Distributed processing; distributed functions?
Fox, Peter T.; FRISTON, KARL J
2012-01-01
After more than twenty years busily mapping the human brain, what have we learned from neuroimaging? This review (coda) considers this question from the point of view of structure–function relationships and the two cornerstones of functional neuroimaging; functional segregation and integration. Despite remarkable advances and insights into the brain’s functional architecture, the earliest and simplest challenge in human brain mapping remains unresolved: We do not have a principled way to map ...
Parton Distribution Function Uncertainties
Giele, Walter T.; Kosower, David A.; Giele, Walter T.; Keller, Stephane A.; Kosower, David A.
2001-01-01
We present parton distribution functions which include a quantitative estimate of its uncertainties. The parton distribution functions are optimized with respect to deep inelastic proton data, expressing the uncertainties as a density measure over the functional space of parton distribution functions. This leads to a convenient method of propagating the parton distribution function uncertainties to new observables, now expressing the uncertainty as a density in the prediction of the observable. New measurements can easily be included in the optimized sets as added weight functions to the density measure. Using the optimized method nowhere in the analysis compromises have to be made with regard to the treatment of the uncertainties.
Distribution Functions of Copulas
Institute of Scientific and Technical Information of China (English)
LI Yong-hong; He Ping
2007-01-01
A general method was proposed to evaluate the distribution function of 〈C1|C2〉 . Some examples were presented to validate the application of the method. Then the sufficient and necessary condition for that the distribution function ofis uniform was proved.
Nuclear Parton Distribution Functions
Energy Technology Data Exchange (ETDEWEB)
I. Schienbein, J.Y. Yu, C. Keppel, J.G. Morfin, F. Olness, J.F. Owens
2009-06-01
We study nuclear effects of charged current deep inelastic neutrino-iron scattering in the framework of a {chi}{sup 2} analysis of parton distribution functions (PDFs). We extract a set of iron PDFs which are used to compute x{sub Bj}-dependent and Q{sup 2}-dependent nuclear correction factors for iron structure functions which are required in global analyses of free nucleon PDFs. We compare our results with nuclear correction factors from neutrino-nucleus scattering models and correction factors for charged-lepton--iron scattering. We find that, except for very high x{sub Bj}, our correction factors differ in both shape and magnitude from the correction factors of the models and charged-lepton scattering.
Modelling distribution functions and fragmentation functions
Rodrigues, J; Mulders, P J
1995-01-01
We present examples for the calculation of the distribution and fragmentation functions using the representation in terms of non-local matrix elements of quark field operators. As specific examples, we use a simple spectator model to estimate the leading twist quark distribution functions and the fragmentation functions for a quark into a nucleon or a pion.
Value Distribution of Meromorphic Functions
Zheng, Jianhua
2011-01-01
"Value Distribution of Meromorphic Functions" focuses on functions meromorphic in an angle or on the complex plane, T directions, deficient values, singular values, potential theory in value distribution and the proof of the celebrated Nevanlinna conjecture. The book introduces various characteristics of meromorphic functions and their connections, several aspects of new singular directions, new results on estimates of the number of deficient values, new results on singular values and behaviours of subharmonic functions which are the foundation for further discussion on the proof of
Practical quasi parton distribution functions
Ishikawa, Tomomi; Qiu, Jian-Wei; Yoshida, Shinsuke
2016-01-01
A completely new strategy to calculate parton distribution functions on the lattice has recently been proposed. In this method, lattice calculable observables, called quasi distributions, are related to normal distributions. The quasi distributions are known to contain power-law UV divergences arise from a Wilson line in the non-local operator, while the normal distributions only have logatithmic UV divergences. We propose possible method to subtract the power divegence to make the matching of the quasi with the normal distributions well-defined. We also demonstrate the matching of the quasi quark distribution between continuum and lattice implementing the power divergence subtraction. The matching calculations are carried out by one-loop perturbation.
Structure functions and parton distributions
Energy Technology Data Exchange (ETDEWEB)
Martin, A.D.; Stirling, W.J. [Univ. of Durham (United Kingdom); Roberts, R.G. [Rutherford Appleton Lab., Chilton, Didcot (United Kingdom)
1995-07-01
The MRS parton distribution analysis is described. The latest sets are shown to give an excellent description of a wide range of deep-inelastic and other hard scattering data. Two important theoretical issues-the behavior of the distributions at small x and the flavor structure of the quark sea-are discussed in detail. A comparison with the new structure function data from HERA is made, and the outlook for the future is discussed.
Beam shifts and distribution functions
Aiello, Andrea
2011-01-01
When a beam of light is reflected by a smooth surface its behavior deviates from geometrical optics predictions. Such deviations are quantified by the so-called spatial and angular Goos-Haenchen (GH) and Imbert-Fedorov (IF) shifts of the reflected beam. These shifts depend upon the shape of the incident beam, its polarization and on the material composition of the reflecting surface. In this article we suggest a novel approach that allows one to unambiguously isolate the beam-shape dependent aspects of GH and IF shifts. We show that this separation is possible as a result of some universal features of shifted distribution functions which are presented and discussed.
Nonparametric Bayes inference for concave distribution functions
DEFF Research Database (Denmark)
Hansen, Martin Bøgsted; Lauritzen, Steffen Lilholt
2002-01-01
Bayesian inference for concave distribution functions is investigated. This is made by transforming a mixture of Dirichlet processes on the space of distribution functions to the space of concave distribution functions. We give a method for sampling from the posterior distribution using a Pólya urn...
Local Polynomial Estimation of Distribution Functions
Institute of Scientific and Technical Information of China (English)
LI Yong-hong; ZENG Xia
2007-01-01
Under the condition that the total distribution function is continuous and bounded on (-∞,∞), we constructed estimations for distribution and hazard functions with local polynomial method, and obtained the rate of strong convergence of the estimations.
Modeling particle size distributions by the Weibull distribution function
Energy Technology Data Exchange (ETDEWEB)
Fang, Zhigang (Rogers Tool Works, Rogers, AR (United States)); Patterson, B.R.; Turner, M.E. Jr (Univ. of Alabama, Birmingham, AL (United States))
1993-10-01
A method is proposed for modeling two- and three-dimensional particle size distributions using the Weibull distribution function. Experimental results show that, for tungsten particles in liquid phase sintered W-14Ni-6Fe, the experimental cumulative section size distributions were well fit by the Weibull probability function, which can also be used to compute the corresponding relative frequency distributions. Modeling the two-dimensional section size distributions facilitates the use of the Saltykov or other methods for unfolding three-dimensional (3-D) size distributions with minimal irregularities. Fitting the unfolded cumulative 3-D particle size distribution with the Weibull function enables computation of the statistical distribution parameters from the parameters of the fit Weibull function.
Modeling nuclear parton distribution functions
Honkanen, H; Guzey, V
2013-01-01
The presence of nuclear medium and collective phenomena which involve several nucleons modify the parton distribution functions of nuclei (nPDFs) compared to those of a free nucleon. These modifications have been investigated by different groups using global analyses of high energy nuclear reaction world data resulting in modern nPDF parametrizations with error estimates, such as EPS09(s), HKN07 and nDS. These phenomenological nPDF sets roughly agree within their uncertainty bands, but have antiquarks for large-$x$ and gluons for the whole $x$-range poorly constrained by the available data. In the kinematics accessible at the LHC this has negative impact on the interpretation of the heavy-ion collision data, especially for the $p + A$ benchmarking runs. The EMC region is also sensitive to the proper definition of $x$, where the nuclear binding effects have to be taken into account, and for heavy nuclei one also needs to take into account that a fraction of the nucleus momentum is carried by the equivalent pho...
Distributed Function Computation in Asymmetric Communication Scenarios
Agnihotri, Samar
2009-01-01
We consider the distributed function computation problem in asymmetric communication scenarios, where the sink computes some deterministic function of the data split among N correlated informants. The distributed function computation problem is addressed as a generalization of distributed source coding (DSC) problem. We are mainly interested in minimizing the number of informant bits required, in the worst-case, to allow the sink to exactly compute the function. We provide a constructive solution for this in terms of an interactive communication protocol and prove its optimality. The proposed protocol also allows us to compute the worst-case achievable rate-region for the computation of any function. We define two classes of functions: lossy and lossless. We show that, in general, the lossy functions can be computed at the sink with fewer number of informant bits than the DSC problem, while computation of the lossless functions requires as many informant bits as the DSC problem.
The parton distribution function library
Energy Technology Data Exchange (ETDEWEB)
Plothow-Besch, H. [Universitat Dortmund (Germany)
1995-07-01
This article describes an integrated package of Parton Density Functions called PDFLIB which has been added to the CERN Program Library Pool W999 and is labelled as W5051. In this package all the different sets of parton density functions of the Nucleon, Pion and the Photon which are available today have been put together. All these sets have been combined in a consistent way such that they all have similar calling sequences and no external data files have to be read in anymore. A default set has been prepared, although those preferring their own set or wanting to test a new one may do so within the package. The package also offers a program to calculate the strong coupling constant {alpha}, to first or second order. The correct {Lambda}{sub QCD} associated to the selected set of structure functions and the number of allowed flavours with respect to the given Q{sup 2} is automatically used in the calculation. The selection of sets, the program parameters as well as the possibilities to modify the defaults and to control errors occurred during execution are described.
Plasma Dispersion Function for the Kappa Distribution
Podesta, John J.
2004-01-01
The plasma dispersion function is computed for a homogeneous isotropic plasma in which the particle velocities are distributed according to a Kappa distribution. An ordinary differential equation is derived for the plasma dispersion function and it is shown that the solution can be written in terms of Gauss' hypergeometric function. Using the extensive theory of the hypergeometric function, various mathematical properties of the plasma dispersion function are derived including symmetry relations, series expansions, integral representations, and closed form expressions for integer and half-integer values of K.
The Wigner distribution function in modal characterisation
CSIR Research Space (South Africa)
Mredlana, Prince
2016-07-01
Full Text Available Optical field characterisation often requires various isolated experiments to obtain characterisation parameters, we investigate a novel approach to characterise an optical field employing a Wigner distribution function with a modal decomposition...
Bounds on transverse momentum dependent distribution functions
Henneman, A A
2001-01-01
When more than one hadron takes part in a hard process, an extended set of quark distribution and fragmentation functions becomes relevant. In this talk, the derivation of Soffer-like bounds for these functions, in the case of a spin-1/2 target, is sketched and some of their aspects are discussed.
Bounds on transverse momentum dependent distribution functions
Henneman, A.
2000-01-01
When more than one hadron takes part in a hard process, an extended set of quark distribution and fragmentation functions becomes relevant. In this talk, the derivation of Soffer-like bounds for these functions, in the case of a spin-1/2 target, is sketched and some of their aspects are discussed.
Bounds on transverse momentum dependent distribution functions
Henneman, A.
2001-01-01
When more than one hadron takes part in a hard process, an extended set of quark distribution and fragmentation functions becomes relevant. In this talk, the derivation of Soffer-like bounds for these functions, in the case of a spin-1/2 target [1], is sketched and some of their aspects are discussed.
Attractor black holes and quantum distribution functions
Energy Technology Data Exchange (ETDEWEB)
Montanez, S. [Instituto de Fisica Teorica CSIC-UAM, Modulo C-XVI, Facultad de Ciencias, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Gomez, C. [Instituto de Fisica Teorica CSIC-UAM, Modulo C-XVI, Facultad de Ciencias, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Theory Group, Physics Department, CERN, 1211 Geneva 23 (Switzerland)
2007-05-15
Using the attractor mechanism and the wavefunction interpretation of the topological string partition function on a Calabi Yau threefold M we study the relation between the Bekenstein-Hawking-Wald entropy of BPS Calabi-Yau black holes and quantum distribution functions defined on H{sup 3}(M). We discuss the OSV conjecture in this context. (Abstract Copyright [2007], Wiley Periodicals, Inc.)
Distributed Oblivious Function Evaluation and Its Applications
Institute of Scientific and Technical Information of China (English)
Hong-Da Li; Xiong Yang; Deng-Guo Feng; Bao Li
2004-01-01
This paper is about distributed oblivious function evaluation (DOFE). In this setting one party (Alice) has a function f(x), and the other party (Bob) with an input α wants to learn f(α) in an oblivious way with the help of a set of servers. What Alice should do is to share her secret function f(x) among the servers. Bob obtains what he should get by interacting with the servers. This paper proposes the model and security requirements for DOFE and analyzes three distributed oblivious polynomial evaluation protocols presented in the paper.
Value-distribution of L-functions
Steuding, Jörn
2007-01-01
These notes present recent results in the value-distribution theory of L-functions with emphasis on the phenomenon of universality. In 1975, Voronin proved that any non-vanishing analytic function can be approximated uniformly by certain shifts of the Riemann zeta-function in the critical strip. This spectacular universality property has a strong impact on the zero-distribution: Riemann’s hypothesis is true if and only if the Riemann zeta-function can approximate itself uniformly (in the sense of Voronin). Meanwhile universality is proved for a large zoo of Dirichlet series, and it is conjectured that all reasonable L-functions are universal. In these notes we prove universality for polynomial Euler products. Our approach follows mainly Bagchi's probabilistic method. We further discuss related topics as, e.g., almost periodicity, density estimates, Nevanlinna theory, and functional independence.
Regge behaviour of distribution functions and and -evolutions of gluon distribution function at low-
Indian Academy of Sciences (India)
U Jamil; J K Sarma
2007-08-01
In this paper, and -evolutions of gluon distribution function from Dokshitzer–Gribov–Lipatov–Altarelli–Parisi (DGLAP) evolution equation in leading order (LO) at low- are presented assuming the Regge behaviour of quarks and gluons at this limit. We compare our results of gluon distribution function with MRST 2001, MRST 2004 and GRV 1998 parametrizations and show the compatibility of Regge behaviour of quark and gluon distribution functions with perturbative quantum chromodynamics (PQCD) at low-. We also discuss the limitations of Taylor series expansion method used earlier to solve DGLAP evolution equations in the Regge behaviour of distribution functions.
Exact probability distribution functions for Parrondo's games
Zadourian, Rubina; Saakian, David B.; Klümper, Andreas
2016-12-01
We study the discrete time dynamics of Brownian ratchet models and Parrondo's games. Using the Fourier transform, we calculate the exact probability distribution functions for both the capital dependent and history dependent Parrondo's games. In certain cases we find strong oscillations near the maximum of the probability distribution with two limiting distributions for odd and even number of rounds of the game. Indications of such oscillations first appeared in the analysis of real financial data, but now we have found this phenomenon in model systems and a theoretical understanding of the phenomenon. The method of our work can be applied to Brownian ratchets, molecular motors, and portfolio optimization.
Proposal for Modified Damage Probability Distribution Functions
DEFF Research Database (Denmark)
Pedersen, Preben Terndrup; Hansen, Peter Friis
1996-01-01
Immidiately following the Estonia disaster, the Nordic countries establishe a project entitled "Safety of Passenger/RoRo Vessels" As part of this project the present proposal for modified damage stability probability distribution functions has been developed. and submitted to "Sub-committee on st......Immidiately following the Estonia disaster, the Nordic countries establishe a project entitled "Safety of Passenger/RoRo Vessels" As part of this project the present proposal for modified damage stability probability distribution functions has been developed. and submitted to "Sub...
Tight Bounds for Distributed Functional Monitoring
DEFF Research Database (Denmark)
Woodruff, David P.; Zhang, Qin
2011-01-01
We resolve several fundamental questions in the area of distributed functional monitoring, initiated by Cormode, Muthukrishnan, and Yi (SODA, 2008). In this model there are $k$ sites each tracking their input and communicating with a central coordinator that continuously maintain an approximate...
Tight Bounds for Distributed Functional Monitoring
DEFF Research Database (Denmark)
Woodruff, David P.; Zhang, Qin
2011-01-01
We resolve several fundamental questions in the area of distributed functional monitoring, initiated by Cormode, Muthukrishnan, and Yi (SODA, 2008). In this model there are $k$ sites each tracking their input and communicating with a central coordinator that continuously maintain an approximate...
Nonequilibrium effects in the energy distribution function
Burns, George; Cohen, L. Kenneth
1983-03-01
The relative nonequilibrium energy distribution function, in the steady state for the irreversibly reacting Br2 in an argon system at 3500 K, is calculated. It is based upon 44 400 classical 3D trajectories, and uses the single uniform ensemble method [H. D. Kutz and G. Burns, J. Chem. Phys. 72, 3562 (1980)]. Although the raw data display a considerable scatter, they clearly indicate a depletion from the equilibrium distribution function over a wide energy range. A careful statistical study of the data is performed. It is found that their histograms can be described over the entire possible energy range by a simple analytical function with only one adjustable parameter. The best fitting procedure yields a surprisingly narrow goodness of fit. However, an apparent deviation of the fit from the data is observed in the energy region where the reaction channel opens. To that extent, this work sheds a new light on the nature of the steady state in an irreversible reaction.
Bi-log-concave Distribution Functions
DEFF Research Database (Denmark)
Dümbgen, Lutz; Kolesnyk, Petro; Wilke, Ralf
2017-01-01
Nonparametric statistics for distribution functions F or densities f=F′ under qualitative shape constraints constitutes an interesting alternative to classical parametric or entirely nonparametric approaches. We contribute to this area by considering a new shape constraint: F is said to be bi......-log-concave, if both logF and log(1−F) are concave. Many commonly considered distributions are compatible with this constraint. For instance, any c.d.f. F with log-concave density f=F′ is bi-log-concave. But in contrast to log-concavity of f, bi-log-concavity of F allows for multimodal densities. We provide various...
Asymmetric pair distribution functions in catalysts
DEFF Research Database (Denmark)
Clausen, B. S.; Nørskov, Jens Kehlet
2000-01-01
The structural parameters, i.e., coordination numbers, bond distances and disorder obtained from the analysis of EXAFS spectra may sometimes be significantly influenced by errors introduced due to the inadequacy of the analysis method applied. Especially in the case of heterogeneous catalysts...... it has been realized that often there is a need to use an improved EXAFS data analysis compared to the simple harmonic approach which works well for well-defined bulk structures. This is due to the fact that catalysts contain highly dispersed or disordered structures with pair distribution functions......, will be described. The method is based on an analysis of the pair distribution functions derived from molecular dynamics simulations of small metal particles and its reliability is demonstrated by comparing structural parameters obtained from independent X-ray diffraction experiments....
Distribution function approach to redshift space distortions
Seljak, Uros
2011-01-01
We develop a phase space distribution function approach to redshift space distortions (RSD), in which the redshift space density can be written as a sum over velocity moments of the distribution function. These moments are density weighted and their lowest orders are density, momentum density, and stress energy density. The series expansion is convergent on large scales. We perform an expansion of these velocity moments into helicity modes, which are eigenmodes under rotation around the axis of Fourier mode direction, generalizing the scalar, vector, tensor decomposition of perturbations to an arbitrary order. We show that only equal helicity moments correlate and derive the angular dependence of the individual contributions to the redshift space power spectrum in terms of angle mu between wave vector and line of sight. We show that the dominant term of mu^2 dependence on large scales is the cross-correlation between the density and scalar part of momentum density, which can be related to the time derivative ...
Distributed Function Calculation over Noisy Networks
Directory of Open Access Journals (Sweden)
Zhidun Zeng
2016-01-01
Full Text Available Considering any connected network with unknown initial states for all nodes, the nearest-neighbor rule is utilized for each node to update its own state at every discrete-time step. Distributed function calculation problem is defined for one node to compute some function of the initial values of all the nodes based on its own observations. In this paper, taking into account uncertainties in the network and observations, an algorithm is proposed to compute and explicitly characterize the value of the function in question when the number of successive observations is large enough. While the number of successive observations is not large enough, we provide an approach to obtain the tightest possible bounds on such function by using linear programing optimization techniques. Simulations are provided to demonstrate the theoretical results.
Neoclassical physics in full distribution function gyrokinetics
Dif-Pradalier, G.; Diamond, P. H.; Grandgirard, V.; Sarazin, Y.; Abiteboul, J.; Garbet, X.; Ghendrih, Ph.; Latu, G.; Strugarek, A.; Ku, S.; Chang, C. S.
2011-06-01
Treatment of binary Coulomb collisions when the full gyrokinetic distribution function is evolved is discussed here. A spectrum of different collision operators is presented, differing through both the physics that can be addressed and the numerics they are based on. Eulerian-like (semi-Lagrangian) and particle in cell (PIC) (Monte-Carlo) schemes are successfully cross-compared, and a detailed confrontation to neoclassical theory is shown.
Wireless distributed functional electrical stimulation system
Directory of Open Access Journals (Sweden)
Jovičić Nenad S
2012-08-01
Full Text Available Abstract Background The control of movement in humans is hierarchical and distributed and uses feedback. An assistive system could be best integrated into the therapy of a human with a central nervous system lesion if the system is controlled in a similar manner. Here, we present a novel wireless architecture and routing protocol for a distributed functional electrical stimulation system that enables control of movement. Methods The new system comprises a set of miniature battery-powered devices with stimulating and sensing functionality mounted on the body of the subject. The devices communicate wirelessly with one coordinator device, which is connected to a host computer. The control algorithm runs on the computer in open- or closed-loop form. A prototype of the system was designed using commercial, off-the-shelf components. The propagation characteristics of electromagnetic waves and the distributed nature of the system were considered during the development of a two-hop routing protocol, which was implemented in the prototype’s software. Results The outcomes of this research include a novel system architecture and routing protocol and a functional prototype based on commercial, off-the-shelf components. A proof-of-concept study was performed on a hemiplegic subject with paresis of the right arm. The subject was tasked with generating a fully functional palmar grasp (closing of the fingers. One node was used to provide this movement, while a second node controlled the activation of extensor muscles to eliminate undesired wrist flexion. The system was tested with the open- and closed-loop control algorithms. Conclusions The system fulfilled technical and application requirements. The novel communication protocol enabled reliable real-time use of the system in both closed- and open-loop forms. The testing on a patient showed that the multi-node system could operate effectively to generate functional movement.
Selected topics on parton distribution functions
Hirai, M; Kumano, S; Saito, K
2011-01-01
We report recent studies on structure functions of the nucleon and nuclei. First, clustering effects are investigated in the structure function F_2 of Be-9 for explaining an unusual nuclear correction found in a JLab experiment. We propose that high densities created by formation of clustering structure like 2*alpha+neutron in Be-9 is the origin of the unexpected JLab result by using the antisymmetrized molecular dynamics (AMD). There is an approved proposal at JLab to investigate the structure functions of light nuclei including the cluster structure, so that much details will become clear in a few years. Second, tensor-polarized quark and antiquark distributions are obtained by analyzing HERMES measurements on the structure function b_1 for the deuteron. The result suggests a finite tensor polarization for antiquark distributions, which is an interesting topic for further theoretical and experimental investigations. An experimental proposal exists at JLab for measuring b_1 of the deuteron as a new tensor-st...
Unbiased spin-dependent Parton Distribution Functions
Nocera, Emanuele Roberto
2014-01-01
We present the first unbiased determination of spin-dependent, or polarized, Parton Distribution Functions (PDFs) of the proton. A statistically sound representation of the corresponding uncertainties is achieved by means of the NNPDF methodology: this was formerly developed for unpolarized distributions and is now generalized to the polarized here for the first time. The features of the procedure, based on robust statistical tools (Monte Carlo sampling for error propagation, neural networks for PDF parametrization, genetic algorithm for their minimization, and possibly reweighting for including new data samples without refitting), are illustrated in detail. Different sets of polarized PDFs are obtained at next-to-leading order accuracy in perturbative quantum chromodynamics, based on both fixed-target inclusive deeply-inelastic scattering data and the most recent polarized collider data. A quantitative appraisal on the potential role of future measurements at an Electron-Ion Collider is also presented. We st...
Distribution Function of Mesoscopic Hopping Conductance
Institute of Scientific and Technical Information of China (English)
何立群; Eugene Kogan; ,Moshe Kaveh; Shlomo Havlin; Nehemia Schartz; LUO Dawei
2002-01-01
We study mesoscopic hopping conductance by computer simulation distribution functions (DFs). It is found that the distributions obtained by choosing randomly the chemical potentials (for a fixed impurity configuration), which corresponds to a typical experimental situation, coincide with those obtained when both impurity configuration and chemical potential are chosen randomly, in agreement with the ergodicity hypothesis. The DFs in shape obtained for one-dimensional systems are found to be quite close to the predictions of the theory by Raikh and Ruzin. For the two-dimensional case, the DFs both for a narrow system and thin film look to be similar (and close to the one-dimensional case). The DF for the conductance of the square sample is nearly Gaussian.
Integrals over the triplet distribution function without the triplet distribution function
Lado, F.
While the triplet distribution function of disordered systems appears in a wide variety of problems in statistical mechanics, it does so always under an integral sign. In this paper, we propose a new method of evaluating such integrals that involves only pair functions throughout and avoids altogether the need for any explicit representation of the little-known triplet function. The procedure is based on an extension of integral equation theory of classical fluids. Numerical illustrations of the method are given for integrals that arise in the calculation of moments of a local field distribution.
Spaceflight alters immune cell function and distribution
Sonnenfeld, Gerald; Mandel, Adrian D.; Konstantinova, Irina V.; Berry, Wallace D.; Taylor, Gerald R.; Lesniak, A. T.; Fuchs, Boris B.; Rakhmilevich, Alexander L.
1992-01-01
Experiments are described which were performed onboard Cosmos 2044 to determine spaceflight effects on immunologically important cell function and distribution. Results indicate that bone marrow cells from flown and suspended rats exhibited a decreased response to a granulocyte/monocyte colony-stimulating factor compared with the bone marrow cells from control rats. Bone marrow cells showed an increase in the percentage of cells expressing markers for helper T-cells in the myelogenous population and increased percentages of anti-asialo granulocyte/monocyte-1-bearing interleulin-2 receptor bearing pan T- and helper T-cells in the lymphocytic population.
Bund, G W
2004-01-01
The mapping of the Wigner distribution function (WDF) for a given bound-state onto a semiclassical distribution function (SDF) satisfying the Liouville equation introduced previously by us is applied to the ground state of the Morse oscillator. Here we give results showing that the SDF gets closer to the corresponding WDF as the number of levels of the Morse oscillator increases. We find that for a Morse oscillator with one level only, the agreement between the WDF and the mapped SDF is very poor but for a Morse oscillator of ten levels it becomes satisfactory.
MBOK: ITS DISTRIBUTION, MEANING, AND FUNCTION
Directory of Open Access Journals (Sweden)
Ajar Pradika A. Tur
2015-12-01
Full Text Available Mbok, in Javanese language, has not only a ’mother’ in meaning. As a lexicon in the language, mbok in one side truly means a ‘mother’ and still has the same meaning although it experiences the morphological process to be, at least, embok, simbok, or mboke. The variations exist and are spoken by Javanese native speakers throughout the Javanese dialects such as Suroboyoan, Solo, Yogyakarta, Bagelen, and Banyumasan dialects spread from the East Java, Yogyakarta, and Central Java. However, mbok, as a particle has different meaning, even different various meanings relying on its distribution in a sentence. Then the meanings bear its different various functions as well in the sentence based on the context of the sentence (grammatical-semantics meaning. Through Teknik Balik (Converse Technique the data gained was analyzed to distinguish the position of the particle in the sentence in order to reach its significant different meanings and functions. At least, from the analysis, we have three positions of mbok in the sentences, that are in the initial, middle, and the end of the sentences. These positions affect the meanings and functions that can be seen as follows; ‘, is not it?’ (Tag Question and ‘is/are” (Verbal Question for emphasizing, ‘please’ for requesting a help, ‘may be’ and ‘in case’ for expressing possibility, and ‘causing’ for expressing cause-effect. Keywords: mbok, semantics, Banyumasan dialect
Pion valence-quark parton distribution function
Directory of Open Access Journals (Sweden)
Lei Chang
2015-10-01
Full Text Available Within the Dyson–Schwinger equation formulation of QCD, a rainbow ladder truncation is used to calculate the pion valence-quark distribution function (PDF. The gap equation is renormalized at a typical hadronic scale, of order 0.5 GeV, which is also set as the default initial scale for the pion PDF. We implement a corrected leading-order expression for the PDF which ensures that the valence-quarks carry all of the pion's light-front momentum at the initial scale. The scaling behavior of the pion PDF at a typical partonic scale of order 5.2 GeV is found to be (1−xν, with ν≃1.6, as x approaches one.
Parton distribution functions with QED corrections
Carrazza, Stefano
2015-01-01
We present the first unbiased determination of parton distribution functions (PDFs) with electroweak corrections. The aim of this thesis is to provide an exhaustive description of the theoretical framework and the technical implementation which leads to the determination of a set of PDFs which includes the photon PDF and quantum electrodynamics (QED) contributions to parton evolution. First, we introduce and motivate the need of including electroweak corrections to PDFs, providing phenomenological examples and presenting an overview of the current state of the art in PDF fits. The theoretical implications of such corrections are then described through the implementation of the combined QCD+QED evolution in APFEL, a public code for the solution of the PDF evolution developed particularly for this thesis. We proceed by presenting the new structure of the Neural-Network PDF (NNPDF) methodology used for the extraction of this set of PDFs with QED corrections. We then provide a first determination of the full set ...
Carotenoids in Algae: Distributions, Biosyntheses and Functions
Directory of Open Access Journals (Sweden)
Shinichi Takaichi
2011-06-01
Full Text Available For photosynthesis, phototrophic organisms necessarily synthesize not only chlorophylls but also carotenoids. Many kinds of carotenoids are found in algae and, recently, taxonomic studies of algae have been developed. In this review, the relationship between the distribution of carotenoids and the phylogeny of oxygenic phototrophs in sea and fresh water, including cyanobacteria, red algae, brown algae and green algae, is summarized. These phototrophs contain division- or class-specific carotenoids, such as fucoxanthin, peridinin and siphonaxanthin. The distribution of α-carotene and its derivatives, such as lutein, loroxanthin and siphonaxanthin, are limited to divisions of Rhodophyta (macrophytic type, Cryptophyta, Euglenophyta, Chlorarachniophyta and Chlorophyta. In addition, carotenogenesis pathways are discussed based on the chemical structures of carotenoids and known characteristics of carotenogenesis enzymes in other organisms; genes and enzymes for carotenogenesis in algae are not yet known. Most carotenoids bind to membrane-bound pigment-protein complexes, such as reaction center, light-harvesting and cytochrome b6f complexes. Water-soluble peridinin-chlorophyll a-protein (PCP and orange carotenoid protein (OCP are also established. Some functions of carotenoids in photosynthesis are also briefly summarized.
Function Analyses of Geographic Information System on Rural Distribution Network
Institute of Scientific and Technical Information of China (English)
FANG Junlong; FAN Yongcun; ZHANG Chunmei; GU Shumin
2006-01-01
With the actuality and characteristic and requirement of rural power enterprise distribution network management, this article introduced the function of geographic information system on the framework of distribution network, in order to develop rural distribution network.
Nuclear modifications of Parton Distribution Functions
Adeluyi, Adeola Adeleke
This dissertation addresses a central question of modern nuclear physics: how does the behavior of fundamental degrees of freedom (quarks and gluons) change in the nuclear environment? This is an important aspect of experimental studies at current facilities such as the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory and the Continuous Electron Beam Accelerator Facility (CEBAF) at the Thomas Jefferson National Laboratory (JLAB). It is also highly relevant to planned experimental efforts at the Large Hadron Collider (LHC) and the future Electron Ion Collider (EIC). All these facilities probe matter via collisions involving nuclei; thus complications arise due to the presence of the attendant nuclear medium. Theoretical efforts to understand and interpret experimental results from such collisions are therefore largely dependent on the resolution of this question. The development of nuclear physics demonstrates that theoretical description is most efficient in terms of the effective degrees of freedom relevant to the scale (energy) being probed. Thus at low energies, nuclei are described as bound states of protons and neutrons (nucleons). At higher energies, the nucleons are no longer elementary, but are revealed to possess an underlying substructure: they are made up of quarks and gluons, collectively termed partons. The mometum distributions of these partons in the nucleon are referred to as Parton Distribution Functions (PDFs). Parton distributions can be determined from experimental measurements of structure functions. The ratio of nuclear structure functions to nucleon structure functions (generically referred to as nuclear ratio) is a measure of the nuclear modifications of the free nucleon PDFs. Thus a study of the nuclear ratio suffices to gain an understanding of nuclear modifications. In this dissertation we aim to describe theoretically nuclear modifications in a restricted region where the nuclear ratio is less than unity, the so
Vasyliunas-Cairns distribution function for space plasma species
Abid, A. A.; Ali, S.; Du, J.; Mamun, A. A.
2015-08-01
A more generalized form of non-Maxwellian distribution function (that can be named as Vasyliunas-Cairns distribution function) is introduced. Its basic properties are numerically analyzed by the variation of two important parameters, namely, α (which shows the amount of energetic particles present in the plasma system) and κ (which shows the superthermality of the plasma species). It has been observed that (i) for α → 0 ( κ → ∞ ), the Vasyliunas-Cairns distribution function reduces to the Vasyliunas or κ (Cairns or nonthermal) distribution function; (ii) for α → 0 and κ → ∞ , it reduces to the Maxwellian distribution function; and (iii) the effect of the parameter α (κ) significantly modifies the basic properties of the Vasyliunas (Cairns) distribution function. The applications of this generalized non-Maxwellian distribution function (Vasyliunas-Cairns distribution function) in different space plasma situations are briefly discussed.
Tight Bounds for Distributed Functional Monitoring
Woodruff, David P
2011-01-01
We resolve several fundamental questions in the area of distributed functional monitoring, initiated by Cormode, Muthukrishnan, and Yi (SODA, 2008). In this model there are $k$ sites each tracking their input and communicating with a central coordinator that continuously maintain an approximate output to a function $f$ computed over the union of the inputs. The goal is to minimize the communication. We show the randomized communication complexity of estimating the number of distinct elements up to a $1+\\eps$ factor is $\\Omega(k/\\eps^2)$, improving the previous $\\Omega(k + 1/\\eps^2)$ bound and matching known upper bounds. For the $p$-th frequency moment $F_p$, $p > 1$, we improve the previous $\\Omega(k + 1/\\eps^2)$ communication bound to $\\tilde{\\Omega}(k^{p-1}/\\eps^2)$. We obtain similar improvements for heavy hitters, empirical entropy, and other problems. We also show that we can estimate $F_p$, for any $p > 1$, using $\\tilde{O}(k^{p-1}\\poly(\\eps^{-1}))$ communication. This drastically improves upon the pre...
Representation of classifier distributions in terms of hypergeometric functions
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
This paper derives alternative analytical expressions for classifier product distributions in terms of Gauss hypergeometric function, 2F1, by considering feed distribution defined in terms of Gates-Gaudin-Schumann function and efficiency curve defined in terms of a logistic function. It is shown that classifier distributions under dispersed conditions of classification pivot at a common size and the distributions are difference similar.The paper also addresses an inverse problem of classifier distributions wherein the feed distribution and efficiency curve are identified from the measured product distributions without needing to know the solid flow split of particles to any of the product streams.
Distributed Function Computation Under Privacy Constraints
Tyagi, Himanshu
2012-01-01
A set of terminals observe correlated data and seek to compute functions of the data using interactive public communication. At the same time, it is required that the value of a private function of the data remains concealed from an eavesdropper observing this communication. In general, the private function and the functions computed by the nodes can be all different. We show that a class of functions are securely computable if and only if the conditional entropy of data given the value of private function is greater than the least rate of interactive communication required for a related multiterminal source-coding task. A single-letter formula is provided for this rate in special cases.
Parametric Probability Distribution Functions for Axon Diameters of Corpus Callosum
Directory of Open Access Journals (Sweden)
Farshid eSepehrband
2016-05-01
Full Text Available Axon diameter is an important neuroanatomical characteristic of the nervous system that alters in the course of neurological disorders such as multiple sclerosis. Axon diameters vary, even within a fiber bundle, and are not normally distributed. An accurate distribution function is therefore beneficial, either to describe axon diameters that are obtained from a direct measurement technique (e.g., microscopy, or to infer them indirectly (e.g., using diffusion-weighted MRI. The gamma distribution is a common choice for this purpose (particularly for the inferential approach because it resembles the distribution profile of measured axon diameters which has been consistently shown to be non-negative and right-skewed. In this study we compared a wide range of parametric probability distribution functions against empirical data obtained from electron microscopy images. We observed that the gamma distribution fails to accurately describe the main characteristics of the axon diameter distribution, such as location and scale of the mode and the profile of distribution tails. We also found that the generalized extreme value distribution consistently fitted the measured distribution better than other distribution functions. This suggests that there may be distinct subpopulations of axons in the corpus callosum, each with their own distribution profiles. In addition, we observed that several other distributions outperformed the gamma distribution, yet had the same number of unknown parameters; these were the inverse Gaussian, log normal, log logistic and Birnbaum-Saunders distributions.
MINIMAX INVARIANT ESTIMATOR OF CONTINUOUS DISTRIBUTION FUNCTION UNDER LINEX LOSS
Institute of Scientific and Technical Information of China (English)
Jianhui NING; Minyu XIE
2007-01-01
In this paper we consider the problem of estimation of a continuous distribution function under the LINEX loss function.The best invariant estimator is obtained,and proved to be minimax for any sample size n≥1.
Characterization of bathtub distributions via percentile residual life functions
Franco-Pereira, Alba M.; Lillo, Rosa E.; Romo, Juan
2010-01-01
In reliability theory and survival analysis, many set of data are generated by distributions with bathtub shaped hazard rate functions. Launer (1993) established several relations between the behaviour of the hazard rate function and the percentile residual life function. In particular, necessary conditions were given for a special type of bathtub distributions in terms of percentile residual life functions. The purpose of this paper is to complete the study initiated by Launer...
Wigner Function of Density Operator for Negative Binomial Distribution
Institute of Scientific and Technical Information of China (English)
HE Min-Hua; XU Xing-Lei; ZHANG Duan-Ming; LI Hong-Qi; PAN Gui-Jun; YIN Yan-Ping; CHEN Zhi-Yuan
2008-01-01
By using the technique of integration within an ordered product (IWOP) of operator we derive Wigner function of density operator for negative binomial distribution of radiation field in the mixed state case, then we derive the Wigner function of squeezed number state, which yields negative binomial distribution by virtue of the entangled state representation and the entangled Wigner operator.
Witherow, William K. (Inventor)
1988-01-01
A Lambertian reference standard for uniformly scattering a beam of light is constructed of a plate having a planar surface with a layer of glue disposed on the surface. An evenly packed layer of monodisperse spheres is set in the layer, and when the standard is used for bi-directional (BRDF) measurements, the spheres are coated with a layer of highly relective substance, such as gold or silver. When the standard is used for bi-directional transmittance distribution function (BTDF) measurements, the spheres are of a transparent material and are provided with a roughened surface, as by acid etching. In this case, the layer of glue is an optical cement, and the plate is of glass, with the spheres, the layer, and the plate all possessing a similar refractive index.
Probability distribution functions in the finite density lattice QCD
Ejiri, S; Aoki, S; Kanaya, K; Saito, H; Hatsuda, T; Ohno, H; Umeda, T
2012-01-01
We study the phase structure of QCD at high temperature and density by lattice QCD simulations adopting a histogram method. We try to solve the problems which arise in the numerical study of the finite density QCD, focusing on the probability distribution function (histogram). As a first step, we investigate the quark mass dependence and the chemical potential dependence of the probability distribution function as a function of the Polyakov loop when all quark masses are sufficiently large, and study the properties of the distribution function. The effect from the complex phase of the quark determinant is estimated explicitly. The shape of the distribution function changes with the quark mass and the chemical potential. Through the shape of the distribution, the critical surface which separates the first order transition and crossover regions in the heavy quark region is determined for the 2+1-flavor case.
Generalized functional responses for species distributions
Matthiopoulos, J.; Hebblewhite, M.; Aarts, G.M; Fieberg, J.
2011-01-01
Researchers employing resource selection functions (RSFs) and other related methods aim to detect correlates of space-use and mitigate against detrimental environmental change. However, an empirical model fit to data from one place or time is unlikely to capture species responses under different con
Computer routines for probability distributions, random numbers, and related functions
Kirby, W.H.
1980-01-01
Use of previously codes and tested subroutines simplifies and speeds up program development and testing. This report presents routines that can be used to calculate various probability distributions and other functions of importance in statistical hydrology. The routines are designed as general-purpose Fortran subroutines and functions to be called from user-written main programs. The probability distributions provided include the beta, chisquare, gamma, Gaussian (normal), Pearson Type III (tables and approximation), and Weibull. Also provided are the distributions of the Grubbs-Beck outlier test, Kolmogorov 's and Smirnov 's D, Student 's t, noncentral t (approximate), and Snedecor F tests. Other mathematical functions include the Bessel function I (subzero), gamma and log-gamma functions, error functions and exponential integral. Auxiliary services include sorting and printer plotting. Random number generators for uniform and normal numbers are provided and may be used with some of the above routines to generate numbers from other distributions. (USGS)
Distribution and functions of sterols and sphingolipids.
Hannich, J Thomas; Umebayashi, Kyohei; Riezman, Howard
2011-05-01
Sterols and sphingolipids are considered mainly eukaryotic lipids even though both are present in some prokaryotes, with sphingolipids being more widespread than sterols. Both sterols and sphingolipids differ in their structural features in vertebrates, plants, and fungi. Interestingly, some invertebrates cannot synthesize sterols de novo and seem to have a reduced dependence on sterols. Sphingolipids and sterols are found in the plasma membrane, but we do not have a clear picture of their precise intracellular localization. Advances in lipidomics and subcellular fractionation should help to improve this situation. Genetic approaches have provided insights into the diversity of sterol and sphingolipid functions in eukaryotes providing evidence that these two lipid classes function together. Intermediates in sphingolipid biosynthesis and degradation are involved in signaling pathways, whereas sterol structures are converted to hormones. Both lipids have been implicated in regulating membrane trafficking.
Distributed implementation of functional program evaluation
Energy Technology Data Exchange (ETDEWEB)
Fasel, J.H.; Douglass, R.J.; Michelsen, R.; Hudak, P.
1985-01-01
In this paper, we explore the potential of the functional model, particularly as it pertains to architecture. In Section 2, we describe the graph-reduction operational model of computation and its relation to AI problems. In Section 3, we discuss a class of architectures that implement graph reduction and a prototype implementation in this class being developed at Los Alamos. Finally, we speculate on the applicability of graph reduction to some other classes of architecture.
Pair distribution functions of silicon/silicon nitride interfaces
Cao, Deng; Bachlechner, Martina E.
2006-03-01
Using molecular dynamics simulations, we investigate different mechanical and structural properties of the silicon/silicon nitride interface. One way to characterize the structure as tensile strain is applied parallel to the interface is to calculate pair distribution functions for specific atom types. The pair distribution function gives the probability of finding a pair of atoms a distance r apart, relative to the probability expected for a completely random distribution at the same density. The pair distribution functions for bulk silicon nitride reflect the fracture of the silicon nitride film at about 8 % and the fact that the centerpiece of the silicon nitride film returns to its original structure after fracture. The pair distribution functions for interface silicon atoms reveal the formation of bonds for originally unbound atom pairs, which is indicative of the interstitial-vacancy defect that causes failure in silicon.
New Function of Seaports: Logistics and Distribution
Directory of Open Access Journals (Sweden)
Igor Jakomin
2003-01-01
Full Text Available The globalization process occurs in all the spheres of ourlife and its quantitative and spatial dimensions affect theworld's development. These trends lead the enterprises to concentrateon their core business and outsource some auxilimy oradditional parts of their production or se1vices. It is vital for theoperation in such conditions that the logistics functionssmoothly and reliably in all its segments.To provide an answer to the given hypothesis, I have dealtwith all the major questions linked to the phenomenon of seaportsand their role in the development of new logistical anddistributional function.
Angular Distributions of Discrete Mesoscale Mapping Functions
Directory of Open Access Journals (Sweden)
Kroszczyński Krzysztof
2015-08-01
Full Text Available The paper presents the results of analyses of numerical experiments concerning GPS signal propagation delays in the atmosphere and the discrete mapping functions defined on their basis. The delays were determined using data from the mesoscale non-hydrostatic weather model operated in the Centre of Applied Geomatics, Military University of Technology. A special attention was paid to investigating angular characteristics of GPS slant delays for low angles of elevation. The investigation proved that the temporal and spatial variability of the slant delays depends to a large extent on current weather conditions
An Orientation Distribution Function for Trabecular Bone
Energy Technology Data Exchange (ETDEWEB)
Lawrence Livermore National Laboratory
2004-10-08
We describe a new method for quantifying the orientation of trabecular bone from three-dimensional images. Trabecular lattices from five human vertebrae were decomposed into individual trabecular elements, and the orientation, mass, and thickness of each element were recorded. Continuous functions that described the total mass (M({var_phi},{theta})) and mean thickness ({tau}({var_phi},{theta})) of all trabeculae as a function of orientation were derived. The results were compared with experimental measurements of the elastic modulus in the three principal anatomic directions. A power law scaling relationship between the anisotropies in mass and elastic modulus was observed; the scaling exponent was 1.41 (R{sup 2} = 0.88). As expected, the preponderance of trabecular mass was oriented along the cranial-caudal direction; on average, there was 3.4 times more mass oriented vertically than horizontally. Moreover, the vertical trabeculae were 30% thicker, on average, than the horizontal trabeculae. The vertical trabecular thickness was inversely related to the connectivity (R{sup 2} = 0.70; p = 0.07), suggesting a possible organization into either few, thick trabeculae or many thin trabeculae. The method, which accounts for the mechanical connectedness of the lattice, provides a rapid way to both visualize and quantify the three-dimensional organization of trabecular bone.
The auroral O+ non-Maxwellian velocity distribution function revisited
Directory of Open Access Journals (Sweden)
F. Leblanc
Full Text Available New characteristics of O+ ion velocity distribution functions in a background of atomic oxygen neutrals subjected to intense external electromagnetic forces are presented. The one dimensional (1-D distribution function along the magnetic field displays a core-halo shape which can be accurately fitted by a two Maxwellian model. The Maxwellian shape of the 1-D distribution function around a polar angle of 21 ± 1° from the magnetic field direction is confirmed, taking into account the accuracy of the Monte Carlo simulations. For the first time, the transition of the O+ 1-D distribution function from a core halo shape along the magnetic field direction to the well-known toroidal shape at large polar angles, through the Maxwellian shape at polar angle of 21 ± 1° is properly explained from a generic functional of the velocity moments at order 2 and 4.
Influence of Generalized (r, q) Distribution Function on Electrostatic Waves
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
Non-Maxwellian particle distribution functions possessing high energy tail and shoulder in the profile of distribution function considerably change the damping characteristics of the waves. In the present paper Landau damping ofelectron plasma (Langmuir) waves and ion-acoustic waves in a hot, isotropic, unmagnetized plasma is studied with the generalized (r, q) distribution function. The results show that for the Langmuir oscillations Landau damping becomes severe as the spectral index r or q reduces. However, for the ion-acoustic waves Landau damping is more sensitive to the ion temperature than the spectral indices.
PROBABILITY DISTRIBUTION FUNCTION OF NEAR-WALL TURBULENT VELOCITY FLUCTUATIONS
Institute of Scientific and Technical Information of China (English)
无
2005-01-01
By large eddy simulation (LES), turbulent databases of channel flows at different Reynolds numbers were established. Then, the probability distribution functions of the streamwise and wall-normal velocity fluctuations were obtained and compared with the corresponding normal distributions. By hypothesis test, the deviation from the normal distribution was analyzed quantitatively. The skewness and flatness factors were also calculated. And the variations of these two factors in the viscous sublayer, buffer layer and log-law layer were discussed. Still illustrated were the relations between the probability distribution functions and the burst events-sweep of high-speed fluids and ejection of low-speed fluids-in the viscous sub-layer, buffer layer and loglaw layer. Finally the variations of the probability distribution functions with Reynolds number were examined.
A Comment on Quantum Distribution Functions and the OSV Conjecture
Gómez, C; Gomez, Cesar; Montanez, Sergio
2006-01-01
Using the attractor mechanism and the relation between the quantization of $H^{3}(M)$ and topological strings on a Calabi Yau threefold $M$ we define a map from BPS black holes into coherent states. This map allows us to represent the Bekenstein-Hawking-Wald entropy as a quantum distribution function on the phase space $H^{3}(M)$. This distribution function is a mixed Husimi/anti-Husimi distribution corresponding to the different normal ordering prescriptions for the string coupling and deviations of the complex structure moduli. From the integral representation of this distribution function in terms of the Wigner distribution we recover the Ooguri-Strominger-Vafa (OSV) conjecture in the region "at infinity" of the complex structure moduli space. The physical meaning of the OSV corrections are briefly discussed in this limit.
A comment on quantum distribution functions and the OSV conjecture
Energy Technology Data Exchange (ETDEWEB)
Gomez, Cesar [Instituto de Fisica Teorica CSIC/UAM, C-XVI Universidad Autonoma, E-28049 Madrid (Spain); Montanez, Sergio [Instituto de Fisica Teorica CSIC/UAM, C-XVI Universidad Autonoma, E-28049 Madrid (Spain)
2006-12-15
Using the attractor mechanism and the relation between the quantization of H{sup 3}(M) and topological strings on a Calabi Yau threefold M we define a map from BPS black holes into coherent states. This map allows us to represent the Bekenstein-Hawking-Wald entropy as a quantum distribution function on the phase space H{sup 3}(M). This distribution function is a mixed Husimi/anti-Husimi distribution corresponding to the different normal ordering prescriptions for the string coupling and deviations of the complex structure moduli. From the integral representation of this distribution function in terms of the Wigner distribution we recover the Ooguri-Strominger-Vafa (OSV) conjecture in the region 'at infinity' of the complex structure moduli space. The physical meaning of the OSV corrections are briefly discussed in this limit.
DUAL INTEGRAL EQUATIONS INVOLVING LEGENDRE FUNCTIONS IN DISTRIBUTION SPACES
Directory of Open Access Journals (Sweden)
P. K. BANERJI, DESHNA LOONKER
2010-11-01
Full Text Available In this paper we use the Mehler-Fock transformation to obtain thesolution of dual integral equations involving Legendre functions. The solutionso obtained is proved to be distributional because they satisfy properties ofdistribution space.
Action-based distribution functions for spheroidal galaxy components
Posti, Lorenzo; Nipoti, Carlo; Ciotti, Luca
2014-01-01
We present an approach to the design of distribution functions that depend on the phase-space coordinates through the action integrals. The approach makes it easy to construct a dynamical model of a given stellar component. We illustrate the approach by deriving distribution functions that self-consistently generate several popular stellar systems, including the Hernquist, Jaffe, Navarro, Frenk and White models. We focus on non-rotating spherical systems, but extension to flattened and rotating systems is trivial. Our distribution functions are easily added to each other and to previously published distribution functions for discs to create self-consistent multi-component galaxies. The models this approach makes possible should prove valuable both for the interpretation of observational data and for exploring the non-equilibrium dynamics of galaxies via N-body simulation.
Action-based distribution functions for spheroidal galaxy components
Posti, Lorenzo; Binney, James; Nipoti, Carlo; Ciotti, Luca
2015-03-01
We present an approach to the design of distribution functions that depend on the phase-space coordinates through the action integrals. The approach makes it easy to construct a dynamical model of a given stellar component. We illustrate the approach by deriving distribution functions that self-consistently generate several popular stellar systems, including the Hernquist, Jaffe, and Navarro, Frenk and White models. We focus on non-rotating spherical systems, but extension to flattened and rotating systems is trivial. Our distribution functions are easily added to each other and to previously published distribution functions for discs to create self-consistent multicomponent galaxies. The models this approach makes possible should prove valuable both for the interpretation of observational data and for exploring the non-equilibrium dynamics of galaxies via N-body simulations.
Mapping distributed brain function and networks with diffuse optical tomography
Eggebrecht, Adam T.; Ferradal, Silvina L.; Robichaux-Viehoever, Amy; Hassanpour, Mahlega S.; Dehghani, Hamid; Snyder, Abraham Z.; Hershey, Tamara; Culver, Joseph P.
2014-06-01
Mapping of human brain function has revolutionized systems neuroscience. However, traditional functional neuroimaging by positron emission tomography or functional magnetic resonance imaging cannot be used when applications require portability, or are contraindicated because of ionizing radiation (positron emission tomography) or implanted metal (functional magnetic resonance imaging). Optical neuroimaging offers a non-invasive alternative that is radiation free and compatible with implanted metal and electronic devices (for example, pacemakers). However, optical imaging technology has heretofore lacked the combination of spatial resolution and wide field of view sufficient to map distributed brain functions. Here, we present a high-density diffuse optical tomography imaging array that can map higher-order, distributed brain function. The system was tested by imaging four hierarchical language tasks and multiple resting-state networks including the dorsal attention and default mode networks. Finally, we imaged brain function in patients with Parkinson's disease and implanted deep brain stimulators that preclude functional magnetic resonance imaging.
A New Lifetime Distribution with Bathtube and Unimodal Hazard Function
Barriga, Gladys D. C.; Louzada-Neto, Francisco; Cancho, Vicente G.
2008-11-01
In this paper we propose a new lifetime distribution which accommodate bathtub-shaped, unimodal, increasing and decreasing hazard function. Some special particular cases are derived, including the standard Weibull distribution. Maximum likelihood estimation is considered for estimate the tree parameters present in the model. The methodology is illustrated in a real data set on industrial devices on a lite test.
Generalised partition functions: inferences on phase space distributions
Treumann, Rudolf A.; Baumjohann, Wolfgang
2016-06-01
It is demonstrated that the statistical mechanical partition function can be used to construct various different forms of phase space distributions. This indicates that its structure is not restricted to the Gibbs-Boltzmann factor prescription which is based on counting statistics. With the widely used replacement of the Boltzmann factor by a generalised Lorentzian (also known as the q-deformed exponential function, where κ = 1/|q - 1|, with κ, q ∈ R) both the kappa-Bose and kappa-Fermi partition functions are obtained in quite a straightforward way, from which the conventional Bose and Fermi distributions follow for κ → ∞. For κ ≠ ∞ these are subject to the restrictions that they can be used only at temperatures far from zero. They thus, as shown earlier, have little value for quantum physics. This is reasonable, because physical κ systems imply strong correlations which are absent at zero temperature where apart from stochastics all dynamical interactions are frozen. In the classical large temperature limit one obtains physically reasonable κ distributions which depend on energy respectively momentum as well as on chemical potential. Looking for other functional dependencies, we examine Bessel functions whether they can be used for obtaining valid distributions. Again and for the same reason, no Fermi and Bose distributions exist in the low temperature limit. However, a classical Bessel-Boltzmann distribution can be constructed which is a Bessel-modified Lorentzian distribution. Whether it makes any physical sense remains an open question. This is not investigated here. The choice of Bessel functions is motivated solely by their convergence properties and not by reference to any physical demands. This result suggests that the Gibbs-Boltzmann partition function is fundamental not only to Gibbs-Boltzmann but also to a large class of generalised Lorentzian distributions as well as to the corresponding nonextensive statistical mechanics.
Numerical distribution functions of fractional unit root and cointegration tests
DEFF Research Database (Denmark)
MacKinnon, James G.; Nielsen, Morten Ørregaard
We calculate numerically the asymptotic distribution functions of likelihood ratio tests for fractional unit roots and cointegration rank. Because these distributions depend on a real-valued parameter, b, which must be estimated, simple tabulation is not feasible. Partly due to the presence...... of this parameter, the choice of model specification for the response surface regressions used to obtain the numerical distribution functions is more involved than is usually the case. We deal with model uncertainty by model averaging rather than by model selection. We make available a computer program which, given...
Institute of Scientific and Technical Information of China (English)
ZHENGZUKANG
1996-01-01
Suppose that Z1,Z2…,Zn are independent normal random variables with common mean μ and variance σ2. Then S2=∑n n=1 (zi-z)2/σ2 and T =（n-1的平方根）-Z/（S2/n的平方根） have x2n-1 distribution and tn-1 distribution respectively. If the normal assumption fails, there will be the remainders of the distribution functions and density functions. This paper gives the direct expansions of distribution functions and density functions of S2 and T up to o(n-1). They are more intuitive and convenient than usual Edgeworth expansions.
Energy and enthalpy distribution functions for a few physical systems.
Wu, K L; Wei, J H; Lai, S K; Okabe, Y
2007-08-02
The present work is devoted to extracting the energy or enthalpy distribution function of a physical system from the moments of the distribution using the maximum entropy method. This distribution theory has the salient traits that it utilizes only the experimental thermodynamic data. The calculated distribution functions provide invaluable insight into the state or phase behavior of the physical systems under study. As concrete evidence, we demonstrate the elegance of the distribution theory by studying first a test case of a two-dimensional six-state Potts model for which simulation results are available for comparison, then the biphasic behavior of the binary alloy Na-K whose excess heat capacity, experimentally observed to fall in a narrow temperature range, has yet to be clarified theoretically, and finally, the thermally induced state behavior of a collection of 16 proteins.
Extended Matrix Variate Hypergeometric Functions and Matrix Variate Distributions
Directory of Open Access Journals (Sweden)
Daya K. Nagar
2015-01-01
Full Text Available Hypergeometric functions of matrix arguments occur frequently in multivariate statistical analysis. In this paper, we define and study extended forms of Gauss and confluent hypergeometric functions of matrix arguments and show that they occur naturally in statistical distribution theory.
Generalised functions and distributional curvature of cosmic strings
Clarke, C J S; Wilson, J P
1996-01-01
A new method is presented for assigning distributional curvature, in an invariant manner, to a space-time of low differentiability, using the techniques of Colombeau's `new generalised functions'. The method is applied to show that curvature of a cone is equivalent to a delta function. The same is true under small enough perturbations.
Nair, T R Gopalakrishnan; Krutthika, H K
2010-01-01
The main goal of this research is to develop the concepts of a revolutionary processor system called Functional Processor System. The fairly novel work carried out in this proposal concentrates on decoding of function pipelines and distributing it in FPUs as a part of scheduling approach. As the functional programs are super-level programs that entails requirements only at functional level, decoding of functions and distribution of functions in the heterogeneous functional processor units are a challenge. We explored the possibilities of segregation of the functions from the application program and distributing the functions on the relevant FPUs by using address mapping techniques. Here we pursue the perception of feeding the functions into the processor farm rather than the processor fetching the instructions or functions and executing it. This work is carried out at theoretical levels and it requires a long way to go in the realization of this work in hardware perhaps with a large industrial team with a pra...
Transverse momentum dependence in gluon distribution and fragmentation functions
Mulders, P J
2001-01-01
We investigate the twist two gluon distribution functions for spin 1/2 hadrons, emphasizing intrinsic transverse momentum of the gluons. These functions are relevant in leading order in the inverse hard scale in scattering processes such as inclusive leptoproduction or Drell-Yan scattering, or more general in hard processes in which at least two hadrons are involved. They show up in azimuthal asymmetries. For future estimates of such observables, we discuss specific bounds on these functions.
Analyzing Distributed Functions in an Integrated Hazard Analysis
Morris, A. Terry; Massie, Michael J.
2010-01-01
Large scale integration of today's aerospace systems is achievable through the use of distributed systems. Validating the safety of distributed systems is significantly more difficult as compared to centralized systems because of the complexity of the interactions between simultaneously active components. Integrated hazard analysis (IHA), a process used to identify unacceptable risks and to provide a means of controlling them, can be applied to either centralized or distributed systems. IHA, though, must be tailored to fit the particular system being analyzed. Distributed systems, for instance, must be analyzed for hazards in terms of the functions that rely on them. This paper will describe systems-oriented IHA techniques (as opposed to traditional failure-event or reliability techniques) that should be employed for distributed systems in aerospace environments. Special considerations will be addressed when dealing with specific distributed systems such as active thermal control, electrical power, command and data handling, and software systems (including the interaction with fault management systems). Because of the significance of second-order effects in large scale distributed systems, the paper will also describe how to analyze secondary functions to secondary functions through the use of channelization.
Phase pupil functions for focal-depth enhancement derived from a Wigner distribution function.
Zalvidea, D; Sicre, E E
1998-06-10
A method for obtaining phase-retardation functions, which give rise to an increase of the image focal depth, is proposed. To this end, the Wigner distribution function corresponding to a specific aperture that has an associated small depth of focus in image space is conveniently sheared in the phase-space domain to generate a new Wigner distribution function. From this new function a more uniform on-axis image irradiance can be accomplished. This approach is illustrated by comparison of the imaging performance of both the derived phase function and a previously reported logarithmic phase distribution.
Stand diameter distribution modelling and prediction based on Richards function.
Directory of Open Access Journals (Sweden)
Ai-guo Duan
Full Text Available The objective of this study was to introduce application of the Richards equation on modelling and prediction of stand diameter distribution. The long-term repeated measurement data sets, consisted of 309 diameter frequency distributions from Chinese fir (Cunninghamia lanceolata plantations in the southern China, were used. Also, 150 stands were used as fitting data, the other 159 stands were used for testing. Nonlinear regression method (NRM or maximum likelihood estimates method (MLEM were applied to estimate the parameters of models, and the parameter prediction method (PPM and parameter recovery method (PRM were used to predict the diameter distributions of unknown stands. Four main conclusions were obtained: (1 R distribution presented a more accurate simulation than three-parametric Weibull function; (2 the parameters p, q and r of R distribution proved to be its scale, location and shape parameters, and have a deep relationship with stand characteristics, which means the parameters of R distribution have good theoretical interpretation; (3 the ordinate of inflection point of R distribution has significant relativity with its skewness and kurtosis, and the fitted main distribution range for the cumulative diameter distribution of Chinese fir plantations was 0.4∼0.6; (4 the goodness-of-fit test showed diameter distributions of unknown stands can be well estimated by applying R distribution based on PRM or the combination of PPM and PRM under the condition that only quadratic mean DBH or plus stand age are known, and the non-rejection rates were near 80%, which are higher than the 72.33% non-rejection rate of three-parametric Weibull function based on the combination of PPM and PRM.
Stand diameter distribution modelling and prediction based on Richards function.
Duan, Ai-guo; Zhang, Jian-guo; Zhang, Xiong-qing; He, Cai-yun
2013-01-01
The objective of this study was to introduce application of the Richards equation on modelling and prediction of stand diameter distribution. The long-term repeated measurement data sets, consisted of 309 diameter frequency distributions from Chinese fir (Cunninghamia lanceolata) plantations in the southern China, were used. Also, 150 stands were used as fitting data, the other 159 stands were used for testing. Nonlinear regression method (NRM) or maximum likelihood estimates method (MLEM) were applied to estimate the parameters of models, and the parameter prediction method (PPM) and parameter recovery method (PRM) were used to predict the diameter distributions of unknown stands. Four main conclusions were obtained: (1) R distribution presented a more accurate simulation than three-parametric Weibull function; (2) the parameters p, q and r of R distribution proved to be its scale, location and shape parameters, and have a deep relationship with stand characteristics, which means the parameters of R distribution have good theoretical interpretation; (3) the ordinate of inflection point of R distribution has significant relativity with its skewness and kurtosis, and the fitted main distribution range for the cumulative diameter distribution of Chinese fir plantations was 0.4∼0.6; (4) the goodness-of-fit test showed diameter distributions of unknown stands can be well estimated by applying R distribution based on PRM or the combination of PPM and PRM under the condition that only quadratic mean DBH or plus stand age are known, and the non-rejection rates were near 80%, which are higher than the 72.33% non-rejection rate of three-parametric Weibull function based on the combination of PPM and PRM.
Valence-quark distribution functions in the kaon and pion
Chen, Chen; Roberts, Craig D; Wan, Shaolong; Zong, Hong-Shi
2016-01-01
We describe expressions for pion and kaon dressed-quark distribution functions that incorporate contributions from gluons which bind quarks into these mesons and hence overcome a flaw of the commonly used handbag approximation. The distributions therewith obtained are purely valence in character, ensuring that dressed-quarks carry all a meson's momentum at a characteristic hadronic scale and vanishing as $(1-x)^2$ when Bjorken-$x\\to 1$. Comparing such distributions within the pion and kaon, it is apparent that the size of SU(3)-flavour symmetry breaking in meson parton distribution functions is modulated by the flavour dependence of dynamical chiral symmetry breaking. Corrections to these leading-order formulae may be divided into two classes, responsible for shifting dressed-quark momentum into glue and sea-quarks. Working with available empirical information, we build an algebraic framework that is capable of expressing the principal impact of both classes of corrections. This enables a realistic comparison...
NUMERICAL SIMULATION OF ORIENTATION DISTRIBUTION FUNCTION OF CYLINDRICAL PARTICLE SUSPENSIONS
Institute of Scientific and Technical Information of China (English)
林建忠; 张凌新
2002-01-01
The orientation distribution function of cylindrical particle suspensions was deduced and numerically simulated, and an application was taken in a wedge-shaped flow field. The relationship between the orientation distribution function and particle orientation angles was obtained. The results show that comparing with the most probable angle distribution which comes to being in short time, the distribution of the steady state doesn' t vary much in range ; the main difference is the anti-clockwise rotation in the right and upper field, that is, particles rotate more at the points where the velocity gradients are larger.The most probable orientations are close to the direction of local streamlines. In the direction of streamlines, with poleradius decreasing, the most probable angles increase,but the angles between their orientations and the local streamlines decrease.
Unbiased estimators for spatial distribution functions of classical fluids.
Adib, Artur B; Jarzynski, Christopher
2005-01-01
We use a statistical-mechanical identity closely related to the familiar virial theorem, to derive unbiased estimators for spatial distribution functions of classical fluids. In particular, we obtain estimators for both the fluid density rho(r) in the vicinity of a fixed solute and the pair correlation g(r) of a homogeneous classical fluid. We illustrate the utility of our estimators with numerical examples, which reveal advantages over traditional histogram-based methods of computing such distributions.
The use of generalized functions and distributions in general relativity
Energy Technology Data Exchange (ETDEWEB)
Steinbauer, R [Department of Mathematics, University of Vienna, Nordbergstrasse 15, A-1090 Wien (Austria); Vickers, J A [School of Mathematics, University of Southampton, Southampton SO17 1BJ (United Kingdom)
2006-05-21
We review the extent to which one can use classical distribution theory in describing solutions of Einstein's equations. We show that there are a number of physically interesting cases which cannot be treated using distribution theory but require a more general concept. We describe a mathematical theory of nonlinear generalized functions based on Colombeau algebras and show how this may be applied in general relativity. We end by discussing the concept of singularity in general relativity and show that certain solutions with weak singularities may be regarded as distributional solutions of Einstein's equations. (topical review)
Gyrokinetic simulations with a general equilibrium distribution function
Wilkie, George; Highcock, Edmund; Abel, Ian; Dorland, William
2013-10-01
Applying the gyrokinetic framework to study the dynamics of fast particles requires a transport-scale equilibrium distribution that is not Maxwellian, and whose functional form may not be known a priori. The GS2 gyrokinetics code has been modified to accommodate an arbitrary equilibrium distribution and this capability has been validated. The need to resolve the tail of the distribution for fast particles introduces numerical challenges that are resolved by implementing a generalized quadrature scheme that retains spectral accuracy of velocity-space integrals. Preliminary simulation results are presented.
The use of Generalised Functions and Distributions in General Relativity
Steinbauer, R; Steinbauer, Roland; Vickers, James A.
2006-01-01
In this paper we review the extent to which one can use classical distribution theory in describing solutions of Einstein's equations. We show that there are a number of physically interesting cases which cannot be treated using distribution theory but require a more general concept. We describe a mathematical theory of nonlinear generalised functions based on Colombeau algebras and show how this may be applied in general relativity. We end by discussing the concept of singularity in general relativity and show that certain solutions with weak singularities may be regarded as distributional solutions of Einstein's equations.
Rubio de Francia's extrapolation theory: estimates for the distribution function
Carro, María J; Torres, Rodolfo H
2010-01-01
Let $T$ be an arbitrary operator bounded from $L^{p_0}(w)$ into $L^{p_0, \\infty}(w)$ for every weight $w$ in the Muckenhoupt class $A_{p_0}$. It is proved in this article that the distribution function of $Tf$ with respect to any weight $u$ can be essentially majorized by the distribution function of $Mf$ with respect to $u$ (plus an integral term easy to control). As a consequence, well-known extrapolation results, including results in a multilinear setting, can be obtained with very simple proofs. New applications in extrapolation for two-weight problems and estimates on rearrangement invariant spaces are established too.
Progress on Bayesian Inference of the Fast Ion Distribution Function
DEFF Research Database (Denmark)
Stagner, L.; Heidbrink, W.W,; Chen, X.;
2013-01-01
The fast-ion distribution function (DF) has a complicated dependence on several phase-space variables. The standard analysis procedure in energetic particle research is to compute the DF theoretically, use that DF in forward modeling to predict diagnostic signals, then compare with measured data...... sensitivity of the measurements are incorporated into Bayesian likelihood probabilities. Prior probabilities describe physical constraints. This poster will show reconstructions of classically described, low-power, MHD-quiescent distribution functions from actual FIDA measurements. A description of the full...
Characterizing microcrack orientation distribution functions in osteonal bone samples.
Wolfram, U; Schwiedrzik, J J; Mirzaali, M J; Bürki, A; Varga, P; Olivier, C; Peyrin, F; Zysset, P K
2016-12-01
Prefailure microdamage in bone tissue is considered to be the most detrimental factor in defining its strength and toughness with respect to age and disease. To understand the influence of microcracks on bone mechanics it is necessary to assess their morphology and three-dimensional distribution. This requirement reaches beyond classic histology and stereology, and methods to obtain such information are currently missing. Therefore, the aim of the study was to develop a methodology that allows to characterize three-dimensional microcrack distributions in bulk bone samples. Four dumbbell-shaped specimens of human cortical bone of a 77-year-old female donor were loaded beyond yield in either tension, compression or torsion (one control). Subsequently, synchrotron radiation micro-computed tomography (SRμCT) was used to obtain phase-contrast images of the damaged samples. A microcrack segmentation algorithm was developed and used to segment microcrack families for which microcrack orientation distribution functions were determined. Distinct microcrack families were observed for each load case that resulted in distinct orientation distribution functions. Microcracks had median areas of approximately 4.7 μm(2) , 33.3 μm(2) and 64.0 μm(2) for tension, compression and torsion. Verifying the segmentation algorithm against a manually segmented ground truth showed good results when comparing the microcrack orientation distribution functions. A size dependence was noted when investigating the orientation distribution functions with respect to the size of the volume of interest used for their determination. Furthermore, a scale separation between tensile, compressive and torsional microcracks was noticeable. Visual comparison to classic histology indicated that microcrack families were successfully distinguished. We propose a methodology to analyse three-dimensional microcrack distributions in overloaded cortical bone. Such information could improve our understanding of
On K-wise Independent Distributions and Boolean Functions
Benjamini, Itai; Peled, Ron
2012-01-01
We pursue a systematic study of the following problem. Let f:{0,1}^n -> {0,1} be a (usually monotone) Boolean function whose behaviour is well understood when the input bits are identically independently distributed. What can be said about the behaviour of the function when the input bits are not completely independent, but only k-wise independent, i.e. every subset of k bits is independent? more precisely, how high should k be so that any k-wise independent distribution "fools" the function, i.e. causes it to behave nearly the same as when the bits are completely independent? We analyze several well known Boolean functions (including AND, Majority, Tribes and Percolation among others), some of which turn out to have surprising properties. In some of our results we use tools from the theory of the classical moment problem, seemingly for the first time in this subject, to shed light on these questions.
Stability of a Generalized Quadratic Functional Equation in Schwartz Distributions
Institute of Scientific and Technical Information of China (English)
Jae-Young CHUNG
2009-01-01
We consider the Hyers-Ulam stability problem of the generalized quadratic functional equation u(o)A+v(o)B-2w(o)P1-2k(o)P2=0, which is a distributional version of the classical generalized quadratic functional equation f(x + y) + g(x - y) - 2h(x) - 2k(y) = 0.
Production analysis of functionally distributed machines for underground mining
Institute of Scientific and Technical Information of China (English)
Fukui Rui; Kusaka Kouhei; Nakao Masayuki; Kodama Yuichi; Uetake Masaaki; Kawai Kazunari
2016-01-01
Recent years, underground mining method is becoming popular because of its potentially high produc-tivity and efficiency. In this method, a mining machinery;load haul dump (LHD), is used as both an exca-vator and a transporter of ore. This paper proposes a distributed system that realizes the excavation and transport functions with separated vehicles, an excavator and a transporter. In addition, this research proposes a mining map and configurations suitable for the proposed distributed system. To evaluate the productivity of the proposed system, a simulation environment has been developed. Analysis using the simulator reveals what performance factors of the excavator and the transporter have large impacts on the productivity. Simulation results also demonstrate the difference of potential between LHD system and the distributed system that can be explained based on their functions allocation.
Probability Distribution Function of Passive Scalars in Shell Models
Institute of Scientific and Technical Information of China (English)
LIU Chun-Ping; ZHANG Xiao-Qiang; LIU Yu-Rong; WANG Guang-Rui; HE Da-Ren; CHEN Shi-Gang; ZHU Lu-Jin
2008-01-01
A shell-model version of passive scalar problem is introduced, which is inspired by the model of K. Ohkitani and M. Yakhot [K. Ohkitani and M. Yakhot, Phys. Rev. Lett. 60 (1988) 983; K. Ohkitani and M. Yakhot, Prog. Theor. Phys. 81 (1988) 329]. As in the original problem, the prescribed random velocity field is Gaussian and 5 correlated in time. Deterministic differential equations are regarded as nonlinear Langevin equation. Then, the Fokker-Planck equations of PDF for passive scalars axe obtained and solved numerically. In energy input range (n < 5, n is the shell number.), the probability distribution function (PDF) of passive scalars is near the Gaussian distribution. In inertial range (5 < n < 16) and dissipation range (n ≥ 17), the probability distribution function (PDF) of passive scalars has obvious intermittence. And the scaling power of passive scalar is anomalous. The results of numerical simulations are compared with experimental measurements.
Bounds on Transverse Momentum Dependent Distribution and Fragmentation Functions
Bacchetta, A.; Boglione, M.; Henneman, A.; Mulders, P. J.
2000-07-01
We give bounds on the distribution and fragmentation functions that appear at leading order in deep inelastic one-particle inclusive leptoproduction or in Drell-Yan processes. These bounds simply follow from positivity of the defining matrix elements and are an important guidance in estimating the magnitude of the azimuthal and spin asymmetries in these processes.
Bounds on transverse momentum dependent distribution and fragmentation functions
Bacchetta, A; Henneman, A A; Mulders, P J
2000-01-01
We give bounds on the distribution and fragmentation functions that appear at leading order in deep inelastic 1-particle inclusive leptoproduction or in Drell-Yan processes. These bounds simply follow from positivity of the defining matrix elements and are an important guidance in estimating the magnitude of the azimuthal and spin asymmetries in these processes.
Family Functions' Distribution in Men and Women Concepts
Kasimova, Ramilya Sh.; Biktagirova, Gulnara F.
2016-01-01
Creating a happy family with a favorable psychological climate is important both for the individual and the society as a whole. One of the factors, that influence the creation of a welfare family, is the content of the spouses' concepts of the family, its functions and their possible distribution. The main purpose of this article is to identify…
Distributed Global Function Model Finding for Wireless Sensor Network Data
Directory of Open Access Journals (Sweden)
Song Deng
2016-01-01
Full Text Available Function model finding has become an important tool for analysis of data collected from wireless sensor networks (WSNs. With the development of WSNs, a large number of sensors have been widely deployed so that the collected data show the characteristics of distribution and mass. For distributed and massive sensor data, traditional centralized function model finding algorithms would lead to a significant decrease in performance. To solve this problem, this paper proposes a distributed global function model finding algorithm for wireless sensor network data (DGFMF-WSND. In DGFMF-WSND, on the basis of gene expression programming (GEP, an adaptive population generation strategy based on sub-population associated evolution is applied to improve the convergence speed of GEP. Secondly, to solve the generation of global function model in distributed wireless sensor networks data, this paper provides a global model generation algorithm based on unconstrained nonlinear least squares. Four representative datasets are used to evaluate the performance of the proposed algorithm. The comparative results show that the improved GEP with adaptive population generation strategy outperforms all other algorithms on the average convergence speed, time-consumption, value of R-square, and prediction accuracy. Meanwhile, experimental results also show that DGFMF-WSND has a clear advantage in terms of time-consumption and error of fitting. Moreover, with increasing of dataset size, DGFMF-WSND also demonstrates good speed-up ratio and scale-up ratio.
Universality of the Distribution Functions of Random Matrix Theory. II
Tracy, Craig A.; Widom, Harold
1999-01-01
This paper is a brief review of recent developments in random matrix theory. Two aspects are emphasized: the underlying role of integrable systems and the occurrence of the distribution functions of random matrix theory in diverse areas of mathematics and physics.
Thermodynamic Derivation of the Equilibrium Distribution Functions of Statistical Mechanics.
Stoeckly, Beth
1979-01-01
Presents a simplified derivation of the equilibrium distribution functions. The derivation proceeds from the change in the Helmholtz free energy when a particle is added to a system of fixed temperature, volume, and chemical potential. The derivations show the relationship between statistical mechanics and macroscopic thermodynamics. (Author/GA)
Limb distribution, motor impairment, and functional classification of cerebral palsy
J.A. Gorter; P.L. Rosenbaum
2004-01-01
This study explored the relationships between the Gross Motor Function Classification System (GMFCS), limb distribution, and type of motor impairment. Data used were collected in the Ontario Motor Growth study, a longitudinal cohort study with a population-based sample of children with cerebral pals
Distributed representations in memory: insights from functional brain imaging.
Rissman, Jesse; Wagner, Anthony D
2012-01-01
Forging new memories for facts and events, holding critical details in mind on a moment-to-moment basis, and retrieving knowledge in the service of current goals all depend on a complex interplay between neural ensembles throughout the brain. Over the past decade, researchers have increasingly utilized powerful analytical tools (e.g., multivoxel pattern analysis) to decode the information represented within distributed functional magnetic resonance imaging activity patterns. In this review, we discuss how these methods can sensitively index neural representations of perceptual and semantic content and how leverage on the engagement of distributed representations provides unique insights into distinct aspects of memory-guided behavior. We emphasize that, in addition to characterizing the contents of memories, analyses of distributed patterns shed light on the processes that influence how information is encoded, maintained, or retrieved, and thus inform memory theory. We conclude by highlighting open questions about memory that can be addressed through distributed pattern analyses.
Valence-quark distribution functions in the kaon and pion
Chen, Chen; Chang, Lei; Roberts, Craig D.; Wan, Shaolong; Zong, Hong-Shi
2016-04-01
We describe expressions for pion and kaon dressed-quark distribution functions that incorporate contributions from gluons which bind quarks into these mesons and hence overcome a flaw of the commonly used handbag approximation. The distributions therewith obtained are purely valence in character, ensuring that dressed quarks carry all the meson's momentum at a characteristic hadronic scale and vanish as (1 -x )2 when Bjorken-x →1 . Comparing such distributions within the pion and kaon, it is apparent that the size of S U (3 ) -flavor symmetry breaking in meson parton distribution functions is modulated by the flavor dependence of dynamical chiral symmetry breaking. Corrections to these leading-order formulas may be divided into two classes, responsible for shifting dressed-quark momentum into glue and sea quarks. Working with available empirical information, we build an algebraic framework that is capable of expressing the principal impact of both classes of corrections. This enables a realistic comparison with experiment which allows us to identify and highlight basic features of measurable pion and kaon valence-quark distributions. We find that whereas roughly two thirds of the pion's light-front momentum is carried by valence dressed quarks at a characteristic hadronic scale; this fraction rises to 95% in the kaon; evolving distributions with these features to a scale typical of available Drell-Yan data produces a kaon-to-pion ratio of u -quark distributions that is in agreement with the single existing data set, and predicts a u -quark distribution within the pion that agrees with a modern reappraisal of π N Drell-Yan data. Precise new data are essential in order to validate this reappraisal and because a single modest-quality measurement of the kaon-to-pion ratio cannot be considered definitive.
Valence-quark distribution functions in the kaon and pion
Energy Technology Data Exchange (ETDEWEB)
Chen, Chen; Chang, Lei; Roberts, Craig D.; Wan, Shaolong; Zong, Hong-Shi
2016-04-18
We describe expressions for pion and kaon dressed-quark distribution functions that incorporate contributions from gluons which bind quarks into these mesons and hence overcome a flaw of the commonly used handbag approximation. The distributions therewith obtained are purely valence in character, ensuring that dressed quarks carry all the meson’s momentum at a characteristic hadronic scale and vanish as ( 1 - x ) ^{2} when Bjorken- x → 1 . Comparing such distributions within the pion and kaon, it is apparent that the size of S U ( 3 ) -flavor symmetry breaking in meson parton distribution functions is modulated by the flavor dependence of dynamical chiral symmetry breaking. Corrections to these leading-order formulas may be divided into two classes, responsible for shifting dressed-quark momentum into glue and sea quarks. Working with available empirical information, we build an algebraic framework that is capable of expressing the principal impact of both classes of corrections. This enables a realistic comparison with experiment which allows us to identify and highlight basic features of measurable pion and kaon valence-quark distributions. We find that whereas roughly two thirds of the pion’s light-front momentum is carried by valence dressed quarks at a characteristic hadronic scale; this fraction rises to 95% in the kaon; evolving distributions with these features to a scale typical of available Drell-Yan data produces a kaon-to-pion ratio of u -quark distributions that is in agreement with the single existing data set, and predicts a u -quark distribution within the pion that agrees with a modern reappraisal of π N Drell-Yan data. Precise new data are essential in order to validate this reappraisal and because a single modest-quality measurement of the kaon-to-pion ratio cannot be considered definitive.
Distribution of Zeros of the Mittag-Leffler Function
Hanneken, John W.
2003-03-01
The Mittag-Leffler function, which is a generalization of the exponential function, occurs naturally in the solution of physical problems involving fractional calculus [i.e. Physica A297 (2001) 361-367, A309 (2002) 275-288]. The zeros of the Mittag-Leffler functions play a significant role in the dynamic solutions. Complete and correct information about the distribution of zeros has not yet been available. A systematic analysis of the zeros of E_α,1(z) has been carried out and an iteration formula for the number of zeros for arbitrary alpha has been obtained.
Recursive confidence band construction for an unknown distribution function.
Kiatsupaibul, Seksan; Hayter, Anthony J
2015-01-01
Given a sample X1,...,Xn of independent observations from an unknown continuous distribution function F, the problem of constructing a confidence band for F is considered, which is a fundamental problem in statistical inference. This confidence band provides simultaneous inferences on all quantiles and also on all of the cumulative probabilities of the distribution, and so they are among the most important inference procedures that address the issue of multiplicity. A fully nonparametric approach is taken where no assumptions are made about the distribution function F. Historical approaches to this problem, such as Kolmogorov's famous () procedure, represent some of the earliest inference methodologies that address the issue of multiplicity. This is because a confidence band at a given confidence level 1-α allows inferences on all of the quantiles of the distribution, and also on all of the cumulative probabilities, at that specified confidence level. In this paper it is shown how recursive methodologies can be employed to construct both one-sided and two-sided confidence bands of various types. The first approach operates by putting bounds on the cumulative probabilities at the data points, and a recursive integration approach is described. The second approach operates by providing bounds on certain specified quantiles of the distribution, and its implementation using recursive summations of multinomial probabilities is described. These recursive methodologies are illustrated with examples, and R code is available for their implementation.
Exponential wealth distribution : a new approach from functional iteration theory*
Directory of Open Access Journals (Sweden)
López José-Luis
2012-08-01
Full Text Available Different approaches are possible in order to derive the exponential regime in statistical systems. Here, a new functional equation is proposed in an economic context to explain the wealth exponential distribution. Concretely, the new iteration [1] given by egin{equation} f_{n+1}(x = int!!int_{u+v>x},{f_n(uf_n(vover u+v} ; {mathrm d}u{mathrm d}v ,. onumber label{syst1} end{equation} f n + 1 ( x = ∫ ∫ u + v > x f n ( u f n ( v u + v d u d v . It is found that the exponential distribution is a stable fixed point of this functional iteration equation. From this point of view, it is easily understood why the exponential wealth distribution (or by extension, other kind of distributions is asymptotically obtained in different multi-agent economic models. Différentes approches pour dériver le régime asymptotique exponentiel dans les systèmes statistiques sont possibles. Ici une nouvelle équation fonctionnelle est proposée, dans le cadre des systèmes économiques, pour expliquer la distribution exponentielle. Nous montrons que cette distribution est le seul point fixe vers lequel la dynamique de cette équation fonctionnelle évolue quand l’itération va vers l’infini. De ce point de vue, il est facile de comprendre l’ubiquité de cette distribution (ou d’autres en différents problèmes statistiques réels.
The transverse momentum dependent distribution functions in the bag model
Energy Technology Data Exchange (ETDEWEB)
Avakian, Harut; Efremov, Anatoly; Schweitzer, Peter; Yuan, Feng
2010-01-29
Leading and subleading twist transverse momentum dependent parton distribution functions (TMDs) are studied in a quark model framework provided by the bag model. A complete set of relations among different TMDs is derived, and the question is discussed how model-(in)dependent such relations are. A connection of the pretzelosity distribution and quark orbital angular momentum is derived. Numerical results are presented, and applications for phenomenology discussed. In particular, it is shown that in the valence-x region the bag model supports a Gaussian Ansatz for the transverse momentum dependence of TMDs.
Transverse momentum dependent distribution functions in the bag model
Energy Technology Data Exchange (ETDEWEB)
Avakian, Harut A. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Efremov, A. V. [Joint Inst. for Nuclear Research (JINR), Dubna (Russian Federation); Schweitzer, P. [Univ. of Connecticut, Storrs, CT (United States); Yuan, F. [Brookhaven National Lab. (BNL), Upton, NY (United States). RIKEN Research Center; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
2010-04-01
Leading and subleading twist transverse momentum dependent parton distribution functions (TMDs) are studied in a quark model framework provided by the bag model. A complete set of relations among different TMDs is derived, and the question is discussed how model-(in)dependent such relations are. A connection of the pretzelosity distribution and quark orbital angular momentum is derived. Numerical results are presented, and applications for phenomenology discussed. In particular, it is shown that in the valence-x region the bag model supports a Gaussian Ansatz for the transverse momentum dependence of TMDs.
Distribution function in the description of relaxation phenomena
DEFF Research Database (Denmark)
Brecht, M.; Klösgen, B.; Reichle, C.;
1999-01-01
with an exact Debye behaviour to be ascribed to the distinct species of different permanent electric dipoles, respectively, a separation into two or more single contributions of dispersion and absorption responses of the electric permittivity may prove to be unsatisfying. Instead, as for the interlamellar water...... adjacent to cell membranes, a distribution of correlation times has to be taken into account to describe the experimentally found additional line broadening in the absorption, the less steep slope in the dispersion curves and the loss of symmetry. Appropiate distribution functions are introduced...
Institute of Scientific and Technical Information of China (English)
N.Ghahramany; G.R.Boroun
2003-01-01
A calculation of the proton structure function F2(x,Q2) is reported with an approximation method that relates the reduced cross section derivative and the F2(x, Q2) scaling violation at low x by using quadratic form for the structure function. This quadratic form approximation method can be used to determine the structure function F2 (x, Q2) from the HERA reduced cross section data taken at low x. This new approach can determine the structure functions F2(x,Q2) with reasonable precision even for low x values which have not been investigated. We observe that the Q2 dependence is quadratic over the full kinematic covered range. To test the validity of our new determined structure functions, we find the gluon distribution function in the leading order approximation with our new calculation for the structure functions and compare them with the QCD parton distribution functions.
Institute of Scientific and Technical Information of China (English)
N. Ghahramany; G.R. Boroun
2003-01-01
A calculation of the proton structure function F2(x,Q2) is reported with an approximation method that relates the reduced cross section derivative and the F2(x, Q2) scaling violation at low x by using quadratic form for the structure function. This quadratic form approximation method can be used to determine the structure function F2 (x, Q2)from the HERA reduced cross section data taken at low x. This new approach can determine the structure functions F2(x,Q2) with reasonable precision even for low x values which have not been investigated. We observe that the Q2 dependence is quadratic over the full kinematic covered range. To test the validity of our new determined structure functions, wefind the gluon distribution function in the leading order approximation with our new calculation for the structure functions and compare them with the QCD parton distribution functions.
Specification of Density Functional Approximation by Radial Distribution Function of Bulk Fluid
Institute of Scientific and Technical Information of China (English)
ZHOU Shi-Qi
2002-01-01
A systematic methodology is proposed to deal with the weighted density approximation version of clas-sical density functional theory by employing the knowledge of radial distribution function of bulk fluid. The presentmethodology results from the concept of universality of the free energy density functional combined with the test particlemethod. It is shown that the new method is very accurate for the predictions of density distribution ofa hard sphere fluidat different confining geometries. The physical foundation of the present methodology is also applied to the quantumdensity functional theory.
Specification of Density Functional Approximation by Radial Distribution Function of Bulk Fluid
Institute of Scientific and Technical Information of China (English)
ZHOUShi－Qi
2002-01-01
A systematic methodology is proposed to deal with the weighted density approximation version of classical density functional theory by employing the knowledge of radial distribution function of bulk fluid.The present methodology results from the concept of universality of the free energy density functional combined with the test particle method.It is shown that the new method is very accurate for the predictions of density distribution of a hard sphere fluid at different confining geometries.The physical foundation of the present methodology is also applied to the quantum density functional theory.
Use of the Digamma Function in Statistical Astrophysics Distributions
Cahill, Michael
2017-06-01
Relaxed astrophysical statistical distributions may be constructed by using the inverse of a most probable energy distribution equation giving the energy ei of each particle in cell i in terms of the cell’s particle population Ni. The digamma mediated equation is A + Bei = Ψ(1+ Ni), where the constants A & B are Lagrange multipliers and Ψ is the digamma function given by Ψ(1+x) = dln(x!)/dx. Results are discussed for a Monatomic Ideal Gas, Atmospheres of Spherical Planets or Satellites and for Spherical Globular Clusters. These distributions are self-terminating even if other factors do not cause a cutoff. The examples are discussed classically but relativistic extensions are possible.
Transverse momentum-dependent parton distribution functions in lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Engelhardt, Michael G. [New Mexico State University; Musch, Bernhard U. [Tech. University Munich; Haegler, Philipp G. [Tech. University Munich; Negele, John W. [MIT; Schaefer, Andreas [Regensburg
2013-08-01
A fundamental structural property of the nucleon is the distribution of quark momenta, both parallel as well as perpendicular to its propagation. Experimentally, this information is accessible via selected processes such as semi-inclusive deep inelastic scattering (SIDIS) and the Drell-Yan process (DY), which can be parametrized in terms of transversemomentum-dependent parton distributions (TMDs). On the other hand, these distribution functions can be extracted from nucleon matrix elements of a certain class of bilocal quark operators in which the quarks are connected by a staple-shaped Wilson line serving to incorporate initial state (DY) or final state (SIDIS) interactions. A scheme for evaluating such matrix elements within lattice QCD is developed. This requires casting the calculation in a particular Lorentz frame, which is facilitated by a parametrization of the matrix elements in terms of invariant amplitudes. Exploratory results are presented for the time-reversal odd Sivers and Boer-Mulders transverse momentum shifts.
Confronting species distribution model predictions with species functional traits.
Wittmann, Marion E; Barnes, Matthew A; Jerde, Christopher L; Jones, Lisa A; Lodge, David M
2016-02-01
Species distribution models are valuable tools in studies of biogeography, ecology, and climate change and have been used to inform conservation and ecosystem management. However, species distribution models typically incorporate only climatic variables and species presence data. Model development or validation rarely considers functional components of species traits or other types of biological data. We implemented a species distribution model (Maxent) to predict global climate habitat suitability for Grass Carp (Ctenopharyngodon idella). We then tested the relationship between the degree of climate habitat suitability predicted by Maxent and the individual growth rates of both wild (N = 17) and stocked (N = 51) Grass Carp populations using correlation analysis. The Grass Carp Maxent model accurately reflected the global occurrence data (AUC = 0.904). Observations of Grass Carp growth rate covered six continents and ranged from 0.19 to 20.1 g day(-1). Species distribution model predictions were correlated (r = 0.5, 95% CI (0.03, 0.79)) with observed growth rates for wild Grass Carp populations but were not correlated (r = -0.26, 95% CI (-0.5, 0.012)) with stocked populations. Further, a review of the literature indicates that the few studies for other species that have previously assessed the relationship between the degree of predicted climate habitat suitability and species functional traits have also discovered significant relationships. Thus, species distribution models may provide inferences beyond just where a species may occur, providing a useful tool to understand the linkage between species distributions and underlying biological mechanisms.
Heavy-quark parton distribution functions and their uncertainties
Energy Technology Data Exchange (ETDEWEB)
Z. Sullivan and P.M. Nadolsky
2001-12-07
We investigate the uncertainties of the heavy-quark parton distribution functions in the variable avor number scheme. Because the charm- and bottom-quark parton distribution functions (PDFs) are constructed predominantly from the gluon PDF, it is a common practice to assume that the heavy-quark and gluon uncertainties are the same. We show that this approximation is a reasonable first guess, but it is better for bottom quarks than charm quarks. We calculate the PDF uncertainty for t-channel single-top-quark production using the Hessian matrix method, and predict a cross section of 2.12{sub -0.29}{sup +0.32} pb at run II of the Tevatron.
Intensity distribution function and statistical properties of fast radio bursts
Li, Long-Biao; Huang, Yong-Feng; Zhang, Zhi-Bin; Li, Di; Li, Bing
2017-01-01
Fast Radio Bursts (FRBs) are intense radio flashes from the sky that are characterized by millisecond durations and Jansky-level flux densities. We carried out a statistical analysis on FRBs that have been discovered. Their mean dispersion measure, after subtracting the contribution from the interstellar medium of our Galaxy, is found to be , supporting their being from a cosmological origin. Their energy released in the radio band spans about two orders of magnitude, with a mean value of erg. More interestingly, although the study of FRBs is still in a very early phase, the published collection of FRBs enables us to derive a useful intensity distribution function. For the 16 non-repeating FRBs detected by the Parkes telescope and the Green Bank Telescope, the intensity distribution can be described as , where is the observed radio fluence in units of Jy ms. Here the power-law index is significantly flatter than the expected value of 2.5 for standard candles distributed homogeneously in a flat Euclidean space. Based on this intensity distribution function, the Five-hundred-meter Aperture Spherical radio Telescope (FAST) is predicted to be able to detect about five FRBs for every 1000 h of observation time.
Automatic Functionality Assignment to AUTOSAR Multicore Distributed Architectures
DEFF Research Database (Denmark)
Maticu, Florin; Pop, Paul; Axbrink, Christian
2016-01-01
of better performance, cost, size, fault-tolerance and power consumption. In this paper we present an approach for the automatic software functionality assignment to multicore distributed architectures. We consider that the systems use the AUTomotive Open System ARchitecture (AUTOSAR). The functionality...... is modeled as a set of software components composed of subtasks, called runnables, in AUTOSAR terminology. We have proposed a Simulated Annealing metaheuristic optimization that decides: the (i) mapping of software components to multicore ECUs, (ii) the assignment of runnables to the ECU cores, (iii...
Distribution of a Certain Partition Function Modulo Powers of Primes
Institute of Scientific and Technical Information of China (English)
Hei-Chi CHAN
2011-01-01
In this paper, we study a certain partition function a(n) defined by Σn≥0 a(n)qn :=∏n=1(1-qn)-1(1-q2n)-1.We prove that given a positive integer j≥1 and a prime m≥5,there are infinitely many congruences of the type a(An + B)≡0 (mod mj). This work is inspired by Ono's ground breaking result in the study of the distribution of the partition function p(n).
Energy Technology Data Exchange (ETDEWEB)
Gamez-Mendoza, Liliana; Terban, Maxwell W.; Billinge, Simon J. L.; Martinez-Inesta, Maria
2017-04-13
The particle size of supported catalysts is a key characteristic for determining structure–property relationships. It is a challenge to obtain this information accurately and
Functional brain networks develop from a "local to distributed" organization.
Directory of Open Access Journals (Sweden)
Damien A Fair
2009-05-01
Full Text Available The mature human brain is organized into a collection of specialized functional networks that flexibly interact to support various cognitive functions. Studies of development often attempt to identify the organizing principles that guide the maturation of these functional networks. In this report, we combine resting state functional connectivity MRI (rs-fcMRI, graph analysis, community detection, and spring-embedding visualization techniques to analyze four separate networks defined in earlier studies. As we have previously reported, we find, across development, a trend toward 'segregation' (a general decrease in correlation strength between regions close in anatomical space and 'integration' (an increased correlation strength between selected regions distant in space. The generalization of these earlier trends across multiple networks suggests that this is a general developmental principle for changes in functional connectivity that would extend to large-scale graph theoretic analyses of large-scale brain networks. Communities in children are predominantly arranged by anatomical proximity, while communities in adults predominantly reflect functional relationships, as defined from adult fMRI studies. In sum, over development, the organization of multiple functional networks shifts from a local anatomical emphasis in children to a more "distributed" architecture in young adults. We argue that this "local to distributed" developmental characterization has important implications for understanding the development of neural systems underlying cognition. Further, graph metrics (e.g., clustering coefficients and average path lengths are similar in child and adult graphs, with both showing "small-world"-like properties, while community detection by modularity optimization reveals stable communities within the graphs that are clearly different between young children and young adults. These observations suggest that early school age children and adults
Distribution-Independent Evolvability of Linear Threshold Functions
Feldman, Vitaly
2011-01-01
Valiant's (2007) model of evolvability models the evolutionary process of acquiring useful functionality as a restricted form of learning from random examples. Linear threshold functions and their various subclasses, such as conjunctions and decision lists, play a fundamental role in learning theory and hence their evolvability has been the primary focus of research on Valiant's framework (2007). One of the main open problems regarding the model is whether conjunctions are evolvable distribution-independently (Feldman and Valiant, 2008). We show that the answer is negative. Our proof is based on a new combinatorial parameter of a concept class that lower-bounds the complexity of learning from correlations. We contrast the lower bound with a proof that linear threshold functions having a non-negligible margin on the data points are evolvable distribution-independently via a simple mutation algorithm. Our algorithm relies on a non-linear loss function being used to select the hypotheses instead of 0-1 loss in V...
A density functional for liquid {sup 4}He including the pair distribution function
Energy Technology Data Exchange (ETDEWEB)
Szybisz, Leszek [Laboratorio TANDAR, Departamento de Fisica, Comision Nacional de Energia Atomica, Av. del Libertador 8250, RA-1429 Buenos Aires (Argentina) and Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, RA-1428 Buenos Aires (Argentina) and Consejo Nacional de Investigaciones Cientificas y Tecnicas, Av. Rivadavia 1917, RA-1033 Buenos Aires (Argentina)]. E-mail: szybisz@tandar.cnea.gov.ar; Urrutia, Ignacio [Laboratorio TANDAR, Departamento de Fisica, Comision Nacional de Energia Atomica, Av. del Libertador 8250, RA-1429 Buenos Aires (Argentina) and Comision de Investigaciones Cientificas de la Prov. de Buenos Aires, Calle 526 entre 10 y 11, RA-1900 La Plata (Argentina)]. E-mail: iurrutia@cnea.gov.ar
2005-04-25
A new semi-microscopic functional for studying adsorption of {sup 4}He on solid surfaces is presented. In this proposal the helium-helium interaction is screened at small distances by the pair distribution function g(r) and, in addition, the contribution which plays an important role in the interpretation of the experimental static response function is written in terms of the gradient of g(r). This functional reproduces the usual test properties. Moreover, a detailed comparison with results of the Orsay-Trento density functional is performed.
Improving Project Management with Simulation and Completion Distribution Functions
Cates, Grant R.
2004-01-01
Despite the critical importance of project completion timeliness, management practices in place today remain inadequate for addressing the persistent problem of project completion tardiness. A major culprit in late projects is uncertainty, which most, if not all, projects are inherently subject to. This uncertainty resides in the estimates for activity durations, the occurrence of unplanned and unforeseen events, and the availability of critical resources. In response to this problem, this research developed a comprehensive simulation based methodology for conducting quantitative project completion time risk analysis. It is called the Project Assessment by Simulation Technique (PAST). This new tool enables project stakeholders to visualize uncertainty or risk, i.e. the likelihood of their project completing late and the magnitude of the lateness, by providing them with a completion time distribution function of their projects. Discrete event simulation is used within PAST to determine the completion distribution function for the project of interest. The simulation is populated with both deterministic and stochastic elements. The deterministic inputs include planned project activities, precedence requirements, and resource requirements. The stochastic inputs include activity duration growth distributions, probabilities for events that can impact the project, and other dynamic constraints that may be placed upon project activities and milestones. These stochastic inputs are based upon past data from similar projects. The time for an entity to complete the simulation network, subject to both the deterministic and stochastic factors, represents the time to complete the project. Repeating the simulation hundreds or thousands of times allows one to create the project completion distribution function. The Project Assessment by Simulation Technique was demonstrated to be effective for the on-going NASA project to assemble the International Space Station. Approximately $500
Measurement and application of bidirectional reflectance distribution function
Liao, Fei; Li, Lin; Lu, Chengwen
2016-10-01
When a beam of light with certain intensity and distribution reaches the surface of a material, the distribution of the diffused light is related to the incident angle, the receiving angle, the wavelength of the light and the types of the material. Bidirectional Reflectance Distribution Function (BRDF) is a method to describe this distribution. For an optical system, the optical and mechanical materials' BRDF are unique, and if we want to calculate stray light of the system we should know the correct BRDF data of the whole materials. There are fundamental significances in the area of space remote sensor where BRDF is needed in the precise radiation calibration. It is also important in the military field where BRDF can be used in the object identification and target tracking, etc. In this paper, 11 kinds of aerospace materials' BRDF are measured and more than 310,000 groups of BRDF data are achieved , and also a BRDF database is established in China for the first time. With the BRDF data of the database, we can create the detector model, build the stray light radiation surface model in the stray light analysis software. In this way, the stray radiation on the detector can be calculated correctly.
Network Packet Length Covert Channel Based on Empirical Distribution Function
Directory of Open Access Journals (Sweden)
Lihua Zhang
2014-06-01
Full Text Available Network packet length covert channel modulates secret message bits onto the packet lengths to transmit secret messages. In this paper, a novel network packet length covert channel is proposed. The proposed scheme is based on the empirical distribution function of packet length series of legitimate traffic. Different from the existing schemes, the lengths of packets which are generated by the covert sender follow the distribution of normal traffic more closely in our scheme. To validate the security of the proposed scheme, the state-of-the-art packet length covert channel detection algorithm is adopted. The experimental results show that the packet length covert channel provides a significant performance improvement in detection resistance meanings
Parton distribution functions in Monte Carlo factorisation scheme
Jadach, S.; Płaczek, W.; Sapeta, S.; Siódmok, A.; Skrzypek, M.
2016-12-01
A next step in development of the KrkNLO method of including complete NLO QCD corrections to hard processes in a LO parton-shower Monte Carlo is presented. It consists of a generalisation of the method, previously used for the Drell-Yan process, to Higgs-boson production. This extension is accompanied with the complete description of parton distribution functions in a dedicated, Monte Carlo factorisation scheme, applicable to any process of production of one or more colour-neutral particles in hadron-hadron collisions.
A distribution-function-valued SPDE and its applications
Wang, Li; Yang, Xu; Zhou, Xiaowen
2017-01-01
In this paper we further study the stochastic partial differential equation first proposed by Xiong [22]. Under localized conditions on its coefficients, we prove a comparison theorem on its solutions and show that the solution is in fact distribution-function-valued. We also establish pathwise uniqueness of the solution. As applications we obtain the well-posedness of martingale problems for two classes of measure-valued diffusions: interacting super-Brownian motions and interacting Fleming-Viot processes. Properties of the two superprocesses such as the existence of density fields and the survival-extinction behaviors are also studied.
A global reanalysis of nuclear parton distribution functions
Eskola, Kari J.; Kolhinen, Vesa J.; Paukkunen, Hannu; Salgado, Carlos A.
2007-05-01
We determine the nuclear modifications of parton distribution functions of bound protons at scales Q2 >= 1.69 GeV2 and momentum fractions 10-5 BRAHMS data for inclusive hadron production in d+Au collisions lend support for a stronger gluon shadowing at x < 0.01 and also that fairly large changes in the gluon modifications do not rapidly deteriorate the goodness of the overall fits, as long as the initial gluon modifications in the region x ~ 0.02-0.04 remain small.
Statistical effect in the parton distribution functions of the nucleon
Zhang, Yunhua; Ma, Bo-Qiang
2008-01-01
A new and simple statistical approach is performed to calculate the parton distribution functions (PDFs) of the nucleon in terms of light-front kinematic variables. We do not put in any extra arbitrary parameter or corrected term by hand, which guarantees the stringency of our approach. Analytic expressions of the $x$-dependent PDFs are obtained in the whole $x$ region [0,1], and some features, especially the low-$x$ rise, are more agreeable with experimental data than those in some previous instant-form statistical models in the infinite-momentum frame (IMF). Discussions on heavy-flavored PDFs are also presented.
Moments of meson distribution functions with dynamical twisted mass fermions
Baron, R; Carbonell, J; Jansen, K; Liu, Z; Pène, O; Urbach, C
2007-01-01
We present our preliminary results on the lowest moment of quark distribution functions of the pion using two flavor dynamical simulations with Wilson twisted mass fermions at maximal twist. The calculation is done in a range of pion masses from 300 to 500 MeV. A stochastic source method is used to reduce inversions in calculating propagators. Finite volume effects at the lowest quark mass are examined by using two different lattice volumes. Our results show that we achieve statistical errors of only a few percent. We plan to compute renormalization constants non-perturbatively and extend the calculation to two more lattice spacings and to the nucleons.
Transfer function modeling of damping mechanisms in distributed parameter models
Slater, J. C.; Inman, D. J.
1994-01-01
This work formulates a method for the modeling of material damping characteristics in distributed parameter models which may be easily applied to models such as rod, plate, and beam equations. The general linear boundary value vibration equation is modified to incorporate hysteresis effects represented by complex stiffness using the transfer function approach proposed by Golla and Hughes. The governing characteristic equations are decoupled through separation of variables yielding solutions similar to those of undamped classical theory, allowing solution of the steady state as well as transient response. Example problems and solutions are provided demonstrating the similarity of the solutions to those of the classical theories and transient responses of nonviscous systems.
The role of the Wigner distribution function in iterative ptychography
Edo, Tega Boro
2015-01-01
Ptychography employs a set of diffraction patterns that capture redundant information about an illuminated specimen as a localized beam is moved over the specimen. The robustness of this method comes from the redundancy of the dataset that in turn depends on the amount of oversampling and the form of the illumination. Although the role of oversampling in ptychography is fairly well understood, the same cannot be said of the illumination structure. This paper provides a vector space model of ptychography that accounts for the illumination structure in a way that highlights the role of the Wigner distribution function in iterative ptychography.
Relativistic effects in model calculations of double parton distribution function
Rinaldi, Matteo
2016-01-01
In this paper we consider double parton distribution functions (dPDFs) which are the main non perturbative ingredients appearing in the double parton scattering cross section formula in hadronic collisions. By using recent calculation of dPDFs by means of constituent quark models within the so called Light-Front approach, we investigate the role of relativistic effects on dPDFs. We find, in particular, that the so called Melosh operators, which allow to properly convert the LF spin into the canonical one and incorporate a proper treatment of boosts, produce sizeable effects on dPDFs. We discuss specific partonic correlations induced by these operators in transverse plane which are relevant to the proton structure and study under which conditions these results are stable against variations in the choice of the proton wave function.
ManeParse : A Mathematica reader for Parton Distribution Functions
Clark, D. B.; Godat, E.; Olness, F. I.
2017-07-01
Parton Distribution Functions (PDFs) are essential non-perturbative inputs for calculation of any observable with hadronic initial states. These PDFs are released by individual groups as discrete grids as a function of the Bjorken- x and energy scale Q. The LHAPDF project maintains a repository of PDFs from various groups in a new standardized LHAPDF6 format, additionally older formats such as the CTEQ PDS grid format are still in use. ManeParse is a package that provides access to PDFs within Mathematica to facilitate calculation and plotting. The program is self-contained so there are no external links to any FORTRAN, C or C++ programs. The package includes the option to use the built-in Mathematica interpolation or a custom cubic Lagrange interpolation routine which allows for flexibility in the extrapolation (particularly at small x-values). ManeParse is fast enough to enable simple calculations (involving even one or two integrations) in the Mathematica framework.
Proton structure and parton distribution functions from HERA
Directory of Open Access Journals (Sweden)
Chekelian Vladimir
2016-01-01
Full Text Available The H1 and ZEUS collaborations at the electron-proton collider HERA collected e± p scattering data corresponding to an integrated luminosity of about 1 fb−1. The data were taken at proton beam energies of 920, 820, 575 and 460 GeV and an electron beam energy of 27.5 GeV, with different electric charges and longitudinal polarisation of the electron beam. Using these data inclusive neutral and charged current deep inelastic cross sections were measured over six orders of magnitude in negative four-momentum-transfer squared, Q2, and Bjorken x. A combination of all inclusive cross sections, published by the H1 and ZEUS collaborations at HERA, was performed. Using these combined HERA data and the individual H1 and ZEUS data taken using the polarised electron beams, the proton structure functions F2, FγZ2, xFγZ3 and FL were obtained, and scaling violations, electroweak unification, and polarisation effects in the charged current process were demonstrated. The combined cross sections were used as a sole input to QCD analyses at leading, next-to-leading and next-to-next-to-leading orders, providing a new set of parton distribution functions, denoted as HERAPDF2.0. An extension of the analysis by including HERA data on charm and jet production allowed a simultaneous determination of parton distributions and the strong coupling.
Mass sensitivity in the radio lateral distribution function
Apel, W D; Bähren, L; Bekk, K; Bertaina, M; Biermann, P L; Blümer, J; Bozdog, H; Brancus, I M; Buchholz, P; Cantoni, E; Chiavassa, A; Daumiller, K; de Souza, V; Di Pierro, F; Doll, P; Engel, R; Falcke, H; Finger, M; Fuchs, B; Fuhrmann, D; Gemmeke, H; Grupen, C; Haungs, A; Heck, D; Hörandel, J R; Horneffer, A; Huber, D; Huege, T; Isar, P G; Kampert, K H; Kang, D; Krömer, O; Kuijpers, J; Link, K; Łuczak, P; Ludwig, M; Mathes, H J; Melissas, M; Morello, C; Oehlschläger, J; Palmieri, N; Pierog, T; Rautenberg, J; Rebel, H; Roth, M; Rühle, C; Saftoiu, A; Schieler, H; Schmid, A; Schröder, F G; Sima, O; Toma, G; Trinchero, G C; Weindl, A; Wochele, J; Wommer, M; Zabierowski, J; Zensus, J A
2013-01-01
Measuring the mass composition of ultra-high energy cosmic rays is one of the main tasks in the cosmic rays field. Here we are exploring the composition signature in the coherent electromagnetic emission from extensive air showers, detected in the MHz frequency range. One of the experiments that successfully detects radio events in the frequency band of 40-80 MHz is the LOPES experiment at KIT. It is a digital interferometric antenna array and has the important advantage of taking data in coincidence with the particle detector array KASCADE-Grande. A possible method to look at the composition signature in the radio data, predicted by simulations, concerns the radio lateral distribution function, since its slope is strongly correlated with Xmax. Recent comparison between REAS3 simulations and LOPES data showed a significantly improved agreement in the lateral distribution function and for this reason an analysis on a possible LOPES mass signature through the slope method is promising. Trying to reproduce a rea...
A meta-analysis of parton distribution functions
Gao, Jun; Nadolsky, Pavel
2014-07-01
A "meta-analysis" is a method for comparison and combination of nonperturbative parton distribution functions (PDFs) in a nucleon obtained with heterogeneous procedures and assumptions. Each input parton distribution set is converted into a "meta-parametrization" based on a common functional form. By analyzing parameters of the meta-parametrizations from all input PDF ensembles, a combined PDF ensemble can be produced that has a smaller total number of PDF member sets than the original ensembles. The meta-parametrizations simplify the computation of the PDF uncertainty in theoretical predictions and provide an alternative to the 2010 PDF4LHC convention for combination of PDF uncertainties. As a practical example, we construct a META ensemble for computation of QCD observables at the Large Hadron Collider using the next-to-next-to-leading order PDF sets from CTEQ, MSTW, and NNPDF groups as the input. The META ensemble includes a central set that reproduces the average of LHC predictions based on the three input PDF ensembles and Hessian eigenvector sets for computing the combined PDF+α s uncertainty at a common QCD coupling strength of 0.118.
The impact of intrinsic charm on the parton distribution functions
Aleedaneshvar, Alireza; Goharipour, Muhammad; Rostami, Saeedeh
2016-12-01
In this work, we present a new investigation about the impact of intrinsic charm (IC) on the physical observables, in particular, on the heavy structure function F2c. Since the IC distribution is dominant at large Bjorken variable x, normally, it is expected that it can be explored only at large x. But, by studying the correlation of the charm density in the proton with F2c, we are going to show that the IC component can also be effective at low x. To investigate further, we perform three QCD global analyses of parton distribution functions (PDFs), by including the EMC F2c data that are recognized as a clear evidence for the existence of the intrinsic charm in the proton, and also by considering the IC component. Although the fit of the EMC data is extremely poor due to the data points with lower x-values, i.e. x EMC data and IC contribution on the behaviour of PDFs.
The impact of intrinsic charm on the parton distribution functions
Aleedaneshvar, Alireza; Rostami, Saeedeh
2016-01-01
In this work, we present a new investigation about the impact of intrinsic charm (IC) on the physical observables, in particular, on the heavy structure function $F_2^c$. Since IC distribution is dominant at large Bjorken variable $x$, normally, it is expected that it can be explored only at large $x$. But, by studying the correlation of the charm density in the proton with $F_2^c$, we are going to show that the IC component can also be effective at low $x$. To investigate further, we perform three QCD global analyses of parton distribution functions (PDFs), by including the EMC $F_2^c$ data that are recognized as clear evidence for existence of the intrinsic charm in the proton, and also by considering the IC component. Although the fit of the EMC data is extremely poor due to the data points with lower $x$ values, i.e. $x< $0.05, but these analyses can give us new information about the impact of EMC data and IC contribution on the behaviour of PDFs.
A meta-analysis of parton distribution functions
Gao, Jun
2014-01-01
A "meta-analysis" is a method for comparison and combination of nonperturbative parton distribution functions (PDFs) in a nucleon obtained with heterogeneous procedures and assumptions. Each input parton distribution set is converted into a "meta-parametrization" based on a common functional form. By analyzing parameters of the meta-parametrizations from all input PDF ensembles, a combined PDF ensemble can be produced that has a smaller total number of PDF member sets than the original ensembles. The meta-parametrizations simplify the computation of the PDF uncertainty in theoretical predictions and provide an alternative to the 2010 PDF4LHC convention for combination of PDF uncertainties. As a practical example, we construct a META ensemble for computation of QCD observables at the Large Hadron Collider using the next-to-next-to-leading order PDF sets from CTEQ, MSTW, and NNPDF groups as the input. The META ensemble includes a central set that reproduces the average of LHC predictions based on the three inpu...
A pseudo zeta function and the distribution of primes.
Chernoff, P R
2000-07-05
The Riemann zeta function is given by: [equation, see published text]. Zeta(s) may be analytically continued to the entire s-plane, except for a simple pole at s = 0. Of great interest are the complex zeros of zeta(s). The Riemann hypothesis states that the complex zeros all have real part 1/2. According to the prime number theorem, pn approximately n logn, where pn is the nth prime. Suppose that pn were exactly nlogn. In other words, in the Euler product above, replace the nth prime by nlogn. In this way, we define a pseudo zeta function C(s) for Re s > 1. One can show that C(s) may be analytically continued at least into the half-plane Re s > 0 except for an isolated singularity (presumably a simple pole) at s = 0. It may be shown that the pseudo zeta function C(s) has no complex zeros whatsoever. This means that the complex zeros of the zeta function are associated with the irregularity of the distribution of the primes.
Universal functional form of 1-minute raindrop size distribution?
Cugerone, Katia; De Michele, Carlo
2015-04-01
Rainfall remains one of the poorly quantified phenomena of the hydrological cycle, despite its fundamental role. No universal laws describing the rainfall behavior are available in literature. This is probably due to the continuous description of rainfall, which is a discrete phenomenon, made by drops. From the statistical point of view, the rainfall variability at particle size scale, is described by the drop size distribution (DSD). With this term, it is generally indicated as the concentration of raindrops per unit volume and diameter, as the probability density function of drop diameter at the ground, according to the specific problem of interest. Raindrops represent the water exchange, under liquid form, between atmosphere and earth surface, and the number of drops and their size have impacts in a wide range of hydrologic, meteorologic, and ecologic phenomena. DSD is used, for example, to measure the multiwavelength rain attenuation for terrestrial and satellite systems, it is an important input for the evaluation of the below cloud scavenging coefficient of the aerosol by precipitation, and is of primary importance to make estimates of rainfall rate through radars. In literature, many distributions have been used to this aim (Gamma and Lognormal above all), without statistical supports and with site-specific studies. Here, we present an extensive investigation of raindrop size distribution based on 18 datasets, consisting in 1-minute disdrometer data, sampled using Joss-Waldvogel or Thies instrument in different locations on Earth's surface. The aim is to understand if an universal functional form of 1-minute drop diameter variability exists. The study consists of three main steps: analysis of the high order moments, selection of the model through the AIC index and test of the model with the use of goodness-of-fit tests.
Efficient Incremental Maintenance for Distributive and Non-Distributive Aggregate Functions
Institute of Scientific and Technical Information of China (English)
Cui-Ping Li; Shan Wang
2006-01-01
Data cube pre-computation is an important concept for supporting OLAP (Online Analytical Processing) and has been studied extensively. It is often not feasible to compute a complete data cube due to the huge storage requirement.Recently proposed quotient cube addressed this issue through a partitioning method that groups cube cells into equivalence partitions. Such an approach not only is useful for distributive aggregate functions such as SUM but also can be applied to the maintenance of holistic aggregate functions like MEDIAN which will require the storage of a set of tuples for each equivalence class. Unfortunately, as changes are made to the data sources, maintaining the quotient cube is non-trivial since the partitioning of the cube cells must also be updated. In this paper, the authors design incremental algorithms to update a quotient cube efficiently for both SUM and MEDIAN aggregate functions. For the aggregate function SUM, concepts are borrowed from the principle of Galois Lattice to develop CPU-efficient algorithms to update a quotient cube. For the aggregate function MEDIAN, the concept of a pseudo class is introduced to further reduce the size of the quotient cube.Coupled with a novel sliding window technique, an efficient algorithm is developed for maintaining a MEDIAN quotient cube that takes up reasonably small storage space. Performance study shows that the proposed algorithms are efficient and scalable over large databases.
Beyond Flory theory: Distribution functions for interacting lattice trees
Rosa, Angelo; Everaers, Ralf
2017-01-01
While Flory theories [J. Isaacson and T. C. Lubensky, J. Physique Lett. 41, 469 (1980), 10.1051/jphyslet:019800041019046900; M. Daoud and J. F. Joanny, J. Physique 42, 1359 (1981), 10.1051/jphys:0198100420100135900; A. M. Gutin et al., Macromolecules 26, 1293 (1993), 10.1021/ma00058a016] provide an extremely useful framework for understanding the behavior of interacting, randomly branching polymers, the approach is inherently limited. Here we use a combination of scaling arguments and computer simulations to go beyond a Gaussian description. We analyze distribution functions for a wide variety of quantities characterizing the tree connectivities and conformations for the four different statistical ensembles, which we have studied numerically in [A. Rosa and R. Everaers, J. Phys. A: Math. Theor. 49, 345001 (2016), 10.1088/1751-8113/49/34/345001 and J. Chem. Phys. 145, 164906 (2016), 10.1063/1.4965827]: (a) ideal randomly branching polymers, (b) 2 d and 3 d melts of interacting randomly branching polymers, (c) 3 d self-avoiding trees with annealed connectivity, and (d) 3 d self-avoiding trees with quenched ideal connectivity. In particular, we investigate the distributions (i) pN(n ) of the weight, n , of branches cut from trees of mass N by severing randomly chosen bonds; (ii) pN(l ) of the contour distances, l , between monomers; (iii) pN(r ⃗) of spatial distances, r ⃗, between monomers, and (iv) pN(r ⃗|l ) of the end-to-end distance of paths of length l . Data for different tree sizes superimpose, when expressed as functions of suitably rescaled observables x ⃗=r ⃗/√{ } or x =l / . In particular, we observe a generalized Kramers relation for the branch weight distributions (i) and find that all the other distributions (ii-iv) are of Redner-des Cloizeaux type, q (x ⃗) =C |x| θexp(-(K|x |) t) . We propose a coherent framework, including generalized Fisher-Pincus relations, relating most of the RdC exponents to each other and to the contact and Flory
Energy Technology Data Exchange (ETDEWEB)
Kantar, Yeliz Mert; Usta, Ilhan [Department of Statistics, Anadolu University, Eskisehir 26470 (Turkey)
2008-05-15
In this study, the minimum cross entropy (MinxEnt) principle is applied for the first time to the wind energy field. This principle allows the inclusion of previous information of a wind speed distribution and covers the maximum entropy (MaxEnt) principle, which is also discussed by Li and Li and Ramirez as special cases in their wind power study. The MinxEnt probability density function (pdf) derived from the MinxEnt principle are used to determine the diurnal, monthly, seasonal and annual wind speed distributions. A comparison between MinxEnt pdfs defined on the basis of the MinxEnt principle and the Weibull pdf on wind speed data, which are taken from different sources and measured in various regions, is conducted. The wind power densities of the considered regions obtained from Weibull and MinxEnt pdfs are also compared. The results indicate that the pdfs derived from the MinxEnt principle fit better to a variety of measured wind speed data than the conventionally applied empirical Weibull pdf. Therefore, it is shown that the MinxEnt principle can be used as an alternative method to estimate both wind distribution and wind power accurately. (author)
The force distribution probability function for simple fluids by density functional theory.
Rickayzen, G; Heyes, D M
2013-02-28
Classical density functional theory (DFT) is used to derive a formula for the probability density distribution function, P(F), and probability distribution function, W(F), for simple fluids, where F is the net force on a particle. The final formula for P(F) ∝ exp(-AF(2)), where A depends on the fluid density, the temperature, and the Fourier transform of the pair potential. The form of the DFT theory used is only applicable to bounded potential fluids. When combined with the hypernetted chain closure of the Ornstein-Zernike equation, the DFT theory for W(F) agrees with molecular dynamics computer simulations for the Gaussian and bounded soft sphere at high density. The Gaussian form for P(F) is still accurate at lower densities (but not too low density) for the two potentials, but with a smaller value for the constant, A, than that predicted by the DFT theory.
Polarized reflectance and transmittance distribution functions of the ocean surface.
Hieronymi, Martin
2016-07-11
Two aspects of ocean modelling are treated: representation of ocean waves considering all size-classes of waves and tracing of light-interactions at the wavy sea surface. Nonlinear wave profiles are realized accounting for a wide range of climatologically relevant sea states and wind speeds. Polarized ray tracing is used to investigate air-incident and whitecap-free reflectance and transmittance distributions with high angular resolution subject to sea-characterizing parameters, such as significant wave height, peak wave period, wind speed, and surface roughness. Wave-shadowing effects of incident and multiple reflected rays are fully considered. Their influence mostly starts with incidence angles greater than 60°, i.e., when the sun is near the horizon, and is especially pronounced for steep sea states. The net effect of multiple reflections is a redistribution of reflectance and transmittance fractions in their respective hemispheres and a slight increase of the net transmission of light into the sea. Revised reflectance and transmittance distribution functions, RDF and TDF, are provided depending on surface roughness in terms of the mean-square slope; reference is made to other sea state parameters. In comparison with the slope statistics approach, uncertainties related to sun near the horizon are reduced and on average this study yields somewhat higher reflectance values with some variability related to the sea state. By means of provided data, irradiance and radiance reflectances can be computed using desired sky radiance distributions, e.g., clear sky, overcast or partly cloudy sky, as well as wind or sea state information including wave propagation direction.
Characterizing the \\lyaf\\ flux probability distribution function using Legendre polynomials
Cieplak, Agnieszka M
2016-01-01
The Lyman-$\\alpha$ forest is a highly non-linear field with a lot of information available in the data beyond the power spectrum. The flux probability distribution function (PDF) has been used as a successful probe of small-scale physics. In this paper we argue that measuring coefficients of the Legendre polyonomial expansion of the PDF offers several advantages over measuring the binned values as is commonly done. In particular, $n$-th coefficient can be expressed as a linear combination of the first $n$ moments, allowing these coefficients to be measured in the presence of noise and allowing a clear route for marginalisation over mean flux. Moreover, in the presence of noise, our numerical work shows that a finite number of coefficients are well measured with very sharp transition into noise dominance. This compresses the available information into a small number of well-measured quantities.
Smooth conditional distribution function and quantiles under random censorship.
Leconte, Eve; Poiraud-Casanova, Sandrine; Thomas-Agnan, Christine
2002-09-01
We consider a nonparametric random design regression model in which the response variable is possibly right censored. The aim of this paper is to estimate the conditional distribution function and the conditional alpha-quantile of the response variable. We restrict attention to the case where the response variable as well as the explanatory variable are unidimensional and continuous. We propose and discuss two classes of estimators which are smooth with respect to the response variable as well as to the covariate. Some simulations demonstrate that the new methods have better mean square error performances than the generalized Kaplan-Meier estimator introduced by Beran (1981) and considered in the literature by Dabrowska (1989, 1992) and Gonzalez-Manteiga and Cadarso-Suarez (1994).
Measurement of bidirectional reflection distribution function on material surface
Institute of Scientific and Technical Information of China (English)
Wei Zhang; Hongyuan Wang; Zhile Wang
2009-01-01
Two automatic measurement methods of bidirectional reflection distribution function (BRDF) are pre sented based on absolute and relative definition. Measurement principle and scheme of the methods are analyzed. A real-time measurement device is developed, the measurement spectral range of which is from ultraviolet to near infrared with 2.4-nm wavelength resolution, and the angular range is 0掳鈥? 360掳 in az imuth angle and 0掳 - 85掳 in zenith angle with 0.01掳 angle resolution. Absolute measurements of BRDF on tinfoil and ceramic tile are performed and the test materials present apparent specular reflection char acteristics. The theoretical error in the experiment is about 6.05%. The BRDF measurement results are closely related to the precision of measurement platform, the sensitivity of measurement instrument, and the stability of illuminating light source.
From Bethe-Salpeter Wave functions to Generalised Parton Distributions
Mezrag, C.; Moutarde, H.; Rodríguez-Quintero, J.
2016-09-01
We review recent works on the modelling of generalised parton distributions within the Dyson-Schwinger formalism. We highlight how covariant computations, using the impulse approximation, allows one to fulfil most of the theoretical constraints of the GPDs. Specific attention is brought to chiral properties and especially the so-called soft pion theorem, and its link with the Axial-Vector Ward-Takahashi identity. The limitation of the impulse approximation are also explained. Beyond impulse approximation computations are reviewed in the forward case. Finally, we stress the advantages of the overlap of lightcone wave functions, and possible ways to construct covariant GPD models within this framework, in a two-body approximation.
From Bethe-Salpeter Wave Functions to Generalised Parton Distributions
Mezrag, C; Rodriguez-Quintero, J
2016-01-01
We review recent works on the modelling of Generalised Parton Distributions within the Dyson-Schwinger formalism. We highlight how covariant computations, using the impulse approximation, allows one to fulfil most of the theoretical constraints of the GPDs. Specific attention is brought to chiral properties and especially the so-called soft pion theorem, and its link with the Axial-Vector Ward-Takahashi identity. The limitation of the impulse approximation are also explained. Beyond impulse approximation computations are reviewed in the forward case. Finally, we stress the advantages of the overlap of lightcone wave functions, and possible ways to construct covariant GPD models within this framework, in a two-body approximation.
Basic features of the pion valence-quark distribution function
Directory of Open Access Journals (Sweden)
Lei Chang
2014-10-01
Full Text Available The impulse-approximation expression used hitherto to define the pion's valence-quark distribution function is flawed because it omits contributions from the gluons which bind quarks into the pion. A corrected leading-order expression produces the model-independent result that quarks dressed via the rainbow–ladder truncation, or any practical analogue, carry all the pion's light-front momentum at a characteristic hadronic scale. Corrections to the leading contribution may be divided into two classes, responsible for shifting dressed-quark momentum into glue and sea-quarks. Working with available empirical information, we use an algebraic model to express the principal impact of both classes of corrections. This enables a realistic comparison with experiment that allows us to highlight the basic features of the pion's measurable valence-quark distribution, qπ(x; namely, at a characteristic hadronic scale, qπ(x∼(1−x2 for x≳0.85; and the valence-quarks carry approximately two-thirds of the pion's light-front momentum.
Impact of QED radiative corrections on Parton Distribution Functions
Sadykov, Renat
2014-01-01
The level of precision achieved by the experimental measurements at the LHC requires the inclusion of higher order electroweak effects to the processes of $ pp $ scattering. In particular the photon-induced process $ \\gamma\\gamma \\to \\ell^+\\ell^- $ make a significant contribution ($ \\sim 10 \\%$) to the dilepton invariant mass distribution. To evaluate the cross-section of this process one need to know the parton distribution function (PDF) of the photon in the proton $ \\gamma (x,\\mu^2) $. The aim of the current study is to investigate the impact of QED corrections on PDFs and describe the implementation of QED-modified evolution equations into beta release of new version of {\\tt QCDNUM} program. The {\\tt APPLGRID} interface to {\\tt SANC} Monte Carlo generator for fast evaluation of photon-induced cross-section is also outlined. The results were cross-checked with {\\tt partonevolution} program, {\\tt MRST2004QED} PDF set and {\\tt APFEL} program. The described developments are planned to include into {\\tt HERAFi...
Insights from probability distribution functions of intensity maps
Breysse, Patrick C; Behroozi, Peter S; Dai, Liang; Kamionkowski, Marc
2016-01-01
In the next few years, intensity-mapping surveys that target lines such as CO, Ly$\\alpha$, and CII stand to provide powerful probes of high-redshift astrophysics. However, these line emissions are highly non-Gaussian, and so the typical power-spectrum methods used to study these maps will leave out a significant amount of information. We propose a new statistic, the probability distribution of voxel intensities, which can access this extra information. Using a model of a CO intensity map at $z\\sim3$ as an example, we demonstrate that this voxel intensity distribution (VID) provides substantial constraining power beyond what is obtainable from the power spectrum alone. We find that a future survey similar to the planned COMAP Full experiment could constrain the CO luminosity function to order $\\sim10\\%$. We also explore the effects of contamination from continuum emission, interloper lines, and gravitational lensing on our constraints and find that the VID statistic retains significant constraining power even ...
Indian Academy of Sciences (India)
U Jamil; J K Sarma
2008-09-01
Evolution of gluon distribution function from Dokshitzer–Gribov–Lipatov–Altarelli–Parisi (DGLAP) evolution equation in next-to-leading order (NLO) at low- is presented assuming the Regge behaviour of quark and gluon at this limit. We compare our results of gluon distribution function with MRST2004, GRV98LO and GRV98NLO parametrizations and show the compatibility of Regge behaviour of quark and gluon distribution functions with perturbative quantum chromodynamics (PQCD) at low-.
Energy Technology Data Exchange (ETDEWEB)
Ramirez-Guinart, Oriol; Rigol, Anna; Vidal, Miquel [Analytical Chemistry department, Faculty of Chemistry, University of Barcelona, Mart i Franques 1-11, 08028, Barcelona (Spain)
2014-07-01
In the frame of the revision of the IAEA TRS 364 (Handbook of parameter values for the prediction of radionuclide transfer in temperate environments), a database of radionuclide solid-liquid distribution coefficients (K{sub d}) in soils was compiled with data coming from field and laboratory experiments, from references mostly from 1990 onwards, including data from reports, reviewed papers, and grey literature. The K{sub d} values were grouped for each radionuclide according to two criteria. The first criterion was based on the sand and clay mineral percentages referred to the mineral matter, and the organic matter (OM) content in the soil. This defined the 'texture/OM' criterion. The second criterion was to group soils regarding specific soil factors governing the radionuclide-soil interaction ('cofactor' criterion). The cofactors depended on the radionuclide considered. An advantage of using cofactors was that the variability of K{sub d} ranges for a given soil group decreased considerably compared with that observed when the classification was based solely on sand, clay and organic matter contents. The K{sub d} best estimates were defined as the calculated GM values assuming that K{sub d} values were always log-normally distributed. Risk assessment models may require as input data for a given parameter either a single value (a best estimate) or a continuous function from which not only individual best estimates but also confidence ranges and data variability can be derived. In the case of the K{sub d} parameter, a suitable continuous function which contains the statistical parameters (e.g. arithmetical/geometric mean, arithmetical/geometric standard deviation, mode, etc.) that better explain the distribution among the K{sub d} values of a dataset is the Cumulative Distribution Function (CDF). To our knowledge, appropriate CDFs has not been proposed for radionuclide K{sub d} in soils yet. Therefore, the aim of this works is to create CDFs for
Distributed Evaluation Functions for Fault Tolerant Multi-Rover Systems
Agogino, Adrian; Turner, Kagan
2005-01-01
The ability to evolve fault tolerant control strategies for large collections of agents is critical to the successful application of evolutionary strategies to domains where failures are common. Furthermore, while evolutionary algorithms have been highly successful in discovering single-agent control strategies, extending such algorithms to multiagent domains has proven to be difficult. In this paper we present a method for shaping evaluation functions for agents that provide control strategies that both are tolerant to different types of failures and lead to coordinated behavior in a multi-agent setting. This method neither relies of a centralized strategy (susceptible to single point of failures) nor a distributed strategy where each agent uses a system wide evaluation function (severe credit assignment problem). In a multi-rover problem, we show that agents using our agent-specific evaluation perform up to 500% better than agents using the system evaluation. In addition we show that agents are still able to maintain a high level of performance when up to 60% of the agents fail due to actuator, communication or controller faults.
ManeParse: a Mathematica reader for Parton Distribution Functions
Clark, D B; Olness, F I
2016-01-01
Parton Distribution Functions (PDFs) are essential non-perturbative inputs for calculation of any observable with hadronic initial states. These PDFs are released by individual groups as discrete grids as a function of the Bjorken-x and energy scale Q. The LHAPDF project at HepForge maintains a repository of PDFs from various groups in a new standardized LHAPDF6 format, as well as older formats such as the CTEQ PDS grid format. ManeParse is a package that provides PDFs within the Mathematica framework to facilitate calculating and plotting. The program is self-contained so there are no external links to any Fortran, C or C++ programs. The package includes the option to use the built-in Mathematica interpolation or a custom cubic Lagrange interpolation routine which allows for flexibility in the extrapolation (particularly at small x values). ManeParse is fast enough to enable simple calculations (involving even one or two integrations) to be easily computed in the Mathematica framework.
Characteristic functions of scale mixtures of multivariate skew-normal distributions
Kim, Hyoung-Moon
2011-08-01
We obtain the characteristic function of scale mixtures of skew-normal distributions both in the univariate and multivariate cases. The derivation uses the simple stochastic relationship between skew-normal distributions and scale mixtures of skew-normal distributions. In particular, we describe the characteristic function of skew-normal, skew-t, and other related distributions. © 2011 Elsevier Inc.
Varron, Davit
2012-01-01
Let $(Y_i,Z_i)_{i\\geq 1}$ be a sequence of independent, identically distributed (i.i.d.) random vectors taking values in $\\RRR^k\\times\\RRR^d$, for some integers $k$ and $d$. Given $z\\in \\RRR^d$, we provide a nonstandard functional limit law for the sequence of functional increments of the compound empirical process, namely $$\\mathbf{\\Delta}_{n,\\cc}(h_n,z,\\cdot):= \\frac{1}{nh_n}\\sliin 1_{[0,\\cdot)}\\poo \\frac{Z_i-z}{{h_n}^{1/d}}\\pff Y_i.$$ Provided that $nh_n\\sim c\\log n $ as $\
Leading non-Gaussian corrections for diffusion orientation distribution function.
Jensen, Jens H; Helpern, Joseph A; Tabesh, Ali
2014-02-01
An analytical representation of the leading non-Gaussian corrections for a class of diffusion orientation distribution functions (dODFs) is presented. This formula is constructed from the diffusion and diffusional kurtosis tensors, both of which may be estimated with diffusional kurtosis imaging (DKI). By incorporating model-independent non-Gaussian diffusion effects, it improves on the Gaussian approximation used in diffusion tensor imaging (DTI). This analytical representation therefore provides a natural foundation for DKI-based white matter fiber tractography, which has potential advantages over conventional DTI-based fiber tractography in generating more accurate predictions for the orientations of fiber bundles and in being able to directly resolve intra-voxel fiber crossings. The formula is illustrated with numerical simulations for a two-compartment model of fiber crossings and for human brain data. These results indicate that the inclusion of the leading non-Gaussian corrections can significantly affect fiber tractography in white matter regions, such as the centrum semiovale, where fiber crossings are common.
Alternative energy estimation from the shower lateral distribution function
De Souza, V; Brito, J; Dobrigkeit, C; Medina-Tanco, G; Souza, Vitor de; Escobar, Carlos O.; Brito, Joel; Dobrigkeit, Carola; Medina-Tanco, Gustavo
2005-01-01
The surface detector technique has been successfully used to detect cosmic ray showers for several decades. Scintillators or Cerenkov water tanks can be used to measure the number of particles and/or the energy density at a given depth in the atmosphere and reconstruct the primary particle properties. It has been shown that the experiment configuration and the resolution in reconstructing the core position determine a distance to the shower axis in which the lateral distribution function (LDF) of particles shows the least variation with respect to different primary particles type, simulation models and specific shapes of the LDF. Therefore, the signal at this distance (600 m for Haverah Park and 1000 m for Auger Observatory) has shown to be a good estimator of the shower energy. Revisiting the above technique, we show that a range of distances to the shower axis, instead of one single point, can be used as estimator of the shower energy. A comparison is done for the Auger Observatory configuration and the new...
Differential Density Statistics of Galaxy Distribution and the Luminosity Function
Albani, V V L; Ribeiro, M B; Stöger, W R; Albani, Vinicius V. L.; Iribarrem, Alvaro S.; Ribeiro, Marcelo B.; Stoeger, William R.
2006-01-01
This paper uses data obtained from the galaxy luminosity function (LF) to calculate two types of radial number densities statistics of the galaxy distribution as discussed in Ribeiro (2005), namely the differential density $\\gamma$ and the integral differential density $\\gamma^\\ast$. By applying the theory advanced by Ribeiro and Stoeger (2003), which connects the relativistic cosmology number counts with the astronomically derived LF, the differential number counts $dN/dz$ are extracted from the LF and used to calculate both $\\gamma$ and $\\gamma^\\ast$ with various cosmological distance definitions, namely the area distance, luminosity distance, galaxy area distance and redshift distance. LF data are taken from the CNOC2 galaxy redshift survey and $\\gamma$ and $\\gamma^\\ast$ are calculated for two cosmological models: Einstein-de Sitter and an $\\Omega_{m_0}=0.3$, $\\Omega_{\\Lambda_0}=0.7$ standard cosmology. The results confirm the strong dependency of both statistics on the distance definition, as predicted in...
Maxwellianization of electron distribution functions by convective instabilities in presheaths
Baalrud, S. D.; Hegna, C. C.; Callen, J. D.
2008-11-01
Langmuir's paradox is a measurement of anomalous electron scattering where a Maxwellian electron velocity distribution function was measured much closer to a boundary than the electron collision length in a stable plasma; here one should expect truncation corresponding to the sheath energy. In this paper we theoretically analyze the presheath region that is present in Langmuir paradox-relevant plasmas (TeTi). It is shown that the ion-acoustic instability is present throughout the presheath causing convective amplification of thermal fluctuations. A collision operator for the plasma kinetic equation including instabilities in a finite space-time domain is derived [1] which shows that electron scattering can be dominated by wave-particle interactions in the presheath. The modified collision operator satisfies the Boltzmann H-theorem, so the only equilibrium is a Maxwellian which is achieved at a rate depending on collisionality. Wave-particle scattering shrinks the electron collision length to within a few cm for these discharges suggesting that one should expect a Maxwellian at the location of previously reported measurements. [1] S.D. Baalrud, J.D. Callen, C.C. Hegna, UW-CPTC 08-4, June 2008 (sub. to Phys. Plasmas).
Metallicity Distribution Functions of Four Local Group dwarf galaxies
Ross, Teresa L; Saha, Abhijit; Anthony-Twarog, Barbara J
2015-01-01
We present stellar metallicities in Leo I, Leo II, IC 1613, and Phoenix dwarf galaxies derived from medium (F390M) and broad (F555W, F814W) band photometry using the Wide Field Camera 3 (WFC3) instrument aboard the Hubble Space Telescope. We measured metallicity distribution functions (MDFs) in two ways, 1) matching stars to isochrones in color-color diagrams, and 2) solving for the best linear combination of synthetic populations to match the observed color-color diagram. The synthetic technique reduces the effect of photometric scatter, and produces MDFs 30-50 % narrower than the MDFs produced from individually matched stars. We fit the synthetic and individual MDFs to analytical chemical evolution models (CEM) to quantify the enrichment and the effect of gas flows within the galaxies. Additionally, we measure stellar metallicity gradients in Leo I and II. For IC 1613 and Phoenix our data do not have the radial extent to confirm a metallicity gradient for either galaxy. We find the MDF of Leo I (dwarf spher...
A generalized AZ-non-Maxwellian velocity distribution function for space plasmas
Abid, A. A.; Khan, M. Z.; Lu, Quanming; Yap, S. L.
2017-03-01
A more generalized form of the non-Maxwellian distribution function, i.e., the AZ-distribution function is presented. Its fundamental properties are numerically observed by the variation of three parameters: α (rate of energetic particles on the shoulder), r (energetic particles on a broad shoulder), and q (superthermality on the tail of the velocity distribution curve of the plasma species). It has been observed that (i) the A Z - distribution function reduces to the ( r , q ) - distribution for α → 0 ; (ii) the A Z - distribution function reduces to the q - distribution for α → 0 , and r → 0 ; (iii) the A Z -distribution reduces to Cairns-distribution function for r → 0 , and q → ∞ ; (iv) the AZ-distribution reduces to Vasyliunas Cairns distribution for r → 0 , and q = κ + 1 ; (v) the AZ-distribution reduces to kappa distribution for α → 0 , r → 0 , and q = κ + 1 ; and (vi) finally, the AZ-distribution reduces to Maxwellian distribution for α → 0 , r → 0 , and q → ∞ . The uses of this more generalized A Z - distribution function in various space plasmas are briefly discussed.
Balasooriya, Uditha; Li, Jackie; Low, Chan Kee
2012-01-01
For any density function (or probability function), there always corresponds a "cumulative distribution function" (cdf). It is a well-known mathematical fact that the cdf is more general than the density function, in the sense that for a given distribution the former may exist without the existence of the latter. Nevertheless, while the density…
METALLICITY DISTRIBUTION FUNCTIONS OF FOUR LOCAL GROUP DWARF GALAXIES
Energy Technology Data Exchange (ETDEWEB)
Ross, Teresa L.; Holtzman, Jon [Department of Astronomy, New Mexico State University, P.O. Box 30001, MSC 4500, Las Cruces, NM 88003-8001 (United States); Saha, Abhijit [NOAO, 950 Cherry Avenue, Tucson, AZ 85726-6732 (United States); Anthony-Twarog, Barbara J., E-mail: rosst@nmsu.edu, E-mail: holtz@nmsu.edu, E-mail: bjat@ku.edu [Department of Physics and Astronomy, University of Kansas, Lawrence, KS 66045-7582 (United States)
2015-06-15
We present stellar metallicities in Leo I, Leo II, IC 1613, and Phoenix dwarf galaxies derived from medium (F390M) and broad (F555W, F814W) band photometry using the Wide Field Camera 3 instrument on board the Hubble Space Telescope. We measured metallicity distribution functions (MDFs) in two ways, (1) matching stars to isochrones in color–color diagrams and (2) solving for the best linear combination of synthetic populations to match the observed color–color diagram. The synthetic technique reduces the effect of photometric scatter and produces MDFs 30%–50% narrower than the MDFs produced from individually matched stars. We fit the synthetic and individual MDFs to analytical chemical evolution models (CEMs) to quantify the enrichment and the effect of gas flows within the galaxies. Additionally, we measure stellar metallicity gradients in Leo I and II. For IC 1613 and Phoenix our data do not have the radial extent to confirm a metallicity gradient for either galaxy. We find the MDF of Leo I (dwarf spheroidal) to be very peaked with a steep metal-rich cutoff and an extended metal-poor tail, while Leo II (dwarf spheroidal), Phoenix (dwarf transition), and IC 1613 (dwarf irregular) have wider, less peaked MDFs than Leo I. A simple CEM is not the best fit for any of our galaxies; therefore we also fit the “Best Accretion Model” of Lynden-Bell. For Leo II, IC 1613, and Phoenix we find similar accretion parameters for the CEM even though they all have different effective yields, masses, star formation histories, and morphologies. We suggest that the dynamical history of a galaxy is reflected in the MDF, where broad MDFs are seen in galaxies that have chemically evolved in relative isolation and narrowly peaked MDFs are seen in galaxies that have experienced more complicated dynamical interactions concurrent with their chemical evolution.
Degradation nonuniformity in the solar diffuser bidirectional reflectance distribution function.
Sun, Junqiang; Chu, Mike; Wang, Menghua
2016-08-01
The assumption of angular dependence stability of the solar diffuser (SD) throughout degradation is critical to the on-orbit calibration of the reflective solar bands (RSBs) in many satellite sensors. Recent evidence has pointed to the contrary, and in this work, we present a thorough investigative effort into the angular dependence of the SD degradation for the Visible Infrared Imaging Radiometer Suite (VIIRS) onboard the Suomi National Polar-orbiting Partnership (SNPP) satellite and for the twin Moderate-resolution Imaging Spectroradiometer (MODIS) onboard Terra and Aqua spacecrafts. One common key step in the RSB calibration is the use of the SD degradation performance measured by an accompanying solar diffuser stability monitor (SDSM) as a valid substitute for the SD degradation factor in the direction of the RSB view. If SD degradations between these two respective directions do not maintain the same relative relationship over time, then the unmitigated use of the SDSM-measured SD degradation factor in the RSB calibration calculation will generate bias, and consequently, long-term drift in derived science products. We exploit the available history of the on-orbit calibration events to examine the response of the SDSM and the RSB detectors to the incident illumination reflecting off SD versus solar declination angle and show that the angular dependency, particularly at short wavelengths, evolves with respect to time. The generalized and the decisive conclusion is that the bidirectional reflectance distribution function (BRDF) of the SD degrades nonuniformly with respect to both incident and outgoing directions. Thus, the SDSM-based measurements provide SD degradation factors that are biased relative to the RSB view direction with respect to the SD. The analysis also reveals additional interesting phenomena, for example, the sharp behavioral change in the evolving angular dependence observed in Terra MODIS and SNPP VIIRS. For SNPP VIIRS the mitigation for this
Amadei, A; Apol, MEF; DiNola, A; Berendsen, HJC
1996-01-01
A new theory is presented for calculating the Helmholtz free energy based on the potential energy distribution function. The usual expressions of free energy, internal energy and entropy involving the partition function are rephrased in terms of the potential energy distribution function, which must
Amadei, A; Apol, MEF; DiNola, A; Berendsen, HJC
1996-01-01
A new theory is presented for calculating the Helmholtz free energy based on the potential energy distribution function. The usual expressions of free energy, internal energy and entropy involving the partition function are rephrased in terms of the potential energy distribution function, which must
Evolution of transverse momentum dependent distribution and fragmentation functions
Henneman, A A; Mulders, P J; Boer, Daniel
2002-01-01
We use Lorentz invariance and the QCD equations of motion to study the evolution of functions that appear at leading order in a 1/Q expansion in azimuthal asymmetries. This includes the evolution equation of the Collins fragmentation function. The moments of these functions are matrix elements of known twist two and twist three operators. We present the evolution in the large N_c limit, restricting to non-singlet for the chiral-even functions.
Evolution of transverse momentum dependent distribution and fragmentation functions
Energy Technology Data Exchange (ETDEWEB)
Henneman, A.A. E-mail: alex@nat.vu.nl; Boer, Danieel; Mulders, P.J
2002-01-07
We use Lorentz invariance and the QCD equations of motion to study the evolution of functions that appear at leading order in a 1/Q expansion in azimuthal asymmetries. This includes the evolution equation of the Collins fragmentation function. The moments of these functions are matrix elements of known twist two and twist three operators. We present the evolution in the large N{sub c} limit, restricting to non-singlet for the chiral-even functions.
Evolution of transverse momentum dependent distribution and fragmentation functions
Henneman, A. A.; Boer, Daniël; Mulders, P. J.
2002-01-01
We use Lorentz invariance and the QCD equations of motion to study the evolution of functions that appear at leading order in a 1/ Q expansion in azimuthal asymmetries. This includes the evolution equation of the Collins fragmentation function. The moments of these functions are matrix elements of known twist two and twist three operators. We present the evolution in the large Nc limit, restricting to non-singlet for the chiral-even functions.
Evolution of transverse momentum dependent distribution and fragmentation functions
Henneman, AA; Boer, D; Mulders, PJ
2002-01-01
We use Lorentz invariance and the QCD equations of motion to study the evolution of functions that appear at leading order in a I / Q expansion in azimuthal asymmetries. This includes the evolution equation of the Collins fragmentation function. The moments of these functions are matrix elements of
Distributional (in)congruence of biodiversity-ecosystem functioning
Mulder, C.; Boit, A.; Mori, S.; Vonk, J.A.; Dyer, S.D.; Faggiano, L.; Geisen, S.; González, A.L.; Kaspari, M.; Lavorel, S.; Marquet, P.A.; Rossberg, A.G.; Sterner, R.W.; Voigt, W.; Wall, D.H.
2012-01-01
The majority of research on biodiversity-ecosystem functioning in laboratories has concentrated on a few traits, but there is increasing evidence from the field that functional diversity controls ecosystem functioning more often than does species number. Given the importance of traits as predictors
Theoretical method for determining the three-particle distribution function of classical systems
Energy Technology Data Exchange (ETDEWEB)
Johnson, E.
1979-01-01
Equilibrium statistical mechanics is considered. A method that should yield accurate three-particle distribution functions is presented. None of the current methods is successful. It appears that the new equation presented may be used with the first and second equations in the YBG hierarchy to obtain exact single-particle, pair, and triplet distribution functions. It should be easy to generalize the results to the n-particle distribution function.
Light field distribution of general function photonic crystals
Wu, Xiang-Yao; Liu, Xiao-Jing; Zhang, Si-Qi; Wang, Jing; Ba, Nuo; Xiao, Li; Li, Hong
2012-01-01
In this paper, We have presented a new general function photonic crystals (GFPCs), which refractive indexes are line functions of space position in two mediums $A$ and $B$, and obtain new results: (1) when the line function of refractive indexes is up or down, the transmissivity can be far larger or smaller than 1. (2) when the refractive indexes function increase or decrease along the direction of incident light, the light intensity should be magnified or weaken, which can be made optical magnifier or attenuator. (3) The GFPCs can be made optical diode when the light positive and negative incident the GFPCs.
Quantum arrival-time distributions from intensity functions
DEFF Research Database (Denmark)
Wlodarz, Joachim
2002-01-01
The quantum time-of-arrival problem is discussed within the standard formulation of nonrelativistic quantum mechanics with parametric time. It is shown that a general class of arrival-time probability distributions results from the assumption that the arrival process of a quantum particle...
Global marine plankton functional type biomass distributions : Phaeocystis spp
Vogt, M.; O'Brien, C.; Peloquin, J.; Schoemann, V.; Breton, E.; Estrada, M.; Gibson, J.; Karentz, D.; Van Leeuwe, M. A.; Stefels, J.; Widdicombe, C.; Peperzak, L.
2012-01-01
The planktonic haptophyte Phaeocystis has been suggested to play a fundamental role in the global biogeochemical cycling of carbon and sulphur, but little is known about its global biomass distribution. We have collected global microscopy data of the genus Phaeocystis and converted abundance data to
Local structure studies using the pair distribution function
Directory of Open Access Journals (Sweden)
Bordet Pierre
2015-01-01
Full Text Available The pair distribution analysis method is a fast spreading structural analysis method allowing to go beyond classical crystallographic analysis by providing quantitative information about local as well as meso-structure. It based on powder diffraction data fourier transformed to direct space. We will present here the main characteristics of the method, and its domain of application.
Caveat on the Boltzmann distribution function use in biology.
Sevcik, Carlos
2017-08-01
Sigmoid semilogarithmic functions with shape of Boltzmann equations, have become extremely popular to describe diverse biological situations. Part of the popularity is due to the easy availability of software which fits Boltzmann functions to data, without much knowledge of the fitting procedure or the statistical properties of the parameters derived from the procedure. The purpose of this paper is to explore the plasticity of the Boltzmann function to fit data, some aspects of the optimization procedure to fit the function to data and how to use this plastic function to differentiate the effect of treatment on data and to attest the statistical significance of treatment effect on the data. Copyright © 2017. Published by Elsevier Ltd.
The holonomic gradient method for the distribution function of the largest root of a Wishart matrix
National Research Council Canada - National Science Library
Hiroki Hashiguchi; Yasuhide Numata; Nobuki Takayama; Akimichi Takemura
2013-01-01
... of a Wishart matrix, which involves a hypergeometric function 1F1 of a matrix argument. Numerical evaluation of the hypergeometric function has been one of the longstanding problems in multivariate distribution theory...
Multi-Functional Distributed Secondary Control for Autonomous Microgrids
DEFF Research Database (Denmark)
Shafiee, Qobad
Microgrids (MGs)--the building blocks of the smart grid-- are local grids comprise different technologies such as power electronics converters, distributed renewable and non-renewable energy sources, energy storage systems, and telecommunications which can operate either in islanded mode...... or connected to the main grid. Apart from the obvious benefits of MGs, their introduction into the traditional distribution network raises many new challenges, thus, a hierarchical control concept has been introduced for these systems. While the decentralized primary control of this hierarchy ensures...... exchanging information with only its direct neighbors through a sparse communication network. Loss of sources and communication links do not affect system operation as long as the communication graph remains connected. Moreover, they are scalable, for that prior knowledge of the system is not required...
On the Intensity Distribution Function of Blazed Reflective Diffraction Gratings
Casini, R.; Nelson, P G
2014-01-01
We derive from first principles the expression for the angular/wavelength distribution of the intensity diffracted by a blazed reflective grating, according to a scalar theory of diffraction. We considered the most common case of a groove profile with rectangular apex. Our derivation correctly identifies the geometric parameters of a blazed reflective grating that determine its diffraction efficiency, and fixes an incorrect but commonly adopted expression in the literature. We compare the pre...
Charaterisation of function spaces via mollification; fractal quantities for distributions
Directory of Open Access Journals (Sweden)
Hans Triebel
2003-01-01
Full Text Available The aim of this paper is twofold. First we characterise elements f belonging to the Besov spaces Bpqs(ℝn with s∈ℝ, 0
distributions generalising well-known corresponding quantities for Radon measures.
Towards Bayesian Inference of the Fast-Ion Distribution Function
DEFF Research Database (Denmark)
Stagner, L.; Heidbrink, W.W.; Salewski, Mirko
2012-01-01
. However, when theory and experiment disagree (for one or more diagnostics), it is unclear how to proceed. Bayesian statistics provides a framework to infer the DF, quantify errors, and reconcile discrepant diagnostic measurements. Diagnostic errors and ``weight functions" that describe the phase space...... sensitivity of the measurements are incorporated into Bayesian likelihood probabilities, while prior probabilities enforce physical constraints. As an initial step, this poster uses Bayesian statistics to infer the DIII-D electron density profile from multiple diagnostic measurements. Likelihood functions...
On k-Gamma and k-Beta Distributions and Moment Generating Functions
Directory of Open Access Journals (Sweden)
Gauhar Rahman
2014-01-01
Full Text Available The main objective of the present paper is to define k-gamma and k-beta distributions and moments generating function for the said distributions in terms of a new parameter k>0. Also, the authors prove some properties of these newly defined distributions.
Do firms share the same functional form of their growth rate distribution? A new statistical test
Lunardi, Josè T; Lillo, Fabrizio; Mantegna, Rosario N; Gallegati, Mauro
2011-01-01
We introduce a new statistical test of the hypothesis that a balanced panel of firms have the same growth rate distribution or, more generally, that they share the same functional form of growth rate distribution. We applied the test to European Union and US publicly quoted manufacturing firms data, considering functional forms belonging to the Subbotin family of distributions. While our hypotheses are rejected for the vast majority of sets at the sector level, we cannot rejected them at the subsector level, indicating that homogenous panels of firms could be described by a common functional form of growth rate distribution.
Non-local velocity distribution function and one-flight approximation
Energy Technology Data Exchange (ETDEWEB)
Bakunin, O.G. [FOM Instituut voor Plasmafysica ' Rijnhuizen' , Associate Euroatom-FOM, 3430 BE Nieuwegein (Netherlands) and Russian Research Center ' Kurchatov Institute' , Nuclear Fusion Institute, sq. Kurchatova 1, 123182 Moscow (Russian Federation)]. E-mail: oleg_bakunin@yahoo.com
2004-09-13
The functional equation describing the collisionless particle velocity distribution function f(V) is considered in the framework of probabilistic approach. The key element of the collisionless particles description is using the waiting time distribution {psi}(t). The solution of the considered functional is obtained for several model functions {psi}(t) and it leads to the power form tails of the velocity distribution f(V). It is possible to adopt considered functional to the Laplace transformation form that allows us to accord 'collision' and 'collisionless' description. This Laplace form of the functional yields the Levy-Smirnov velocity distribution function with the characteristic exponent aL=1/2.
Directory of Open Access Journals (Sweden)
Aydın Kahriman
2011-11-01
Full Text Available Determine the diameter distribution of a stand and its relations with stand ages, site index, density and mixture percentage is very important both biologically and economically. The Weibull with two parameters, Weibull with three parameters, Gamma with two parameters, Gamma with three parameters, Beta, Lognormal with two parameters, Lognormal with three parameters, Normal, Johnson SB probability density functions were used to determination of diameter distributions. This study aimed to compared based on performance of describing different diameter distribution and to describe the best successful function of diameter distributions. The data were obtaited from 162 temporary sample plots measured Scots pine and Oriental beech mixed stands in Black Sea Region. The results show that four parameter Johnson SB function for both scots pine and oriental beech is the best successful function to describe diameter distributions based on error index values calculated by difference between observed and predicted diameter distributions.
THE INITIAL MASS FUNCTION MODELED BY A LEFT TRUNCATED BETA DISTRIBUTION
Energy Technology Data Exchange (ETDEWEB)
Zaninetti, Lorenzo, E-mail: zaninetti@ph.unito.it [Dipartimento di Fisica, Via Pietro Giuria 1, I-10125 Torino (Italy)
2013-03-10
The initial mass function for stars is usually fitted by three straight lines, which means it has seven parameters. The presence of brown dwarfs (BDs) increases the number of straight lines to four and the number of parameters to nine. Another common fitting function is the lognormal distribution, which is characterized by two parameters. This paper is devoted to demonstrating the advantage of introducing a left truncated beta probability density function, which is characterized by four parameters. The constant of normalization, the mean, the mode, and the distribution function are calculated for the left truncated beta distribution. The normal beta distribution that results from convolving independent normally distributed and beta distributed components is also derived. The chi-square test and the Kolmogorov-Smirnov test are performed on a first sample of stars and BDs that belongs to the massive young cluster NGC 6611, and on a second sample that represents the masses of the stars of the cluster NGC 2362.
The initial mass function modeled by a left truncated beta distribution
Zaninetti, L
2013-01-01
The initial mass function (IMF) for the stars is usually fitted by three straight lines, which means seven parameters. The presence of brown dwarfs (BD) increases to four the straight lines and to nine the parameters. Another common fitting function is the lognormal distribution, which is characterized by two parameters. This paper is devoted to demonstrating the advantage of introducing a left truncated beta probability density function, which is characterized by four parameters. The constant of normalization, the mean, the mode and the distribution function are calculated for the left truncated beta distribution. The normal-beta (NB) distribution which results from convolving independent normally distributed and beta distributed components is also derived. The chi-square test and the K-S test are performed on a first sample of stars and BDs which belongs to the massive young cluster NGC 6611 and on a second sample which represents the star's masses of the cluster NGC 2362.
Formal Difference Analysis and Unification on p-Norm Distribution Density Functions
Institute of Scientific and Technical Information of China (English)
LIU Zhengcai; ZHU Jianjun; WANG Huaiyu
2006-01-01
The cause of the formal difference of p-norm distribution density functions is analyzed, two problems in the deduction of p-norm formulating are improved, and it is proved that two different forms of p-norm distribution density functions are equivalent. This work is useful for popularization and application of the p-norm theory to surveying and mapping.
Nonparametric estimation of the stationary M/G/1 workload distribution function
DEFF Research Database (Denmark)
Hansen, Martin Bøgsted
2005-01-01
In this paper it is demonstrated how a nonparametric estimator of the stationary workload distribution function of the M/G/1-queue can be obtained by systematic sampling the workload process. Weak convergence results and bootstrap methods for empirical distribution functions for stationary associ...
Margaret M. Mayfield; John M. Dwyer; Loic Chalmandrier; Jessie A. Wells; Stephen P. Bonser; Carla P. Catterall; Fabrice DeClerck; Yi Ding; Jennifer M. Fraterrigo; Daniel J. Metcalfe; Cibele Queiroz; Peter A. Vesk; John W. Morgan
2013-01-01
â¢ Premise of study: Plant functional traits are commonly used as proxies for plant responses to environmental challenges, yet few studies have explored how functional trait distributions differ across gradients of land-use change. By comparing trait distributions in intact forests with those across land-use change gradients, we can improve our understanding of the ways...
Constructing the probability distribution function for the total capacity of a power system
Energy Technology Data Exchange (ETDEWEB)
Vasin, V.P.; Prokhorenko, V.I.
1980-01-01
The difficulties involved in constructing the probability distribution function for the total capacity of a power system consisting of numerous power plants are discussed. A method is considered for the approximate determination of such a function by a Monte Carlo method and by exact calculation based on special recursion formulas on a particular grid of argument values. It is shown that there may be significant deviations between the true probability distribution and a normal distribution.
On the Intensity Distribution Function of Blazed Reflective Diffraction Gratings
Casini, R
2014-01-01
We derive from first principles the expression for the angular/wavelength distribution of the intensity diffracted by a blazed reflective grating, according to a scalar theory of diffraction. We considered the most common case of a groove profile with rectangular apex. Our derivation correctly identifies the geometric parameters of a blazed reflective grating that determine its diffraction efficiency, and fixes an incorrect but commonly adopted expression in the literature. We compare the predictions of this scalar theory with those resulting from a rigorous vector treatment of diffraction from one-dimensional blazed reflective gratings.
Cumulative overlap distribution function in realistic spin glasses
Billoire, A.; Maiorano, A.; Marinari, E.; Martin-Mayor, V.; Yllanes, D.
2014-09-01
We use a sample-dependent analysis, based on medians and quantiles, to analyze the behavior of the overlap probability distribution of the Sherrington-Kirkpatrick and 3D Edwards-Anderson models of Ising spin glasses. We find that this approach is an effective tool to distinguish between replica symmetry breaking-like and droplet-like behavior of the spin-glass phase. Our results are in agreement with a replica symmetry breaking-like behavior for the 3D Edwards-Anderson model.
Dijk, Peter H.; Heikamp, A; Bambang Oetomo, Sidarto
1997-01-01
Objective: Surfactant nebulisation is a promising alternative to surfactant instillation in newborns with the respiratory distress syndrome. Although less surfactant is deposited in the lung, it improves gas exchange, probably due to a superior distribution. We hypothesize that a more uniform distri
Dijk, Peter H.; Heikamp, A; Bambang Oetomo, Sidarto
1997-01-01
Objective: Surfactant nebulisation is a promising alternative to surfactant instillation in newborns with the respiratory distress syndrome. Although less surfactant is deposited in the lung, it improves gas exchange, probably due to a superior distribution. We hypothesize that a more uniform distri
Multi-level methods and approximating distribution functions
Wilson, D.; Baker, R. E.
2016-07-01
Biochemical reaction networks are often modelled using discrete-state, continuous-time Markov chains. System statistics of these Markov chains usually cannot be calculated analytically and therefore estimates must be generated via simulation techniques. There is a well documented class of simulation techniques known as exact stochastic simulation algorithms, an example of which is Gillespie's direct method. These algorithms often come with high computational costs, therefore approximate stochastic simulation algorithms such as the tau-leap method are used. However, in order to minimise the bias in the estimates generated using them, a relatively small value of tau is needed, rendering the computational costs comparable to Gillespie's direct method. The multi-level Monte Carlo method (Anderson and Higham, Multiscale Model. Simul. 10:146-179, 2012) provides a reduction in computational costs whilst minimising or even eliminating the bias in the estimates of system statistics. This is achieved by first crudely approximating required statistics with many sample paths of low accuracy. Then correction terms are added until a required level of accuracy is reached. Recent literature has primarily focussed on implementing the multi-level method efficiently to estimate a single system statistic. However, it is clearly also of interest to be able to approximate entire probability distributions of species counts. We present two novel methods that combine known techniques for distribution reconstruction with the multi-level method. We demonstrate the potential of our methods using a number of examples.
A distributed transducer system for functional electrical stimulation
DEFF Research Database (Denmark)
Gudnason, Gunnar; Nielsen, Jannik Hammel; Bruun, Erik
2001-01-01
Implanted transducers for functional electrical stimulation (FES) powered by inductive links are subject to conflicting requirements arising from low link efficiency, a low power budget and the need for protection of the weak signals against strong RF electromagnetic fields. We propose a solution...
Characterizing short-term stability for Boolean networks over any distribution of transfer functions
Seshadhri, C.; Smith, Andrew M.; Vorobeychik, Yevgeniy; Mayo, Jackson R.; Armstrong, Robert C.
2016-07-01
We present a characterization of short-term stability of Kauffman's N K (random) Boolean networks under arbitrary distributions of transfer functions. Given such a Boolean network where each transfer function is drawn from the same distribution, we present a formula that determines whether short-term chaos (damage spreading) will happen. Our main technical tool which enables the formal proof of this formula is the Fourier analysis of Boolean functions, which describes such functions as multilinear polynomials over the inputs. Numerical simulations on mixtures of threshold functions and nested canalyzing functions demonstrate the formula's correctness.
Seshadhri, C; Smith, Andrew M; Vorobeychik, Yevgeniy; Mayo, Jackson R; Armstrong, Robert C
2016-07-01
We present a characterization of short-term stability of Kauffman's NK (random) Boolean networks under arbitrary distributions of transfer functions. Given such a Boolean network where each transfer function is drawn from the same distribution, we present a formula that determines whether short-term chaos (damage spreading) will happen. Our main technical tool which enables the formal proof of this formula is the Fourier analysis of Boolean functions, which describes such functions as multilinear polynomials over the inputs. Numerical simulations on mixtures of threshold functions and nested canalyzing functions demonstrate the formula's correctness.
A linear functional differential equation with distributions in the input
Directory of Open Access Journals (Sweden)
Vadim Z. Tsalyuk
2003-10-01
Full Text Available This paper studies the functional differential equation $$ dot x(t = int_a^t {d_s R(t,s, x(s} + F'(t, quad t in [a,b], $$ where $F'$ is a generalized derivative, and $R(t,cdot$ and $F$ are functions of bounded variation. A solution is defined by the difference $x - F$ being absolutely continuous and satisfying the inclusion $$ frac{d}{dt} (x(t - F(t in int_a^t {d_s R(t,s,x(s}. $$ Here, the integral in the right is the multivalued Stieltjes integral presented in cite{VTs1} (in this article we review and extend the results in cite{VTs1}. We show that the solution set for the initial-value problem is nonempty, compact, and convex. A solution $x$ is said to have memory if there exists the function $x$ such that $x(a = x(a$, $x(b = x(b$, $ x(t in [x(t-0,x(t+0]$ for $t in (a,b$, and $frac{d}{dt} (x(t - F(t = int_a^t {d_s R(t,s,{x}(s}$, where Lebesgue-Stieltjes integral is used. We show that such solutions form a nonempty, compact, and convex set. It is shown that solutions with memory obey the Cauchy-type formula $$ x(t in C(t,ax(a + int_a^t C(t,s, dF(s. $$
Global marine plankton functional type biomass distributions: Phaeocystis sp.
Directory of Open Access Journals (Sweden)
C. Widdicombe
2012-05-01
Full Text Available The planktonic haptophyte Phaeocystis has been suggested to play a fundamental role in the global biogeochemical cycling of carbon and sulphur, but little is known about its global biomass distribution. We have collected global microscopy data of the genus Phaeocystis and converted abundance data to carbon biomass using species-specific carbon conversion factors. Microscopic counts of single-celled and colonial Phaeocystis were obtained both through the mining of online databases and by accepting direct submissions (both published and unpublished from Phaeocystis specialists. We recorded abundance data from a total of 1595 depth-resolved stations sampled between 1955–2009. The quality-controlled dataset includes 5057 counts of individual Phaeocystis cells resolved to species level and information regarding life-stages from 3526 samples. 83% of stations were located in the Northern Hemisphere while 17% were located in the Southern Hemisphere. Most data were located in the latitude range of 50–70° N. While the seasonal distribution of Northern Hemisphere data was well-balanced, Southern Hemisphere data was biased towards summer months. Mean species- and form-specific cell diameters were determined from previously published studies. Cell diameters were used to calculate the cellular biovolume of Phaeocystis cells, assuming spherical geometry. Cell biomass was calculated using a carbon conversion factor for Prymnesiophytes (Menden-Deuer and Lessard, 2000. For colonies, the number of cells per colony was derived from the colony volume. Cell numbers were then converted to carbon concentrations. An estimation of colonial mucus carbon was included a posteriori, assuming a mean colony size for each species. Carbon content per cell ranged from 9 pg (single-celled Phaeocystis antarctica to 29 pg (colonial Phaeocystis globosa. Non-zero Phaeocystis cell biomasses (without mucus carbon range from 2.9 × 10−5 μg l−1 to 5.4 × 103 μg l−1, with a
Global marine plankton functional type biomass distributions: Phaeocystis spp.
Directory of Open Access Journals (Sweden)
C. Widdicombe
2012-09-01
Full Text Available The planktonic haptophyte Phaeocystis has been suggested to play a fundamental role in the global biogeochemical cycling of carbon and sulphur, but little is known about its global biomass distribution. We have collected global microscopy data of the genus Phaeocystis and converted abundance data to carbon biomass using species-specific carbon conversion factors. Microscopic counts of single-celled and colonial Phaeocystis were obtained both through the mining of online databases and by accepting direct submissions (both published and unpublished from Phaeocystis specialists. We recorded abundance data from a total of 1595 depth-resolved stations sampled between 1955–2009. The quality-controlled dataset includes 5057 counts of individual Phaeocystis cells resolved to species level and information regarding life-stages from 3526 samples. 83% of stations were located in the Northern Hemisphere while 17% were located in the Southern Hemisphere. Most data were located in the latitude range of 50–70° N. While the seasonal distribution of Northern Hemisphere data was well-balanced, Southern Hemisphere data was biased towards summer months. Mean species- and form-specific cell diameters were determined from previously published studies. Cell diameters were used to calculate the cellular biovolume of Phaeocystis cells, assuming spherical geometry. Cell biomass was calculated using a carbon conversion factor for prymnesiophytes. For colonies, the number of cells per colony was derived from the colony volume. Cell numbers were then converted to carbon concentrations. An estimation of colonial mucus carbon was included a posteriori, assuming a mean colony size for each species. Carbon content per cell ranged from 9 pg C cell−1 (single-celled Phaeocystis antarctica to 29 pg C cell−1 (colonial Phaeocystis globosa. Non-zero Phaeocystis cell biomasses (without mucus carbon range from 2.9 × 10−5 to 5.4 × 103 μg C l−1, with a mean of 45.7 μg C
Partitioning of Function in a Distributed Graphics System.
1985-03-01
clipping fo~r extents totally outside the area being drawn. -’- his is effectively die display processing unil. In a hiigher- performance... clipping and scaling. However, in the IRIS workstation these functions are provided in hardware by the Geometry Engilic [381. General’y, the IRIS provides...VIiv.., ] VIO VlO VlO +VIO VIO VGTS VOTS BSP VGTS rCP fexecute PUP Telnet iptn Internal a) VAX-IKP b) PUP Telnet c) IP Telnet Figure 6-2: Server host
[Opioid receptors of the CNS: function, structure and distribution].
Slamberová, R
2004-01-01
Even though the alkaloids of opium, such as morphine and codeine, were isolated at the beginning of 19th century, the opioid receptors were not determined until 1970's. The discovery of endogenous opioid peptides, such as endorphins, enkephalins and dynorphins, has helped to differentiate between the specific opioid receptor subtypes, mu, delta and kappa, that are used up to now. Opioid receptors are distributed in the central nervous system unevenly. Each receptor subtype has its own specific and nonspecific agonists and antagonists. Opioides, as exogenous opioid receptor agonists, are drugs that are often used in medicine for their analgesic effects, but they are also some of the most heavily abused drugs in the world. Opioides may also induce long-term changes in the numbers and binding activities of opioid receptors. Some of our studies in fact demonstrate that prenatal morphine exposure can alter opioid receptors of adult rats. This may begin to provide insight into the sources of some of the morphological and behavioral changes in the progeny of mothers that received or abused opioides during pregnancy.
Global study of nuclear modifications on parton distribution functions
Wang, Rong; Fu, Qiang
2016-01-01
A global analysis of nuclear medium modifications of parton distributions is presented using deeply inelastic scattering data of various nuclear targets. Two obtained data sets are provided for quark and gluon nuclear modification factors, referred as nIMParton16. One is from the global fit only to the experimental data of isospin-scalar nuclei (Set A), and the other is from the fit to all the measured nuclear data (Set B). The scale-dependence is described by DGLAP equations with nonlinear corrections in this work. The Fermi motion and off-shell effect, nucleon swelling, and parton-parton recombination are taken into account together for modeling the complicated $x$-dependence of nuclear modification. The nuclear gluon shadowing in this paper is dynamically generated by the QCD evolution of parton splitting and recombination processes with zero gluon density at the input scale. Sophisticated nuclear dependence of nuclear medium effects is studied with only two free parameters. With the obtained free paramete...
Li, Q; He, Y L; Wang, Y; Tao, W Q
2007-11-01
A coupled double-distribution-function lattice Boltzmann method is developed for the compressible Navier-Stokes equations. Different from existing thermal lattice Boltzmann methods, this method can recover the compressible Navier-Stokes equations with a flexible specific-heat ratio and Prandtl number. In the method, a density distribution function based on a multispeed lattice is used to recover the compressible continuity and momentum equations, while the compressible energy equation is recovered by an energy distribution function. The energy distribution function is then coupled to the density distribution function via the thermal equation of state. In order to obtain an adjustable specific-heat ratio, a constant related to the specific-heat ratio is introduced into the equilibrium energy distribution function. Two different coupled double-distribution-function lattice Boltzmann models are also proposed in the paper. Numerical simulations are performed for the Riemann problem, the double-Mach-reflection problem, and the Couette flow with a range of specific-heat ratios and Prandtl numbers. The numerical results are found to be in excellent agreement with analytical and/or other solutions.
Indian Academy of Sciences (India)
R Saravanan; K S Syed Ali; S Israel
2008-04-01
The local, average and electronic structure of the semiconducting materials Si and Ge has been studied using multipole, maximum entropy method (MEM) and pair distribution function (PDF) analyses, using X-ray powder data. The covalent nature of bonding and the interaction between the atoms are clearly revealed by the two-dimensional MEM maps plotted on (1 0 0) and (1 1 0) planes and one-dimensional density along [1 0 0], [1 1 0] and [1 1 1] directions. The mid-bond electron densities between the atoms are 0.554 e/Å3 and 0.187 e/Å3 for Si and Ge respectively. In this work, the local structural information has also been obtained by analyzing the atomic pair distribution function. An attempt has been made in the present work to utilize the X-ray powder data sets to refine the structure and electron density distribution using the currently available versatile methods, MEM, multipole analysis and determination of pair distribution function for these two systems.
Alternative oxidase: distribution, induction, properties, structure, regulation, and functions.
Rogov, A G; Sukhanova, E I; Uralskaya, L A; Aliverdieva, D A; Zvyagilskaya, R A
2014-12-01
The respiratory chain in the majority of organisms with aerobic type metabolism features the concomitant existence of the phosphorylating cytochrome pathway and the cyanide- and antimycin A-insensitive oxidative route comprising a so-called alternative oxidase (AOX) as a terminal oxidase. In this review, the history of AOX discovery is described. Considerable evidence is presented that AOX occurs widely in organisms at various levels of organization and is not confined to the plant kingdom. This enzyme has not been found only in Archaea, mammals, some yeasts and protists. Bioinformatics research revealed the sequences characteristic of AOX in representatives of various taxonomic groups. Based on multiple alignments of these sequences, a phylogenetic tree was constructed to infer their possible evolution. The ways of AOX activation, as well as regulatory interactions between AOX and the main respiratory chain are described. Data are summarized concerning the properties of AOX and the AOX-encoding genes whose expression is either constitutive or induced by various factors. Information is presented on the structure of AOX, its active center, and the ubiquinone-binding site. The principal functions of AOX are analyzed, including the cases of cell survival, optimization of respiratory metabolism, protection against excess of reactive oxygen species, and adaptation to variable nutrition sources and to biotic and abiotic stress factors. It is emphasized that different AOX functions complement each other in many instances and are not mutually exclusive. Examples are given to demonstrate that AOX is an important tool to overcome the adverse aftereffects of restricted activity of the main respiratory chain in cells and whole animals. This is the first comprehensive review on alternative oxidases of various organisms ranging from yeasts and protists to vascular plants.
Institute of Scientific and Technical Information of China (English)
G.R. Boroun
2005-01-01
An approximation method based on Regge behavior is presented. This new method relates the reduced cross section derivative and the structure function Regge behavior at Iow x. With the use of this approximation method,the C and λ parameters are calculated from the HERA reduced cross section data taken at low-x. Also, we calculate the structure functions F2(x, Q2) even for low-x values, which have not been investigated. To test the validity of calculated structure functions, we find the gluon distribution function in the Leading order approximation based on Regge behaviour of structure function and compare to the NLO QCD fit to H1 data and NLO parton distribution function.
On the spectrum of a distribution function and on unique factorization
Directory of Open Access Journals (Sweden)
T. Pham-Gia
1982-01-01
Full Text Available The spectrum of a distribution function is related to the quasi-analyticity of a class of functions {CM(j}, where M(j is a multisequence of positive numbers. For a regular multisequence, a result on the uniqueness of characteristic function decomposition is given.
Göldel, B.; Kissling, W.D.; Svenning, J.-C.
2015-01-01
Functional traits play a key role in driving biodiversity effects on ecosystem functioning. Here, we examine the geographical distributions of three key functional traits in New World palms (Arecaceae), an ecologically important plant group, and their relationships with current climate, soil and gla
Sehar, Sumbul; Nouman Sarwar, Qureshi Muhammad
2016-04-01
In many physical situations such as space or laboratory plasmas a hot low-density electron populations can be generated superimposed on the bulk cold population, resulting in a particle distribution function consisting of a dense cold part and hot superthermal tail. Space observations show that electron distributions are often observed with flat top at low energies and high energy tails. The appropriate distribution to model such non-Maxwellian features is the generalized (r,q) distribution function which in limiting forms can be reduced to kappa and Maxwellian distribution functions. In this study, Kinetic model is employed to study the electron-acoustic and ion-ion acoustic instabilities in four component plasma with generalized (r,q) distribution function for both magnetized and unmagnetized plasmas. Departure of plasma from Maxwellian distributions significantly alters the growth rates as compared to the Maxwellian plasma. Significant growth observed for highly non-Maxwellian distributions as well as plasmas with higher dense and hot electron population. Existence of weak damping is also established when the distribution contains broadened flat tops at the low energies or tends to be Maxwellian. These results may be applied in both experimental and space physics regimes.
Function and distribution of bilin biosynthesis enzymes in photosynthetic organisms.
Dammeyer, Thorben; Frankenberg-Dinkel, Nicole
2008-10-01
Bilins are open-chain tetrapyrrole molecules essential for light-harvesting and/or sensing in many photosynthetic organisms. While they serve as chromophores in phytochrome-mediated light-sensing in plants, they additionally function in light-harvesting in cyanobacteria, red algae and cryptomonads. Associated to phycobiliproteins a variety of bile pigments is responsible for the specific light-absorbance properties of the organisms enabling efficient photosynthesis under different light conditions. The initial step of bilin biosynthesis is the cleavage of heme by heme oxygenases (HO) to afford the first linear molecule biliverdin. This reaction is ubiquitously found also in non-photosynthetic organisms. Biliverdin is then further reduced by site specific reductases most of them belonging to the interesting family of ferredoxin-dependent bilin reductases (FDBRs)-a new family of radical oxidoreductases. In recent years much progress has been made in the field of heme oxygenases but even more in the widespread family of FDBRs, revealing novel biochemical FDBR activities, new crystal structures and new ecological aspects, including the discovery of bilin biosynthesis genes in wild marine phage populations. The aim of this review is to summarize and discuss the recent progress in this field and to highlight the new and remaining questions.
Distribution function approach to irreversible adsorption of interacting colloidal particles
Faraudo, Jordi; Bafaluy, Javier
2000-01-01
A statistical-mechanical description of the irreversible adsorption of interacting colloidal particles is developed. Our approach describes in a consistent way the interaction of particles from the bulk with adsorbed particles during the transport process towards the adsorbing surface. The macroscopic physical quantities corresponding to the actual process are expressed as averages over simpler auxiliary processes which proceed in the presence of a fixed number n of adsorbed particles. The adsorption rate verifies a generalized Langmuir equation, in which the kinetic resistance (the inverse of the kinetic coefficient) is expressed as the sum of a diffusional resistance and a resistance due to interaction with adsorbed particles during the transport process (blocking effect). Contrary to previous approaches, the blocking effect is not due to geometrical exclusion, instead it measures how the transport from the bulk is affected by the adsorbed particles. From the general expressions obtained, we have derived coverage expansions for the adsorption rate and the surface correlation function. The theory is applied to the case of colloidal particles interacting through DLVO potentials. This form of the kinetic coefficient is shown to be in agreement with recent experimental results, in which RSA fails.
Regulation of REGγ cellular distribution and function by SUMO modification
Institute of Scientific and Technical Information of China (English)
Yan Wu; Honglin Luo; Xiaotao Li; Lu Wang; Ping Zhou; Guangqiang Wang; Yu Zeng; Ying Wang; Jian Liu; Bianhong Zhang; Shuang Liu
2011-01-01
Discovery of emerging REGy-regulated proteins has accentuated the RECry-proteasome as an important pathway in multiple biological processes, including cell growth, cell cycle regulation, and apoptosis. However, little is known about the regulation of the REGy-proteasome pathway. Here we demonstrate that REGγ can be SUMOylated in vitro and in vivo by SUMO-1, SUMO-2, and SUMO-3. The SUMO-E3 protein inhibitor of activated STAT(PIAS)1physically associates with REGy and promotes SUMOylation of REGy. SUMOylation of RECry was found to occur at multiple sites, including K6, K14, and K12. Mutation analysis indicated that these SUMO sites simultaneously contributed to the SUMOylation status of REGy in cells. Posttranslational modification of REGγ by SUMO conjugation was revealed to mediate cytosolic translocation of REGγ and to cause increased stability of this proteasome activator.SUMOylation-deficient REGγ displayed attenuated ability to degrade p21waf//Cipl due to reduced affinity of the REGγ SUMOylation-defective mutant for p21. Taken together, we report a previously unrecognized mechanism regulating the activity of the proteasome activator REGy. This regulatory mechanism may enable REGy to function as a more potent factor in protein degradation with a broader substrate spectrum.
SMPDF Web: a web-based application for specialized minimal parton distribution functions
Carrazza, Stefano
2016-01-01
We present SMPDF Web, a web interface for the construction of parton distribution functions (PDFs) with a minimal number of error sets needed to represent the PDF uncertainty of specific processes (SMPDF).
The U.S. Environmental Protection Agency's Environmental Monitoring and Assessment Program (EMAP) employs the cumulative distribution function (cdf) to measure the status of quantitative variables for resources of interest. The ability to compare cdf's for a resource from, say,...
Energy Technology Data Exchange (ETDEWEB)
K.G. Mon
1998-05-15
The purpose of this calculation is to process the cumulative distribution functions (CDFs) characterizing the temperature threshold for the onset of corrosion provided by expert elicitation and minimize the set of values to 200 points for use in WAPDEG.
Distributional Methods for a Class of Functional Equations and Their Stabilities
Institute of Scientific and Technical Information of China (English)
Jae Young CHUNG
2007-01-01
We consider a class of n-dimensional Pompeiu equations and that of Pexider equations and their Hyers-Ulam stability problems in the spaces of Schwartz distributions. First, reducing the given distribution version of functional equations to differential equations we find their solutions. Secondly,using approximate identities we prove the Hyers-Ulam stability of the equations.
Concentration of empirical distribution functions with applications to non-i.i.d. models
Bobkov, S G; 10.3150/10-BEJ254
2010-01-01
The concentration of empirical measures is studied for dependent data, whose joint distribution satisfies Poincar\\'{e}-type or logarithmic Sobolev inequalities. The general concentration results are then applied to spectral empirical distribution functions associated with high-dimensional random matrices.
Lapenta, C. C.
1992-01-01
The functionality of the Distributed Active Archive Centers (DAACs) which are significant elements of the Earth Observing System Data and Information System (EOSDIS) is discussed. Each DAAC encompasses the information management system, the data archival and distribution system, and the product generation system. The EOSDIS DAACs are expected to improve the access to earth science data set needed for global change research.
A study of the up-and-down method for non-normal distribution functions
DEFF Research Database (Denmark)
Vibholm, Svend; Thyregod, Poul
1988-01-01
The assessment of breakdown probabilities is examined by the up-and-down method. The exact maximum-likelihood estimates for a number of response patterns are calculated for three different distribution functions and are compared with the estimates corresponding to the normal distribution. Estimat...
Thomas E. Dilts; Peter J. Weisberg; Camie M. Dencker; Jeanne C. Chambers
2015-01-01
We have three goals. (1) To develop a suite of functionally relevant climate variables for modelling vegetation distribution on arid and semi-arid landscapes of the Great Basin, USA. (2) To compare the predictive power of vegetation distribution models based on mechanistically proximate factors (water deficit variables) and factors that are more mechanistically removed...
A central body fat distribution is related to renal function impairment, even in lean subjects
Pinto-Sietsma, SJ; Navis, G; Janssen, WMT; de Zeeuw, D; Gans, ROB; de Jong, PE
2003-01-01
Background Overweight and obesity are believed to be associated with renal damage. Whether this depends on fat distribution is not known. We hypothesize that in addition to overweight, fat distribution may be associated with renal function abnormalities. Methods: We studied the relation between body
Meiling, Yu; Lianshou, Liu
2008-01-01
Pair distribution function for delocalized quarks in the strongly coupled quark gluon plasma (sQGP) as well as in the states at intermediate stages of crossover from hadronic matter to sQGP are calculated using a molecule-like aggregation model. The shapes of the obtained pair distribution functions exhibit the character of liquid. The increasing correlation length in the process of crossover indicates a diminishing viscosity of the fluid system.
ON THE ESTIMATION OF DISTANCE DISTRIBUTION FUNCTIONS FOR POINT PROCESSES AND RANDOM SETS
Directory of Open Access Journals (Sweden)
Dietrich Stoyan
2011-05-01
Full Text Available This paper discusses various estimators for the nearest neighbour distance distribution function D of a stationary point process and for the quadratic contact distribution function Hq of a stationary random closed set. It recommends the use of Hanisch's estimator of D, which is of Horvitz-Thompson type, and the minussampling estimator of Hq. This recommendation is based on simulations for Poisson processes and Boolean models.
Zalvidea; Colautti; Sicre
2000-05-01
An analysis of the Strehl ratio and the optical transfer function as imaging quality parameters of optical elements with enhanced focal length is carried out by employing the Wigner distribution function. To this end, we use four different pupil functions: a full circular aperture, a hyper-Gaussian aperture, a quartic phase plate, and a logarithmic phase mask. A comparison is performed between the quality parameters and test images formed by these pupil functions at different defocus distances.
Herculano-Houzel, Suzana; Watson, Charles; Paxinos, George
2013-01-01
How are neurons distributed along the cortical surface and across functional areas? Here we use the isotropic fractionator (Herculano-Houzel and Lent, 2005) to analyze the distribution of neurons across the entire isocortex of the mouse, divided into 18 functional areas defined anatomically. We find that the number of neurons underneath a surface area (the N/A ratio) varies 4.5-fold across functional areas and neuronal density varies 3.2-fold. The face area of S1 contains the most neurons, followed by motor cortex and the primary visual cortex. Remarkably, while the distribution of neurons across functional areas does not accompany the distribution of surface area, it mirrors closely the distribution of cortical volumes-with the exception of the visual areas, which hold more neurons than expected for their volume. Across the non-visual cortex, the volume of individual functional areas is a shared linear function of their number of neurons, while in the visual areas, neuronal densities are much higher than in all other areas. In contrast, the 18 functional areas cluster into three different zones according to the relationship between the N/A ratio and cortical thickness and neuronal density: these three clusters can be called visual, sensory, and, possibly, associative. These findings are remarkably similar to those in the human cerebral cortex (Ribeiro et al., 2013) and suggest that, like the human cerebral cortex, the mouse cerebral cortex comprises two zones that differ in how neurons form the cortical volume, and three zones that differ in how neurons are distributed underneath the cortical surface, possibly in relation to local differences in connectivity through the white matter. Our results suggest that beyond the developmental divide into visual and non-visual cortex, functional areas initially share a common distribution of neurons along the parenchyma that become delimited into functional areas according to the pattern of connectivity established later.
A Real Cohen Distribution Function%Cohen实分布函数
Institute of Scientific and Technical Information of China (English)
袁通全; 韦吉爵
2011-01-01
Based on the general expression of distribution function in the quantum phase space defined by Cohen, a real Cohen distribution function is educed, which depends on the parameter and satisfies the marginal conditions. In addition, the expressions of the derived function for ground state and the first excited state of the harmonic oscillator are gained and their pictures with of the distribution function are compared with that of Wigner function.%从Cohen定义的量子相空间中的分布函数的一般表达式出发,导出了一个依赖于参数γ的满足边缘条件的实分布函数.求出了谐振子基态和第一激发态的分布函数的表达式,并把γ=1时函数的图象和Wigner函数图象作了比较.
Lyapunov Functions, Stationary Distributions, and Non-equilibrium Potential for Reaction Networks
DEFF Research Database (Denmark)
Anderson, David F; Craciun, Gheorghe; Gopalkrishnan, Manoj;
2015-01-01
We consider the relationship between stationary distributions for stochastic models of reaction systems and Lyapunov functions for their deterministic counterparts. Specifically, we derive the well-known Lyapunov function of reaction network theory as a scaling limit of the non-equilibrium potent......We consider the relationship between stationary distributions for stochastic models of reaction systems and Lyapunov functions for their deterministic counterparts. Specifically, we derive the well-known Lyapunov function of reaction network theory as a scaling limit of the non......-equilibrium potential of the stationary distribution of stochastically modeled complex balanced systems. We extend this result to general birth-death models and demonstrate via example that similar scaling limits can yield Lyapunov functions even for models that are not complex or detailed balanced, and may even have...
The truncated lognormal distribution as a luminosity function for SWIFT-BAT gamma-ray bursts
Zaninetti, L
2016-01-01
The determination of the luminosity function (LF) in gamma ray bursts (GRBs) depends on the adopted cosmology, each one characterized by its corresponding luminosity distance. Here we analyse three cosmologies: the standard cosmology, the plasma cosmology, and the pseudo-Euclidean universe. The LF of the GRBs is firstly modeled by the lognormal distribution and the four broken power law, and secondly by a truncated lognormal distribution. The truncated lognormal distribution fits acceptably the range in luminosity of GRBs as a function of the redshift.
The Truncated Lognormal Distribution as a Luminosity Function for SWIFT-BAT Gamma-Ray Bursts
Directory of Open Access Journals (Sweden)
Lorenzo Zaninetti
2016-11-01
Full Text Available The determination of the luminosity function (LF in Gamma ray bursts (GRBs depends on the adopted cosmology, each one characterized by its corresponding luminosity distance. Here, we analyze three cosmologies: the standard cosmology, the plasma cosmology and the pseudo-Euclidean universe. The LF of the GRBs is firstly modeled by the lognormal distribution and the four broken power law and, secondly, by a truncated lognormal distribution. The truncated lognormal distribution fits acceptably the range in luminosity of GRBs as a function of the redshift.
Quark distribution functions in the chiral quark-soliton model cancellation of quantum anomalies
Göke, K; Polyakov, M V; Schweitzer, P; Urbano, D
2001-01-01
In the framework of the chiral quark-soliton model of the nucleon we investigate the properties of the polarized quark distribution. In particular we analyse the so called anomalous difference between the representations of the quark distribution functions in terms of occupied and non-occupied quark states. By an explicit analytical calculation it is shown that this anomaly is absent in the polarized isoscalar distribution \\Delta u + \\Delta d, which is ultaviolet finite. In the case of the polarized isovector quark distribution which is also needed for the regularization of the ultraviolet divergence.
Institute of Scientific and Technical Information of China (English)
Hong Tang; Xiaogang Sun; Guibin Yuan
2007-01-01
In total light scattering particle sizing technique, the relationship among Sauter mean diameter D32, mean extinction efficiency Q, and particle size distribution function is studied in order to inverse the mean diameter and particle size distribution simply. We propose a method which utilizes the mean extinction efficiency ratio at only two selected wavelengths to solve D32 and then to inverse the particle size distribution associated with (Q) and D32. Numerical simulation results show that the particle size distribution is inversed accurately with this method, and the number of wavelengths used is reduced to the greatest extent in the measurement range. The calculation method has the advantages of simplicity and rapidness.
Gurgiolo, Chris; Vinas, Adolfo F.
2009-01-01
This paper presents a spherical harmonic analysis of the plasma velocity distribution function using high-angular, energy, and time resolution Cluster data obtained from the PEACE spectrometer instrument to demonstrate how this analysis models the particle distribution function and its moments and anisotropies. The results show that spherical harmonic analysis produced a robust physical representation model of the velocity distribution function, resolving the main features of the measured distributions. From the spherical harmonic analysis, a minimum set of nine spectral coefficients was obtained from which the moment (up to the heat flux), anisotropy, and asymmetry calculations of the velocity distribution function were obtained. The spherical harmonic method provides a potentially effective "compression" technique that can be easily carried out onboard a spacecraft to determine the moments and anisotropies of the particle velocity distribution function for any species. These calculations were implemented using three different approaches, namely, the standard traditional integration, the spherical harmonic (SPH) spectral coefficients integration, and the singular value decomposition (SVD) on the spherical harmonic methods. A comparison among the various methods shows that both SPH and SVD approaches provide remarkable agreement with the standard moment integration method.
Anselmino, M.; Avakian, H.; Boer, Daniël; Bradamante, F.; Burkardt, M.; Chen, J.P.; Cisbani, E.; Contalbrigo, M.; Crabb, D.; Dutta, D.; Gamberg, L.; Gao, H.; Hasch, D.; Huang, J.; Huang, M.; Kang, Z.; Keppel, C.; Laskaris, G.; Liang, Z.-T.; Liu, M.X.; Makins, N.; McKeown, R.D.; Metz, A.; Meziani, Z.-E.; Musch, B.; Peng, J.-C.; Prokudin, A.; Qian, X.; Qiang, Y.; Qiu, J.W.; Rossi, P.; SCHWEITZER, C.; Soffer, J.; Sulkosky, V.; Wang, Ying; Xiao, B.; Ye, Q.; Ye, Q.-J.; Yuan, F.; Zhan, X.; Zhang, Y.; Zheng, W.; Zhou, J.
2011-01-01
We present a summary of a recent workshop held at Duke University on Partonic Transverse Momentum in Hadrons: Quark Spin-Orbit Correlations and Quark-Gluon Interactions. The transverse-momentum-dependent parton distribution functions (TMDs), parton-to-hadron fragmentation functions, and multi-parton
New Requirements of the Voltage/VAR Function for Smart Inverter in Distributed Generation Control
Directory of Open Access Journals (Sweden)
Yun-Su Kim
2016-11-01
Full Text Available International Electronical Committee (IEC 61850-90-7 is a part of the IEC 61850 series which specifies the advanced functions and object models for power converter based Distributed Energy Resources (DERs. One of its functions, the Voltage/VAR (V/V control function, is used to enhance the stability and the reliability of the voltage in the distribution system. The conventional V/V function acts mainly for flattening the voltage profile as for a basic grid support function. Currently, other objectives such as the minimization of line loss and the operational costs reduction are coming into the spotlight. In order to attain these objectives, the V/V function and hence the DER units shall actively respond to the change of distribution system conditions. In this paper, the modification of V/V function and new requirements are proposed. To derive new requirements of V/V function, loss minimization is applied to a particle swarm optimization (PSO algorithm where the condition of voltage constraint is considered not to deteriorate the voltage stability of the distribution system.
RADIAL DISTRIBUTION FUNCTION OF cis-1,4-POLYBUTADIENE BY ELECTRON DIFFRACTION
Institute of Scientific and Technical Information of China (English)
ZHOU Enle; KAN Xianglan; ZHAO Xiaoguang
1983-01-01
The interatomic distance function of rareearth catalyzed cis-1,4-polybutadiene was studied by radial distribution function (RDF) derived from electron diffraction. Two intramolecular peaks and three intermolecular peaks have been found on the RDF. The appearance of such a number of intermolecular maxima on the RDF can be explained by the local parallel packing of long molecular chains of the amorphous polymers.
Roussel-Dupre, R.
1979-01-01
It was shown that, in the presence of the steep temperature gradients characteristic of EUV models of the solar transition region, the electron and proton velocity distribution functions are non-Maxwellian and are characterized by high energy tails. The magnitude of these tails are estimated for a model of the transition region and the heat flux is calculated at a maximum of 30 percent greater than predicted by collision-dominated theory.
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
Applying 3-dimension finite difference method, the distribution characteristics of horizontal field transfer func-tions for rectangular conductor have been computed, and the law of distribution for Re-part and Im-part has been given. The influences of source field period, the conductivity, the buried depth and the length of the conductor on the transfer functions were studied. The extrema of transfer functions appear at the center, the four corners and around the edges of conductor, and move with the edges. This feature demonstrates that around the edges are best places for transfer functions￠ observation.
Bayes Estimation of Shape Parameter of Minimax Distribution under Different Loss Functions
Directory of Open Access Journals (Sweden)
Lanping Li
2015-04-01
Full Text Available The object of this study is to study the Bayes estimation of the unknown shape parameter of Minimax distribution. The prior distribution used here is the non-informative quasi-prior of the parameter. Bayes estimators are derived under squared error loss function and three asymmetric loss functions, which are the LINEX loss, precaution loss and entropy loss functions. Monte Carlo simulations are performed to compare the performances of these Bayes estimates under different situations. Finally, we summarize the result and give the conclusion of this study.
Institute of Scientific and Technical Information of China (English)
LIU Wuxiang; MA Shaokun; WU Hao
2014-01-01
An orthotropic functionally graded piezoelectric rectangular plate with arbitrarily distributed material properties was studied, which is simply supported and grounded (electrically) on its four lateral edges. The state equations of the functionally graded piezoelectric material were obtained using the state-space approach, and a Peano-Baker series solution was obtained for the coupled electroelastic fields of the functionally graded piezoelectric plate subjected to mechanical and electric loading on its upper and lower surfaces. The influence of different distributions of material properties on the structural response of the plate was studied using the obtained solutions.
On the use of functional calculus for phase-type and related distributions
DEFF Research Database (Denmark)
Bladt, Mogens; Campillo Navarro, Azucena; Nielsen, Bo Friis
of matrices. Functional calculus, which is a branch of operator theory frequently associated with complex analysis, can be applied to phase-type and matrix-exponential distributions in a rather straightforward way. In this paper we provide a number of examples on how to execute the formal arguments.......The area of phase-type distributions is renowned for its ability to obtain closed form formulas or algorithmically exact solutions to many complex stochastic models. The method of functional calculus will provide an additional tool along these lines for establishing results in terms of functions...
On the use of functional calculus for phase-type and related distributions
DEFF Research Database (Denmark)
Bladt, Mogens; Navarro, Azucena Campillo; Nielsen, Bo Friis
2016-01-01
of matrices. Functional calculus, which is a branch of operator theory frequently associated with complex analysis, can be applied to phase-type and matrix-exponential distributions in a rather straightforward way. In this article we provide a number of examples of how to execute the formal arguments.......The area of phase-type distributions is renowned for its ability to obtain closed form formulas or algorithmically exact solutions to many complex stochastic models. The method of functional calculus will provide an additional tool along these lines for establishing results in terms of functions...
Lyapunov Functions, Stationary Distributions, and Non-equilibrium Potential for Reaction Networks.
Anderson, David F; Craciun, Gheorghe; Gopalkrishnan, Manoj; Wiuf, Carsten
2015-09-01
We consider the relationship between stationary distributions for stochastic models of reaction systems and Lyapunov functions for their deterministic counterparts. Specifically, we derive the well-known Lyapunov function of reaction network theory as a scaling limit of the non-equilibrium potential of the stationary distribution of stochastically modeled complex balanced systems. We extend this result to general birth-death models and demonstrate via example that similar scaling limits can yield Lyapunov functions even for models that are not complex or detailed balanced, and may even have multiple equilibria.
Directory of Open Access Journals (Sweden)
SANKU DEY
2010-11-01
Full Text Available The generalized exponential (GE distribution proposed by Gupta and Kundu (1999 is an important lifetime distribution in survival analysis. In this article, we propose to obtain Bayes estimators and its associated risk based on a class of non-informative prior under the assumption of three loss functions, namely, quadratic loss function (QLF, squared log-error loss function (SLELF and general entropy loss function (GELF. The motivation is to explore the most appropriate loss function among these three loss functions. The performances of the estimators are, therefore, compared on the basis of their risks obtained under QLF, SLELF and GELF separately. The relative efficiency of the estimators is also obtained. Finally, Monte Carlo simulations are performed to compare the performances of the Bayes estimates under different situations.
Lamparter, Tilman
2006-03-16
Phytochromes are photoreceptors, discovered in plants, that control a wide variety of developmental processes. They have also been found in bacteria and fungi, but for many species their biological role remains obscure. This work concentrates on the phytochrome system of Agrobacterium tumefaciens, a non-photosynthetic soil bacterium with two phytochromes. To identify proteins that might share common functions with phytochromes, a co-distribution analysis was performed on the basis of protein sequences from 138 bacteria. A database of protein sequences from 138 bacteria was generated. Each sequence was BLASTed against the entire database. The homolog distribution of each query protein was then compared with the homolog distribution of every other protein (target protein) of the same species, and the target proteins were sorted according to their probability of co-distribution under random conditions. As query proteins, phytochromes from Agrobacterium tumefaciens, Pseudomonas aeruginosa, Deinococcus radiodurans and Synechocystis PCC 6803 were chosen along with several phytochrome-related proteins from A. tumefaciens. The Synechocystis photosynthesis protein D1 was selected as a control. In the D1 analyses, the ratio between photosynthesis-related proteins and those not related to photosynthesis among the top 150 in the co-distribution tables was > 3:1, showing that the method is appropriate for finding partner proteins with common functions. The co-distribution of phytochromes with other histidine kinases was remarkably high, although most co-distributed histidine kinases were not direct BLAST homologs of the query protein. This finding implies that phytochromes and other histidine kinases share common functions as parts of signalling networks. All phytochromes tested, with one exception, also revealed a remarkably high co-distribution with glutamate synthase and methionine synthase. This result implies a general role of bacterial phytochromes in ammonium
th-Nearest neighbour distribution functions of a binary fluid mixture
Indian Academy of Sciences (India)
P Sur; B Bhattacharjee
2009-09-01
For obtaining microscopic structural information in binary mixtures, often partial pair correlation functions are used. In the present study, a general approach is presented for obtaining the neighbourhood structural information for binary mixtures in terms of nth nearest neighbour distribution (NND) functions (for = 1, 2, 3, ...$\\ldots$). These functions are derived from the partial pair correlation functions in a hierarchical manner, based on the approach adopted earlier by us for single component fluids. Comparison of the results with MD simulation for Lennard-Jones binary mixtures is also presented. NND functions show reasonable matching for smaller n values particularly at higher density. The average th nearest neighbour distance shows interesting feature.
Geometrical approach to the distribution of the zeroes for the Husimi function
Toscano, F; Toscano, Fabricio; Almeida, Alfredo M. Ozorio de
1999-01-01
We construct a semiclassical expression for the Husimi function of autonomous systems in one degree of freedom, by smoothing with a Gaussian function an expression that captures the essential features of the Wigner function in the semiclassical limit. Our approximation reveals the "center and chord" estructure that the Husimi function inherits from the Wigner function, down to very shallow "valleys", where lie the Husimi zeroes. This explanation for the distribution of zeroes along curves relies on the geometry of the classical torus, rather than the complex analytical properties of the WKB method in the Bargmann representation. We evaluate the zeroes for several examples.
Analytical evaluation of the plasma dispersion function for a Fermi-Dirac distribution
Institute of Scientific and Technical Information of China (English)
B.A. Mamedov
2012-01-01
An efficient method for the analytic evaluation of the plasma dispersion function for the Fermi-Dirac distribution is proposed.The new method has been developed using the binomial expansion theorem and the Gamma functions.The general formulas obtained for the plasma dispersion function are utilized for the evaluation of the response function.The resulting series present better convergence rates.Several acceleration techniques are combined to further improve the efficiency.The obtained results for the plasma dispersion function are in good agreement with the known numerical data.
Random matrices, generalized zeta functions and self-similarity of zero distributions
Energy Technology Data Exchange (ETDEWEB)
Shanker, O [Bitfone Corporation, 32451 Golden Lantern Ste. 301, Laguna Niguel, CA 92677 (United States)
2006-11-10
There is growing evidence for a connection between random matrix theories used in physics and the theory of the Riemann zeta function and L-functions. The theory underlying the location of the zeros of these generalized zeta functions is one of the key unsolved problems. Physicists are interested because of the Hilbert-Polya conjecture, that the non-trivial zeros of the zeta function correspond to the eigenvalues of some positive operator. To complement the continuing theoretical work, it would be useful to study empirically the locations of the zeros by different methods. In this paper we use the rescaled range analysis to study the spacings between successive zeros of these functions. Over large ranges of the zeros the spacings have a Hurst exponent of about 0.095, using sample sizes of 10 000 zeros. This implies that the distribution has a high fractal dimension (1.9), and shows a lot of detailed structure. The distribution is of the anti-persistent fractional Brownian motion type, with a significant degree of anti-persistence. Thus, the high-order zeros of these functions show a remarkable self-similarity in their distribution, over fifteen orders of magnitude for the Riemann zeta function{exclamation_point} We find that the Hurst exponents for the random matrix theories show a different behaviour. A heuristic study of the effect of low-order primes seems to show that this effect is a promising candidate to explain the results that we observe in this study. We study the distribution of zeros for L-functions of conductors 3 and 4, and find that the distribution is similar to that of the Riemann zeta functions.
Zirnstein, E. J.; McComas, D. J.
2015-12-01
Kappa functions have long been used in the analysis and modeling of suprathermal particles in various space plasmas. In situ observations of the supersonic solar wind show its distribution contains a cold ion core and power-law tail, which is well-represented by a kappa function. In situ plasma observations by Voyager, as well as observations of energetic neutral atom (ENA) spectra by the Interstellar Boundary Explorer (IBEX), showed that the compressed and heated inner heliosheath (IHS) plasma beyond the termination shock can also be represented by a kappa function. IBEX exposes the IHS plasma properties through the detection of ENAs generated by charge-exchange in the IHS. However, charge-exchange modifies the plasma as it flows through the IHS, and makes it difficult to ascertain the parent proton distribution. In this paper we investigate the evolution of proton distributions, initially represented by a kappa function, that experience losses due to charge-exchange in the IHS. In the absence of other processes, it is no longer representable by a single kappa function due to the energy-dependent, charge-exchange process. While one can still fit a kappa function to the evolving proton distribution over limited energy ranges, this yields fitting parameters (pseudo-density, pseudo-temperature, pseudo-kappa index) that depend on the energy range of the fit. We discuss the effects of fitting a kappa function to the IHS proton distribution over limited energy ranges, its dependence on the initial proton distribution properties at the termination shock, and implications for understanding the observations.
Energy Technology Data Exchange (ETDEWEB)
Zirnstein, E. J.; McComas, D. J., E-mail: ezirnstein@swri.edu, E-mail: dmccomas@swri.edu [Southwest Research Institute, San Antonio, TX 78228 (United States)
2015-12-10
Kappa functions have long been used in the analysis and modeling of suprathermal particles in various space plasmas. In situ observations of the supersonic solar wind show its distribution contains a cold ion core and power-law tail, which is well-represented by a kappa function. In situ plasma observations by Voyager, as well as observations of energetic neutral atom (ENA) spectra by the Interstellar Boundary Explorer (IBEX), showed that the compressed and heated inner heliosheath (IHS) plasma beyond the termination shock can also be represented by a kappa function. IBEX exposes the IHS plasma properties through the detection of ENAs generated by charge-exchange in the IHS. However, charge-exchange modifies the plasma as it flows through the IHS, and makes it difficult to ascertain the parent proton distribution. In this paper we investigate the evolution of proton distributions, initially represented by a kappa function, that experience losses due to charge-exchange in the IHS. In the absence of other processes, it is no longer representable by a single kappa function due to the energy-dependent, charge-exchange process. While one can still fit a kappa function to the evolving proton distribution over limited energy ranges, this yields fitting parameters (pseudo-density, pseudo-temperature, pseudo-kappa index) that depend on the energy range of the fit. We discuss the effects of fitting a kappa function to the IHS proton distribution over limited energy ranges, its dependence on the initial proton distribution properties at the termination shock, and implications for understanding the observations.
Indian Academy of Sciences (India)
N Barik; R N Mishra
2001-04-01
Considering the nucleon as consisting entirely of its valence quarks conﬁned independently in a scalar-vector harmonic potential; unpolarized structure functions 1(,2) and 2(x,2) are derived in the Bjorken limit under certain simplifying assumptions; from which valence quark distribution functions (,2) and (,2) are appropriately extracted satisfying the normalization constraints. QCD-evolution of these input distributions from a model scale of 2=0.07 GeV2 to a higher $Q^{2}$ scale of $Q^{2}_{0} = 15$ GeV2 yields (, $Q^{2}_{0}$) and (, $Q^{2}_{0}$) in good agreement with experimental data. The gluon and sea-quark distributions such as (,$Q^{2}_{0}$) and (, $Q^{2}_{0}$) are dynamically generated with a reasonable qualitative agreement with the available data; using the leading order renormalization group equations with appropriate valence-quark distributions as the input.
Yazdanpanah, N.; Tavassoly, M. K.; Juárez-Amaro, R.; Moya-Cessa, H. M.
2017-10-01
We study the possibility of reconstructing the quantum state of light in a cavity subject to dissipation. We pass atoms, also subject to decay, through the cavity and surprisingly show that both decays allow the measurement of s-parametrized quasiprobability distributions. In fact, if we consider only atomic decay, we show that the Wigner function may be reconstructed. Because these distributions contain whole information of the initial field state, it is possible to recover information after both atomic and field decays occur.
Fitness function distributions over generalized search neighborhoods in the q-ary hypercube.
Sutton, Andrew M; Chicano, Francisco; Whitley, L Darrell
2013-01-01
The frequency distribution of a fitness function over regions of its domain is an important quantity for understanding the behavior of algorithms that employ randomized sampling to search the function. In general, exactly characterizing this distribution is at least as hard as the search problem, since the solutions typically live in the tails of the distribution. However, in some cases it is possible to efficiently retrieve a collection of quantities (called moments) that describe the distribution. In this paper, we consider functions of bounded epistasis that are defined over length-n strings from a finite alphabet of cardinality q. Many problems in combinatorial optimization can be specified as search problems over functions of this type. Employing Fourier analysis of functions over finite groups, we derive an efficient method for computing the exact moments of the frequency distribution of fitness functions over Hamming regions of the q-ary hypercube. We then use this approach to derive equations that describe the expected fitness of the offspring of any point undergoing uniform mutation. The results we present provide insight into the statistical structure of the fitness function for a number of combinatorial problems. For the graph coloring problem, we apply our results to efficiently compute the average number of constraint violations that lie within a certain number of steps of any coloring. We derive an expression for the mutation rate that maximizes the expected fitness of an offspring at each fitness level. We also apply the results to the slightly more complex frequency assignment problem, a relevant application in the domain of the telecommunications industry. As with the graph coloring problem, we provide formulas for the average value of the fitness function in Hamming regions around a solution and the expectation-optimal mutation rate.
Banik, S K; Ray, D S; Banik, Suman Kumar; Bag, Bidhan Chandra; Ray, Deb Shankar
2002-01-01
Traditionally, the quantum Brownian motion is described by Fokker-Planck or diffusion equations in terms of quasi-probability distribution functions, e.g., Wigner functions. These often become singular or negative in the full quantum regime. In this paper a simple approach to non-Markovian theory of quantum Brownian motion using {\\it true probability distribution functions} is presented. Based on an initial coherent state representation of the bath oscillators and an equilibrium canonical distribution of the quantum mechanical mean values of their co-ordinates and momenta we derive a generalized quantum Langevin equation in $c$-numbers and show that the latter is amenable to a theoretical analysis in terms of the classical theory of non-Markovian dynamics. The corresponding Fokker-Planck, diffusion and the Smoluchowski equations are the {\\it exact} quantum analogues of their classical counterparts. The present work is {\\it independent} of path integral techniques. The theory as developed here is a natural ext...
Peano on derivative of measures, strict derivative of distributive set functions
Greco, Gabriele H; Pagani, Enrico M
2010-01-01
By retracing research on coexistent magnitudes (grandeurs coexistantes) by Cauchy (1841), Peano in "Applicazioni geometriche del calcolo infinitesimale" (1887) defines the "density" (strict derivative) of a "mass" (a distributive set function) with respect to a "volume" (a positive distributive set function), proves its continuity (whenever the strict derivative exists) and shows the validity of the mass-density paradigm: "mass" is recovered from "density" by integration with respect to "volume". It is remarkable that Peano's strict derivative provides a consistent mathematical ground to the concept of "infinitesimal ratio" between two magnitudes, successfully used since Kepler. In this way the classical (i.e., pre-Lebesgue) measure theory reaches a complete and definitive form in Peano's Applicazioni geometriche. A primary aim of the present paper is a detailed exposition of Peano's work of 1887 leading to the concept of strict derivative of distributive set functions and their use. Moreover, we compare Pean...
Dust heating by Alfvén waves using non-Maxwellian distribution function
Energy Technology Data Exchange (ETDEWEB)
Zubia, K. [Department of Physics, Government College University, Lahore 54000 (Pakistan); Shah, H. A. [Department of Physics, Forman Christian College, Lahore 54600 (Pakistan); Yoon, P. H. [Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742 (United States); School of Space Research, Kyung Hee University, Yongin, Gyeonggi 446-701 (Korea, Republic of)
2015-08-15
Quasilinear theory is employed in order to evaluate the resonant heating rate by Alfvén waves, of multiple species dust particles in a hot, collisionless, and magnetized plasma, with the underlying assumption that the dust velocity distribution function can be modeled by a generalized (r, q) distribution function. The kinetic linear dispersion relation for the electromagnetic dust cyclotron Alfvén waves is derived, and the dependence of the heating rate on the magnetic field, mass, and density of the dust species is subsequently investigated. The heating rate and its dependence on the spectral indices r and q of the distribution function are also investigated. It is found that the heating is sensitive to negative value of spectral index r.
Di Troia, Claudio
2015-01-01
A class of parametric distribution functions has been proposed in [C.DiTroia, Plasma Physics and Controlled Fusion,54,2012] as equilibrium distribution functions (EDFs) for charged particles in fusion plasmas, representing supra-thermal particles in anisotropic equilibria for Neutral Beam Injection, Ion Cyclotron Heating scenarios. Moreover, the EDFs can also represent nearly isotropic equilibria for Slowing-Down $alpha$ particles and core thermal plasma populations. These EDFs depend on constants of motion (COMs). Assuming an axisymmetric system with no equilibrium electric field, the EDF depends on the toroidal canonical momentum $P_\\phi$, the kinetic energy $w$ and the magnetic moment \\mu. In the present work, the EDFs are obtained from first principles and general hypothesis. The derivation is probabilistic and makes use of the Bayes' Theorem. The bayesian argument allows us to describe how far from the prior probability distribution function (pdf), e.g. Maxwellian, the plasma is, based on the information...
Electron Distribution Functions in the Diffusion Region of Asymmetric Magnetic Reconnection
Bessho, N.; Chen, L.-J.; Hesse, M.
2016-01-01
We study electron distribution functions in a diffusion region of antiparallel asymmetric reconnection by means of particle-in-cell simulations and analytical theory. At the electron stagnation point, the electron distribution comprises a crescent-shaped population and a core component. The crescent-shaped distribution is due to electrons coming from the magnetosheath toward the stagnation point and accelerated mainly by electric field normal to the current sheet. Only a part of magnetosheath electrons can reach the stagnation point and form the crescent-shaped distribution that has a boundary of a parabolic curve. The penetration length of magnetosheath electrons into the magnetosphere is derived. We expect that satellite observations can detect crescent-shaped electron distributions during magnetopause reconnection.
Sarabia, José María; Jordá, Vanesa
2014-12-01
The importance of the Pietra index in socioeconomic systems and econophysics has been highlighted by Eliazar and Sokolov (2010). In this paper, we obtain closed expressions for the Pietra index for the generalized function for the size of income proposed by McDonald (1984). This family is composed of three classes of distributions: the generalized gamma distribution (GG), the generalized beta of the first kind (GB1) and the generalized beta of the second kind (GB2). For the different distributions, we obtain closed and simple expressions of the Pietra index, which can be easily computed. We also obtain the Pietra index for other relevant income models including finite mixtures of distributions and the κ-generalized distribution (Clementi et al., 2008). Finally, two empirical applications with real income data are given.
Electron Velocity Distribution Function in Magnetic Clouds in the Solar Wind
Nieves-Chinchil, Teresa; Vinas, Adolfo F.; Bale, Stuart D.
2006-01-01
We present a study of the kinetic properties of the electron velocity distribution functions within magnetic clouds, since they are the dominant thermal component. The study is based on high time resolution data from the GSFC WIND/SWE electron spectrometer and the Berkeley 3DP electron plasma instruments. Recent studies on magnetic clouds have shown observational evidence of anti-correlation between the total electron density and electron temperature, which suggest a polytrope law P(sub e) = alpha(Nu(sub e) (sup gamma)) for electrons with the constant gamma approximates 0.5 non-Maxwellian electron distributions (i.e. non-thermal) within magnetic clouds. These works suggested that the non-thermal electrons can contribute as much as 50% of the total electron pressure within magnetic clouds. We have revisited some of the magnetic cloud events previously studied and attempted to quantify the nature of the non-thermal electrons by modeling the electron velocity distribution function using a kappa distribution function to characterize the kinetic non-thermal effects. If non-thermal tail effects are the source for the anti-correlation between the moment electron temperature and density and if the kappa distribution is a reasonable representative model of non-thermal effects, then the electron velocity distribution within magnetic clouds should show indication for small K-values when gamma < 1.
Electron Distribution Functions in Solar Flares from combined X-ray and EUV Observations
Battaglia, Marina
2013-01-01
Simultaneous solar flare observations with SDO and RHESSI provide spatially resolved information about hot plasma and energetic particles in flares. RHESSI allows the properties of both hot (> 8 MK) thermal plasma and nonthermal electron distributions to be inferred, while SDO/AIA is more sensitive to lower temperatures. We present and implement a new method to reconstruct electron distribution functions from SDO/AIA data. The combined analysis of RHESSI and AIA data allows the electron distribution function to be inferred over the broad energy range from ~0.1 keV up to a few tens of keV. The analysis of two well observed flares suggests that the distributions in general agree to within a factor of three when the RHESSI values are extrapolated into the intermediate range 1-3 keV, with AIA systematically predicting lower electron distributions. Possible instrumental and numerical effects, as well as potential physical origins for this discrepancy are discussed. The inferred electron distribution functions in g...
Meson cloud effects on the pion quark distribution function in the chiral constituent quark model
Watanabe, Akira; Suzuki, Katsuhiko
2016-01-01
We investigate the valence quark distribution function of the pion $v^{\\pi}(x,Q^2)$ in the framework of the chiral constituent quark model and evaluate the meson cloud effects on $v^{\\pi}(x,Q^2)$. We explicitly demonstrate how the meson cloud effects affect $v^{\\pi}(x,Q^2)$ in detail. We find that the meson cloud correction causes an overall 32\\% reduction of the valence quark distribution and an enhancement at the small Bjorken $x$ regime. Besides, we also find that the dressing effect of the meson cloud will make the valence quark distribution to be softer in the large $x$ region.
Lobach, I.; Benediktovitch, A.
2016-07-01
The possibility of quantitative texture analysis by means of parametric x-ray radiation (PXR) from relativistic electrons with Lorentz factor γ > 50MeV in a polycrystal is considered theoretically. In the case of rather smooth orientation distribution function (ODF) and large detector (θD >> 1/γ) the universal relation between ODF and intensity distribution is presented. It is shown that if ODF is independent on one from Euler angles, then the texture is fully determined by angular intensity distribution. Application of the method to the simulated data shows the stability of the proposed algorithm.
The role of the Fox-Wright functions in fractional sub-diffusion of distributed order
Mainardi, Francesco
2007-01-01
The fundamental solution of the fractional diffusion equation of distributed order in time (usually adopted for modelling sub-diffusion processes) is obtained based on its Mellin-Barnes integral representation. Such solution is proved to be related via a Laplace-type integral to the Fox-Wright functions. A series expansion is also provided in order to point out the distribution of time-scales related to the distribution of the fractional orders. The results of the time fractional diffusion equation of a single order are also recalled and then re-obtained from the general theory.
Achievements and open issues in the determination of polarized parton distribution functions
Nocera, Emanuele R
2015-01-01
I review the current status of the determination of helicity-dependent, or polarized, parton distribution functions from a comprehensive analysis of experimental data in perturbative quantum chromodynamics. I illustrate the latest achievements driven by new measurements in polarized proton-proton collisions at the Relativistic Heavy Ion Collider, namely the first evidence of a sizable polarized light sea quark asymmetry and of a positive polarized gluon distribution in the proton. I discuss which are the open issues in the determination of polarized distributions, and how these may be addressed in the future by ongoing, planned and proposed experimental programs.
Energy Technology Data Exchange (ETDEWEB)
Schroeder, J. W. R., E-mail: james-schroeder@uiowa.edu; Skiff, F.; Howes, G. G.; Kletzing, C. A. [Department of Physics and Astronomy, University of Iowa, Iowa City, Iowa 52242 (United States); Carter, T. A.; Dorfman, S. [Department of Physics and Astronomy, University of California, Los Angeles, California 90095-1547 (United States)
2015-12-10
Wave propagation can be an accurate method for determining material properties. High frequency whistler mode waves (0.7 < ω/|Ω{sub ce}| < 1) in an overdense plasma (ω{sub pe} > |Ω{sub ce}|) are damped primarily by Doppler-shifted electron cyclotron resonance. A kinetic description of whistler mode propagation parallel to the background magnetic field shows that damping is proportional to the parallel electron distribution function. This property enables an experimental determination of the parallel electron distribution function using a measurement of whistler mode wave absorption. The whistler mode wave absorption diagnostic uses this technique on UCLA’s Large Plasma Device (LaPD) to measure the distribution of high energy electrons (5 − 10v{sub te}) with 0.1% precision. The accuracy is limited by systematic effects that need to be considered carefully. Ongoing research uses this diagnostic to investigate the effect of inertial Alfvén waves on the electron distribution function. Results presented here verify experimentally the linear effects of inertial Alfvén waves on the reduced electron distribution function, a necessary step before nonlinear physics can be tested. Ongoing experiments with the whistler mode wave absorption diagnostic are making progress toward the first direct detection of electrons nonlinearly accelerated by inertial Alfvén waves, a process believed to play an important role in auroral generation.
Soot Particle Size Distribution Functions in a Turbulent Non-Premixed Ethylene-Nitrogen Flame
Boyette, Wesley
2017-02-21
A scanning mobility particle sizer with a nano differential mobility analyzer was used to measure nanoparticle size distribution functions in a turbulent non-premixed flame. The burner utilizes a premixed pilot flame which anchors a C2H4/N2 (35/65) central jet with ReD = 20,000. Nanoparticles in the flame were sampled through a N2-filled tube with a 500- μm orifice. Previous studies have shown that insufficient dilution of the nanoparticles can lead to coagulation in the sampling line and skewed particle size distribution functions. A system of mass flow controllers and valves were used to vary the dilution ratio. Single-stage and two-stage dilution systems were investigated. A parametric study on the effect of the dilution ratio on the observed particle size distribution function indicates that particle coagulation in the sampling line can be eliminated using a two-stage dilution process. Carbonaceous nanoparticle (soot) concentration particle size distribution functions along the flame centerline at multiple heights in the flame are presented. The resulting distributions reveal a pattern of increasing mean particle diameters as the distance from the nozzle along the centerline increases.
Energy Technology Data Exchange (ETDEWEB)
Diefenthaler, Markus
2010-08-15
Intention of the present thesis was the study of transverse-momentum dependent quark distribution functions. In the focus stood the Fourier analysis of azimutal single-spin asymmetries of pions and charged kaons performed within the HERMES experiment. These asymmetries were reconstructed from deep-inelastic scattering events on a transversely polarized proton target and decomposed in Fourier components. In the framework of quantum chromodynamics such components can be interpreted as folding of quark distribution and fragmentation functions. By the analysis of the transverse-momentum dependent quark distribution functions the study of spin-orbit correlations in the internal of the nucleon was made possible. By this conclusions on the orbital angular momentum of the quarks can be drawn. The extracted Fourier components extend the hitherto available informations on the transverse-momentum dependent quark distribution functions remarkably. The presented Fourier analysis made not only a detection of the Collins and Sivers effects possible, but beyond the extraction of the signals of the pretzelosity and worm-gear distributions. The so obtained results will conclusively contribute to the understanding of future measurements in this field and furthermore make possible a test of fundamental predictions of quantum chromodynamics.
Directory of Open Access Journals (Sweden)
Anupam Pathak
2014-11-01
Full Text Available Abstract: Problem Statement: The two-parameter exponentiated Rayleigh distribution has been widely used especially in the modelling of life time event data. It provides a statistical model which has a wide variety of application in many areas and the main advantage is its ability in the context of life time event among other distributions. The uniformly minimum variance unbiased and maximum likelihood estimation methods are the way to estimate the parameters of the distribution. In this study we explore and compare the performance of the uniformly minimum variance unbiased and maximum likelihood estimators of the reliability function R(t=P(X>t and P=P(X>Y for the two-parameter exponentiated Rayleigh distribution. Approach: A new technique of obtaining these parametric functions is introduced in which major role is played by the powers of the parameter(s and the functional forms of the parametric functions to be estimated are not needed. We explore the performance of these estimators numerically under varying conditions. Through the simulation study a comparison are made on the performance of these estimators with respect to the Biasness, Mean Square Error (MSE, 95% confidence length and corresponding coverage percentage. Conclusion: Based on the results of simulation study the UMVUES of R(t and ‘P’ for the two-parameter exponentiated Rayleigh distribution found to be superior than MLES of R(t and ‘P’.
The twist-3 parton distribution function e(x) in large-Nc chiral theory
Cebulla, C; Schweitzer, P; Urbano, D
2007-01-01
The chirally-odd twist-3 parton distribution function e(x) of the nucleon is studied in the large-Nc limit in the framework of the chiral quark-soliton model. It is demonstrated that in spite of properties not shared by other distribution functions, namely the appearance of a delta(x)-singularity and quadratic divergences in e(x), an equally reliable calculation is possible. Among the most remarkable results obtained in this work is the fact that the coefficient of the delta(x)-singularity can be computed exactly in this model, avoiding involved numerics. Our results complete existing studies in literature.
Incoherent scatter spectra from plasma of a 13-moment approximation distribution function
Institute of Scientific and Technical Information of China (English)
2008-01-01
The function and physical mechanism of heat flow and the viscous stress in the velocity distribution function expanded by Maxwellian distribution are presented. With the introduction of effective temperature Tf, incoherent scatter spectra from plasma for electromagnetic wave in arbitrary line of sight are given. The effect of asymmetry and anisotropy provided by heat flow and the viscous stress on power spectra is discussed. Radar spectra are calculated for different cases of electric field, direction, collision frequency and temperature. The effect of heat flow and the viscous stress on inversion results is analyzed. With a large electric field, the character of non-Maxwellian must be considered.
Evaluation of mobile dislocation density based on distribution function of dislocation segments
Institute of Scientific and Technical Information of China (English)
周志敏; 孙艳蕊; 周海涛
2004-01-01
A function is offered to represent the distribution of reduced length of dislocation segments. The segment distribution of materials, e. g. , MgO and Cu, can be well described by taking appropriate values of parametersm and n. Based on this function, a model for evaluating the mobile dislocation density is developed. Provided the total dislocation density and applied stress are known, the mobile dislocation density could be readily assessed by using this model. For pure copper the mobile dislocation density and strain rates at deferent strains are evaluated. The calculated results are consistent with the known experimental data.
On the approximations of the distribution function of fusion alpha particles
Energy Technology Data Exchange (ETDEWEB)
Bilato, R., E-mail: roberto.bilato@ipp.mpg.de; Brambilla, M.; Poli, E. [Max Planck Institute for Plasma Physics, EURATOM Association, Boltzmannstr. 2, 85748 Garching (Germany)
2014-10-15
The solution of the drift-kinetic equation for fusion-born alpha particles is derived in the limit of dominant parallel streaming, and it is related to the usual slowing-down distribution function. The typical approximations of the fast tail of fusion-born alpha particles are briefly compared and discussed. In particular, approximating the distribution function of fast-alpha particles with an “equivalent” Maxwellian is inaccurate to describe absorption of radio-frequency waves in the ion-cyclotron range of frequencies.
Electron-photon shower distribution function tables for lead, copper and air absorbers
Messel, H
2013-01-01
Electron-Photon Shower Distribution Function: Tables for Lead, Copper and Air Absorbers presents numerical results of the electron-photon shower distribution function for lead, copper, and air absorbers. Electron or photon interactions, including Compton scattering, elastic Coulomb scattering, and the photo-electric effect, are taken into account in the calculations. This book consists of four chapters and begins with a review of both theoretical and experimental work aimed at deducing the characteristics of the cascade produced from the propagation of high energy electrons and photons through
On exactness and unbiasedness of confidence bands for a continuous distribution function
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
We define a class of confidence bands for distribution functions,named simple confidence bands.The class of bands includes the common step bands and continuous bands,some of which may perform better than the smoothed bands not belonging to the class,e.g.,the kernel smoothed bands.It is shown that under some mild assumptions,the simple bands with exact coverage for continuous distribution functions are all step bands.The unbiasedness problem of the step bands is also investigated.It is proved that most of two-sided step bands are biased and one-sided step bands are unbiased.
Comment on "Wigner phase-space distribution function for the hydrogen atom"
DEFF Research Database (Denmark)
Dahl, Jens Peder; Springborg, Michael
1999-01-01
We object to the proposal that the mapping of the three-dimensional hydrogen atom into a four-dimensional harmonic oscillator can be readily used to determine the Wigner phase-space distribution function for the hydrogen atom. [S1050-2947(99)07005-5].......We object to the proposal that the mapping of the three-dimensional hydrogen atom into a four-dimensional harmonic oscillator can be readily used to determine the Wigner phase-space distribution function for the hydrogen atom. [S1050-2947(99)07005-5]....
Diffusion-relaxation distribution functions of sedimentary rocks in different saturation states.
Hürlimann, M D; Flaum, M; Venkataramanan, L; Flaum, C; Freedman, R; Hirasaki, G J
2003-01-01
We present diffusion-relaxation distribution functions measured on four rock cores that were prepared in a succession of different saturation states of brine and crude oil. The measurements were performed in a static gradient field at a Larmor frequency of 1.76 MHz. The diffusion-relaxation distribution functions clearly separate the contributions from the two fluid phases. The results can be used to identify the wetting and non-wetting phase, to infer fluid properties of the phases, and to obtain additional information on the geometrical arrangement of the phases. We also observe effects due to restricted diffusion and susceptibility induced internal gradients.
Construction Learning as a Function of Frequency, Frequency Distribution, and Function
Ellis, Nick C.; Ferreira-Junior, Fernando
2009-01-01
This article considers effects of construction frequency, form, function, and prototypicality on second language acquisition (SLA). It investigates these relationships by focusing on naturalistic SLA in the European Science Foundation corpus (Perdue, 1993) of the English verb-argument constructions (VACs): verb locative (VL), verb object locative…
Institute of Scientific and Technical Information of China (English)
HUANG De-jin; DING Hao-jiang; CHEN Wei-qiu
2007-01-01
The bending problem of a functionally graded anisotropic cantilever beam subjected to a linearly distributed load is investigated. The analysis is based on the exact elasticity equations for the plane stress problem. The stress function is introduced and assumed in the form of a polynomial of the longitudinal coordinate. The expressions for stress components are then educed from the stress function by simple differentiation.The stress function is determined from the compatibility equation as well as the boundary conditions by a skilful deduction. The analytical solution is compared with FEM calculation, indicating a good agreement.
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
The bending problem of a functionally graded anisotropic cantilever beam subjected to thermal and uniformly distributed load is investigated, with material parameters being arbitrary functions of the thickness coordinate. The heat conduction problem is treated as a 1D problem through the thickness. Based on the elementary formulations for plane stress problem, the stress function is assumed to be in the form of polynomial of the longitudinal coordinate variable, from which the stresses can be derived.The stress function is then determined completely with the compatibility equation and boundary conditions. A practical example is presented to show the application of the method.
An empirical formula for the distribution function of a thin exponential disc
Sharma, Sanjib
2013-01-01
An empirical formula for a Shu distribution function that reproduces a thin disc with exponential surface density to good accuracy is presented. The formula has two free parameters that specify the functional form of the velocity dispersion. Conventionally, this requires the use of an iterative algorithm to produce the correct solution, which is computationally taxing for applications like Markov Chain Monte Carlo (MCMC) model fitting. The formula has been shown to work for flat, rising and falling rotation curves. Application of this methodology to one of the Dehnen distribution functions is also shown. Finally, an extension of this formula to reproduce velocity dispersion profiles that are an exponential function of radius is also presented. Our empirical formula should greatly aid the efficient comparison of disc models with large stellar surveys or N-body simulations.
Stability of a Logarithmic Functional Equation in Distributions on a Restricted Domain
Directory of Open Access Journals (Sweden)
Jaeyoung Chung
2013-01-01
Full Text Available Let be the set of real numbers, , , and . As classical and versions of the Hyers-Ulam stability of the logarithmic type functional equation in a restricted domain, we consider the following inequalities: , and in the sectors . As consequences of the results, we obtain asymptotic behaviors of the previous inequalities. We also consider its distributional version , where , , , , , and the inequality means that for all test functions .
Distribution of Cerebral Microbleeds Determines Their Association with Impaired Kidney Function
Song, Tae-Jin; Kim, Jinkwon; Lee, Hye Sun; Nam, Chung Mo; Nam, Hyo Suk; Kim, Young Dae; Heo, Ji Hoe
2014-01-01
Background and Purpose Cerebral microbleeds (CMBs) are associated with various pathologies of the cerebral small vessels according to their distribution (i.e., cerebral amyloid angiopathy or hypertensive angiopathy). We investigated the association between CMB location and kidney function in acute ischemic stroke patients. Methods We enrolled 1669 consecutive patients with acute ischemic stroke who underwent gradient-recalled echo brain magnetic resonance imaging. Kidney function was determin...
Effect of spectral index distribution on estimating the AGN radio luminosity function
Yuan, Zunli; Zhou, Ming; Mao, Jirong
2016-01-01
In this paper, we scrutinize the effect of spectral index distribution on estimating the AGN (active galactic nucleus) radio luminosity function (RLF) by a Monte Carlo method. We find that the traditional bivariate RLF estimators can cause bias in varying degree. The bias is especially pronounced for the flat-spectrum radio sources whose spectral index distribution is more scattered. We believe that the bias is caused because the $K$-corrections complicate the truncation boundary on the $L-z$ plane of the sample, but the traditional bivariate RLF estimators have difficulty in dealing with this boundary condition properly. We suggest that the spectral index distribution should be incorporated into the RLF analysis process to obtain a robust estimation. This drives the need for a trivariate function of the form $\\Phi(\\alpha,z,L)$ which we show provides an accurate basis for measuring the RLF.
Effect of Spectral Index Distribution on Estimating the AGN Radio Luminosity Function
Yuan, Zunli; Wang, Jiancheng; Zhou, Ming; Mao, Jirong
2016-10-01
In this paper, we scrutinize the effect of spectral index distribution on estimating the active galactic nucleus radio luminosity function (RLF) by a Monte Carlo method. We find that the traditional bivariate RLF estimators can cause bias in varying degrees. The bias is especially pronounced for the flat-spectrum radio sources whose spectral index distribution is more scattered. We believe that the bias is caused because the K-corrections complicate the truncation boundary on the L-z plane of the sample, but the traditional bivariate RLF estimators have difficulty dealing with this boundary condition properly. We suggest that the spectral index distribution should be incorporated into the RLF analysis process to obtain a robust estimation. This drives the need for a trivariate function of the form Φ(α, z, L), which we show provides an accurate basis for measuring the RLF.
Zhang, Baoyong; Lam, James; Xu, Shengyuan
2015-07-01
This paper revisits the problem of asymptotic stability analysis for neural networks with distributed delays. The distributed delays are assumed to be constant and prescribed. Since a positive-definite quadratic functional does not necessarily require all the involved symmetric matrices to be positive definite, it is important for constructing relaxed Lyapunov-Krasovskii functionals, which generally lead to less conservative stability criteria. Based on this fact and using two kinds of integral inequalities, a new delay-dependent condition is obtained, which ensures that the distributed delay neural network under consideration is globally asymptotically stable. This stability criterion is then improved by applying the delay partitioning technique. Two numerical examples are provided to demonstrate the advantage of the presented stability criteria.
Local Field Distribution Function and High Order Field Moments for metal-dielectric composites.
Genov, Dentcho A.; Sarychev, Andrey K.; Shalaev, Vladimir M.
2001-11-01
In a span of two decades the physics of nonlinear optics saw vast improvement in our understanding of optical properties for various inhomogeneous mediums. One such medium is the metal-dielectric composite, where the metal inclusions have a surface coverage fraction of p, while the rest (1-p) is assumed to represent the dielectric host. The computations carried out by using different theoretical models and the experimental data show existence of giant local electric and magnetic field fluctuations. In this presentation we will introduce a new developed 2D model that determines exactly the Local Field Distribution Function (LFDF) and all other relevant parameters of the film. The LFDF for small filling factors will be shown to transform from lognormal distribution into a single-dipole distribution function. We also will confirm the predictions of the scaling theory for the high field moments, which have a power law dependence on the loss factor.
Distributional asymptotic expansions of spectral functions and of the associated Green kernels
Directory of Open Access Journals (Sweden)
R. Estrada
1999-03-01
Full Text Available Asymptotic expansions of Green functions and spectral densities associated with partial differential operators are widely applied in quantum field theory and elsewhere. The mathematical properties of these expansions can be clarified and more precisely determined by means of tools from distribution theory and summability theory. (These are the same, insofar as recently the classic Cesaro--Riesz theory of summability of series and integrals has been given a distributional interpretation. When applied to the spectral analysis of Green functions (which are then to be expanded as series in a parameter, usually the time,these methods show: (1 The ``local'' or ``global'' dependence of the expansion coefficients on the background geometry, etc., is determined by the regularity of the asymptotic expansion of the integrand at the origin (in ``frequency space''; this marks the difference between a heat kernel and a Wightman two-point function, for instance. (2 The behavior of the integrand at infinity determines whether the expansion of the Green function is genuinely asymptotic in the literal, pointwise sense, or is merely valid in a distributional (Cesaro-averaged sense; this is the difference between the heat kernel and the Schrodinger kernel. (3 The high-frequency expansion of the spectral density itself is local in a distributional sense (but not pointwise. These observations make rigorous sense out of calculations in the physics literature that are sometimes dismissed as merely formal.
Energy Technology Data Exchange (ETDEWEB)
Grechin, S G; Nikolaev, P P; Sharandin, E A [N.E. Bauman Moscow State Technical University, Moscow (Russian Federation)
2014-10-31
The functional possibilities of diode-side-pumped laser heads of solid-state lasers for forming inverse population distributions of different types are analysed. The invariants determining the relationship between the laser head parameters upon scaling are found. The results of comparative experimental studies are presented. (lasers)
Directory of Open Access Journals (Sweden)
V. Rusan
2012-01-01
Full Text Available The paper considers calculation methods for reliability of agricultural distribution power networks while using Boolean algebra functions and analytical method. Reliability of 10 kV overhead line circuits with automatic sectionalization points and automatic standby activation has been investigated in the paper.
Velocity-space tomography of the fast-ion distribution function
DEFF Research Database (Denmark)
Jacobsen, Asger Schou; Salewski, Mirko; Geiger, Benedikt;
2013-01-01
Fast ions play an important role in heating the plasma in a magnetic confinement fusion device. Fast-ion Dα(FIDA) spectroscopy diagnoses fast ions in small measurement volumes. Spectra measured by a FIDA diagnostic can be related to the 2D fast-ion velocity distribution function. A single FIDA vi...
A.C.D. Donkers (Bas); T. Lourenco (Tania); B.G.C. Dellaert (Benedict); D.G. Goldstein (Daniel G.)
2013-01-01
textabstract In this paper we propose the use of preferred outcome distributions as a new method to elicit individuals' value and probability weighting functions in decisions under risk. Extant approaches for the elicitation of these two key ingredients of individuals' risk attitude typically rely
On the calculation of x-ray scattering signals from pairwise radial distribution functions
DEFF Research Database (Denmark)
Dohn, Asmus Ougaard; Biasin, Elisa; Haldrup, Kristoffer;
2015-01-01
We derive a formulation for evaluating (time-resolved) x-ray scattering signals of solvated chemical systems, based on pairwise radial distribution functions, with the aim of this formulation to accompany molecular dynamics simulations. The derivation is described in detail to eliminate any possi...
HI column density distribution function at z=0 : Connection to damped Ly alpha statistics
Zwaan, Martin; Verheijen, MAW; Briggs, FH
We present a measurement of the HI column density distribution function f(N-HI) at the present epoch for column densities > 10(20) cm(-2). These high column densities compare to those measured in damped Ly alpha lines seen in absorption against background quasars. Although observationally rare, it
Drought tolerance of tropical tree species : functional traits, trade-offs and species distribution
Markesteijn, L.
2010-01-01
KEY-WORDS: Bolivia, drought tolerance, shade tolerance, functional traits, trade-offs, ecophysiology, species distribution Tropical forests occur under rainfall regimes that vary greatly in the rainfall pattern and frequency and intensity of drought. Consequently water availability is one of the
Directory of Open Access Journals (Sweden)
George C. McBane
2006-05-01
Full Text Available A set of FORTRAN subprograms is presented to compute density and cumulative distribution functions and critical values for the range ratio statistics of Dixon (1951, The Annals of Mathematical Statistics These statistics are useful for detection of outliers in small samples.
Energy Technology Data Exchange (ETDEWEB)
K.G. Mon
1998-05-13
The purpose of this calculation is to process the cumulative distribution functions (CDFs) characterizing the relative humidity (RH) thresholds for the onset of carbon steel corrosion provided by expert elicitation and minimize the set of values to 200 points for use in WAPDEG.
Methods to determine fast-ion distribution functions from multi-diagnostic measurements
DEFF Research Database (Denmark)
Jacobsen, Asger Schou; Salewski, Mirko
Understanding the behaviour of fast ions in a fusion plasma is very important, since the fusion-born alpha particles are expected to be the main source of heating in a fusion power plant. Preferably, the entire fast-ion velocity-space distribution function would be measured. However, no fast...
HI column density distribution function at z=0 : Connection to damped Ly alpha statistics
Zwaan, Martin; Verheijen, MAW; Briggs, FH
1999-01-01
We present a measurement of the HI column density distribution function f(N-HI) at the present epoch for column densities > 10(20) cm(-2). These high column densities compare to those measured in damped Ly alpha lines seen in absorption against background quasars. Although observationally rare, it a
DEFF Research Database (Denmark)
Boetker, Johan P.; Koradia, Vishal; Rades, Thomas;
2012-01-01
was subjected to quench cooling thereby creating an amorphous form of the drug from both starting materials. The milled and quench cooled samples were, together with the crystalline starting materials, analyzed with X-ray powder diffraction (XRPD), Raman spectroscopy and atomic pair-wise distribution function...
Duijns, S.; Knot, I.E.; Piersma, T.; van Gils, J.A.
2015-01-01
1.Mechanistic insights and predictive understanding of the spatial distributions of foragers are typically derived by fitting either field measurements on intake rates and food abundance, or observations from controlled experiments, to functional response models. It has remained unclear, however, wh
DEFF Research Database (Denmark)
Hansen, Flemming Yssing; Carneiro, K.
1977-01-01
A simple numerical method, which unifies the calculation of structure factors from X-ray or neutron diffraction data with the calculation of reliable pair distribution functions, is described. The objective of the method is to eliminate systematic errors in the normalizations and corrections of t...
Reconstruction of Single-Grain Orientation Distribution Functions for Crystalline Materials
DEFF Research Database (Denmark)
Hansen, Per Christian; Sørensen, Henning Osholm; Sükösd, Zsuzsanna;
A fundamental imaging problem in microstructural analysis of metals is the reconstruction of local crystallographic orientations from X-ray diffraction measurements. This work deals with the computation of the 3D orientation distribution function for individual grains of the material in considera...
Gonoskov, Arkady
2016-01-01
We propose an algorithm for reducing the number of macro-particles in PIC simulations in such a way that an arbitrary number of conservation laws can be preserved exactly and all the distribution functions are not modified in any other way than due to the statistical noise.
Fan, Yuting; Li, Jianqiang; Xu, Kun; Chen, Hao; Lu, Xun; Dai, Yitang; Yin, Feifei; Ji, Yuefeng; Lin, Jintong
2013-09-09
In this paper, we analyze the performance of IEEE 802.11 distributed coordination function in simulcast radio-over-fiber-based distributed antenna systems (RoF-DASs) where multiple remote antenna units (RAUs) are connected to one wireless local-area network (WLAN) access point (AP) with different-length fiber links. We also present an analytical model to evaluate the throughput of the systems in the presence of both the inter-RAU hidden-node problem and fiber-length difference effect. In the model, the unequal delay induced by different fiber length is involved both in the backoff stage and in the calculation of Ts and Tc, which are the period of time when the channel is sensed busy due to a successful transmission or a collision. The throughput performances of WLAN-RoF-DAS in both basic access and request to send/clear to send (RTS/CTS) exchange modes are evaluated with the help of the derived model.
Evolving Molecular Cloud Structure and the Column Density Probability Distribution Function
Ward, Rachel L; Sills, Alison
2014-01-01
The structure of molecular clouds can be characterized with the probability distribution function (PDF) of the mass surface density. In particular, the properties of the distribution can reveal the nature of the turbulence and star formation present inside the molecular cloud. In this paper, we explore how these structural characteristics evolve with time and also how they relate to various cloud properties as measured from a sample of synthetic column density maps of molecular clouds. We find that, as a cloud evolves, the peak of its column density PDF will shift to surface densities below the observational threshold for detection, resulting in an underlying lognormal distribution which has been effectively lost at late times. Our results explain why certain observations of actively star-forming, dynamically older clouds, such as the Orion molecular cloud, do not appear to have any evidence of a lognormal distribution in their column density PDFs. We also study the evolution of the slope and deviation point ...
Energy Technology Data Exchange (ETDEWEB)
Gao, Li-Na; Liu, Fu-Hu [Shanxi University, Institute of Theoretical Physics, Shanxi (China); Lacey, Roy A. [Stony Brook University, Departments of Chemistry and Physics, Stony Brook, NY (United States)
2016-05-15
Experimental results of the transverse-momentum distributions of φ mesons and Ω hyperons produced in gold-gold (Au-Au) collisions with different centrality intervals, measured by the STAR Collaboration at different energies (7.7, 11.5, 19.6, 27, and 39 GeV) in the beam energy scan (BES) program at the relativistic heavy-ion collider (RHIC), are approximately described by the single Erlang distribution and the two-component Schwinger mechanism. Moreover, the STAR experimental transverse-momentum distributions of negatively charged particles, produced in Au-Au collisions at RHIC BES energies, are approximately described by the two-component Erlang distribution and the single Tsallis statistics. The excitation functions of free parameters are obtained from the fit to the experimental data. A weak softest point in the string tension in Ω hyperon spectra is observed at 7.7 GeV. (orig.)
Power-law distribution functions derived from maximum entropy and a symmetry relationship
Peterson, G J
2011-01-01
Power-law distributions are common, particularly in social physics. Here, we explore whether power-laws might arise as a consequence of a general variational principle for stochastic processes. We describe communities of 'social particles', where the cost of adding a particle to the community is shared equally between the particle joining the cluster and the particles that are already members of the cluster. Power-law probability distributions of community sizes arise as a natural consequence of the maximization of entropy, subject to this 'equal cost sharing' rule. We also explore a generalization in which there is unequal sharing of the costs of joining a community. Distributions change smoothly from exponential to power-law as a function of a sharing-inequality quantity. This work gives an interpretation of power-law distributions in terms of shared costs.
Directory of Open Access Journals (Sweden)
J. C. Ferrari
Full Text Available Abstract This work evaluates the usage of the multimodal lognormal function to describe Particle Size Distributions (PSD of emulsion and suspension polymerization processes, including continuous reactions with particle re-nucleation leading to complex multimodal PSDs. A global optimization algorithm, namely Particle Swarm Optimization (PSO, was used for parameter estimation of the proposed model, minimizing the objective function defined by the mean squared errors. Statistical evaluation of the results indicated that the multimodal lognormal function could describe distinctive features of different types of PSDs with accuracy and consistency.
Value Distribution and Uniqueness Results of Zero-Order Meromorphic Functions to Their q-Shift
Directory of Open Access Journals (Sweden)
Haiwa Guan
2012-01-01
Full Text Available We investigate value distribution and uniqueness problems of meromorphic functions with their q-shift. We obtain that if f is a transcendental meromorphic (or entire function of zero order, and Q(z is a polynomial, then afn(qz+f(z−Q(z has infinitely many zeros, where q∈ℂ∖{0}, a is nonzero constant, and n≥5 (or n≥3. We also obtain that zero-order meromorphic function share is three distinct values IM with its q-difference polynomial P(f, and if limsup r→∞(N(r,f/T(r,f<1, then f≡P(f.
Multivariable H-Function with Application to Temperature Distribution in a Moving Medium
Directory of Open Access Journals (Sweden)
A. K. Singh
1983-01-01
Full Text Available The Meijer's G-function has been obtained for the first time as a solution of a differential equation governing a heat conduction problem. The problem of temperature distribution in a moving medium between x = - 1 and x = 1 and having variable velocity and variable thermal conductivity is considered. Due to a general character of the G-function, many known and unknown results may be derived as particular cases. The modified multivariable H-function to obtain a particular solution has been employed.
Directory of Open Access Journals (Sweden)
Alejandro Quintela-del-Rio
2012-08-01
Full Text Available The R package kerdiest has been designed for computing kernel estimators of the distribution function and other related functions. Because of its usefulness in real applications, the bandwidth parameter selection problem has been considered, and a cross-validation method and two of plug-in type have been implemented. Moreover, three relevant functions in nature hazards have also been programmed. The package is completed with two interesting data sets, one of geological type (a complete catalogue of the earthquakes occurring in the northwest of the Iberian Peninsula and another containing the maximum peak flow levels of a river in the United States of America.
Directory of Open Access Journals (Sweden)
Lamparter Tilman
2006-03-01
Full Text Available Abstract Background Phytochromes are photoreceptors, discovered in plants, that control a wide variety of developmental processes. They have also been found in bacteria and fungi, but for many species their biological role remains obscure. This work concentrates on the phytochrome system of Agrobacterium tumefaciens, a non-photosynthetic soil bacterium with two phytochromes. To identify proteins that might share common functions with phytochromes, a co-distribution analysis was performed on the basis of protein sequences from 138 bacteria. Results A database of protein sequences from 138 bacteria was generated. Each sequence was BLASTed against the entire database. The homolog distribution of each query protein was then compared with the homolog distribution of every other protein (target protein of the same species, and the target proteins were sorted according to their probability of co-distribution under random conditions. As query proteins, phytochromes from Agrobacterium tumefaciens, Pseudomonas aeruginosa, Deinococcus radiodurans and Synechocystis PCC 6803 were chosen along with several phytochrome-related proteins from A. tumefaciens. The Synechocystis photosynthesis protein D1 was selected as a control. In the D1 analyses, the ratio between photosynthesis-related proteins and those not related to photosynthesis among the top 150 in the co-distribution tables was > 3:1, showing that the method is appropriate for finding partner proteins with common functions. The co-distribution of phytochromes with other histidine kinases was remarkably high, although most co-distributed histidine kinases were not direct BLAST homologs of the query protein. This finding implies that phytochromes and other histidine kinases share common functions as parts of signalling networks. All phytochromes tested, with one exception, also revealed a remarkably high co-distribution with glutamate synthase and methionine synthase. This result implies a general role of
Distribution and genetic diversity of functional microorganisms in different CANON reactors.
Liu, Tao; Li, Dong; Zeng, Huiping; Li, Xiangkun; Liang, Yuhai; Chang, Xiaoyan; Zhang, Jie
2012-11-01
Completely autotrophic nitrogen removal over nitrite (CANON) has been regarded as an efficient and economical process for nitrogen removal from wastewater. The distribution and genetic diversity of the functional microorganisms in five lab-scale CANON reactors have been investigated by using some molecular biology methods. Nitrosomonas-like aerobic ammonium oxidizing bacteria (AerAOB) and Candidatus Brocadia-related anaerobic ammonium oxidizing bacteria (AnAOB) were detected as predominant functional microbes in the five reactors while Nitrobacter-like nitrite oxidizing bacteria (NOB) existed only in the systems operated at ambient temperature. Communities of AerAOB and AnAOB were almost similar among the five reactors while the distribution of the functional microbes was either scattered or densely packed. Meanwhile, this study has demonstrated the feasibility of starting up CANON by inoculating conventional activated sludge in low ammonium content at ambient temperature.
Neural compensation, muscle load distribution and muscle function in control of biped models
Bavarian, B.
Three aspects of the neuromuscular control of muscle actuators in biped movements were studied: neural compensation, muscle load distribution, and muscle function. A block diagram of a neural control circuit model of the control nervous system is presented. Based on this block diagram a circuit comprised of a dynamic compensator, an inverse plant, and pre-programmed reference trajectory generators is proposed for control of a general n-link biped model. This circuit is used to study the postural stability and point-to-point voluntary movement of a two-link planar biped with two pairs of muscle models. The muscle load distribution, relevant to functional electrical stimulation of paraplegic patients for restoration of limited motor function, is considered. A quantitative analysis of the local controllability of a two-link planar biped model incorporating six major muscles of the lower extremities is presented. A model of the muscle for the lower extremities is presented.
Transverse Momentum Dependent Parton Distribution Functions through SIDIS and Drell-Yan at COMPASS
AUTHOR|(CDS)2079419; Ramos, Sérgio; Quintans, Catarina
The spin structure of the nucleon has been studied at the COMPASS experiment at CERN. The Semi-Inclusive Deep Inelastic Scattering (SIDIS) measurements are a powerful tool to access the Parton Distribution Functions (PDFs) and the Transverse Momentum Dependent Parton Distribution Functions (TMD PDFs). The COMPASS polarised target gives the opportunity to measure the azimuthal modulations depending on the spin orientation and the extraction of the transverse spin asymmetries, which are convolutions of TMD PDFs of the nucleon and Fragmentation Functions (FF). The analysis of these data is done in several kinematic bins, which provides a vast input for the theoreticians to extract the TMDs and the FFs and their kinematic dependence. The TMD PDFs are also accessible through the measurement of the Drell-Yan process, in this case the transverse spin asymmetries are convolutions of two TMD PDFs, one corresponding to the annihilating quark from the beam hadron and the other to the annihilating quark from the target h...
Modeling fractal structure of city-size distributions using correlation function
Chen, Yanguang
2011-01-01
Zipf's law is one the most conspicuous empirical facts for cities, however, there is no convincing explanation for the scaling relation between rank and size and its scaling exponent. Based on the idea from general fractals and scaling, this paper proposes a dual competition hypothesis of city develop to explain the value intervals and the special value, 1, of the power exponent. Zipf's law and Pareto's law can be mathematically transformed into one another. Based on the Pareto distribution, a frequency correlation function can be constructed. By scaling analysis and multifractals spectrum, the parameter interval of Pareto exponent is derived as (0.5, 1]; Based on the Zipf distribution, a size correlation function can be built, and it is opposite to the first one. By the second correlation function and multifractals notion, the Pareto exponent interval is derived as [1, 2). Thus the process of urban evolution falls into two effects: one is Pareto effect indicating city number increase (external complexity), a...
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
The authors derive laws of the iterated logarithm for kernel estimator of regression function based on directional data. The results are distribution free in the sense that they are true for all distributions of design variable.
Ko, William L.; Fleischer, Van Tran
2012-01-01
In the formulations of earlier Displacement Transfer Functions for structure shape predictions, the surface strain distributions, along a strain-sensing line, were represented with piecewise linear functions. To improve the shape-prediction accuracies, Improved Displacement Transfer Functions were formulated using piecewise nonlinear strain representations. Through discretization of an embedded beam (depth-wise cross section of a structure along a strain-sensing line) into multiple small domains, piecewise nonlinear functions were used to describe the surface strain distributions along the discretized embedded beam. Such piecewise approach enabled the piecewise integrations of the embedded beam curvature equations to yield slope and deflection equations in recursive forms. The resulting Improved Displacement Transfer Functions, written in summation forms, were expressed in terms of beam geometrical parameters and surface strains along the strain-sensing line. By feeding the surface strains into the Improved Displacement Transfer Functions, structural deflections could be calculated at multiple points for mapping out the overall structural deformed shapes for visual display. The shape-prediction accuracies of the Improved Displacement Transfer Functions were then examined in view of finite-element-calculated deflections using different tapered cantilever tubular beams. It was found that by using the piecewise nonlinear strain representations, the shape-prediction accuracies could be greatly improved, especially for highly-tapered cantilever tubular beams.
Emergence of q-statistical functions in a generalized binomial distribution with strong correlations
Ruiz, G.; Tsallis, C.
2015-05-01
We study a symmetric generalization pk ( N ) ( η , α ) of the binomial distribution recently introduced by Bergeron et al., where η ∈ [0, 1] denotes the win probability and α is a positive parameter. This generalization is based on q-exponential generating functions ( eq gen z ≡ [ 1 + ( 1 - qgen ) z ] 1 / ( 1 - q gen ) ; e1 z = e z ) where qgen = 1 + 1/α. The numerical calculation of the probability distribution function of the number of wins k, related to the number of realizations N, strongly approaches a discrete qdisc-Gaussian distribution, for win-loss equiprobability (i.e., η = 1/2) and all values of α. Asymptotic N → ∞ distribution is in fact a qatt-Gaussian eq att - β z 2 , where qatt = 1 - 2/(α - 2) and β = (2α - 4). The behavior of the scaled quantity k/Nγ is discussed as well. For γ distribution, yielding a power law, although not exactly a qLD-exponential decay. All q-statistical parameters which emerge are univocally defined by (η, α). Finally, we discuss the analytical connection with the Pólya urn problem.
How Bright is the Proton? A Precise Determination of the Photon Parton Distribution Function
Manohar, Aneesh; Nason, Paolo; Salam, Gavin P.; Zanderighi, Giulia
2016-12-01
It has become apparent in recent years that it is important, notably for a range of physics studies at the Large Hadron Collider, to have accurate knowledge on the distribution of photons in the proton. We show how the photon parton distribution function (PDF) can be determined in a model-independent manner, using electron-proton (e p ) scattering data, in effect viewing the e p →e +X process as an electron scattering off the photon field of the proton. To this end, we consider an imaginary, beyond the Standard Model process with a flavor changing photon-lepton vertex. We write its cross section in two ways: one in terms of proton structure functions, the other in terms of a photon distribution. Requiring their equivalence yields the photon distribution as an integral over proton structure functions. As a result of the good precision of e p data, we constrain the photon PDF at the level of 1%-2% over a wide range of momentum fractions.
Electron velocity distribution functions from the solar wind to the corona
Maksimovic, M.; Pierrard, V.; Lemaire, J.; Larson, D.
1999-06-01
Typical electron velocity distribution functions observed at 1 AU from the Sun by the instrument 3DP aboard of WIND are used as boundary conditions to determine the electron velocity distribution function at 4 solar radii in the corona. The velocity distribution functions (VDF) at low altitude are obtained by solving the Fokker-Planck equation, using two different sets of boundary conditions. The first set typically corresponds to a VDF observed in a low speed solar wind flow (i.e., characterized by ``core'' and ``halo'' electrons); the second one corresponds to high speed solar wind (i.e. characterized by ``core,'' ``halo'' and ``strahl'' populations). We use the observed electron VDFs as test particles which are submitted to external forces and Coulomb collisions with a background plasma. Closer to the Sun, the relative density of the core electrons is found to increase compared to the densities of the halo population. Nevertheless, we find that in order to match the observed distributions at 1 AU, suprathermal tails have to be present in the VDF of the test electron at low altitudes in the corona. Note that the present work has been submitted to Journal of Geophysical Research [6]. This is the reason why we present here only an extended summary.
The correlation between lung sound distribution and pulmonary function in COPD patients.
Directory of Open Access Journals (Sweden)
Masamichi Mineshita
Full Text Available BACKGROUND: Regional lung sound intensity in chronic obstructive pulmonary disease (COPD patients is influenced by the severity and distribution of emphysema, obstructed peripheral airways, and altered ribcage and diaphragm configurations and movements due to hyperinflation. Changes in the lung sound distribution accompanied by pulmonary function improvements in COPD patients were observed after bronchodilator inhalation. We investigated the association of lung sound distribution with pulmonary functions, and the effects of emphysematous lesions on this association. These studies were designed to acquire the basic knowledge necessary for the application of lung sound analysis in the physiological evaluation of COPD patients. METHODS: Pulmonary function tests and the percentage of upper- and lower-lung sound intensity (quantitative lung data [QLD] were evaluated in 47 stable male COPD patients (54 - 82 years of age. In 39 patients, computed tomography taken within 6 months of the study was available and analyzed. RESULTS: The ratio of lower QLD to upper QLD showed significant positive correlations with FEV1 %predicted (%FEV1; ρ=0.45, p40%, n=20 and were stronger in less emphysematous patients (n=19, %FEV1; ρ=0.64, p<0.005, %MEF50; ρ=0.71, p<0.001. CONCLUSIONS: In COPD patients, the ratio of lower- to upper-lung sound intensities decreased according to the severity of obstructive changes, although emphysematous lesions considerably affected lung sound distribution.
Measurements of neutral and ion velocity distribution functions in a Hall thruster
Svarnas, Panagiotis; Romadanov, Iavn; Diallo, Ahmed; Raitses, Yevgeny
2015-11-01
Hall thruster is a plasma device for space propulsion. It utilizes a cross-field discharge to generate a partially ionized weakly collisional plasma with magnetized electrons and non-magnetized ions. The ions are accelerated by the electric field to produce the thrust. There is a relatively large number of studies devoted to characterization of accelerated ions, including measurements of ion velocity distribution function using laser-induced fluorescence diagnostic. Interactions of these accelerated ions with neutral atoms in the thruster and the thruster plume is a subject of on-going studies, which require combined monitoring of ion and neutral velocity distributions. Herein, laser-induced fluorescence technique has been employed to study neutral and single-charged ion velocity distribution functions in a 200 W cylindrical Hall thruster operating with xenon propellant. An optical system is installed in the vacuum chamber enabling spatially resolved axial velocity measurements. The fluorescence signals are well separated from the plasma background emission by modulating the laser beam and using lock-in detectors. Measured velocity distribution functions of neutral atoms and ions at different operating parameters of the thruster are reported and analyzed. This work was supported by DOE contract DE-AC02-09CH11466.
DEFF Research Database (Denmark)
Corell, Mikael; Wicher, Grzegorz; Limbach, Christoph;
2010-01-01
. In this study, we investigated the distribution of N-cadherin in the developing postnatal and adult rat peripheral nervous system. N-cadherin was found primarily in ensheathing glia throughout development, concentrated at neuron-glial or glial-glial contacts of the sciatic nerve, dorsal root ganglia (DRG......), and myenteric plexi. In the sciatic nerve, N-cadherin decreases with age and progress of myelination. In adult animals, N-cadherin was found exclusively in nonmyelinating Schwann cells. The distribution of N-cadherin in developing E17 DRG primary cultures is similar to what was observed in vivo. Functional...
Hayden, Michael R; Holtzman, Jon A; Nidever, David L; Bird, Jonathan C; Weinberg, David H; Andrews, Brett H; Prieto, Carlos Allende; Anders, Friedrich; Beers, Timothy C; Bizyaev, Dmitry; Chiappini, Cristina; Cunha, Katia; Frinchaboy, Peter; García-Herńandez, Domingo A; Pérez, Ana E García; Girardi, Léo; Harding, Paul; Hearty, Fred R; Johnson, Jennifer A; Majewski, Steven R; Mészáros, Szabolcs; Minchev, Ivan; O'Connell, Robert; Pan, Kaike; Robin, Annie C; Schiavon, Ricardo P; Schneider, Donald P; Schultheis, Mathias; Shetrone, Matthew; Skrutskie, Michael; Steinmetz, Matthias; Smith, Verne; Zamora, Olga; Zasowski, Gail
2015-01-01
Using a sample of 69,919 red giants from the SDSS-III/APOGEE Data Release 12, we measure the distribution of stars in the [$\\alpha$/Fe] vs. [Fe/H] plane and the metallicity distribution functions (MDF) across an unprecedented volume of the Milky Way disk, with radius $311$ kpc. The peak of the midplane MDF shifts to lower metallicity at larger $R$, reflecting the Galactic metallicity gradient. Most strikingly, the shape of the midplane MDF changes systematically with radius, with a negatively skewed distribution at $31$ kpc or [$\\alpha$/Fe]$>0.18$, the MDF shows little dependence on $R$. The positive skewness of the outer disk MDF may be a signature of radial migration; we show that blurring of stellar populations by orbital eccentricities is not enough to explain the reversal of MDF shape but a simple model of radial migration can do so.
Chakraborty, P.; Kapusta, J. I.
2017-01-01
In simulations of high energy heavy ion collisions that employ viscous hydrodynamics, single particle distributions are distorted from their thermal equilibrium form due to gradients in the flow velocity. These are closely related to the formulas for the shear and bulk viscosities in the quasiparticle approximation. Distorted single particle distributions are now commonly used to calculate the emission of photons and dilepton pairs, and in the late stage to calculate the conversion of a continuous fluid to individual particles. We show how distortions of the single particle distribution functions due to both shear and bulk viscous effects can be done rigorously in the quasiparticle approximation and illustrate it with the linear σ model at finite temperature.
On the calculation of x-ray scattering signals from pairwise radial distribution functions
DEFF Research Database (Denmark)
Dohn, Asmus Ougaard; Biasin, Elisa; Haldrup, Kristoffer;
2015-01-01
We derive a formulation for evaluating (time-resolved) x-ray scattering signals of solvated chemical systems, based on pairwise radial distribution functions, with the aim of this formulation to accompany molecular dynamics simulations. The derivation is described in detail to eliminate any possi...... possible ambiguities, and the result includes a modification to the atom-type formulation which to our knowledge is previously unaccounted for. The formulation is numerically implemented and validated.......We derive a formulation for evaluating (time-resolved) x-ray scattering signals of solvated chemical systems, based on pairwise radial distribution functions, with the aim of this formulation to accompany molecular dynamics simulations. The derivation is described in detail to eliminate any...
The uncertainty of parton distribution functions due to physical observables in a global analysis
Aleedaneshvar, Alireza; Rostami, Saeedeh
2016-01-01
The recent measurement of the differential $ \\gamma+c $-jet cross section, performed at the Tevatron collider in Run II by the D0 collaboration, is studied in a next-to-leading order (NLO) global QCD analysis to assess its impact on the proton parton distribution functions (PDFs). We show that these data lead to a significant change on the gluon and charm quark distributions. We demonstrate also that there is an inconsistency between the new high precision HERA I+II combined data and Tevatron measurement. Moreover, in this study we investigate the impact of older EMC measurements of charm structure function $F_{c}^{2}$ on the PDFs and compare the results with those gaining from the analysis of Tevatron data. We show that both of them have a same impact on PDFs, and thus can be recognized as same evidences for inefficiency of perturbative QCD in dealing with the charm production in some kinematic regions.
Anselmino, M; H., J O Gonzalez; Melis, S; Prokudin, A
2013-01-01
The unpolarised transverse momentum dependent distribution and fragmentation functions are extracted from HERMES and COMPASS experimental measurements of SIDIS multiplicities for charged hadron production. The data are grouped into independent bins of the kinematical variables, in which the TMD factorisation is expected to hold. A simple factorised functional form of the TMDs is adopted, with a Gaussian dependence on the intrinsic transverse momentum, which turns out to be quite adequate in shape. HERMES data do not need any normalisation correction, while fits of the COMPASS data much improve with a $y$-dependent overall normalisation factor. A comparison of the extracted TMDs with previous EMC and JLab data confirms the adequacy of the simple Gaussian distributions. The possible role of the TMD evolution is briefly considered.
Kinetic corrections from analytic non-Maxwellian distribution functions in magnetized plasmas
Izacard, Olivier
2016-01-01
In magnetized plasma physics, almost all developed analytic theories assume a Maxwellian distribution function (MDF) and in some cases small deviations are described using the perturbation theory. The deviations with respect to the Maxwellian equilibrium, called kinetic effects, are required to be taken into account specially for fusion reactor plasmas. Generally, because the perturbation theory is not consistent with observed steady-state non-Maxwellians, these kinetic effects are numerically evaluated by very CPU-expensive codes, avoiding the analytic complexity of velocity phase space integrals. We develop here a new method based on analytic non-Maxwellian distribution functions constructed from non-orthogonal basis sets in order to (i) use as few parameters as possible, (ii) increase the efficiency to model numerical and experimental non-Maxwellians, (iii) help to understand unsolved problems such as diagnostics discrepancies from the physical interpretation of the parameters, and (iv) obtain analytic cor...
Directory of Open Access Journals (Sweden)
2009-06-01
Full Text Available Thermoplastics having various short and long-chain branches, characterized by the melt index measured at the processing temperature – according to their average molecular mass – can be processed using universal principles, independently of their chemical composition. The average molecular mass is the result of a molecular mass distribution, being the fingerprint of the chemical synthetic technology. The actual shape of the shear viscosity function aiming at the quantitative characterization of viscous flow, containing material-dependent parameters, depends on the ratio of high and low molecular mass fractions, the width of the molecular mass distribution function and on the number of short and long chain branches. This publication deals with the critical analysis of the mathematical methods of transforming these two curves of basic importance into each other.
Energy Technology Data Exchange (ETDEWEB)
Mu, Xiaoke, E-mail: muxiaoke@gmail.com [Institute of Nanotechnology (INT), Karlsruhe Institute of Technology (KIT), 76344 Eggenstein-Leopoldshafen (Germany); Helmholtz-Institute Ulm for Electrochemical Energy Storage (HIU), Karlsruhe Institute of Technology (KIT), 89081 Ulm (Germany); Wang, Di [Institute of Nanotechnology (INT), Karlsruhe Institute of Technology (KIT), 76344 Eggenstein-Leopoldshafen (Germany); Karlsruhe Nano Micro Facility (KNMF), Karlsruhe Institute of Technology (KIT), 76344 Eggenstein-Leopoldshafen (Germany); Feng, Tao [Herbert Gleiter Institute of Nanoscience, Nanjing University of Science and Technology (NJUST), 210094 Nanjing (China); Kübel, Christian [Institute of Nanotechnology (INT), Karlsruhe Institute of Technology (KIT), 76344 Eggenstein-Leopoldshafen (Germany); Helmholtz-Institute Ulm for Electrochemical Energy Storage (HIU), Karlsruhe Institute of Technology (KIT), 89081 Ulm (Germany); Karlsruhe Nano Micro Facility (KNMF), Karlsruhe Institute of Technology (KIT), 76344 Eggenstein-Leopoldshafen (Germany)
2016-09-15
Characterizing heterogeneous nanostructured amorphous materials is a challenging topic, because of difficulty to solve disordered atomic arrangement in nanometer scale. We developed a new transmission electron microscopy (TEM) method to enable phase analysis and mapping of heterogeneous amorphous structures. That is to combine scanning TEM (STEM) diffraction mapping, radial distribution function (RDF) analysis, and hyperspectral analysis. This method was applied to an amorphous zirconium oxide and zirconium iron multilayer system, and showed extreme sensitivity to small atomic packing variations. This approach helps to understand local structure variations in glassy composite materials and provides new insights to correlate structure and properties of glasses. - Highlights: • A method for phase mapping of nanostructured amorphous materials was developed. • The phase mapping is purely based on structural information. • The method combines STEM diffraction with radial distribution function analysis. • The method was applied on an amorphous multilayer for demonstrating its sensitivity.
Parton distribution functions at LO, NLO and NNLO with correlated uncertainties between orders
:,; Britzger, D; Camarda, S; Cooper-Sarkar, A M; Diaconu, C; Feltesse, J; Gizhko, A; Glazov, A; Kolesnikov, V; Lohwasser, K; Luszczak, A; Myronenko, V; Pirumov, H; Placakyte, R; Rabbertz, K; Radescu, V; Sapronov, A; Schoenig, A; Shushkevich, S; Slominski, W; Starovoitov, P; Sutton, M; Tomaszewska, J; Turkot, O; Watt, G; Wichmann, K; Lisovyi, M
2014-01-01
Sets of parton distribution functions (PDFs) of the proton are reported for the leading (LO), next-to-leading (NLO) and next-to-next-to leading order (NNLO) QCD calculations. The parton distribution functions are determined with the HERAFitter program using the data from the HERA experiments and preserving correlations between uncertainties for the LO, NLO and NNLO PDF sets. The sets are used to study cross-section ratios and their uncertainties when calculated at different orders in QCD. A reduction of the overall theoretical uncertainty is observed if correlations between the PDF sets are taken into account for the ratio of $WW$ di-boson to $Z$ boson production cross sections at the LHC.
CDFTBL: A statistical program for generating cumulative distribution functions from data
Energy Technology Data Exchange (ETDEWEB)
Eslinger, P.W. (Pacific Northwest Lab., Richland, WA (United States))
1991-06-01
This document describes the theory underlying the CDFTBL code and gives details for using the code. The CDFTBL code provides an automated tool for generating a statistical cumulative distribution function that describes a set of field data. The cumulative distribution function is written in the form of a table of probabilities, which can be used in a Monte Carlo computer code. A a specific application, CDFTBL can be used to analyze field data collected for parameters required by the PORMC computer code. Section 2.0 discusses the mathematical basis of the code. Section 3.0 discusses the code structure. Section 4.0 describes the free-format input command language, while Section 5.0 describes in detail the commands to run the program. Section 6.0 provides example program runs, and Section 7.0 provides references. The Appendix provides a program source listing. 11 refs., 2 figs., 19 tabs.
Contractive Interference Functions and Rates of Convergence of Distributed Power Control Laws
Johansson, Hamid Reza Feyzmahdavian 'and' Mikael
2012-01-01
The standard interference functions introduced by Yates have been very influential on the analysis and design of distributed power control laws. While powerful and versatile, the framework has some drawbacks: the existence of fixed-points has to be established separately, and no guarantees are given on the rate of convergence of the iterates. This paper introduces contractive interference functions, a slight reformulation of the standard interference functions that guarantees the existence and uniqueness of fixed-points along with geometric convergence. We show that many power control laws from the literature are contractive and derive, sometimes for the first time, analytical convergence rate estimates for these algorithms. We also prove that contractive interference functions converge when executed totally asynchronously and, under the assumption that the communication delay is bounded, derive an explicit bound on the convergence time penalty due to increased delay. Finally, we demonstrate that although all...
Burkhart, Blakesley; Murray, Claire; Stanimirovic, Snezana
2015-01-01
The shape of the probability distribution function (PDF) of molecular clouds is an important ingredient for modern theories of star formation and turbulence. Recently, several studies have pointed out observational difficulties with constraining the low column density (i.e. Av <1) PDF using dust tracers. In order to constrain the shape and properties of the low column density probability distribution function, we investigate the PDF of multiphase atomic gas in the Perseus molecular cloud using opacity-corrected GALFA-HI data and compare the PDF shape and properties to the total gas PDF and the N(H2) PDF. We find that the shape of the PDF in the atomic medium of Perseus is well described by a lognormal distribution, and not by a power-law or bimodal distribution. The peak of the atomic gas PDF in and around Perseus lies at the HI-H2 transition column density for this cloud, past which the N(H2) PDF takes on a powerlaw form. We find that the PDF of the atomic gas is narrow and at column densities larger than...
Tovar-Pescador, J.; Pozo-Vazquez, D.; Batlles, J.; López, G.; Muñoz-Vicente, D.
2004-10-01
Solar irradiance is a key factor in the physiological processes of living beings. To obtain simple correlations for the estimation of the performance of biological systems, which transform the solar energy by photosynthesis, and to generate synthetic data, it is necessary to know the frequency distributions of photosynthetically active radiation (PAR). In this work we carried out an analysis of the properties of hourly values of PAR data, using 9 years of data collected in southern Spain. In particularly, its dependence on the optical mass, for all type of skies including cloudy skies, is studied. Results shows that, for a given value of the optical mass, the PAR density distributions are not symmetrical and have a certain degree of bimodality. The increment in the optical mass value has two effects on the PAR distributions, the first one is a shift toward lower values of the maximum and the second one is a decrease in the range of PAR values. Finally, a model of the frequency distribution of PAR values, based on a new kind of functions related to the Boltzmann’s statistic, is proposed. The parameters of these functions depend just on the optical mass. Results show a very good agreement between the data and the model proposed.
Tovar-Pescador, J.; Pozo-Vázquez, D.; Batlles, J.; López, G.; Rubio, M. A.
2003-04-01
To obtain simple correlations for the estimation of the performance of biological systems, which transform the solar energy by photosynthesis, and to generate synthetic data, it is necessary to know the frequency distributions of photosynthetically active radiation (PAR). In this work we carried out an analysis of the properties of hourly values of PAR data collected in southern Spain. Its dependence on the optical mass for all type of skies, including cloudy skies, is analyzed. Results show that, for a given value of the optical mass, the PAR density distributions are not symmetrical and have certain degree of bimodality. The increment in the optical mass value has two effects on the PAR distributions, the first one is a shift toward lower values of the maximum and the second one is a decrease in the range of PAR values. A model of the frequency distribution of PAR values, based on a new kind of functions related to the Boltzmann´s statistic, is proposed. The parameters of these functions depend just on the optical mass. Results show a very good agreement between the data and the model proposed
Indian Academy of Sciences (India)
Hasan Çallioğlu
2011-02-01
An analytical thermoelasticity solution for a disc made of functionally graded materials (FGMs) is presented. Infinitesimal deformation theory of elasticity and power law distribution for functional gradation are used in the solution procedure. Some relative results for the stress and displacement components along the radius are presented due to internal pressure, external pressure, centrifugal force and steady state temperature. From the results, it is found that the grading indexes play an important role in determining the thermomechanical responses of FG disc and in optimal design of these structures.
Distribution and Other Properties of Zeros of Mittag-Leffler Functions
Hanneken, John W.; Narahari Achar, B. N.; Puzio, Raymond
2005-03-01
The zeros of the Mittag-Leffler function play a significant role in the solutions of dynamic problems in fractional calculus. For example see the book Fractional Differential Equations by Podlubny, or for a specific application see the fractional oscillator by Achar et. al. Physica A297 (2001) 361-367; A309 (2002) 275-288; A339 (2204) 311-319. Very little, however, is known about these zeros. A summary of the available information about the zeros of Mittag-Leffler functions will be given and new results pertaining to their distribution will be presented.
Institute of Scientific and Technical Information of China (English)
Liang Jianwen; You Hongbing
2005-01-01
Based on one type of practical Biot's equation and the dynamic-stiffness matrices ofa poroelastic soil layer and half-space, Green's functions were derived for uniformly distributed loads acting on an inclined line in a poroelastic layered site. This analysis overcomes significant problems in wave scattering due to local soil conditions and dynamic soil-structure interaction. The Green's functions can be reduced to the case of an elastic layered site developed by Wolf in 1985. Parametric studies are then carried out through two example problems.
Directory of Open Access Journals (Sweden)
Ahmad Herison
2014-04-01
Full Text Available Mangrove ecosystem existence is important for environment and other organisms because of its ecological and economical values, so that management and preservation of mangrove ecosystem are needed. The purpose of this research was to determine the existing condition of mangrove, both its distribution and its functional transformation in Indah Kapuk Coastal Area. Avicennia marina becomes important as wave attenuation, a form of abrasion antidote. Transect-Square and Spot-Check methods were used to determine the existing condition of A.marina mangrove forests. Autocad program, coordinate converter, Google Earth, Google Map, and Arc View were applied in process of making mangrove distribution map. In western of research location exactly at Station 1 and Station 2, the density value of mangrove was 450 and 825 tree ha-1, respectively with sparse category because they were contaminated by waste and litter. In eastern of research location namely Station 3, Station 4, and Station 5 the mangroves grow well with density value of 650 (sparse, 1,500 (very dense, and 1,200 tree ha-1 (fair, respectively, eventhough the contamination still happened. The mangrove forests around the stations do not function as wave attenuation because there were many waterfront constructions which have replaced the function of mangrove forests to damp the wave. In short, it can be stated that the mangrove's function has changed in a case of wave attenuation. The function of mangrove forests is not determined by mangrove forest density but it is determined by mangrove's free position.
Energy Technology Data Exchange (ETDEWEB)
Bretagne, J. (Paris-11 Univ., 91 - Orsay (France)); Graham, W.G. (Queen' s Univ., Belfast, Northern Ireland (UK). Dept. of Physics); Hopkins, M.B. (Dublin City Univ. (Ireland). Dept. of Physics)
1991-05-14
Experimental and theoretical electron energy distribution functions (EEDFS) measured in and calculated for the driver of a multicusp ion source operating in hydrogen are compared. The results show that atomic physics based theoretical models can accurately predict the EEDF in such discharges if some appropriate experimentally determined quantities are used as input parameters. The magnitude and shape of the EEDF is found to be particularly sensitive to the effective surface area to volume ratio for electrons. (author).
Energy Technology Data Exchange (ETDEWEB)
Alexandrou, Constantia [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; Cyprus Institute, Nicosia (Cyprus). Computation-based Science and Technology Research Center; Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Cichy, Krzysztof [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Poznan Univ. (Poland). Faculty of Physics; Drach, Vincent [Univ. of Southern Denmark, Odense (Denmark). CP3-Origins and the Danish Inst. for Advanced Study DIAS; Garcia-Ramos, Elena [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik; Hadjiyiannakou, Kyriakos [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; Jansen, Karl; Steffens, Fernanda; Wiese, Christian [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC
2014-11-15
We report on our exploratory study for the evaluation of the parton distribution functions from lattice QCD, based on a new method proposed in Ref.∝arXiv:1305.1539. Using the example of the nucleon, we compare two different methods to compute the matrix elements needed, and investigate the application of gauge link smearing. We also present first results from a large production ensemble and discuss the future challenges related to this method.
Alexandrou, Constantia; Drach, Vincent; Garcia-Ramos, Elena; Hadjiyiannakou, Kyriakos; Jansen, Karl; Steffens, Fernanda; Wiese, Christian
2014-01-01
We report on our exploratory study for the evaluation of the parton distribution functions from lattice QCD, based on a new method proposed in Ref.~arXiv:1305.1539. Using the example of the nucleon, we compare two different methods to compute the matrix elements needed, and investigate the application of gauge link smearing. We also present first results from a large production ensemble and discuss the future challenges related to this method.
Gas-kinetic numerical method for solving mesoscopic velocity distribution function equation
Institute of Scientific and Technical Information of China (English)
Zhihui Li; Hanxin Zhang
2007-01-01
A gas-kinetic numerical method for directly solving the mesoscopic velocity distribution function equation is presented and applied to the study of three-dimensional complex flows and micro-channel flows covering various flow regimes. The unified velocity distribution function equation describing gas transport phenomena from rarefied transition to continuumflow regimes can be presented on the basis of the kinetic Boltzmann-Shakhov model equation. The gas-kinetic finite-difference schemes for the velocity distribution function are constructed by developing a discrete velocity ordinate method of gas kinetic theory and an unsteady time-splitting technique from computational fluid dynamics. Gas-kinetic boundary conditions and numerical modeling can be established by directly manipulating on the mesoscopic velocity distribution function. A new Gauss-type discrete velocity numerical integration method can be developed and adopted to attack complex flows with different Mach numbers. HPF parallel strategy suitable for the gas-kinetic numerical method is investigated and adopted to solve three-dimensional complex problems. High Mach number flows around three-dimensional bodies are computed preliminarily with massive scale parallel. It is noteworthy and of practical importance that the HPF parallel algorithm for solving three-dimensional complex problems can be effectively developed to cover various flow regimes. On the other hand, the gas-kinetic numerical method is extended and used to study micro-channel gas flows including the classical Couette flow, the Poiseuillechannel flow and pressure-driven gas flows in twodimensional short micro-channels. The numerical experience shows that the gas-kinetic algorithm may be a powerful tool in the numerical simulation of microscale gas flows occuring in the Micro-Electro-Mechanical System (MEMS).
Energy Technology Data Exchange (ETDEWEB)
Krasilnikov, M. B., E-mail: mihail.krasilnikov@gmail.com; Kudryavtsev, A. A. [St. Petersburg State University, St. Petersburg 198504 (Russian Federation); Kapustin, K. D. [St. Petersburg University ITMO, St. Petersburg 197101 (Russian Federation)
2014-12-15
It is shown that the local approximation for computing the electron distribution function depends both on the ratio between the energy relaxation length and a characteristic plasma length and on the ratio between heating and ambipolar electric fields. In particular, the local approximation is not valid at the discharge periphery even at high pressure due to the fact that the ambipolar electric field practically always is larger than the heating electric field.
White-light implementation of the Wigner-distribution function with an achromatic processor.
Lancis, J; Sicre, E E; Tajahuerce, E; Andrés, P
1995-12-10
A temporally incoherent optical processor that combines diffractive and refractive components is proposed for performing two different operations simultaneously: an achromatic image along an axis and an achromatic one-dimensional Fourier transformation along the orthogonal axis. These properties are properly employed to achieve the achromatic white-light display of the Wigner-distribution function associated with a one-dimensional real signal, with high redundancy and variable scale.
Directory of Open Access Journals (Sweden)
Azam Zaka
2014-10-01
Full Text Available This paper is concerned with the modifications of maximum likelihood, moments and percentile estimators of the two parameter Power function distribution. Sampling behavior of the estimators is indicated by Monte Carlo simulation. For some combinations of parameter values, some of the modified estimators appear better than the traditional maximum likelihood, moments and percentile estimators with respect to bias, mean square error and total deviation.
Kinetic corrections from analytic non-Maxwellian distribution functions in magnetized plasmas
Izacard, Olivier
2016-01-01
In magnetized plasma physics, almost all developed analytic theories assume a Maxwellian distribution function (MDF) and in some cases small deviations are described using the perturbation theory. The deviations with respect to the Maxwellian equilibrium, called kinetic effects, are required to be taken into account specially for fusion reactor plasmas. Generally, because the perturbation theory is not consistent with observed steady-state non-Maxwellians, these kinetic effects are numericall...
Pham-Van-diep, Gerald C.; Erwin, Daniel A.
1989-01-01
Velocity distribution functions in normal shock waves in argon and helium are calculated using Monte Carlo direct simulation. These are compared with experimental results for argon at M = 7.18 and for helium at M = 1.59 and 20. For both argon and helium, the variable-hard-sphere (VHS) model is used for the elastic scattering cross section, with the velocity dependence derived from a viscosity-temperature power-law relationship in the way normally used by Bird (1976).
2016-04-26
created using probability distribution functions. This new model performs as well or better than other modern models of the solar wind velocity. In... Physics , 120: 7987-8001, doi: 10.1002/2014JA020962. Abstract: The temporal and spatial variations of the thermospheric mass density during a series of...2015), Theoretical study of zonal differences of electron density at midlatitudes with GITM simulation, J. Geophys. Res. Space Physics , 120, 2951
A discrete spherical X-ray transform of orientation distribution functions using bounding cubes
DEFF Research Database (Denmark)
Kazantsev, Ivan G; Schmidt, Søren; Poulsen, Henning Friis
2009-01-01
We investigate a cubed sphere parametrization of orientation space with the aim of constructing a discrete voxelized version of the spherical x-ray transform. For tracing the propagation of a unit great circle through the partition subsets, the frustums of the cubed sphere, a fast procedure is pr...... within rectangular voxel arrays partitioning the bounding cubes. Hence algebraic reconstruction techniques can be used in a comprehensive way for orientation distribution function estimation from diffraction data....
Intestinal gas content and distribution in health and in patients with functional gut symptoms
Bendezú, Álvaro; Barba, Elisabeth; Burri, Emanuel; Cisternas, Daniel; Malagelada Prats, Carolina; Segui, Santi; Accarino Garaventa, Anna María; Quiroga, Sergi; Monclús Lahoya, Eva; Navazo Álvaro, Isabel; Malagelada Benapres, Juan Ramon; Azpiroz Vidaur, Fernando
2015-01-01
Background: The precise relation of intestinal gas to symptoms, particularly abdominal bloating and distension remains incompletely elucidated. Our aim was to define the normal values of intestinal gas volume and distribution and to identify abnormalities in relation to functional-type symptoms. Methods:Abdominal computed tomography scans were evaluated in healthy subjects (n = 37) and in patients in three conditions: basal (when they were feeling well; n = 88), during an episode of abdomi...
Lanfang Sun; Emi Kawano-Yamashita; Takashi Nagata; Hisao Tsukamoto; Yuji Furutani; Mitsumasa Koyanagi; Akihisa Terakita
2014-01-01
Mammals contain 1 melanopsin (Opn4) gene that is expressed in a subset of retinal ganglion cells to serve as a photopigment involved in non-image-forming vision such as photoentrainment of circadian rhythms. In contrast, most nonmammalian vertebrates possess multiple melanopsins that are distributed in various types of retinal cells; however, their functions remain unclear. We previously found that the lamprey has only 1 type of mammalian-like melanopsin gene, which is similar to that observe...
Online platform for simulations of ion energy distribution functions behind a plasma boundary sheath
Wollny, Alexander; Shihab, Mohammed; Brinkmann, Ralf Peter
2012-10-01
Plasma processes, particularly plasma etching and plasma deposition are crucial for a large variety of industrial manufacturing purposes. For these processes the knowledge of the ion energy distribution function plays a key role. Measurements of the ion energy and ion angular distribution functions (IEDF, IADF) are at least challenging and often impossible in industrial processes. An alternative to measurements of the IEDF are simulations. With this contribution we present a self-consistent model available online for everyone. The simulation of ion energy and ion angular distribution functions involves the well known plasma boundary sheath model by Brinkmann [1-4], which is controlled via a web interface (http://sheath.tet.rub.de). After a successful simulation run all results are evaluable within the browser and ready for download for further analysis.[4pt] [1] R.P. Brinkmann, J. Phys. D: Appl. Phys. 44, 042002 (2011)[0pt] [2] R.P. Brinkmann, J. Phys. D: Appl. Phys. 42, 194009 (2009)[0pt] [3] R.P. Brinkmann, J. App. Phys. 102, 093303 (2007)[0pt] [4] M. Kratzer et al., J. Appl. Phys. 90, 2169 (2001)
Statistical Measurement of the Gamma-ray Source-count Distribution as a Function of Energy
Zechlin, Hannes-S; Donato, Fiorenza; Fornengo, Nicolao; Regis, Marco
2016-01-01
Statistical properties of photon count maps have recently been proven as a new tool to study the composition of the gamma-ray sky with high precision. We employ the 1-point probability distribution function of 6 years of Fermi-LAT data to measure the source-count distribution dN/dS and the diffuse components of the high-latitude gamma-ray sky as a function of energy. To that aim, we analyze the gamma-ray emission in five adjacent energy bands between 1 GeV and 171 GeV. It is demonstrated that the source-count distribution as a function of flux is compatible with a broken power law up to energies of 50 GeV. The index below the break is between 1.95 and 2.0. For higher energies, a simple power law fits the data, with an index of 2.2^{+0.7}_{-0.3} in the energy band between 50 GeV and 171 GeV. Upper limits on further possible breaks as well as the angular power of unresolved sources are derived. We find that point source populations probed by this method can explain 83^{+7}_{-13}% (81^{+52}_{-19}%) of the extrag...
On The Estimation of Survival Function and Parameter Exponential Life Time Distribution
Directory of Open Access Journals (Sweden)
Hadeel S. Al-Kutubi
2009-01-01
Full Text Available Problem statement: The study and research of survival or reliability or life time belong to the same area of study but they may belong to a different area of application. In survival analysis one can use several life time distribution, exponential distribution with mean life time θ is one of them. To estimate this parameter and survival function we must be used estimation procedures with less MSE and MPE. Approach: The only statistical theory that combined modeling inherent uncertainty and statistical uncertainty is Bayesian statistics. The theorem of Bayes provided a solution to how learn from data. Bayes theorem was depending on prior and posterior distribution and standard Bayes estimator depends on Jeffery prior information. In this study we annexed Jeffery prior information to get the modify Bayes estimator and then compared it with standard Bayes estimator and maximum likelihood estimator to find the best (less MSE and MPE. Results: when we derived Bayesian and Maximum likelihood of the scale parameter and survival functions. Simulation study was used to compare between estimators and Mean Square Error (MSE and Mean Percentage Error (MPE of estimators are computed. Conclusion: The new proposed estimator of modify Bayes estimator in parameter and survival function was the best estimator (less MSE and MPE when we compared it with standard Bayes and maximum likelihood estimator.
Quasi-parton distribution functions: A study in the diquark spectator model
Directory of Open Access Journals (Sweden)
Leonard Gamberg
2015-04-01
Full Text Available A set of quasi-parton distribution functions (quasi-PDFs have been recently proposed by Ji. Defined as the matrix elements of equal-time spatial correlations, they can be computed on the lattice and should reduce to the standard PDFs when the proton momentum Pz is very large. Since taking the Pz→∞ limit is not feasible in lattice simulations, it is essential to provide guidance for which values of Pz the quasi-PDFs are good approximations of standard PDFs. Within the framework of the spectator diquark model, we evaluate both the up and down quarks' quasi-PDFs and standard PDFs for all leading-twist distributions (unpolarized distribution f1, helicity distribution g1, and transversity distribution h1. We find that, for intermediate parton momentum fractions x, quasi-PDFs are good approximations to standard PDFs (within 20–30% when Pz≳1.5–2 GeV. On the other hand, for large x∼1 much larger Pz>4 GeV is necessary to obtain a satisfactory agreement between the two sets. We further test the Soffer positivity bound, and find that it does not hold in general for quasi-PDFs.
Kinetic corrections from analytic non-Maxwellian distribution functions in magnetized plasmas
Energy Technology Data Exchange (ETDEWEB)
Izacard, Olivier, E-mail: izacard@llnl.gov [Lawrence Livermore National Laboratory, 7000 East Avenue, L-637, Livermore, California 94550 (United States)
2016-08-15
In magnetized plasma physics, almost all developed analytic theories assume a Maxwellian distribution function (MDF) and in some cases small deviations are described using the perturbation theory. The deviations with respect to the Maxwellian equilibrium, called kinetic effects, are required to be taken into account especially for fusion reactor plasmas. Generally, because the perturbation theory is not consistent with observed steady-state non-Maxwellians, these kinetic effects are numerically evaluated by very central processing unit (CPU)-expensive codes, avoiding the analytic complexity of velocity phase space integrals. We develop here a new method based on analytic non-Maxwellian distribution functions constructed from non-orthogonal basis sets in order to (i) use as few parameters as possible, (ii) increase the efficiency to model numerical and experimental non-Maxwellians, (iii) help to understand unsolved problems such as diagnostics discrepancies from the physical interpretation of the parameters, and (iv) obtain analytic corrections due to kinetic effects given by a small number of terms and removing the numerical error of the evaluation of velocity phase space integrals. This work does not attempt to derive new physical effects even if it could be possible to discover one from the better understandings of some unsolved problems, but here we focus on the analytic prediction of kinetic corrections from analytic non-Maxwellians. As applications, examples of analytic kinetic corrections are shown for the secondary electron emission, the Langmuir probe characteristic curve, and the entropy. This is done by using three analytic representations of the distribution function: the Kappa distribution function, the bi-modal or a new interpreted non-Maxwellian distribution function (INMDF). The existence of INMDFs is proved by new understandings of the experimental discrepancy of the measured electron temperature between two diagnostics in JET. As main results, it
Kinetic corrections from analytic non-Maxwellian distribution functions in magnetized plasmas
Izacard, Olivier
2016-08-01
In magnetized plasma physics, almost all developed analytic theories assume a Maxwellian distribution function (MDF) and in some cases small deviations are described using the perturbation theory. The deviations with respect to the Maxwellian equilibrium, called kinetic effects, are required to be taken into account especially for fusion reactor plasmas. Generally, because the perturbation theory is not consistent with observed steady-state non-Maxwellians, these kinetic effects are numerically evaluated by very central processing unit (CPU)-expensive codes, avoiding the analytic complexity of velocity phase space integrals. We develop here a new method based on analytic non-Maxwellian distribution functions constructed from non-orthogonal basis sets in order to (i) use as few parameters as possible, (ii) increase the efficiency to model numerical and experimental non-Maxwellians, (iii) help to understand unsolved problems such as diagnostics discrepancies from the physical interpretation of the parameters, and (iv) obtain analytic corrections due to kinetic effects given by a small number of terms and removing the numerical error of the evaluation of velocity phase space integrals. This work does not attempt to derive new physical effects even if it could be possible to discover one from the better understandings of some unsolved problems, but here we focus on the analytic prediction of kinetic corrections from analytic non-Maxwellians. As applications, examples of analytic kinetic corrections are shown for the secondary electron emission, the Langmuir probe characteristic curve, and the entropy. This is done by using three analytic representations of the distribution function: the Kappa distribution function, the bi-modal or a new interpreted non-Maxwellian distribution function (INMDF). The existence of INMDFs is proved by new understandings of the experimental discrepancy of the measured electron temperature between two diagnostics in JET. As main results, it
Distributed analysis functional testing using GangaRobot in the ATLAS experiment
Legger, Federica; ATLAS Collaboration
2011-12-01
Automated distributed analysis tests are necessary to ensure smooth operations of the ATLAS grid resources. The HammerCloud framework allows for easy definition, submission and monitoring of grid test applications. Both functional and stress test applications can be defined in HammerCloud. Stress tests are large-scale tests meant to verify the behaviour of sites under heavy load. Functional tests are light user applications running at each site with high frequency, to ensure that the site functionalities are available at all times. Success or failure rates of these tests jobs are individually monitored. Test definitions and results are stored in a database and made available to users and site administrators through a web interface. In this work we present the recent developments of the GangaRobot framework. GangaRobot monitors the outcome of functional tests, creates a blacklist of sites failing the tests, and exports the results to the ATLAS Site Status Board (SSB) and to the Service Availability Monitor (SAM), providing on the one hand a fast way to identify systematic or temporary site failures, and on the other hand allowing for an effective distribution of the work load on the available resources.
The Galactic IMF: origin in the combined mass distribution functions of dust grains and gas clouds
Casuso, E
2011-01-01
We present here a theoretical model to account for the stellar IMF as a result of the composite behaviour of the gas and dust distribution functions. Each of these has previously been modelled and the models tested against observations. The model presented here implies a relation between the characteristic size of the dust grains and the characteristic final mass of the stars formed within the clouds containing the grains, folded with the relation between the mass of a gas cloud and the characteristic mass of the stars formed within it. The physical effects of dust grain size are due to equilibrium relations between the efficiency of grains in cooling the clouds, which is a falling function of grain size, and the efficiency of grains in catalyzing the production of molecular hydrogen, which is a rising function of grain size. We show that folding in the effects of grain distribution can yield a reasonable quantitative account of the IMF, while gas cloud mass function alone cannot do so.
Xie, Jiang-Bo; Xu, Gui-Qing; Jenerette, G Darrel; Bai, Yong-fei; Wang, Zhong-Yuan; Li, Yan
2015-07-20
Species competitive abilities and their distributions are closely related to functional traits such as biomass allocation patterns. When we consider how nutrient supply affects competitive abilities, quantifying the apparent and true plasticity in functional traits is important because the allometric relationships among traits are universal in plants. We propose to integrate the notion of allometry and the classical reaction norm into a composite theoretical framework that quantifies the apparent and true plasticity. Combining the framework with a meta-analysis, a series of field surveys and a competition experiment, we aimed to determine the causes of the dune/interdune distribution patterns of two Haloxylon species in the Gurbantonggut Desert. We found that (1) the biomass allocation patterns of both Haloxylon species in responses to environmental conditions were apparent rather than true plasticity and (2) the allometric allocation patterns affected the plants' competition for soil nutrient supply. A key implication of our results is that the apparent plasticity in functional traits of plants determines their response to environmental change. Without identifying the apparent and true plasticity, we would substantially overestimate the magnitude, duration and even the direction of plant responses in functional traits to climate change.
Functional distribution of nicotinic receptors in CA3 region of the hippocampus.
Grybko, Michael; Sharma, Geeta; Vijayaraghavan, Sukumar
2010-01-01
Nicotinic acetylcholine receptor (nAChR) modulation of a number of parameters of synaptic signaling in the brain has been demonstrated. It is likely that effects of nicotine are due to its ability to modulate network excitability as a whole. A pre-requisite to understanding the effects of nicotine on network properties is the elucidation of functional receptors. We have examined the distribution of functional nAChRs in the dentate gyrus granule cells and the CA3 region of the mammalian hippocampus using calcium imaging from acute slices. Our results demonstrate the presence of functional nAChRs containing the alpha7 subunit (alpha7-nAChRs) on mossy fiber boutons, CA3 pyramidal cells, and on astrocytes. In addition, both CA3 interneurons and granule cells show nicotinic signals. Our study suggests that functional nicotinic receptors are widespread in their distribution and that calcium imaging might be an effective technique to examine locations of these receptors in the mammalian brain.
Liu, Feng; Archer, Steven R; Gelwick, Frances; Bai, Edith; Boutton, Thomas W; Wu, Xinyuan Ben
2013-01-01
Woody plant encroachment into grasslands has been globally widespread. The woody species invading grasslands represent a variety of contrasting plant functional groups and growth forms. Are some woody plant functional types (PFTs) better suited to invade grasslands than others? To what extent do local patterns of distribution and abundance of woody PFTs invading grasslands reflect intrinsic topoedaphic properties versus plant-induced changes in soil properties? We addressed these questions in the Southern Great Plains, United States at a subtropical grassland known to have been encroached upon by woody species over the past 50-100 years. A total of 20 woody species (9 tree-statured; 11 shrub-statured) were encountered along a transect extending from an upland into a playa basin. About half of the encroaching woody plants were potential N2-fixers (55% of species), but they contributed only 7% to 16 % of the total basal area. Most species and the PFTs they represent were ubiquitously distributed along the topoedaphic gradient, but with varying abundances. Overstory-understory comparisons suggest that while future species composition of these woody communities is likely to change, PFT composition is not. Canonical correspondence analysis (CCA) ordination and variance partitioning (Partial CCA) indicated that woody species and PFT composition in developing woody communities was primarily influenced by intrinsic landscape location variables (e.g., soil texture) and secondarily by plant-induced changes in soil organic carbon and total nitrogen content. The ubiquitous distribution of species and PFTs suggests that woody plants are generally well-suited to a broad range of grassland topoedaphic settings. However, here we only examined categorical and non-quantitative functional traits. Although intrinsic soil properties exerted more control over the floristics of grassland-to-woodland succession did plant modifications of soil carbon and nitrogen concentrations, the latter
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Feng Liu
Full Text Available Woody plant encroachment into grasslands has been globally widespread. The woody species invading grasslands represent a variety of contrasting plant functional groups and growth forms. Are some woody plant functional types (PFTs better suited to invade grasslands than others? To what extent do local patterns of distribution and abundance of woody PFTs invading grasslands reflect intrinsic topoedaphic properties versus plant-induced changes in soil properties? We addressed these questions in the Southern Great Plains, United States at a subtropical grassland known to have been encroached upon by woody species over the past 50-100 years. A total of 20 woody species (9 tree-statured; 11 shrub-statured were encountered along a transect extending from an upland into a playa basin. About half of the encroaching woody plants were potential N2-fixers (55% of species, but they contributed only 7% to 16 % of the total basal area. Most species and the PFTs they represent were ubiquitously distributed along the topoedaphic gradient, but with varying abundances. Overstory-understory comparisons suggest that while future species composition of these woody communities is likely to change, PFT composition is not. Canonical correspondence analysis (CCA ordination and variance partitioning (Partial CCA indicated that woody species and PFT composition in developing woody communities was primarily influenced by intrinsic landscape location variables (e.g., soil texture and secondarily by plant-induced changes in soil organic carbon and total nitrogen content. The ubiquitous distribution of species and PFTs suggests that woody plants are generally well-suited to a broad range of grassland topoedaphic settings. However, here we only examined categorical and non-quantitative functional traits. Although intrinsic soil properties exerted more control over the floristics of grassland-to-woodland succession did plant modifications of soil carbon and nitrogen
Functional traits predict drought performance and distribution of Mediterranean woody species
Lopez-Iglesias, Bárbara; Villar, Rafael; Poorter, Lourens
2014-04-01
Water availability is one of the key environmental factors that affect plant establishment and distribution. In many regions water availability will decline with climate change, exposing small seedlings to a greater likelihood of drought. In this study, 17 leaves, stem, root, and whole-plant traits of ten woody Mediterranean species were measured under favourable growing conditions and seedling drought survival was evaluated during a simulated dry-down episode. The aims of this study were: i) to assess drought survival of different species, ii) to analyse which functional traits predict drought survival time, and iii) to explain species distribution in the field, based on species drought survival and drought strategies. Drought survival time varied ten-fold across species, from 19 to 192 days. Across species, drought survival was positively related to the rooting depth per leaf area, i.e., the ability to acquire water from deeper soil layers while reducing transpiring leaf area. Drought survival time was negatively related to species ability to grow quickly, as indicated by high relative growth and net assimilation rates. Drought survival also explained species distribution in the field. It was found that species were sorted along a continuum, ranging between two contrasting species functional extremes based on functional traits and drought performance. One extreme consisted of acquisitive fast-growing deciduous species, with thin, soft metabolically active leaves, with high resource use and vulnerability to drought. The opposite extreme consisted of conservative slow-growing evergreen species with sclerophyllous leaves, deep roots, a low transpiring area, and low water use, resulting in high drought survival and drought tolerance. The results show that these drought strategies shape species distribution in this Mediterranean area.
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Lanfang Sun
Full Text Available Mammals contain 1 melanopsin (Opn4 gene that is expressed in a subset of retinal ganglion cells to serve as a photopigment involved in non-image-forming vision such as photoentrainment of circadian rhythms. In contrast, most nonmammalian vertebrates possess multiple melanopsins that are distributed in various types of retinal cells; however, their functions remain unclear. We previously found that the lamprey has only 1 type of mammalian-like melanopsin gene, which is similar to that observed in mammals. Here we investigated the molecular properties and localization of melanopsin in the lamprey and other cyclostome hagfish retinas, which contribute to visual functions including image-forming vision and mainly to non-image-forming vision, respectively. We isolated 1 type of mammalian-like melanopsin cDNA from the eyes of each species. We showed that the recombinant lamprey melanopsin was a blue light-sensitive pigment and that both the lamprey and hagfish melanopsins caused light-dependent increases in calcium ion concentration in cultured cells in a manner that was similar to that observed for mammalian melanopsins. We observed that melanopsin was distributed in several types of retinal cells, including horizontal cells and ganglion cells, in the lamprey retina, despite the existence of only 1 melanopsin gene in the lamprey. In contrast, melanopsin was almost specifically distributed to retinal ganglion cells in the hagfish retina. Furthermore, we found that the melanopsin-expressing horizontal cells connected to the rhodopsin-containing short photoreceptor cells in the lamprey. Taken together, our findings suggest that in cyclostomes, the global distribution of melanopsin in retinal cells might not be related to the melanopsin gene number but to the extent of retinal contribution to visual function.
Nelson, James Byron
2016-01-01
The manuscript presents a Visual Basic[superscript R] for Applications function that operates within Microsoft Office Excel[superscript R] to return the area below the curve for a given F within a specified non-central F distribution. The function will be of use to Excel users without programming experience wherever a non-central F distribution is…
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Dong Hyun Cho
2016-01-01
Full Text Available Using simple formulas for generalized conditional Wiener integrals on a function space which is an analogue of Wiener space, we evaluate two generalized analytic conditional Wiener integrals of a generalized cylinder function which is useful in Feynman integration theories and quantum mechanics. We then establish various integral transforms over continuous paths with change of scales for the generalized analytic conditional Wiener integrals. In these evaluation formulas and integral transforms we use multivariate normal distributions so that the orthonormalization process of projection vectors which are needed to establish the conditional Wiener integrals can be removed in the existing change of scale transforms. Consequently the transforms in the present paper can be expressed in terms of the generalized cylinder function itself.
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Zhenxiang Jiang
2016-01-01
Full Text Available The traditional methods of diagnosing dam service status are always suitable for single measuring point. These methods also reflect the local status of dams without merging multisource data effectively, which is not suitable for diagnosing overall service. This study proposes a new method involving multiple points to diagnose dam service status based on joint distribution function. The function, including monitoring data of multiple points, can be established with t-copula function. Therefore, the possibility, which is an important fusing value in different measuring combinations, can be calculated, and the corresponding diagnosing criterion is established with typical small probability theory. Engineering case study indicates that the fusion diagnosis method can be conducted in real time and the abnormal point can be detected, thereby providing a new early warning method for engineering safety.
Probability distribution functions of turbulence in seepage-affected alluvial channel
Sharma, Anurag; Kumar, Bimlesh
2017-02-01
The present experimental study is carried out on the probability distribution functions (PDFs) of turbulent flow characteristics within near-bed-surface and away-from-bed surfaces for both no seepage and seepage flow. Laboratory experiments were conducted in the plane sand bed for no seepage (NS), 10% seepage (10%S) and 15% seepage (15%) cases. The experimental calculation of the PDFs of turbulent parameters such as Reynolds shear stress, velocity fluctuations, and bursting events is compared with theoretical expression obtained by Gram-Charlier (GC)-based exponential distribution. Experimental observations follow the computed PDF distributions for both no seepage and seepage cases. Jensen-Shannon divergence (JSD) method is used to measure the similarity between theoretical and experimental PDFs. The value of JSD for PDFs of velocity fluctuation lies between 0.0005 to 0.003 while the JSD value for PDFs of Reynolds shear stress varies between 0.001 to 0.006. Even with the application of seepage, the PDF distribution of bursting events, sweeps and ejections are well characterized by the exponential distribution of the GC series, except that a slight deflection of inward and outward interactions is observed which may be due to weaker events. The value of JSD for outward and inward interactions ranges from 0.0013 to 0.032, while the JSD value for sweep and ejection events varies between 0.0001 to 0.0025. The theoretical expression for the PDF of turbulent intensity is developed in the present study, which agrees well with the experimental observations and JSD lies between 0.007 and 0.015. The work presented is potentially applicable to the probability distribution of mobile-bed sediments in seepage-affected alluvial channels typically characterized by the various turbulent parameters. The purpose of PDF estimation from experimental data is that it provides a complete numerical description in the areas of turbulent flow either at a single or finite number of points.
THE STELLAR METALLICITY DISTRIBUTION FUNCTION OF THE GALACTIC HALO FROM SDSS PHOTOMETRY
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An, Deokkeun [Department of Science Education, Ewha Womans University, Seoul 120-750 (Korea, Republic of); Beers, Timothy C. [National Optical Astronomy Observatory, Tucson, AZ 85719 (United States); Johnson, Jennifer A.; Pinsonneault, Marc H. [Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Lee, Young Sun [Department of Physics and Astronomy and JINA (Joint Institute for Nuclear Astrophysics), Michigan State University, E. Lansing, MI 48824 (United States); Bovy, Jo [Institute for Advanced Study, Einstein Drive, Princeton, NJ 08540 (United States); Ivezic, Zeljko [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Carollo, Daniela [Macquarie University Research Centre in Astronomy, Astrophysics and Astrophotonics, Department of Physics and Astronomy, Macquarie University, NSW 2109 (Australia); Newby, Matthew, E-mail: deokkeun@ewha.ac.kr [Department of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute Troy, NY 12180 (United States)
2013-01-20
We explore the stellar metallicity distribution function of the Galactic halo based on SDSS ugriz photometry. A set of stellar isochrones is calibrated using observations of several star clusters and validated by comparisons with medium-resolution spectroscopic values over a wide range of metal abundance. We estimate distances and metallicities for individual main-sequence stars in the multiply scanned SDSS Stripe 82, at heliocentric distances in the range 5-8 kpc and |b| > 35 Degree-Sign , and find that the in situ photometric metallicity distribution has a shape that matches that of the kinematically selected local halo stars from Ryan and Norris. We also examine independent kinematic information from proper-motion measurements for high Galactic latitude stars in our sample. We find that stars with retrograde rotation in the rest frame of the Galaxy are generally more metal poor than those exhibiting prograde rotation, which is consistent with earlier arguments by Carollo et al. that the halo system comprises at least two spatially overlapping components with differing metallicity, kinematics, and spatial distributions. The observed photometric metallicity distribution and that of Ryan and Norris can be described by a simple chemical evolution model by Hartwick (or by a single Gaussian distribution); however, the suggestive metallicity-kinematic correlation contradicts the basic assumption in this model that the Milky Way halo consists primarily of a single stellar population. When the observed metallicity distribution is deconvolved using two Gaussian components with peaks at [Fe/H] Almost-Equal-To -1.7 and -2.3, the metal-poor component accounts for {approx}20%-35% of the entire halo population in this distance range.
Influence of emphysema distribution on pulmonary function parameters in COPD patients
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Helder Novais e Bastos
2015-12-01
Full Text Available ABSTRACT OBJECTIVE: To evaluate the impact that the distribution of emphysema has on clinical and functional severity in patients with COPD. METHODS: The distribution of the emphysema was analyzed in COPD patients, who were classified according to a 5-point visual classification system of lung CT findings. We assessed the influence of emphysema distribution type on the clinical and functional presentation of COPD. We also evaluated hypoxemia after the six-minute walk test (6MWT and determined the six-minute walk distance (6MWD. RESULTS: Eighty-six patients were included. The mean age was 65.2 ± 12.2 years, 91.9% were male, and all but one were smokers (mean smoking history, 62.7 ± 38.4 pack-years. The emphysema distribution was categorized as obviously upper lung-predominant (type 1, in 36.0% of the patients; slightly upper lung-predominant (type 2, in 25.6%; homogeneous between the upper and lower lung (type 3, in 16.3%; and slightly lower lung-predominant (type 4, in 22.1%. Type 2 emphysema distribution was associated with lower FEV1, FVC, FEV1/FVC ratio, and DLCO. In comparison with the type 1 patients, the type 4 patients were more likely to have an FEV1 < 65% of the predicted value (OR = 6.91, 95% CI: 1.43-33.45; p = 0.016, a 6MWD < 350 m (OR = 6.36, 95% CI: 1.26-32.18; p = 0.025, and post-6MWT hypoxemia (OR = 32.66, 95% CI: 3.26-326.84; p = 0.003. The type 3 patients had a higher RV/TLC ratio, although the difference was not significant. CONCLUSIONS: The severity of COPD appears to be greater in type 4 patients, and type 3 patients tend to have greater hyperinflation. The distribution of emphysema could have a major impact on functional parameters and should be considered in the evaluation of COPD patients.
Sala, Joseph B; Rämä, Pia; Courtney, Susan M
2003-01-01
We investigated the degree to which the distributed and overlapping patterns of activity for working memory (WM) maintenance of objects and spatial locations are functionally dissociable. Previous studies of the neural system responsible for maintenance of different types of information in WM have reported seemingly contradictory results concerning the degree to which spatial and nonspatial information maintenance leads to distinct patterns of activation in prefrontal cortex. These inconsistent results may be partly attributable to the fact that different types of objects were used for the "object WM task" across studies. In the current study, we directly compared the patterns of response during WM tasks for face identity, house identity, and spatial location using functional magnetic resonance imaging (fMRI). Furthermore, independence of the neural resources available for spatial and object WM was tested behaviorally using a dual-task paradigm. Together, these results suggest that the mechanisms for the maintenance of house identity information are distributed and overlapping with those that maintain spatial location information, while the mechanisms for maintenance of face identity information are relatively more independent. There is, however, a consistent functional topography that results in superior prefrontal cortex producing the greatest response during spatial WM tasks, and middle and inferior prefrontal cortices producing their greatest responses during object WM tasks, independent of the object type. These results argue for a dorsal-ventral functional organization for spatial and nonspatial information. However, objects may contain both spatial and nonspatial information and, thus, have a distributed but not equipotent representation across both dorsal and ventral prefrontal cortex.
Zhang, Shiyi
The overall emphasis of this dissertation research included two kinds of asymmetrically-functionalized nanoparticles with anisotropic distributions of chemical functionalities, three degradable polymers synthesized by organocatalyzed ring-opening polymerizations, and two polyphosphoester-based nanoparticle systems for various biomedical applications. Inspired by the many hierarchical assembly processes that afford complex materials in Nature, the construction of asymmetrically-functionalized nanoparticles with efficient surface chemistries and the directional organization of those building blocks into complex structures have attracted much attention. The first method generated a Janus-faced polymer nanoparticle that presented two orthogonally click-reactive surface chemistries, thiol and azido. This robust method involved reactive functional group transfer by templating against gold nanoparticle substrates. The second method produced nanoparticles with sandwich-like distribution of crown ether functionalities through a stepwise self-assembly process that utilized crown ether-ammonium supramolecular interactions to mediate inter-particle association and the local intra-particle phase separation of unlike hydrophobic polymers. With the goal to improve the efficiency of the production of degradable polymers with tunable chemical and physical properties, a new type of reactive polyphosphoester was synthesized bearing alkynyl groups by an organocatalyzed ring-opening polymerization, the chemical availability of the alkyne groups was investigated by employing "click" type azide-alkyne Huisgen cycloaddition and thiol-yne radical-mediated reactions. Based on this alkyne-functionalized polyphosphoester polymer and its two available "click" type reactions, two degradable nanoparticle systems were developed. To develop the first system, the well defined poly(ethylene oxide)-block-polyphosphester diblock copolymer was transformed into a multifunctional Paclitaxel drug
Neumann, Martin; Zoppi, Marco
2002-03-01
We have performed extensive path integral Monte Carlo simulations of liquid and solid neon, in order to derive the kinetic energy as well as the single-particle and pair distribution functions of neon atoms in the condensed phases. From the single-particle distribution function n(r) one can derive the momentum distribution and thus obtain an independent estimate of the kinetic energy. The simulations have been carried out using mostly the semiempirical HFD-C2 pair potential by Aziz et al. [R. A. Aziz, W. J. Meath, and A. R. Allnatt, Chem. Phys. 79, 295 (1983)], but, in a few cases, we have also used the Lennard-Jones potential. The differences between the potentials, as measured by the properties investigated, are not very large, especially when compared with the actual precision of the experimental data. The simulation results have been compared with all the experimental information that is available from neutron scattering. The overall agreement with the experiments is very good.
Main functions and taxonomic distribution of virulence genes in Brucella melitensis 16 M.
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Aniel Jessica Leticia Brambila-Tapia
Full Text Available Many virulence genes have been detected in attenuated mutants of Brucella melitensis 16 M; nevertheless, a complete report of these genes, including the main Cluster of Orthologous Groups (COG represented as well as the taxonomical distribution among all complete bacterial and archaeal genomes, has not been analyzed. In this work a total of 160 virulence genes that have been reported in attenuated mutants in B. melitensis were included and analyzed. Additionally, we obtained 250 B. melitensis randomly selected genes as a reference group for the taxonomical comparisons. The COGs and the taxonomical distribution profile for 789 nonredundant bacterial and archaeal genomes were obtained and compared with the whole-genome COG distribution and with the 250 randomly selected genes, respectively. The main COGs associated with virulence genes corresponded to the following: intracellular trafficking, secretion and vesicular transport (U; cell motility (N; nucleotide transport and metabolism (F; transcription (K; and cell wall/membrane/envelope biogenesis (M. In addition, we found that virulence genes presented a higher proportion of orthologs in the Euryarchaeota and Proteobacteria phyla, with a significant decrease in Chlamydiae, Bacteroidetes, Tenericutes, Firmicutes and Thermotogae. In conclusion, we found that genes related to specific functions are more relevant to B. melitensis virulence, with the COG U the most significant. Additionally, the taxonomical distribution of virulence genes highlights the importance of these genes in the related Proteobacteria, being less relevant in distant groups of organisms with the exception of Euryarchaeota.
Effects of Acids, Bases, and Heteroatoms on Proximal Radial Distribution Functions for Proteins.
Nguyen, Bao Linh; Pettitt, B Montgomery
2015-04-14
The proximal distribution of water around proteins is a convenient method of quantifying solvation. We consider the effect of charged and sulfur-containing amino acid side-chain atoms on the proximal radial distribution function (pRDF) of water molecules around proteins using side-chain analogs. The pRDF represents the relative probability of finding any solvent molecule at a distance from the closest or surface perpendicular protein atom. We consider the near-neighbor distribution. Previously, pRDFs were shown to be universal descriptors of the water molecules around C, N, and O atom types across hundreds of globular proteins. Using averaged pRDFs, a solvent density around any globular protein can be reconstructed with controllable relative error. Solvent reconstruction using the additional information from charged amino acid side-chain atom types from both small models and protein averages reveals the effects of surface charge distribution on solvent density and improves the reconstruction errors relative to simulation. Solvent density reconstructions from the small-molecule models are as effective and less computationally demanding than reconstructions from full macromolecular models in reproducing preferred hydration sites and solvent density fluctuations.
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A. B. Levina
2016-03-01
Full Text Available Error detection codes are mechanisms that enable robust delivery of data in unreliable communication channels and devices. Unreliable channels and devices are error-prone objects. Respectively, error detection codes allow detecting such errors. There are two classes of error detecting codes - classical codes and security-oriented codes. The classical codes have high percentage of detected errors; however, they have a high probability to miss an error in algebraic manipulation. In order, security-oriented codes are codes with a small Hamming distance and high protection to algebraic manipulation. The probability of error masking is a fundamental parameter of security-oriented codes. A detailed study of this parameter allows analyzing the behavior of the error-correcting code in the case of error injection in the encoding device. In order, the complexity of the encoding function plays an important role in the security-oriented codes. Encoding functions with less computational complexity and a low probability of masking are the best protection of encoding device against malicious acts. This paper investigates the influence of encoding function complexity on the error masking probability distribution. It will be shownthat the more complex encoding function reduces the maximum of error masking probability. It is also shown in the paper that increasing of the function complexity changes the error masking probability distribution. In particular, increasing of computational complexity decreases the difference between the maximum and average value of the error masking probability. Our resultshave shown that functions with greater complexity have smoothed maximums of error masking probability, which significantly complicates the analysis of error-correcting code by attacker. As a result, in case of complex encoding function the probability of the algebraic manipulation is reduced. The paper discusses an approach how to measure the error masking
Guasp, J.; Pastor, I.; Álvarez-Estrada, R. F.; Castejón, F.
2015-02-01
Analytical results obtained recently of the ab-initio classical incoherent Thomson Scattering (TS) spectrum from a single-electron (Alvarez-Estrada et al 2012 Phys. Plasmas 19 062302) have been numerically implemented in a paralelized code to efficiently compute the TS emission from a given electron distribution function, irrespective of its characteristics and/or the intensity of the incoming radiation. These analytical results display certain differences, when compared with other authors, in the general case of incoming linearly and circularly polarized radiation and electrons with arbitrary initial directions. We regard such discrepancies and the ubiquitous interest in TS as motivations for this work. Here, we implement some analytical advances (like generalized Bessel functions for incoming linearly polarized radiation) in TS. The bulk of this work reports on the efficient computation of TS spectra (based upon our analytical approach), for an electron population having an essentially arbitrary distribution function and for both incoming linearly and circularly polarized radiation. A detailed comparison between the present approach and a previous Monte Carlo one (Pastor et al 2011 Nuclear Fusion 51 043011), dealing with the ab-initio computation of TS spectra, is reported. Both approaches are shown to fully agree with each other. As key computational improvements, the analytical technique yields a × 30 to × 100 gain in computation time and is a very flexible tool to compute the scattered spectrum and eventually the scattered electromagnetic fields in the time domain. The latter are computed explicitly here for the first time, as far as we know. Scaling laws for the power integrated over frequency versus initial kinetic energy are studied for the case of isotropic and monoenergetic electron distribution functions and their potential application as diagnostic tools for high-energy populations is briefly discussed. Finally, we discuss the application of these
Escala, Ivanna; Kirby, Evan N.; Wetzel, Andrew R.; Hopkins, Philip F.
2016-06-01
We examine the metallicity distribution functions (MDFs) of simulated, isolated dwarf galaxies (M_{star} = 4 × 10^{4} - 3 × 10^{8} M_{⊙}) from the Feedback in Realistic Environments (FIRE) project to quantify the impact of star formation history (SFH) and baryonic physics. These high-resolution cosmological simulations include realistic treatments of stellar evolution and complex gas dynamics and do not require the usual approximations (e.g., instantaneous recycling and instantaneous mixing) of analytic chemical evolution models. The evolution of the MDF with redshift informs which processes drive the dominant contributions to the distribution at z = 0, thus enabling a reconstruction of the SFH and gas loss/accretion history. We then compare the theoretical MDFs to the observed MDFs of Local Group dwarf galaxies to infer plausible SFHs for each matched galaxy.
Cumulative distribution functions associated with bubble-nucleation processes in cavitation
Watanabe, Hiroshi
2010-11-15
Bubble-nucleation processes of a Lennard-Jones liquid are studied by molecular dynamics simulations. Waiting time, which is the lifetime of a superheated liquid, is determined for several system sizes, and the apparent finite-size effect of the nucleation rate is observed. From the cumulative distribution function of the nucleation events, the bubble-nucleation process is found to be not a simple Poisson process but a Poisson process with an additional relaxation time. The parameters of the exponential distribution associated with the process are determined by taking the relaxation time into account, and the apparent finite-size effect is removed. These results imply that the use of the arithmetic mean of the waiting time until a bubble grows to the critical size leads to an incorrect estimation of the nucleation rate. © 2010 The American Physical Society.
Invertebrate lysozymes: Diversity and distribution, molecular mechanism and in vivo function
Indian Academy of Sciences (India)
Joris M Van Herreweghe; Chris W Michiels
2012-06-01
Lysozymes are antibacterial enzymes widely distributed among organisms. Within the animal kingdom, mainly three major lysozyme types occur. Chicken (c)-type lysozyme and goose (g)-type lysozyme are predominantly, but not exclusively, found in vertebrate animals, while the invertebrate (i)-type lysozyme is typical for invertebrate organisms, and hence its name. Since their discovery in 1975, numerous research articles report on the identification of i-type lysozymes in a variety of invertebrate phyla. This review describes the current knowledge on i-type lysozymes, outlining their distribution, molecular mechanism and in vivo function taking the representative from Venerupis philippinarum (formerly Tapes japonica) (Vp-ilys) as a model. In addition, invertebrate g-type and ch-type (chalaropsis) lysozymes, which have been described in molluscs and nematodes, respectively, are also briefly discussed.
Green's function formalism in semi-infinite composites: an investigation of local field distribution
Li, Chen; Gu, Ying; Dai, Bing; Gong, Qi-Huang
2004-11-01
In the resonant composites, the formerly developed Green's function formalism (GFF) can be used to compute the local field distribution near resonance. In this paper, we extend the GFF in the infinite network to the semi-infinite networks by the method of image. Using the formalism, we investigate the local field distribution near resonance for the impurity clusters with admittance epsilon0 embedded in one semi-infinite network with epsilon1. With varying the admittance epsilon2 of another semi-infinite network, we find that the local fields in the boundary experience great changes, especially at epsilon2 = -epsilon1. The existence of the boundary enhances the localization of the fields within and around the metallic clusters. Therefore, the intensity of local field is influenced by the arrangement of impurity metallic bonds and its distance from the boundary.
Green's function formalism in semi-infinite composites:an investigation of local field distribution
Institute of Scientific and Technical Information of China (English)
Li Chen; Gu Ying; Dai Bing; Gong Qi-Huang
2004-01-01
In the resonant composites, the formerly developed Green's function formalism (GFF) can be used to compute the local field distribution near resonance. In this paper, we extend the GFF in the infinite network to the semi-infinite networks by the method of image. Using the formalism, we investigate the local field distribution near resonance for the impurity clusters with admittance ∈0 embedded in one semi-infinite network with ∈1. With varying the admittance ∈2 of another semi-infinite network, we find that the local fields in the boundary experience great changes, especially at ∈2= -∈1. The existence of the boundary enhances the localization of the fields within and around the metallic clusters.Therefore, the intensity of local field is influenced by the arrangement of impurity metallic bonds and its distance from the boundary.
Performance Analytical Model of IEEE 802.11 Distributed Coordination Function
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
IEEE 802.11 distributed coordination function (DCF) is a distributed medium access scheme based on carrier sense multiple access with collision avoidance (CSMA/CA) protocol. Many literatures have analyzed the performance of IEEE 802.11 DCF. However, such literatures either used simulation methods or built the analytical models under the assumption that the saturation condition was satisfied. To overcome such a problem, in this paper, a bi-dimensional Markovian model has been introduced to depict the DCF mechanism. The proposed model introduced an idle stage and a discrete time M/G/1 queue to deduce the channel throughput under finite load traffic. Simulation results proved the accuracy of the proposed model.
Mer, K. K. S.; Ray, S.
2011-12-01
Functionally graded cylindrical ingot of Al-Al2O3 composite synthesized by centrifugal casting shows particle distribution and hardness decreasing radially from the outer radius to inner radius. The progressive decrease in alumina content and hardness from the outer radius towards the center may be attributed to higher centrifugal force acting on relatively denser alumina particles during rotation, as compared to that acting on lighter alloy melt. It is also observed, as one moves down from the top to the bottom of cast ingot the alumina content decreases. This is surprising in view of higher density of alumina particles relative to the melt. The particle settling should have resulted at more particles towards the bottom, but distribution observed is in contradiction.
Modelling the bidirectional reflectance distribution functions (BRDF of sea areas polluted by oil
Directory of Open Access Journals (Sweden)
Zbigniew Otremba
2004-12-01
Full Text Available The paper discusses the possibilities of modelling the bi-directional reflectance distribution function (BRDF in sea areas polluted by oil. Three sea basin models are considered: a coastal one free of oil, one polluted by an oil film and one polluted by an oil emulsion. The following concentrations of oil were compared: for the film, 1 cm3 of oil per 1 m2 water surface, for the emulsion 1 cm3 of oil in 1 m3 of water. The optical properties of Romashkino crude oil were taken into consideration, as were various angles of incident solar light. The conversion of BRDFs into a directional distribution of the optical contrast of polluted areas is demonstrated.
SUePDF: a program to obtain quantitative pair distribution functions from electron diffraction data
Tran, Dung Trung; Svensson, Gunnar; Tai, Cheuk-Wai
2017-01-01
SUePDF is a graphical user interface program written in MATLAB to achieve quantitative pair distribution functions (PDFs) from electron diffraction data. The program facilitates structural studies of amorphous materials and small nanoparticles using electron diffraction data from transmission electron microscopes. It is based on the physics of electron scattering as well as the total scattering methodology. A method of background modeling is introduced to treat the intensity tail of the direct beam, inelastic scattering and incoherent multiple scattering. Kinematical electron scattering intensity is scaled using the electron scattering factors. The PDFs obtained after Fourier transforms are normalized with respect to number density, nanoparticle form factor and the non-negativity of probability density. SUePDF is distributed as free software for academic users. PMID:28190994
Energy Technology Data Exchange (ETDEWEB)
Dodt, Dirk Hilar
2009-01-05
The experimental determination of the electron energy distribution of a low pressure glow discharge in neon from emission spectroscopic data has been demonstrated. The spectral data were obtained with a simple overview spectrometer and analyzed using a strict probabilistic, Bayesian data analysis. It is this Integrated Data Analysis (IDA) approach, which allows the significant extraction of non-thermal properties of the electron energy distribution function (EEDF). The results bear potential as a non-invasive alternative to probe measurements. This allows the investigation of spatially inhomogeneous plasmas (gradient length smaller than typical probe sheath dimensions) and plasmas with reactive constituents. The diagnostic of reactive plasmas is an important practical application, needed e.g. for the monitoring and control of process plasmas. Moreover, the experimental validation of probe theories for magnetized plasmas as a long-standing topic in plasma diagnostics could be addressed by the spectroscopic method. (orig.)
Institute of Scientific and Technical Information of China (English)
刘波; 王琼林; 刘少武; 于慧芳; 李达; 姚月娟; 潘清; 魏伦
2012-01-01
The modified single base propellant samples were prepared by impregnating blasting oil into single base grains and deactivating deterrent in water medium. The concentration distribution of functional compositions in this propellant was determined by using FTIR micro-spectroscopy. Its combustion performance was investigated by means of closed-bomb and interior ballistic tests. The results show that the concentration of NG distributes parabolically along the radius and the con- centration of NA decreases from the surface to the centre exponentially. The deeper the NG impregnates, the slower the NA concentration decreases, the stronger the progressive combustion is and the better the interior ballistic performance is. When the depth corresponding to maximum NG concentration is about 1/2 of the web and the NA decreases slowly, the pro- gressive combustion is the strongest and the interior ballistic performance is the best.
Kitahara, Takeshi; Furuya, Hiroki; Nakamura, Hajime
Since traffic in IP access networks is less aggregated than in backbone networks, its variance could be significant and its distribution may be long-tailed rather than Gaussian in nature. Such characteristics make it difficult to forecast traffic volume in IP access networks for appropriate capacity planning. This paper proposes a traffic forecasting method that includes a function to control residual error distribution in IP access networks. The objective of the proposed method is to grasp the statistical characteristics of peak traffic variations, while conventional methods focus on average rather than peak values. In the proposed method, a neural network model is built recursively while weighting residual errors around the peaks. This enables network operators to control the trade-off between underestimation and overestimation errors according to their planning policy. Evaluation with a total of 136 daily traffic volume data sequences measured in actual IP access networks demonstrates the performance of the proposed method.
Parton distribution functions probed in ultraperipheral collisions at the CERN Large Hadron Collider
Thomas, J; Brady, N; Clark, D B; Godat, E; Olness, F
2016-01-01
Vector meson production in ultra-peripheral pA and AA collisions at the CERN Large Hadron Collider (LHC) are very sensitive to Parton Distribution Functions (PDF) as well as to their leading-order, next-to-leading-order, and medium corrections. This process is a complimentary tool to explore the effects of different PDFs in particle production in proton-nucleus and nucleus-nucleus central collisions. Existing and forthcoming data available, e.g., from ALICE and CMS, may be used in conjunction with our theoretical predictions to constrain the PDFs. We make predictions for rapidity distributions and for cross sections of J/$\\psi$ , $\\psi(2S)$ and $\\Upsilon$ production at $\\sqrt{s_{NN}}=2.76$ TeV and $\\sqrt{s_{NN}}=5$ TeV. We use the second energy as representative for the Run 2 of PbPb collisions at the LHC.
A Proton-Cyclotron Wave Storm Generated by Unstable Proton Distribution Functions in the Solar Wind
Wicks, R. T.; Alexander, R. L.; Stevens, M.; Wilson, L. B., III; Moya, P. S.; Vinas, A.; Jian, L. K.; Roberts, D. A.; O’Modhrain, S.; Gilbert, J. A.; Zurbuchen, T. H.
2016-01-01
We use audification of 0.092 seconds cadence magnetometer data from the Wind spacecraft to identify waves with amplitudes greater than 0.1 nanoteslas near the ion gyrofrequency (approximately 0.1 hertz) with duration longer than 1 hour during 2008. We present one of the most common types of event for a case study and find it to be a proton-cyclotron wave storm, coinciding with highly radial magnetic field and a suprathermal proton beam close in density to the core distribution itself. Using linear Vlasov analysis, we conclude that the long-duration, large-amplitude waves are generated by the instability of the proton distribution function. The origin of the beam is unknown, but the radial field period is found in the trailing edge of a fast solar wind stream and resembles other events thought to be caused by magnetic field footpoint motion or interchange reconnection between coronal holes and closed field lines in the corona.
Yan, Wang-Ji; Ren, Wei-Xin
2016-12-01
Recent advances in signal processing and structural dynamics have spurred the adoption of transmissibility functions in academia and industry alike. Due to the inherent randomness of measurement and variability of environmental conditions, uncertainty impacts its applications. This study is focused on statistical inference for raw scalar transmissibility functions modeled as complex ratio random variables. The goal is achieved through companion papers. This paper (Part I) is dedicated to dealing with a formal mathematical proof. New theorems on multivariate circularly-symmetric complex normal ratio distribution are proved on the basis of principle of probabilistic transformation of continuous random vectors. The closed-form distributional formulas for multivariate ratios of correlated circularly-symmetric complex normal random variables are analytically derived. Afterwards, several properties are deduced as corollaries and lemmas to the new theorems. Monte Carlo simulation (MCS) is utilized to verify the accuracy of some representative cases. This work lays the mathematical groundwork to find probabilistic models for raw scalar transmissibility functions, which are to be expounded in detail in Part II of this study.
Garcia-Molina, Antoni; Andrés-Colás, Nuria; Perea-García, Ana; Neumann, Ulla; Dodani, Sheel C; Huijser, Peter; Peñarrubia, Lola; Puig, Sergi
2013-08-01
Copper (Cu), an essential redox active cofactor, participates in fundamental biological processes, but it becomes highly cytotoxic when present in excess. Therefore, living organisms have established suitable mechanisms to balance cellular and systemic Cu levels. An important strategy to maintain Cu homeostasis consists of regulating uptake and mobilization via the conserved family of CTR/COPT Cu transport proteins. In the model plant Arabidopsis thaliana, COPT1 protein mediates root Cu acquisition, whereas COPT5 protein functions in Cu mobilization from intracellular storage organelles. The function of these transporters becomes critical when environmental Cu bioavailability diminishes. However, little is know about the mechanisms that mediate plant Cu distribution. In this report, we present evidence supporting an important role for COPT6 in Arabidopsis Cu distribution. Similarly to COPT1 and COPT2, COPT6 fully complements yeast mutants defective in high-affinity Cu uptake and localizes to the plasma membrane of Arabidopsis cells. Whereas COPT2 mRNA is only up-regulated upon severe Cu deficiency, COPT6 transcript is expressed under Cu excess conditions and displays a more gradual increase in response to decreases in environmental Cu levels. Consistent with COPT6 expression in aerial vascular tissues and reproductive organs, copt6 mutant plants exhibit altered Cu distribution under Cu-deficient conditions, including increased Cu in rosette leaves but reduced Cu levels in seeds. This altered Cu distribution is fully rescued when the wild-type COPT6 gene is reintroduced into the copt6 mutant line. Taken together, these findings highlight the relevance of COPT6 in shoot Cu redistribution when environmental Cu is limited.
Buffle, J.; Altmann, R. S.; Filella, M.; Tessier, A.
1990-06-01
This paper presents a new conceptual approach to interpreting titration curves of metal complexation by physically and chemically heterogeneous natural complexants such as humic acids, clays, complete soils, or sediments. The physico-chemical and analytical difficulties encountered with such systems are reviewed by comparison with a system containing only a few simple ligands, followed by discussion of the new approach on the same basis. It is shown that interpretation of heterogeneous complexant properties necessitates a preliminary transformation of experimental raw data into a function sufficiently normalized so as to allow comparison of results obtained under different conditions. A normalized function called a Site Occupation Distribution Function (SODF) and its potential usefulness is described here. The SODF is a readily computable function which relates the complexation buffer intensity of the system to the differential free energy of the complexation sites present. Its major interest is that it enables one to obtain both a rigorous mathematical description of the complexant properties (even when highly heterogeneous) at the macroscopic level and, in certain cases, an estimation of the molecular-scale behavior of particular site types. The relationship of the SODF to other distribution functions proposed in the literature is discussed and applications are exemplified using simulated and real natural systems. In particular, its utility is discussed in detail for (1) discriminating between different site types (major, minor, dominant, background), (2) evaluating the degree of heterogeneity of an unknown complexant system, (3) estimating the nature and true thermodynamic constants of complexes, and (4) yielding a rigorous definition of "complexation capacity."
Directory of Open Access Journals (Sweden)
Ahmad Herison
2014-04-01
Full Text Available Mangrove ecosystem existence is important for environment and other organisms because of its ecological and economical values, so that management and preservation of mangrove ecosystem are needed. The purpose of this research was to determine the existing condition of mangrove, both its distribution and its functional transformation in Indah Kapuk Coastal Area. Avicennia marina becomes important as wave attenuation, a form of abrasion antidote. Transect-Square and Spot-Check methods were used to determine the existing condition of A.marina mangrove forests. Autocad program, coordinate converter, Google Earth, Google Map, and Arc View were applied in process of making mangrove distribution map. In western of research location exactly at Station 1 and Station 2, the density value of mangrove was 450 and 825 tree ha-1, respectively with sparse category because they were contaminated by waste and litter. In eastern of research location namely Station 3, Station 4, and Station 5 the mangroves grow well with density value of 650 (sparse, 1,500 (very dense, and 1,200 tree ha-1 (fair, respectively, eventhough the contamination still happened. The mangrove forests around the stations do not function as wave attenuation because there were many waterfront constructions which have replaced the function of mangrove forests to damp the wave. In short, it can be stated that the mangrove's function has changed in a case of wave attenuation. The function of mangrove forests is not determined by mangrove forest density but it is determined by mangrove's free position.Keywords: Avicennia marina, mangrove, wave attenuation, waterfront constructions
Goldstein, Sheldon; Lebowitz, Joel L.; Mastrodonato, Christian; Tumulka, Roderich; Zanghì, Nino
2016-03-01
A quantum system (with Hilbert space {H}1) entangled with its environment (with Hilbert space {H}2) is usually not attributed to a wave function but only to a reduced density matrix {ρ1}. Nevertheless, there is a precise way of attributing to it a random wave function {ψ1}, called its conditional wave function, whose probability distribution {μ1} depends on the entangled wave function {ψ in H1 ⊗ H2} in the Hilbert space of system and environment together. It also depends on a choice of orthonormal basis of H2 but in relevant cases, as we show, not very much. We prove several universality (or typicality) results about {μ1}, e.g., that if the environment is sufficiently large then for every orthonormal basis of H2, most entangled states {ψ} with given reduced density matrix {ρ1} are such that {μ1} is close to one of the so-called GAP (Gaussian adjusted projected) measures, {GAP(ρ1)}. We also show that, for most entangled states {ψ} from a microcanonical subspace (spanned by the eigenvectors of the Hamiltonian with energies in a narrow interval {[E, E+ δ E]}) and most orthonormal bases of H2, {μ1} is close to {GAP({tr}2 ρ_{mc})} with {ρ_{mc}} the normalized projection to the microcanonical subspace. In particular, if the coupling between the system and the environment is weak, then {μ1} is close to {GAP(ρ_β)} with {ρ_β} the canonical density matrix on H1 at inverse temperature {β=β(E)}. This provides the mathematical justification of our claim in Goldstein et al. (J Stat Phys 125: 1193-1221, 2006) that GAP measures describe the thermal equilibrium distribution of the wave function.
Directory of Open Access Journals (Sweden)
Tanabe Naoya
2012-04-01
Full Text Available Abstract Background The progression of chronic obstructive pulmonary disease (COPD considerably varies among patients. Those with emphysema identified by quantitative computed tomography (CT are associated with the rapid progression assessed by forced expiratory volume in one second (FEV1. However, whether the rate of the decline in lung function is independently affected by the regional distribution or the severity of emphysema in the whole lung is unclear. Methods We followed up 131 male patients with COPD for a median of 3.7 years. We measured wall area percent (WA% in right apical segmental bronchus, total lung volume, percent low attenuation volume (LAV%, and the standard deviation (SD of LAV% values from CT images of 10 isovolumetric partitions (SD-LAV as an index of cranial-caudal emphysema heterogeneity. Annual changes in FEV1 were then determined using a random coefficient model and relative contribution of baseline clinical parameters, pulmonary function, and CT indexes including LAV%, SD-LAV, and WA% to annual changes in FEV1 were examined. Results The mean (SD annual change in FEV1 was −44.4 (10.8 mL. Multivariate random coefficient model showed that higher baseline FEV1, higher LAV%, current smoking, and lower SD-LAV independently contributed to an excessive decline in FEV1, whereas ratio of residual volume to total lung capacity, ratio of diffusing capacity to alveolar ventilation, and WA% did not, after adjusting for age, height, weight, and ratio of CT-measured total lung volume to physiologically-measured total lung capacity. Conclusions A more homogeneous distribution of emphysema contributed to an accelerated decline in FEV1 independently of baseline pulmonary function, whole-lung emphysema severity, and smoking status. In addition to whole-lung analysis of emphysema, CT assessment of the cranial-caudal distribution of emphysema might be useful for predicting rapid, progressive disease and for developing a targeted
Calculation of momentum distribution function of a non-thermal fermionic dark matter
Biswas, Anirban; Gupta, Aritra
2017-03-01
The most widely studied scenario in dark matter phenomenology is the thermal WIMP scenario. Inspite of numerous efforts to detect WIMP, till now we have no direct evidence for it. A possible explanation for this non-observation of dark matter could be because of its very feeble interaction strength and hence, failing to thermalise with the rest of the cosmic soup. In other words, the dark matter might be of non-thermal origin where the relic density is obtained by the so-called freeze-in mechanism. Furthermore, if this non-thermal dark matter is itself produced substantially from the decay of another non-thermal mother particle, then their distribution functions may differ in both size and shape from the usual equilibrium distribution function. In this work, we have studied such a non-thermal (fermionic) dark matter scenario in the light of a new type of U(1)B‑L model. The U(1)B‑L model is interesting, since, besides being anomaly free, it can give rise to neutrino mass by Type II see-saw mechanism. Moreover, as we will show, it can accommodate a non-thermal fermionic dark matter as well. Starting from the collision terms, we have calculated the momentum distribution function for the dark matter by solving a coupled system of Boltzmann equations. We then used it to calculate the final relic abundance, as well as other relevant physical quantities. We have also compared our result with that obtained from solving the usual Boltzmann (or rate) equations directly in terms of comoving number density, Y. Our findings suggest that the latter approximation is valid only in cases where the system under study is close to equilibrium, and hence should be used with caution.
Modeling fractal structure of city-size distributions using correlation functions.
Directory of Open Access Journals (Sweden)
Yanguang Chen
Full Text Available Zipf's law is one the most conspicuous empirical facts for cities, however, there is no convincing explanation for the scaling relation between rank and size and its scaling exponent. Using the idea from general fractals and scaling, I propose a dual competition hypothesis of city development to explain the value intervals and the special value, 1, of the power exponent. Zipf's law and Pareto's law can be mathematically transformed into one another, but represent different processes of urban evolution, respectively. Based on the Pareto distribution, a frequency correlation function can be constructed. By scaling analysis and multifractals spectrum, the parameter interval of Pareto exponent is derived as (0.5, 1]; Based on the Zipf distribution, a size correlation function can be built, and it is opposite to the first one. By the second correlation function and multifractals notion, the Pareto exponent interval is derived as [1, 2. Thus the process of urban evolution falls into two effects: one is the Pareto effect indicating city number increase (external complexity, and the other the Zipf effect indicating city size growth (internal complexity. Because of struggle of the two effects, the scaling exponent varies from 0.5 to 2; but if the two effects reach equilibrium with each other, the scaling exponent approaches 1. A series of mathematical experiments on hierarchical correlation are employed to verify the models and a conclusion can be drawn that if cities in a given region follow Zipf's law, the frequency and size correlations will follow the scaling law. This theory can be generalized to interpret the inverse power-law distributions in various fields of physical and social sciences.
Modeling fractal structure of city-size distributions using correlation functions.
Chen, Yanguang
2011-01-01
Zipf's law is one the most conspicuous empirical facts for cities, however, there is no convincing explanation for the scaling relation between rank and size and its scaling exponent. Using the idea from general fractals and scaling, I propose a dual competition hypothesis of city development to explain the value intervals and the special value, 1, of the power exponent. Zipf's law and Pareto's law can be mathematically transformed into one another, but represent different processes of urban evolution, respectively. Based on the Pareto distribution, a frequency correlation function can be constructed. By scaling analysis and multifractals spectrum, the parameter interval of Pareto exponent is derived as (0.5, 1]; Based on the Zipf distribution, a size correlation function can be built, and it is opposite to the first one. By the second correlation function and multifractals notion, the Pareto exponent interval is derived as [1, 2). Thus the process of urban evolution falls into two effects: one is the Pareto effect indicating city number increase (external complexity), and the other the Zipf effect indicating city size growth (internal complexity). Because of struggle of the two effects, the scaling exponent varies from 0.5 to 2; but if the two effects reach equilibrium with each other, the scaling exponent approaches 1. A series of mathematical experiments on hierarchical correlation are employed to verify the models and a conclusion can be drawn that if cities in a given region follow Zipf's law, the frequency and size correlations will follow the scaling law. This theory can be generalized to interpret the inverse power-law distributions in various fields of physical and social sciences.
CDF-XL: computing cumulative distribution functions of reaction time data in Excel.
Houghton, George; Grange, James A
2011-12-01
In experimental psychology, central tendencies of reaction time (RT) distributions are used to compare different experimental conditions. This emphasis on the central tendency ignores additional information that may be derived from the RT distribution itself. One method for analysing RT distributions is to construct cumulative distribution frequency plots (CDFs; Ratcliff, Psychological Bulletin 86:446-461, 1979). However, this method is difficult to implement in widely available software, severely restricting its use. In this report, we present an Excel-based program, CDF-XL, for constructing and analysing CDFs, with the aim of making such techniques more readily accessible to researchers, including students (CDF-XL can be downloaded free of charge from the Psychonomic Society's online archive). CDF-XL functions as an Excel workbook and starts from the raw experimental data, organised into three columns (Subject, Condition, and RT) on an Input Data worksheet (a point-and-click utility is provided for achieving this format from a broader data set). No further preprocessing or sorting of the data is required. With one click of a button, CDF-XL will generate two forms of cumulative analysis: (1) "standard" CDFs, based on percentiles of participant RT distributions (by condition), and (2) a related analysis employing the participant means of rank-ordered RT bins. Both analyses involve partitioning the data in similar ways, but the first uses a "median"-type measure at the participant level, while the latter uses the mean. The results are presented in three formats: (i) by participants, suitable for entry into further statistical analysis; (ii) grand means by condition; and (iii) completed CDF plots in Excel charts.
Directory of Open Access Journals (Sweden)
Chris Bambey Guure
2012-01-01
Full Text Available The survival function of the Weibull distribution determines the probability that a unit or an individual will survive beyond a certain specified time while the failure rate is the rate at which a randomly selected individual known to be alive at time will die at time (. The classical approach for estimating the survival function and the failure rate is the maximum likelihood method. In this study, we strive to determine the best method, by comparing the classical maximum likelihood against the Bayesian estimators using an informative prior and a proposed data-dependent prior known as generalised noninformative prior. The Bayesian estimation is considered under three loss functions. Due to the complexity in dealing with the integrals using the Bayesian estimator, Lindley’s approximation procedure is employed to reduce the ratio of the integrals. For the purpose of comparison, the mean squared error (MSE and the absolute bias are obtained. This study is conducted via simulation by utilising different sample sizes. We observed from the study that the generalised prior we assumed performed better than the others under linear exponential loss function with respect to MSE and under general entropy loss function with respect to absolute bias.
The effects of body fat distribution on pulmonary function tests in the overweight and obese.
Ceylan, Emel; Cömlekçi, Abdurrahman; Akkoçlu, Atila; Ceylan, Cengiz; Itil, Oya; Ergör, Gül; Yeşil, Sena
2009-01-01
To determine the predominant pulmonary function abnormality in overweight and moderately obese subjects and to evaluate the correlation between the severity of lung function impairment and the degree of obesity. Fifty-three volunteers underwent physical examination, skin fold measurements, and standardized pulmonary function tests. Thirty-one women and 22 men with a mean age of 40.2 (18-66) years were studied. The reduction in functional residual capacity (FRC) and expiratory reserve volume (ERV) were the most common abnormalities in overweight and obese subjects. The reduction in static lung volume was correlated with the degree of obesity in women and men. Stepwise multiple regression coefficients were obtained separately for women and men. Subscapular skinfold was the best predictor in women for FRC and waist-to-hip ratio (WHR) and BMI were found the best for ERV. WHR was found predictive for forced vital capacity, total lung capacity, and FRC in men. The lung volumes are substantially affected in our overweight and obese subjects. This influence is focused on different parameters of respiratory functions in men and women in relation to body fat distribution.
Cancer-associated mutations are preferentially distributed in protein kinase functional sites.
Izarzugaza, Jose M G; Redfern, Oliver C; Orengo, Christine A; Valencia, Alfonso
2009-12-01
Protein kinases are a superfamily involved in many crucial cellular processes, including signal transmission and regulation of cell cycle. As a consequence of this role, kinases have been reported to be associated with many types of cancer and are considered as potential therapeutic targets. We analyzed the distribution of pathogenic somatic point mutations (drivers) in the protein kinase superfamily with respect to their location in the protein, such as in structural, evolutionary, and functionally relevant regions. We find these driver mutations are more clearly associated with key protein features than other somatic mutations (passengers) that have not been directly linked to tumor progression. This observation fits well with the expected implication of the alterations in protein kinase function in cancer pathogenicity. To explain the relevance of the detected association of cancer driver mutations at the molecular level in the human kinome, we compare these with genetically inherited mutations (SNPs). We find that the subset of nonsynonymous SNPs that are associated to disease, but sufficiently mild to the point of being widespread in the population, tend to avoid those key protein regions, where they could be more detrimental for protein function. This tendency contrasts with the one detected for cancer associated-driver-mutations, which seems to be more directly implicated in the alteration of protein function. The detailed analysis of protein kinase groups and a number of relevant examples, confirm the relation between cancer associated-driver-mutations and key regions for protein kinase structure and function.
Wang, Huihui; Sukhomlinov, Vladimir S.; Kaganovich, Igor D.; Mustafaev, Alexander S.
2017-02-01
Based on accurate representation of the He+-He angular differential scattering cross sections consisting of both elastic and charge exchange collisions, we performed detailed numerical simulations of the ion velocity distribution functions (IVDF) by Monte Carlo collision method (MCC). The results of simulations are validated by comparison with the experimental data of the ion mobility and the transverse diffusion. The IVDF simulation study shows that due to significant effect of scattering in elastic collisions IVDF cannot be separated into product of two independent IVDFs in the transverse and parallel to the electric field directions.
A New Analytic Method for IEEE 802.11 Distributed Coordination Function
Hwang, Gang Uk; Chung, Min Young; Lee, Yutae
In this paper, we consider a network of N identical IEEE 802.11 DCF (Distributed Coordination Function) terminals with RTS/CTS mechanism, each of which is assumed to be saturated. For performance analysis, we propose a simple and efficient mathematical model to derive the statistical characteristics of the network such as the inter-transmission time of packets in the network and the service time (the inter-transmission time of successful packet transmissions) of the network. Numerical results and simulations are provided to validate the accuracy of our model and to study the performance of the IEEE 802.11 DCF network.
APFEL Web a web-based application for the graphical visualization of parton distribution functions
Carrazza, Stefano; Palazzo, Daniele; Rojo, Juan
2015-01-01
We present APFEL Web, a web-based application designed to provide a flexible user-friendly tool for the graphical visualization of parton distribution functions (PDFs). In this note we describe the technical design of the APFEL Web application, motivating the choices and the framework used for the development of this project. We document the basic usage of APFEL Web and show how it can be used to provide useful input for a variety of collider phenomenological studies. Finally we provide some examples showing the output generated by the application.
Distribution Function Estimation of the Timing Jitter in Sample Rate Converter
Directory of Open Access Journals (Sweden)
Vipan Kakkar
2010-04-01
Full Text Available The aim of digital sample rate conversion is to bring a digital audio signal from one sample frequency to another. The distortion of the audio signal introduced by the sample rate converter should be as low as possible. The generation of the output samples from the inputsamples may be performed by the application of various methods. In this paper, a new technique of digital sample-rate converter is proposed. We perform the analysis for distribution function estimation of the timing jitter in proposed digital sample rate converter.
Energy Technology Data Exchange (ETDEWEB)
Ward, Gregory; Mistrick, Ph.D., Richard; Lee, Eleanor; McNeil, Andrew; Jonsson, Ph.D., Jacob
2011-01-21
We describe two methods which rely on bidirectional scattering distribution functions (BSDFs) to model the daylighting performance of complex fenestration systems (CFS), enabling greater flexibility and accuracy in evaluating arbitrary assemblies of glazing, shading, and other optically-complex coplanar window systems. Two tools within Radiance enable a) efficient annual performance evaluations of CFS, and b) accurate renderings of CFS despite the loss of spatial resolution associated with low-resolution BSDF datasets for inhomogeneous systems. Validation, accuracy, and limitations of the methods are discussed.
Radial distribution function for hard spheres in fractal dimensions. A heuristic approximation
Santos, Andrés
2016-01-01
Analytic approximations for the radial distribution function, the structure factor, and the equation of state of hard-core fluids in fractal dimension $d$ ($1 \\leq d \\leq 3$) are developed as heuristic interpolations from the knowledge of the exact and Percus-Yevick results for the hard-rod and hard-sphere fluids, respectively. In order to assess their value, such approximate results are compared with those of recent Monte Carlo simulations and numerical solutions of the Percus-Yevick equation for fractal dimension [M. Heinen et al., Phys. Rev. Lett. \\textbf{115}, 097801 (2015)], a good agreement being observed.
Ahmed, Al-Rubaiee A
2013-01-01
In this work the estimation of the lateral distribution function in Extensive Air showers was performed by using a system for air shower simulations which is called AIRES version 2.6 for different hadronic models like (QGSJET99, SIBYLL and SIBYLL1.6). The simulation was fulfilled in the high energy range (10^15-10^19 eV) for different primary particles like (gamma, protons and iron nuclei) for vertical showers. This simulation can be used to reconstruct the type and energy of the particle that generated Extensive Air showers for charged particles that registered with different arrays.
DEFF Research Database (Denmark)
Boetker, Johan P.; Koradia, Vishal; Rades, Thomas
2012-01-01
was subjected to quench cooling thereby creating an amorphous form of the drug from both starting materials. The milled and quench cooled samples were, together with the crystalline starting materials, analyzed with X-ray powder diffraction (XRPD), Raman spectroscopy and atomic pair-wise distribution function...... (PDF) analysis of the XRPD pattern. When compared to XRPD and Raman spectroscopy, the PDF analysis was superior in displaying the difference between the amorphous samples prepared by milling and quench cooling approaches of the two starting materials....
Expansion of a plasma into vacuum with a bi-Maxwellian electron distribution function
Directory of Open Access Journals (Sweden)
Diaw A.
2013-11-01
Full Text Available A comprehensive theory is developped to describe the expansion of a plasma into a vacuum with a two-temperature electron distribution function. The characteristics of the rarefaction shock which occurs in the plasma when the hot- to the cold-electron temperature ratio is larger than 9.9 are investigated with a semi-infinite plasma. Furthermore by using a finite plasma foil, a possible heating of the cold electrons population is evidenced, for a sufficiently large hot- to the cold-electron density ratio.
Modeling and simulation of ion energy distribution functions in technological plasmas
Mussenbrock, Thomas
2011-01-01
The highly advanced treatment of surfaces as etching and deposition is mainly enabled by the extraordinary properties of technological plasmas. The primary factors that influence these processes are the flux and the energy of various species, particularly ions, that impinge the substrate surface. These features can be theoretically described using the ion energy distribution function (IEDF). The article is intended to summarize the fundamental concepts of modeling and simulation of IEDFs from simplified models to self-consistent plasma simulations. Finally, concepts for controlling the IEDF are discussed.
Shi, Guangyuan; Li, Song; Huang, Ke; Li, Zile; Zheng, Guoxing
2016-10-01
We have developed a new numerical ray-tracing approach for LIDAR signal power function computation, in which the light round-trip propagation is analyzed by geometrical optics and a simple experiment is employed to acquire the laser intensity distribution. It is relatively more accurate and flexible than previous methods. We emphatically discuss the relationship between the inclined angle and the dynamic range of detector output signal in biaxial LIDAR system. Results indicate that an appropriate negative angle can compress the signal dynamic range. This technique has been successfully proved by comparison with real measurements.
IEEE 802.11 Distributed Coordination Function:Enhancement and Analysis
Institute of Scientific and Technical Information of China (English)
WU HaiTao(邬海涛); LIN Yu(林宇); CHENG ShiDuan(程时端); PENG Yong(彭泳); LONG KePing(隆克平)
2003-01-01
IEEE 802.11 Medium Access Control (MAC) is proposed to support asynchronousand time bounded delivery of radio packets. Distributed Coordination Function (DCF), which uses Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) and binary slotted exponent ial backoff, is the basis of the 802.11 MAC. This paper proposes a throughput enhancement forDCF by adjusting the Contention Window (CW) setting scheme. Moreover, an analytical modelbased on Markov chain is introduced to compute the enhanced throughput. The accuracy of themodel and the enhancement of the proposed scheme are verified by elaborate simulations.
Energy Technology Data Exchange (ETDEWEB)
Vereshchagin, D.A. [Theoretical Physics Department, Kaliningrad State University, A. Nevsky st. 14, Kaliningrad (Russian Federation); Leble, S.B. [Theoretical Physics Department, Kaliningrad State University, A. Nevsky st. 14, Kaliningrad (Russian Federation) and Theoretical Physics and Mathematical Methods Department, Gdansk University of Technology, ul. Narutowicza 11/12, Gdansk (Poland)]. E-mail: leble@mifgate.pg.gda.pl; Solovchuk, M.A. [Theoretical Physics Department, Kaliningrad State University, A. Nevsky st. 14, Kaliningrad (Russian Federation)]. E-mail: solovchuk@yandex.ru
2006-01-02
The system of hydrodynamic-type equations for a stratified gas in gravity field is derived from BGK equation by method of piecewise continuous distribution function. The obtained system of the equations generalizes the Navier-Stokes one at arbitrary Knudsen numbers. The problem of a wave disturbance propagation in a rarefied gas is explored. The verification of the model is made for a limiting case of a homogeneous medium. The phase velocity and attenuation coefficient values are in an agreement with former fluid mechanics theories; the attenuation behavior reproduces experiment and kinetics-based results at more wide range of the Knudsen numbers.
Rahbar, Kambiz; Faez, Karim; Attaran-Kakhki, Ebrahim
2012-06-01
Reduction of image quality under the effects of wavefront aberration of the optical system has a direct impact on the vision system's performance. This paper tries to estimate the amount of aberration with the use of wavelet transform profilometry. The basic idea is based on the principle that under aberration effects, the position of the fringes' image on the image plane will change, and this change correlates with the amount of aberration. So the distribution of aberration function can directly be extracted through measuring the amount of changes in the fringes' image on the image plane. Experimental results and the empirical validity of this idea are evaluated.
González, Diego Luis; Pimpinelli, Alberto; Einstein, T. L.
2011-07-01
We study the configurational structure of the point-island model for epitaxial growth in one dimension. In particular, we calculate the island gap and capture zone distributions. Our model is based on an approximate description of nucleation inside the gaps. Nucleation is described by the joint probability density pnXY(x,y), which represents the probability density to have nucleation at position x within a gap of size y. Our proposed functional form for pnXY(x,y) describes excellently the statistical behavior of the system. We compare our analytical model with extensive numerical simulations. Our model retains the most relevant physical properties of the system.
Role and Properties of Wilson Lines in Transverse-Momentum-Dependent Parton Distribution Functions
Stefanis, N G; Karanikas, A I
2010-01-01
We summarize the renormalization-group properties of transverse-momentum dependent (TMD) parton distribution functions (PDF)s arguing that in the light-cone gauge the overlapping ultraviolet and rapidity divergences cannot be solely controlled by (dimensional) regularization, but necessitate their renormalization. In doing so, we show that at the one-loop order this additional divergence entails an anomalous dimension which can be attributed to a cusp in the gauge contour at light-cone infinity. Then, we present a recent analysis of TMD PDFs which incorporates in the gauge links the Pauli term $\\sim F^{\\mu\
Drying of brick as a function of heat flows and analysis of moisture and temperature distributions
DEFF Research Database (Denmark)
Svendsen, Sv Aa Højgaard; Rudbeck, Claus Christian; Bunch-Nielsen, Tommy
1997-01-01
In order to investigate the driving mechanisms for frost damages in brickwork, laboratory tests has been performed on a test brick wall. These test include monitoring of temperature and moisture distribution in the wall as function of the influence of driving rain, wind speed and solar radiation....... After the initial tests the surface of the wall was treated with mortar and a new series of test was performed. The wall with and without treatment performed almost equal during the influence of driving rain, and during the later drying phase, the difference was equally small....
A radial distribution function-based open boundary force model for multi-centered molecules
Neumann, Philipp
2014-06-01
We derive an expression for radial distribution function (RDF)-based open boundary forcing for molecules with multiple interaction sites. Due to the high-dimensionality of the molecule configuration space and missing rotational invariance, a computationally cheap, 1D approximation of the arising integral expressions as in the single-centered case is not possible anymore. We propose a simple, yet accurate model invoking standard molecule- and site-based RDFs to approximate the respective integral equation. The new open boundary force model is validated for ethane in different scenarios and shows very good agreement with data from periodic simulations. © World Scientific Publishing Company.
Benavides, Francisco; Leiderman, Ricardo; Souza, Andre; Carneiro, Giovanna; Bagueira, Rodrigo
2017-09-01
In the present work, we formulate and solve an inverse problem to recover the surface relaxivity as a function of pore size. The input data for our technique are the T2 distribution measurement and the micro-tomographic image of the rock sample under investigation. We simulate the NMR relaxation signal for a given surface relaxivity function using the random walk method and rank different surface relaxivity functions according to the correlation of the resulting simulated T2 distributions with the measured T2 distribution. The optimization is performed using genetic algorithms and determines the surface relaxivity function whose corresponding simulated T2 distribution best matches the measured T2 distribution. In the proposed methodology, pore size is associated with a number of collisions in the random walk simulations. We illustrate the application of the proposed method by performing inversions from synthetic and laboratory input data and compare the obtained results with those obtained using the uniform relaxivity assumption.
Hyde, M W; Schmidt, J D; Havrilla, M J
2009-11-23
A polarimetric bidirectional reflectance distribution function (pBRDF), based on geometrical optics, is presented. The pBRDF incorporates a visibility (shadowing/masking) function and a Lambertian (diffuse) component which distinguishes it from other geometrical optics pBRDFs in literature. It is shown that these additions keep the pBRDF bounded (and thus a more realistic physical model) as the angle of incidence or observation approaches grazing and better able to model the behavior of light scattered from rough, reflective surfaces. In this paper, the theoretical development of the pBRDF is shown and discussed. Simulation results of a rough, perfect reflecting surface obtained using an exact, electromagnetic solution and experimental Mueller matrix results of two, rough metallic samples are presented to validate the pBRDF.
Martinez-Medina, L A; Moreno, E; Peimbert, A
2016-01-01
Recent observations show that the Milky Way's metallicity distribution function (MDF) changes its shape as a function of radius. This new evidence of radial migration within the stellar disc sets additional constrains on Galactic models. By performing controlled test particle simulations in a very detailed, observationally motivated model of the Milky Way, we demonstrate that, in the inner region of the disc, the MDF is shaped by the joint action of the bar and spiral arms, while at outer radii the MDF is mainly shaped by the spiral arms. We show that the spiral arms are able to imprint their signature in the radial migration, shaping the MDF in the outskirts of the Galactic disc with a minimal participation of the bar. Conversely, this work has the potential to characterize some structural and dynamical parameters of the spiral arms based on radial migration and the shape of the MDF.
Emerging operando and x-ray pair distribution function methods for energy materials development
Energy Technology Data Exchange (ETDEWEB)
Chapman, Karena W.
2016-03-01
Our energy needs drive widespread materials research. Advances in materials characterization are critical to this research effort. Using new characterization tools that allow us to probe the atomic structure of energy materials in situ as they operate, we can identify how their structure is linked to their functional properties and performance. These fundamental insights serve as a roadmap to enhance performance in the next generation of advanced materials. In the last decade, developments in synchrotron instrumentation have made the pair distribution function (PDF) method and operando x-ray studies more readily accessible tools capable of providing valuable insights into complex materials systems. Here, the emergence of the PDF method as a versatile structure characterization tool and the further enhancement of this method through developments in operando capabilities and multivariate data analytics are described. These advances in materials characterization are demonstrated by several highlighted studies focused on energy storage in batteries.
Testing the process dependence of the Sivers function via hadron distributions inside a jet
Energy Technology Data Exchange (ETDEWEB)
D' Alesio, Umberto [Dipartimento di Fisica, Universita di Cagliari, Cittadella Universitaria, I-09042 Monserrato (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Cagliari, C.P. 170, I-09042 Monserrato (Italy); Gamberg, Leonard, E-mail: lpg10@psu.edu [Division of Science, Penn State Berks, Reading, PA 19610 (United States); Kang Zhongbo [RIKEN BNL Research Center, Brookhaven National Laboratory, Upton, NY 11973 (United States); Murgia, Francesco [Istituto Nazionale di Fisica Nucleare, Sezione di Cagliari, C.P. 170, I-09042 Monserrato (Italy); Pisano, Cristian [Dipartimento di Fisica, Universita di Cagliari, Cittadella Universitaria, I-09042 Monserrato (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Cagliari, C.P. 170, I-09042 Monserrato (Italy)
2011-10-25
We study the process dependence of the Sivers function by considering the impact of color-gauge invariant initial and final state interactions on transverse spin asymmetries in proton-proton scattering reactions within the framework of the transverse momentum dependent (TMD), generalized parton model. To this aim, we consider the azimuthal distribution of leading pions inside a fragmenting jet as well as single inclusive jet asymmetry in polarized proton-proton collisions. In contrast to single inclusive pion production, in both cases we can isolate the Sivers contribution and thereby study its process dependence. The predictions for the Sivers asymmetry obtained with and without inclusion of color gauge factors are comparable in size but with opposite signs. We conclude that both processes represent unique opportunities to discriminate among the two approaches and test the universality properties of the Sivers function in hadronic scattering reactions.
Kakehashi, Yoshiro; Chandra, Sumal
2016-04-01
We have developed a first-principles local ansatz wavefunction approach with momentum-dependent variational parameters on the basis of the tight-binding LDA+U Hamiltonian. The theory goes beyond the first-principles Gutzwiller approach and quantitatively describes correlated electron systems. Using the theory, we find that the momentum distribution function (MDF) bands of paramagnetic bcc Fe along high-symmetry lines show a large deviation from the Fermi-Dirac function for the d electrons with eg symmetry and yield the momentum-dependent mass enhancement factors. The calculated average mass enhancement m*/m = 1.65 is consistent with low-temperature specific heat data as well as recent angle-resolved photoemission spectroscopy (ARPES) data.
Three Semi-empirical Analytic Expressions for the Radial Distribution Function of Hard Spheres
Institute of Scientific and Technical Information of China (English)
SUN Jiu-Xun; CAI Ling-Cang; WU Qiang; JING Fu-Qian
2004-01-01
Three simple analytic expressions satisfying the limitation condition at low densities for the radial distribution function of hard spheres are developed in terms of a polynomial expansion of nonlinear base functions and the Carnahan-Starling equation of state. The simplicity and precision for these expressions are superior to the well-known Percus-Yevick expression. The coefficients contained in these expressions have been determined by fitting the Monte Carlo data for the first coordination shell, and by fitting both the Monte Carlo data and the numerical results of PercusYevick expression for the second coordination shell. One of the expressions has been applied to develop an analytic equation of state for the square-well fluid, and the numerical results are in good agreement with the computer simulation data.
Directory of Open Access Journals (Sweden)
Al-Rubaiee A.
2015-01-01
Full Text Available The Cherenkov light lateral distribution function (LDF was simulated with the CORSIKAcode in the energy range (1013 - 1016 eV. This simulation was performed for conditions and configurations of the Tunka EAS Cherenkov array for the two primary particles (p and Fe. Basing on the simulated results, many approximated functions are structured for two primary particles and different zenith angles. This allowed us to reconstruct the EAS events, which is, to determine the type and energy of the primary particles that produced showers from signal amplitudes of Cherenkov radiation measured by the Tunka Cherenkov array experiment. Comparison of the calculated LDF of Cherenkov radiation with that measured at the Tunka EAS array shows the ability to identify the primary particle that initiated the EAS cascades by determining its primary energy around the knee region of the cosmic ray spectrum.
Johansson, Mikael P; Sundholm, Dage
2004-02-15
We recently performed detailed analyses of the electronic structure of low-spin iron porphyrins using density-functional theory (DFT). Both the spin-density distributions of the oxidized, ferric forms, as well as the changes in total charge density upon reduction to the ferrous forms have been explored. Here, we compare the DFT results with wave-function theory, more specifically, with the approximate singles and doubles coupled-cluster method (CC2). Different spin states are considered by studying representative models of low spin, intermediate spin, and high spin species. The CC2 calculations corroborate the DFT results; the spin density exhibits the same amount of molecular spin polarization, and the charge delocalization is of comparable magnitude. Slight differences in the descriptions are noted and discussed.
On bounds for the characteristic functions of some degenerate multidimensional distributions
Shervashidze, T
2002-01-01
We discuss an application of an inequality for the modulus of the characteristic function of a system of monomials in random variables to the convergence of the density of the corresponding system of the sample mixed moments. We also consider the behavior of constants in the inequality for the characteristic function of a trigonometric analogue of the above-mentioned system when the random variables are independent and uniformly distributed. Both inequalities were derived earlier by the from a multidimensional analogue of Vinogradov's inequality for a trigonometric integral. As a byproduct the lower bound for the spectrum of A sub k A sub k ' is obtained, where A sub k is the matrix of coefficients of the first k+1 Chebyshev polynomials of first kind.
Institute of Scientific and Technical Information of China (English)
DESHOUILLERS; Jean-Marc; HASSANI; Mehdi
2010-01-01
In two previous papers,the first named author jointly with Florian Luca and Henryk Iwaniec,have studied the distribution modulo 1 of sequences which have linear growth and are mean values of multiplicative functions on the set of all the integers.In this note,we give a first result concerning sequences with linear growth associated to the mean values of multiplicative functions on a set of polynomial values,proving the density modulo 1 of the sequencem[∑((m2+1))(m2+1)(m≤n)]n.This result is but an illustration of the theme which is currently being developed in the PhD thesis of the second named author.
Analysis of the 802.11e Enhanced Distributed Channel Access Function
Inan, Inanc; Ayanoglu, Ender
2007-01-01
The IEEE 802.11e standard revises the Medium Access Control (MAC) layer of the former IEEE 802.11 standard for Quality-of-Service (QoS) provision in the Wireless Local Area Networks (WLANs). The Enhanced Distributed Channel Access (EDCA) function of 802.11e defines multiple Access Categories (AC) with AC-specific Contention Window (CW) sizes, Arbitration Interframe Space (AIFS) values, and Transmit Opportunity (TXOP) limits to support MAC-level QoS and prioritization. We propose an analytical model for the EDCA function which incorporates an accurate CW, AIFS, and TXOP differentiation at any traffic load. The proposed model is also shown to capture the effect of MAC layer buffer size on the performance. Analytical and simulation results are compared to demonstrate the accuracy of the proposed approach for varying traffic loads, EDCA parameters, and MAC layer buffer space.
Xu, Xiaonong; Lu, Dingwei; Xu, Xibin; Yu, Yang; Gu, Min
2017-09-01
The Halbach type hollow cylindrical permanent magnet array (HCPMA) is a volume compact and energy conserved field source, which have attracted intense interests in many practical applications. Here, using the complex variable integration method based on the Biot-Savart Law (including current distributions inside the body and on the surfaces of magnet), we derive analytical field solutions to an ideal multipole HCPMA in entire space including the interior of magnet. The analytic field expression inside the array material is used to construct an analytic demagnetization function, with which we can explain the origin of demagnetization phenomena in HCPMA by taking into account an ideal magnetic hysteresis loop with finite coercivity. These analytical field expressions and demagnetization functions provide deeper insight into the nature of such permanent magnet array systems and offer guidance in designing optimized array system.
Al-Rubaiee, A A; M., Marwah; Al-Douri, Y
2015-01-01
The Cherenkov light lateral distribution function (LDF) was simulated with the CORSIKA code, in the energy range (10^13-10^16) eV. This simulation was performed for conditions and configurations of the Tunka EAS Cherenkov array for two primary particles (p and Fe). Basing on the simulated results, many approximated functions are structured for two primary particles and different zenith angles. This allowed us to reconstruct the EAS events, which is, to determine the type and energy of the primary particles that produced showers from signal amplitudes of Cherenkov radiation which measured with Tunka Cherenkov array experiment. Comparison of the calculated LDF of Cherenkov radiation with that measured at the Tunka EAS array shows the ability for identifying of the primary particle that initiated the EAS cascades determining of its primary energy around the knee region of the cosmic ray spectrum.
A novel time dependent gamma evaluation function for dynamic 2D and 3D dose distributions.
Podesta, Mark; Persoon, Lucas C G G; Verhaegen, Frank
2014-10-21
Modern external beam radiotherapy requires detailed verification and quality assurance so that confidence can be placed on both the delivery of a single treatment fraction and on the consistency of delivery throughout the treatment course. To verify dose distributions, a comparison between prediction and measurement must be made. Comparisons between two dose distributions are commonly performed using a Gamma evaluation which is a calculation of two quantities on a pixel by pixel basis; the dose difference, and the distance to agreement. By providing acceptance criteria (e.g. 3%, 3 mm), the function will find the most appropriate match within its two degrees of freedom. For complex dynamic treatments such as IMRT or VMAT it is important to verify the dose delivery in a time dependent manner and so a gamma evaluation that includes a degree of freedom in the time domain via a third parameter, time to agreement, is presented here. A C++ (mex) based gamma function was created that could be run on either CPU and GPU computing platforms that would allow a degree of freedom in the time domain. Simple test cases were created in both 2D and 3D comprising of simple geometrical shapes with well-defined boundaries varying over time. Changes of varying magnitude in either space or time were introduced and repeated gamma analyses were performed varying the criteria. A clinical VMAT case was also included, artificial air bubbles of varying size were introduced to a patient geometry, along with shifts of varying magnitude in treatment time. For all test cases where errors in distance, dose or time were introduced, the time dependent gamma evaluation could accurately highlight the errors.The time dependent gamma function presented here allows time to be included as a degree of freedom in gamma evaluations. The function allows for 2D and 3D data sets which are varying over time to be compared using appropriate criteria without penalising minor offsets of subsequent radiation fields
Karvar, Serhan; Suda, Jo; Zhu, Lixin; Rockey, Don C
2014-10-15
Na(+)/H(+) exchanger regulatory factor 1 (NHERF1) is a multifunctional scaffolding protein that interacts with receptors and ion transporters in its PDZ domains and with the ezrin-radixin-moesin (ERM) family of proteins in its COOH terminus. The role of NHERF1 in hepatocyte function remains largely unknown. We examine the distribution and physiological significance of NHERF1 and multidrug resistance-associated protein 2 (Mrp-2) in hepatocytes. A WT radixin binding site mutant (F355R) and NHERF1 PDZ1 and PDZ2 domain adenoviral mutant constructs were tagged with yellow fluorescent protein and expressed in polarized hepatocytes to study localization and function of NHERF1. Cellular distribution of NHERF1 and radixin was visualized by fluorescence microscopy. A 5-chloromethylfluorescein diacetate (CMFDA) assay was used to characterize Mrp-2 function. Similar to Mrp-2, WT NHERF1 and the NHERF1 PDZ2 deletion mutant were localized to the canalicular membrane. In contrast, the radixin binding site mutant (F355R) and the NHERF1 PDZ1 deletion mutant, which interacts poorly with Mrp-2, were rarely associated with the canalicular membrane. Knockdown of NHERF1 led to dramatically impaired CMFDA secretory response. Use of CMFDA showed that the NHERF1 PDZ1 and F355R mutants were devoid of a secretory response, while WT NHERF1-infected cells exhibited increased secretion of glutathione-methylfluorescein. The data indicate that NHERF1 interacts with Mrp-2 via the PDZ1 domain of NHERF1 and, furthermore, that NHERF1 is essential for maintaining the localization and function of Mrp-2.
Brasil, L S; Juen, L; Batista, J D; Pavan, M G; Cabette, H S R
2014-10-01
We demonstrate that the distribution of the functional feeding groups of aquatic insects is related to hierarchical patch dynamics. Patches are sites with unique environmental and functional characteristics that are discontinuously distributed in time and space within a lotic system. This distribution predicts that the occurrence of species will be based predominantly on their environmental requirements. We sampled three streams within the same drainage basin in the Brazilian Cerrado savanna, focusing on waterfalls and associated habitats (upstream, downstream), representing different functional zones. We collected 2,636 specimens representing six functional feeding groups (FFGs): brushers, collector-gatherers, collector-filterers, shredders, predators, and scrapers. The frequency of occurrence of these groups varied significantly among environments. This variation appeared to be related to the distinct characteristics of the different habitat patches, which led us to infer that the hierarchical patch dynamics model can best explain the distribution of functional feeding groups in minor lotic environments, such as waterfalls.
Taut, Andreas; Wimmer-Schweingruber, Robert; Berger, Lars; Drews, Christian
2016-07-01
Interstellar pickup ions in the heliosphere exhibit a characteristic suprathermal Velocity Distribution Function (VDF). This is the result of their injection into the solar wind as a highly anisotropic torus distribution which is continuously modulated by pitch-angle scattering and cooling processes. As the impact of these processes on the pickup ion VDF depends on present and past solar wind conditions, the pickup ion VDF is not static but variable in shape and intensity. Using the good counting statistics of the Charge-Time-Of-Flight sensor onboard SOHO we were able to resolve a systematic variability of the He^+ VDF. On the one hand the intensity of freshly created pickup ions near the injection speed increases during magnetic field configurations in which the initial torus distribution lies inside the sensor's aperture. This complements our studies showing a persisting anisotropy of the He^+ VDF and introduces a limit for the efficiency of pitch-angle scattering. On the other hand we observe anomalous shapes of the He^+ VDF in the vicinity of stream interaction regions, where the VDF tends to be shifted towards higher speeds. These observations may be explained by a modified cooling behaviour in these regions. Furthermore we observe an enhancement of ions above the injection speed that were likely accelerated in compression regions. Here, we present our observations and discuss the implications on the processes named above.
Posterior cerebral artery Wada test: sodium amytal distribution and functional deficits
Energy Technology Data Exchange (ETDEWEB)
Urbach, H.; Schild, H.H. [Dept. of Radiology/Neuroradiology, Univ. of Bonn (Germany); Klemm, E.; Biersack, H.J. [Bonn Univ. (Germany). Klinik fuer Nuklearmedizin; Linke, D.B.; Behrends, K.; Schramm, J. [Dept. of Neurosurgery, Univ. of Bonn (Germany)
2001-04-01
Inadequate sodium amytal delivery to the posterior hippocampus during the intracarotid Wada test has led to development of selective tests. Our purpose was to show the sodium amytal distribution in the posterior cerebral artery (PCA) Wada test and to relate it to functional deficits during the test. We simultaneously injected 80 mg sodium amytal and 14.8 MBq {sup 99} {sup m}Tc-hexamethylpropyleneamine oxime (HMPAO) into the P2-segment of the PCA in 14 patients with temporal lobe epilepsy. To show the skull, we injected 116 MBq {sup 99} {sup m}Tc-HDP intravenously. Sodium amytal distribution was determined by high-resolution single-photon emission computed tomography (SPECT). In all patients, HMPAO was distributed throughout the parahippocampal gyrus and hippocampus; it was also seen in the occipital lobe in all cases and in the thalamus in 11. Eleven patients were awake and cooperative; one was slightly uncooperative due to speech comprehension difficulties and perseveration. All patients showed contralateral hemianopia during the test. Four patients had nominal dysphasia for 1-3 min. None developed motor deficits or had permanent neurological deficits. Neurological deficits due to inactivation of extrahippocampal areas thus do not grossly interfere with neuropsychological testing during the test. (orig.)
Detection of two power-law tails in the probability distribution functions of massive GMCs
Schneider, N; Girichidis, P; Rayner, T; Motte, F; Andre, P; Russeil, D; Abergel, A; Anderson, L; Arzoumanian, D; Benedettini, M; Csengeri, T; Didelon, P; Francesco, J D; Griffin, M; Hill, T; Klessen, R S; Ossenkopf, V; Pezzuto, S; Rivera-Ingraham, A; Spinoglio, L; Tremblin, P; Zavagno, A
2015-01-01
We report the novel detection of complex high-column density tails in the probability distribution functions (PDFs) for three high-mass star-forming regions (CepOB3, MonR2, NGC6334), obtained from dust emission observed with Herschel. The low column density range can be fit with a lognormal distribution. A first power-law tail starts above an extinction (Av) of ~6-14. It has a slope of alpha=1.3-2 for the rho~r^-alpha profile for an equivalent density distribution (spherical or cylindrical geometry), and is thus consistent with free-fall gravitational collapse. Above Av~40, 60, and 140, we detect an excess that can be fitted by a flatter power law tail with alpha>2. It correlates with the central regions of the cloud (ridges/hubs) of size ~1 pc and densities above 10^4 cm^-3. This excess may be caused by physical processes that slow down collapse and reduce the flow of mass towards higher densities. Possible are: 1. rotation, which introduces an angular momentum barrier, 2. increasing optical depth and weaker...
Extent of sensitivity of single photon production to parton distribution functions
Indian Academy of Sciences (India)
Somnath De
2014-06-01
We have studied the production of single isolated prompt photons in high-energy proton–proton collisions at the RHIC ($\\sqrt{s}$ = 200 GeV) and the LHC ($\\sqrt{s}$ = 7 TeV) energies within the framework of perturbative QCD upto next-to-leading order of strong coupling (). We have used five different parametrizations of parton distribution function (PDF) starting from the old CTEQ4M to the new CT10 distributions and compared our results with the recent single-prompt photon data from the PHENIX and the CMS Collaborations. The prompt photon cross-section is found to be described equally well by all the PDFs within the experimental errors at the RHIC and the LHC energies. The deviation in the single-prompt photon yield for different PDF sets is within ±20% when compared to CTEQ4M, indicating the upper bound of uncertainty in determining the gluon density. The diphoton measurement could be a potential candidate to constrain the gluon distribution inside the proton.
Observations of the He+ pickup ion torus velocity distribution function with SOHO/CELIAS/CTOF
Taut, Andreas; Berger, Lars; Bochsler, Peter; Drews, Christian; Klecker, Berndt; Wimmer-Schweingruber, Robert F.
2016-03-01
Interstellar PickUp Ions (PUIs) are created from neutrals coming from the interstellar medium that get ionized inside the heliosphere. Once ionized, the freshly created ions are injected into the magnetized solar wind plasma with a highly anisotropic torus-shaped Velocity Distribution Function (VDF). It has been commonly assumed that wave-particle interactions rapidly destroy this torus by isotropizing the distribution in one hemisphere of velocity space. However, recent observations of a He+ torus distribution using PLASTIC on STEREO showed that the assumption of a rapid isotropization is oversimplified. The aim of this work is to complement these studies. Using He+ data from the Charge Time-Of-Flight (CTOF) sensor of the Charge, ELement, and Isotope Analysis System (CELIAS) on-board the SOlar and Heliospheric Observatory (SOHO) and magnetic field data from the Magnetic Field Investigation (MFI) magnetometer of the WIND spacecraft, we derive the projected 1-D VDF of He+ for different magnetic field configurations. Depending on the magnetic field direction, the initial torus VDF lies inside CTOF's aperture or not. By comparing the VDFs derived under different magnetic field directions with each other we reveal an anisotropic signature of the He+ VDF.
Xiang, Xing; Wang, Ruicheng; Wang, Hongmei; Gong, Linfeng; Man, Baiying; Xu, Ying
2017-03-01
High abundance and widespread distribution of the archaeal phylum Bathyarchaeota in marine environment have been recognized recently, but knowledge about Bathyarchaeota in terrestrial settings and their correlation with environmental parameters is fairly limited. Here we reported the abundance of Bathyarchaeota members across different ecosystems and their correlation with environmental factors by constructing 16S rRNA clone libraries of peat from the Dajiuhu Peatland, coupling with bioinformatics analysis of 16S rRNA data available to date in NCBI database. In total, 1456 Bathyarchaeota sequences from 28 sites were subjected to UniFrac analysis based on phylogenetic distance and multivariate regression tree analysis of taxonomy. Both phylogenetic and taxon-based approaches showed that salinity, total organic carbon and temperature significantly influenced the distribution of Bathyarchaeota across different terrestrial habitats. By applying the ecological concept of ‘indicator species’, we identify 9 indicator groups among the 6 habitats with the most in the estuary sediments. Network analysis showed that members of Bathyarchaeota formed the “backbone” of archaeal community and often co-occurred with Methanomicrobia. These results suggest that Bathyarchaeota may play an important ecological role within archaeal communities via a potential symbiotic association with Methanomicrobia. Our results shed light on understanding of the biogeography, potential functions of Bathyarchaeota and environment conditions that influence Bathyarchaea distribution in terrestrial settings.
Interpretation of heavy rainfall spatial distribution in mountain watersheds by copula functions
Grossi, Giovanna; Balistrocchi, Matteo
2016-04-01
The spatial distribution of heavy rainfalls can strongly influence flood dynamics in mountain watersheds, depending on their geomorphologic features, namely orography, slope, land covers and soil types. Unfortunately, the direct observation of rainfall fields by meteorological radar is very difficult in this situation, so that interpolation of rain gauge observations or downscaling of meteorological predictions must be adopted to derive spatial rainfall distributions. To do so, various stochastic and physically based approaches are already available, even though the first one is the most familiar in hydrology. Indeed, Kriging interpolation procedures represent very popular techniques to face this problem by means of a stochastic approach. A certain number of restrictive assumptions and parameter uncertainties however affects Kriging. Many alternative formulations and additional procedures were therefore developed during the last decades. More recently, copula functions (Joe, 1997; Nelsen, 2006; Salvadori et al. 2007) were suggested to provide a more straightforward solution to carry out spatial interpolations of hydrologic variables (Bardossy & Pegram; 2009). Main advantages lie in the possibility of i) assessing the dependence structure relating to rainfall variables independently of marginal distributions, ii) expressing the association degree through rank correlation coefficients, iii) implementing marginal distributions and copula functions belonging to different models to develop complex joint distribution functions, iv) verifying the model reliability by effective statistical tests (Genest et al., 2009). A suitable case study to verify these potentialities is provided by the Taro River, a right-bank tributary of the Po River (northern Italy), whose contributing area amounts to about 2˙000 km2. The mountain catchment area is divided into two similar watersheds, so that spatial distribution is crucial in extreme flood event generation. A quite well diffused
Flavour dependence of the pion and kaon form factors and parton distribution functions
Hutauruk, Parada T P; Thomas, Anthony W
2016-01-01
The separate quark flavour contributions to the pion and kaon valence quark distribution functions are studied, along with the corresponding electromagnetic form factors in the space-like region. The calculations are made using the solution of the Bethe-Salpeter equation for the model of Nambu and Jona-Lasinio with proper-time regularization. Both the pion and kaon form factors and the valence quark distribution functions reproduce many of the features of the available empirical data. The larger mass if the strange quark naturally explains the empirical fact that the ratio $u_{K^+}(x)/u_{\\pi^+}(x)$ drops below unity at large $x$, with a value of approximately $M^2_u/M_s^2$ as $x \\to 1$. With regard to the elastic form factors we report a large flavour dependence, with the $u$-quark contribution to the kaon form factor being an order of magnitude smaller than that of the $s$-quark at large $Q^2$, which may be a sensitive measure of confinement effects in QCD. Surprisingly though, the total $K^+$ and $\\pi^+$ fo...
An improved global analysis of nuclear parton distribution functions including RHIC data
Eskola, K J; Salgado, C A
2008-01-01
We present an improved leading-order global DGLAP analysis of nuclear parton distribution functions (nPDFs), supplementing the traditionally used data from deep inelastic lepton-nucleus scattering and Drell-Yan dilepton production in proton-nucleus collisions, with inclusive high-$p_T$ hadron production data measured at RHIC in d+Au collisions. With the help of an extended definition of the $\\chi^2$ function, we now can more efficiently exploit the constraints the different data sets offer, for gluon shadowing in particular, and account for the overall data normalization uncertainties during the automated $\\chi^2$ minimization. The very good simultaneous fit to the nuclear hard process data used demonstrates the feasibility of a universal set of nPDFs, but also limitations become visible. The high-$p_T$ forward-rapidity hadron data of BRAHMS add a new crucial constraint into the analysis by offering a direct probe for the nuclear gluon distributions -- a sector in the nPDFs which has traditionally been very b...
Directory of Open Access Journals (Sweden)
Julianne de Castro Oliveira
2012-06-01
Full Text Available The objective of this study was to evaluate the effectiveness of fatigue life, Frechet, Gamma, Generalized Gamma, Generalized Logistic, Log-logistic, Nakagami, Beta, Burr, Dagum, Weibull and Hyperbolic distributions in describing diameter distribution in teak stands subjected to thinning at different ages. Data used in this study originated from 238 rectangular permanent plots 490 m2 in size, installed in stands of Tectona grandis L. f. in Mato Grosso state, Brazil. The plots were measured at ages 34, 43, 55, 68, 81, 82, 92, 104, 105, 120, 134 and 145 months on average. Thinning was done in two occasions: the first was systematic at age 81months, with a basal area intensity of 36%, while the second was selective at age 104 months on average and removed poorer trees, reducing basal area by 30%. Fittings were assessed by the Kolmogorov-Smirnov goodness-of-fit test. The Log-logistic (3P, Burr (3P, Hyperbolic (3P, Burr (4P, Weibull (3P, Hyperbolic (2P, Fatigue Life (3P and Nakagami functions provided more satisfactory values for the k-s test than the more commonly used Weibull function.
Protocol of Secure Key Distribution Using Hash Functions and Quantum Authenticated Channels (KDP-6DP
Directory of Open Access Journals (Sweden)
Mohammed M.A. Majeed
2010-01-01
Full Text Available Problem statement: In previous researches, we investigated the security of communication channels, which utilizes authentication, key distribution between two parties, error corrections and cost establishment. In the present work, we studied new concepts of Quantum Authentication (QA and sharing key according to previous points. Approach: This study presented a new protocol concept that allows the session and key generation on-site by independently applying a cascade of two hash functions on a random string of bits at the sender and receiver sides. This protocol however, required a reliable method of authentication. It employed an out-of-band authentication methodology based on quantum theory, which uses entangled pairs of photons. Results: The proposed quantum-authenticated channel is secure in the presence of eavesdropper who has access to both the classical and the quantum channels. Conclusion/Recommendations: The key distribution process using cascaded hash functions provides better security. The concepts presented by this protocol represent a valid approach to the communication security problem.
The Velocity Distribution Function of Galaxy Clusters as a Cosmological Probe
Ntampaka, M; Cisewski, J; Price, L C
2016-01-01
We present a new approach for quantifying the abundance of galaxy clusters and constraining cosmological parameters using dynamical measurements. In the standard method, galaxy line-of-sight (LOS) velocities, $v$, or velocity dispersions are used to infer cluster masses, $M$, in order to quantify the halo mass function (HMF), $dn(M)/d\\log(M)$, which is strongly affected by mass measurement errors. In our new method, the probability distribution of velocities for each cluster in the sample are summed to create a new statistic called the velocity distribution function (VDF), $dn(v)/dv$. The VDF can be measured more directly and precisely than the HMF and it can also be robustly predicted with cosmological simulations which capture the dynamics of subhalos or galaxies. We apply these two methods to mock cluster catalogs and forecast the bias and constraints on the matter density parameter $\\Omega_m$ and the amplitude of matter fluctuations $\\sigma_8$ in flat $\\Lambda$CDM cosmologies. For an example observation o...
Energy Technology Data Exchange (ETDEWEB)
Juang, K.W.; Lee, D.Y.; Hsiao, C.K. [National Taiwan Univ., Tapei (Taiwan, Province of China)
1998-10-01
Accurate delineation of contaminated soils is essential for risk assessment and remediation. The probability of pollutant concentrations lower than a cutoff value is more important than the best estimate of pollutant concentrations for unsampled locations in delineating contaminated soils. In this study, a new method, kriging with the cumulative distribution function (CDF) of order statistics (CDF kriging), is introduced and compared with indicator kriging. It is used to predict the probability that extractable concentrations of Zn will be less than a cut-off value for soils to be declared hazardous. The 0.1 M HCl-extractable Zn concentrations of topsoil of a paddy field having an area of about 2000 ha located in Taiwan are used. A comparison of the CDF of order statistics and indicator function transformation shows that the variance and the coefficient of variation (CV) of the CDF of order statistics transformed data are smaller than those of the indicator function transformed data. This suggests that the CDF of order statistics transformation possesses less variability than does the indicator function transformation. In addition, based on cross-validation, CDF kriging is found to reduce the mean squared errors of estimations by about 30% and to reduce the mean kriging variances by about 26% compared with indicator kriging.
Distributed analysis functional testing using GangaRobot in the ATLAS experiment
Legger, F; The ATLAS collaboration
2011-01-01
Automated distributed analysis tests are necessary to ensure smooth operations of the ATLAS grid resources. The HammerCloud framework allows for easy definition, submission and monitoring of grid test applications. Both functional and stress test applications can be defined in HammerCloud. Stress tests are large-scale tests meant to verify the behaviour of sites under heavy load. Functional tests are light user applications running at each site with high frequency, to ensure that the site functionalities are available at all times. Success or failure rates of these tests jobs are individually monitored. Test definitions and results are stored in a database and made available to users and site administrators through a web interface. In this work we present the recent developments of the GangaRobot framework. GangaRobot monitors the outcome of functional tests, creates a blacklist of sites failing the tests, and exports the results tothe ATLAS Site Status Board (SSB) and to the Service Availability Monitor (SAM...
Chashei, I. V.; Fahr, H. J.
Charge-exchange processes between interstellar H-/O-atoms and protons of the bulk of the interstellar plasma flow downstream of the outer bowshock in the heliospheric interface induce secondary ions leading to non-relaxated velocity distribution functions. The relaxation of these freshly induced ions towards an equilibrium distribution occurs due to Coulomb interactions and wave-particle interactions with the background turbulence. Since Coulomb interactions are of low relevance, we study here in detail the effect of wave-particle interactions. To find the turbulence levels in the interface we consider the MHD-wave transformation at the outer shock surface between the interface and the local interstellar plasma. The turbulence in the outer interface region is shown to be dominated by incompressible Alfvén waves both for cases of quasiparallel and quasiperpendicular shocks. Also we show that waves propagating towards the shock are more intensive than those propagating away from it. The level of Alfvén turbulence in the interface is estimated using the recent data on local interstellar turbulence deduced from observations of interstellar scintillations of distant radiosources. Two proton relaxation processes are considered: quasilinear resonant interactions with Alfvén waves and non-linear self-induced wave-particle scattering. The corresponding diffusion coefficients are estimated, and typical time periods for protons and oxygen ions relaxation are shown to be of the same order of magnitude as H-/O-atoms passage time over the extent of the interface. This indicates that perturbed ion distribution functions must be expected there.
Directory of Open Access Journals (Sweden)
Tun-Wei Hsu
Full Text Available Hepatic encephalopathy (HE is a complex neuropsychiatric syndrome and a major complication of liver cirrhosis. Dysmetabolism of the brain, related to elevated ammonia levels, interferes with intercortical connectivity and cognitive function. For evaluation of network efficiency, a 'small-world' network model can quantify the effectiveness of information transfer within brain networks. This study aimed to use small-world topology to investigate abnormalities of neuronal connectivity among widely distributed brain regions in patients with liver cirrhosis using resting-state functional magnetic resonance imaging (rs-fMRI. Seventeen cirrhotic patients without HE, 9 with minimal HE, 9 with overt HE, and 35 healthy controls were compared. The interregional correlation matrix was obtained by averaging the rs-fMRI time series over all voxels in each of the 90 regions using the automated anatomical labeling model. Cost and correlation threshold values were then applied to construct the functional brain network. The absolute and relative network efficiencies were calculated; quantifying distinct aspects of the local and global topological network organization. Correlations between network topology parameters, ammonia levels, and the severity of HE were determined using linear regression and ANOVA. The local and global topological efficiencies of the functional connectivity network were significantly disrupted in HE patients; showing abnormal small-world properties. Alterations in regional characteristics, including nodal efficiency and nodal strength, occurred predominantly in the association, primary, and limbic/paralimbic regions. The degree of network organization disruption depended on the severity of HE. Ammonia levels were also significantly associated with the alterations in local network properties. Results indicated that alterations in the rs-fMRI network topology of the brain were associated with HE grade; and that focal or diffuse lesions
Functionality and Performance Visualization of the Distributed High Quality Volume Renderer (HVR)
Shaheen, Sara
2012-07-01
Volume rendering systems are designed to provide means to enable scientists and a variety of experts to interactively explore volume data through 3D views of the volume. However, volume rendering techniques are computationally intensive tasks. Moreover, parallel distributed volume rendering systems and multi-threading architectures were suggested as natural solutions to provide an acceptable volume rendering performance for very large volume data sizes, such as Electron Microscopy data (EM). This in turn adds another level of complexity when developing and manipulating volume rendering systems. Given that distributed parallel volume rendering systems are among the most complex systems to develop, trace and debug, it is obvious that traditional debugging tools do not provide enough support. As a consequence, there is a great demand to provide tools that are able to facilitate the manipulation of such systems. This can be achieved by utilizing the power of compute graphics in designing visual representations that reflect how the system works and that visualize the current performance state of the system.The work presented is categorized within the field of software Visualization, where Visualization is used to serve visualizing and understanding various software. In this thesis, a number of visual representations that reflect a number of functionality and performance aspects of the distributed HVR, a high quality volume renderer system that uses various techniques to visualize large volume sizes interactively. This work is provided to visualize different stages of the parallel volume rendering pipeline of HVR. This is along with means of performance analysis through a number of flexible and dynamic visualizations that reflect the current state of the system and enables manipulation of them at runtime. Those visualization are aimed to facilitate debugging, understanding and analyzing the distributed HVR.
Sun, Shan
2013-05-01
Anammox (anaerobic ammonium oxidation) process is a one-step conversion of ammonia into nitrogen gas with nitrite as an electron acceptor. It has been developed as a sustainable technology for ammonia removal from wastewater in the last decade. For wastewater treatment, anammox biomass was widely developed as microbial aggregate where the conditions for enrichment of anammox community must be delicately controlled and growth of other bacteria especially NOB should be suppressed to enhance nitrogen removal efficiency. Little is known about the distribution of microbial aggregates in anammox process. Thus the objective of our study was to assess whether segregation of biomass occurs in granular anammox system. In this study, a laboratory-scale sequential batch reactor (SBR) was successfully operated for a period of 80 days with granular anammox biomass. Temporal and spatial distribution of microbial aggregates was studied by particle characterization system and the distribution of functional microbial communities was studied with qPCR and 16s rRNA amplicon pyrosequencing. Our study revealed the spatial and temporal distribution of biomass aggregates based on their sizes and density. Granules (>200 μm) preferentially accumulated in the bottom of the reactor while floccules (30-200 μm) were relatively rich at the top layer. The average density of aggregate was higher at the bottom than the density of those at the top layer. Degranulation caused by lack of hydrodynamic shear force in the top layer was considered responsible for this phenomenon. NOB was relatively rich in the top layer while percentage of anammox population was higher at the bottom, and anammox bacteria population gradually increased over a period of time. NOB growth was supposed to be associated with the increase of floccules based on the concurrent occurrence. Thus, segregation of biomass can be utilized to develop an effective strategy to enrich anammox and wash out NOB by shortening the settling
Pérez-Hoyos, Santiago; Sanz-Requena, José Francisco; Sánchez-Lavega, Agustín; Irwin, Patrick G. J.; Smith, Andrew
2016-10-01
The phase function describes the way particles scatter the incoming radiation. This is a fundamental piece of knowledge in order to understand how a planetary atmosphere scatters sunlight and so it has a profound influence in the retrieved atmospheric properties such as cloud height, particle density distribution and radiative forcing by aerosols. In this work we analyze data from the Imaging Science Subsystem (ISS) instrument onboard Cassini spacecraft to determine the particle phase function at blue (451 nm) and near infrared wavelengths (727-890 nm) of particles in the upper troposphere, where most of the incoming visible sunlight is scattered. In order to do so, we use observations taken in later 2010 and 2011 covering a broad range of phase angles from ∼10° to ∼160° in the blue (BL1) and near infrared filters associated with intermediate and deep methane absorption bands (MT2, CB2, MT3). Particles at all latitudes are found to be strongly forward scattering. The equatorial particles are in good agreement with laboratory measurements of 10 μm ammonia ice crystals, while mid- and sub-polar latitude particles may be similar to the equatorial particles, but they may also be consistent with 1 μm ellipsoids with moderate aspect ratios. Uncertainties due to limited phase coverage and parameter degeneracy prevent strong constraints of the particle shapes and sizes at these locations. Results for the particle phase function are also used to describe the spatial distribution of tropospheric particles both vertically and latitudinally in the Northern hemisphere.
Distribution of cerebral microbleeds determines their association with impaired kidney function.
Song, Tae-Jin; Kim, Jinkwon; Lee, Hye Sun; Nam, Chung Mo; Nam, Hyo Suk; Kim, Young Dae; Heo, Ji Hoe
2014-07-01
Cerebral microbleeds (CMBs) are associated with various pathologies of the cerebral small vessels according to their distribution (i.e., cerebral amyloid angiopathy or hypertensive angiopathy). We investigated the association between CMB location and kidney function in acute ischemic stroke patients. We enrolled 1669 consecutive patients with acute ischemic stroke who underwent gradient-recalled echo brain magnetic resonance imaging. Kidney function was determined using the estimated glomerular filtration rate (eGFR). CMBs were classified into strictly lobar, strictly nonlobar (i.e., only deep or infratentorial), and a combination of both lobar and nonlobar. Multinomial logistic regression analyses were used to determine the factors associated with the existence of CMBs according to their location. The patients were aged 66±12 years (mean±standard deviation), and 61.9% (1033/1669) of them were male. CMBs were found in 27.0% (452/1669) of the patients. The stroke subtypes of small-artery occlusion and cardioembolism occurred more frequently in those with strictly nonlobar CMBs (10.8%) and strictly lobar CMBs (48.8%), respectively. The mean eGFR was lower in the strictly nonlobar CMBs group (72±28 mL/min/1.73 m(2)) and the both lobar and nonlobar CMBs group (72±25 mL/min/1.73 m(2)) than in the no-CMBs group (86±29 mL/min/1.73 m(2)). Multivariate multinomial logistic regression revealed that eGFR CMBs (odds ratio=2.63, p=0.001). Impaired kidney function is associated with strictly nonlobar CMBs. Our findings indicate that the distribution of CMBs should be considered when evaluating their relationships or prognoses.
2016-01-01
Statistical downscaling is used to improve the knowledge of spatial distributions from broad–scale to fine–scale maps with higher potential for conservation planning. We assessed the effectiveness of downscaling in two commonly used species distribution models: Maximum Entropy (MaxEnt) and the Favourability Function (FF). We used atlas data (10 x 10 km) of the fire salamander Salamandra salamandra distribution in southern Spain to derive models at a 1 x 1 km resolution. Downscaled models were...
Wang, You-qi; Bai, Yi-ru; Wang, Jian-yu
2016-02-15
Surface soil samples (0-20 cm) from eight different functional areas in Yinchuan city were collected. There were 10 samples respectively in each functional area. The urban soil heavy metals (Zn, Cd, Pb, Mn, Cu and Cr) pollution characteristics and sources in eight different functional areas were evaluated by mathematical statistics and geostatistical analysis method. Meanwhile, the spatial distributions of heavy metals based on the geography information system (GIS) were plotted. The average values of total Zn, Cd, Pb, Mn, Cu and Cr were 74.87, 0.15, 29.02, 553.55, 40.37 and 80.79 mg x kg(-1), respectively. The results showed that the average value of soil heavy metals was higher than the soil background value of Ningxia, which indicated accumulation of the heavy metals in urban soil. The single factor pollution index of soil heavy metals was in the sequence of Cu > Pb > Zn > Cr > Cd > Mn. The average values of total Zn, Cd, Pb and Cr were higher in north east, south west and central city, while the average values of Mn and Cu were higher in north east and central city. There was moderate pollution in road and industrial area of Yinchuan, while the other functional areas showed slight pollution according to Nemoro synthesis index. The pollution degree of different functional areas was as follows: road > industrial area > business district > medical treatment area > residential area > public park > development zone > science and education area. The results indicated that the soil heavy metal pollution condition in Yinchuan City has been affected by human activities with the development of economy.
Lu, Dan; Zhang, Guannan; Webster, Clayton; Barbier, Charlotte
2016-12-01
In this work, we develop an improved multilevel Monte Carlo (MLMC) method for estimating cumulative distribution functions (CDFs) of a quantity of interest, coming from numerical approximation of large-scale stochastic subsurface simulations. Compared with Monte Carlo (MC) methods, that require a significantly large number of high-fidelity model executions to achieve a prescribed accuracy when computing statistical expectations, MLMC methods were originally proposed to significantly reduce the computational cost with the use of multifidelity approximations. The improved performance of the MLMC methods depends strongly on the decay of the variance of the integrand as the level increases. However, the main challenge in estimating CDFs is that the integrand is a discontinuous indicator function whose variance decays slowly. To address this difficult task, we approximate the integrand using a smoothing function that accelerates the decay of the variance. In addition, we design a novel a posteriori optimization strategy to calibrate the smoothing function, so as to balance the computational gain and the approximation error. The combined proposed techniques are integrated into a very general and practical algorithm that can be applied to a wide range of subsurface problems for high-dimensional uncertainty quantification, such as a fine-grid oil reservoir model considered in this effort. The numerical results reveal that with the use of the calibrated smoothing function, the improved MLMC technique significantly reduces the computational complexity compared to the standard MC approach. Finally, we discuss several factors that affect the performance of the MLMC method and provide guidance for effective and efficient usage in practice.
Sonnino, Giorgio; Peeters, Philippe; Sonnino, Alberto; Nardone, Pasquale; Steinbrecher, György
2015-01-01
In previous works, we derived stationary density distribution functions (DDF) where the local equilibrium is determined by imposing the maximum entropy (MaxEnt) principle, under the scale invariance restrictions, and the minimum entropy production theorem. In this paper we demonstrate that it is possible to reobtain these DDF solely from the MaxEnt principle subject to suitable scale invariant restrictions in all the variables. For the sake of concreteness, we analyse the example of ohmic, fully ionized, tokamak-plasmas, in the weak-collisional transport regime. In this case we show that it is possible to reinterpret the stationary distribution function in terms of the Prigogine distribution function where the logarithm of the DDF is directly linked to the entropy production of the plasma. This leads to the suggestive idea that also the stationary neoclassical distribution functions, for magnetically confined plasmas in the collisional transport regimes, may be derived solely by the MaxEnt principle.
St Pierre, L.; Burchsted, D.; Warren, D.
2015-12-01
Large wood provides critical ecosystem services such as fish habitat, temperature regulation and bank stabilization. In the northeastern U.S., the distribution of large wood is documented; however, there is little understanding of the movement, longevity and geomorphic function. This research examines the hypothesis that tree species control the persistence and geomorphic function of instream wood in the Appalachian region of the northeastern U.S. To do this, we assessed size, location, and species of logs in New Hampshire rivers, including locations in the White Mountain National Forest (WMNF) where these data were collected ten years ago. We expanded the previous dataset to include assessment of geomorphic function, including creation of diversion channels, pool formation, and sediment storage, among others. We also added new sites in the WMNF and sites on a large rural river in southwestern NH to increase the range of geomorphic variables to now include: confined and unconfined channels; 1st to 4th order streams; low to high gradient; meandering, multithreaded, and straight channels; and land use such as historic logging, modern agriculture, and post-agricultural abandonment. At each study site, we located all large logs (>10cm diameter, > 1m length) and log jams (>3 accumulated logs that provide a geomorphic function) along 100m-700m reaches. We marked each identified log with a numbered tag and recorded species, diameter, length, orientation, GPS location, tag number, and photographs. We assessed function and accumulation, decay, stability, and source classes for each log. Along each reach we measured riparian forest composition and structure and channel width. Preliminary analysis suggests that tree species significantly affects the function of logs: yellow birch and American sycamore are highly represented. Additionally, geomorphic setting also plays a primary role, where unconfined reaches have large logs that provide important functions; those functions
Velders, G.J.M.; Feil, D.
1989-01-01
Quantum-chemical density-functional theory (DFT) calculations, using the local-density approximation (LDA), have been performed for hydrogen-bounded silicon clusters to determine the electron density distribution of the Si-Si bond. The density distribution in the bonding region is compared with calc
Abdelrahman, Mahmoud A. E.; Sohaly, M. A.
2017-08-01
This work deals with the construction of the exact traveling wave solutions for the nonlinear Schrödinger equation by the new Riccati-Bernoulli Sub-ODE method. Additionally, we apply this method in order to study the random solutions by finding the probability distribution function when the coefficient in our problem is a random variable. The travelling wave solutions of many equations physically or mathematically are expressed by hyperbolic functions, trigonometric functions and rational functions. We discuss our method in the deterministic case and also in a random case, by studying the beta distribution for the random input.
Distribution function approach to redshift space distortions: N-body simulations
Okumura, Teppei; McDonald, Patrick; Desjacques, Vincent
2011-01-01
Measurement of redshift-space distortions (RSD) offers an attractive method to directly probe the cosmic growth history of density perturbations. A distribution function approach where RSD can be written as a sum over density weighted velocity moment correlators has recently been developed. We use Nbody simulations to investigate the individual contributions and convergence of this expansion for dark matter. If the series is expanded as a function of powers of mu, cosine of the angle between the Fourier mode and line of sight, there are a finite number of terms contributing at each order. We present these terms and investigate their contribution to the total as a function of wavevector k. For mu^2 the correlation between density and momentum dominates on large scales. Higher order corrections, which act as a Finger-of-God (FoG) term, contribute 1% at k~0.015h/Mpc, 10% at k~0.05h/Mpc at z=0, while for k>0.15h/Mpc they dominate and make the total negative. These higher order terms are dominated by density-energ...
Production of a double-humped ion velocity distribution function in a single-ended Q-machine
DEFF Research Database (Denmark)
Andersen, S.A.; Jensen, Vagn Orla; Michelsen, Poul
1970-01-01
An experimental method of producing a double-humped velocity distribution function for the ions in a Q-machine is described. The method is based on charge exchange processes between neutral ceasium and the ions in a ceasium plasma.......An experimental method of producing a double-humped velocity distribution function for the ions in a Q-machine is described. The method is based on charge exchange processes between neutral ceasium and the ions in a ceasium plasma....
Misakian, M.; Mumma, M. J.; Faris, J. F.
1975-01-01
Dissociative excitation of CO2 by electron impact was studied using the methods of translational spectroscopy and angular distribution analysis. Earlier time of flight studies revealed two overlapping spectra, the slower of which was attributed to metastable CO(a3 pi) fragments. The fast peak is the focus of this study. Threshold energy, angular distribution, and improve time of flight measurements indicate that the fast peak actually consists of five overlapping features. The slowest of the five features is found to consist of metastable 0(5S) produced by predissociation of a sigma u + state of CO2 into 0(5S) + CO(a3 pi). Oxygen Rydberg fragments originating directly from a different sigma u + state are believed to make up the next fastest feature. Mechanisms for producing the three remaining features are discussed.
Becker, Peter A.; Das, Santabrata; Le, Truong
2011-12-01
The acceleration of relativistic particles in a viscous accretion disk containing a standing shock is investigated as a possible explanation for the energetic outflows observed around radio-loud black holes. The energy/space distribution of the accelerated particles is computed by solving a transport equation that includes the effects of first-order Fermi acceleration, bulk advection, spatial diffusion, and particle escape. The velocity profile of the accreting gas is described using a model for shocked viscous disks recently developed by the authors, and the corresponding Green's function distribution for the accelerated particles in the disk and the outflow is obtained using a classical method based on eigenfunction analysis. The accretion-driven, diffusive shock acceleration scenario explored here is conceptually similar to the standard model for the acceleration of cosmic rays at supernova-driven shocks. However, in the disk application, the distribution of the accelerated particles is much harder than would be expected for a plane-parallel shock with the same compression ratio. Hence the disk environment plays a key role in enhancing the efficiency of the shock acceleration process. The presence of the shock helps to stabilize the disk by reducing the Bernoulli parameter, while channeling the excess binding energy into the escaping relativistic particles. In applications to M87 and Sgr A*, we find that the kinetic power in the jet is {\\sim}0.01\\,\\dot{M} c^2, and the outflowing relativistic particles have a mean energy ~300 times larger than that of the thermal gas in the disk at the shock radius. Our results suggest that a standing shock may be an essential ingredient in accretion onto underfed black holes, helping to resolve the long-standing problem of the stability of advection-dominated accretion disks.
Burkhart, Blakesley; Lee, Min-Young; Murray, Claire E.; Stanimirović, Snezana
2015-10-01
The shape of the probability distribution function (PDF) of molecular clouds is an important ingredient for modern theories of star formation and turbulence. Recently, several studies have pointed out observational difficulties with constraining the low column density (i.e., {A}V\\lt 1) PDF using dust tracers. In order to constrain the shape and properties of the low column density PDF, we investigate the PDF of multiphase atomic gas in the Perseus molecular cloud using opacity-corrected GALFA-HI data and compare the PDF shape and properties to the total gas PDF and the N(H2) PDF. We find that the shape of the PDF in the atomic medium of Perseus is well described by a lognormal distribution and not by a power-law or bimodal distribution. The peak of the atomic gas PDF in and around Perseus lies at the HI-H2 transition column density for this cloud, past which the N(H2) PDF takes on a power-law form. We find that the PDF of the atomic gas is narrow, and at column densities larger than the HI-H2 transition, the HI rapidly depletes, suggesting that the HI PDF may be used to find the HI-H2 transition column density. We also calculate the sonic Mach number of the atomic gas by using HI absorption line data, which yield a median value of Ms = 4.0 for the CNM, while the HI emission PDF, which traces both the WNM and CNM, has a width more consistent with transonic turbulence.
Taut, A.; Drews, C.; Berger, L.; Wimmer-Schweingruber, R. F.
2015-12-01
The 1D Velocity Distribution Function (VDF) of He+ pickup ions shows two distinct populations that reflect the sources of these ions. The highly suprathermal population is the result of the ionization and pickup of almost resting interstellar neutrals that are injected into the solar wind as a highly anisotropic torus distribution. The nearly thermalized population is centered around the solar wind bulk speed and is mainly attributed to inner-source pickup ions that originate in the inner heliosphere. It is generally believed that the initial torus distribution of interstellar pickup ions is rapidly isotropized by resonant wave-particle interactions, but recent observations by Drews et al. (2015) of a torus-like VDF strongly limit this isotropization. This in turn means that more observational data is needed to further characterize the kinetic behavior of pickup ions. In this study we use data from the Charge-Time-Of-Flight sensor on-board SOHO. As this sensor offers unrivaled counting statistics for He+ together with a sufficient mass-per-charge resolution it is well-suited for investigating the He+ VDF on comparatively short timescales. We combine this data with the high resolution magnetic field data from WIND via an extrapolation to the location of SOHO. With this combination of instruments we investigate the He+ VDF for time periods of different solar wind speeds, magnetic field directions, and wave power. We find a systematic trend of the short-term He+ VDF with these parameters. Especially by varying the considered magnetic field directions we observe a 1D projection of the anisotropic torus-like VDF. In addition, we investigate stream interaction regions and coronal mass ejections. In the latter we observe an excess of inner-source He+ that is accompanied by a significant increase of heavy pickup ion count rates. This may be linked to the as yet ill understood production mechanism of inner-source pickup ions.
Transverse-momentum dependent parton distribution functions beyond leading twist in quark models
Lorcé, C; Schweitzer, P
2014-01-01
Higher-twist transverse momentum dependent parton distribution functions (TMDs) are a valuable probe of the quark-gluon dynamics in the nucleon, and play a vital role for the explanation of sizable azimuthal asymmetries in hadron production from unpolarized and polarized deep-inelastic lepton-nucleon scattering observed in experiments at CERN, DESY and Jefferson Lab. The associated observables are challenging to interpret, and still await a complete theoretical explanation, which makes guidance from models valuable. In this work we establish the formalism to describe unpolarized higher-twist TMDs in the light-front framework based on a Fock-space expansion of the nucleon state in terms of free on-shell parton states. We derive general expressions and present numerical results in a practical realization of this picture provided by the light-front constituent quark model. We review several other popular quark model approaches including free quark ensemble, bag, spectator and chiral quark-soliton model.
Real-Time Performance Analysis of Infrastructure-based IEEE 802.11 Distributed Coordination Function
Xia, Feng; Wang, Linqiang; Hao, Ruonan
2012-01-01
With the increasing popularity of wireless networks, wireless local area networks (WLANs) have attracted significant research interest, which play a critical role in providing anywhere and anytime connectivity. For WLANs the IEEE 802.11 standard is the most mature technology and has been widely adopted for wireless networks. This paper analyzes real-time performance of the IEEE 802.11 standard that adopts the MAC protocol of Distributed Coordination Function (DCF) operating in infrastructure mode. Extensive simulations have been done to examine how the network performance in terms of realtime metrics including effective data rate, latency and packet loss rate will be impacted by some critical parameters (e.g. CWmin and packet payload). The results are presented and analyzed. The analysis of simulation results can provide support for parameter configuration and optimization of WLANs for realtime applications.
Nonequilibrium distribution functions of nucleons in relativistic nucleus-nucleus collisions
Anchishkin, D; Cleymans, J; 10.5488/CMP.16.13201
2013-01-01
The collision smearing of the nucleon momenta about their initial values during relativistic nucleus-nucleus collisions is investigated. To a certain degree, our model belongs to the transport type, and we investigate the evolution of the nucleon system created at a nucleus-nucleus collision. However, we parameterize this development by the number of collisions of every particle during evolution rather than by the time variable. It is assumed that the group of nucleons which leave the system after the same number of collisions can be joined in a particular statistical ensemble. The nucleon nonequilibrium distribution functions, which depend on a certain number of collisions of a nucleon before freeze-out, are derived.