Model of bidirectional reflectance distribution function for metallic materials
International Nuclear Information System (INIS)
Wang Kai; Zhu Jing-Ping; Liu Hong; Hou Xun
2016-01-01
Based on the three-component assumption that the reflection is divided into specular reflection, directional diffuse reflection, and ideal diffuse reflection, a bidirectional reflectance distribution function (BRDF) model of metallic materials is presented. Compared with the two-component assumption that the reflection is composed of specular reflection and diffuse reflection, the three-component assumption divides the diffuse reflection into directional diffuse and ideal diffuse reflection. This model effectively resolves the problem that constant diffuse reflection leads to considerable error for metallic materials. Simulation and measurement results validate that this three-component BRDF model can improve the modeling accuracy significantly and describe the reflection properties in the hemisphere space precisely for the metallic materials. (paper)
Model of bidirectional reflectance distribution function for metallic materials
Wang, Kai; Zhu, Jing-Ping; Liu, Hong; Hou, Xun
2016-09-01
Based on the three-component assumption that the reflection is divided into specular reflection, directional diffuse reflection, and ideal diffuse reflection, a bidirectional reflectance distribution function (BRDF) model of metallic materials is presented. Compared with the two-component assumption that the reflection is composed of specular reflection and diffuse reflection, the three-component assumption divides the diffuse reflection into directional diffuse and ideal diffuse reflection. This model effectively resolves the problem that constant diffuse reflection leads to considerable error for metallic materials. Simulation and measurement results validate that this three-component BRDF model can improve the modeling accuracy significantly and describe the reflection properties in the hemisphere space precisely for the metallic materials.
Optical properties (bidirectional reflectance distribution function) of shot fabric
Lu, Rong; Koenderink, Jan J.; Kappers, Astrid M L
2000-01-01
To study the optical properties of materials, one needs a complete set of the angular distribution functions of surface scattering from the materials. Here we present a convenient method for collecting a large set of bidirectional reflectance distribution function (BRDF) samples in the hemispherical
A new setup to measure bidirectional reflectance distribution functions
Roosjen, P.P.J.; Clevers, J.G.P.W.; Bartholomeus, H.
2012-01-01
The Plant Facility, a new laboratory goniometer system, built by the Wageningen University has been tested in order to take bidirectional reflectance distribution function (BRDF) measurements. An ASD FieldSpec 3 spectroradiometer mounted on an industrial robot arm is able to measure small targets
Belcour, Laurent; Pacanowski, Romain; Delahaie, Marion; Laville-Geay, Aude; Eupherte, Laure
2014-12-01
We compare the performance of various analytical retroreflecting bidirectional reflectance distribution function (BRDF) models to assess how they reproduce accurately measured data of retroreflecting materials. We introduce a new parametrization, the back vector parametrization, to analyze retroreflecting data, and we show that this parametrization better preserves the isotropy of data. Furthermore, we update existing BRDF models to improve the representation of retroreflective data.
Comparison of the bidirectional reflectance distribution function of various surfaces
International Nuclear Information System (INIS)
Fernandez, R.; Seasholtz, R.G.; Oberle, L.G.; Kadambi, J.R.
1989-01-01
This paper describes the development and use of a system to measure the bidirectional reflectance distribution function (BRDF) of various surfaces. The BRDF measurements are to be used in the analysis and design of optical measurement systems such as laser anemometers. An Ar-ion laser (514 nm) was the light source. Preliminary results are presented for eight samples: two glossy black paints, two flat black paints, black glass, sand-blasted Al, unworked Al, and a white paint. A BaSO4 white reflectance standard was used as the reference sample throughout the tests. 8 refs
Ferrero, Alejandro; Rabal, Ana María; Campos, Joaquín; Pons, Alicia; Hernanz, María Luisa
2012-12-20
A study on the variation of the spectral bidirectional reflectance distribution function (BRDF) of four diffuse reflectance standards (matte ceramic, BaSO(4), Spectralon, and white Russian opal glass) is accomplished through this work. Spectral BRDF measurements were carried out and, using principal components analysis, its spectral and geometrical variation respect to a reference geometry was assessed from the experimental data. Several descriptors were defined in order to compare the spectral BRDF variation of the four materials.
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.
Nishino, Ko; Lombardi, Stephen
2011-01-01
We introduce a novel parametric bidirectional reflectance distribution function (BRDF) model that can accurately encode a wide variety of real-world isotropic BRDFs with a small number of parameters. The key observation we make is that a BRDF may be viewed as a statistical distribution on a unit hemisphere. We derive a novel directional statistics distribution, which we refer to as the hemispherical exponential power distribution, and model real-world isotropic BRDFs as mixtures of it. We derive a canonical probabilistic method for estimating the parameters, including the number of components, of this novel directional statistics BRDF model. We show that the model captures the full spectrum of real-world isotropic BRDFs with high accuracy, but a small footprint. We also demonstrate the advantages of the novel BRDF model by showing its use for reflection component separation and for exploring the space of isotropic BRDFs.
Optical properties (bidirectional reflectance distribution function) of shot fabric.
Lu, R; Koenderink, J J; Kappers, A M
2000-11-01
To study the optical properties of materials, one needs a complete set of the angular distribution functions of surface scattering from the materials. Here we present a convenient method for collecting a large set of bidirectional reflectance distribution function (BRDF) samples in the hemispherical scattering space. Material samples are wrapped around a right-circular cylinder and irradiated by a parallel light source, and the scattered radiance is collected by a digital camera. We tilted the cylinder around its center to collect the BRDF samples outside the plane of incidence. This method can be used with materials that have isotropic and anisotropic scattering properties. We demonstrate this method in a detailed investigation of shot fabrics. The warps and the fillings of shot fabrics are dyed different colors so that the fabric appears to change color at different viewing angles. These color-changing characteristics are found to be related to the physical and geometrical structure of shot fabric. Our study reveals that the color-changing property of shot fabrics is due mainly to an occlusion effect.
Lee, Yu; Yu, Chanki; Lee, Sang Wook
2018-01-10
We present a sequential fitting-and-separating algorithm for surface reflectance components that separates individual dominant reflectance components and simultaneously estimates the corresponding bidirectional reflectance distribution function (BRDF) parameters from the separated reflectance values. We tackle the estimation of a Lafortune BRDF model, which combines a nonLambertian diffuse reflection and multiple specular reflectance components with a different specular lobe. Our proposed method infers the appropriate number of BRDF lobes and their parameters by separating and estimating each of the reflectance components using an interval analysis-based branch-and-bound method in conjunction with iterative K-ordered scale estimation. The focus of this paper is the estimation of the Lafortune BRDF model. Nevertheless, our proposed method can be applied to other analytical BRDF models such as the Cook-Torrance and Ward models. Experiments were carried out to validate the proposed method using isotropic materials from the Mitsubishi Electric Research Laboratories-Massachusetts Institute of Technology (MERL-MIT) BRDF database, and the results show that our method is superior to a conventional minimization algorithm.
Laboratory-based bidirectional reflectance distribution functions of radiometric tarps
International Nuclear Information System (INIS)
Georgiev, Georgi T.; Butler, James J.
2008-01-01
Laboratory-based bidirectional reflectance distribution functions (BRDFs) of radiometric tarp samples used in the vicarious calibration of Earth remote sensing satellite instruments are presented in this paper. The results illustrate the BRDF dependence on the orientation of the tarps' weft and warp threads. The study was performed using the GSFC scatterometer at incident zenith angles of 0 deg., 10 deg., and 30 deg.; scatter zenith angles from 0 deg. to 60 deg.; and scatter azimuth angles of 0 deg., 45 deg., 90 deg., 135 deg., and 180 deg.. The wavelengths were 485 nm, 550 nm, 633 nm, and 800 nm. The tarp's weft and warp dependence on BRDF is well defined at all measurement geometries and wavelengths. The BRDF difference can be as high as 8% at 0 deg. incident angle and 12% at 30 deg. incident angle. The fitted BRDF data show a very small discrepancy from the measured ones. New data on the forward and backscatter properties of radiometric tarps are reported. The backward scatter is well pronounced for the white samples. The black sample has well-pronounced forward scatter. The provided BRDF characterization of radiometric tarps is an excellent reference for anyone interested in using tarps for radiometric calibrations. The results are NIST traceable
Laboratory-based bidirectional reflectance distribution functions of radiometric tarps.
Georgiev, Georgi T; Butler, James J
2008-06-20
Laboratory-based bidirectional reflectance distribution functions (BRDFs) of radiometric tarp samples used in the vicarious calibration of Earth remote sensing satellite instruments are presented in this paper. The results illustrate the BRDF dependence on the orientation of the tarps' weft and warp threads. The study was performed using the GSFC scatterometer at incident zenith angles of 0 degrees, 10 degrees, and 30 degrees; scatter zenith angles from 0 degrees to 60 degrees; and scatter azimuth angles of 0 degrees, 45 degrees, 90 degrees, 135 degrees, and 180 degrees. The wavelengths were 485 nm, 550 nm, 633 nm, and 800 nm. The tarp's weft and warp dependence on BRDF is well defined at all measurement geometries and wavelengths. The BRDF difference can be as high as 8% at 0 degrees incident angle and 12% at 30 degrees incident angle. The fitted BRDF data show a very small discrepancy from the measured ones. New data on the forward and backscatter properties of radiometric tarps are reported. The backward scatter is well pronounced for the white samples. The black sample has well-pronounced forward scatter. The provided BRDF characterization of radiometric tarps is an excellent reference for anyone interested in using tarps for radiometric calibrations. The results are NIST traceable.
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
Dynamic Bidirectional Reflectance Distribution Functions: Measurement and Representation
2008-02-01
be included in the harmonic fits. Other sets of orthogonal functions such as Zernike polynomials have also been used to characterize BRDF and could...reflectance spectra of 3D objects,” Proc. SPIE 4663, 370–378 2001. 13J. R. Shell II, C. Salvagio, and J. R. Schott, “A novel BRDF measurement technique
Bhandari, Anak; Hamre, Børge; Frette, Øvynd; Zhao, Lu; Stamnes, Jakob J; Kildemo, Morten
2011-06-01
A Lambert surface would appear equally bright from all observation directions regardless of the illumination direction. However, the reflection from a randomly scattering object generally has directional variation, which can be described in terms of the bidirectional reflectance distribution function (BRDF). We measured the BRDF of a Spectralon white reflectance standard for incoherent illumination at 405 and 680 nm with unpolarized and plane-polarized light from different directions of incidence. Our measurements show deviations of the BRDF for the Spectralon white reflectance standard from that of a Lambertian reflector that depend both on the angle of incidence and the polarization states of the incident light and detected light. The non-Lambertian reflection characteristics were found to increase more toward the direction of specular reflection as the angle of incidence gets larger.
Ferrero, A; Campos, J; Rabal, A M; Pons, A; Hernanz, M L; Corróns, A
2011-09-26
The Bidirectional Reflectance Distribution Function (BRDF) is essential to characterize an object's reflectance properties. This function depends both on the various illumination-observation geometries as well as on the wavelength. As a result, the comprehensive interpretation of the data becomes rather complex. In this work we assess the use of the multivariable analysis technique of Principal Components Analysis (PCA) applied to the experimental BRDF data of a ceramic colour standard. It will be shown that the result may be linked to the various reflection processes occurring on the surface, assuming that the incoming spectral distribution is affected by each one of these processes in a specific manner. Moreover, this procedure facilitates the task of interpolating a series of BRDF measurements obtained for a particular sample. © 2011 Optical Society of America
Bi-directional reflectance distribution function of a tungsten block for ITER divertor
International Nuclear Information System (INIS)
Iwamae, Atsushi; Ogawa, Hiroaki; Sugie, Tatsuo; Kusama, Yoshinori
2012-02-01
In order to investigate reflection properties on plasma-facing material in ITER, the bi-directional reflectance distribution function (BRDF) of a tungsten block sample has been measured. On the machining surface of the block, one-directional machining lines are engraved. Two laser diodes λ652 nm and λ473 nm were used to simulate H α and H β emissions, respectively. The reflected light is affected by the machining surface. The reflected light traces an arc when the incident light is injected in the parallel direction to the engraved line. On the other hand the reflected light traces a line shape when the incident light is injected in the perpendicular direction to the engraved lines. Ray tracing simulation qualitatively explains the experimental results. (author)
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.
Wavelength dependence of the bidirectional reflectance distribution function (BRDF) of beach sands.
Doctor, Katarina Z; Bachmann, Charles M; Gray, Deric J; Montes, Marcos J; Fusina, Robert A
2015-11-01
The wavelength dependence of the dominant directional reflective properties of beach sands was demonstrated using principal component analysis and the related correlation matrix. In general, we found that the hyperspectral bidirectional reflectance distribution function (BRDF) of beach sands has weak wavelength dependence. Its BRDF varies slightly in three broad wavelength regions. The variations are more evident in surfaces of greater visual roughness than in smooth surfaces. The weak wavelength dependence of the BRDF of beach sand can be captured using three broad wavelength regions instead of hundreds of individual wavelengths.
Butler, Samuel D; Nauyoks, Stephen E; Marciniak, Michael A
2015-06-01
Of the many classes of bidirectional reflectance distribution function (BRDF) models, two popular classes of models are the microfacet model and the linear systems diffraction model. The microfacet model has the benefit of speed and simplicity, as it uses geometric optics approximations, while linear systems theory uses a diffraction approach to compute the BRDF, at the expense of greater computational complexity. In this Letter, nongrazing BRDF measurements of rough and polished surface-reflecting materials at multiple incident angles are scaled by the microfacet cross section conversion term, but in the linear systems direction cosine space, resulting in great alignment of BRDF data at various incident angles in this space. This results in a predictive BRDF model for surface-reflecting materials at nongrazing angles, while avoiding some of the computational complexities in the linear systems diffraction model.
Otremba, Zbigniew; Piskozub, Jacek
2004-04-19
The Bi-directional Reflectance Distribution Function (BRDF) of both clean seawaters and those polluted with oil film was determined using the Monte Carlo radiative transfer technique in which the spectrum of complex refractive index of Romashkino crude oil and the optical properties of case II water for chosen wavelengths was considered. The BRDF values were recorded for 1836 solid angular sectors of throughout the upper hemisphere. The visibility of areas polluted with oil observed from various directions and for various wavelengths is discussed.
Far-infrared /FIR/ optical black bidirectional reflectance distribution function /BRDF/
Smith, S. M.
1981-01-01
A nonspecular reflectometer and its operation at far-infrared wavelengths are described. Large differences in nonspecular reflectance were found to exist between different optically black coatings. Normal incidence bidirectional reflectance distribution function /BRDF) measurements at wavelengths between 12 and 316 microns of three black coatings show that their mean BRDFs increase with wavelength. The specularity of two of these coatings also showed a strong wavelength dependence, while the specularity of one coating seemed independent of wavelength. The BRDF of one coating depended on the angle of incidence at 12 and 38 microns, but not at 316 microns. Beyond 200 microns, it was found necessary to correct the measurements for the beam spread of the instrument.
Liu, Hong; Zhu, Jingping; Wang, Kai
2015-08-24
The geometrical attenuation model given by Blinn was widely used in the geometrical optics bidirectional reflectance distribution function (BRDF) models. Blinn's geometrical attenuation model based on symmetrical V-groove assumption and ray scalar theory causes obvious inaccuracies in BRDF curves and negatives the effects of polarization. Aiming at these questions, a modified polarized geometrical attenuation model based on random surface microfacet theory is presented by combining of masking and shadowing effects and polarized effect. The p-polarized, s-polarized and unpolarized geometrical attenuation functions are given in their separate expressions and are validated with experimental data of two samples. It shows that the modified polarized geometrical attenuation function reaches better physical rationality, improves the precision of BRDF model, and widens the applications for different polarization.
Germer, Thomas A
2017-11-20
We measured the Mueller matrix bidirectional reflectance distribution function (BRDF) of a sintered polytetrafluoroethylene (PTFE) sample over the scattering hemisphere for six incident angles (0°-75° in 15° steps) and for four wavelengths (351 nm, 532 nm, 633 nm, and 1064 nm). The data for each wavelength were fit to a phenomenological description for the Mueller matrix BRDF, which is an extension of the bidirectional surface scattering modes developed by Koenderink and van Doorn [J. Opt. Soc. Am. A.15, 2903 (1998)JOAOD60740-323210.1364/JOSAA.15.002903] for unpolarized BRDF. This description is designed to be complete, to obey the appropriate reciprocity conditions, and to provide a full description of the Mueller matrix BRDF as a function of incident and scattering directions for each wavelength. The description was further extended by linearizing the surface scattering mode coefficients with wavelength. This data set and its parameterization provides a comprehensive on-demand description of the reflectance properties for this commonly used diffuse reflectance reference material over a wide range of wavelengths.
Modelling the bidirectional reflectance distribution functions (BRDF of sea areas polluted by oil
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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.
Modeling the bidirectional reflectance distribution function of mixed finite plant canopies and soil
Schluessel, G.; Dickinson, R. E.; Privette, J. L.; Emery, W. J.; Kokaly, R.
1994-01-01
An analytical model of the bidirectional reflectance for optically semi-infinite plant canopies has been extended to describe the reflectance of finite depth canopies contributions from the underlying soil. The model depends on 10 independent parameters describing vegetation and soil optical and structural properties. The model is inverted with a nonlinear minimization routine using directional reflectance data for lawn (leaf area index (LAI) is equal to 9.9), soybeans (LAI, 2.9) and simulated reflectance data (LAI, 1.0) from a numerical bidirectional reflectance distribution function (BRDF) model (Myneni et al., 1988). While the ten-parameter model results in relatively low rms differences for the BRDF, most of the retrieved parameters exhibit poor stability. The most stable parameter was the single-scattering albedo of the vegetation. Canopy albedo could be derived with an accuracy of less than 5% relative error in the visible and less than 1% in the near-infrared. Sensitivity were performed to determine which of the 10 parameters were most important and to assess the effects of Gaussian noise on the parameter retrievals. Out of the 10 parameters, three were identified which described most of the BRDF variability. At low LAI values the most influential parameters were the single-scattering albedos (both soil and vegetation) and LAI, while at higher LAI values (greater than 2.5) these shifted to the two scattering phase function parameters for vegetation and the single-scattering albedo of the vegetation. The three-parameter model, formed by fixing the seven least significant parameters, gave higher rms values but was less sensitive to noise in the BRDF than the full ten-parameter model. A full hemispherical reflectance data set for lawn was then interpolated to yield BRDF values corresponding to advanced very high resolution radiometer (AVHRR) scan geometries collected over a period of nine days. The resulting parameters and BRDFs are similar to those for the
Zhan, Hanyu; Voelz, David G.
2016-12-01
The polarimetric bidirectional reflectance distribution function (pBRDF) describes the relationships between incident and scattered Stokes parameters, but the familiar surface-only microfacet pBRDF cannot capture diffuse scattering contributions and depolarization phenomena. We propose a modified pBRDF model with a diffuse scattering component developed from the Kubelka-Munk and Le Hors et al. theories, and apply it in the development of a method to jointly estimate refractive index, slope variance, and diffuse scattering parameters from a series of Stokes parameter measurements of a surface. An application of the model and estimation approach to experimental data published by Priest and Meier shows improved correspondence with measurements of normalized Mueller matrix elements. By converting the Stokes/Mueller calculus formulation of the model to a degree of polarization (DOP) description, the estimation results of the parameters from measured DOP values are found to be consistent with a previous DOP model and results.
International Nuclear Information System (INIS)
Guo Li-Xin; Gou Xue-Yin; Zhang Lian-Bo
2014-01-01
In this study, the bidirectional reflectance distribution function (BRDF) of a one-dimensional conducting rough surface and a dielectric rough surface are calculated with different frequencies and roughness values in the microwave band by using the method of moments, and the relationship between the bistatic scattering coefficient and the BRDF of a rough surface is expressed. From the theory of the parameters of the rough surface BRDF, the parameters of the BRDF are obtained using a genetic algorithm. The BRDF of a rough surface is calculated using the obtained parameter values. Further, the fitting values and theoretical calculations of the BRDF are compared, and the optimization results are in agreement with the theoretical calculation results. Finally, a reference for BRDF modeling of a Gaussian rough surface in the microwave band is provided by the proposed method. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)
Griner, D. B.
1979-01-01
The paper considers the bidirectional reflectance distribution function (BRDF) of black coatings used on stray light suppression systems for the Space Telescope (ST). The ST stray light suppression requirement is to reduce earth, moon, and sun light in the focal plane to a level equivalent to one 23 Mv star per square arcsecond, an attenuation of 14 orders of magnitude. It is impractical to verify the performance of a proposed baffle system design by full scale tests because of the large size of the ST, so that a computer analysis is used to select the design. Accurate computer analysis requires a knowledge of the diffuse scatter at all angles from the surface of the coatings, for all angles of incident light. During the early phases of the ST program a BRDF scanner was built at the Marshall Space Flight Center to study the scatter from black materials; the measurement system is described and the results of measurements on samples proposed for use on the ST are presented.
Directory of Open Access Journals (Sweden)
Min-Jhong Gu
2014-08-01
Full Text Available This article describes the development of a suite of programs that is capable of simulating the radiation properties of a random rough surface (RRS. The fundamental approach involves the generation, by fast Fourier transform (FFT built with rigorous finite difference time domain (FDTD, as the theoretical basis for the simulation of a bidirectional reflectance distribution function (BRDF of the RRS. The results are compared with the measurements and modeling of existing work to verify the feasibility of customized programming. It was found that the results of this study were a better match to the measurement data than those achieved in other modeling work.
Wang, Qianqian; Zhao, Jing; Gong, Yong; Hao, Qun; Peng, Zhong
2017-11-20
A hybrid artificial bee colony (ABC) algorithm inspired by the best-so-far solution and bacterial chemotaxis was introduced to optimize the parameters of the five-parameter bidirectional reflectance distribution function (BRDF) model. To verify the performance of the hybrid ABC algorithm, we measured BRDF of three kinds of samples and simulated the undetermined parameters of the five-parameter BRDF model using the hybrid ABC algorithm and the genetic algorithm, respectively. The experimental results demonstrate that the hybrid ABC algorithm outperforms the genetic algorithm in convergence speed, accuracy, and time efficiency under the same conditions.
2007-03-01
66 3.5.1 Specular Reflection Assumption . . . . . . . . . . . . . . . . . . . 70 3.5.2 Radiosity ...69 3.31. Radiosity Algorithm Flowchart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 3.32. POV...3.5.2 Radiosity . The first algorithm implemented to attempt to hemispher- ically integrate the irradiance contribution was classical radiosity as
An explicit canopy BRDF model and inversion. [Bidirectional Reflectance Distribution Function
Liang, Shunlin; Strahler, Alan H.
1992-01-01
Based on a rigorous canopy radiative transfer equation, the multiple scattering radiance is approximated by the asymptotic theory, and the single scattering radiance calculation, which requires an numerical intergration due to considering the hotspot effect, is simplified. A new formulation is presented to obtain more exact angular dependence of the sky radiance distribution. The unscattered solar radiance and single scattering radiance are calculated exactly, and the multiple scattering is approximated by the delta two-stream atmospheric radiative transfer model. The numerical algorithms prove that the parametric canopy model is very accurate, especially when the viewing angles are smaller than 55 deg. The Powell algorithm is used to retrieve biospheric parameters from the ground measured multiangle observations.
Ma, B.; Li, J.; Fan, W.; Ren, H.; Xu, X.
2017-12-01
Leaf area index (LAI) is one of the important parameters of vegetation canopy structure, which can represent the growth condition of vegetation effectively. The accuracy, availability and timeliness of LAI data can be improved greatly, which is of great importance to vegetation-related research, such as the study of atmospheric, land surface and hydrological processes to obtain LAI by remote sensing method. Heihe River Basin is the inland river basin in northwest China. There are various types of vegetation and all kinds of terrain conditions in the basin, so it is helpful for testing the accuracy of the model under the complex surface and evaluating the correctness of the model to study LAI in this area. On the other hand, located in west arid area of China, the ecological environment of Heihe Basin is fragile, LAI is an important parameter to represent the vegetation growth condition, and can help us understand the status of vegetation in the Heihe River Basin. Different from the previous LAI inversion models, the BRDF (bidirectional reflectance distribution function) unified model can be applied for both continuous vegetation and discrete vegetation, it is appropriate to the complex vegetation distribution. LAI is the key input parameter of the model. We establish the inversion algorithm that can exactly retrieve LAI using remote sensing image based on the unified model. First, we determine the vegetation type through the vegetation classification map to obtain the corresponding G function, leaf and surface reflectivity. Then, we need to determine the leaf area index (LAI), the aggregation index (ζ) and the sky scattered light ratio (β) range and the value of the interval, entering all the parameters into the model to calculate the corresponding reflectivity ρ and establish the lookup table of different vegetation. Finally, we can invert LAI on the basis of the established lookup table. The principle of inversion is least squares method. We have produced 1 km
Directory of Open Access Journals (Sweden)
M. Dumont
2010-03-01
Full Text Available High-accuracy measurements of snow Bidirectional Reflectance Distribution Function (BRDF were performed for four natural snow samples with a spectrogonio-radiometer in the 500–2600 nm wavelength range. These measurements are one of the first sets of direct snow BRDF values over a wide range of lighting and viewing geometry. They were compared to BRDF calculated with two optical models. Variations of the snow anisotropy factor with lighting geometry, wavelength and snow physical properties were investigated. Results show that at wavelengths with small penetration depth, scattering mainly occurs in the very top layers and the anisotropy factor is controlled by the phase function. In this condition, forward scattering peak or double scattering peak is observed. In contrast at shorter wavelengths, the penetration of the radiation is much deeper and the number of scattering events increases. The anisotropy factor is thus nearly constant and decreases at grazing observation angles. The whole dataset is available on demand from the corresponding author.
Butler, J.J.; Park, H.; Barnes, P.Y.; Early, E.A.; Eijk-Olij, C. van; Zoutman, A.E.; Buller-Leeuwen, S. van; Groote Schaarsberg, J.
2002-01-01
The measurement and long-term monitoring of global total ozone by ultraviolet albedo measuring satellite instruments require accurate and precise determination of the Bi-directional Reflectance Distribution Function (BRDF) of laboratory-based diffusers used in the pre-launch calibration of those
Butler, J.J.; Park, H.; Barnes, P.Y.; Early, E.A.; Eijk-Olij, C. van; Zoutman, A.E.; Buller-Leeuwen, S. van; Groote Schaarsberg, J.
2002-01-01
The measurement and long-term monitoring of global total ozone by ultraviolet albedo measuring satellite instruments require accurate and precise determination of the Bi-directional Reflectance Distribution Function (BRDF) of laboratory-based diffusers used in the pre-launch calibration of those instruments. To assess the ability of laboratories to provide accurate Ultra Violet (UV) diffuse BRDF measurements, a BRDF measurement comparison was initiated by the NASA Total Ozone Mapping Spectrom...
Prokhorov, Alexander; Prokhorova, Nina I
2012-11-20
We applied the bidirectional reflectance distribution function (BRDF) model consisting of diffuse, quasi-specular, and glossy components to the Monte Carlo modeling of spectral effective emissivities for nonisothermal cavities. A method for extension of a monochromatic three-component (3C) BRDF model to a continuous spectral range is proposed. The initial data for this method are the BRDFs measured in the plane of incidence at a single wavelength and several incidence angles and directional-hemispherical reflectance measured at one incidence angle within a finite spectral range. We proposed the Monte Carlo algorithm for calculation of spectral effective emissivities for nonisothermal cavities whose internal surface is described by the wavelength-dependent 3C BRDF model. The results obtained for a cylindroconical nonisothermal cavity are discussed and compared with results obtained using the conventional specular-diffuse model.
Kim, Hye-Won; Yeom, Jong-Min; Shin, Daegeun; Choi, Sungwon; Han, Kyung-Soo; Roujean, Jean-Louis
2017-08-01
In this study, a new assessment of thin cloud detection with the application of bidirectional reflectance distribution function (BRDF) model-based background surface reflectance was undertaken by interpreting surface spectra characterized using the Geostationary Ocean Color Imager (GOCI) over a land surface area. Unlike cloud detection over the ocean, the detection of cloud over land surfaces is difficult due to the complicated surface scattering characteristics, which vary among land surface types. Furthermore, in the case of thin clouds, in which the surface and cloud radiation are mixed, it is difficult to detect the clouds in both land and atmospheric fields. Therefore, to interpret background surface reflectance, especially underneath cloud, the semiempirical BRDF model was used to simulate surface reflectance by reflecting solar angle-dependent geostationary sensor geometry. For quantitative validation, Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) data were used to make a comparison with the proposed cloud masking result. As a result, the new cloud masking scheme resulted in a high probability of detection (POD = 0.82) compared with the Moderate Resolution Imaging Spectroradiometer (MODIS) (POD = 0.808) for all cloud cases. In particular, the agreement between the CALIPSO cloud product and new GOCI cloud mask was over 94% when detecting thin cloud (e.g., altostratus and cirrus) from January 2014 to June 2015. This result is relatively high in comparison with the result from the MODIS Collection 6 cloud mask product (MYD35).
Yura, H T; Thrane, L; Andersen, P E
2000-12-01
Within the paraxial approximation, a closed-form solution for the Wigner phase-space distribution function is derived for diffuse reflection and small-angle scattering in a random medium. This solution is based on the extended Huygens-Fresnel principle for the optical field, which is widely used in studies of wave propagation through random media. The results are general in that they apply to both an arbitrary small-angle volume scattering function, and arbitrary (real) ABCD optical systems. Furthermore, they are valid in both the single- and multiple-scattering regimes. Some general features of the Wigner phase-space distribution function are discussed, and analytic results are obtained for various types of scattering functions in the asymptotic limit s > 1, where s is the optical depth. In particular, explicit results are presented for optical coherence tomography (OCT) systems. On this basis, a novel way of creating OCT images based on measurements of the momentum width of the Wigner phase-space distribution is suggested, and the advantage over conventional OCT images is discussed. Because all previous published studies regarding the Wigner function are carried out in the transmission geometry, it is important to note that the extended Huygens-Fresnel principle and the ABCD matrix formalism may be used successfully to describe this geometry (within the paraxial approximation). Therefore for completeness we present in an appendix the general closed-form solution for the Wigner phase-space distribution function in ABCD paraxial optical systems for direct propagation through random media, and in a second appendix absorption effects are included.
Billing, H.; Koslowsky, D.
In the AVHRR data of the polar orbiting NOAA Satellites, directional reflectance under a certain view from satellite and a certain illumination by the sun is measured. Due to the nearly sunsynchroneous orbit of the NOAA satellite, each area is seen under different viewing angles in successive days. Only after approximately 9 days, the conditions are again similar. Areas, seen in specular direction, may appear only half as bright, as if seen in antispecular direction. This deviation from a Lambertian reflector is a function of the surface roughness and the degree of coverage with vegetation. The NOAA afternoon satellites drift by half an hour from year to year. Thus even data from the same season, but different years, are seen under different illumination conditions. To derive the bidirectional reflection distribution function in dependence on satellite viewing angle and solar illumination becomes a very complicated procedure. Using the Helmholtz reciprocity principle (HRP), i.e. the symetrie in viewing and illumination, reduces the problem by one dimension. For different bidimensional reflection laws it will be tested, whether they can be formulated to fullfill the HRP. Via regression, the parameters will be deduced for time series of AVHRR data of 10 years from NOAA 11,14,16 and 17. Brdfunctions, suggested by Rao as well as a law, suggested by Ba seem to become unstable for low sun resp. large viewing zenit angles. Only brdfs with 4 coefficients can fit the observed distributions. A nonlinear temporal angular model (NTAM), suggested by Latifovic,Cihlar and Chen, seems to be suitable to describe even the hot spot and the dependence on plant growth. The coefficients of these brdf-function will be derived via regression for monthly series of cloud free data for the European area, where AVHRR data in full resolution are received in Berlin. Using these coefficients, monthly maps of surface roughness are produced for the above area for the time since 1985. Ba, M
dftools: Distribution function fitting
Obreschkow, Danail
2018-05-01
dftools, written in R, finds the most likely P parameters of a D-dimensional distribution function (DF) generating N objects, where each object is specified by D observables with measurement uncertainties. For instance, if the objects are galaxies, it can fit a mass function (D=1), a mass-size distribution (D=2) or the mass-spin-morphology distribution (D=3). Unlike most common fitting approaches, this method accurately accounts for measurement in uncertainties and complex selection functions.
Directional reflectance factor distributions of a cotton row crop
Kimes, D. S.; Newcomb, W. W.; Schutt, J. B.; Pinter, P. J., Jr.; Jackson, R. D.
1984-01-01
The directional reflectance factor distribution spanning the entire exitance hemisphere was measured for a cotton row crop (Gossypium barbadense L.) with 39 percent ground cover. Spectral directional radiances were taken in NOAA satellite 7 AVHRR bands 1 and 2 using a three-band radiometer with restricted 12 deg full angle field of view at half peak power points. Polar co-ordinate system plots of directional reflectance factor distributions and three-dimensional computer graphic plots of scattered flux were used to study the dynamics of the directional reflectance factor distribution as a function of spectral band, geometric structure of the scene, solar zenith and azimuth angles, and optical properties of the leaves and soil. The factor distribution of the incomplete row crops was highly polymodal relative to that for complete vegetation canopies. Besides the enhanced reflectance for the antisolar point, a reflectance minimum was observed towards the forwardscatter direction in the principle plane of the sun. Knowledge of the mechanics of the observed dynamics of the data may be used to provide rigorous validation for two- or three-dimensional radiative transfer models, and is important in interpreting aircraft and satellite data where the solar angle varies widely.
The tensor distribution function.
Leow, A D; Zhu, S; Zhan, L; McMahon, K; de Zubicaray, G I; Meredith, M; Wright, M J; Toga, A W; Thompson, P M
2009-01-01
Diffusion weighted magnetic resonance imaging is a powerful tool that can be employed to study white matter microstructure by examining the 3D displacement profile of water molecules in brain tissue. By applying diffusion-sensitized gradients along a minimum of six directions, second-order tensors (represented by three-by-three positive definite matrices) can be computed to model dominant diffusion processes. However, conventional DTI is not sufficient to resolve more complicated white matter configurations, e.g., crossing fiber tracts. Recently, a number of high-angular resolution schemes with more than six gradient directions have been employed to address this issue. In this article, we introduce the tensor distribution function (TDF), a probability function defined on the space of symmetric positive definite matrices. Using the calculus of variations, we solve the TDF that optimally describes the observed data. Here, fiber crossing is modeled as an ensemble of Gaussian diffusion processes with weights specified by the TDF. Once this optimal TDF is determined, the orientation distribution function (ODF) can easily be computed by analytic integration of the resulting displacement probability function. Moreover, a tensor orientation distribution function (TOD) may also be derived from the TDF, allowing for the estimation of principal fiber directions and their corresponding eigenvalues.
Auroal electron distribution function
International Nuclear Information System (INIS)
Kaufmann, R.L.; Dusenbery, P.B.; Thomas, B.J.; Arnoldy, R.L.
1978-01-01
The electron velocity distribution function is presented in the energy range 25 eV 8 cm/s (E=300 eV) are nearly isotropic in pitch angle throughout the flight. Upgoing electrons show almost no pitch angle dependence beyond 120 0 , and their fluxes decline smoothly as energy increases, with little or no evidence of a plateau. Preliminary results of numerical integrations, to study bulk properties and stability of the plasma are presented
Unifying distribution functions: some lesser known distributions.
Moya-Cessa, J R; Moya-Cessa, H; Berriel-Valdos, L R; Aguilar-Loreto, O; Barberis-Blostein, P
2008-08-01
We show that there is a way to unify distribution functions that describe simultaneously a classical signal in space and (spatial) frequency and position and momentum for a quantum system. Probably the most well known of them is the Wigner distribution function. We show how to unify functions of the Cohen class, Rihaczek's complex energy function, and Husimi and Glauber-Sudarshan distribution functions. We do this by showing how they may be obtained from ordered forms of creation and annihilation operators and by obtaining them in terms of expectation values in different eigenbases.
The spatial distribution of infrared radiation from visible reflection nebulae
Luan, Ling; Werner, Michael W.; Dwek, Eli; Sellgren, Kris
1989-01-01
The emission at IRAS 12 and 25 micron bands of reflection nebulae is far in excess of that expected from the longer wavelength equilibrium thermal emission. The excess emission in the IRAS 12 micron band is a general phenomenon, seen in various components of interstellar medium such as IR cirrus clouds, H II regions, atomic and molecular clouds, and also normal spiral galaxies. This excess emission has been attributed to UV excited fluorescence in polycyclic aromatic hydrocarbon (PAH) molecules or to the effect of temperature fluctuations in very small grains. Results are presented of studies of IRAS data on reflection nebulae selected from the van den Bergh reflection nebulae sample. Detailed scans of flux ratio and color temperature across the nebulae were obtained in order to study the spatial distribution of IR emission. A model was used to predict the spatial distribution of IR emission from dust grains illuminated by a B type star. The model was also used to explore the excitation of the IRAS 12 micron band emission as a function of stellar temperature. The model predictions are in good agreement with the analysis of reflection nebulae, illuminated by stars with stellar temperature ranging from 21,000 down to 3,000 K.
Nitrogen vertical distribution by canopy reflectance spectrum in winter wheat
International Nuclear Information System (INIS)
Huang, W J; Yang, Q Y; Peng, D L; Huang, L S; Zhang, D Y; Yang, G J
2014-01-01
Nitrogen is a key factor for plant photosynthesis, ecosystem productivity and leaf respiration. Under the condition of nitrogen deficiency, the crop shows the nitrogen deficiency symptoms in the bottom leaves, while excessive nitrogen will affect the upper layer leaves first. Thus, timely measurement of vertical distribution of foliage nitrogen content is critical for growth diagnosis, crop management and reducing environmental impact. This study presents a method using bi-directional reflectance difference function (BRDF) data to invert foliage nitrogen vertical distribution. We developed upper-layer nitrogen inversion index (ULNI), middle-layer nitrogen inversion index (MLNI) and bottom-layer nitrogen inversion index (BLNI) to reflect foliage nitrogen inversion at upper layer, middle layer and bottom layer, respectively. Both ULNI and MLNI were made by the value of the ratio of Modified Chlorophyll Absorption Ration Index to the second Modified Triangular Vegetation Index (MCARI/MTVI2) referred to as canopy nitrogen inversion index (CNII) in this study at ±40° and ±50°, and at ±30° and ±40° view angles, respectively. The BLNI was composed by the value of nitrogen reflectance index (NRI) at ±20° and ±30° view angles. These results suggest that it is feasible to measure foliage nitrogen vertical-layer distribution in a large scale by remote sensing
International Nuclear Information System (INIS)
Hasegawa, K.; Matsuyama, H.; Tsuzuki, H.; Sweda, T.
2006-01-01
The effect of the dependence of the satellite data on sun/sensor geometry must be considered in the case of monitoring vegetation from satellites. Vegetation structure causes uneven scattering of sunlight, which is expressed by bi-directional reflectance distribution function (BRDF). The purpose of this study is to estimate the effect of BRDF of monitoring vegetation using the reflectance of visible and near-infrared bands. We investigated the vegetation in succession stages after forest fire (main species: spruce) in the northwestern Canada. BRF (Bidirectional Reflectance Factor) was measured in the seven sites of some succession stages, along with the measurements of leaf area index (LAI) and biomass. The main results obtained in this study are summarized as follows. (1) In each site, the difference of Normalized Difference Vegetation Index (NDVI) value around 0.1-0.2 was caused by BRDF when the sensor angle was changed from -15deg to 15 deg, being equivalent to the standard image of IKONOS. Also, LAI estimated by NDVI varied from 22% to 65% of the average. (2) The robustness of other vegetation indices to BRDF was compared. The reflectance of the near-infrared band normalized by the sum of other bands (nNIR), and Global Environmental Monitoring Index (GEMI) were investigated along with NDVI. It is clarified that nNIR was most robust in the site where vegetation existed. GEMI was most robust in the sites of scarce vegetation, while NDVI was strongly affected by BRDF in such sites
Characterization of Stationary Distributions of Reflected Diffusions
2014-01-01
operations research to finance and mathemat- ical physics , and their stationary distributions often serve to characterize or approximate important...REFERENCES [1] Atar , R., Budhiraja, A. and Dupuis, P. (2001). On positive recurrence of constrained diffusion processes. Ann. Probab., 29 No. 2, 979-1000
Structure functions and parton distributions
International Nuclear Information System (INIS)
Olness, F.; Tung, Wu-Ki
1991-04-01
Activities of the structure functions and parton distributions group is summarized. The impact of scheme-dependence of parton distributions (especially sea-quarks and gluons) on the quantitative formulation of the QCD parton model is highlighted. Recent progress on the global analysis of parton distributions is summarized. Issues on the proper use of the next-to-leading parton distributions are stressed
Distribution functions of probabilistic automata
Vatan, F.
2001-01-01
Each probabilistic automaton M over an alphabet A defines a probability measure Prob sub(M) on the set of all finite and infinite words over A. We can identify a k letter alphabet A with the set {0, 1,..., k-1}, and, hence, we can consider every finite or infinite word w over A as a radix k expansion of a real number X(w) in the interval [0, 1]. This makes X(w) a random variable and the distribution function of M is defined as usual: F(x) := Prob sub(M) { w: X(w) automata in detail. Automata with continuous distribution functions are characterized. By a new, and much more easier method, it is shown that the distribution function F(x) is an analytic function if it is a polynomial. Finally, answering a question posed by D. Knuth and A. Yao, we show that a polynomial distribution function F(x) on [0, 1] can be generated by a prob abilistic automaton iff all the roots of F'(x) = 0 in this interval, if any, are rational numbers. For this, we define two dynamical systems on the set of polynomial distributions and study attracting fixed points of random composition of these two systems.
Structure functions and parton distributions
International Nuclear Information System (INIS)
Martin, A.D.; Stirling, W.J.; Roberts, R.G.
1995-01-01
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
Spatial distribution of reflected gamma rays by Monte Carlo simulation
International Nuclear Information System (INIS)
Jehouani, A.; Merzouki, A.; Boutadghart, F.; Ghassoun, J.
2007-01-01
In nuclear facilities, the reflection of gamma rays of the walls and metals constitutes an unknown origin of radiation. These reflected gamma rays must be estimated and determined. This study concerns reflected gamma rays on metal slabs. We evaluated the spatial distribution of the reflected gamma rays spectra by using the Monte Carlo method. An appropriate estimator for the double differential albedo is used to determine the energy spectra and the angular distribution of reflected gamma rays by slabs of iron and aluminium. We took into the account the principal interactions of gamma rays with matter: photoelectric, coherent scattering (Rayleigh), incoherent scattering (Compton) and pair creation. The Klein-Nishina differential cross section was used to select direction and energy of scattered photons after each Compton scattering. The obtained spectra show peaks at 0.511 * MeV for higher source energy. The Results are in good agreement with those obtained by the TRIPOLI code [J.C. Nimal et al., TRIPOLI02: Programme de Monte Carlo Polycinsetique a Trois dimensions, CEA Rapport, Commissariat a l'Energie Atomique.
Directory of Open Access Journals (Sweden)
L. A. Gubanova
2015-03-01
Full Text Available The paper deals with findings for the energy reflection coefficient distribution of anti- reflection coating along the surface of optical elements with a very small radius (2-12 mm. The factors influencing the magnitude of the surface area of the optical element, in which the energy reflection coefficient is constant, were detected. The main principles for theoretical models that describe the spectral characteristics of the multilayer interference coatings were used to achieve these objectives. The relative size of the enlightenment area is defined as the ratio of the radius for the optical element surface, where the reflection is less than a certain value, to its radius (ρ/r. The result of research is the following: this size is constant for a different value of the curvature radius for the optical element made of the same material. Its value is determined by the refractive index of material (nm, from which the optical element was made, and the design of antireflection coatings. For single-layer coatings this value is ρ/r = 0.5 when nm = 1.51; and ρ/r = 0.73 when nm = 1.75; for two-layer coatings ρ/r = 0.35 when nm = 1.51 and ρ/r = 0.41 when nm = 1.75. It is shown that with increasing of the material refractive index for the substrate size, the area of minimum reflection coefficient is increased. The paper considers a single-layer, two-layer, three-layer and five-layer structures of antireflection coatings. The findings give the possibility to conclude that equal thickness coverings formed on the optical element surface with a small radius make no equal reflection from the entire surface, and distribution of the layer thickness needs to be looked for, providing a uniform radiation reflection at all points of the spherical surface.
Teachers' reflections on distributive leadership in public primary ...
African Journals Online (AJOL)
hierarchy, leadership styles, power, principals, school climate, teacher ... of the work of the principal, has led to the emergence of distributive forms of ..... premised on shared collaboration, where their function is to “connect and contribute”.
Directory of Open Access Journals (Sweden)
Xin Mi Yang
2015-01-01
Full Text Available We make preliminary investigations on a new approach to reducing radar cross section (RCS of conducting objects. This approach employs novel planar metasurfaces characterizing nonuniform distribution of reflection phase. The operation principle of this approach and the design rule of the associated metasurfaces are explained using a simplified theoretical model. We then present a design example of such metasurfaces, in which three-layer stacked square patches with variable sizes are utilized as the reflecting elements. The proposed RCS-reduction approach is verified by both numerical simulations and measurements on the example, under the assumption of normal plane wave incidence. It is observed that, in a fairly wide frequency band (from 3.6 to 5.5 GHz, the presented example is capable of suppressing the specular reflections of conducting plates significantly (by more than 7 dB for two orthogonal incident polarizations.
Distribution function of dark matter
International Nuclear Information System (INIS)
Evans, N. Wyn; An, Jin H.
2006-01-01
There is good evidence from N-body simulations that the velocity distribution in the outer parts of halos is radially anisotropic, with the kinetic energy in the radial direction roughly equal to the sum of that in the two tangential directions. We provide a simple algorithm to generate such cosmologically important distribution functions. Introducing r E (E), the radius of the largest orbit of a particle with energy E, we show how to write down almost trivially a distribution function of the form f(E,L)=L -1 g(r E ) for any spherical model - including the 'universal' halo density law (Navarro-Frenk-White profile). We in addition give the generic form of the distribution function for any model with a local density power-law index α and anisotropy parameter β and provide limiting forms appropriate for the central parts and envelopes of dark matter halos. From those, we argue that, regardless of the anisotropy, the density falloff at large radii must evolve to ρ∼r -4 or steeper ultimately
Vertical distribution of meiofauna on reflective sandy beaches
Directory of Open Access Journals (Sweden)
Mariana de Oliveira Martins
2015-12-01
Full Text Available Abstract Extreme physical conditions usually limit the meiofauna occurrence and distribution in highly hydrodynamic environments such as reflective beaches. Despite sediment grains of the upper layers being constantly resuspended and deposited, the high energy of the swash zone besides depositing coarse sediments allows an ample vertical distribution of meiofaunal organisms. The effect of physical, chemical and sediment variables on the vertical distribution of meiofaunal organims and nematodes was analysed on two reflective exposed beaches. Sampling was conducted at three sampling points on each beach in the swash zone. The sediment collected was divided into four 10-cm strata (0-10 cm, 10-20 cm, 20-30 cm, 30-40 cm. The statistical differences between strata due to factors previously established (i.e. meiofaunal composition, density of most abundant taxa were tested using a hierarchical PERMANOVA applied under similarity and euclidian distances. An inverse relation among average grain size, content of organic matter and sediment sorting was evident. Coarser sediment characterized the upper layers, while at deeper layers the sediment was very poorly sorted and presented a higher content of organic matter. A similar pattern in the vertical distribution of meiofaunal and nematofaunal composition and density was detected. The lowest densities were associated with the first stratum (0-10 cm, highly affected by hydrodynamics. The vertical distribution of organisms was statistically different only when the interaction among factors was considered. This result suggests that zonation and vertical distribution of meiofaunal organisms are determined by the within-beach variability.
CMP reflection imaging via interferometry of distributed subsurface sources
Kim, D.; Brown, L. D.; Quiros, D. A.
2015-12-01
The theoretical foundations of recovering body wave energy via seismic interferometry are well established. However in practice, such recovery remains problematic. Here, synthetic seismograms computed for subsurface sources are used to evaluate the geometrical combinations of realistic ambient source and receiver distributions that result in useful recovery of virtual body waves. This study illustrates how surface receiver arrays that span a limited distribution suite of sources, can be processed to reproduce virtual shot gathers that result in CMP gathers which can be effectively stacked with traditional normal moveout corrections. To verify the feasibility of the approach in practice, seismic recordings of 50 aftershocks following the magnitude of 5.8 Virginia earthquake occurred in August, 2011 have been processed using seismic interferometry to produce seismic reflection images of the crustal structure above and beneath the aftershock cluster. Although monotonic noise proved to be problematic by significantly reducing the number of usable recordings, the edited dataset resulted in stacked seismic sections characterized by coherent reflections that resemble those seen on a nearby conventional reflection survey. In particular, "virtual" reflections at travel times of 3 to 4 seconds suggest reflector sat approximately 7 to 12 km depth that would seem to correspond to imbricate thrust structures formed during the Appalachian orogeny. The approach described here represents a promising new means of body wave imaging of 3D structure that can be applied to a wide array of geologic and energy problems. Unlike other imaging techniques using natural sources, this technique does not require precise source locations or times. It can thus exploit aftershocks too small for conventional analyses. This method can be applied to any type of microseismic cloud, whether tectonic, volcanic or man-made.
Functional Reflective Polarizer for Augmented Reality and Color Vision Deficiency
2016-03-03
augment reality system is relatively high as compared to a polarizing beam splitter or a conventional reflective polarizer. Such a functional reflective...brightness of the display [7]. A key component for polarization management is polarizing beam splitter (PBS). Even though the PBS has exceptional...polarizer that can be incorporated into a compact augmented reality system. The design principle of the functional reflective polarizer is explained and
Tunneling and reflection in unimolecular reaction kinetic energy release distributions
Hansen, K.
2018-02-01
The kinetic energy release distributions in unimolecular reactions is calculated with detailed balance theory, taking into account the tunneling and the reflection coefficient in three different types of transition states; (i) a saddle point corresponding to a standard RRKM-type theory, (ii) an attachment Langevin cross section, and (iii) an absorbing sphere potential at short range, without long range interactions. Corrections are significant in the one dimensional saddle point states. Very light and lightly bound absorbing systems will show measurable effects in decays from the absorbing sphere, whereas the Langevin cross section is essentially unchanged.
Determination of size distribution function
International Nuclear Information System (INIS)
Teshome, A.; Spartakove, A.
1987-05-01
The theory of a method is outlined which gives the size distribution function (SDF) of a polydispersed system of non-interacting colloidal and microscopic spherical particles, having sizes in the range 0-10 -5 cm., from a gedanken experimental scheme. It is assumed that the SDF is differentiable and the result is obtained for rotational frequency in the order of 10 3 (sec) -1 . The method may be used independently, but is particularly useful in conjunction with an alternate method described in a preceding paper. (author). 8 refs, 2 figs
An Empirical Mass Function Distribution
Murray, S. G.; Robotham, A. S. G.; Power, C.
2018-03-01
The halo mass function, encoding the comoving number density of dark matter halos of a given mass, plays a key role in understanding the formation and evolution of galaxies. As such, it is a key goal of current and future deep optical surveys to constrain the mass function down to mass scales that typically host {L}\\star galaxies. Motivated by the proven accuracy of Press–Schechter-type mass functions, we introduce a related but purely empirical form consistent with standard formulae to better than 4% in the medium-mass regime, {10}10{--}{10}13 {h}-1 {M}ȯ . In particular, our form consists of four parameters, each of which has a simple interpretation, and can be directly related to parameters of the galaxy distribution, such as {L}\\star . Using this form within a hierarchical Bayesian likelihood model, we show how individual mass-measurement errors can be successfully included in a typical analysis, while accounting for Eddington bias. We apply our form to a question of survey design in the context of a semi-realistic data model, illustrating how it can be used to obtain optimal balance between survey depth and angular coverage for constraints on mass function parameters. Open-source Python and R codes to apply our new form are provided at http://mrpy.readthedocs.org and https://cran.r-project.org/web/packages/tggd/index.html respectively.
Quantum distribution function of nonequilibrium system
International Nuclear Information System (INIS)
Sogo, Kiyoshi; Fujimoto, Yasushi.
1990-03-01
A path integral representation is derived for the Wigner distribution function of a nonequilibrium system coupled with heat bath. Under appropriate conditions, the Wigner distribution function approaches an equilibrium distribution, which manifests shifting and broadening of spectral lines due to the interaction with heat bath. It is shown that the equilibrium distribution becomes the quantum canonical distribution in the vanishing coupling constant limit. (author)
Attachment patterns and Reflective Functioning in Traumatized Refugees
DEFF Research Database (Denmark)
Riber, Karin
, attachment systems, emotion-regulation, and personality. Attachment research on the consequences of organized violence and forced migration is sparse and research in PTSD-treatment for refugees is lacking behind. Cumulative pre-migration traumatic experiences and ongoing post-migration stressors might lead...... Psychiatry, Denmark. June 2011-March 2012 patients fulfilling inclusion criteria entered the trial. The present sample consisted of those of the 135 patients who were Arabic-speaking (N=67). Measures involved the Adult Attachment Interview, The Reflective Functioning Scale, Revised Adult Attachment Scale...... and reflective functioning will be described and implications for psychotherapy discussed. Keywords: Adult attachment, reflective functioning, refugee traumatisation....
Borelli, Jessica L; Hong, Kajung; Rasmussen, Hannah F; Smiley, Patricia A
2017-09-01
Theorists argue that parental reflective functioning (PRF) is activated in response to emotions, potentially supporting parenting sensitivity even when arousal is high. That is, when parents become emotionally reactive when interacting with their children, those who can use PRF to understand their children's mental states should be able to parent sensitively, which, in turn, should promote children's ability to understand their own mental states. We test this theory by examining whether, in the face of physiological reactivity, mothers' PRF inhibits one form of parenting insensitivity, overcontrol (OC), and whether this process in turn predicts children's RF. A diverse sample of school-age children (N = 106, Mage = 10.27 years) completed a standardized failure paradigm while their mothers were asked to passively observe. Following the stressor, mothers and children independently completed interviews regarding the task, which were later coded for RF with respect to children's mental states. Mothers provided saliva samples before and after the stressor, and after the interview, which were later assayed for cortisol reactivity; maternal behavior during the stressor task was coded for OC. Among mothers with low levels of RF, greater increases in cortisol were associated with more displays of OC, whereas among mothers with high PRF, greater cortisol reactivity was associated with fewer OC behaviors. For low PRF mothers, higher reactivity and OC predicted lower children's PRF for their own experiences. The findings provide initial evidence for a protective function of PRF, and may point toward the importance of promoting PRF in intervention programs to reduce parental OC. (PsycINFO Database Record (c) 2017 APA, all rights reserved).
The Value of Reflective: Functioning within an Academic Therapeutic Nursery.
LaLonde, Mary M; Dreier, Mona; Aaronson, Gayle; O'Brien, John
2015-01-01
The self begins as a social self and is dependent on the other and the self-other relationship. Furthermore, shortly after birth, the intersubjective self is nurtured and sustained by the reciprocal interactions with the significant other. Recent research suggests that the significant other's reciprocity depends on his or her capacity for mentalization, and this reflective functioning capacity influences not only the child's developing sense of I, other, and we, but also his or her developing attachment pattern. Several studies have demonstrated that parental reflective functioning can be improved with intervention, and enhancing parental reflective functioning can lead to a more secure attachment pattern and better outcomes for the child and parent. Therefore, intervention with toddlers and their families requires us to consider this dynamic two-person psychology. In this paper, we describe an academic parent-child nursery program aimed at enhancing parental reflective functioning. A clinical example from the collaborative treatment of a mother and her two-year-old will demonstrate how reflective functioning can be enhanced in the parent-child dyad and lead to a more secure parent-child relationship. We will also discuss the value of reflective functioning to the interdisciplinary team and how we dealt with countertransference issues that arose during the treatment.
International Nuclear Information System (INIS)
Vagin, K. Yu.; Uryupin, S. A.
2013-01-01
The reflection of a test electromagnetic pulse from the plasma formed as a result of tunnel ionization of atoms in the field of a circularly polarized high-power radiation pulse is analyzed using the kinetic approach to describe electron motion. It is shown that the reflected pulse is significantly amplified due to the development of Weibel instability. The amplification efficiency is determined by the maximum value of the instability growth rate, which depends on the degree of anisotropy of the photoelectron distribution function
Heilpern, Tal; Manjare, Manoj; Govorov, Alexander O; Wiederrecht, Gary P; Gray, Stephen K; Harutyunyan, Hayk
2018-05-10
Developing a fundamental understanding of ultrafast non-thermal processes in metallic nanosystems will lead to applications in photodetection, photochemistry and photonic circuitry. Typically, non-thermal and thermal carrier populations in plasmonic systems are inferred either by making assumptions about the functional form of the initial energy distribution or using indirect sensors like localized plasmon frequency shifts. Here we directly determine non-thermal and thermal distributions and dynamics in thin films by applying a double inversion procedure to optical pump-probe data that relates the reflectivity changes around Fermi energy to the changes in the dielectric function and in the single-electron energy band occupancies. When applied to normal incidence measurements our method uncovers the ultrafast excitation of a non-Fermi-Dirac distribution and its subsequent thermalization dynamics. Furthermore, when applied to the Kretschmann configuration, we show that the excitation of propagating plasmons leads to a broader energy distribution of electrons due to the enhanced Landau damping.
A functional equation for the specular reflection of rays.
Le Bot, A
2002-10-01
This paper aims to generalize the "radiosity method" when applied to specular reflection. Within the field of thermics, the radiosity method is also called the "standard procedure." The integral equation for incident energy, which is usually derived for diffuse reflection, is replaced by a more appropriate functional equation. The latter is used to solve some specific problems and it is shown that all the classical features of specular reflection, for example, the existence of image sources, are embodied within this equation. This equation can be solved with the ray-tracing technique, despite the implemented mathematics being quite different. Several interesting features of the energy field are presented.
COVAL, Compound Probability Distribution for Function of Probability Distribution
International Nuclear Information System (INIS)
Astolfi, M.; Elbaz, J.
1979-01-01
1 - Nature of the physical problem solved: Computation of the probability distribution of a function of variables, given the probability distribution of the variables themselves. 'COVAL' has been applied to reliability analysis of a structure subject to random loads. 2 - Method of solution: Numerical transformation of probability distributions
Electron distribution function in laser heated plasmas
International Nuclear Information System (INIS)
Fourkal, E.; Bychenkov, V. Yu.; Rozmus, W.; Sydora, R.; Kirkby, C.; Capjack, C. E.; Glenzer, S. H.; Baldis, H. A.
2001-01-01
A new electron distribution function has been found in laser heated homogeneous plasmas by an analytical solution to the kinetic equation and by particle simulations. The basic kinetic model describes inverse bremsstrahlung absorption and electron--electron collisions. The non-Maxwellian distribution function is comprised of a super-Gaussian bulk of slow electrons and a Maxwellian tail of energetic particles. The tails are heated due to electron--electron collisions and energy redistribution between superthermal particles and light absorbing slow electrons from the bulk of the distribution function. A practical fit is proposed to the new electron distribution function. Changes to the linear Landau damping of electron plasma waves are discussed. The first evidence for the existence of non-Maxwellian distribution functions has been found in the interpretation, which includes the new distribution function, of the Thomson scattering spectra in gold plasmas [Glenzer , Phys. Rev. Lett. 82, 97 (1999)
Asymptotic functions and multiplication of distributions
International Nuclear Information System (INIS)
Todorov, T.D.
1979-01-01
Considered is a new type of generalized asymptotic functions, which are not functionals on some space of test functions as the Schwartz distributions. The definition of the generalized asymptotic functions is given. It is pointed out that in future the particular asymptotic functions will be used for solving some topics of quantum mechanics and quantum theory
Does reflective functioning mediate the relationship between attachment and personality?
Nazzaro, Maria Paola; Boldrini, Tommaso; Tanzilli, Annalisa; Muzi, Laura; Giovanardi, Guido; Lingiardi, Vittorio
2017-10-01
Mentalization, operationalized as reflective functioning (RF), can play a crucial role in the psychological mechanisms underlying personality functioning. This study aimed to: (a) study the association between RF, personality disorders (cluster level) and functioning; (b) investigate whether RF and personality functioning are influenced by (secure vs. insecure) attachment; and (c) explore the potential mediating effect of RF on the relationship between attachment and personality functioning. The Shedler-Westen Assessment Procedure (SWAP-200) was used to assess personality disorders and levels of psychological functioning in a clinical sample (N = 88). Attachment and RF were evaluated with the Adult Attachment Interview (AAI) and Reflective Functioning Scale (RFS). Findings showed that RF had significant negative associations with cluster A and B personality disorders, and a significant positive association with psychological functioning. Moreover, levels of RF and personality functioning were influenced by attachment patterns. Finally, RF completely mediated the relationship between (secure/insecure) attachment and adaptive psychological features, and thus accounted for differences in overall personality functioning. Lack of mentalization seemed strongly associated with vulnerabilities in personality functioning, especially in patients with cluster A and B personality disorders. These findings provide support for the development of therapeutic interventions to improve patients' RF. Copyright © 2017 Elsevier B.V. All rights reserved.
Reflective functioning and attachment in adolescent eating disorders
Siddell, Laurette
2017-01-01
Introduction: A systematic review was undertaken to identify any psychological predictors of treatment dropout for individuals diagnosed with an eating disorder, to help inform psychological therapy and reduce attrition. An empirical study was conducted to understand developmental psychological mechanisms at play in the aetiology and maintenance of eating disordered symptomology by assessing reflective functioning and attachment from a trans-diagnostic perspective. Method...
Empirical distribution function under heteroscedasticity
Czech Academy of Sciences Publication Activity Database
Víšek, Jan Ámos
2011-01-01
Roč. 45, č. 5 (2011), s. 497-508 ISSN 0233-1888 Grant - others:GA UK(CZ) GA402/09/0557 Institutional research plan: CEZ:AV0Z10750506 Keywords : Robustness * Convergence * Empirical distribution * Heteroscedasticity Subject RIV: BB - Applied Statistics , Operational Research Impact factor: 0.724, year: 2011 http://library.utia.cas.cz/separaty/2011/SI/visek-0365534.pdf
Positivity of time-frequency distribution functions
Janssen, A.J.E.M.
1988-01-01
This paper deals with the question how various 'natural' conditions posed on time-frequency distribution functions prevent them to be nonnegative everywhere for all signals. The attention is restricted mainly to distribution functions that involve the signal bilinearly. This paper summarizes and
Borelli, Jessica L.; Hong, Kajung; Rasmussen, Hannah F.; Smiley, Patricia A.
2017-01-01
Theorists argue that parental reflective functioning (PRF) is activated in response to emotions, potentially supporting parenting sensitivity even when arousal is high. That is, when parents become emotionally reactive when interacting with their children, those who can use PRF to understand their children's mental states should be able to parent…
Highly reflective polymeric substrates functionalized utilizing atomic layer deposition
Zuzuarregui, Ana; Coto, Borja; Rodríguez, Jorge; Gregorczyk, Keith E.; Ruiz de Gopegui, Unai; Barriga, Javier; Knez, Mato
2015-08-01
Reflective surfaces are one of the key elements of solar plants to concentrate energy in the receivers of solar thermal electricity plants. Polymeric substrates are being considered as an alternative to the widely used glass mirrors due to their intrinsic and processing advantages, but optimizing both the reflectance and the physical stability of polymeric mirrors still poses technological difficulties. In this work, polymeric surfaces have been functionalized with ceramic thin-films by atomic layer deposition. The characterization and optimization of the parameters involved in the process resulted in surfaces with a reflection index of 97%, turning polymers into a real alternative to glass substrates. The solution we present here can be easily applied in further technological areas where seemingly incompatible combinations of polymeric substrates and ceramic coatings occur.
Highly reflective polymeric substrates functionalized utilizing atomic layer deposition
Energy Technology Data Exchange (ETDEWEB)
Zuzuarregui, Ana, E-mail: a.zuzuarregui@nanogune.eu; Gregorczyk, Keith E. [CIC Nanogune Consolider, de Tolosa Hiribidea 76, 20018 San Sebastián (Spain); Coto, Borja; Ruiz de Gopegui, Unai; Barriga, Javier [IK4-Tekniker, Iñaki Goenaga 5, 20600 Eibar (Spain); Rodríguez, Jorge [Torresol Energy (SENER Group), Avda. de Zugazarte 61, 48930 Las Arenas (Spain); Knez, Mato [CIC Nanogune Consolider, de Tolosa Hiribidea 76, 20018 San Sebastián (Spain); IKERBASQUE Basque Foundation for Science, Maria Diaz de Haro 3, 48013 Bilbao (Spain)
2015-08-10
Reflective surfaces are one of the key elements of solar plants to concentrate energy in the receivers of solar thermal electricity plants. Polymeric substrates are being considered as an alternative to the widely used glass mirrors due to their intrinsic and processing advantages, but optimizing both the reflectance and the physical stability of polymeric mirrors still poses technological difficulties. In this work, polymeric surfaces have been functionalized with ceramic thin-films by atomic layer deposition. The characterization and optimization of the parameters involved in the process resulted in surfaces with a reflection index of 97%, turning polymers into a real alternative to glass substrates. The solution we present here can be easily applied in further technological areas where seemingly incompatible combinations of polymeric substrates and ceramic coatings occur.
Highly reflective polymeric substrates functionalized utilizing atomic layer deposition
International Nuclear Information System (INIS)
Zuzuarregui, Ana; Gregorczyk, Keith E.; Coto, Borja; Ruiz de Gopegui, Unai; Barriga, Javier; Rodríguez, Jorge; Knez, Mato
2015-01-01
Reflective surfaces are one of the key elements of solar plants to concentrate energy in the receivers of solar thermal electricity plants. Polymeric substrates are being considered as an alternative to the widely used glass mirrors due to their intrinsic and processing advantages, but optimizing both the reflectance and the physical stability of polymeric mirrors still poses technological difficulties. In this work, polymeric surfaces have been functionalized with ceramic thin-films by atomic layer deposition. The characterization and optimization of the parameters involved in the process resulted in surfaces with a reflection index of 97%, turning polymers into a real alternative to glass substrates. The solution we present here can be easily applied in further technological areas where seemingly incompatible combinations of polymeric substrates and ceramic coatings occur
Asymptotic numbers, asymptotic functions and distributions
International Nuclear Information System (INIS)
Todorov, T.D.
1979-07-01
The asymptotic functions are a new type of generalized functions. But they are not functionals on some space of test-functions as the distributions of Schwartz. They are mappings of the set denoted by A into A, where A is the set of the asymptotic numbers introduced by Christov. On its part A is a totally-ordered set of generalized numbers including the system of real numbers R as well as infinitesimals and infinitely large numbers. Every two asymptotic functions can be multiplied. On the other hand, the distributions have realizations as asymptotic functions in a certain sense. (author)
Efective infrared reflectivity and dielectric function of polycrystalline alumina ceramics
Czech Academy of Sciences Publication Activity Database
Nuzhnyy, Dmitry; Petzelt, Jan; Borodavka, Fedir; Vaněk, Přemysl; Šimek, Daniel; Trunec, D.; Maca, K.
2017-01-01
Roč. 254, č. 5 (2017), s. 1-8, č. článku 1600607. ISSN 0370-1972 R&D Projects: GA ČR GA15-08389S Institutional support: RVO:68378271 Keywords : alumina * ceramics * effective dielectric function * effective medium approximation * geometrical resonances * infrared reflectivity Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 1.674, year: 2016
Scaling function, spectral function and nucleon momentum distribution in nuclei
International Nuclear Information System (INIS)
Antonov, A.N.; Ivanov, M.V.; Caballero, J.A.; Barbaro, M.B.; Udias, J.M.; Moya de Guerra, E.; Donnelly, T.W.
2010-01-01
The aim of the study is to find a good simultaneous description of the spectral function and the momentum distribution in relation to the realistic scaling function obtained from inclusive electron-nuclei scattering experiments. We start with a modified Hartree-Fock spectral function in which the energy dependent part (δ-function) is replaced by the Gaussian distributions with hole state widths as free parameters. We calculate the scaling function and the nucleon momentum distribution on the basis of the spectral function constructed in this way, trying to find a good description of the experimental data. The obtained scaling function has a weak asymmetry and the momentum distribution has not got a high-momentum tail in the case when harmonic-oscillator single-particle wave functions are used. So, to improve the behavior of the momentum distribution we used the basis of natural orbitals (NO) in which short-range correlations are partly incorporated. The results for the scaling function show again a weak asymmetry, but in this case the momentum distribution has a high-momentum tail. As a next step we include final-state interactions (FSI) in the calculations to reproduce the experimentally observed asymmetry of the scaling function. (author)
Costa Gondim, João José; de Oliveira Albuquerque, Robson; Clayton Alves Nascimento, Anderson; García Villalba, Luis Javier; Kim, Tai-Hoon
2016-11-04
Concerns about security on Internet of Things (IoT) cover data privacy and integrity, access control, and availability. IoT abuse in distributed denial of service attacks is a major issue, as typical IoT devices' limited computing, communications, and power resources are prioritized in implementing functionality rather than security features. Incidents involving attacks have been reported, but without clear characterization and evaluation of threats and impacts. The main purpose of this work is to methodically assess the possible impacts of a specific class-amplified reflection distributed denial of service attacks (AR-DDoS)-against IoT. The novel approach used to empirically examine the threat represented by running the attack over a controlled environment, with IoT devices, considered the perspective of an attacker. The methodology used in tests includes that perspective, and actively prospects vulnerabilities in computer systems. This methodology defines standardized procedures for tool-independent vulnerability assessment based on strategy, and the decision flows during execution of penetration tests (pentests). After validation in different scenarios, the methodology was applied in amplified reflection distributed denial of service (AR-DDoS) attack threat assessment. Results show that, according to attack intensity, AR-DDoS saturates reflector infrastructure. Therefore, concerns about AR-DDoS are founded, but expected impact on abused IoT infrastructure and devices will be possibly as hard as on final victims.
Directory of Open Access Journals (Sweden)
João José Costa Gondim
2016-11-01
Full Text Available Concerns about security on Internet of Things (IoT cover data privacy and integrity, access control, and availability. IoT abuse in distributed denial of service attacks is a major issue, as typical IoT devices’ limited computing, communications, and power resources are prioritized in implementing functionality rather than security features. Incidents involving attacks have been reported, but without clear characterization and evaluation of threats and impacts. The main purpose of this work is to methodically assess the possible impacts of a specific class–amplified reflection distributed denial of service attacks (AR-DDoS–against IoT. The novel approach used to empirically examine the threat represented by running the attack over a controlled environment, with IoT devices, considered the perspective of an attacker. The methodology used in tests includes that perspective, and actively prospects vulnerabilities in computer systems. This methodology defines standardized procedures for tool-independent vulnerability assessment based on strategy, and the decision flows during execution of penetration tests (pentests. After validation in different scenarios, the methodology was applied in amplified reflection distributed denial of service (AR-DDoS attack threat assessment. Results show that, according to attack intensity, AR-DDoS saturates reflector infrastructure. Therefore, concerns about AR-DDoS are founded, but expected impact on abused IoT infrastructure and devices will be possibly as hard as on final victims.
Costa Gondim, João José; de Oliveira Albuquerque, Robson; Clayton Alves Nascimento, Anderson; García Villalba, Luis Javier; Kim, Tai-Hoon
2016-01-01
Concerns about security on Internet of Things (IoT) cover data privacy and integrity, access control, and availability. IoT abuse in distributed denial of service attacks is a major issue, as typical IoT devices’ limited computing, communications, and power resources are prioritized in implementing functionality rather than security features. Incidents involving attacks have been reported, but without clear characterization and evaluation of threats and impacts. The main purpose of this work is to methodically assess the possible impacts of a specific class–amplified reflection distributed denial of service attacks (AR-DDoS)–against IoT. The novel approach used to empirically examine the threat represented by running the attack over a controlled environment, with IoT devices, considered the perspective of an attacker. The methodology used in tests includes that perspective, and actively prospects vulnerabilities in computer systems. This methodology defines standardized procedures for tool-independent vulnerability assessment based on strategy, and the decision flows during execution of penetration tests (pentests). After validation in different scenarios, the methodology was applied in amplified reflection distributed denial of service (AR-DDoS) attack threat assessment. Results show that, according to attack intensity, AR-DDoS saturates reflector infrastructure. Therefore, concerns about AR-DDoS are founded, but expected impact on abused IoT infrastructure and devices will be possibly as hard as on final victims. PMID:27827931
Teachers' reflections on distributive leadership in public primary ...
African Journals Online (AJOL)
The findings revealed that leadership in Soweto primary schools is rooted in classical leadership practices and that any potential for the practice of distributive leadership is hindered by autocratic styles of leadership, hierarchical structures, and non-participative decision-making. Keywords: Activity Theory, collective ...
Angular distribution of diffuse reflectance from incoherent multiple scattering in turbid media.
Gao, M; Huang, X; Yang, P; Kattawar, G W
2013-08-20
The angular distribution of diffuse reflection is elucidated with greater understanding by studying a homogeneous turbid medium. We modeled the medium as an infinite slab and studied the reflection dependence on the following three parameters: the incident direction, optical depth, and asymmetry factor. The diffuse reflection is produced by incoherent multiple scattering and is solved through radiative transfer theory. At large optical depths, the angular distribution of the diffuse reflection with small incident angles is similar to that of a Lambertian surface, but, with incident angles larger than 60°, the angular distributions have a prominent reflection peak around the specular reflection angle. These reflection peaks are found originating from the scattering within one transport mean free path in the top layer of the medium. The maximum reflection angles for different incident angles are analyzed and can characterize the structure of angular distributions for different asymmetry factors and optical depths. The properties of the angular distribution can be applied to more complex systems for a better understanding of diffuse reflection.
Attachment Patterns and Reflective Functioning in traumatised refugees
DEFF Research Database (Denmark)
Riber, Karin
2013-01-01
psychotherapy research has shown is central to change and effect. Aims: 1) To examine attachment patterns and reflective functioning in traumatised refugees with PTSD, and 2) shed light on their significance to therapeutic alliance and treatment effect. Methods: All Arabic speaking patients in the study......Traumatized refugees have often suffered severe, prolonged, repeated traumas and pose a challenge to treatment. Attachment patterns and level of mentalizing seem to work as protection mechanisms in traumatizing events and to be important for positively utilizing the therapeutic alliance which...
Phenomenological relation between distribution and fragmentation functions
International Nuclear Information System (INIS)
Ma Boqiang; Schmidt, Ivan; Soffer, Jacques; Yang Jianjun
2002-01-01
We study the relation between the quark distribution function q(x) and the fragmentation function D q (z) based on a general form D q (x)=C(z)z α q(z) for valence and sea quarks. By adopting two known parametrizations of quark distributions for the proton, we find three simple options for the fragmentation functions that can provide a good description of the available experimental data on proton production in e + e - inelastic annihilation. These three options support the revised Gribov-Lipatov relation D q (z)=zq(z) at z→1, as an approximate relation for the connection between distribution and fragmentation functions. The three options differ in the sea contributions and lead to distinct predictions for antiproton production in the reaction p+p→p-bar+X, thus they are distinguishable in future experiments at RHIC-BNL
Environmental DNA reflects spatial and temporal jellyfish distribution.
Directory of Open Access Journals (Sweden)
Toshifumi Minamoto
Full Text Available Recent development of environmental DNA (eDNA analysis allows us to survey underwater macro-organisms easily and cost effectively; however, there have been no reports on eDNA detection or quantification for jellyfish. Here we present the first report on an eDNA analysis of marine jellyfish using Japanese sea nettle (Chrysaora pacifica as a model species by combining a tank experiment with spatial and temporal distribution surveys. We performed a tank experiment monitoring eDNA concentrations over a range of time intervals after the introduction of jellyfish, and quantified the eDNA concentrations by quantitative real-time PCR. The eDNA concentrations peaked twice, at 1 and 8 h after the beginning of the experiment, and became stable within 48 h. The estimated release rates of the eDNA in jellyfish were higher than the rates previously reported in fishes. A spatial survey was conducted in June 2014 in Maizuru Bay, Kyoto, in which eDNA was collected from surface water and sea floor water samples at 47 sites while jellyfish near surface water were counted on board by eye. The distribution of eDNA in the bay corresponded with the distribution of jellyfish inferred by visual observation, and the eDNA concentration in the bay was ~13 times higher on the sea floor than on the surface. The temporal survey was conducted from March to November 2014, in which jellyfish were counted by eye every morning while eDNA was collected from surface and sea floor water at three sampling points along a pier once a month. The temporal fluctuation pattern of the eDNA concentrations and the numbers of observed individuals were well correlated. We conclude that an eDNA approach is applicable for jellyfish species in the ocean.
Convolution of Distribution-Valued Functions. Applications.
BARGETZ, CHRISTIAN
2011-01-01
In this article we examine products and convolutions of vector-valued functions. For nuclear normal spaces of distributions Proposition 25 in [31,p. 120] yields a vector-valued product or convolution if there is a continuous product or convolution mapping in the range of the vector-valued functions. For specific spaces, we generalize this result to hypocontinuous bilinear maps at the expense of generality with respect to the function space. We consider holomorphic, meromorphic and differentia...
Personality Is Reflected in the Brain's Intrinsic Functional Architecture
Adelstein, Jonathan S.; Shehzad, Zarrar; Mennes, Maarten; DeYoung, Colin G.; Zuo, Xi-Nian; Kelly, Clare; Margulies, Daniel S.; Bloomfield, Aaron; Gray, Jeremy R.; Castellanos, F. Xavier; Milham, Michael P.
2011-01-01
Personality describes persistent human behavioral responses to broad classes of environmental stimuli. Investigating how personality traits are reflected in the brain's functional architecture is challenging, in part due to the difficulty of designing appropriate task probes. Resting-state functional connectivity (RSFC) can detect intrinsic activation patterns without relying on any specific task. Here we use RSFC to investigate the neural correlates of the five-factor personality domains. Based on seed regions placed within two cognitive and affective ‘hubs’ in the brain—the anterior cingulate and precuneus—each domain of personality predicted RSFC with a unique pattern of brain regions. These patterns corresponded with functional subdivisions responsible for cognitive and affective processing such as motivation, empathy and future-oriented thinking. Neuroticism and Extraversion, the two most widely studied of the five constructs, predicted connectivity between seed regions and the dorsomedial prefrontal cortex and lateral paralimbic regions, respectively. These areas are associated with emotional regulation, self-evaluation and reward, consistent with the trait qualities. Personality traits were mostly associated with functional connections that were inconsistently present across participants. This suggests that although a fundamental, core functional architecture is preserved across individuals, variable connections outside of that core encompass the inter-individual differences in personality that motivate diverse responses. PMID:22140453
Personality is reflected in the brain's intrinsic functional architecture.
Directory of Open Access Journals (Sweden)
Jonathan S Adelstein
Full Text Available Personality describes persistent human behavioral responses to broad classes of environmental stimuli. Investigating how personality traits are reflected in the brain's functional architecture is challenging, in part due to the difficulty of designing appropriate task probes. Resting-state functional connectivity (RSFC can detect intrinsic activation patterns without relying on any specific task. Here we use RSFC to investigate the neural correlates of the five-factor personality domains. Based on seed regions placed within two cognitive and affective 'hubs' in the brain--the anterior cingulate and precuneus--each domain of personality predicted RSFC with a unique pattern of brain regions. These patterns corresponded with functional subdivisions responsible for cognitive and affective processing such as motivation, empathy and future-oriented thinking. Neuroticism and Extraversion, the two most widely studied of the five constructs, predicted connectivity between seed regions and the dorsomedial prefrontal cortex and lateral paralimbic regions, respectively. These areas are associated with emotional regulation, self-evaluation and reward, consistent with the trait qualities. Personality traits were mostly associated with functional connections that were inconsistently present across participants. This suggests that although a fundamental, core functional architecture is preserved across individuals, variable connections outside of that core encompass the inter-individual differences in personality that motivate diverse responses.
The parental reflective functioning questionnaire: Development and preliminary validation
Luyten, Patrick; Mayes, Linda C.; Nijssens, Liesbet; Fonagy, Peter
2017-01-01
This paper reports on three studies on the development and validation of the Parental Reflective Functioning Questionnaire (PRFQ), a brief, multidimensional self-report measure that assesses parental reflective functioning or mentalizing, that is, the capacity to treat the infant as a psychological agent. Study 1 investigated the factor structure, reliability, and relationships of the PRFQ with demographic features, symptomatic distress, attachment dimensions, and emotional availability in a socially diverse sample of 299 mothers of a child aged 0–3. In Study 2, the factorial invariance of the PRFQ in mothers and fathers was investigated in a sample of 153 first-time parents, and relationships with demographic features, symptomatic distress, attachment dimensions, and parenting stress were investigated. Study 3 investigated the relationship between the PRFQ and infant attachment classification as assessed with the Strange Situation Procedure (SSP) in a sample of 136 community mothers and their infants. Exploratory and confirmatory factor analyses suggested three theoretically consistent factors assessing pre-mentalizing modes, certainty about the mental states of the infant, and interest and curiosity in the mental states of the infant. These factors were generally related in theoretically expected ways to parental attachment dimensions, emotional availability, parenting stress, and infant attachment status in the SSP. Yet, at the same time, more research on the PRFQ is needed to further establish its reliability and validity. PMID:28472162
Wigner distribution function for an oscillator
International Nuclear Information System (INIS)
Davies, R.W.; Davies, K.T.R.
1975-01-01
We present two new derivations of the Wigner distribution function for a simple harmonic oscillator Hamiltonian. Both methods are facilitated using a formula which expresses the Wigner function as a simple trace. The first method of derivation utilizes a modification of a theorem due to Messiah. An alternative procedure makes use of the coherent state representation of an oscillator. The Wigner distribution function gives a semiclassical joint probability for finding the system with given coordinates and momenta, and the joint probability is factorable for the special case of an oscillator. An important application of this result occurs in the theory of nuclear fission for calculating the probability distributions for the masses, kinetic energies, and vibrational energies of the fission fragments at infinite separation. (U.S.)
Sewage reflects the distribution of human faecal Lachnospiraceae
McLellan, Sandra L.; Newton, Ryan J.; Vandewalle, Jessica L.; Shanks, Orin C.; Huse, Susan M.; Eren, A. Murat; Sogin, Mitchell L.
2014-01-01
Summary Faecal pollution contains a rich and diverse community of bacteria derived from animals and humans, many of which might serve as alternatives to the traditional enterococci and Escherichia coli faecal indicators. We used massively parallel sequencing (MPS) of the 16S rRNA gene to characterize microbial communities from wastewater treatment plant (WWTP) influent sewage from 12 cities geographically distributed across the USA. We examined members of the Clostridiales, which included the families Clostridiaceae, Lachnospiraceae and Ruminococcaceae for their potential as sewage indicators. Lachnospiraceae was one of the most abundant groups of faecal bacteria in sewage, and several Lachnospiraceae high-abundance sewage pyrotags occurred in at least 46 of 48 human faecal samples. Clone libraries targeting Clostridium coccoides (C. coccoides) in sewage samples demonstrated that Lachnospiraceae-annotated V6 pyrotags encompassed the previously reported C. coccoides group. We used oligotyping to profile the genus Blautia within Lachnospiraceae and found oligotypes comprised of 24 entropy components that showed patterns of host specificity. These findings suggest that indicators based on Blautia might have the capacity to discriminate between different faecal pollution sources. Development of source-specific alternative indicators would enhance water quality assessments, which leads to improved ecosystem health and reduced human health risk due to waterborne disease. PMID:23438335
Distribution function of faint galaxy numbers
International Nuclear Information System (INIS)
Fesenko, L.M.
1981-01-01
The Lick observatory counts of galaxies are considered. The distribution of number of galaxies in elementary regions (ER) of 1 degx1 deg is investigated. Each field of 6 degx6 deg was treated separately At b>40 deg the probab+lity to observe of n galaxies in ER is an exponential decreasing function of n, if unequality n> were fulfilled. The mean apparent multiplicity of a galaxy (2.8+-0.9) was derived. The galaxy number distribution was simple model for the number of various systems of galaxies. The supperclustering of galaxies was not introduced. Based on that model the approximate expression for galaxy number distribution was considered and was compared with observed distributions. The agreement between these distributions become better with reducing of the interstellar absorption of light
New generalized functions and multiplication of distributions
International Nuclear Information System (INIS)
Colombeau, J.F.
1984-01-01
Since its conception, Quantum Field Theory is based on 'heuristic' computations (in particular products of distributions) that, despite lots of effort, remained meaningless from a mathematical viewpoint. In this book the author presents a new mathematical theory giving a rigorous mathematical sense to these heuristic computations and, from a mathematical viewpoint, to all products of distributions. This new mathematical theory is a new theory of Generalized Functions defined on any open subset Ω of Rsup(n), which are much more general than the distributions on Ω. (Auth.)
Equilibrium distribution function in collisionless systems
International Nuclear Information System (INIS)
Pergamenshchik, V.M.
1988-01-01
Collisionless systems of a large number of N particles interacting by Coulomb forces are widely spread in cosmic and laboratory plasma. A statistical theory of equilibrium state of collisionless Coulomb systems which evolution obeys Vlasov equation is proposed. The developed formalism permits a sequential consideration of such distributed in one-particle six-dimensional phase space of a system and to obtain a simple result: equilibrium distribution function has the form of Fermi-Dirac distribution and doesn't depend on initial state factors
Dynamic radial distribution function from inelastic neutron scattering
International Nuclear Information System (INIS)
McQueeney, R.J.
1998-01-01
A real-space, local dynamic structure function g(r,ω) is defined from the dynamic structure function S(Q,ω), which can be measured using inelastic neutron scattering. At any particular frequency ω, S(Q,ω) contains Q-dependent intensity oscillations which reflect the spatial distribution and relative displacement directions for the atoms vibrating at that frequency. Information about local and dynamic atomic correlations is obtained from the Fourier transform of these oscillations g(r,ω) at the particular frequency. g(r,ω) can be formulated such that the elastic and frequency-summed limits correspond to the average and instantaneous radial distribution function, respectively, and is thus called the dynamic radial distribution function. As an example, the dynamic radial distribution function is calculated for fcc nickel in a model which considers only the harmonic atomic displacements due to phonons. The results of these calculations demonstrate that the magnitude of the atomic correlations can be quantified and g(r,ω) is a well-defined correlation function. This leads to a simple prescription for investigating local lattice dynamics. copyright 1998 The American Physical Society
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...
Electron distribution functions in Io plasma torus
International Nuclear Information System (INIS)
Boev, A.G.
2003-01-01
Electron distribution functions measured by the Voyager 1 in different shares of the Io plasma torus are explained. It is proved that their suprathermal tails are formed by the electrical field induced by the 'Jupiter wind'. The Maxwellian parts of all these spectra characterize thermal equilibrium populations of electrons and the radiation of exited ions
Electron energy-distribution functions in gases
International Nuclear Information System (INIS)
Pitchford, L.C.
1981-01-01
Numerical calculation of the electron energy distribution functions in the regime of drift tube experiments is discussed. The discussion is limited to constant applied fields and values of E/N (ratio of electric field strength to neutral density) low enough that electron growth due to ionization can be neglected
Natural Microbial Assemblages Reflect Distinct Organismal and Functional Partitioning
Wilmes, P.; Andersson, A.; Kalnejais, L. H.; Verberkmoes, N. C.; Lefsrud, M. G.; Wexler, M.; Singer, S. W.; Shah, M.; Bond, P. L.; Thelen, M. P.; Hettich, R. L.; Banfield, J. F.
2007-12-01
The ability to link microbial community structure to function has long been a primary focus of environmental microbiology. With the advent of community genomic and proteomic techniques, along with advances in microscopic imaging techniques, it is now possible to gain insights into the organismal and functional makeup of microbial communities. Biofilms growing within highly acidic solutions inside the Richmond Mine (Iron Mountain, Redding, California) exhibit distinct macro- and microscopic morphologies. They are composed of microorganisms belonging to the three domains of life, including archaea, bacteria and eukarya. The proportion of each organismal type depends on sampling location and developmental stage. For example, mature biofilms floating on top of acid mine drainage (AMD) pools exhibit layers consisting of a densely packed bottom layer of the chemoautolithotroph Leptospirillum group II, a less dense top layer composed mainly of archaea, and fungal filaments spanning across the entire biofilm. The expression of cytochrome 579 (the most highly abundant protein in the biofilm, believed to be central to iron oxidation and encoded by Leptospirillum group II) is localized at the interface of the biofilm with the AMD solution, highlighting that biofilm architecture is reflected at the functional gene expression level. Distinct functional partitioning is also apparent in a biological wastewater treatment system that selects for distinct polyphosphate accumulating organisms. Community genomic data from " Candidatus Accumulibacter phosphatis" dominated activated sludge has enabled high mass-accuracy shotgun proteomics for identification of key metabolic pathways. Comprehensive genome-wide alignment of orthologous proteins suggests distinct partitioning of protein variants involved in both core-metabolism and specific metabolic pathways among the dominant population and closely related species. In addition, strain- resolved proteogenomic analysis of the AMD biofilms
Distribution functions and thermodynamic functions of many particle systems
International Nuclear Information System (INIS)
Isihara, A.; Rosa Junior, S.G.
1976-01-01
A method is given of determining and upper bound of the entropy of a classical interacting system. A family of gaussian trial distribution functions is introduced for an electron gas. It was found that the ring diagram energy corresponds to the minimum free energy which the family produces. In contrast to the ring diagram method, the new approach is extremely simple and general [pt
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.
DISTRIBUTED RC NETWORKS WITH RATIONAL TRANSFER FUNCTIONS,
A distributed RC circuit analogous to a continuously tapped transmission line can be made to have a rational short-circuit transfer admittance and...one rational shortcircuit driving-point admittance. A subcircuit of the same structure has a rational open circuit transfer impedance and one rational ...open circuit driving-point impedance. Hence, rational transfer functions may be obtained while considering either generator impedance or load
Survival Function Analysis of Planet Size Distribution
Zeng, Li; Jacobsen, Stein B.; Sasselov, Dimitar D.; Vanderburg, Andrew
2018-01-01
Applying the survival function analysis to the planet radius distribution of the Kepler exoplanet candidates, we have identified two natural divisions of planet radius at 4 Earth radii and 10 Earth radii. These divisions place constraints on planet formation and interior structure model. The division at 4 Earth radii separates small exoplanets from large exoplanets above. When combined with the recently-discovered radius gap at 2 Earth radii, it supports the treatment of planets 2-4 Earth rad...
REFLECTIVE FUNCTIONING AND PERSONALITY ORGANIZATION: ASSOCIATIONS WITH NEGATIVE MATERNAL BEHAVIORS.
Ensink, Karin; Rousseau, Marie-Eve; Biberdzic, Marko; Bégin, Michaël; Normandin, Lina
2017-05-01
The aim of this study was to examine whether mothers who manifest insensitive and disconnected behaviors in interaction with their infants differ in terms of maternal reflective functioning (RF), personality organization, and histories of abuse. A total of 86 mother-infant dyads, 28 of them with histories of abuse, participated in the study. RF was assessed with the Adult Attachment Interview (C. George, N. Kaplan, & M. Main, 1985), and personality organization was assessed with the self-report Inventory of Personality Organization (M.F. Lenzenweger, J.F. Clarkin, O.F. Kernberg, & P.A. Foelsh, 2001; L. Normandin et al., 2002), before the birth of the baby. Maternal behaviors were assessed using the Disconnected and Extremely Insensitive Parenting measure when the infants were 15 to 18 months old. The results of multivariate analyses of covariance indicate that both RF and personality organization were associated with disconnected and extremely insensitive maternal behaviors. Mothers classified as presenting intrusive/aggressive behaviors had significantly lower RF as well as significantly more difficulties in personality organization, including reality testing, identity, and defense mechanisms. Withdrawn and disconnected maternal behaviors were associated with the combination of difficulties in mentalization and personality organization rather than difficulties in one specific area. In sum, the study provides new evidence regarding the importance of a mentalizing stance about early attachment relationships for the modulation of maternal behaviors, especially intrusive/aggressive behaviors. © 2017 Michigan Association for Infant Mental Health.
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.
Wireless distributed functional electrical stimulation system.
Jovičić, Nenad S; Saranovac, Lazar V; Popović, Dejan B
2012-08-09
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. 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. 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. 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.
Investigation of omnidirectional reflection band in ZnTe/ZnSe distributed Bragg reflector
Energy Technology Data Exchange (ETDEWEB)
Huang, Ying-Shin [Department of Electrical Engineering, National Taiwan Ocean University, Keelung 20224, Taiwan (China); Hu, Sheng-Yao [Department of Digital Technology Design, Tungfang Design University, Kaohsiung 82941, Taiwan (China); Lee, Yueh-Chien, E-mail: jacklee@mail.tnu.edu.tw [Department of Electronic Engineering, Tungnan University, New Taipei City 22202, Taiwan (China); Chang, Chung-Cheng; Tiong, Kwong-Kau [Department of Electrical Engineering, National Taiwan Ocean University, Keelung 20224, Taiwan (China); Shen, Ji-Lin [Department of Physics, Chung Yuan Christian University, Chung-Li 32023, Taiwan (China); Chou, Wu-Ching [Department of Electrophysics, National Chiao Tung University, Hsinchu 30010, Taiwan (China)
2015-11-15
We report the characteristics of reflectance spectra of the 15- and 20-period ZnTe/ZnSe distributed Bragg reflector grown on GaAs (001) substrates by molecular beam epitaxy. The reflectance spectra measured at various incident angles and polarizations were investigated by the theoretical curves simulated using transfer matrix method. The wavelength variation of the refractive indices described by Sellmeier equation and random thickness model were also considered for the interpretation of the experimentally observed curves. An omnidirectional reflection range defined from the edge of incident-angle-dependent reflection band with TE and TM polarizations is about 15 nm, and is consistent with the observed experimental curves. The results showed that the selected ZnTe and ZnSe materials are suitable for constructing multilayer structures having omnidirectional reflection band. - Highlights: • ZnTe/ZnSe distributed Bragg reflector grown by molecular beam epitaxy. • The reflectance spectra are measured at various incidence angles and polarizations. • The theoretical curves are considered by Sellmeier and random thickness models. • An observed omnidirectional reflection range in ZnTe/ZnSe DBR is about 15 nm.
Effects of temporal distribution of specular and diffuse reflections on perceived music quality
Smitthakorn, Pattra
The purpose of this study was to investigate the effects of the temporal distribution of diffuse and specular reflections on the perceived acoustic qualities of music performance. Sets of impulse responses were designed with different temporal distributions of early acoustic energy (specular and diffuse reflections). Then, three types of anechoic sound sources---orchestral music, trumpet, and piano---were convolved with the designed impulse responses. The results from the listening tests revealed that different room environments were needed to acoustically support different source characteristics. The results show the following: (1) specular reflections arriving within 40 msec of the direct sound improved perceived "clarity" and "intimacy"; (2) specular reflections arriving between 40-80 msec after the direct sound improved perceived "clarity" for orchestral music; (3) specular reflections arriving later than 80 msec after the direct sound are not desirable; (4) large numbers of diffuse reflections arriving within 40 and 80 msec of the direct sound improved perceived "intimacy", "texture", and "overall impression" for all sound sources, heightened perceived "clarity" for trumpet and piano, and reduced perceived "glare" for trumpet; and (5) diffuse reflections arriving between 80-160 msec of the direct sound preserved perceived "reverberance" and reduced perceived "echoes" as opposed to specular reflections arriving in the same time period. The results of this study indicate that music performance halls should be designed to include diffuse reflections from surfaces within the 80 msec time period to achieve preferred texture, intimacy, clarity and overall impression and in the 160 msec time period to reduce echoes; specular reflections arriving within the 40 msec time period should be provided to enhance perceived clarity.
Directory of Open Access Journals (Sweden)
Joanne Embree
2001-01-01
Full Text Available Ideally, editorials are written one to two months before publication in the Journal. It was my turn to write this one. I had planned to write the first draft the evening after my clinic on Tuesday, September 11. It didn't get done that night or during the next week. Somehow, the topic that I had originally chosen just didn't seem that important anymore as I, along my friends and colleagues, reflected on the changes that the events of that day were likely to have on our lives.
High reflectivity YDH/SiO2 distributed Bragg reflector for UV-C wavelength regime
Alias, Mohd Sharizal; Alatawi, Abdullah; Wong, Ka Chun; Tangi, Malleswararao; Holguin Lerma, Jorge Alberto; Stegenburgs, Edgars; Shakfa, Mohammad Khaled; Ng, Tien Khee; Rahman, Abdul; Alyamani, Ahmed; Ooi, Boon S.
2018-01-01
A distributed Bragg reflector (DBR) composed of Y2O3-doped HfO2 (YDH)/SiO2 layers with high reflectivity spectrum centered at a wavelength of ~240 nm is deposited using radio-frequency magnetron sputtering. Before the DBR deposition, optical
International Nuclear Information System (INIS)
Naumis, Gerardo G.; Bazan, A.; Torres, M.; Aragon, J.L.; Quintero-Torres, R.
2008-01-01
One of the few examples in which the physical properties of an incommensurable system reflect an underlying higher dimensionality is presented. Specifically, we show that the reflectivity distribution of an incommensurable one-dimensional cavity is given by the density of states of a tight-binding Hamiltonian in a two-dimensional triangular lattice. Such effect is due to an independent phase decoupling of the scattered waves, produced by the incommensurable nature of the system, which mimics a random noise generator. This principle can be applied to design a cavity that avoids resonant reflections for almost any incident wave. An optical analogy, by using three mirrors with incommensurable distances between them, is also presented. Such array produces a countable infinite fractal set of reflections, a phenomena which is opposite to the effect of optical invisibility
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.
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
Time evolution of distribution functions in dissipative environments
International Nuclear Information System (INIS)
Hu Li-Yun; Chen Fei; Wang Zi-Sheng; Fan Hong-Yi
2011-01-01
By introducing the thermal entangled state representation, we investigate the time evolution of distribution functions in the dissipative channels by bridging the relation between the initial distribution function and the any time distribution function. We find that most of them are expressed as such integrations over the Laguerre—Gaussian function. Furthermore, as applications, we derive the time evolution of photon-counting distribution by bridging the relation between the initial distribution function and the any time photon-counting distribution, and the time evolution of R-function characteristic of nonclassicality depth. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)
Audio feature extraction using probability distribution function
Suhaib, A.; Wan, Khairunizam; Aziz, Azri A.; Hazry, D.; Razlan, Zuradzman M.; Shahriman A., B.
2015-05-01
Voice recognition has been one of the popular applications in robotic field. It is also known to be recently used for biometric and multimedia information retrieval system. This technology is attained from successive research on audio feature extraction analysis. Probability Distribution Function (PDF) is a statistical method which is usually used as one of the processes in complex feature extraction methods such as GMM and PCA. In this paper, a new method for audio feature extraction is proposed which is by using only PDF as a feature extraction method itself for speech analysis purpose. Certain pre-processing techniques are performed in prior to the proposed feature extraction method. Subsequently, the PDF result values for each frame of sampled voice signals obtained from certain numbers of individuals are plotted. From the experimental results obtained, it can be seen visually from the plotted data that each individuals' voice has comparable PDF values and shapes.
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
Functional brain networks develop from a "local to distributed" organization.
Fair, Damien A; Cohen, Alexander L; Power, Jonathan D; Dosenbach, Nico U F; Church, Jessica A; Miezin, Francis M; Schlaggar, Bradley L; Petersen, Steven E
2009-05-01
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 both have
The Wigner distribution function in modal characterisation
CSIR Research Space (South Africa)
Mredlana, Prince
2016-07-01
Full Text Available function in modal characterisation P. MREDLANA1, D. NAIDOO1, C MAFUSIRE2, T. KRUGER2, A. DUDLEY1,3, A. FORBES1,3 1CSIR National Laser Centre, PO BOX 395, Pretoria 0001, South Africa. 2Department of Physics, Faculty of Natural and Agricultural..., the Wigner distribution of ð ð¥ is an integral of the correlation function ð ð¥ + 1 2 ð¥â² ð â ð¥ + 1 2 ð¥â² represented as: ðð ð¥, ð = ð ð¥ + 1 2 ð¥â² ð â ð¥ + 1 2 ð¥â² ðâððð¥â²ðð...
Energy Technology Data Exchange (ETDEWEB)
Du, Jiangtao; Sharples, Steve [School of Architecture, University of Sheffield, Crookesmoor Building, Conduit Road, Sheffield S10 1FL (United Kingdom)
2010-07-15
This study investigated the impacts of different diffuse reflectance distributions and well geometries on vertical daylight factors and vertical internally reflected components in atria. Two forms of reflectance distribution patterns of wall surface were examined: horizontal and vertical reflectance band variation. The square atrium models studied have a broader WI range of 0.25-2.0, which represent shallow, medium and high atria. Radiance, a powerful package based on backward ray tracing technique, was used for the simulations of vertical daylight levels. The results show that different reflectance distributions of square atrium walls do have an impact on the vertical daylight factors and vertical internally reflected components under overcast sky condition. The impact relates to the orientation of the band with different reflectance distributions on the wall. Compared with the vertical band surface, the horizontal band surface has a much more complicated effect. The horizontal distributions of the reflectances significantly affects the vertical daylight levels at the locations more than 30% atrium height on the wall. For an atrium with a height more than 1/2 the width, the effect tends to increase with the increasing well index. The vertical distributions of the reflectance, nevertheless, do not substantially take effect on the vertical daylight levels in atria except for some special reflectance distribution patterns. (author)
Identification method of non-reflective faults based on index distribution of optical fibers.
Lee, Wonkyoung; Myong, Seung Il; Lee, Jyung Chan; Lee, Sangsoo
2014-01-13
This paper investigates an identification method of non-reflective faults based on index distribution of optical fibers. The method identifies not only reflective faults but also non-reflective faults caused by tilted fiber-cut, lateral connector-misalignment, fiber-bend, and temperature variation. We analyze the reason why wavelength dependence of the fiber-bend is opposite to that of the lateral connector-misalignment, and the effect of loss due to temperature variation on OTDR waveforms through simulation and experimental results. This method can be realized by only upgrade of fault-analysis software without the hardware change, it is, therefore, competitive and cost-effective in passive optical networks.
International Nuclear Information System (INIS)
Soskin, S.M.
1987-01-01
The authors examine Brownian motion in a square well with reflecting walls. An exact solution is obtained for the corresponding Einstein-Fokker-Planck equation, which is used to find the coordinate correlation function in explicit form. The correlation function, normalized to the square of the distance between the walls, typically exhibits a similarity property: its behavior as a function of time, friction, temperature, and wall separation reduces to a function of one simple combination of those four quantities. The limiting cases of low and high friction are investigated in detail, with explicit expressions being derived for the spectrum
Theoretical method for determining particle distribution functions of classical systems
International Nuclear Information System (INIS)
Johnson, E.
1980-01-01
An equation which involves the triplet distribution function and the three-particle direct correlation function is obtained. This equation was derived using an analogue of the Ornstein--Zernike equation. The new equation is used to develop a variational method for obtaining the triplet distribution function of uniform one-component atomic fluids from the pair distribution function. The variational method may be used with the first and second equations in the YBG hierarchy to obtain pair and triplet distribution functions. It should be easy to generalize the results to the n-particle distribution function
Smith, J. A.; Cooper, K.; Randolph, M.
1984-01-01
A classical description of the one dimensional radiative transfer treatment of vegetation canopies was completed and the results were tested against measured prairie (blue grama) and agricultural canopies (soybean). Phase functions are calculated in terms of directly measurable biophysical characteristics of the canopy medium. While the phase functions tend to exhibit backscattering anisotropy, their exact behavior is somewhat more complex and wavelength dependent. A Monte Carlo model was developed that treats soil surfaces with large periodic variations in three dimensions. A photon-ray tracing technology is used. Currently, the rough soil surface is described by analytic functions and appropriate geometric calculations performed. A bidirectional reflectance distribution function is calculated and, hence, available for other atmospheric or canopy reflectance models as a lower boundary condition. This technique is used together with an adding model to calculate several cases where Lambertian leaves possessing anisotropic leaf angle distributions yield non-Lambertian reflectance; similar behavior is exhibited for simulated soil surfaces.
Development of pair distribution function analysis
International Nuclear Information System (INIS)
Vondreele, R.; Billinge, S.; Kwei, G.; Lawson, A.
1996-01-01
This is the final report of a 3-year LDRD project at LANL. It has become more and more evident that structural coherence in the CuO 2 planes of high-T c superconducting materials over some intermediate length scale (nm range) is important to superconductivity. In recent years, the pair distribution function (PDF) analysis of powder diffraction data has been developed for extracting structural information on these length scales. This project sought to expand and develop this technique, use it to analyze neutron powder diffraction data, and apply it to problems. In particular, interest is in the area of high-T c superconductors, although we planned to extend the study to the closely related perovskite ferroelectric materials andother materials where the local structure affects the properties where detailed knowledge of the local and intermediate range structure is important. In addition, we planned to carry out single crystal experiments to look for diffuse scattering. This information augments the information from the PDF
International Nuclear Information System (INIS)
Aslan, Mustafa M.; Wriedt, Thomas
2010-01-01
In this article, we describe a parametric study of the effects of the size distribution (SD) and the concentration of nanospheres in ethanol on the angular reflectance. Calculations are based on an effective medium approach in which the effective dielectric constant of the mixture is obtained using the Maxwell-Garnett formula. The detectable size limits of gold, aluminum, and silver nanospheres on a 50-nm-thick gold film are calculated to investigate the sensitivity of the reflectance to the SD and the concentration of the nanospheres. The following assumptions are made: (1) the total number of particles in the unit volume of suspension is constant, (2) the nanospheres in the suspension on a gold film have a SD with three different concentrations, and (3) there is no agglomeration and the particles have a log-normal SD, where the effective diameter, d eff and the effective variance, ν eff are given. The dependence of the reflectance on the d eff , ν eff , and the width of the SD are also investigated numerically. The angular variation of the reflectance as a function of the incident angle shows a strong dependence on the effective size of the metallic nanospheres. The results confirm that the size of the nanospheres (d eff o and 75 o for a given concentration with a particular SD.
International Nuclear Information System (INIS)
Bund, G W; Tijero, M C
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. The purpose of the present work is to obtain values of the potential parameters represented by the number of levels in the case of the Morse oscillator, for which the SDF becomes a faithful approximation of the corresponding WDF. 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. We also discuss the limit ℎ → 0 for fixed potential parameters
Werdell, P. Jeremy; Ooesler, Collin S.
2012-01-01
The daily, synoptic images provided by satellite ocean color instruments provide viable data streams for observing changes in the biogeochemistrY of marine ecosystems. Ocean reflectance inversion models (ORMs) provide a common mechanism for inverting the "color" of the water observed a satellite into marine inherent optical properties (lOPs) through a combination of empiricism and radiative transfer theory. lOPs, namely the spectral absorption and scattering characteristics of ocean water and its dissolved and particulate constituents, describe the contents of the upper ocean, information critical for furthering scientific understanding of biogeochemical oceanic processes. Many recent studies inferred marine particle sizes and discriminated between phytoplankton functional groups using remotely-sensed lOPs. While all demonstrated the viability of their approaches, few described the vertical distributions of the water column constituents under consideration and, thus, failed to report the biophysical conditions under which their model performed (e.g., the depth and thickness of the phytoplankton bloom(s)). We developed an ORM to remotely identifY Noctiluca miliaris and other phytoplankton functional types using satellite ocean color data records collected in the northern Arabian Sea. Here, we present results from analyses designed to evaluate the applicability and sensitivity of the ORM to varied biophysical conditions. Specifically, we: (1) synthesized a series of vertical profiles of spectral inherent optical properties that represent a wide variety of bio-optical conditions for the northern Arabian Sea under aN Miliaris bloom; (2) generated spectral remote-sensing reflectances from these profiles using Hydrolight; and, (3) applied the ORM to the synthesized reflectances to estimate the relative concentrations of diatoms and N Miliaris for each example. By comparing the estimates from the inversion model to those from synthesized vertical profiles, we were able to
International Nuclear Information System (INIS)
Makarious, A.S.; Swilem, Y.I.; Awwad, Z.; Bayomy, T.
1993-01-01
Slow neutrons and secondary gamma ray distributions in concrete shields with and without a reflecting layer behind layer behind the concrete shield have been investigated first in case of using a bare reactor beam and then on using a B-4 C filtered beam. The total and capture secondary gamma ray coefficient (B gamma and B gamma C ), the ratio of the reflected thermal neutron (gamma) the ratio of the secondary gamma rays caused by reflected neutrons to those caused transmitted neutrons (Th I gamma/F I gamma) and the effect of inserting a blocking layer (a B-4 C layer) between the concrete shield and the reflector on the suppression of the produced secondary gamma rays have been investigated. It was found that the presence of the reflector layer behind the concrete shield reflects some thermal neutrons back to the concrete shields and so it increases the number of thermal neutrons at the interface between the concrete shield and the reflector. Also the capture secondary gamma rays was increased at the interface between the two medii due to the capture of the reflected thermal neutrons in the concrete shields. It was shown that B-gamma is higher than and that B g amma B gamma C and I gamma T h/ I gamma i f for the different concrete types is higher in case of using the graphite reflector than that in using either water or paraffin reflectors. Putting a blocking layer (B 4 C layer) between the concrete shield and the reflector decreases the produced secondary gamma rays due to the absorption of the reflected thermal neutrons. 17 figs
Pair distribution function and structure factor of spherical particles
International Nuclear Information System (INIS)
Howell, Rafael C.; Proffen, Thomas; Conradson, Steven D.
2006-01-01
The availability of neutron spallation-source instruments that provide total scattering powder diffraction has led to an increased application of real-space structure analysis using the pair distribution function. Currently, the analytical treatment of finite size effects within pair distribution refinement procedures is limited. To that end, an envelope function is derived which transforms the pair distribution function of an infinite solid into that of a spherical particle with the same crystal structure. Distributions of particle sizes are then considered, and the associated envelope function is used to predict the particle size distribution of an experimental sample of gold nanoparticles from its pair distribution function alone. Finally, complementing the wealth of existing diffraction analysis, the peak broadening for the structure factor of spherical particles, expressed as a convolution derived from the envelope functions, is calculated exactly for all particle size distributions considered, and peak maxima, offsets, and asymmetries are discussed
Retrieval of cloud droplet size distribution parameters from polarized reflectance measurements
Directory of Open Access Journals (Sweden)
M. Alexandrov
2011-09-01
Full Text Available We present an algorithm for retrieval of cloud droplet size distribution parameters (effective radius and variance from the Research Scanning Polarimeter (RSP measurements. The RSP is an airborne prototype for the Aerosol Polarimetery Sensor (APS, which is due to be launched as part of the NASA Glory Project. This instrument measures both polarized and total reflectances in 9 spectral channels with center wavelengths ranging from 410 to 2250 nm. For cloud droplet size retrievals we utilize the polarized reflectances in the scattering angle range between 140 and 170 degrees where they exhibit rainbow. The shape of the rainbow is determined mainly by single-scattering properties of the cloud particles, that simplifies the inversions and reduces retrieval uncertainties. The retrieval algorithm was tested using realistically simulated cloud radiation fields. Our retrievals of cloud droplet sizes from actual RSP measurements made during two recent field campaigns were compared with the correlative in situ observations.
Geometrically distributed one-dimensional photonic crystals for light-reflection in all angles.
Alagappan, G; Wu, P
2009-07-06
We demonstrate that a series of one-dimensional photonic crystals made of any dielectric materials, with the periods are distributed in a geometrical progression of a common ratio, r rc (theta,P), where rc is a structural parameter that depends on the angle of incidence, theta, and polarization, P, is capable of blocking light of any spectral range. If an omni-directional reflection is desired for all polarizations and for all incident angles smaller than thetao, then r rc (theta(o),p), where p is the polarization with the electric field parallel to the plane of incidence. We present simple and formula like expressions for rc, width of the bandgap, and minimum number of photonic crystals to achieve a perfect light reflection.
Das, Saurabh; Maitra, Animesh
2018-04-01
Characterization of precipitation is important for proper interpretation of rain information from remotely sensed data. Rain attenuation and radar reflectivity (Z) depend directly on the drop size distribution (DSD). The relation between radar reflectivity/rain attenuation and rain rate (R) varies widely depending upon the origin, topography, and drop evolution mechanism and needs further understanding of the precipitation characteristics. The present work utilizes 2 years of concurrent measurements of DSD using a ground-based disdrometer at five diverse climatic conditions in Indian subcontinent and explores the possibility of rain classification based on microphysical characteristics of precipitation. It is observed that both gamma and lognormal distributions are performing almost similar for Indian region with a marginally better performance by one model than other depending upon the locations. It has also been found that shape-slope relationship of gamma distribution can be a good indicator of rain type. The Z-R relation, Z = ARb, is found to vary widely for different precipitation systems, with convective rain that has higher values of A than the stratiform rain for two locations, whereas the reverse is observed for the rest of the three locations. Further, the results indicate that the majority of rainfall (>50%) in Indian region is due to the convective rain although the occurrence time of convective rain is low (<10%).
Mcclelland, J.; Silk, J.
1979-01-01
The evolution of the two-point correlation function for the large-scale distribution of galaxies in an expanding universe is studied on the assumption that the perturbation densities lie in a Gaussian distribution centered on any given mass scale. The perturbations are evolved according to the Friedmann equation, and the correlation function for the resulting distribution of perturbations at the present epoch is calculated. It is found that: (1) the computed correlation function gives a satisfactory fit to the observed function in cosmological models with a density parameter (Omega) of approximately unity, provided that a certain free parameter is suitably adjusted; (2) the power-law slope in the nonlinear regime reflects the initial fluctuation spectrum, provided that the density profile of individual perturbations declines more rapidly than the -2.4 power of distance; and (3) both positive and negative contributions to the correlation function are predicted for cosmological models with Omega less than unity.
Power maximization of a spheric reflected reactor with optimized fuel distribution
International Nuclear Information System (INIS)
Reade, Joamar Rodrigues Vincent
1979-01-01
The maximum power of a spheric reflected reactor was determined using the theory of optimal control. The control variable employed was the fuel distribution, in accordance to constraints on the power density and on the concentration fuel. It was considered a thermal reactor with a fixed radius. The reactor was fuelled with U-235 and moderated with light water. The nuclear reactor was described by a diffusion theory model. The analytical solution was obtained for both two and four groups of energy and a FORTRAN program was developed to obtain the numerical results. (author)
High reflectivity YDH/SiO2 distributed Bragg reflector for UV-C wavelength regime
Alias, Mohd Sharizal
2018-02-15
A distributed Bragg reflector (DBR) composed of Y2O3-doped HfO2 (YDH)/SiO2 layers with high reflectivity spectrum centered at a wavelength of ~240 nm is deposited using radio-frequency magnetron sputtering. Before the DBR deposition, optical properties for a single layer of YDH, SiO2, and HfO2 thin films were studied using spectroscopic ellipsometry and spectrophotometry. To investigate the performance of YDH as a material for the high refractive index layer in the DBR, a comparison of its optical properties was made with HfO2 thin films. Due to larger optical bandgap, the YDH thin films demonstrated higher transparency, lower extinction coefficient, and lower absorption coefficient in the UV-C regime (especially for wavelengths below 250 nm) compared to the HfO2 thin films. The deposited YDH/SiO2 DBR consisting of 15 periods achieved a reflectivity higher than 99.9% at the wavelength of ~240 nm with a stopband of ~50 nm. The high reflectivity and broad stopband of YDH/SiO2 DBRs will enable further advancement of various photonic devices such as vertical-cavity surface-emitting lasers, resonant-cavity light-emitting diodes, and resonant-cavity photodetectors operating in the UV-C wavelength regime.
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.
Automatic Functionality Assignment to AUTOSAR Multicore Distributed Architectures
DEFF Research Database (Denmark)
Maticu, Florin; Pop, Paul; Axbrink, Christian
2016-01-01
The automotive electronic architectures have moved from federated architectures, where one function is implemented in one ECU (Electronic Control Unit), to distributed architectures, where several functions may share resources on an ECU. In addition, multicore ECUs are being adopted because...... 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...
International Nuclear Information System (INIS)
Nikuradse, A.; Weidner, J.
1974-01-01
Analytic expressions for the intensity distribution of a molecular beam reflected by a solid surface which consists of face centered cubic elementary cells have been studied. One has also tried to study the influence of the spatial distribution of the elementary crystal cells on the intensity of reflection. Some curves which had been evaluated and designed by a computer are now published. The Kratzer potential of interaction has alway been supposed [fr
Hlaing, Soe; Gilerson, Alexander; Harmal, Tristan; Tonizzo, Alberto; Weidemann, Alan; Arnone, Robert; Ahmed, Samir
2012-01-01
Water-leaving radiances, retrieved from in situ or satellite measurements, need to be corrected for the bidirectional properties of the measured light in order to standardize the data and make them comparable with each other. The current operational algorithm for the correction of bidirectional effects from the satellite ocean color data is optimized for typical oceanic waters. However, versions of bidirectional reflectance correction algorithms specifically tuned for typical coastal waters and other case 2 conditions are particularly needed to improve the overall quality of those data. In order to analyze the bidirectional reflectance distribution function (BRDF) of case 2 waters, a dataset of typical remote sensing reflectances was generated through radiative transfer simulations for a large range of viewing and illumination geometries. Based on this simulated dataset, a case 2 water focused remote sensing reflectance model is proposed to correct above-water and satellite water-leaving radiance data for bidirectional effects. The proposed model is first validated with a one year time series of in situ above-water measurements acquired by collocated multispectral and hyperspectral radiometers, which have different viewing geometries installed at the Long Island Sound Coastal Observatory (LISCO). Match-ups and intercomparisons performed on these concurrent measurements show that the proposed algorithm outperforms the algorithm currently in use at all wavelengths, with average improvement of 2.4% over the spectral range. LISCO's time series data have also been used to evaluate improvements in match-up comparisons of Moderate Resolution Imaging Spectroradiometer satellite data when the proposed BRDF correction is used in lieu of the current algorithm. It is shown that the discrepancies between coincident in-situ sea-based and satellite data decreased by 3.15% with the use of the proposed algorithm.
DEFF Research Database (Denmark)
Tafur Monroy, Idelfonso; Öhman, Filip; Yvind, Kresten
2006-01-01
We report on a bidirectional 85 km long reach PON system supported by distributed fiber Raman amplification with a record 7.5 Gb/s remote carrier modulated upstream signal by employing a reflective SOA-EA monolithically integrated circuit......We report on a bidirectional 85 km long reach PON system supported by distributed fiber Raman amplification with a record 7.5 Gb/s remote carrier modulated upstream signal by employing a reflective SOA-EA monolithically integrated circuit...
Distribution function in the description of relaxation phenomena
DEFF Research Database (Denmark)
Brecht, M.; Klösgen, B.; Reichle, C.
1999-01-01
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...... and discussed as to their physical relevance. The application of these selected distribution functions results in transformed Debye equations. Thus, analogous analytical expressions are obtained that are well adapted for a numerical fitting of the parameters containing both the width and the asymmetry...... of the distribution functions....
Wigner Function of Density Operator for Negative Binomial Distribution
International Nuclear Information System (INIS)
Xu Xinglei; Li Hongqi
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
Bilinear phase-plane distribution functions and positivity
Janssen, A.J.E.M.
1985-01-01
There is a theorem of Wigner that states that phase-plane distribution functions involving the state bilinearly and having correct marginals must take negative values for certain states. The purpose of this paper is to support the statement that these phase-plane distribution functions are for
Distribution function of excitations in systems with fractional statistics
International Nuclear Information System (INIS)
Protogenov, A.P.
1992-08-01
The distribution function of low-energy excitations in 2+1D systems has been considered. It is shown that in these systems the quantum distribution function differs from the usual one by having a finite value of the entropy of linked braids. (author). 47 refs
Regge behaviour of distribution functions and evolution of gluon ...
Indian Academy of Sciences (India)
work we solved DGLAP evolution equation for gluon distribution function at low-x in next-to-leading order (NLO) and the t and x-evolutions of gluon distribution function thus obtained have been compared with global MRST2004 and GRV98 parametrizations. In PQCD, since the higher-order terms in the leading logarithmic.
The Wigner distribution function applied to optical signals and systems
Bastiaans, M.J.
1978-01-01
In this paper the Wigner distribution function has been introduced for optical signals and systems. The Wigner distribution function of an optical signal appears to be in close resemblance to the ray concept in geometrical optics. This resemblance reaches even farther: although derived from Fourier
Application of the Wigner distribution function in optics
Bastiaans, M.J.; Mecklenbräuker, W.; Hlawatsch, F.
1997-01-01
This contribution presents a review of the Wigner distribution function and of some of its applications to optical problems. The Wigner distribution function describes a signal in space and (spatial) frequency simultaneously and can be considered as the local frequency spectrum of the signal.
Distribution functions for fluids in random media
International Nuclear Information System (INIS)
Madden, W.G.; Glandt, E.D.
1988-01-01
A random medium is considered, composed of identifiable interactive sites or obstacles equilibrated at a high temperature and then quenched rapidly to form a rigid structure, statistically homogeneous on all but molecular length scales. The equilibrium statistical mechanics of a fluid contained inside this quenched medium is discussed. Various particle-particle and particle-obstacle correlation functions, which differ form the corresponding functions for a fully equilibrated binary mixture, are defined through an averaging process over the static ensemble of obstacle configurations and applications of topological reduction techniques. The Ornstein-Zernike equations also differ from their equilibrium counterparts
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.
Wigner's function and other distribution functions in mock phase spaces
International Nuclear Information System (INIS)
Balazs, N.L.; Jennings, B.K.
1983-06-01
This review deals with the methods of associating functions with quantum mechanical operators in such a manner that these functions should furnish conveniently semiclassical approximations. We present a unified treatment of methods and result which usually appear under the expressions Wigner's functions, Weyl's association, Kirkwood's expansion, Glauber's coherent state representation, etc.; we also construct some new associations. The mathematical paraphernalia are collected in the appendices
International Nuclear Information System (INIS)
Totović, A R; Crnjanski, J V; Krstić, M M; Gvozdić, D M
2014-01-01
In this paper, we analyze two semiconductor optical amplifier (SOA) structures, traveling-wave and reflective, with the active region made of the bulk material. The model is based on the stationary traveling-wave equations for forward and backward propagating photon densities of the signal and the amplified spontaneous emission, along with the stationary carrier rate equation. We start by introducing linear approximation of the carrier density spatial distribution, which enables us to find solutions for the photon densities in a closed analytical form. An analytical approach ensures a low computational resource occupation and an easy analysis of the parameters influencing the SOA’s response. The comparison of the analytical and numerical results shows high agreement for a wide range of the input optical powers and bias currents. (paper)
Tight Bounds for Distributed Functional Monitoring
DEFF Research Database (Denmark)
Woodruff, David P.; Zhang, Qin
2011-01-01
$, our bound resolves their main open question. Our lower bounds are based on new direct sum theorems for approximate majority, and yield significant improvements to problems in the data stream model, improving the bound for estimating $F_p, p > 2,$ in $t$ passes from $\\tilde{\\Omega}(n^{1-2/p}/(\\eps^{2/p......} t))$ to $\\tilde{\\Omega}(n^{1-2/p}/(\\eps^{4/p} t))$, giving the first bound for estimating $F_0$ in $t$ passes of $\\Omega(1/(\\eps^2 t))$ bits of space that does not use the gap-hamming problem, and showing a distribution for the gap-hamming problem with high external information cost or super...
Wigner's function and other distribution functions in mock phase space
International Nuclear Information System (INIS)
Balazs, N.L.
1984-01-01
This review deals with the methods of associating functions with quantum mechanical operators in such a manner that these functions should furnish conveniently semiclassical approximations. We present a unified treatment of methods and results which usually appear under expressions such as Wigner's function. Weyl's association, Kirkwood's expansion, Glauber's coherent state representation, etc.; we also construct some new associations. Section 1 gives the motivation by discussing the Thomas-Fermi theory of an atom with this end in view. Section 2 introduce new operators which resemble Dirac delta functions with operator arguments, the operators being the momenta and coordinates. Reasons are given as to why this should be useful. Next we introduce the notion of an operator basis, and discuss the possibility and usefulness of writing an operator as a linear combination of the basis operators. The coefficients in the linear combination are c-numbers and the c-numbers are associated with the operator (in that particularly basis). The delta function type operators introduced before can be used as a basis for the dynamical operators, and the c-numbers obtained in this manner turn out to be the c-number functions used by Wigner, Weyl, Krikwood, Glauber, etc. New bases and associations can now be invented at will. One such new basis is presented and discussed. The reason and motivations for choosing different bases is then explained. The copious and seemingly random mathematical relations between these functions are then nothing else but the relations between the expansion coefficients engendered by the relations between bases. These are shown and discussed in this light. A brief discussion is then given to possible transformation of the p, q labels. Section 3 gives examples of how the semiclassical expansions are generated for these functions and exhibits their equivalence. The mathematical paraphernalia are collected in the appendices. (orig.)
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.
Elaiophores: their taxonomic distribution, morphology and functions
Directory of Open Access Journals (Sweden)
Clivia Carolina Fiorilo Possobom
Full Text Available ABSTRACT Elaiophores are floral glands that secrete non-volatile oils as a reward for their pollinators. Their secretions mediate a specialized interaction between oil-producing plants and a few species of oil-collecting bees - Apidae and Melittidae. The present review focuses on the morphological and functional aspects of these secretory structures. We also provide information on their chemistry and pollination ecology. Our survey is organized taxonomically among the plant families for which elaiophore occurrence has been confirmed -for the monocots, Iridaceae and Orchidaceae, and for the eudicots, Calceolariaceae, Cucurbitaceae, Krameriaceae, Malpighiaceae, Plantaginaceae, Primulaceae, Scrophulariaceae, Solanaceae and Stilbaceae. Most oil flowers are zygomorphic, bisexual, nectarless and present their elaiophores on the protective whorls or on the androecium. Trichomal elaiophores are reported in all of these families except Krameriaceae and Malpighiaceae, and they vary in the density and morphology of the trichomes. Epithelial elaiophores occur in some monocot representatives and in Krameriaceae and Malpighiaceae, and are similar among species. An intermediate type of elaiophore is reported in some species of Orchidaceae. Regardless of elaiophore type, these glands have similar subcellular features and secretion-release mechanisms. Finally, we note the dearth of information on elaiophore ultrastructure and functioning for several plant families.
Wills, Peter R; Scott, David J; Winzor, Donald J
2012-03-01
This reexamination of a high-speed sedimentation equilibrium distribution for α-chymotrypsin under slightly acidic conditions (pH 4.1, I(M) 0.05) has provided experimental support for the adequacy of nearest-neighbor considerations in the allowance for effects of thermodynamic nonideality in the characterization of protein self-association over a moderate concentration range (up to 8 mg/mL). A widely held but previously untested notion about allowance for thermodynamic nonideality effects is thereby verified experimentally. However, it has also been shown that a greater obstacle to better characterization of protein self-association is likely to be the lack of a reliable estimate of monomer net charge, a parameter that has a far more profound effect on the magnitude of the measured equilibrium constant than any deficiency in current procedures for incorporating the effects of thermodynamic nonideality into the analysis of sedimentation equilibrium distributions reflecting reversible protein self-association. Copyright Â© 2011 Elsevier Inc. All rights reserved.
Cai, Lile; Tay, Wei-Liang; Nguyen, Binh P; Chui, Chee-Kong; Ong, Sim-Heng
2013-01-01
Transfer functions play a key role in volume rendering of medical data, but transfer function manipulation is unintuitive and can be time-consuming; achieving an optimal visualization of patient anatomy or pathology is difficult. To overcome this problem, we present a system for automatic transfer function design based on visibility distribution and projective color mapping. Instead of assigning opacity directly based on voxel intensity and gradient magnitude, the opacity transfer function is automatically derived by matching the observed visibility distribution to a target visibility distribution. An automatic color assignment scheme based on projective mapping is proposed to assign colors that allow for the visual discrimination of different structures, while also reflecting the degree of similarity between them. When our method was tested on several medical volumetric datasets, the key structures within the volume were clearly visualized with minimal user intervention. Copyright © 2013 Elsevier Ltd. All rights reserved.
Rocket measurement of auroral partial parallel distribution functions
Lin, C.-A.
1980-01-01
The auroral partial parallel distribution functions are obtained by using the observed energy spectra of electrons. The experiment package was launched by a Nike-Tomahawk rocket from Poker Flat, Alaska over a bright auroral band and covered an altitude range of up to 180 km. Calculated partial distribution functions are presented with emphasis on their slopes. The implications of the slopes are discussed. It should be pointed out that the slope of the partial parallel distribution function obtained from one energy spectra will be changed by superposing another energy spectra on it.
Leveraging Distributions in Physical Unclonable Functions
Directory of Open Access Journals (Sweden)
Wenjie Che
2017-10-01
Full Text Available A special class of Physical Unclonable Functions (PUFs referred to as strong PUFs can be used in novel hardware-based authentication protocols. Strong PUFs are required for authentication because the bit strings and helper data are transmitted openly by the token to the verifier, and therefore are revealed to the adversary. This enables the adversary to carry out attacks against the token by systematically applying challenges and obtaining responses in an attempt to machine learn, and later predict, the token’s response to an arbitrary challenge. Therefore, strong PUFs must both provide an exponentially large challenge space and be resistant to machine-learning attacks in order to be considered secure. We investigate a transformation called temperature–voltage compensation (TVCOMP, which is used within the Hardware-Embedded Delay PUF (HELP bit string generation algorithm. TVCOMP increases the diversity and unpredictability of the challenge–response space, and therefore increases resistance to model-building attacks. HELP leverages within-die variations in path delays as a source of random information. TVCOMP is a linear transformation designed specifically for dealing with changes in delay introduced by adverse temperature–voltage (environmental variations. In this paper, we show that TVCOMP also increases entropy and expands the challenge–response space dramatically.
Stacks, Ann M; Muzik, Maria; Wong, Kristyn; Beeghly, Marjorie; Huth-Bocks, Alissa; Irwin, Jessica L; Rosenblum, Katherine L
2014-01-01
This study examined relationships among maternal reflective functioning, parenting, infant attachment, and demographic risk in a relatively large (N = 83) socioeconomically diverse sample of women with and without a history of childhood maltreatment and their infants. Most prior research on parental reflective functioning has utilized small homogenous samples. Reflective functioning was assessed with the Parent Development Interview, parenting was coded from videotaped mother-child interactions, and infant attachment was evaluated in Ainsworth's Strange Situation by independent teams of reliable coders masked to maternal history. Reflective functioning was associated with parenting sensitivity and secure attachment, and inversely associated with demographic risk and parenting negativity; however, it was not associated with maternal maltreatment history or PTSD. Parenting sensitivity mediated the relationship between reflective functioning and infant attachment, controlling for demographic risk. Findings are discussed in the context of prior research on reflective functioning and the importance of targeting reflective functioning in interventions.
Z. Meghnatisi; N. Nematollahi
2009-01-01
Let Xi1, · · · , Xini be a random sample from a gamma distribution with known shape parameter νi > 0 and unknown scale parameter βi > 0, i = 1, 2, satisfying 0 < β1 6 β2. We consider the class of mixed estimators for estimation of β1 and β2 under reflected gamma loss function. It has been shown that the minimum risk equivariant estimator of βi, i = 1, 2, which is admissible when no information on the ordering of parameters are given, is inadmissible and dominated by a cla...
Hirose, Misa; Toyota, Saori; Tsumura, Norimichi
2018-02-01
In this research, we evaluate the visibility of age spot and freckle with changing the blood volume based on simulated spectral reflectance distribution and the actual facial color images, and compare these results. First, we generate three types of spatial distribution of age spot and freckle in patch-like images based on the simulated spectral reflectance. The spectral reflectance is simulated using Monte Carlo simulation of light transport in multi-layered tissue. Next, we reconstruct the facial color image with changing the blood volume. We acquire the concentration distribution of melanin, hemoglobin and shading components by applying the independent component analysis on a facial color image. We reproduce images using the obtained melanin and shading concentration and the changed hemoglobin concentration. Finally, we evaluate the visibility of pigmentations using simulated spectral reflectance distribution and facial color images. In the result of simulated spectral reflectance distribution, we found that the visibility became lower as the blood volume increases. However, we can see that a specific blood volume reduces the visibility of the actual pigmentations from the result of the facial color images.
New control system: distribution of the GANICIEL functions
International Nuclear Information System (INIS)
David, L.; Lecorche, E.
1992-01-01
This report describes the material configurations of the various processors, and of the distribution between them of the different software functions which constitute the GANICIEL. (A.B.). 9 refs., 4 figs
Transverse momentum dependent (TMD) parton distribution functions : status and prospects
Angeles-Martinez, R.; Bacchetta, A.; Balitsky, I.I.; Boer, D.; Boglione, M.; Boussarie, R.; Ceccopieri, F.A.; Cherednikov, I.O.; Connor, P.; Echevarria, M. G.; Ferrera, G.; Luyando, J. Grados; Hautmann, F.; Jung, H.; Kasemets, T.; Kutak, K.; Lansberg, J.P.; Lelek, A.; Lykasov, G.; Martinez, J. D. Madrigal; Mulders, P. J.; Nocera, Emanuele R.; Petreska, E.; Pisano, C.; Placakyte, R.; Radescu, V.; Radici, M.; Schnell, G.; Scimemi, I.; Signori, A.; Szymanowski, L.; Monfared, S. Taheri; van der Veken, F.F.; van Haevermaet, H.J.; van Mechelen, P.; Vladimirov, A.; Wallon, S.
2015-01-01
We review transverse momentum dependent (TMD) parton distribution functions, their application to topical issues in high-energy physics phenomenology, and their theoretical connections with QCD resummation, evolution and factorization theorems. We illustrate the use of TMDs via examples of
On relation between distribution functions in hard and soft processes
International Nuclear Information System (INIS)
Kisselev, A.V.; Petrov, V.A.
1992-10-01
It is shown that in the particle-exchange model the hadron-hadron scattering amplitude admits parton-like representation with the distribution functions coinciding with those extracted from deep inelastic processes. (author). 13 refs
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...
Directory of Open Access Journals (Sweden)
Clarissa eCavallina
2015-09-01
Full Text Available Attention-deficit/hyperactivity disorder (ADHD is a disorder characterized by a chronic, pervasive, and developmentally inappropriate level of impulsivity, attention and concentration. It is associated with adverse academic and social functions and stress to families. Studies provide evidence that family variables are correlated with this disorder and that parenting styles play an important role in its complexity. However, a thorough investigation of the impact of parental affective and relational aspects on the ADHD child’s areas of functioning is still needed. We suggest investigating parenting characteristics to a greater extent by adopting an attachment perspective with a focus on parental reflective functioning as it pertains to the child’s ADHD clinical condition. In future research, parents’ attachment and the parental reflective functioning should be taken into account.
Generalised partition functions: inferences on phase space distributions
Directory of Open Access Journals (Sweden)
R. A. Treumann
2016-06-01
Full Text Available 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
Kornrumpf, Benthe; Dimigen, Olaf; Sommer, Werner
2017-06-01
Visuospatial attention is an important mechanism in reading that governs the uptake of information from foveal and parafoveal regions of the visual field. However, the spatiotemporal dynamics of how attention is allocated during eye fixations are not completely understood. The current study explored the use of EEG alpha-band oscillations to investigate the spatial distribution of attention during reading. We reanalyzed two data sets, focusing on the lateralization of alpha activity at posterior scalp sites. In each experiment, participants read short lists of German nouns in two paradigms: either by freely moving their eyes (saccadic reading) or by fixating the screen center while the text moved passively from right to left at the same average speed (RSVP paradigm). In both paradigms, upcoming words were either visible or masked, and foveal processing load was manipulated by varying the words' lexical frequencies. Posterior alpha lateralization revealed a sustained rightward bias of attention during saccadic reading, but not in the RSVP paradigm. Interestingly, alpha lateralization was not influenced by word frequency (foveal load) or preview during the preceding fixation. Hence, alpha did not reflect transient attention shifts within a given fixation. However, in both experiments, we found that in the saccadic reading condition a stronger alpha lateralization shortly before a saccade predicted shorter fixations on the subsequently fixated word. These results indicate that alpha lateralization can serve as a measure of attention deployment and its link to oculomotor behavior in reading. © 2017 Society for Psychophysiological Research.
On a Functional Equation for the Generating Function of the Logarithmic Series Distribution
Panaretos, John
1987-01-01
This note deals with finding the solution of a functional equation, where the function involved has the additional property of being a probability generating function. It turns out that the unique solution of this particular functional equation is the probability generating function of the logarithmic series distribution
Exact probability distribution function for the volatility of cumulative production
Zadourian, Rubina; Klümper, Andreas
2018-04-01
In this paper we study the volatility and its probability distribution function for the cumulative production based on the experience curve hypothesis. This work presents a generalization of the study of volatility in Lafond et al. (2017), which addressed the effects of normally distributed noise in the production process. Due to its wide applicability in industrial and technological activities we present here the mathematical foundation for an arbitrary distribution function of the process, which we expect will pave the future research on forecasting of the production process.
Advanced Inverter Functions and Communication Protocols for Distribution Management
Energy Technology Data Exchange (ETDEWEB)
Nagarajan, Adarsh; Palmintier, Bryan; Baggu, Murali
2016-05-05
This paper aims at identifying the advanced features required by distribution management systems (DMS) service providers to bring inverter-connected distributed energy resources into use as an intelligent grid resource. This work explores the standard functions needed in the future DMS for enterprise integration of distributed energy resources (DER). The important DMS functionalities such as DER management in aggregate groups, including the discovery of capabilities, status monitoring, and dispatch of real and reactive power are addressed in this paper. It is intended to provide the industry with a point of reference for DER integration with other utility applications and to provide guidance to research and standards development organizations.
A comparison of reflectance properties on polymer micro-structured functional surface
DEFF Research Database (Denmark)
Regi, Francesco; Li, Dongya; Nielsen, Jannik Boll
In this study, a functional micro-structure surface [1] has been developed as a combination of arrays of micro ridges. The scope of the surface is to achieve specific directional optical properties: that is, under constrained lighting, maximizing the reflectance from a certain viewing direction, ...
Wong, Kristyn; Stacks, Ann M.; Rosenblum, Katherine L.; Muzik, Maria
2017-01-01
This study assessed the links between infant negative affect, parental reflective functioning (RF), and toddler behavior problems in a sample of 84 women and their infants. Mothers provided self-report demographic data and completed the Infant Behavior Questionnaire-Revised during a home visit when the infant was 7 months old. They also completed…
A functional-dynamic reflection on participatory processes in modeling projects.
Seidl, Roman
2015-12-01
The participation of nonscientists in modeling projects/studies is increasingly employed to fulfill different functions. However, it is not well investigated if and how explicitly these functions and the dynamics of a participatory process are reflected by modeling projects in particular. In this review study, I explore participatory modeling projects from a functional-dynamic process perspective. The main differences among projects relate to the functions of participation-most often, more than one per project can be identified, along with the degree of explicit reflection (i.e., awareness and anticipation) on the dynamic process perspective. Moreover, two main approaches are revealed: participatory modeling covering diverse approaches and companion modeling. It becomes apparent that the degree of reflection on the participatory process itself is not always explicit and perfectly visible in the descriptions of the modeling projects. Thus, the use of common protocols or templates is discussed to facilitate project planning, as well as the publication of project results. A generic template may help, not in providing details of a project or model development, but in explicitly reflecting on the participatory process. It can serve to systematize the particular project's approach to stakeholder collaboration, and thus quality management.
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.
Rationalisation of distribution functions for models of nanoparticle magnetism
International Nuclear Information System (INIS)
El-Hilo, M.; Chantrell, R.W.
2012-01-01
A formalism is presented which reconciles the use of different distribution functions of particle diameter in analytical models of the magnetic properties of nanoparticle systems. For the lognormal distribution a transformation is derived which shows that a distribution of volume fraction transforms into a lognormal distribution of particle number albeit with a modified median diameter. This transformation resolves an apparent discrepancy reported in Tournus and Tamion [Journal of Magnetism and Magnetic Materials 323 (2011) 1118]. - Highlights: ► We resolve a problem resulting from the misunderstanding of the nature. ► The nature of dispersion functions in models of nanoparticle magnetism. ► The derived transformation between distributions will be of benefit in comparing models and experimental results.
Electron and ion distribution functions in magnetopause reconnection
Wang, S.; Chen, L. J.; Bessho, N.; Hesse, M.; Kistler, L. M.; Torbert, R. B.; Mouikis, C.; Pollock, C. J.
2015-12-01
We investigate electron and ion velocity distribution functions in dayside magnetopause reconnection events observed by the Cluster and MMS spacecraft. The goal is to build a spatial map of electron and ion distribution features to enable the indication of the spacecraft location in the reconnection structure, and to understand plasma energization processes. Distribution functions, together with electromagnetic field structures, plasma densities, and bulk velocities, are organized and compared with particle-in-cell simulation results to indicate the proximities to the reconnection X-line. Anisotropic features in the distributions of magnetospheric- and magnetosheath- origin electrons at different locations in the reconnection inflow and exhaust are identified. In particular, parallel electron heating is observed in both the magnetosheath and magnetosphere inflow regions. Possible effects of the guide field strength, waves, and upstream density and temperature asymmetries on the distribution features will be discussed.
Kaon quark distribution functions in the chiral constituent quark model
Watanabe, Akira; Sawada, Takahiro; Kao, Chung Wen
2018-04-01
We investigate the valence u and s ¯ quark distribution functions of the K+ meson, vK (u )(x ,Q2) and vK (s ¯)(x ,Q2), in the framework of the chiral constituent quark model. We judiciously choose the bare distributions at the initial scale to generate the dressed distributions at the higher scale, considering the meson cloud effects and the QCD evolution, which agree with the phenomenologically satisfactory valence quark distribution of the pion and the experimental data of the ratio vK (u )(x ,Q2)/vπ (u )(x ,Q2) . We show how the meson cloud effects affect the bare distribution functions in detail. We find that a smaller S U (3 ) flavor symmetry breaking effect is observed, compared with results of the preceding studies based on other approaches.
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.
Vaudelle, Fabrice; L'Huillier, Jean-Pierre; Askoura, Mohamed Lamine
2017-06-01
Red and near-Infrared light is often used as a useful diagnostic and imaging probe for highly scattering media such as biological tissues, fruits and vegetables. Part of diffusively reflected light gives interesting information related to the tissue subsurface, whereas light recorded at further distances may probe deeper into the interrogated turbid tissues. However, modelling diffusive events occurring at short source-detector distances requires to consider both the distribution of the light sources and the scattering phase functions. In this report, a modified Monte Carlo model is used to compute light transport in curved and multi-layered tissue samples which are covered with a thin and highly diffusing tissue layer. Different light source distributions (ballistic, diffuse or Lambertian) are tested with specific scattering phase functions (modified or not modified Henyey-Greenstein, Gegenbauer and Mie) to compute the amount of backscattered and transmitted light in apple and human skin structures. Comparisons between simulation results and experiments carried out with a multispectral imaging setup confirm the soundness of the theoretical strategy and may explain the role of the skin on light transport in whole and half-cut apples. Other computational results show that a Lambertian source distribution combined with a Henyey-Greenstein phase function provides a higher photon density in the stratum corneum than in the upper dermis layer. Furthermore, it is also shown that the scattering phase function may affect the shape and the magnitude of the Bidirectional Reflectance Distribution (BRDF) exhibited at the skin surface.
Ray tracing the Wigner distribution function for optical simulations
Mout, B.M.; Wick, Michael; Bociort, F.; Petschulat, Joerg; Urbach, Paul
2018-01-01
We study a simulation method that uses the Wigner distribution function to incorporate wave optical effects in an established framework based on geometrical optics, i.e., a ray tracing engine. We use the method to calculate point spread functions and show that it is accurate for paraxial systems
Uniform convergence of the empirical spectral distribution function
Mikosch, T; Norvaisa, R
1997-01-01
Let X be a linear process having a finite fourth moment. Assume F is a class of square-integrable functions. We consider the empirical spectral distribution function J(n,X) based on X and indexed by F. If F is totally bounded then J(n,X) satisfies a uniform strong law of large numbers. If, in
Spin-dependent parton distributions and structure functions
International Nuclear Information System (INIS)
Bentz, W.; Ito, T.; Cloet, I.C.; Thomas, A.W.; Yazaki, K.
2008-01-01
Nuclear parton distributions and structure functions are determined in an effective chiral quark theory. We also discuss an extension of our model to fragmentation functions. Presented at the 20th Few-Body Conference, Pisa, Italy, 10-14 September 2007. (author)
Comparison of parton distributions and structure functions for the proton
International Nuclear Information System (INIS)
Abramowicz, H.; Charchula, K.; Krawczyk, M.; Levy, A.
1990-09-01
A comparative study of the most popular parton parametrizations is presented. The individual parton distributions as well as the F 2 structure function are discussed with a particular emphasis on the low x region, 10 -4 -2 . The predictions of these parametrizations for the F 2 structure function have a wide spread which persists also in the HERA kinematical region. (orig.)
Mindfulness Plus Reflection Training: Effects on Executive Function in Early Childhood
Directory of Open Access Journals (Sweden)
Philip David Zelazo
2018-02-01
Full Text Available Executive function (EF skills are essential for academic achievement, and poverty-related stress interferes with their development. This pre-test, post-test, follow-up randomized-control trial assessed the impact of an intervention targeting reflection and stress reduction on children's EF skills. Preschool children (N = 218 from schools serving low-income families in two U.S. cities were randomly assigned to one of three options delivered in 30 small-group sessions over 6 weeks: Mindfulness + Reflection training; Literacy training; or Business as Usual (BAU. Sessions were conducted by local teachers trained in a literacy curriculum or Mindfulness + Reflection intervention, which involved calming activities and games that provided opportunities to practice reflection in the context of goal-directed problem solving. EF improved in all groups, but planned contrasts indicated that the Mindfulness + Reflection group significantly outperformed the BAU group at Follow-up (4 weeks post-test. No differences in EF were observed between the BAU and Literacy training groups. Results suggest that a brief, small-group, school-based intervention teaching mindfulness and reflection did not improve EF skills more than literacy training but is promising compared to BAU for improving EF in low-income preschool children several weeks following the intervention.
Rumination and self-reflection in stress narratives and relations to psychological functioning.
Marin, Kelly A; Rotondo, Elena K
2017-01-01
The longitudinal study aims to expand what is known about the costs and benefits of narrating stressful experiences by exploring changes in rumination within the narrative process and comparing it to changes in self-reflection. Rumination (e.g., brooding, self-criticism, and negative emotions) and self-reflection were measured in stress narratives of 56 college students. There were several goals: (1) examine changes in narrative rumination and narrative self-reflection over 3 days of writing, (2) examine the relations among the changes in narrative rumination variables and narrative self-reflection and (3) examine how changes in narrative rumination and narrative self-reflection relate to multiple measures of psychological functioning. Overall, individuals increased self-reflection over the 3-day writing task. Individuals who increased ruminative brooding across the 3 days of writing showed lower ego identity development (short term and long term) and self-esteem (short term), while increased self-criticism was positively correlated with identity distress (short term). Implications of the different aspects of narrative rumination, specifically in the context of stressful experiences, are discussed.
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.
Functions and generality of logic reflections on Dedekind's and Frege's logicisms
Benis-Sinaceur, Hourya; Sandu, Gabriel
2015-01-01
This book examines three connected aspects of Frege's logicism: the differences between Dedekind's and Frege's interpretation of the term 'logic' and related terms and reflects on Frege's notion of function, comparing its understanding and the role it played in Frege's and Lagrange's foundational programs. It concludes with an examination of the notion of arbitrary function, taking into account Frege's, Ramsey's and Russell's view on the subject. Composed of three chapters, this book sheds light on important aspects of Dedekind's and Frege's logicisms. The first chapter explains how, although he shares Frege's aim at substituting logical standards of rigor to intuitive imports from spatio-temporal experience into the deductive presentation of arithmetic, Dedekind had a different goal and used or invented different tools. The chapter highlights basic dissimilarities between Dedekind's and Frege's actual ways of doing and thinking. The second chapter reflects on Frege's notion of a function, in comparison with ...
Russo, Cesare; Jin, Zhezhen; Palmieri, Vittorio; Homma, Shunichi; Rundek, Tatjana; Elkind, Mitchell S V; Sacco, Ralph L; Di Tullio, Marco R
2012-08-01
Increased arterial stiffness and wave reflection have been reported in heart failure with normal ejection fraction (HFNEF) and in asymptomatic left ventricular (LV) diastolic dysfunction, a precursor of HFNEF. It is unclear whether women, who have higher frequency of HFNEF, are more vulnerable than men to the deleterious effects of arterial stiffness on LV diastolic function. We investigated, in a large community-based cohort, whether sex differences exist in the relationship among arterial stiffness, wave reflection, and LV diastolic function. Arterial stiffness and wave reflection were assessed in 983 participants from the Cardiovascular Abnormalities and Brain Lesions study using applanation tonometry. The central pulse pressure/stroke volume index, total arterial compliance, pulse pressure amplification, and augmentation index were used as parameters of arterial stiffness and wave reflection. LV diastolic function was evaluated by 2-dimensional echocardiography and tissue-Doppler imaging. Arterial stiffness and wave reflection were greater in women compared with men, independent of body size and heart rate (all Pfunction in both sexes. Further adjustment for cardiovascular risk factors attenuated these relationships; however, a higher central pulse pressure/stroke volume index predicted LV diastolic dysfunction in women (odds ratio, 1.54; 95% confidence intervals, 1.03 to 2.30) and men (odds ratio, 2.09; 95% confidence interval, 1.30 to 3.39), independent of other risk factors. In conclusion, in our community-based cohort study, higher arterial stiffness was associated with worse LV diastolic function in men and women. Women's higher arterial stiffness, independent of body size, may contribute to their greater susceptibility to develop HFNEF.
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.
Tafur Monroy, I.; Öhman, F.; Yvind, K.; Kjaer, R.; Peucheret, C.; Koonen, A.M.J.; Jeppesen, P.
2006-01-01
We report on a bidirectional 85 km long reach PON system supported by distributed fiber Raman amplification with a record 7.5 Gb/s remote carrier modulated upstream signal by employing a reflective SOA-EA monolithically integrated circuit.
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 ρ(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.
Free energy distribution function of a random Ising ferromagnet
International Nuclear Information System (INIS)
Dotsenko, Victor; Klumov, Boris
2012-01-01
We study the free energy distribution function of a weakly disordered Ising ferromagnet in terms of the D-dimensional random temperature Ginzburg–Landau Hamiltonian. It is shown that besides the usual Gaussian 'body' this distribution function exhibits non-Gaussian tails both in the paramagnetic and in the ferromagnetic phases. Explicit asymptotic expressions for these tails are derived. It is demonstrated that the tails are strongly asymmetric: the left tail (for large negative values of the free energy) is much slower than the right one (for large positive values of the free energy). It is argued that at the critical point the free energy of the random Ising ferromagnet in dimensions D < 4 is described by a non-trivial universal distribution function which is non-self-averaging
Specification of optical components using Wigner distribution function
International Nuclear Information System (INIS)
Xu Jiancheng; Li Haibo; Xu Qiao; Chai Liqun; Fan Changjiang
2010-01-01
In order to characterize and specify small-scale local wavefront deformation of optical component, a method based on Wigner distribution function has been proposed, which can describe wavefront deformation in spatial and spatial frequency domain. The relationship between Wigner distribution function and power spectral density is analyzed and thus the specification of small-scale local wavefront deformation is obtained by Wigner distribution function. Simulation and experiment demonstrate the effectiveness of the proposed method. The proposed method can not only identify whether the optical component meets the requirement of inertial confinement fusion (ICF), but also determine t he location where small-scale wavefront deformation is unqualified. Thus it provides an effective guide to the revision of unqualified optical components. (authors)
Nonclassicality indicator for the real phase-space distribution functions
International Nuclear Information System (INIS)
Sadeghi, Parvin; Khademi, Siamak; Nasiri, Sadollah
2010-01-01
Benedict et al. and Kenfack et al. advocated nonclassicality indicators based on the measurement of negativity of the Wigner distribution functions. These indicators have some applications in quantum mechanics and quantum optics. In this paper we define a nonclassicality indicator in terms of the interference in phase space, which is applicable to some real distribution functions including those of Wigner. As a special case one may reproduce the previous results using our indicator for the Wigner distribution functions. This indicator is examined for cases of the Schroedinger cat state and the thermal states and the results are compared with those obtained by previous methods. It seems that the physical behavior of nonclassicality indicators originates in the uncertainty principle. This is shown by an onto correspondence between these indicators and the uncertainty principle.
The use of generalized functions and distributions in general relativity
International Nuclear Information System (INIS)
Steinbauer, R; Vickers, J A
2006-01-01
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)
On the distribution functions in the quantum mechanics and Wigner functions
International Nuclear Information System (INIS)
Kuz'menkov, L.S.; Maksimov, S.G.
2002-01-01
The problem on the distribution functions, leading to the similar local values of the particles number, pulse and energy, as in the quantum mechanics, is formulated and solved. The method is based on the quantum-mechanical determination of the probability density. The derived distribution function coincides with the Wigner function only for the spatial-homogeneous systems. The Bogolyubov equations chain, the Liouville equation for the distribution quantum functions by any number of particles in the system, the general expression for the tensor of the dielectric permittivity of the plasma electron component are obtained [ru
Karlsson, Hanna; Pettersson, Anders; Larsson, Marcus; Strömberg, Tomas
2011-02-01
Model based analysis of calibrated diffuse reflectance spectroscopy can be used for determining oxygenation and concentration of skin chromophores. This study aimed at assessing the effect of including melanin in addition to hemoglobin (Hb) as chromophores and compensating for inhomogeneously distributed blood (vessel packaging), in a single-layer skin model. Spectra from four humans were collected during different provocations using a twochannel fiber optic probe with source-detector separations 0.4 and 1.2 mm. Absolute calibrated spectra using data from either a single distance or both distances were analyzed using inverse Monte Carlo for light transport and Levenberg-Marquardt for non-linear fitting. The model fitting was excellent using a single distance. However, the estimated model failed to explain spectra from the other distance. The two-distance model did not fit the data well at either distance. Model fitting was significantly improved including melanin and vessel packaging. The most prominent effect when fitting data from the larger separation compared to the smaller separation was a different light scattering decay with wavelength, while the tissue fraction of Hb and saturation were similar. For modeling spectra at both distances, we propose using either a multi-layer skin model or a more advanced model for the scattering phase function.
Fitting the Probability Distribution Functions to Model Particulate Matter Concentrations
International Nuclear Information System (INIS)
El-Shanshoury, Gh.I.
2017-01-01
The main objective of this study is to identify the best probability distribution and the plotting position formula for modeling the concentrations of Total Suspended Particles (TSP) as well as the Particulate Matter with an aerodynamic diameter<10 μm (PM 10 ). The best distribution provides the estimated probabilities that exceed the threshold limit given by the Egyptian Air Quality Limit value (EAQLV) as well the number of exceedance days is estimated. The standard limits of the EAQLV for TSP and PM 10 concentrations are 24-h average of 230 μg/m 3 and 70 μg/m 3 , respectively. Five frequency distribution functions with seven formula of plotting positions (empirical cumulative distribution functions) are compared to fit the average of daily TSP and PM 10 concentrations in year 2014 for Ain Sokhna city. The Quantile-Quantile plot (Q-Q plot) is used as a method for assessing how closely a data set fits a particular distribution. A proper probability distribution that represents the TSP and PM 10 has been chosen based on the statistical performance indicator values. The results show that Hosking and Wallis plotting position combined with Frechet distribution gave the highest fit for TSP and PM 10 concentrations. Burr distribution with the same plotting position follows Frechet distribution. The exceedance probability and days over the EAQLV are predicted using Frechet distribution. In 2014, the exceedance probability and days for TSP concentrations are 0.052 and 19 days, respectively. Furthermore, the PM 10 concentration is found to exceed the threshold limit by 174 days
Electron distribution function in electron-beam-excited plasmas
International Nuclear Information System (INIS)
Brau, C.A.
1976-01-01
In monatomic plasmas excited by high-intensity relativistic electron beams, the electron secondary distribution function is dominated by elastic electron-electron collisions at low electron energies and by inelastic electron-atom collisions at high electron energies (above the excitation threshold). Under these conditions, the total rate of excitation by inelastic collisions is limited by the rate at which electron-electron collisions relax the distribution function in the neighborhood of the excitation threshold. To describe this effect quantitatively, an approximate analytic solution of the electron Boltzmann equation is obtained, including both electron-electron and inelastic collisions. The result provides a simple formula for the total rate of excitation
Distribution functions and moments in the theory of coagulation
International Nuclear Information System (INIS)
Pich, J.
1990-04-01
Different distribution functions and their moments used in the Theory of coagulation are summarized and analysed. Relations between the moments of these distribution functions are derived and the physical meaning of individual moments is briefly discussed. The time evolution of the moment of order zero (total number concentration) during the coagulation process is analysed for the general kernel of the Smoluchowski equation. On this basis the time evolution of certain physically important quantities related to this moment such as mean particle size, surface and volume as well as surface concentration is described. Equations for the half time of coagulation for the general collision frequency factor are derived. (orig.) [de
On the use of the KMR unintegrated parton distribution functions
Golec-Biernat, Krzysztof; Staśto, Anna M.
2018-06-01
We discuss the unintegrated parton distribution functions (UPDFs) introduced by Kimber, Martin and Ryskin (KMR), which are frequently used in phenomenological analyses of hard processes with transverse momenta of partons taken into account. We demonstrate numerically that the commonly used differential definition of the UPDFs leads to erroneous results for large transverse momenta. We identify the reason for that, being the use of the ordinary PDFs instead of the cutoff dependent distribution functions. We show that in phenomenological applications, the integral definition of the UPDFs with the ordinary PDFs can be used.
International Nuclear Information System (INIS)
Chun, Moon-Hyun; Han, Seok-Jung; Tak, Nam-IL
2000-01-01
A simple measure of uncertainty importance using the entire change of cumulative distribution functions (CDFs) has been developed for use in probability safety assessments (PSAs). The entire change of CDFs is quantified in terms of the metric distance between two CDFs. The metric distance measure developed in this study reflects the relative impact of distributional changes of inputs on the change of an output distribution, while most of the existing uncertainty importance measures reflect the magnitude of relative contribution of input uncertainties to the output uncertainty. The present measure has been evaluated analytically for various analytical distributions to examine its characteristics. To illustrate the applicability and strength of the present measure, two examples are provided. The first example is an application of the present measure to a typical problem of a system fault tree analysis and the second one is for a hypothetical non-linear model. Comparisons of the present result with those obtained by existing uncertainty importance measures show that the metric distance measure is a useful tool to express the measure of uncertainty importance in terms of the relative impact of distributional changes of inputs on the change of an output distribution
International Nuclear Information System (INIS)
Ivanov, V.M.; Ershova, N.I.
2001-01-01
Immobilized Eriochrome Cyanine R was used for the direct trace determination of aluminium and beryllium by diffuse reflectance spectrometry. Anion exchanger AV-17, silica gel Silochrom C-120, Chromaton N-Super, silica gel C 18 , and cellulose were examined as supports. Optimal sorption conditions were found. The dependence of chromaticity functions (chromaticity coordinates, lightness, color saturation, yellowness, and whiteness) on different factors was studied. Advantages of the use of chromaticity functions rather than the diffuse reflectance coefficient were demonstrated. A method is developed for the separate determination of aluminium and beryllium using cellulose as the support; the method was used for the analysis of real samples and tested with standard samples. When solution samples of 50 and 100 ml were used, the determination limit was 0.004 μg/ml for aluminium and 0.0002 μg/ml for beryllium, respectively [ru
Quantum mechanics with non-negative quantum distribution function
International Nuclear Information System (INIS)
Zorin, A.V.; Sevastianov, L.A.
2010-01-01
Full text: (author)Among numerous approaches to probabilistic interpretation of the conventional quantum mechanics the most close to the N. Bohr idea of the correspondence principle is the D.I. Blokhintzev - Ya.P. Terletsky approach using the quantum distribution function on the coordinate- momentum space. The detailed investigation of this approach has lead to the correspondence rule of V.V. Kuryshkin. Quantum mechanics of Kuryshkin (QMK) embody the program proposed by Yu.M. Shirokov for unifying classical and quantum mechanics in similar mathematical models. QMK develops and enhances Wigner's proposal concerning the calculation of quantum corrections to classical thermodynamic parameters using a phase distribution function. The main result of QMK is the possibility of description by mean of a positively-valued distribution function. This represents an important step towards a completely statistical model of quantum phenomena, compared with the quasi-probabilistic nature of Wigner distribution. Wigner's model does not permit to perform correctly the classical limit in quantum mechanics as well. On the other hand, QMK has a much more complex structure of operators of observables. One of the unsolved problems of QMK is the absence of a priori rules for establishing of auxiliary functions. Nevertheless, while it is impossible to overcome the complex form of operators, we find it quite possible to derive some methods of filing sets of auxiliary functions
Function allocation in distributed safeguards and security systems
International Nuclear Information System (INIS)
Barlich, G.L.
1991-01-01
Computerized distributed systems are being used to collect and manage data for activities such as nuclear materials accounting, process control, laboratory coordination, and security. Poor choices made in allocating functions to individual processors can make a system unusable by burdening machines with excessive network retrievals and updates. During system design phases, data allocation algorithms based on operation frequencies, field sizes, security information, and reliability requirements can be applied in sensitivity studies to mathematically ensure processor efficiency. The Los Alamos Network Design System (NDS) implements such an allocation algorithm. The authors analyzed a large, existing distributed system to test the cost functions and to compare actual network problems with NDS results. Several common configurations were also designed and studied using the software. From these studies, some basic principles for allocating functions emerged. In this paper recommendations for function allocation in generic systems and related design options are discussed
Directory of Open Access Journals (Sweden)
محمد أحمد حسن الأفندي
2017-12-01
Full Text Available This study investigated the characteristics of happiness function in an Islamic economy framework. It analyzed the nature and trend of the link between economic growth, equal distribution and level of human happiness. These interrelated concepts form the essence of this study problem. The study assumed four main possible tracks for the happiness function in an Islamic economy, which ultimately emphasized the wider concept of happiness that includes faith and moral values. It indicates that people’s happiness increases with the increase of material and non material resources. However, happiness increases even if material resources decline. That is a case which reflects impact of faith and moral values on people’s happiness. The study indicated the importance of conducting empirical and field studies to examine the effect of material and non- material potentials on happiness. Keywords: Happiness function, Material resources for Happiness, Nonmaterial resources for happiness, Economic growth, Equal distribution.
Total reflection coefficients of low-energy photons presented as universal functions
Directory of Open Access Journals (Sweden)
Ljubenov Vladan
2010-01-01
Full Text Available The possibility of expressing the total particle and energy reflection coefficients of low-energy photons in the form of universal functions valid for different shielding materials is investigated in this paper. The analysis is based on the results of Monte Carlo simulations of photon reflection by using MCNP, FOTELP, and PENELOPE codes. The normal incidence of the narrow monoenergetic photon beam of the unit intensity and of initial energies from 20 keV up to 100 keV is considered, and particle and energy reflection coefficients from the plane homogenous targets of water, aluminum, and iron are determined and compared. The representations of albedo coefficients on the initial photon energy, on the probability of large-angle photon scattering, and on the mean number of photon scatterings are examined. It is found out that only the rescaled albedo coefficients dependent on the mean number of photon scatterings have the form of universal functions and these functions are determined by applying the least square method.
On the Hierarchy of Functioning Rules in Distributed Computing
Bui , Alain; Bui , Marc; Lavault , Christian
1999-01-01
International audience; In previous papers, we used a Markovian model to determine the optimal functioning rules of a distributed system in various settings. Searching optimal functioning rules amounts to solve an optimization problem under constraints. The hierarchy of solutions arising from the above problem is called the “first order hierarchy”, and may possibly yield equivalent solutions. The present paper emphasizes a specific technique for deciding between two equivalent solutions, whic...
Ray tracing the Wigner distribution function for optical simulations
Mout, Marco; Wick, Michael; Bociort, Florian; Petschulat, Joerg; Urbach, Paul
2018-01-01
We study a simulation method that uses the Wigner distribution function to incorporate wave optical effects in an established framework based on geometrical optics, i.e., a ray tracing engine. We use the method to calculate point spread functions and show that it is accurate for paraxial systems but produces unphysical results in the presence of aberrations. The cause of these anomalies is explained using an analytical model.
Progress on Bayesian Inference of the Fast Ion Distribution Function
DEFF Research Database (Denmark)
Stagner, L.; Heidbrink, W.W,; Chen, X.
2013-01-01
. 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. 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...
Directory of Open Access Journals (Sweden)
Peter Fonagy
Full Text Available Reflective functioning or mentalizing is the capacity to interpret both the self and others in terms of internal mental states such as feelings, wishes, goals, desires, and attitudes. This paper is part of a series of papers outlining the development and psychometric features of a new self-report measure, the Reflective Functioning Questionnaire (RFQ, designed to provide an easy to administer self-report measure of mentalizing. We describe the development and initial validation of the RFQ in three studies. Study 1 focuses on the development of the RFQ, its factor structure and construct validity in a sample of patients with Borderline Personality Disorder (BPD and Eating Disorder (ED (n = 108 and normal controls (n = 295. Study 2 aims to replicate these findings in a fresh sample of 129 patients with personality disorder and 281 normal controls. Study 3 addresses the relationship between the RFQ, parental reflective functioning and infant attachment status as assessed with the Strange Situation Procedure (SSP in a sample of 136 community mothers and their infants. In both Study 1 and 2, confirmatory factor analyses yielded two factors assessing Certainty (RFQ_C and Uncertainty (RFQ_U about the mental states of self and others. These two factors were relatively distinct, invariant across clinical and non-clinical samples, had satisfactory internal consistency and test-retest stability, and were largely unrelated to demographic features. The scales discriminated between patients and controls, and were significantly and in theoretically predicted ways correlated with measures of empathy, mindfulness and perspective-taking, and with both self-reported and clinician-reported measures of borderline personality features and other indices of maladaptive personality functioning. Furthermore, the RFQ scales were associated with levels of parental reflective functioning, which in turn predicted infant attachment status in the SSP. Overall, this study lends
Zhao, Yi; Cao, Xiangyu; Gao, Jun; Liu, Xiao; Li, Sijia
2016-05-16
We demonstrate a simple reconfigurable metasurface with multiple functions. Anisotropic tiles are investigated and manufactured as fundamental elements. Then, the tiles are combined in a certain sequence to construct a metasurface. Each of the tiles can be adjusted independently which is like a jigsaw puzzle and the whole metasurface can achieve diverse functions by different layouts. For demonstration purposes, we realize polarization conversion, anomalous reflection and diffusion by a jigsaw puzzle metasurface with 6 × 6 pieces of anisotropic tile. Simulated and measured results prove that our method offers a simple and effective strategy for metasurface design.
Distribution of functional traits in subtropical trees across environmental and forest use gradients
Blundo, Cecilia; Malizia, Lucio R.; González-Espinosa, Mario
2015-11-01
The relationship between functional traits and environmental factors contribute to understanding community structure and predicting which species will be able to elude environmental filters in different habitats. We selected 10 functional traits related to morphology, demography and regeneration niche in 54 subtropical premontane tree species to describe their main axes of functional differentiation. We derived species traits, environmental variables and species abundance data from 20 1-ha permanent plots established in a seasonal subtropical premontane forest in northwestern Argentina. We analyzed the relationship between species functional traits and environmental factors through RLQ and fourth-corner analyzes. We found an axis of structural differentiation that segregates understory from canopy species, and an axis of functional differentiation that segregates species that maximize resource acquisition from those that promote resource conservation. Environmental and forest use gradients operate hierarchically over subtropical premontane tree species influencing the distribution of demographic and morphological traits. The interaction between climatic and topographic factors influences the distribution of species functional traits at the regional scale. In addition, the history of forest use seems to operate at the landscape scale and explains the distribution of species traits reflecting a trade-off between resource acquisition and resource conservation strategies in secondary forests across different successional stages. Our results support the idea that functional traits may be used to analyze community structure and dynamics through niche differentiation and environmental filtering processes.
Fourier transform distribution function of relaxation times; application and limitations
Boukamp, Bernard A.
2015-01-01
A simple Fourier transform (FT) method is presented for obtaining a Distribution Function of Relaxation Times (DFRT) for electrochemical impedance spectroscopy (EIS) data. By using a special data extension procedure the FT is performed over the range from -∞ ≤ lnω ≤ + ∞. The integration procedure is
Score Function of Distribution and Revival of the Moment Method
Czech Academy of Sciences Publication Activity Database
Fabián, Zdeněk
2016-01-01
Roč. 45, č. 4 (2016), s. 1118-1136 ISSN 0361-0926 R&D Projects: GA MŠk(CZ) LG12020 Institutional support: RVO:67985807 Keywords : characteristics of distributions * data characteristics * general moment method * Huber moment estimator * parametric methods * score function Subject RIV: BB - Applied Statistics , Operational Research Impact factor: 0.311, year: 2016
Numerical Loading of a Maxwellian Probability Distribution Function
International Nuclear Information System (INIS)
Lewandowski, J.L.V.
2003-01-01
A renormalization procedure for the numerical loading of a Maxwellian probability distribution function (PDF) is formulated. The procedure, which involves the solution of three coupled nonlinear equations, yields a numerically loaded PDF with improved properties for higher velocity moments. This method is particularly useful for low-noise particle-in-cell simulations with electron dynamics
Three-dimensional coupled double-distribution-function lattice ...
Indian Academy of Sciences (India)
Ruo-Fan Qiu
2017-11-14
Nov 14, 2017 ... Abstract. Two three-dimensional (3D) lattice Boltzmann models in the framework of coupled double-distribution- function approach for compressible flows, in which specific-heat ratio and Prandtl number can be adjustable, are developed in this paper. The main differences between the two models are ...
Photon distribution function for stocks wave for stimulated Raman scattering
International Nuclear Information System (INIS)
Man'ko, O.V.; Tcherniega, N.V.
1997-04-01
New time-dependent integrals of motion are found for stimulated Raman scattering. Explicit formula for the photon-number probability distribution as a function of the laser-field intensity and the medium parameters is obtained in terms of Hermite polynomials of two variables. (author). 29 refs
Wigner distribution function of circularly truncated light beams
Bastiaans, M.J.; Nijhawan, O.P.; Gupta, A.K.; Musla, A.K.; Singh, Kehar
1998-01-01
Truncating a light beam is expressed as a convolution of its Wigner distribution function and the WDF of the truncating aperture. The WDF of a circular aperture is derived and an approximate expression - which is exact in the space and the spatial-frequency origin and whose integral over the spatial
Electron-cyclotron-resonant-heated electron distribution functions
International Nuclear Information System (INIS)
Matsuda, Y.; Nevins, W.M.; Cohen, R.H.
1981-01-01
Recent studies at Lawrence Livermore National Laboratory (LLNL) with a bounce-averaged Fokker-Planck code indicate that the energetic electron tail formed by electron-cyclotron resonant heating (ECRH) at the second harmonic is not Maxwellian. We present the results of our bounce-averaged Fokker-Planck code along with some simple analytic models of hot-electron distribution functions
Parton distribution functions in the context of parton showers
International Nuclear Information System (INIS)
Nagy, Zoltán; Soper, Davison E.
2014-01-01
When the initial state evolution of a parton shower is organized according to the standard “backward evolution” prescription, ratios of parton distribution functions appear in the splitting probabilities. The shower thus organized evolves from a hard scale to a soft cutoff scale. At the end of the shower, one expects that only the parton distributions at the soft scale should affect the results. The other effects of the parton distributions should have cancelled. This means that the kernels for parton evolution should be related to the shower splitting functions. If the initial state partons can have non-zero masses, this requires that the evolution kernels cannot be the usual (MS)-bar kernels. We work out what the parton evolution kernels should be to match the shower evolution contained in the parton shower event generator DEDUCTOR, in which the b and c quarks have non-zero masses.
Energy Technology Data Exchange (ETDEWEB)
Couture, O; Cherin, E; Foster, F S [Imaging Research, Sunnybrook Health Sciences Centre/University of Toronto, Toronto (Canada)
2007-07-21
A model predicting the reflection of ultrasound from multiple layers of small scattering spheres is developed. Predictions of the reflection coefficient, which takes into account the interferences between the different sphere layers, are compared to measurements performed in the 10-80 MHz and 15-35 MHz frequency range with layers of glass beads and spherical acute myeloid leukemia (AML) cells, respectively. For both types of scatterers, the reflection coefficient increases as a function of their density on the surface for less than three superimposed layers, at which point it saturates at 0.38 for glass beads and 0.02 for AML cells. Above three layers, oscillations of the reflection coefficient due to constructive or destructive interference between layers are observed experimentally and are accurately predicted by the model. The use of such a model could lead to a better understanding of the structures observed in layered tissue images.
Plasma dispersion function for a Fermi-Dirac distribution
International Nuclear Information System (INIS)
Melrose, D. B.; Mushtaq, A.
2010-01-01
A plasma dispersion function (PDF) is defined for a nonrelativistic Fermi-Dirac distribution and its properties are explored. The degree of degeneracy is described by a parameter ξ=e μ e /T e , for electrons, with μ e /T e large and negative in the nondegenerate limit, and large and positive in the completely degenerate limit. The PDF is denoted Z(y,ξ), where the variable y=ω/√(2)kV e , is the argument of the conventional PDF, Z(y)=Z(y,0), for a Maxwellian distribution. In the completely degenerate limit, Z(y,ξ) approaches a logarithmic function that depends on the Fermi temperature and is independent of T e . Analytic approximations to Z(y,ξ) are derived in terms of polylogarithmic functions for y 2 >>1 and for y 2 <<1.
Barnes-Holmes, Dermot; Hussey, Ian
2016-02-01
The functional-cognitive meta-theoretical framework has been offered as a conceptual basis for facilitating greater communication and cooperation between the functional/behavioural and cognitive traditions within psychology, thus leading to benefits for both scientific communities. The current article is written from the perspective of two functional researchers, who are also proponents of the functional-cognitive framework, and attended the "Building Bridges between the Functional and Cognitive Traditions" meeting at Ghent University in the summer of 2014. The article commences with a brief summary of the functional approach to theory, followed by our reflections upon the functional-cognitive framework in light of that meeting. In doing so, we offer three ways in which the framework could be clarified: (a) effective communication between the two traditions is likely to be found at the level of behavioural observations rather than effects or theory, (b) not all behavioural observations will be deemed to be of mutual interest to both traditions, and (c) observations of mutual interest will be those that serve to elaborate and extend existing theorising in the functional and/or cognitive traditions. The article concludes with a summary of what we perceive to be the strengths and weaknesses of the framework, and a suggestion that there is a need to determine if the framework is meta-theoretical or is in fact a third theoretical approach to doing psychological science. © 2015 International Union of Psychological Science.
Do seedling functional groups reflect ecological strategies of woody plant species in Caatinga?
Directory of Open Access Journals (Sweden)
Tatiane Gomes Calaça Menezes
2017-11-01
Full Text Available ABSTRACT It is assumed that morphological traits of seedlings reflect different strategies in response to environmental conditions. The ecological significance of this has been widely documented in rainforests, where habitat structure and species interactions play an important role in community assembly. However, in seasonally dry ecosystems, where environmental filtering is expected to strongly influence community structure, this relationship is poorly understood. We investigated this relationship between functional groups of seedlings and life history traits and tested whether functional group predicts the ecological strategies employed by woody species to deal with the stressful conditions in seasonally dry ecosystems. Seedling functional groups, life history traits and traits that reflect ecological strategies for occupying seasonally dry environments were described for twenty-six plant species. Seedlings of species from the Caatinga vegetation exhibited a functional profile different from that observed in rainforests ecosystems. Phanerocotylar-epigeal seedlings were the most frequently observed groups, and had the largest range of ecological strategies related to dealing with seasonally dry environments, while phanerocotylar-hypogeal-reserve seedlings exhibited an increase in frequency with seasonality. We discuss these results in relation to those observed in other tropical forests and their ecological significance in seasonally dry environments.
Modelling and Order of Acoustic Transfer Functions Due to Reflections from Augmented Objects
Directory of Open Access Journals (Sweden)
Diemer de Vries
2007-01-01
Full Text Available It is commonly accepted that the sound reflections from real physical objects are much more complicated than what usually is and can be modelled by room acoustics modelling software. The main reason for this limitation is the level of detail inherent in the physical object in terms of its geometrical and acoustic properties. In the present paper, the complexity of the sound reflections from a corridor wall is investigated by modelling the corresponding acoustic transfer functions at several receiver positions in front of the wall. The complexity for different wall configurations has been examined and the changes have been achieved by altering its acoustic image. The results show that for a homogenous flat wall, the complexity is significant and for a wall including various smaller objects, the complexity is highly dependent on the position of the receiver with respect to the objects.
Effect of black silicon disordered structures distribution on its wideband reduced reflectance
International Nuclear Information System (INIS)
Saab, D Abi; Mostarshedi, S; Basset, P; Protat, S; Angelescu, D; Richalot, E
2014-01-01
We present a simple and accurate model for the reflectance simulation of black silicon (BSi) based on the finite element method (FEM). Normalized-root-mean-square error (NRMSE) with experimental measurements below 0.25% has been obtained for wavelength range between 450 and 950 nm. The model is made of a four basic shape cell whose dimensions are extracted from an accurate topography of the BSi obtained by FIB-SEM tomography. Additional BSi modelling techniques were studied, which take into account the BSi irregular topography, demonstrating an important influence of the local structure height variation in the BSi surface spectral reflectance. (paper)
Ćurčić-Blake, Branislava; van der Meer, Lisette; Pijnenborg, Gerdina H M; David, Anthony S; Aleman, André
2015-12-01
Impaired insight into illness, associated with worse treatment outcome, is common in schizophrenia. Insight has been related to the self-reflective processing, centred on the medial frontal cortex. We hypothesized that anatomical and functional routes to and from the ventromedial prefrontal cortex (vmPFC) would differ in patients according to their degree of impaired insight. Forty-five schizophrenia patients and 19 healthy subjects performed a self-reflection task during fMRI, and underwent diffusion tensor imaging. Using dynamic causal modelling we observed increased effective connectivity from the posterior cingulate cortex (PCC), inferior parietal lobule (IPL), and dorsal mPFC (dmPFC) towards the vmPFC with poorer insight and decrease from vmPFC to the IPL. Stronger connectivity from the PCC to vmPFC during judgment of traits related to self was associated with poorer insight. We found small-scale significant changes in white matter integrity associated with clinical insight. Self-reflection may be influenced by synaptic changes that lead to the observed alterations in functional connectivity accompanied by the small-scale but measurable alterations in anatomical connections. Our findings may point to a neural compensatory response to an impairment of connectivity between self-processing regions. Similarly, the observed hyper-connectivity might be a primary deficit linked to inefficiency in the component cognitive processes that lead to impaired insight. We suggest that the stronger cognitive demands placed on patients with poor insight is reflected in increased effective connectivity during the task in this study. © 2015 Wiley Periodicals, Inc.
Decomposing Wage Distributions Using Recentered Influence Function Regressions
Directory of Open Access Journals (Sweden)
Sergio P. Firpo
2018-05-01
Full Text Available This paper provides a detailed exposition of an extension of the Oaxaca-Blinder decomposition method that can be applied to various distributional measures. The two-stage procedure first divides distributional changes into a wage structure effect and a composition effect using a reweighting method. Second, the two components are further divided into the contribution of each explanatory variable using recentered influence function (RIF regressions. We illustrate the practical aspects of the procedure by analyzing how the polarization of U.S. male wages between the late 1980s and the mid 2010s was affected by factors such as de-unionization, education, occupations, and industry changes.
Universal Probability Distribution Function for Bursty Transport in Plasma Turbulence
International Nuclear Information System (INIS)
Sandberg, I.; Benkadda, S.; Garbet, X.; Ropokis, G.; Hizanidis, K.; Castillo-Negrete, D. del
2009-01-01
Bursty transport phenomena associated with convective motion present universal statistical characteristics among different physical systems. In this Letter, a stochastic univariate model and the associated probability distribution function for the description of bursty transport in plasma turbulence is presented. The proposed stochastic process recovers the universal distribution of density fluctuations observed in plasma edge of several magnetic confinement devices and the remarkable scaling between their skewness S and kurtosis K. Similar statistical characteristics of variabilities have been also observed in other physical systems that are characterized by convection such as the x-ray fluctuations emitted by the Cygnus X-1 accretion disc plasmas and the sea surface temperature fluctuations.
Multi-Functional Distributed Generation Unit for Power Quality Enhancement
DEFF Research Database (Denmark)
Zeng, Zheng; Yang, Huan; Guerrero, Josep M.
2015-01-01
A multi-functional distributed generation unit (MFDGU) and its control strategy are proposed in this paper for the purpose of enhancing power quality in low-voltage networks. By using the 3H-bridge converter structure, an MFDGU can be applied in 3-phase 4-wire low-voltage distribution networks...... reference of the MFDGU, which can be easily implemented in three-phase networks. A 15kVA prototype consisting of three full bridge converters has been built and tested. Experimental results show the feasibility of the proposed topology and control strategy....
Electrical Distribution System Functional Inspection (EDSFI) data base program
International Nuclear Information System (INIS)
Gautam, A.
1993-01-01
This document describes the organization, installation procedures, and operating instructions for the database computer program containing inspection findings from the US Nuclear Regulatory Commission's (NRC's) Electrical Distribution System Functional Inspections (EDSFIs). The program enables the user to search and sort findings, ascertain trends, and obtain printed reports of the findings. The findings include observations, unresolved issues, or possible deficiencies in the design and implementation of electrical distribution systems in nuclear plants. This database will assist those preparing for electrical inspections, searching for deficiencies in a plant, and determining the corrective actions previously taken for similar deficiencies. This database will be updated as new EDSFIs are completed
Directory of Open Access Journals (Sweden)
Z. Meghnatisi
2009-06-01
Full Text Available Let Xi1, · · · , Xini be a random sample from a gamma distribution with known shape parameter νi > 0 and unknown scale parameter βi > 0, i = 1, 2, satisfying 0 < β1 6 β2. We consider the class of mixed estimators for estimation of β1 and β2 under reflected gamma loss function. It has been shown that the minimum risk equivariant estimator of βi, i = 1, 2, which is admissible when no information on the ordering of parameters are given, is inadmissible and dominated by a class of mixed estimators when it is known that the parameters are ordered. Also, the inadmissible estimators in the class of mixed estimators are derived. Finally the results are extended to some subclass of exponential family
Effects of perfluorochemical distribution and elimination dynamics on cardiopulmonary function.
Miller, T F; Milestone, B; Stern, R; Shaffer, T H; Wolfson, M R
2001-03-01
Based on a physicochemical property profile, we tested the hypothesis that different perfluorochemical (PFC) liquids may have distinct effects on intrapulmonary PFC distribution, lung function, and PFC elimination kinetics during partial liquid ventilation (PLV). Young rabbits were studied in five groups [healthy, PLV with perflubron (PFB) or with perfluorodecalin (DEC); saline lavage injury and conventional mechanical ventilation (CMV); saline lavage injury PLV with PFB or with DEC]. Arterial blood chemistry, respiratory compliance (Cr), quantitative computed tomography of PFC distribution, and PFC loss rate were assessed for 4 h. Initial distribution of PFB was more homogenous than that of DEC; over time, PFB redistributed to dependent regions whereas DEC distribution was relatively constant. PFC loss rate decreased over time in all groups, was higher with DEC than PFB, and was lower with injury. In healthy animals, arterial PO(2) (Pa(O(2))) and Cr decreased with either PFC; the decrease was greater and sustained with DEC. Lavaged animals treated with either PFC demonstrated increased Pa(O(2)), which was sustained with PFB but deteriorated with DEC. Lavaged animals treated with PFB demonstrated increased Cr, higher Pa(O(2)), and lower arterial PCO(2) than with CMV or PLV with DEC. The results indicate that 1) initial distribution and subsequent intrapulmonary redistribution of PFC are related to PFC properties; 2) PFC distribution influences PFC elimination, gas exchange, and Cr; and 3) PFC elimination, gas exchange, and Cr are influenced by PFC properties and lung condition.
26 CFR 1.312-1 - Adjustment to earnings and profits reflecting distributions by corporations.
2010-04-01
... profits of the issuing corporation upon a disposition of section 306 stock unless such disposition is a... distribution of property by a corporation with respect to its stock, its earnings, and profits (to the extent... distribution of stock or rights to acquire stock a portion of which is includible in income by reason of...
Gaze Step Distributions Reflect Fixations and Saccades: A Comment on Stephen and Mirman (2010)
Bogartz, Richard S.; Staub, Adrian
2012-01-01
In three experimental tasks Stephen and Mirman (2010) measured gaze steps, the distance in pixels between gaze positions on successive samples from an eyetracker. They argued that the distribution of gaze steps is best fit by the lognormal distribution, and based on this analysis they concluded that interactive cognitive processes underlie eye…
Raindrop size distribution and radar reflectivity-rain rate relationships for radar hydrology
Uijlenhoet, R.
2001-01-01
The conversion of the radar reflectivity factor Z (mm6m-3) to rain rate R (mm h-1) is a crucial step in the hydrological application of weather radar measurements. It has been common practice for over 50 years now to take for this conversion a simple power law relationship between Z and R. It is the
International Nuclear Information System (INIS)
Boyd, D.A.; Skiff, F.; Gulick, S.
1997-01-01
A two-chord, four-beam suprathermal electron diagnostic has been installed on TdeV (B>1.5 T, R=0.86 m, a=0.25 m). Resonant absorption of extraordinary mode electron cyclotron waves is measured to deduce the chordal averaged suprathermal electron distribution function amplitude at the resonant momentum. Simultaneously counterpropagating beams permit good refractive loss cancellation. A nonlinear frequency sweep leads to a concentration of appropriately propagating power in a narrow range of time of flight, thus increasing the signal-to-noise ratio and facilitating the rejection of spurious reflections. Numerous measurements of electron distribution functions have been obtained during lower-hybrid current-drive experiments. copyright 1997 American Institute of Physics
Zwart, Hub; Brenninkmeijer, Jonna; Eduard, Peter; Krabbenborg, Lotte; Laursen, Sheena; Revuelta, Gema; Toonders, Winnie
2017-01-01
In 1968, Jürgen Habermas claimed that, in an advanced technological society, the emancipatory force of knowledge can only be regained by actively recovering the 'forgotten experience of reflection'. In this article, we argue that, in the contemporary situation, critical reflection requires a deliberative ambiance, a process of mutual learning, a consciously organised process of deliberative and distributed reflection. And this especially applies, we argue, to critical reflection concerning a specific subset of technologies which are actually oriented towards optimising human cognition (neuro-enhancement). In order to create a deliberative ambiance, fostering critical upstream reflection on emerging technologies, we developed (in the context of a European 7 th Framework Programme project on neuro-enhancement and responsible research and innovation, called NERRI) the concept of a mutual learning exercise (MLE). Building on a number of case studies, we analyse what an MLE involves, both practically and conceptually, focussing on key aspects such as ambiance and expertise, the role of 'genres of the imagination' and the profiles of various 'subcultures of debate'. Ideally, an MLE becomes a contemporary version of the Socratic agora, providing a stage where multiple and sometimes unexpected voices and perspectives mutually challenge each other, in order to strength-en the societal robustness and responsiveness of emerg-ing technologies.
Spatial distribution measured by the modulation transfer function
International Nuclear Information System (INIS)
Rossi, P.; Brice, D.K.; Doyle, B.L.
2003-01-01
Spatial distributions in ion micro-beam and IBA experimental practice are regularly characterized through the parameters of FWHM and tail area percentage (TF, tail fraction). Linear and stationary transducer theory allows these distributions to be described in the Fourier-dual frequency space, and provides an indirect method to evaluate them through measurement of the modulation transfer function (MTF). We suggest direct measurement of MTF by employing bar pattern grids, similar to those used for calibration of radiological equipment. Assuming spatial distributions of the form exp(-(|αx|) η ), we are able to relate the MTF measurements to the more popular FWHM and TF. This new approach to determine spatial resolution can become a standard for use by the micro-beam community
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.
Parton distribution functions with QED corrections in the valon model
Mottaghizadeh, Marzieh; Taghavi Shahri, Fatemeh; Eslami, Parvin
2017-10-01
The parton distribution functions (PDFs) with QED corrections are obtained by solving the QCD ⊗QED DGLAP evolution equations in the framework of the "valon" model at the next-to-leading-order QCD and the leading-order QED approximations. Our results for the PDFs with QED corrections in this phenomenological model are in good agreement with the newly related CT14QED global fits code [Phys. Rev. D 93, 114015 (2016), 10.1103/PhysRevD.93.114015] and APFEL (NNPDF2.3QED) program [Comput. Phys. Commun. 185, 1647 (2014), 10.1016/j.cpc.2014.03.007] in a wide range of x =[10-5,1 ] and Q2=[0.283 ,108] GeV2 . The model calculations agree rather well with those codes. In the latter, we proposed a new method for studying the symmetry breaking of the sea quark distribution functions inside the proton.
Strict calculation of electron energy distribution functions in inhomogeneous plasmas
International Nuclear Information System (INIS)
Winkler, R.
1996-01-01
It is objective of the paper to report on strict calculations of the velocity or energy distribution function function and related macroscopic properties of the electrons from appropriate electron kinetic equations under various plasma conditions and to contribute to a better understanding of the electron behaviour in inhomogeneous plasma regions. In particular, the spatial relaxation of plasma electrons acted upon by uniform electric fields, the response of plasma electrons on spatial disturbances of the electric field, the electron kinetics under the impact of space charge field confinement in the dc column plasma and the electron velocity distribution is stronger field as occurring in the electrode regions of a dc glow discharge is considered. (author)
Water distribution function across the curved lipid bilayer: SANS study
International Nuclear Information System (INIS)
Kiselev, M.A.; Zemlyanaya, E.V.; Ryabova, N.Y.; Hauss, T.; Dante, S.; Lombardo, D.
2008-01-01
The neutron scattering length density across the membrane is simulated on the basis of fluctuated model of lipid bilayer. The use of a separated form factors method has been applied for the identification of the structural features of the polydispersed unilamellar DMPC vesicle system. The hydration of vesicle is described by sigmoid distribution function of the water molecules. The application of the model to the obtained SANS spectra allow the determination of the main parameters of the system, such as the average vesicle radius (and its polydispersity), the membrane thickness, the thickness of hydrocarbon chain region, the number of water molecules located per lipid molecule, and the phospholipid surface area. Moreover the approach allow the calculation of some relevant parameters connected with the water distribution function across the bilayer system. The main features of the obtained results furnish an explanation of why lipid membrane is easily penetrated by the water molecules of the solution
Sequential function approximation on arbitrarily distributed point sets
Wu, Kailiang; Xiu, Dongbin
2018-02-01
We present a randomized iterative method for approximating unknown function sequentially on arbitrary point set. The method is based on a recently developed sequential approximation (SA) method, which approximates a target function using one data point at each step and avoids matrix operations. The focus of this paper is on data sets with highly irregular distribution of the points. We present a nearest neighbor replacement (NNR) algorithm, which allows one to sample the irregular data sets in a near optimal manner. We provide mathematical justification and error estimates for the NNR algorithm. Extensive numerical examples are also presented to demonstrate that the NNR algorithm can deliver satisfactory convergence for the SA method on data sets with high irregularity in their point distributions.
Charge symmetry breaking in parton distribution functions from lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Horsley, R.; Zanotti, J.M. [Edinburgh Univ. (United Kingdom). School of Physics and Astronomy; Nakamura, Y. [Regensburg Univ. (Germany). Inst. fuer Theoretische Physik; Tsukuba Univ., Ibaraki (Japan). Center for Computational Sciences; Pleiter, D. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Rakow, P.E.L. [Liverpool Univ. (United Kingdom). Theoretical Physics Div.; Schierholz, G. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Stueben, H. [Konrad-Zuse-Zentrum fuer Informationstechnik Berlin (Germany); Thomas, A.W.; Young, R.D. [Adelaide Univ. SA (Australia). School of Physics and Chemistry; Winter, F. [Edinburgh Univ. (United Kingdom). School of Physics and Astronomy; Regensburg Univ. (Germany). Inst. fuer Theoretische Physik
2010-12-15
By determining the quark momentum fractions of the octet baryons from N{sub f}=2+1 lattice simulations, we are able to predict the degree of charge symmetry violation in the parton distribution functions of the nucleon. This is of importance, not only as a probe of our understanding of the non-perturbative structure of the proton but also because such a violation constrains the accuracy of global ts to parton distribution functions and hence the accuracy with which, for example, cross sections at the LHC can be predicted. A violation of charge symmetry may also be critical in cases where symmetries are used to guide the search for physics beyond the Standard Model. (orig.)
Charge symmetry breaking in parton distribution functions from lattice QCD
International Nuclear Information System (INIS)
Horsley, R.; Zanotti, J.M.; Rakow, P.E.L.; Stueben, H.; Thomas, A.W.; Young, R.D.; Winter, F.; Regensburg Univ.
2010-12-01
By determining the quark momentum fractions of the octet baryons from N f =2+1 lattice simulations, we are able to predict the degree of charge symmetry violation in the parton distribution functions of the nucleon. This is of importance, not only as a probe of our understanding of the non-perturbative structure of the proton but also because such a violation constrains the accuracy of global ts to parton distribution functions and hence the accuracy with which, for example, cross sections at the LHC can be predicted. A violation of charge symmetry may also be critical in cases where symmetries are used to guide the search for physics beyond the Standard Model. (orig.)
Beam brightness calculation for analytical and empirical distribution functions
International Nuclear Information System (INIS)
Myers, T.J.; Boulais, K.A.; O, Y.S.; Rhee, M.J.
1992-01-01
The beam brightness, a figure of merit for a beam quality useful for high-current low-emittance beams, was introduced by van Steenbergen as B = I/V 4 , where I is the beam current and V 4 is the hypervolume in the four-dimensional trace space occupied by the beam particles. Customarily, the brightness is expressed in terms of the product of emittances ε x ε y as B = ηI/(π 2 ε x ε y ), where η is a form factor of order unity which depends on the precise definition of emittance and hypervolume. Recently, a refined definition of the beam brightness based on the arithmetic mean value defined in statistics is proposed. The beam brightness is defined as B triple-bond 4 > = I -1 ∫ ρ 4 2 dxdydx'dy', where I is the beam current given by I ∫ ρ 4 dxdydx'dy'. Note that in this definition, neither the hypervolume V 4 nor the emittance, are explicitly used; the brightness is determined solely by the distribution function. Brightnesses are unambiguously calculated and expressed analytically in terms of the respective beam current and effective emittance for a few commonly used distribution functions, including Maxwellian and water-bag distributions. Other distributions of arbitrary shape frequently encountered in actual experiments are treated numerically. The resulting brightnesses are expressed in the form B = ηI/(π 2 ε x ε y ), and η is found to be weakly dependent on the form of velocity distribution as well as spatial distribution
Distribution functions of sections and projections of convex bodies
Kim, Jaegil; Yaskin, Vladyslav; Zvavitch, Artem
2015-01-01
Typically, when we are given the section (or projection) function of a convex body, it means that in each direction we know the size of the central section (or projection) perpendicular to this direction. Suppose now that we can only get the information about the sizes of sections (or projections), and not about the corresponding directions. In this paper we study to what extent the distribution function of the areas of central sections (or projections) of a convex body can be used to derive ...
The Wigner distribution function for squeezed vacuum superposed state
International Nuclear Information System (INIS)
Zayed, E.M.E.; Daoud, A.S.; AL-Laithy, M.A.; Naseem, E.N.
2005-01-01
In this paper, we construct the Wigner distribution function for a single-mode squeezed vacuum mixed-state which is a superposition of the squeezed vacuum state. This state is defined as a P-representation for the density operator. The obtained Wigner function depends, beside the phase-space variables, on the mean number of photons occupied by the coherent state of the mode. This mean number relates to the mean free path through a given relation, which enables us to measure this number experimentally by measuring the mean free path
Probabilistic Q-function distributions in fermionic phase-space
International Nuclear Information System (INIS)
Rosales-Zárate, Laura E C; Drummond, P D
2015-01-01
We obtain a positive probability distribution or Q-function for an arbitrary fermionic many-body system. This is different to previous Q-function proposals, which were either restricted to a subspace of the overall Hilbert space, or used Grassmann methods that do not give probabilities. The fermionic Q-function obtained here is constructed using normally ordered Gaussian operators, which include both non-interacting thermal density matrices and BCS states. We prove that the Q-function exists for any density matrix, is real and positive, and has moments that correspond to Fermi operator moments. It is defined on a finite symmetric phase-space equivalent to the space of real, antisymmetric matrices. This has the natural SO(2M) symmetry expected for Majorana fermion operators. We show that there is a physical interpretation of the Q-function: it is the relative probability for observing a given Gaussian density matrix. The distribution has a uniform probability across the space at infinite temperature, while for pure states it has a maximum value on the phase-space boundary. The advantage of probabilistic representations is that they can be used for computational sampling without a sign problem. (fast track communication)
The electron energy distribution function of noble gases with flow
International Nuclear Information System (INIS)
Karditsas, P.J.
1989-01-01
The treatment of the Boltzmann equation by several investigators, for the determination of the electron energy distribution function (EEDF) in noble gases was restricted to static discharges. It is of great interest to magnetoplasmadynamic power generation to develop the Boltzmann equation to account for the effect of the bulk fluid flow on the EEDF. The two term expansion of the Boltzmann equation, as given, results in additional terms introduced to the equations due to the bulk fluid flow, with velocity u
Q2 evolution of a soft gluon distribution function
International Nuclear Information System (INIS)
Enkovskij, L.L.; Kotikov, A.V.; Pakkanoni, F.
1992-01-01
Model parameter dependence refferring to the function of gluon distribution linked with the exchange of a dipole pomeron from Q 2 is calculated within the framework of the Gribov-Lipatov-Altarelli-Parisi evolution equation (GLAP) both in the leading logarithm approximation and in the double logarithmic approximation. The behaviour of logarithmic parametrization ∼ (ln(1/x)) b appears to be unstable in relation to perturbative calculations
Brookhaven Reactor Experiment Control Facility, a distributed function computer network
International Nuclear Information System (INIS)
Dimmler, D.G.; Greenlaw, N.; Kelley, M.A.; Potter, D.W.; Rankowitz, S.; Stubblefield, F.W.
1975-11-01
A computer network for real-time data acquisition, monitoring and control of a series of experiments at the Brookhaven High Flux Beam Reactor has been developed and has been set into routine operation. This reactor experiment control facility presently services nine neutron spectrometers and one x-ray diffractometer. Several additional experiment connections are in progress. The architecture of the facility is based on a distributed function network concept. A statement of implementation and results is presented
DEFF Research Database (Denmark)
Kjeldsen, Tinne Hoff; Blomhøj, Morten
2013-01-01
position held by the modeler(s) and the practitioners in the extra-mathematical domain. For students to experience the significance of different scientific practices and cultures for the function and status of mathematical modeling in other sciences, students need to be placed in didactical situations......Mathematical models and mathematical modeling play different roles in the different areas and problems in which they are used. The function and status of mathematical modeling and models in the different areas depend on the scientific practice as well as the underlying philosophical and theoretical...... where such differences are exposed and made into explicit objects of their reflections. It can be difficult to create such situations in the teaching of contemporary science in which modeling is part of the culture. In this paper we show how history can serve as a means for students to be engaged...
Kark, Sarah M; Slotnick, Scott D; Kensinger, Elizabeth A
2016-12-01
Most studies using a recognition memory paradigm examine the neural processes that support the ability to consciously recognize past events. However, there can also be nonconscious influences from the prior study episode that reflect repetition suppression effects-a reduction in the magnitude of activity for repeated presentations of stimuli-that are revealed by comparing neural activity associated with forgotten items to correctly rejected novel items. The present fMRI study examined the effect of emotional valence (positive vs. negative) on repetition suppression effects. Using a standard recognition memory task, 24 participants viewed line drawings of previously studied negative, positive, and neutral photos intermixed with novel line drawings. For each item, participants made an old-new recognition judgment and a sure-unsure confidence rating. Collapsed across valence, repetition suppression effects were found in ventral occipital-temporal cortex and frontal regions. Activity levels in the majority of these regions were not modulated by valence. However, repetition enhancement of the amygdala and ventral occipital-temporal cortex functional connectivity reflected nonconscious memory for negative items. In this study, valence had little effect on activation patterns but had a larger effect on functional connectivity patterns that were markers of nonconscious memory. Beyond memory and emotion, these findings are relevant to other cognitive and social neuroscientists that utilize fMRI repetition effects to investigate perception, attention, social cognition, and other forms of learning and memory.
Theoretical derivation of wind power probability distribution function and applications
International Nuclear Information System (INIS)
Altunkaynak, Abdüsselam; Erdik, Tarkan; Dabanlı, İsmail; Şen, Zekai
2012-01-01
Highlights: ► Derivation of wind power stochastic characteristics are standard deviation and the dimensionless skewness. ► The perturbation is expressions for the wind power statistics from Weibull probability distribution function (PDF). ► Comparisons with the corresponding characteristics of wind speed PDF abides by the Weibull PDF. ► The wind power abides with the Weibull-PDF. -- Abstract: The instantaneous wind power contained in the air current is directly proportional with the cube of the wind speed. In practice, there is a record of wind speeds in the form of a time series. It is, therefore, necessary to develop a formulation that takes into consideration the statistical parameters of such a time series. The purpose of this paper is to derive the general wind power formulation in terms of the statistical parameters by using the perturbation theory, which leads to a general formulation of the wind power expectation and other statistical parameter expressions such as the standard deviation and the coefficient of variation. The formulation is very general and can be applied specifically for any wind speed probability distribution function. Its application to two-parameter Weibull probability distribution of wind speeds is presented in full detail. It is concluded that provided wind speed is distributed according to a Weibull distribution, the wind power could be derived based on wind speed data. It is possible to determine wind power at any desired risk level, however, in practical studies most often 5% or 10% risk levels are preferred and the necessary simple procedure is presented for this purpose in this paper.
Teachers' reflections on distributive leadership in public primary schools in Soweto
Directory of Open Access Journals (Sweden)
Suraiya R Naicker
2013-01-01
Full Text Available Schooling has become increasingly complex in purpose and structure and therefore requires appropriate forms of leadership to address this challenge. One current leadership approach that is receiving national and global attention is distributive leadership. A qualitative approach was employed to investigate teachers' experiences and perceptions of the practice of distributive leadership in public primary schools in Soweto. Soweto is a township in Johannesburg, South Africa, which comprises predominantly black African residents. The findings revealed that leadership in Soweto primary schools is rooted in classical leadership practices and that any potential for the practice of distributive leadership is hindered by autocratic styles of leadership, hierarchical structures, and non-participative decision-making.
Directory of Open Access Journals (Sweden)
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.
Generation of Optimal Basis Functions for Reconstruction of Power Distribution
Energy Technology Data Exchange (ETDEWEB)
Park, Moonghu [Sejong Univ., Seoul (Korea, Republic of)
2014-05-15
This study proposes GMDH to find not only the best functional form but also the optimal parameters those describe the power distribution most accurately. A total of 1,060 cases of axially 1-dimensional core power distributions of 20-nodes are generated by 3-dimensional core analysis code covering BOL to EOL core burnup histories to validate the method. Axially five-point box powers at in-core detectors are considered as measurements. The reconstructed axial power shapes using GMDH method are compared to the reference power shapes. The results show that the proposed method is very robust and accurate compared with spline fitting method. It is shown that the GMDH analysis can give optimal basis functions for core power shape reconstruction. The in-core measurements are the 5 detector snapshots and the 20-node power distribution is successfully reconstructed. The effectiveness of the method is demonstrated by comparing the results of spline fitting for BOL, saddle and top-skewed power shapes.
Quasilinear ion distribution function during first harmonic ion cyclotron heating
International Nuclear Information System (INIS)
Brambilla, M.
1993-12-01
The quasilinear modification of the ion distribution function during first harmonic ion cyclotron (FHIC) heating is investigated both with a simple already well established analytic one-dimensional approach, and with a new two dimensional steady state solver of the quasilinear kinetic equation, SSFPQL. By accepting to disregard the effects of ion trapping in banana orbits, but including finite Larmor radius effects, the latter code has been made much faster than full surface-averaged codes; yet it can provide most of the relevant information on the suprathermal ion tail produced by this heating method. With SSFPQL we confirm that the one-dimensional model gives fair approximations for global properties of the distribution function, such as the average energy content of the tail and the fusion reactivity. On the other hand the tail is found to be very anisotropic, the increase of the parallel effective temperature being a small fraction of the total energy increase. Information on the anisotropy is essential to study the feedback of the fast ion tail on wave propagation and absorption, which is quite sensitive to the distribution of parallel velocities. The insight gained in the derivation and discussion of this model can be used to build a selfconsistent description of this heating scenario, whose implementation requires only a reasonable numerical effort. (orig.)
Sedimentary alkenone distributions reflect salinity changes in the Baltic Sea over the Holocene
Warden, L.A.; van der Meer, M.T.J.; Moros, Matthias; Sinninghe Damsté, J.S.
2016-01-01
The Baltic Sea has had a complex salinity history since the last deglaciation. Here we show how distributions of alkenones and their δD values varied with past fluctuations in salinity in the Baltic Sea over the Holocene by examining a Holocene record (11.2–0.1 cal kyr BP) from the Arkona Basin.
New light on an old problem: Reflections on barriers and enablers of distributed energy
International Nuclear Information System (INIS)
Szatow, Anthony; Quezada, George; Lilley, Bill
2012-01-01
This viewpoint article, New light on an Old Problem, aims to stimulate thought and discussion on pathways to rapid emission reduction trajectories. It considers briefly the history of the Australian energy system and recent attempts to support emerging, distributed energy supply systems, before exploring the importance of new energy supply models and how they may emerge organically, ahead of further policy and regulatory shifts in Australia. The article is shaped by extensive primary research, literature review and engagement with policy makers, industry and community organisations, energy market institutions, colleagues and others over a period of four years. It outlines how new business models may reduce emissions ahead of policy and regulation, and the importance of keeping an open mind when considering ‘barriers’ to distributed energy. We hope this article will spark interest and dialogue with colleagues who may be experiencing and grappling with similar challenges. - Research highlights: ► We discuss documented barriers to distributed energy. ► We draw on socio-technical system literature and our research experience to outline a possible solution to distributed energy barriers. ► We describe a hypothetical energy service business model, led by the property sector, as a catalyst for energy market change. ► We outline reasons for our confidence in this property sector led energy services model.
Directory of Open Access Journals (Sweden)
Khanh eDao Duc
2015-07-01
Full Text Available The dynamics of neuronal networks connected by synaptic dynamics can sustain long periods of depolarization that can last for hundreds of milliseconds such as Up states recorded during sleep or anesthesia. Yet the underlying mechanism driving these periods remain unclear. We show here within a mean-field model that the residence times of the neuronal membrane potential in cortical Up states does not follow a Poissonian law, but presents several peaks. Furthermore, the present modeling approach allows extracting some information about the neuronal network connectivity from the time distribution histogram. Based on a synaptic-depression model, we find that these peaks, that can be observed in histograms of patch-clamp recordings are not artifacts of electrophysiological measurements, but rather are an inherent property of the network dynamics. Analysis of the equations reveals a stable focus located close to the unstable limit cycle, delimiting a region that defines the Up state. The model further shows that the peaks observed in the Up state time distribution are due to winding around the focus before escaping from the basin of attraction. Finally, we use in vivo recordings of intracellular membrane potential and we recover from the peak distribution, some information about the network connectivity. We conclude that it is possible to recover the network connectivity from the distribution of times that the neuronal membrane voltage spends in Up states.
Volpe, Noelia L; Hadley, Adam S; Robinson, W Douglas; Betts, Matthew G
Translocation experiments, in which researchers displace animals and then monitor their movements to return home, are commonly used as tools to assess functional connectivity of fragmented landscapes. Such experiments are purported to have important advantages of being time efficient and of standardizing “motivation” to move across individuals. Yet, we lack tests of whether movement behavior of translocated birds reflects natural behavior of unmanipulated birds. We compared the routine movement behavior of a tropical hummingbird, the Green Hermit (Phaethornis guy), to that of experimentally translocated individuals. We tested for differences in site selection patterns during movement at two spatial scales (point and path levels). We also compared movement rates between treatments. Behaviors documented during translocation experiments reflected those observed during routine movements. At the point level, both translocated and non-translocated birds showed similar levels of preference for mature tropical forest. At the path level, step selection functions showed both translocated and non-translocated hummingbirds avoiding movement across non-forested matrix and selecting streams as movement corridors. Movement rates were generally higher during translocation experiments. However, the negative influence of forest cover on movement rates was proportionately similar in translocation and routine movement treatments. We report the first evidence showing that movement behavior of birds during translocation experiments is similar to their natural movement behavior. Therefore, translocation experiments may be reliable tools to address effects of landscape structure on animal movement. We observed consistent selection of landscape elements between translocated and non-translocated birds, indicating that both routine and translocation movement studies lead to similar conclusions regarding the effect of landscape structure and forest composition on functional connectivity
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.
Melatonin membrane receptors in peripheral tissues: Distribution and functions
Slominski, Radomir M.; Reiter, Russel J.; Schlabritz-Loutsevitch, Natalia; Ostrom, Rennolds S.; Slominski, Andrzej T.
2012-01-01
Many of melatonin’s actions are mediated through interaction with the G-protein coupled membrane bound melatonin receptors type 1 and type 2 (MT1 and MT2, respectively) or, indirectly with nuclear orphan receptors from the RORα/RZR family. Melatonin also binds to the quinone reductase II enzyme, previously defined the MT3 receptor. Melatonin receptors are widely distributed in the body; herein we summarize their expression and actions in non-neural tissues. Several controversies still exist regarding, for example, whether melatonin binds the RORα/RZR family. Studies of the peripheral distribution of melatonin receptors are important since they are attractive targets for immunomodulation, regulation of endocrine, reproductive and cardiovascular functions, modulation of skin pigmentation, hair growth, cancerogenesis, and aging. Melatonin receptor agonists and antagonists have an exciting future since they could define multiple mechanisms by which melatonin modulates the complexity of such a wide variety of physiological and pathological processes. PMID:22245784
Zimmermann, R.; Romeis, D.; Bihannic, I.; Cohen Stuart, M.A.; Sommer, J.U.; Werner, C.; Duval, J.F.L.
2014-01-01
Unravelling details of charge, structure and molecular interactions of functional polymer coatings defines an important analytical challenge that requires the extension of current methodologies. In this article we demonstrate how streaming current measurements interpreted with combined self
National Oceanic and Atmospheric Administration, Department of Commerce — The standard (analog) ionosonde produces photographic records known as ionograms, which show the variations of the virtual height of reflection as a function of the...
Hazenberg, Pieter; Leijnse, Hidde; Uijlenhoet, Remko
2015-04-01
Between 25 and 27 August 2010 a long-duration mesoscale convective system was observed above the Netherlands, locally giving rise to rainfall accumulations exceeding 150 mm. Correctly measuring the amount of precipitation during such an extreme event is important, both from a hydrological and meteorological perspective. Unfortunately, the operational weather radar measurements were affected by multiple sources of error and only 30% of the precipitation observed by rain gauges was estimated. Such an underestimation of heavy rainfall, albeit generally less strong than in this extreme case, is typical for operational weather radar in The Netherlands. In general weather radar measurement errors can be subdivided into two groups: (1) errors affecting the volumetric reflectivity measurements (e.g. ground clutter, radar calibration, vertical profile of reflectivity) and (2) errors resulting from variations in the raindrop size distribution that in turn result in incorrect rainfall intensity and attenuation estimates from observed reflectivity measurements. A stepwise procedure to correct for the first group of errors leads to large improvements in the quality of the estimated precipitation, increasing the radar rainfall accumulations to about 65% of those observed by gauges. To correct for the second group of errors, a coherent method is presented linking the parameters of the radar reflectivity-rain rate (Z-R) and radar reflectivity-specific attenuation (Z-k) relationships to the normalized drop size distribution (DSD). Two different procedures were applied. First, normalized DSD parameters for the whole event and for each precipitation type separately (convective, stratiform and undefined) were obtained using local disdrometer observations. Second, 10,000 randomly generated plausible normalized drop size distributions were used for rainfall estimation, to evaluate whether this Monte Carlo method would improve the quality of weather radar rainfall products. Using the
DISTRIBUTION OF PARASTATISTICS FUNCTIONS: AN OVERVIEW OF THERMODYNAMICS PROPERTIES
Directory of Open Access Journals (Sweden)
R. Yosi Aprian Sari
2016-05-01
Full Text Available This study aims to determine the thermodynamic properties of the parastatistics system of order two. The thermodynamic properties to be searched include the Grand Canonical Partition Function (GCPF Z, and the average number of particles N. These parastatistics systems is in a more general form compared to quantum statistical distribution that has been known previously, i.e.: the Fermi-Dirac (FD and Bose-Einstein (BE. Starting from the recursion relation of grand canonical partition function for parastatistics system of order two that has been known, recuresion linkages for some simple thermodynamic functions for parastatistics system of order two are derived. The recursion linkages are then used to calculate the thermodynamic functions of the model system of identical particles with limited energy levels which is similar to the harmonic oscillator. From these results we concluded that from the Grand Canonical Partition Function (GCPF, Z, the thermodynamics properties of parastatistics system of order two (paraboson and parafermion can be derived and have similar shape with parastatistics system of order one (Boson and Fermion. The similarity of the graph shows similar thermodynamic properties. Keywords: parastatistics, thermodynamic properties
International Nuclear Information System (INIS)
Liu, S.M.; Rodgers, W.E.; Knuth, E.L.
1977-01-01
Interactions of satellite-speed helium atoms (accelerated in an expansion from an arc-heated supersonic-molecular-beam source) with practical satellite surfaces have been investigated experimentally. The density and energy distributions of the scattered atoms were measured using a detection system developed for this study. This detection system includes (a) a target positioning mechanism, (b) a detector rotating mechanism, and (c) a mass spectrometer and/or a retarding-field energy analyzer. (Auth.)
Unbiased Polarised Parton Distribution Functions and their Uncertainties
Nocera, Emanuele R.; Ridolfi, Giovanni; Rojo, Juan
2012-01-01
We present preliminary results on the determination of spin-dependent, or polarised, Parton Distribution Functions (PDFs) from all relevant inclusive polarised DIS data. The analysis is performed within the NNPDF approach, which provides a faithful and statistically sound representation of PDFs and their uncertainties. We describe how the NNPDF methodology has been extended to the polarised case, and compare our results with other recent polarised parton sets. We show that polarised PDF uncertainties can be sizeably underestimated in standard determinations, most notably for the gluon.
Transverse momentum dependent (TMD) parton distribution functions. Status and prospects
International Nuclear Information System (INIS)
Angeles-Martinez, R.; Bacchetta, A.; Pavia Univ.; Balitsky, I.I.
2015-07-01
We provide a concise overview on transverse momentum dependent (TMD) parton distribution functions, their application to topical issues in high-energy physics phenomenology, and their theoretical connections with QCD resummation, evolution and factorization theorems. We illustrate the use of TMDs via examples of multi-scale problems in hadronic collisions. These include transverse momentum q T spectra of Higgs and vector bosons for low q T , and azimuthal correlations in the production of multiple jets associated with heavy bosons at large jet masses. We discuss computational tools for TMDs, and present an application of a new tool, TMDlib, to parton density fits and parameterizations.
Are there approximate relations among transverse momentum dependent distribution functions?
Energy Technology Data Exchange (ETDEWEB)
Harutyun AVAKIAN; Anatoli Efremov; Klaus Goeke; Andreas Metz; Peter Schweitzer; Tobias Teckentrup
2007-10-11
Certain {\\sl exact} relations among transverse momentum dependent parton distribution functions due to QCD equations of motion turn into {\\sl approximate} ones upon the neglect of pure twist-3 terms. On the basis of available data from HERMES we test the practical usefulness of one such ``Wandzura-Wilczek-type approximation'', namely of that connecting $h_{1L}^{\\perp(1)a}(x)$ to $h_L^a(x)$, and discuss how it can be further tested by future CLAS and COMPASS data.
Bandyopadhyay, Malay; Gupta, Shamik; Segal, Dvira
2011-03-01
We investigate DNA breathing dynamics by suggesting and examining several Brownian functionals associated with bubble lifetime and reactivity. Bubble dynamics is described as an overdamped random walk in the number of broken base pairs. The walk takes place on the Poland-Scheraga free-energy landscape. We suggest several probability distribution functions that characterize the breathing process, and adopt the recently studied backward Fokker-Planck method and the path decomposition method as elegant and flexible tools for deriving these distributions. In particular, for a bubble of an initial size x₀, we derive analytical expressions for (i) the distribution P(t{f}|x₀) of the first-passage time t{f}, characterizing the bubble lifetime, (ii) the distribution P(A|x₀) of the area A until the first-passage time, providing information about the effective reactivity of the bubble to processes within the DNA, (iii) the distribution P(M) of the maximum bubble size M attained before the first-passage time, and (iv) the joint probability distribution P(M,t{m}) of the maximum bubble size M and the time t{m} of its occurrence before the first-passage time. These distributions are analyzed in the limit of small and large bubble sizes. We supplement our analytical predictions with direct numericalsimulations of the related Langevin equation, and obtain a very good agreement in the appropriate limits. The nontrivial scaling behavior of the various quantities analyzed here can, in principle, be explored experimentally.
Analysis of the proton longitudinal structure function from the gluon distribution function
International Nuclear Information System (INIS)
Boroun, G.R.; Rezaei, B.
2012-01-01
We make a critical, next-to-leading order, study of the relationship between the longitudinal structure function F L and the gluon distribution proposed in Cooper-Sarkar et al. (Z. Phys. C 39:281, 1988; Acta Phys. Pol. B 34:2911 2003), which is frequently used to extract the gluon distribution from the proton longitudinal structure function at small x. The gluon density is obtained by expanding at particular choices of the point of expansion and compared with the hard Pomeron behavior for the gluon density. Comparisons with H1 data are made and predictions for the proposed best approach are also provided. (orig.)
Directory of Open Access Journals (Sweden)
H. Kaviani
2007-09-01
Full Text Available Band structure of porous alumina photonic crystal in the Γ X direction was calculated using order-N method . In a comparison of calculated results with experimental data of reflective and absorptive index, the variation of refractive index of alumina in the external region of oxide layer, around the pores were studied. A Gaussian distribution function was adopted for phosphate anions in the external oxide layer and the variation of refractive index and diffusion depth were determined. The structure of the first four bands was calculated using the obtained distribution of refractive index in the external oxide layer for both TE and TM mode. This results show a narrow full band gap in the TM mode.
Memory intensive functional architecture for distributed computer control systems
International Nuclear Information System (INIS)
Dimmler, D.G.
1983-10-01
A memory-intensive functional architectue for distributed data-acquisition, monitoring, and control systems with large numbers of nodes has been conceptually developed and applied in several large-scale and some smaller systems. This discussion concentrates on: (1) the basic architecture; (2) recent expansions of the architecture which now become feasible in view of the rapidly developing component technologies in microprocessors and functional large-scale integration circuits; and (3) implementation of some key hardware and software structures and one system implementation which is a system for performing control and data acquisition of a neutron spectrometer at the Brookhaven High Flux Beam Reactor. The spectrometer is equipped with a large-area position-sensitive neutron detector
Exciton distribution function and secondary radiation in polar semiconductors
International Nuclear Information System (INIS)
Trallero Giner, C.; Sotolongo Costa, O.
1985-07-01
An explicit non-equilibrium distribution function for excitons in the ground state n=1 in the case when the fundamental interaction is with acoustical phonons is calculated for polar semiconductors. Using it, a general expression for the secondary radiation cross-section (valid for Raman, hot and thermalized luminescence processes), is obtained. The results are applied to explain the temperature dependence of the 1LO and 2LO luminescence lines half-width in CdS single crystals. The relative contributions of 3LO Raman and luminescence intensities and the variation of the secondary emission spectrum as function of exciton life-time are studied. Comparison with experimental results yields quantitative agreement. (author)
Fukushima, Makoto; Saunders, Richard C; Leopold, David A; Mishkin, Mortimer; Averbeck, Bruno B
2012-06-07
In the absence of sensory stimuli, spontaneous activity in the brain has been shown to exhibit organization at multiple spatiotemporal scales. In the macaque auditory cortex, responses to acoustic stimuli are tonotopically organized within multiple, adjacent frequency maps aligned in a caudorostral direction on the supratemporal plane (STP) of the lateral sulcus. Here, we used chronic microelectrocorticography to investigate the correspondence between sensory maps and spontaneous neural fluctuations in the auditory cortex. We first mapped tonotopic organization across 96 electrodes spanning approximately two centimeters along the primary and higher auditory cortex. In separate sessions, we then observed that spontaneous activity at the same sites exhibited spatial covariation that reflected the tonotopic map of the STP. This observation demonstrates a close relationship between functional organization and spontaneous neural activity in the sensory cortex of the awake monkey. Copyright © 2012 Elsevier Inc. All rights reserved.
A method for the characterization of the reflectance of anisotropic functional surfaces
DEFF Research Database (Denmark)
Regi, Francesco; Nielsen, J B; Li, Dongya
2018-01-01
The functional properties of micro-structured surfaces have gained increasing interest thanks to many applications such as wetting, adhesion, thermal and/or electrical conductivity. In this study, directional optical properties, i.e. contrast between two regions of a surface, were achieved...... reflectance of the surface for a range of design-specific view-illumination configurations was determined using a method that involves a Hirox RH-2000 digital microscope, used as a gonioreflectometer. This method allows the empirical determination of the optimum surface microstructure for maximizing contrast...... between two horizontally orthogonal views. The results show that even if the uncertainty related to the instrumentation is up to 20% in some cases, this procedure is suitable for the characterization of the surface of both metal and plastic counterpart....
Protein functional features are reflected in the patterns of mRNA translation speed.
López, Daniel; Pazos, Florencio
2015-07-09
The degeneracy of the genetic code makes it possible for the same amino acid string to be coded by different messenger RNA (mRNA) sequences. These "synonymous mRNAs" may differ largely in a number of aspects related to their overall translational efficiency, such as secondary structure content and availability of the encoded transfer RNAs (tRNAs). Consequently, they may render different yields of the translated polypeptides. These mRNA features related to translation efficiency are also playing a role locally, resulting in a non-uniform translation speed along the mRNA, which has been previously related to some protein structural features and also used to explain some dramatic effects of "silent" single-nucleotide-polymorphisms (SNPs). In this work we perform the first large scale analysis of the relationship between three experimental proxies of mRNA local translation efficiency and the local features of the corresponding encoded proteins. We found that a number of protein functional and structural features are reflected in the patterns of ribosome occupancy, secondary structure and tRNA availability along the mRNA. One or more of these proxies of translation speed have distinctive patterns around the mRNA regions coding for certain protein local features. In some cases the three patterns follow a similar trend. We also show specific examples where these patterns of translation speed point to the protein's important structural and functional features. This support the idea that the genome not only codes the protein functional features as sequences of amino acids, but also as subtle patterns of mRNA properties which, probably through local effects on the translation speed, have some consequence on the final polypeptide. These results open the possibility of predicting a protein's functional regions based on a single genomic sequence, and have implications for heterologous protein expression and fine-tuning protein function.
Determining integral density distribution in the mach reflection of shock waves
Shevchenko, A. M.; Golubev, M. P.; Pavlov, A. A.; Pavlov, Al. A.; Khotyanovsky, D. V.; Shmakov, A. S.
2017-05-01
We present a method for and results of determination of the field of integral density in the structure of flow corresponding to the Mach interaction of shock waves at Mach number M = 3. The optical diagnostics of flow was performed using an interference technique based on self-adjusting Zernike filters (SA-AVT method). Numerical simulations were carried out using the CFS3D program package for solving the Euler and Navier-Stokes equations. Quantitative data on the distribution of integral density on the path of probing radiation in one direction of 3D flow transillumination in the region of Mach interaction of shock waves were obtained for the first time.
Knabe, Johannes F; Nehaniv, Chrystopher L; Schilstra, Maria J
2008-01-01
Methods that analyse the topological structure of networks have recently become quite popular. Whether motifs (subgraph patterns that occur more often than in randomized networks) have specific functions as elementary computational circuits has been cause for debate. As the question is difficult to resolve with currently available biological data, we approach the issue using networks that abstractly model natural genetic regulatory networks (GRNs) which are evolved to show dynamical behaviors. Specifically one group of networks was evolved to be capable of exhibiting two different behaviors ("differentiation") in contrast to a group with a single target behavior. In both groups we find motif distribution differences within the groups to be larger than differences between them, indicating that evolutionary niches (target functions) do not necessarily mold network structure uniquely. These results show that variability operators can have a stronger influence on network topologies than selection pressures, especially when many topologies can create similar dynamics. Moreover, analysis of motif functional relevance by lesioning did not suggest that motifs were of greater importance to the functioning of the network than arbitrary subgraph patterns. Only when drastically restricting network size, so that one motif corresponds to a whole functionally evolved network, was preference for particular connection patterns found. This suggests that in non-restricted, bigger networks, entanglement with the rest of the network hinders topological subgraph analysis.
Ion and electron Kappa distribution functions in the plasma sheet.
Moya, P. S.; Stepanova, M. V.; Espinoza, C.; Antonova, E. E.; Valdivia, J. A.
2017-12-01
We present a study of ion and electron flux spectra in the Earth's plasma sheet using kappa distribution functions. Satellite data from the THEMIS mission were collected for thousands of crossings through the plasma sheet, between 7 and 35 Re and during the years 2008-2009. The events were separated according to the geomagnetic activity at the time. Our results show the distribution of the kappa index and characteristic energies across the plasma sheet and its evolution with distance to Earth for quiet times and for the substorm expansion and recovery phases. For the ions, it is observed that the kappa values tend to decrease outwards and that this effect is more significant in the dusk sector, where the smallest values are found for distances beyond 15 Re. The main effect of the substorms appears as an enhancement of this behavior. The electrons show a much more homogeneous distribution in quiet times, with a mild tendency for larger kappa values at larger distances. During substorms, the kappa values tend to equalize and appear very homogenous during expansion. However, they exhibit a significant increase in the dusk sector during the recovery substorm phase. Finally, we observe that the characteristic energy of the particles during substorms increases and concentrate at distances less than 15 Re.
A Noninformative Prior on a Space of Distribution Functions
Directory of Open Access Journals (Sweden)
Alexander Terenin
2017-07-01
Full Text Available In a given problem, the Bayesian statistical paradigm requires the specification of a prior distribution that quantifies relevant information about the unknowns of main interest external to the data. In cases where little such information is available, the problem under study may possess an invariance under a transformation group that encodes a lack of information, leading to a unique prior—this idea was explored at length by E.T. Jaynes. Previous successful examples have included location-scale invariance under linear transformation, multiplicative invariance of the rate at which events in a counting process are observed, and the derivation of the Haldane prior for a Bernoulli success probability. In this paper we show that this method can be extended, by generalizing Jaynes, in two ways: (1 to yield families of approximately invariant priors; and (2 to the infinite-dimensional setting, yielding families of priors on spaces of distribution functions. Our results can be used to describe conditions under which a particular Dirichlet Process posterior arises from an optimal Bayesian analysis, in the sense that invariances in the prior and likelihood lead to one and only one posterior distribution.
Elzubeir, Margaret
2011-01-01
This report describes and explores the impact of a series of faculty-led faculty development programs underpinned by principles of distributed educational leadership. We aimed to prepare faculty for their roles as facilitators and assessors in a newly implemented problem-based (PBL) graduate entry medical program. We asked participants attending a series of faculty development programs to evaluate workshops attended using an in-house designed survey. Overall descriptive statistics for all workshops and qualitative feedback for PBL workshops alone were examined. It was concluded that clinical faculty who are not specialized in medical education can offer high-quality, well-accepted training for their peers. Faculty development, underpinned by a distributed leadership approach which supports learning organization tenets, imaginative, flexible and democratic approaches to developing and nurturing expertise at all levels of the organization, is likely to lead to improvements in medical education. Despite the limitations of the survey approach to evaluation of faculty development programs, the information provided is useful both as a basis for decision making and program improvement.
A Didatic Reflection on Distribution of Textual Genres to the Primary School
Directory of Open Access Journals (Sweden)
João Bosco Figueiredo-Gomes
2015-12-01
Full Text Available Considering the interest on the studies about textual genre and its teaching in the three last decades, the present article presents a report of an analysis of collection of didactic books of Portuguese language of the Primary School II, which aimed at verifying if the didactic book enables a comprehension about different textual genres as for the student, in relation to the context and social use, as well as for the teacher, in relation to parameters in order to do an analysis and choice of didactic collection books. The theoretical methodological framework based mainly in the contributions of Interactionism Socio-discursive: Bronckart (1999, 2003 and Schneuwly and Dolz (2004; in the studies by Marcuschi (2002, 2008 and in the orientations about the teaching of mother language contained in the National Curriculum Guidelines – PCN (BRASIL, 1998. The results provided a reflection that offers param-eters to the analysis, choice and organization of didactic collections, as well as suggestions of pedagogic implementation towards the teaching of Portuguese language.
International Nuclear Information System (INIS)
Dobbertin, R.
1976-01-01
Functional relations are derived which link the reduced distribution functions of a classical N-particle system through the entropy production due to microscopic deviations from hamiltonian dynamics. These relations have been used in an earlier paper for the closure of the BBGKY-hierarchy and may be useful for the establishment of collective particle models in particular and the understanding of irreversibility in general. (Auth.)
Multivesicular Bodies in Neurons: Distribution, Protein Content, and Trafficking Functions
VON BARTHELD, CHRISTOPHER S.; ALTICK, AMY L.
2011-01-01
Summary Multivesicular bodies (MVBs) are intracellular endosomal organelles characterized by multiple internal vesicles that are enclosed within a single outer membrane. MVBs were initially regarded as purely prelysosomal structures along the degradative endosomal pathway of internalized proteins. MVBs are now known to be involved in numerous endocytic and trafficking functions, including protein sorting, recycling, transport, storage, and release. This review of neuronal MVBs summarizes their research history, morphology, distribution, accumulation of cargo and constitutive proteins, transport, and theories of functions of MVBs in neurons and glia. Due to their complex morphologies, neurons have expanded trafficking and signaling needs, beyond those of “geometrically simpler” cells, but it is not known whether neuronal MVBs perform additional transport and signaling functions. This review examines the concept of compartment-specific MVB functions in endosomal protein trafficking and signaling within synapses, axons, dendrites and cell bodies. We critically evaluate reports of the accumulation of neuronal MVBs based on evidence of stress-induced MVB formation. Furthermore, we discuss potential functions of neuronal and glial MVBs in development, in dystrophic neuritic syndromes, injury, disease, and aging. MVBs may play a role in Alzheimer’s, Huntington’s, and Niemann-Pick diseases, some types of frontotemporal dementia, prion and virus trafficking, as well as in adaptive responses of neurons to trauma and toxin or drug exposure. Functions of MVBs in neurons have been much neglected, and major gaps in knowledge currently exist. Developing truly MVB-specific markers would help to elucidate the roles of neuronal MVBs in intra- and intercellular signaling of normal and diseased neurons. PMID:21216273
International Nuclear Information System (INIS)
Letfus, V.; Apostolov, E.M.
1980-01-01
By analysing the autocorrelation function of the geomagnetic Asup(p)-index, a series of subsidiary maxima were found which seem to indicate that they correspond to periods considerably different from the solar rotation period. It was found that these subsidiary maxima are located symmetrically around the maxima of the first and second recurrences of the solar rotation period (and probably also around the subsequent ones). This fact leads to a model of two or more geoactive longitudes on the Sun. (author)
Wang, Dong-Bo; Zhang, Jin-Chuan; Cheng, Feng-Min; Zhao, Yue; Zhuo, Ning; Zhai, Shen-Qiang; Wang, Li-Jun; Liu, Jun-Qi; Liu, Shu-Man; Liu, Feng-Qi; Wang, Zhan-Guo
2018-02-01
In this work, quantum cascade lasers (QCLs) based on strain compensation combined with two-phonon resonance design are presented. Distributed feedback (DFB) laser emitting at 4.76 μm was fabricated through a standard buried first-order grating and buried heterostructure (BH) processing. Stable single-mode emission is achieved under all injection currents and temperature conditions without any mode hop by the optimized antireflection (AR) coating on the front facet. The AR coating consists of a double layer dielectric of Al2O3 and Ge. For a 2-mm laser cavity, the maximum output power of the AR-coated DFB-QCL was more than 170 mW at 20 °C with a high wall-plug efficiency (WPE) of 4.7% in a continuous-wave (CW) mode.
Fernando, Denise R; Marshall, Alan T; Lynch, Jonathan P
2016-01-01
Sugar maple and red maple are closely-related co-occurring tree species significant to the North American forest biome. Plant abiotic stress effects including nutritional imbalance and manganese (Mn) toxicity are well documented within this system, and are implicated in enhanced susceptibility to biotic stresses such as insect attack. Both tree species are known to overaccumulate foliar manganese (Mn) when growing on unbuffered acidified soils, however, sugar maple is Mn-sensitive, while red maple is not. Currently there is no knowledge about the cellular sequestration of Mn and other nutrients in these two species. Here, electron-probe x-ray microanalysis was employed to examine cellular and sub-cellular deposition of excessively accumulated foliar Mn and other mineral nutrients in vivo. For both species, excess foliar Mn was deposited in symplastic cellular compartments. There were striking between-species differences in Mn, magnesium (Mg), sulphur (S) and calcium (Ca) distribution patterns. Unusually, Mn was highly co-localised with Mg in mesophyll cells of red maple only. The known sensitivity of sugar maple to excess Mn is likely linked to Mg deficiency in the leaf mesophyll. There was strong evidence that Mn toxicity in sugar maple is primarily a symplastic process. For each species, leaf-surface damage due to biotic stress including insect herbivory was compared between sites with acidified and non-acidified soils. Although it was greatest overall in red maple, there was no difference in biotic stress damage to red maple leaves between acidified and non-acidified soils. Sugar maple trees on buffered non-acidified soil were less damaged by biotic stress compared to those on unbuffered acidified soil, where they are also affected by Mn toxicity abiotic stress. This study concluded that foliar nutrient distribution in symplastic compartments is a determinant of Mn sensitivity, and that Mn stress hinders plant resistance to biotic stress.
Hoppe, Franziska; Zhusui Kyzy, Taalaigul; Usupbaev, Adilet; Schickoff, Udo
2017-04-01
At least 30% of Kyrgyz pasture areas are considered to be subject to vegetation and soil degradation. Since animal husbandry is the economic basis to sustain people's livelihoods, rangeland degradation presents a threat for the majority of the population. Recently, the usage of plant functional traits as a powerful tool for the characterization of vegetation dynamics in response to anthropogenic and natural disturbances has been put forward. Grazing is one of the most severe disturbances on vegetation, which concerns equally the loss of area and biomass. Because grazing is both depending on and affecting plant functional traits, important insights can be generated, based on this codependency. We hypothesized that the contrasting grazing intensity of summer and winter pastures is reflected by the chosen traits. We used traits such as plant height, flowering start, growth form as well as SLA (Specific Leaf Area) and LMA (Leaf Mass per Area). Based on former phytosociological classification of the main pasture types (summer and winter pastures), community structure and the traits of dominant plant species were analyzed. Our results showed that on winter pastures grazing decreased plant height and SLA and favored plants with an earlier flowering start as well as rosette plants and ascending plants. We conclude that the study of trait composition in relation to anthropogenic disturbances can provide important insights into the mechanism of plant response to grazing in high-altitude rangelands.
The reflection of life functional entailment and imminence in relational biology
Louie, A H
2013-01-01
A. H. Louie’s The Reflection of Life: Functional Entailment and Imminence in Relational Biology is a continuation of the exploratory journey in relational biology which began with his 2009 monograph More Than Life Itself: A Synthetic Continuation in Relational Biology. The theme of his first book was ‘What is life?’; the theme of this sequel is “How do two life forms interact?” Biology is a subject concerned with organization of relations. Relational biology is the approach that advocates ‘function dictates structure”, rather than ‘structure implies function’. It is mathematics decoded into biological realizations. The book demonstrates some of the powers of the approach of relational biology, and illustrates how pertinent problems in biology can be better addressed this way. In the first volume the theory was developed by using partially ordered sets, lattices, simulations, models, Aristotle’s four causes, graphs, categories, simple and complex systems, anticipatory systems, and metabolis...
Rolfe, Margaret I; Donoghue, Deborah Anne; Longman, Jo M; Pilcher, Jennifer; Kildea, Sue; Kruske, Sue; Kornelsen, Jude; Grzybowski, Stefan; Barclay, Lesley; Morgan, Geoffrey Gerard
2017-02-23
Australia has a universal health care system and a comprehensive safety net. Despite this, outcomes for Australians living in rural and remote areas are worse than those living in cities. This study will examine the current state of equity of access to birthing services for women living in small communities in rural and remote Australia from a population perspective and investigates whether services are distributed according to need. Health facilities in Australia were identified and a service catchment was determined around each using a one-hour road travel time from that facility. Catchment exclusions: metropolitan areas, populations above 25,000 or below 1,000, and a non-birthing facility within the catchment of one with birthing. Catchments were attributed with population-based characteristics representing need: population size, births, demographic factors, socio-economic status, and a proxy for isolation - the time to the nearest facility providing a caesarean section (C-section). Facilities were dichotomised by service level - those providing birthing services (birthing) or not (no birthing). Birthing services were then divided by C-section provision (C-section vs no C-section birthing). Analysis used two-stage univariable and multivariable logistic regression. There were 259 health facilities identified after exclusions. Comparing services with birthing to no birthing, a population is more likely to have a birthing service if they have more births, (adjusted Odds Ratio (aOR): 1.50 for every 10 births, 95% Confidence Interval (CI) [1.33-1.69]), and a service offering C-sections 1 to 2 h drive away (aOR: 28.7, 95% CI [5.59-148]). Comparing the birthing services categorised by C-section vs no C-section, the likelihood of a facility having a C-section was again positively associated with increasing catchment births and with travel time to another service offering C-sections. Both models demonstrated significant associations with jurisdiction but not socio
International Nuclear Information System (INIS)
Wyatt, Robert E.; Kouri, Donald J.; Hoffman, David K.
2000-01-01
The quantum trajectory method (QTM) was recently developed to solve the hydrodynamic equations of motion in the Lagrangian, moving-with-the-fluid, picture. In this approach, trajectories are integrated for N fluid elements (particles) moving under the influence of both the force from the potential surface and from the quantum potential. In this study, distributed approximating functionals (DAFs) are used on a uniform grid to compute the necessary derivatives in the equations of motion. Transformations between the physical grid where the particle coordinates are defined and the uniform grid are handled through a Jacobian, which is also computed using DAFs. A difficult problem associated with computing derivatives on finite grids is the edge problem. This is handled effectively by using DAFs within a least squares approach to extrapolate from the known function region into the neighboring regions. The QTM-DAF is then applied to wave packet transmission through a one-dimensional Eckart potential. Emphasis is placed upon computation of the transmitted density and wave function. A problem that develops when part of the wave packet reflects back into the reactant region is avoided in this study by introducing a potential ramp to sweep the reflected particles away from the barrier region. (c) 2000 American Institute of Physics
International Nuclear Information System (INIS)
Kantar, Yeliz Mert; Usta, Ilhan
2008-01-01
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
Directory of Open Access Journals (Sweden)
Byoung-Kwan Cho
2013-09-01
Full Text Available Spectroscopy has proven to be an efficient tool for measuring the properties of meat. In this article, hyperspectral imaging (HSI techniques are used to determine the moisture content in cooked chicken breast over the VIS/NIR (400–1,000 nm spectral range. Moisture measurements were performed using an oven drying method. A partial least squares regression (PLSR model was developed to extract a relationship between the HSI spectra and the moisture content. In the full wavelength range, the PLSR model possessed a maximum of 0.90 and an SEP of 0.74%. For the NIR range, the PLSR model yielded an of 0.94 and an SEP of 0.71%. The majority of the absorption peaks occurred around 760 and 970 nm, representing the water content in the samples. Finally, PLSR images were constructed to visualize the dehydration and water distribution within different sample regions. The high correlation coefficient and low prediction error from the PLSR analysis validates that HSI is an effective tool for visualizing the chemical properties of meat.
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.
Energy Technology Data Exchange (ETDEWEB)
Ingerle, D., E-mail: dingerle@ati.ac.at [Atominstitut, Vienna University of Technology, Stadionallee 2, A-1020 Vienna (Austria); Meirer, F. [Inorganic Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht (Netherlands); Pepponi, G.; Demenev, E.; Giubertoni, D. [MiNALab, CMM-irst, Fondazione Bruno Kessler, Via Sommarive 18, I-38050 Povo (Italy); Wobrauschek, P.; Streli, C. [Atominstitut, Vienna University of Technology, Stadionallee 2, A-1020 Vienna (Austria)
2014-09-01
The continuous downscaling of the process size for semiconductor devices pushes the junction depths and consequentially the implantation depths to the top few nanometers of the Si substrate. This motivates the need for sensitive methods capable of analyzing dopant distribution, total dose and possible impurities. X-ray techniques utilizing the external reflection of X-rays are very surface sensitive, hence providing a non-destructive tool for process analysis and control. X-ray reflectometry (XRR) is an established technique for the characterization of single- and multi-layered thin film structures with layer thicknesses in the nanometer range. XRR spectra are acquired by varying the incident angle in the grazing incidence regime while measuring the specular reflected X-ray beam. The shape of the resulting angle-dependent curve is correlated to changes of the electron density in the sample, but does not provide direct information on the presence or distribution of chemical elements in the sample. Grazing Incidence XRF (GIXRF) measures the X-ray fluorescence induced by an X-ray beam incident under grazing angles. The resulting angle dependent intensity curves are correlated to the depth distribution and mass density of the elements in the sample. GIXRF provides information on contaminations, total implanted dose and to some extent on the depth of the dopant distribution, but is ambiguous with regard to the exact distribution function. Both techniques use similar measurement procedures and data evaluation strategies, i.e. optimization of a sample model by fitting measured and calculated angle curves. Moreover, the applied sample models can be derived from the same physical properties, like atomic scattering/form factors and elemental concentrations; a simultaneous analysis is therefore a straightforward approach. This combined analysis in turn reduces the uncertainties of the individual techniques, allowing a determination of dose and depth profile of the implanted
Domain wall partition function of the eight-vertex model with a non-diagonal reflecting end
International Nuclear Information System (INIS)
Yang Wenli; Chen Xi; Feng Jun; Hao Kun; Shi Kangjie; Sun Chengyi; Yang Zhanying; Zhang Yaozhong
2011-01-01
With the help of the Drinfeld twist or factorizing F-matrix for the eight-vertex SOS model, we derive the recursion relations of the partition function for the eight-vertex model with a generic non-diagonal reflecting end and domain wall boundary condition. Solving the recursion relations, we obtain the explicit determinant expression of the partition function. Our result shows that, contrary to the eight-vertex model without a reflecting end, the partition function can be expressed as a single determinant.
Maxwell, Hilary; Tasca, Giorgio A; Grenon, Renee; Faye, Megan; Ritchie, Kerri; Bissada, Hany; Balfour, Louise
2017-08-01
Coherence of mind and reflective functioning may impact negative affect and interpersonal functioning over and above the effects of symptoms of depression and interpersonal problems that contribute to symptoms of binge-eating disorder (BED) and overweight/obesity. Matched samples of overweight women with BED and overweight and normal weight women without BED completed the Adult Attachment Interview, a measure of depressive symptoms, and a measure of interpersonal problems. Greater symptoms of depression distinguished women with BED from the matched comparison samples. Greater interpersonal problems differentiated women with BED from overweight women without BED. Coherence of Mind scores did not differentiate the samples. However, lower Reflective Functioning scores did distinguish both women with BED and overweight women without BED from normal weight women. Lower reflective functioning may lead to binge eating independent of depressive symptoms and interpersonal problems.
Parton distribution functions and benchmark cross sections at NNLO
Energy Technology Data Exchange (ETDEWEB)
Alekhin, S. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Institute for High Energy Physics (IHEP), Protvino (Russian Federation); Bluemlein, J.; Moch, S. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)
2012-02-15
We present a determination of parton distribution functions (ABM11) and the strong coupling constant {alpha}{sub s} at next-to-leading order and next-to-next-to-leading order (NNLO) in QCD based on world data for deep-inelastic scattering and fixed-target data for the Drell-Yan process. The analysis is performed in the fixed-flavor number scheme for n{sub f}=3,4,5 and uses the MS-scheme for {alpha}{sub s} and the heavy-quark masses. At NNLO we obtain the value {alpha}{sub s}(MZ)=0.1134{+-}0.0011. The fit results are used to compute benchmark cross sections at hadron colliders to NNLO accuracy and to compare to data from the LHC. (orig.)
Electron energy distribution function control in gas discharge plasmas
International Nuclear Information System (INIS)
Godyak, V. A.
2013-01-01
The formation of the electron energy distribution function (EEDF) and electron temperature in low temperature gas discharge plasmas is analyzed in frames of local and non-local electron kinetics. It is shown, that contrary to the local case, typical for plasma in uniform electric field, there is the possibility for EEDF modification, at the condition of non-local electron kinetics in strongly non-uniform electric fields. Such conditions “naturally” occur in some self-organized steady state dc and rf discharge plasmas, and they suggest the variety of artificial methods for EEDF modification. EEDF modification and electron temperature control in non-equilibrium conditions occurring naturally and those stimulated by different kinds of plasma disturbances are illustrated with numerous experiments. The necessary conditions for EEDF modification in gas discharge plasmas are formulated
Jeans' criterion and nonextensive velocity distribution function in kinetic theory
International Nuclear Information System (INIS)
Du Jiulin
2004-01-01
The effect of nonextensivity of self-gravitating systems on the Jeans' criterion for gravitational instability is studied in the framework of Tsallis statistics. The nonextensivity is introduced in the Jeans problem by a generalized q-nonextensive velocity distribution function through the equation of state of ideal gas in nonextensive kinetic theory. A new Jeans' criterion is deduced with a factor √(2/(5-3q)) that, however, differs from that one in [Astron. Astrophys. 396 (2002) 309] and new results of gravitational instability are analyzed for the nonextensive parameter q. An understanding of physical meaning of q and a possible seismic observation to find astronomical evidence for a value of q different from unity are also discussed
Anomalous Skin Effect for Anisotropic Electron Velocity Distribution Function
International Nuclear Information System (INIS)
Igor Kaganovich; Edward Startsev; Gennady Shvets
2004-01-01
The anomalous skin effect in a plasma with a highly anisotropic electron velocity distribution function (EVDF) is very different from skin effect in a plasma with the isotropic EVDF. An analytical solution was derived for the electric field penetrated into plasma with the EVDF described as a Maxwellian with two temperatures Tx >> Tz, where x is the direction along the plasma boundary and z is the direction perpendicular to the plasma boundary. The skin layer was found to consist of two distinctive regions of width of order nTx/w and nTz/w, where nTx,z/w = (Tx,z/m)1/2 is the thermal electron velocity and w is the incident wave frequency
Distribution and functional traits of charophytes and vascular plants
DEFF Research Database (Denmark)
Båstrup-Spohr, Lars
rare species are specialists in particular environments, while the abundant species have traits such as broad salinity tolerance, tall shoots, vegetative reproduction and variable life form. Vascular plants, in contrast to charophytes, occupy the entire gradient from submerged to drained conditions......A large variety of plant species of very different evolutionary origin are found within and along the margins of aquatic ecosystems. These species have very different adaptations depending on the particular environmental condition under which they grow. This thesis examines the role...... of these adaptations or functional traits for the distribution on large scales and along specific environmental gradients. Characean algae (charophytes) are an ancient group of aquatic plants found in most aquatic ecosystems. I confirmed that they have declined markedly during the 20th century, most likely...
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).
Theoretical characterization of electron energy distribution function in RF plasmas
International Nuclear Information System (INIS)
Capitelli, M.; Capriati, G.; Dilonardo, M.; Gorse, C.; Longo, S.
1993-01-01
Different methods for the modeling of low-temperature plasmas of both technological and fundamental interest are discussed. The main concept of all these models is the electron energy distribution function (eedf) which is necessary to calculate the rate coefficients for any chemical reaction involving electrons. Results of eedf calculations in homogeneous SF 6 and SiH 4 plasmas are discussed based on solution of the time-dependent Boltzmann equation. The space-dependent eedf in an RF discharge in He is calculated taking into account the sheath oscillations by a Monte Carlo model assuming the plasma heating mechanism and the electric field determined by using a fluid model. The need to take into account the ambipolar diffusion of electrons in RF discharge modeling is stressed. A self-consistent model based on coupling the equations of the fluid model and the chemical kinetics ones is presented. (orig.)
Global study of nuclear modifications on parton distribution functions
Directory of Open Access Journals (Sweden)
Rong Wang
2017-07-01
Full Text Available 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 parameters from the global analysis, the nuclear modifications of parton distribution functions of unmeasured nuclei can be predicted in our model. Nuclear modification of deuteron is also predicted and shown with recent measurement at JLab.
Basic features of the pion valence-quark distribution function
Energy Technology Data Exchange (ETDEWEB)
Chang, Lei [CSSM, School of Chemistry and Physics, University of Adelaide, Adelaide, SA 5005 (Australia); Mezrag, Cédric; Moutarde, Hervé [Centre de Saclay, IRFU/Service de Physique Nucléaire, F-91191 Gif-sur-Yvette (France); Roberts, Craig D. [Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Rodríguez-Quintero, Jose [Departamento de Física Aplicada, Facultad de Ciencias Experimentales, Universidad de Huelva, Huelva E-21071 (Spain); Tandy, Peter C. [Center for Nuclear Research, Department of Physics, Kent State University, Kent, OH 44242 (United States)
2014-10-07
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, q{sup π}(x); namely, at a characteristic hadronic scale, q{sup π}(x)∼(1−x){sup 2} for x≳0.85; and the valence-quarks carry approximately two-thirds of the pion's light-front momentum.
Energy Technology Data Exchange (ETDEWEB)
Klockenkämper, Reinhold, E-mail: reinhold.klockenkaemper@isas.de; Bohlen, Alex von
2014-09-01
A survey was carried out with users and manufacturers of Total Reflection X-ray Fluorescence instrumentation in order to demonstrate the worldwide distribution of TXRF equipment and the different fields of applications. In general, TXRF users come from universities and scientific institutes, from working places at synchrotron beam-lines, or laboratories in semiconductor fabs. TXRF instrumentation is distributed in more than 50 countries on six continents and is applied at about 200 institutes and laboratories. The number of running desktop instruments amounts to nearly 300 units. About 60 beamlines run working places dedicated to TXRF. About 300 floor-mounted instruments are estimated to be used in about 150 fabs of the semiconductor industry. In total, 13 different fields of applications could be registered statistically from three different aspects. - Highlights: • According to the survey world maps show the distribution of TXRF equipment. • Nearly 700 individual units are running actually in 57 countries of 6 continents. • Users work at 200 universities, 60 synchrotron-beamlines, and 150 semiconductor fabs. • 13 fields of applications (e.g. environmental, chemical) are evaluated statistically. • Manufacturers, conference members and authors lead to 3 different pie-charts.
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
Ordway, Monica Roosa; Webb, Denise; Sadler, Lois S; Slade, Arietta
2015-01-01
The current state of science suggests that safe, responsive, and nurturing parent-child relationships early in children's lives promotes healthy brain and child development and protection against lifelong disease by reducing toxic stress and promoting foundational social-emotional health. Pediatric health care providers (HCPs) have a unique opportunity to foster these relationships. However, such a role requires a shift in pediatric health care from a focus only on children to one that includes families and communities, as well as the inclusion of children's social and emotional health with their physical health. To foster healthy parent-child relationships, HCPs must develop the expertise to integrate approaches that support the family's socioemotional health into pediatric primary care. This article suggests ways in which pediatric HCPs can integrate a focus on parental reflective functioning into their clinical work, helping parents to understand some of the thoughts and feelings that underlie their children's behavior. Copyright © 2015 National Association of Pediatric Nurse Practitioners. Published by Elsevier Inc. All rights reserved.
Tweeting dignity: A practical theological reflection on Twitter’s normative function
Directory of Open Access Journals (Sweden)
Jan Albert Van den Berg
2017-08-01
Full Text Available Social media makes an important contribution to a rapidly changing world in which various domains of meaning are described anew. The evolving nature and dynamic character of social media therefore provides for a rich praxis terrain with which to interact from a practical theological orientation. More specifically associated with the theme of this contribution, the social media sphere also provides an excellent space not only to rethink but also to reenact expressions of dignity in society. The research is facilitated from a practical theological orientation, with particular focus on a normative dimension as embodied in aspects of dignity. Through the use of an interdisciplinary approach and methodology, some contours of dignity specifically associated with South African politics as well as the so-called Charlie Hebdo attacks in 2015 in Paris expressed on the social media platform, Twitter, are described and discussed. From this empirical analysis, description and discussion, a practical theological reflection is offered in which aspects of dignity associated with a normativity function are described. Some practical theological perspectives contributing to future relevant tweeting on dignity are also formulated and provided in conclusion.
Borelli, Jessica L; Palmer, Alexandra; Vanwoerden, Salome; Sharp, Carla
2017-12-13
Although convergence in parent-youth reports of adolescent psychopathology is critical for treatment planning, research documents a pervasive lack of agreement in ratings of adolescents' symptoms. Attachment insecurity (particularly disorganized attachment) and impoverished reflective functioning (RF) are 2 theoretically implicated predictors of low convergence that have not been examined in the literature. In a cross-sectional investigation of adolescents receiving inpatient psychiatric treatment, we examined whether disorganized attachment and low (adolescent and parent) RF were associated with patterns of convergence in adolescent internalizing and externalizing symptoms. Compared with organized adolescents, disorganized adolescents had lower parent-youth convergence in reports of their internalizing symptoms and higher convergence in reports of their externalizing symptoms; low adolescent self-focused RF was associated with low convergence in parent-adolescent reports of internalizing symptoms, whereas low adolescent global RF was associated with high convergence in parent-adolescent reports of externalizing symptoms. Among adolescents receiving inpatient psychiatric treatment, disorganized attachment and lower RF were associated with weaker internalizing symptom convergence and greater externalizing symptom convergence, which if replicated, could inform assessment strategies and treatment planning in this setting.
Energy Technology Data Exchange (ETDEWEB)
Cronin-Golomb; Yariv
1986-07-01
A GaA1As semiconductor laser with feedback from a barium titanate photorefractive ring passive phase-conjugate mirror can be made to perform repeating or nonrepeating frequency scans over a 10-nm range toward either the blue or the red. The direction of scanning and whether the scans repeat may be controlled by adjusting the overlap of the interaction beams in the crystal. This overlap region may be adjusted so that the diode frequency spectrum, originally occupying about 10 longitudinal modes, scans and narrows as the conjugate signal builds up, coming to rest often in one, but sometimes two or three, longitudinal modes as a result of self-generated distributed-feedback effects. Also reported similar effects caused by feedback from the total-internal-reflection passive phase-conjugate mirror. The alignment-control mechanism of the ring mirror is, however, not available in this case.
Energy Technology Data Exchange (ETDEWEB)
Cronin-Golomb, M.; Yariv, A.
1986-07-01
A GaAlAs semiconductor laser with feedback from a barium titanate photorefractive ring passive phase-conjugate mirror can be made to perform repeating or nonrepeating frequency scans over a 10-nm range toward either the blue or the red. The direction of scanning and whether the scans repeat may be controlled by adjusting the overlap of the interaction beams in the crystal. This overlap region may be adjusted so that the diode frequency spectrum, originally occupying about 10 longitudinal modes, scans and narrows as the conjugate signal builds up, coming to rest often in one, but sometimes two or three, longitudinal modes as a result of self-generated distributed-feedback effects. We also report similar effects caused by feedback from the total-internal-reflection passive phase-conjugate mirror. The alignment-control mechanism of the ring mirror is, however, not available in this case.
Cronin-Golomb, Mark; Yariv, Amnon
1986-07-01
A GaAlAs semiconductor laser with feedback from a barium titanate photorefractive ring passive phase-conjugate mirror can be made to perform repeating or nonrepeating frequency scans over a 10-nm range toward either the blue or the red. The direction of scanning and whether the scans repeat may be controlled by adjusting the overlap of the interaction beams in the crystal. This overlap region may be adjusted so that the diode frequency spectrum, originally occupying about 10 longitudinal modes, scans and narrows as the conjugate signal builds up, coming to rest often in one, but sometimes two or three, longitudinal modes as a result of self-generated distributed-feedback effects. We also report similar effects caused by feedback from the total-internal-reflection passive phase-conjugate mirror. The alignment-control mechanism of the ring mirror is, however, not available in this case.
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.
RISM theory distribution functions for Lennard--Jones interaction site fluids
International Nuclear Information System (INIS)
Johnson, E.; Hazoume, R.P.
1978-01-01
Reference interaction site model (RISM) theory distribution functions for Lennard-Jones interaction site fluids are discussed. The comparison with computer simulation results suggests that these distribution functions are as accurate as RISM distribution functions for fused hard sphere molecular fluids
Pair distribution function analysis applied to decahedral gold nanoparticles
International Nuclear Information System (INIS)
Nakotte, H; Silkwood, C; Kiefer, B; Karpov, D; Fohtung, E; Page, K; Wang, H-W; Olds, D; Manna, S; Fullerton, E E
2017-01-01
The five-fold symmetry of face-centered cubic (fcc) derived nanoparticles is inconsistent with the translational symmetry of a Bravais lattice and generally explained by multiple twinning of a tetrahedral subunit about a (joint) symmetry axis, with or without structural modification to the fcc motif. Unlike in bulk materials, five-fold twinning in cubic nanoparticles is common and strongly affects their structural, chemical, and electronic properties. To test and verify theoretical approaches, it is therefore pertinent that the local structural features of such materials can be fully characterized. The small size of nanoparticles severely limits the application of traditional analysis techniques, such as Bragg diffraction. A complete description of the atomic arrangement in nanoparticles therefore requires a departure from the concept of translational symmetry, and prevents fully evaluating all the structural features experimentally. We describe how recent advances in instrumentation, together with the increasing power of computing, are shaping the development of alternative analysis methods of scattering data for nanostructures. We present the application of Debye scattering and pair distribution function (PDF) analysis towards modeling of the total scattering data for the example of decahedral gold nanoparticles. PDF measurements provide a statistical description of the pair correlations of atoms within a material, allowing one to evaluate the probability of finding two atoms within a given distance. We explored the sensitivity of existing synchrotron x-ray PDF instruments for distinguishing four different simple models for our gold nanoparticles: a multiply twinned fcc decahedron with either a single gap or multiple distributed gaps, a relaxed body-centered orthorhombic (bco) decahedron, and a hybrid decahedron. The data simulations of the models were then compared with experimental data from synchrotron x-ray total scattering. We present our experimentally
Nawrot, Rafal; Zuschin, Martin; Chattopadhyay, Devapriya
2015-04-01
Following the opening of the Suez Canal hundreds of Red Sea species have entered the Mediterranean Sea making it a global hot spot of marine bioinvasion. With the ongoing influx of the subtropical and tropical alien species and increasing sea surface temperatures, the Mediterranean biota is currently gaining a more tropical character and increasingly becoming a mixture of faunal stocks with different evolutionary histories. This susceptibility to invasion was suggested to reflect the presence of an empty ecological space left after decimation of incumbent warm-water fauna during Plio-Pleistocene climate fluctuations. As molluscs are among the most prolific immigrants, we test this hypothesis using data on taxonomic composition and body size of Pliocene Mediterranean bivalves derived from the literature sources and museum collections. The Pliocene inter-specific size-frequency distribution (SFD) is strikingly similar to the SFDs of the Recent Red Sea bivalve fauna, in spite of different biogeographic provenance and the absence of true reef ecosystems in the Pliocene of the Mediterranean region. In contrast, body-size patterns in both assemblages are significantly different from the present-day Mediterranean fauna characterized by smaller median and modal size. Our preliminary results suggest that the distinct shape of the modern Mediterranean SFD may reflect the selective nature of the late Piacenzian - Galesian (Late Pliocene - Early Pleistocene) extinctions pulses related to the onset of the Northern Hemisphere glaciations. These extinctions affected almost 40% of Pliocene species and were biased towards large-bodied taxa. They were not followed by re-immigration of warm-water species owing to the isolation from the tropical Atlantic biota by the cold upwelling along the NW coasts of Africa. The resulting invasion credit (sensu Jackson & Sax, 2010) is currently being paid by the Red Sea bivalves colonizing the Mediterranean Sea through the Suez Canal. Successful
Metacognition does not imply self-reflection, but it does imply function.
Hoffman, Megan L; Schwartz, Bennett L
2014-05-01
Is self-reflection necessary for metacognition to occur? Like Kornell (2014, pp. 143-149), we struggle with this question. If humans metacognition is not always self-reflective, why should we expect animals to be so? We suggest that one way to pursue metacognition in animals is to examine its ecological and evolutionary relevance. ©2014 APA, all rights reserved.
Pulmonary function and V/Q distribution in hyperthyroidism
International Nuclear Information System (INIS)
Mori, Yutaka; Mashima, Yasuoki; Shimada, Takao; Kawakami, Kenji; Tominaga, Shigeru.
1987-01-01
Pulmonary functions of the hyperthyroidisms were evaluated before and after therapy. Kr-81m continuous inhalation and Tc-99m MAA (Macro Agguregated Albumin) perfusion study, spirography (VC, RV, FRC, TLC, CV), Diffusion capacity, and flow volume (V25, V50) study were done before and after therapy of 32 hyperthyroidisms. As a result VC% increased and RV% decreased significantly after the therapy, due to improvement of weakness of respiratory muscle. No significant changes were recognized on FRC, TLC, CV, DLco, V25, V50 after the therapy. Perfusion shifted to the upper lung fields in 21 (91 %) out of 23 hyperthyroidism patients. There was no significant change of ventilatory distribution after the therapy. V/Q ratio in upper lung fields therefore decreased in hyperthyroid state. After the therapy, perfusion in upper lung fields recovered to normal pattern, corresponding to normalization of T4 value. Shift of perfusion to upper lung fields was considered to be one of pathophysiological changes of hemodynamics in the hyperthyroidisms. (author)
Distribution functions for resonantly trapped orbits in the Galactic disc
Monari, Giacomo; Famaey, Benoit; Fouvry, Jean-Baptiste; Binney, James
2017-11-01
The present-day response of a Galactic disc stellar population to a non-axisymmetric perturbation of the potential has previously been computed through perturbation theory within the phase-space coordinates of the unperturbed axisymmetric system. Such an Eulerian linearized treatment, however, leads to singularities at resonances, which prevent quantitative comparisons with data. Here, we manage to capture the behaviour of the distribution function (DF) at a resonance in a Lagrangian approach, by averaging the Hamiltonian over fast angle variables and re-expressing the DF in terms of a new set of canonical actions and angles variables valid in the resonant region. We then follow the prescription of Binney, assigning to the resonant DF the time average along the orbits of the axisymmetric DF expressed in the new set of actions and angles. This boils down to phase-mixing the DF in terms of the new angles, such that the DF for trapped orbits depends only on the new set of actions. This opens the way to quantitatively fitting the effects of the bar and spirals to Gaia data in terms of DFs in action space.
Method of trial distribution function for quantum turbulence
International Nuclear Information System (INIS)
Nemirovskii, Sergey K.
2012-01-01
Studying quantum turbulence the necessity of calculation the various characteristics of the vortex tangle (VT) appears. Some of 'crude' quantities can be expressed directly via the total length of vortex lines (per unit of volume) or the vortex line density L(t) and the structure parameters of the VT. Other more 'subtle' quantities require knowledge of the vortex line configurations {s(xi,t) }. Usually, the corresponding calculations are carried out with the use of more or less truthful speculations concerning arrangement of the VT. In this paper we review other way to solution of this problem. It is based on the trial distribution functional (TDF) in space of vortex loop configurations. The TDF is constructed on the basis of well established properties of the vortex tangle. It is designed to calculate various averages taken over stochastic vortex loop configurations. In this paper we also review several applications of the use this model to calculate some important characteristics of the vortex tangle. In particular we discussed the average superfluid mass current J induced by vortices and its dynamics. We also describe the diffusion-like processes in the nonuniform vortex tangle and propagation of turbulent fronts.
Radial Distribution Functions of Strongly Coupled Two-Temperature Plasmas
Shaffer, Nathaniel R.; Tiwari, Sanat Kumar; Baalrud, Scott D.
2017-10-01
We present tests of three theoretical models for the radial distribution functions (RDFs) in two-temperature strongly coupled plasmas. RDFs are useful in extending plasma thermodynamics and kinetic theory to strong coupling, but they are usually known only for thermal equilibrium or for approximate one-component model plasmas. Accurate two-component modeling is necessary to understand the impact of strong coupling on inter-species transport, e.g., ambipolar diffusion and electron-ion temperature relaxation. We demonstrate that the Seuferling-Vogel-Toeppfer (SVT) extension of the hypernetted chain equations not only gives accurate RDFs (as compared with classical molecular dynamics simulations), but also has a simple connection with the Yukawa OCP model. This connection gives a practical means to recover the structure of the electron background from knowledge of the ion-ion RDF alone. Using the model RDFs in Effective Potential Theory, we report the first predictions of inter-species transport coefficients of strongly coupled plasmas far from equilibrium. This work is supported by NSF Grant No. PHY-1453736, AFSOR Award No. FA9550-16-1-0221, and used XSEDE computational resources.
Obtaining parton distribution functions from self-organizing maps
International Nuclear Information System (INIS)
Honkanen, H.; Liuti, S.; Loitiere, Y.C.; Brogan, D.; Reynolds, P.
2007-01-01
We present an alternative algorithm to global fitting procedures to construct Parton Distribution Functions parametrizations. The proposed algorithm uses Self-Organizing Maps which at variance with the standard Neural Networks, are based on competitive-learning. Self-Organizing Maps generate a non-uniform projection from a high dimensional data space onto a low dimensional one (usually 1 or 2 dimensions) by clustering similar PDF representations together. The SOMs are trained on progressively narrower selections of data samples. The selection criterion is that of convergence towards a neighborhood of the experimental data. All available data sets on deep inelastic scattering in the kinematical region of 0.001 ≤ x ≤ 0.75, and 1 ≤ Q 2 ≤ 100 GeV 2 , with a cut on the final state invariant mass, W 2 ≥ 10 GeV 2 were implemented. The proposed fitting procedure, at variance with standard neural network approaches, allows for an increased control of the systematic bias by enabling the user to directly control the data selection procedure at various stages of the process. (author)
Re-examining the effect of particle phase functions on the remote-sensing reflectance.
Xiong, Yuanheng; Zhang, Xiaodong; He, Shuangyan; Gray, Deric J
2017-08-20
Even though it is well known that both the magnitude and detailed angular shape of scattering (phase function, PF), particularly in the backward angles, affect the color of the ocean, the current remote-sensing reflectance (R rs ) models typically account for the effect of its magnitude only through the backscattering coefficient (b b ). Using 116 volume scattering function (VSF) measurements previously collected in three coastal waters around the U.S. and in the water of the North Atlantic Ocean, we re-examined the effect of particle PF on R rs in four scenarios. In each scenario, the magnitude of particle backscattering (i.e., b bp ) is known, but the knowledge on the angular shape of particle backscattering is assumed to increase from knowing nothing about the shape of particle PFs to partially knowing the particle backscattering ratio (B p ), the exact backscattering shape as defined by β˜ p (γ≥90°) (particle VSF normalized by the particle total scattering coefficient), and the exact backscattering shape as defined by the χ p factor (particle VSF normalized by the particle backscattering coefficient). At sun zenith angle=30°, the nadir-viewed R rs would vary up to 65%, 35%, 20%, and 10%, respectively, as the constraints on the shape of particle backscattering become increasingly stringent from scenarios 1 to 4. In all four scenarios, the R rs variations increase with both viewing and sun angles and are most prominent in the direction opposite the sun. Our results show a greater impact of the measured particle PFs on R rs than previously found, mainly because our VSF data show a much greater variability in B p , β˜ p (γ≥90°), and χ p than previously known. Among the uncertainties in R rs due to the particle PFs, about 97% can be explained by χ p , 90% by β˜ p (γ≥90°), and 27% by B p . The results indicate that the uncertainty in ocean color remote sensing can be significantly constrained by accounting for χ p of the VSFs.
About the use of reflectance terminology in imaging spectroscopy
Schaepman-Strub, G.; Schaepman, M.E.; Dangel, S.; Painter, T.; Martonchik, J.
2005-01-01
Analysing databases, field and airborne spectrometer data, modelling studies and publications, a lack of consistency in the use of definitions and terminology of reflectance quantities can be observed. One example is the term `BRDF¿ (bidirectional reflectance distribution function) assigned to
The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...
2014-03-27
WIGNER DISTRIBUTION FUNCTIONS AS A TOOL FOR STUDYING GAS PHASE ALKALI METAL PLUS NOBLE GAS COLLISIONS THESIS Keith A. Wyman, Second Lieutenant, USAF...the U.S. Government and is not subject to copyright protection in the United States. AFIT-ENP-14-M-39 WIGNER DISTRIBUTION FUNCTIONS AS A TOOL FOR...APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED AFIT-ENP-14-M-39 WIGNER DISTRIBUTION FUNCTIONS AS A TOOL FOR STUDYING GAS PHASE ALKALI METAL PLUS
DEFF Research Database (Denmark)
2008-01-01
Method and apparatus for determining dielectric function of liquid solutions and thereby concentrations of substances in aqueous solution or the volatile/non-volatile nature of the liquid by self-referenced reflection THz spectroscopy. Having the aqueous solution in any container with a window al....... The invention is particularly useful for determining alcohol (ethanol) content in aqueous solution containing other substances and particles....
Czech Academy of Sciences Publication Activity Database
Pospíšil, Jaroslav; Jakubík, P.; Machala, L.
2005-01-01
Roč. 116, - (2005), s. 573-585 ISSN 0030-4026 Institutional research plan: CEZ:AV0Z10100522 Keywords : random-target measuring method * light-reflection white - noise target * digital video camera * modulation transfer function * power spectral density Subject RIV: BH - Optics, Masers, Lasers Impact factor: 0.395, year: 2005
Spaceflight effects on T lymphocyte distribution, function and gene expression
Gridley, Daila S.; Slater, James M.; Luo-Owen, Xian; Rizvi, Asma; Chapes, Stephen K.; Stodieck, Louis S.; Ferguson, Virginia L.; Pecaut, Michael J.
2009-01-01
The immune system is highly sensitive to stressors present during spaceflight. The major emphasis of this study was on the T lymphocytes in C57BL/6NTac mice after return from a 13-day space shuttle mission (STS-118). Spleens and thymuses from flight animals (FLT) and ground controls similarly housed in animal enclosure modules (AEM) were evaluated within 3–6 h after landing. Phytohemagglutinin-induced splenocyte DNA synthesis was significantly reduced in FLT mice when based on both counts per minute and stimulation indexes (P < 0.05). Flow cytometry showed that CD3+ T and CD19+ B cell counts were low in spleens from the FLT group, whereas the number of NK1.1+ natural killer (NK) cells was increased (P < 0.01 for all three populations vs. AEM). The numerical changes resulted in a low percentage of T cells and high percentage of NK cells in FLT animals (P < 0.05). After activation of spleen cells with anti-CD3 monoclonal antibody, interleukin-2 (IL-2) was decreased, but IL-10, interferon-γ, and macrophage inflammatory protein-1α were increased in FLT mice (P < 0.05). Analysis of cancer-related genes in the thymus showed that the expression of 30 of 84 genes was significantly affected by flight (P < 0.05). Genes that differed from AEM controls by at least 1.5-fold were Birc5, Figf, Grb2, and Tert (upregulated) and Fos, Ifnb1, Itgb3, Mmp9, Myc, Pdgfb, S100a4, Thbs, and Tnf (downregulated). Collectively, the data show that T cell distribution, function, and gene expression are significantly modified shortly after return from the spaceflight environment. PMID:18988762
Positivity properties of phase-plane distribution functions
Janssen, A.J.E.M.
1984-01-01
The aim of this paper is to compare the members of Cohen's class of phase-plane distributions with respect to positivity properties. It is known that certain averages (which are in a sense compatible with Heisenberg's uncertainty principle) of the Wigner distribution over the phase-plane yield
van Ackeren, Markus J; Schneider, Till R; Müsch, Kathrin; Rueschemeyer, Shirley-Ann
2014-10-22
Research from the previous decade suggests that word meaning is partially stored in distributed modality-specific cortical networks. However, little is known about the mechanisms by which semantic content from multiple modalities is integrated into a coherent multisensory representation. Therefore we aimed to characterize differences between integration of lexical-semantic information from a single modality compared with two sensory modalities. We used magnetoencephalography in humans to investigate changes in oscillatory neuronal activity while participants verified two features for a given target word (e.g., "bus"). Feature pairs consisted of either two features from the same modality (visual: "red," "big") or different modalities (auditory and visual: "red," "loud"). The results suggest that integrating modality-specific features of the target word is associated with enhanced high-frequency power (80-120 Hz), while integrating features from different modalities is associated with a sustained increase in low-frequency power (2-8 Hz). Source reconstruction revealed a peak in the anterior temporal lobe for low-frequency and high-frequency effects. These results suggest that integrating lexical-semantic knowledge at different cortical scales is reflected in frequency-specific oscillatory neuronal activity in unisensory and multisensory association networks. Copyright © 2014 the authors 0270-6474/14/3314318-06$15.00/0.
Directory of Open Access Journals (Sweden)
PatrÃ¬cia Branco
2016-09-01
Full Text Available One of the most overlooked topics at the level of reflection regarding law and the legal system, has been the courthouse architecture. Architecture organizes and structures space, making it intelligible, understandable, and capable of being interpreted as possible, being that the exterior and interior, as well as materials and objects present therein can facilitate or inhibit our activities through how they mean and represent certain messages. Hence it becomes necessary to make an analysis of the spaces of justice - and here I have in mind the Courthouse as a privileged public space of justice – taking into consideration the circumstances of time, place of jurisdiction, the historical, political, regulatory, and socio-cultural contexts, as well as legal tradition. Thus, and by analyzing the trends (international and national of development of construction and / or adaptation (types of buildings and internal organization, focusing on different infrastructures and accessibility and respective use, including, here, the representations and spatial practices of the real actors (professionals and users, I propose to consider the importance of regarding courthouses as spaces of justice, through the lenses given by the functions of recognition, functionality and access to law and justice. Uno de los temas sobre los que menos se ha reflexionado en el ámbito del derecho y el sistema legal ha sido la arquitectura de los juzgados. La arquitectura organiza y estructura el espacio, haciéndolo inteligible, comprensible y capaz de interpretarlo como algo posible, ya que el exterior y el interior, así como los materiales y objetos presentes, pueden facilitar o inhibir nuestras actividades mediante la forma en que emiten y representan ciertos mensajes. Por lo tanto, es necesario realizar un análisis de los espacios de la Justicia - y aquí se entiende el juzgado como un espacio público privilegiado de la Justicia - teniendo en cuenta las circunstancias de
Romanelli, N.; Mazelle, C.; Meziane, K.
2018-02-01
Seen from the solar wind (SW) reference frame, the presence of newborn planetary protons upstream from the Martian and Venusian bow shocks and SW protons reflected from each of them constitutes two sources of nonthermal proton populations. In both cases, the resulting proton velocity distribution function is highly unstable and capable of giving rise to ultralow frequency quasi-monochromatic electromagnetic plasma waves. When these instabilities take place, the resulting nonlinear waves are convected by the SW and interact with nonthermal protons located downstream from the wave generation region (upstream from the bow shock), playing a predominant role in their dynamics. To improve our understanding of these phenomena, we study the interaction between a charged particle and a large-amplitude monochromatic circularly polarized electromagnetic wave propagating parallel to a background magnetic field, from first principles. We determine the number of fix points in velocity space, their stability, and their dependence on different wave-particle parameters. Particularly, we determine the temporal evolution of a charged particle in the pitch angle-gyrophase velocity plane under nominal conditions expected for backstreaming protons in planetary foreshocks and for newborn planetary protons in the upstream regions of Venus and Mars. In addition, the inclusion of wave ellipticity effects provides an explanation for pitch angle distributions of suprathermal protons observed at the Earth's foreshock, reported in previous studies. These analyses constitute a mean to evaluate if nonthermal proton velocity distribution functions observed at these plasma environments present signatures that can be understood in terms of nonlinear wave-particle processes.
Directory of Open Access Journals (Sweden)
D. Hewson
2017-06-01
Full Text Available Evaporation induced self-assembled (EISA thin films of cellulose nanocrystals (CNCs have shown great potential for displaying structural colour across the visible spectrum. They are believed primarily to reflect left handed circularly polarised (LCP light due to their natural tendency to form structures comprising left handed chirality. Accordingly the fabrication of homogenously coloured CNC thin films is challenging. Deposition of solid material towards the edge of a dried droplet, via the coffee-stain effect, is one such difficulty in achieving homogenous colour across CNC films. These effects are most easily observed in films prepared from droplets where observable reflection of visible light is localised around the edge of the dry film. We report here, the observation of both left and right hand circularly polarised (LCP/RCP light in reflection from distinct separate regions of CNC EISA thin films and we elucidate how these reflections are dependent on the distribution of CNC material within the EISA thin film. Optical models of reflection are presented which are based on structures revealed using high resolution transmission electron microscopy (TEM images of film cross sections. We have also employed spectroscopic characterisation techniques to evaluate the distribution of solid CNC material within a selection of CNC EISA thin films and we have correlated this distribution with polarised light spectra collected from each film. We conclude that film regions from which RCP light was reflected were associated with lower CNC concentrations and thicker film regions.
Kleef, van P.W.; Trijp, van J.C.M.; Luning, P.A.; Jongen, W.M.F.
2002-01-01
Food innovation can have its source in either superior understanding of consumer demand (pull) or in superiority at the supply side (science and technology push). However, in either case market success depends on the degree to which the new product reflects unmet consumer needs. The present study
Decomposing a Utility Function Based on Discrete Distribution Independence
DEFF Research Database (Denmark)
He, Ying; Dyer, James; Butler, John
2014-01-01
For two-attribute decision-making problems, the multilinear utility model cannot be applied when the risk aversion on one attribute depends on the level of the other attribute. We propose a family of general preference conditions called nth-degree discrete distribution independence that can...... accommodate a variety of dependence relationships between two attributes. The special case of second-degree discrete distribution independence is equivalent to the utility independence condition. We focus on third-degree discrete distribution independence that leads to a decomposition formula that contains...
Directory of Open Access Journals (Sweden)
Bilčík Matúš
2018-03-01
Full Text Available Due to expansion of utilisation of photovoltaics in ordinary households, the question arises how this phenomenon affects the electric power of photovoltaic modules. The article deals with the electric power analysis of photovoltaic modules as a function of two very important factors. The first examined factor was partial shading, and the second factor was the intensity of reflected radiation. In order to determine the dependence of module power on the aforementioned parameters, a measurement system under laboratory conditions has been prepared. For identification of the reflected radiation effect on the power of the photovoltaic module, a series of measurements was performed on 7 different surfaces with the same radiation source. It is evident from obtained experimental result that the ratio of reflected irradiation on the solar module power is 1.29%. By simulation of partial shading of photovoltaic module, the decrease of 86.15% in its output power was identified.
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
Characteristic functions of scale mixtures of multivariate skew-normal distributions
Kim, Hyoung-Moon; Genton, Marc G.
2011-01-01
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
Probability Distribution Function of the Upper Equatorial Pacific Current Speeds
National Research Council Canada - National Science Library
Chu, Peter C
2005-01-01
...), constructed from hourly ADCP data (1990-2007) at six stations for the Tropical Atmosphere Ocean project satisfies the two-parameter Weibull distribution reasonably well with different characteristics between El Nino and La Nina events...
Calculations of higher twist distribution functions in the MIT bag model
International Nuclear Information System (INIS)
Signal, A.I.
1997-01-01
We calculate all twist-2, -3 and -4 parton distribution functions involving two quark correlations using the wave function of the MIT bag model. The distributions are evolved up to experimental scales and combined to give the various nucleon structure functions. Comparisons with recent experimental data on higher twist structure functions at moderate values of Q 2 give good agreement with the calculated structure functions. (orig.)
International Nuclear Information System (INIS)
Li, M.; Li, X.
2005-01-01
The probabilistic distribution of wind speed is one of the important wind characteristics for the assessment of wind energy potential and for the performance of wind energy conversion systems, as well as for the structural and environmental design and analysis. In this study, an exponential family of distribution functions has been developed for the description of the probabilistic distribution of wind speed, and comparison with the wind speed data taken from different sources and measured at different geographical locations in the world has been made. This family of distributions is developed by introducing a pre-exponential term to the theoretical distribution derived from the Maximum Entropy Principle (MEP). The statistical analysis parameter based on the wind power density is used as the suitability judgement for the distribution functions. It is shown that the MEP-type distributions not only agree better with a variety of the measured wind speed data than the conventionally used empirical Weibull distribution, but also can represent the wind power density much more accurately. Therefore, the MEP-type distributions are more suitable for the assessment of the wind energy potential and the performance of wind energy conversion systems. (author)
International Nuclear Information System (INIS)
Tang Hong; Lin Jianzhong
2013-01-01
The moment method can be used to determine the time evolution of particle size distribution due to Brownian coagulation based on the general dynamic equation (GDE). But the function form of the initial particle size distribution must be determined beforehand for the moment method. If the assumed function type of the initial particle size distribution has an obvious deviation from the true particle population, the evolution of particle size distribution may be different from the real evolution tendency. Thus, a simple and general method is proposed based on the moment method. In this method, the Johnson's S B function is chosen as a general distribution function to fit the initial distributions including the log normal (L-N), Rosin–Rammler (R-R), normal (N-N) and gamma distribution functions, respectively. Meanwhile, using the modified beta function to fit the L-N, R-R, N-N and gamma functions is also conducted as a comparison in order to present the advantage of the Johnson's S B function as the general distribution function. And then, the time evolution of particle size distributions using the Johnson's S B function as the initial distribution can be obtained by several lower order moment equations of the Johnson's S B function in conjunction with the GDE during the Brownian coagulation process. Simulation experiments indicate that fairly reasonable results of the time evolution of particle size distribution can be obtained with this proposed method in the free molecule regime, transition regime and continuum plus near continuum regime, respectively, at the early time stage of evolution. The Johnson's S B function has the ability of describing the early time evolution of different initial particle size distributions. (paper)
Regge behaviour of structure function and gluon distribution at low-x in leading order
International Nuclear Information System (INIS)
Sarma, J.K.
2000-01-01
We present a method to find the gluon distribution from the F 2 proton structure function data at low-x assuming the Regge behaviour of the gluon distribution function at this limit. We use the leading order (LO) Altarelli-Parisi (AP) evolution equation in our analysis and compare our result with those of other authors. We also discuss the limitations of the Taylor expansion method in extracting the gluon distribution from the F 2 structure function used by those authors. (orig.)
End to end distribution functions for a class of polymer models
International Nuclear Information System (INIS)
Khandekar, D.C.; Wiegel, F.W.
1988-01-01
The two point end-to-end distribution functions for a class of polymer models have been obtained within the first cumulant approximation. The trial distribution function this purpose is chosen to correspond to a general non-local quadratic functional. An Exact expression for the trial distribution function is obtained. It is pointed out that these trial distribution functions themselves can be used to study certain aspects of the configurational behaviours of polymers. These distribution functions are also used to obtain the averaged mean square size 2 > of a polymer characterized by the non-local quadratic potential energy functional. Finally, we derive an analytic expression for 2 > of a polyelectrolyte model and show that for a long polymer a weak electrostatic interaction does not change the behaviour of 2 > from that of a free polymer. (author). 16 refs
Transition in the equilibrium distribution function of relativistic particles.
Mendoza, M; Araújo, N A M; Succi, S; Herrmann, H J
2012-01-01
We analyze a transition from single peaked to bimodal velocity distribution in a relativistic fluid under increasing temperature, in contrast with a non-relativistic gas, where only a monotonic broadening of the bell-shaped distribution is observed. Such transition results from the interplay between the raise in thermal energy and the constraint of maximum velocity imposed by the speed of light. We study the Bose-Einstein, the Fermi-Dirac, and the Maxwell-Jüttner distributions, and show that they all exhibit the same qualitative behavior. We characterize the nature of the transition in the framework of critical phenomena and show that it is either continuous or discontinuous, depending on the group velocity. We analyze the transition in one, two, and three dimensions, with special emphasis on twodimensions, for which a possible experiment in graphene, based on the measurement of the Johnson-Nyquist noise, is proposed.
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 conne......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...
Hiremath, Chaitra; Dey, Avyarthana
2017-01-01
Abstract Background: Self-reflection is the process of conscious evaluation of one’s traits, abilities, and attitudes. Deficient self-reflective processes might underlie lack of insight into schizophrenia. The limited research literature on the neural correlates of self-reflection in schizophrenia is inconclusive. In this study, we investigated the neural correlates of self-reflection in schizophrenia patients attending a tertiary care hospital in India. Methods: Nineteen male schizophrenia patients (mean age = 32.68 ± 7.11, mean years of education =15.21 ± 1.93) and 19 male healthy controls (mean age = 26.96 ± 4.67, mean years of education = 18.11 ± 3.13) participated in the study. Participants performed a previously validated self-reflection task while undergoing functional magnetic resonance imaging (fMRI; 3-Tesla). The task comprised of 144 words subdivided into 4 domains: Self-reflection, Other-reflection, Affect labeling, and Perceptual. The task was presented as 3 runs of 8 blocks each. The images were preprocessed and analyzed using SPM-12. After preprocessing, contrasts comparing Self-reflection with the other domains were modeled at the individual subject level. In second-level analysis, the first-level contrasts were entered into a 2-sample t test to compare patient and healthy control groups. The results were thresholded at P Self-reflection > Other-reflection contrast, schizophrenia patients demonstrated greater activation of right and left superior parietal lobules (BA 5 and 7), right inferior parietal lobule (BA 39), left parahippocampal gyrus (BA 36), and left premotor cortex (BA 6). For the Self-reflection > Affect labeling contrast, patients showed greater activation of precuneus (BA 7) and right inferior occipital gyrus (BA 19), and lesser activation of left inferior frontal gyrus (BA 45 and 47). And for the Self-reflection > Perceptual contrast, patients showed greater activation of left middle frontal gyrus (BA 10
Grassi, Davide; Desideri, Giovambattista; Necozione, Stefano; Ruggieri, Fabrizio; Blumberg, Jeffrey B; Stornello, Michele; Ferri, Claudio
2012-09-01
Nitric oxide plays a pivotal role in regulating vascular tone. Different studies show endothelial function is impaired during hyperglycemia. Dark chocolate increases flow-mediated dilation in healthy and hypertensive subjects with and without glucose intolerance; however, the effect of pretreatment with dark chocolate on endothelial function and other vascular responses to hyperglycemia has not been examined. Therefore, we aimed to investigate the effects of flavanol-rich dark chocolate administration on (1) flow-mediated dilation and wave reflections; (2) blood pressure, endothelin-1 and oxidative stress, before and after oral glucose tolerance test (OGTT). Twelve healthy volunteers (5 males, 28.2±2.7 years) randomly received either 100 g/d dark chocolate or flavanol-free white chocolate for 3 days. After 7 days washout period, volunteers were switched to the other treatment. Flow-mediated dilation, stiffness index, reflection index, peak-to-peak time, blood pressure, endothelin-1 and 8-iso-PGF(2α) were evaluated after each treatment phase and OGTT. Compared with white chocolate, dark chocolate ingestion improved flow-mediated dilation (P=0.03), wave reflections, endothelin-1 and 8-iso-PGF(2α) (Pwave reflections, blood pressure, and endothelin-1 and 8-iso-PGF(2α) increased after OGTT. OGTT causes acute, transient impairment of endothelial function and oxidative stress, which is attenuated by flavanol-rich dark chocolate. These results suggest cocoa flavanols may contribute to vascular health by reducing the postprandial impairment of arterial function associated with the pathogenesis of atherosclerosis.
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
Functional distribution of coronary vascular volume in beating goat hearts
van der Ploeg, C. P.; Dankelman, J.; Spaan, J. A.
1993-01-01
With use of hemoglobin-bound O2 as an endogenous tracer, intramyocardial blood volume distribution between vessels involved in O2 exchange and more distal vessels was estimated. In nine anesthetized open-chest goats, the left main coronary artery was cannulated and perfused at a constant flow.
Comparative study of the uncertainties in parton distribution functions
International Nuclear Information System (INIS)
Alekhin, S.I.
2003-01-01
Comparison of the methods used to extract the uncertainties in parton distributions is given, including their statistical properties and practical issues of implementation. Advantages and disadvantages of different methods are illustrated using the examples based on the analysis of real data. Available PDFs sets with associated uncertainties are reviewed and critically compared
Data synthesis and display programs for wave distribution function analysis
Storey, L. R. O.; Yeh, K. J.
1992-01-01
At the National Space Science Data Center (NSSDC) software was written to synthesize and display artificial data for use in developing the methodology of wave distribution analysis. The software comprises two separate interactive programs, one for data synthesis and the other for data display.
Directory of Open Access Journals (Sweden)
Sanjay Kumar Singh
2011-06-01
Full Text Available In this Paper we propose Bayes estimators of the parameters of Exponentiated Exponential distribution and Reliability functions under General Entropy loss function for Type II censored sample. The proposed estimators have been compared with the corresponding Bayes estimators obtained under Squared Error loss function and maximum likelihood estimators for their simulated risks (average loss over sample space.
Emrich, Stephen M; Riggall, Adam C; Larocque, Joshua J; Postle, Bradley R
2013-04-10
Traditionally, load sensitivity of sustained, elevated activity has been taken as an index of storage for a limited number of items in visual short-term memory (VSTM). Recently, studies have demonstrated that the contents of a single item held in VSTM can be decoded from early visual cortex, despite the fact that these areas do not exhibit elevated, sustained activity. It is unknown, however, whether the patterns of neural activity decoded from sensory cortex change as a function of load, as one would expect from a region storing multiple representations. Here, we use multivoxel pattern analysis to examine the neural representations of VSTM in humans across multiple memory loads. In an important extension of previous findings, our results demonstrate that the contents of VSTM can be decoded from areas that exhibit a transient response to visual stimuli, but not from regions that exhibit elevated, sustained load-sensitive delay-period activity. Moreover, the neural information present in these transiently activated areas decreases significantly with increasing load, indicating load sensitivity of the patterns of activity that support VSTM maintenance. Importantly, the decrease in classification performance as a function of load is correlated with within-subject changes in mnemonic resolution. These findings indicate that distributed patterns of neural activity in putatively sensory visual cortex support the representation and precision of information in VSTM.
International Nuclear Information System (INIS)
Vondreele, R.; Larson, A.; Lawson, A.; Sheldon, R.; Wright, S.
1996-01-01
The preferred orientation of crystal grains within a manufactured part is described most fully by its orientation distribution function (ODF), which is a mapping of the probability of each of the possible grain orientations with respect to the exterior dimensions. Traditionally, an ODF is determined from pole figures for a relatively small number of reflections. These pole figures are measured with x-rays or neutrons using short detector scans over the center of an individual diffraction peak for a large number of different sample orientations. This is efficient if the selected diffraction peaks are reasonably strong (relative to background) and well separated, such as in pure fcc and bcc metals. It is also appropriate for constant wavelength sources where collection of individual diffraction peak intensities is a reasonably efficient use of the source. However, the traditional method is not very efficient for neutron diffraction at a spallation source such as LANSCE where the entire diffraction pattern is accessible for each sample setting. Moreover, a different approach is necessary for complicated diffraction patterns, such as from composite materials, intermetallic compounds, high T c ceramics, polyphasic minerals and polymers where there is expected to be heavy overlap of adjacent diffraction peaks. In addition, the large number of settings normally collected for an individual pole figure may not be necessary, since the entire pattern is obtained at each setting. Thus, a new method of ODF analysis needs to be developed to handle the more complex diffraction patterns obtained from modern technological materials as well as take advantage of the particular characteristics of spallation neutron sources. This project sought to develop the experimental procedures and the mathematical treatment needed to produce an orientation distribution function (ODF) directly from full diffraction patterns from a sample in a limited number of orientations
Towards Bayesian Inference of the Fast-Ion Distribution Function
DEFF Research Database (Denmark)
Stagner, L.; Heidbrink, W.W.; Salewski, Mirko
2012-01-01
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....... 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...
QCD phenomenology of parton distribution functions at small x
International Nuclear Information System (INIS)
Tung, Wu-Ki
1990-09-01
The small x behavior of parton distributions is studied phenomenologically by examining in detail a series of QCD-evolved distribution sets obtained in a new global analysis of deep inelastic scattering and lepton-pair production experiments. The importance of 2-loop evolution is discussed. The main features and results of the global analysis are described. The range of small x behavior consistent with next-to-leading order QCD and current data is delineated. The extrapolated small x behavior is parameterized by effective Q-dependent power- and logarithmic-law parameters. Intriguing features of the evolution of these parameters with Q are presented. Alternative parametrizations based on the analytic solution for small x is also explored. 20 refs., 6 figs., 1 tab
Frequency distribution function of stellar flares in the Orion association
International Nuclear Information System (INIS)
Parsamian, E.S.
1981-01-01
The temporal distributions of flare stars in the Orion association and the numbers of stars with different flare frequencies are determined by means of Ambartsumian's (1978) method, which uses the chronology of discovery of 'first' flares and the chronology of confirmations, i.e., the temporal distributions of 'repeated' flares. It is shown that flare stars with high flare frequency (not greater than 1000 hours) in the Pleiades are basically stars of low luminosity with M(U) not less than 13m. Two independent methods of determining the number of flare stars in the aggregates confirm that there are about 1.5 times more flare stars in the Orion association than in the Pleiades
Plasma distribution functions in accretion onto neutron stars
International Nuclear Information System (INIS)
Cramer, N.F.
1982-01-01
Even though it is likely that the process of creation of an inverted electron distribution in the slowly converging magnetic field lines would not arise because of the fast destruction of anisotropy by collisions, it is possible that a rapid build-up of an inverted population, as might occur in a shock transition, could be preserved for a relatively long time by means of transfer of momentum, rather than energy, from an inverted population of protons
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.
Lima, Alice; Lemasson, Alban; Boye, Martin; Hausberger, Martine
2017-12-01
Under natural conditions bottlenose dolphins (Tursiops truncatus) spend their time mostly feeding and then travelling, socializing, or resting. These activities are not randomly distributed, with feeding being higher in early morning and late afternoon. Social activities and vocal behavior seem to be very important in dolphin daily activity. This study aimed to describe the activity time-budget and its relation to vocal behavior for dolphins in a zoological park. We recorded behaviors and vocalizations of six dolphins over 2 months. All subjects performed more non-agonistic social interactions and play in the morning than in the afternoon. The different categories of vocalizations were distributed non-randomly throughout the day, with more chirps in the afternoon, when the animals were "less social." The most striking result was the strong correlation between activities and the categories of vocalizations produced. The results confirm the association between burst pulses and whistles with social activities, but also reveal that both are also associated with solitary play. More chirps were produced when dolphins were engaged in socio-sexual behaviors, emphasizing the need for further questioning about the function of this vocal category. This study reveals that: (i) in a group kept in zoological management, social activities are mostly present in the morning; and (ii) the acoustic signals produced by dolphins may give a reliable representation of their current activities. While more studies on the context of signal production are needed, our findings provide a useful tool for understanding free ranging dolphin behavior when they are not visible. © 2017 Wiley Periodicals, Inc.
Optic neuropathies--importance of spatial distribution of mitochondria as well as function.
Yu Wai Man, C Y; Chinnery, P F; Griffiths, P G
2005-01-01
Optic neuropathies such as Leber's hereditary optic neuropathy, dominant optic atrophy and toxic amblyopia are an important cause of irreversible visual failure. Although they are associated with a defect of mitochondrial energy production, their pathogenesis is poorly understood. A common feature to all these disorders is relatively selective degeneration of the papillomacular bundle of retinal ganglion cells resulting central or caecocentral visual field defects. The striking similarity in the pattern of clinical involvement seen with these disparate disorders suggests a common pathway in their aetiology. The existing hypothesis that the optic nerve head has higher energy demands than other tissues making it uniquely dependent on oxidative phosporylation is not satisfactory. First, other ocular tissues such as photoreceptors, which are more dependent on oxidative phosporylation are not affected. Second, other mitochondrial disorders, which have a greater impact on mitochondrial energy function, do not affect the optic nerve. The optic nerve head has certain unique ultra structural features. Ganglion cell axons exit the eye through a perforated collagen plate, the lamina cribrosa. There is a sharp discontinuity in the density of mitochondria at the optic nerve head, with a very high concentration in the prelaminar nerve fibre layer and low concentration behind the lamina. This has previously been attributed to a mechanical hold up of axoplasmic flow, which has itself been proposed as a factor in the pathogenesis of a number of optic neuropathies. More recent evidence shows that mitochondrial distribution reflects the different energy requirements of the unmyelinated prelaminar axons in comparison to the myelinated retrolaminar axons. The heterogeous distribution of mitochondria is actively maintained to support conduction through the optic nerve head. We propose that factors that disrupt the heterogeneous distribution of mitochondria can result in ganglion cell
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.
Existence of the Wigner function with correct marginal distributions along tilted lines on a lattice
International Nuclear Information System (INIS)
Horibe, Minoru; Takami, Akiyoshi; Hashimoto, Takaaki; Hayashi, Akihisa
2002-01-01
For the Wigner function of a system in N-dimensional Hilbert space, we propose the condition, which ensures that the Wigner function has correct marginal distributions along tilted lines. Under this condition we get the Wigner function without ambiguity if N is odd. If N is even, the Wigner function does not exist
The Wigner distribution function and Hamilton's characteristics of a geometric-optical system
Bastiaans, M.J.
1979-01-01
Four system functions have been defined for an optical system; each of these functions describes the system completely in terms of Fourier optics. From the system functions the Wigner distribution function of an optical system has been defined; although derived from Fourier optics, this Wigner
CT-quantified emphysema distribution is associated with lung function decline
Hoesein, F.A.A.M.; Rikxoort, E.M. van; Ginneken, B. van; de Jong, P. A.; Prokop, M.; Lammers, J.W.; Zanen, P.
2012-01-01
Emphysema distribution is associated with COPD. It is however unknown whether CT-quantified emphysema distribution (upper/lower lobe) is associated with lung function decline in heavy (former) smokers.587 male participants underwent lung CT-scanning and pulmonary function testing at baseline and
About the functions of the Wigner distribution for the q-deformed harmonic oscillator model
International Nuclear Information System (INIS)
Atakishiev, N.M.; Nagiev, S.M.; Djafarov, E.I.; Imanov, R.M.
2005-01-01
Full text : A q-deformed model of the linear harmonic oscillator in the Wigner phase-space is studied. It was derived an explicit expression for the Wigner probability distribution function, as well as the Wigner distribution function of a thermodynamic equilibrium for this model
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...
The Wigner distribution function for the one-dimensional parabose oscillator
International Nuclear Information System (INIS)
Jafarov, E; Lievens, S; Jeugt, J Van der
2008-01-01
In the beginning of the 1950s, Wigner introduced a fundamental deformation from the canonical quantum mechanical harmonic oscillator, which is nowadays sometimes called a Wigner quantum oscillator or a parabose oscillator. Also, in quantum mechanics the so-called Wigner distribution is considered to be the closest quantum analogue of the classical probability distribution over the phase space. In this paper, we consider which definition for such a distribution function could be used in the case of non-canonical quantum mechanics. We then explicitly compute two different expressions for this distribution function for the case of the parabose oscillator. Both expressions turn out to be multiple sums involving (generalized) Laguerre polynomials. Plots then show that the Wigner distribution function for the ground state of the parabose oscillator is similar in behaviour to the Wigner distribution function of the first excited state of the canonical quantum oscillator
Zambrano García, A.; Medina Coyotzin, C.; Rojas Amaro, A.; López Veneroni, D.; Martínez, L. Chang; Sosa Iglesias, G.
2009-09-01
Mezquital Valley (MV), a Mexican wastewater-based agricultural and industrial region, is a "hot spot" of regulated air pollutants emissions, but the concurrent unregulated ones, like hazardous metals and polycyclic aromatic hydrocarbons (PAH), remain undocumented. A biomonitoring survey with the epiphytic Tillandsia recurvata was conducted there to detect spatial patterns and potential sources of 20 airborne elements and 15 PAH. The natural δ13C and δ15N ratios of this plant helped in source identification. The regional mean concentration of most elements was two (Cr) to over 40 times (Ni, Pb, V) higher than reported for Tillandsia in other countries. Eleven elements, pyrene and chrysene had 18-214% higher mean concentration at the industrial south than at the agricultural north of MV. The total quantified PAH (mean, 572 ng g-1; range, 143-2568) were composed by medium (65%, phenanthrene to chrysene), low (28%, naphthalene to fluorene) and high molecular weight compounds (7%, Benzo(b)fluoranthene to indeno(1,2,3-cd)pyrene). The δ13C (mean, -14.6‰; range, -15.7‰ to -13.7‰) was consistently lower than -15‰ near the major petroleum combustion sources. The δ15N (mean, -3.0‰; range, -9.9‰ to 3.3‰) varied from positive at agriculture/industrial areas to negative at rural sites. Factor analysis provided a five-factor solution for 74% of the data variance: 1) crustal rocks, 39.5% (Al, Ba, Cu, Fe, Sr, Ti); 2) soils, 11.3%, contrasting contributions from natural (Mg, Mn, Zn) and saline agriculture soils (Na); 3) cement production and fossil fuel combustion, 9.8% (Ca, Ni, V, chrysene, pyrene); 4) probable agricultural biomass burning, 8.1% (K and benzo(g,h,i)perylene), and 5) agriculture with wastewater, 5.2% (δ15N and P). These results indicated high deposition of bioaccumulative air pollutants at MV, especially at the industrial area. Since T. recurvata reflected the regional differences in exposition, it is recommended as a biomonitor for comparisons
Ma, Wei-Ming
1997-06-01
An analytical two-flow model is derived from the radiative transfer equation to simulate the distribution of irradiance in coastal waters with a wind-roughed surface and bottom reflectance. The model utilizes unique boundary conditions, including the surface slope of the downwelling and upwelling irradiance as well as the influence of wind and bottom reflectance on simulated surface reflectance. The developed model provides a simple mathematical concept for understanding the irradiant light flux and associated processes in coastal or fresh water as well as turbid estuarine waters. The model is applied to data from the Banana River and coastal Atlantic Ocean water off the east coast of central Florida, USA. The two-flow irradiance model is capable of simulating realistic above-surface reflectance signatures under wind-roughened air-water surface given realistic input parameters including a specular flux conversion coefficient, absorption coefficient, backscattering coefficient, atmospheric visibility, bottom reflectance, and water depth. The root-mean-squared error of the calculated above-surface reflectances is approximately 3% in the Banana River and is less than 15% in coastal Atlantic Ocean off the east of Florida. Result of the subsurface reflectance sensitivity analysis indicates that the specular conversion coefficient is the most sensitive parameter in the model, followed by the beam attenuation coefficient, absorption coefficient, water depth, backscattering coefficient, specular irradiance, diffuse irradiance, bottom reflectance, and wind speed. On the other hand, result of the above-surface reflectance sensitivity analysis indicates that the wind speed is the most important parameter, followed by bottom reflectance, attenuation coefficient, water depth, conversion coefficient, specular irradiance, downwelling irradiance, absorption coefficient, and backscattering coefficient. Model results depend on the accuracy of these parameters to a large degree and
Directory of Open Access Journals (Sweden)
José F González-Maya
Full Text Available Functional diversity represents a measure of diversity that incorporates the role of species in an ecosystem, and therefore its dynamics and resilience. Assessing its drivers and spatial variation represents an important step forward in our understanding of functional ecosystem dynamics and it is also necessary to achieve a comprehensive conservation planning. In this paper, we assessed mammal functional diversity for the 218 ecoregions within the Neotropical realm. We evaluated the overall influence and spatial variation of species richness, ecoregion extent, intervention and species at risk on functional diversity. Using ordinary least squares and geographically weighted regression modeling approaches, we found that intervened areas and threatened and non-threatened species are the most influential overall drivers of functional diversity. However, we also detected that these variables do not operate equally across scales. Our local analyses indicated both that the variation explained and local coefficients vary spatially depending on the ecoregion and major habitat type. As estimates of functional diversity are based on current distribution of all mammals, negative influence of intervened areas and positive influence of non-threatened species may reflect a potential degradation of functional processes for some ecosystems. Most generally, the negative influence of intervention together with the influence of threatened species indicates that some areas are currently more susceptible to functional diversity loss. Our results help to pinpoint key areas requiring urgent conservation action to reduce natural land-cover loss and areas where threatened species play influential roles on ecosystem functioning.
Measurement-induced decoherence and Gaussian smoothing of the Wigner distribution function
International Nuclear Information System (INIS)
Chun, Yong-Jin; Lee, Hai-Woong
2003-01-01
We study the problem of measurement-induced decoherence using the phase-space approach employing the Gaussian-smoothed Wigner distribution function. Our investigation is based on the notion that measurement-induced decoherence is represented by the transition from the Wigner distribution to the Gaussian-smoothed Wigner distribution with the widths of the smoothing function identified as measurement errors. We also compare the smoothed Wigner distribution with the corresponding distribution resulting from the classical analysis. The distributions we computed are the phase-space distributions for simple one-dimensional dynamical systems such as a particle in a square-well potential and a particle moving under the influence of a step potential, and the time-frequency distributions for high-harmonic radiation emitted from an atom irradiated by short, intense laser pulses
Multi-level methods and approximating distribution functions
International Nuclear Information System (INIS)
Wilson, D.; Baker, R. E.
2016-01-01
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.
Iodine-125 toxicity as a function of intranuclear radionuclide distribution
International Nuclear Information System (INIS)
Yasui, L.S.; Hofer, K.G.
1984-01-01
Chinese hamster ovary (CHO) cells were synchronized in the G/sub 1/ phase of the cell cycle by isoleucine deprivation and then subjected to 8 hr. labeling with /sup 125/I-iododeoxyuridine (/sup 125/IUdR) either in the presence or absence of aphidicolin. Cells labeled in the presence of aphidicolin showed a D/sub 0/ of 30 decays/cell as compared to a D/sub 0/ of 90-100 decays for control cells. Presumably, aphidicolin had shifted /sup 125/IUdR incorporation into a sensitive sub-fraction of the nuclear genome. However, no aphidicolin effect was seen in identical studies on asynchronous cell populations, i.e., both control and aphidicolin treated cells showed a D/sub 0/ of 90-100 decays/cell. An attempt was made to correlate /sup 125/I toxicity with intranuclear /sup 125/I distribution. Electron-microsopic autoradiography and Chi=squared analysis revealed that in all experimental groups grain density was highest in the heterochromatin region of the nucleus. However, isoleucine deprivation lead to a dramatic decrease in the nuclear area occupied by heterochromatin (19.5% in control cells, 0.7% in synchronized cells), resulting in a corresponding increase in area and grain density for the euchromatin containing portion of the nucleus. These observations suggest that any shift in intranuclear distribution of /sup 125/I causes a dramatic change in the toxic effects of intranuclear /sup 125/I decays
Multi-level methods and approximating distribution functions
Energy Technology Data Exchange (ETDEWEB)
Wilson, D., E-mail: daniel.wilson@dtc.ox.ac.uk; Baker, R. E. [Mathematical Institute, University of Oxford, Radcliffe Observatory Quarter, Woodstock Road, Oxford, OX2 6GG (United Kingdom)
2016-07-15
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.
Lyons, Kristen E; Zelazo, Philip David
2011-01-01
While an abundance of research has investigated the development of the automatic and controlled processes through which individuals control their thoughts, emotions, and actions, less research has emphasized the role of the self in self-regulation. This chapter synthesizes four literatures that have examined the mechanisms through which the individual acts in a managerial role, evaluating the current status of the system and initiating regulatory actions as necessary. Taken together, these literatures (on executive function, error monitoring, metacognition, and uncertainty monitoring) suggest that self-reflection plays a critical role in self-regulation, and that developmental improvements in self-reflection (via increasing levels of conscious awareness and enhanced calibration of monitoring systems) may serve as driving forces underlying developmental improvement (and temperamental individual differences) in children's ability to control their thoughts and actions.
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
The distribution function of a probability measure on a space with a fractal structure
Energy Technology Data Exchange (ETDEWEB)
Sanchez-Granero, M.A.; Galvez-Rodriguez, J.F.
2017-07-01
In this work we show how to define a probability measure with the help of a fractal structure. One of the keys of this approach is to use the completion of the fractal structure. Then we use the theory of a cumulative distribution function on a Polish ultrametric space and describe it in this context. Finally, with the help of fractal structures, we prove that a function satisfying the properties of a cumulative distribution function on a Polish ultrametric space is a cumulative distribution function with respect to some probability measure on the space. (Author)
Francisco, E.; Pendás, A. Martín; Blanco, M. A.
2008-04-01
Given an N-electron molecule and an exhaustive partition of the real space ( R) into m arbitrary regions Ω,Ω,…,Ω ( ⋃i=1mΩ=R), the edf program computes all the probabilities P(n,n,…,n) of having exactly n electrons in Ω, n electrons in Ω,…, and n electrons ( n+n+⋯+n=N) in Ω. Each Ω may correspond to a single basin (atomic domain) or several such basins (functional group). In the later case, each atomic domain must belong to a single Ω. The program can manage both single- and multi-determinant wave functions which are read in from an aimpac-like wave function description ( .wfn) file (T.A. Keith et al., The AIMPAC95 programs, http://www.chemistry.mcmaster.ca/aimpac, 1995). For multi-determinantal wave functions a generalization of the original .wfn file has been introduced. The new format is completely backwards compatible, adding to the previous structure a description of the configuration interaction (CI) coefficients and the determinants of correlated wave functions. Besides the .wfn file, edf only needs the overlap integrals over all the atomic domains between the molecular orbitals (MO). After the P(n,n,…,n) probabilities are computed, edf obtains from them several magnitudes relevant to chemical bonding theory, such as average electronic populations and localization/delocalization indices. Regarding spin, edf may be used in two ways: with or without a splitting of the P(n,n,…,n) probabilities into α and β spin components. Program summaryProgram title: edf Catalogue identifier: AEAJ_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEAJ_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 5387 No. of bytes in distributed program, including test data, etc.: 52 381 Distribution format: tar.gz Programming language: Fortran 77 Computer
A distributed transducer system for functional electrical stimulation
DEFF Research Database (Denmark)
Gudnason, Gunnar; Nielsen, Jannik Hammel; Bruun, Erik
2001-01-01
to be affected by the inductive link. Neural stimulators are affected to a lesser degree, but still benefit from the partitioning. As a test case, we have designed a transceiver and a sensor chip which implement this partitioning policy. The transceiver is designed to operate in the 6.78 MHz ISM band......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...... to these problems by partitioning the RF transceiver and sensor/actuator functions onto separate integrated circuits. By amplifying measured neural signals directly at the measurements site and converting them into the digital domain before passing them to the transceiver the signal integrity is less likely...
Distributing functionality in the Drift Scan Camera System
International Nuclear Information System (INIS)
Nicinski, T.; Constanta-Fanourakis, P.; MacKinnon, B.; Petravick, D.; Pluquet, C.; Rechenmacher, R.; Sergey, G.
1993-11-01
The Drift Scan Camera (DSC) System acquires image data from a CCD camera. The DSC is divided physically into two subsystems which are tightly coupled to each other. Functionality is split between these two subsystems: the front-end performs data acquisition while the host subsystem performs near real-time data analysis and control. Yet, through the use of backplane-based Remote Procedure Calls, the feel of one coherent system is preserved. Observers can control data acquisition, archiving to tape, and other functions from the host, but, the front-end can accept these same commands and operate independently. The DSC meets the needs for such robustness and cost-effective computing
SYSTEMIC REFLECTION AS A PRECURSOR OF THE OPTIMAL FUNCTIONING OF ADOLESCENTS
Directory of Open Access Journals (Sweden)
A. H. Chetveryk-Burchak
2016-04-01
Results. The results demonstrated that systemic reﬂection was positively correlated with emotional creativity, psychological and subjective forms of well-being and mental health continuum of the adolescents. The multiple correlation-regression analysis yielded the most informative aspects of the reﬂection and emotional creativity predictive of the optimal functioning of an individual. They include: positive correlations with systemic reﬂection and all features of emotional creativity (novelty, effectiveness, authenticity, and negative with quasi-reﬂection. Conclusions. It was proved that systemic reﬂection was a statistically signiﬁcant positive predictor for optimal functioning of the adolescents.
Modelling the joint distribution of competing risks survival times using copula functions
Kaishev, V. K.; Haberman, S.; Dimitrova, D. S.
2005-01-01
The problem of modelling the joint distribution of survival times in a competing risks model, using copula functions is considered. In order to evaluate this joint distribution and the related overall survival function, a system of non-linear differential equations is solved, which relates the crude and net survival functions of the modelled competing risks, through the copula. A similar approach to modelling dependent multiple decrements was applied by Carriere (1994) who used a Gaussian cop...
Formative versus Reflective Measurement in Executive Functions: A Critique of Willoughby et al.
Peterson, Eric; Welsh, Marilyn C.
2014-01-01
Research into executive functioning (EF) has indeed grown exponentially across the past few decades, but as the Willoughby et al. critique makes clear, there remain fundamental questions to be resolved. The crux of their argument is built upon an examination of the confirmatory factor analysis (CFA) approach to understanding executive processes.…
A step towards functional integration : Reflection program case ‘Rotterdam roof park’
Kok, M.; Kothuis, Baukje; Kok, Matthijs
2017-01-01
Many functions are combined in the Rotterdam Roof Park project: It is a shopping mall, a parking garage, a park on the roof, and last but not least, a flood defense. The research in our program was done after the buildings and structures had been built. So the
Brachial index does not reflect upper extremity functionality following surgery for vascular trauma
Directory of Open Access Journals (Sweden)
Erdal Simsek
2014-04-01
Full Text Available OBJECTIVES: Vascular injuries to the upper extremities requiring surgical repair are common after accidents. However, neither postoperative functionality nor hemodynamic status of the extremity are routinely described. We evaluated the postoperative functional and hemodynamic status of patients with vascular traumas in the upper extremities. METHODS: 26 patients who suffered penetrating vascular traumas in the upper extremities from November 2008 to December 2011 were retrospectively evaluated. Data on first approach, surgical technique employed and early postoperative outcomes were recorded. Further data on the post-discharge period, including clinical functional status of the arm, Doppler ultrasonography and brachial-brachial index were also evaluated. RESULTS: Average follow up was 33.5±10.8 months. Right (1.05±0.09 and left (1.04±0.08 brachial indexes were measured during follow up,. Doppler ultrasonography showed arterial occlusion in 4 patients (15%. Near-normal brachial-brachial indexes was observed in all four of these patients with occlusion of one of the upper extremity arteries, even though they exhibited limited arm function for daily work. CONCLUSIONS: Evaluation of the postoperative outcomes of this small series of patients with penetrating vascular traumas in the upper extremity revealed that 15% of them suffered occlusion of one artery of the upper extremity. Artery occlusion did not correlate with brachial-brachial Doppler index, probably due to rich collateral circulation, but occlusion was associated with an extremity that was dysfunctional for the purposes of daily work. The result of the brachial-brachial index does not therefore correlate with functionality.
Lei, Ning; Xiong, Xiaoxiong
2016-01-01
The Visible Infrared Imaging Radiometer Suite (VIIRS) aboard the Suomi National Polar-orbiting Partnership (SNPP) satellite is a passive scanning radiometer and an imager, observing radiative energy from the Earth in 22 spectral bands from 0.41 to 12 microns which include 14 reflective solar bands (RSBs). Extending the formula used by the Moderate Resolution Imaging Spectroradiometer instruments, currently the VIIRS determines the sensor aperture spectral radiance through a quadratic polynomial of its detector digital count. It has been known that for the RSBs the quadratic polynomial is not adequate in the design specified spectral radiance region and using a quadratic polynomial could drastically increase the errors in the polynomial coefficients, leading to possible large errors in the determined aperture spectral radiance. In addition, it is very desirable to be able to extend the radiance calculation formula to correctly retrieve the aperture spectral radiance with the level beyond the design specified range. In order to more accurately determine the aperture spectral radiance from the observed digital count, we examine a few polynomials of the detector digital count to calculate the sensor aperture spectral radiance.
Mannaerts, Dominique; Faes, Ellen; Goovaerts, Inge; Stoop, Tibor; Cornette, Jerome; Gyselaers, Wilfried; Spaanderman, Marc; Van Craenenbroeck, Emeline M; Jacquemyn, Yves
2017-11-01
Endothelial function and arterial stiffness are known to be altered in preeclamptic pregnancies. Previous studies have shown conflicting results regarding the best technique for assessing vascular function in pregnancy. In this study, we made a comprehensive evaluation of in vivo vascular function [including flow-mediated dilatation (FMD), peripheral arterial tonometry (PAT), and arterial stiffness] in preeclamptic patients and compared them with normal pregnancies. In addition, we assessed the relation between vascular function and systemic inflammation. Fourteen patients with preeclampsia (PE) and 14 healthy pregnant controls were included. Endothelial function was determined by FMD and PAT and arterial stiffness by carotid-femoral pulse-wave velocity and augmentation index. Systemic inflammation was assessed using mean platelet volume (MPV) and neutrophil-lymphocyte ratio (NLR). The reactive hyperemia index, assessed using PAT, is decreased at the third trimester compared with the first trimester in a normal, uncomplicated pregnancy ( P = 0.001). Arterial stiffness is significantly higher in PE versus normal pregnancy ( P function, obtained by FMD, is deteriorated in PE versus normal pregnancy ( P = 0.015), whereas endothelial function assessment by PAT is improved in PE versus normal pregnancy ( P = 0.001). Systemic inflammation (MPV and NLR) increases during normal pregnancy. FMD and PAT are disturbed in PE. Endothelial function, assessed by FMD and PAT, shows distinct results. This may indicate that measurements with FMD and PAT reflect different aspects of endothelial function and that PAT should not be used as a substitute for FMD as a measure of endothelial function in pregnancy. Copyright © 2017 the American Physiological Society.
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 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
Sargisson, Rebecca J; White, K Geoffrey
2003-11-01
Forgetting functions with 18 delay intervals were generated for delayed matching-to-sample performance in pigeons. Delay interval variation was achieved by arranging five different sets of five delays across daily sessions. In different conditions, the delays were distributed in arithmetic or logarithmic series. There was no convincing evidence for different effects on discriminability of the distributions of different delays. The mean data were better fitted by some mathematical functions than by others, but the best-fitting functions depended on the distribution of delays. In further conditions with a fixed set of five delays, discriminability was higher with a logarithmic distribution of delays than with an arithmetic distribution. This result is consistent with the treatment of the forgetting function in terms of generalization decrement.
Bjørneraas, Kari; Herfindal, Ivar; Solberg, Erling Johan; Sæther, Bernt-Erik; van Moorter, Bram; Rolandsen, Christer Moe
2012-01-01
Identifying factors shaping variation in resource selection is central for our understanding of the behaviour and distribution of animals. We examined summer habitat selection and space use by 108 Global Positioning System (GPS)-collared moose in Norway in relation to sex, reproductive status, habitat quality, and availability. Moose selected habitat types based on a combination of forage quality and availability of suitable habitat types. Selection of protective cover was strongest for reproducing females, likely reflecting the need to protect young. Males showed strong selection for habitat types with high quality forage, possibly due to higher energy requirements. Selection for preferred habitat types providing food and cover was a positive function of their availability within home ranges (i.e. not proportional use) indicating functional response in habitat selection. This relationship was not found for unproductive habitat types. Moreover, home ranges with high cover of unproductive habitat types were larger, and smaller home ranges contained higher proportions of the most preferred habitat type. The distribution of moose within the study area was partly related to the distribution of different habitat types. Our study shows how distribution and availability of habitat types providing cover and high-quality food shape ungulate habitat selection and space use.
MORSEC-SP, Step Function Angular Distribution for Cross-Sections Calculation by Program MORSE
International Nuclear Information System (INIS)
1980-01-01
1 - Description of problem or function: MORSEC-SP allows one to utilize a step distribution to describe the angular dependence of the multi- group function in the MORSEC cross section module of the MORSE Monte Carlo code. The step distribution is always non-negative and may be used in the random walk and for making point detector estimators. 2 - Method of solution: MORSEC-SP utilizes a table look up procedure to provide the probability of scattering when making point detector estimates for a given incident energy group and scattering angle. In the random walk, the step distributions are converted to cumulative distributions and an angle of scatter is selected from the cumulative distributions. Step distributions are obtained from calculation using the converted moments from the given Legendre coefficients of the scattering distributions. 3 - Restrictions on the complexity of the problem: Additional coding to the MORSEC module is variable dimensional and fully incorporated into blank common
Directory of Open Access Journals (Sweden)
Sébastien Boyas
Full Text Available The purpose of this study was to investigate the influence of fatiguing exercise intensity on the nature and extent of fatigue-induced changes in neuromuscular function and postural stability in quiet standing. We also explored the contribution of selected neuromuscular mechanisms involved in force production to postural stability impairment observed following fatigue using an approach based on multivariate regressions. Eighteen young subjects performed 30-s postural trials on one leg with their eyes closed. Postural trials were performed before and after fatiguing exercises of different intensities: 25, 50 and 75% of maximal isometric plantarflexor torque. Fatiguing exercises consisted of sustaining a plantarflexor isometric contraction at the target intensity until task failure. Maximal isometric plantarflexor torque, electromyographic activity of plantarflexor and dorsiflexor muscles, activation level (twitch interpolation technique and twitch contractile properties of plantarflexors were used to characterize neuromuscular function. The 25% exercise was associated with greater central fatigue whereas the 50 and 75% exercises involved mostly peripheral fatigue. However, all fatiguing exercises induced similar alterations in postural stability, which was unexpected considering previous literature. Stepwise multiple regression analyses showed that fatigue-related changes in selected parameters related to neuromuscular function could explain more than half (0.51≤R(2≤0.82 of the changes in postural variables for the 25% exercise. On the other hand, regression models were less predictive (0.17≤R(2≤0.73 for the 50 and 75% exercises. This study suggests that fatiguing exercise intensity does not influence the extent of postural stability impairment, but does influence the type of fatigue induced and the neuromuscular function predictors explaining changes in postural variables.
Abney, Drew H; Paxton, Alexandra; Dale, Rick; Kello, Christopher T
2015-11-01
Successful interaction requires complex coordination of body movements. Previous research has suggested a functional role for coordination and especially synchronization (i.e., time-locked movement across individuals) in different types of human interaction contexts. Although such coordination has been shown to be nearly ubiquitous in human interaction, less is known about its function. One proposal is that synchrony supports and facilitates communication (Topics Cogn Sci 1:305-319, 2009). However, questions still remain about what the properties of coordination for optimizing communication might look like. In the present study, dyads worked together to construct towers from uncooked spaghetti and marshmallows. Using cross-recurrence quantification analysis, we found that dyads with loosely coupled gross body movements performed better, supporting recent work suggesting that simple synchrony may not be the key to effective performance (Riley et al. 2011). We also found evidence that leader-follower dynamics-when sensitive to the specific role structure of the interaction-impact task performance. We discuss our results with respect to the functional role of coordination in human interaction.
The brain network reflecting bodily self-consciousness: a functional connectivity study
Ionta, Silvio; Martuzzi, Roberto; Salomon, Roy
2014-01-01
Several brain regions are important for processing self-location and first-person perspective, two important aspects of bodily self-consciousness. However, the interplay between these regions has not been clarified. In addition, while self-location and first-person perspective in healthy subjects are associated with bilateral activity in temporoparietal junction (TPJ), disturbed self-location and first-person perspective result from damage of only the right TPJ. Identifying the involved brain network and understanding the role of hemispheric specializations in encoding self-location and first-person perspective, will provide important information on system-level interactions neurally mediating bodily self-consciousness. Here, we used functional connectivity and showed that right and left TPJ are bilaterally connected to supplementary motor area, ventral premotor cortex, insula, intraparietal sulcus and occipitotemporal cortex. Furthermore, the functional connectivity between right TPJ and right insula had the highest selectivity for changes in self-location and first-person perspective. Finally, functional connectivity revealed hemispheric differences showing that self-location and first-person perspective modulated the connectivity between right TPJ, right posterior insula, and right supplementary motor area, and between left TPJ and right anterior insula. The present data extend previous evidence on healthy populations and clinical observations in neurological deficits, supporting a bilateral, but right-hemispheric dominant, network for bodily self-consciousness. PMID:24396007
Directory of Open Access Journals (Sweden)
Vedenyapin Aleksandr Dmitrievich
2015-11-01
Full Text Available This paper is the construction of the distribution function using the Bernoulli scheme, and is also designed to correct some of the mistakes that were made in the article [2]. Namely, a function built in [2] need not be monotonous, and some formulas need to be adjusted. The idea of building as well as in [2], is based on the model of Cox-Ross-Rubinstein "binary market". The essence of the model was to divide time into N steps, and assuming that the price of an asset at each step can move either up to a certain value with probability p, or down also by some certain value with probability q = 1 - p. Prices in step N can take only a finite number of values. "Success" or "failure" was the changing price for some fixed value in the model of Cox-Ross-Rubinstein. Here as a "success" or "failure" at every step we consider the affiliation of changing the index value to the section [r, S] either to the interval [I, r. Further a function P(r was introduced, which at any step gives us the probability of "success". The maximum index value increase for the all period of time [T, 2T] will be equal nS, and the maximum possible reduction will be equal nI. Then let x ∈ [nI, nS]. This segment will reflect every possible total variation that we can get at the end of a period of time [T, 2T]. The further introduced inequality k ≥ (x - nI/(S - I gives us the minimum number of successes that needed for total changing could be in the section [x, nS] if was n - k reductions with the index value to I. Then was introduced the function r(x, kmin which is defined on the interval (nI, nS] and provided us some assurance that the total index changing could be in the section [x, nS] if successful interval is [r(x, kmin, S] and the amount of success is satisfying to our inequality. The probability of k "successes" and n - k "failures" is calculated according to the formula of Bernoulli, where the probability of "success" is determined by the function P(r, and r is determined
Martins, J H C; Santos, N C; Figueira, P; Melo, C
2016-11-01
The direct detection of reflected light from exoplanets is an excellent probe for the characterization of their atmospheres. The greatest challenge for this task is the low planet-to-star flux ratio, which even in the most favourable case is of the order of 10 -4 in the optical. This ratio decreases even more for planets in their host's habitable zone, typically lower than 10 -7 . To reach the signal-to-noise level required for such detections, we propose to unleash the power of the Cross Correlation Function in combination with the collecting power of next generation observing facilities. The technique we propose has already yielded positive results by detecting the reflected spectral signature of 51 Pegasi b (see Martins et al. 2015). In this work, we attempted to infer the number of hours required for the detection of several planets in their host's habitable zone using the aforementioned technique from theoretical EELT observations. Our results show that for 5 of the selected planets it should be possible to directly recover their reflected spectral signature.
International Nuclear Information System (INIS)
Boroun, G.R.
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 low 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 F 2 (x,Q 2 ) 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.
Zhang, Liwen; Vander Meer, Lisette; Opmeer, Esther M; Marsman, Jan-Bernard C; Ruhé, Henricus G; Aleman, André
2016-12-01
Disturbances in implicit self-processing have been reported both in psychotic patients with bipolar disorder (BD) and schizophrenia. It remains unclear whether these two psychotic disorders show disturbed functional connectivity during explicit self-reflection, which is associated with social functioning and illness symptoms. Therefore, we investigated functional connectivity during explicit self-reflection in BD with past psychosis and schizophrenia. Twenty-three BD-patients, 17 schizophrenia-patients and 21 health controls (HC) performed a self-reflection task, including the conditions self-reflection, close other-reflection and semantic control. Functional connectivity was investigated with generalized psycho-physiological interaction (gPPI). During self-reflection compared to semantic, BD-patients had decreased connectivity between several cortical-midline structures (CMS) nodes (i.e., anterior cingulate cortex, ventromedial prefrontal cortex), the insula and the head of the caudate while HC showed increased connectivities. Schizophrenia-patients, during close other-reflection compared to semantic, demonstrated reduced ventral-anterior insula-precuneus/posterior cingulate cortex (PCC) functional connectivity, whereas this was increased in HC. There were no differences between BD and schizophrenia during self- and close other-reflection. We propose that decreased functional connectivity between the CMS nodes/insula and head of the caudate in BD-patients may imply a reduced involvement of the motivational system during self-reflection; and the reduced functional connectivity between the ventral-anterior insula and precuneus/PCC during close other-reflection in schizophrenia-patients may subserve difficulties in information integration of autobiographical memory and emotional awareness in relation to close others. These distinctive impaired patterns of functional connectivity in BD and schizophrenia (compared to HC) deserve further investigation to determine their
International Nuclear Information System (INIS)
Khromov, V.V.
1978-01-01
The notion of neutron importance when applied to nuclear reactor statics problems described by time-independent homogeneous equations of neutron transport with provision for normalization of neutron distribution is considered. An equation has been obtained for the function of neutron importance in a conditionally critical reactor with respect to an arbitrary nons linear functional determined for the normalized neutron distribution. Relation between this function and the generalized Green function of the selfconjugated operator of the reactor equation is determined and the formula of small perturbations for the functionals of a conditionally critical reactor is deduced
Neuper, Malte; Ehret, Uwe
2014-05-01
The relation between the measured radar reflectivity factor Z and surface rainfall intensity R - the Z/R relation - is profoundly complex, so that in general one speaks about radar-based quantitative precipitation estimation (QPE) rather than exact measurement. Like in Plato's Allegory of the Cave, what we observe in the end is only the 'shadow' of the true rainfall field through a very small backscatter of an electromagnetic signal emitted by the radar, which we hope has been actually reflected by hydrometeors. The meteorological relevant and valuable Information is gained only indirectly by more or less justified assumptions. One of these assumptions concerns the drop size distribution, through which the rain intensity is finally associated with the measured radar reflectivity factor Z. The real drop size distribution is however subject to large spatial and temporal variability, and consequently so is the true Z/R relation. Better knowledge of the true spatio-temporal Z/R structure therefore has the potential to improve radar-based QPE compared to the common practice of applying a single or a few standard Z/R relations. To this end, we use observations from six laser-optic disdrometers, two vertically pointing micro rain radars, 205 rain gauges, one rawindsonde station and two C-band Doppler radars installed or operated in and near the Attert catchment (Luxembourg). The C-band radars and the rawindsonde station are operated by the Belgian and German Weather Services, the rain gauge data was partly provided by the French, Dutch, Belgian, German Weather Services and the Ministry of Agriculture of Luxembourg and the other equipment was installed as part of the interdisciplinary DFG research project CAOS (Catchment as Organized Systems). With the various data sets correlation analyzes were executed. In order to get a notion on the different appearance of the reflectivity patterns in the radar image, first of all various simple distribution indices (for example the
Reflective functioning in postpartum depressed women with and without comorbid personality disorder
DEFF Research Database (Denmark)
Cordes, Katharina; Smith-Nielsen, Johanne; Tharner, Anne
2017-01-01
, and thus maternal psychopathology after birth, such as postpartum depression (PPD) and Personality Disorder (PD), may not only affect the mother’s socioemotional functioning but also the development of the child. However, little is known about mentalizing abilities of PPD mothers, and mothers with PPD...... and comorbid PD. Therefore, the aim of this study was to evaluate RF in women presenting symptoms of PPD (n = 13), and women with PPD symptoms and comorbid PD (n = 14) compared with a nonclinical group (n = 52). Women were interviewed with the Adult Attachment Interview (AAI) before birth (nonclinical group...
International Nuclear Information System (INIS)
Alger, T.W.
1979-01-01
A new method for determining the particle-size-distribution function of a polydispersion of spherical particles is presented. The inversion technique for the particle-size-distribution function is based upon matching the measured intensity profile of angularly scattered light with a summation of the intensity contributions of a series of appropriately spaced, narrowband, size-distribution functions. A numerical optimization technique is used to determine the strengths of the individual bands that yield the best agreement with the measured scattered-light-intensity profile. Because Mie theory is used, the method is applicable to spherical particles of all sizes. Several numerical examples demonstrate the application of this inversion method
Smith, David V; Clithero, John A; Boltuck, Sarah E; Huettel, Scott A
2014-12-01
According to many studies, the ventromedial prefrontal cortex (VMPFC) encodes the subjective value of disparate rewards on a common scale. Yet, a host of other reward factors-likely represented outside of VMPFC-must be integrated to construct such signals for valuation. Using functional magnetic resonance imaging (fMRI), we tested whether the interactions between posterior VMPFC and functionally connected brain regions predict subjective value. During fMRI scanning, participants rated the attractiveness of unfamiliar faces. We found that activation in dorsal anterior cingulate cortex, anterior VMPFC and caudate increased with higher attractiveness ratings. Using data from a post-scan task in which participants spent money to view attractive faces, we quantified each individual's subjective value for attractiveness. We found that connectivity between posterior VMPFC and regions frequently modulated by social information-including the temporal-parietal junction (TPJ) and middle temporal gyrus-was correlated with individual differences in subjective value. Crucially, these additional regions explained unique variation in subjective value beyond that extracted from value regions alone. These findings indicate not only that posterior VMPFC interacts with additional brain regions during valuation, but also that these additional regions carry information employed to construct the subjective value for social reward. © The Author (2014). Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.
[Salt, renal function and high blood pressure--reflections on a current issue].
Aurell, Mattias
2002-11-21
The role of salt intake for blood pressure control has been discussed for a long time. A brief review is given of some pertinent physiological facts to explain this relationship and evolutionary aspects of renal function are emphasized. Salt intake is very high in the modern society, often as high as 15 g sodium chloride per 24 hours while 3-6 g may be more than enough to maintain an adequate salt balance. If the kidneys cannot cope with this severe sodium overload, blood pressure will rise. Therefore, the kidneys' ability to excrete sodium is a key factor and the salt excretion capacity is the kidneys' major barostatic function. As barostats, the kidneys control the blood pressure by ultimately determining the sodium excretion. Reducing sodium intake is, however, difficult as more than 50% of the intake is contained in the food we buy such as bread, sausages, canned food, chips and fast-food. Food products should therefore be "salt declared", but information on this aspect is generally lacking. If the population's salt intake could be reduced by 50%, the prevalence of hypertension will be much reduced, perhaps also by as much as 50%. The cost to society for treating hypertension would be reduced accordingly. Salt intake is also an important aspect of the overweight problem among today's youth. Salt and overweight impose great health risks later in life. Preventive measures in this area must be given high priority in future health care work.
Directory of Open Access Journals (Sweden)
Alejandra Zucchi
2007-12-01
Full Text Available El objetivo general de este trabajo es presentar el concepto de Funcionamiento Reflexivo (FR y su relación con el Funcionamiento Reflexivo Materno (FRM a partir de la aplicación de la Entrevista de Desarrollo Parental (PDI-RII, A Slade et. al. 2005 y su evaluación a través de la Escala de Funcionamiento Reflexivo (Fonagy et al. 1998. Dicho instrumento esta siendo aplicado en un estudio de seguimiento que relaciona la regulación afectiva diádica a los 6 meses del bebé (estudiada en el Proyecto UBACyT P803 y el Funcionamiento Reflexivo Materno en la misma muestra a los 36-42 meses de edad del niño (UBACyT P806. El FR puede definirse como la capacidad de percibir y comprenderse a símismo y a los otros en términos de estados mentales. El FRM es la capacidad materna para sostener en la mente la noción de que el propio hijo es un sujeto que posee sus propios sentimientos, deseos e intenciones.The aim of this paper is to introduce the concepts of Reflective Functioning (RF and Maternal Reflective Functioning (MRF as they are explored by the PDI R-II instrument (Parental Developmental Interview. PDI-R II is being used in a follow up research project with mother- infant dyads whose children are currently 36-42 months old (UBACyT P806. This study relates MRF to Affect Regulation (Studied in a first stage when infants were 6 months years old, UBACyT P803. RF refers to the capacity to reflect on internal experience; to know, imagine, and represent inner life and own mental states and to recognize and represent those same mental states in others. MRF refers to the mother's capacity to hold the child's mental states in her mind.
The disposition index does not reflect β-cell function in IGT subjects treated with pioglitazone.
DeFronzo, Ralph A; Tripathy, Devjit; Abdul-Ghani, Muhammad; Musi, Nicolas; Gastaldelli, Amalia
2014-10-01
The insulin secretion/insulin resistance (IR) (disposition) index (ΔI/ΔG ÷ IR, where Δ is change from baseline, I is insulin, and G is glucose) is commonly used as a measure of β-cell function. This relationship is curvilinear and becomes linear when log transformed. ΔI is determined by 2 variables: insulin secretion rate (ISR) and metabolic clearance of insulin. We postulated that the characteristic curvilinear relationship would be lost if Δ plasma C-peptide (ΔCP) (instead of Δ plasma insulin) was plotted against insulin sensitivity. A total of 441 individuals with impaired glucose tolerance (IGT) from ACT NOW received an oral glucose tolerance test and were randomized to pioglitazone or placebo for 2.4 years. Pioglitazone reduced IGT conversion to diabetes by 72% (P < .0001). ΔI/ΔG vs the Matsuda index of insulin sensitivity showed the characteristic curvilinear relationship. However, when ΔCP/ΔG or ΔISR/ΔG was plotted against the Matsuda index, the curvilinear relationship was completely lost. This discordance was explained by 2 distinct physiologic effects that altered plasma insulin response in opposite directions: 1) increased ISR and 2) augmented metabolic clearance of insulin. The net result was a decline in the plasma insulin response to hyperglycemia during the oral glucose tolerance test. These findings demonstrate a physiologic control mechanism wherein the increase in ISR ensures adequate insulin delivery into the portal circulation to suppress hepatic glucose production while delivering a reduced but sufficient amount of insulin to peripheral tissues to maintain the pioglitazone-mediated improvement in insulin sensitivity without excessive hyperinsulinemia. These results demonstrate the validity of the disposition index when relating the plasma insulin response to insulin sensitivity but underscore the pitfall of this index when drawing conclusions about β-cell function, because insulin secretion declined despite an increase in the
International Nuclear Information System (INIS)
Seo, Sang-Hun; In, Jung-Hwan; Chang, Hong-Young
2005-01-01
The temporal behaviour of the electron energy distribution function (EEDF) and the plasma parameters such as electron density, electron temperature and plasma and floating potentials in a mid-frequency pulsed dc magnetron plasma are investigated using time-resolved probe measurements. A negative-voltage dc pulse with an average power of 160 W during the pulse-on period, a repetition frequency of 20 kHz and a duty cycle of 50% is applied to the cathode of a planar unbalanced magnetron discharge with a grounded substrate. The measured electron energy distribution is found to exhibit a bi-Maxwellian distribution, which can be resolved with the low-energy electron group and the high-energy tail part during the pulse-on period, and a Maxwellian distribution only with low-energy electrons as a consequence of initially rapid decay of the high-energy tail part during the pulse-off period. This characteristic evolution of the EEDF is reflected in the decay characteristics of the electron density and temperature in the afterglow. These parameters exhibit twofold decay represented by two characteristic decay times of an initial fast decay time τ 1 , and a subsequent slower decay time τ 2 in the afterglow when approximated with a bi-exponential function. While the initial fast decay times are of the order of 1 μs (τ T1 ∼ 0.99 μs and τ N1 ∼ 1.5 μs), the slower decay times are of the order of a few tens of microseconds (τ T2 ∼ 7 μs and τ N2 ∼ 40 μs). The temporal evolution of the plasma parameters are qualitatively explained by considering the formation mechanism of the bi-Maxwellian electron distribution function and the electron transports of these electron groups in bulk plasma
A Data-Driven Reflectance Model
Matusik, Wojciech; Pfister, Hanspeter; Brand, Matt; McMillan, Leonard
2003-01-01
We present a generative model for isotropic bidirectional reflectance distribution functions (BRDFs) based on acquired reflectance data. Instead of using analytical reflectance models, we represent each BRDF as a dense set of measurements. This allows us to interpolate and extrapolate in the space of acquired BRDFs to create new BRDFs. We treat each acquired BRDF as a single high-dimensional vector taken from a space of all possible BRDFs. We apply both linear (subspace) and non-linear (manif...
Low-energy ion distribution functions on a magnetically quiet day at geostationary altitude /L = 7/
Singh, N.; Raitt, W. J.; Yasuhara, F.
1982-01-01
Ion energy and pitch angle distribution functions are examined for a magnetically quiet day using averaged data from ATS 6. For both field-aligned and perpendicular fluxes, the populations have a mixture of characteristic energies, and the distribution functions can be fairly well approximated by Maxwellian distributions over three different energy bands in the range 3-600 eV. Pitch angle distributions varying with local time, and energy distributions are used to compute total ion density. Pitch angle scattering mechanisms responsible for the observed transformation of pitch angle distribution are examined, and it is found that a magnetic noise of a certain power spectral density belonging to the electromagnetic ion cyclotron mode near the ion cyclotron frequency can be effective in trapping the field aligned fluxes by pitch angle scattering.
International Nuclear Information System (INIS)
Khalid, S.; Alam, A.
2016-01-01
Collaborative Virtual Environments (CVEs) falls under Virtual Reality (VR) where two or more users manipulate objects collaboratively. In this paper we have made some experiments to make assembly from constituents parts scattered in Virtual Environment (VE) based on task distribution model using assistance functions for checking and enhancing user performance. The CVEs subjects setting on distinct connected machines via local area network. In this perspective, we consider the effects of assistance function with oral communication on collaboration, co-presence and users performance. Twenty subjects performed collaboratively an assembly task on static and dynamic based task distribution. We examine the degree of influence of assistance function with oral communications on user's performance based on task distribution model. The results show that assistance functions with oral communication based on task distribution model not only increase user performance but also enhance the sense of copresence and awareness. (author)
On the spherical harmonic expansion of the neutron angular distribution function
Energy Technology Data Exchange (ETDEWEB)
Depken, Sven
1959-03-15
The neutron (one-velocity) angular distribution function is expanded in terms of spherical harmonic tensors. The solution to the equations of the moments is given explicitly and the result is applied to the plane, spherical and cylinder symmetrical cases.
New statistical function for the angular distribution of evaporation residues produced by heavy ions
International Nuclear Information System (INIS)
Rigol, J.
1994-01-01
A new statistical function has been found for modelling the angular distribution of evaporation residues produced by heavy ions. Experimental results are compared with the calculated ones. 11 refs.; 4 figs. (author)
Model etch profiles for ion energy distribution functions in an inductively coupled plasma reactor
International Nuclear Information System (INIS)
Chen, W.; Abraham-Shrauner, B.; Woodworth, J.R.
1999-01-01
Rectangular trench profiles are modeled with analytic etch rates determined from measured ion distribution functions. The pattern transfer step for this plasma etch is for trilayer lithography. Argon and chlorine angular ion energy distribution functions measured by a spherical collector ring analyzer are fit to a sum of drifting Maxwellian velocity distribution functions with anisotropic temperatures. The fit of the model ion distribution functions by a simulated annealing optimization procedure converges adequately for only two drifting Maxwellians. The etch rates are proportional to analytic expressions for the ion energy flux. Numerical computation of the etch profiles by integration of the characteristic equations for profile points and connection of the profiles points is efficient. copyright 1999 American Vacuum Society
On the spherical harmonic expansion of the neutron angular distribution function
International Nuclear Information System (INIS)
Depken, Sven
1959-03-01
The neutron (one-velocity) angular distribution function is expanded in terms of spherical harmonic tensors. The solution to the equations of the moments is given explicitly and the result is applied to the plane, spherical and cylinder symmetrical cases
A radial distribution function-based open boundary force model for multi-centered molecules
Neumann, Philipp; Eckhardt, Wolfgang; Bungartz, Hans-Joachim
2014-01-01
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
International Nuclear Information System (INIS)
Stubblefield, F.W.
1976-01-01
A scheme for managing resources required for transaction processing in the common node of a distributed function computer system has been given. The scheme has been found to be satisfactory for all common node services provided so far
A mathematical model of functioning of channels of distribution of freight traffic
Shramenko, N.
2006-01-01
The mathematical model of functioning of channels of distribution of freight traffics is developed at international transportations which allows to optimize technological parameters of separate parts and to minimize expenses along the logistical chain.
Ion thermal conductivity and ion distribution function in the banana regime
International Nuclear Information System (INIS)
Taguchi, Masayoshi
1988-01-01
A method for calculating the ion thermal conductivity and the ion distribution function in the banana regime is formulated for an axisymmetric toroidal plasma of arbitrary aspect ratio. A simple expression for this conductivity is also derived. (author)
International Nuclear Information System (INIS)
Fukumasa, O.; Itatani, R.
1978-01-01
The change of the electron beam distribution function due to the wave excited by the beam density modulation is observed, in relation to the suppression of electron waves in a beam-plasma system. (Auth.)
Parton distribution function for quarks in an s-channel approach
Hautmann, F
2007-01-01
We use an s-channel picture of hard hadronic collisions to investigate the parton distribution function for quarks at small momentum fraction x, which corresponds to very high energy scattering. We study the renormalized quark distribution at one loop in this approach. In the high-energy picture, the quark distribution function is expressed in terms of a Wilson-line correlator that represents the cross section for a color dipole to scatter from the proton. We model this Wilson-line correlator in a saturation model. We relate this representation of the quark distribution function to the corresponding representation of the structure function F_T(x,Q^2) for deeply inelastic scattering.
Bayesian extraction of the parton distribution amplitude from the Bethe-Salpeter wave function
Gao, Fei; Chang, Lei; Liu, Yu-xin
2017-07-01
We propose a new numerical method to compute the parton distribution amplitude (PDA) from the Euclidean Bethe-Salpeter wave function. The essential step is to extract the weight function in the Nakanishi representation of the Bethe-Salpeter wave function in Euclidean space, which is an ill-posed inversion problem, via the maximum entropy method (MEM). The Nakanishi weight function as well as the corresponding light-front parton distribution amplitude (PDA) can be well determined. We confirm prior work on PDA computations, which was based on different methods.
Bayesian extraction of the parton distribution amplitude from the Bethe–Salpeter wave function
Directory of Open Access Journals (Sweden)
Fei Gao
2017-07-01
Full Text Available We propose a new numerical method to compute the parton distribution amplitude (PDA from the Euclidean Bethe–Salpeter wave function. The essential step is to extract the weight function in the Nakanishi representation of the Bethe–Salpeter wave function in Euclidean space, which is an ill-posed inversion problem, via the maximum entropy method (MEM. The Nakanishi weight function as well as the corresponding light-front parton distribution amplitude (PDA can be well determined. We confirm prior work on PDA computations, which was based on different methods.
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.
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...
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.
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. Estimates...
Bounds for the probability distribution function of the linear ACD process
Fernandes, Marcelo
2003-01-01
Rio de Janeiro This paper derives both lower and upper bounds for the probability distribution function of stationary ACD(p, q) processes. For the purpose of illustration, I specialize the results to the main parent distributions in duration analysis. Simulations show that the lower bound is much tighter than the upper bound.
Equivalence of functional limit theorems for stationary point processes and their Palm distributions
Nieuwenhuis, G.
1989-01-01
Let P be the distribution of a stationary point process on the real line and let P0 be its Palm distribution. In this paper we consider two types of functional limit theorems, those in terms of the number of points of the point process in (0, t] and those in terms of the location of the nth point
Reflecting reflection in supervision
DEFF Research Database (Denmark)
Lystbæk, Christian Tang
associated with reflection and an exploration of alternative conceptions that view reflection within the context of settings which have a more group- and team-based orientation. Drawing on an action research project on health care supervision, the paper questions whether we should reject earlier views...... of reflection, rehabilitate them in order to capture broader connotations or move to new ways of regarding reflection that are more in keeping with not only reflective but also emotive, normative and formative views on supervision. The paper presents a critical perspective on supervision that challenge...... the current reflective paradigm I supervision and relate this to emotive, normative and formative views supervision. The paper is relevant for Nordic educational research into the supervision and guidance...
Subhi, Hikmat; Latham, Keziah; Myint, Joy; Crossland, Michael
2017-11-20
To develop an appropriate method of assessing visual field (VF) loss which reflects its functional consequences, this study aims to determine which method(s) of assessing VF best reflect mobility difficulty. This cross-sectional observational study took place within a single primary care setting. Participants attended a single session at a University Eye Clinic, Cambridge, UK, with data collected by a single researcher (HS), a qualified optometrist. 50 adult participants with peripheral field impairment were recruited for this study. Individuals with conditions not primarily affecting peripheral visual function, such as macular degeneration, were excluded from the study. Participants undertook three custom and one standard binocular VF tests assessing VF to 60°, and also integrated monocular threshold 24-2 visual fields (IVF). Primary VF outcomes were average mean threshold, percentage of stimuli seen and VF area. VF outcomes were compared with self-reported mobility function assessed with the Independent Mobility Questionnaire, and time taken and patient acceptability were also considered. Receiver operating characteristic (ROC) curves determined which tests best predicted difficulty with mobility tasks. Greater VF loss was associated with greater self-reported mobility difficulty with all field paradigms (R 2 0.38-0.48, all Pmobility tasks in ROC analysis. Mean duration of the tests ranged from 1 min 26 s (±9 s) for kinetic assessment to 9 min 23 s (±24 s) for IVF. The binocular VF tests extending to 60° eccentricity all relate similarly to self-reported mobility function, and slightly better than integrated monocular VFs. A kinetic assessment of VF area is quicker than and as effective at predicting mobility function as static threshold assessment. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.
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.
Relaxation of the vibrational distribution function in N2 time varying discharges
International Nuclear Information System (INIS)
Capitelli, M.; Gorse, C.; Ricard, A.
1981-01-01
Relaxation of the electron and vibrational distribution functions have been calculated in function of residence time in nitrogen electrical discharges and post-discharges. In the discharge the vibrational temperature get bigger with the residence time for t -2 s. In the post-discharge the vibrational distribution is evolving in such a manner that the high levels are overpopulated as the low vibrational level population is dropping
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.
Dominant role of many-body effects on the carrier distribution function of quantum dot lasers
Peyvast, Negin; Zhou, Kejia; Hogg, Richard A.; Childs, David T. D.
2016-03-01
The effects of free-carrier-induced shift and broadening on the carrier distribution function are studied considering different extreme cases for carrier statistics (Fermi-Dirac and random carrier distributions) as well as quantum dot (QD) ensemble inhomogeneity and state separation using a Monte Carlo model. Using this model, we show that the dominant factor determining the carrier distribution function is the free carrier effects and not the choice of carrier statistics. By using empirical values of the free-carrier-induced shift and broadening, good agreement is obtained with experimental data of QD materials obtained under electrical injection for both extreme cases of carrier statistics.
Abdulsttar, Marwah M.; Al-Rubaiee, A. A.; Ali, Abdul Halim Kh.
2016-01-01
Cherenkov light lateral distribution function (CLLDF) simulation was fulfilled using CORSIKA code for configurations of Tunka EAS array of different zenith angles. The parameterization of the CLLDF was carried out as a function of the distance from the shower core in extensive air showers (EAS) and zenith angle on the basis of the CORSIKA simulation of primary proton around the knee region with the energy 3.10^15 eV at different zenith angles. The parameterized CLLDF is verified in comparison...
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.
Kwon, Yong-Soo; Cho, Young-Nan; Kim, Moon-Ju; Jin, Hye-Mi; Jung, Hyun-Ju; Kang, Jeong-Hwa; Park, Ki-Jeong; Kim, Tae-Jong; Kee, Hae Jin; Kim, Nacksung; Kee, Seung-Jung; Park, Yong-Wook
2015-05-01
Mucosal-associated invariant T (MAIT) cells contribute to protection against certain microorganism infections. The aims of this study were to examine the levels of MAIT cells in pulmonary tuberculosis (TB) and nontuberculous mycobacteria (NTM) lung disease patients, to evaluate the clinical relevance of MAIT cell levels, and to investigate the functions of MAIT cells. Patients with pulmonary TB (n = 35), NTM (n = 29), and healthy controls (n = 75) were enrolled in the study. MAIT cell levels and functions were measured by flow cytometry. Circluating MAIT cell levels were found to be reduced in TB and NTM patients. MAIT cell deficiency reflects a variety of clinical conditions. In particular, MAIT cell numbers were significantly correlated with sputum AFB positivity, extent of disease, hemoglobin levels, lymphocyte counts, CRP and ESR levels. MAIT cells in TB patients failed to produce interferon-γ irrespective of the mode of stimulation, whereas NTM patients displayed a defect in MR1-dependent signaling pathway. Notably, an elevated expression of programmed death-1 was also associated with MAIT cell deficiency in TB. This study shows that MAIT cells are numerically and functionally deficient in TB and NTM patients and these deficiencies could contribute to immune system dysreguation in mycobacterial infection. Copyright © 2015 Elsevier Ltd. All rights reserved.
Directory of Open Access Journals (Sweden)
Motoyasu Honma
Full Text Available It has been speculated that humans have an inherent ability to overcome sleepiness that counteracts homeostatic sleep pressure. However, it remains unclear which cortical substrate activities are involved in the ability to overcome sleepiness during the execution of cognitive tasks. Here we sought to confirm that this ability to overcome sleepiness in task execution improves performance on cognitive tasks, showing activation of neural substrates in the frontal cortex, by using a modified n-back (2- and 0-back working memory task and functional near-infrared spectroscopy. The change in alertness was just correlated with performances on the 2-back task. Activity in the right prefrontal cortex changed depending on alertness changes on the 2- and 0-back tasks independently, which indicates that activity in this region clearly reflects the ability to overcome sleepiness; it may contribute to the function of providing sufficient activity to meet the task load demands. This study reveals characteristics of the ability to overcome sleepiness during the n-back working memory task which goes beyond the attention-control function traditionally proposed.
Determination of the radial distribution function with the tomographic atom probe
International Nuclear Information System (INIS)
Heinrich, A.; Al-Kassab, T.
2004-01-01
Full text: An algorithm for the determination of the radial distribution function (RDF) and the partial radial distribution function from tomographic atom probe data is introduced and some examples for its application are discussed. Homogeneous distribution of atoms can easily be determined from measured data. Using our algorithm, the lattice of simple cubic structures may be estimated solely from TAP data. The results for bcc and fcc alloys and metals will be presented. By evaluating the vicinity of each atom, information about order phenomena in multi component alloy can be retrieved including short range order. The advantage of determining the (partial) radial distribution functions for any sample with our algorithm is that all data can be derived by one single experiment whereas all other methods of determining a pRDF require one experiment for each pRDF. (author)
Rossi, R.; Hendrix, E.M.T.
2014-01-01
We discuss the problem of computing optimal linearisation parameters for the first order loss function of a family of arbitrarily distributed random variable. We demonstrate that, in contrast to the problem in which parameters must be determined for the loss function of a single random variable,
Wigner distribution function and its application to first-order optics
Bastiaans, M.J.
1979-01-01
The Wigner distribution function of optical signals and systems has been introduced. The concept of such functions is not restricted to deterministic signals, but can be applied to partially coherent light as well. Although derived from Fourier optics, the description of signals and systems by means
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...
nth-Nearest neighbour distribution functions of a binary fluid mixture ...
Indian Academy of Sciences (India)
Administrator
for ob- taining the NND functions for single component flu- ids, to binary fluid mixtures. The MD simulation and computation details are presented in section 4. Results are elaborated in section 5 and conclusions are provided in section 6. 2. n-Particle distribution function. Considering a binary system of Nα and Nβ particles.
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.
Convery, P. D.; Schriver, D.; Ashour-Abdalla, M.; Richard, R. L.
2002-01-01
Nongyrotropic plasma distribution functions can be formed in regions of space where guiding center motion breaks down as a result of strongly curved and weak ambient magnetic fields. Such are the conditions near the current sheet in the Earth's middle and distant magnetotail, where observations of nongyrotropic ion distributions have been made. Here a systematic parameter study of nongyrotropic proton distributions using electromagnetic hybrid simulations is made. We model the observed nongyrotropic distributions by removing a number of arc length segments from a cold ring distribution and find significant differences with the results of simulations that initially have a gyrotropic ring distribution. Model nongyrotropic distributions with initially small perpendicular thermalization produce growing fluctuations that diffuse the ions into a stable Maxwellian-like distribution within a few proton gyro periods. The growing waves produced by nongyrotropic distributions are similar to the electromagnetic proton cyclotron waves produced by a gyrotropic proton ring distribution in that they propagate parallel to the background magnetic field and occur at frequencies on the order of the proton gyrofrequency, The maximum energy of the fluctuating magnetic field increases as the initial proton distribution is made more nongyrotropic, that is, more highly bunched in perpendicular velocity space. This increase can be as much as twice the energy produced in the gyrotropic case.
International Nuclear Information System (INIS)
Arslanbekov, R.R.; Kolokolov, N.B.; Kudryavtsev, A.A.; Khromov, N.A.
1991-01-01
Gorbunov et al. have developed a kinetic theory of the electron current drawn by a probe, which substantially extends the region of applicability of the probe method for determining the electron energy distribution function, enabling probes to be used for intermediate and high pressures (up to p ≤ 0.5 atm for monatomic gases). They showed that for λ var-epsilon >> a + d (where a is the probe radius, d is the sheath thickness, and λ var-epsilon is the electron energy relaxation length) the current density j e (V) drawn by the probe is related to the unperturbed distribution function by an integral equation involving the distribution function. The kernal of the integral equation can be written as a function of the diffusion parameter. In the present paper the method of quadrature sums is employed in order to obtain the electron energy distribution function from probe characteristics at intermediate and high pressures. This technique enables them to recover the distribution function from the integral equation when the diffusion parameter has an arbitrary energy dependence ψ 0 (var-epsilon) in any given energy range. The effectiveness of the method is demonstrated by application to both model problems and experimental data
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...
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.
Dynamical behavior connection of the gluon distribution and the proton structure function at small x
International Nuclear Information System (INIS)
Boroun, G.R.
2014-01-01
We make a critical study of the relationship between the singlet structure function F 2 S and the gluon distribution G(x,Q 2 ) proposed in the past two decades, which is frequently used to extract the gluon distribution from the proton structure function. We show that a simple relation is not generally valid in the simplest state. We complete this relation by using a Laplace transform method and hard-pomeron behavior at LO and NLO at small x. Our study shows that this relation is dependent on the splitting functions and initial conditions at Q 2 =Q 2 0 and running coupling constant at NLO. The resulting analytic expression allows us to predict the proton structure function with respect to the gluon distributions and to compare the results with H1 data and a QCD analysis fit. Comparisons with other results are made and predictions for the proposed best approach are also provided. (orig.)
Peculiarities of the momentum distribution functions of strongly correlated charged fermions
Larkin, A. S.; Filinov, V. S.; Fortov, V. E.
2018-01-01
New numerical version of the Wigner approach to quantum thermodynamics of strongly coupled systems of particles has been developed for extreme conditions, when analytical approximations based on different kinds of perturbation theories cannot be applied. An explicit analytical expression of the Wigner function has been obtained in linear and harmonic approximations. Fermi statistical effects are accounted for by effective pair pseudopotential depending on coordinates, momenta and degeneracy parameter of particles and taking into account Pauli blocking of fermions. A new quantum Monte-Carlo method for calculations of average values of arbitrary quantum operators has been developed. Calculations of the momentum distribution functions and the pair correlation functions of degenerate ideal Fermi gas have been carried out for testing the developed approach. Comparison of the obtained momentum distribution functions of strongly correlated Coulomb systems with the Maxwell-Boltzmann and the Fermi distributions shows the significant influence of interparticle interaction both at small momenta and in high energy quantum ‘tails’.
International Nuclear Information System (INIS)
Jiang Haimei; Liu Xinjian; Qiu Lin; Li Fengju
2014-01-01
Based on the meteorological data from weather stations around several domestic nuclear power plants, the statistical results of extreme minimum temperatures, minimum. central pressures of tropical cyclones and some other parameters are calculated using extreme value I distribution function (EV- I), generalized extreme value distribution function (GEV) and generalized Pareto distribution function (GP), respectively. The influence of different distribution functions and parameter solution methods on the statistical results of extreme values is investigated. Results indicate that generalized extreme value function has better applicability than the other two distribution functions in the determination of standard meteorological parameters for nuclear power plants. (authors)
Analysis of calculating methods for failure distribution function based on maximal entropy principle
International Nuclear Information System (INIS)
Guo Chunying; Lin Yuangen; Jiang Meng; Wu Changli
2009-01-01
The computation of invalidation distribution functions of electronic devices when exposed in gamma rays is discussed here. First, the possible devices failure distribution models are determined through the tests of statistical hypotheses using the test data. The results show that: the devices' failure distribution can obey multi-distributions when the test data is few. In order to decide the optimum failure distribution model, the maximal entropy principle is used and the elementary failure models are determined. Then, the Bootstrap estimation method is used to simulate the intervals estimation of the mean and the standard deviation. On the basis of this, the maximal entropy principle is used again and the simulated annealing method is applied to find the optimum values of the mean and the standard deviation. Accordingly, the electronic devices' optimum failure distributions are finally determined and the survival probabilities are calculated. (authors)
Wigner distribution function of Hermite-cosine-Gaussian beams through an apertured optical system.
Sun, Dong; Zhao, Daomu
2005-08-01
By introducing the hard-aperture function into a finite sum of complex Gaussian functions, the approximate analytical expressions of the Wigner distribution function for Hermite-cosine-Gaussian beams passing through an apertured paraxial ABCD optical system are obtained. The analytical results are compared with the numerically integrated ones, and the absolute errors are also given. It is shown that the analytical results are proper and that the calculation speed for them is much faster than for the numerical results.
Hazenberg, Pieter; Leijnse, Hidde; Uijlenhoet, Remko
2014-11-01
Between 25 and 27 August 2010 a long-duration mesoscale convective system was observed above the Netherlands, locally giving rise to rainfall accumulations exceeding 150 mm. Correctly measuring the amount of precipitation during such an extreme event is important, both from a hydrological and meteorological perspective. Unfortunately, the operational weather radar measurements were affected by multiple sources of error and only 30% of the precipitation observed by rain gauges was estimated. Such an underestimation of heavy rainfall, albeit generally less strong than in this extreme case, is typical for operational weather radar in The Netherlands. In general weather radar measurement errors can be subdivided into two groups: (1) errors affecting the volumetric reflectivity measurements (e.g. ground clutter, radar calibration, vertical profile of reflectivity) and (2) errors resulting from variations in the raindrop size distribution that in turn result in incorrect rainfall intensity and attenuation estimates from observed reflectivity measurements. A stepwise procedure to correct for the first group of errors leads to large improvements in the quality of the estimated precipitation, increasing the radar rainfall accumulations to about 65% of those observed by gauges. To correct for the second group of errors, a coherent method is presented linking the parameters of the radar reflectivity-rain rate (Z - R) and radar reflectivity-specific attenuation (Z - k) relationships to the normalized drop size distribution (DSD). Two different procedures were applied. First, normalized DSD parameters for the whole event and for each precipitation type separately (convective, stratiform and undefined) were obtained using local disdrometer observations. Second, 10,000 randomly generated plausible normalized drop size distributions were used for rainfall estimation, to evaluate whether this Monte Carlo method would improve the quality of weather radar rainfall products. Using the
Geometrical approach to the distribution of the zeros for the Husimi function
International Nuclear Information System (INIS)
Toscano, Fabricio; Almeida, M. Ozorio de
1999-03-01
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 structure that the Husimi function inherits from the Wigner function, down to very shallow valleys, where lie the Husimi zeros. This explanation for the distribution of zeros along curves relies on the geometry of the classical torus, rather the complex analytic properties of the WKB method in the Bargmann representation. We evaluate the zeros for several examples. (author)
Analytical evaluation of the plasma dispersion function for a Fermi Dirac distribution
International Nuclear Information System (INIS)
Mamedov, B.A.
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. (physics of gases, plasmas, and electric discharges)
International Nuclear Information System (INIS)
Muldrew, D.B.
1986-01-01
The time variation of the electron temperature profile in the ionosphere following turn-on of a powerful 1-s HF pulse is determined numerically from the energy balance equation. Using this and the equations of motion and continuity for a plasma, the effect of heating and the pondermotive force of a powerful HF wave on the electron density and electric field distributions are determined by numerical simulation. The temperature variation and ponderomotive force modify the density distribution, and this new density distribution, in turn, modifies the electric field distribution of the HF wave. The density deviations grow for a few hundred milliseconds after HF turn-on and then begin to fluctuate in time. At all heights the wave number of the density deviations is approximately twice the wave number of the HF wave. For electric fields near reflection of about 6.0 V/m, the electric field distribution becomes complicated, apparently depending on Bragg scattering of the HF wave from the density deviations. Density impulses propagate away (up and down) from electric field maxima, at the ion thermal velocity, at both turn-on and turn-off of the HF wave
Elias, P. Q.; Jarrige, J.; Cucchetti, E.; Cannat, F.; Packan, D.
2017-09-01
Measuring the full ion velocity distribution function (IVDF) by non-intrusive techniques can improve our understanding of the ionization processes and beam dynamics at work in electric thrusters. In this paper, a Laser-Induced Fluorescence (LIF) tomographic reconstruction technique is applied to the measurement of the IVDF in the plume of a miniature Hall effect thruster. A setup is developed to move the laser axis along two rotation axes around the measurement volume. The fluorescence spectra taken from different viewing angles are combined using a tomographic reconstruction algorithm to build the complete 3D (in phase space) time-averaged distribution function. For the first time, this technique is used in the plume of a miniature Hall effect thruster to measure the full distribution function of the xenon ions. Two examples of reconstructions are provided, in front of the thruster nose-cone and in front of the anode channel. The reconstruction reveals the features of the ion beam, in particular on the thruster axis where a toroidal distribution function is observed. These findings are consistent with the thruster shape and operation. This technique, which can be used with other LIF schemes, could be helpful in revealing the details of the ion production regions and the beam dynamics. Using a more powerful laser source, the current implementation of the technique could be improved to reduce the measurement time and also to reconstruct the temporal evolution of the distribution function.
Probability distribution functions for intermittent scrape-off layer plasma fluctuations
Theodorsen, A.; Garcia, O. E.
2018-03-01
A stochastic model for intermittent fluctuations in the scrape-off layer of magnetically confined plasmas has been constructed based on a super-position of uncorrelated pulses arriving according to a Poisson process. In the most common applications of the model, the pulse amplitudes are assumed exponentially distributed, supported by conditional averaging of large-amplitude fluctuations in experimental measurement data. This basic assumption has two potential limitations. First, statistical analysis of measurement data using conditional averaging only reveals the tail of the amplitude distribution to be exponentially distributed. Second, exponentially distributed amplitudes leads to a positive definite signal which cannot capture fluctuations in for example electric potential and radial velocity. Assuming pulse amplitudes which are not positive definite often make finding a closed form for the probability density function (PDF) difficult, even if the characteristic function remains relatively simple. Thus estimating model parameters requires an approach based on the characteristic function, not the PDF. In this contribution, the effect of changing the amplitude distribution on the moments, PDF and characteristic function of the process is investigated and a parameter estimation method using the empirical characteristic function is presented and tested on synthetically generated data. This proves valuable for describing intermittent fluctuations of all plasma parameters in the boundary region of magnetized plasmas.
International Nuclear Information System (INIS)
Tiilikainen, J; Bosund, V; Mattila, M; Hakkarainen, T; Sormunen, J; Lipsanen, H
2007-01-01
Nonunique solutions of the x-ray reflectivity (XRR) curve fitting problem were studied by modelling layer structures with neural networks and designing a fitness function to handle the nonidealities of measurements. Modelled atomic-layer-deposited aluminium oxide film structures were used in the simulations to calculate XRR curves based on Parratt's formalism. This approach reduced the dimensionality of the parameter space and allowed the use of fitness landscapes in the study of nonunique solutions. Fitness landscapes, where the height in a map represents the fitness value as a function of the process parameters, revealed tracks where the local fitness optima lie. The tracks were projected on the physical parameter space thus allowing the construction of the crosserror equation between weakly determined parameters, i.e. between the mass density and the surface roughness of a layer. The equation gives the minimum error for the other parameters which is a consequence of the nonuniqueness of the solution if noise is present. Furthermore, the existence of a possible unique solution in a certain parameter range was found to be dependent on the layer thickness and the signal-to-noise ratio
Kono, A.; Sato, T.; Shinohara, M.; Mochizuki, K.; Yamada, T.; Uehira, K.; Shimbo, T.; Machida, Y.; Hino, R.; Azuma, R.
2017-12-01
Off the Boso Peninsula, Japan, the Pacific plate (PAC) is subducting westward beneath the Honshu Island Arc (HIA) and the Philippine Sea plate (PHS), while the PHS is subducting northwestward under the HIA. Such tectonic interactions have caused various seismic events such as the Boso Slow Slip Events (SSEs). To better understand these seismic events, it is important to determine the structure under this region. In May 2017, we published 2D P-wave velocity structure under the survey area, and showed geometry of the upper surface of PHS (UPHS) and reflection intensity variation along it. From our result and previous studies, relatively strong reflection from the UPHS can be observed near the main slip area of Boso SSEs, and such reflective area may relate with the Boso SSEs. However, it is still insufficient to link both only from the 2D models and further work is needed to reveal spatial distribution of the strong reflection area. From July to August 2009, we conducted a marine seismic experiment using airgun as source off the east coast of the Boso Peninsula. Airgun was shot along the 4 survey lines, and 27 Ocean Bottom Seismometers (OBSs) were deployed in the survey area. In our presentation, we used 18 OBSs to determine 3D P-wave velocity structure. We estimated 3D velocity structure from airgun data recorded in the OBSs by using the FAST (Zelt and Barton, 1998). Next, we picked the reflection traveltimes likely reflected from the UPHS and applied them to the Traveltime mapping method (Fujie et al. 2006) to estimate spatial locations of the reflectors. As a result, reflections from the UPHS seem to concentrate near the main slip area of the Boso SSEs and an area where the serpentine seamount chain of the Izu-Bonin subduction zone is subducting. Acknowledgement The marine seismic experiment was conducted by R/V Hakuhou-maru of Japan Agency for Marine-Earth Science and Technology, and the OBSs were retrieved by Shincho-maru of Shin-Nihon-Kaiji co. Ltd. (Present
International Nuclear Information System (INIS)
Grendel, M.
1981-01-01
Boundary conditions for distribution functions of quasiparticles scattered by an interface between two crystalline grains are presented. Contrary to former formulations where Maxwell-Boltzmann statistics was considered, the present boundary conditions take into account the quantum statistics (Fermi-Dirac or Bose-Einstein) of quasiparticles. Provided that small deviations only from thermodynamic equilibrium are present, the boundary conditions are linearized, and then their ''renormalization'' is investigated in case of elastic scattering. The final results of the renormalization, which are obtained for a simplified model of an interface, sugo.est that the portion of the Fermi (Bose)-quasiparticles reflected or transmitted specularly is decreased (increased) in comparison with the case of quasiparticles obeying Maxwell-Boltzmann statistics. (author)
International Nuclear Information System (INIS)
Xie, M.; Goh, T.N.; Tang, Y.
2004-01-01
The failure rate function and mean residual life function are two important characteristics in reliability analysis. Although many papers have studied distributions with bathtub-shaped failure rate and their properties, few have focused on the underlying associations between the mean residual life and failure rate function of these distributions, especially with respect to their changing points. It is known that the change point for mean residual life can be much earlier than that of failure rate function. In fact, the failure rate function should be flat for a long period of time for a distribution to be useful in practice. When the difference between the change points is large, the flat portion tends to be longer. This paper investigates the change points and focuses on the difference of the changing points. The exponentiated Weibull, a modified Weibull, and an extended Weibull distribution, all with bathtub-shaped failure rate function will be used. Some other issues related to the flatness of the bathtub curve are discussed
Velocity-space tomography of the fast-ion distribution function
DEFF Research Database (Denmark)
Jacobsen, Asger Schou; Salewski, Mirko; Geiger, Benedikt
2013-01-01
probes certain regions in velocity-space, determined by the geometry of the set-up. Exploiting this, the fast-ion distribution function can be inferred using a velocity-space tomography method. This poster contains a tomography calculated from measured spectra from three different FIDA views at ASDEX......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 view...... Upgrade. The quality of the tomography improves with the number of FIDA views simultaneously measuring the same volume. To investigate the potential benefits of including additional views (up to 18), tomographies are inferred from synthetic spectra calculated from a simulated distribution function...
Differential subcellular distribution of ion channels and the diversity of neuronal function.
Nusser, Zoltan
2012-06-01
Following the astonishing molecular diversity of voltage-gated ion channels that was revealed in the past few decades, the ion channel repertoire expressed by neurons has been implicated as the major factor governing their functional heterogeneity. Although the molecular structure of ion channels is a key determinant of their biophysical properties, their subcellular distribution and densities on the surface of nerve cells are just as important for fulfilling functional requirements. Recent results obtained with high resolution quantitative localization techniques revealed complex, subcellular compartment-specific distribution patterns of distinct ion channels. Here I suggest that within a given neuron type every ion channel has a unique cell surface distribution pattern, with the functional consequence that this dramatically increases the computational power of nerve cells. Copyright © 2011 Elsevier Ltd. All rights reserved.
Kratzer, Markus; Lasnik, Michael; Röhrig, Sören; Teichert, Christian; Deluca, Marco
2018-01-11
Lead zirconate titanate (PZT) is one of the prominent materials used in polycrystalline piezoelectric devices. Since the ferroelectric domain orientation is the most important parameter affecting the electromechanical performance, analyzing the domain orientation distribution is of great importance for the development and understanding of improved piezoceramic devices. Here, vector piezoresponse force microscopy (vector-PFM) has been applied in order to reconstruct the ferroelectric domain orientation distribution function of polished sections of device-ready polycrystalline lead zirconate titanate (PZT) material. A measurement procedure and a computer program based on the software Mathematica have been developed to automatically evaluate the vector-PFM data for reconstructing the domain orientation function. The method is tested on differently in-plane and out-of-plane poled PZT samples, and the results reveal the expected domain patterns and allow determination of the polarization orientation distribution function at high accuracy.
International Nuclear Information System (INIS)
Michael G. Waddell; William J. Domoracki; Tom J. Temples; Jerome Eyer
2001-01-01
The Earth Sciences and Resources Institute, University of South Carolina is conducting a 14 month proof of concept study to determine the location and distribution of subsurface Dense Nonaqueous Phase Liquid (DNAPL) carbon tetrachloride (CCl 4 ) contamination at the 216-Z-9 crib, 200 West area, Department of Energy (DOE) Hanford Site, Washington by use of two-dimensional high resolution seismic reflection surveys and borehole geophysical data. The study makes use of recent advances in seismic reflection amplitude versus offset (AVO) technology to directly detect the presence of subsurface DNAPL. The techniques proposed are a noninvasive means towards site characterization and direct free-phase DNAPL detection. This report covers the results of Task 3 and change of scope of Tasks 4-6. Task 1 contains site evaluation and seismic modeling studies. The site evaluation consists of identifying and collecting preexisting geological and geophysical information regarding subsurface structure and the presence and quantity of DNAPL. The seismic modeling studies were undertaken to determine the likelihood that an AVO response exists and its probable manifestation. Task 2 is the design and acquisition of 2-D seismic reflection data designed to image areas of probable high concentration of DNAPL. Task 3 is the processing and interpretation of the 2-D data. Task 4, 5, and 6 were designing, acquiring, processing, and interpretation of a three dimensional seismic survey (3D) at the Z-9 crib area at 200 west area, Hanford
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.
Taucare-Ríos, A; Nentwig, W; Bizama, G; Bustamante, R O
2018-06-08
The Mediterranean recluse spider, Loxosceles rufescens (Dufour, 1820) (Araneae: Sicariidae) is a cosmopolitan spider that has been introduced in many parts of the world. Its bite can be dangerous to humans. However, the potential distribution of this alien species, which is able to spread fairly quickly with human aid, is completely unknown. Using a combination of global and regional niche models, it is possible to analyse the spread of this species in relation to environmental conditions. This analysis found that the successful spreading of this species varies according to the region invaded. The majority of populations in Asia are stable and show niche conservatism, whereas in North America this spider is expected to be less successful in occupying niches that differ from those in its native region and that do not support its synanthropic way of living. © 2018 The Royal Entomological Society.
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’.
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.
Soot Particle Size Distribution Functions in a Turbulent Non-Premixed Ethylene-Nitrogen Flame
Boyette, Wesley; Chowdhury, Snehaunshu; Roberts, William L.
2017-01-01
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.
Characteristics of ion distribution functions in dipolarizing flux bundles: Event studies
Runov, A.; Angelopoulos, V.; Artemyev, A.; Birn, J.; Pritchett, P. L.; Zhou, X.-Z.
2017-06-01
Taking advantage of multipoint observations from a repeating configuration of the five Time History of Events and Macroscale Interactions during Substorms (THEMIS) probes separated by 1 to 2 Earth radii (RE) along X, Y, and Z in the geocentric solar magnetospheric system (GSM), we study ion distribution functions collected by the probes during three dipolarizing flux bundle (DFB) events observed at geocentric distances 9 energy and twice the thermal energy, although the distribution in the ambient plasma sheet was isotropic. The anisotropic ion distribution in DFBs injected toward the inner magnetosphere may provide the free energy for waves and instabilities, which are important elements of particle energization.
International Nuclear Information System (INIS)
Muhammad Izwan Zariq Mokhtar; Nurul Adyani Ghazali; Muhammad Yazid Nasir; Norhazlina Suhaimi
2016-01-01
Ozone is known as an important secondary pollutant in the atmosphere. The aim of this study is to find the best fit distribution for calculating exceedance and return period of ozone based on suburban areas; Perak (AMS1) and Pulau Pinang (AMS2). Three distributions namely Gamma, Rayleigh and Laplace were used to fit 2 years ozone data (2010 and 2011). The parameters were estimated by using Maximum Likelihood Estimation (MLE) in order to plot probability distribution function (PDF) and cumulative distribution function (CDF). Four performance indicators were used to find the best distribution namely, normalized absolute error (NAE), prediction accuracy (PA), coefficient of determination (R 2 ) and root mean square error (RMSE). The best distribution to represent ozone concentration at both sites in 2010 and 2011 is Gamma distribution with the smallest error measure (NAE and RMSE) and the highest adequacy measure (PA and R 2 ). For the 2010 data, AMS1 was predicted to exceed 0.1 ppm for 2 days in 2011 with a return period of one occurrence. (author)