSE). The method is based on a projection onto the subspace of divergence-free (incompressible) functions interleaved with a Krylov-based exponential time integration (KBEI). These time integration methods provide a high order accurate, stable approach with many of the advantages of explicit methods, and can reduce the computational resources over conventional methods. The method is scalable in the sense that the computational costs grow linearly with problem size. Exponential integrators, used typically to solve systems of ODEs, utilize matrix vector products of the exponential of the Jacobian on a vector. For large systems, this product can be approximated efficiently by Krylov subspace methods. However, in contrast to explicit methods, KBEIs are not restricted by the time step. While implicit methods require a solution of a linear system with the Jacobian, KBEIs only require matrix vector products of the Jacobian. Furthermore, these methods are based on linearization, so there is no non-linear system solve at each time step. Differential-algebraic equations (DAEs) are ordinary differential equations (ODEs) subject to algebraic constraints. The discretized NSE constitute a system of DAEs, where the incompressibility condition is the algebraic constraint. Exponential integrators can be extended to DAEs with linear constraints imposed via a projection onto the constraint manifold. This results in a projected ODE that is integrated by a KBEI. In this approach, the Krylov subspace satisfies the constraint, hence the solution at the advanced time step automatically satisfies the constraint as well. For the NSE, the projection onto the constraint is typically achieved by a projection induced by the L{sup 2} inner product. We examine this L{sup 2} projection and an H{sup 1} projection induced by the H{sup 1} semi-inner product. The H

  11. Solving Point-Reactor Kinetics Equations Using Exponential Moment Methods

    DTIC Science & Technology

    2013-03-21

    equations of the following form: ( ) ( ) ( ) ( ) ( )i i i dn t t n t c t S t dt               (2) ( ) ( ) ( )i ii i dc t c t n...presented in the function. Exponential moment functions are orderless; that is, the value of the function is invariant under permutations of its...turned into an integral equation by   ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) i i i i i i i i i i i i dn

  12. Incomplete exponential sums and Diffie-Hellman triples

    NASA Astrophysics Data System (ADS)

    Banks, William D.; Friedlander, John B.; Konyagin, Sergei V.; Shparlinski, Igor E.

    2006-03-01

    Let p be a prime and vartheta an integer of order t in the multiplicative group modulo p. In this paper, we continue the study of the distribution of Diffie-Hellman triples (vartheta(x,) vartheta(y,) vartheta(xy) ) by considering the closely related problem of estimating exponential sums formed from linear combinations of the entries in such triples. We show that the techniques developed earlier for complete sums can be combined, modified and developed further to treat incomplete sums as well. Our bounds imply uniformity of distribution results for Diffie-Hellman triples as the pair (x,y) varies over small boxes.

  13. Exponential Decay of Covariances for the Supercritical Membrane Model

    NASA Astrophysics Data System (ADS)

    Bolthausen, Erwin; Cipriani, Alessandra; Kurt, Noemi

    2017-08-01

    We consider the membrane model, that is the centered Gaussian field on {\\mathbb{Z}^d} whose covariance matrix is given by the inverse of the discrete Bilaplacian. We impose a {δ}-pinning condition, giving a reward of strength {\\varepsilon} for the field to be 0 at any site of the lattice. In this paper we prove that in dimensions {d≥ 5} covariances of the pinned field decay at least exponentially, as opposed to the field without pinning, where the decay is polynomial. The proof is based on estimates for certain discrete weighted norms, a percolation argument and on a Bernoulli domination result.

  14. Exponentially accurate approximations to piece-wise smooth periodic functions

    NASA Technical Reports Server (NTRS)

    Greer, James; Banerjee, Saheb

    1995-01-01

    A family of simple, periodic basis functions with 'built-in' discontinuities are introduced, and their properties are analyzed and discussed. Some of their potential usefulness is illustrated in conjunction with the Fourier series representations of functions with discontinuities. In particular, it is demonstrated how they can be used to construct a sequence of approximations which converges exponentially in the maximum norm to a piece-wise smooth function. The theory is illustrated with several examples and the results are discussed in the context of other sequences of functions which can be used to approximate discontinuous functions.

  15. A By-Level Analysis of Multiplicative Exponential Linear Logic

    NASA Astrophysics Data System (ADS)

    Gaboardi, Marco; Roversi, Luca; Vercelli, Luca

    We study the relations between Multiplicative Exponential Linear Logic ( mELL) and Baillot-Mazza Linear Logic by Levels ( mL 3). We design a decoration-based translation between propositional mELL and propositional mL 3. The translation preserves the cut elimination. Moreover, we show that there is a proof net {Pi} of second order mELL that cannot have a representative {Pi'} in second order mL 3 under any decoration. This suggests that levels can be an analytical tool in understanding the complexity of second order quantifier.

  16. Exponential Methods for the Time Integration of Schroedinger Equation

    SciTech Connect

    Cano, B.; Gonzalez-Pachon, A.

    2010-09-30

    We consider exponential methods of second order in time in order to integrate the cubic nonlinear Schroedinger equation. We are interested in taking profit of the special structure of this equation. Therefore, we look at symmetry, symplecticity and approximation of invariants of the proposed methods. That will allow to integrate till long times with reasonable accuracy. Computational efficiency is also our aim. Therefore, we make numerical computations in order to compare the methods considered and so as to conclude that explicit Lawson schemes projected on the norm of the solution are an efficient tool to integrate this equation.

  17. A Mixed Exponential Time Series Model. NMEARMA(p,q).

    DTIC Science & Technology

    1980-03-01

    AD-AO85 316 NAVAL POSTGRADUATE SCHOOL MONTEREY CA F/G 12/1 A MIXED EXPONENTIAL TIME SERIES MODEL. NMEARMA(P,Q).(U MAR GO A .J LAWRANCE , P A LEWIS...This report was prepared by: A. J. Lawrance University of Birmingham Birmingham, England Reviewed by: Released by- Michael G. Sover’ign, Chirman...MODEL, NMEARMA(p,q) by A. J. Lawrance P. A. W. Lewis University of Birmingham Naval Postgraduate School Birmingham, England Monterey, California, USA

  18. Asymptotic Structure of Constrained Exponential Random Graph Models

    NASA Astrophysics Data System (ADS)

    Zhu, Lingjiong

    2017-03-01

    In this paper, we study exponential random graph models subject to certain constraints. We obtain some general results about the asymptotic structure of the model. We show that there exists non-trivial regions in the phase plane where the asymptotic structure is uniform and there also exists non-trivial regions in the phase plane where the asymptotic structure is non-uniform. We will get more refined results for the star model and in particular the two-star model for which a sharp transition from uniform to non-uniform structure, a stationary point and phase transitions will be obtained.

  19. A conditionally exponential decay approach to scaling in finance

    NASA Astrophysics Data System (ADS)

    Weron, Rafal; Weron, Karina; Weron, Aleksander

    We demonstrate how the basic ideas of the fractal and the heterogeneous market hypotheses lead to a rigorous mathematical model, which can be used to solve the problem of characterizing the distribution of price changes corresponding to the empirical scaling law of volatility for high-frequency data from the foreign exchange market. For this purpose, we adopt the conditionally exponential decay model, which describes asymptotic behaviour of general complex systems. We also discuss the overall rationale for why one might expect such scaling laws to hold for financial data.

  20. On the function inverse to the exponential integral function

    NASA Astrophysics Data System (ADS)

    Pecina, P.

    1986-01-01

    The paper deals briefly with one integral of the basic equations of meteoric physics which includes the exponential integral function Ei(x). It is further shown that the approximation of the function inverse to Ei(x), Ei-1(x), is also required. The construction of this function, using series expansion by means of Chebyshev polynomials, is described. Computer programs, written in Fortran IV G, which serve to compute the values of Ei(x) and Ei-1(x), accurate to 13 decimal figures, are included.

  1. Stretched Exponential Relaxation of Glasses at Low Temperature.

    PubMed

    Yu, Yingtian; Wang, Mengyi; Zhang, Dawei; Wang, Bu; Sant, Gaurav; Bauchy, Mathieu

    2015-10-16

    The question of whether glass continues to relax at low temperature is of fundamental and practical interest. Here, we report a novel atomistic simulation method allowing us to directly access the long-term dynamics of glass relaxation at room temperature. We find that the potential energy relaxation follows a stretched exponential decay, with a stretching exponent β=3/5, as predicted by Phillips's diffusion-trap model. Interestingly, volume relaxation is also found. However, it is not correlated to the energy relaxation, but it is rather a manifestation of the mixed alkali effect.

  2. Hermite-Padé approximation of exponential functions

    NASA Astrophysics Data System (ADS)

    Astafyeva, A. V.; Starovoitov, A. P.

    2016-06-01

    The paper is concerned with diagonal Hermite-Padé polynomials of the first kind for the system of exponentials \\{eλ_jz\\}j=0^k with arbitrary distinct complex parameters \\{λ_k\\}j=0^k. An asymptotic formula for the remainder term is established and the location of the zeros is described. For real parameters the asymptotics are found and the extremal properties are described. The theorems obtained supplement the well-known results due to Borwein, Wielonsky, Saff, Varga and Stahl. Bibliography: 43 titles.

  3. Neural pulse frequency modulation of an exponentially correlated Gaussian process

    NASA Technical Reports Server (NTRS)

    Hutchinson, C. E.; Chon, Y.-T.

    1976-01-01

    The effect of NPFM (Neural Pulse Frequency Modulation) on a stationary Gaussian input, namely an exponentially correlated Gaussian input, is investigated with special emphasis on the determination of the average number of pulses in unit time, known also as the average frequency of pulse occurrence. For some classes of stationary input processes where the formulation of the appropriate multidimensional Markov diffusion model of the input-plus-NPFM system is possible, the average impulse frequency may be obtained by a generalization of the approach adopted. The results are approximate and numerical, but are in close agreement with Monte Carlo computer simulation results.

  4. Dual solutions of radiative MHD nanofluid flow over an exponentially stretching sheet with heat generation/absorption

    NASA Astrophysics Data System (ADS)

    Naramgari, Sandeep; Sulochana, C.

    2016-01-01

    In this study, we analyzed the heat and mass transfer in thermophoretic radiative hydromagnetic nanofluid flow over an exponentially stretching porous sheet embedded in porous medium with internal heat generation/absorption, viscous dissipation and suction/injection effects. The governing partial differential equations of the flow are converted into nonlinear coupled ordinary differential equations by using similarity transformation. Runge-Kutta-based shooting technique is employed to yield the numerical solutions for the model. The effect of non-dimensional parameters on velocity, temperature and concentration profiles are discussed and presented through graphs. The physical quantities of interest local skin friction coefficient, Nusselt and Sherwood numbers are calculated and presented through tables.

  5. Truncated γ-exponential models for tidal stellar systems

    NASA Astrophysics Data System (ADS)

    Gomez-Leyton, Y. J.; Velazquez, L.

    2016-05-01

    We introduce a parametric family of models to characterize the properties of astrophysical systems in a quasi-stationary evolution under the incidence evaporation. We start from an one-particle distribution fγ (q, p|β,ɛs) that considers an appropriate deformation of Maxwell-Boltzmann form with inverse temperature β, in particular, a power-law truncation at the scape energy ɛs with exponent γ > 0. This deformation is implemented using a generalized γ-exponential function obtained from the fractional integration of ordinary exponential. As shown in this work, this proposal generalizes models of tidal stellar systems that predict particles distributions with isothermal cores and polytropic haloes, e.g.: Michie-King models. We perform the analysis of thermodynamic features of these models and their associated distribution profiles. A nontrivial consequence of this study is that profiles with isothermal cores and polytropic haloes are only obtained for low energies whenever deformation parameter γ < γc ≃ 2.13. This study is a first approximation to characterize a self- gravitating system, so we consider equal to all the particles that constitute the system.

  6. CONSISTENCY UNDER SAMPLING OF EXPONENTIAL RANDOM GRAPH MODELS.

    PubMed

    Shalizi, Cosma Rohilla; Rinaldo, Alessandro

    2013-04-01

    The growing availability of network data and of scientific interest in distributed systems has led to the rapid development of statistical models of network structure. Typically, however, these are models for the entire network, while the data consists only of a sampled sub-network. Parameters for the whole network, which is what is of interest, are estimated by applying the model to the sub-network. This assumes that the model is consistent under sampling, or, in terms of the theory of stochastic processes, that it defines a projective family. Focusing on the popular class of exponential random graph models (ERGMs), we show that this apparently trivial condition is in fact violated by many popular and scientifically appealing models, and that satisfying it drastically limits ERGM's expressive power. These results are actually special cases of more general results about exponential families of dependent random variables, which we also prove. Using such results, we offer easily checked conditions for the consistency of maximum likelihood estimation in ERGMs, and discuss some possible constructive responses.

  7. Hyperbolic neighborhoods as organizers of finite-time exponential stretching

    NASA Astrophysics Data System (ADS)

    Balasuriya, Sanjeeva; Ouellette, Nicholas

    2016-11-01

    Hyperbolic points and their unsteady generalization, hyperbolic trajectories, drive the exponential stretching that is the hallmark of nonlinear and chaotic flow. Typical experimental and observational velocity data is unsteady and available only over a finite time interval, and in such situations hyperbolic trajectories will move around in the flow, and may lose their hyperbolicity at times. Here we introduce a way to determine their region of influence, which we term a hyperbolic neighborhood, which marks fluid elements whose dynamics are instantaneously dominated by the hyperbolic trajectory. We establish, using both theoretical arguments and numerical verification from model and experimental data, that the hyperbolic neighborhoods profoundly impact Lagrangian stretching experienced by fluid elements. In particular, we show that fluid elements traversing a flow experience exponential boosts in stretching while within these time-varying regions, that greater residence time within hyperbolic neighborhoods is directly correlated to larger Finite-Time Lyapunov Exponent (FTLE) values, and that FTLE diagnostics are reliable only when the hyperbolic neighborhoods have a geometrical structure which is regular in a specific sense. Future Fellowship Grant FT130100484 from the Australian Research Council (SB), and a Terman Faculty Fellowship from Stanford University (NO).

  8. Freddi: Fast Rise Exponential Decay accretion Disk model Implementation

    NASA Astrophysics Data System (ADS)

    Malanchev, K. L.; Lipunova, G. V.

    2016-10-01

    Freddi (Fast Rise Exponential Decay: accretion Disk model Implementation) solves 1-D evolution equations of the Shakura-Sunyaev accretion disk. It simulates fast rise exponential decay (FRED) light curves of low mass X-ray binaries (LMXBs). The basic equation of the viscous evolution relates the surface density and viscous stresses and is of diffusion type; evolution of the accretion rate can be found on solving the equation. The distribution of viscous stresses defines the emission from the source. The standard model for the accretion disk is implied; the inner boundary of the disk is at the ISCO or can be explicitely set. The boundary conditions in the disk are the zero stress at the inner boundary and the zero accretion rate at the outer boundary. The conditions are suitable during the outbursts in X-ray binary transients with black holes. In a binary system, the accretion disk is radially confined. In Freddi, the outer radius of the disk can be set explicitely or calculated as the position of the tidal truncation radius.

  9. Arima model and exponential smoothing method: A comparison

    NASA Astrophysics Data System (ADS)

    Wan Ahmad, Wan Kamarul Ariffin; Ahmad, Sabri

    2013-04-01

    This study shows the comparison between Autoregressive Moving Average (ARIMA) model and Exponential Smoothing Method in making a prediction. The comparison is focused on the ability of both methods in making the forecasts with the different number of data sources and the different length of forecasting period. For this purpose, the data from The Price of Crude Palm Oil (RM/tonne), Exchange Rates of Ringgit Malaysia (RM) in comparison to Great Britain Pound (GBP) and also The Price of SMR 20 Rubber Type (cents/kg) with three different time series are used in the comparison process. Then, forecasting accuracy of each model is measured by examinethe prediction error that producedby using Mean Squared Error (MSE), Mean Absolute Percentage Error (MAPE), and Mean Absolute deviation (MAD). The study shows that the ARIMA model can produce a better prediction for the long-term forecasting with limited data sources, butcannot produce a better prediction for time series with a narrow range of one point to another as in the time series for Exchange Rates. On the contrary, Exponential Smoothing Method can produce a better forecasting for Exchange Rates that has a narrow range of one point to another for its time series, while itcannot produce a better prediction for a longer forecasting period.

  10. Data assimilation on the exponentially accurate slow manifold.

    PubMed

    Cotter, Colin

    2013-05-28

    I describe an approach to data assimilation making use of an explicit map that defines a coordinate system on the slow manifold in the semi-geostrophic scaling in Lagrangian coordinates, and apply the approach to a simple toy system that has previously been proposed as a low-dimensional model for the semi-geostrophic scaling. The method can be extended to Lagrangian particle methods such as Hamiltonian particle-mesh and smooth-particle hydrodynamics applied to the rotating shallow-water equations, and many of the properties will remain for more general Eulerian methods. Making use of Hamiltonian normal-form theory, it has previously been shown that, if initial conditions for the system are chosen as image points of the map, then the fast components of the system have exponentially small magnitude for exponentially long times as ε→0, and this property is preserved if one uses a symplectic integrator for the numerical time stepping. The map may then be used to parametrize initial conditions near the slow manifold, allowing data assimilation to be performed without introducing any fast degrees of motion (more generally, the precise amount of fast motion can be selected).

  11. Exponentially more precise quantum simulation of fermions in second quantization

    NASA Astrophysics Data System (ADS)

    Babbush, Ryan; Berry, Dominic W.; Kivlichan, Ian D.; Wei, Annie Y.; Love, Peter J.; Aspuru-Guzik, Alán

    2016-03-01

    We introduce novel algorithms for the quantum simulation of fermionic systems which are dramatically more efficient than those based on the Lie-Trotter-Suzuki decomposition. We present the first application of a general technique for simulating Hamiltonian evolution using a truncated Taylor series to obtain logarithmic scaling with the inverse of the desired precision. The key difficulty in applying algorithms for general sparse Hamiltonian simulation to fermionic simulation is that a query, corresponding to computation of an entry of the Hamiltonian, is costly to compute. This means that the gate complexity would be much higher than quantified by the query complexity. We solve this problem with a novel quantum algorithm for on-the-fly computation of integrals that is exponentially faster than classical sampling. While the approaches presented here are readily applicable to a wide class of fermionic models, we focus on quantum chemistry simulation in second quantization, perhaps the most studied application of Hamiltonian simulation. Our central result is an algorithm for simulating an N spin-orbital system that requires \\tilde{{ O }}({N}5t) gates. This approach is exponentially faster in the inverse precision and at least cubically faster in N than all previous approaches to chemistry simulation in the literature.

  12. Dealing with the exponential wall in electronic structure calculations

    NASA Astrophysics Data System (ADS)

    Fulde, Peter; Stoll, Hermann

    2017-05-01

    An alternative to the density functional theory is the use of wavefunction based electronic structure calculations for solids. In order to perform them, the Exponential Wall (EW) problem has to be resolved. It is caused by an exponential increase of the number of configurations with increasing electron number N. There are different routes one may follow. One is to characterize a many-electron wavefunction by a vector in Liouville space with a cumulant metric rather than in Hilbert space. This removes the EW problem. Another is to model the solid by an impurity or fragment embedded in a bath which is treated at a much lower level than the former. This is the case in the Density Matrix Embedding Theory (DMET) or the Density Embedding Theory (DET). The latter two are closely related to a Schmidt decomposition of a system and to the determination of the associated entanglement. We show here the connection between the two approaches. It turns out that the DMET (or DET) has an identical active space as a previously used Local Ansatz, based on a projection and partitioning approach. Yet, the EW problem is resolved differently in the two cases. By studying a H10 ring, these differences are analyzed with the help of the method of increments.

  13. Properties of branching exponential flights in bounded domains

    NASA Astrophysics Data System (ADS)

    Zoia, A.; Dumonteil, E.; Mazzolo, A.

    2012-11-01

    In a series of recent works, important results have been reported concerning the statistical properties of exponential flights evolving in bounded domains, a widely adopted model for finite-speed transport phenomena (Blanco S. and Fournier R., Europhys. Lett., 61 (2003) 168; Mazzolo A., Europhys. Lett., 68 (2004) 350; Bénichou O. et al., Europhys. Lett., 70 (2005) 42). Motivated by physical and biological systems where random spatial displacements are coupled with Galton-Watson birth-death mechanisms, such as neutron multiplication, diffusion of reproducing bacteria or spread of epidemics, in this letter we extend those results in two directions, via a Feynman-Kac formalism. First, we characterize the occupation statistics of exponential flights in the presence of absorption and branching, and give explicit moment formulas for the total length travelled by the walker and the number of performed collisions in a given domain. Then, we show that the survival and escape probability can be derived as well by resorting to a similar approach.

  14. A stochastic evolutionary model generating a mixture of exponential distributions

    NASA Astrophysics Data System (ADS)

    Fenner, Trevor; Levene, Mark; Loizou, George

    2016-02-01

    Recent interest in human dynamics has stimulated the investigation of the stochastic processes that explain human behaviour in various contexts, such as mobile phone networks and social media. In this paper, we extend the stochastic urn-based model proposed in [T. Fenner, M. Levene, G. Loizou, J. Stat. Mech. 2015, P08015 (2015)] so that it can generate mixture models, in particular, a mixture of exponential distributions. The model is designed to capture the dynamics of survival analysis, traditionally employed in clinical trials, reliability analysis in engineering, and more recently in the analysis of large data sets recording human dynamics. The mixture modelling approach, which is relatively simple and well understood, is very effective in capturing heterogeneity in data. We provide empirical evidence for the validity of the model, using a data set of popular search engine queries collected over a period of 114 months. We show that the survival function of these queries is closely matched by the exponential mixture solution for our model.

  15. Improved technique for one-way transformation of information

    DOEpatents

    Cooper, J.A.

    1987-05-11

    Method and apparatus are provided for one-way transformation of data according to multiplication and/or exponentiation modulo a prime number. An implementation of the invention permits the one way residue transformation, useful in encryption and similar applications, to be implemented by n-bit computers substantially with no increase in difficulty or complexity over a natural transformation thereby, using a modulus which is a power of two. 9 figs.

  16. Facilitating Understanding of a Catch-22 Concept: Teaching Exponential Change with Logo.

    ERIC Educational Resources Information Center

    Weller, Herman G.; Johnson, Vivian

    1992-01-01

    Describes a unit for teaching exponential change in a noncalculus physics course by having students write recursive procedures in LOGO to graphically represent linear and exponential change. Summarizes the experience of implementing the unit in a segment on radioactive decay. Modifications to the unit are suggested for teaching exponential change…

  17. Facilitating Understanding of a Catch-22 Concept: Teaching Exponential Change with Logo.

    ERIC Educational Resources Information Center

    Weller, Herman G.; Johnson, Vivian

    1992-01-01

    Describes a unit for teaching exponential change in a noncalculus physics course by having students write recursive procedures in LOGO to graphically represent linear and exponential change. Summarizes the experience of implementing the unit in a segment on radioactive decay. Modifications to the unit are suggested for teaching exponential change…

  18. Fourier Transformation

    NASA Astrophysics Data System (ADS)

    Scherer, Philipp O. J.

    Fourier transformation is a very important tool for signal analysis but also helpful to simplify the solution of differential equations or the calculation of convolution integrals. An important numerical method is the discrete Fourier transformation which can be used for trigonometric interpolation and also as a numerical approximation to the continuous Fourier integral. It can be realized efficiently by Goertzel's algorithm or the family of fast Fourier transformation methods. For real valued even functions the computationally simpler discrete cosine transformation can be applied. Several computer experiments demonstrate the principles of trigonometric interpolation and nonlinear filtering.

  19. Double metric, generalized metric, and α' -deformed double field theory

    NASA Astrophysics Data System (ADS)

    Hohm, Olaf; Zwiebach, Barton

    2016-03-01

    We relate the unconstrained "double metric" of the "α' -geometry" formulation of double field theory to the constrained generalized metric encoding the spacetime metric and b -field. This is achieved by integrating out auxiliary field components of the double metric in an iterative procedure that induces an infinite number of higher-derivative corrections. As an application, we prove that, to first order in α' and to all orders in fields, the deformed gauge transformations are Green-Schwarz-deformed diffeomorphisms. We also prove that to first order in α' the spacetime action encodes precisely the Green-Schwarz deformation with Chern-Simons forms based on the torsionless gravitational connection. This seems to be in tension with suggestions in the literature that T-duality requires a torsionful connection, but we explain that these assertions are ambiguous since actions that use different connections are related by field redefinitions.

  20. On the interaction of deep water waves and exponential shear currents

    NASA Astrophysics Data System (ADS)

    Cheng, Jun; Cang, Jie; Liao, Shi-Jun

    2009-05-01

    A train of periodic deep-water waves propagating on a steady shear current with a vertical distribution of vorticity is investigated by an analytic method, namely the homotopy analysis method (HAM). The magnitude of the vorticity varies exponentially with the magnitude of the stream function, while remaining constant on a particular streamline. The so-called Dubreil-Jacotin transformation is used to transfer the original exponentially nonlinear boundary-value problem in an unknown domain into an algebraically nonlinear boundary-value problem in a known domain. Convergent series solutions are obtained not only for small amplitude water waves on a weak current but also for large amplitude waves on a strong current. The nonlinear wave-current interaction is studied in detail. It is found that an aiding shear current tends to enlarge the wave phase speed, sharpen the wave crest, but shorten the maximum wave height, while an opposing shear current has the opposite effect. Besides, the amplitude of waves and fluid velocity decay over the depth more quickly on an aiding shear current but more slowly on an opposing shear current than that of waves on still water. Furthermore, it is found that Stokes criteria of wave breaking is still valid for waves on a shear current: a train of propagating waves on a shear current breaks as the fiuid velocity at crest equals the wave phase speed. Especially, it is found that the highest waves on an opposing shear current are even higher and steeper than that of waves on still water. Mathematically, this analytic method is rather general in principle and can be employed to solve many types of nonlinear partial differential equations with variable coefficients in science, finance and engineering.

  1. Absolute exponential stability of recurrent neural networks with generalized activation function.

    PubMed

    Xu, Jun; Cao, Yong-Yan; Sun, Youxian; Tang, Jinshan

    2008-06-01

    In this paper, the recurrent neural networks (RNNs) with a generalized activation function class is proposed. In this proposed model, every component of the neuron's activation function belongs to a convex hull which is bounded by two odd symmetric piecewise linear functions that are convex or concave over the real space. All of the convex hulls are composed of generalized activation function classes. The novel activation function class is not only with a more flexible and more specific description of the activation functions than other function classes but it also generalizes some traditional activation function classes. The absolute exponential stability (AEST) of the RNN with a generalized activation function class is studied through three steps. The first step is to demonstrate the global exponential stability (GES) of the equilibrium point of original RNN with a generalized activation function being equivalent to that of RNN under all vertex functions of convex hull. The second step transforms the RNN under every vertex activation function into neural networks under an array of saturated linear activation functions. Because the GES of the equilibrium point of three systems are equivalent, the next stability analysis focuses on the GES of the equilibrium point of RNN system under an array of saturated linear activation functions. The last step is to study both the existence of equilibrium point and the GES of the RNN under saturated linear activation functions using the theory of M-matrix. In the end, a two-neuron RNN with a generalized activation function is constructed to show the effectiveness of our results.

  2. A relative entropy method to measure non-exponential random data

    NASA Astrophysics Data System (ADS)

    Liang, Yingjie; Chen, Wen

    2015-01-01

    This paper develops a relative entropy method to measure non-exponential random data in conjunction with fractional order moment, logarithmic moment and tail statistics of Mittag-Leffler distribution. The distribution of non-exponential random data follows neither the exponential distribution nor exponential decay. The proposed strategy is validated by analyzing the experiment data, which are generated by Monte Carlo method using Mittag-Leffler distribution. Compared with the traditional Shannon entropy, the relative entropy method is simple to be implemented, and its corresponding relative entropies approximated by the fractional order moment, logarithmic moment and tail statistics can easily and accurately detect the non-exponential random data.

  3. Non-exponential Stabilization of Linear Time-invariant Systems by Time-varying Controllers

    NASA Astrophysics Data System (ADS)

    Inoue, Masaki; Wada, Teruyo; Ikeda, Masao

    This paper proposes non-exponential stabilization of linear time-invariant systems by linear time-varying controllers. We consider state feedback and dynamic output feedback to make the states of the closed-loop systems decay non-exponentially. We first introduce a non-exponential stability concept that the state of a time-varying system converges to the origin with a bound provided by a desired function. Then, we give non-exponential stabilizability conditions and time-varying controllers to achieve the desired behavior of the closed-loop systems. By the proposed methods, we can realize various non-exponential behaviors, which may improve control performance.

  4. Supergravity with doubled spacetime structure

    NASA Astrophysics Data System (ADS)

    Ma, Chen-Te; Pezzella, Franco

    2017-03-01

    Double field theory (DFT) is a low-energy effective theory of a manifestly O (D ,D ) -invariant formulation of the closed-string theory. The theory is based on a doubling of the D -dimensional spacetime structure and, in order to preserve the gauge symmetry provided by the invariance under generalized diffeomorphisms, a constraint has to be imposed on fields and gauge parameters. In this paper, we consider a DFT-inspired supergravity by using a suitable commutative star product of fields and gauge parameters with the aim of studying the corresponding algebraic structure. This star product is not associative, implying the nonclosure of the gauge transformations. Despite this, we get a consistent theory in which an orthogonality condition of momenta associated with double fields is also necessary to have a closed gauge algebra. We first start from the simplest case of one compact spatial dimension. Then, the extension to the case of d spatial dimensions is taken into consideration.

  5. Exponential-family random graph models for valued networks

    PubMed Central

    Krivitsky, Pavel N.

    2013-01-01

    Exponential-family random graph models (ERGMs) provide a principled and flexible way to model and simulate features common in social networks, such as propensities for homophily, mutuality, and friend-of-a-friend triad closure, through choice of model terms (sufficient statistics). However, those ERGMs modeling the more complex features have, to date, been limited to binary data: presence or absence of ties. Thus, analysis of valued networks, such as those where counts, measurements, or ranks are observed, has necessitated dichotomizing them, losing information and introducing biases. In this work, we generalize ERGMs to valued networks. Focusing on modeling counts, we formulate an ERGM for networks whose ties are counts and discuss issues that arise when moving beyond the binary case. We introduce model terms that generalize and model common social network features for such data and apply these methods to a network dataset whose values are counts of interactions. PMID:24678374

  6. Exponential and power laws in public procurement markets

    NASA Astrophysics Data System (ADS)

    Kristoufek, Ladislav; Skuhrovec, Jiri

    2012-07-01

    We analyze for the first time a unique public procurement database, which includes information about a number of bidders for a contract, a final price, an identification of a winner and an identification of a contracting authority for each of more than 40000 public procurements in the Czech Republic between 2006 and 2011, focusing on the distributional properties of the variables of interest. We uncover several scaling laws —the exponential law for the number of bidders, and the power laws for the total revenues and total spendings of the participating companies, which even follows Zipf's law for the 100 most spending institutions. We propose an analogy between extensive and non-extensive systems in physics and the public procurement market situations. Through an entropy maximization, such analogy yields some interesting results and policy implications with respect to the Maxwell-Boltzmann and Pareto distributions in the analyzed quantities.

  7. Non-exponential decay of dark localized surface plasmons.

    PubMed

    Ginzburg, Pavel; Zayats, Anatoly V

    2012-03-12

    It is shown that the decay of the weakly coupled to radiation (dark) modes of subwavelength plasmonic nanostructures is strongly nonexponential. Their lifetime is overestimated by conventional exponential relaxation time obtained in the standard Markovian approximation. These effects are manifestations of the strong dispersion and near-field feedback. The developed theoretical framework introduces an ensemble of local relaxation degrees of freedom coupled to plasmonic mode in order to describe its decay due to material losses. The macroscopic description of the decay process leads to the specific memory function of the system, evaluated from the modal and material dispersions of the plasmonic nanostructure. Proper knowledge of the relaxation behavior is vital for various applications relying on light-matter interactions of emitters with nanoscale objects, such as fluorescence manipulation, bio-imaging, sensing, spasers, sub-diffraction optics, Raman scattering, and quantum optics.

  8. Asymptotic behavior of Cardassian cosmologies with exponential potentials

    SciTech Connect

    Lazkoz, Ruth; Leon, Genly

    2005-06-15

    In this paper we analyze the asymptotic behavior of Cardassian cosmological models filled with a perfect fluid and a scalar field with an exponential potential. Cardassian cosmologies arise from modifications of the Friedmann equation, and among the different proposals within that framework we will choose those of the form 3H{sup 2}-{rho}{proportional_to}{rho}{sup n} with n<1. We construct two three-dimensional dynamical systems arising from the evolution equations, respectively, adapted for studying the high and low energy limits. Using standard dynamical systems techniques we find the fixed points and characterize the solutions they represent. We pay especial attention to the properties inherent to the modifications and compare with the (standard) unmodified scenario. Among other interesting results, we find there are no late-time tracking attractors.

  9. Income inequality in Romania: The exponential-Pareto distribution

    NASA Astrophysics Data System (ADS)

    Oancea, Bogdan; Andrei, Tudorel; Pirjol, Dan

    2017-03-01

    We present a study of the distribution of the gross personal income and income inequality in Romania, using individual tax income data, and both non-parametric and parametric methods. Comparing with official results based on household budget surveys (the Family Budgets Survey and the EU-SILC data), we find that the latter underestimate the income share of the high income region, and the overall income inequality. A parametric study shows that the income distribution is well described by an exponential distribution in the low and middle incomes region, and by a Pareto distribution in the high income region with Pareto coefficient α = 2.53. We note an anomaly in the distribution in the low incomes region (∼9,250 RON), and present a model which explains it in terms of partial income reporting.

  10. Exponentially small splitting of separatrices beyond Melnikov analysis: Rigorous results

    NASA Astrophysics Data System (ADS)

    Baldomá, Inmaculada; Fontich, Ernest; Guardia, Marcel; Seara, Tere M.

    We study the problem of exponentially small splitting of separatrices of one degree of freedom classical Hamiltonian systems with a non-autonomous perturbation fast and periodic in time. We provide a result valid for general systems which are algebraic or trigonometric polynomials in the state variables. It consists on obtaining a rigorous proof of the asymptotic formula for the measure of the splitting. We obtain that the splitting has the asymptotic behavior Kɛβe, identifying the constants K, β, a in terms of the system features. We consider several cases. In some cases, assuming the perturbation is small enough, the values of K, β coincide with the classical Melnikov approach. We identify the limit size of the perturbation for which this theory holds true. However for the limit cases, which appear naturally both in averaging and bifurcation theories, we encounter that, generically, K and β are not well predicted by Melnikov theory.

  11. Exponentially Fragile PT Symmetry in Lattices with Localized Eigenmodes

    SciTech Connect

    Bendix, Oliver; Fleischmann, Ragnar; Kottos, Tsampikos; Shapiro, Boris

    2009-07-17

    We study the effect of localized modes in lattices of size N with parity-time (PT) symmetry. Such modes are arranged in pairs of quasidegenerate levels with splitting deltaapproxexp{sup -N/x}i where xi is their localization length. The level 'evolution' with respect to the PT breaking parameter gamma shows a cascade of bifurcations during which a pair of real levels becomes complex. The spontaneous PT symmetry breaking occurs at gamma{sub PT}approxmin(delta), thus resulting in an exponentially narrow exact PT phase. As N/xi decreases, it becomes more robust with gamma{sub PT}approx1/N{sup 2} and the distribution P(gamma{sub PT}) changes from log-normal to semi-Gaussian. Our theory can be tested in the frame of optical lattices.

  12. Statistical modelling of agrometeorological time series by exponential smoothing

    NASA Astrophysics Data System (ADS)

    Murat, Małgorzata; Malinowska, Iwona; Hoffmann, Holger; Baranowski, Piotr

    2016-01-01

    Meteorological time series are used in modelling agrophysical processes of the soil-plant-atmosphere system which determine plant growth and yield. Additionally, long-term meteorological series are used in climate change scenarios. Such studies often require forecasting or projection of meteorological variables, eg the projection of occurrence of the extreme events. The aim of the article was to determine the most suitable exponential smoothing models to generate forecast using data on air temperature, wind speed, and precipitation time series in Jokioinen (Finland), Dikopshof (Germany), Lleida (Spain), and Lublin (Poland). These series exhibit regular additive seasonality or non-seasonality without any trend, which is confirmed by their autocorrelation functions and partial autocorrelation functions. The most suitable models were indicated by the smallest mean absolute error and the smallest root mean squared error.

  13. Iterative Exponential Growth Synthesis and Assembly of Uniform Diblock Copolymers.

    PubMed

    Jiang, Yivan; Golder, Matthew R; Nguyen, Hung V-T; Wang, Yufeng; Zhong, Mingjiang; Barnes, Jonathan C; Ehrlich, Deborah J C; Johnson, Jeremiah A

    2016-08-03

    Studies on the phase segregation of unimolecular block copolymers (BCPs) are limited by a lack of reliable, versatile methods for the synthesis of such polymers on the preparative scale. Herein, we describe an advancement of Iterative Exponential Growth (IEG) wherein chiral allyl-based IEG oligomers are subjected to thiol-ene reactions and converted into unimolecular BCPs. With this strategy we have synthesized uniform BCPs with molar masses up to 12.1 kDa on ∼1 g scale. BCPs composed of decane-based side chains and either triethyleneglycol- or thioglycerol-based side chains phase-segregate into hexagonal cylinder morphologies. The assembly is not driven by side-chain crystallization, but is instead the result of amorphous BCP assembly.

  14. Stretched exponential distribution of recurrent time of wars in China

    NASA Astrophysics Data System (ADS)

    Tang, Da-Hai; Han, Xiao-Pu; Wang, Bing-Hong

    2010-07-01

    As a killing machine and a decisive factor of history, wars play an important role in social system. In this paper, we present an empirical exploration of the distribution of recurrent time of wars in ancient China and find that it obeys a stretched exponential form. The pattern we found implies that there are undetected mechanisms that underlie the dynamics of wars. In order to explain the origin of this form, a model mainly based on the correlation between two consecutive wars is constructed, which is somewhat similar to the Bak-Sneppen model. The simulation results of the model are in agreement with the empirical statistics and suggest that the dynamics of wars could relate with self-organized criticality.

  15. Predicting jet radius in electrospinning by superpositioning exponential functions

    NASA Astrophysics Data System (ADS)

    Widartiningsih, P. M.; Iskandar, F.; Munir, M. M.; Viridi, S.

    2016-08-01

    This paper presents an analytical study of the correlation between viscosity and fiber diameter in electrospinning. Control over fiber diameter in electrospinning process was important since it will determine the performance of resulting nanofiber. Theoretically, fiber diameter was determined by surface tension, solution concentration, flow rate, and electric current. But experimentally it had been proven that significantly viscosity had an influence to fiber diameter. Jet radius equation in electrospinning process was divided into three areas: near the nozzle, far from the nozzle, and at jet terminal. There was no correlation between these equations. Superposition of exponential series model provides the equations combined into one, thus the entire of working parameters on electrospinning take a contribution to fiber diameter. This method yields the value of solution viscosity has a linear relation to jet radius. However, this method works only for low viscosity.

  16. Exponential absorption edge and disorder in Column IV amorphous semiconductors

    NASA Astrophysics Data System (ADS)

    Zanatta, A. R.; Mulato, M.; Chambouleyron, I.

    1998-11-01

    We discuss the likely origin of the exponential absorption tail, or Urbach edge, of fourfold coordinated amorphous (a-)semiconductors. The present analysis is based on a compilation of a considerable amount of experimental data originating from a great variety of samples, alloys, and authors, and obtained with quite different spectroscopic techniques. An attempt is made to correlate the measured Urbach edge with the structural and optical properties of the samples. The present analysis indicates that the Urbach edge may not only reflect the shape of the joint density of states of the valence and conduction band tails, but may also have important contributions from short-range order potential fluctuations produced by charged defects or impurities.

  17. Black hole as a magnetic monopole within exponential nonlinear electrodynamics

    NASA Astrophysics Data System (ADS)

    Kruglov, S. I.

    2017-03-01

    We perform the gauge covariant quantization of the exponential model of nonlinear electrodynamics. Magnetically charged black holes, in the framework of our model are considered, and the regular black hole solution is obtained in general relativity. The asymptotic black hole solution at r → ∞ is found. We calculate the magnetic mass of the black hole and the metric function which are expressed via the parameter β of the model and the magnetic charge. The thermodynamic properties and thermal stability of regular black holes are analysed. We calculate the Hawking temperature of black holes and their heat capacity at the constant magnetic charge. We find a point where the temperature changes the sign that corresponds to the first-order phase transition. It is shown that at critical point, where the heat capacity diverges, there is a phase transition of the second-order. We obtain the parameters of the model when the black hole is stable.

  18. Atomic shell structure from the Single-Exponential Decay Detector

    SciTech Connect

    Silva, Piotr de; Korchowiec, Jacek; Wesolowski, Tomasz A.

    2014-04-28

    The density of atomic systems is analysed via the Single-Exponential Decay Detector (SEDD). SEDD is a scalar field designed to explore mathematical, rather than physical, properties of electron density. Nevertheless, it has been shown that SEDD can serve as a descriptor of bonding patterns in molecules as well as an indicator of atomic shells [P. de Silva, J. Korchowiec, and T. A. Wesolowski, ChemPhysChem 13, 3462 (2012)]. In this work, a more detailed analysis of atomic shells is done for atoms in the Li–Xe series. Shell populations based on SEDD agree with the Aufbau principle even better than those obtained from the Electron Localization Function, which is a popular indicator of electron localization. A link between SEDD and the local wave vector is given, which provides a physical interpretation of SEDD.

  19. On exponential stability of gravity driven viscoelastic flows

    NASA Astrophysics Data System (ADS)

    Jiang, Fei; Wu, Guochun; Zhong, Xin

    2016-05-01

    We investigate stability of an equilibrium state to a nonhomogeneous incompressible viscoelastic fluid driven by gravity in a bounded domain Ω ⊂R3 of class C3. First, we establish a critical number κC, which depends on the equilibrium density and the gravitational constant, and is a threshold of the elasticity coefficient κ for instability and stability of the linearized perturbation problem around the equilibrium state. Then we prove that the equilibrium state is exponential stability provided that κ >κC and the initial disturbance quantities around the equilibrium state satisfy some relations. In particular, if the equilibrium density ρ bar is a Rayleigh-Taylor (RT) type and ρbar‧ is a constant, our result strictly shows that the sufficiently large elasticity coefficient can prevent the RT instability from occurrence.

  20. Evaluation of lung elastic recoil by exponential curve analysis.

    PubMed

    Knudson, R J; Kaltenborn, W T

    1981-10-01

    Static deflation pressure-volume curves for the lungs of 104 subjects were satisfactorily fitted to an exponential function, V = Vmax - Ae-kP (where Vmax is volume V extrapolated to infinite transpulmonary pressure P, and A and k are constants). Subjects included 48 who met rigorous criteria defining normal, 35 were PiM phenotype for alpha-1-antitrypsin deficiency and 21 were PiMZ phenotype. The shape constant k was significantly related to age, whereas an index of curve position was not. Values for k corresponded closely to the data of other investigators suggesting that it was independent of size and insensitive to differences in experimental technique. Elevated values of k, indicative of emphysema, were no more prevalent among PiMZ subjects than among subjects with no alpha-1-anti-trypsin deficiency. The natural logarithm (1n) of k, rather than k itself, appears to provide a useful, normally distributed, expression of lung distensibility.

  1. Iterative exponential growth of stereo- and sequence-controlled polymers.

    PubMed

    Barnes, Jonathan C; Ehrlich, Deborah J C; Gao, Angela X; Leibfarth, Frank A; Jiang, Yivan; Zhou, Erica; Jamison, Timothy F; Johnson, Jeremiah A

    2015-10-01

    Chemists have long sought sequence-controlled synthetic polymers that mimic nature's biopolymers, but a practical synthetic route that enables absolute control over polymer sequence and structure remains a key challenge. Here, we report an iterative exponential growth plus side-chain functionalization (IEG+) strategy that begins with enantiopure epoxides and facilitates the efficient synthesis of a family of uniform >3 kDa macromolecules of varying sequence and stereoconfiguration that are coupled to produce unimolecular polymers (>6 kDa) with sequences and structures that cannot be obtained using traditional polymerization techniques. Selective side-chain deprotection of three hexadecamers is also demonstrated, which imbues each compound with the ability to dissolve in water. We anticipate that these new macromolecules and the general IEG+ strategy will find broad application as a versatile platform for the scalable synthesis of sequence-controlled polymers.

  2. Iterative exponential growth of stereo- and sequence-controlled polymers

    NASA Astrophysics Data System (ADS)

    Barnes, Jonathan C.; Ehrlich, Deborah J. C.; Gao, Angela X.; Leibfarth, Frank A.; Jiang, Yivan; Zhou, Erica; Jamison, Timothy F.; Johnson, Jeremiah A.

    2015-10-01

    Chemists have long sought sequence-controlled synthetic polymers that mimic nature's biopolymers, but a practical synthetic route that enables absolute control over polymer sequence and structure remains a key challenge. Here, we report an iterative exponential growth plus side-chain functionalization (IEG+) strategy that begins with enantiopure epoxides and facilitates the efficient synthesis of a family of uniform >3 kDa macromolecules of varying sequence and stereoconfiguration that are coupled to produce unimolecular polymers (>6 kDa) with sequences and structures that cannot be obtained using traditional polymerization techniques. Selective side-chain deprotection of three hexadecamers is also demonstrated, which imbues each compound with the ability to dissolve in water. We anticipate that these new macromolecules and the general IEG+ strategy will find broad application as a versatile platform for the scalable synthesis of sequence-controlled polymers.

  3. Auxiliary Parameter MCMC for Exponential Random Graph Models

    NASA Astrophysics Data System (ADS)

    Byshkin, Maksym; Stivala, Alex; Mira, Antonietta; Krause, Rolf; Robins, Garry; Lomi, Alessandro

    2016-11-01

    Exponential random graph models (ERGMs) are a well-established family of statistical models for analyzing social networks. Computational complexity has so far limited the appeal of ERGMs for the analysis of large social networks. Efficient computational methods are highly desirable in order to extend the empirical scope of ERGMs. In this paper we report results of a research project on the development of snowball sampling methods for ERGMs. We propose an auxiliary parameter Markov chain Monte Carlo (MCMC) algorithm for sampling from the relevant probability distributions. The method is designed to decrease the number of allowed network states without worsening the mixing of the Markov chains, and suggests a new approach for the developments of MCMC samplers for ERGMs. We demonstrate the method on both simulated and actual (empirical) network data and show that it reduces CPU time for parameter estimation by an order of magnitude compared to current MCMC methods.

  4. On Using Exponential Parameter Estimators with an Adaptive Controller

    NASA Technical Reports Server (NTRS)

    Patre, Parag; Joshi, Suresh M.

    2011-01-01

    Typical adaptive controllers are restricted to using a specific update law to generate parameter estimates. This paper investigates the possibility of using any exponential parameter estimator with an adaptive controller such that the system tracks a desired trajectory. The goal is to provide flexibility in choosing any update law suitable for a given application. The development relies on a previously developed concept of controller/update law modularity in the adaptive control literature, and the use of a converse Lyapunov-like theorem. Stability analysis is presented to derive gain conditions under which this is possible, and inferences are made about the tracking error performance. The development is based on a class of Euler-Lagrange systems that are used to model various engineering systems including space robots and manipulators.

  5. Reversible accumulation of double- and single-stranded DNA breaks in DNA in growth-arrested cells

    SciTech Connect

    S'yakste, N.I.; S'yakste, T.G.; Zaleskaya, N.D.

    1987-01-01

    The authors study the possibility of the formation and repair of double-stranded breaks in DNA during a change in the proliferative status of cells. Jungarian hamster fibroblasts, transformed by SV-40 virus, were cultured in Carrel's flasks in a nutrient mixture containing Eagle's medium, lactalbumin hydrolysate, and bovine serum in the ratio of 4.5:4.5:1. DNA was labelled by the addition of 0.4 MBq/ml of tritium-thymidine to the incubation medium for 2-7 days. To arrest cell growth, the monolayer formed seven days after seeding was placed in medium with the serum concentration lowered to 1%, and incubated for 7-9 days. The cells were restimulated for division with fresh complete medium. The mitotic index was 20% in the exponentially growing cultures while in the resting cultures it was 1-2% and rose to 16% 2 days after stimulation. Double-stranded DNA breaks were determined by neutral elution of DNA; single-stranded breaks were measured by the alkaline DNA uncoiling method with fixation of hydroxyapatite. The formation of double-stranded DNA breaks and their repair, in response to a change in the proliferative status of the cell, were discovered for the first time.

  6. Transformational Events

    ERIC Educational Resources Information Center

    Denning, Peter J.; Hiles, John E.

    2006-01-01

    Transformational Events is a new pedagogic pattern that explains how innovations (and other transformations) happened. The pattern is three temporal stages: an interval of increasingly unsatisfactory ad hoc solutions to a persistent problem (the "mess"), an offer of an invention or of a new way of thinking, and a period of widespread adoption and…

  7. Reading Transformation

    ERIC Educational Resources Information Center

    Reeves, Melinda

    2006-01-01

    The parents of students who attend Decatur High School thought that there was little hope of their kids going on to college. After a year or so in Decatur's reading program, their sons and daughters were both transformed and college bound. In this article, the author describes how Decatur was able to successfully transform their students. Seven…

  8. Reading Transformation

    ERIC Educational Resources Information Center

    Reeves, Melinda

    2006-01-01

    The parents of students who attend Decatur High School thought that there was little hope of their kids going on to college. After a year or so in Decatur's reading program, their sons and daughters were both transformed and college bound. In this article, the author describes how Decatur was able to successfully transform their students. Seven…

  9. Transformational Events

    ERIC Educational Resources Information Center

    Denning, Peter J.; Hiles, John E.

    2006-01-01

    Transformational Events is a new pedagogic pattern that explains how innovations (and other transformations) happened. The pattern is three temporal stages: an interval of increasingly unsatisfactory ad hoc solutions to a persistent problem (the "mess"), an offer of an invention or of a new way of thinking, and a period of widespread adoption and…

  10. Exponential and power-law mass distributions in brittle fragmentation

    NASA Astrophysics Data System (ADS)

    Åström, J. A.; Linna, R. P.; Timonen, J.; Møller, Peder Friis; Oddershede, Lene

    2004-08-01

    Generic arguments, a minimal numerical model, and fragmentation experiments with gypsum disk are used to investigate the fragment-size distribution that results from dynamic brittle fragmentation. Fragmentation is initiated by random nucleation of cracks due to material inhomogeneities, and its dynamics are pictured as a process of propagating cracks that are unstable against side-branch formation. The initial cracks and side branches both merge mutually to form fragments. The side branches have a finite penetration depth as a result of inherent damping. Generic arguments imply that close to the minimum strain (or impact energy) required for fragmentation, the number of fragments of size s scales as s-(2D-1)/Df1(-(2/λ)Ds)+f2(-s0-1(λ+s1/D)D) , where D is the Euclidean dimension of the space, λ is the penetration depth, and f1 and f2 can be approximated by exponential functions. Simulation results and experiments can both be described by this theoretical fragment-size distribution. The typical largest fragment size s0 was found to diverge at the minimum strain required for fragmentation as it is inversely related to the density of initially formed cracks. Our results also indicate that scaling of s0 close to this divergence depends on, e.g., loading conditions, and thus is not universal. At the same time, the density of fragment surface vanishes as L-1 , L being the linear dimension of the brittle solid. The results obtained provide an explanation as to why the fragment-size distributions found in nature can have two components, an exponential as well as a power-law component, with varying relative weights.

  11. Exponential protection of zero modes in Majorana islands.

    PubMed

    Albrecht, S M; Higginbotham, A P; Madsen, M; Kuemmeth, F; Jespersen, T S; Nygård, J; Krogstrup, P; Marcus, C M

    2016-03-10

    Majorana zero modes are quasiparticle excitations in condensed matter systems that have been proposed as building blocks of fault-tolerant quantum computers. They are expected to exhibit non-Abelian particle statistics, in contrast to the usual statistics of fermions and bosons, enabling quantum operations to be performed by braiding isolated modes around one another. Quantum braiding operations are topologically protected insofar as these modes are pinned near zero energy, with the departure from zero expected to be exponentially small as the modes become spatially separated. Following theoretical proposals, several experiments have identified signatures of Majorana modes in nanowires with proximity-induced superconductivity and atomic chains, with small amounts of mode splitting potentially explained by hybridization of Majorana modes. Here, we use Coulomb-blockade spectroscopy in an InAs nanowire segment with epitaxial aluminium, which forms a proximity-induced superconducting Coulomb island (a 'Majorana island') that is isolated from normal-metal leads by tunnel barriers, to measure the splitting of near-zero-energy Majorana modes. We observe exponential suppression of energy splitting with increasing wire length. For short devices of a few hundred nanometres, sub-gap state energies oscillate as the magnetic field is varied, as is expected for hybridized Majorana modes. Splitting decreases by a factor of about ten for each half a micrometre of increased wire length. For devices longer than about one micrometre, transport in strong magnetic fields occurs through a zero-energy state that is energetically isolated from a continuum, yielding uniformly spaced Coulomb-blockade conductance peaks, consistent with teleportation via Majorana modes. Our results help to explain the trivial-to-topological transition in finite systems and to quantify the scaling of topological protection with end-mode separation.

  12. Subglacial bedforms reveal an exponential size-frequency distribution

    NASA Astrophysics Data System (ADS)

    Hillier, J. K.; Smith, M. J.; Clark, C. D.; Stokes, C. R.; Spagnolo, M.

    2013-05-01

    Subglacial bedforms preserved in deglaciated landscapes record characteristics of past ice-sediment flow regimes, providing insight into subglacial processes and ice sheet dynamics. Individual forms vary considerably, but they can often be grouped into coherent fields, typically called flow-sets, that reflect discrete episodes of ice flow. Within these, bedform size-frequency distributions (predominantly height, width and length) are currently described by several statistics (e.g., mean, median, and standard deviation) that, arguably, do not best capture the defining characteristics of these populations. This paper seeks to create a better description based upon semi-log plots, which reveal that the frequency distributions of bedform dimensions (drumlin, mega-scale glacial lineation, and ribbed moraine) plot as straight lines above the mode (ϕ). This indicates, by definition, an exponential distribution, for which a simple and easily calculated, yet statistically rigorous, description is designed. Three descriptive parameters are proposed: gradient (λ; the exponent, characterising bedforms likely least affected by non-glacial factors), area-normalised y-intercept (β0; quantifying spatial density), and the mode (ϕ). Below ϕ, small features are less prevalent due to i) measurement: data, sampling and mapping fidelity; ii) possible post-glacial degradation; or iii) genesis: not being created sub-glacially. This new description has the benefit of being insensitive to the impact of potentially unmapped or degraded smaller features and better captures properties relating to ice flow. Importantly, using λ, flow sets can now be more usefully compared with each other across all deglaciated regions and with the output of numerical ice sheet models. Applications may also exist for analogous fluvial and aeolian bedforms. Identifying the characteristic exponential and that it is typical of 'emergent' subglacial bedforms is a new and potentially powerful constraint on

  13. Exponential protection of zero modes in Majorana islands

    NASA Astrophysics Data System (ADS)

    Albrecht, S. M.; Higginbotham, A. P.; Madsen, M.; Kuemmeth, F.; Jespersen, T. S.; Nygård, J.; Krogstrup, P.; Marcus, C. M.

    2016-03-01

    Majorana zero modes are quasiparticle excitations in condensed matter systems that have been proposed as building blocks of fault-tolerant quantum computers. They are expected to exhibit non-Abelian particle statistics, in contrast to the usual statistics of fermions and bosons, enabling quantum operations to be performed by braiding isolated modes around one another. Quantum braiding operations are topologically protected insofar as these modes are pinned near zero energy, with the departure from zero expected to be exponentially small as the modes become spatially separated. Following theoretical proposals, several experiments have identified signatures of Majorana modes in nanowires with proximity-induced superconductivity and atomic chains, with small amounts of mode splitting potentially explained by hybridization of Majorana modes. Here, we use Coulomb-blockade spectroscopy in an InAs nanowire segment with epitaxial aluminium, which forms a proximity-induced superconducting Coulomb island (a ‘Majorana island’) that is isolated from normal-metal leads by tunnel barriers, to measure the splitting of near-zero-energy Majorana modes. We observe exponential suppression of energy splitting with increasing wire length. For short devices of a few hundred nanometres, sub-gap state energies oscillate as the magnetic field is varied, as is expected for hybridized Majorana modes. Splitting decreases by a factor of about ten for each half a micrometre of increased wire length. For devices longer than about one micrometre, transport in strong magnetic fields occurs through a zero-energy state that is energetically isolated from a continuum, yielding uniformly spaced Coulomb-blockade conductance peaks, consistent with teleportation via Majorana modes. Our results help to explain the trivial-to-topological transition in finite systems and to quantify the scaling of topological protection with end-mode separation.

  14. Multiple factors underlying the maximum motility of Escherichia coli as cultures enter post-exponential growth.

    PubMed Central

    Amsler, C D; Cho, M; Matsumura, P

    1993-01-01

    Motility and chemotaxis allow cells to move away from stressful microenvironments. Motility of Escherichia coli in batch cultures, as measured by cell swimming speed, was low in early-exponential-phase cells, peaked as the cells entered post-exponential phase, and declined into early stationary phase. Transcription from the flhB operon and synthesis of flagellin protein similarly peaked in late exponential and early post-exponential phases, respectively. The increase in swimming speed between early-exponential and post-exponential phases was correlated with twofold increases in both flagellar length and flagellar density per cell volume. This increased investment in flagella probably reflects the increased adaptive value of motility in less favorable environments. The decrease in speed between post-exponential and stationary phases was correlated with a threefold decrease in torque produced by the flagellar motors and presumably reflects decreased proton motive force available to stationary-phase cells. Images PMID:8407796

  15. Analytic solutions to modelling exponential and harmonic functions using Chebyshev polynomials: fitting frequency-domain lifetime images with photobleaching.

    PubMed

    Malachowski, George C; Clegg, Robert M; Redford, Glen I

    2007-12-01

    A novel approach is introduced for modelling linear dynamic systems composed of exponentials and harmonics. The method improves the speed of current numerical techniques up to 1000-fold for problems that have solutions of multiple exponentials plus harmonics and decaying components. Such signals are common in fluorescence microscopy experiments. Selective constraints of the parameters being fitted are allowed. This method, using discrete Chebyshev transforms, will correctly fit large volumes of data using a noniterative, single-pass routine that is fast enough to analyse images in real time. The method is applied to fluorescence lifetime imaging data in the frequency domain with varying degrees of photobleaching over the time of total data acquisition. The accuracy of the Chebyshev method is compared to a simple rapid discrete Fourier transform (equivalent to least-squares fitting) that does not take the photobleaching into account. The method can be extended to other linear systems composed of different functions. Simulations are performed and applications are described showing the utility of the method, in particular in the area of fluorescence microscopy.

  16. Vibrational energies for HFCO using a neural network sum of exponentials potential energy surface

    NASA Astrophysics Data System (ADS)

    Pradhan, Ekadashi; Brown, Alex

    2016-05-01

    A six-dimensional potential energy surface (PES) for formyl fluoride (HFCO) is fit in a sum-of-products form using neural network exponential fitting functions. The ab initio data upon which the fit is based were computed at the explicitly correlated coupled cluster with single, double, and perturbative triple excitations [CCSD(T)-F12]/cc-pVTZ-F12 level of theory. The PES fit is accurate (RMSE = 10 cm-1) up to 10 000 cm-1 above the zero point energy and covers most of the experimentally measured IR data. The PES is validated by computing vibrational energies for both HFCO and deuterated formyl fluoride (DFCO) using block improved relaxation with the multi-configuration time dependent Hartree approach. The frequencies of the fundamental modes, and all other vibrational states up to 5000 cm-1 above the zero-point energy, are more accurate than those obtained from the previous MP2-based PES. The vibrational frequencies obtained on the PES are compared to anharmonic frequencies at the MP2/aug-cc-pVTZ and CCSD(T)/aug-cc-pVTZ levels of theory obtained using second-order vibrational perturbation theory. The new PES will be useful for quantum dynamics simulations for both HFCO and DFCO, e.g., studies of intramolecular vibrational redistribution leading to unimolecular dissociation and its laser control.

  17. Free-space communications over exponentiated Weibull turbulence channels with nonzero boresight pointing errors.

    PubMed

    Yi, Xiang; Yao, Mingwu

    2015-02-09

    In this paper, we present analytical expressions for the performance of urban free-space optical (FSO) communication systems under the combined influence of atmospheric turbulence- and misalignment-induced fading (pointing errors). The atmospheric turbulence channel is modeled by the exponentiated Weibull (EW) distribution that can accurately describe the probability density function (PDF) of the irradiance fluctuations associated with a transmitted Gaussian-beam wave and a finite-sized receiving aperture. The nonzero boresight pointing error PDF model, which is recently proposed for considering the effects of both boresight and jitter, is adopted in analysis. We derive a novel expression for the composite PDF in terms of a convergent double series involving a Meijer's G-function. Based on the statistical results mentioned above, exact expressions for the average bit error rate of on-off keying modulation scheme and the outage probability are developed. To provide more insight, we also perform an asymptotic error rate analysis at high average signal-to-noise ratio. Our analytical results indicate that the diversity gain for the zero boresight case is determined only by the ratio between the equivalent beamwidth at the receiver and the jitter standard deviation, while for the nonzero boresight case, the diversity gain is related to the ratio of the equivalent beamwidth to the jitter variance as well as the parameter of the EW distribution.

  18. Exponential growth and selection in self-replicating materials from DNA origami rafts

    NASA Astrophysics Data System (ADS)

    He, Xiaojin; Sha, Ruojie; Zhuo, Rebecca; Mi, Yongli; Chaikin, Paul M.; Seeman, Nadrian C.

    2017-10-01

    Self-replication and evolution under selective pressure are inherent phenomena in life, and but few artificial systems exhibit these phenomena. We have designed a system of DNA origami rafts that exponentially replicates a seed pattern, doubling the copies in each diurnal-like cycle of temperature and ultraviolet illumination, producing more than 7 million copies in 24 cycles. We demonstrate environmental selection in growing populations by incorporating pH-sensitive binding in two subpopulations. In one species, pH-sensitive triplex DNA bonds enable parent-daughter templating, while in the second species, triplex binding inhibits the formation of duplex DNA templating. At pH 5.3, the replication rate of species I is ~1.3-1.4 times faster than that of species II. At pH 7.8, the replication rates are reversed. When mixed together in the same vial, the progeny of species I replicate preferentially at pH 7.8 similarly at pH 5.3, the progeny of species II take over the system. This addressable selectivity should be adaptable to the selection and evolution of multi-component self-replicating materials in the nanoscopic-to-microscopic size range.

  19. Vibrational energies for HFCO using a neural network sum of exponentials potential energy surface.

    PubMed

    Pradhan, Ekadashi; Brown, Alex

    2016-05-07

    A six-dimensional potential energy surface (PES) for formyl fluoride (HFCO) is fit in a sum-of-products form using neural network exponential fitting functions. The ab initio data upon which the fit is based were computed at the explicitly correlated coupled cluster with single, double, and perturbative triple excitations [CCSD(T)-F12]/cc-pVTZ-F12 level of theory. The PES fit is accurate (RMSE = 10 cm(-1)) up to 10 000 cm(-1) above the zero point energy and covers most of the experimentally measured IR data. The PES is validated by computing vibrational energies for both HFCO and deuterated formyl fluoride (DFCO) using block improved relaxation with the multi-configuration time dependent Hartree approach. The frequencies of the fundamental modes, and all other vibrational states up to 5000 cm(-1) above the zero-point energy, are more accurate than those obtained from the previous MP2-based PES. The vibrational frequencies obtained on the PES are compared to anharmonic frequencies at the MP2/aug-cc-pVTZ and CCSD(T)/aug-cc-pVTZ levels of theory obtained using second-order vibrational perturbation theory. The new PES will be useful for quantum dynamics simulations for both HFCO and DFCO, e.g., studies of intramolecular vibrational redistribution leading to unimolecular dissociation and its laser control.

  20. [Transformation toughening

    SciTech Connect

    Rafa, M.J.

    1993-04-19

    In NiAl, we have succeeded in determining the complete Ginzburg-Landau strain free energy function necessary to model the cubic to tetragonal martensite transformation in a sample of any size. We believe that this is the first time that the parameters of a Ginzburg-Landau functional and the complete strain spinodal for any three-dimensional displacive transformation were used in simulating the transformation near a crack tip under Mode I loading; the transformation pattern and toughening are different from standard transformation toughening theories. Furthermore, the strain spinodal has an approximately conical shape which can be specified by two material dependent experimentally accessible parameters, rather than the ellipsoidal shape in standard theories. Stress induced martensitic transformation in a polycrystalline sample of NiAl was simulated. In the ZrO[sub 2] system, first principles calculations to determine the semi-empirical potentials for simulating the cubic-tetragonal and tetragonal-monoclinic transformations have been started by doing a more elaborate total energy calculation.In the Al[sub 2]0[sub 3] system, we have discovered that the first principles calculations and semi-empirical potentials have just been completed byanother group in England which we will use instead to base our molecular dynamics simulations on.

  1. Lightweight transformer

    SciTech Connect

    Swallom, D.W.; Enos, G.

    1990-05-01

    The technical effort described in this report relates to the program that was performed to design, fabricate, and test a lightweight transformer for Strategic Defense Initiative Organization (SDIO) mission requirements. The objectives of this program were two-fold: (1) design and fabricate a lightweight transformer using liquid hydrogen as the coolant; and (2) test the completed transformer assembly with a low voltage, dc power source. Although the full power testing with liquid helium was not completed, the program demonstrated the viability of the design approach. The lightweight transformer was designed and fabricated, and low and moderate power testing was completed. The transformer is a liquid hydrogen cooled air core transformer that uses thin copper for its primary and secondary windings. The winding mass was approximately 12 kg, or 0.03 kg/kW. Further refinements of the design to a partial air core transformer could potentially reduce the winding mass to as low as 4 or 5 kg, or 0.0125 kg/kW. No attempt was made on this program to reduce the mass of the related structural components or cryogenic container. 8 refs., 39 figs., 2 tabs.

  2. Gauss and Markov quadrature formulae with nodes at zeros of eigenfunctions of a Sturm-Liouville problem, which are exact for entire functions of exponential type

    SciTech Connect

    Gorbachev, D V; Ivanov, V I

    2015-08-31

    Gauss and Markov quadrature formulae with nodes at zeros of eigenfunctions of a Sturm-Liouville problem, which are exact for entire functions of exponential type, are established. They generalize quadrature formulae involving zeros of Bessel functions, which were first designed by Frappier and Olivier. Bessel quadratures correspond to the Fourier-Hankel integral transform. Some other examples, connected with the Jacobi integral transform, Fourier series in Jacobi orthogonal polynomials and the general Sturm-Liouville problem with regular weight are also given. Bibliography: 39 titles.

  3. Gauss and Markov quadrature formulae with nodes at zeros of eigenfunctions of a Sturm-Liouville problem, which are exact for entire functions of exponential type

    NASA Astrophysics Data System (ADS)

    Gorbachev, D. V.; Ivanov, V. I.

    2015-08-01

    Gauss and Markov quadrature formulae with nodes at zeros of eigenfunctions of a Sturm-Liouville problem, which are exact for entire functions of exponential type, are established. They generalize quadrature formulae involving zeros of Bessel functions, which were first designed by Frappier and Olivier. Bessel quadratures correspond to the Fourier-Hankel integral transform. Some other examples, connected with the Jacobi integral transform, Fourier series in Jacobi orthogonal polynomials and the general Sturm-Liouville problem with regular weight are also given. Bibliography: 39 titles.

  4. Exponentially growing bubbles around early supermassive black holes

    NASA Astrophysics Data System (ADS)

    Gilli, R.; Calura, F.; D'Ercole, A.; Norman, C.

    2017-07-01

    We address the as yet unexplored issue of outflows induced by exponentially growing power sources, focusing on early supermassive black holes (BHs). We assumed that these objects grow to 109M⊙ by z = 6 by Eddington-limited accretion and convert 5% of their bolometric output into a wind. We first considered the case of energy-driven and momentum-driven outflows expanding in a region where the gas and total mass densities are uniform and equal to the average values in the Universe at z> 6. We derived analytic solutions for the evolution of the outflow: for an exponentially growing power with e-folding time tSal, we find that the late time expansion of the outflow radius is also exponential, with e-folding time of 5tSal and 4tSal in the energy-driven and momentum-driven limit, respectively. We then considered energy-driven outflows produced by quasi-stellar objects (QSOs) at the centre of early dark matter halos of different masses and powered by BHs growing from different seeds. We followed the evolution of the source power and of the gas and dark matter density profiles in the halos from the beginning of the accretion until z = 6. The final bubble radius and velocity do not depend on the seed BH mass, but are instead smaller for larger halo masses. At z = 6, bubble radii in the range 50-180 kpc and velocities in the range 400-1000 km s-1 are expected for QSOs hosted by halos in the mass range 3 × 1011-1013M⊙. These radius and velocity scales compare well with those measured for the outflowing gas in the z = 6.4 QSO SDSS J1148+5251. By the time the QSO is observed, we found that the total thermal energy injected within the bubble in the case of an energy-driven outflow is Eth 5 × 1060 erg. This is in excellent agreement with the value of Eth = (6.2 ± 1.7) × 1060 erg measured through the detection of the thermal Sunyaev-Zeldovich effect around a large population of luminous QSOs at lower redshifts. This suggests that QSO outflows are closer to the energy

  5. Fast generic polar harmonic transforms.

    PubMed

    Hoang, Thai V; Tabbone, Salvatore

    2014-07-01

    Generic polar harmonic transforms have recently been proposed to extract rotation-invariant features from images and their usefulness has been demonstrated in a number of pattern recognition problems. However, direct computation of these transforms from their definition is inefficient and is usually slower than some efficient computation strategies that have been proposed for other methods. This paper presents a number of novel computation strategies to compute these transforms rapidly. The proposed methods are based on the inherent recurrence relations among complex exponential and trigonometric functions used in the definition of the radial and angular kernels of these transforms. The employment of these relations leads to recursive and addition chain-based strategies for fast computation of harmonic function-based kernels. Experimental results show that the proposed method is about 10× faster than direct computation and 5× faster than fast computation of Zernike moments using the q-recursive strategy. Thus, among all existing rotation-invariant feature extraction methods, polar harmonic transforms are the fastest.

  6. Triple transformation

    NASA Astrophysics Data System (ADS)

    Khan, Farrukh I.; Schinn, Dustin S.

    2013-08-01

    A new business plan that enables policy transformation and resource mobilization at the national and international level, while improving access to resources, will allow the Green Climate Fund to integrate development goals and action on climate change.

  7. The exponential eigenmodes of the carbon-climate system

    NASA Astrophysics Data System (ADS)

    Raupach, M. R.

    2012-09-01

    Several basic ratios describing the carbon-climate system are observed to adopt relatively steady values. Examples include the CO2 airborne fraction (the fraction of the total anthropogenic CO2 emission flux that accumulates in the atmosphere) and the ratio T/QE of warming (T) to cumulative total CO2 emissions (QE). This paper explores the reason for such near-constancy in the past, and its likely limitations in future. The contemporary carbon-climate system is often approximated as a first-order linear system, for example in response-function descriptions. All such linear systems have exponential eigenfunctions in time (an eigenfunction being one that, if applied to the system as a forcing, produces a response of the same shape). This implies that, if the carbon-climate system is idealised as a linear system (Lin) forced by exponentially growing CO2 emissions (Exp), then all ratios among fluxes and perturbation state variables are constant. Important cases are the CO2 airborne fraction (AF), the cumulative airborne fraction (CAF), other CO2 partition fractions and cumulative partition fractions into land and ocean stores, the CO2 sink uptake rate (kS, the combined land and ocean CO2 sink flux per unit excess atmospheric CO2), and the ratio T/QE. Further, the AF and the CAF are equal. The Lin and Exp idealisations apply approximately (but not exactly) to the carbon-climate system in the period from the start of industrialisation (nominally 1750) to the present, consistent with the observed near-constancy of the AF, CAF and T/QE in this period. A nonlinear carbon-climate model is used to explore how the likely future breakdown of both the Lin and Exp idealisations will cause the AF, CAF and kS to depart significantly from constancy, in ways that depend on CO2 emissions scenarios. However, T/QE remains approximately constant in typical scenarios, because of compensating interactions between emissions trajectories, carbon-cycle dynamics and non-CO2 gases. This theory

  8. Transformational leadership.

    PubMed

    Luzinski, Craig

    2011-12-01

    This month, the director of the Magnet Recognition Program® takes an in-depth look at the Magnet® model component transformational leadership. The author examines the expectations for Magnet organizations around this component. What are the qualities that make a nursing leader truly transformational, and what is the best approach to successfully lead a healthcare organization through today's volatile healthcare environment?

  9. [Investigation of the structure of magnesium and lithium salts of T2 phage DNA by the method of x-ray diffraction. The possible mechanisms of the participation of cations in the structural transformation of double-stranded DNA].

    PubMed

    Skuratovskii, I Ia; Bartenev, V N

    1978-01-01

    The secondary structure of DNA is known to be largely determined by the kind of counterion bound to it. We have used the X-ray diffraction method to study the structure of magnesium and lithium salts of T2 phage DNA in oriented fibres. The structural behaviour of this glucosylated DNA in the form of magnesium and lithium salts was shown to be identical to the behaviour of the same salts of "normal" calf thymus DNA throughout the studied range of relative humidities (44-95%). However these two DNAs in the form of sodium salt are known to behave quite differently. One can presume that Mg2+ and Li+ influence the structural behaviour of double-stranded DNA so effectively as to be able to "ignore" the fact that T2 phage DNA contains glucoside residues. The results of this work and the already known facts concerning the structure of DNA in the form of various cation salts (in solution and in "solid" fibres) indicate that the structural behaviour of double-stranded DNA is mainly determined by the cation located in the region of the narrow groove of the double helix. If cations are graded according to the efficiency of their influence on the structural behaviour of DNA in fibres, the scale will coincide with that of their DNA-binding strength in water solution, that is: Mg2+ greater than Li+ greater than Na+ greater than K+ greater than Rb+. A qualitative consideration of electrostatic interaction between the cations and the negatively charged DNA strands leads one to suppose that this interaction must obstruct the transition of individual DNA molecules from the B-form to the A-form. Aggregation of self-aggregation of DNA molecules is presumed necessary to enable them to adopt the A-conformation.

  10. YThe BigH3 Tumor Suppressor Gene in Radiation-Induced Malignant Transformation of Human Bronchial Epithelial Cells

    NASA Astrophysics Data System (ADS)

    Zhao, Y.; Shao, G.; Piao, C.; Hei, T.

    Carcinogenesis is a multi-stage process with sequences of genetic events governing the phenotypic expression of a series of transformation steps leading to the development of metastatic cancer Previous studies from this laboratory have identified a 7 fold down- regulation of the novel tumor suppressor Big-h3 among radiation induced tumorigenic BEP2D cells Furthermore ectopic re-expression of this gene suppresses tumorigenic phenotype and promotes the sensitivity of these tumor cells to etoposide-induced apoptosis To extend these studies using a genomically more stable bronchial cell line we ectopically expresses the catalytic subunit of telomerase hTERT in primary human small airway epithelial SAE cells and generated several clonal cell lines that have been continuously in culture for more than 250 population doublings and are considered immortal Comparably-treated control SAE cells infected with only the viral vector senesced after less than 10 population doublings The immortalized clones demonstrated anchorage dependent growth and are non-tumorigenic in nude mice These cells show no alteration in the p53 gene but a decrease in p16 expression Exponentially growing SAEh cells were exposed to graded doses of 1 GeV nucleon of 56 Fe ions accelerated at the Brookhaven National Laboratory Irradiated cells underwent gradual phenotypic alterations after extensive in vitro cultivation Transformed cells developed through a series of successive steps before becoming anchorage independent in semisolid medium These findings indicate

  11. Double inflation

    SciTech Connect

    Silk, J.; Turner, M.S.

    1986-04-01

    The Zel'dovich spectrum of adiabatic density perturbations is a generic prediction of inflation. There is increasing evidence that when the spectrum is normalized by observational data on small scales, there is not enough power on large scales to account for the observed large-scale structure in the Universe. Decoupling the spectrum on large and small scales could solve this problem. As a means of decoupling the large and small scales we propose double inflation (i.e., two episodes of inflation). In this scenario the spectrum on large scales is determined by the first episode of inflation and those on small scales by a second episode of inflation. We present three models for such a scenario. By nearly saturating the large angular-scale cosmic microwave anisotropy bound, we can easily account for the observed large-scale structure. We take the perturbations on small scales to be very large, deltarho/rho approx. = 0.1 to 0.01, which results in the production of primordial black holes (PBHs), early formation of structure, reionization of the Universe, and a rich array of astrophysical events. The ..cap omega..-problem is also addressed by our scenario. Allowing the density perturbations produced by the second episode of inflation to be large also lessens the fine-tuning required in the scalar potential and makes reheating much easier. We briefly speculate on the possibility that the second episode of inflation proceeds through the nucleation of bubbles, which today manifest themselves as empty bubbles whose surfaces are covered with galaxies. 37 refs., 1 fig.

  12. Seeing Double

    NASA Astrophysics Data System (ADS)

    Pesic, Peter

    2003-10-01

    The separateness and connection of individuals is perhaps the central question of human life: What, exactly, is my individuality? To what degree is it unique? To what degree can it be shared, and how? To the many philosophical and literary speculations about these topics over time, modern science has added the curious twist of quantum theory, which requires that the elementary particles of which everything consists have no individuality at all. All aspects of chemistry depend on this lack of individuality, as do many branches of physics. From where, then, does our individuality come? In Seeing Double, Peter Pesic invites readers to explore this intriguing set of questions. He draws on literary and historical examples that open the mind (from Homer to Martin Guerre to Kafka), philosophical analyses that have helped to make our thinking and speech more precise, and scientific work that has enabled us to characterize the phenomena of nature. Though he does not try to be all-inclusive, Pesic presents a broad range of ideas, building toward a specific point of view: that the crux of modern quantum theory is its clash with our ordinary concept of individuality. This represents a departure from the usual understanding of quantum theory. Pesic argues that what is bizarre about quantum theory becomes more intelligible as we reconsider what we mean by individuality and identity in ordinary experience. In turn, quantum identity opens a new perspective on us. Peter Pesic is a Tutor and Musician-in-Residence at St. John's College, Santa Fe, New Mexico. He has a Ph.D. in physics from Stanford University.

  13. An Exponential Luminous Efficiency Model for Hypervelocity Impact into Regolith

    NASA Technical Reports Server (NTRS)

    Swift, W. R.; Moser, D. E.; Suggs, R. M.; Cooke, W. J.

    2011-01-01

    The flash of thermal radiation produced as part of the impact-crater forming process can be used to determine the energy of the impact if the luminous efficiency is known. From this energy the mass and, ultimately, the mass flux of similar impactors can be deduced. The luminous efficiency, eta, is a unique function of velocity with an extremely large variation in the laboratory range of under 6 km/s but a necessarily small variation with velocity in the meteoric range of 20 to 70 km/s. Impacts into granular or powdery regolith, such as that on the moon, differ from impacts into solid materials in that the energy is deposited via a serial impact process which affects the rate of deposition of internal (thermal) energy. An exponential model of the process is developed which differs from the usual polynomial models of crater formation. The model is valid for the early time portion of the process and focuses on the deposition of internal energy into the regolith. The model is successfully compared with experimental luminous efficiency data from both laboratory impacts and from lunar impact observations. Further work is proposed to clarify the effects of mass and density upon the luminous efficiency scaling factors. Keywords hypervelocity impact impact flash luminous efficiency lunar impact meteoroid 1

  14. An Exponential Luminous Efficiency Model for Hypervelocity Impact into Regolith

    NASA Technical Reports Server (NTRS)

    Swift, Wesley R.; Moser, D.E.; Suggs, Robb M.; Cooke, W.J.

    2010-01-01

    The flash of thermal radiation produced as part of the impact-crater forming process can be used to determine the energy of the impact if the luminous efficiency is known. From this energy the mass and, ultimately, the mass flux of similar impactors can be deduced. The luminous efficiency, Eta is a unique function of velocity with an extremely large variation in the laboratory range of under 8 km/s but a necessarily small variation with velocity in the meteoric range of 20 to 70 km/s. Impacts into granular or powdery regolith, such as that on the moon, differ from impacts into solid materials in that the energy is deposited via a serial impact process which affects the rate of deposition of internal (thermal) energy. An exponential model of the process is developed which differs from the usual polynomial models of crater formation. The model is valid for the early time portion of the process and focuses on the deposition of internal energy into the regolith. The model is successfully compared with experimental luminous efficiency data from laboratory impacts and from astronomical determinations and scaling factors are estimated. Further work is proposed to clarify the effects of mass and density upon the luminous efficiency scaling factors

  15. Multivariate Exponential Survival Trees And Their Application to Tooth Prognosis

    PubMed Central

    Fan, Juanjuan; Nunn, Martha E.; Su, Xiaogang

    2009-01-01

    SUMMARY This paper is concerned with developing rules for assignment of tooth prognosis based on actual tooth loss in the VA Dental Longitudinal Study. It is also of interest to rank the relative importance of various clinical factors for tooth loss. A multivariate survival tree procedure is proposed. The procedure is built on a parametric exponential frailty model, which leads to greater computational efficiency. We adopted the goodness-of-split pruning algorithm of LeBlanc and Crowley (1993) to determine the best tree size. In addition, the variable importance method is extended to trees grown by goodness-of-fit using an algorithm similar to the random forest procedure in Breiman (2001). Simulation studies for assessing the proposed tree and variable importance methods are presented. To limit the final number of meaningful prognostic groups, an amalgamation algorithm is employed to merge terminal nodes that are homogenous in tooth survival. The resulting prognosis rules and variable importance rankings seem to offer simple yet clear and insightful interpretations. PMID:21709804

  16. Exponential fading to white of black holes in quantum gravity

    NASA Astrophysics Data System (ADS)

    Barceló, Carlos; Carballo-Rubio, Raúl; Garay, Luis J.

    2017-05-01

    Quantization of the gravitational field may allow the existence of a decay channel of black holes into white holes with an explicit time-reversal symmetry. The definition of a meaningful decay probability for this channel is studied in spherically symmetric situations. As a first nontrivial calculation, we present the functional integration over a set of geometries using a single-variable function to interpolate between black-hole and white-hole geometries in a bounded region of spacetime. This computation gives a finite result which depends only on the Schwarzschild mass and a parameter measuring the width of the interpolating region. The associated probability distribution displays an exponential decay law on the latter parameter, with a mean lifetime inversely proportional to the Schwarzschild mass. In physical terms this would imply that matter collapsing to a black hole from a finite radius bounces back elastically and instantaneously, with negligible time delay as measured by external observers. These results invite to reconsider the ultimate nature of astrophysical black holes, providing a possible mechanism for the formation of black stars instead of proper general relativistic black holes. The existence of both this decay channel and black stars can be tested in future observations of gravitational waves.

  17. Exponential 6 parameterization for the JCZ3-EOS

    SciTech Connect

    McGee, B.C.; Hobbs, M.L.; Baer, M.R.

    1998-07-01

    A database has been created for use with the Jacobs-Cowperthwaite-Zwisler-3 equation-of-state (JCZ3-EOS) to determine thermochemical equilibrium for detonation and expansion states of energetic materials. The JCZ3-EOS uses the exponential 6 intermolecular potential function to describe interactions between molecules. All product species are characterized by r*, the radius of the minimum pair potential energy, and {var_epsilon}/k, the well depth energy normalized by Boltzmann`s constant. These parameters constitute the JCZS (S for Sandia) EOS database describing 750 gases (including all the gases in the JANNAF tables), and have been obtained by using Lennard-Jones potential parameters, a corresponding states theory, pure liquid shock Hugoniot data, and fit values using an empirical EOS. This database can be used with the CHEETAH 1.40 or CHEETAH 2.0 interface to the TIGER computer program that predicts the equilibrium state of gas- and condensed-phase product species. The large JCZS-EOS database permits intermolecular potential based equilibrium calculations of energetic materials with complex elemental composition.

  18. On the role of exponential smoothing in circadian dosimetry.

    PubMed

    Price, Luke L A

    2014-01-01

    The effects lighting has on health through modulation of circadian rhythms are becoming increasingly well documented. Data are still needed to show how light exposures are influenced by architecture and lighting design and circadian dosimetry analyses should provide duration, phase and amplitude measures of 24 h exposure profiles. Exponential smoothing is used to derive suitable metrics from 24 h light measurements collected from private dwellings. A further application of these modified exposure time series as physiological models of the light drive is discussed. Unlike previous light drive models, the dose rate persists into periods of darkness following exposures. Comparisons to long duration exposure studies suggest this type of persistent light drive model could be incorporated into contemporary physiological models of the human circadian oscillator. © 2014 Crown copyright. Photochemistry and Photobiology © 2014 The American Society of Photobiology. This article is published with the permission of the Controller of HMSO and the Queen's Printer for Scotland and Public Health England.

  19. Exponential flux-controlled memristor model and its floating emulator

    NASA Astrophysics Data System (ADS)

    Liu, Wei; Wang, Fa-Qiang; Ma, Xi-Kui

    2015-11-01

    As commercial memristors are still unavailable in the market, mathematic models and emulators which can imitate the features of the memristor are meaningful for further research. In this paper, based on the analyses of characteristics of the q-φ curve, an exponential flux-controlled model, which has the quality that its memductance (memristance) will keep monotonically increasing or decreasing unless the voltage’s polarity reverses (if not approach the boundaries), is constructed. A new approach to designing the floating emulator of the memristor is also proposed. This floating structure can flexibly meet various demands for the current through the memristor (especially the demand for a larger current). The simulations and experiments are presented to confirm the effectiveness of this model and its floating emulator. Project supported by the National Natural Science Foundation of China (Grant Nos. 51377124 and 51221005), the Foundation for the Author of National Excellent Doctoral Dissertation of China (Grant No. 201337), the Program for New Century Excellent Talents in University of China (Grant No. NCET-13-0457), and the Natural Science Basic Research Plan in Shaanxi Province of China (Grant No. 2012JQ7026).

  20. Predictors of the peak width for networks with exponential links

    USGS Publications Warehouse

    Troutman, B.M.; Karlinger, M.R.

    1989-01-01

    We investigate optimal predictors of the peak (S) and distance to peak (T) of the width function of drainage networks under the assumption that the networks are topologically random with independent and exponentially distributed link lengths. Analytical results are derived using the fact that, under these assumptions, the width function is a homogeneous Markov birth-death process. In particular, exact expressions are derived for the asymptotic conditional expectations of S and T given network magnitude N and given mainstream length H. In addition, a simulation study is performed to examine various predictors of S and T, including N, H, and basin morphometric properties; non-asymptotic conditional expectations and variances are estimated. The best single predictor of S is N, of T is H, and of the scaled peak (S divided by the area under the width function) is H. Finally, expressions tested on a set of drainage basins from the state of Wyoming perform reasonably well in predicting S and T despite probable violations of the original assumptions. ?? 1989 Springer-Verlag.

  1. A comparison of the generalized gamma and exponentiated Weibull distributions.

    PubMed

    Cox, Christopher; Matheson, Matthew

    2014-09-20

    This paper provides a comparison of the three-parameter exponentiated Weibull (EW) and generalized gamma (GG) distributions. The connection between these two different families is that the hazard functions of both have the four standard shapes (increasing, decreasing, bathtub, and arc shaped), and in fact, the shape of the hazard is the same for identical values of the three parameters. For a given EW distribution, we define a matching GG using simulation and also by matching the 5 (th) , 50 (th) , and 95 (th) percentiles. We compare EW and matching GG distributions graphically and using the Kullback-Leibler distance. We find that the survival functions for the EW and matching GG are graphically indistinguishable, and only the hazard functions can sometimes be seen to be slightly different. The Kullback-Leibler distances are very small and decrease with increasing sample size. We conclude that the similarity between the two distributions is striking, and therefore, the EW represents a convenient alternative to the GG with the identical richness of hazard behavior. More importantly, these results suggest that having the four basic hazard shapes may to some extent be an important structural characteristic of any family of distributions. Copyright © 2014 John Wiley & Sons, Ltd.

  2. Mutant number distribution in an exponentially growing population

    NASA Astrophysics Data System (ADS)

    Keller, Peter; Antal, Tibor

    2015-01-01

    We present an explicit solution to a classic model of cell-population growth introduced by Luria and Delbrück (1943 Genetics 28 491-511) 70 years ago to study the emergence of mutations in bacterial populations. In this model a wild-type population is assumed to grow exponentially in a deterministic fashion. Proportional to the wild-type population size, mutants arrive randomly and initiate new sub-populations of mutants that grow stochastically according to a supercritical birth and death process. We give an exact expression for the generating function of the total number of mutants at a given wild-type population size. We present a simple expression for the probability of finding no mutants, and a recursion formula for the probability of finding a given number of mutants. In the ‘large population-small mutation’ limit we recover recent results of Kessler and Levine (2014 J. Stat. Phys. doi:10.1007/s10955-014-1143-3) for a fully stochastic version of the process.

  3. Osmotic significance of glycerol accumulation in exponentially growing yeasts.

    PubMed Central

    Reed, R H; Chudek, J A; Foster, R; Gadd, G M

    1987-01-01

    Natural-abundance 13C-nuclear magnetic resonance spectroscopy has shown glycerol to be the major osmotically significant low-molecular-weight solute in exponentially growing, salt-stressed cells of the yeasts Saccharomyces cerevisiae, Zygosaccharomyces rouxii, and Debaromyces hansenii. Measurement of the intracellular nonosmotic volume (i.e., the fraction of the cell that is osmotically unresponsive) by using the Boyle-van't Hoff relationship (for nonturgid cells, the osmotic volume is directly proportional to the reciprocal of the external osmotic pressure) showed that the nonosmotic volume represented up to 53% of the total cell volume; the highest values were recorded in media with maximum added NaCl. Determinations of intracellular glycerol levels with respect to cell osmotic volumes showed that increases in intracellular glycerol may counterbalance up to 95% of the external osmotic pressure due to added NaCl. The lack of other organic osmotica in 13C-nuclear magnetic resonance spectra indicates that inorganic ions may constitute the remaining component of intracellular osmotic pressure. PMID:3314706

  4. Absence of exponential clustering in quantum Coulomb fluids

    NASA Astrophysics Data System (ADS)

    Alastuey, A.; Martin, Ph. A.

    1989-12-01

    We show that the quantum corrections to the classical correlations of a Coulomb fluid do not decay exponentially fast for all values of the thermodynamical parameters. Specifically, the ħ4 term in the Wigner-Kirkwood expansion of the equilibrium charge-charge correlations of the quantum one-component plasma is found to decay like ||r||-10. More generally, using functional integration, we present a diagrammatic representation of the ħ expansion of the correlations in a multicomponent fluid with a locally regularized Coulomb potential and Maxwell-Boltzmann statistics. The ħ2n terms are found to decay algebraically for all n>=2. Furthermore, an analysis of the hierarchy equations for the correlations provides upper bounds that are compatible with the findings of the perturbative expansion. Except for the monopole, all higher-order multipole sum rules do not hold, in general, in the quantum system. This violation of the multipole sum rules as well as the related algebraic tails are due to the intrinsic quantum fluctuations that prevent a perfect organization of the screening clouds. This phenomenon is illustrated in a simpler model where the large-distance correlations between two quantum particles embedded in a classical plasma can be exactly computed.

  5. Exponential repulsion improves structural predictability of molecular docking.

    PubMed

    Bazgier, Václav; Berka, Karel; Otyepka, Michal; Banáš, Pavel

    2016-10-30

    Molecular docking is a powerful tool for theoretical prediction of the preferred conformation and orientation of small molecules within protein active sites. The obtained poses can be used for estimation of binding energies, which indicate the inhibition effect of designed inhibitors, and therefore might be used for in silico drug design. However, the evaluation of ligand binding affinity critically depends on successful prediction of the native binding mode. Contemporary docking methods are often based on scoring functions derived from molecular mechanical potentials. In such potentials, nonbonded interactions are typically represented by electrostatic interactions between atom-centered partial charges and standard 6-12 Lennard-Jones potential. Here, we present implementation and testing of a scoring function based on more physically justified exponential repulsion instead of the standard Lennard-Jones potential. We found that this scoring function significantly improved prediction of the native binding modes in proteins bearing narrow active sites such as serine proteases and kinases. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  6. Analysis of preloaded bolted joints under exponentially decaying pressure

    SciTech Connect

    Esmailzadeh, E.; Chorashi, M.; Ohadi, A.R.

    1996-11-01

    Dynamic properties of joints must be considered when designing complex structures. A good deal of investigation has been carried out for a better understanding of the dynamic behavior of mechanical joints. It is suitable initially to identify the parameters of a mechanical joint by using either experimental modal analysis or accurate finite element model, and then predicating the behavior of closure bolting system by means of spring-mass-damper model. The effect of bolt prestress on the maximum bolt displacement and stress has been treated. The loading is assumed to be initially peaked, exponentially decaying internal pressure pulse acting on the closure. The dependence of peak bolt stresses and deflections on the bolt prestress level and system damping is investigated. It has been shown that the derived formulas, if damping is neglected, reduce to those reported in the literature. Furthermore, the damping effect is shown to be most important, especially for large natural frequencies, longer loading duration, and lower levels of prestress. Existence of damping, which results in the reduction of maximum bolt displacement and stress, was shown to be beneficial, especially for longer loading duration. The importance of bolt displacement reduction from the viewpoint of fatigue life, vibration loosening, and sealing, especially for lower values of prestress, has been fully emphasized.

  7. Nonstationary multistate Coulomb and multistate exponential models for nonadiabatic transitions

    SciTech Connect

    Ostrovsky, V. N.

    2003-07-01

    The nonstationary Schroedinger equation is considered in a finite basis of states. The model Hamiltonian matrix corresponds to a single diabatic potential curve with a Coulombic {approx}1/t time dependence. An arbitrary number of other diabatic potential curves are flat, i.e., time independent and have arbitrary energies. Related states are coupled by constant interactions with the Coulomb state. The resulting nonstationary Schroedinger equation is solved by the method of contour integral. Probabilities of transitions to any other state are obtained as t{yields}{infinity} in a simple analytical form for the case when the Coulomb state is populated initially (at instant of time t{yields}+0). The formulas apply both to the cases when a horizontal diabatic potential curve is crossed by the Coulomb one and to a noncrossing situation. In the limit of weak coupling, the transition probabilities are interpreted in terms of a sequence of pairwise Landau-Zener-type transitions. Mapping of the Coulomb model onto an exactly solvable exponential multistate model is established. For the special two-state case, the well-known Nikitin model is recovered.

  8. Double Your Major, Double Your Return?

    ERIC Educational Resources Information Center

    Del Rossi, Alison F.; Hersch, Joni

    2008-01-01

    We use the 2003 National Survey of College Graduates to provide the first estimates of the effect on earnings of having a double major. Overall, double majoring increases earnings by 2.3% relative to having a single major among college graduates without graduate degrees. Most of the gains from having a double major come from choosing fields across…

  9. Irreducibility and Exponential Mixing of Some Stochastic Hydrodynamical Systems Driven by Pure Jump Noise

    NASA Astrophysics Data System (ADS)

    Fernando, Pani W.; Hausenblas, E.; Razafimandimby, Paul A.

    2016-12-01

    In this paper, we derive several results related to the long-time behavior of a class of stochastic semilinear evolution equations in a separable Hilbert space H: du(t) +[Au(t)+B(u(t),u(t))] dt = dL(t), quad{u}(0)=xin H. Here A is a positive self-adjoint operator and B is a bilinear map, and the driving noise L is basically a {D(A^{-1/2})} -valued lévy process satisfying several technical assumptions. By using a density transformation theorem type for lévy measure, we first prove a support theorem and an irreducibility property of the Ornstein-Uhlenbeck processes associated to the nonlinear stochastic problem. Second, by exploiting the previous results we establish the irreducibility of the nonlinear problem provided that for a certain {γ in [0,1/4]} B is continuous on {D(A^γ)× D(A^γ)} with values in {D(A^ {-1/2})}. Using a coupling argument, the exponential ergodicity is also proved under the stronger assumption that B is continuous on {H ×H}. While the latter condition is only satisfied by the nonlinearities of GOY and Sabra shell models, the assumption under which the irreducibility property holds is verified by several hydrodynamical systems such as the 2D Navier-Stokes, Magnetohydrodynamics equations, the 3D Leray-{{\\varvec{α}}} model, the GOY and Sabra shell models.

  10. Semiclassical theory of nonadiabatic transitions in a two-state exponential model

    NASA Astrophysics Data System (ADS)

    Osherov, Vladimir I.; Ushakov, Vladimir G.; Nakamura, Hiroki

    1998-04-01

    A general two-state exponential potential model is solved with use of the Bessel transformation and the WKB (Wentzel-Kramers-Brillouin) type semiclassical approximation. Accurate expressions are obtained for the nonadiabatic transition probability for one passage of the transition point and for the two dynamical phases. Functionalities of these quantities in terms of two basic parameters are the same as those obtained before by Nikitin. The two basic parameters are, however, expressed in more general and accurate forms. Accuracies of these expressions are numerically confirmed. The three quantities, the nonadiabatic transition probability and the two dynamical phases, constitute the nonadiabatic transition matrix and can be used to describe various (spectroscopic as well as scattering) processes not only for a two-state but also for a multichannel system. A possible generalization of the present theory is also briefly discussed to formulate a unified theory that can cover both Landau-Zener-Stueckelberg and Rosen-Zener-Demkov cases within the adiabatic state representation.

  11. Chemical reaction and radiation effects on MHD flow past an exponentially stretching sheet with heat sink

    NASA Astrophysics Data System (ADS)

    Nur Wahida Khalili, Noran; Aziz Samson, Abdul; Aziz, Ahmad Sukri Abdul; Ali, Zaileha Md

    2017-09-01

    In this study, the problem of MHD boundary layer flow past an exponentially stretching sheet with chemical reaction and radiation effects with heat sink is studied. The governing system of PDEs is transformed into a system of ODEs. Then, the system is solved numerically by using Runge-Kutta-Fehlberg fourth fifth order (RKF45) method available in MAPLE 15 software. The numerical results obtained are presented graphically for the velocity, temperature and concentration. The effects of various parameters are studied and analyzed. The numerical values for local Nusselt number, skin friction coefficient and local Sherwood number are tabulated and discussed. The study shows that various parameters give significant effect on the profiles of the fluid flow. It is observed that the reaction rate parameter affected the concentration profiles significantly and the concentration thickness of boundary layer decreases when reaction rate parameter increases. The analysis found is validated by comparing with the results previous work done and it is found to be in good agreement.

  12. /q-exponential, Weibull, and /q-Weibull distributions: an empirical analysis

    NASA Astrophysics Data System (ADS)

    Picoli, S.; Mendes, R. S.; Malacarne, L. C.

    2003-06-01

    In a comparative study, the q-exponential and Weibull distributions are employed to investigate frequency distributions of basketball baskets, cyclone victims, brand-name drugs by retail sales, and highway length. In order to analyze the intermediate cases, a distribution, the q-Weibull one, which interpolates the q-exponential and Weibull ones, is introduced. It is verified that the basketball baskets distribution is well described by a q-exponential, whereas the cyclone victims and brand-name drugs by retail sales ones are better adjusted by a Weibull distribution. On the other hand, for highway length the q-exponential and Weibull distributions do not give satisfactory adjustment, being necessary to employ the q-Weibull distribution. Furthermore, the introduction of this interpolating distribution gives an illumination from the point of view of the stretched exponential against inverse power law ( q-exponential with q>1) controversy.

  13. Exponential model normalization for electrical capacitance tomography with external electrodes under gap permittivity conditions

    NASA Astrophysics Data System (ADS)

    Baidillah, Marlin R.; Takei, Masahiro

    2017-06-01

    A nonlinear normalization model which is called exponential model for electrical capacitance tomography (ECT) with external electrodes under gap permittivity conditions has been developed. The exponential model normalization is proposed based on the inherently nonlinear relationship characteristic between the mixture permittivity and the measured capacitance due to the gap permittivity of inner wall. The parameters of exponential equation are derived by using an exponential fitting curve based on the simulation and a scaling function is added to adjust the experiment system condition. The exponential model normalization was applied to two dimensional low and high contrast dielectric distribution phantoms by using simulation and experimental studies. The proposed normalization model has been compared with other normalization models i.e. Parallel, Series, Maxwell and Böttcher models. Based on the comparison of image reconstruction results, the exponential model is reliable to predict the nonlinear normalization of measured capacitance in term of low and high contrast dielectric distribution.

  14. TRANSFORMATION OF BACILLUS LICHENIFORMIS1

    PubMed Central

    Gwinn, Darrel D.; Thorne, Curtis B.

    1964-01-01

    Gwinn, Darrel D. (Oregon State University, Corvallis), and Curtis B. Thorne. Transformation of Bacillus licheniformis. J. Bacteriol. 87:519–526. 1964.—When a series of 28 auxotrophic mutants of Bacillus licheniformis were screened for transformation, only three of them, M28 (glycine−), M30 (uncharacterized), and M33 (purine−), produced a detectable number of transformants. The screening method consisted of spreading auxotrophic cells and deoxyribonucleic acid (DNA) from the prototrophic strain 9945A on minimal agar plates and observing the plates for development of prototrophic colonies. M28 transformed at a higher frequency than did the two other mutants, and it was studied in greater detail. Although up to 20% of the recipient cells spread on the plates in the presence of DNA gave rise to prototrophic colonies over a period of 72 hr, only about 10−3% of the cells produced transformants when they were incubated with DNA in liquid suspension for 1 hr. The most competent cultures of many tested were those grown on a shaker for 22 hr in a medium composed of nutrient broth, salts, and glycerol. When mutations resulting in requirements for histidine, leucine, serine, and trytophan were introduced singly into the glycine mutant, transformants for the leucine, serine, and histidine markers could be obtained at will, but transformants for the tryptophan marker were not detected even though all four of the double mutants could be transformed to glycine independence. PMID:14127566

  15. Improved exponential convergence result for generalized neural networks including interval time-varying delayed signals.

    PubMed

    Rajchakit, G; Saravanakumar, R; Ahn, Choon Ki; Karimi, Hamid Reza

    2017-02-01

    This article examines the exponential stability analysis problem of generalized neural networks (GNNs) including interval time-varying delayed states. A new improved exponential stability criterion is presented by establishing a proper Lyapunov-Krasovskii functional (LKF) and employing new analysis theory. The improved reciprocally convex combination (RCC) and weighted integral inequality (WII) techniques are utilized to obtain new sufficient conditions to ascertain the exponential stability result of such delayed GNNs. The superiority of the obtained results is clearly demonstrated by numerical examples.

  16. Exponential stability of linear discrete systems with nonconstant matrices and nonconstant delay

    NASA Astrophysics Data System (ADS)

    Diblík, Josef

    2017-07-01

    The paper studies the exponential stability and exponential estimation of solutions to linear discrete systems with delay x (k +1 )=A (k )x (k )+B (k )x (k -m (k )), k =0 ,1 ,… where x is an n-dimensional dependent variable, A(k) and B(k) are n×n real matrices, and m(k) ∈ ℕ. Using the method of Lyapunov functions, conditions are derived for exponential stability.

  17. Rapid and ultrasensitive detection of microRNA by target-assisted isothermal exponential amplification coupled with poly (thymine)-templated fluorescent copper nanoparticles

    NASA Astrophysics Data System (ADS)

    Park, Kwan Woo; Batule, Bhagwan S.; Kang, Kyoung Suk; Park, Ki Soo; Park, Hyun Gyu

    2016-10-01

    We devised a novel method for rapid and ultrasensitive detection of target microRNA (miRNA) by employing target-assisted isothermal exponential amplification (TAIEA) combined with poly (thymine)-templated fluorescent copper nanoparticles (CuNPs) as signaling probes. The target miRNA hybridizes to the unimolecular template DNA and works as a primer for the extension reaction to form double-stranded product, which consequently generates two nicking endonuclease recognition sites. By simultaneous nicking and displacement reactions, exponential amplification generates many poly (thymine) strands as final products, which are employed for the synthesis of fluorescent CuNPs. Based on the fluorescent signal from CuNPs, target miRNA is detected as low as 0.27 fM around 1 h of total analysis time. The diagnostic capability of this system has been successfully demonstrated by reliably detecting target miRNA from different cell lysates, showing its great potential towards real clinical applications.

  18. Psychoanalytic transformations.

    PubMed

    Riolo, Fernando

    2007-12-01

    The author describes how Bion took Freud's conception of dreams as a form of thought and used it as the basis of his theory of transformations. Bion developed an expanded theory of 'dream thought', understood as a process of selection and transformation of sensory and emotional experiences. In this theory, the work of analysis is in turn conceived as a process not only of deciphering symbols, of revealing already existing unconscious meanings, but also of symbol production--of a process for generating thoughts and conferring meaning on experiences that have never been conscious and never been repressed because they have never been 'thought'. Analysis, in its specific operational sense, becomes a system of transformation whereby unconscious somatopsychic processes acquire the conditions for representability and become capable of translation into thoughts, words and interpretations. The rules of transformation applied by the patient in his representations and those applied by the analyst in his interpretations have the same importance for the analytic process as those described by Freud for the process of dreaming. The author discusses the broad categories of transformation adduced by Bion (rigid motion, projective, and in hallucinosis) and introduces some further distinctions within them.

  19. New Nonequilibrium-to-Equilibrium Dynamical Scaling and Stretched-Exponential Critical Relaxation in Cluster Algorithms

    NASA Astrophysics Data System (ADS)

    Nonomura, Yoshihiko

    2014-11-01

    Nonequilibrium relaxation behaviors in the Ising model on a square lattice based on the Wolff algorithm are totally different from those based on local-update algorithms. In particular, the critical relaxation is described by the stretched-exponential decay. We propose a novel scaling procedure to connect nonequilibrium and equilibrium behaviors continuously, and find that the stretched-exponential scaling region in the Wolff algorithm is as wide as the power-law scaling region in local-update algorithms. We also find that relaxation to the spontaneous magnetization in the ordered phase is characterized by the exponential decay, not the stretched-exponential decay based on local-update algorithms.

  20. Coupled-cluster singles and doubles for extended systems

    NASA Astrophysics Data System (ADS)

    Hirata, So; Podeszwa, Rafał; Tobita, Motoi; Bartlett, Rodney J.

    2004-02-01

    Coupled-cluster theory with connected single and double excitation operators (CCSD) and related approximations, such as linearized CCSD, quadratic configuration interaction with single and double excitation operators, coupled-cluster with connected double excitation operator (CCD), linearized CCD, approximate CCD, and second- and third-order many-body perturbation theories, are formulated and implemented for infinitely extended one-dimensional systems (polymers), on the basis of the periodic boundary conditions and distance-based screening of integrals, density matrix elements, and excitation amplitudes. The variation of correlation energies with the truncation radii of short- and long-range lattice sums and with the number of wave vector sampling points in the first Brillouin zone is examined for polyethylene, polyacetylene, and polyyne, and is shown to be a function of the degree of π-electron conjugation or the fundamental band gaps. The t2 and t1 amplitudes in the atomic orbital (AO) basis are obtained by first computing the t amplitudes in the Bloch-orbital basis and subsequently back-transforming them into the AO basis. The plot of these AO-based t amplitudes as a function of unit cells also indicates that the t2 amplitudes of polyacetylene and polyyne exhibit appreciably slower decay than those of polyethylene, although the asymptotic decay behavior is invariably 1/r3. The AO-based t1 amplitudes appear to correlate strongly with the electronic structure, and they decay seemingly exponentially for polyethylene whereas they stay at a constant magnitude across the seventh nearest neighbors of polyacetylene and polyyne, which attests to far reaching effects of nondynamical electron correlation mediated by orbital rotation. Nonetheless, the unit cell contributions to the correlation energies taper below 10-6 hartree after 15 Å for all three polymers. The basis set dependence of the decay behavior of t2 amplitudes is also examined for linear hydrogen fluoride

  1. Establishment and transformation of telomerase-immortalized human small airway epithelial cells by heavy ions

    NASA Astrophysics Data System (ADS)

    Zhao, Y. L.; Piao, C. Q.; Hei, T. K.

    Previous studies from this laboratory have identified a number of causally linked genes including the novel tumor suppressor Betaig-h3 that were differentially expressed in radiation induced tumorigenic BEP2D cells. To extend these studies using a genomically more stable bronchial cell line, we show here that ectopic expression of the catalytic subunit of telomerase (hTERT) in primary human small airway epithelial (SAE) cells resulted in the generation of several clonal cell lines that have been continuously in culture for more than 250 population doublings and are considered immortal. Comparably-treated control SAE cells infected with only the viral vector senesced after less than 10 population doublings. The immortalized clones demonstrated anchorage dependent growth and are non-tumorigenic in nude mice. These cells show no alteration in the p53 gene but a decrease in p16 expression. Exponentially growing SAEh cells were exposed to graded doses of 1 GeV/nucleon of 56Fe ions accelerated at the Brookhaven National Laboratory. Irradiated cells underwent gradual phenotypic alterations after extensive in vitro cultivation. Transformed cells developed through a series of successive steps before becoming anchorage independent in semisolid medium. These findings indicate that hTERT-immortalized cells, being diploid and chromosomal stable, should be a useful model in assessing mechanism of radiation carcinogenesis.

  2. Crystal chemistry of a Ba-dominant analogue of hydrodelhayelite and natural ion-exchange transformations in double- and triple-layer phyllosilicates in post-volcanic systems of the Eifel region, Germany

    NASA Astrophysics Data System (ADS)

    Zubkova, N. V.; Chukanov, N. V.; Pekov, I. V.; Turchkova, A. G.; Lykova, I. S.; Schüller, W.; Ternes, B.; Pushcharovsky, D. Yu.

    2016-12-01

    A Ba-dominant (Ba > K) analogue of hydrodelhayelite (BDAH) from Löhley (Eifel Mts., Rhineland-Palatinate, Germany) and Ba-enriched varieties of related double- and triple-layer phyllosilicates from Eifel are studied. The crystal structure of BDAH was solved by direct methods and refined to R = 0.0698 [1483 unique reflections with I > 2σ( I)]. It is orthorhombic, Pmmn, a = 23.9532(9), b = 7.0522(3), c = 6.6064(3) Å, V = 1115.97(8) Å3, Z = 2. The structure is based upon delhayelite-type double-layer tetrahedral blocks [(Al,Si)4Si12O34(OH,O)4] connected by chains of (Ca,Fe)-centered octahedra. Ba2+ and subordinate K+ occur at partially vacant sites in zeolitic channels within the tetrahedral blocks. The crystal-chemical formula of BDAH is: (Ba0.42K0.34□0.24)(Ca0.88Fe0.12)2(□0.90Mg0.10)2[Si6(Al0.5Si0.5)2O17(OH0.71O0.29)2]ṡ6H2O. The formation of BDAH and Ba-rich varieties of altered delhayelite/fivegite, günterblassite and hillesheimite is considered as a result of leaching of Na, Cl, F and, partially, K and Ca accompanied with hydration and the capture of Ba as a result of natural ion exchange. These minerals are structurally a "bridge" between single-layer phyllosilicates and zeolites having the open three-dimensional tetrahedral Al-Si-O frameworks.

  3. EXPONENTIAL TIME DIFFERENCING FOR HODGKIN-HUXLEY-LIKE ODES.

    PubMed

    Börgers, Christoph; Nectow, Alexander R

    2013-01-01

    Several authors have proposed the use of exponential time differencing (ETD) for Hodgkin-Huxley-like partial and ordinary differential equations (PDEs and ODEs). For Hodgkin-Huxley-like PDEs, ETD is attractive because it can deal effectively with the stiffness issues that diffusion gives rise to. However, large neuronal networks are often simulated assuming "space-clamped" neurons, i.e., using the Hodgkin-Huxley ODEs, in which there are no diffusion terms. Our goal is to clarify whether ETD is a good idea even in that case. We present a numerical comparison of first- and second-order ETD with standard explicit time-stepping schemes (Euler's method, the midpoint method, and the classical fourth-order Runge-Kutta method). We find that in the standard schemes, the stable computation of the very rapid rising phase of the action potential often forces time steps of a small fraction of a millisecond. This can result in an expensive calculation yielding greater overall accuracy than needed. Although it is tempting at first to try to address this issue with adaptive or fully implicit time-stepping, we argue that neither is effective here. The main advantage of ETD for Hodgkin-Huxley-like systems of ODEs is that it allows underresolution of the rising phase of the action potential without causing instability, using time steps on the order of one millisecond. When high quantitative accuracy is not necessary and perhaps, because of modeling inaccuracies, not even useful, ETD allows much faster simulations than standard explicit time-stepping schemes. The second-order ETD scheme is found to be substantially more accurate than the first-order one even for large values of Δt.

  4. EXPONENTIAL TIME DIFFERENCING FOR HODGKIN–HUXLEY-LIKE ODES

    PubMed Central

    Börgers, Christoph; Nectow, Alexander R.

    2013-01-01

    Several authors have proposed the use of exponential time differencing (ETD) for Hodgkin–Huxley-like partial and ordinary differential equations (PDEs and ODEs). For Hodgkin–Huxley-like PDEs, ETD is attractive because it can deal effectively with the stiffness issues that diffusion gives rise to. However, large neuronal networks are often simulated assuming “space-clamped” neurons, i.e., using the Hodgkin–Huxley ODEs, in which there are no diffusion terms. Our goal is to clarify whether ETD is a good idea even in that case. We present a numerical comparison of first- and second-order ETD with standard explicit time-stepping schemes (Euler’s method, the midpoint method, and the classical fourth-order Runge–Kutta method). We find that in the standard schemes, the stable computation of the very rapid rising phase of the action potential often forces time steps of a small fraction of a millisecond. This can result in an expensive calculation yielding greater overall accuracy than needed. Although it is tempting at first to try to address this issue with adaptive or fully implicit time-stepping, we argue that neither is effective here. The main advantage of ETD for Hodgkin–Huxley-like systems of ODEs is that it allows underresolution of the rising phase of the action potential without causing instability, using time steps on the order of one millisecond. When high quantitative accuracy is not necessary and perhaps, because of modeling inaccuracies, not even useful, ETD allows much faster simulations than standard explicit time-stepping schemes. The second-order ETD scheme is found to be substantially more accurate than the first-order one even for large values of Δt. PMID:24058276

  5. Development of a Double Nuclear Gene-Targeting Method by Two-Step Transformation Based on a Newly Established Chloramphenicol-Selection System in the Red Alga Cyanidioschyzon merolae.

    PubMed

    Fujiwara, Takayuki; Ohnuma, Mio; Kuroiwa, Tsuneyoshi; Ohbayashi, Ryudo; Hirooka, Shunsuke; Miyagishima, Shin-Ya

    2017-01-01

    The unicellular red alga Cyanidioschyzon merolae possesses a simple cellular architecture that consists of one mitochondrion, one chloroplast, one peroxisome, one Golgi apparatus, and several lysosomes. The nuclear genome content is also simple, with very little genetic redundancy (16.5 Mbp, 4,775 genes). In addition, molecular genetic tools such as gene targeting and inducible gene expression systems have been recently developed. These cytological features and genetic tractability have facilitated various omics analyses. However, only a single transformation selection marker URA has been made available and thus the application of genetic modification has been limited. Here, we report the development of a nuclear targeting method by using chloramphenicol and the chloramphenicol acetyltransferase (CAT) gene. In addition, we found that at least 200-bp homologous arms are required and 500-bp arms are sufficient for a targeted single-copy insertion of the CAT selection marker into the nuclear genome. By means of a combination of the URA and CAT transformation systems, we succeeded in producing a C. merolae strain that expresses HA-cyclin 1 and FLAG-CDKA from the chromosomal CYC1 and CDKA loci, respectively. These methods of multiple nuclear targeting will facilitate genetic manipulation of C. merolae.

  6. Development of a Double Nuclear Gene-Targeting Method by Two-Step Transformation Based on a Newly Established Chloramphenicol-Selection System in the Red Alga Cyanidioschyzon merolae

    PubMed Central

    Fujiwara, Takayuki; Ohnuma, Mio; Kuroiwa, Tsuneyoshi; Ohbayashi, Ryudo; Hirooka, Shunsuke; Miyagishima, Shin-Ya

    2017-01-01

    The unicellular red alga Cyanidioschyzon merolae possesses a simple cellular architecture that consists of one mitochondrion, one chloroplast, one peroxisome, one Golgi apparatus, and several lysosomes. The nuclear genome content is also simple, with very little genetic redundancy (16.5 Mbp, 4,775 genes). In addition, molecular genetic tools such as gene targeting and inducible gene expression systems have been recently developed. These cytological features and genetic tractability have facilitated various omics analyses. However, only a single transformation selection marker URA has been made available and thus the application of genetic modification has been limited. Here, we report the development of a nuclear targeting method by using chloramphenicol and the chloramphenicol acetyltransferase (CAT) gene. In addition, we found that at least 200-bp homologous arms are required and 500-bp arms are sufficient for a targeted single-copy insertion of the CAT selection marker into the nuclear genome. By means of a combination of the URA and CAT transformation systems, we succeeded in producing a C. merolae strain that expresses HA-cyclin 1 and FLAG-CDKA from the chromosomal CYC1 and CDKA loci, respectively. These methods of multiple nuclear targeting will facilitate genetic manipulation of C. merolae. PMID:28352279

  7. Immersed surfaces and membranes transformations

    NASA Astrophysics Data System (ADS)

    Kats, E. I.; Monastyrsky, M. I.

    2015-06-01

    Physical and biological observation methods provide a variety of bilayer membranes’ shapes and their transformations. Besides, the topological and geometrical methods allow us to deduce a classification of all possible membrane surfaces. This double-sided approach leads to a deeper insight into membranes properties. Our goal is to apply an appropriate mathematical technique for classifying vesicles (closed surfaces in mathematical terminology) and for their transformation ways. The problem turned out to be an intricate one, and to our knowledge no mathematical techniques have been applied to its solution. We find that all vesicles can be decomposed in a small number of universality classes generated by a few ‘bricks’: a torus, a screwed torus, and the real projective plane. We consider several ways of transforming membrane surfaces, bearing in mind that they possess an additional extremal property. Our method exploits different constructions of minimal surfaces in S3. We estimate energetic barrier for transformation of minimal membrane surfaces using the so-called doubling procedure. This problem is far from being a pure theoretical exercise. For instance, almost all cells’ biological functions, or tumor progression, are accompanied by apparently singular cell membrane transformations.

  8. Factorization of fermion doubles on the lattice

    NASA Astrophysics Data System (ADS)

    de A. Bicudo, P. J.

    2000-04-01

    We address the problem of the fermion species doubling on the Lattice. Our strategy is to factorize the fermion doubles from the action. The mass term of the Dirac-Wilson action is changed. In this case the extra roots which appear in the action of free fermions in the moment representation are independent of the mass and can be factorized from the fermion propagator. However the gauge couplings suffer from the pathological ghost poles which are common to non-local actions. This action can be used to find a solution of the Ginsparg Wilson relation, which is cured from the non-local pathology. Finally we compare this factorized action with solutions of The Ginsparg Wilson relation. We find that the present is equivalent to the Zenkin action, and that it is not exponentially local, in contrast with Neuberger's action.

  9. Lightweight Transformer

    DTIC Science & Technology

    1990-05-01

    could be used in any power conditioning circuit, inserted between any power source and load combination. Thus, its applicability is universal and...Typical Current Waveform from the Power Supply with a 5 ß Electrical Load -63- FILTER r—*-. REPRESENTS 16 OTOS IN PARELLEL , TEST / TRANSFORMER

  10. Transformation & Metamorphosis

    ERIC Educational Resources Information Center

    Lott, Debra

    2009-01-01

    The sculptures of Canadian artist Brian Jungen are a great inspiration for a lesson on creating new forms. Jungen transforms found objects into unique creations without fully concealing their original form or purpose. Frank Stella's sculpture series, including "K.132,2007" made of stainless steel and spray paint, is another great example of…

  11. Transforming Schools.

    ERIC Educational Resources Information Center

    Cookson, Peter W., Jr., Ed.; Schneider, Barbara, Ed.

    The authors in this book address the issues that relate to the crisis in American education and review some of the proposed solutions. To transform education, schools must be examined as social systems that are interrelated with families, communities, and the world of work. Following the introduction, section 1, "Conditions for Educational…

  12. Transformation & Metamorphosis

    ERIC Educational Resources Information Center

    Lott, Debra

    2009-01-01

    The sculptures of Canadian artist Brian Jungen are a great inspiration for a lesson on creating new forms. Jungen transforms found objects into unique creations without fully concealing their original form or purpose. Frank Stella's sculpture series, including "K.132,2007" made of stainless steel and spray paint, is another great example of…

  13. Transformation Time

    ERIC Educational Resources Information Center

    Berry, John N., III

    2007-01-01

    The program for the march by librarians on America's capital for the American Library Association (ALA) conference is predictably loaded with lobbying, legislation, and DC tours. It also abounds with professional opportunity and reflects the impact of Leslie Burger, one of the most activist ALA presidents in recent history. Her "Transformation"…

  14. Transforming Schools.

    ERIC Educational Resources Information Center

    Cookson, Peter W., Jr., Ed.; Schneider, Barbara, Ed.

    The authors in this book address the issues that relate to the crisis in American education and review some of the proposed solutions. To transform education, schools must be examined as social systems that are interrelated with families, communities, and the world of work. Following the introduction, section 1, "Conditions for Educational…

  15. Transformative Assessment

    ERIC Educational Resources Information Center

    Popham, W. James

    2008-01-01

    If you're at all skeptical that "formative assessment" is just another buzzword, then here's a book that will change the way you think about the role that formative assessment can play in transforming education into a more powerful and positive process. Renowned expert W. James Popham clarifies what formative assessment really is, why…

  16. Transforming Curriculum.

    ERIC Educational Resources Information Center

    Cronin, C. H.; Feldman, Phillip

    1994-01-01

    Presents comparisons between the traditional curriculum and the essential learnings curriculum implemented at the Moss Point School District in Moss Point, Mississippi. Describes in detail the curriculum transformation process. Provides insight into the role of technology in the reading/language arts curriculum. (RS)

  17. Transformation Time

    ERIC Educational Resources Information Center

    Berry, John N., III

    2007-01-01

    The program for the march by librarians on America's capital for the American Library Association (ALA) conference is predictably loaded with lobbying, legislation, and DC tours. It also abounds with professional opportunity and reflects the impact of Leslie Burger, one of the most activist ALA presidents in recent history. Her "Transformation"…

  18. Revisiting the quantum harmonic oscillator via unilateral Fourier transforms

    NASA Astrophysics Data System (ADS)

    Nogueira, Pedro H. F.; de Castro, Antonio S.

    2016-01-01

    The literature on the exponential Fourier approach to the one-dimensional quantum harmonic oscillator problem is revised and criticized. It is shown that the solution of this problem has been built on faulty premises. The problem is revisited via the Fourier sine and cosine transform method and the stationary states are properly determined by requiring definite parity and square-integrable eigenfunctions.

  19. The Movement to Transform High School. Forum Report

    ERIC Educational Resources Information Center

    Frey, Susan

    2005-01-01

    Although society has changed exponentially over the past 100 years, secondary schools have remained largely static, according to Gerald Hayward, who moderated EdSource's 28th Annual Forum, "Shaking up the Status Quo: The Movement to Transform High School," held in March 2005. Calling high schools difficult, complicated, and expensive,…

  20. Exponential H(infinity) synchronization of general discrete-time chaotic neural networks with or without time delays.

    PubMed

    Qi, Donglian; Liu, Meiqin; Qiu, Meikang; Zhang, Senlin

    2010-08-01

    This brief studies exponential H(infinity) synchronization of a class of general discrete-time chaotic neural networks with external disturbance. On the basis of the drive-response concept and H(infinity) control theory, and using Lyapunov-Krasovskii (or Lyapunov) functional, state feedback controllers are established to not only guarantee exponential stable synchronization between two general chaotic neural networks with or without time delays, but also reduce the effect of external disturbance on the synchronization error to a minimal H(infinity) norm constraint. The proposed controllers can be obtained by solving the convex optimization problems represented by linear matrix inequalities. Most discrete-time chaotic systems with or without time delays, such as Hopfield neural networks, cellular neural networks, bidirectional associative memory networks, recurrent multilayer perceptrons, Cohen-Grossberg neural networks, Chua's circuits, etc., can be transformed into this general chaotic neural network to be H(infinity) synchronization controller designed in a unified way. Finally, some illustrated examples with their simulations have been utilized to demonstrate the effectiveness of the proposed methods.