Density Spectrums from Kinetic Inflations
Hwang, J
1996-01-01
The pole-like accelerated expansion stages purely driven by the coupling between the gravity and the dilaton field without referring to the potential term can be realized in a class of generalized gravity theories. We consider three such scenarios based on the scalar-tensor gravity, the induced gravity and the string theory. Quantum fluctuations during the expansion stages (including more general situations) can be derived in exact analytic forms. Assuming that the pole-like acceleration stage provides a viable inflation scenario in the early universe we derive the generated classical density spectrums. The generated classical density field shows a generic tilted spectrum with $n \\simeq 4$ which differs from the observed spectrum supporting $n \\simeq 1$.
Density fluctuation spectrum in whistler turbulence
Energy Technology Data Exchange (ETDEWEB)
Shaikh, Dastgeer, E-mail: dastgeer.shaikh@uah.ed [Department of Physics and Center for Space Plasma and Aeronomy Research, University of Alabama in Huntsville, Huntsville, Alabama 35899 (United States)
2010-05-31
We develop a nonlinear two-dimensional fluid model of whistler turbulence that includes effect of electron fluid density perturbations. The latter is coupled nonlinearly with wave magnetic field. This coupling leads essentially to finite compressibility effects in whistler turbulence model. We find from our simulations that despite strong compressibility effects, the density fluctuations follow the evolution of the wave magnetic field fluctuations. In a characteristic regime where large scale whistlers are predominant, the coupled density fluctuations are found to follow a Kolmogorov-like phenomenology in the inertial range turbulence. Consequently, the turbulent energy is dominated by the large scale (compared to electron inertial length) eddies and it follows a Kolmogorov-like k{sup -7/3} spectrum, where k is a characteristic wavenumber.
Density Functional Approach Based on Numerically Obtained Bridge Functional
Institute of Scientific and Technical Information of China (English)
ZHOUShi－Qi
2002-01-01
The ornstein-zenike equation is solved with the Rogers-Young approximation for bulk hard sphere fluid and Lennard-Jones fluid for several state points.Then the resulted bulk fluid radial distribution function combined with the test particle method is employed to determine numerically the function relationship of bridge functional as a function of indirect correlation function.It is found that all of the calculated points from different phase space state points for a same type of fluid collapse onto a same smooth curve.Then the numerically obtained curve is used to substitute the analytic expression of the bridge functional as a function of indirect correlation function required in the methodology [J.Chem.Phys,112(2000)8079] to determine the density distribution of non-uniform hard sphere fluid and Lennard-Jones fluid.The good agreement of theoretical predictions with the computer simulation data is obtained.The present numerical procedure incroporates the knowledge of bulk fluid radial distribution function into the constructing of the density functional approximation and makes the original methodology more accurate and more filexible for various interaction potential fluid.
Density Functional Approach Based on Numerically Obtained Bridge Functional
Institute of Scientific and Technical Information of China (English)
ZHOU Shi-Qi
2002-01-01
The Ornstein Zernike equation is solved with the Rogers Young approximation for bulk hard sphere fluidand Lennard-Jones fluid for several state points. Then the resulted bulk fluid radial distribution function combinedwith the test particle method is employed to determine numerically the function relationship of bridge functional as afunction of indirect correlation function. It is found that all of the calculated points from different phase space statepoints for a same type of fluid collapse onto a same smooth curve. Then the numerically obtained curve is used tosubstitute the analytic expression of the bridge functional as a function of indirect correlation function required in themethodology [J. Chem. Phys. 112 (2000) 8079] to deterrnine the density distribution of non-uniform hard spherefluid and Lennard Jones fluid. The good agreement of theoretical predictions with the computer simulation data isobtained. The present numerical procedure incorporates the knowledge of bulk fluid radial distribution function intothe constructing of the density functional approximation and makes the original methodology more accurate and moreflexible for various interaction potential fluid.
Power Spectrum Density of Long-Term MAXI Data
Sugimoto, Juri; Mihara, Tatehiro; Sugizaki, Mutsumi; Serino, Motoko; Kitamoto, Shunji; Sato, Ryousuke; Ueda, Yoshihiro; Ueno, Shiro
Monitor of All-sky X-ray Image (MAXI) on the International Space Station has been observing the X-ray sky since 2009 August 15. It has accumulated the X-ray data for about four years, so far. X-ray objects are usually variable and their variability can be studied by the power spectrum density (PSD) of the X-ray light curves. We applied our method to calculate PSDs of several kinds of objects observed with MAXI. We obtained significant PSDs from 16 Seyfert galaxies. For blackhole binary Cygnus X-1 there was a difference in the shape of PSD between the hard state and the soft state. For high mass X-ray binaries, Cen X-3, SMC X-1, and LMC X-4, there were several peaks in the PSD corresponding to the orbital period and the superorbital period.
Power Spectrum Density of long-term MAXI data
Sugimoto, Juri; Sugizaki, Mutsumi; Serino, Motoko; Kitamoto, Shunji; Sato, Ryousuke; Ueda, Yoshihiro; Ueno, Shiro
2013-01-01
Monitor of All-sky X-ray Image (MAXI) on the International Space Station has been observing the X-ray sky since 2009 August 15. It has accumulated the X-ray data for about four years, so far. X-ray objects are usually variable and their variability can be studied by the power spectrum density (PSD) of the X-ray light curves.We applied our method to calculate PSDs of several kinds of objects observed with MAXI. We obtained significant PSDs from 16 Seyfert galaxies.For blackhole binary Cygnus X-1 there was a difference in the shape of PSD between the hard state and the soft state. For high mass X-ray binaries, Cen X-3, SMC X-1, and LMC X-4, there were several peaks in the PSD corresponding to the orbital period and the superorbital period.
Large Scale Magnetic Fields: Density Power Spectrum in Redshift Space
Indian Academy of Sciences (India)
Rajesh Gopal; Shiv K. Sethi
2003-09-01
We compute the density redshift-space power spectrum in the presence of tangled magnetic fields and compare it with existing observations. Our analysis shows that if these magnetic fields originated in the early universe then it is possible to construct models for which the shape of the power spectrum agrees with the large scale slope of the observed power spectrum. However requiring compatibility with observed CMBR anisotropies, the normalization of the power spectrum is too low for magnetic fields to have significant impact on the large scale structure at present. Magnetic fields of a more recent origin generically give density power spectrum ∝ 4 which doesn’t agree with the shape of the observed power spectrum at any scale. Magnetic fields generate curl modes of the velocity field which increase both the quadrupole and hexadecapole of the redshift space power spectrum. For curl modes, the hexadecapole dominates over quadrupole. So the presence of curl modes could be indicated by an anomalously large hexadecapole, which has not yet been computed from observation. It appears difficult to construct models in which tangled magnetic fields could have played a major role in shaping the large scale structure in the present epoch. However if they did, one of the best ways to infer their presence would be from the redshift space effects in the density power spectrum.
Matter density perturbation and power spectrum in running vacuum model
Geng, Chao-Qiang
2016-01-01
We investigate the matter density perturbation $\\delta_m$ and power spectrum $P(k)$ in the running vacuum model (RVM) with the cosmological constant being a function of the Hubble parameter, given by $\\Lambda = \\Lambda_0 + 6 \\sigma H H_0+ 3\
Complex spectrum of spin models for finite-density QCD
Nishimura, Hiromichi; Pangeni, Kamal
2016-01-01
We consider the spectrum of transfer matrix eigenvalues associated with Polyakov loops in lattice QCD at strong coupling. The transfer matrix at finite density is non-Hermitian, and its eigenvalues become complex as a manifestation of the sign problem. We show that the symmetry under charge conjugation and complex conjugation ensures that the eigenvalues are either real or part of a complex conjugate pair, and the complex pairs lead to damped oscillatory behavior in Polyakov loop correlation functions, which also appeared in our previous phenomenological models using complex saddle points. We argue that this effect should be observable in lattice simulations of QCD at finite density.
SERS spectrum of gallic acid obtained from a modified silver colloid
Garrido, C.; Diaz-Fleming, G.; Campos-Vallette, M. M.
2016-06-01
Two different crystals of the gallic acid were microscopically separated from a p.a. commercial product. The Raman spectra analysis allowed distinguishing monomeric and dimeric structures. The vibrational wave numbers were computed using DFT quantum chemical calculations. The data obtained from wave number calculations are used to assign vibrational bands obtained in the Raman spectrum. The dimer, characterized as ellagic acid, involves the carboxyl and hydroxyl moieties. The Raman spectrum in water solution of each species is dominated by the monomeric form. A low negatively charged Ag colloid allowed obtain to the best of our knowledge, the first surface enhanced Raman scattering (SERS) spectrum of the gallic acid. The possible electrophilic attacking sites of the title molecule are identified using MEP surface plot study and the orientation of the analyte on the metal surface is proposed tilted to the surface.
Optimally focused cold atom systems obtained using density-density correlations.
Putra, Andika; Campbell, Daniel L; Price, Ryan M; De, Subhadeep; Spielman, I B
2014-01-01
Resonant absorption imaging is a common technique for detecting the two-dimensional column density of ultracold atom systems. In many cases, the system's thickness along the imaging direction greatly exceeds the imaging system's depth of field, making the identification of the optimally focused configuration difficult. Here we describe a systematic technique for bringing Bose-Einstein condensates (BEC) and other cold-atom systems into an optimal focus even when the ratio of the thickness to the depth of field is large: a factor of 8 in this demonstration with a BEC. This technique relies on defocus-induced artifacts in the Fourier-transformed density-density correlation function (the power spectral density, PSD). The spatial frequency at which these artifacts first appear in the PSD is maximized on focus; the focusing process therefore both identifies and maximizes the range of spatial frequencies over which the PSD is uncontaminated by finite-thickness effects.
Power Spectrum Density of Stochastic Oscillating Accretion Disk
Indian Academy of Sciences (India)
G. B. Long; J. W. Ou; Y. G. Zheng
2016-06-01
In this paper, we employ a stochastic oscillating accretion disk model for the power spectral index and variability of BL Lac object S5 0716+714. In the model, we assume that there is a relativistic oscillation of thin accretion disks and it interacts with an external thermal bath through a friction force and a random force. We simulate the light curve and the power spectrum density (PSD) at (i) over-damped, (ii) critically damped and (iii) under-damped cases, respectively. Our results show that the simulated PSD curves depend on the intrinsic property of the accretion disk, and it could be produced in a wide interval ranging from 0.94 to 2.05 by changing the friction coefficient in a stochastic oscillating accretion disk model. We argue that accretion disk stochastic oscillating could be a possible interpretation for observed PSD variability.
Wang, Hefeng
2014-08-14
We present a quantum algorithm that provides a general approach for obtaining the energy spectrum of a physical system without making a guess on its eigenstates. In this algorithm, a probe qubit is coupled to a quantum register R which consists of one ancilla qubit and an n-qubit register that represents the system. R is prepared in a general reference state, and a general excitation operator that acts on R is constructed. The probe exhibits a dynamical response only when it is resonant with a transition from the reference state to an excited state of R which contains the eigenstates of the system. By varying the probe's frequency, the energy spectrum and the eigenstates of the system can be obtained.
Modeling the Void H I Column Density Spectrum
Manning, C V
2003-01-01
The equivalent width distribution function (EWDF) of \\hone absorbers specific to the void environment has been recently derived (Manning 2002), revealing a large line density of clouds (dN/dz ~500 per unit z for Log (N_HI)> 12.4). I show that the void absorbers cannot be diffuse (or so-called filamentary) clouds, expanding with the Hubble flow, as suggested by N-body/hydro simulations. Absorbers are here modeled as the baryonic remnants of sub-galactic perturbations that have expanded away from their dark halos in response to reionization at z ~ 6.5. A 1-D Lagrangian hydro/gravity code is used to follow the dynamic evolution and ionization structure of the baryonic clouds for a range of halo circular velocities. The simulation products at z=0 can be combined according to various models of the halo velocity distribution function to form a column density spectrum that can be compared with the observed. I find that such clouds may explain the observed EWDF if the halo velocity distribution function is as steep a...
Phonon spectrum of YBCO obtained by specific heat inversion method for real data
Tao Wen; Dai Xian Xi; Dai Ji Xin; Evenson, W E
2003-01-01
In this paper, the phonon spectrum of YBCO is obtained from experimental specific heat data by an exact inversion formula with a parameter for eliminating divergences. The results can be compared to those of neutron inelastic scattering, which can only be carried out in a few laboratories. Some key points of specific heat-phonon spectrum inversion (SPI) theory and a method of asymptotic behaviour control are discussed. An improved unique existence theorem is presented, and a universal function set for numerical calculation of SPI is calculated with high accuracy, which makes the inversion method applicable and convenient in practice. This is the first time specific heat-phonon SPI has been realized for a concrete system.
Matter density perturbation and power spectrum in running vacuum model
Geng, Chao-Qiang; Lee, Chung-Chi
2016-10-01
We investigate the matter density perturbation δm and power spectrum P(k) in the running vacuum model (RVM) with the cosmological constant being a function of the Hubble parameter, given by Λ = Λ0 + 6σHH0 + 3νH2, in which the linear and quadratic terms of H would originate from the QCD vacuum condensation and cosmological renormalization group, respectively. Taking the dark energy perturbation into consideration, we derive the evolution equation for δm and find a specific scale dcr = 2π/kcr, which divides the evolution of the universe into the sub and super-interaction regimes, corresponding to k ≪ kcr and k ≫ kcr, respectively. For the former, the evolution of δm has the same behavior as that in the ΛCDM model, while for the latter, the growth of δm is frozen (greatly enhanced) when ν + σ > ( matter and dark energy. It is clear that the observational data rule out the cases with ν < 0 and ν + σ < 0, while the allowed window for the model parameters is extremely narrow with ν , |σ | ≲ {O}(10^{-7}).
Matter density perturbation and power spectrum in running vacuum model
Geng, Chao-Qiang; Lee, Chung-Chi
2017-01-01
We investigate the matter density perturbation δm and power spectrum P(k) in the running vacuum model, with the cosmological constant being a function of the Hubble parameter, given by Λ = Λ0 + 6σHH0 + 3νH2, in which the linear and quadratic terms of H would originate from the QCD vacuum condensation and cosmological renormalization group, respectively. Taking the dark energy perturbation into consideration, we derive the evolution equation for δm and find a specific scale dcr = 2π/kcr, which divides the evolution of the universe into the sub-interaction and super-interaction regimes, corresponding to k ≪ kcr and k ≫ kcr, respectively. For the former, the evolution of δm has the same behaviour as that in the Λ cold dark model, while for the latter, the growth of δm is frozen (greatly enhanced) when ν + σ > (extremely narrow with ν , |σ | ≲ O(10^{-7}).
Xu, Meng-long; Yang, Chang-bao; Liu, Wan-song; Wu, Yan-gang; Zhang, Chen-xi
2015-08-01
It chooses 15 kinds of rock from the three major rock categories as the rock samples (the number of rock samples is 208) and obtains the density, susceptibility and reflection spectrum at the wave band of 350~2500 nm. It calculates the correlative coefficients with the aim of studying the characteristic relationship between the property (including the density and the susceptibility) of the rock and the reflectivity. It concludes the wave band of the reflection spectrum which owes the prospect to discuss the density and susceptibility of the rock qualitatively or quantitatively, meanwhile, it sums up the characteristic of the curves of the correlative coefficients. In this paper, the discussion and analysis based on the results show that the study on the character relationship between the property of rock (density and susceptibility) and the reflection spectrum is meaningful and workable.
Trokielewicz, Mateusz; Bartuzi, Ewelina; Michowska, Katarzyna; Andrzejewska, Antonina; Selegrat, Monika
2015-09-01
In the age of modern, hyperconnected society that increasingly relies on mobile devices and solutions, implementing a reliable and accurate biometric system employing iris recognition presents new challenges. Typical biometric systems employing iris analysis require expensive and complicated hardware. We therefore explore an alternative way using visible spectrum iris imaging. This paper aims at answering several questions related to applying iris biometrics for images obtained in the visible spectrum using smartphone camera. Can irides be successfully and effortlessly imaged using a smartphone's built-in camera? Can existing iris recognition methods perform well when presented with such images? The main advantage of using near-infrared (NIR) illumination in dedicated iris recognition cameras is good performance almost independent of the iris color and pigmentation. Are the images obtained from smartphone's camera of sufficient quality even for the dark irides? We present experiments incorporating simple image preprocessing to find the best visibility of iris texture, followed by a performance study to assess whether iris recognition methods originally aimed at NIR iris images perform well with visible light images. To our best knowledge this is the first comprehensive analysis of iris recognition performance using a database of high-quality images collected in visible light using the smartphones flashlight together with the application of commercial off-the-shelf (COTS) iris recognition methods.
Erdem, Recai
2017-03-01
The equation of state of an energy density may be significantly modified by coupling it to another energy density. In the light of this observation we check the possibility of producing cosmic accelerated expansion in this way. In particular we consider the case where matter is converted to radiation (or vice versa by particle physics processes). We find that cosmic accelerated expansion can be obtained in this way only if an intermediate state with negative equation of state forms during the conversion.
Cosmological Density and Power Spectrum from Peculiar Velocities Nonlinear Corrections and PCA
Silberman, L; Eldar, A; Zehavi, I
2001-01-01
we allow for nonlinear effects in the likelihood analysis of galaxy peculiar velocities, and obtain ~35%-lower values for the cosmological density parameter and for the amplitude of mass-density fluctuations. The power spectrum in the linear regime is assumed to be a flat LCDM model (h=0.65, n=1, COBE) with only Om_m as a free parameter. Since the likelihood is driven by the nonlinear regime, we "break" the power spectrum at k_b=0.2 h/Mpc and fit a power law at k>k_b. This allows for independent matching of the nonlinear behavior and an unbiased fit in the linear regime. The analysis assumes Gaussian fluctuations and errors, and a linear relation between velocity and density. Tests using mock catalogs that properly simulate nonlinear effects demonstrate that this procedure results in a reduced bias and a better fit. We find for the Mark3 and SFI data Om_m=0.32+-0.06 and 0.37+-0.09 respectively, with sigma_8*Om_m^0.6 =0.49+-0.06 and 0.63+-0.08, in agreement with constraints from other data. The quoted 90% erro...
Directory of Open Access Journals (Sweden)
R Dariani
2015-01-01
Full Text Available Reflection spectra of four porous silicon samples under etching times of 2, 6, 10, and 14 min with current density of 10 mA/cm2 were measured. Reflection spectra behaviors for all samples were the same, but their intensities were different and decreased by increasing the etching time. The similar behavior of reflection spectra could be attributed to the electrolyte solution concentration which was the same during fabrication and reduction of reflection spectrum due to the reduction of particle size. Also, the region for the lowest intensity at reflection spectra was related to porous silicon energy gap which shows blue shift for porous silicon energy gap. Roughness study of porous silicon samples was done by scattering spectra measurements, Rayleigh criteria, and Davis-Bennet equation. Scattering spectra of the samples were measured at 10, 15, and 20 degrees by using spectrophotometer. Reflected light intensity reduced by increasing the scattering angle except for the normal scattering which agreed with Rayleigh criteria. Also, our results showed that by increasing the etching time, porosity (sizes and numbers of pores increases and therefore light absorption increases and scattering from surface reduces. But since scattering varies with the observation scale (wavelength, the relationship between scattering and porosity differs by varying the observation scale (wavelength
Khalchukov, F. F.; Korolkova, E. V.; Kudryavtsev, V. A.; Malgin, A. S.; Ryazhskaya, O. G.; Zatsepin, G. T.
1985-01-01
The vertical muon spectrum up to 15 TeV obtained with the underground installation is presented. Recent experimental data dealing with horizontal and vertical cosmic ray muon spectra are analyzed and discussed.
A Procedure to Obtain the Effective Nuclear Charge from the Atomic Spectrum of Sodium
Sala*, O.; Araki, Koiti; Noda, L. K.
1999-09-01
The penetration of the valence electron orbitals of the alkali metals into their inner shells and its effect on the energy levels can be considered through two methods that take into account modifications of the hydrogen formula (one-electron system). One of them considers the quantum defect, modifying the quantum number n; the other considers the effective nuclear charge Z* replacing the nuclear charge Z. The method using the quantum defect is widely used because this quantity is practically constant for a given angular momentum quantum number l. However, the method using effective nuclear charge is more realistic because it explains many atomic and molecular properties - but the effective nuclear charge depends on l as well as on the principal quantum number n. This article describes a relatively simple graphical procedure to calculate the effective nuclear charges experienced by the sodium valence electron from its atomic spectrum. A relation of Z* with n for a given l is obtained and the Z* values for all states of the valence electron are found; the energy terms can also be determined. The calculations can be performed by using common spreadsheet software.
Size and average density spectra of macromolecules obtained from hydrodynamic data.
Pavlov, G M
2007-02-01
It is proposed to normalize the Mark-Kuhn-Houwink-Sakurada type of equation relating the hydrodynamic characteristics, such as intrinsic viscosity, velocity sedimentation coefficient and translational diffusion coefficient of linear macromolecules to their molecular masses for the values of linear density M(L) and the statistical segment length A. When the set of data covering virtually all known experimental information is normalized for M(L), it is presented as a size spectrum of linear polymer molecules. Further normalization for the A value reduces all data to two regions: namely the region exhibiting volume interactions and that showing hydrodynamic draining. For chains without intachain excluded volume effects these results may be reproduced using the Yamakawa-Fujii theory of wormlike cylinders. Data analyzed here cover a range of contour lengths of linear chains varying by three orders of magnitude, with the range of statistical segment lengths varying approximately 500 times. The plot of the dependence of [eta]M on M represents the spectrum of average specific volumes occupied by linear and branched macromolecules. Dendrimers and globular proteins for which the volume occupied by the molecule in solution is directly proportional to M have the lowest specific volume. The homologous series of macromolecules in these plots are arranged following their fractal dimensionality.
Jayatilaka, Dylan; Dittrich, Birger
2008-05-01
An approach is outlined for X-ray structure refinement using atomic density fragments obtained by Hirshfeld partitioning of quantum-mechanical density fragments. Results are presented for crystal structure refinements of urea and benzene using these 'Hirshfeld atoms'. Using this procedure, the quantum-mechanical non-spherical electron density is taken into account in the structural model based on the conformation found in the crystal. Contrary to current consensus in structure refinement, the anisotropic displacement parameters of H atoms can be reproduced from neutron diffraction measurements simply from a least-squares fit using the Hirshfeld atoms derived from the BLYP level of theory and including a simple point-charge model to treat the crystal environment.
Flow rate of particles through apertures obtained from self-similar density and velocity profiles
2012-01-01
‘‘Beverloo’s law’’ is considered as the standard expression to estimate the ﬂow rate of particles through apertures. This relation was obtained by simple dimensional analysis and includes empirical parameters whose physical meaning is poorly justiﬁed. In this Letter, we study the density and velocity proﬁles in the ﬂow of particles through an aperture. We ﬁnd that, for the whole range of apertures studied, both proﬁles are self-similar. Hence, by means of the functionality obtained for the...
Directory of Open Access Journals (Sweden)
Orhan Gökhan
2012-01-01
Full Text Available The effects of copper ion concentrations and electrolyte temperature on the morphologies and on the apparent densities of electrolytic copper powders at high current densities under galvanostatic regime were examined. These parameters were evaluated by the current efficiency of hydrogen evolution. In addition, scanning electron microscopy was used for analyzing the morphology of the copper powders. It was found that the morphology was dependent over the copper ion concentration and electrolyte temperature under same current density (CD conditions. At 150 mA cm-2 and the potential of 1000±20 mV (vs. SCE, porous and disperse copper powders were obtained at low concentrations of Cu ions (0.120 M Cu2+ in 0.50 M H2SO4. Under this condition, high rate of hydrogen evolution reaction took place parallel to copper electrodeposition. The morphology was changed from porous, disperse and cauliflower-like to coral-like, shrub-like and stalk-stock like morphology with the increasing of Cu ion concentrations towards 0.120 M, 0.155 M, 0.315 M, 0.475 M and 0.630 M Cu2+ in 0.5 M H2SO4 respectively at the same CD. Similarly, as the temperature was increased, powder morphology and apparent density were observed to be changed. The apparent density values of copper powders were found to be suitable for many of the powder metallurgy applications.
Hazra, Milan
2016-01-01
Valuable dynamical and structural information about neat liquid DMSO at ambient conditions can be obtained through study of low frequency vibrations in the far infrared (FIR), that is, terahertz regime. For DMSO, collective excitations as well as single molecule stretches and bends have been measured by different kinds of experiments such as OHD-RIKES and terahertz spectroscopy. In the present work we investigate the intermolecular vibrational spectrum of DMSO through three different computational techniques namely (i) the far-infra red spectrum obtained through Fourier transform of total dipole moment auto time correlation function, (ii) from Fourier transform of the translational and angular velocity time autocorrelation functions and a (iii) quenched normal mode analysis of the parent liquid at 300K. The three spectrum, although exhibit differences among each other, reveal similar features which are in good, semi-quantitative, agreement with experimental results. Study of participation ratio of the density...
Directory of Open Access Journals (Sweden)
S. Dastgeer
2005-01-01
Full Text Available Interstellar scintillation and angular radio wave broadening measurements show that interstellar and solar wind (electron density fluctuations exhibit a Kolmogorov-like k-5/3 power spectrum extending over many decades in wavenumber space. The ubiquity of the Kolmogorov-like interstellar medium (ISM density spectrum led to an explanation based on coupling incompressible magnetohydrodynamic (MHD fluctuations to density fluctuations through a 'pseudosound' relation within the context of 'nearly incompressible' (NI hydrodynamics (HD and MHD models. The NI theory provides a fundamentally different explanation for the observed ISM density spectrum in that the density fluctuations can be a consequence of passive scalar convection due to background incompressible fluctuations. The theory further predicts generation of long-scale structures and various correlations between the density, temperature and the (magneto acoustic as well as convective pressure fluctuations in the compressible ISM fluids in different thermal regimes that are determined purely by the thermal fluctuation level. In this paper, we present the results of our two dimensional nonlinear fluid simulations, exploring various nonlinear aspects that lead to inertial range ISM turbulence within the context of a NI hydrodymanics model. In qualitative agreement with the NI predictions and the in-situ observations, we find that i the density fluctuations exhibit a Kolmogorov-like spectrum via a passive convection in the field of the background incompressible fluctuations, ii the compressible ISM fluctuations form long scale flows and structures, and iii the density and the temperature fluctuations are anti-correlated.
Kauffmann, Steven Kenneth
2013-01-01
The quantum mechanics status of the probability vector current density has long seemed to be marginal. On one hand no systematic prescription for its construction is provided, and the special examples of it that are obtained for particular types of Hamiltonian operator could conceivably be attributed to happenstance. On the other hand this concept's key physical interpretation as local average particle flux, which flows from the equation of continuity that it is supposed to satisfy in conjunction with the probability scalar density, has been claimed to breach the uncertainty principle. Given the dispiriting impact of that claim, we straightaway point out that the subtle directional nature of the uncertainty principle makes it consistent with the measurement of local average particle flux. We next focus on the fact that the unique closed-form linear-superposition quantization of any classical Hamiltonian function yields in tandem the corresponding unique linear-superposition closed-form divergence of the proba...
Obtaining raised density connections by thermosonic microwelding in 3D integrated microcircuits
Directory of Open Access Journals (Sweden)
Lanin V. L.
2014-06-01
Full Text Available The authors consider the processes of obtaining raised density microwelded connections in 3D-integrated microcircuits by the thermosonic microwelding. The processes include the use of the raised frequencies of ultrasound, application of the microinstrument with a thinning of the working end and precision devices for ball formation, which provide reproducibility of connections quality. At a small step of contact pads, the use of a wire of small diameter (not more than 25 µm is necessary for devices with a multilevel arrangement of leads and chess arrangement of contact pads on the chip, providing the maximum length of the formed crosspieces does not exceed 4—5 mm.
Institute of Scientific and Technical Information of China (English)
WANG Zheng; ZHU Dianxiang
2007-01-01
This paper took the upper-lower wide belt sander B229 with four-feet wide belts,manufactured in China,as the study target.By means of framework dynamic design,we study its vibration characteristics by commencing from the place having horizontal defects and used experimental modal analysis (EMA) and power spectrum density (PSD) to observe the sanding parts and the whole machine,respectively.In the modal test,we mainly adopted the cross spots testing method to get the frequency response function of the fixed spots to every excitation vibration spot,then applied the SISO frequency response function and the frequency response function fitting method to identify and complete parameter recognition,respectively.The typical frequency response function chart of the whole machine and its sanding parts,as well as its second-order mode charts of contacting roller,were obtained.Through PSD analysis,we can get the amplitude-frequency spectrum and drive frequency.
Flow Rate of Particles through Apertures Obtained from Self-Similar Density and Velocity Profiles
Janda, Alvaro; Zuriguel, Iker; Maza, Diego
2012-06-01
“Beverloo’s law” is considered as the standard expression to estimate the flow rate of particles through apertures. This relation was obtained by simple dimensional analysis and includes empirical parameters whose physical meaning is poorly justified. In this Letter, we study the density and velocity profiles in the flow of particles through an aperture. We find that, for the whole range of apertures studied, both profiles are self-similar. Hence, by means of the functionality obtained for them the mass flow rate is calculated. The comparison of this expression with the Beverloo’s one reveals some differences which are crucial to understanding the mechanism that governs the flow of particles through orifices.
Gupta, Abhishek Kumar; Singh, Manish Pratap; Singh, Rajendra Kumar; Chandra, Suresh
2012-05-28
A non-hydrolytic one pot sol-gel method has been used to synthesize mesoporous silica ionogels with the confined ionic liquid (IL) 1-ethyl 3-methyl imidazolium tetra fluoro-borate [EMIM][BF(4)]. The precursor for obtaining the SiO(2) matrix was tetraethyl orthosilicate (TEOS) and formic acid was used as a catalyst. These ionogels have been characterized by density measurements, TEM, BET, DSC, TGA and FTIR. The incorporation of the ionic liquid [EMIM][BF(4)] enhances the gellification rate which results in the ionogels having very low density (~0.3 g cm(-3)). The low density has been explained on the basis of the creation of 'blind embedded pores' in the matrix (apart from open pores) due to very rapid gellification (~1 min). Morphological studies provide experimental evidence for the presence of blind pores/voids inside the ionogel ingots. We have also shown that the IL entrapped in nanopores (~7-8 nm pore size) of the SiO(2) matrix has different physical properties than the bulk IL viz. (a) the phase transition temperatures (T(g), T(c) and T(m)) of the IL change upon confinement, (b) the thermal stability reduces upon confinement, and (c) the pore wall interaction with the IL results in changes in the C-H vibrations of the imidazolium ring and alkyl chain (the former increasing) which is also indicated in our DFT-calculation.
Indian Academy of Sciences (India)
S Chakraborty; R Ramesh; J M Lough
2000-03-01
Density, 18O and 13C were measured along two tracks, one close to the central growth axis and the other, ∼20° off the axis, in a coral (Porites lutea) collected from the Stanley Reef, Central Great Barrier Reef, Australia. The 18O variations in the coral are well correlated with sea surface temperature changes. The common variances between the two tracks were about 60% in the 18O, 13C and the skeletal density variations. Part of the noise (40%) could be due to the difficulty of sampling exactly time contemporaneous parts of each band along the two tracks and part of it could be due to genuine intraband variability. In spite of the intraband variability, the time series obtained from the two tracks are similar, indicating that the dominant causative factor for the isotopic variations is external, i.e., the environmental conditions that prevail during the growth of the coral; density band formation does not appear to be directly controlled by the sea surface temperature.
Energy Technology Data Exchange (ETDEWEB)
Yao, X.Z.; Yang, T.F.; Chang-Diaz, F.R. [Plasma Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)
1995-09-01
The resonance fluorescence of neutral hydrogen illuminated by {ital H}{sub {alpha}} radiation has been used as a technique for the spatially and temporally resolved density measurements of neutral hydrogen in high temperature plasmas, such as in the tokamak and magnetic mirror plasma fusion devices. The fluorescence signal, usually very weak and buried in the background of stray laser light and {ital H}{sub {alpha}} emission, is very difficult to extract and its measurements are inaccurate. This paper discusses the improvement of the signal extraction using two optical path laser-induced fluorescence (LIF) methods. One optical path carries the fluorescence signal and the background (the stray laser light and {ital H}{sub {alpha}} emission), whereas the other path carries only the background signal. By combining these two signals, a clean fluorescence signal can be isolated by subtracting out the background using a differential amplifier. The measurement is obtained instantaneously from these two signals which are taken simultaneously in one pulse rather than being extracted from two separate spectra taken in two sequential pulses (double pulses). This method, therefore, makes a significant improvement on the double pulse technique in terms of the accuracy of the measurement and the time resolution. Using this LIF technique the measurement of the neutral density profile in the exhaust of a tandem mirror plasma propulsion device is obtained and presented. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.
Energy Technology Data Exchange (ETDEWEB)
Benavente C, J. A.; Lacerda, M. A. S.; Guimaraes, A. M.; Da Silva, T. A. [Universidade Federal de Minas Gerais, Departamento de Engenharia Nuclear, Programa de Pos-graduacao em Ciencias e Tecnicas Nucleares, Pte. Antonio Carlos 6627, Belo Horizonte 31270-901, Minas Gerais (Brazil); Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98060 Zacatecas, Zac. (Mexico)
2015-10-15
In a cyclotron facility is strongly advised the use of spectrometry techniques to support workplace neutron dosimetry. Bonner sphere spectrometer (Bss) is the most used for radiation protection applications. Bss data must be unfolded to determine the spectral particle fluence. Some computer codes have been utilized for this purpose. These codes allow unfolding the spectrum from the Bss count rates through different algorithms. Some iterative routines need an initial guess spectrum to start the unfolding. The adequate choice of this initial spectrum is a critical part of the process and can affect the final solution. In this work, we evaluate the influence of the initial guess spectrum in the unfolding of Bss data obtained in four points inside the bunker of a PET cyclotron. The measurements were done utilizing a modified Bss system with thermoluminescent detectors (TLDs). Codes BUNKIUT and NSDUAZ were utilized to unfold the Bss data. For the NSDUAZ the starting spectrum is automatically obtained from a library initial guess spectra. For the BUNKIUT code were utilized two different initial guess spectra: (a) a Maxwellian spectrum with temperature of 1.4 MeV and shape factor of 0.1, created with the MAXIET algorithm and; (b) the spectra obtained through simulation with the MCNPX code version 2.7. Spectra obtained with both unfold codes and with the different initial guess spectra presented epithermal and thermal neutrons due to room-return effects. However, the contribution of the fast neutron to the total fluence were quite different for the different cases studied. These differences highlight the importance of an appropriate choice of an initial guess spectra for the quality of the results. (Author)
Hwang, Jungseek
2016-03-01
We investigate temperature smearing effects on the electron-boson spectral density function (I2χ(ω)) obtained from optical data using a maximum entropy inversion method. We start with two simple model input I2χ(ω), calculate the optical scattering rates at selected temperatures using the model input spectral density functions and a generalized Allen’s formula, then extract back I2χ(ω) at each temperature from the calculated optical scattering rate using the maximum entropy method (MEM) which has been used for analysis of optical data of high-temperature superconductors including cuprates, and finally compare the resulting I2χ(ω) with the input ones. From this approach we find that the inversion process can recover the input I2χ(ω) almost perfectly when the quality of fits is good enough and also temperature smearing (or thermal broadening) effects appear in the I2χ(ω) when the quality of fits is not good enough. We found that the coupling constant and the logarithmically averaged frequency are robust to the temperature smearing effects and/or the quality of fits. We use these robust properties of the two quantities as criterions to check whether experimental data have intrinsic temperature-dependent evolutions or not. We carefully apply the MEM to two material systems (one optimally doped and the other underdoped cuprates) and conclude that the I2χ(ω) extracted from the optical data contain intrinsic temperature-dependent evolutions.
Directory of Open Access Journals (Sweden)
Erich Heidenreich
2016-12-01
Full Text Available Research on the mechanisms of adaptive mutagenesis in resting, i.e. non-replicating cells relies on appropriate mutation assays. Here we provide a novel procedure for the detection of frameshift-reverting mutations in yeast. Proliferation of non-reverted cells in this assay is suppressed by the lack of a fermentable carbon source. The test allele was constructed in a way that the reversions mimic microsatellite instability, a condition often found in cancer cells. We show the cell numbers during these starvation conditions and provide a DNA sequence spectrum of a representative set of revertants. The data in this article support the publication "Glucose starvation as a selective tool for the study of adaptive mutations in Saccharomyces cerevisiae" (Heidenreich and Steinboeck, 2016 [1].
Mapping Bone Mineral Density Obtained by Quantitative Computed Tomography to Bone Volume Fraction
Pennline, James A.; Mulugeta, Lealem
2017-01-01
Methods for relating or mapping estimates of volumetric Bone Mineral Density (vBMD) obtained by Quantitative Computed Tomography to Bone Volume Fraction (BVF) are outlined mathematically. The methods are based on definitions of bone properties, cited experimental studies and regression relations derived from them for trabecular bone in the proximal femur. Using an experimental range of values in the intertrochanteric region obtained from male and female human subjects, age 18 to 49, the BVF values calculated from four different methods were compared to the experimental average and numerical range. The BVF values computed from the conversion method used data from two sources. One source provided pre bed rest vBMD values in the intertrochanteric region from 24 bed rest subject who participated in a 70 day study. Another source contained preflight vBMD values from 18 astronauts who spent 4 to 6 months on the ISS. To aid the use of a mapping from BMD to BVF, the discussion includes how to formulate them for purpose of computational modeling. An application of the conversions would be used to aid in modeling of time varying changes in vBMD as it relates to changes in BVF via bone remodeling and/or modeling.
Corrections to the density-functional theory electronic spectrum: Copper phthalocyanine
DEFF Research Database (Denmark)
Vazquez, Hector; Jelinek, P.; Brandbyge, Mads;
2009-01-01
A method for improving the electronic spectrum of standard Density-Functional Theory (DFT) calculations (i.e., LDA or GGA approximations) is presented, and its application is discussed for the case of the copper phthalocyanine (CuPc) molecule. The method is based on a treatment of exchange and co...
Analysing MUAP of EMG Signal with Power Density Spectrum in Matlab
Directory of Open Access Journals (Sweden)
Akash Kumar Bhoi
2013-07-01
Full Text Available The lack of a proper description of the EMG signal is probably the greatest single factor which has hampered the development of electromyography into a precise discipline. Our proposed methodology described the relationship between the EMG signal and the properties of a contracting muscle by analysing its power density spectrum. We have also discussed the basic concepts on Motor Unit Action potential and analyzed the spectral density of a healthy person EMG signal. The Power spectral Density is calculated with Welch's PSD estimate method by taking Hamming {&} Kaiser Window. This model can be useful for the study of gate analysis and control scheme of the peripheral nervous system
Maximum flux density of the gyrosynchrotron spectrum in a nonuniform source
Institute of Scientific and Technical Information of China (English)
Ai-Hua Zhou; Rong-Chuan Wang; Cheng-Wen Shao
2009-01-01
The maximum flux density of a gyrosynchrotron radiation spectrum in a mag- netic dip|oe model with self absorption and gyroresonance is calculated. Our calculations show that the maximum flux density of the gyrosynchrotron spectrum increases with in- creasing low-energy cutoff, number density, input depth of energetic electrons, magnetic field strength and viewing angle, and with decreasing energy spectral index of energetic electrons, number density and temperature of thermal electrons. It is found that there are linear correlations between the logarithms of the maximum flux density and the above eight parameters with correlation coefficients higher than 0.91 and fit accuracies better than 10%. The maximum flux density could be a good indicator of the changes of these source parameters. In addition, we find that there are very good positive linear correla- tions between the logarithms of the maximum flux density and peak frequency when the above former five parameters vary respectively. Their linear correlation coefficients are higher than 0.90 and the fit accuracies are better than 0.5%.
Energy Technology Data Exchange (ETDEWEB)
Ishimatsu, Naoki, E-mail: naoki@sci.hiroshima-u.ac.jp; Matsumoto, Ken; Maruyama, Hiroshi [Department of Physics, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashihiroshima, Hiroshima 739-8526 (Japan); Kawamura, Naomi; Mizumaki, Masaichiro [Japan Synchrotron Radiation Research Institute (JASRI), SPring-8, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Sumiya, Hitoshi [Electronics and Materials R& D Laboratories, Sumitomo Electric Industries, 1-1-1 Koyakita, Itami, Hyogo 664-0016 (Japan); Irifune, Tetsuo [Geodynamics Research Center, Ehime University, 2-5 Bunkyo-cho, Matsuyama 790-8577 (Japan)
2012-09-01
Nano-polycrystalline diamond has been used to obtain a glitch-free X-ray absorption spectrum under high pressure. The advantage and capability of nano-polycrystalline diamond anvils is discussed by a comparison of the glitch map with that of single-crystal diamond anvils. Nano-polycrystalline diamond (NPD) [Irifune et al. (2003 ▶), Nature (London), 421, 599] has been used to obtain a glitch-free X-ray absorption spectrum under high pressure. In the case of conventional single-crystal diamond (SCD) anvils, glitches owing to Bragg diffraction from the anvils are superimposed on X-ray absorption spectra. The glitch has long been a serious problem for high-pressure research activities using X-ray spectroscopy because of the difficulties of its complete removal. It is demonstrated that NPD is one of the best candidate materials to overcome this problem. Here a glitch-free absorption spectrum using the NPD anvils over a wide energy range is shown. The advantage and capability of NPD anvils is discussed by a comparison of the glitch map with that of SCD anvils.
Application of resistograph to obtain the density and to differentiate wood species
Directory of Open Access Journals (Sweden)
Acuña, Luis
2011-09-01
Full Text Available This project offers a methodology for the analysis of resistographic profiles obtained from samples of wood and the extraction of precise data from these profiles.
Tests were conducted on healthy samples of wood from six different species, as well as on “old” wood in use as part of timber structures with an age of 80-120 years.
Based on the data collected using the resistograph, a series of variables was determined, and statistically analysed. An analysis of the data reveals the close relation between the resistographic variables and wood density (R2> 90%. Equally, in the case of healthy wood, an analysis of the defined variables permits the identification of the species of the sample with a very high probability and, therefore, its indirect resistance values.
En este trabajo se aporta una metodología para realizar el análisis de los perfiles resistográficos obtenidos de piezas de madera y poder con ello obtener con precisión determinados datos de las mismas.
Los ensayos se realizaron sobre madera sana de seis especies distintas, así como sobre piezas de madera “antigua” en uso, pertenecientes a estructuras de edificaciones con unos 80-120 años de servicio.
A partir de los datos recogidos por el resistógrafo se definieron una serie de variables, y fueron analizadas estadísticamente. Del análisis de los datos cabe destacar la magnífica relación existente entre las variables resistográficas y la densidad de la madera (R2> 90%. Igualmente, en el caso de madera sana, el análisis de las variables definidas permite asignar con una probabilidad muy elevada, la especie a la que pueda pertenecer y, por consiguiente, sus valores resistentes indirectos.
Institute of Scientific and Technical Information of China (English)
YANGXiao－Xue; WUYing
2002-01-01
We develop a simple approach to obtain explicitly exact analytical expressions of particle and kineticenergy densities for noninteracting Fermi gases in one-dimensional harmonic confinement,and in one-dimensional box confinement as well.
Institute of Scientific and Technical Information of China (English)
YANG XiaoXue; WU Ying
2002-01-01
We develop a simple approach to obtain explicitly exact analytical expressions of particle and kinetic-energy densities for noninteracting Fermi gases in one-dimensional harmonic confinement, and in one-dimensional boxconfinement as well.
Bartelmann, Matthias; Kozlikin, Elena; Lilow, Robert; Dombrowski, Johannes; Mildenberger, Julius
2016-01-01
In earlier work, we have developed a Kinetic Field Theory (KFT) for cosmological structure formation and showed that the non-linear density-fluctuation power spectrum known from numerical simulations can be reproduced quite well even if particle interactions are taken into account to first order only. Besides approximating gravitational interactions, we had to truncate the initial correlation hierarchy of particle momenta at the second order. Here, we substantially simplify KFT. We show that its central object, the free generating functional, can be factorized, taking the full hierarchy of momentum correlations into account. The factors appearing in the generating functional have a universal form and can thus be tabulated for fast access in perturbation schemes. Our results show that the complete hierarchy of initial momentum correlations is responsible for a characteristic deformation in the density-fluctuation power spectrum, caused by mode transport independent of the particle interaction. At the present e...
Statistical Analysis of the Spectral Density Estimate Obtained via Coifman Scaling Function
2007-01-01
Spectral density built as Fourier transform of covariance sequence of stationary random process is determining the process characteristics and makes for analysis of it’s structure. Thus, one of the main problems in time series analysis is constructing consistent estimates of spectral density via successive, taken after equal periods of time observations of stationary random process. This article is devoted to investigation of problems dealing with application of wavelet anal...
Wallis, David; Hansen, Lars N; Ben Britton, T; Wilkinson, Angus J
2016-09-01
Dislocations in geological minerals are fundamental to the creep processes that control large-scale geodynamic phenomena. However, techniques to quantify their densities, distributions, and types over critical subgrain to polycrystal length scales are limited. The recent advent of high-angular resolution electron backscatter diffraction (HR-EBSD), based on diffraction pattern cross-correlation, offers a powerful new approach that has been utilised to analyse dislocation densities in the materials sciences. In particular, HR-EBSD yields significantly better angular resolution (olivine, the dominant mineral in Earth's upper mantle by testing (1) different inversion methods for estimating geometrically necessary dislocation (GND) densities, (2) the sensitivity of the method under a range of data acquisition settings, and (3) the ability of the technique to resolve a variety of olivine dislocation structures. The relatively low crystal symmetry (orthorhombic) and few slip systems in olivine result in well constrained GND density estimates. The GND density noise floor is inversely proportional to map step size, such that datasets can be optimised for analysing either short wavelength, high density structures (e.g. subgrain boundaries) or long wavelength, low amplitude orientation gradients. Comparison to conventional images of decorated dislocations demonstrates that HR-EBSD can characterise the dislocation distribution and reveal additional structure not captured by the decoration technique. HR-EBSD therefore provides a highly effective method for analysing dislocations in olivine and determining their role in accommodating macroscopic deformation.
Correlation between the Flux Density and Polarization for Flat Spectrum Radio Quasars
Indian Academy of Sciences (India)
Fei-Peng Pi; Yong-Xiang Wang; Jing Pan
2011-03-01
In this paper, using the preliminary database of the University of Michigan Radio Astronomy Observatory (UMRAO) at the radio frequencies, we calculated the weighted polarization at 8 GHz and investigated the correlation between the polarization and the flux density for 92 flat spectrum radio quasars (FSRQs). We found that the two observations are closely and positively correlated for FSRQs. This is perhaps from a relativistic beaming effect.
Complex spectrum of finite-density lattice QCD with static quarks at strong coupling
Nishimura, Hiromichi; Pangeni, Kamal
2015-01-01
We calculate the spectrum of transfer matrix eigenvalues associated with Polyakov loops in finite-density lattice QCD with static quarks. These eigenvalues determine the spatial behavior of Polyakov loop correlations functions. Our results are valid for all values of the gauge coupling in $1+1$ dimensions, and valid in the strong-coupling region for any number of dimensions. When the quark chemical potential $\\mu$ is nonzero, the spatial transfer matrix $T$ is non-Hermitian. The appearance of complex eigenvalues in $T$ is a manifestation of the sign problem in finite-density QCD. The invariance of finite-density QCD under the combined action of charge conjugation $\\mathcal{C}$ and complex conjugation $\\mathcal{K}$ implies that the eigenvalues of $T$ are either real or part of a complex pair. Calculation of the spectrum confirms the existence of complex pairs in much of the temperature-chemical potential plane. Many features of the spectrum for static quarks are determined by a particle-hole symmetry. For $\\mu...
The \\HI column density power spectrum of six nearby spiral galaxies
Dutta, Prasun
2013-01-01
We propose a method to determine the power spectrum of \\HI column density fluctuations using radio-interferometric observations of 21-cm emission from the ISM of galaxies. We have used this to estimate the power spectra of six nearly face on nearby spiral galaxies. Earlier work has shown that these power spectra are well fitted by power laws with slopes around -1.6 across length-scales $\\sim 1 \\, {\\rm kpc}$ to $\\sim 10 \\, {\\rm kpc}$, the amplitude however was undetermined. In the present work we have determined the amplitude of the \\HI column density power spectrum. We find that the \\HI column density $N_{\\rm HI}$ expressed in units of $10^{20} \\, {\\rm cm}^{-2}$ has mean square fluctuations in the range $\\sim 0.03$ to $\\sim 20$. The amplitude of the power spectrum is found to be tightly correlated with the \\HI mass fraction of the galaxies. The physical process responsible for these scale-invariant fluctuations is, however, at present not known.
Energy Technology Data Exchange (ETDEWEB)
Wallis, David, E-mail: davidwa@earth.ox.ac.uk [Department of Earth Sciences, University of Oxford, South Parks Road, Oxford, Oxfordshire, OX1 3AN (United Kingdom); Hansen, Lars N. [Department of Earth Sciences, University of Oxford, South Parks Road, Oxford, Oxfordshire, OX1 3AN (United Kingdom); Ben Britton, T. [Department of Materials, Imperial College London, Royal School of Mines, Exhibition Road, London SW7 2AZ (United Kingdom); Wilkinson, Angus J. [Department of Materials, University of Oxford, Parks Road, Oxford, Oxfordshire, OX1 3PH (United Kingdom)
2016-09-15
Dislocations in geological minerals are fundamental to the creep processes that control large-scale geodynamic phenomena. However, techniques to quantify their densities, distributions, and types over critical subgrain to polycrystal length scales are limited. The recent advent of high-angular resolution electron backscatter diffraction (HR-EBSD), based on diffraction pattern cross-correlation, offers a powerful new approach that has been utilised to analyse dislocation densities in the materials sciences. In particular, HR-EBSD yields significantly better angular resolution (<0.01°) than conventional EBSD (~0.5°), allowing very low dislocation densities to be analysed. We develop the application of HR-EBSD to olivine, the dominant mineral in Earth's upper mantle by testing (1) different inversion methods for estimating geometrically necessary dislocation (GND) densities, (2) the sensitivity of the method under a range of data acquisition settings, and (3) the ability of the technique to resolve a variety of olivine dislocation structures. The relatively low crystal symmetry (orthorhombic) and few slip systems in olivine result in well constrained GND density estimates. The GND density noise floor is inversely proportional to map step size, such that datasets can be optimised for analysing either short wavelength, high density structures (e.g. subgrain boundaries) or long wavelength, low amplitude orientation gradients. Comparison to conventional images of decorated dislocations demonstrates that HR-EBSD can characterise the dislocation distribution and reveal additional structure not captured by the decoration technique. HR-EBSD therefore provides a highly effective method for analysing dislocations in olivine and determining their role in accommodating macroscopic deformation. - Highlights: • Lattice orientation gradients in olivine were measured using HR-EBSD. • The limited number of olivine slip systems enable simple least squares inversion for GND
Kappatou, A.; Jaspers, R. J. E.; Delabie, E.; Marchuk, O.; Biel, W.; Jakobs, M. A.
2012-10-01
Investigation of impurity transport properties in tokamak plasmas is essential and a diagnostic that can provide information on the impurity content is required. Combining charge exchange recombination spectroscopy (CXRS) and beam emission spectroscopy (BES), absolute radial profiles of impurity densities can be obtained from the CXRS and BES intensities, electron density and CXRS and BES emission rates, without requiring any absolute calibration of the spectra. The technique is demonstrated here with absolute impurity density radial profiles obtained in TEXTOR plasmas, using a high efficiency charge exchange spectrometer with high etendue, that measures the CXRS and BES spectra along the same lines-of-sight, offering an additional advantage for the determination of absolute impurity densities.
Energy Technology Data Exchange (ETDEWEB)
Kappatou, A.; Delabie, E. [FOM Institute DIFFER - Dutch Institute for Fundamental Energy Research, Association EURATOM-FOM, 3430 BE Nieuwegein (Netherlands); Jaspers, R. J. E.; Jakobs, M. A. [Science and Technology of Nuclear Fusion, Eindhoven University of Technology, 5600 MB Eindhoven (Netherlands); Marchuk, O.; Biel, W. [Institute for Energy and Climate Research, Forschungszentrum Julich GmbH, Trilateral Euregio Cluster, 52425 Julich (Germany)
2012-10-15
Investigation of impurity transport properties in tokamak plasmas is essential and a diagnostic that can provide information on the impurity content is required. Combining charge exchange recombination spectroscopy (CXRS) and beam emission spectroscopy (BES), absolute radial profiles of impurity densities can be obtained from the CXRS and BES intensities, electron density and CXRS and BES emission rates, without requiring any absolute calibration of the spectra. The technique is demonstrated here with absolute impurity density radial profiles obtained in TEXTOR plasmas, using a high efficiency charge exchange spectrometer with high etendue, that measures the CXRS and BES spectra along the same lines-of-sight, offering an additional advantage for the determination of absolute impurity densities.
Reconstructing the spectrum of the pregalactic density field from astronomical data
Kashlinsky, A
1998-01-01
In this paper we evaluate the spectrum of the pregalactic density field on scales $1h^{-1}Mpc < r < 100h^{-1}$Mpc from a variety of astronomical data. APM data on $w(\\theta)$ in six narrow magnitude is used, after correcting to possible evolutionary effects, to constrain the spectrum of galaxy clustering on scales $10h^{-1}Mpc < r < 50-100h^{-1}Mpc$. Fitting power spectra of CDM models to the data at all depths requires $\\Omega h=0.2$ if the primordial index $n=1$ and $\\Omega h=0.3$ if the spectrum is tilted with $n=0.7$. Then we compare the peculiar velocity field predicted by the APM spectrum of galaxy (light) distribution with the actual velocity data. The two fields are consistent and the comparison suggests that the bias factor is scale independent with $\\Omega^{0.6}/b\\simeq$(0.2-0.3). The next dataset used comes from the cluster correlation data. We calculate in detail the amplification of the cluster correlation function due to gravitational clustering and use the data on both the slope of ...
Exact Third-Order Density Perturbation and One-Loop Power Spectrum in General Dark Energy Models
Lee, Seokcheon; Biern, Sang Gyu
2014-01-01
Under the standard perturbation theory (SPT), we obtain the fully consistent third-order density fluctuation and kernels for the general dark energy models without using the Einstein-de Sitter (EdS) universe assumption for the first time. We also show that even though the temporal and spatial components of the SPT solutions can not be separable, one can find the exact solutions to any order in general dark energy models. With these exact solutions, we obtain the less than \\% error correction of one-loop matter power spectrum compared to that obtained from the EdS assumption for $k = 0.1 {\\rm h\\, Mpc}^{-1}$ mode at $z = 0$ (1, 1.5). Thus, the EdS assumption works very well at this scale. However, if one considers the correction for $P_{13}$, the error is about 6 (9, 11) \\% for the same mode at $z = 0$ (1, 1.5). One absorbs $P_{13}$ into the linear power spectrum in the renormalized perturbation theory (RPT) and thus one should use the exact solution instead of the approximation one. The error on the resummed p...
DEFF Research Database (Denmark)
Benavente, J.; Silva, V.; Pradanos, P.
2010-01-01
A version of the Donnan steric-partitioning pore model with dielectrical exclusion (DSPM-DE) has been used to get information on the pore size and charge density of a commercial membrane, NF45 from FilmTec, from its retention of KCl solutions. The conductivity inside the pores has been measured...... of the membrane. These two methods give results in fair accordance which probes that the sometimes controversial method of DSPM-DE can give accurate results for the charge as well as for the mean pore size of a nanofiltration membrane. Sonic clues to improve the way this model can be used are given as well....
Gas Density Fluctuations in the Perseus Cluster: Clumping Factor and Velocity Power Spectrum
Zhuravleva, I; Arevalo, P; Schekochihin, A A; Allen, S W; Fabian, A C; Forman, W R; Sanders, J S; Simionescu, A; Sunyaev, R; Vikhlinin, A; Werner, N
2015-01-01
X-ray surface brightness fluctuations in the core of the Perseus Cluster are analyzed, using deep observations with the Chandra observatory. The amplitude of gas density fluctuations on different scales is measured in a set of radial annuli. It varies from 8 to 12 per cent on scales of ~10-30 kpc within radii of 30-160 kpc from the cluster center and from 9 to 7 per cent on scales of ~20-30 kpc in an outer, 60-220 kpc annulus. Using a statistical linear relation between the observed amplitude of density fluctuations and predicted velocity, the characteristic velocity of gas motions on each scale is calculated. The typical amplitudes of the velocity outside the central 30 kpc region are 90-140 km/s on ~20-30 kpc scales and 70-100 km/s on smaller scales ~7-10 kpc. The velocity power spectrum is consistent with cascade of turbulence and its slope is in a broad agreement with the slope for canonical Kolmogorov turbulence. The gas clumping factor estimated from the power spectrum of the density fluctuations is low...
Mechanical properties of low density polymeric foams obtained from full-ﬁeld measurements
Directory of Open Access Journals (Sweden)
Pierron F.
2010-06-01
Full Text Available This exploratory paper presents some preliminary results on the use of fullﬁeld deformation measurements on low density polymeric foams to identify the evolution of Poisson’s ratio with compressive strain. Two types of foams were tested: a standard low density polyurethane foam and an auxetic foam manufactured from a similar precursor. 2D digital image correlation was used to measure the strain ﬁeld at the specimens surfaces. Then, Poisson’s ratios were identiﬁed using a dedicated inverse method called the Virtual Fields Method (VFM and the results compared with the standard approaches. The results illustrate the advantages of the VFM compared to the standard procedure. It was also found that for the standard foam, very strong localization eﬀects resulted in biased Poisson’s ratio evaluation. It was shown that this could be corrected by taking into account these localization eﬀects thanks to the full-ﬁeld information.
Directory of Open Access Journals (Sweden)
Francesco Zanlungo
Full Text Available We propose a way to introduce in microscopic pedestrian models a "social norm" in collision avoiding and overtaking, i.e. the tendency, shared by pedestrians belonging to the same culture, to avoid collisions and perform overtaking in a preferred direction. The "social norm" is implemented, regardless of the specific collision avoiding model, as a rotation in the perceived velocity vector of the opponent at the moment of computation of the collision avoiding strategy, and justified as an expectation that the opponent will follow the same "social norm" (for example a tendency to avoid on the left and overtake on the right, as proposed in this work for Japanese pedestrians. By comparing with real world data, we show that the introduction of this norm allows for a better reproduction of macroscopic pedestrian density and velocity patterns.
Hochegger, G P
2000-01-01
The electron content data, obtained by satellite-to-satellite occultations of radio signals can lead to height profiles of electron density by discrete inversion. Since there is no possibility to verify such profiles by means of other measurements (practically never measurements at the same time and same location) it was necessary to simulate occultation scenarios by means of an ionosphere model to obtain a large number of comparisons sufficient for investigations on a statistical basis. The obtained electron contents were inverted and compared with electron density height profiles, obtained with the same ionospheric model for the occultation point. The differences between these profiles were investigated (difference between the F2-peak maxima, the height of the maxima, the shape of the topside and bottom side ionosphere). Since simulations were done for chosen locations (250 randomly spread on the globe) for every month and every second hour and for two solar activity levels (HSA and LSA), a whole year was '...
DEFF Research Database (Denmark)
Høgfeldt Hansen, Leif
2016-01-01
The publication functions as a proces description of the development and construction of an urban furniture SPECTRUM in the city of Gwangju, Republic of Korea. It is used as the cataloque for the exhibition of Spectrum.......The publication functions as a proces description of the development and construction of an urban furniture SPECTRUM in the city of Gwangju, Republic of Korea. It is used as the cataloque for the exhibition of Spectrum....
Exact third-order density perturbation and one-loop power spectrum in general dark energy models
Directory of Open Access Journals (Sweden)
Seokcheon Lee
2014-09-01
Full Text Available Under the standard perturbation theory (SPT, we obtain the fully consistent third-order density fluctuation and kernels for the general dark energy models without using the Einstein–de Sitter (EdS universe assumption for the first time. We also show that even though the temporal and spatial components of the SPT solutions cannot be separable, one can find the exact solutions to any order in general dark energy models. With these exact solutions, we obtain the less than % error correction of one-loop matter power spectrum compared to that obtained from the EdS assumption for k=0.1 hMpc−1 mode at z=0(1,1.5. Thus, the EdS assumption works very well at this scale. However, if one considers the correction for P13, the error is about 6 (9, 11% for the same mode at z=0(1,1.5. One absorbs P13 into the linear power spectrum in the renormalized perturbation theory (RPT and thus one should use the exact solution instead of the approximation one. The error on the resummed propagator N of RPT is about 14 (8, 6% at z=0(1,1.5 for k=0.4 hMpc−1. For k=1 hMpc−1, the error correction of the total matter power spectrum is about 3.6 (4.6, 4.5% at z=0(1,1.5. Upcoming observation is required to archive the sub-percent accuracy to provide the strong constraint on the dark energy and this consistent solution is prerequisite for the model comparison.
Directory of Open Access Journals (Sweden)
Johann Charwat-Pessler
2015-06-01
Full Text Available The ability of bone graft substitutes to promote new bone formation has been increasingly used in the medical field to repair skeletal defects or to replace missing bone in a broad range of applications in dentistry and orthopedics. A common way to assess such materials is via micro computed tomography (µ-CT, through the density information content provided by the absorption of X-rays. Information on the chemical composition of a material can be obtained via Raman spectroscopy. By investigating a bone sample from miniature pigs containing the bone graft substitute Bio Oss®, we pursued the target of assessing to what extent the density information gained by µ-CT imaging matches the chemical information content provided by Raman spectroscopic imaging. Raman images and Raman correlation maps of the investigated sample were used in order to generate a Raman based segmented image by means of an agglomerative, hierarchical cluster analysis. The resulting segments, showing chemically related areas, were subsequently compared with the µ-CT image by means of a one-way ANOVA. We found out that to a certain extent typical gray-level values (and the related histograms in the µ-CT image can be reliably related to specific segments within the image resulting from the cluster analysis.
Institute of Scientific and Technical Information of China (English)
Jaime Goslvez; Stephen Johnston; Carmen Lpez-Fernndez; Altea Goslbez; Francisca Arroyo; Jose Lus Fernndez; Juan G lvarez
2014-01-01
Objective:To investigate the DNA longevity characteristics associated with each resultant fraction following density gradient centrifugation (DGC) in comparison to that of the original neat ejaculated sample. Methods:An aliquot of neat semen (NSS) collected from 7 patients was processed using DGC resulting in 3 fractions;Fraction 1:seminal plasma/40%gradient interface (GI);Fraction 2:40%GI/80%GI;Fraction 3:80%GI/pellet. An aliquot of each fraction and NSS was cryopreserved, thawed and incubated at 37 ℃for 24h;the increase of sperm DNA fragmentation was assessed using the Dyn-Halosperm assay following 0, 3, 6 and 24h of incubation. Results:While there was a significant reduction in the incidence of baseline sperm DNA fragmentation following DGC in Fraction 3, sperm DNA longevity was shown to be higher in the NSS than in any other sub-population following incubation. The highest levels of baseline DNA damage were found in Fractions 1 and 2;these fractions also showed the highest rate DNA fragmentation following incubation, subsequently exhibiting the lowest DNA longevity. Conclusion:1) Unnecessary incubation of spermatozoa prior to artificial insemination or in vitro fertilization, should be avoided, since sperm DNA longevity is significantly reduced after ex vivo sperm handling and 2) Although sperm selection by DCG significantly reduces the baseline levels of SDF of sperm in Fraction 3, sperm DNA longevity in this fraction was ultimately lower following 24 h incubation when compared to sperm recovered from non-centrifuged NSS.
Gas density fluctuations in the Perseus Cluster: clumping factor and velocity power spectrum
Energy Technology Data Exchange (ETDEWEB)
Zhuravleva, I.; Churazov, E.; Arevalo, P.; Schekochihin, A. A.; Allen, S. W.; Fabian, A. C.; Forman, W. R.; Sanders, J. S.; Simionescu, A.; Sunyaev, R.; Vikhlinin, A.; Werner, N.
2015-05-20
X-ray surface brightness fluctuations in the core of the Perseus Cluster are analysed, using deep observations with the Chandra observatory. The amplitude of gas density fluctuations on different scales is measured in a set of radial annuli. It varies from 7 to 12 per cent on scales of ~10–30 kpc within radii of 30–220 kpc from the cluster centre. Using a statistical linear relation between the observed amplitude of density fluctuations and predicted velocity, the characteristic velocity of gas motions on each scale is calculated. The typical amplitudes of the velocity outside the central 30 kpc region are 90–140 km s^{-1} on ~20–30 kpc scales and 70–100 km s^{-1} on smaller scales ~7–10 kpc. The velocity power spectrum (PS) is consistent with cascade of turbulence and its slope is in a broad agreement with the slope for canonical Kolmogorov turbulence. The gas clumping factor estimated from the PS of the density fluctuations is lower than 7–8 per cent for radii ~30–220 kpc from the centre, leading to a density bias of less than 3–4 per cent in the cluster core. Uncertainties of the analysis are examined and discussed. Future measurements of the gas velocities with the Astro-H, Athena and Smart-X observatories will directly measure the gas density–velocity perturbation relation and further reduce systematic uncertainties in this analysis.
DEFF Research Database (Denmark)
Findeisen, E.; Feidenhans'l, R.; Vigild, Martin Etchells
1994-01-01
Specular reflectivity of neutrons and x rays can be used to determine the scattering length density profile of a material perpendicular to its surface. We have applied these techniques to study amorphous, diamondlike, hydrocarbon films. By the combination of these two techniques we obtain not only...... the mass density, but also the concentration of hydrogen, which varies in our case between 0 and 30 at.%. This method is a new and nondestructive way to determine the concentration of hydrogen within an error of less than 2 at.% in samples with sharp interfaces. It is especially suited for diamondlike...... carbon films....
Zuehlsdorff, Tim J; Payne, Mike C; Haynes, Peter D
2015-01-01
We present a solution of the full TDDFT eigenvalue equation in the linear response formalism exhibiting a linear-scaling computational complexity with system size, without relying on the simplifying Tamm-Dancoff approximation (TDA). The implementation relies on representing the occupied and unoccupied subspace with two different sets of in situ optimised localised functions, yielding a very compact and efficient representation of the transition density matrix of the excitation with the accuracy associated with a systematic basis set. The TDDFT eigenvalue equation is solved using a preconditioned conjugate-gradients algorithm that is very memory-efficient. The algorithm is validated on a test molecule and a good agreement with results obtained from standard quantum chemistry packages is found, with the preconditioner yielding a significant improvement in convergence rates. The method developed in this work is then used to reproduce experimental results of the absorption spectrum of bacteriochlorophyll (BChl) i...
Rapid modelling of the redshift-space power spectrum multipoles for a masked density field
Wilson, M. J.; Peacock, J. A.; Taylor, A. N.; de la Torre, S.
2017-01-01
In this work, we reformulate the forward modelling of the redshift-space power spectrum multipole moments for a masked density field, as encountered in galaxy redshift surveys. Exploiting the symmetries of the redshift-space correlation function, we provide a masked-field generalization of the Hankel transform relation between the multipole moments in real and Fourier space. Using this result, we detail how a likelihood analysis requiring computation for a broad range of desired P(k) models may be executed 103-104 times faster than with other common approaches, together with significant gains in spectral resolution. We present a concrete application to the complex angular geometry of the VIMOS Public Extragalactic Redshift Survey PDR-1 release and discuss the validity of this technique for finite-angle surveys.
Fault Feature Extraction of Rolling Bearing Based on an Improved Cyclical Spectrum Density Method
Institute of Scientific and Technical Information of China (English)
LI Min; YANG Jianhong; WANG Xiaojing
2015-01-01
The traditional cyclical spectrum density(CSD) method is widely used to analyze the fault signals of rolling bearing. All modulation frequencies are demodulated in the cyclic frequency spectrum. Consequently, recognizing bearing fault type is difficult. Therefore, a new CSD method based on kurtosis(CSDK) is proposed. The kurtosis value of each cyclic frequency is used to measure the modulation capability of cyclic frequency. When the kurtosis value is large, the modulation capability is strong. Thus, the kurtosis value is regarded as the weight coefficient to accumulate all cyclic frequencies to extract fault features. Compared with the traditional method, CSDK can reduce the interference of harmonic frequency in fault frequency, which makes fault characteristics distinct from background noise. To validate the effectiveness of the method,experiments are performed on the simulation signal, the fault signal of the bearing outer race in the test bed, and the signal gathered from the bearing of the blast furnace belt cylinder. Experimental results show that the CSDK is better than the resonance demodulation method and the CSD in extracting fault features and recognizing degradation trends. The proposed method provides a new solution to fault diagnosis in bearings.
Correlation between peak energy and Fourier power density spectrum slope in gamma-ray bursts
Dichiara, S; Amati, L; Frontera, F; Margutti, R
2016-01-01
The origin of the gamma-ray burst (GRB) prompt emission still defies explanation, in spite of recent progress made, for example, on the occasional presence of a thermal component in the spectrum along with the ubiquitous non-thermal component that is modelled with a Band function. The combination of finite duration and aperiodic modulations make GRBs hard to characterise temporally. Although correlations between GRB luminosity and spectral hardness on one side and time variability on the other side have long been known, the loose and often arbitrary definition of the latter makes the interpretation uncertain. We characterise the temporal variability in an objective way and search for a connection with rest-frame spectral properties for a number of well-observed GRBs. We studied the individual power density spectra (PDS) of 123 long gamma-ray bursts with measured redshift, rest-frame peak energy Ep,i of the time-averaged nuFnu spectrum, and well-constrained PDS slope alpha detected with Swift, Fermi and past s...
Morfín-Otero, Rayo; Mendoza-Olazarán, Soraya; Silva-Sánchez, Jesús; Rodríguez-Noriega, Eduardo; Laca-Díaz, Jorge; Tinoco-Carrillo, Perla; Petersen, Luis; López, Perla; Reyna-Flores, Fernando; Alcantar-Curiel, Dolores; Garza-Ramos, Ulises; Garza-González, Elvira
2013-10-01
The prevalence and genetic characteristics of Escherichia coli and Klebsiella pneumoniae clinical isolates producing extended-spectrum β-lactamase (ESBL) were examined. Between October 2010 and March 2011, E. coli (n=460) and K. pneumoniae (n=78) isolates were collected at a tertiary care hospital in Guadalajara, Mexico. The minimum inhibitory concentration (MIC) for each isolate was determined using a broth microdilution method, and ESBL production was assayed. The presence of β-lactamase genes, blaSHV, blaCTX-M, and blaTLA-1, was detected by PCR and confirmed with sequencing. Only ESBL-producing isolates were further subjected to pulsed-field gel electrophoresis (PFGE) and plasmid profiling. All of the ESBL isolates were multidrug resistant and 75/460 (16.3%) E. coli isolates and 21/78 (26.9%) K. pneumoniae isolates were found to produce ESBL. For the E. coli isolates, >95% susceptibility to amikacin, meropenem, fosfomycin, imipenem, and nitrofurantoin was observed. For K. pneumoniae, similar results were obtained, with discrepancies observed for gentamicin and nitrofurantoin. PFGE further identified eleven pulsotypes for E. coli and three clusters of K. pneumoniae. CTX-M-15 was detected in 85% of ESBL-producing E. coli and in 76% of ESBL-producing K. pneumoniae. In contrast, SHV-5 ESBL was identified in 17% of E. coli isolates and in 86% of K. pneumoniae isolates. The bla-TLA-1 gene was not detected in any of the 96 isolates analyzed. Overall, CTX-M-15 and SHV-5 were found to have a high rate of spread throughout the hospital and were associated with strong multidrug resistance.
Energy Technology Data Exchange (ETDEWEB)
Pozuelo, F.; Querol, A.; Gallardo, S.; Rodenas, J.; Verdu, G.
2012-07-01
In this case, used codes PENELOPE MCNP5, based on the Monte Carlo method for x-ray spectrum taking into account the characteristics of the x-ray tube. In order to achieve a greater fit of simulated by the theoretical spectrum. It carried out a sensitivity analysis of the parameters available in both codes. The obtaining of the simulated spectrum could lead to an improvement in quality control of the x-ray tube to incorporate it as a method complementary to techniques.
Directory of Open Access Journals (Sweden)
C. Stolle
2004-06-01
Full Text Available To obtain a comprehensive view on high latitude processes by applying different observation techniques, the SIRCUS campaign was initiated in 2001/2002. This paper compares electron density profiles derived from CHAMP radio occultation data and those measured with the EISCAT facility. Since ionospheric profiling with the help of space-based received GPS is a relatively new technique, validations with established independent instruments are of crucial need. We present 28 profiling events for quasi-statistical analyses, which occurred during the SIRCUS campaigns and describe some of them in more detail. We found out that the majority of profile comparisons in electron density peak value and height, as well as in TEC, lie within the error ranges of the two methods. Differences in the ionospheric quantities do not necessarily occur when the locations of the occultation and of the radar site show considerable distances. Differences are more pronounced when the ionosphere is remarkably structured.
Energy Technology Data Exchange (ETDEWEB)
Zuehlsdorff, T. J., E-mail: tjz21@cam.ac.uk; Payne, M. C. [Cavendish Laboratory, J. J. Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Hine, N. D. M. [Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); Haynes, P. D. [Department of Materials, Imperial College London, Exhibition Road, London SW7 2AZ (United Kingdom); Department of Physics, Imperial College London, Exhibition Road, London SW7 2AZ (United Kingdom); Thomas Young Centre for Theory and Simulation of Materials, Imperial College London, Exhibition Road, London SW7 2AZ (United Kingdom)
2015-11-28
We present a solution of the full time-dependent density-functional theory (TDDFT) eigenvalue equation in the linear response formalism exhibiting a linear-scaling computational complexity with system size, without relying on the simplifying Tamm-Dancoff approximation (TDA). The implementation relies on representing the occupied and unoccupied subspaces with two different sets of in situ optimised localised functions, yielding a very compact and efficient representation of the transition density matrix of the excitation with the accuracy associated with a systematic basis set. The TDDFT eigenvalue equation is solved using a preconditioned conjugate gradient algorithm that is very memory-efficient. The algorithm is validated on a small test molecule and a good agreement with results obtained from standard quantum chemistry packages is found, with the preconditioner yielding a significant improvement in convergence rates. The method developed in this work is then used to reproduce experimental results of the absorption spectrum of bacteriochlorophyll in an organic solvent, where it is demonstrated that the TDA fails to reproduce the main features of the low energy spectrum, while the full TDDFT equation yields results in good qualitative agreement with experimental data. Furthermore, the need for explicitly including parts of the solvent into the TDDFT calculations is highlighted, making the treatment of large system sizes necessary that are well within reach of the capabilities of the algorithm introduced here. Finally, the linear-scaling properties of the algorithm are demonstrated by computing the lowest excitation energy of bacteriochlorophyll in solution. The largest systems considered in this work are of the same order of magnitude as a variety of widely studied pigment-protein complexes, opening up the possibility of studying their properties without having to resort to any semiclassical approximations to parts of the protein environment.
Zuehlsdorff, T. J.; Hine, N. D. M.; Payne, M. C.; Haynes, P. D.
2015-11-01
We present a solution of the full time-dependent density-functional theory (TDDFT) eigenvalue equation in the linear response formalism exhibiting a linear-scaling computational complexity with system size, without relying on the simplifying Tamm-Dancoff approximation (TDA). The implementation relies on representing the occupied and unoccupied subspaces with two different sets of in situ optimised localised functions, yielding a very compact and efficient representation of the transition density matrix of the excitation with the accuracy associated with a systematic basis set. The TDDFT eigenvalue equation is solved using a preconditioned conjugate gradient algorithm that is very memory-efficient. The algorithm is validated on a small test molecule and a good agreement with results obtained from standard quantum chemistry packages is found, with the preconditioner yielding a significant improvement in convergence rates. The method developed in this work is then used to reproduce experimental results of the absorption spectrum of bacteriochlorophyll in an organic solvent, where it is demonstrated that the TDA fails to reproduce the main features of the low energy spectrum, while the full TDDFT equation yields results in good qualitative agreement with experimental data. Furthermore, the need for explicitly including parts of the solvent into the TDDFT calculations is highlighted, making the treatment of large system sizes necessary that are well within reach of the capabilities of the algorithm introduced here. Finally, the linear-scaling properties of the algorithm are demonstrated by computing the lowest excitation energy of bacteriochlorophyll in solution. The largest systems considered in this work are of the same order of magnitude as a variety of widely studied pigment-protein complexes, opening up the possibility of studying their properties without having to resort to any semiclassical approximations to parts of the protein environment.
Khemani, Vedika; Pollmann, Frank; Sondhi, S L
2016-06-17
The eigenstates of many-body localized (MBL) Hamiltonians exhibit low entanglement. We adapt the highly successful density-matrix renormalization group method, which is usually used to find modestly entangled ground states of local Hamiltonians, to find individual highly excited eigenstates of MBL Hamiltonians. The adaptation builds on the distinctive spatial structure of such eigenstates. We benchmark our method against the well-studied random field Heisenberg model in one dimension. At moderate to large disorder, the method successfully obtains excited eigenstates with high accuracy, thereby enabling a study of MBL systems at much larger system sizes than those accessible to exact-diagonalization methods.
Directory of Open Access Journals (Sweden)
Hiroshi Yoshihara
2014-06-01
Full Text Available The Mode I critical stress intensity factor (KIc obtained by single-edge-notched bending (SENB tests of medium-density fiberboard (MDF was experimentally analyzed. In the SENB test, the critical load for crack propagation (Pc was determined from the relationship between load/loading-line displacement and load/crack opening displacement (COD. A double cantilever beam (DCB test was also conducted and the results were compared with those of SENB tests. The value of Mode I critical stress intensity factor was obtained by introducing an additional crack length, when the crack length ranged from 0.5 to 0.7 times the depth of the specimen. This range coincided well with that used to derive the appropriate KIc value in the single-edge-notched tension (SENT test, which was conducted using the specimens with a similar confi guration cut from the MDF panel used in this study.
Guidorzi, C; Amati, L; Campana, S; Orlandini, M; Romano, P; Stamatikos, M; Tagliaferri, G
2012-01-01
We calculate the average power density spectra (PDS) of 244 long gamma-ray bursts detected with the Swift Burst Alert Telescope in the 15-150 keV band from January 2005 to August 2011. For the first time we derived the average PDS in the source rest frame of 97 GRBs with known redshift. For 49 of them an average PDS was also obtained in a common source-frame energy band to account for the dependence of time profiles on energy. Previous results obtained on BATSE GRBs with unknown redshift showed that the average spectrum in the 25-2000 keV band could be modelled with a power-law with a 5/3 index over nearly two decades of frequency with a break at ~1 Hz. Depending on the normalisation and on the subset of GRBs considered, our results show analogous to steeper slopes (between 1.7 and 2.0) of the power-law. However, no clear evidence for the break at ~1 Hz was found, although the softer energy band of BAT compared with BATSE might account for that. We instead find a break at lower frequency corresponding to a ty...
Hirano, Y; Kiyama, S; Fujiwara, Y; Koguchi, H; Sakakita, H
2015-11-01
A high current density (≈3 mA/cm(2)) hydrogen ion beam source operating in an extremely low-energy region (E(ib) ≈ 150-200 eV) has been realized by using a transition to a highly focused state, where the beam is extracted from the ion source chamber through three concave electrodes with nominal focal lengths of ≈350 mm. The transition occurs when the beam energy exceeds a threshold value between 145 and 170 eV. Low-level hysteresis is observed in the transition when E(ib) is being reduced. The radial profiles of the ion beam current density and the low temperature ion current density can be obtained separately using a Faraday cup with a grid in front. The measured profiles confirm that more than a half of the extracted beam ions reaches the target plate with a good focusing profile with a full width at half maximum of ≈3 cm. Estimation of the particle balances in beam ions, the slow ions, and the electrons indicates the possibility that the secondary electron emission from the target plate and electron impact ionization of hydrogen may play roles as particle sources in this extremely low-energy beam after the compensation of beam ion space charge.
Hashimoto, Y.; Shimizu, C.; Kishi, S.; Chao, Y. E.; Wan-Chung, L.
2016-12-01
Changes in stress state with seismic cycles are significant to understand the magnitude and nature of earthquakes. 1999 Chi-Chi earthquake occurred along the Chelung-pu fault, Taiwan. Structural data was obtained from core samples from Taiwan Chelung-pu fault Drilling Project (TCDP). Paleo-stress analysis revealed that the paleo-stress changes between horizontal compression and horizontal extension, which possibly corresponds to stress change before and after earthquake (Hashimoto et al., 2015). The microfault inversion analysis provided an opportunity to classify the micro-faults corresponding to the stress state before and after earthquake. In this study, we have analyzed roughness of micro-faults using power spectrum density and Hurst exponent to understand the roughness change with seismic cycles. Micro-faults were classified into two groups related to stress state before and after earthquake using misfit angle. Misfit angle is the angle between calculated slip direction and observed slip direction for each estimated stress state. Microfaults were sampled from TCDP core. 12 of each samples for horizontal compression and horizontal extension stress state were analyzed. 3D surface data of the slip surface of microfaults were obtained by 3D macro scope (Keyence, VR-3200). Three lines in a surface were analyzed to get power spectrum density-wave number relationships. Hurst exponent is a parameter related to a slope of a log-linear decreasing line in power spectrum density-wave number relationship. Power spectrum density before earthquake is smaller than that after earthquake. Hurst exponent is constant around 0.73-0.75 both in the stress states before and after earthquake. The differences between the directions parallel or vertical to the slip direction were not observed. These results suggest that amplitude decreases with slip at the time of horizontal compression (stress state before earthquake) at to keep the slope in power spectrum density-wave number
Reduced-density-matrix spectrum and block entropy of permutationally invariant many-body systems.
Salerno, Mario; Popkov, Vladislav
2010-07-01
Spectral properties of the reduced density matrix (RDM) of permutational invariant quantum many-body systems are investigated. The RDM block diagonalization which accounts for all symmetries of the Hamiltonian is achieved. The analytical expression of the RDM spectrum is provided for arbitrary parameters and rigorously proved in the thermodynamical limit. The existence of several sum rules and recurrence relations among RDM eigenvalues is also demonstrated and the distribution function of RDM eigenvalues (including degeneracies) characterized. In particular, we prove that the distribution function approaches a two-dimensional Gaussian in the limit of large subsystem sizes n>1. As a physical application we discuss the von Neumann entropy (VNE) of a block of size n for a system of hard-core bosons on a complete graph, as a function of n and of the temperature T. The occurrence of a crossover of VNE from purely logarithmic behavior at T=0 to a purely linear behavior in n for T≥Tc, is demonstrated.
Roke, Y.; Harten, P.N. van; Buitelaar, J.K.; Tenback, D.E.; Quekel, L.G.; Rijke, Y.B. de; Boot, A.M.
2012-01-01
OBJECTIVE: To investigate the long-term effects of antipsychotic (AP) treatment and AP-induced hyperprolactinemia on bone mineral density (BMD) and body composition in male adolescents with autism spectrum disorders (ASDs) and/or disruptive behavior disorder (DBD). DESIGN: Physically healthy 10- to
Y. Roke (Yvette); P.N. van Harten (Peter); J.K. Buitelaar (Jan); D.E. Tenback (Diederik); L.G.B.A. Quekel (Lorentz G. B.); Y.B. de Rijke (Yolanda); A.M. Boot (Annemieke)
2012-01-01
textabstractObjective: To investigate the long-term effects of antipsychotic (AP) treatment and AP-induced hyperprolactinemia on bone mineral density (BMD) and body composition in male adolescents with autism spectrum disorders (ASDs) and/or disruptive behavior disorder (DBD). Design: Physically hea
Roke, Yvette; van Harten, Peter N.; Buitelaar, Jan K.; Tenback, Diederik E.; Quekel, Lorentz G. B. A.; de Rijke, Yolanda B.; Boot, Annemieke M.
2012-01-01
Objective: To investigate the long-term effects of antipsychotic (AP) treatment and AP-induced hyperprolactinemia on bone mineral density (BMD) and body composition in male adolescents with autism spectrum disorders (ASDs) and/or disruptive behavior disorder (DBD). Design: Physically healthy 10- to
Hannah, I G; Reid, H A S
2012-01-01
To demonstrate the effect of turbulent background density fluctuations on flare accelerated electron transport in the solar corona. Using the quasi-linear approximation, we numerically simulate the propagation of a beam of accelerated electrons from the solar corona to chromosphere, including the self-consistent response of the inhomogeneous background plasma in the form of Langmuir waves. We calculate the X-ray spectrum from these simulations using the bremsstrahlung cross-section and fit the footpoint spectrum using the collisional "thick-target" model, a standard approach adopted in observational studies. We find that the interaction of the Langmuir waves with the background electron density gradient shifts the waves to higher phase velocity where they then resonate with higher velocity electrons. The consequence is that some of the electrons are shifted to higher energies, producing more high energy X-rays than expected in the cases where the density inhomogeneity is not considered. We find that the level...
Chaudhuri, Ratan K; Lascu, Zoia; Puccetti, Germain; Deshpande, Anant A; Paknikar, Sashikumar K
2006-01-01
Di-2,2'-diethylhexyl-3,5-dimethoxy-4-hydroxy-benzylidenemalonate (INCI name diethylhexyl syringylidene malonate, DESM), the target photostabilizer, was synthesized in one step by condensation of 3,5-dimethoxy-4-hydroxy benzaldehyde (Syringaldehyde) with di-2,2'-diethylhexyl malonate. Photostability data in sunscreen formulations showed that DESM is photostable and improves the photostability of avobenzone significantly when compared to control (without a photostabilizer). Photostable broad-spectrum sunscreen formulations with high SPF (>30) have been achieved by combining avobenzone, DESM and UV-B sunscreens, such as homosalate, octisalate or other UV-B sunscreens. It seems that (a) triplet-state energy transfer from avobenzone to DESM and (b) scavenging of reactive species are responsible for the observed stabilization of avobenzone. In vitro study of the two formulations containing DESM clearly showed critical wavelength of well over 370 nm and can thus be categorized as broad-spectrum sunscreens. DESM does not have any contribution to in vivo SPF; instead it boosts SPF by about 5 units in high-SPF products. DESM was found to be an excellent singlet-oxygen quencher, thereby reducing photodegradation of avobenzone caused by singlet oxygen. In short, the multiplicity of effects and formulation benefits seen with DESM makes it an ideal choice as a unique antioxidant photostabilizer for a variety of cosmetic products targeting young and mature skin alike.
Directory of Open Access Journals (Sweden)
César Augusto Guevara-Cuéllar
2010-12-01
Full Text Available Introduction: Although the levels of low-density lipoprotein (LDL-C should ideally be determined by beta quantification or enzymatic methods, there are limitations in developing countries. The goal of this study is to compare LDL-C obtained through three formulae (LDL-Cnf with LDL-C obtained through the Friedewald formula (LDL-Cf using LDL-C through enzymatic methods as the most-accepted reference method in clinical practice (LDL-Cr.Methods: A concordance study was carried out in a reference laboratory in Cali, Colombia. The three formulae were (mg/dl: Men with triglycerides under 400 mg/dl: LDL-C = Total Cholesterol (TC - triglycerides (TG /6.5 - 45; men with triglycerides equal to or greater than 400 mg/dl: LDL-C = (TC - (TG / 7 -50 and women: LDL-C = (TC-(TG /6.5 - 70.Results: Three-hundred fifteen values were obtained of which 53% were for women. The mean age and LDL-Cr were 54 years (±15.8 and 112.1 mg/dl (±32.5, respectively. The median (interquartile range, mg/dl of TC, high-density lipoprotein (HDL-C and TG were 204 mg/dl (171-229, 51 mg/dl (41-61, and 156 mg/dl (99-237, respectively. There were no differences between mean values of LDL-Cr and LDL-Cnf (113.48 vs. 112.67 mg/dl; p=0.45. The intraclass correlation coefficient among LDL-Cr and LDL-Cf and LDL-Cnf were high (R=0.93 and 0.92, respectively. The correlation between LDL-Cf and LDL-Cnf was 0.95. There is no difference between the areas under the receiver operating characteristic (ROC curve with the level of LDL-Cr at 160 mg/dl for LDL-Cnf and LDL-Cf. (0.94 vs. 0.93; p=0.27.Conclusion: There is high concordance between LDL-Cf and LDL-Cnf. These formulae could be an alternative when there are limitations to determine LDL-C because of the lack of enzymatic methods or through Friedewald formula due to the absence of HDL-C.
Directory of Open Access Journals (Sweden)
César Augusto Guevara-Amador
2011-01-01
Full Text Available Introduction: Although the levels of low-density lipoprotein (LDL-C should ideally be determined by beta quantification or enzymatic methods, there are limitations in developing countries. The goal of this study is to compare LDL-C obtained through three formulae (LDL-Cnf with LDL-C obtained through the Friedewald formula (LDL-Cf using LDL-C through enzymatic methods as the most-accepted reference method in clinical practice (LDL-Cr. Methods: A concordance study was carried out in a reference laboratory in Cali, Colombia. The three formulae were (mg/dl: Men with triglycerides under 400 mg/dl: LDL-C = Total Cholesterol (TC - triglycerides (TG /6.5 - 45; men with triglycerides equal to or greater than 400 mg/dl: LDL-C = (TC - (TG / 7 -50 and women: LDL-C = (TC-(TG /6.5 - 70. Results: Three-hundred fifteen values were obtained of which 53% were for women. The mean age and LDL-Cr were 54 years (±15.8 and 112.1 mg/dl (±32.5, respectively. The median (interquartile range, mg/dl of TC, high-density lipoprotein (HDL-C and TG were 204 mg/dl (171-229, 51 mg/dl (41-61, and 156 mg/dl (99-237, respectively. There were no differences between mean values of LDL-Cr and LDL-Cnf (113.48 vs. 112.67 mg/dl; p=0.45. The intraclass correlation coefficient among LDL-Cr and LDL-Cf and LDL-Cnf were high (R=0.93 and 0.92, respectively. The correlation between LDL-Cf and LDL-Cnf was 0.95. There is no difference between the areas under the receiver operating characteristic (ROC curve with the level of LDL-Cr at 160 mg/dl for LDL-Cnf and LDL-Cf. (0.94 vs. 0.93; p=0.27. Conclusion: There is high concordance between LDL-Cf and LDL-Cnf. These formulae could be an alternative when there are limitations to determine LDL-C because of the lack of enzymatic methods or through Friedewald formula due to the absence of HDL-C.
Charge-Density-Excitation Spectrum in the t-t'-J-V Model
Greco, Andrés; Yamase, Hiroyuki; Bejas, Matías
2017-03-01
We study the density-density correlation function in a large-N scheme of the t-t'-J-V model. When the nearest-neighbor Coulomb interaction V is zero, our model exhibits phase separation in a wide doping region and we obtain large spectral weight near momentum q = (0,0) at low energy, which originates from the proximity to phase separation. These features are much stronger for electron doping than for hole doping. However, once phase separation is suppressed by including a finite V, the low-energy spectral weight around q = (0,0) is substantially suppressed. Instead a sharp zero-sound mode is stabilized above the particle-hole continuum. We discuss that the presence of a moderate value of V, which is frequently neglected in the t-J model, is important to understand low-energy charge excitations especially close to q = (0,0) for electron doping. This insight should be taken into account in a future study of x-ray scattering measurements.
1–2.4 μm Near-IR Spectrum of the Giant Planet β Pictoris b Obtained with the Gemini Planet Imager
Chilcote, Jeffrey; Pueyo, Laurent; De Rosa, Robert J.; Vargas, Jeffrey; Macintosh, Bruce; Bailey, Vanessa P.; Barman, Travis; Bauman, Brian; Bruzzone, Sebastian; Bulger, Joanna; Burrows, Adam S.; Cardwell, Andrew; Chen, Christine H.; Cotten, Tara; Dillon, Daren; Doyon, Rene; Draper, Zachary H.; Duchêne, Gaspard; Dunn, Jennifer; Erikson, Darren; Fitzgerald, Michael P.; Follette, Katherine B.; Gavel, Donald; Goodsell, Stephen J.; Graham, James R.; Greenbaum, Alexandra Z.; Hartung, Markus; Hibon, Pascale; Hung, Li-Wei; Ingraham, Patrick; Kalas, Paul; Konopacky, Quinn; Larkin, James E.; Maire, Jérôme; Marchis, Franck; Marley, Mark S.; Marois, Christian; Metchev, Stanimir; Millar-Blanchaer, Maxwell A.; Morzinski, Katie M.; Nielsen, Eric L.; Norton, Andrew; Oppenheimer, Rebecca; Palmer, David; Patience, Jennifer; Perrin, Marshall; Poyneer, Lisa; Rajan, Abhijith; Rameau, Julien; Rantakyrö, Fredrik T.; Sadakuni, Naru; Saddlemyer, Leslie; Savransky, Dmitry; Schneider, Adam C.; Serio, Andrew; Sivaramakrishnan, Anand; Song, Inseok; Soummer, Remi; Thomas, Sandrine; Wallace, J. Kent; Wang, Jason J.; Ward-Duong, Kimberly; Wiktorowicz, Sloane; Wolff, Schuyler
2017-04-01
Using the Gemini Planet Imager located at Gemini South, we measured the near-infrared (1.0–2.4 μm) spectrum of the planetary companion to the nearby, young star β Pictoris. We compare the spectrum obtained with currently published model grids and with known substellar objects and present the best matching models as well as the best matching observed objects. Comparing the empirical measurement of the bolometric luminosity to evolutionary models, we find a mass of 12.9 ± 0.2 {{ M }}{Jup}, an effective temperature of 1724 ± 15 K, a radius of 1.46 ± 0.01 {{ R }}{Jup}, and a surface gravity of {log}g=4.18+/- 0.01 [dex] (cgs). The stated uncertainties are statistical errors only, and do not incorporate any uncertainty on the evolutionary models. Using atmospheric models, we find an effective temperature of 1700–1800 K and a surface gravity of {log}g=3.5–4.0 [dex] depending upon the model. These values agree well with other publications and with “hot-start” predictions from planetary evolution models. Further, we find that the spectrum of β Pic b best matches a low surface gravity L2 ± 1 brown dwarf. Finally, comparing the spectrum to field brown dwarfs, we find the the spectrum best matches 2MASS J04062677–381210 and 2MASS J03552337+1133437.
Energy Technology Data Exchange (ETDEWEB)
Rey-Ronco, M.A., E-mail: rey@uniovi.e [Departamento de Energia, Universidad de Oviedo, 33004 Oviedo (Spain); Alonso-Sanchez, T., E-mail: tjalonso@uniovi.e [Departamento de Explotacion y Prospeccion de Minas, Universidad de Oviedo, 33004 Oviedo (Spain); Castro-Garcia, M.P., E-mail: UO21947@uniovi.e [Departamento de Explotacion y Prospeccion de Minas, Universidad de Oviedo, 33004 Oviedo (Spain)
2010-09-15
In this paper, we show a procedure for producing {sup 16}N and a method to obtain its gamma spectrum with a NaI(Tl) detector. We also demonstrate the interest of this radioactive element for the purpose of NaI(Tl) detector calibration and for the determination of fluorine in geological specimens using an Alpha Beryllium neutron source. This work consists of a theoretical study which analyzes the characteristics of {sup 16}N and nuclear reactions that originate from an Americium Beryllium source of 1Ci activity. We justify our choice of reaction {sup 19}F(n,{alpha}){sup 16}N and the use of fluorspar as a source of fluorine. The mathematical procedure followed to obtain the gamma rays spectrum produced by {sup 16}N in a NaI(Tl) detector is shown.
Institute of Scientific and Technical Information of China (English)
ZHUANG You-Yi; ZHANG Yao-Ju
2009-01-01
A new design is presented to improve the magnetic recording density in all-optical magnetic storage.By using the high numerical lens with a high-pass angular spectrum filter, circularly polarized laser pulses are focused into the magneto-optic film with the perpendicular anisotropy.Magnetization of the film is induced by the inverse Faraday effect.As the obstructed angle of the filter increases the magnetic recording density increases evidently.The magnetization intensity and the sidelobe effect are also discussed.
DEFF Research Database (Denmark)
R. Goicoechea, Javier; Cernicharo, J.; Karska, A.
2012-01-01
We present the first complete 55-671 um spectral scan of a low-mass Class 0 protostar (Serpens SMM1) taken with the PACS and SPIRE spectrometers on board Herschel. More than 145 lines have been detected, most of them rotationally excited lines of 12CO (full ladder from J=4-3 to 42-41), H2O, OH, 13......(warm)~375 K and Tk(cool)~150 K). Gas densities n(H2)~5x10^6 cm^-3 are needed to reproduce the observed far-IR lines arising from shocks in the inner protostellar envelope for which we derive upper limit abundances of x(CO)~10^-4, x(H2O)~0.2x10^-5 and x(OH)~10^-6. The lower energy submm 12CO and H2O lines...
The effects of high density on the X-ray spectrum reflected from accretion discs around black holes
García, Javier A.; Fabian, Andrew C.; Kallman, Timothy R.; Dauser, Thomas; Parker, Michael L.; McClintock, Jeffrey E.; Steiner, James F.; Wilms, Jörn
2016-10-01
Current models of the spectrum of X-rays reflected from accretion discs around black holes and other compact objects are commonly calculated assuming that the density of the disc atmosphere is constant within several Thomson depths from the irradiated surface. An important simplifying assumption of these models is that the ionization structure of the gas is completely specified by a single, fixed value of the ionization parameter ξ, which is the ratio of the incident flux to the gas density. The density is typically fixed at ne = 1015 cm-3. Motivated by observations, we consider higher densities in the calculation of the reflected spectrum. We show by computing model spectra for ne ≳ 1017 cm-3 that high-density effects significantly modify reflection spectra. The main effect is to boost the thermal continuum at energies ≲ 2 keV. We discuss the implications of these results for interpreting observations of both active galactic nuclei and black hole binaries. We also discuss the limitations of our models imposed by the quality of the atomic data currently available.
Dunn, H. J.
1981-01-01
A computer program for performing frequency analysis of time history data is presented. The program uses circular convolution and the fast Fourier transform to calculate power density spectrum (PDS) of time history data. The program interfaces with the advanced continuous simulation language (ACSL) so that a frequency analysis may be performed on ACSL generated simulation variables. An example of the calculation of the PDS of a Van de Pol oscillator is presented.
Early Structure Formation from Primordial Density Fluctuations with a Blue, Tilted Power Spectrum
Hirano, Shingo; Zhu, Nick; Yoshida, Naoki; Spergel, David; Yorke, Harold W.
2015-11-01
While observations of large-scale structure and the cosmic microwave background (CMB) provide strong constraints on the amplitude of the primordial power spectrum (PPS) on scales larger than 10 Mpc, the amplitude of the power spectrum on sub-galactic length scales is much more poorly constrained. We study early structure formation in a cosmological model with a blue-tilted PPS. We assume that the standard scale-invariant PPS is modified at small length scales as P(k)∼ {k}{m{{s}}} with ms > 1. We run a series of cosmological hydrodynamic simulations to examine the dependence of the formation epoch and the characteristic mass of primordial stars on the tilt of the PPS. In models with ms > 1, star-forming gas clouds are formed at z > 100 when the formation of hydrogen molecules is inefficient because the intense CMB radiation destroys chemical intermediates. Without efficient coolant, the gas clouds gravitationally contract while retaining a high temperature. The protostars formed in such “hot” clouds grow very rapidly through accretion to become extremely massive stars that may leave massive black holes with a few hundred solar masses at z > 100. The shape of the PPS critically affects the properties and the formation epoch of the first generation of stars. Future experiments on CMB polarization and spectrum distortion may provide important information on the nature of the first stars and their formation epoch, and hence on the shape of the small-scale power spectrum.
Cortical Serotonin Type-2 Receptor Density in Parents of Children with Autism Spectrum Disorders
Goldberg, Jeremy; Anderson, George M.; Zwaigenbaum, Lonnie; Hall, Geoffrey B. C.; Nahmias, Claude; Thompson, Ann; Szatmari, Peter
2009-01-01
Parents (N = 19) of children with autism spectrum disorders (ASD) and adult controls (N = 17) underwent positron emission tomography (PET) using [[superscript 18]F]setoperone to image cortical serotonin type-2 (5-HT2) receptors. The 5-HT2 binding potentials (BPs) were calculated by ratioing [[superscript 18]F]setoperone intensity in regions of…
Institute of Scientific and Technical Information of China (English)
LI Hui; ZHOU TuanHui; LI JingWei; SHEN JinHua; JI HaiSheng; NI HouKun; ZHANG HaiYing; ZHANG YaNan; LIU HongRui; DENG YuanYong; WANG DongGuang; DU QiuSheng
2009-01-01
The flash spectra in the Hel D3 line were obtained during the 2008 total solar eclipse. This paper describes the instrument and the calibration of the obtained flash spectrum, and presents our initial results.The average integrated intensity is E_(ave)=8.13×10~(13)erg·cm~(-1)·s~(-1)·ster~(-1)ath=1100km,which confirms that the Hel D3 emission is negatively correlated with the solar activity. The surface brightness reaches a maximum of F_(ave)=8.25×10~5 erg·cm~(-2)·s~(-1)·ster(-1) at about h≈(1290±75) km and then decreases exponentially with height when h > 1800 km with an exponential index β= 1.63×10~(-8)cm~(-1).
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
The flash spectra in the HeI D3 line were obtained during the 2008 total solar eclipse. This paper describes the instrument and the calibration of the obtained flash spectrum, and presents our initial results. The average integrated intensity is Eave = 8.13×1013 erg·cm-1· s-1·ster-1 at h = 1100 km, which confirms that the HeI D3 emission is negatively correlated with the solar activity. The surface brightness reaches a maximum of F ave = 8.25×105 erg·cm-2·s-1·ster-1 at about h ≈ (1290 ± 75) km and then decreases exponentially with height when h >1800 km with an exponential index β = 1.63×10-8 cm-1.
Chen, Lin; Ren, Jing; Guo, Fan; Zhou, LiangJi; Li, Ye; He, An; Jiang, Wei
2014-03-01
To understand the formation process of vacuum gap in coaxial microsecond conduction time plasma opening switch (POS), we have made measurements of the line-integrated plasma density during switch operation using a time-resolved sensitive He-Ne interferometer. The conduction current and conduction time in experiments are about 120 kA and 1 μs, respectively. As a result, more than 85% of conduction current has been transferred to an inductive load with rise time of 130 ns. The radial dependence of the density is measured by changing the radial location of the line-of-sight for shots with the same nominal POS parameters. During the conduction phase, the line-integrated plasma density in POS increases at all radial locations over the gun-only case by further ionization of material injected from the guns. The current conduction is observed to cause a radial redistribution of the switch plasma. A vacuum gap forms rapidly in the plasma at 5.5 mm from the center conductor, which is consistent with the location where magnetic pressure is the largest, allowing current to be transferred from the POS to the load.
Early structure formation from primordial density fluctuations with a blue-tilted power spectrum
Hirano, Shingo; Yoshida, Naoki; Spergel, David; Yorke, Harold W
2015-01-01
While observations of large-scale structure and the cosmic microwave background (CMB) provide strong constraints on the amplitude of the primordial power spectrum (PPS) on scales larger than 10 Mpc, the amplitude of the power spectrum on sub-galactic length scales is much more poorly constrained. We study early structure formation in a cosmological model with a blue-tilted PPS. We assume that the standard scale-invariant PPS is modified at small length scales as $P(k) \\sim k^{m_{\\rm s}}$ with $m_{\\rm s} > 1$. We run a series of cosmological hydrodynamic simulations to examine the dependence of the formation epoch and the characteristic mass of primordial stars on the tilt of the PPS. In models with $m_{\\rm s} > 1$, star-forming gas clouds are formed at $z > 100$, when formation of hydrogen molecules is inefficient because the intense CMB radiation destroys chemical intermediates. Without efficient coolant, the gas clouds gravitationally contract while keeping a high temperature. The protostars formed in such ...
Binek, Ch.
1998-01-01
In order to provide an experimental access to the statistical theory of Lee and Yang (1952) the density function g(theta) of zeros on the Lee-Yang circle has been determined for the first time by analyzing isothermal magnetization data, m(H), of the Ising ferromagnet FeCl2 in axial magnetic fields, H, at temperatures 34 < T < 99K. The validity of our approach is demonstrated by the perfect agreement of magnetic specific heat data as calculated from g(theta) and m(H) via Maxwells relation, res...
Hartley, Madeline K; Vine, Seanna; Walsh, Elizabeth; Avrantinis, Sara; Daub, G William; Cave, Robert J
2016-03-03
We investigate several representative density functional theory approaches for the calculation of relative activation energies and free energies of a set of model pericyclic reactions, some of which have been studied experimentally. In particular, we use a standard hybrid functional (B3LYP), the same hybrid functional augmented with a basis set superposition error and dispersion correction, a meta-hybrid functional developed to treat transition states and weak interactions (M06-2X), and the recently implemented random phase approximation (RPA) based on Kohn-Sham orbitals from conventional density functional theory by Furche and co-workers. We apply these methods to calculate relative activation energies and estimated free energies for the amide acetal Claisen rearrangement. We focus on relative activation energies to assess the effects of steric and weak interactions in the various methods and compare with experiment where possible. We also discuss the advantages of using this set of reactions as a test bed for the comparison of treatments of weak interactions. We conclude that all methods yield similar trends in relative reactivity, but the RPA yields results in best agreement with the experimental values.
Density Fluctuation Spectrum of Solar Wind Turbulence between Ion and Electron Scales
Chen, C H K; Bonnell, J W; Mozer, F S; Bale, S D
2012-01-01
We present a measurement of the spectral index of density fluctuations between ion and electron scales in solar wind turbulence using the EFI instrument on the ARTEMIS spacecraft. The mean spectral index at 1 AU was found to be -2.75 +/- 0.06, steeper than predictions for pure whistler or kinetic Alfven wave turbulence, but consistent with previous magnetic field measurements. The steep spectra are also consistent with expectations of increased intermittency or damping of some of the turbulent energy over this range of scales. Neither the spectral index nor the flattening of the density spectra before ion scales were found to depend on the proximity to the pressure anisotropy instability thresholds, suggesting that they are features inherent to the turbulent cascade.
Directory of Open Access Journals (Sweden)
I. Morino
2012-11-01
Full Text Available The practical usefulness of a desktop optical spectrum analyzer (OSA for measuring atmospheric CO2 and CH4 column densities at surface sites was examined in two separate measurement campaigns. The first comparison involved operating the OSA in parallel with a high resolution Fourier transform spectroscopy (FTS situated at the University of Wollongong in Australia. Scale factors for the OSA were assigned for the column average volume mixing ratios of xCO2 and xCH4 by comparing with the well-studied FTS. The second method is a calibration against aircraft CO2 profiles in situ over Tsukuba in Japan obtained during a GOSAT validation campaign carried out from 28 January to 7 February 2011. The xCO2 values in the campaign, deduced by use of a derived OSA scale factor, were in excellent agreement with the integrated aircraft profiles.
Directory of Open Access Journals (Sweden)
I. Morino
2012-06-01
Full Text Available The practical usefulness of a desktop optical spectrum analyzer (OSA for measuring atmospheric CO2 and CH4 column densities at surface sites was examined in two separate measurement campaigns. The first involved a long term measurement in parallel with a high resolution Fourier transform spectroscopy (FTS studies at the University of Wollongong in Australia. Scale factors of the OSA were assigned for the column average volume mixing ratios of xCO2 and xCH4 by comparing with the well-studied FTS. The second method is a calibration against aircraft CO2 profiles in situ over Tsukuba in Japan obtained during a GOSAT validation campaign carried out from 28 January to 7 February 2011. The xCO2 values in the campaign, deduced by use of a derived OSA scale factor, were in excellent agreement with the integrated aircraft profiles.
Zhong, Jianfeng; Zhong, Shuncong; Zhang, Qiukun; Zhuang, Yizhou; Lu, Huancai; Fu, Xinbin
2017-01-01
A non-projection fringe vision measurement system suitable for vibration monitoring was proposed by using the concept of a 2D optical coherence vibration tomography (2D-OCVT) technique. An artificial quasi-interferogram fringe pattern (QIFP), similar to the interferogram of the 2D-OCVT system, was pasted onto the surface of a vibrating structure as a sensor. Image sequences of the QIFP were captured by a high-speed CMOS camera that worked as a detector. It was possible to obtain both the in-plane and out-of-plane vibration simultaneously. The in-plane vibration was obtained by tracking the center of the imaged QIFP using an image cross-correlation method, whilst the out-of-plane vibration was obtained from the changes in period density of the imaged QIFP. The influence of the noise sources from the CMOS image sensor, together with the effect of the imaging distance, the period density of the QIFP and also the key parameters of the fringe density enhanced by the spectrum correction method on the accuracy of the displacement measurement, were investigated by numerical simulations and experiments. Compared with the results from a conventional accelerometer-based measurement system, the proposed method was demonstrated to be an effective and accurate technique for measuring structural vibration without introducing any extra mass from the accelerometer. The significant advantages of this method include its simple installation and real-time dynamic response measurement capability, making the measurement system ideal for the low- and high-frequency vibration monitoring of engineering structures.
The pseudo-Goldstone spectrum of 2-colour QCD at finite density
Kogut, J B; Sinclair, D K
2003-01-01
We examine the spectrum of 2-colour lattice QCD with 4 continuum flavours at a finite chemical potential ($\\mu$) for quark-number, on a $12^3 \\times 24$ lattice. First we present evidence that the system undergoes a transition to a state with a diquark condensate, which spontaneously breaks quark number at $\\mu=m_\\pi/2$, and that this transition is mean field in nature. We then examine the 3 states that would be Goldstone bosons at $\\mu=0$ for zero Dirac and Majorana quark masses. The predictions of chiral effective Lagrangians give a good description of the behaviour of these masses for $\\mu < m_\\pi/2$. Except for the heaviest of these states, these predictions diverge from our measurements, once $\\mu$ is significantly greater than $m_\\pi/2$. However, the qualitative behaviour of these masses, indicates that the physics is very similar to that predicted by these effective Lagrangians, and there is some indication that at least part of these discrepancies is due to saturation, a lattice artifact.
Afdala, Adfal; Nuryani, Nuryani; Satrio Nugroho, Anto
2017-01-01
Atrial fibrillation (AF) is a disorder of the heart with fairly high mortality in adults. AF is a common heart arrythmia which is characterized by a missing or irregular contraction of atria. Therefore, finding a method to detect atrial fibrillation is necessary. In this article a system to detect atrial fibrillation has been proposed. Detection system utilized backpropagation artifical neural network. Data input in this method includes power spectrum density of R-peaks interval of electrocardiogram which is selected by wrapping method. This research uses parameter learning rate, momentum, epoch and hidden layer. System produces good performance with accuracy, sensitivity, and specificity of 83.55%, 86.72 % and 81.47 %, respectively.
Chan, Bun; Radom, Leo
2011-09-13
A variety of combinations of B-LYP-based double-hybrid density functional theory (DHDFT) procedures and basis sets have been examined. A general observation is that the optimal combination of exchange contributions is in the proximity of 30% Becke 1988 (B88) exchange and 70% Hartree-Fock (HF) exchange, while for the correlation contributions, the use of independently optimized spin-component-scaled Møller-Plesset second-order perturbation theory (SCS-MP2) parameters (MP2OS and MP2SS) is beneficial. The triple-ζ Dunning aug'-cc-pVTZ+d and Pople 6-311+G(3df,2p)+d basis sets are found to be cost-effective for DHDFT methods. As a result, we have formulated the DuT-D3 DHDFT procedure, which employs the aug'-cc-pVTZ+d basis set and includes 30% B88 and 70% HF exchange energies, 59% LYP, 47% MP2OS, and 36% MP2SS correlation energies, and a D3 dispersion correction with the parameters s6 = 0.5, sr,6 = 1.569, and s8 = 0.35. Likewise, the PoT-D3 DHDFT procedure was formulated with the 6-311+G(3df,2p)+d basis set and has 32% B88 and 68% HF exchange energies, 63% LYP, 46% MP2OS, and 27% MP2SS correlation energies, and the D3 parameters s6 = 0.5, sr,6 = 1.569, and s8 = 0.30. Testing using the large E3 set of 740 energies demonstrates the robustness of these methods. Further comparisons show that the performance of these methods, particularly DuT-D3, compares favorably with the previously reported DSD-B-LYP and DSD-B-LYP-D3 methods used in conjunction with quadruple-ζ aug'-pc3+d and aug'-def2-QZVP basis sets but at lower computational expense. The previously reported ωB97X-(LP)/6-311++G(3df,3pd) procedure also performs very well. Our findings highlight the cost-effectiveness of appropriate- and moderate-sized triple-ζ basis sets in the application of DHDFT procedures.
Characteristics of power spectrum density function of EMG during muscle contraction below 30%MVC.
Roman-Liu, Danuta; Konarska, Maria
2009-10-01
The aim of the study was to quantify changes in PSDF frequency bands of the EMG signal and EMG parameters such as MF, MPF and zero crossing, with an increase in the level of muscle contractions in the range from 0.5% to 30% RMS(max) and to determine the frequency bands with the lowest dependency on RMS level so that this could be used in investigating muscle fatigue. Sixteen men, aged from 23 to 33 years old (mean 26.1), who participated in the study performed two force exertion tests. Fragments of EMG which corresponded to the levels of muscle contraction of 0.5%, 1%, 2.5%, 5%, 10%, 15%, 20%, 25%, 30% RMS(max) registered from left and right trapezius pars descendents (TP) and left and right extensor digitorum superficialis (ED) muscles were selected for analysis. The analysis included changes in standard parameters of the EMG signal and changes in PSDF frequency bands, which occurred across muscle contraction levels. To analyze changes in PSDF across the level of muscle contraction, the spectrum was divided into six frequency bandwidths. The analysis of parameters focused on the differences in those parameters between the analyzed muscles, at different levels of muscle contraction. The study revealed that, at muscle contraction levels below 5% RMSmax, contraction level influences standard parameters of the EMG signal and that at such levels of muscle contraction every change in muscle contraction level (recruitment of additional MUs) is reflected in PSDF. The frequency band with the lowest dependency on contraction level was 76-140 Hz for which in both muscles no contraction level effect was detected for contraction levels above 5% RMS(max). The reproducibility of the results was very high, since the observations in of the left and right muscles were almost equal. The other factor, which strongly influences PSDF of the EMG signal, is probably the examined muscle structure (muscle morphology, size, function, subcutaneous layer, cross talk). It seems that low
Du, Yanjun; Nayak, Gaurav; Oinuma, Gaku; Ding, Yanjun; Peng, Zhimin; Bruggeman, Peter J.
2017-09-01
The measurement of absolute densities of ubiquitous OH radicals and gas temperatures in water containing plasmas has recently drawn a lot of attention. In this paper, we extend the self-absorption model introduced in Du et al 2016 Plasma Sources Sci. Technol. 25 04LT02 with a description of the excited state by a superposition of two Boltzmann distributions to take the non-thermal rotational distribution of the excited state into account. This technique is applied to a diffuse He + H2O RF discharge and it is shown that in addition to the determination of the ground state OH density and rotational temperature, the properties of the excited state OH(A) can also be simultaneously determined. A model of the steady-state distribution of the hot and cold group density of OH(A) is able to describe the dependence of the rotational population distributions of the excited state as a function of the water concentration. The method is also applied to a filamentary Ar + H2O DBD. While the non-homogeneous nature of the DBD leads to complications, the production of OH(A) by multiple production mechanisms leading to a complex nascent rotational population distribution causes the fitting procedure of the emission spectrum (with self-absorption) to break down.
Guan, Jingang; Wang, Fan; Ziegler, Tom; Cox, Hazel
2006-07-28
Orbital energies, ionization potentials, molecular constants, potential energy curves, and the excitation spectrum of O(2) are calculated using time-dependent density functional theory (TDDFT) with Tamm-Dancoff approximation (TDA). The calculated negative highest occupied molecular orbital energy (-epsilon(HOMO)) is compared with the energy difference ionization potential for five exchange correlation functionals consisting of the local density approximation (LDAxc), gradient corrected Becke exchange plus Perdew correlation (B(88X)+P(86C)), gradient regulated asymptotic correction (GRAC), statistical average of orbital potentials (SAOP), and van Leeuwen and Baerends asymptotically correct potential (LB94). The potential energy curves calculated using TDDFT with the TDA at internuclear distances from 1.0 to 1.8 A are divided into three groups according to the electron configurations. The 1pi(u) (4)1pi(g) (2) electron configuration gives rise to the X (3)Sigma(g) (-), a (1)Delta(g), and b (1)Sigma(g) (+) states; the 1pi(u) (3)1pi(g) (3) electron configuration gives rise to the c (1)Sigma(u) (-), C (3)Delta(u), and A (3)Sigma(u) (+) states; and the B (3)Sigma(u) (-), A (1)Delta(u), and f (1)Sigma(u) (+) states are determined by the mixing of two or more electron configurations. The excitation spectrum of the oxygen molecule, calculated with the aforementioned exchange correlation functionals, shows that the results are quite sensitive to the choice of functional. The LDAxc and the B(88X)+P(86C) functionals produce similar spectroscopic patterns with a single strongly absorbing band positioned at 19.82 and 19.72 eV, respectively, while the asymptotically corrected exchange correlation functionals of the SAOP and the LB94 varieties yield similar excitation spectra where the computed strongly absorbing band is located at 16.09 and 16.42 eV, respectively. However, all of the exchange correlation functionals yield only one strongly absorbing band (oscillator strength
Correa, Camila A; Schaye, Joop; Duffy, Alan R
2015-01-01
We explore the relation between the structure and mass accretion histories of dark matter halos using a suite of cosmological simulations. We confirm that the formation time, defined as the time when the virial mass of the main progenitor equals the mass enclosed within the scale radius, correlates strongly with concentration. We provide a semi-analytic model for halo mass history that combines analytic relations with fits to simulations. This model has the functional form, $M(z) = M_{0}(1+z)^{\\alpha}e^{\\beta z}$, where the parameters $\\alpha$ and $\\beta$ are directly correlated with concentration. We then combine this model for the halo mass history with the analytic relations between $\\alpha$, $\\beta$ and the linear power spectrum derived by Correa et al. (2014) to establish the physical link between halo concentration and the initial density perturbation field. Finally, we provide fitting formulas for the halo mass history as well as numerical routines, we derive the accretion rate as a function of halo ma...
Gil-Ramírez, Alicia; Soler-Rivas, Cristina; Rodriguez-Casado, Arantxa; Ruiz-Rodríguez, Alejandro; Reglero, Guillermo; Marín, Francisco Ramón
2015-01-01
Culinary-medicinal mushrooms are able to lower blood cholesterol levels in animal models by different mechanisms. They might impair the endogenous cholesterol synthesis and exogenous cholesterol absorption during digestion. Mushroom extracts, obtained using pressurized water extractions (PWE) from Agaricus bisporus basidiomes, supplemented or not supplemented with selenium, were applied to HepG2 cell cultures to study the expression of 19 genes related to cholesterol homeostasis by low-density arrays (LDA). Only the PWE fractions obtained at 25°C showed 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) inhibitory activity. Besides the enzymatic inhibition, PWE extracts may downregulate some of the key genes involved in the cholesterol homeostasis, such as the squalene synthase gene (FDFT1), since its mRNA expression falls by one third of its initial value. In summary, A. bisporus extracts may also modulate biological cholesterol levels by molecular mechanisms further than the enzymatic way previously reported.
Na, Bomin; Choi, Byoung Wook; Kim, Bumsang
2013-11-01
Computed tomography (CT) is the primary non-invasive imaging technique used for most patients with suspected liver disease. In order to improve liver-specific imaging properties and prevent toxic effects in patients with compromised renal function, we investigated the encapsulation of iodine within ethosomal vesicles. As a first step in the development of novel contrast agents using ethosomes for CT imaging applications, iodine was entrapped within ethosomes and iodine-containing ethosomes of the desired size were obtained by extrusion using a polycarbonate membrane with a defined pore size. Ethosomes containing iodine showed a relatively high CT density, which decreased when they were extruded, due to the rupture and re-formation of the lipid bilayer of the ethosome. However, when a solution with a high iodine concentration was used as a dispersion media during the extrusion process, the decrease in CT density could be prevented. In addition, ethosomes containing iodine were taken up efficiently by macrophages, which are abundant in the liver, and these ethosomes exhibited no cellular toxicity. These results demonstrate that iodine could be entrapped within ethosomal vesicles, giving the ethosomes a relatively high CT density, and that the extrusion technique used in this study could conveniently and reproducibly produce ethosomal vesicles with a desired size. Therefore, ethosomes containing iodine, as prepared in this study, have potential as contrast agents with applications in CT imaging.
Bijay, Biplab; Banik, Prabir; Bhadra, Arunava
2016-09-01
In this work we examine with the help of Monte Carlo simulation whether a consistent primary energy spectrum of cosmic rays emerges from both the experimentally observed total charged particles and muon size spectra of cosmic ray extensive air showers considering primary composition may or may not change beyond the knee of the energy spectrum. It is found that EAS-TOP observations consistently infer a knee in the primary energy spectrum provided the primary is pure unchanging iron whereas no consistent primary spectrum emerges from simultaneous use of the KASCADE observed total charged particle and muon spectra. However, it is also found that when primary composition changes across the knee the estimation of spectral index of total charged particle spectrum is quite tricky, depends on the choice of selection of points near the knee in the size spectrum.
Bijay, Biplab; Bhadra, Arunava
2015-01-01
In this work we examine with the help of Monte Carlo simulation whether a consistent primary energy spectrum of cosmic rays emerges from both the experimentally observed total charged particles and muon size spectra of cosmic ray extensive air showers considering primary composition may or may not change beyond the knee of the energy spectrum. It is found that EAS-TOP observations consistently infer a knee in the primary energy spectrum provided the primary is pure unchanging iron whereas no consistent primary spectrum emerges from simultaneous use of the KASCADE observed total charged particle and muon spectra. However, it is also found that when primary composition changes across the knee the estimation of spectral index of total charged particle spectrum is quite tricky, depends on the choice of selection of points near the knee in the size spectrum.
Perumal, Praveen; Anitha, Kuttae Viswanathan; Reddy, Jetti Ramesh; Muthukumar, Balasubramanium
2016-01-01
PURPOSE This pilot study was to find the influence of complete denture on the brain activity and cognitive function of edentulous patients measured through Electroencephalogram (EEG) signals. MATERIALS AND METHODS The study recruited 20 patients aged from 50 to 60 years requiring complete dentures with inclusion and exclusion criteria. The brain function and cognitive function were analyzed with a mental state questionnaire and a 15-minute analysis of power spectral density of EEG alpha waves. The analysis included edentulous phase and post denture insertion adaptive phase, each done before and after chewing. The results obtained were statistically evaluated. RESULTS Power Spectral Density (PSD) values increased from edentulous phase to post denture insertion adaption phase. The data were grouped as edentulous phase before chewing (EEG p1-0.0064), edentulous phase after chewing (EEG p2-0.0073), post denture insertion adaptive phase before chewing (EEG p3-0.0077), and post denture insertion adaptive phase after chewing (EEG p4-0.0096). The acquired values were statistically analyzed using paired t-test, which showed statistically significant results (P<.05). CONCLUSION This pilot study showed functional improvement in brain function of edentulous patients with complete dentures rehabilitation. PMID:27350852
Tissot, Catherine
2011-01-01
Background: There is general agreement across all interested parties that a process of working together is the best way to determine which school or educational setting is right for an individual child with autism spectrum disorder. In the UK, families and local authorities both desire a constructive working relationship and see this as the best…
Tissot, Catherine
2011-01-01
Background: There is general agreement across all interested parties that a process of working together is the best way to determine which school or educational setting is right for an individual child with autism spectrum disorder. In the UK, families and local authorities both desire a constructive working relationship and see this as the best…
Sagdinc, Seda; Kandemirli, Fatma; Bayari, Sevgi Haman
2007-02-01
Sertraline hydrochloride is a highly potent and selective inhibitor of serotonin (5HT). It is a basic compound of pharmaceutical application for antidepressant treatment (brand name: Zoloft). Ab initio and density functional computations of the vibrational (IR) spectrum, the molecular geometry, the atomic charges and polarizabilities were carried out. The infrared spectrum of sertraline is recorded in the solid state. The observed IR wave numbers were analysed in light of the computed vibrational spectrum. On the basis of the comparison between calculated and experimental results and the comparison with related molecules, assignments of fundamental vibrational modes are examined. The X-ray geometry and experimental frequencies are compared with the results of our theoretical calculations.
Tissot, Catherine
2011-01-01
Background: There is general agreement across all interested parties that a process of working together is the best way to determine which school or educational setting is right for an individual child with autism spectrum disorder. In the UK, families and local authorities both desire a constructive working relationship and see this as the best means by which to reach an agreement to determine where a child should be educated. It has been shown in published works 1 1. Batten and colleague...
Rorai, A; Haehnelt, M G; Carswell, R F; Bolton, J S; Cristiani, S; D'Odorico, V; Cupani, G; Barai, P; Calura, F; Kim, T -S; Pomante, E; Tescari, E; Viel, M
2016-01-01
At low densities the standard ionisation history of the intergalactic medium (IGM) predicts a decreasing temperature of the IGM with decreasing density once hydrogen (and helium) reionisation is complete. Heating the high-redshift, low-density IGM above the temperature expected from photo-heating is difficult, and previous claims of high/rising temperatures in low density regions of the Universe based on the probability density function (PDF) of the opacity in Lyman-$\\alpha$ forest data at $2
Institute of Scientific and Technical Information of China (English)
Norbert MISKOLCZI; Richard SAGI; László BARTHA; Lívia FORCEK
2009-01-01
A new route of utilization of α-olefin rich hydrocarbon fractions obtained by waste polymer pyrolysis was investigated. α-olefin-succinic-anhydride intermediate-based pour point depressant additives for diesel fuel were synthesized, in which reactions needed α-olefins were obtained by pyrolysis of waste high-density polyethylene (HDPE). Fraction of α-olefins was produced by the de-polymerization of plastic waste in a tube reactor at 500℃ in the absence of catalysts and air. C17～22 range of mixtures of olefins and paraffins were separated for synthesis and then, these hydrocarbons were reacted with maleic-anhydride (MA) for formation of α-olefin-succinic-anhydride intermediates. The olefin-rich hydrocarbon fraction contained approximately 60% of olefins, including 90%～95% α-olefins. Other intermediates were produced in the same way by using commercial C20 α-olefin instead of C17～22 olefin mixture. The two different experimental intermediates with number average molecular weights of 1850g/mol and 1760g/mol were reacted with different alcohols: 1-butanol, 1-hexanol, 1-octanol, i-butanol, and c-hexanol to produce their ester derivatives. The synthesized ten experimental pour point depressants were added in different concentrations to conventional diesel fuel, which had no other additive content before. The structure and efficiency of experimental additives were followed by different standardized and non-standardized methods. Results showed that the experimental additives on the basis of the product of waste pyrolysis were able to decrease not only the pour but also the cloud point and cold filter plugging point (CFPP) of diesel fuel, whose effects could be observed even if the concentration of additives was low. Furthermore, all additives had anti-wear and anti-friction effects in diesel fuel.
Cano-Hernández, Karla Sarahí; Nava-Townsend, Santiago; Sánchez-Boiso, Adriana; Sánchez-Urbina, Rocío; Contreras-Ramos, Alejandra; Erdmenger-Orellana, Julio Roberto; Tamayo-Espinosa, Tania; Becerra-Becerra, Rosario; Segura-Stanford, Begoña; Solano-Fiesco, Liborio; Balderrábano-Saucedo, Norma Alicia
2017-09-22
To determine the prevalence and spectrum of diseases that predispose to sudden cardiac death in Mexican children and to identify the main early signs and symptoms that can enable the health personnel to suspect about these diseases and to refer the patients to a tertiary hospital in a timely manner. Incidence, prevalence and prevalence of period as well as early symptoms, clinical data and follow-up are described in all children found with diseases that predispose to sudden cardiac death at The Children's Hospital of Mexico. Fifty-nine patients 8 ± 5 years old, 40 with cardiomyopathies and 19 with inherited arrhythmogenic diseases. The prevalence of period was 9.5/1,000 patients/year. Early more common symptoms were dyspnea, palpitations and syncope. In 9 cases a Mendelian inheritance pattern was found. Three patients died of sudden cardiac death during the period of study. Diseases that predispose to sudden cardiac death in children are not very well known for general and medical community. Every child with dyspnea, palpitations and/or syncope, should refer to the intensive search of this diseases. A complete cardiological evaluation in all members of the family is indicated. Copyright © 2017 Instituto Nacional de Cardiología Ignacio Chávez. Publicado por Masson Doyma México S.A. All rights reserved.
Peverati, Roberto; Truhlar, Donald G
2014-03-13
Kohn-Sham density functional theory is in principle an exact formulation of quantum mechanical electronic structure theory, but in practice we have to rely on approximate exchange-correlation (xc) functionals. The objective of our work has been to design an xc functional with broad accuracy across as wide an expanse of chemistry and physics as possible, leading--as a long-range goal--to a functional with good accuracy for all problems, i.e. a universal functional. To guide our path towards that goal and to measure our progress, we have developed-building on earlier work of our group-a set of databases of reference data for a variety of energetic and structural properties in chemistry and physics. These databases include energies of molecular processes, such as atomization, complexation, proton addition and ionization; they also include molecular geometries and solid-state lattice constants, chemical reaction barrier heights, and cohesive energies and band gaps of solids. For this paper, we gather many of these databases into four comprehensive databases, two with 384 energetic data for chemistry and solid-state physics and another two with 68 structural data for chemistry and solid-state physics, and we test two wave function methods and 77 density functionals (12 Minnesota meta functionals and 65 others) in a consistent way across this same broad set of data. We especially highlight the Minnesota density functionals, but the results have broader implications in that one may see the successes and failures of many kinds of density functionals when they are all applied to the same data. Therefore, the results provide a status report on the quest for a universal functional.
Murakami, K; Matsuda, R; Fujiwara, K
2014-01-01
The objectives of this work using Phaseolus vulgaris were to examine whether the light spectrum incident on mature primary leaves (PLs) is related to leaf-to-leaf systemic regulation of developing trifoliate leaves (TLs) in photosynthetic characteristics, and to investigate the relative importance of spectrum and photosynthetic photon flux density (PPFD) in light-induced systemic regulation. Systemic regulation was induced by altering PPFD and the spectrum of light incident on PLs using a shading treatment and lighting treatments including either white, blue, green or red light-emitting diodes (LEDs). Photosynthetic characteristics were evaluated by measuring the light-limited and light-saturated net photosynthetic rates and the amounts of nitrogen (N), chlorophyll (Chl) and ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco; EC 4.1.1.39). Shading treatment on PLs decreased the amounts of N, Chl and Rubisco of TLs and tended to decrease the photosynthetic rates. However, we observed no systemic effects induced by the light spectrum on PLs in this study, except that a higher amount of Rubisco of TLs was observed when the PLs were irradiated with blue LEDs. Our results imply that photoreceptors in mature leaves have little influence on photosynthetic rates and amounts of N and Chl of developing leaves through systemic regulation, although the possibility of the action of blue light irradiation on the amount of Rubisco cannot be ruled out. Based on these results, we concluded that the light spectrum incident on mature leaves has little systemic effect on developing leaves in terms of photosynthetic characteristics and that the light-induced systemic regulation was largely accounted for by PPFD.
Liakos, Dimitrios G; Neese, Frank
2015-09-08
The recently developed domain-based local pair natural orbital coupled cluster theory with single, double, and perturbative triple excitations (DLPNO-CCSD(T)) delivers results that are closely approaching those of the parent canonical coupled cluster method at a small fraction of the computational cost. A recent extended benchmark study established that, depending on the three main truncation thresholds, it is possible to approach the canonical CCSD(T) results within 1 kJ (default setting, TightPNO), 1 kcal/mol (default setting, NormalPNO), and 2-3 kcal (default setting, LoosePNO). Although thresholds for calculations with TightPNO are 2-4 times slower than those based on NormalPNO thresholds, they are still many orders of magnitude faster than canonical CCSD(T) calculations, even for small and medium sized molecules where there is little locality. The computational effort for the coupled cluster step scales nearly linearly with system size. Since, in many instances, the coupled cluster step in DLPNO-CCSD(T) is cheaper or at least not much more expensive than the preceding Hartree-Fock calculation, it is useful to compare the method against modern density functional theory (DFT), which requires an effort comparable to that of Hartree-Fock theory (at least if Hartree-Fock exchange is part of the functional definition). Double hybrid density functionals (DHDF's) even require a MP2-like step. The purpose of this article is to evaluate the cost vs accuracy ratio of DLPNO-CCSD(T) against modern DFT (including the PBE, B3LYP, M06-2X, B2PLYP, and B2GP-PLYP functionals and, where applicable, their van der Waals corrected counterparts). To eliminate any possible bias in favor of DLPNO-CCSD(T), we have chosen established benchmark sets that were specifically proposed for evaluating DFT functionals. It is demonstrated that DLPNO-CCSD(T) with any of the three default thresholds is more accurate than any of the DFT functionals. Furthermore, using the aug-cc-pVTZ basis set and
Development of a new full-spectrum litho-density logging tool%新型全谱岩性密度测井仪
Institute of Scientific and Technical Information of China (English)
彭晓光; 柏林; 田彦民; 刘东友
2012-01-01
The paper introduces a new full-spectrum lithology density logging tool. It is capable to collect full spectrum data during well logging. This logging tool can generate a complete spectrogram, and provide more stratum information to satisfy users' needs. The logging tool is mainly based on field programmable logic device ( FPGA ) , which is practical for data collecting and processing. The pulse conditioning circuit is designed to ensure the accuracy of detection. In order to ensure real-time data transmission,the dual port RAM is applied with the use of the high-speed AD,which is applicable for data quantizing. This new full-spectrum lithology density logging tool can be widely used in well logging industry because the spectrogram is accurate and the system operation is stable after simulation experiments and system testing.%设计了1种新型全谱岩性密度测井仪.该仪器能在测井过程中对核脉冲信号进行全谱采集,可形成完整谱图,提供更多的地层信息,满足用户需要.该仪器基于现场可编译逻辑器件(FPGA)设计,用于数据采集和数据处理.为保证探测精度设计了脉冲调理电路,同时配合使用高速AD进行数字量化,采用双端口RAM技术保证数据传输的实时性.通过仿真实验和系统测试,仪器测得谱图准确,系统运行稳定,可广泛应用于生产测井.
Peverati, Roberto
2012-01-01
Kohn-Sham density functional theory is in principle an exact formulation of quantum mechanical electronic structure theory, but in practice we have to rely on approximate exchange-correlation (xc) functionals. The objective of our work has been to design an xc functional with broad accuracy across as wide an expanse of chemistry and physics as possible, leading-as a long-range goal-to a functional with good accuracy for all problems, i.e., a universal functional. To guide our path toward that goal and to measure our progress, we have developed-building on earlier work in our group-a set of databases of reference data for a variety of energetic and structural properties in chemistry and physics. These databases include energies of molecular processes such as atomization, complexation, proton addition, and ionization; they also include molecular geometries and solid-state lattice constants, chemical reaction barrier heights, and cohesive energies and band gaps of solids. For the present paper we gather many of ...
Hwang, Jungseek
2016-03-31
We introduce an approximate method which can be used to simulate the optical conductivity data of correlated multiband systems for normal and superconducting cases by taking advantage of a reversed process in comparison to a usual optical data analysis, which has been used to extract the electron-boson spectral density function from measured optical spectra of single-band systems, like cuprates. We applied this method to optical conductivity data of two multiband pnictide systems (Ba0.6K0.4Fe2As2 and LiFeAs) and obtained the electron-boson spectral density functions. The obtained electron-boson spectral density consists of a sharp mode and a broad background. The obtained spectral density functions of the multiband systems show similar properties as those of cuprates in several aspects. We expect that our method helps to reveal the nature of strong correlations in the multiband pnictide superconductors.
Rota, S; Bel, J; Guzzo, L; Peacock, J A; Wilson, M J; Pezzotta, A; de la Torre, S; Garilli, B; Bolzonella, M; Scodeggio, M; Abbas, U; Adami, C; Bottini, D; Cappi, A; Cucciati, O; Davidson, I; Franzetti, P; Fritz, A; Iovino, A; Krywult, J; Brun, V Le; Fèvre, O Le; Mascagni, D; Małek, K; Marulli, F; Percival, W J; Polletta, M; Pollo, A; Tasca, L A M; Tojeiro, R; Vergani, D; Zanichelli, A; Arnouts, S; Branchini, E; Coupon, J; De Lucia, G; Ilbert, O; Moscardini, L; Moutard, T
2016-01-01
We use the final catalogue of the VIMOS Public Extragalactic Redshift Survey (VIPERS) to measure the power spectrum of the galaxy distribution at high redshift, presenting results that extend beyond $z=1$ for the first time. We apply an FFT technique to four independent sub-volumes comprising a total of $51,728$ galaxies at $0.6
The Absorption Spectrum of High-Density Stellar Ejecta in the Line-of-Sight to Eta Carinae
Gull, T R; Bruhweiler, F C; Nielsen, K E; Verner, E; Danks, A
2004-01-01
Using the high dispersion NUV mode of the Space Telescope Imaging Spectrograph (STIS) aboard the Hubble Space Telescope (HST) to observe Eta Carinae, we have resolved and identified over 500 sharp, circumstellar absorption lines of iron-group singly-ionized and neutral elements with ~20 velocity components ranging from -146 km/s to -585 km/s. These lines are from transitions originating from ground and metastable levels as high as 40,000 cm-1 above ground. The absorbing material is located either in dense inhomogeneities in the stellar wind, the warm circumstellar gas immediately in the vicinity of Eta Carinae, or within the cooler foreground lobe of the Homunculus. We have used classical curve-of-growth analysis to derive atomic level populations for FeII at -146 km/s and for TiII at -513 km/s. These populations, plus photoionization and statistical equilibrium modeling, provide electron temperatures, Te, densities, n, and constraints on distances from the stellar source, r. For the -146 km/s component, we d...
van Duijnen, Piet Th; Greene, Shannon N; Richards, Nigel G J
2007-07-28
We report the calculated visible spectrum of [FeIII(PyPepS)2]- in aqueous solution. From all-classical molecular dynamics simulations on the solute and 200 water molecules with a polarizable force field, 25 solute/solvent configurations were chosen at random from a 50 ps production run and subjected the systems to calculations using time-dependent density functional theory (TD-DFT) for the solute, combined with a solvation model in which the water molecules carry charges and polarizabilities. In each calculation the first 60 excited states were collected in order to span the experimental spectrum. Since the solute has a doublet ground state several excitations to states are of type "three electrons in three orbitals," each of which gives rise to a manifold of a quartet and two doublet states which cannot properly be represented by single Slater determinants. We applied a tentative scheme to analyze this type of spin contamination in terms of Delta and Delta transitions between the same orbital pairs. Assuming the associated states as pure single determinants obtained from restricted calculations, we construct conformation state functions (CFSs), i.e., eigenfunctions of the Hamiltonian Sz and S2, for the two doublets and the quartet for each Delta,Delta pair, the necessary parameters coming from regular and spin-flip calculations. It appears that the lower final states remain where they were originally calculated, while the higher states move up by some tenths of an eV. In this case filtering out these higher states gives a spectrum that compares very well with experiment, but nevertheless we suggest investigating a possible (re)formulation of TD-DFT in terms of CFSs rather than determinants.
Fransson, Thomas; Burdakova, Daria; Norman, Patrick
2016-05-21
X-ray absorption spectra of carbon, silicon, germanium, and sulfur compounds have been investigated by means of damped four-component density functional response theory. It is demonstrated that a reliable description of relativistic effects is obtained at both K- and L-edges. Notably, an excellent agreement with experimental results is obtained for L2,3-spectra-with spin-orbit effects well accounted for-also in cases when the experimental intensity ratio deviates from the statistical one of 2 : 1. The theoretical results are consistent with calculations using standard response theory as well as recently reported real-time propagation methods in time-dependent density functional theory, and the virtues of different approaches are discussed. As compared to silane and silicon tetrachloride, an anomalous error in the absolute energy is reported for the L2,3-spectrum of silicon tetrafluoride, amounting to an additional spectral shift of ∼1 eV. This anomaly is also observed for other exchange-correlation functionals, but it is seen neither at other silicon edges nor at the carbon K-edge of fluorine derivatives of ethene. Considering the series of molecules SiH4-XFX with X = 1, 2, 3, 4, a gradual divergence from interpolated experimental ionization potentials is observed at the level of Kohn-Sham density functional theory (DFT), and to a smaller extent with the use of Hartree-Fock. This anomalous error is thus attributed partly to difficulties in correctly emulating the electronic structure effects imposed by the very electronegative fluorines, and partly due to inconsistencies in the spurious electron self-repulsion in DFT. Substitution with one, or possibly two, fluorine atoms is estimated to yield small enough errors to allow for reliable interpretations and predictions of L2,3-spectra of more complex and extended silicon-based systems.
Schorr, Melanie; Thomas, Jennifer J; Eddy, Kamryn T; Dichtel, Laura E; Lawson, Elizabeth A; Meenaghan, Erinne; Lederfine Paskal, Margaret; Fazeli, Pouneh K; Faje, Alexander T; Misra, Madhusmita; Klibanski, Anne; Miller, Karen K
2017-04-01
DSM-5 revised the diagnostic criteria for anorexia nervosa (AN) by eliminating the amenorrhea requirement, liberalizing weight and psychological criteria, and adding the formal diagnosis of "atypical AN" for individuals with AN psychological symptoms without low weight. We sought to determine whether bone density (BMD) is impaired in women diagnosed with AN using the new, more liberal, DSM-5 criteria. Cross-sectional study of 168 women, 18 - 45y: (1) AN by DSM-IV (DSM-IV AN) (n = 37), (2) AN by DSM-5 but not DSM-IV criteria (DSM-5 AN) (n = 33), (3) atypical AN (ATYPICAL AN) (n = 77), (4) healthy comparison group (HC) (n = 21). Measurements included dual energy X-ray absorptiometry, Eating Disorder Examination-Questionnaire, Eating Disorder Inventory-2, Hamilton Depression and Anxiety Rating Scales. BMD Z-score DSM-IV, 82% of DSM-5, and 69% of ATYPICAL. Mean Z-scores were comparably low in DSM-IV and DSM-5, intermediate in ATYPICAL, and highest in HC. Lack of prior low weight or amenorrhea was, but history of overweight/obesity was not, protective against bone loss. Mean lean mass and percent fat mass were significantly lower in all AN groups than HC. DSM-IV, DSM-5, and ATYPICAL had comparable psychopathology. Despite liberalizing diagnostic criteria, many women diagnosed with AN and atypical AN using DSM-5 criteria have low BMD. Presence or history of low weight and/or amenorrhea remain important indications for DXA. Loss of lean mass, in addition to fat mass, is present in all AN groups, and may contribute to low BMD. The deleterious effect of eating disorders on BMD extends beyond those with current low weight and amenorrhea. © 2016 Wiley Periodicals, Inc.(Int J Eat Disord 2017; 50:343-351). © 2016 Wiley Periodicals, Inc.
Lee, Dongjin; Jin, Changhyun; Noh, Youngwook; Park, Seokhyun; Choi, Sun-Woo
2016-07-01
By exerting different O2 partial pressures (0, 20, 40, and 60 sccm) onto copper substrates, we discovered that the growth parameter, namely, the O2 flow rate, affects the degree of nucleation, diameter, length, and crystalline quality of CuO nanowires (NWs). Scanning electron microscopy (SEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM) were used to analyze the evolution of the morphological and the microstructural changes in the CuO nanostructures. The formation of a Cu2O interlayer between the Cu and the CuO layers could be adjusted by controlling more precisely the O2 flow rate. In addition, the reducing (H2S) and the oxidizing (O2, NO2, and SO2) gas sensing performances of these O2-assisted CuO NWs were compared with those of CuO NWs grown in static air. The response to the reducing H2S of the sensors based on CuO NWs grown using O2 at 40 sccm showed a higher electrical change and faster response and recovery times than the sensors based on CuO NWs grown using lower O2 flow rates, including the ones grown in static air and/or used for sensing oxidizing gases (O2, NO2, and SO2) did. On the basis of their growth and their gas-sensing applications, the possible mechanisms characteristic of the density-controlled CuO NWs grown using various O2 partial pressures are discussed.
Directory of Open Access Journals (Sweden)
Kim K. H.
2013-01-01
Full Text Available A few microns thick silicon films on glass coated with a dielectric intermediate layer can be crystallised by a single pass of a line-focused diode laser beam. Under favorable process conditions relatively large linear grains with low defect density are formed. Most grain boundaries are defect-free low-energy twin-boundaries. Boron-doped laser crystallised films are processed into solar cells by diffusing an emitter from a phosphorous spin-on-dopant source, measuring up to 539 mV open-circuit voltage prior to metallisation. After applying a point-contact metallisation the best cell achieves 7.8% energy conversion efficiency, open-circuit voltage of 526 mV and short-circuit current of 26 mA/cm2. The efficiency is significantly limited by a low fill-factor of 56% due to the simplified metallisation approach. The internal quantum efficiency of laser crystallised cells is consistent with low front surface recombination. By improving cell metallisation and enhancing light-trapping the efficiencies of above 13% can be achieved.
Peng, Junming; Liu, Yongchang; Ma, Zongqing; Shahriar Al Hossain, M.; Xin, Ying; Jin, Jianxun
2016-09-01
High performance Cu doped MgB2 bulks were prepared by an in-situ method with carbon-coated amorphous boron as precursor. It was found that the usage of carbon-coated boron in present work leads to the formation of uniformly refined MgB2 grains, as well as a high level of homogeneous carbon doping in the MgB2 samples, which significantly enhance the Jc in both Cu doped and undoped bulks compared to MgB2 bulks with normal amorphous boron precursor. Moreover, minor Cu can service as activator, and thus facilitates the growth of MgB2 grains and improves crystallinity and grain connectivity, which can bring about the excellent critical current density (Jc) at self fields and low fields (the best values are 7 × 105 A/cm2 at self fields, and 1 × 105 A/cm2 at 2 T, 20 K, respectively). Simultaneously, minor Cu addition can reduce the amount of MgO impurity significantly, also contributing to the improvement of Jc at low fields. Our work suggests that Cu-activated sintering combined with employment of carbon-coated amorphous boron as precursor could be a promising technique to produce practical MgB2 bulks or wires with excellent Jc on an industrial scale.
Energy Technology Data Exchange (ETDEWEB)
Mueller, Martin; /SLAC
2010-12-16
The study of the power density spectrum (PDS) of fluctuations in the X-ray flux from active galactic nuclei (AGN) complements spectral studies in giving us a view into the processes operating in accreting compact objects. An important line of investigation is the comparison of the PDS from AGN with those from galactic black hole binaries; a related area of focus is the scaling relation between time scales for the variability and the black hole mass. The PDS of AGN is traditionally modeled using segments of power laws joined together at so-called break frequencies; associations of the break time scales, i.e., the inverses of the break frequencies, with time scales of physical processes thought to operate in these sources are then sought. I analyze the Method of Light Curve Simulations that is commonly used to characterize the PDS in AGN with a view to making the method as sensitive as possible to the shape of the PDS. I identify several weaknesses in the current implementation of the method and propose alternatives that can substitute for some of the key steps in the method. I focus on the complications introduced by uneven sampling in the light curve, the development of a fit statistic that is better matched to the distributions of power in the PDS, and the statistical evaluation of the fit between the observed data and the model for the PDS. Using archival data on one AGN, NGC 3516, I validate my changes against previously reported results. I also report new results on the PDS in NGC 4945, a Seyfert 2 galaxy with a well-determined black hole mass. This source provides an opportunity to investigate whether the PDS of Seyfert 1 and Seyfert 2 galaxies differ. It is also an attractive object for placement on the black hole mass-break time scale relation. Unfortunately, with the available data on NGC 4945, significant uncertainties on the break frequency in its PDS remain.
基于FPGA静态傅里叶变换干涉系统的实时数据采集%Based on FPGA Real-time Spectrum Obtained of Static Fourier Spectrometer
Institute of Scientific and Technical Information of China (English)
刘睿强; 王用鑫
2011-01-01
In order to meet the special requirements the speed of interference fringes acquisition and processing in Static Fourier Transform Spectrometer, design implementation using FPGA interferogram acquisition- and spectrum recovery systems, static Fourier acquisition by CCD fringes, will be digital Gray value input to the FPGA, the Fourier transform (FFT), modulus, obtained after spectral calibration, spectral information of incident light. The main algorithm of spectrum analysis are the base 2 FFT and the spectral calibration that can be detected in the two standards to the location within the wavelength calibration achieved. Through the analysis of various apodization functions, are closest to the true value of the windowing effect. Experiments were collected center wavelength 635 nm, 650 nm, 780nm, 808 nm, 850nm semiconductor laser, the incident is equivalent to a static Fourier transform interferometer with a wedge-shaped formation of interference fringes, and FPGA results in the recovery spectrum Avantes Company's fiber optic spectrometer measured results comparison, and the error is ±2 nm.%针对静态傅里叶变换光谱仪中干涉条纹采集与处理对速度快的特殊要求,设计了用FPGA实现干涉图采集和光谱复原系统,通.过CCD采集静态傅里叶干涉条纹后,将数字灰度值输入到FPGA中,进行傅里叶变换(FFT)、取模、光谱标定等处理后得到入射光的光谱信息.光谱获取的算法主要由基2-FFT和光谱标定实现,光谱标定是通过在可探测波长内取两个标准位置来计算中心波长准确位置的.为了获得较好的加窗效果,对多种切趾函数进行了分析,通过仿真数据得到半宽和中心波长位置都相对较好的加窗方式.实验分别对中心波长635 nm,650 nm,780 nm,808 nm,850 nm的半导体激光器进行干涉条纹采集,当激光入射等效楔形静态傅里叶变换干涉具后形成干涉条纹,由CCD采集传给FPGA,本算法复原得到的
Directory of Open Access Journals (Sweden)
Manuel F. Valero
2009-01-01
Full Text Available Se obtuvo una gama de polioles a partir del aceite de ricino modificado por transesterificación con pentaeritriol y glicerina. Los productos resultantes fueron caracterizados físico-químicamente. Se sintetizaron elastómeros de poliuretano a partir de los polioles derivados del aceite de ricino modificado. La densidad de entrecruzamiento se determinó por ensayos de hinchamiento a partir de la ecuación de Flory-Rehner apoyada en la espectroscopia MALDI TOF MS para determinar la estructura química de la unidad repetitiva promedio del poliuretano. Se estudió la variación de la densidad de entrecruzamiento de los poliuretanos con base en el índice de hidroxilo del poliol utilizado en la síntesis. Los resultados muestran que los PU obtenidos a través de la modificación del aceite con pentaeritriol tienen una mayor densidad de entrecruzamiento que los PU obtenidos a partir del aceite original y de los polioles derivados de la reacción de transesterificación del aceite con glicerina, debido a que estos polioles poseen una mayor funcionalidad hidroxílica.Two series of polyols were obtained from castor oil modified by transesterification with various amounts of pentaerythritol and glycerol. The resultant polyol properties were characterized as a function of the hydroxyl functionality. Polyurethane elastomers (PU were synthesized from the two series of polyols obtained. The crosslink density of those polyurethanes was determined by swelling tests data adjusted to the Flory-Rehner's equation and according to the elasticity theory. The variation of the crosslink density of polyurethanes was studied by following the hydroxyl value of the modified polyol utilized in the synthesis and based on the average structure of each polyurethane repeating unit, as determined by the method of matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy (MALDI TOF MS. The results show that the PU obtained through castor oil modified with
Compressive Wideband Spectrum Sensing for Fixed Frequency Spectrum Allocation
Liu, Yipeng
2010-01-01
Too high sampling rate is the bottleneck to wideband spectrum sensing for cognitive radio (CR). As the survey shows that the sensed signal has a sparse representation in frequency domain in the mass, compressed sensing (CS) can be used to transfer the sampling burden to the digital signal processor. An analog to information converter (AIC) can randomly sample the received signal with sub-Nyquist rate to obtained the random measurements. Considering that the static frequency spectrum allocation of primary radios means the bounds between different primary radios is known in advance, here we incorporate information of the spectrum boundaries between different primary user as a priori information to obtain a mixed l2/l1 norm denoising operator (MNDO). In the MNDO, the estimated power spectrum density (PSD) vector is divided into block sections with bounds corresponding different allocated primary radios. Different from previous standard l1-norm constraint on the whole PSD vector, a sum of the l2 norm of each sect...
DEFF Research Database (Denmark)
Hammerum, Anette M.; Larsen, Jesper; Dalhoff Andersen, Vibe;
2014-01-01
Objectives: To compare and characterize extended-spectrum b-lactamase (ESBL)-producing Escherichia coli from pigsties, pig farmers and their families on farms with previous high or no use of third- or fourth-generation cephalosporins. Methods: Twenty farms with no third- or fourth-generation ceph...
Energy Technology Data Exchange (ETDEWEB)
Oliveira, Jose Anderson Machado; Raulino, Anamelia de Medeiros Dantas; Raulino, Jose Leonardo Costa; Campos, Ana Regina Nascimento; Prasad, Shiva; Santana, Renato Alexandre Costa de, E-mail: jmo.anderson@gmail.com, E-mail: anameliadantas@yahoo.com.br, E-mail: leonardo.jcr@hotmail.com, E-mail: arncampos@yahoo.com.br, E-mail: prasad@deq.ufcg.edu.br, E-mail: renatoacs@ufcg.edu.br [Universidade Federal de Campina Grande (UFCG), Cuite, PB (Brazil). Lab. de Eletroquimica e Corrosao
2017-01-15
Metallic coatings can be applied for different purposes, for example to improve the mechanical, catalytic, anti corrosive properties or simply to improve the decorative appearance. In the work the Fe-Ni alloys have been obtained by electrodeposition process using a simple electrolytic bath containing the reagents, nickel sulfate, iron sulfate and sodium tartrate. A complete experimental design 2{sup 2} , associated with the response surface methodology (RSM) technique was used as optimization tool. Chemical composition, current efficiency, surface morphology and electrochemical corrosion measures were performed. It was observed that a decrease in the pH favored an increase in iron and decrease in nickel contents in the alloy. The iron content influenced the alloy morphology. The best experiment showed an average corrosion resistance 5471.5 Ω.cm² and a corrosion current density 4.814x10{sup -6} A/cm². This experiment presented a composition of 70 wt% Ni and 30 wt% Fe in the alloy and an average deposition current efficiency of 58.7%. (author)
Feng; Lu; Shen; Kim; Eisaki; Damascelli; Yoshizaki; Shimoyama; Kishio; Gu; Oh; Andrus; O'Donnell; Eckstein; Shen
2000-07-14
We report that the doping and temperature dependence of photoemission spectra near the Brillouin zone boundary of Bi(2)Sr(2)CaCu(2)O(8+delta)exhibit unexpected sensitivity to the superfluid density. In the superconducting state, the photoemission peak intensity as a function of doping scales with the superfluid density and the condensation energy. As a function of temperature, the peak intensity shows an abrupt behavior near the superconducting phase transition temperature where phase coherence sets in, rather than near the temperature where the gap opens. This anomalous manifestation of collective effects in single-particle spectroscopy raises important questions concerning the mechanism of high-temperature superconductivity.
Energy Technology Data Exchange (ETDEWEB)
Doroshkevich, A.G.; Zel' dovich, Y.B.; Syunyaev, R.A.; Khlopov, M.Y.
1980-07-01
If the neutrino has a rest mass, a scale comparable with the distance between clusters of galaxies would have been singled out in the universe. The amplitude of neutrino density perturbations on smaller scales should diminish in proportion to a high power of the perturbation wavelength. The evolution of adiabatic and entropic (isothermal) density perturbations is considered, and it is shown that the existence of a neutrino rest mass would imply smaller fine-scale fluctuations in the microwave background radiation than models in which m/sub ..nu../=0.
Institute of Scientific and Technical Information of China (English)
张耿; 李杰; 杨子敬
2011-01-01
Track irregularity is the main excitation source to vibration of the maglev train, and it has direct influence on stability and ride quality of the train. The statistical specimens of track irregularities are collected from the TangShan low-speed maglev experimental line on the basis of the stationarity tests of the specimens, the Fast Fourier Transform(FFT) method was used to evaluate the spectra of the whole specimen space. Distribution of track irregularities in space wavelengths was found. Analysis results show that the structural parameters, installation precision and rolling technique of tracks are the main causes of track irregularity. Referring to the mature PSD( power spectrum density) expressions published athome and abroatl, the set fitting formulas of PSD for low-speed maglev railway lines were proposed. The parameter values of PSD fitting curves for low-speed maglev track irregularities were obtained by use of the damping curve-fitting algorithm in the least-squares sense. Significaul reference is provided to study on track irregularity PSD of low-speed maglev railway lines.%轨道不平顺是磁浮列车振动的主要激扰源,直接关系到列车运行的稳定性和舒适性.文章基于唐山低速磁浮试验线实测的轨道不平顺数据,采用周期图法进行样本空间的谱估计,得到轨道不平顺在各空间波长的分布.分析结果表明,轨道本身结构参数、轨道安装精度和F轨的轧制工艺是产生轨道不平顺的主要原因.参考国内外成熟的铁路轨道谱线表达形式,得到低速磁浮轨道谱的拟合曲线公式,应用阻尼最小二乘算法拟合轨道谱表达式的参数,对于研究我国磁浮轨道不平顺功率谱有重要的参考价值.
Bloch, F.; Staub, H.
1943-08-18
Measurements of the spectrum of the fission neutrons of 25 are described, in which the energy of the neutrons is determined from the ionization produced by individual hydrogen recoils. The slow neutrons producing fission are obtained by slowing down the fast neutrons from the Be-D reaction of the Stanford cyclotron. In order to distinguish between fission neutrons and the remaining fast cyclotron neutrons both the cyclotron current and the pusle amplifier are modulated. A hollow neutron container, in which slow neutrons have a lifetime of about 2 milliseconds, avoids the use of large distances. This method results in much higher intensities than the usual modulation arrangement. The results show a continuous distribution of neutrons with a rather wide maximum at about 0.8 MV falling off to half of its maximum value at 2.0 MV. The total number of netrons is determined by comparison with the number of fission fragments. The result seems to indicate that only about 30% of the neutrons have energies below .8 MV. Various tests are described which were performed in order to rule out modification of the spectrum by inelastic scattering. Decl. May 4, 1951
Bera, Sudesna; Chakrabarti, Barnali; Das, T. K.
2017-04-01
We show that the conditional shape invariance symmetry can be used as a very powerful tool to calculate the eigenvalues of the mixed potential V (r) = ar + br2 + c/r + l (l + 1)/r2 for a restricted set of potential parameters. The energy for any state can be obtained algebraically, albeit for a severely restricted set of potential parameters. We also indicate that each member of the hierarchy of Hamiltonians is basically conditionally translational shape invariant. Comparison of analytically obtained results with numerical results is also presented. Our present methodology can be taken as an alternative treatment for the calculation of any higher order excited states of conditionally exactly solvable (CES) potentials.
Mattingly, Sean; Berumen, Jorge; Chu, Feng; Hood, Ryan; Skiff, Fred
2014-10-01
By using two independently tunable lasers, each with its own collection optics and Ar II LIF transition scheme, we are able to investigate plasma ion density fluctuations as a function of not only spatial scales but also as a function of ion velocities as sampled on different points of a single Doppler-broadened spectral emission line. We do this by measuring the two point correlation C (x , v ,x' ,v' , τ) = t . With the current system, the two carriages determine x and x', while the velocities selected by each laser determine v and v'. Using the two lasers to make two point correlations in phase space demonstrates effects that are not fully understood. In this experiment, we explore the striking difference in correlations when, in the past, the particle orbits overlap in space versus when they do not overlap. This is performed on a small cylindrical laboratory plasma with n ~109 cm-3 , Te ~ 5 eV, Ti ~ 0 . 06 , and a 1 kG axial magnetic field. LIF is performed on ions at two locations aligned with the magnetic field line with a viewing volume comparable to the size of the Larmor radius. Results and interpretations from these experiments are presented and discussed. DOE Grant DE-FG02-99ER54543.
Directory of Open Access Journals (Sweden)
André M. Senna
2013-01-01
:3] and [3:1] PMDA mol/mol of free OH, respectively. A gel was synthesized in excess of 200% of PMDA in relation to free OH groups of the AC. The basis of the Flory-Rehner theory was used for determining crosslinking in the gels. Briefly, the main results showed that the crosslinking density increased proportionally to the amount of PMDA added to the reaction medium. Distinct AFM topographies were obtained for distinct gels, which were also different from the polymer cellulose acetate. This work was motivated by the technological importance of polymers from renewable sources such as cellulose, in which a cellulose derivative was developed with promising application in drug delivery and in adsorption of heavy metals in aqueous systems. The advantage of this cellulose acetate derivative is the use of fewer steps in its synthesis.
Achievable capacity of a spectrum sharing system over hyper fading channels
Ekin, Sabit
2009-11-01
Cognitive radio with spectrum sharing feature is a promising technique to address the spectrum under-utilization problem in dynamically changing environments. In this paper, achievable capacity gain of spectrum sharing systems over dynamic fading environments is studied. For the analysis, a theoretical fading model called hyper fading model that is suitable to the dynamic nature of cognitive radio channel is proposed. Closed-form expression of probability density function (PDF) and cumulative density function (CDF) of the signal-to-noise ratio (SNR) for secondary users in spectrum sharing systems are derived. In addition, the capacity gains achievable with spectrum sharing systems in high and low power regions are obtained. Numerical simulations are performed to study the effects of different fading figures, average powers, interference temperature, and number of secondary users on the achievable capacity.
Entanglement spectrum in cluster dynamical mean-field theory
Udagawa, Masafumi; Motome, Yukitoshi
2015-01-01
We study the entanglement spectrum of the Hubbard model at half filling on a kagome lattice. The entanglement spectrum is defined by the set of eigenvalues of a reduced thermal density matrix, which is naturally obtained in the framework of the dynamical mean-field theory. Adopting the cluster dynamical mean-field theory combined with continuous-time auxiliary-field Monte Carlo method, we calculate the entanglement spectrum for a three-site triangular cluster in the kagome Hubbard model. We find that the results at the three-particle sector well capture the qualitative nature of the system. In particular, the eigenvalue of the reduced density matrix, corresponding to the chiral degrees of freedom, exhibits a characteristic temperature scale Tchiral, below which a metallic state with large quasiparticle mass is stabilized. The entanglement spectra at different particle number sectors also exhibit characteristic changes around Tchiral, implying the development of inter-triangular ferromagnetic correlations in the correlated metallic regime.
Toward detailed prominence seismology - II. Charting the continuous magnetohydrodynamic spectrum
Blokland, J W S
2011-01-01
Starting from accurate MHD flux rope equilibria containing prominence condensations, we initiate a systematic survey of their linear eigenoscillations. To quantify the full spectrum of linear MHD eigenmodes, we require knowledge of all flux-surface localized modes, charting out the continuous parts of the MHD spectrum. We combine analytical and numerical findings for the continuous spectrum for realistic prominence configurations. The equations governing all eigenmodes for translationally symmetric, gravitating equilibria containing an axial shear flow, are analyzed, along with their flux-surface localized limit. The analysis is valid for general 2.5D equilibria, where either density, entropy, or temperature vary from one flux surface to another. We analyze the mode couplings caused by the poloidal variation in the flux rope equilibria, by performing a small gravity parameter expansion. We contrast the analytical results with continuous spectra obtained numerically. For equilibria where the density is a flux ...
Institute of Scientific and Technical Information of China (English)
贺芳
2013-01-01
A decision-making method with a modified interval number density aggregation operator is proposed to solve the group weights problems with index data known and weights unknown .First, the several concepts of in-terval number and interval number density aggregation operator are introduced , the method of interval number clustering is improved , the direct algorithm is applied to cluster the one-dimensional data , and fuzzy statistics variables are defined to make sure which is the best way to clustering .Then based on a modified interval number density aggregation operator the group weights problems with index data known and weights unknown are solved . Finally it is shown that the method is feasible and effective with an example .%针对指标数据已知，而权重数据未知的群组赋权问题，给出了一种基于改进的区间数密度集结算子来进行指标群组赋权的决策方法。首先给出了区间数和区间数密度集结算子（ IDM）的定义及性质，改进了以前区间数聚类的方法，应用直接法对一维区间数据组进行聚类，并定义了模糊统计量，以确定最为合理的一种聚类方式。然后基于改进的区间数密度集结算子这种数学模型，来解决指标值数据已知，而权重未知的群组赋权问题。最后举例说明该方法的可行性和实用性。
Greisch, Jean-François; Chmela, Jiří; Harding, Michael E; Wunderlich, Dirk; Schäfer, Bernhard; Ruben, Mario; Klopper, Wim; Schooss, Detlef; Kappes, Manfred M
2017-02-22
We report a combined investigation of europium(iii)9-oxo-phenalen-1-one (PLN) coordination complexes, [Eu(PLN)4AE](+) with AE = Mg, Ca, and Sr, using gas-phase photoluminescence, trapped ion-mobility spectrometry and density-functional computations. In order to sort out the structural impact of the alkali earth dications on the photoluminescence spectra, the experimental data are compared to the predicted ligand-field splittings as well as to the collision cross-sections for different isomers of [Eu(PLN)4AE](+). The best fitting interpretation is that one isomer family predominantly contributes to the recorded luminescence. The present work demonstrates the complexity of the coordination patterns of multicenter lanthanoid chelates involved in dynamical equilibria and the pertinence of using isolation techniques to elucidate their photophysical properties.
Submillimeter Polarization Spectrum in the Vela C Molecular Cloud
Gandilo, Natalie N; Angilè, Francesco E; Ashton, Peter; Benton, Steven J; Devlin, Mark J; Dober, Bradley; Fissel, Laura M; Fukui, Yasuo; Galitzki, Nicholas; Klein, Jeffrey; Korotkov, Andrei L; Li, Zhi-Yun; Martin, Peter G; Matthews, Tristan G; Moncelsi, Lorenzo; Nakamura, Fumitaka; Netterfield, Calvin B; Novak, Giles; Pascale, Enzo; Poidevin, Frédérick; Santos, Fabio P; Savini, Giorgio; Scott, Douglas; Shariff, Jamil A; Soler, Juan Diego; Thomas, Nicholas E; Tucker, Carole E; Tucker, Gregory S; Ward-Thompson, Derek
2015-01-01
Polarization maps of the Vela C molecular cloud were obtained at 250um, 350um, and 500um during the 2012 flight of the balloon-borne telescope BLASTPol. These measurements are used in conjunction with 850um data from Planck to study the submillimeter spectrum of the polarization fraction for this cloud. The spectrum is relatively flat and does not exhibit the minimum at \\lambda ~350um observed in previous measurements of other molecular clouds. The shape of the spectrum does not depend strongly on the radiative environment of the dust, as quantified by the column density or the dust temperature obtained from Herschel data. The polarization ratios observed in Vela C are consistent with a model of a porous clumpy molecular cloud being uniformly heated by the interstellar radiation field.
Primary spectrum and composition with IceCube/IceTop
,
2016-01-01
IceCube, with its surface array IceTop, detects three different components of extensive air showers: the total signal at the surface, GeV muons in the periphery of the showers and TeV muons in the deep array of IceCube. The spectrum is measured with high resolution from the knee to the ankle with IceTop. Composition and spectrum are extracted from events seen in coincidence by the surface array and the deep array of IceCube. The muon lateral distribution at the surface is obtained from the data and used to provide a measurement of the muon density at 600 meters from the shower core up to 30 PeV. Results are compared to measurements from other experiments to obtain an overview of the spectrum and composition over an extended range of energy. Consistency of the surface muon measurements with hadronic interaction models and with measurements at higher energy is discussed.
Energy Technology Data Exchange (ETDEWEB)
Martin-Viera Cueto, J. A.; Garcia Pareja, S.; Benitez Villegas, E. M.; Moreno Saiz, E. M.; Bodineau Gil, C.; Caudepon Moreno, F.
2011-07-01
The objective of this work is to obtain the conversion curve of Hounsfield units (A) versus electron densities using a mannequin with different tissue equivalent materials. This provides for the effective energy beam CT and is used to characterize the linear coefficients of absorption of different materials that comprise the dummy.
Determination of the Density of Energy States in a Quantizing Magnetic Field for Model Kane
Directory of Open Access Journals (Sweden)
G. Gulyamov
2016-01-01
Full Text Available For nonparabolic dispersion law determined by the density of the energy states in a quantizing magnetic field, the dependence of the density of energy states on temperature in quantizing magnetic fields is studied with the nonquadratic dispersion law. Experimental results obtained for PbTe were analyzed using the suggested model. The continuous spectrum of the energy density of states at low temperature is transformed into discrete Landau levels.
Khusenov, Arslonnazar; Rakhmanberdiev, Gappar; Rakhimov, Dilshod; Khalikov, Muzaffar
2014-01-01
In the article first obtained inulin ester inulin acetate, by etherification of inulin with acetic anhydride has been exposed. Obtained product has been studied using elementary analysis and IR spectroscopy.
Kern, Christoph; Deutschmann, Tim; Werner, Cynthia; Sutton, A. Jeff; Elias, Tamar; Kelly, Peter J.
2012-01-01
Sulfur dioxide (SO2) is monitored using ultraviolet (UV) absorption spectroscopy at numerous volcanoes around the world due to its importance as a measure of volcanic activity and a tracer for other gaseous species. Recent studies have shown that failure to take realistic radiative transfer into account during the spectral retrieval of the collected data often leads to large errors in the calculated emission rates. Here, the framework for a new evaluation method which couples a radiative transfer model to the spectral retrieval is described. In it, absorption spectra are simulated, and atmospheric parameters are iteratively updated in the model until a best match to the measurement data is achieved. The evaluation algorithm is applied to two example Differential Optical Absorption Spectroscopy (DOAS) measurements conducted at Kilauea volcano (Hawaii). The resulting emission rates were 20 and 90% higher than those obtained with a conventional DOAS retrieval performed between 305 and 315 nm, respectively, depending on the different SO2 and aerosol loads present in the volcanic plume. The internal consistency of the method was validated by measuring and modeling SO2 absorption features in a separate wavelength region around 375 nm and comparing the results. Although additional information about the measurement geometry and atmospheric conditions is needed in addition to the acquired spectral data, this method for the first time provides a means of taking realistic three-dimensional radiative transfer into account when analyzing UV-spectral absorption measurements of volcanic SO2 plumes.
Speaker Identification From Youtube Obtained Data
Directory of Open Access Journals (Sweden)
Nitesh Kumar Chaudhary
2014-10-01
Full Text Available An efficient, and intuitive algorithm is presented for the identification of speakers from a long dataset (like YouTube long discussion, Cocktail party recorded audio or video.The goal of automatic speaker identification is to identify the number of different speakers and prepare a model for that speaker by extraction, characterization and speaker-specific information contained in the speech signal. It has many diverse application specially in the field of Surveillance , Immigrations at Airport , cyber security , transcription in multi-source of similar sound source, where it is difficult to assign transcription arbitrary. The most commonly speech parameterization used in speaker verification, K-mean, cepstral analysis, is detailed. Gaussian mixture modeling, which is the speaker modeling technique is then explained. Gaussian mixture models (GMM, perhaps the most robust machine learning algorithm has been introduced to examine and judge carefully speaker identification in text independent. The application or employment of Gaussian mixture models for monitoring & Analysing speaker identity is encouraged by the familiarity, awareness, or understanding gained through experience that Gaussian spectrum depict the characteristics of speaker's spectral conformational pattern and remarkable ability of GMM to construct capricious densities after that we illustrate 'Expectation maximization' an iterative algorithm which takes some arbitrary value in initial estimation and carry on the iterative process until the convergence of value is observed We have tried to obtained 85 ~ 95% of accuracy using speaker modeling of vector quantization and Gaussian Mixture model ,so by doing various number of experiments we are able to obtain 79 ~ 82% of identification rate using Vector quantization and 85 ~ 92.6% of identification rate using GMM modeling by Expectation maximization parameter estimation depending on variation of parameter.
The matter power spectrum from the Ly alpha forest : an optical depth estimate
Zaroubi, S; Nusser, A; Haehnelt, M; Kim, TS; Viel, M.
2006-01-01
We measure the matter power spectrum from 31 Ly alpha spectra spanning the redshift range of 1.6-3.6. The optical depth, tau, for Ly alpha absorption of the intergalactic medium is obtained from the flux using the inversion method of Nusser & Haehnelt. The optical depth is converted to density by us
Band structure and density of states in FeAs-based superconductors
Kashurnikov, V. A.; Krasavin, A. V.
2015-09-01
The generalized quantum Monte Carlo algorithm was used to obtain one-particle excitation spectrum and electron density of states for two-dimensional FeAs-clusters modeling iron-based superconductors within the limits of the full two-orbital model. The calculations were performed for clusters with sizes up to 10×10 FeAs-cells. The excitation spectra were reconstructed from Matsubara Green's function. The spectral density of states and the total density of states near the Fermi level were obtained. The data are in accordance with known experimental results. The influence of the cluster size, temperature, and the interaction strength on the density of states was analysed.
... severe defect, resulting in essentially nonfunctional peroxisomes. This phenomenon produces the range of severity of the disorders. How is the Zellweger Spectrum Diagnosed? The distinctive shape of the head and face of a child born with one of the diseases of the ...
Energy Technology Data Exchange (ETDEWEB)
Palistrant, M. E., E-mail: mepalistrant@yandex.com; Ursu, V. A. [Academy of Sciences of Moldova, Institute of Applied Physics (Moldova, Republic of)
2013-04-15
A theory of thermodynamic properties of a spin density wave (SDW) in a quasi-two-dimensional system (with a preset impurity concentration x) is constructed. We choose an anisotropic dispersion relation for the electron energy and assume that external magnetic field H has an arbitrary direction relative to magnetic moment M{sub Q}. The system of equations defining order parameters M{sub Q}{sup z}, M{sub Q}{sup {sigma}}, M{sub z}, and M{sup {sigma}} is constructed and transformed with allowance for the Umklapp processes. Special cases when H Double-Vertical-Line M{sub Q} and H Up-Tack M{sub Q} (H{sub Z}H{sup {sigma}} = 0) are considered in detail as well as cases of weak fields H of arbitrary direction. The condition for the transition of the system to the commensurate and incommensurate states of the SDW is analyzed. The concentration dependence of magnetic transition temperature T{sub M} is calculated, and the components of the order parameter for the incommensurate phase are determined. The phase diagram (T,{approx}x) is constructed. The effect of the magnetic field on magnetic transition temperature T{sub M} is analyzed for H{sub Z}H{sup {sigma}} = 0, and longitudinal magnetic susceptibility {chi} Double-Vertical-Line is calculated; this quantity demonstrates the temperature dependence corresponding to a system with a gap for x < x{sub c} and to a gapless state for x > x{sub c}. In the immediate vicinity of the critical impurity concentration (x {approx} x{sub c}), the temperature dependence of the magnetic susceptibility acquires a local maximum. The effect of anisotropy of the electron energy spectrum on the investigated physical quantities is also analyzed.
Energy spectrum and phase diagrams of two-sublattice hard-core boson model
Directory of Open Access Journals (Sweden)
I.V. Stasyuk
2013-06-01
Full Text Available The energy spectrum, spectral density and phase diagrams have been obtained for two-sublattice hard-core boson model in frames of random phase approximation approach. Reconstruction of boson spectrum at the change of temperature, chemical potential and energy difference between local positions in sublattices is studied. The phase diagrams illustrating the regions of existence of a normal phase which can be close to Mott-insulator (MI or charge-density (CDW phase diagrams as well as the phase with the Bose-Einstein condensate (SF phase are built.
Gamma spectrum following neutron capture in {sup 167}Er
Energy Technology Data Exchange (ETDEWEB)
Visser, D.; Khoo, T.L.; Lister, C.J. [and others
1995-08-01
Statistical decay from a highly excited state samples all the lower-lying states and, hence, provides a sensitive measure of the level density. Pairing has a major impact on the level density, e.g. creating a pair gap between the 0- and 2-quasiparticle configurations. Hence the shape of the statistical spectrum contains information on pairing, and can be used to provide information on the reduction of pairing with thermal excitation energy. For this reason, we measured the complete spectrum of {gamma}rays following thermal neutron capture in {sup 167}Er. The experiment was performed at the Brookhaven reactor using Compton-suppressed Ge detectors from TESSA. The spectrum, which was corrected for detector response and efficiency, reveals primary (first-step, high-energy) transitions up to nearly 8 MeV, secondary (last-step, lower-energy) transitions, as we as a continuous statistical component. Effort was expanded to identify all lines from contaminant sources and an upper limit of 5% was tentatively set for their contributions. The spectral shape of the statistical spectrum will be compared with theoretical spectra obtained from a calculation of pairing which accounts for a stepwise reduction of the pair correlations as the number of quasiparticles increases. The primary lines which decay directly to the near-yrast states will also be used to deduce the level densities.
Refinements in the Los Alamos model of the prompt fission neutron spectrum
Energy Technology Data Exchange (ETDEWEB)
Madland, D.G., E-mail: dgm@lanl.gov; Kahler, A.C.
2017-01-15
This paper presents a number of refinements to the original Los Alamos model of the prompt fission neutron spectrum and average prompt neutron multiplicity as derived in 1982. The four refinements are due to new measurements of the spectrum and related fission observables many of which were not available in 1982. They are also due to a number of detailed studies and comparisons of the model with previous and present experimental results including not only the differential spectrum, but also integral cross sections measured in the field of the differential spectrum. The four refinements are (a) separate neutron contributions in binary fission, (b) departure from statistical equilibrium at scission, (c) fission-fragment nuclear level-density models, and (d) center-of-mass anisotropy. With these refinements, for the first time, good agreement has been obtained for both differential and integral measurements using the same Los Alamos model spectrum.
Dynamic spectrum auction in wireless communication
Chen, Yanjiao
2015-01-01
This brief explores current research on dynamic spectrum auctions, focusing on fundamental auction theory, characteristics of the spectrum market, spectrum auction architecture and possible auction mechanisms. The brief explains how dynamic spectrum auctions, which enable new users to gain spectrum access and existing spectrum owners to obtain financial benefits, can greatly improve spectrum efficiency by resolving the artificial spectrum shortage. It examines why operators and users face significant challenges due to specialty of the spectrum market and the related requirements imposed on the auction mechanism design. Concise and up-to-date, Dynamic Spectrum Auction in Wireless Communication is designed for researchers and professionals in computer science or electrical engineering. Students studying networking will also find this brief a valuable resource.
Probability-consistent spectrum and code spectrum
Institute of Scientific and Technical Information of China (English)
沈建文; 石树中
2004-01-01
In the seismic safety evaluation (SSE) for key projects, the probability-consistent spectrum (PCS), usually obtained from probabilistic seismic hazard analysis (PSHA), is not consistent with the design response spectrum given by Code for Seismic Design of Buildings (GB50011-2001). Sometimes, there may be a remarkable difference between them. If the PCS is lower than the corresponding code design response spectrum (CDS), the seismic fortification criterion for the key projects would be lower than that for the general industry and civil buildings. In the paper, the relation between PCS and CDS is discussed by using the ideal simple potential seismic source. The results show that in the most areas influenced mainly by the potential sources of the epicentral earthquakes and the regional earthquakes, PCS is generally lower than CDS in the long periods. We point out that the long-period response spectra of the code should be further studied and combined with the probability method of seismic zoning as much as possible. Because of the uncertainties in SSE, it should be prudent to use the long-period response spectra given by SSE for key projects when they are lower than CDS.
Was The Electromagnetic Spectrum A Blackbody Spectrum In The Early Universe?
Opher, Merav; Opher,Reuven
1997-01-01
It is assumed, in general, that the electromagnetic spectrum in the Primordial Universe was a blackbody spectrum in vacuum. We derive the electromagnetic spectrum, based on the Fluctuation-Dissipation Theorem that describes the electromagnetic fluctuations in a plasma. Our description includes thermal and collisional effects in a plasma. The electromagnetic spectrum obtained differs from the blackbody spectrum in vacuum at low frequencies. In particular, concentrating on the primordial nucleo...
[Erythromycin ethylsuccinate obtaining possibilities].
Stan, Cătălina Daniela; Stefanache, Alina; Tântaru, Gladiola; Poiată, Antonia; Dumitrache, M; Diaconu, D E; Profire, Lenuţa
2008-01-01
In this study we tried to improve the erythromycin ethylsuccinate obtaining, having in view to separate the erythromycin ester by crystallization in water. The erythromycin acylation and the erythromycin ethylsuccinate crystallization were realized, following the next steps: 1. the acylation of the erythromycin with a methylene chloride solution of monoethylsuccinyl chloride, at 25-28 degrees C for 3 hours in the presence of NaHCO3; 2. the transfer of the erythromycin ethylsuccinate from methylene chloride solution in acetone solution by distillation of mixture methylene chloride: acetone 1:1 at 25-28 degrees C; 3. erythromycin ethylsuccinate separation by crystallization in water at pH = 8-8.5 and 5 degrees C for 90 minutes. The quality control for the erythromycin ester was performed according to the Xth edition of Romanian Pharmacopoeia standards using national standard for erythromycin ethylsuccinate and national standard for erythromycin with an activity of 1: 937 U and 2.02% humidity. The Micrococcus luteus ATCC 9341 was used as a test microorganism and a thin layer cromatography was performed for qualitative control. 13.1 g of erythromycin ethylsuccinate were obtained with an output of the process of 82.02%. Using water for the separation of erythromycin ethylsuccinate the output of the process is greater (82.02%) than in case of using petroleum ether (74.14%) or hexane (80.25%). The thin layer cromatography revealed an Rf = 0.56 and the microbiological activity of the erythromycin ethylsuccinate was 98.7% compared with the standard. Using water instead of hexane or petroleum ether is gainful for the separation of erythromycin ethylsuccinate from the reaction medium. The obtained erythromycin ethylsuccinate corresponds to the Xth edition of Romanian Pharmacopoeia standards. So, the raw materials consumption is decreased, the costs are cut down, the obtained product purity is high and the output of the process is greater.
Quantification of Sugars in Soft Drinks and Fruit Juices by Density ...
African Journals Online (AJOL)
Density and refractometric methods can be used to obtain only the total amount of sugar. However .... The first coordinate is calculated so as to predict as much as pos- sible the ... spectrum i and wave number j, R0 corresponds to the back-.
Terahertz spectrum of gallic acid
Wu, Meng; Zhao, Guozhong; Wang, Haiyan; Liang, Chengshen
2009-11-01
Gallic acid is natural polyphenol compound found in many green plants. More and more experiments have demonstrated that the gallic acid has comprehensive applications. In the field of medicine, the gallic acid plays an important role in antianaphylaxis, antineoplastic, antimycotic, anti-inflammatory, antivirotic, antiasthmatic and inhibiting the degradation of insulin. It also has a lot of applications in chemical industry, food industry and light industry. So it is important to study the terahertz time-domain spectroscopy of gallic acid. Terahertz time-domain spectroscopy (THz-TDS) is a new coherent spectral technology based on the femtosecond laser. In this work, the spectral characteristics of gallic acid in the range of 0.4 THz to 2.6 THz have been measured by THz-TDS. We obtained its absorption and refraction spectra at room temperature. The vibration absorption spectrum of the single molecule between 0.4 THz and 2.6 THz is simulated based on the Density Functional Theory (DFT). It is found that the gallic acid has the spectral response to THz wave in this frequency range. The results show the abnormal dispersion at 1.51 THz and 2.05 THz. These results can be used in the qualitative analysis of gallic acid and the medicine and food inspection.
van Duijnen, Piet Th.; Greene, Shannon N.; Richards, Nigel G. J.
2007-01-01
We report the calculated visible spectrum of [Fe-III(PyPepS)(2)](-) in aqueous solution. From all-classical molecular dynamics simulations on the solute and 200 water molecules with a polarizable force field, 25 solute/solvent configurations were chosen at random from a 50 ps production run and subj
Spectrum Trading for Efficient Spectrum Utilization
Directory of Open Access Journals (Sweden)
Cong Xiong
2014-04-01
Full Text Available The conventional command and control based spectrum management has led to substantial underutilization of some spectrum bands while severely crowding others due to the uneven and dynamic needs that vary over time and at different locations. Spectrum trading has emerged as a promising management approach to substantially improve spectrum utilization and user experience in wireless communications by taking advantage of market-based mechanisms. This article presents an overview of spectrum trading, including the fundamental characteristics of spectrum trading markets, the state-of-the-art techniques for modeling and resolving various spectrum trading issues, and trading based dynamic spectrum sharing and access. Moreover, some open issues in spectrum trading are identified for future research in this area.
Analytical approach to high harmonics spectrum in the nanobunching regime
Cherednychek, Mykyta
2016-01-01
With the high-order harmonic generation (HHG) from plasma sur- faces it is possible to turn a laser pulse into a train of attosecond or even zeptosecond pulses in the backward radiation. These attosecond pulses may have amplitude several orders of magnitude higher than that of the laser pulse under appropriate conditions. We study this process in detail, especially the nanobunching of the plasma electron density. We derive an analytical expression that describes the electron density pro- file and obtain a good agreement with particle-in-cell simulation results. We investigate the most efficient case of HHG at moderate laser intensity (I = 2*10^20 W/cm^2 ) on the over-dense plasma slab with an exponential profile pre-plasma. Subsequently we calculate the spectra of a single at- tosecond pulse from the backward radiation using our expression for the density shape in combination with the equation for the spectrum of the nanobunch radiation.
Spectrum Analysis of Wind Profiling Radar Measurements
Institute of Scientific and Technical Information of China (English)
阮征; 慕瑞琪; 魏鸣; 葛润生
2014-01-01
Unlike previous studies on wind turbulence spectrum in the planetary boundary layer, this investigation focuses on high-altitude (1-5 km) wind energy spectrum and turbulence spectrum under various weather conditions. A fast Fourier transform (FFT) is used to calculate the wind energy and turbulence spectrum density at high altitudes (1-5 km) based on wind profiling radar (WPR) measurements. The turbulence spectrum under stable weather conditions at high altitudes is expressed in powers within a frequency range of 2 × 10-5-10-3 s-1, and the slope b is between -0.82 and -1.04, indicating that the turbulence is in the transition from the energetic area to the inertial sub-range. The features of strong weather are reflected less obviously in the wind energy spectrum than in the turbulence spectrum, with peaks showing up at different heights in the latter spectrum. Cold windy weather appears over a period of 1.5 days in the turbulence spectrum. Wide-range rainstorms exhibit two or three peaks in the spectrum over a period of 15-20 h, while in severe convective weather conditions, there are two peaks at 13 and 9 h. The results indicate that spectrum analysis of wind profiling radar measurements can be used as a supplemental and helpful method for weather analysis.
Measurement of neutron spectrum in vertical channel of IR-8 nuclear reactor
Kashchuk, Y A; Sevastyanov, V D; Egorov, E V
2002-01-01
Paper presents the experimental results of measurement of neutron flux spectrum and density in a dry vertical channel if the Kurchatov Institute RRC IR-8 research reactor. One obtained data due to application of 5 sets of various activation detectors. The spectrum was reconstructed on the basis of the KASKAD combined computer program used for the method of integral neutron detectors. The derived results enable to design most efficiently experiments to irradiate and to investigate into radiation resistance of the ITER diagnostic system various components in a new irradiation channel of IR-8 research reactor
Quantum corrected non-thermal radiation spectrum from the tunnelling mechanism
Chakraborty, Subenoy; Corda, Christian
2015-01-01
Tunnelling mechanism is today considered a popular and widely used method in describing Hawking radiation. However, in relation to black hole (BH) emission, this mechanism is mostly used to obtain the Hawking temperature by comparing the probability of emission of an outgoing particle with the Boltzmann factor. On the other hand, Banerjee and Majhi reformulated the tunnelling framework deriving a black body spectrum through the density matrix for the outgoing modes for both the Bose-Einstein distribution and the Fermi-Dirac distribution. In contrast, Parikh and Wilczek introduced a correction term performing an exact calculation of the action for a tunnelling spherically symmetric particle and, as a result, the probability of emission of an outgoing particle corresponds to a non-strictly thermal radiation spectrum. Recently, one of us (C. Corda) introduced a BH effective state and was able to obtain a non-strictly black body spectrum from the tunnelling mechanism corresponding to the probability of emission o...
Mazzeo, Giuseppe; Cimmino, Alessio; Andolfi, Anna; Evidente, Antonio; Superchi, Stefano
2014-09-01
A time-dependent Density Functional Theory (TDDFT) computational simulation of the electronic circular dichroism (ECD) spectrum of the phytotoxin scytalone (1), produced by different plant pathogenic fungi and involved in melanin production, was undertaken with the aim to establish a nonempirical correlation between the spectrum and the absolute configuration of this compound. In fact, very low optical rotation data of do not afford a reliable absolute configuration assignment while, on the contrary, the use of ECD can provide a useful tool for its stereochemical description. This structurally simple molecule displayed a considerable molecular flexibility, which made it mandatory to obtain an accurate conformers distribution to get a good reproduction of the experimental ECD spectrum. Only the application of an implicit integral equation formalism Polarizable Continuum Model (IEF-PCM) solvation model in the calculations allowed us to properly describe the conformer populations and finally obtain a more than satisfactory spectral simulation.
The optical phonon spectrum of SmFeAsO
Marini, C.; Mirri, C.; Profeta, G.; Lupi, S.; Di Castro, D.; Sopracase, R.; Postorino, P.; Calvani, P.; Perucchi, A.; Massidda, S.; Tropeano, G. M.; Putti, M.; Martinelli, A.; Palenzona, A.; Dore, P.
2008-01-01
We measured the Raman and the Infrared phonon spectrum of SmFeAsO polycrystalline samples. We also performed Density Functional Theory calculations within the pseudopotential approximation to obtain the structural and dynamical lattice properties of both the SmFeAsO and the prototype LaFeAsO compounds. The measured Raman and Infrared phonon frequencies are well predicted by the optical phonon frequencies computed at the Gamma point, showing the capability of the employed ab-initio methods to ...
Broadband detection of squeezed vacuum A spectrum of quantum states
Breitenbach, G; Schiller, S; Mlynek, J; Breitenbach, Gerd; Illuminati, Fabrizio; Schiller, Stephan; Mlynek, Jurgen
1998-01-01
We demonstrate the simultaneous quantum state reconstruction of the spectral modes of the light field emitted by a continuous wave degenerate optical parametric amplifier. The scheme is based on broadband measurement of the quantum fluctuations of the electric field quadratures and subsequent Fourier decomposition into spectral intervals. Applying the standard reconstruction algorithms to each bandwidth-limited quantum trajectory, a "spectrum" of density matrices and Wigner functions is obtained. The recorded states show a smooth transition from the squeezed vacuum to a vacuum state. In the time domain we evaluated the first order correlation function of the squeezed output field, showing good agreement with the theory.
Institute of Scientific and Technical Information of China (English)
冯跟胜; 党金春; 等
1995-01-01
A method used for on line determining the change of wheat density with a automatic watering machine in a lqarge flour mill has been studied.The results show that the higher distinguishing ability is obtained when using 241Am as a γ-ray source for measuring the wheat density than using 137Cs.
U.S. Environmental Protection Agency — Road density is generally highly correlated with amount of developed land cover. High road densities usually indicate high levels of ecological disturbance. More...
Wu, Jin-Hui; Yang, Rui-Feng; Wang, Gao
2012-07-01
To improve the accuracy of the transient temperature detection system, transient temperature inversion processing algorithms was proposed based on spectrum analysis of speckle pattern interferometry. The interference fringes were formed by speckle interferometry in the system, and due to transient temperature changes that cause the material strain, the speckle interference pattern changes. The interference fringes on the measured surface were obtained by the area array CCD collection before and after deformation. The corresponding spectrum density function will change with the changes in the transient temperature, and the amplitude changes of center wavelength were inverted by the speckle pattern interferometry. Through detecting and calculating the ratio of the amplitude of the center wavelength, the transient temperature can be obtained by spectrum analysis. In the analysis and calculation for the function of transient temperature and material strain, material strain and interference fringes, the amplitude and phase function of the transient temperature change and interference fringes were derived, providing the necessary conditions for detecting spectral density function temperature. The experiment used 660 nm laser diode and SI6600 type area CCD detector. By extracting the offset of the center wavelength from the spectrum distribution function, the calculation and calibration data were compared to the data obtained with the traditional method of interference temperature detection, and the result showed that the detection accuracy can achieve 0.3%. Compared to traditional direct detection of interference fringes changes, the accuracy improved nearly three times by the method.
Study of Magnesium Diboride Clusters Using Hybrid Density Functional Theory
Directory of Open Access Journals (Sweden)
D. Rodríguez
2007-12-01
Full Text Available Using hybrid density functional theory and a relatively large basis set, the lowest energy equilibrium structure, vibrational spectrum, and natural orbital analysis were obtained for magnesium diboride clusters [(MgB2x for x=1,2, and 3]. For comparison, boron clusters [BxÃ‚Â forÃ‚Â x=2,4,Ã‚Â andÃ‚Â 6] were also considered. The MgB2 and (MgB22 showed equilibrium structures with the boron atoms in arrangements similar to what was obtained for pure boron atoms, whereas, for (MgB23 a different arrangement of boron was obtained. From the population analysis, large electron density in the boron atoms forming the clusters was observed.
The low lying glueball spectrum
Energy Technology Data Exchange (ETDEWEB)
Adam Szczepaniak; Eric Swanson
2003-12-18
The complete low-lying positive charge conjugation glueball spectrum is obtained from QCD. The formalism relies on the construction of an efficient quasiparticle gluon basis for Hamiltonian QCD in Coulomb gauge. The resulting rapidly convergent Fock space expansion is exploited to derive quenched low-lying glueball masses with no free parameters which are in remarkable agreement with lattice gauge theory.
Image analysis and classification by spectrum enhancement: new developments
Crosta, Giovanni F.
2010-01-01
The "enhanced spectrum" of an image g[.] is a function h[.] of wave-number u obtained by a sequence of operations on the power spectral density of g[.]. The main properties and the available theorems on the correspondence between spectrum enhancement and spatial differentiation, of either integer or fractional order, are stated. In order to apply the enhanced spectrum to image classification, one has to go, by interpolation, from h[.] to a polynomial q[.]. The graph of q[.] provides the set of morphological descriptors of the original image, suitable for submission to a multivariate statistical classifier. Since q[.] depends on an n-tuple, Ψ, of parameters which control image pre-processing, spectrum enhancement and interpolation, then one can train the classifier by tuning Ψ. In fact, classifier training is more articulated and relies on a "design", whereby different training sets are processed. The best performing n-tuple, Ψ*, is selected by maximizing a "design-wide" figure of merit. Next one can apply the trained classifier to recognize new images. A recent application to materials science is summarized.
Wideband luminescence of high-density InAs quantum dots on GaAsSb/GaAs layers
Osaka, Yuji; Tanabe, Hiroyuki; Yamada, Kazuhiro; Yamaguchi, Koichi
2013-09-01
In order to achieve wideband luminescence, ultrahigh density InAs quantum dots (QDs) were grown on GaAsSb buffer layers by molecular beam epitaxy under various growth conditions. Ultrahigh density of 3.8-5.2×1011 cm-2 and large size fluctuation were obtained. Photoluminescence (PL) spectra of ultrahigh density QD layers were changed by adjusting the growth conditions. Three ultrahigh density QD layers with different PL spectra were stacked on GaAs (001) substrate. The PL spectrum of edge emission revealed strong intensity and a broad linewidth of 194 nm. The presented QD structures are expected for development of wideband superluminescent diodes.
The Spectrum and Laplacian Spectrum of the Dice Lattice
Li, Shuli; Yan, Weigen; Tian, Tao
2016-07-01
The dice lattice is the dual lattice of kagomé lattice. Many physical properties on the dice lattice have been studied by physicists, such as Ising model, Glassy dynamics of Josephson arrays, and Lattice Green's function. In this paper, we derive the spectrum and Laplacian spectrum of the dice lattice with toroidal boundary condition. In addition, we apply our results to obtain the formulae of the number of spanning trees, the Kirchhoff index, and the energy of the dice lattice with toroidal boundary condition.
DEFF Research Database (Denmark)
Garnett, E S; Webber, C E; Coates, G
1977-01-01
The density of a defined volume of the human lung can be measured in vivo by a new noninvasive technique. A beam of gamma-rays is directed at the lung and, by measuring the scattered gamma-rays, lung density is calculated. The density in the lower lobe of the right lung in normal man during quiet...... breathing in the sitting position ranged from 0.25 to 0.37 g.cm-3. Subnormal values were found in patients with emphsema. In patients with pulmonary congestion and edema, lung density values ranged from 0.33 to 0.93 g.cm-3. The lung density measurement correlated well with the findings in chest radiographs...... but the lung density values were more sensitive indices. This was particularly evident in serial observations of individual patients....
Capacity limits of spectrum-sharing systems over hyper-fading channels
Ekin, Sabit
2011-01-20
Cognitive radio (CR) with spectrum-sharing feature is a promising technique to address the spectrum under-utilization problem in dynamically changing environments. In this paper, the achievable capacity gain of spectrum-sharing systems over dynamic fading environments is studied. To perform a general analysis, a theoretical fading model called hyper-fading model that is suitable to the dynamic nature of CR channel is proposed. Closed-form expressions of probability density function (PDF) and cumulative density function (CDF) of the signal-to-noise ratio (SNR) for secondary users (SUs) in spectrum-sharing systems are derived. In addition, the capacity gains achievable with spectrum-sharing systems in high and low power regions are obtained. The effects of different fading figures, average fading powers, interference temperatures, peak powers of secondary transmitters, and numbers of SUs on the achievable capacity are investigated. The analytical and simulation results show that the fading figure of the channel between SUs and primary base-station (PBS), which describes the diversity of the channel, does not contribute significantly to the system performance gain. © 2011 John Wiley & Sons, Ltd.
Spectrum Assignment with Non-Deterministic Bandwidth of Spectrum Holein Cognitive Radio Networks
Directory of Open Access Journals (Sweden)
Huang Jie
2016-01-01
Full Text Available The spectrum allocation for cognitive radio networks (CRNs has received considerable studies under the assumption that the bandwidth of spectrum holes is static. However, in practice, the bandwidth of spectrum holes is time-varied due to primary user/secondary user (PU/SU activity and mobility, which result in non-determinacy. This paper studies the spectrum allocation for CRNs with non-deterministic bandwidth of spectrum holes. We present a novel probability density function (PDF model through order statistic to describe the non-deterministic bandwidth of spectrum holes and provide a bound to approximate it. After that, a statistical spectrum allocation model based on stochastic multiple knapsack problem (MKP is established for spectrum allocation with non-deterministic bandwidth of spectrum holes. To reduce the computational complexity, we transform this stochastic programming probleminto a constant MKP though exploiting the properties of cumulative distribution function (CDF, which can be solved via MTHG algorithm by using auxiliary variable. Simulation results illustrate that the proposed statistical spectrum allocation algorithm can achieve better performances compared to the existing algorithms when the bandwidth of spectrum holes istime-varied.
Novel pricing model for spectrum leasing in secondary spectrum market
Institute of Scientific and Technical Information of China (English)
WANG Lei; XU Xing-kun; XU Wen-jun; HE Zhi-qiang; LIN Jia-ru
2010-01-01
According to the property rights model of cognitive radio,primary users who own the spectral resource have the right to lease or trade part of it to secondary users in exchange for appropriate profit. In this paper,an implementation of this framework is investigated,where a primary link can lease the owned spectrum to secondary nodes in exchange for cooperation (relaying). A novel pricing model is proposed that enables the trading between spectrum and cooperation. Based on the demand of secondary nodes,the primary link attempts to maximize its quality of service (QoS) by setting the price of spectrum. Taking the price asked by primary link,the secondary nodes aim to obtain most profits by deciding the amount of spectrum to buy and then pay for it by cooperative transmission. The investigated model is conveniently cast in the framework of seller/buyer (Stackelberg) games. Analysis and numerical results show that our pricing model is effective and practical for spectrum leasing based on trading spectral resource for cooperation.
Spectrum resolving power of hearing: measurements, baselines, and influence of maskers
Directory of Open Access Journals (Sweden)
Alexander Ya. Supin
2011-06-01
Full Text Available Contemporary methods of measurement of frequency tuning in the auditory system are reviewed. Most of them are based on the frequency-selective masking paradigm and require multi-point measurements (a number of masked thresholds should be measured to obtain a single frequency-tuning estimate. Therefore, they are rarely used for practical needs. As an alternative approach, frequency-selective properties of the auditory system may be investigated using probes with complex frequency spectrum patterns, in particular, rippled noise that is characterized by a spectrum with periodically alternating maxima and minima. The maximal ripple density discriminated by the auditory system is a convenient measure of the spectrum resolving power (SRP. To find the highest resolvable ripple density, a phase-reversal test has been suggested. Using this technique, normal SRP, its dependence on probe center frequency, spectrum contrast, and probe level were measured. The results were not entirely predictable by frequency-tuning data obtained by masking methods. SRP is influenced by maskers, with on- and off-frequency maskers influencing SRP very differently. Dichotic separation of the probe and masker results in almost complete release of SRP from influence of maskers.
Target tracking based on frequency spectrum amplitude
Institute of Scientific and Technical Information of China (English)
Guo Huidong; Zhang Xinhua; Xia Zhijun
2006-01-01
The amplitude of frequency spectrum can be integrated with probabilistic data association (PDA) to distinguish the target with clutter echoes, especially in low SNR underwater environment. A new target-tracking algorithm is presented which adopts the amplitude of frequency spectrum to improve target tracking in clutter. The probabilistic density distribution of frequency spectrum amplitude is analyzed. By simulation, the results show that the algorithm is superior to PDA. This approach enhances stability for the association probability and increases the performance of target tracking.
Seyfert 1 composite spectrum using SDSS Legacy survey data
Pol, Nihan; Wadadekar, Yogesh
2017-02-01
We present a rest-frame composite spectrum for Seyfert 1 galaxies using spectra obtained from the 12th Data Release of the Sloan Digital Sky Survey. The spectrum is constructed by combining data from a total of 10112 galaxies, spanning a redshift range of 0-0.793. We produce an electronic table of the median and geometric mean composite Seyfert 1 spectrum. We measure the spectral index of the composite spectrum, and compare it with that of the composite quasar spectrum. We also measure the flux and width of the strong emission lines present in the composite spectrum. We compare the entire spectrum with the quasar spectrum in the context of the unification model for active galactic nuclei. The two composite spectra match extremely well in the blue part of the spectrum, while there is an offset in flux in the red portion of the spectrum.
Level densities of iron isotopes and lower-energy enhancement of y-strength function
Energy Technology Data Exchange (ETDEWEB)
Voinov, A V; Grimes, S M; Agvaanluvsan, U; Algin, E; Belgya, T; Brune, C R; Guttormsen, M; Hornish, M J; Massey, T N; Mitchell, G; Rekstad, J; Schiller, A; Siem, S
2005-08-30
The neutron spectrum from the {sup 55}Mn(d,n){sup 56}Fe reaction has been measured at E{sub d} = 7 MeV. The level density of {sup 56}Fe obtained from neutron evaporation spectrum has been compared to the level density from Oslo-type {sup 57}Fe({sup 3}He, a{gamma}){sup 56}Fe experiment [1]. The good agreement supports the recent results [1, 8] including an availability of a low-energy enhancement in the {gamma}-strength function for iron isotopes. The new level density function allowed us to investigate an excitation energy dependence of this enhancement, which is shown to increase with increasing excitation energy.
Bogatov, A. P.; Drakin, A. E.; D'yachkov, N. V.; Gushchik, T. I.
2016-08-01
Expressions for the amplitudes of amplified spontaneous emission waves in a diode amplifier near the frequency ω0 of a 'strong' input monochromatic wave have been derived in terms of a random function of a stationary Gaussian process. We have found expressions for the spectral density of the amplitudes and shown that, on the red side of the spectrum with respect to frequency ω0, spontaneous emission waves obtain additional nonlinear gain, induced by the strong wave, whereas on the blue side of the spectrum an additional loss is induced. Such behaviour of the amplitudes of amplified waves agrees with previous results.
Kurtosis, skewness, and non-Gaussian cosmological density perturbations
Luo, Xiaochun; Schramm, David N.
1993-01-01
Cosmological topological defects as well as some nonstandard inflation models can give rise to non-Gaussian density perturbations. Skewness and kurtosis are the third and fourth moments that measure the deviation of a distribution from a Gaussian. Measurement of these moments for the cosmological density field and for the microwave background temperature anisotropy can provide a test of the Gaussian nature of the primordial fluctuation spectrum. In the case of the density field, the importance of measuring the kurtosis is stressed since it will be preserved through the weakly nonlinear gravitational evolution epoch. Current constraints on skewness and kurtosis of primeval perturbations are obtained from the observed density contrast on small scales and from recent COBE observations of temperature anisotropies on large scales. It is also shown how, in principle, future microwave anisotropy experiments might be able to reveal the initial skewness and kurtosis. It is shown that present data argue that if the initial spectrum is adiabatic, then it is probably Gaussian, but non-Gaussian isocurvature fluctuations are still allowed, and these are what topological defects provide.
Li, Xiongwei; Fu, Yangting; Li, Zheng; Liu, Jianming; Ni, Weidou
2014-01-01
Measurements of carbon content in coal using laser-induced breakdown spectroscopy (LIBS) is limited by its low measurement precision and accuracy. A spectrum standardization method was proposed to achieve both reproducible and accurate results for the quantitative analysis of carbon content in coal with LIBS. The proposed method utilized the molecular carbon emissions to compensate the diminution of atomic carbon emission caused by matrix effect. The compensated carbon line intensities were further converted into an assumed standard state with fixed plasma temperature, electron density, and total number density of elemental carbon, which is proportional to its concentration in the coal samples. In addition, in order to obtained better compensation for total carbon number density fluctuations, an iterative algorithm was applied, which is different from our previous standardization calculations. The modified spectrum standardization model was applied to the measurement of carbon content in 24 bituminous coal sa...
Measuring the VIPERS galaxy power spectrum at z∼1
Rota, Stefano; Bel, Julien; Granett, Ben; Guzzo, Luigi
2016-10-01
The VIMOS Public Extragalactic Redshift Survey [VIPERS, Guzzo et al. 2014] is using the VIMOS spectrograph at the ESO VLT to measure redshifts for ~ 100,000 galaxies with IAB < 22.5 and 0.5 < z < 1.2, over an area of 24 deg2 (split over the W1 and W4 fields of CFHTLS). VIPERS currently provides, at such redshifts, the best compromise between volume, number of galaxies and dense spatial sampling. We present here the first estimate of the power spectrum of the galaxy distribution, P(k), at redshifts z ~ 0.75 and z ~ 1, obtained from the ~ 55,000 redshifts of the PDR-1 data release. We discuss first constraints on cosmological quantities, as the matter density and the baryonic fraction, obtained for the first time at an epoch when the Universe was about half its current age.
Directory of Open Access Journals (Sweden)
João Alfredo Braida
2006-08-01
ótese de que a palha existente sobre o solo é capaz de absorver parte da energia de compactação produzida pelo trânsito de máquinas e animais.The susceptibility of soils to compaction, measured by the Proctor test, decreases with increasing soil organic matter (SOM content. For a given energy level, with increasing SOM contents the maximum obtained density decreases and the corresponding critical moisture content increases. Due to its low density, elasticity and deformation susceptibility, straw is potentially able to dissipate applied loads. This study was conducted to evaluate the SOM effect on the soil compaction curve and to evaluate the ability that mulch has to absorb compactive energy in the Proctor test. The compaction test was carried out using soil surface samples (0 to 0.05 m of a Hapludalf, with sandy loam texture at its soil surface, and an Oxisol, with clayey texture at its soil surface, both with variations in the SOM content. The maximum density, the critical moisture content, the liquid and plastic limits, and the soil organic carbon content were determined. A second test was performed to evaluate the ability of mulch to absorb compactive energy, by compacting Hapludalf samples with the presence of a straw layer on the soil surface, inside a Proctor cylinder, at amounts corresponding to 2, 4, 8 and 12 Mg ha-1. SOM accumulation reduced the maximum density and increased the critical moisture content, suggesting an increased resistance to soil compaction. In the Proctor test the straw on the soil surface dissipated up to 30 % of the compactive energy and reduced the bulk density, confirming the hypothesis that mulch can absorb part of the compactive energy caused by machine traffic and by animals.
Asymptotic Density of Eigenvalue Clusters for the Perturbed Landau Hamiltonian
Pushnitski, Alexander; Villegas-Blas, Carlos
2011-01-01
We consider the Landau Hamiltonian (i.e. the 2D Schroedinger operator with constant magnetic field) perturbed by an electric potential V which decays sufficiently fast at infinity. The spectrum of the perturbed Hamiltonian consists of clusters of eigenvalues which accumulate to the Landau levels. Applying a suitable version of the anti-Wick quantization, we investigate the asymptotic distribution of the eigenvalues within a given cluster as the number of the cluster tends to infinity. We obtain an explicit description of the asymptotic density of the eigenvalues in terms of the Radon transform of the perturbation potential V.
Lattice simulation of the SU(2) chiral model at zero and non-zero pion density
Rindlisbacher, Tobias
2015-01-01
We propose a flux representation based lattice formulation of the partition function corresponding to the SU(2) principal chiral Lagrangian, including a chemical potential and scalar/pseudo-scalar source terms. Lattice simulations are then used to obtain non-perturbative properties of the theory, in particular its mass spectrum at zero and non-zero pion density. We also sketch a method to efficiently measure general one- and two-point functions during the worm updates.
Phonon density of states in Tl 2CaBa 2Cu 2O 8
Chaplot, S. L.; Dasannacharya, B. A.; Mukhopadhyay, R.; Rao, K. R.; Vijayaraghavan, P. R.; Iyer, R. M.; Phatak, G. M.; Yakhmi, J. V.
1991-10-01
The neutron-weighted phonon density of states in the high-temperature superconductor Tl 2CaBa 2Cu 2O 8 ( Tc=107 K) is obtained from coherent inelastic neutron scattering measurements at the Dhruva reactor at 300 K. The phonon spectrum is qualitatively similar to that in the 90 K superconductor YBa 2Cu 3O 7, and compares well with an independent lattice dynamical calculation.
Quantum Corrected Non-Thermal Radiation Spectrum from the Tunnelling Mechanism
Directory of Open Access Journals (Sweden)
Subenoy Chakraborty
2015-06-01
Full Text Available The tunnelling mechanism is today considered a popular and widely used method in describing Hawking radiation. However, in relation to black hole (BH emission, this mechanism is mostly used to obtain the Hawking temperature by comparing the probability of emission of an outgoing particle with the Boltzmann factor. On the other hand, Banerjee and Majhi reformulated the tunnelling framework deriving a black body spectrum through the density matrix for the outgoing modes for both the Bose-Einstein distribution and the Fermi-Dirac distribution. In contrast, Parikh and Wilczek introduced a correction term performing an exact calculation of the action for a tunnelling spherically symmetric particle and, as a result, the probability of emission of an outgoing particle corresponds to a non-strictly thermal radiation spectrum. Recently, one of us (C. Corda introduced a BH effective state and was able to obtain a non-strictly black body spectrum from the tunnelling mechanism corresponding to the probability of emission of an outgoing particle found by Parikh and Wilczek. The present work introduces the quantum corrected effective temperature and the corresponding quantum corrected effective metric is written using Hawking’s periodicity arguments. Thus, we obtain further corrections to the non-strictly thermal BH radiation spectrum as the final distributions take into account both the BH dynamical geometry during the emission of the particle and the quantum corrections to the semiclassical Hawking temperature.
Aspects of unconventional density waves
Maki, Kazumi; Dóra, Balázs; Virosztek, Attila
2003-12-01
Recently many people discuss unconventional density waves (i.e. unconventional charge density waves (UCDW) and unconventional spin density waves (USDW)). Unlike in conventional density waves, the quasiparticle spectrum in these systems is gapless. Also these systems remain metallic. Indeed it appears that there are many candidates for UDW. The low temperature phase of α-(BEDT-TTF)2KHg(SCN)4, the antiferromagnetic phase in URu2Si2, the CDW in transition metal dichalcogenite NbSe2, the pseudogap phase in high Tc cuprate superconductors, the glassy phase in organic superconductor κ-(BEDT-TTF)2Cu[N(CN)2]Br. After a brief introduction on UCDW and USDW, we shall discuss some of the above systems, where we believe we have evidence for unconventional density waves.
Can the tinnitus spectrum identify tinnitus subgroups?
Directory of Open Access Journals (Sweden)
Karin M Heijneman
2013-01-01
Full Text Available The tinnitus spectrum is a psycho-acoustic metric of tinnitus. Previous work found a tight relation between the spectrum and the tone audiogram. This suggests that the spectrum and the audiogram provide essentially the same information, and the added value of the spectrum is limited. In order to test whether the spectrum shows tinnitus characteristics that cannot be inferred from the audiogram, we re-examined the relation between the tinnitus spectrum and the tone audiogram, in a group of 80 tinnitus patients. We defined three subgroups of patients, using the shape of their tinnitus spectrum: (1 patients with a spectrum, monotonously increasing with frequency (2 patients with a distinct peak in their spectrum, (3 all other patients. Patients in group 3 typically showed low frequency tinnitus spectra. In all three groups, the largest hearing loss was at high frequencies (>2 kHz. The mean audiograms of group 1 and 2 were remarkably similar; group 3 had an additional hearing loss for the lower frequencies (<2 kHz. The three groups did not differ with respect to age, sex, or tinnitus questionnaire outcomes. In subgroups 2 and 3, the shape of the spectrum clearly differed from that of the tone audiogram. In other words, the spectrum technique provided information that could not have been obtained by tone audiometry alone. Therefore, the spectrum measurement may develop into a technique that can differentiate between classes of tinnitus. This may eventually contribute to the effective management of tinnitus, as various classes of tinnitus may require different therapeutic interventions.
Structure of the spectrum of infinite dimensional Hamiltonian operators
Institute of Scientific and Technical Information of China (English)
Alatancang
2008-01-01
This paper deals with the structure of the spectrum of infinite dimensional Hamiltonian operators.It is shown that the spectrum,the union of the point spectrum and residual spectrum,and the continuous spectrum are all symmetric with respect to the imaginary axis of the complex plane. Moreover,it is proved that the residual spectrum does not contain any pair of points symmetric with respect to the imaginary axis;and a complete characterization of the residual spectrum in terms of the point spectrum is then given.As applications of these structure results,we obtain several necessary and sufficient conditions for the residual spectrum of a class of infinite dimensional Hamiltonian operators to be empty.
Seyfert 1 Composite Spectrum using SDSS Legacy Survey Data
Pol, Nihan
2016-01-01
We present a rest-frame composite spectrum for Seyfert 1 galaxies using spectra obtained from the DR12 release of the Sloan Digital Sky Survey (SDSS). The spectrum is constructed by combining data from a total of 10,112 galaxies, spanning a redshift range of 0 to 0.793. We produce an electronic table of the median and geometric mean composite Seyfert 1 spectrum. We measure the spectral index of the composite spec- trum, and compare it with that of the composite quasar spectrum. We also measure the flux and width of the strong emission lines present in the composite spectrum. We compare the entire spectrum with the quasar spectrum in the context of the AGN unification model. The two composite spectra match extremely well in the blue part of the spectrum, while there is an offset in flux in the red portion of the spectrum.
14 N NQR spectrum of sildenafil citrate
Stephenson, David; Singh, Nadia
2015-04-01
The 14N nuclear quadrupole resonance (NQR) spectrum of sildenafil citrate tablets has been recorded allowing the quadrupole coupling constants and asymmetry parameters of all six unique nitrogen atoms in its structure to be determined. A density function calculation gives results that are largely in agreement with the experimental values.
The Weibull functional form for the energetic particle spectrum at interplanetary shock waves
Laurenza, M.; Consolini, G.; Storini, M.; Pallocchia, G.; Damiani, A.
2016-11-01
Transient interplanetary shock waves are often associated with high energy particle enhancements, which are called energetic storm particle (ESP) events. Here we present a case study of an ESP event, recorded by the SEPT, LET and HET instruments onboard the STEREO B spacecraft, on 3 October 2011, in a wide energy range from 0.1 MeV to ∼ 30 MeV. The obtained particle spectrum is found to be reproduced by a Weibull like shape. Moreover, we show that the Weibull spectrum can be theoretically derived as the asymptotic steady state solution of the diffusion loss equation by assuming anomalous diffusion for particle velocity. The evaluation of Weibull's parameters obtained from particle observations and the power spectral density of the turbulent fluctations in the shock region, support this scenario and suggest that stochastic acceleration can contribute significantly to the acceleration of high energetic particles at collisioness shock waves.
Directory of Open Access Journals (Sweden)
Jorge A. Suby
2006-12-01
Full Text Available La densidad mineral ósea ha sido identificada como una de las propiedades de los huesos que mediatiza la acción de los agentes y procesos tafonómicos (meteorización, atrición, etc. sobre los conjuntos arqueológicos. En los últimos años se han planteado algunos problemas en torno a las metodologías empleadas para el análisis de densidad mineral ósea y su aplicación en arqueología. En el presente trabajo, se comparan los resultados generados a través de dos métodos diferentes de obtención de valores de densidad mineral ósea mediante la técnica de Absorciometría Fotónica de Rayos X, empleados anteriormente por otros autores. Si bien el estudio de las Propiedades Óseas Intrínsecas (forma, tamaño y densidad mineral ósea, entre otros factores ha sido vinculado anteriormente a la tafonomía de restos faunísticos, son escasos los trabajos que estudian estos aspectos sobre el registro biológico humano. En este sentido se discute la aplicación de información biomecánica a conjuntos arqueológicos humanos, como indicador de la acción de procesos tafonómicos ligados a la densidad mineral ósea.Bone mineral density (BMD has been identified as a one of the bone properties that mediate the action of agents and taphonomic processes (weathering, attrition, etc. on archaeological assemblages. In recent years, several problems have been described for methods of BMD evaluation and their application in archaeology. In this paper, results are compared of two different Photon Abpsortiometric methods (DXA to obtain BMD values. Furthermore, their application is interpreted for two human bone assemblages from Tierra del Fuego. Even though BMD information was interpreted in the past from many faunal assemblages, this kind of information has only been included in a few studies related to human remains that analyze bone structure as a taphonomic indicator. In this sense, the application of biomechanical information to human bone assemblages
A phenomenological model for the X-ray spectrum of Nova V2491 Cygni
Pinto, Ciro; Verbunt, Frank; Kaastra, Jelle S; Costantini, Elisa; Detmers, Rob G
2012-01-01
The X-ray flux of Nova V2491 Cyg reached a maximum some forty days after optical maximum. The X-ray spectrum at that time, obtained with the RGS of XMM-Newton, shows deep, blue-shifted absorption by ions of a wide range of ionization. We show that the deep absorption lines of the X-ray spectrum at maximum, and nine days later, are well described by the following phenomenological model with emission from a central blackbody and from a collisionally ionized plasma (CIE). The blackbody spectrum (BB) is absorbed by three main highly-ionized expanding shells; the CIE and BB are absorbed by cold circumstellar and interstellar matter that includes dust. The outflow density does not decrease monotonically with distance. The abundances of the shells indicate that they were ejected from an O-Ne white dwarf. We show that the variations on time scales of hours in the X-ray spectrum are caused by a combination of variation in the central source and in the column density of the ionized shells. Our phenomenological model gi...
Energy Technology Data Exchange (ETDEWEB)
Tikhonov, E. V., E-mail: tikhonov@mig.phys.msu.ru [Moscow State University (Russian Federation); Uspenskii, Yu. A. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation); Khokhlov, D. R. [Moscow State University (Russian Federation)
2015-06-15
A quasiparticle electronic spectrum belongs to the characteristics of nanoobjects that are most important for applications. The following methods of calculating the electronic spectrum are analyzed: the Kohn-Sham equations of the density functional theory (DFT), the hybrid functional method, the GW approximation, and the Lehmann approximation used in the spectral representation of one-electron Green’s function. The results of these approaches are compared with the data of photoemission measurements of benzene, PTCDA, and phthalocyanine (CuPc, H{sub 2}Pc, FePc, PtPc) molecules, which are typical representatives of organic molecular semiconductors (OMS). This comparison demonstrates that the Kohn-Sham equations of DFT incorrectly reproduce the electronic spectrum of OMS. The hybrid functional method correctly describes the spectrum of the valence and conduction bands; however, the HOMO-LUMO gap width is significantly underestimated. The correct gap width is obtained in both the GW approximation and the Lehmann approach, and the total energy in this approach can be calculated in the local density approximation of DFT.
Obtaining the borders of urban areas
Comin, Cesar Henrique; Costa, Luciano da Fontoura
2015-01-01
The access to an ever increasing amount of information in the modern world gave rise to the development of many quantitative indicators about urban regions in the globe. Therefore, there is a growing need for a precise definition of how to delimit urban regions, so as to allow proper respective characterization and modeling. Here we present a straightforward methodology to automatically detect urban region borders. The method is based on the density of street crossings around a single seed point associated to the urban area of interest. We exemplify the potential of the methodology by characterizing the geometry and topology of 21 urban regions obtained from 8 distinct countries. The geometry is studied by employing the lacunarity measurement, which is associated to the regularity of holes contained in a pattern. The topology is analyzed by associating the betweenness centrality of the streets with their respective class, such as motorway or residential, obtained from a database.
Subsampling for graph power spectrum estimation
Chepuri, Sundeep Prabhakar
2016-10-06
In this paper we focus on subsampling stationary random signals that reside on the vertices of undirected graphs. Second-order stationary graph signals are obtained by filtering white noise and they admit a well-defined power spectrum. Estimating the graph power spectrum forms a central component of stationary graph signal processing and related inference tasks. We show that by sampling a significantly smaller subset of vertices and using simple least squares, we can reconstruct the power spectrum of the graph signal from the subsampled observations, without any spectral priors. In addition, a near-optimal greedy algorithm is developed to design the subsampling scheme.
Spectrum of the Anomalous Microwave Emission in the North Celestial Pole with WMAP 7-Year Data
Directory of Open Access Journals (Sweden)
Anna Bonaldi
2012-01-01
Full Text Available We estimate the frequency spectrum of the diffuse anomalous microwave emission (AME on the North Celestial Pole (NCP region of the sky with the Correlated Component Analysis (CCA component separation method applied to WMAP 7-yr data. The NCP is a suitable region for this analysis because the AME is weakly contaminated by synchrotron and free-free emission. By modeling the AME component as a peaked spectrum we estimate the peak frequency to be 21.7±0.8 GHz, in agreement with previous analyses which favored νp < 23 GHz. The ability of our method to correctly recover the position of the peak is verified through simulations. We compare the estimated AME spectrum with theoretical spinning dust models to constrain the hydrogen density nH. The best results are obtained with densities around 0.2–0.3 cm−3, typical of warm ionised medium (WIM to warm neutral medium (WNM conditions. The degeneracy with the gas temperature prevents an accurate determination of nH, especially for low hydrogen ionization fractions, where densities of a few cm−3 are also allowed.
Directory of Open Access Journals (Sweden)
Alexander Kramida
2017-02-01
Full Text Available New wavelength measurements in the vacuum ultraviolet (VUV, ultraviolet and visible spectral regions have been combined with available literature data to refine and extend the description of the spectrum of singly ionized copper (Cu II. In the VUV region, we measured 401 lines using a concave grating spectrograph and photographic plates. In the UV and visible regions, we measured 276 lines using a Fourier-transform spectrometer. These new measurements were combined with previously unpublished data from the thesis of Ross, with accurate VUV grating measurements of Kaufman and Ward, and with less accurate older measurements of Shenstone to construct a comprehensive list of ≈2440 observed lines, from which we derived a revised set of 379 optimized energy levels, complemented with 89 additional levels obtained using series formulas. Among the 379 experimental levels, 29 are new. Intensities of all lines observed in different experiments have been reduced to the same uniform scale by using newly calculated transition probabilities (A-values. We combined our calculations with published measured and calculated A-values to provide a set of 555 critically evaluated transition probabilities with estimated uncertainties, 162 of which are less than 20%.
Energy Technology Data Exchange (ETDEWEB)
Heitmann, Katrin [Los Alamos National Laboratory; Habib, Salman [Los Alamos National Laboratory; Higdon, David [Los Alamos National Laboratory; Williams, Brian J [Los Alamos National Laboratory; White, Martin [Los Alamos National Laboratory; Wagner, Christian [Los Alamos National Laboratory
2008-01-01
The power spectrum of density fluctuations is a foundational source of cosmological information. Precision cosmological probes targeted primarily at investigations of dark energy require accurate theoretical determinations of the power spectrum in the nonlinear regime. To exploit the observational power of future cosmological surveys, accuracy demands on the theory are at the one percent level or better. Numerical simulations are currently the only way to produce sufficiently error-controlled predictions for the power spectrum. The very high computational cost of (precision) N-body simulations is a major obstacle to obtaining predictions in the nonlinear regime, while scanning over cosmological parameters. Near-future observations, however, are likely to provide a meaningful constraint only on constant dark energy equation of state 'wCDM' cosmologies. In this paper we demonstrate that a limited set of only 37 cosmological models -- the 'Coyote Universe' suite -- can be used to predict the nonlinear matter power spectrum at the required accuracy over a prior parameter range set by cosmic microwave background observations. This paper is the second in a series of three, with the final aim to provide a high-accuracy prediction scheme for the nonlinear matter power spectrum for wCDM cosmologies.
Modelling the TSZ power spectrum
Energy Technology Data Exchange (ETDEWEB)
Bhattacharya, Suman [Los Alamos National Laboratory; Shaw, Laurie D [YALE; Nagai, Daisuke [YALE
2010-01-01
The structure formation in university is a hierarchical process. As universe evolves, tiny density fluctuations that existed in the early universe grows under gravitational instability to form massive large scale structures. The galaxy clusters are the massive viralized objects that forms by accreting smaller clumps of mass until they collapse under their self-gravity. As such galaxy clusters are the youngest objects in the universe which makes their abundance as a function of mass and redshift, very sensitive to dark energy. Galaxy clusters can be detected by measuring the richness in optical waveband, by measuring the X-ray flux, and in the microwave sky using Sunyaev-Zel'dovich (SZ) effect. The Sunyaev-Zel'dovich (SZ) effect has long been recognized as a powerful tool for detecting clusters and probing the physics of the intra-cluster medium. Ongoing and future experiments like Atacama Cosmology Telescope, the South Pole Telescope and Planck survey are currently surveying the microwave sky to develop large catalogs of galaxy clusters that are uniformly selected by the SZ flux. However one major systematic uncertainties that cluster abundance is prone to is the connection between the cluster mass and the SZ flux. As shown by several simulation studies, the scatter and bias in the SZ flux-mass relation can be a potential source of systematic error to using clusters as a cosmology probe. In this study they take a semi-analytic approach for modeling the intra-cluster medium in order to predict the tSZ power spectrum. The advantage of this approach is, being analytic, one can vary the parameters describing gas physics and cosmology simultaneously. The model can be calibrated against X-ray observations of massive, low-z clusters, and using the SZ power spectrum which is sourced by high-z lower mass galaxy groups. This approach allows us to include the uncertainty in gas physics, as dictated by the current observational uncertainties, while measuring the
Obtaining corneal tissue for keratoplasty.
Navarro Martínez-Cantullera, A; Calatayud Pinuaga, M
2016-10-01
Cornea transplant is the most common tissue transplant in the world. In Spain, tissue donation activities depend upon transplant coordinator activities and the well-known Spanish model for organ and tissue donation. Tissue donor detection system and tissue donor evaluation is performed mainly by transplant coordinators using the Spanish model on donation. The evaluation of a potential tissue donor from detection until recovery is based on an exhaustive review of the medical and social history, physical examination, family interview to determine will of the deceased, and a laboratory screening test. Corneal acceptance criteria for transplantation have a wider spectrum than other tissues, as donors with active malignancies and infections are accepted for kearatoplasty in most tissue banks. Corneal evaluation during the whole process is performed to ensure the safety of the donor and the recipient, as well as an effective transplant. Last step before processing, corneal recovery, must be performed under standard operating procedures and in a correct environment. Copyright © 2016 Sociedad Española de Oftalmología. Published by Elsevier España, S.L.U. All rights reserved.
An algorithm for noise correction of dual-energy computed tomography material density images.
Maia, Rafael Simon; Jacob, Christian; Hara, Amy K; Silva, Alvin C; Pavlicek, William; Ross, Mitchell J
2015-01-01
Dual-energy computed tomography (DECT) images can undergo a two-material decomposition process which results in two images containing material density information. Material density images obtained by that process result in images with increased pixel noise. Noise reduction in those images is desirable in order to improve image quality. A noise reduction algorithm for material density images was developed and tested. A three-level wavelet approach combined with the application of an anisotropic diffusion filter was used. During each level, the resulting noise maps are further processed, until the original resolution is reached and the final noise maps obtained. Our method works in image space and, therefore, can be applied to any type of material density images obtained from any DECT vendor. A quantitative evaluation of the noise-reduced images using the signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and 2D noise power spectrum was done to quantify the improvements. The noise reduction algorithm was applied to a set of images resulting in images with higher SNR and CNR than the raw density images obtained by the decomposition process. The average improvement in terms of SNR gain was about 49 % while CNR gain was about 52 %. The difference between the raw and filtered regions of interest mean values was far from reaching statistical significance (minimum [Formula: see text], average [Formula: see text]). We have demonstrated through a series of quantitative analyses that our novel noise reduction algorithm improves the image quality of DECT material density images.
Competition with Dynamic Spectrum Leasing
Duan, Lingjie; Shou, Biying
2010-01-01
This paper presents a comprehensive analytical study of two competitive cognitive operators' spectrum leasing and pricing strategies, taking into account operators' heterogeneity in leasing costs and users' heterogeneity in transmission power and channel conditions. We model the interactions between operators and users as a three-stage dynamic game, where operators make simultaneous spectrum leasing and pricing decisions in Stages I and II, and users make purchase decisions in Stage III. Using backward induction, we are able to completely characterize the game's equilibria. We show that both operators make the equilibrium leasing and pricing decisions based on simple threshold policies. Moreover, two operators always choose the same equilibrium price despite their difference in leasing costs. Each user receives the same signal-to-noise-ratio (SNR) at the equilibrium, and the obtained payoff is linear in its transmission power and channel gain. We also compare the duopoly equilibrium with the coordinated case ...
Rigidity spectrum of Forbush decrease
Sakakibara, S.; Munakata, K.; Nagashima, K.
1985-01-01
Using data from neutron monitors and muon telescopes at surface and underground stations, the average rigidity spectrum of Forbush decreases (Fds) during the period of 1978-1982 were obtained. Thirty eight Ed-events are classified into two groups Hard Fd and Soft Fd according to size of Fd at Sakashita station. It is found that a spectral form of fractional-power type (P to the-gamma sub 1 (P+P sub c) to the -gamma sub2) is more suitable for the present purpose than that of power-exponential type or of power type with an upper limiting rigidity. The best fitted spectrum of fractional-power type is expressed by gamma sub1 = 0.37, gamma sub2 = 0.89 and P subc = 10 GV for Hard Fd and gamma sub1 = 0.77, gamma sub2 = 1.02 and P sub c - 14GV for Soft Fd.
Viel, M; Viel, Matteo; Haehnelt, Martin G.
2006-01-01
(abridged) The flux power spectrum of the Lyman-alpha forest in quasar (QSO) absorption spectra is sensitive to a wide range of cosmological and astrophysical parameters and instrumental effects. Modelling the flux power spectrum in this large parameter space to an accuracy comparable to the statistical uncertainty of large samples of QSO spectra is very challenging. We use here a coarse grid of hydrodynamical simulations run with GADGET-2 to obtain a ``best guess'' model around which we calculate a finer grid of flux power spectra using a Taylor expansion of the flux power spectrum to first order. We find that the SDSS flux power spectrum alone is able to constrain a wide range of parameters including the amplitude of the matter power spectrum sigma_8, the matter density Omega_m, the spectral index of primordial density fluctuations n, the effective optical depth tau_eff and its evolution. The thermal history of the Intergalactic Medium (IGM) is, however, poorly constrained and the SDSS data favour either an...
Autism Spectrum Disorder (ASD)
... Español (Spanish) Recommend on Facebook Tweet Share Compartir Autism spectrum disorder (ASD) is a developmental disability that can cause ... factors that may put children at risk for autism spectrum disorder (ASD) and other developmental disabilities. More E-mail ...
Energy Technology Data Exchange (ETDEWEB)
Stebbins, A.
1997-05-01
Here we give an introduction to the observed spectrum of the Cosmic Microwave Background Radiation (CMBR) and discuss what can be learned about it. Particular attention will be given to how Compton scattering can distort the spectrum of the CMBR. An incomplete bibliography of relevant papers is also provided.
Nekovee, Maziar; Rudd, Richard
2017-01-01
In this paper an overview is given of the current status of 5G industry standards, spectrum allocation and use cases, followed by initial investigations of new opportunities for spectrum sharing in 5G using cognitive radio techniques, considering both licensed and unlicensed scenarios. A particular attention is given to sharing millimeter-wave frequencies, which are of prominent importance for 5G.
Fetal Alcohol Spectrum Disorder
Caley, Linda M.; Kramer, Charlotte; Robinson, Luther K.
2005-01-01
Fetal alcohol spectrum disorder (FASD) is a serious and widespread problem in this country. Positioned within the community with links to children, families, and healthcare systems, school nurses are a critical element in the prevention and treatment of those affected by fetal alcohol spectrum disorder. Although most school nurses are familiar…
Wave Reflection Coefficient Spectrum
Institute of Scientific and Technical Information of China (English)
俞聿修; 邵利民; 柳淑学
2003-01-01
The wave reflection coefficient frequency spectrum and directional spectrum for concrete face slope breakwaters and rubble mound breakwaters are investigated through physical model tests in the present study. The reflection coefficients of oblique irregular waves are analyzed by the Modified Two-Point Method (MTPM) proposed by the authors. The results show that the wave reflection coefficient decreases with increasing wave frequency and incident angle or decreasing structure slope. The reflection coefficient frequency spectrum and its variation with Iribarren number are given in this paper. The paper also suggests an empirical 3-dimensional reflection coefficient spectrum, i.e. reflection coefficient directional spectrum, which can be used to illustrate quantitatively the variation of reflection coefficient with the incident angle and the Iribarren number for oblique irregular waves.
Directory of Open Access Journals (Sweden)
Ana Lúcia Peixoto de Freitas
2003-12-01
Full Text Available His study was performed to compare the methods of detection and to estimate the prevalence of extended-spectrum beta-lactamases (ESBL among Klebsiella spp and E.coli in a university hospital in southern Brazil. We also used a molecular typing method to evaluate the genetic correlation between isolates of ESBL K.pneumoniae. Production of ESBL was investigated in 95 clinical isolates of Klebsiella spp and Escherichia coli from Hospital de Clínicas de Porto Alegre, using Kirby-Bauer zone diameter (KB, double-disk diffusion (DD, breakpoint for ceftazidime (MIC CAZ, increased zone diameter with clavulanate (CAZ/CAC and ratio of ceftazidime MIC/ceftazidime-clavulanate MIC (MIC CAZ/CAC. Molecular typing was performed by DNA macrorestriction analysis followed by pulsed-field gel electrophoresis. The KB method displayed the highest rates of ESBL (up to 70% of Klebsiella and 59% of E.coli, contrasting with all the other methods (p Este estudo foi desenvolvido para comparar métodos de detecção e para estimar a prevalência de Klebsiella spp e E.coli produtoras de beta-lactamases de espetro ampliado (ESBL em um Hospital Universitário no sul do Brasil. A correlação genética, determinada através de método molecular de tipagem, entre as amostras de K. pneumoniae também foi determinada. A produção de ESBL foi investigada em 95 amostras de Klebsiella spp e E.coli obtidas de pacientes no Hospital de Clínicas de Porto Alegre usando-se: medida do diâmetro a zona de inibição (KB, dupla-difusão de disco (DD, valores de concentração inibitória mínima da ceftazidima (MIC CAZ, aumento do diâmetro da zona de inibição com adição de clavulanato (CAZ/CAC e a relação entre o MIC da ceftazidima/MIC ceftazidima com clavulanato (MIC CAZ/CAC. A tipagem molecular foi realizada utilizando-se o método de macrorestrição de DNA e eletroforese em campo pulsado (PFGE. O método KB apresentou as maiores taxas de produção de ESBL (> 70% para Klebsiella e
Earth's density flattening and hypothesis of latitudinal normal density
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
In this paper, the definition of latitudinal density and density flattening of the level ellipsoid is given, and integral formulas of latitudinal density for pole gravity and equator gravity are derived. According to the pole gravity condition and equator gravity condition for the level ellipsoid, latitudinal density distribution function of the level ellipsoid is obtained. It is proved mathematically that latitudinal density of the earth's equator is larger than that of the pole, the earth's density flat-tening calculated preliminarily is 1/322, and hypothesis of the earth's latitudinal normal density is further proposed, so that theoretical preparation for studying the forming cause of the earth gravity in problems such as continent drift, mantle convection, and submarine extension is made well.
Drugs obtained by biotechnology processing
Hugo de Almeida; Maria Helena Amaral; Paulo Lobão
2011-01-01
In recent years, the number of drugs of biotechnological origin available for many different diseases has increased exponentially, including different types of cancer, diabetes mellitus, infectious diseases (e.g. AIDS Virus / HIV) as well as cardiovascular, neurological, respiratory, and autoimmune diseases, among others. The pharmaceutical industry has used different technologies to obtain new and promising active ingredients, as exemplified by the fermentation technique, recombinant DNA tec...
Truncated States Obtained by Iteration
Institute of Scientific and Technical Information of China (English)
W.B.Cardoso; N.G.de Almeida
2008-01-01
We introduce the concept of truncated states obtained via iterative processes(TSI)and study its statistical features,making an analogy with dynamical systems theory(DST).As a specific example,we have studied TSI for the doubring and the logistic functions,which are standard functions in studying chaos.TSI for both the doubling and logistic functions exhibit certain similar patterns when their statistical features are compared from the point of view of DST.
Restoration of density of states for FeAs-based superconductors
Kashurnikov, V. A.; Krasavin, A. V.; Zhumagulov, Ya V.
2016-09-01
The spectral and total electron density of states were calculated for two-dimensional FeAs-clusters modeling iron-based superconductors, with use of the generalized quantum Monte Carlo algorithm within the limits of the two-orbital model. The spectra have been obtained by means of the stochastic procedure, which was modified to restore the kernel of the integral equation relating the Matsubara Green's function and the spectral density. The calculations were made for clusters with sizes up to 10 × 10 FeAs-cells. The data on the total density of states near the Fermi level are obtained. There are two branches of the quasiparticle spectrum on both sides of the Fermi level. The effect of the values of the interaction parameter, the cluster size and temperature on the excitation spectra is discussed.
Impact of quantum entanglement on spectrum of cosmological fluctuations
Energy Technology Data Exchange (ETDEWEB)
Kanno, Sugumi, E-mail: sugumi.kanno@uct.ac.za [Laboratory for Quantum Gravity and Strings and Astrophysics, Cosmology and Gravity Center, Department of Mathematics and Applied Mathematics, University of Cape Town, Private Bag, Rondebosch 7701 (South Africa)
2014-07-01
We investigate the effect of entanglement between two causally separated open charts in de Sitter space on the spectrum of vacuum fluctuations. We consider a free massive scalar field, and construct the reduced density matrix by tracing out the vacuum state for one of the open charts, as recently derived by Maldacena and Pimentel. We formulate the mean-square vacuum fluctuations by using the reduced density matrix and show that the scale invariant spectrum of massless scalar field is realized on small scales. On the other hand, we find that the quantum entanglement affects the shape of the spectrum on large scales comparable to or greater than the curvature radius.
Impact of quantum entanglement on spectrum of cosmological fluctuations
Kanno, Sugumi
2014-01-01
We investigate the effect of entanglement between two causally separated open charts in de Sitter space on the spectrum of vacuum fluctuations. We consider a free massive scalar field, and construct the reduced density matrix by tracing out the vacuum state for one of the open charts, as recently derived by Maldacena and Pimentel. We formulate the mean-square vacuum fluctuations by using the reduced density matrix and show that the scale invariant spectrum of massless scalar field is realized on small scales. On the other hand, we find that the quantum entanglement affects the shape of the spectrum on large scales comparable to or greater than the curvature radius.
Spectrum of the Wilson Dirac operator at finite lattice spacings
DEFF Research Database (Denmark)
Akemann, G.; Damgaard, Poul Henrik; Splittorff, Kim;
2011-01-01
We consider the effect of discretization errors on the microscopic spectrum of the Wilson Dirac operator using both chiral Perturbation Theory and chiral Random Matrix Theory. A graded chiral Lagrangian is used to evaluate the microscopic spectral density of the Hermitian Wilson Dirac operator...... as well as the distribution of the chirality over the real eigenvalues of the Wilson Dirac operator. It is shown that a chiral Random Matrix Theory for the Wilson Dirac operator reproduces the leading zero-momentum terms of Wilson chiral Perturbation Theory. All results are obtained for fixed index...... of the Wilson Dirac operator. The low-energy constants of Wilson chiral Perturbation theory are shown to be constrained by the Hermiticity properties of the Wilson Dirac operator....
Polymerization contraction of resin composite vs. energy and power density of light-cure.
Asmussen, Erik; Peutzfeldt, Anne
2005-10-01
This study measured the polymerization contraction of a resin composite cured at three levels of energy density, each attained at six different levels of power density. The polymerization contraction of the composite was recorded by the method of the deflecting disc (n = 5) for 1 h following the start of irradiation. Power densities of 50, 100, 200, 400, 800 and 1,000 mW cm(-2), as measured on a dental radiometer, were obtained by variation of distance and supply voltage of a commercial light-curing unit. The spectral distribution at each power density was recorded using a spectrophotometer. The absorption spectrum of camphorquinone was also recorded, and the efficiency of the radiation at each power density was calculated as the integral over wavelength of the product of absorption and emission. From the slope of the contraction curves, an approximation to the initial rate of polymerization, Rp, was calculated and was taken as an alternative measure of power density. Statistical analyses showed that polymerization contraction increased significantly with increasing levels of energy density received by the resin composite, and, for each level of energy density, that the contraction decreased significantly with increasing power density.
Measurement of the $^{8}B$ neutrino spectrum
Winter, W; Jiang, C L; Ahmad, I; Freedman, S J; Greene, J; Heinz, A; Henderson, D; Janssens, R V F; Moore, E F; Mukherjee, G; Pardo, R C; Paul, M; Pennington, T; Savard, G; Schiffer, J P; Seweryniak, D; Zinkann, G P; 10.1016/S0375-9474(03)01122-9
2003-01-01
The neutrino spectrum from the decay of /sup 8/B is a crucial ingredient in interpreting recent data from solar neutrino detectors. The beta /sup +/ decay of /sup 8/B proceeds to a broad state in /sup 8/Be, and the shape of the neutrino spectrum may be obtained from a measurement of the alpha spectrum following the beta /sup +/ decay. A new technique has been used at the ATLAS accelerator to measure this spectrum by implanting /sup 8/B particles into the midplane of a 91 mu m thick Si detector. The advantage of this method is that both alpha particles are detected and systematic effects due to energy loss in catcher foils and dead layers of the detector are eliminated. To calibrate the detector, alpha 's from the decay of /sup 20/Na ions produced and implanted with the same technique were used. (5 refs).
Energy Technology Data Exchange (ETDEWEB)
Perez Alvarez, M. E.; Sena Espinel, E. de; Delgado Aparicio, J. M.; Martin Rincon, C.; Garcia Repiso, S.; Ramos Pacho, J. A.; Verde Velasco, J. M.; Gomez Gonzalez, N.; Cons Perez, N.; Saez Beltran, M.
2013-07-01
In order to discern with what calibration curve is obtained a more accurate dosimetry distribution, dose measurements are carried out on the treatment unit and the values found are evaluated. (Author)
Directory of Open Access Journals (Sweden)
Belgya Tamás
2017-01-01
Full Text Available The gamma-ray spectrum and the decay scheme of 114Cd obtained from a radiative neutron capture experiment on 113Cd samples are modelled in the framework of extreme statistical model. The unfolding of the experimental spectrum with proper normalization yields a total capture cross section of 21640 b and an average gamma-ray multiplicity of 4.1. Using the extreme statistical model the development of the low energy decay scheme of 114Cd is in progress. In the model the constant-temperature level density is used, where the temperature parameter was very sensitive to the shape of the modelled gamma-ray spectrum. Using this sensitivity T = 0.62 MeV was obtained with the constraint of good description of low energy level density and the level density at the binding energy. This is in full agreement with our earlier publication. For the description of the continuum shape of the unfolded spectrum the inclusion of low energy enhancement for the photon strength function was an important new addition.
DEFF Research Database (Denmark)
Reuman, Daniel C.; Gislason, Henrik; Barnes, Carolyn
2014-01-01
of taxonomy (all the species in a region regardless of clade) are much less studied but are equally important and will illuminate a different set of ecological and evolutionary processes. We develop and test a mechanistic model of how diversity varies with body mass in marine ecosystems. The model predicts...... the form of the diversity spectrum', which quantifies the distribution of species' asymptotic body masses, is a species analogue of the classic size spectrum of individuals, and which we have found to be a new and widely applicable description of diversity patterns. The marine diversity spectrum...... is predicted to be approximately linear across an asymptotic mass range spanning seven orders of magnitude. Slope -0 center dot 5 is predicted for the global marine diversity spectrum for all combined pelagic zones of continental shelf seas, and slopes for large regions are predicted to lie between -0 center...
Todd, Donald; Tsvetkov, Pavel
2012-01-01
Fast Spectrum Reactors presents a detailed overview of world-wide technology contributing to the development of fast spectrum reactors. With a unique focus on the capabilities of fast spectrum reactors to address nuclear waste transmutation issues, in addition to the well-known capabilities of breeding new fuel, this volume describes how fast spectrum reactors contribute to the wide application of nuclear power systems to serve the global nuclear renaissance while minimizing nuclear proliferation concerns. Readers will find an introduction to the sustainable development of nuclear energy and the role of fast reactors, in addition to an economic analysis of nuclear reactors. A section devoted to neutronics offers the current trends in nuclear design, such as performance parameters and the optimization of advanced power systems. The latest findings on fuel management, partitioning and transmutation include the physics, efficiency and strategies of transmutation, homogeneous and heterogeneous recycling, in addit...
Truncated states obtained by iteration
Cardoso, W B
2007-01-01
Quantum states of the electromagnetic field are of considerable importance, finding potential application in various areas of physics, as diverse as solid state physics, quantum communication and cosmology. In this paper we introduce the concept of truncated states obtained via iterative processes (TSI) and study its statistical features, making an analogy with dynamical systems theory (DST). As a specific example, we have studied TSI for the doubling and the logistic functions, which are standard functions in studying chaos. TSI for both the doubling and logistic functions exhibit certain similar patterns when their statistical features are compared from the point of view of DST. A general method to engineer TSI in the running-wave domain is employed, which includes the errors due to the nonidealities of detectors and photocounts.
Spectrum and network measurements
Witte, Robert A
2014-01-01
This new edition of Spectrum and Network Measurements enables readers to understand the basic theory, relate it to measured results, and apply it when creating new designs. This comprehensive treatment of frequency domain measurements successfully consolidates all the pertinent theory into one text. It covers the theory and practice of spectrum and network measurements in electronic systems. It also provides thorough coverage of Fourier analysis, transmission lines, intermodulation distortion, signal-to-noise ratio and S-parameters.
Observing broad-absorption line quasars with Spectrum-Rontgen-Gamma
DEFF Research Database (Denmark)
Singh, K.P.; Schnopper, H.W.; Westergaard, Niels Jørgen Stenfeldt
1998-01-01
Broad-absorption line quasars are found to have extremely weak soft X-ray emission when compared with other optically selected quasars. In the only example of PHL 5200 for which a detailed X-ray spectrum has been obtained with ASCA, strong absorption in the source appears to be responsible for th...... from the line of sight passing through large column density clouds. Simultaneous UV observations will help to constrain the ionization state of the absorbers, and also improve the overall UV to X-ray continuum measurements in them....
Energy Technology Data Exchange (ETDEWEB)
Kullie, Ossama [CNRS et Universite de Strasbourg, Institut de Chimie, Laboratoire de Chimie Quantique, 1 Rue Blaise Pascal, F- 67008 Strasbourg cedex (France)
2012-07-01
In this poster I present a (time-dependent) density functional study of the 20 low-lying excited states as well the ground states of the zinc dimer Zn{sub 2}. I analyze the spectrum of the dimer obtained form all electrons calculations which are performed using time-depended density functional with a relativistic 4-components-, and spin-free-Hamiltonian. I show results for different well-known density functional approximations, in comparing with literature and experimental values, the results are very encouraging, especially for the lowest excited states of these dimers. However, the results show that only the long-range corrected functionals such CAMB3LYP gives the correct asymptotic behavior for the higher states, for which the best result is obtained, and a comparable result is obtained from PBE0 functional.
Chen, Wei-kang; Fang, Hui
2016-03-01
The basic principle of polarization-differentiation elastic light scattering spectroscopy based techniques is that under the linear polarized light incidence, the singlely scattered light from the superficial biological tissue and diffusively scattered light from the deep tissue can be separated according to the difference of polarization characteristics. The novel point of the paper is to apply this method to the detection of particle suspension and, to realize the simultaneous measurement of its particle size and number density in its natural status. We design and build a coaxial cage optical system, and measure the backscatter signal at a specified angle from a polystyrene microsphere suspension. By controlling the polarization direction of incident light with a linear polarizer and adjusting the polarization direction of collected light with another linear polarizer, we obtain the parallel polarized elastic light scattering spectrum and cross polarized elastic light scattering spectrum. The difference between the two is the differential polarized elastic light scattering spectrum which include only the single scattering information of the particles. We thus compare this spectrum to the Mie scattering calculation and extract the particle size. We then also analyze the cross polarized elastic light scattering spectrum by applying the particle size already extracted. The analysis is based on the approximate expressions taking account of light diffusing, from which we are able to obtain the number density of the particle suspension. We compare our experimental outcomes with the manufacturer-provided values and further analyze the influence of the particle diameter standard deviation on the number density extraction, by which we finally verify the experimental method. The potential applications of the method include the on-line particle quality monitoring for particle manufacture as well as the fat and protein density detection of milk products.
Directory of Open Access Journals (Sweden)
Sang-Seon Byun
2014-01-01
Full Text Available This paper considers the problem of centralized spectrum allocations in wireless sensor networks towards the following goals: (1 maximizing fairness, (2 reflecting the priority among sensor data, and (3 avoiding unnecessary spectrum handoff. We cast this problem into a multiobjective mixed integer nonconvex nonlinear programming that is definitely difficult to solve at least globally without any aid of conversion or approximation. To tackle this intractability, we first convexify the original problem using arithmetic-geometric mean approximation and logarithmic change of the decision variables and then deploy weighted Chebyshev norm-based scalarization method in order to collapse the multiobjective problem into a single objective one. Finally, we apply simple rounding method in order to obtain approximate integer solutions. The results obtained from the numerical experiments show that, by adjusting the weight on each objective function, the proposed algorithm allocates spectrum bands fairly with well observing each sensor’s priority and reduced spectrum handoffs.
Density Estimations in Laboratory Debris Flow Experiments
Queiroz de Oliveira, Gustavo; Kulisch, Helmut; Malcherek, Andreas; Fischer, Jan-Thomas; Pudasaini, Shiva P.
2016-04-01
Bulk density and its variation is an important physical quantity to estimate the solid-liquid fractions in two-phase debris flows. Here we present mass and flow depth measurements for experiments performed in a large-scale laboratory set up. Once the mixture is released and it moves down the inclined channel, measurements allow us to determine the bulk density evolution throughout the debris flow. Flow depths are determined by ultrasonic pulse reflection, and the mass is measured with a total normal force sensor. The data were obtained at 50 Hz. The initial two phase material was composed of 350 kg debris with water content of 40%. A very fine pebble with mean particle diameter of 3 mm, particle density of 2760 kg/m³ and bulk density of 1400 kg/m³ in dry condition was chosen as the solid material. Measurements reveal that the debris bulk density remains high from the head to the middle of the debris body whereas it drops substantially at the tail. This indicates lower water content at the tail, compared to the head and the middle portion of the debris body. This means that the solid and fluid fractions are varying strongly in a non-linear manner along the flow path, and from the head to the tail of the debris mass. Importantly, this spatial-temporal density variation plays a crucial role in determining the impact forces associated with the dynamics of the flow. Our setup allows for investigating different two phase material compositions, including large fluid fractions, with high resolutions. The considered experimental set up may enable us to transfer the observed phenomena to natural large-scale events. Furthermore, the measurement data allows evaluating results of numerical two-phase mass flow simulations. These experiments are parts of the project avaflow.org that intends to develop a GIS-based open source computational tool to describe wide spectrum of rapid geophysical mass flows, including avalanches and real two-phase debris flows down complex natural
Decimated signal diagonalization for obtaining the complete eigenspectra of large matrices
Belkić, Dževad; Dando, Paul A.; Taylor, Howard S.; Main, Jörg
1999-12-01
An alternative method for obtaining high and interior eigenvalues of a dense spectrum is presented. The method takes advantage of the accurate, well-tested and fully understood algorithms for the fast Fourier transform to create, in a natural manner, a `window' containing only a small number of eigenvalues of the spectrum. The method is easy to implement, stable, efficient and accurate.
Optical phonons in Ge quantum dots obtained on Si(111)
Talochkin, A B
2002-01-01
The light combination scattering on the optical phonons in the Ge quantum dots, obtained on the Si surface of the (111) orientation through the molecular-beam epitaxy, is studied. The series of lines, connected with the phonon spectrum quantization, was observed. It is shown, that the phonon modes frequencies are well described by the elastic properties and dispersion of the voluminous Ge optical phonons. The value of the Ge quantum dots deformation is determined
Results obtained by investigating saffron ussing FT-IR spectroscopy
Directory of Open Access Journals (Sweden)
Luisa Andronie
2016-11-01
Full Text Available The biological activity and the pharmaceutical properties of plants are strongly dependent on their structure. The FT-IR spectra of saffron (commercial have been obtained. The vibrational fundamentals from the IR spectrum, were analyzed and assigned acoording to the available literature. In the present research work the genus saffron is selected because it is famous in wold as foods and also as medicine.
Frequency spectrum analysis for spectrum stabilization in airborne gamma-ray spectrometer.
Zeng, Guoqiang; Tan, Chengjun; Ge, Liangquan; Zhang, Qingxian; Gu, Yi
2014-02-01
Abnormal multi-crystal spectral drifts often can be observed when power on the airborne gamma-ray spectrometer. Currently, these spectral drifts of each crystal are generally eliminated through manual adjustment, which is time-consuming and labor-ineffective. To realize this quick automatic spectrum stabilization of multi-crystal, a frequency spectrum analysis method for natural gamma-ray background spectrum is put forward in this paper to replace traditional spectrum stabilization method used characteristic peak. Based on the polynomial fitting of high harmonics in frequency spectrum and gamma-ray spectral drift, it calculates overall spectral drift of natural gamma-ray spectrum and adjusts the gain of spectrometer by this spectral drift value, thus completing quick spectrum stabilization in the power on stage of spectrometer. This method requires no manual intervention and can obtain the overall spectral drift value automatically under no time-domain pre-processing to the natural gamma-ray spectra. The spectral drift value calculated by this method has an absolute error less than five channels (1024 resolution) and a relative error smaller than 0.80%, which can satisfy the quick automatic spectrum stabilization requirement when power on the airborne gamma-ray spectrometer instead of manual operation.
[Galaxy spectrum subtraction of a mixed spectrum based on two class PCA eigen-spectra].
Tu, Liang-Ping; Wu, Fu-Chao; Luo, A-Li; Zhao, Yong-Heng
2010-06-01
The authors present a new method called two class PCA for decomposing the mixed spectra, namely, for subtracting the host galaxy contamination from each SN spectrum. The authors improved the quality of reconstructed galaxy spectrum and computational efficiency, and these improvements were realized because we used both the PCA eigen spectra of galaxy templates library and SN templates library to model the mixed spectrum. The method includes mainly three steps described as follows. The first step is calculating two class PCA eigen spectra of galaxy templates and SN templates respectively. The second step is determining all reconstructed coefficients by the SVD matrix decomposition or orthogonal transformation. And the third step is computing a reconstructed galaxy spectrum and subtracting it from each mixed spectrum. Experiments show that this method can obtain an accurate decomposition of a mixed synthetic spectrum, and is a method with low time-consumption to get the reliable SN spectrum without galaxy contamination and can be used for spectral analysis of large amount of spectra. The time consumption using our method is much lower than that using chi2-template fitting for a spectrum.
Drugs obtained by biotechnology processing
Directory of Open Access Journals (Sweden)
Hugo Almeida
2011-06-01
Full Text Available In recent years, the number of drugs of biotechnological origin available for many different diseases has increased exponentially, including different types of cancer, diabetes mellitus, infectious diseases (e.g. AIDS Virus / HIV as well as cardiovascular, neurological, respiratory, and autoimmune diseases, among others. The pharmaceutical industry has used different technologies to obtain new and promising active ingredients, as exemplified by the fermentation technique, recombinant DNA technique and the hybridoma technique. The expiry of the patents of the first drugs of biotechnological origin and the consequent emergence of biosimilar products, have posed various questions to health authorities worldwide regarding the definition, framework, and requirements for authorization to market such products.Nos últimos anos, tem aumentado exponencialmente o número de fármacos de origem biotecnológica ao dispor das mais diversas patologias, entre elas destacam-se, os diferentes tipos de cancêr, as doenças infecciosas (ex. vírus AIDS/HIV, as doenças autoimunes, as doenças cardiovasculares, a Diabetes Mellitus, as doenças neurológicas, as doenças respiratórias, entre outras. A indústria farmacêutica tem recorrido a diferentes tecnologias para a obtenção de novos e promissores princípios ativos, como são exemplo a fermentação, a técnica de DNA Recombinante, a técnica de hidridoma, entre outras. A queda das patentes dos primeiros fármacos de origem biotecnológica e o consequente aparecimento dos produtos biossimilares têm colocado diferentes questões às autoridades de saúde mundiais, sobre a definição, enquadramento e exigências para a autorização de entrada no mercado deste tipo de produtos.
Power Spectrum of Generalized Fractional Gaussian Noise
Directory of Open Access Journals (Sweden)
Ming Li
2013-01-01
Full Text Available Recently, we introduced a type of autocorrelation function (ACF to describe a long-range dependent (LRD process indexed with two parameters, which takes standard fractional Gaussian noise (fGn for short as a special case. For simplicity, we call it the generalized fGn (GfGn. This short paper gives the power spectrum density function (PSD of GfGn.
Development of a Lithium Beam Probe and Measurement of Density Pedestal in JT-60U
Kojima, Atsushi; Kamiya, Kensaku; Fujita, Takaaki; Kubo, Hirotaka; Iguchi, Harukazu; Oyama, Naoyuki; Suzuki, Takahiro; Kamada, Yutaka; JT-60 Team
A lithium beam probe (LiBP) has been developed for the measurement of electron density profiles with highly spatial and temporal resolutions in JT-60U. Using an electron beam heating ion source with a capability of 10 mA extraction, a 5.5 mA beam has been injected to the plasmas. It corresponds to the equivalent neutral beam current of 2 mA. A spectrum width of the beam emission has been small enough to separate Zeeman splitting. By use of the LiBP, time evolutions of pedestal density profiles during type I and grassy edge localized modes (ELMs) have been obtained for the first time. After a type I ELM crash, the drop of the line-integrated density measured by an interferometer delays by 2 ms later than that of the pedestal density. Comparing the line-integrated density to the line integration of the edge density profile measured by the LiBP, it is found that the recovery from the type I ELM crash is correlated with the reduction of core plasma density. As for grassy ELMs, grassy ELMs have smaller density crashes than that of type I ELMs, which is mainly derived from the narrower ELM affected area.
Institute of Scientific and Technical Information of China (English)
吴波; 杨秀德; 张颂
2011-01-01
基于密度泛函理论计算了2个贵金属(Ag、Au、Cu)纳米团簇组成的团簇对的静电极化率和吸收光谱,结果表明这2个团簇之间存在强烈的静电耦合效应,其贡献主要来自于外加弱电场下团簇之间的电荷迁移和电子云的扭曲.随着团簇对间距的不断增大,静电极化率先增大后减小,存在一个极化率最大的最佳位置.在团簇对的吸收谱中,随着团簇对间距的增加,高能峰的位置和强度基本保持不变,而低能峰则不断蓝移且峰值先增大后减小,最终消失于高能峰的位置.进一步计算团簇-吡嗪和团簇-吡嗪-团簇体系的静电极化率和吸收光谱,结果发现团簇连接有机小分子后部分电子将从有机小分子向团簇迁移,使整个体系具有较大的固有极矩,在外加弱电场下,团簇与有机小分子之间的电荷迁移能力显著增强.%For a cluster-pair consisting of two same noble metal(Ag, Au, Cu) clusters, the static polarizability and absorption spectrum were calculated within density functional theory(DFT). The results show that between two cluster particles an intense static coupling effect exist, and under weak electric field which are mainly contributed by the charge transfer between two clusters and the distortion of electron cloud of individual cluster. Increasing interval distance of cluster-pair, the polarizability increases firstly then decreases, and an optimal position is characterized by the maximal polarizability. For the absorption spectrum of the cluster-pair, with the increase of interval distance the high-energy peak almost hold its absorption position unchanged, then the low-energy peak will step blue shift and the strength increases firstly then gradually decreases, lastly disappears at the high-energy position. For the static polarizability and absorption spectrum of the cluster-pyrazine or the cluster-pyrazine-cluster system, the farther calculations show that some electrons in small
Energy Technology Data Exchange (ETDEWEB)
Killian, E.W. [Idaho National Engineering Lab., Idaho Falls, ID (United States)
1997-11-01
A technique has been developed at the Idaho National Engineering Laboratory to sum high resolution gamma-ray pulse spectra from systems with multiple Ge detectors. Lockheed Martin Idaho Technologies Company operates a multi-detector spectrometer configuration at the Stored Waste Examination Pilot Plant facility which is used to characterize the radionuclide contents in waste drums destined for shipment to Waste Isolation Pilot Plant. This summing technique was developed to increase the sensitivity of the system, reduce the count times required to properly quantify the radio-nuclides and provide a more consistent methodology for combining data collected from multiple detectors. In spectrometer systems with multiple detectors looking at non homogeneous waste forms it is often difficult to combine individual spectrum analysis results from each detector to obtain a meaningful result for the total waste container. This is particularly true when the counting statistics in each individual spectrum are poor. The spectrum summing technique adds the spectra collected by each detector into a single spectrum which has better counting statistics than each individual spectrum. A normal spectral analysis program can then be used to analyze the sum spectrum to obtain radio-nuclide values which have smaller errors and do not have to be further manipulated to obtain results for the total waste container. 2 refs., 2 figs.
Institute of Scientific and Technical Information of China (English)
Wang Hanchao; Huang Lirong; Shi Zhongwei
2011-01-01
A two-electrode multi-quantum-well semiconductor optical amplifier is designed and fabricated. The amplified spontaneous emission (ASE) spectrum and gain were measured and analyzed. It is shown that the ASE spectrum and gain characteristic are greatly influenced by the distribution of the injection current density. By changing the injection current density of two electrodes, the full width at half maximum, peak wavelength, peak power of the ASE spectrum and the gain characteristic can be easily controlled.
Bandwidth Scale for Frequency Spectrum of Sea Waves
Institute of Scientific and Technical Information of China (English)
王伟; 孙孚; 钱成春; 邓拥军
2000-01-01
It is well known that energy spectrum bandwidth should be able to reflect the degree of energy concentration. However, the commonly used bandwidth factors defined by Longuet-Higgins could not fit the concept satisfactorily. A new kind of spectrum bandwidth scale factor with a clear physical meaning is given in the present paper and a constant is obtained which reveals the intrinsic characteristics of sea waves. Thereby a universal relationship between significant wave height of sea waves and spectrum bandwidth is established.
An optical spectrum of a large isolated gas-phase PAH cation: C78H26+
Zhen, Junfeng; Bonnamy, Anthony; Joblin, Christine
2015-01-01
A gas-phase optical spectrum of a large polycyclic aromatic hydrocarbon (PAH) cation - C78H26 +- in the 410-610 nm range is presented. This large all-benzenoid PAH should be large enough to be stable with respect to photodissociation in the harsh conditions prevailing in the interstellar medium (ISM). The spectrum is obtained via multi-photon dissociation (MPD) spectroscopy of cationic C78H26 stored in the Fourier Transform Ion Cyclotron Resonance (FT-ICR) cell using the radiation from a mid-band optical parametric oscillator (OPO) laser. The experimental spectrum shows two main absorption peaks at 431 nm and 516 nm, in good agreement with a theoretical spectrum computed via time-dependent density functional theory (TD-DFT). DFT calculations indicate that the equilibrium geometry, with the absolute minimum energy, is of lowered, nonplanar C2 symmetry instead of the more symmetric planar D2h symmetry that is usually the minimum for similar PAHs of smaller size. This kind of slightly broken symmetry could produ...
Liu, Fushun; Liu, Chengcheng; Chen, Jiefeng; Wang, Bin
2017-08-01
The key concept of spectrum response estimation with commercial software, such as the SESAM software tool, typically includes two main steps: finding a suitable loading spectrum and computing the response amplitude operators (RAOs) subjected to a frequency-specified wave component. In this paper, we propose a nontraditional spectrum response estimation method that uses a numerical representation of the retardation functions. Based on estimated added mass and damping matrices of the structure, we decompose and replace the convolution terms with a series of poles and corresponding residues in the Laplace domain. Then, we estimate the power density corresponding to each frequency component using the improved periodogram method. The advantage of this approach is that the frequency-dependent motion equations in the time domain can be transformed into the Laplace domain without requiring Laplace-domain expressions for the added mass and damping. To validate the proposed method, we use a numerical semi-submerged pontoon from the SESAM. The numerical results show that the responses of the proposed method match well with those obtained from the traditional method. Furthermore, the estimated spectrum also matches well, which indicates its potential application to deep-water floating structures.
Large-Scale Power Spectrum and Cosmological Parameters from SFI Peculiar Velocities
Freudling, W; Da Costa, L N; Dekel, A; Eldar, A; Giovanelli, R; Haynes, M P; Salzer, J J; Wegner, G; Zaroubi, S; Freudling, Wolfram; Zehavi, Idit; Costa, Luiz N. da; Dekel, Avishai; Eldar, Amiram; Giovanelli, Riccardo; Haynes, Martha P.; Salzer, John J.; Wegner, Gary; Zaroubi, Saleem
1999-01-01
We estimate the power spectrum of mass density fluctuations from peculiar velocities of galaxies by applying an improved maximum-likelihood technique to the new all-sky SFI catalog. Parametric models are used for the power spectrum and the errors, and the free parameters are determined by assuming Gaussian velocity fields and errors and maximizing the probability of the data given the model. It has been applied to generalized CDM models with and without COBE normalization. The method has been carefully tested using artificial SFI catalogs. The most likely distance errors are found to be similar to the original error estimates in the SFI data. The general result that is not very sensitive to the prior model used is a relatively high amplitude of the power spectrum. For example, at k=0.1 h/Mpc we find P(k)Ømega^{1.2}=(4.4+/-1.7)X10^3 (Mpc/h)^3. An integral over the power spectrum yields cosmological parameters are obtained for families of CDM models. For example, for COBE-normalized \\Lambda CDM models (scalar ...
Some Problems on the Global Wavelet Spectrum
Institute of Scientific and Technical Information of China (English)
WU Shu; LIU Qinyu
2005-01-01
In order to test the validity of the global wavelet spectrum - a new period analysis method based on wavelet analysis, we carried out some simple experiments. In our experiments we used idealized time series and real Ni(~n)o 3 sea surface temperature (SST) for testing purposes. First we combined different signals which have the same power but different periods into some new time series. Then we calculated the global wavelet spectra and Fourier power spectra for the testing time series. The testing results revealed that on some occasions the global wavelet spectrum tends to amplify the relative power of longer periods. By making comparisons with the results obtained by the traditional Fourier power spectrum, we demonstrated that on an occasion when the global wavelet spectrum does not work the Fourier power spectrum can be used to achieve the right results. Hence it is recommended that when making period analysis with the global wavelet spectrum one needs to do further tests to confirm their results.
Nonlinear density fluctuation field theory for large scale structure
Institute of Scientific and Technical Information of China (English)
Yang Zhang; Hai-Xing Miao
2009-01-01
We develop an effective field theory of density fluctuations for a Newtonian self-gravitating N-body system in quasi-equilibrium and apply it to a homogeneous uni-verse with small density fluctuations. Keeping the density fluctuations up to second or-der, we obtain the nonlinear field equation of 2-pt correlation ξ(r), which contains 3-pt correlation and formal ultra-violet divergences. By the Groth-Peebles hierarchical ansatz and mass renormalization, the equation becomes closed with two new terms beyond the Gaussian approximation, and their coefficients are taken as parameters. The analytic solu-tion is obtained in terms of the hypergeometric functions, which is checked numerically.With one single set of two fixed parameters, the correlation ξ(r) and the corresponding power spectrum P(k) simultaneously match the results from all the major surveys, such as APM, SDSS, 2dfGRS, and REFLEX. The model gives a unifying understanding of several seemingly unrelated features of large scale structure from a field-theoretical per-spective. The theory is worth extending to study the evolution effects in an expanding universe.
... Information › Bone Density Exam/Testing › Low Bone Density Low Bone Density Low bone density is when your ... compared to people with normal bone density. Detecting Low Bone Density A bone density test will determine ...
Characterization of rough interfaces obtained by boriding
Energy Technology Data Exchange (ETDEWEB)
Campos-Silva, I. [Instituto Politecnico Nacional, SEPI-ESIME, U.P. Adolfo Lopez Mateos, Zacatenco, Mexico D.F. 07738 (Mexico)], E-mail: icampos@ipn.mx; Balankin, A.S. [Instituto Politecnico Nacional, SEPI-ESIME, U.P. Adolfo Lopez Mateos, Zacatenco, Mexico D.F. 07738 (Mexico); Sierra, A.H. [Instituto Politecnico Nacional, UPIICSA, Av. Te 950, Col Granjas, Mexico D.F. 08400 (Mexico); Lopez-Perrusquia, N. [Instituto Politecnico Nacional, SEPI-ESIME, U.P. Adolfo Lopez Mateos, Zacatenco, Mexico D.F. 07738 (Mexico); Escobar-Galindo, R. [Instituto de Ciencia de Materiales de Madrid (CSIC), Cantoblanco, Madrid E-28049 (Spain); Morales-Matamoros, D. [Instituto Mexicano del Petroleo, Eje Lazaro Cardenas Norte, Mexico D.F. 07738 (Mexico)
2008-12-30
This study evaluates the morphology of borided interfaces by means of the fractal theory. The boride layers were formed in the AISI M2 steel by applying the paste boriding treatment at temperatures of 1253 and 1273 K and treatment times of 2 and 6 h, while a boron carbide paste thickness of 4 or 5 mm covered the samples surface in order to produce the boron diffusion. The morphology of interfaces formed between FeB and Fe{sub 2}B layers and between Fe{sub 2}B layer and steel substrate was analyzed by the rescaled-range (R/S), root-mean-square (RMS), and Fourier power spectrum (FPS) methods. Moreover, the multi-affine spectra of roughness exponent were obtained by calculating the q-order height-height correlation functions. We found that both interfaces are multi-affine, rather than self-affine. The multi-affine spectra of roughness exponents are found to be different for FeB/Fe{sub 2}B and Fe{sub 2}B/substrate interfaces, but independent on the treatment parameters (boron carbide paste thickness, temperature, and boriding time). Furthermore, we found that the multi-affine spectra of both interfaces behave as it is expected for 'universal multi-fractals' with the Levy index {gamma} = 1, associated with the multiplicative cascades with a log-Cauchy distribution. Furthermore, our data suggest a great homogeneity of the boron diffusion field, characterized by universal fractal dimension D{sub diff} = 2.90 {+-} 0.01. These findings provide a novel insight into the nature of phase formation during the boriding treatment.
Institute of Scientific and Technical Information of China (English)
Xie Dilin
2004-01-01
The infrared spectra of pure compounds of ninety thousands, poly compounds of twelve thousand, drugs of one thousand were included in the data bank. All of them can be searched out according to their serial number, chemical name, commercial name, amount of each atoms, or molecular formula, as well as their spectrum peak appearances. Program for spectrum information inputting, program for spectrum information search and program for spectrum peak appearance search were included in the system; in addition, spectrum information data bank, spectrum peak code data bank and spectrum figure data bank were attached to the system. System program was written by Visial Basic, and run under Windows system. The spectrum information data bank and spectrum figure data bank were administrated by Microsoft Access.The program for spectrum message inputting can be used to add message data and spectrum figure of some new compounds into the data banks by users themselves. The program for spectrum message search was designed to find out all the message data and spectrum figure of interested compound according to someone of the message data. The program for spectrum peak search was designed to find out some spectra most similar in peak shape with unknown spectrum by peak to peak comparison. When the wavenumbers and transmittances of main peaks in the spectrum of unknown sample were entered, the spectrum peak search was performed and several hits with higher similarity were reported including their similarity scores, spectrum serial numbers, sample's states,melt points, molecular formulas as well as spectrum images. If the search result was not satisfactory,some methods to modify spectrum parameters were reminded and search was performed again.
BB mode angular power spectrum of CMB from massive gravity
Malsawmtluangi, N
2016-01-01
The primordial massive gravitational waves are placed in the squeezed vacuum state and corresponding $BB$-mode correlation angular power spectrum of the cosmic microwave background is obtained for various slow roll inflation models. The angular power spectrum is compared with the limit of BICEP2/Keck and Planck joint analysis data and the hybrid inflation model is found favorable.
Triplet State Resonance Raman Spectrum of all-trans-diphenylbutadiene
DEFF Research Database (Denmark)
Wilbrandt, Robert Walter; Grossman, W.E.L.; Killough, P.M
1984-01-01
The resonance Raman spectrum of all-trans-diphenylbutadiene (DPB) in its ground state and the resonance Raman spectrum (RRS) of DPB in its short-lived electronically excited triplet state are reported. Transient spectra were obtained by a pump-probe technique using two pulsed lasers...
Rodwell, Peter
1982-01-01
Describes and evaluates the hardware, software, peripheral devices, performance capabilities, and programing capacity of the Sinclair ZX Spectrum microcomputer. The computer's display system, its version of the BASIC programing language, its graphics capabilities, and the unique features of its data entry keyboard are discussed. (JL)
Autism Spectrum Disorder (ASD)
... with: 1 Communication and interaction with other people Restricted interests and repetitive behaviors Different people with autism can have different symptoms. For this reason, autism is known as a spectrum disorder —which means that there is a range of ...
Centers for Disease Control (CDC) Podcasts
2014-04-02
This podcast discusses autism spectrum disorder (ASD), a developmental disability that causes problems with social, communication, and behavioral skills. CDC estimates that one in 68 children has been identified as having ASD. Created: 4/2/2014 by National Center on Birth Defects and Developmental Disabilities (NCBDDD). Date Released: 4/2/2014.
Bolton, Adam S; Brownstein, Joel; Pandey, Parul; Schlegel, David; Shu, Yiping
2011-01-01
This contribution describes the "spectro-perfectionism" algorithm of Bolton & Schlegel (2010, PASP, 122, 248) that is being implemented within the Baryon Oscillation Spectroscopic Survey (BOSS) of the Sloan Digital Sky Survey III (SDSS-III), in terms of its potential to deliver Poisson-limited sky subtraction and lossless compression of the input spectrum likelihood functional given raw CCD data.
Battlefield spectrum management
Sivakumar, C.
1997-06-01
Modern tactical communications systems rely on radios to support network and user connectivity. One of the challenges for network planners and managers is to make best use of scarce and vulnerable frequency spectrum resources to support the communication needs of war fighters. With the wide variety of Iris radio types typically to be deployed in the battlefield (ranging from high frequency to super high frequency), a comprehensive suite of tools is necessary to ensure that frequency interference is kept minimum. Without a sophisticated frequency spectrum management system, the most advanced tactical communications systems could be rendered useless, jeopardizing human life and national security. For these reasons, it is important to develop an Iris wide battlefield spectrum management capability that takes full advantage of current frequency spectrum management research and development (R&D), related tools, and supporting technology for assigning frequencies. This session briefly describes various assignment strategies being adopted in the Iris BFSM for overcoming cosite/collocated/farsite interferences along with the propagation models [from high frequency (HF) to super high frequency (SHF)] used for the assignment of frequencies. Also a brief thread outlining the process for generating frequency allocation/assignment request and analysis of frequency interference is discussed.
Isomer Spectrum of Small Carbon Clusters
Institute of Scientific and Technical Information of China (English)
SHENG Yang; LI Peng; NING Xi-Jing
2004-01-01
A theoretical method is developed to find isomers of cluster particles, and the isomer spectrum of carbon clusters Cn (n = 3-44) is obtained. It is found that the isomers of 3-11 atoms are in either mono-ring or line shapes,while the isomers of 12-18 atoms show flat sheet shapes. As cluster size increases, bowl isomers become more (n ＞ 19) until cage isomers dominate the structures (n ＞ 27). Based on the isomer spectrum, results of a previous experiment are interpreted.
More about the light baryon spectrum
Eichmann, Gernot
2016-01-01
We discuss the light baryon spectrum obtained from a recent quark-diquark calculation, implementing non-pointlike diquarks that are self-consistently calculated from their Bethe-Salpeter equations. We examine the orbital angular momentum content in the baryons' rest frame and highlight the fact that baryons carry all possible values of L compatible with their spin, without the restriction P=(-1)^L which is only valid nonrelativistically. We furthermore investigate the meaning of complex conjugate eigenvalues of Bethe-Salpeter equations, their possible connection with 'anomalous' states, and we propose a method to eliminate them from the spectrum.
More About the Light Baryon Spectrum
Eichmann, Gernot
2017-03-01
We discuss the light baryon spectrum obtained from a recent quark-diquark calculation, implementing non-pointlike diquarks that are self-consistently calculated from their Bethe-Salpeter equations. We examine the orbital angular momentum content in the baryons' rest frame and highlight the fact that baryons carry all possible values of L compatible with their spin, without the restriction P=(-1)^L which is only valid nonrelativistically. We furthermore investigate the meaning of complex conjugate eigenvalues of Bethe-Salpeter equations, their possible connection with `anomalous' states, and we propose a method to eliminate them from the spectrum.
Time-variant power spectrum analysis for the detection of transient episodes in HRV signal.
Bianchi, A M; Mainardi, L; Petrucci, E; Signorini, M G; Mainardi, M; Cerutti, S
1993-02-01
A time-variant algorithm of autoregressive (AR) identification is introduced and applied to the heart rate variability (HRV) signal. The power spectrum is calculated from the AR coefficients derived from each single RR interval considered. Time-variant AR coefficients are determined through adaptive parametric identification with a forgetting factor which obtains weighed values on a running temporal window of 50 preceding measurements. Power spectrum density (PSD) is hence obtained at each cardiac cycle, making it possible to follow the dynamics of the spectral parameters on a beat-by-beat basis. These parameters are mainly the LF (low frequency) and the HF (high frequency) powers, and their ratio LF/HF. These together account for the balanced sympatho-vagal control mechanism affecting the heart rate. This method is applied to subjects suffering from transient ischemic attacks. The time variant spectral parameters suggest an early activation of LF component in the HRV power spectrum. It precedes by approximately 1.5-2 min the tachycardia and the ST displacement, generally indicative of the onset of an ischemic episode. The results suggest an arousal of sympathetic system before the acute attack.
Electron density of states of Fe-based superconductors: Quantum trajectory Monte Carlo method
Kashurnikov, V. A.; Krasavin, A. V.; Zhumagulov, Ya. V.
2016-03-01
The spectral and total electron densities of states in two-dimensional FeAs clusters, which simulate iron-based superconductors, have been calculated using the generalized quantum Monte Carlo algorithm within the full two-orbital model. Spectra have been reconstructed by solving the integral equation relating the Matsubara Green's function and spectral density by the method combining the gradient descent and Monte Carlo algorithms. The calculations have been performed for clusters with dimensions up to 10 × 10 FeAs cells. The profiles of the Fermi surface for the entire Brillouin zone have been presented in the quasiparticle approximation. Data for the total density of states near the Fermi level have been obtained. The effect of the interaction parameter, size of the cluster, and temperature on the spectrum of excitations has been studied.
Aloisio, R; Di Carlo, G; Galante, A; Grillo, A F
2000-01-01
Lattice formulation of Finite Baryon Density QCD is problematic from computer simulation point of view; it is well known that for light quark masses the reconstructed partition function fails to be positive in a wide region of parameter space. For large bare quark masses, instead, it is possible to obtain more sensible results; problems are still present but restricted to a small region. We present evidence for a saturation transition independent from the gauge coupling $\\beta$ and for a transition line that, starting from the temperature critical point at $\\mu=0$, moves towards smaller $\\beta$ with increasing $\\mu$ as expected from simplified phenomenological arguments.
Density vs distance for the DUNE beam from two recent geology density maps
Roe, Byron P
2016-01-01
The densities passed through for neutrinos going from Fermilab to Sanford lab are obtained using two recent density tables, crustal [1] and Shen-Ritzwoller[2], as well as the values from an older table PEMC[3].
A survey of the millimeter-wave spectrum of Sagittarius B2
Cummins, S. E.; Thaddeus, P.; Linke, R. A.
1986-01-01
More than 60 percent of the millimeter wave spectrum between 70 and 150 GHz of the giant Sgr B2 molecular cloud was surveyed with the Bell Laboratories 7 m telescope at a spectral resolution of 1 MHz. The observations and instrumentation are described, including beam efficiency and beamwidth as functions of frequency, frequency coverage, and rms noise. The catalog used to identify the 457 lines found is summarized, and the analysis of the data to determine column densities and rotational temperatures is discussed. The range of rotational temperatures obtained and their relation to the kinetic temperature, and their implications for the hydrogen density, are considered. More than 300 lines are transitions of 21 molecules, and the results for these are analyzed, giving excitation diagrams for most of them. A partly successful attempt is made to use ratios of the calculated abundances to predict abundances of as yet undetected species. Finally, the spectra for the entire survey are presented.
Generalized Thermostatistics and Wavelet Analysis of the Solar Wind and Proton Density Variability
Bolzan, M J A; Ramos, F M; Fagundes, P R; Sahai, Y; Bolzan, Mauricio J. A.; Rosa, Reinaldo R.; Ramos, Fernando M.; Fagundes, Paulo R.; Sahai, Yogeshwar
2005-01-01
In this paper, we analyze the probability density function (PDF) of solar wind velocity and proton density, based on generalized thermostatistics (GT) approach, comparing theoretical results with observational data. The time series analyzed were obtained from the SOHO satellite mission where measurements were sampled every hour. We present in the investigations data for two years of different solar activity: (a) moderate activity (MA) period (1997) and (b) high activity (HA) period (2000). For the MA period, the results show good agreement between experimental data and GT model. For the HA period, the agreement between experimental and theoretical PDFs was fairly good, but some distortions were observed, probably due to intermittent characteristics of turbulent processes. As a complementary analysis, the Global Wavelet Spectrum (GWS) was obtained allowing the characterization of the predominant temporal variability scales for both the periods and the stochastics aspects of the nonlinear solar wind variability...
BLOCK H-MATRICES AND SPECTRUM OF BLOCK MATRICES
Institute of Scientific and Technical Information of China (English)
黄廷祝; 黎稳
2002-01-01
The block H-matrices are studied by the concept of G-functions, several concepts of block matrices are introduced. Equivalent characters of block H-matrices are obtained. Spectrum localizations claracterized by Gfunctions for block matrices are got.
Josephson junction spectrum analyzer for millimeter and submillimeter wavelengths
Energy Technology Data Exchange (ETDEWEB)
Larkin, S.Y.; Anischenko, S.E.; Khabayev, P.V. [State Research Center, Kiev (Ukraine)
1994-12-31
A prototype of the Josephson-effect spectrum analyzer developed for the millimeter-wave band is described. The measurement results for spectra obtained in the frequency band from 50 to 250 GHz are presented.
Srivastava, Mayuri; Rani, P; Singh, N P; Yadav, R A
2014-01-01
Vibrational spectrum of pyridoxine has been investigated using experimental IR and Raman spectroscopic and density functional theory (DFT) methods. Vibrational assignments of the observed IR and Raman bands have been proposed in light of the results obtained from computations. In order to assign the observed IR and Raman frequencies the potential energy distributions (PEDs) have also been computed. Optimized geometrical parameters suggest that if the OH groups of the two methyl groups are replaced by H atoms the resulting molecule has Cs point group symmetry. To investigate molecular stability and bond strength we have used natural bond orbital analysis (NBO). Charge transfer occurs in the molecule have been shown by the calculated highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) energies. The mapping of electron density iso-surface with electrostatic potential (ESP), has been carried out to get the information about the size, shape, charge density distribution and site of chemical reactivity of the molecule.
The QCD spectrum with three quark flavors
Bernard, C; DeGrand, T A; Datta, S; DeTar, C E; Gottlieb, S; Heller, U M; Orginos, K; Sugar, R; Toussaint, D; Bernard, Claude; Burch, Tom; Grand, Thomas A. De; Datta, Saumen; Tar, Carleton De; Gottlieb, Steven; Heller, Urs M.; Orginos, Kostas; Sugar, Robert; Toussaint, Doug
2001-01-01
We present results from a lattice hadron spectrum calculation using three flavors of dynamical quarks - two light and one strange, and quenched simulations for comparison. These simulations were done using a one-loop Symanzik improved gauge action and an improved Kogut-Susskind quark action. The lattice spacings, and hence also the physical volumes, were tuned to be the same in all the runs to better expose differences due to flavor number. Lattice spacings were tuned using the static quark potential, so as a byproduct we obtain updated results for the effect of sea quarks on the static quark potential. We find indications that the full QCD meson spectrum is in better agreement with experiment than the quenched spectrum. For the 0++ (a0) meson we see a coupling to two pseudoscalar mesons, or a meson decay on the lattice.
Premorbid neurocognitive functioning in schizophrenia spectrum disorder
DEFF Research Database (Denmark)
Sørensen, Holger Jelling; Mortensen, E.L.; Parnas, Josef
2006-01-01
was 0.97 (95% CI 0.94-1.00) (p = .022), and the risk of schizophrenia spectrum disorder decreased by 3% (95% CI 6 to 0%). The Coding deficit on the WISC may indicate deficits in perceptual motor speed or in working memory processing speed in young individuals who later develop schizophrenia, schizotypal...... in adolescence, the aim of the present prospective study was to examine whether low scores on Coding is associated with the risk of developing schizophrenia spectrum disorders. The 12 subtests of the WISC were administered to 311 children and adolescents with a mean age of 15.1 years (range: 8 to 20 years......), and the diagnostic assessment (DSM-IIIR) was conducted by senior clinicians 25 years later. The group with schizophrenia spectrum disorder consisted of 84 individuals, and this group obtained significantly lower scores on Coding than nonschizophrenic controls. This difference could not be explained by differences...
Power spectrum analysis for optical tweezers
DEFF Research Database (Denmark)
Berg-Sørensen, K.; Flyvbjerg, H.
2004-01-01
the Lorentzian provides. This is achieved using old and new theory for Brownian motion in an incompressible fluid, and new results for a popular photodetection system. The trap and photodetection system are then calibrated simultaneously in a manner that makes optical tweezers a tool of precision for force......The force exerted by an optical trap on a dielectric bead in a fluid is often found by fitting a Lorentzian to the power spectrum of Brownian motion of the bead in the trap. We present explicit functions of the experimental power spectrum that give the values of the parameters fitted, including...... obtain perfect fits and calibrate tweezers with less than 1% error when the trapping force is not too strong. Relatively strong traps have power spectra that cannot be fitted properly with any Lorentzian, we find. This underscores the need for better understanding of the power spectrum than...
Neutron spectrum unfolding using radial basis function neural networks.
Alvar, Amin Asgharzadeh; Deevband, Mohammad Reza; Ashtiyani, Meghdad
2017-07-26
Neutron energy spectrum unfolding has been the subject of research for several years. The Bayesian theory, Monte Carlo simulation, and iterative methods are some of the methods that have been used for neutron spectrum unfolding. In this study, the radial basis function (RBF), multilayer perceptron, and artificial neural networks (ANNs) were used for the unfolding of neutron spectrum, and a comparison was made between the networks' results. Both neural network architectures were trained and tested using the same data set for neutron spectrum unfolding from the response of LiI detectors with Eu impurity. Advantages of each ANN method in the unfolding of neutron energy spectrum were investigated, and the performance of the networks was compared. The results obtained showed that RBF neural network can be applied as an effective method for unfolding neutron spectrum, especially when the main target is the neutron dosimetry. Copyright © 2017 Elsevier Ltd. All rights reserved.
Perturbation Theory of the Cosmological Log-Density Field
Wang, Xin; Szapudi, István; Szalay, Alex; Chen, Xuelei; Lesgourgues, Julien; Riotto, Antonio; Sloth, Martin; 10.1088/0004-637X/735/1/32
2011-01-01
The matter density field exhibits a nearly lognormal probability density distribution (PDF) after entering into the nonlinear regime. Recently, it has been shown that the shape of the power spectrum of a logarithmically transformed density field is very close to the linear density power spectrum, motivating an analytic study of it. In this paper, we develop cosmological perturbation theory for the power spectrum of this field. Our formalism is developed in the context of renormalized perturbation theory, which helps to regulate the convergence behavior of the perturbation series, and of the Taylor- series expansion we use of the logarithmic mapping. This approach allows us to handle the critical issue of density smoothing in a straightforward way. We also compare our perturbative results with simulation measurements.
Density convection near radiating ICRF antennas and its effect on the coupling of lower hybrid waves
Energy Technology Data Exchange (ETDEWEB)
Ekedahl, A.; Colas, L.; Beaumont, B.; Bibet, Ph.; Bremond, S.; Kazarian, F. [Association Euratom-CEA Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee; Mayoral, M.L.; Mailloux, J. [Euratom/UKAEA Fusion Association, Culham Science Centre, Abingdon, OX (United Kingdom); Noterdaeme, J.M. [Max-Planck-Institut fuer Plasmaphysik, Euratom Association, Garching (Germany)]|[Gent University, EESA Dept. (Belgium); Tuccillo, A.A. [Associazione Euratom-ENEA sulla Fusione, CR Frascati, Rome (Italy)
2003-07-01
Combined operation of lower hybrid (LH) and Ion Cyclotron Resonance Frequency (ICRF) waves can result in a degradation of the LH wave coupling, as observed both in the Tore-Supra and Jet tokamaks. The reflection coefficient on the part of the LH launcher magnetically connected to the powered ICRF antenna increases, suggesting a local decrease in the electron density in the connecting flux tubes. This has been confirmed by Langmuir probe measurements on the LH launchers in the latest Tore-Supra experiments. Moreover, recent experiments in Jet indicate that the LH coupling degradation depends on the ICRF power and its launched k{sub /} spectrum. The 2D density distribution around the Tore-Supra ICRF antennas has been modelled with the CELLS-code, balancing parallel losses with diffusive transport and sheath induced ExB convection, obtained from RF field mapping using the ICANT-code. The calculations are in qualitative agreement with the experimental observations, i.e. density depletion is obtained, localised mainly in the antenna shadow, and dependent on ICRF power and antenna spectrum. (authors)
Spread spectrum image steganography.
Marvel, L M; Boncelet, C R; Retter, C T
1999-01-01
In this paper, we present a new method of digital steganography, entitled spread spectrum image steganography (SSIS). Steganography, which means "covered writing" in Greek, is the science of communicating in a hidden manner. Following a discussion of steganographic communication theory and review of existing techniques, the new method, SSIS, is introduced. This system hides and recovers a message of substantial length within digital imagery while maintaining the original image size and dynamic range. The hidden message can be recovered using appropriate keys without any knowledge of the original image. Image restoration, error-control coding, and techniques similar to spread spectrum are described, and the performance of the system is illustrated. A message embedded by this method can be in the form of text, imagery, or any other digital signal. Applications for such a data-hiding scheme include in-band captioning, covert communication, image tamperproofing, authentication, embedded control, and revision tracking.
Abdallah, Wael A.
2012-11-05
Asphaltenes extracted from seven different crude oils representing different geological formations from around the globe were analyzed using the Raman spectroscopic technique. Each spectrum is fitted with four main peaks using the Gaussian function. On the basis of D1 and G bands of the Raman spectrum, asphaltene indicated an ordered structure with the presence of boundary defected edges. The average aromatic sheet size of the asphaltene molecules is estimated within the range of 1.52-1.88 nm, which represents approximately seven to eight aromatic fused rings. This estimation is based on the integrated intensity of D1 and G bands, as proposed by Tunistra and Koenig. The results here are in perfect agreement with so many other used techniques and indicate the potential applicability of Raman measurements to determine the average aromatic ring size and its boundary. © 2012 American Chemical Society.
The Supersymmetric Particle Spectrum
Barger, V; Ohmann, P
1994-01-01
We examine the spectrum of supersymmetric particles predicted by grand unified theoretical (GUT) models where the electroweak symmetry breaking is accomplished radiatively. We evolve the soft supersymmetry breaking parameters according to the renormalization group equations (RGE). The minimization of the Higgs potential is conveniently described by means of tadpole diagrams. We present complete one-loop expressions for these minimization conditions, including contributions from the matter and the gauge sectors. We concentrate on the low $\\tan \\beta$ fixed point region (that provides a natural explanation of a large top quark mass) for which we find solutions to the RGE satisfying both experimental bounds and fine-tuning criteria. We also find that the constraint from the consideration of the lightest supersymmetric particle as the dark matter of the universe is accommodated in much of parameter space where the lightest neutralino is predominantly gaugino. The supersymmetric mass spectrum displays correlations...
Raman spectrum of natural and synthetic stishovite
Hemley, R.J.; Mao, Ho-kwang; Chao, E.C.T.
1986-01-01
Raman spectra of natural and synthetic samples of stishovite have been measured with a micro-optical spectrometer system. These spectra have a pattern that is characteristic of rutile-structured oxides. The spectrum of synthetic stishovite is characterized by well-resolved bands at 231, 589, 753, and 967 cm-1, which are assigned as the B1g, Eg, A1g, and B2g fundamentals, respectively, of the first-order Raman spectrum of the ideal, ordered structure. Natural stishovite obtained from Meteor Crater, Arizona has a first-order Raman spectrum that is fully consistent with that of the synthetic material. The observed spectrum of the natural sample, however, is weaker and has bands in addition to those identified as fundamentals in the spectrum of the synthetic material. A broad band at ???475 cm-1 may be indicative of glass or contaminants derived from the extraction procedure. Alternatively, this band may arise from multiphonon scattering that is enhanced by poor crystallinity or structural disorder in the natural shocked sample. ?? 1986 Springer-Verlag.
[Clinical spectrum of neuroborreliosis].
Owecki, Michał K; Kozubski, Wojciech
2007-01-01
Lyme disease is a multisystem infectious disease with a wide variety of symptoms involving the skin as well as nervous, musculosceletal and cardiovascular systems. Lyme disease is caused by spirochaete Borrelia burgdorferi transmitted by Ixodes tics in endemic regions. The diverse manifestations of neuroborreliosis require it to be included in differential diagnosis of many neurological disorders. The paper reviews the spectrum of clinical symptoms of nervous system involvement in early and late Lyme disease.
AUTISM SPECTRUM DISORDERS (ASD)
Middha Akanksha; Kataria Sahil; Sandhu Premjeet; Kapoor Bhawna
2011-01-01
Autism or Autism Spectrum Disorders (ASD) is a serious neurological disorder affecting communication skills, social interactions, adaptability in an individual, and also causes dramatic changes in behavioral patterns. This condition typically lasts throughout one’s lifetime and affects both, children as well as adults. Research has shown a tenfold increase in autism cases over the past decade and still rising at an alarming pace. The origins of autism are not known even to modern science. Aut...
Directory of Open Access Journals (Sweden)
Y. Narita
2011-02-01
Full Text Available A new analysis method is presented that provides a high-resolution power spectrum in a broad wave number domain based on multi-point measurements. The analysis technique is referred to as the Multi-point Signal Resonator (MSR and it benefits from Capon's minimum variance method for obtaining the proper power spectral density of the signal as well as the MUSIC algorithm (Multiple Signal Classification for considerably reducing the noise part in the spectrum. The mathematical foundation of the analysis method is presented and it is applied to synthetic data as well as Cluster observations of the interplanetary magnetic field. Using the MSR technique for Cluster data we find a wave in the solar wind propagating parallel to the mean magnetic field with relatively small amplitude, which is not identified by the Capon spectrum. The Cluster data analysis shows the potential of the MSR technique for studying waves and turbulence using multi-point measurements.
Observation of Phillips' spectrum in Faraday waves
Castillo, Gustavo
2016-01-01
We report the observation of the Phillips' spectrum of gravity surface waves driven by a horizontally moving wave maker interacting with Faraday waves. We measure the temporal fluctuations of the surface wave amplitude at a given location and we show that, for a wide range of forcing parameters, they display a power-law spectrum that greatly differs from the one predicted by the WT theory but coincides with Phillips' spectrum for gravity waves. We compute the probability density function of the local surface height increments, which show that they change strongly across time scales. The structure functions of these increments are shown to display power-laws as a function of the time lag, with exponents that are not linear with the order of the structure function, thus showing that the wave field is intermittent. We argue that the origin of this scale-invariant intermittent spectrum is the Faraday wave pattern breakup due to its advection by the propagating gravity waves, which can be related directly to the P...
The bias of galaxies and the density of the universe from the 2dF galaxy redshift survey
Verde, Licia; Heavens, Alan F.; Percival, Will J.; Matarrese, Sabino
2002-01-01
By studying the bispectrum of the galaxy distribution in the 2dF galaxy redhsift survey (2dFGRS), we have shown that 2dFGRS galaxies are unbiased tracers of the mass distribution. This allows us the break the degeneracy intrinsic to power spectrum studies, between the matter density parameter Omega_m and the bias parameter b, and to obtain an accurate measurement of Omega_m: Omega_{m,z_{eff}}=0.27 \\pm 0.06, a measurement obtained from the 2dFGRS alone, independently from other data sets. This...
Overview of galactic results obtained by MAGIC
Energy Technology Data Exchange (ETDEWEB)
Zanin, Roberta
2013-06-15
MAGIC is a system of two atmospheric Cherenkov telescopes which explores the very-high-energy sky, from some tens of GeV up to tens of TeV. Located in the Canary island of La Palma, MAGIC has the lowest energy threshold among the instruments of its kind, well suited to study the still poorly explored energy band below 100 GeV. Although the space-borne gamma-ray telescope Fermi/LAT is sensitive up to 300 GeV, gamma-ray rates drop fast with increasing energy, so γ-ray collection areas larger than 10{sup 4}m{sup 2}, as those provided by grounds-based instruments, are crucial above a few GeV. The combination of MAGIC and Fermi/LAT observations have provided the first astrophysical spectra sampled in the inverse Compton peak region, resulting in a complete coverage from MeV up to TeV energies, as well as the discovery of a pulsed emission in the very-high-energy band. This paper focuses on the latest results on Galactic sources obtained by MAGIC which are highlighted by the detection of the pulsed gamma-ray emission from the Crab pulsar up to 400 GeV. In addition, we will present the morphological study on the W51 complex which allowed to pinpoint the location of the majority of the emission around the interaction point between the supernova remnant W51C and the star forming region W51B, but also to find a possible contribution from the associated pulsar wind nebula. Other important scientific achievements involve the Crab Nebula with an unprecedented spectrum covering three decades in energy starting from 50 GeV and a morphological study of the unidentified source HESS J1857+026 which supports the pulsar wind nebula scenario. Finally we will report on the searches of very-high-energy signals from gamma-ray binaries, mainly LS I 303+ and HESS J0632+057.
Density Dependence of Nuclear Symmetry Energy
Behera, B; Tripathy, S K
2016-01-01
High density behaviour of nuclear symmetry energy is studied on the basis of a stiffest density dependence of asymmetric contribution to energy per nucleon in charge neutral $n+p+e+\\mu$ matter under beta equilibrium. The density dependence of nuclear symmetry energy obtained in this way is neither very stiff nor soft at high densities and is found to be in conformity with recent observations of neutron stars
Density dependence of nuclear symmetry energy
Behera, B.; Routray, T. R.; Tripathy, S. K.
2016-10-01
High density behavior of nuclear symmetry energy is studied on the basis of the stiffest density dependence of asymmetric contribution to energy per nucleon in charge neutral n + p + e + μ matter under beta equilibrium. The density dependence of nuclear symmetry energy obtained in this way is neither very stiff nor soft at high densities and is found to be in conformity with recent observations of neutron stars.
Airborne Crowd Density Estimation
Meynberg, O.; Kuschk, G.
2013-10-01
This paper proposes a new method for estimating human crowd densities from aerial imagery. Applications benefiting from an accurate crowd monitoring system are mainly found in the security sector. Normally crowd density estimation is done through in-situ camera systems mounted on high locations although this is not appropriate in case of very large crowds with thousands of people. Using airborne camera systems in these scenarios is a new research topic. Our method uses a preliminary filtering of the whole image space by suitable and fast interest point detection resulting in a number of image regions, possibly containing human crowds. Validation of these candidates is done by transforming the corresponding image patches into a low-dimensional and discriminative feature space and classifying the results using a support vector machine (SVM). The feature space is spanned by texture features computed by applying a Gabor filter bank with varying scale and orientation to the image patches. For evaluation, we use 5 different image datasets acquired by the 3K+ aerial camera system of the German Aerospace Center during real mass events like concerts or football games. To evaluate the robustness and generality of our method, these datasets are taken from different flight heights between 800 m and 1500 m above ground (keeping a fixed focal length) and varying daylight and shadow conditions. The results of our crowd density estimation are evaluated against a reference data set obtained by manually labeling tens of thousands individual persons in the corresponding datasets and show that our method is able to estimate human crowd densities in challenging realistic scenarios.
THz spectrum of reduced glutathione
Institute of Scientific and Technical Information of China (English)
WANG; Weining; YAN; Haitao; YUE; Weiwei; ZHAO; Guozhong; Z
2005-01-01
The optical characteristics of reduced glutathione molecules between 0.2 THz and 2.4 THz have been investigated by THz time-domain spectroscopy (THz-TDS). The absorption characteristics and optical parameters of the reduced glutathione purged with Nitrogen at room temperature were obtained experimentally. The measured results were fitted well with the theoretical results computed by using Density Functional Theory (DFT) in far-infrared range. Also the conformation of the reduced glutathione molecule was simulated by Gaussian 03. This work has demonstrated significantly that THz-TDS spectroscopy can further be used to study other biological molecules in biological and biomedical engineering.
New theory of superconductivity. Method of equilibrium density matrix
Bondarev, Boris
2014-01-01
A new variational method for studying the equilibrium states of an interacting particles system has been proposed. The statistical description of the system is realized by means of a density matrix. This method is used for description of conduction electrons in metals. An integral equation for the electron distribution function over wave vectors has been obtained. The solutions of this equation have been found for those cases where the single-particle Hamiltonian and the electron interaction Hamiltonian can be approximated by a quite simple expression. It is shown that the distribution function at temperatures below the critical value possesses previously unknown features which allow to explain the superconductivity of metals and presence of a gap in the energy spectrum of superconducting electrons.
Density Functional Theory Study of Infrared and Ultraviolet Spectra of Urea L-Malic Acid
Institute of Scientific and Technical Information of China (English)
Yan-lan Zhang; Hong-yan Wang; Dong-sheng Jiao; Yong-hong Hu
2008-01-01
Urea L-malic acid, a new second order nonlinear optical crystal, was studied using density functional theory (DFT). PBEPBE/6-31+G(d,p) method, the optimal method for comparing the results from thc sevcral DFT methods, was chosen to study the molecular structure. Infrared and ultraviolet-visible spectra were obtained and compared with experiments. The ultraviolet-visible spectrum was also analyzed by the molecular orbital population. The geometries, and the infrared and ultraviolet-visible spectra in water were studied using DFT methods in combination with the polarized continuum model to predict the perturbations by the solvent effect.
Dobos, L.; Budavári, T.; Csabai, I.; Szalay, A. S.
2008-10-01
We present the Filter and Spectrum Services consisting of easy-to-use web applications and web services for searching, plotting and managing large collections of spectral energy distribution data and filter profiles as well as for performing various scientific operations on spectra in a unified framework. The services provide keyword search, advanced query forms and SQL query possibilities for selecting spectra or bandpass curves which may be retrieved in a variety of file formats including XML, VOTable and ASCII. All SDSS DR1-DR5 spectra had been loaded into a database as well as the entire 2dF catalog that adds up to more than 2.5 million SEDs of about a million spatial objects, but registered users can upload their own data making it available for the rest of the community and are free to modify or delete them at any time. Theoretical catalogs, such as the Bruzual-Charlot stochastic burst model spectrum library (100k spectra) and the BaSeL stellar library are also available. Scientific services allow building rest-frame composite spectra out of selected spectra; calculating synthetic magnitudes by convolving spectra with an arbitrary set of bandpass curves of optical instrument filters to generate simulated photometric catalogs on-the-fly; galactic extinction correction, fitting of the continuum using different set of templates (Bruzual-Charlot '03 templates, SDSS eigenspectra), line fitting. All scientific functionalities are available from the web user interface and via the SOAP web services for programmers. MySpectrum is a cross-platform version of the spectrum web service for setting up your own spectrum repository. It integrates into the main service allowing easy access to your data for the whole VO community. The main idea behind our web services is to move scientific functionalities physically close to the database in order to spare network bandwidth. This way scientists may do research without setting up expensive hardware, downloading large datasets
Spectrum from Faint Galaxy IRAS F00183-7111
2003-01-01
NASA's Spitzer Space Telescope has detected the building blocks of life in the distant universe, albeit in a violent milieu. Training its powerful infrared eye on a faint object located at a distance of 3.2 billion light-years, Spitzer has observed the presence of water and organic molecules in the galaxy IRAS F00183-7111. With an active galactic nucleus, this is one of the most luminous galaxies in the universe, rivaling the energy output of a quasar. Because it is heavily obscured by dust (see visible-light image in the inset), most of its luminosity is radiated at infrared wavelengths.The infrared spectrograph instrument onboard Spitzer breaks light into its constituent colors, much as a prism does for visible light. The image shows a low-resolution spectrum of the galaxy obtained by the spectrograph at wavelengths between 4 and 20 microns. Spectra are graphical representations of a celestial object's unique blend of light. Characteristic patterns, or fingerprints, within the spectra allow astronomers to identify the object's chemical composition and to determine such physical properties as temperature and density.The broad depression in the center of the spectrum denotes the presence of silicates (chemically similar to beach sand) in the galaxy. An emission peak within the bottom of the trough is the chemical signature for molecular hydrogen. The hydrocarbons (orange) are organic molecules comprised of carbon and hydrogen, two of the most common elements on Earth. Since it has taken more than three billion years for the light from the galaxy to reach Earth, it is intriguing to note the presence of organics in a distant galaxy at a time when life is thought to have started forming on our home planet.Additional features in the spectrum reveal the presence of water ice (blue), carbon dioxide ice (green) and carbon monoxide (purple) in both gas and solid forms. The magenta peak corresponds to singly ionized neon gas, a spectral line often used by astronomers as a
Enhancing the Cosmic Shear Power Spectrum
Simpson, Fergus; Heymans, Catherine; Jimenez, Raul; Verde, Licia
2015-01-01
Applying a transformation to a non-Gaussian field can enhance the information content of the resulting power spectrum, by reducing the correlations between Fourier modes. In the context of weak gravitational lensing, it has been shown that this gain in information content is significantly compromised by the presence of shape noise. We apply clipping to mock convergence fields, a technique which is known to be robust in the presence of noise and has been successfully applied to galaxy number density fields. When analysed in isolation the resulting convergence power spectrum returns degraded constraints on cosmological parameters. However substantial gains can be achieved by performing a combined analysis of the power spectra derived from both the original and transformed fields. Even in the presence of realistic levels of shape noise, we demonstrate that this approach is capable of reducing the area of likelihood contours within the $\\Omega_m - \\sigma_8$ plane by more than a factor of three.
Hybrid spread spectrum radio system
Smith, Stephen F [London, TN; Dress, William B [Camas, WA
2010-02-09
Systems and methods are described for hybrid spread spectrum radio systems. A method, includes receiving a hybrid spread spectrum signal including: fast frequency hopping demodulating and direct sequence demodulating a direct sequence spread spectrum signal, wherein multiple frequency hops occur within a single data-bit time and each bit is represented by chip transmissions at multiple frequencies.
Santoro, Ernesto; Mazzeo, Giuseppe; Petrovic, Ana G; Cimmino, Alessio; Koshoubu, Jun; Evidente, Antonio; Berova, Nina; Superchi, Stefano
2015-08-01
The absolute configuration (AC) of the plant phytotoxin inuloxin A, produced by Inula viscosa, and of the fungal phytotoxin seiricardine A, obtained from Seiridium fungi, pathogen for cypress, has been determined by experimental measurements and theoretical simulations of chiroptical properties of three related methods, namely, Optical Rotatory Dispersion (ORD), Electronic Circular Dichroism (ECD), and Vibrational Circular Dichroism (VCD). Computational prediction by Density Functional Theory (DFT) of VCD spectra and by Time-dependent DFT (TDDFT) of ORD and ECD spectra allowed to assign (7R,8R,10S) AC to naturally occurring (+)-inuloxin A. In the case of compound (-)-seiricardine A, which lacks useful for the analysis UV-Vis absorption, and thus provides a hardly detectable ECD spectrum and quite low ORD values, an introduction of a suitable chromophore by chemical derivatization was performed. The corresponding derivative, 2-O-p-bromobenzoate ester, gave rise to an intense ECD spectrum and higher ORD and VCD values. The comparison of computed spectra with the experimental ones allowed to assign (1S,2R,3aS,4S,5R,7aS) AC to (-)-2-O-p-bromobenzoate ester of seiricardine A and then to (-)-seiricardine A. This study further supports a recent trend of concerted application of more than a single chiroptical technique toward an unambiguous assignment of AC of flexible and complex natural products. Moreover, the use of chemical derivatization, with insertion of suitable chromophoric moieties has allowed to treat also UV-Vis transparent molecules by ECD and ORD spectroscopies.
Evaluation of Spectrum Usage for GSM band in Indoor and Outdoor Scenario for Dynamic Spectrum Access
DEFF Research Database (Denmark)
Patil, Kishor P.; Barge, Snehal; Skouby, Knud Erik
2013-01-01
measurement results of GSM band including statistical as well as spectral occupancy details obtained from measurement campaign conducted in Pune, India for indoor and outdoor scenarios. The results can be further used as an input for spectrum regulator for considering Cognitive Radio (CR) operation in GSM...
A method to obtain pulse contrast on a single shot
Institute of Scientific and Technical Information of China (English)
Xiaoping Ouyang; Xiaoyan Li; Yanli Zhang; Zhaoyang Li; Guang Xu; Tao Wang; Baoqiang Zhu; Jianqiang Zhu
2009-01-01
@@ A novel method for obtaining a single shot multi-point high dynamic range pulse contrast measurement is presented.We use Dammann gratings to generate multiple beamlets by division of amplitude on ultra-short laser pulses.The analysis results show that this method can achieve high dynamic range in pulse contrast measurement on a single shot by using photomultiplier tube (PMT) detectors and the long work-ing distances to minimize cross talk between channels.Some distortion of pulse shape is also analyzed detailedly with the Dammann grating and its compensation grating, which may degrade the pulse contrast measurement in some degree by pulse stretching and spectrum clipping.
Diagrammatic expansion for positive density-response spectra: Application to the electron gas
Uimonen, A.-M.; Stefanucci, G.; Pavlyukh, Y.; van Leeuwen, R.
2015-03-01
In a recent paper [Phys. Rev. B 90, 115134 (2014), 10.1103/PhysRevB.90.115134] we put forward a diagrammatic expansion for the self-energy which guarantees the positivity of the spectral function. In this work we extend the theory to the density-response function. We write the generic diagram for the density-response spectrum as the sum of "partitions." In a partition the original diagram is evaluated using time-ordered Green's functions on the left half of the diagram, antitime-ordered Green's functions on the right half of the diagram, and lesser or greater Green's function gluing the two halves. As there exists more than one way to cut a diagram in two halves, to every diagram corresponds more than one partition. We recognize that the most convenient diagrammatic objects for constructing a theory of positive spectra are the half-diagrams. Diagrammatic approximations obtained by summing the squares of half-diagrams do indeed correspond to a combination of partitions which, by construction, yield a positive spectrum. We develop the theory using bare Green's functions and subsequently extend it to dressed Green's functions. We further prove a connection between the positivity of the spectral function and the analytic properties of the polarizability. The general theory is illustrated with several examples and then applied to solve the long-standing problem of including vertex corrections without altering the positivity of the spectrum. In fact already the first-order vertex diagram, relevant to the study of gradient expansion, Friedel oscillations, etc., leads to spectra which are negative in certain frequency domain. We find that the simplest approximation to cure this deficiency is given by the sum of the zeroth-order bubble diagram, the first-order vertex diagram, and a partition of the second-order ladder diagram. We evaluate this approximation in the three-dimensional homogeneous electron gas and show the positivity of the spectrum for all frequencies and
Energy Technology Data Exchange (ETDEWEB)
Borovskiy, A. V. [Department of Computer Science and Cybernetics, Baikal State University of Economics and Law, 11 Lenin Street, Irkutsk 664003 (Russian Federation); Galkin, A. L. [Coherent and Nonlinear Optics Department, A.M. Prokhorov General Physics Institute of the RAS, 38 Vavilov Street, Moscow 119991 (Russian Federation); Department of Physics of MBF, Pirogov Russian National Research Medical University, 1 Ostrovitianov Street, Moscow 117997 (Russian Federation); Kalashnikov, M. P., E-mail: galkin@kapella.gpi.ru [Max-Born-Institute for Nonlinear Optics and Short-Time Spectroscopy, 2a Max-Born-Strasse, Berlin 12489 (Germany)
2015-04-15
The new method of calculating energy spectra of accelerated electrons, based on the parameterization by their initial coordinates, is proposed. The energy spectra of electrons accelerated by Gaussian ultra-short relativistic laser pulse at a selected angle to the axis of the optical system focusing the laser pulse in a low density gas are theoretically calculated. The two-peak structure of the electron energy spectrum is obtained. Discussed are the reasons for its appearance as well as an applicability of other models of the laser field.
Institute of Scientific and Technical Information of China (English)
YAN Lixin; ZHANG Yongsheng; LIU Jingru; HUANG Wenhui; TANG Chuanxiang; CHENG Jianping
2008-01-01
The predominant spectral blueshifting of a sub-picosecond UV laser pulse induced by ultrafast ionization of noble gases was investigated. Spectral measurements were made at various gas densities. Typical quasi-periodic structures in the blueshifted spectrum were obtained. The observations were in connection with the so-called self-phase modulation of laser pulses in the ultrafast ionization process which was simply simulated with an ADK (Ammosov-Delone-Krainov) ionization model. Some quantitative information can be deduced from the measurements and calculations.
The Neutron Spectrum in a Uranium Tube
Energy Technology Data Exchange (ETDEWEB)
Johansson, E.; Jonsson, E.; Lindberg, M.; Mednis, J.
1963-10-15
A series of experimental and theoretical investigations on neutron spectra in lattice cells has been started at the reactor R1. This report gives the results from the first one of these cells - one with a tube of natural -uranium surrounded by heavy water. In the measurements the cell was placed in the central, vertical channel of the reactor. The neutron spectrum from a lead scatterer in the uranium tube - outer diameter 49.2 mm, inner diameter 28.3 mm - was measured with a fast chopper in the energy region 0.01 to 100 eV. Subsidiary measurements indicated that the spectrum in the beam from the lead piece corresponds to the spectrum of the angular flux integrated over all angles. This correspondence is important for the interpretation of the experimental data. The thermal part of the spectrum was found to deviate significantly from a Maxwellian. However, the deviation is not very large, and one could use a Maxwellian, at least to give a rough idea of the hardness of the spectrum. For the present tube the temperature of this Maxwellian was estimated as 90 to 100 deg C above the moderator temperature (33 deg C). In the joining region the rise of the spectrum towards the thermal part is slower than for the cell boundary spectrum, measured earlier. In the epithermal region the limited resolution of the chopper has affected the measurements at the energies of the uranium resonances. However, the shape of the spectrum on the flanks of the first resonance in {sup 238}U (6.68 eV) has been obtained accurately. In the theoretical treatment the THERMOS code with a free gas scattering model has been used. The energy region was 3.06 - 0.00025 eV. The agreement with the measurements is good for the thermal part - possibly the theoretical spectrum is a little softer than the experimental one. In the joining region the results from THERMOS are comparatively high - probably due to the scattering model used.
Supernovae anisotropy power spectrum
Ghodsi, Hoda; Habibi, Farhang
2016-01-01
We contribute another anisotropy study to this field of research using Supernovae Type Ia (SNe Ia). In this work, we utilise the power spectrum calculation method and apply it to both the current SNe Ia data and simulation. Our simulations are constructed with the characteristics of the upcoming survey of the Large Synoptic Survey Telescope (LSST), which shall bring us the largest SNe Ia collection to date. We make predictions for the amplitude of a possible dipole anisotropy or anisotropy in higher multipole moments that would be detectable by the LSST.
Virk, Jasveer; Liew, Zeyan; Olsen, Jørn; Nohr, Ellen A.; Catov, Janet M.; Ritz, Beate
2016-01-01
Objective: To evaluate whether early folic acid supplementation during pregnancy prevents diagnosis of autism spectrum disorders in offspring. Methods: Information on autism spectrum disorder diagnosis was obtained from the National Hospital Register and the Central Psychiatric Register. We estimated risk ratios for autism spectrum disorders for…
Precise and accurate determination of the ^{8}B decay spectrum
DEFF Research Database (Denmark)
Kirsebom, Oliver Sølund; Hyldegaard, Solveig; Alcorta, M.;
2011-01-01
Accurate measurements of the 8B neutrino spectrum are important for the interpretation of solar neutrino data. Experimentally, the 8B neutrino spectrum can be obtained from the measurement of the β-delayed α spectrum. We report on an α-α coincidence measurement performed at the IGISOL facility in...
Minimal length and bouncing-particle spectrum
Nozari, K.; Pedram, P.
2010-12-01
In this paper we study the effects of the Generalized Uncertainty Principle (GUP) on the spectrum of a particle that is bouncing vertically and elastically on a smooth reflecting floor in the Earth's gravitational field (a quantum bouncer). We calculate energy levels and corresponding wave functions of this system in terms of the GUP parameter. We compare the outcomes of our study with the results obtained from elementary quantum mechanics. A potential application of the present study is discussed finally.
Minimal Length and Bouncing Particle Spectrum
Nozari, Kourosh
2010-01-01
In this paper we study the effects of the Generalized Uncertainty Principle (GUP) on the spectrum of a particle that is bouncing vertically and elastically on a smooth reflecting floor in the Earth's gravitational field (a quantum bouncer). We calculate energy levels and corresponding wave functions of this system in terms of the GUP parameter. We compare the outcomes of our study with the results obtained from elementary quantum mechanics. A potential application of the present study is discussed finally.
Two-resonance probe for measuring electron density in low-pressure plasmas
Kim, D. W.; You, S. J.; Kim, S. J.; Kim, J. H.; Oh, W. Y.
2017-04-01
A technique for measuring double-checked electron density using two types of microwave resonance is presented. Simultaneous measurement of the resonances (plasma and quarter-wavelength resonator resonances), which were used for the cutoff probe (CP) and hairpin probe (HP), was achieved by the proposed microwave resonance probe. The developed two-resonance probe (TRP) consists of parallel separated coaxial cables exposing the radiation and detection tips. The structure resembles that of the CP, except the gapped coaxial cables operate not only as a microwave feeder for the CP but also as a U- shaped quarter-wavelength resonator for the HP. By virtue of this structure, the microwave resonances that have typically been used for measuring the electron density for the CP and HP were clearly identified on the microwave transmission spectrum of the TRP. The two types of resonances were measured experimentally under various power and pressure conditions for the plasma. A three-dimensional full-wave simulation model for the TRP is also presented and used to investigate and reproduce the resonances. The electron densities inferred from the resonances were compared and showed good agreement. Quantitative differences between the densities were attributed to the effects of the sheath width and spatial density gradient on the resonances. This accessible technique of using the TRP to obtain double-checked electron densities may be useful for comparative study and provides complementary uses for the CP and HP.
Hoard, D W; Brinkworth, Carolyn S; Ciardi, David R; Wachter, Stefanie
2007-01-01
We present the first mid-infrared (5.5-14.5 micron) spectrum of a highly magnetic cataclysmic variable, EF Eridani, obtained with the Infrared Spectrograph on the Spitzer Space Telescope. The spectrum displays a relatively flat, featureless continuum. A spectral energy distribution model consisting of a 9500 K white dwarf, L5 secondary star, cyclotron emission corresponding to a B~13 MG white dwarf magnetic field, and an optically thin circumbinary dust disk is in reasonable agreement with the extant 2MASS, IRAC, and IRS observations of EF Eri. Cyclotron emission is ruled out as a dominant contributor to the infrared flux density at wavelengths >3 microns. The spectral energy distribution longward of ~5 microns is dominated by dust emission. Even longer wavelength observations would test the model's prediction of a continuing gradual decline in the circumbinary disk-dominated region of the spectral energy distribution.
The spectrum of a single photoionized cloud
Ferland, G J
2003-01-01
The emission-line spectrum of a quasar is most likely emitted by an ensemble of photoionized clouds moving with a variety of velocities, with a range of densities and distances from the central object. The state of the art in this field is to first compute the emission from a single cloud, and then prescribe a mix of clouds to reproduce line intensities, profiles, and reverberation lags. Here I review the parameters that de-fine emission from a single cloud and the outstanding problems in qua-sar emission-line analysis.
Li, Xiongwei; Wang, Zhe; Fu, Yangting; Li, Zheng; Liu, Jianmin; Ni, Weidou
2014-01-01
Measurement of coal carbon content using laser-induced breakdown spectroscopy (LIBS) is limited by its low precision and accuracy. A modified spectrum standardization method was proposed to achieve both reproducible and accurate results for the quantitative analysis of carbon content in coal using LIBS. The proposed method used the molecular emissions of diatomic carbon (C2) and cyanide (CN) to compensate for the diminution of atomic carbon emissions in high volatile content coal samples caused by matrix effect. The compensated carbon line intensities were further converted into an assumed standard state with standard plasma temperature, electron number density, and total number density of carbon, under which the carbon line intensity is proportional to its concentration in the coal samples. To obtain better compensation for fluctuations of total carbon number density, the segmental spectral area was used and an iterative algorithm was applied that is different from our previous spectrum standardization calculations. The modified spectrum standardization model was applied to the measurement of carbon content in 24 bituminous coal samples. The results demonstrate that the proposed method has superior performance over the generally applied normalization methods. The average relative standard deviation was 3.21%, the coefficient of determination was 0.90, the root mean square error of prediction was 2.24%, and the average maximum relative error for the modified model was 12.18%, showing an overall improvement over the corresponding values for the normalization with segmental spectrum area, 6.00%, 0.75, 3.77%, and 15.40%, respectively.
Reduction of Artifacts in Images from MR Truncated Data Using Singularity Spectrum Analysis
Institute of Scientific and Technical Information of China (English)
骆建华; 庄天戈
2000-01-01
In this paper, the theory of signal singularity spectrum analysis (SSA) is proposed. Using SSA theory, a new method is presented to reduce truncation artifacts in magnetic resonance (MR) image due to truncated spectrum data. In the scheme, after detecting signal singularity locations using wavelet analysis in spectrum domain, SSA mathematic model is constructed, where weight coefficients are determined by known truncated spectrum data. Then, the remainder of the truncated spectrum can be obtained using SSA. Experiment and simulation results show that the SSA method will produce fewer artifacts in MR image from truncated spectrum than existing methods.
Singhania, Rajeshree
2005-04-01
Autistic spectrum disorders is a complex developmental disorder with social and communication dysfunction at its core. It has a wide clinical spectrum with a common triad of impairments -- social communication, social interaction and social imagination. Even mild or subtle difficulties can have a profound and devastating impact on the child. To be able to provide suitable treatments and interventions the distinctive way of thinking and learning of autistic children has to be understood. The core areas of social, emotional, communication and language deficits have to be addressed at all levels of functioning. The important goals of assessment include a categorical diagnosis of autism that looks at differential diagnosis, a refined precise documentation of the child's functioning in various developmental domains and ascertaining presence of co-morbid conditions. The interventions have to be adapted to the individual's chronological age, developmental phase and level of functioning. The strategies of curriculum delivery and teaching the child with autism is distinctive and includes presence of structure to increase predictability and strategies to reduce arousal of anxiety.
Transverse myelitis spectrum disorders
Directory of Open Access Journals (Sweden)
Pandit Lekha
2009-01-01
Full Text Available Acute transverse myelitis (ATM is an inflammatory demyelinating disorder that affects the spinal cord focally resulting in motor sensory and autonomic dysfunction. Establishing the diagnosis of ATM is not as difficult as determining the possible etiology. There is a difference in the perception of ATM seen in the West as compared to developing countries. In the West multiple sclerosis (MS is the most common inflammatory disorder of the central nervous system. An attack of ATM may be the beginning of MS. However, this may not be the case in developing countries where MS is uncommon. Most often transverse myelitis is monophasic and at best represents a site-restricted form of acute disseminated encephalomyelitis (ADEM. Traditionally the combination of optic neuritis and ATM, occurring as a monophasic illness would have been called as neuromyelitis optica (NMO. Changing concepts in the definition of NMO and the discovery of a biomarker, neuromyelitis optica immunoglobulin (NMO_IgG, has changed the way relapsing autoimmune disorders are being perceived currently. A variety of idiopathic inflammatory disorders such as Japanese form of optic spinal MS, recurrent myelitis, and recurrent optic neuritis have been brought under the umbrella of neuromyelitis spectrum disorders because of the association with NMO-IgG. Complete transverse myelitis accompanied by longitudinally extensive transverse myelitis which is seronegative for this biomarker has also been reported from several countries including Japan, Australia, and India. Thus, ATM is a heterogeneous disorder with a varied clinical spectrum, etiology, and outcome.
The Atacama Cosmology Telescope: Two-Season ACTPol Lensing Power Spectrum
Sherwin, Blake D; Sehgal, Neelima; Madhavacheril, Mathew; Addison, Graeme E; Aiola, Simone; Allison, Rupert; Battaglia, Nicholas; Beall, James A; Becker, Daniel T; Bond, J Richard; Calabrese, Erminia; Datta, Rahul; Devlin, Mark J; Dunner, Rolando; Dunkley, Joanna; Fox, Anna E; Gallardo, Patricio; Halpern, Mark; Hasselfield, Matthew; Henderson, Shawn; Hill, J Colin; Hilton, Gene C; Hubmayr, Johannes; Hughes, John P; Hincks, Adam D; Hlozek, Renee; Huffenberger, Kevin M; Koopman, Brian; Kosowsky, Arthur; Louis, Thibaut; Maurin, Loic; McMahon, Jeff; Moodley, Kavilan; Naess, Sigurd; Nati, Federico; Newburgh, Laura; Niemack, Michael D; Page, Lyman A; Sievers, Jonathan; Spergel, David N; Staggs, Suzanne T; Thornton, Robert J; Van Lanen, Jeff; Vavagiakis, Eve; Wollack, Edward J
2016-01-01
We report a measurement of the power spectrum of cosmic microwave background (CMB) lensing from two seasons of Atacama Cosmology Telescope Polarimeter (ACTPol) CMB data. The CMB lensing power spectrum is extracted from both temperature and polarization data using quadratic estimators. We obtain results that are consistent with the expectation from the best-fit Planck LCDM model over a range of multipoles L=80-2100, with an amplitude of lensing A_lens = 1.06 +/- 0.15 (stat.) +/- 0.06 (sys.) relative to Planck. Our measurement of the CMB lensing power spectrum gives sigma_8 Omega_m^0.25 = 0.643 +/- 0.054; including baryon acoustic oscillation scale data, we constrain the amplitude of density fluctuations to be sigma_8 = 0.831 +/- 0.053. We also update constraints on the neutrino mass sum. We verify our lensing measurement with a number of null tests and systematic checks, finding no evidence of significant systematic errors. This measurement relies on a small fraction of the ACTPol data already taken; more prec...
Institute of Scientific and Technical Information of China (English)
ZHOU Meng-ran; LI Zhen-bi
2007-01-01
Because of the former gas chemistry examination method defects, tunable diode laser absorption spectrum technology (TDLAS) was used. Itused an isolated absorption spectrum of the gas molecule to measure the gas absorption spectrum in order to distinguish the gas conveniently. The second harmonic (2f) was measured in this system.Due to the fact which the harmonious signal is proportional to the concentration of the absorption gas, the gas concentration may be obtained through examining harmonious signal. The theoretical analysis and the experimental result indicate that under the same level of pressure, survey with the signal-to-noise ratio(SNR) of 2f signal increases the accuracy by one order of magnitude and may reach 10-3 and the sensitivity may reach the 10-6 level compared to that of direct absorption. 5% methane density and a 30 cm absorption cell were used in the experiment. It has several advantages including high sensitivity, best resolution, and faster response and so on. The gas concentration monitoring ofcoal mine may be accomplished.
Density Distribution Sunflower Plots
Directory of Open Access Journals (Sweden)
William D. Dupont
2003-01-01
Full Text Available Density distribution sunflower plots are used to display high-density bivariate data. They are useful for data where a conventional scatter plot is difficult to read due to overstriking of the plot symbol. The x-y plane is subdivided into a lattice of regular hexagonal bins of width w specified by the user. The user also specifies the values of l, d, and k that affect the plot as follows. Individual observations are plotted when there are less than l observations per bin as in a conventional scatter plot. Each bin with from l to d observations contains a light sunflower. Other bins contain a dark sunflower. In a light sunflower each petal represents one observation. In a dark sunflower, each petal represents k observations. (A dark sunflower with p petals represents between /2-pk k and /2+pk k observations. The user can control the sizes and colors of the sunflowers. By selecting appropriate colors and sizes for the light and dark sunflowers, plots can be obtained that give both the overall sense of the data density distribution as well as the number of data points in any given region. The use of this graphic is illustrated with data from the Framingham Heart Study. A documented Stata program, called sunflower, is available to draw these graphs. It can be downloaded from the Statistical Software Components archive at http://ideas.repec.org/c/boc/bocode/s430201.html . (Journal of Statistical Software 2003; 8 (3: 1-5. Posted at http://www.jstatsoft.org/index.php?vol=8 .
Li, Guang-Xing; Burkert, Andreas
2016-09-01
Gravity is believed to be important on multiple physical scales in molecular clouds. However, quantitative constraints on gravity are still lacking. We derive an analytical formula which provides estimates on multiscale gravitational energy distribution using the observed surface density probability distribution function (PDF). Our analytical formalism also enables one to convert the observed column density PDF into an estimated volume density PDF, and to obtain average radial density profile ρ(r). For a region with N_col ˜ N^{-γ _N}, the gravitational energy spectra is E_p(k)˜ k^{-4(1 - 1/γ _N)}. We apply the formula to observations of molecular clouds, and find that a scaling index of -2 of the surface density PDF implies that ρ ˜ r-2 and Ep(k) ˜ k-2. The results are valid from the cloud scale (a few parsec) to around ˜ 0.1 pc. Because of the resemblance the scaling index of the gravitational energy spectrum and the that of the kinetic energy power spectrum of the Burgers turbulence (where E ˜ k-2), our result indicates that gravity can act effectively against turbulence over a multitude of physical scales. This is the critical scaling index which divides molecular clouds into two categories: clouds like Orion and Ophiuchus have shallower power laws, and the amount of gravitational energy is too large for turbulence to be effective inside the cloud. Because gravity dominates, we call this type of cloud g-type clouds. On the other hand, clouds like the California molecular cloud and the Pipe nebula have steeper power laws, and turbulence can overcome gravity if it can cascade effectively from the large scale. We call this type of cloud t-type clouds. The analytical formula can be used to determine if gravity is dominating cloud evolution when the column density PDF can be reliably determined.
Palit, Sourav; Chakrabarti, Sandip Kumar; Ray, Suman
2016-07-01
Earth's lower ionosphere and upper atmosphere absorb X-rays and gamma-rays from astronomical sources such as solar flares, Short Gamma ray Repeaters (SGRs) or Gamma Ray Bursts (GRBs). The electron-ion production rates due to the ionization of such energetic photons at different heights depend on the intensity and wavelength of the injected spectrum and hence vary from one source to another. Obviously the ion density vs. altitude profile has the imprint of the incident photon spectrum. In this paper, we examine the possibility of inverting the electron density-height profiles uniquely by deconvolution of the VLF amplitude signal to obtain information on the injected spectrum. We have been able to reproduce the soft-X-ray part of the injected spectra from two different classes of solar flares with satisfactory accuracy. With the possibilities of probing even lower parts of the atmosphere, the method presented here is useful to carry out a similar exercise to infer the higher energy part of solar flare spectra and spectra of more energetic events such as the GRBs, SGRs etc. We show that to a certain accuracy, the Earth's atmosphere may be used as a gigantic detector of relatively strong ionizing extra-terrestrial events.
Bakala, P; Karas, V; Dovciak, M; Wildner, M; Wzientek, D; Sramkova, E; Abramowicz, M; Goluchova, K; Mazur, G P; Vincent, F H
2014-01-01
High frequency quasi-periodic oscillations (HF QPOs) appear in the X-ray variability of several accreting low-mass binaries. In a series of works it was suggested that these QPOs may have connection to inhomogeneities orbiting close to an inner edge of the accretion disc. In this paper we explore the appearance of an observable signal generated by small radiating circular hot spots moving along quasi-elliptic trajectories close to the innermost stable circular orbit in the Schwarzschild spacetime. Our consideration takes into account the capabilities of observatories that have been operating in the past two decades represented by the Rossi X-ray Timing Explorer (RXTE) and the proposed future instruments represented by the Large Observatory for X-ray Timing (LOFT). For these purposes we choose such model parameters that lead to lightcurves comparable to those observed in Galactic black hole sources, in particular the microquasar GRS 1915+105. We find that when a weak signal corresponding to the hot-spot Kepler...
Directory of Open Access Journals (Sweden)
Jaime Gosálvez
2014-06-01
Conclusion: 1 Unnecessary incubation of spermatozoa prior to artificial insemination or in vitro fertilization, should be avoided, since sperm DNA longevity is significantly reduced after ex vivo sperm handling and 2 Although sperm selection by DCG significantly reduces the baseline levels of SDF of sperm in Fraction 3, sperm DNA longevity in this fraction was ultimately lower following 24 h incubation when compared to sperm recovered from non-centrifuged NSS.
A Cognitive Agent for Spectrum Monitoring and Informed Spectrum Access
2017-06-01
ARL-TR-8041 ● JUNE 2017 US Army Research Laboratory A Cognitive Agent for Spectrum Monitoring and Informed Spectrum Access by...needed. Do not return it to the originator. ARL-TR-8041 ● JUNE 2017 US Army Research Laboratory A Cognitive Agent for Spectrum...should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of
Eigenvalue spectrum of lattice N=4 super Yang-Mills
Weir, D.; Catterall, S.; Mehta, D. B.
We present preliminary results for the eigenvalue spectrum of four-dimensional ${\\cal N}=4$ super Yang-Mills theory on the lattice. In particular, by studying the the spectral density a measurement of the anomalous dimension is made and found to be consistent with zero.
{sup 14}N NQR spectrum of sildenafil citrate
Energy Technology Data Exchange (ETDEWEB)
Stephenson, David, E-mail: david.stephenson@sta.uwi.edu; Singh, Nadia [University of the West Indies, Chemistry Department (Trinidad and Tobago)
2015-04-15
The {sup 14}N nuclear quadrupole resonance (NQR) spectrum of sildenafil citrate tablets has been recorded allowing the quadrupole coupling constants and asymmetry parameters of all six unique nitrogen atoms in its structure to be determined. A density function calculation gives results that are largely in agreement with the experimental values.
Effects of Gyroresonance Absorption and Self Absorption on the Gyrosynchrotron Radiation Spectrum
Institute of Scientific and Technical Information of China (English)
ZHOU Ai-Hua; SU Ying-Na; HUANG Guang-Li
2004-01-01
Effects of gyroresonance absorption and self absorption on the gyrosynchrotron radiation spectrum are investi gated with a model in a magnetic dipole field. It is found that the gyroresonance absorption and self absorption suppress substantially the gyrosynchrotron radiation at lower frequencies where the radio source is optically thick.The suppression of the gyroresonance absorption on the spectrum increases with the increasing temperature and density of thermal electrons. The suppression of the self absorption on the spectrum increases as increasing number density of the nonthermal electrons. The influences of the gyroresonance absorption and the self one on the spectrum are compared quantitatively. It is shown that only when the number density of the nonthermal electron reaches a higher value of about 3 × 104 cm-3 above 10keV, can the effect of the self absorption on the spectrum compare with the effect of the gyroresonance absorption.
Yan, Fei; Petr-Gotzens, Monika G; Zhao, Gang; Wang, Wei; Wang, Liang; Liu, Yujuan; Pallé, Enric
2014-01-01
With the rapid developments in the exoplanet field, more and more terrestrial exoplanets are being detected. Characterising their atmospheres using transit observations will become a key datum in the quest for detecting an Earth-like exoplanet. The atmospheric transmission spectrum of our Earth will be an ideal template for comparison with future exo-Earth candidates. By observing a lunar eclipse, which offers a similar configuration to that of an exoplanet transit, we have obtained a high resolution and high signal-to-noise ratio transmission spectrum of the Earth's atmosphere. This observation was performed with the High Resolution Spectrograph at Xinglong Station, China during the total lunar eclipse in December 2011. We compare the observed transmission spectrum with our atmospheric model, and determine the characteristics of the various atmospheric species in detail. In the transmission spectrum, O2, O3, O2-O2, NO2 and H2O are detected, and their column densities are measured and compared with the satell...
Wave decomposition phenomenon and spectrum evolution over submerged bars
Institute of Scientific and Technical Information of China (English)
LI Benxia; YU Xiping
2009-01-01
Wave decomposition phenomenon and spectrum evolution over submerged bars are investigated by a previously developed numerical model. First, the computed free surface displacements of regular waves at various locations are compared with the available experimental data to confirm the validity of the numerical model, and satisfactory agreements are obtained. In addition, variations of decomposition characteristics with incident wave parameters and the change of energy spectrum for regular waves are also studied. Then the spectrum evolution of irregular waves over submerged bars, as well as the influence of incident peak wave period and the steepness of the front slope of the bar on spectrum evolution, is investigated. Wave decomposition and spectral shape are found to be significantly influenced by the incident wave conditions. When the upslope of the bar becomes 1:2, the length of the slope becomes shorter and will not benefit the generation of high frequency energy, so spectrum evolution is not significant.
Vibrational properties of gold nanoparticles obtained by green synthesis
Alvarez, Ramón A. B.; Cortez-Valadez, M.; Bueno, L. Oscar Neira; Britto Hurtado, R.; Rocha-Rocha, O.; Delgado-Beleño, Y.; Martinez-Nuñez, C. E.; Serrano-Corrales, Luis Ivan; Arizpe-Chávez, H.; Flores-Acosta, M.
2016-10-01
This study reports the synthesis and characterization of gold nanoparticles through an ecological method to obtain nanostructures from the extract of the plant Opuntia ficus-indica. Colloidal nanoparticles show sizes that vary between 10-20 nm, and present various geometric morphologies. The samples were characterized through optical absorption, Raman Spectroscopy and Transmission Electron Microscopy (TEM). Additionally, low energy metallic clusters of Aun (n=2-20 atoms) were modeled by computational quantum chemistry. The theoretical results were obtained with Density Functional Theory (DFT). The predicted results of Au clusters show a tendency and are correlated with the experimental results concerning the optical absorption bands and Raman spectroscopy in gold nanoparticles.
Neutron spectrum unfolding using neural networks
Energy Technology Data Exchange (ETDEWEB)
Vega C, H.R.; Hernandez D, V.M.; Manzanares A, E. [Universidad Autonoma de Zacatecas, A.P. 336, 98000 Zacatecas (Mexico)]. E-mail: rvega@cantera.reduaz.mx
2004-07-01
An artificial neural network has been designed to obtain the neutron spectra from the Bonner spheres spectrometer's count rates. The neural network was trained using a large set of neutron spectra compiled by the International Atomic Energy Agency. These include spectra from iso- topic neutron sources, reference and operational neutron spectra obtained from accelerators and nuclear reactors. The spectra were transformed from lethargy to energy distribution and were re-binned to 31 energy groups using the MCNP 4C code. Re-binned spectra and UTA4 matrix were used to calculate the expected count rates in Bonner spheres spectrometer. These count rates were used as input and correspondent spectrum was used as output during neural network training. The network has 7 input nodes, 56 neurons as hidden layer and 31 neurons in the output layer. After training the network was tested with the Bonner spheres count rates produced by twelve neutron spectra. The network allows unfolding the neutron spectrum from count rates measured with Bonner spheres. Good results are obtained when testing count rates belong to neutron spectra used during training, acceptable results are obtained for count rates obtained from actual neutron fields; however the network fails when count rates belong to monoenergetic neutron sources. (Author)
Rotational spectrum of tryptophan
Energy Technology Data Exchange (ETDEWEB)
Sanz, M. Eugenia, E-mail: maria.sanz@kcl.ac.uk; Cabezas, Carlos, E-mail: ccabezas@qf.uva.es; Mata, Santiago, E-mail: santiago.mata@uva.es; Alonso, Josè L., E-mail: jlalonso@qf.uva.es [Grupo de Espectroscopia Molecular (GEM), Edificio Quifima, Laboratorios de Espectroscopia y Bioespectroscopia, Unidad Asociada CSIC, Parque Científico Uva, Universidad de Valladolid, 47011 Valladolid (Spain)
2014-05-28
The rotational spectrum of the natural amino acid tryptophan has been observed for the first time using a combination of laser ablation, molecular beams, and Fourier transform microwave spectroscopy. Independent analysis of the rotational spectra of individual conformers has conducted to a definitive identification of two different conformers of tryptophan, with one of the observed conformers never reported before. The analysis of the {sup 14}N nuclear quadrupole coupling constants is of particular significance since it allows discrimination between structures, thus providing structural information on the orientation of the amino group. Both observed conformers are stabilized by an O–H···N hydrogen bond in the side chain and a N–H···π interaction forming a chain that reinforce the strength of hydrogen bonds through cooperative effects.
Rotational Spectrum of Tryptophan
Sanz, M. Eugenia; Cabezas, Carlos; Mata, Santiago; Alonso, José L.
2014-06-01
The rotational spectrum of the natural amino acid tryptophan has been observed using a recently constructed LA-MB-FTMW spectrometer, specifically designed to optimize the detection of heavier molecules at a lower frequency range. Independent analyses of the rotational spectra of individual conformers have conducted to a definitive identification of two different conformers of tryptophan, with one of the observed conformers never reported before. The experimental values of the 14N nuclear quadrupole coupling constants have been found capital in the discrimination of the conformers. Both observed conformers are stabilized by a O-H\\cdotsN hydrogen bond in the side chain and a N-H\\cdotsπ interaction forming a chain that reinforces the strength of hydrogen bonds through cooperative effects.
Directory of Open Access Journals (Sweden)
Rebecca E. Rosenberg
2011-01-01
Full Text Available We used a national online registry to examine variation in cumulative prevalence of community diagnosis of psychiatric comorbidity in 4343 children with autism spectrum disorders (ASD. Adjusted multivariate logistic regression models compared influence of individual, family, and geographic factors on cumulative prevalence of parent-reported anxiety disorder, depression, bipolar disorder, and attention deficit/hyperactivity disorder or attention deficit disorder. Adjusted odds of community-assigned lifetime psychiatric comorbidity were significantly higher with each additional year of life, with increasing autism severity, and with Asperger syndrome and pervasive developmental disorder—not otherwise specified compared with autistic disorder. Overall, in this largest study of parent-reported community diagnoses of psychiatric comorbidity, gender, autistic regression, autism severity, and type of ASD all emerged as significant factors correlating with cumulative prevalence. These findings could suggest both underlying trends in actual comorbidity as well as variation in community interpretation and application of comorbid diagnoses in ASD.
Electromagnetic spectrum management system
Seastrand, Douglas R.
2017-01-31
A system for transmitting a wireless countermeasure signal to disrupt third party communications is disclosed that include an antenna configured to receive wireless signals and transmit wireless counter measure signals such that the wireless countermeasure signals are responsive to the received wireless signals. A receiver processes the received wireless signals to create processed received signal data while a spectrum control module subtracts known source signal data from the processed received signal data to generate unknown source signal data. The unknown source signal data is based on unknown wireless signals, such as enemy signals. A transmitter is configured to process the unknown source signal data to create countermeasure signals and transmit a wireless countermeasure signal over the first antenna or a second antenna to thereby interfere with the unknown wireless signals.
Microwave Spectrum of Hexafluoroisopropanol
Shahi, Abhishek; Mani, Devendra; Arunan, E.
2012-06-01
Hexafluoroisopropanol (HFIP) is an important organic solvent and probably the only solvent which can dissolve polythene. IR studies, on this molecule confirm the existence of antiperiplanar (ap) and synclinical (sc) conformers. We have observed pure rotational spectrum of this molecule and the fitted rotational constants (A= 2105.1208(11) MHz, B= 1053.9942(3) MHz, C= 932.3398(3) MHz) confirm the presence of ap conformer. There are many other observed lines which most probably corresponds to sc structure and due to the large amplitude motion of H-atom, some of these transitions show tunneling splitting. Work is in progress for the deuterated (OD) and C-13 isotopologues of the monomer. HFIP is expected to exhibit interesting hydrogen bonding properties and we are planning to investigate them by studying its complex with water. The results will be presented in this talk. H. Schaal, T. Höber, and M. A. Suhm, J. Phys. Chem. A 104, 265 (2000).
Laboratory Density Functionals
Giraud, B. G.
2007-01-01
We compare several definitions of the density of a self-bound system, such as a nucleus, in relation with its center-of-mass zero-point motion. A trivial deconvolution relates the internal density to the density defined in the laboratory frame. This result is useful for the practical definition of density functionals.
Laboratory Density Functionals
Giraud, B G
2007-01-01
We compare several definitions of the density of a self-bound system, such as a nucleus, in relation with its center-of-mass zero-point motion. A trivial deconvolution relates the internal density to the density defined in the laboratory frame. This result is useful for the practical definition of density functionals.
Energy Technology Data Exchange (ETDEWEB)
Dodelson, Scott; /Fermilab /Chicago U., Astron. Astrophys. Ctr. /Northwestern U.; Shapiro, Charles; /Chicago U. /KICP, Chicago; White, Martin J.; /UC, Berkeley, Astron.
2005-08-01
Measurements of ellipticities of background galaxies are sensitive to the reduced shear, the cosmic shear divided by (1-{kappa}) where {kappa} is the projected density field. They compute the difference between shear and reduced shear both analytically and with simulations. The difference becomes more important an smaller scales, and will impact cosmological parameter estimation from upcoming experiments. A simple recipe is presented to carry out the required correction.
Energy Technology Data Exchange (ETDEWEB)
Dodelson, Scott; /Fermilab /Chicago U., Astron. Astrophys. Ctr. /Northwestern U.; Shapiro, Charles; /Chicago U. /KICP, Chicago; White, Martin J.; /UC, Berkeley, Astron.
2005-08-01
Measurements of ellipticities of background galaxies are sensitive to the reduced shear, the cosmic shear divided by (1-{kappa}) where {kappa} is the projected density field. They compute the difference between shear and reduced shear both analytically and with simulations. The difference becomes more important an smaller scales, and will impact cosmological parameter estimation from upcoming experiments. A simple recipe is presented to carry out the required correction.
Standardizing CT lung density measure across scanner manufacturers.
Chen-Mayer, Huaiyu Heather; Fuld, Matthew K; Hoppel, Bernice; Judy, Philip F; Sieren, Jered P; Guo, Junfeng; Lynch, David A; Possolo, Antonio; Fain, Sean B
2017-03-01
Computed Tomography (CT) imaging of the lung, reported in Hounsfield Units (HU), can be parameterized as a quantitative image biomarker for the diagnosis and monitoring of lung density changes due to emphysema, a type of chronic obstructive pulmonary disease (COPD). CT lung density metrics are global measurements based on lung CT number histograms, and are typically a quantity specifying either the percentage of voxels with CT numbers below a threshold, or a single CT number below which a fixed relative lung volume, nth percentile, falls. To reduce variability in the density metrics specified by CT attenuation, the Quantitative Imaging Biomarkers Alliance (QIBA) Lung Density Committee has organized efforts to conduct phantom studies in a variety of scanner models to establish a baseline for assessing the variations in patient studies that can be attributed to scanner calibration and measurement uncertainty. Data were obtained from a phantom study on CT scanners from four manufacturers with several protocols at various tube potential voltage (kVp) and exposure settings. Free from biological variation, these phantom studies provide an assessment of the accuracy and precision of the density metrics across platforms solely due to machine calibration and uncertainty of the reference materials. The phantom used in this study has three foam density references in the lung density region, which, after calibration against a suite of Standard Reference Materials (SRM) foams with certified physical density, establishes a HU-electron density relationship for each machine-protocol. We devised a 5-step calibration procedure combined with a simplified physical model that enabled the standardization of the CT numbers reported across a total of 22 scanner-protocol settings to a single energy (chosen at 80 keV). A standard deviation was calculated for overall CT numbers for each density, as well as by scanner and other variables, as a measure of the variability, before and after the
Interpretation of the COBE FIRAS CMBR spectrum
Wright, E. L.; Mather, J. C.; Fixsen, D. J.; Kogut, A.; Shafer, R. A.; Bennett, C. L.; Boggess, N. W.; Cheng, E. S.; Silverberg, R. F.; Smoot, G. F.
1994-01-01
The cosmic microwave background radiation (CMBR) spectrum measured by the Far-Infrared Absolute Spectrophotometer (FIRAS) instrument on NASA's Cosmic Background Explorer (COBE) is indistinguishable from a blackbody, implying stringent limits on energy release in the early universe later than the time t = 1 yr after the big bang. We compare the FIRAS data to previous precise measurements of the cosmic microwave background spectrum and find a reasonable agreement. We discuss the implications of the absolute value of y is less than 2.5 x 10(exp -5) and the absolute value of mu is less than 3.3 x 10(exp -4) 95% confidence limits found by Mather et al. (1994) on many processes occurring after t = 1 yr, such as explosive structure formation, reionization, and dissipation of small-scale density perturbations. We place limits on models with dust plus Population III stars, or evolving populations of IR galaxies, by directly comparing the Mather et al. spectrum to the model predictions.
Towards a worldwide wood economics spectrum.
Chave, Jerome; Coomes, David; Jansen, Steven; Lewis, Simon L; Swenson, Nathan G; Zanne, Amy E
2009-04-01
Wood performs several essential functions in plants, including mechanically supporting aboveground tissue, storing water and other resources, and transporting sap. Woody tissues are likely to face physiological, structural and defensive trade-offs. How a plant optimizes among these competing functions can have major ecological implications, which have been under-appreciated by ecologists compared to the focus they have given to leaf function. To draw together our current understanding of wood function, we identify and collate data on the major wood functional traits, including the largest wood density database to date (8412 taxa), mechanical strength measures and anatomical features, as well as clade-specific features such as secondary chemistry. We then show how wood traits are related to one another, highlighting functional trade-offs, and to ecological and demographic plant features (growth form, growth rate, latitude, ecological setting). We suggest that, similar to the manifold that tree species leaf traits cluster around the 'leaf economics spectrum', a similar 'wood economics spectrum' may be defined. We then discuss the biogeography, evolution and biogeochemistry of the spectrum, and conclude by pointing out the major gaps in our current knowledge of wood functional traits.
Multiconfiguration Pair-Density Functional Theory.
Li Manni, Giovanni; Carlson, Rebecca K; Luo, Sijie; Ma, Dongxia; Olsen, Jeppe; Truhlar, Donald G; Gagliardi, Laura
2014-09-09
We present a new theoretical framework, called Multiconfiguration Pair-Density Functional Theory (MC-PDFT), which combines multiconfigurational wave functions with a generalization of density functional theory (DFT). A multiconfigurational self-consistent-field (MCSCF) wave function with correct spin and space symmetry is used to compute the total electronic density, its gradient, the on-top pair density, and the kinetic and Coulomb contributions to the total electronic energy. We then use a functional of the total density, its gradient, and the on-top pair density to calculate the remaining part of the energy, which we call the on-top-density-functional energy in contrast to the exchange-correlation energy of Kohn-Sham DFT. Because the on-top pair density is an element of the two-particle density matrix, this goes beyond the Hohenberg-Kohn theorem that refers only to the one-particle density. To illustrate the theory, we obtain first approximations to the required new type of density functionals by translating conventional density functionals of the spin densities using a simple prescription, and we perform post-SCF density functional calculations using the total density, density gradient, and on-top pair density from the MCSCF calculations. Double counting of dynamic correlation or exchange does not occur because the MCSCF energy is not used. The theory is illustrated by applications to the bond energies and potential energy curves of H2, N2, F2, CaO, Cr2, and NiCl and the electronic excitation energies of Be, C, N, N(+), O, O(+), Sc(+), Mn, Co, Mo, Ru, N2, HCHO, C4H6, c-C5H6, and pyrazine. The method presented has a computational cost and scaling similar to MCSCF, but a quantitative accuracy, even with the present first approximations to the new types of density functionals, that is comparable to much more expensive multireference perturbation theory methods.
Stoppage in Autism Spectrum Disorders
DEFF Research Database (Denmark)
Grønborg, Therese Koops; Hansen, Stefan Nygaard; Nielsen, Svend V
2015-01-01
of bias in sibling recurrence risk estimation. This study investigated whether stoppage occurs in Danish families with a firstborn child diagnosed with autism spectrum disorders, and if stoppage was differential. We found that stoppage occurs moderately in Danish families affected by autism spectrum...... disorders, and that stoppage is differential. However, differential stoppage is a minor source of estimation bias in Danish sibling recurrence risk studies of autism spectrum disorders....
Method of estimating pulse response using an impedance spectrum
Energy Technology Data Exchange (ETDEWEB)
Morrison, John L; Morrison, William H; Christophersen, Jon P; Motloch, Chester G
2014-10-21
Electrochemical Impedance Spectrum data are used to predict pulse performance of an energy storage device. The impedance spectrum may be obtained in-situ. A simulation waveform includes a pulse wave with a period greater than or equal to the lowest frequency used in the impedance measurement. Fourier series coefficients of the pulse train can be obtained. The number of harmonic constituents in the Fourier series are selected so as to appropriately resolve the response, but the maximum frequency should be less than or equal to the highest frequency used in the impedance measurement. Using a current pulse as an example, the Fourier coefficients of the pulse are multiplied by the impedance spectrum at corresponding frequencies to obtain Fourier coefficients of the voltage response to the desired pulse. The Fourier coefficients of the response are then summed and reassembled to obtain the overall time domain estimate of the voltage using the Fourier series analysis.
SiGe superlattice nanocrystal infrared and Raman spectra: A density functional theory study
Abdulsattar, Mudar A.
2012-02-01
Infrared and Raman vibrational spectrum are calculated using ab initio density functional theory for SiGe superlattice nanocrystal of approximately 1.6 nm length. After obtaining the optimum positions of atoms via geometrical optimization using density functional theory, coupled perturbed Hartree-Fock equations are solved iteratively to obtain vibrational spectrum. Frequencies of vibrations are analyzed against intensities, reduced masses, and vibrational force constants. A scale factor of 0.81 is suggested to correct the frequencies of the present calculations that are obtained using STO-3 G basis functions. Results show that SiGe nanocrystals have complex and rich vibrational spectrum that can be generally divided into three regions. The highest reduced masses are in the first region where Si and Ge atoms are the main contributors to vibrations with a smaller number of vibrations attributed to hydrogen atoms. The highest intensity lines in SiGe superlattice nanocrystals are in the middle region where most of the modes of vibration can be excited. The third region is characterized by high force constants. The first region shows a redshift of the original Ge-Si bond vibration from the calculated bulk 418 cm-1 to the present nanocrystal 395 cm-1. Hydrogen vibrations interferences are found in the same redshift region that might induce uncertainties in the experimentally measured redshift. Si-H and Ge-H vibrations are observed mainly in the second and third region and less frequently in the first region. These vibrations include modes of vibration such as symmetric, asymmetric, wagging, scissor, rocking, and twisting modes.
DENSITY, EQUILIBRIUM HEAT OF FUSION AND EQUILIBRIUM MELTING TEMPERATURE OF NYLON 1010
Institute of Scientific and Technical Information of China (English)
FENG Jinhua; MO Zishen; CHEN Donglin
1990-01-01
The density, equilibrium heat of fusion and equilibrium melting temperature of Nylon 1010 were determined by means of infrared spectrum, differential scanning calorimetry, wide angle X-ray diffraction and density measurement techniques. According to Starkweather 's method crystalline density ρc and amorphous density ρa were estimated to be 1.098 and 1.003 g/cm3 respectively by extrapolating the straight lines of the IR absorbance against density to zero intensity. Owing to the less intense in absorbance and less sensitive to the change in crystallinity of the amorphors band the thus obtained ρc was too low in value.Thereby the value of the ratio ρc / ρa is far less than generally accepted mean value for most crystalline polymers. Accordingly, traditional X-raydiffraction method was used through determining the crystalline dimension(a=4.9(A), b=5.4(A) , c=27.8(A) , α=4 9 °β=77.0 °γ= 63.5 ° ) , and a rather correct value of ρc or the crystal density 1. 13 g/cm3 was obtained . The equilibrium heat of fusion Δ H 0m was estimated to be 244.0 J/g plotting Δ Hm's of specimens with different crystallinity against their corresponding specific volumes Vsp and extrapolating to completely crystalline condition ( Vcsp = 1 /ρc) As to the equilibrium melting temperature T0m ,because of the easiness ofrecrystallization of melt crystallized Nylon 1010 specimen ,the well-known Hoffman's Tm-Tc method failed in determining this value and an usually rarely used Kamide double extrapolation method was adopted. The so obtained value of T0m 487 seems to be fairly reasonable.
Regression in autistic spectrum disorders.
Stefanatos, Gerry A
2008-12-01
A significant proportion of children diagnosed with Autistic Spectrum Disorder experience a developmental regression characterized by a loss of previously-acquired skills. This may involve a loss of speech or social responsitivity, but often entails both. This paper critically reviews the phenomena of regression in autistic spectrum disorders, highlighting the characteristics of regression, age of onset, temporal course, and long-term outcome. Important considerations for diagnosis are discussed and multiple etiological factors currently hypothesized to underlie the phenomenon are reviewed. It is argued that regressive autistic spectrum disorders can be conceptualized on a spectrum with other regressive disorders that may share common pathophysiological features. The implications of this viewpoint are discussed.
Energy Technology Data Exchange (ETDEWEB)
Kudrin, Alexander V.; Shkokova, Natalya M. [Department of Radiophysics, University of Nizhny Novgorod, 23 Gagarin Ave., Nizhny Novgorod 603950 (Russian Federation); Ferencz, Orsolya E. [MTA Research Centre for Astronomy and Earth Sciences, Csatkai E. u. 6–8, Sopron H-9400 (Hungary); Zaboronkova, Tatyana M. [Department of Radiophysics, University of Nizhny Novgorod, 23 Gagarin Ave., Nizhny Novgorod 603950 (Russian Federation); Department of Nuclear Physics, R. E. Alekseev State Technical University of Nizhny Novgorod, 24 Minin St., Nizhny Novgorod 603950 (Russian Federation)
2014-11-15
Pulsed radiation from a loop antenna located in a cylindrical duct with enhanced plasma density is studied. The radiated energy and its distribution over the spatial and frequency spectra of the excited waves are derived and analyzed as functions of the antenna and duct parameters. Numerical results referring to the case where the frequency spectrum of the antenna current is concentrated in the whistler range are reported. It is shown that under ionospheric conditions, the presence of an artificial duct with enhanced density can lead to a significant increase in the energy radiated from a pulsed loop antenna compared with the case where the same source is immersed in the surrounding uniform magnetoplasma. The results obtained can be useful in planning active ionospheric experiments with pulsed electromagnetic sources operated in the presence of artificial field-aligned plasma density irregularities that are capable of guiding whistler waves.
Indian Academy of Sciences (India)
Li Xiao-Hong; Cui Hong-Ling; Li Li-Ben; Zhang Xian-Zhou
2013-07-01
Density functional theory calculations were performed to study the new polynitro cage compound with the similar framework of HNIW. IR spectrum, heat of formation and thermodynamic properties were predicted. The bond dissociation energies and bond orders for the weakest bonds were analysed to investigate the thermal stability of the title compound. The detonation and pressure were evaluated by using the Kamlet-Jacobs equations based on the theoretical density and condensed HOFs. In addition, the results show that there exists an essentially linear relationship between the WBIs of N-NO2 bonds and the charges -QNO2 on the nitro groups. The crystal structure obtained by molecular mechanics belongs to P21/C space group, with lattice parameters Z = 4, a = 12.3421 Å, b = 24.6849 Å, c = 20.4912 Å, = 1.896 g cm-3. The designed compound has high thermal stability and good detonation properties and is a promising high energy density compound.
Toward optimal cluster power spectrum analysis
Smith, Robert E
2014-01-01
The power spectrum of galaxy clusters is an important probe of the cosmological model. In this paper we determine the optimal weighting scheme for maximizing the signal-to-noise ratio for such measurements. We find a closed form analytic expression for the optimal weights. Our expression takes into account: cluster mass, finite survey volume effects, survey masking, and a flux limit. The implementation of this weighting scheme requires knowledge of the measured cluster masses, and analytic models for the bias and space-density of clusters as a function of mass and redshift. Recent studies have suggested that the optimal method for reconstruction of the matter density field from a set of clusters is mass-weighting (Seljak et al 2009, Hamaus et al 2010, Cai et al 2011). We compare our optimal weighting scheme with this approach and also with the original power spectrum scheme of Feldman et al (1994). We show that our optimal weighting scheme outperforms these approaches for both volume- and flux-limited cluster...
The Puzzling Spectrum of HD 94509
Cowley, C R; Hubrig, S
2015-01-01
The spectral features of HD 94509 are highly unusual, adding an extreme to the zoo of Be and shell stars. The shell dominates the spectrum, showing lines typical for spectral types mid-A to early-F, while the presence of a late/mid B-type central star is indicated by photospheric hydrogen line wings and helium lines. Numerous metallic absorption lines have broad wings but taper to narrow cores. They cannot be fit by Voigt profiles. We aim to describe and illustrate unusual spectral features of this star, and make rough calculations to estimate physical conditions and abundances in the shell. Furthermore, the central star is characterized. We assume mean conditions for the shell. An electron density estimate is made from the Inglis-Teller formula. Excitation temperatures and column densities for Fe I and Fe II are derived from curves of growth. The neutral H column density is estimated from high Paschen members. The column densities are compared with calculations made with the photoionization code Cloudy. Atmo...
Flat radio-spectrum galaxies and BL Lacs I. Core properties
Dennett-Thorpe, J; Marcha, MJ
2000-01-01
This paper concerns the relationship of BL Lacs and flat-spectrum weak emission-line galaxies. We compare the weak emission-line galaxies and the BL Lacs in a sample of 57 flat-spectrum objects (Marcha et al. 1996), using high-frequency radio and non-thermal optical flux densities, spectral indices
Flat radio-spectrum galaxies and BL Lacs I. Core properties
Dennett-Thorpe, J; Marcha, MJ
This paper concerns the relationship of BL Lacs and flat-spectrum weak emission-line galaxies. We compare the weak emission-line galaxies and the BL Lacs in a sample of 57 flat-spectrum objects (Marcha et al. 1996), using high-frequency radio and non-thermal optical flux densities, spectral indices
The very flat radio spectrum of 0735 plus 178 - A cosmic conspiracy
Cotton, W. D.; Wittels, J. J.; Shapiro, I. I.; Marcaide, J.; Owen, F. N.; Spangler, S. R.; Rius, A.; Angulo, C.; Clark, T. A.; Knight, C. A.
1980-01-01
Multifrequency interferometric and total flux density measurements of the radiation from 0735 plus 178 are discussed. It is shown that it is far more likely that the very flat radio spectrum of this source results from a superposition of incoherent synchrotron radiation from four distinct, homogeneous components, each with a peaked spectrum, than from radiation from a single inhomogeneous component.
High Density Metamaterials for Visible Light
2016-11-28
Split Ring Resonator Metamaterials with Fundamental Magnetic Resonance in the Middle Visible Spectrum,” Adv. Opt. Mater., vol. 2, no. 3, pp. 280–285...AFRL-AFOSR-JP-TR-2016-0097 High density metamaterials for visible light Dao Hua Zhang NANYANG TECHNOLOGICAL UNIVERSITY Final Report 11/28/2016...COVERED (From - To) 16 Jul 2014 to 15 Jul 2016 4. TITLE AND SUBTITLE High density metamaterials for visible light 5a. CONTRACT NUMBER 5b. GRANT
The Correlation between Dispersion Measure and X-ray Column Density from Radio Pulsars
He, C; Kaspi, V M
2013-01-01
Pulsars are remarkable objects that emit across the entire electromagnetic spectrum, providing a powerful probe of the interstellar medium. In this study, we investigate the relation between dispersion measure (DM) and X-ray absorption column density NH using 68 radio pulsars detected at X-ray energies with the Chandra X-ray Observatory or XMM-Newton. We find a best-fit empirical linear relation of NH (10^20 cm^-2)= 0.30+0.13-0.09 DM (pc cm^-3), which corresponds to an average ionization of 10+4-3%, confirming the ratio of one free electron per ten neutral hydrogen atoms commonly assumed in the literature. We also compare different NH estimates and note that some NH values obtained from X-ray observations are higher than the total Galactic HI column density along the same line of sight, while the optical extinction generally gives the best NH predictions.
Laboratory millimeter wave spectrum and astronomical search for vinyl acetate
Kolesniková, L.; Peña, I.; Alonso, J. L.; Cernicharo, J.; Tercero, B.; Kleiner, I.
2015-05-01
Context. The recent discovery of methyl acetate in Orion KL makes vinyl acetate, CH3C=OOCH=CH2, a potential molecule in the interstellar medium. We obtained very accurate spectroscopic constants in a comprehensive laboratory analysis of its rotational spectra which can be used to predict those transition frequencies towards interstellar sources. Aims: We present the experimental study and theoretical analysis of the ground torsional state of vinyl acetate in a large spectral range for astrophysical use. Methods: The room-temperature rotational spectrum of vinyl acetate has been measured from 125 to 305 GHz to provide direct frequencies to the astronomical community. Additional measurements have also been made using a broadband CP-FTMW spectrometer in the region of 6-18 GHz. Transition lines, corresponding to the most stable conformer, have been observed and assigned. All the rotational transitions revealed the A-E splitting due to the methyl internal rotation and had to be treated with a specific internal rotation code (BELGI-Cs). Results: We analyzed 2508 transitions up to J'' = 75 for vt = 0 for the most stable conformer of vinyl acetate. The new lines were globally fitted with previously published data and 24 parameters of the Hamiltonian were accurately determined. The spectral features of vinyl acetate were then searched for in Orion KL. Using the whole line survey of Orion KL (80-280 GHz) obtained with the IRAM 30 m radio telescope we can provide only an upper limit to the column density of vinyl acetate. However, using the ALMA science verification data we obtain a tentative detection of this species that will require further search at other frequencies to confirm its presence in this high mass star forming region. Table 2 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/577/A91
Multi-Higgs Mass Spectrum in Gauge-Higgs Unification
Kojima, Kentaro; Yamashita, Toshifumi
2008-01-01
We study an SU(2) supersymmetric gauge model in a framework of gauge-Higgs unification. Multi-Higgs spectrum appears in the model at low energy. We develop a useful perturbative approximation scheme for evaluating effective potential to study the multi-Higgs mass spectrum. We find that both tree-massless and massive Higgs scalars obtain mass corrections of similar size from finite parts of the loop effects. The corrections modify multi-Higgs mass spectrum, and hence, the loop effects are significant in view of future verifications of the gauge-Higgs unification scenario in high-energy experiments.
Theoretical modeling of the absorption spectrum of aqueous riboflavin
Zanetti-Polzi, Laura; Aschi, Massimiliano; Daidone, Isabella; Amadei, Andrea
2017-02-01
In this study we report the modeling of the absorption spectrum of riboflavin in water using a hybrid quantum/classical mechanical approach, the MD-PMM methodology. By means of MD-PMM calculations, with which the effect of riboflavin internal motions and of solvent interactions on the spectroscopic properties can be explicitly taken into account, we obtain an absorption spectrum in very good agreement with the experimental spectrum. In particular, the calculated peak maxima show a consistent improvement with respect to previous computational approaches. Moreover, the calculations show that the interaction with the environment may cause a relevant recombination of the gas-phase electronic states.
The action spectrum in chloroplast translocation in multilayer leaf cells
Directory of Open Access Journals (Sweden)
Zbigniew Lechowski
2015-01-01
Full Text Available By measurement of light transmittance through a leaf as criterion of chloroplast translocation, the action spectrum of Ajuga reptans was established. In the spectrum obtained, a correction was introduced for leaf autoabsorption calculated on the basis of the Beer-Lambert law. The action spectrum has two maxima: at λ= 375 nm and λ= 481 nm. The range above 502 nm has no significant effect on chloroplast translocation. Comparison with other objects examined demonstrated that in multilayer leaf cells riboflavin seems also to be a photoreceptor active in this process.
High resolution full-spectrum water Raman lidar
Institute of Scientific and Technical Information of China (English)
LIU FuChao; YI Fan; JIA JingYu; ZHANG YunPeng; ZHANG ShaoDong; YU ChangMing; TAN Ying
2012-01-01
Knowledge of the temporal-spatial distribution of water content in atmosphere and water phase change in cloud is important for atmospheric study.For this purpose,we have developed a high resolution full-spectrum water Raman lidar that can collect Raman signals from ice,water droplets and water vapor simultaneously.A double-grating polychromator and a 32-channel photomultiplier-tube detector are used to obtain a spectral resolution of ～0.19 nm in the full Raman spectrum range of water.Preliminary observations present the water Raman spectrum characteristics of both the mixed-phase cloud and humid air under cloudless condition.
Statistics of Lyapunov exponent spectrum in randomly coupled Kuramoto oscillators.
Patra, Soumen K; Ghosh, Anandamohan
2016-03-01
Characterization of spatiotemporal dynamics of coupled oscillatory systems can be done by computing the Lyapunov exponents. We study the spatiotemporal dynamics of randomly coupled network of Kuramoto oscillators and find that the spectral statistics obtained from the Lyapunov exponent spectrum show interesting sensitivity to the coupling matrix. Our results indicate that in the weak coupling limit the gap distribution of the Lyapunov spectrum is Poissonian, while in the limit of strong coupling the gap distribution shows level repulsion. Moreover, the oscillators settle to an inhomogeneous oscillatory state, and it is also possible to infer the random network properties from the Lyapunov exponent spectrum.
Spectrum of pediatric skin biopsies
Directory of Open Access Journals (Sweden)
Grace D′costa
2007-01-01
Full Text Available Background: Skin diseases are common in childhood and they are common reasons for pediatric visits to the hospital. In spite of this high occurrence, there are very few prospective studies addressing this issue. Aims: The present study was directed at determining the spectrum of dermato-pathological lesions encountered in a large general tertiary care hospital, over a two-year period. Materials and Methods: 107 cases formed the total sample studied, in a part prospective and part retrospective study. A detailed clinical history was recorded on a proforma prepared for the purpose and gross photographs were taken wherever possible. Results: Skin biopsies accounted for 7.29% of the total surgical pathology load, 55.44% of the total pediatric biopsies and 10.82% of the total number of skin biopsies. The age and sex distribution pattern revealed that the maximum number of biopsies (62.61% were of older children, with a male preponderance (57.94%. The anatomic distribution pattern indicated predominant involvement of the limbs (59.82%. The maximum numbers of cases were of infectious nature (24.29%; the most frequently encountered being borderline tuberculoid Hansen′s disease (8.4%. A positive correlation with the clinical diagnosis was obtained in 56.07% cases. Conclusions: Histopathology contributed to the diagnosis in a significant number of (82.23% cases, indicating its importance and utility.
Spectrum handoff algorithm with imperfect spectrum sensing incognitive radio networks
Ma, Bin; Bao, Xiao-min; Xie, Xian-zhong
2016-10-01
To guarantee the quality of service of licensed users, the unlicensed users must vacate the occupied channel by spectrum handoff if licensed users appear in the licensed spectrum. However, spectrum sensing with false alarm and missed detection may lead to more inaccuracy problems when unlicensed users perform spectrum handoff. To improve the problems mentioned before, we utilize PRP M/G/1 queuing network model to propose a spectrum handoff algorithm with error data retransmission mechanism and analyze its performance by transmission delay and extended data delivery time. In addition, we discuss the relationship between false alarm probability, extended data delivery time and user traffic load and verify the effectiveness of the proposed algorithm.
Considering Air Density in Wind Power Production
Farkas, Zénó
2011-01-01
In the wind power production calculations the air density is usually considered as constant in time. Using the CIPM-2007 equation for the density of moist air as a function of air temperature, air pressure and relative humidity, we show that it is worth taking the variation of the air density into account, because higher accuracy can be obtained in the calculation of the power production for little effort.
DTV protection regions for spectrum sharing
Directory of Open Access Journals (Sweden)
Nasir Faruk
2014-09-01
Full Text Available In this Letter, the authors propose a technique that allows a secondary user (SU to reuse the spectrum allocated to TV broadcast system. The approach is based on protection view point and an SU is allowed to transmit outside the noise limited contour (grade B contour with additional protection margin. An algorithm was developed that predicts the grade B contour and makes a decision on the availability of the spectrum. The keep-out distance was obtained using the existing path loss models and a model developed based on field strength measurements conducted in the very high frequency (VHF and ultra high frequency (UHF broadcast frequencies. Results of simulation indicate that the extra margin does not follow a linear curve as expected, but strongly depends on the operating frequency and terrain profile of the area. In addition, the measured model's prediction deviates significantly from the other models' prediction.
Cause of winter gravity wave spectrum saturation
Institute of Scientific and Technical Information of China (English)
WU; Yongfu; XU; Jiyao
2005-01-01
This paper utilizes horizontal velocity measurements observed from 19 chaff rockets and nearly simultaneous temperature measurements collected from 19 falling sphere rockets to study the cause of winter gravity wave spectrum saturation. Results suggest that strong horizontal velocity shears larger than 0.04 s-1 are observed to be present at various heights near the winter mesopause. On one single chaff rocket flight, an extremely strong horizontal velocity shear as high as 0.33 s-1 is observed at 87.4 km and is believed to be the strongest value ever measured in the mesosphere. These strong horizontal velocity shears, together with Brunt-V(a)is(a)l(a) frequency squared obtained from the temperature profile, act collectively to yield two dynamical instability regions of Richardson number smaller than 1/4, suggesting that the saturated gravity wave spectrum observed by the chaff rockets in winter is a result of dynamical instability.
Autofit and the Spectrum of Eugenol
Riffe, Erika; Welden, Sawyer; Cockram, Emma; Ervin, Katherine; Shipman, Steven; Funderburk, Cameron M.; Brown, Gordon G.; Widicus Weaver, Susanna L.
2016-06-01
The rotational spectrum of eugenol, the primary constituent in clove oil, was obtained via chirped-pulse Fourier transform microwave spectroscopy from 3-8 GHz in a supersonic expansion on a sample that was extracted from cloves via steam distillation. Ab initio calculations indicate that this molecule possesses several conformers with energies that are only a few hundred wavenumbers above that of the global minimum conformation, due to different relative orientations of the molecule's methoxy and allyl groups. Eugenol's spectrum was analyzed with a new version of the Autofit software that has been designed to run in cluster computing environments. Here we will present the results of this study, including benchmarking results for the new version of Autofit.
Interstellar absorption lines in the spectrum of Gamma Velorum
Morton, D. C.; Bhavsar, S. P.
1979-01-01
Copernicus scans of selected interstellar absorption lines in the UV spectrum of Gamma Vel are analyzed, together with ground-based data, to obtain column densities for various ion states of C, N, O, Na, Mg, Al, Si, P, S, Cl, Ar, Ca, Mn, Fe, and CO. N I and O I are fitted to a single empirical curve of growth with a velocity parameter (b) of 8 km/s; Mg II, Si II, P II, S II, Mn II, and Fe II are fitted to another curve with b between 3 and 9 km/s. Abundance determinations relative to H I show that: (1) C, N, P, S, and Ar are probably close to their solar values; (2) O may be depleted by about a factor of 2; (3) Mg, Al, Si, Cl, Mn, and Fe are depleted by a factor of 4 or more: (4) Al is depleted by at least a factor of 10 in the H II region; and (5) both N V and O VI are present, but not C IV. The N V/O VI ratio implies that the electron temperature in the H II region is about 275,000 K.
Dirac cones in the spectrum of bond-decorated graphenes
Energy Technology Data Exchange (ETDEWEB)
Van den Heuvel, Willem, E-mail: wvan@unimelb.edu.au; Soncini, Alessandro, E-mail: asoncini@unimelb.edu.au [School of Chemistry, The University of Melbourne, VIC 3010 (Australia)
2014-06-21
We present a two-band model based on periodic Hückel theory, which is capable of predicting the existence and position of Dirac cones in the first Brillouin zone of an infinite class of two-dimensional periodic carbon networks, obtained by systematic perturbation of the graphene connectivity by bond decoration, that is by inclusion of arbitrary π-electron Hückel networks into each of the three carbon–carbon π-bonds within the graphene unit cell. The bond decoration process can fundamentally modify the graphene unit cell and honeycomb connectivity, representing a simple and general way to describe many cases of graphene chemical functionalization of experimental interest, such as graphyne, janusgraphenes, and chlorographenes. Exact mathematical conditions for the presence of Dirac cones in the spectrum of the resulting two-dimensional π-networks are formulated in terms of the spectral properties of the decorating graphs. Our method predicts the existence of Dirac cones in experimentally characterized janusgraphenes and chlorographenes, recently speculated on the basis of density functional theory calculations. For these cases, our approach provides a proof of the existence of Dirac cones, and can be carried out at the cost of a back of the envelope calculation, bypassing any diagonalization step, even within Hückel theory.
Fast dictionary-based reconstruction for diffusion spectrum imaging.
Bilgic, Berkin; Chatnuntawech, Itthi; Setsompop, Kawin; Cauley, Stephen F; Yendiki, Anastasia; Wald, Lawrence L; Adalsteinsson, Elfar
2013-11-01
Diffusion spectrum imaging reveals detailed local diffusion properties at the expense of substantially long imaging times. It is possible to accelerate acquisition by undersampling in q-space, followed by image reconstruction that exploits prior knowledge on the diffusion probability density functions (pdfs). Previously proposed methods impose this prior in the form of sparsity under wavelet and total variation transforms, or under adaptive dictionaries that are trained on example datasets to maximize the sparsity of the representation. These compressed sensing (CS) methods require full-brain processing times on the order of hours using MATLAB running on a workstation. This work presents two dictionary-based reconstruction techniques that use analytical solutions, and are two orders of magnitude faster than the previously proposed dictionary-based CS approach. The first method generates a dictionary from the training data using principal component analysis (PCA), and performs the reconstruction in the PCA space. The second proposed method applies reconstruction using pseudoinverse with Tikhonov regularization with respect to a dictionary. This dictionary can either be obtained using the K-SVD algorithm, or it can simply be the training dataset of pdfs without any training. All of the proposed methods achieve reconstruction times on the order of seconds per imaging slice, and have reconstruction quality comparable to that of dictionary-based CS algorithm.
Institute of Scientific and Technical Information of China (English)
ZHOU Ri-Feng; WANG Jue; CHEN Wei-Min
2009-01-01
Due to X-ray attenuation being approximately proportional to material density, it is possible to measure the inner density through Industrial Computed Tomography (ICT) images accurately. In practice, however, a number of factors including the non-linear effects of beam hardening and diffuse scattered radia-tion complicate the quantitative measurement of density variations in materials. This paper is based on the linearization method of beam hardening correction, and uses polynomial fitting coefficient which is obtained by the curvature of iron polychromatic beam data to fit other materials. Through theoretical deduction, the paper proves that the density measure error is less than 2% if using pre-filters to make the spectrum of linear accelerator range mainly 0.3 MeV to 3 MeV. Experiment had been set up at an ICT system with a 9 MeV electron linear accelerator. The result is satisfactory. This technique makes the beam hardening correction easy and simple, and it is valuable for measuring the ICT density and making use of the CT images to recognize materials.
First results obtained by the Cluster STAFF experiment
Directory of Open Access Journals (Sweden)
N. Cornilleau-Wehrlin
Full Text Available The Spatio Temporal Analysis of Field Fluctuations (STAFF experiment is one of the five experiments, which constitute the Cluster Wave Experiment Consortium (WEC. STAFF consists of a three-axis search coil magnetometer to measure magnetic fluctuations at frequencies up to 4 kHz, a waveform unit (up to either 10 Hz or 180 Hz and a Spectrum Analyser (up to 4 kHz. The Spectrum Analyser combines the 3 magnetic components of the waves with the two electric components measured by the Electric Fields and Waves experiment (EFW to calculate in real time the 5 × 5 Hermitian cross-spectral matrix at 27 frequencies distributed logarithmically in the frequency range 8 Hz to 4 kHz. The time resolution varies between 0.125 s and 4 s. The first results show the capabilities of the experiment, with examples in different regions of the magnetosphere-solar wind system that were encountered by Cluster at the beginning of its operational phase. First results obtained by the use of some of the tools that have been prepared specifically for the Cluster mission are described. The characterisation of the motion of the bow shock between successive crossings, using the reciprocal vector method, is given. The full characterisation of the waves analysed by the Spectrum Analyser, thanks to a dedicated program called PRASSADCO, is applied to some events; in particular a case of very confined electromagnetic waves in the vicinity of the equatorial region is presented and discussed.
Key words. Magnetospheric physics (magnetopause, cusp and boundary layer – Space plasma physics (waves and instabilities; shock waves
The density curve of F distribution
Institute of Scientific and Technical Information of China (English)
LIU Xiaopeng; LIU Kunhui
2004-01-01
Employing the properties of special function,we discuss the positional relation between two density curves with different parameters for F distribution in this paper.Some varying regularities about the position of density curve of F distribution have been obtained.
Comment on Breakup Densities of Hot Nuclei
Viola, V E; Natowitz, J B; Yennello, S J
2006-01-01
In [1,2]the observed decrease in spectral peak energies of IMFs emitted from hot nuclei was interpreted in terms of a breakup density that decreased with increasing energy. Subsequently, Raduta et al. [3] performed MMM simulations that showed decreasing spectral peaks could be obtained at constant density. In this letter we examine this apparent inconsistency.
The Thermal Entropy Density of Spacetime
Directory of Open Access Journals (Sweden)
Rongjia Yang
2013-01-01
Full Text Available Introducing the notion of thermal entropy density via the first law of thermodynamics and assuming the Einstein equation as an equation of thermal state, we obtain the thermal entropy density of any arbitrary spacetime without assuming a temperature or a horizon. The results confirm that there is a profound connection between gravity and thermodynamics.
Bachmann, Kurt T.
2000-01-01
I helped to complete a research project with NASA scientists Dr. David Hathaway (my mentor), Rick Bogart, and John Beck from the SOHO/SOI collaboration. Our published paper in 'Solar Physics' was titled 'The Solar Convection Spectrum' (April 2000). Two of my undergraduate students were named on the paper--Gavrav Khutri and Josh Petitto. Gavrav also wrote a short paper for the National Conference of Undergraduate Research Proceedings in 1998 using a preliminary result. Our main result was that we show no evidence of a scale of convection named 'mesogranulation'. Instead, we see only direct evidence for the well-known scales of convection known as graduation and supergranulation. We are also completing work on vertical versus horizontal flow fluxes at the solar surface. I continue to work on phase relationships of solar activity indicators, but I have not yet written a paper with my students on this topic. Along with my research results, I have developed and augmented undergraduate courses at Birmingham-Southern College by myself and with other faculty. We have included new labs and observations, speakers from NASA and elsewhere, new subject material related to NASA and space science. I have done a great deal of work in outreach, mostly as President and other offices in the Birmingham Astronomical Society. My work includes speaking, attracting speakers, giving workshops, and governing.
PINS Spectrum Identification Guide
Energy Technology Data Exchange (ETDEWEB)
A.J. Caffrey
2012-03-01
The Portable Isotopic Neutron Spectroscopy—PINS, for short—system identifies the chemicals inside munitions and containers without opening them, a decided safety advantage if the fill chemical is a hazardous substance like a chemical warfare agent or an explosive. The PINS Spectrum Identification Guide is intended as a reference for technical professionals responsible for the interpretation of PINS gamma-ray spectra. The guide is divided into two parts. The three chapters that constitute Part I cover the science and technology of PINS. Neutron activation analysis is the focus of Chapter 1. Chapter 2 explores PINS hardware, software, and related operational issues. Gamma-ray spectral analysis basics are introduced in Chapter 3. The six chapters of Part II cover the identification of PINS spectra in detail. Like the PINS decision tree logic, these chapters are organized by chemical element: phosphorus-based chemicals, chlorine-based chemicals, etc. These descriptions of hazardous, toxic, and/or explosive chemicals conclude with a chapter on the identification of the inert chemicals, e.g. sand, used to fill practice munitions.
Rotational Spectrum of Saccharine
Alonso, Elena R.; Mata, Santiago; Alonso, José L.
2017-06-01
A significant step forward in the structure-activity relationships of sweeteners was the assignment of the AH-B moiety in sweeteners by Shallenberger and Acree. They proposed that all sweeteners contain an AH-B moiety, known as glucophore, in which A and B are electronegative atoms separated by a distance between 2.5 to 4 Å. H is a hydrogen atom attached to one of the electronegative atom by a covalent bond. For saccharine, one of the oldest artificial sweeteners widely used in food and drinks, two possible B moieties exist ,the carbonyl oxygen atom and the sulfoxide oxygen atom although there is a consensus of opinion among scientists over the assignment of AH-B moieties to HN-SO. In the present work, the solid of saccharine (m.p. 220°C) has been vaporized by laser ablation (LA) and its rotational spectrum has been analyzed by broadband CP-FTMW and narrowband MB-FTMW Fourier transform microwave techniques. The detailed structural information extracted from the rotational constants and ^{14}N nuclear quadrupole coupling constants provided enough information to ascribe the glucophore's AH and B sites of saccharine. R. S. Shallenberger, T. E. Acree. Nature 216, 480-482 Nov 1967. R. S. Shallenberger. Taste Chemistry; Blackie Academic & Professional, London, (1993).
The worldwide leaf economics spectrum
Wright, I.J.; Reich, P.B.; Westoby, M.; Ackerly, D.D.; Baruch, Z.; Bongers, F.J.J.M.; Cavender-Bares, J.; Chapin, T.; Cornelissen, J.H.C.; Diemer, M.; Flexas, J.; Garnier, E.; Groom, P.K.; Gulias, J.; Hikosaka, K.; Lamont, B.B.; Lee, T.; Lee, W.; Lusk, C.; Midgley, J.J.; Navas, M.L.; Niinements, Ü.; Oleksyn, J.; Osada, N.; Poorter, H.; Poot, P.; Prior, L.; Pyankov, V.I.; Roumet, C.; Thomas, S.C.; Tjoelker, M.G.; Veneklaas, E.J.; Villar, R.
2004-01-01
Bringing together leaf trait data spanning 2,548 species and 175 sites we describe, for the first time at global scale, a universal spectrum of leaf economics consisting of key chemical, structural and physiological properties. The spectrum runs from quick to slow return on investments of nutrients
The spectrum of spinning superparticles
Bergshoeff, E.; Holten, J.W. van
1989-01-01
We construct the action and transformation rules of a massless spinning superparticle in D dimensions which has N worldline as well as M target space supersymmetries. The spectrum of physical states for different values of N, M and D is presented. We also discuss the action, symmetries and spectrum
Dynamic Spectrum Sharing among Femtocells
DEFF Research Database (Denmark)
Da Costa, Gustavo Wagner Oliveira
2012-01-01
The ever-growing demand for mobile broadband is leading to an imminent spectrum scarcity. In order to cope with such situation dynamic spectrum sharing and the widespread deployment of small cells (femtocells) are promising solutions. Delivering such a view is not short of challenges. Massive dep...
HISTOMORPHOLOGICAL SPECTRUM OF BREAST LESIONS
Directory of Open Access Journals (Sweden)
Kiran H. S
2016-07-01
Full Text Available BACKGROUND Cancer of the breast is the second most common cause of cancer in women. Benign or malignant lesions presenting as mass in the breast causes anxiety to the patients and the family members. AIMS AND OBJECTIVES OF THE STUDY 1. To classify different types of lesions of breast, both benign and malignant. 2. Histomorphological study of various types of benign and malignant breast lesions. 3. To study spectrum of lesions associated with benign and malignant breast diseases. SETTING AND DESIGN All the breast biopsies, lumpectomies, and mastectomy specimens presenting to Department of Pathology of our institution between June 2012 to June 2014. MATERIALS AND METHODS A sample size of 100 cases are included in this study. Clinical details are taken from records. The specimens of breast sent to the Department of Pathology are processed by routine histopathological techniques. Histopathological features are studied on haematoxylin and eosin-stained sections. STATISTICAL ANALYSIS Statistically, the test of proportion is used to obtain the frequency of all lesions. Chi-square test, which is used to find the association between the spectrum of lesions showed a p value of 0.0438 and hence the study was considered significant. RESULTS In our study, out of 100 cases, malignant breast lesions constituted the majority of the lesions comprising of 49 cases (49%, followed by benign lesions comprising 46 cases (46% and the inflammatory lesions comprising 5 cases (5%. Among benign lesions, fibrocystic disease was the predominant lesion comprising of 39 cases (41%, followed by fibroadenoma comprising 26 cases (28%, which is followed by 13 cases (14% of fibrocystic disease with columnar cell change and 8 cases (9% of sclerosing adenosis. Among malignant lesions, invasive ductal carcinoma (NST type was the most common lesion comprising 31 cases (61% followed by 11 cases (21% of invasive lobular carcinoma. Invasive papillary carcinoma and medullary carcinoma
Understanding redshift space distortions in density-weighted peculiar velocity
Sugiyama, Naonori S; Spergel, David N
2015-01-01
Observations of the kinetic Sunyaev-Zel'dovich (kSZ) effect measure the density-weighted velocity field, a potentially powerful cosmological probe. This paper presents an analytical method to predict the power spectrum and two-point correlation function of the density-weighted velocity in redshift space, the direct observables in kSZ surveys. We show a simple relation between the density power spectrum and the density-weighted velocity power spectrum that holds for both dark matter and halos. Using this relation, we can then extend familiar perturbation expansion techniques to the kSZ power spectrum. One of the most important features of the density-weighted velocity is the change of the sign of infall velocity at small scales due to the nonlinear redshift space distortion. Our model can explain this characteristic feature without any free parameters. As a result, our results can precisely predict the non-linear behavior of the density-weighted velocity field in redshift space up to $\\sim10\\ h^{-1} {\\rm Mpc}$...
Method for obtaining solid micro -or nanoparticles
Ventosa Rull, Nora; Veciana Miró, Jaume; Cano-Sarabia, Mary; Sala Vergés, Santiago
2008-01-01
[EN] The invention provides a novel method for obtaining solid micro -or nanoparticIes with a homogeneous structure. A method is provided for obtaining solid micro -or nanoparticIes with a homogeneous structure having a particIe size of less than 10 /lm where the processed solid compound has the natural, crystalline, amorphous, polymorphic and other features associated with the starting compound. In accordance with the invention a method which also makes it possible to obtain solid m...
Comparison of RF spectrum prediction methods for dynamic spectrum access
Kovarskiy, Jacob A.; Martone, Anthony F.; Gallagher, Kyle A.; Sherbondy, Kelly D.; Narayanan, Ram M.
2017-05-01
Dynamic spectrum access (DSA) refers to the adaptive utilization of today's busy electromagnetic spectrum. Cognitive radio/radar technologies require DSA to intelligently transmit and receive information in changing environments. Predicting radio frequency (RF) activity reduces sensing time and energy consumption for identifying usable spectrum. Typical spectrum prediction methods involve modeling spectral statistics with Hidden Markov Models (HMM) or various neural network structures. HMMs describe the time-varying state probabilities of Markov processes as a dynamic Bayesian network. Neural Networks model biological brain neuron connections to perform a wide range of complex and often non-linear computations. This work compares HMM, Multilayer Perceptron (MLP), and Recurrent Neural Network (RNN) algorithms and their ability to perform RF channel state prediction. Monte Carlo simulations on both measured and simulated spectrum data evaluate the performance of these algorithms. Generalizing spectrum occupancy as an alternating renewal process allows Poisson random variables to generate simulated data while energy detection determines the occupancy state of measured RF spectrum data for testing. The results suggest that neural networks achieve better prediction accuracy and prove more adaptable to changing spectral statistics than HMMs given sufficient training data.
Using quartzofeldspathic waste to obtain foamed glass material
Directory of Open Access Journals (Sweden)
O.V. Kazmina
2016-03-01
Full Text Available The present paper proposes a method for the processing of mine refuse non-ferrous metal ore in the production of foamed glass. The subject of this research is a low-temperature frit synthesis (<900 °C, allowing for the high-temperature glass melting process to be avoided. The technology for the production of frit without complete melting of the batch and without using glass-making units offers a considerable reduction in energy consumption and air pollution. It was found that material samples obtained with a density of up to 250 kg/m3 are of rigidity (up to 1.7 MPa in comparison with the conventional foamed glass (1 MPa. This increased rigidity was due to the presence of crystalline phase particles in its interpore partition of less than 2 µm in size. Material with a density of 300 kg/cm3 is recommended for thermal insulation for the industrial and construction sectors. At densities above 300 kg/cm3 and a strength of 2.5 MPa, the purpose becomes heat-insulating construction material. The proposed method for obtaining a porous material from waste widens our choice of raw materials for foamed glass, whilst saving resources and energy.
U.S. Environmental Protection Agency — Road density is generally highly correlated with amount of developed land cover. High road densities usually indicate high levels of ecological disturbance. More...
Level Densities and Radiative Strength Functions in ^{56}FE and ^{57}FE
Energy Technology Data Exchange (ETDEWEB)
Tavukcu, Emel [North Carolina State Univ., Raleigh, NC (United States)
2002-12-10
Understanding nuclear level densities and radiative strength functions is important for pure and applied nuclear physics. Recently, the Oslo Cyclotron Group has developed an experimental method to extract level densities and radiative strength functions simultaneously from the primary γ rays after a light-ion reaction. A primary γ-ray spectrum represents the γ-decay probability distribution. The Oslo method is based on the Axel-Brink hypothesis, according to which the primary γ-ray spectrum is proportional to the product of the level density at the final energy and the radiative strength function. The level density and the radiative strength function are fit to the experimental primary γ-ray spectra, and then normalized to known data. The method works well for heavy nuclei. The present measurements extend the Oslo method to the lighter mass nuclei ^{56}Fe and ^{57}Fe. The experimental level densities in ^{56}Fe and ^{57}Fe reveal step structure. This step structure is a signature for nucleon pair breaking. The predicted pairing gap parameter is in good agreement with the step corresponding to the first pair breaking. Thermodynamic quantities for ^{56}Fe and ^{57}Fe are derived within the microcanonical and canonical ensembles using the experimental level densities. Energy-temperature relations are considered using caloric curves and probability density functions. The differences between the thermodynamics of small and large systems are emphasized. The experimental heat capacities are compared with the recent theoretical calculations obtained in the Shell Model Monte Carlo method. Radiative strength functions in ^{56}Fe and ^{57}Fe have surprisingly high values at low γ-ray energies. This behavior has not been observed for heavy nuclei, but has been observed in other light- and medium-mass nuclei. The origin of this low γ-ray energy effect remains unknown.
The Spectrum Sequences of Periodic Frame Multiresolution Analysis
Institute of Scientific and Technical Information of China (English)
Yun Zhang LI; Qiao Fang LIAN
2009-01-01
The periodic multiresolution analysis (PMRA) and the periodic frame multiresolution analysis (PFMRA) provide a general recipe for the construction of periodic wavelets and periodic wavelet frames,respectively. This paper addresses PFMRAs by the introduction of the notion of spec-trum sequence. In terms of spectrum sequences,the scaling function sequences generating a normalized PFMRA are characterized; a characterization of the spectrum sequences of PFMRAs is obtained,which provides a method to construct PFMRAs since its proof is constructive; a necessary and sufficient con-dition for a PFMRA to admit a single wavelet frame sequence is obtained; a necessary and sufficient condition for a PFMRA to be contained in a given PMRA is also obtained. What is more,it is proved that an arbitrary PFMRA must be contained in some PMRA. In the meanwhile,some examples are provided to illustrate the general theory.
On the Spectral Index-Flux Density Relation for Large Samples of Radio Sources
Institute of Scientific and Technical Information of China (English)
Xi-Zhen Zhang; W. Reich; P. Reich; R. Wielebinski
2003-01-01
We present new statistical results on the spectral index-flux densityrelation for large samples of radio sources using archival data of the most sensitivesurveys, such as 6C, Miyun, WENSS, B3, NVSS, GB87. Instrumental selectioneffects and the completeness of the catalogs are discussed. Based on the spec-tral indices calculated for about 200 000 sources from the WENSS (327 MHz) andNVSS (1.4 GHz) catalogs, we obtained (1) The median spectral index increases fromαmed ～ -0.9 to αmed ～ -0.8 (Sν∝να), while S327 flux densities decrease from0.1 Jy down to 25 mJy. The median spectral indices nearly show no variation withinthe error bars when the flux density is larger than 0.1 Jy. (2) A dependence of thefraction of ultra-steep spectrum sources (USS, -1.5 ≤α＜-1.0), steep spectrumsources (SSS, -1.0 ≤α＜ -0.5) and flat spectrum sources (FSS, -0.5 ≤α≤ 0.0) ispartly responsible for the spectral flattening. Another contribution to the spectralflattening comes from the variation of αmed of steep spectrum sources (α＜-0.5)themselves which increases with decreasing flux densities. (3) The spectral flatteningfor faint sources (down to S327 ～ 20 mJy) with steep spectra (α＜-0.5) suggeststhat αmed is correlated with luminosity rather than redshift according to the Con-don' model. (4) A strong spectral selection effect occurs when spectral indices arecalculated from samples with a large frequency separation.
Design and Environment, 1972
1972-01-01
Three-part report pinpointing problems and uncovering solutions for the dual concepts of density (ratio of people to space) and crowding (psychological response to density). Section one, A Primer on Crowding,'' reviews new psychological and social findings; section two, Density in the Suburbs,'' shows conflict between status quo and increased…
Possible effect of subsurface inhomogeneities on the lunar microwave spectrum
Fisher, A. D.; Staelin, D. H.
1977-01-01
Inhomogeneities beneath the lunar surface could alter the average microwave emission spectrum of the moon in a fashion generally consistent with observations, even in the absence of an average heat flux or density gradients with depth. The lunar subsurface was modeled as an inhomogeneous lossy dielectric with three-dimensional refractive-index fluctuations characterized by independent horizontal and vertical correlation lengths. The model suggests that attempts to infer the physical properties of the moon from the lunar microwave spectrum could be significantly inaccurate if subsurface scattering were neglected.
The Effect of Curvaton Decay on the Primordial Power Spectrum
Firouzjahi, Hassan; Malik, Karim; Zarei, Moslem
2012-01-01
We study the effect of curvaton decay on the primordial power spectrum. Using analytical approximations and also numerical calculations, we find that the power spectrum is enhanced during the radiation dominated era after the curvaton decay. The amplitude of the Bardeen potential is controlled by the fraction of the energy density in the curvaton at the time of curvaton decay. We show that the enhancement in the amplitude of the primordial curvature perturbation is, however, not large enough to lead to primordial black hole overproduction on scales which re-enter the horizon after the time of curvaton decay.
Dolby, C E; Gull, S F; Dolby, Carl E.; Goodsell, Mark D.; Gull, Stephen F.
2003-01-01
A coordinate system is constructed for a general accelerating observer in 1+1 dimensions, and is used to determine the particle density of the massless Dirac vacuum for that observer. Equations are obtained for the spatial distribution and frequency distribution of massless fermions seen by this observer, in terms of the rapidity function of the observer's worldline. Examples that are considered include the uniformly accelerating observer as a limiting case, but do not always involve particle horizons. Only the low frequency limit depends on the possible presence of particle horizons. The rest of the spectrum is `almost thermal' whenever the observer's acceleration is `almost uniform'.
Structure and phonon spectrum of a submonolayer Ni film on the surface of Cu(100)
Rusina, G. G.; Borisova, S. D.; Chulkov, E. V.
2016-02-01
The equilibrium atomic structure and the phonon spectra of a submonolayer (θ = 0.5 monolayer) Ni film deposited on the surface of Cu(100) are calculated using the potentials obtained by the embedded atom method. We consider atomic relaxation, the vibrational state density distribution on Ni and substrate atoms, and polarization of vibrational modes. Variation of the phonon spectrum upon segregation of Cu atoms on the film surface is considered. It is shown that mixing of vibrations of Ni adatoms with vibrations of substrate atoms occurs in the entire frequency range, leading to a frequency shift of the vibrational modes of the substrate and to the occurrence of new vibrational states atypical of a clean surface. The Cu(100)- c(2 × 2)-Ni structure is dynamically stabler when placed in the subsurface layer of the substrate.
The power spectrum and bispectrum of SDSS DR11 BOSS galaxies II: cosmological interpretation
Gil-Marín, Héctor; Noreña, Jorge; Cuesta, Antonio J; Samushia, Lado; Percival, Will J; Wagner, Christian; Manera, Marc; Schneider, Donald P
2014-01-01
We examine the cosmological implications of the measurements of the linear growth rate of cosmological structure obtained in a companion paper from the power spectrum and bispectrum monopoles of the Sloan Digital Sky Survey III Baryon Oscillation Spectroscopic Survey Data, Release 11, CMASS galaxies. This measurement was of $f^{0.43}\\sigma_8$, where $\\sigma_8$ is the amplitude of dark matter density fluctuations, and $f$ is the linear growth rate, at the effective redshift of the survey, $z_{\\rm eff}=0.57$. In conjunction with Cosmic Microwave Background (CMB) data, interesting constraints can be placed on models with non-standard neutrino properties and models where gravity deviates from general relativity on cosmological scales. In particular, the sum of the masses of the three species of the neutrinos is constrained to $m_\
Farrell, Justin; Havens, Timothy C.; Ho, K. C.; Keller, James M.; Ton, Tuan T.; Wong, David C.; Soumekh, Mehrdad
2011-06-01
Buried explosives have proven to be a challenging problem for which ground penetrating radar (GPR) has shown to be effective. This paper discusses an explosive hazard detection algorithm for forward looking GPR (FLGPR). The proposed algorithm uses the fast Fourier transform (FFT) to obtain spectral features of anomalies in the FLGPR imagery. Results show that the spectral characteristics of explosive hazards differ from that of background clutter and are useful for rejecting false alarms (FAs). A genetic algorithm (GA) is developed in order to select a subset of spectral features to produce a more generalized classifier. Furthermore, a GA-based K-Nearest Neighbor probability density estimator is employed in which targets and false alarms are used as training data to produce a two-class classifier. The experimental results of this paper use data collected by the US Army and show the effectiveness of spectrum based features in the detection of explosive hazards.
SPECTRUM SENSING IN COGNITIVE RADIO NETWORKS: QOS CONSIDERATIONS
Directory of Open Access Journals (Sweden)
Nabil Giweli
2015-12-01
Full Text Available The rapidly growing number of wireless communication devices has led to massive increases in radio traffic density, resulting in a noticeable shortage of available spectrum. To address this shortage, the Cognitive Radio (CR technology offers promising solutions that aim to improve the spectrum utilization. The operation of CR relies on detecting the so-called spectrum holes, the frequency bands that remain unoccupied by their licensed operators. The unlicensed users are then allowed to communicate using these spectrum holes. As such, the performance of CR is highly dependent on the employed spectrum sensing methods. Several sensing methods are already available. However, no individual method can accommodate all potential CR operation scenarios. Hence, it is fair to ascertain that the performance of a CR device can be improved if it is capable of supporting several sensing methods. It should obviously also be able to select the most suitable method. In this paper, several spectrum sensing methods are compared and analyzed, aiming to identify their advantages and shortcomings in different CR operating conditions. Furthermore, it identifies the features that need to be considered while selecting a suitable sensing method from the catalog of available methods.
Negativity spectrum of one-dimensional conformal field theories
Ruggiero, Paola; Calabrese, Pasquale
2016-01-01
The partial transpose $\\rho_A^{T_2}$ of the reduced density matrix $\\rho_A$ is the key object to quantify the entanglement in mixed states, in particular through the presence of negative eigenvalues in its spectrum. Here we derive analytically the distribution of the eigenvalues of $\\rho_A^{T_2}$, that we dub negativity spectrum, in the ground sate of gapless one-dimensional systems described by a Conformal Field Theory (CFT), focusing on the case of two adjacent intervals. We show that the negativity spectrum is universal and depends only on the central charge of the CFT, similarly to the entanglement spectrum. The precise form of the negativity spectrum depends on whether the two intervals are in a pure or mixed state, and in both cases, a dependence on the sign of the eigenvalues is found. This dependence is weak for bulk eigenvalues, whereas it is strong at the spectrum edges. We also investigate the scaling of the smallest (negative) and largest (positive) eigenvalues of $\\rho_A^{T_2}$. We check our resu...
True CMB Power Spectrum Estimation
Paykari, P; Fadili, M J
2012-01-01
The cosmic microwave background (CMB) power spectrum is a powerful cosmological probe as it entails almost all the statistical information of the CMB perturbations. Having access to only one sky, the CMB power spectrum measured by our experiments is only a realization of the true underlying angular power spectrum. In this paper we aim to recover the true underlying CMB power spectrum from the one realization that we have without a need to know the cosmological parameters. The sparsity of the CMB power spectrum is first investigated in two dictionaries; Discrete Cosine Transform (DCT) and Wavelet Transform (WT). The CMB power spectrum can be recovered with only a few percentage of the coefficients in both of these dictionaries and hence is very compressible in these dictionaries. We study the performance of these dictionaries in smoothing a set of simulated power spectra. Based on this, we develop a technique that estimates the true underlying CMB power spectrum from data, i.e. without a need to know the cosmo...
The Phase Coherence of Interstellar Density Fluctuations
Burkhart, Blakesley
2015-01-01
Studies of MHD turbulence often investigate the Fourier power spectrum to provide information on the nature of the turbulence cascade. However, the Fourier power spectrum only contains the Fourier amplitudes and rejects all information regarding the Fourier phases. Here we investigate the utility of two statistical diagnostics for recovering information on Fourier phases in ISM density data: the averaged amplitudes of the bispectrum and the phase coherence index (PCI), a new phase technique for the ISM. We create 3D density and 2D column density maps using a set of simulations of isothermal ideal MHD turbulence with a wide range of sonic and Alfv\\'enic Mach numbers. We find that the bispectrum averaged along different angles with respect to either the $k_1$ or $k_2$ axis is primarily sensitive to the sonic Mach number while averaging the bispectral amplitudes over different annuli is sensitive to both the sonic and Alfv\\'enic Mach numbers. The PCI of density suggests that the most correlated phases occur in s...
A natural origin of primordial density perturbations
Lieu, Richard
2009-01-01
We suggest here a mechanism for the seeding of the primordial density fluctuations. We point out that a process like reheating at the end of inflation will inevitably generate perturbations, even on superhorizon scales, by the local diffusion of energy. Provided that the reheating temperature is of order the GUT scale, the density contrast $\\delta_R$ for spheres of radius $R$ will be of order $10^{-5}$ at horizon entry, consistent with the values measured by \\texttt{WMAP}. If this were a purely classical process, $\\delta_R^2$ would fall as $1/R^4$ beyond the horizon, and the resulting primordial density power spectrum would be $P(k) \\propto k^n$ with $n=4$. However, as shown by Gabrielli et al, a quantum diffusion process can generate a power spectrum with any index in the range $01$). Thus, the two characteristic parameters that determine the appearance of present day structures could be natural consequences of this mechanism. These are in any case the minimum density variations that must have formed if the ...
Borde, Arnaud; Palanque-Delabrouille, Nathalie; Rossi, Graziano; Viel, Matteo; Bolton, James S.; Yèche, Christophe; LeGoff, Jean-Marc; Rich, Jim
2014-07-01
Current experiments are providing measurements of the flux power spectrum from the Lyman-α forests observed in quasar spectra with unprecedented accuracy. Their interpretation in terms of cosmological constraints requires specific simulations of at least equivalent precision. In this paper, we present a suite of cosmological N-body simulations with cold dark matter and baryons, specifically aiming at modeling the low-density regions of the inter-galactic medium as probed by the Lyman-α forests at high redshift. The simulations were run using the GADGET-3 code and were designed to match the requirements imposed by the quality of the current SDSS-III/BOSS or forthcoming SDSS-IV/eBOSS data. They are made using either 2 × 7683 simeq 1 billion or 2 × 1923 simeq 14 million particles, spanning volumes ranging from (25 Mpc h-1)3 for high-resolution simulations to (100 Mpc h-1)3 for large-volume ones. Using a splicing technique, the resolution is further enhanced to reach the equivalent of simulations with 2 × 30723 simeq 58 billion particles in a (100 Mpc h-1)3 box size, i.e. a mean mass per gas particle of 1.2 × 105Msolar h-1. We show that the resulting power spectrum is accurate at the 2% level over the full range from a few Mpc to several tens of Mpc. We explore the effect on the one-dimensional transmitted-flux power spectrum of four cosmological parameters (ns, σ8, Ωm and H0) and two astrophysical parameters (T0 and γ) that are related to the heating rate of the intergalactic medium. By varying the input parameters around a central model chosen to be in agreement with the latest Planck results, we built a grid of simulations that allows the study of the impact on the flux power spectrum of these six relevant parameters. We improve upon previous studies by not only measuring the effect of each parameter individually, but also probing the impact of the simultaneous variation of each pair of parameters. We thus provide a full second-order expansion, including
de Lasson, Jakob Rosenkrantz; Kristensen, Philip Trøst; Mørk, Jesper; Gregersen, Niels
2015-12-15
We present and validate a semianalytical quasi-normal mode (QNM) theory for the local density of states (LDOS) in coupled photonic crystal (PhC) cavity-waveguide structures. By means of an expansion of the Green's function on one or a few QNMs, a closed-form expression for the LDOS is obtained, and for two types of two-dimensional PhCs, with one and two cavities side-coupled to an extended waveguide, the theory is validated against numerically exact computations. For the single cavity, a slightly asymmetric spectrum is found, which the QNM theory reproduces, and for two cavities, a nontrivial spectrum with a peak and a dip is found, which is reproduced only when including both the two relevant QNMs in the theory. In both cases, we find relative errors below 1% in the bandwidth of interest.
Generating random density matrices
Zyczkowski, Karol; Nechita, Ion; Collins, Benoit
2010-01-01
We study various methods to generate ensembles of quantum density matrices of a fixed size N and analyze the corresponding probability distributions P(x), where x denotes the rescaled eigenvalue, x=N\\lambda. Taking a random pure state of a two-partite system and performing the partial trace over one subsystem one obtains a mixed state represented by a Wishart--like matrix W=GG^{\\dagger}, distributed according to the induced measure and characterized asymptotically, as N -> \\infty, by the Marchenko-Pastur distribution. Superposition of k random maximally entangled states leads to another family of explicitly derived distributions, describing singular values of the sum of k independent random unitaries. Taking a larger system composed of 2s particles, constructing $s$ random bi-partite states, performing the measurement into a product of s-1 maximally entangled states and performing the partial trace over the remaining subsystem we arrive at a random state characterized by the Fuss-Catalan distribution of order...
Fundamentals of spread spectrum modulation
Ziemer, Rodger E
2007-01-01
This lecture covers the fundamentals of spread spectrum modulation, which can be defined as any modulation technique that requires a transmission bandwidth much greater than the modulating signal bandwidth, independently of the bandwidth of the modulating signal. After reviewing basic digital modulation techniques, the principal forms of spread spectrum modulation are described. One of the most important components of a spread spectrum system is the spreading code, and several types and their characteristics are described. The most essential operation required at the receiver in a spread spect
Broad-spectrum antiviral agents
Directory of Open Access Journals (Sweden)
Jun-Da eZhu
2015-05-01
Full Text Available Development of highly effective, broad-spectrum antiviral agents is the major objective shared by the fields of virology and pharmaceutics. Antiviral drug development has focused on targeting viral entry and replication, as well as modulating cellular defense system. High throughput screening of molecules, genetic engineering of peptides, and functional screening of agents have identified promising candidates for development of optimal broad-spectrum antiviral agents to intervene in viral infection and control viral epidemics. This review discusses current knowledge, prospective applications, opportunities, and challenges in the development of broad-spectrum antiviral agents.
Spectral Reconstruction for Obtaining Virtual Hyperspectral Images
Perez, G. J. P.; Castro, E. C.
2016-12-01
Hyperspectral sensors demonstrated its capabalities in identifying materials and detecting processes in a satellite scene. However, availability of hyperspectral images are limited due to the high development cost of these sensors. Currently, most of the readily available data are from multi-spectral instruments. Spectral reconstruction is an alternative method to address the need for hyperspectral information. The spectral reconstruction technique has been shown to provide a quick and accurate detection of defects in an integrated circuit, recovers damaged parts of frescoes, and it also aids in converting a microscope into an imaging spectrometer. By using several spectral bands together with a spectral library, a spectrum acquired by a sensor can be expressed as a linear superposition of elementary signals. In this study, spectral reconstruction is used to estimate the spectra of different surfaces imaged by Landsat 8. Four atmospherically corrected surface reflectance from three visible bands (499 nm, 585 nm, 670 nm) and one near-infrared band (872 nm) of Landsat 8, and a spectral library of ground elements acquired from the United States Geological Survey (USGS) are used. The spectral library is limited to 420-1020 nm spectral range, and is interpolated at one nanometer resolution. Singular Value Decomposition (SVD) is used to calculate the basis spectra, which are then applied to reconstruct the spectrum. The spectral reconstruction is applied for test cases within the library consisting of vegetation communities. This technique was successful in reconstructing a hyperspectral signal with error of less than 12% for most of the test cases. Hence, this study demonstrated the potential of simulating information at any desired wavelength, creating a virtual hyperspectral sensor without the need for additional satellite bands.
Obtaining material identification with cosmic ray radiography
Morris, Christopher; Bacon, Jeffrey; Chen, Elliott; Lukić, Zarija; Milner, Edward; Miyadera, Haruo; Perry, John; Schwellenbach, Dave; Aberle, Derek; Dreesen, Wendi; Green, J Andrew; McDuff, George G; Nagamine, Kanetada; Sossong, Michael; Spore, Candace; Toleman, Nathan
2012-01-01
The passage of muons through matter is mostly affected by their Coulomb interactions with electrons and nuclei. The muon interactions with electrons lead to continuous energy loss and stopping of muons, while their scattering off nuclei lead to angular 'diffusion'. By measuring both the number of stopped muons and angular changes in muon trajectories we can estimate density and identify materials. Here we demonstrate the material identification using data taken at Los Alamos with the Mini Muon Tracker.
Institute of Scientific and Technical Information of China (English)
GE Huiliang; HE Zuoyong; BAO Xuemei
2001-01-01
The point power spectrum density and the wavenumber frequency spectrum density of turbulent-boundary-layer fluctuation pressure were measured in water-tunnel by use of a φ8 mm hydrophone and a 20-element array, respectively. The non-dimensional representation of measured point power spectrum coincides with the measured results by Bull M. K. et. al. in wind tunnel. The convection peak can be seen clearly in the measured wavenumber frequencyspectrum and the convection velocity can be calculated from the location of the convection peak.The response spectrum of a polyvinylidence fluoride (PVDF) hydrophone, which receiving area is 100 mm × 60 mm, was also measured. By comparing it with the response spectrum of the φ8 mm hydrophone, it is shown that the PVDF hyrdophone has a strong wavenumber filtering effect on turbulent-boundary-layer pressure fluctuation.
Amplitude of primeval fluctuations from cosmological mass density reconstructions
Seljak, Uros; Bertschinger, Edmund
1994-01-01
We use the POTENT reconstruction of the mass density field in the nearby universe to estimate the amplitude of the density fluctuation power spectrum for various cosmological models. We find that sigma(sub 8) Omega(sub m sup 0.6) = 1.3(sub -0.3 sup +0.4), almost independently of the power spectrum. This value agrees well with the Cosmic Background Explorer (COBE) normalization for the standard cold dark matter model, while alternative models predict an excessive amplitude compared with COBE. Flat, low Omega(sub m) models and tilted models with spectral index n less than 0.8 are particularly discordant.
Palladium nanoparticles obtained by mechanical milling
Energy Technology Data Exchange (ETDEWEB)
Sampedro, B.; Hernando, A. [Instituto de Magnetismo Aplicado (RENFE-UCM-CSIC), P.O. Box 155, 28230 Las Rozas, Madrid (Spain); Dpto. Fisica de Materiales, UCM, 28040 Madrid (Spain); Rojas, T.C.; Fernandez, A. [Instituto de Ciencia de Materiales de Sevilla, Centro mixto CSIC-UNIV, 41092 Sevilla (Spain)
2006-05-15
Opposed to the existing chemical methods, we have used a physical one in order to obtain palladium nanoparticles. In this work we present the HRTEM observation of Pd nanoparticles obtained by mechanical milling. These particles are around 6 nm in size. The Pd milled samples have exhaustively been structurally characterized. We have also studied its magnetic properties as a function of the milling time and magnetic measurements are according to those previously carried out by us in palladium nanoparticles obtained by chemical methods. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
Spectrum Analyzers Incorporating Tunable WGM Resonators
Savchenkov, Anatoliy; Matsko, Andrey; Strekalov, Dmitry; Maleki, Lute
2009-01-01
A photonic instrument is proposed to boost the resolution for ultraviolet/ optical/infrared spectral analysis and spectral imaging allowing the detection of narrow (0.00007-to-0.07-picometer wavelength resolution range) optical spectral signatures of chemical elements in space and planetary atmospheres. The idea underlying the proposal is to exploit the advantageous spectral characteristics of whispering-gallery-mode (WGM) resonators to obtain spectral resolutions at least three orders of magnitude greater than those of optical spectrum analyzers now in use. Such high resolutions would enable measurement of spectral features that could not be resolved by prior instruments.
The Stimulated Raman Spectrum of Cyanogen
Bermejo; Escribano; Santos
1997-11-01
The Raman spectrum of cyanogen 12C214N2 has been investigated at nearly Doppler resolution by means of the Stimulated Raman technique. The regions around the Q branches of the nu1 (2330 cm-1) and nu2 (845 cm-1) vibrations have been recorded. Besides the fundamentals, hot bands arising from v5 = 1, v5 = 2, and v4 = 1 have been observed. The spectra have been analyzed, and rotational constants for the excited states have been obtained. Computer simulations of the Raman contours have been carried out as a test of the assignments. Copyright 1997 Academic Press. Copyright 1997Academic Press
A Lattice Study of the Glueball Spectrum
Institute of Scientific and Technical Information of China (English)
LIU Chuan
2001-01-01
Glueball spectrum is studied using an improved gluonic action on asymmetric lattices in the pure SU(3)gauge theory. The smallest spatial lattice spacing is about 0.08 fm which makes the extrapolation to the continuum limit more reliable. In particular, attention is paid to the scalar glueball mass which is known to have problems in the extrapolation. Converting our lattice results to physical units using the scale set by the static quark potential,we obtain the following results for the glueball masses: MG(0++) = 1730(90) MeV for the scalar glueball mass and MG(2++) = 2400(95) MeV for the tensor glueball.
A Lattice Study of the Glueball Spectrum
Institute of Scientific and Technical Information of China (English)
LIU Chuan
2001-01-01
The glueball spectrum is studied using an improved gluonic action on asymmetric lattices in the pure SU(3) lattice gauge theory. The smallest spatial lattice spacing is about 0.08 fm which makes the extrapolation to the ontinuum limit more reliable. Converting our lattice results to physical units using the scale set by the static quark potential, we obtain the following results for the glueball masses: MG(0++) -＝ 1730(90) MeV for the scalarglueball and MG(2++) ＝ 2400(95) MeV for the tensor glueball.
AUTISM SPECTRUM DISORDERS (ASD
Directory of Open Access Journals (Sweden)
Middha Akanksha
2011-05-01
Full Text Available Autism or Autism Spectrum Disorders (ASD is a serious neurological disorder affecting communication skills, social interactions, adaptability in an individual, and also causes dramatic changes in behavioral patterns. This condition typically lasts throughout one’s lifetime and affects both, children as well as adults. Research has shown a tenfold increase in autism cases over the past decade and still rising at an alarming pace. The origins of autism are not known even to modern science. Autism exists at different levels in individuals affected by the disease and is classified into five types. Symptoms for autism are more pronounced and prevalent in children compared to adults. Though some studies attribute autism to gene abnormality, science is yet to furnish hard facts about exact autism causes. Scientists and doctors are also unanimous in their opinion that autism, as of yet, has no cure. Treatments of autism are widely available and help in alleviating the symptoms of autism which make living with the condition easier.Several factors work together in causing autism but isolation and identification of a chief cause or causes has yet to be accomplished by modern science. Some people mistakenly believe that autism is related to bad parenting, vaccinations, or malnutrition. But these misconceptions are due to improper knowledge related to the disease. Symptoms of autism usually surface within the first two years of birth in children. Autistic children usually avoid eye contact and are poor imitators of sound together with a disliking towards a change in routines as well as non adaptability to new environments. At present, there is an absence of medical tests which can diagnose autism. The diagnosis of autism is largely based on developmental history and behavioral patterns. Medicinal treatments of autism have a downside as autism patients develop resistance to certain drugs over long period of use. All types of autism demand a good plan of
Cyclostationary Beacon for Assisting Spectrum Sensing in Opportunistic Spectrum Access
Directory of Open Access Journals (Sweden)
Thomas Kaiser
2011-03-01
Full Text Available Cognitive radio is a promising solution to the problem of spectrum scarcity by means of allowing secondary radio networks access the spectrum opportunistically. One of the most important issues in cognitive radio is how to detect existing over-the-air signals reliably. Not a few literatures have reported that signals could be detected via their inherent or embedded properties. However, this approach may not be reliable and flexible enough for all kinds of signals with different modulation types. In this paper, we propose a type of multitone beacon signal carrying cyclostationary signatures, which is able to enhance the reliability and efficiency of signal detection at low cost of spectrum overhead. This beacon not only can indicate the presence or absence of user signal but also can reveal some other information helpful to opportunistic spectrum access through the information bits carried on its cyclostationary signatures. It could be applied to device/network identification, indication of spectrum allocation and spectrum rendezvous, both for primary and secondary users. Based on our previous work reported in [1], the generation and detection algorithm of the beacon signal are extended with improved spectral efficiency. Performance is discussed with both computer simulation and testbed validation.
Explicit versus implicit social cognition testing in autism spectrum disorder.
Callenmark, Björn; Kjellin, Lars; Rönnqvist, Louise; Bölte, Sven
2014-08-01
Although autism spectrum disorder is defined by reciprocal social-communication impairments, several studies have found no evidence for altered social cognition test performance. This study examined explicit (i.e. prompted) and implicit (i.e. spontaneous) variants of social cognition testing in autism spectrum disorder. A sample of 19 adolescents with autism spectrum disorder and 19 carefully matched typically developing controls completed the Dewey Story Test. 'Explicit' (multiple-choice answering format) and 'implicit' (free interview) measures of social cognition were obtained. Autism spectrum disorder participants did not differ from controls regarding explicit social cognition performance. However, the autism spectrum disorder group performed more poorly than controls on implicit social cognition performance in terms of spontaneous perspective taking and social awareness. Findings suggest that social cognition alterations in autism spectrum disorder are primarily implicit in nature and that an apparent absence of social cognition difficulties on certain tests using rather explicit testing formats does not necessarily mean social cognition typicality in autism spectrum disorder.
OPTIMIZATION OF SPECTRUM UTILIZATION IN COGNITIVE RADIO SYSTEM
Institute of Scientific and Technical Information of China (English)
Li Hongjiang; Zhu Qi
2011-01-01
In Cognitive Radio (CR) networks,CR user has to detect the spectrum channel periodically to make sure that the channel is idle during data transmission frame in order to avoid the collisions to the primary users.Hence recent research has been focused on the interference avoidance problem.Quality of Service (QoS) requirement of CR user will affect the time of data transmission in each frame.In this paper,in order to solve the interference avoidance and spectrum utilization problems without cooperation among CR users,a new scheme to obtain the optimal duration of data transmission frame is proposed to maximize the spectrum utilization and guarantee the protection to the primary users.The main advantages of our proposed scheme include the followings:(1) QoS requirement of CR user is concerned; (2) p-persistent Media Access Control (MAC) random access is used to avoid the collisions among CR users; (3) CR network system capacity is considered.We develop a Markov chain of the primary spectrum channel states and an exponential distribution of the CR user's traffic model to analyze the performance of our proposed scheme.Computer simulation shows that there is an optimal data transmission time to maximize the spectrum utilization.However,the regulatory constraint of the collision rate to the primary users has to be satisfied at the expense of spectrum utilization.And also the tradeoff between the spectrum utilization and the capacity of the CR system is taken into account.
Speech enhancement based on multitaper spectrum and psychoacoustical weighting rule
Institute of Scientific and Technical Information of China (English)
WU Hongwei; WU Zhenyang; ZHAO Li
2007-01-01
Multitaper spectrum has lower variance than the traditional periodogram. The noise spectrum and the noise to noisy signal spectrum ratio (NNSR) were estimated from the multitaper spectrum of the noisy signal; the pre-enhanced speech for calculating the noise masking threshold was obtained by the spectral amplitude subtraction method, whose gain is a function of NNSR; the final enhanced speech was obtained by suppressing the Fourier spectrum of the noisy speech with the psychoacoustical weighting rule incorporating the noise masking threshold. Because of the low variance feature of the multitaper spectrum, a modified offset formula was proposed to calculate the noise masking threshold, thus the reconstructed speech with this modification has an improvement in MBSD (Modified Bark Spectral Distortion).When a maximum limitation less than one to the psychoacoustical weighting rule is further proposed, the higher the input SNR (＞ 0 dB) is, the more improvement the segmental SNR and the overall SNR have. The informal listening tests show that there is little speech distortion for the enhanced speech processed by the proposed method, the background noise is reduced much and free of musical noise.
Energy Technology Data Exchange (ETDEWEB)
Dutta, Alo, E-mail: alo_dutta@yahoo.com [Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block-JD, Sector III, Salt Lake, Kolkata, 700106 (India); Mukhopadhyay, P.K. [Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block-JD, Sector III, Salt Lake, Kolkata, 700106 (India); Sinha, T.P. [Department of Physics, Bose Institute, 93/1 Acharya Prafulla Chandra Road, Kolkata, 700 009 (India); Shannigrahi, Santiranjan [Institute of Materials Research and Engineering, Agency for Science Technology and Research, 3 Research Link, Singapore, 117602 (Singapore); Himanshu, A.K.; Sen, Pintu; Bandyopadhyay, S.K. [Variable Energy Cyclotron Centre, 1/AF Bidhannagar, Kolkata, 700064 (India)
2016-08-15
The density functional theory (DFT) under the generalized gradient approximation (GGA) has been used to investigate the electronic structure of double perovskite oxide Sr{sub 2}SmNbO{sub 6} synthesized by the solid-state reaction technique. The Rietveld refinement of the X-ray diffraction pattern of the sample shows the monoclinic P2{sub 1}/n phase at room temperature. The X-ray photoemission spectrum (XPS) of the material is collected in the energy window of 0–1200 eV. The chemical shift of the constituent elements calculated from the core level XPS spectra is used to analyze the covalency between the O anion and Sm/Nb cations. The valence band (VB) XPS spectrum is compared with the calculated VB spectrum using partial density of states in a standard way. The Raman spectrum is employed to investigate the phonon modes of the material in the monoclinic phase. Lorentzian lines are used to fit the experimental Raman spectrum, which present 24 phonon modes corresponding to the stretching and banding of NbO{sub 6}/SmO{sub 6} octahedra and translational motion of Sr along the Sr−O bond. The discrepancy between the measured and calculated band gap values has been removed by applying modified Becke-Johnson (mBJ) potential in the DFT calculations. The experimental optical band gap obtained from the UV–visible reflectance spectrum is found to be 3.42 eV, which is well matched with the DFT calculated value of 3.2 eV, and suggests the semiconducting nature of the material. The real (ε′) and imaginary (ε″) parts of the optical dielectric constant as a function of energy along the x-, y- and z-polarization directions using mBJ potential are calculated. The collective vibrational modes of the atoms, the Born effective charge of the ions and their effect on the static dielectric constant of the material are studied using DFT. The calculated value of static dielectric constant for SSN is found to be 41.3. - Highlights: • Electronic structure and dynamical
Probability densities and Lévy densities
DEFF Research Database (Denmark)
Barndorff-Nielsen, Ole Eiler
For positive Lévy processes (i.e. subordinators) formulae are derived that express the probability density or the distribution function in terms of power series in time t. The applicability of the results to finance and to turbulence is briefly indicated.......For positive Lévy processes (i.e. subordinators) formulae are derived that express the probability density or the distribution function in terms of power series in time t. The applicability of the results to finance and to turbulence is briefly indicated....
Probability densities and Lévy densities
DEFF Research Database (Denmark)
Barndorff-Nielsen, Ole Eiler
For positive Lévy processes (i.e. subordinators) formulae are derived that express the probability density or the distribution function in terms of power series in time t. The applicability of the results to finance and to turbulence is briefly indicated.......For positive Lévy processes (i.e. subordinators) formulae are derived that express the probability density or the distribution function in terms of power series in time t. The applicability of the results to finance and to turbulence is briefly indicated....
Eulerian bias and the galaxy density field
Mann, B M; Heavens, A F; Mann, Bob; Peacock, John; Heavens, Alan
1997-01-01
We investigate the effects on cosmological clustering statistics of empirical biasing, where the galaxy distribution is a local transformation of the present-day Eulerian density field. The effects of the suppression of galaxy numbers in voids, and their enhancement in regions of high density, are considered, independently and in combination. We compare results from numerical simulations with the predictions of simple analytic models. We find that the bias is generally scale-dependent, so that the shape of the galaxy power spectrum differs from that of the underlying mass distribution. The degree of bias is always a monotonic function of scale, tending to an asymptotic value on scales where the density fluctuations are linear. The scale dependence is often rather weak, with many reasonable prescriptions giving a bias which is nearly independent of scale. We have investigated whether such an Eulerian bias can reconcile a range of theoretical power spectra with the twin requirements of fitting the galaxy power ...
Treatment of biomass to obtain ethanol
Dunson, Jr., James B.; Elander, Richard T.; Tucker, III, Melvin P.; Hennessey, Susan Marie
2011-08-16
Ethanol was produced using biocatalysts that are able to ferment sugars derived from treated biomass. Sugars were obtained by pretreating biomass under conditions of high solids and low ammonia concentration, followed by saccharification.
Obtaining breathers in nonlinear Hamiltonian lattices
Flach, S
1995-01-01
Abstract We present a numerical method for obtaining high-accuracy numerical solutions of spatially localized time-periodic excitations on a nonlinear Hamiltonian lattice. We compare these results with analytical considerations of the spatial decay. We show that nonlinear contributions have to be considered, and obtain very good agreement between the latter and the numerical results. We discuss further applications of the method and results.
Critical Heegaard surfaces obtained by amalgamation
Lee, Jung Hoon
2011-01-01
Critical surfaces are defined by Bachman as topological index 2 surfaces, generalizing incompressible surfaces and strongly irreducible surfaces. In this paper we give a condition to obtain critical Heegaard surfaces by amalgamation. As a special case, we obtain critical Heegaard surfaces by boundary stabilization. It gives critical Heegaard surfaces of non-minimal genus, for 3-manifolds which do not admit distinct Heegaard splittings (up to isotopy).
ELEMENTARY DENSITY BOUNDS FOR SELF-SIMILAR SETS AND APPLICATION
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
Falconer[1] used the relationship between upper convex density and upper spherical density to obtain elementary density bounds for s-sets at HS-almost all points of the sets. In this paper, following Falconer[1], we first provide a basic method to estimate the lower bounds of these two classes of set densities for the self-similar s-sets satisfying the open set condition (OSC), and then obtain elementary density bounds for such fractals at all of their points. In addition, we apply the main results to the famous classical fractals and get some new density bounds.
Electron energy spectrum in core-shell elliptic quantum wire
Directory of Open Access Journals (Sweden)
V.Holovatsky
2007-01-01
Full Text Available The electron energy spectrum in core-shell elliptic quantum wire and elliptic semiconductor nanotubes are investigated within the effective mass approximation. The solution of Schrodinger equation based on the Mathieu functions is obtained in elliptic coordinates. The dependencies of the electron size quantization spectrum on the size and shape of the core-shell nanowire and nanotube are calculated. It is shown that the ellipticity of a quantum wire leads to break of degeneration of quasiparticle energy spectrum. The dependences of the energy of odd and even electron states on the ratio between semiaxes are of a nonmonotonous character. The anticrosing effects are observed at the dependencies of electron energy spectrum on the transversal size of the core-shell nanowire.
SLAM, a Mathematica interface for SUSY spectrum generators
Energy Technology Data Exchange (ETDEWEB)
Marquard, Peter [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Zerf, Nikolai [Alberta Univ., Edmonton, AB (Canada). Dept. of Physics
2013-09-15
We present and publish a Mathematica package, which can be used to automatically obtain any numerical MSSM input parameter from SUSY spectrum generators, which follow the SLHA standard, like SPheno, SOFTSUSY or Suspect. The package enables a very comfortable way of numerical evaluations within the MSSM using Mathematica. It implements easy to use predefined high scale and low scale scenarios like mSUGRA or m{sub h}{sup max} and if needed enables the user to directly specify the input required by the spectrum generators. In addition it supports an automatic saving and loading of SUSY spectra to and from a SQL data base, avoiding the rerun of a spectrum generator for a known spectrum.
SLAM, a Mathematica interface for SUSY spectrum generators
Marquard, Peter
2013-01-01
We present and publish a Mathematica package, which can be used to automatically obtain any numerical MSSM input parameter from SUSY spectrum generators, which follow the SLHA standard, like Spheno, Softsusy or Suspect. The package enables a very comfortable way of numerical evaluations within the MSSM using Mathematica. It implements easy to use predefined high scale and low scale scenarios like mSUGRA or mh_max and if needed enables the user to directly specify the input required by the spectrum generators. In addition it supports an automatic saving and loading of SUSY spectra to and from a SQL data base, avoiding the rerun of a spectrum generator for a known spectrum.
High flux lithium antineutrino source with variable hard spectrum
Lyashuk, V I
2016-01-01
The high flux antineutrino source with hard antineutrino spectrum based on neutron activation of 7Li and subsequent fast beta-decay (T 1/2 = 0.84 s) of the 8Li isotope with emission of antineutrino with energy up to 13 MeV - is discussed. Creation of the intensive isotope neutrino source of hard spectrum will allow to increase the detection statistics of neutrino interaction and it is especially urgent for oscillation experiments. The scheme of the proposed neutrino source is based on the continuous transport of the created 8Li to the neutrino detector, which moved away from the place of neutron activation. Analytical expressions for lithium antineutrino flux is obtained. The discussed source will ensure to increase the cross section for reactions with deuteron from several times to tens compare to the reactor antineutrino spectrum. An another unique feature of the installation is the possibility to vary smoothly the hardness of the antineutrino spectrum.
Autism Spectrum Disorder and Fragile X Syndrome
... Just Figuring Out CGG Repeats! Donate Print PDF Autism Spectrum Disorder and Fragile X Syndrome Fragile X ... known single gene cause of ASD What Is Autism Spectrum Disorder? Read my Story Autism spectrum disorder ( ...
Autism Spectrum Disorder and Fragile X Syndrome
... only after another family member has been diagnosed. Autism Spectrum Disorder and Fragile X Syndrome Fragile X ... known single gene cause of ASD What Is Autism Spectrum Disorder? Autism spectrum disorder (ASD) is a ...
Genetics Home Reference: ataxia neuropathy spectrum
... Understand Genetics Home Health Conditions ataxia neuropathy spectrum ataxia neuropathy spectrum Enable Javascript to view the expand/ ... boxes. Download PDF Open All Close All Description Ataxia neuropathy spectrum is part of a group of ...
Longitudinal peak detected Schottky spectrum
Shaposhnikova, E
2009-01-01
The "peak detected Schottky" spectrum is a diagnostic used since the late seventies for beam observation in the SPS and now already applied to the LHC. This tool was always believed, however without proof, to give a good picture of the particle distribution in synchrotron frequencies similar to the longitudinal Schottky spectrum of unbunched beam for revolution frequencies.In this paper an analysis of this measurement technique is presented both in a general form and for the particular realisation in the SPS. In addition the limitations of the present experimental set-up are discussed together with possible improvements. The analysis shows that for an optimised experimental set-up the spectrum of the peak detected signal is very close to the synchrotron frequency distribution inside the bunch - much closer than that given by the traditional longitudinal bunched-beam Schottky spectrum.
Generation of solar spectrum by using LEDs
Lu, Pengzhi; Yang, Hua; Pei, Yanrong; Li, Jing; Xue, Bin; Wang, Junxi; Li, Jinmin
2016-09-01
Light emitting diode (LED) has been recognized as an applicable light source for indoor and outdoor lighting, city beautifying, landscape facilities, and municipal engineering etc. Conventional LED has superior characteristics such as long life time, low power consumption, high contrast, and wide viewing angle. Recently, LED with high color-rendering index and special spectral characteristics has received more and more attention. This paper is intended to report a solar spectrum simulated by multichip LED light source. The typical solar spectrum of 5500k released by CIE was simulated as a reference. Four types of LEDs with different spectral power distributions would be used in the LED light source, which included a 430nm LED, a 480nm LED, a 500nm LED and a white LED. In order to obtain better simulation results, the white LED was achieved by a 450nm LED chip with the mixture of phosphor. The phosphor combination was prepared by mixing green phosphor, yellow phosphor and red phosphor in a certain proportion. The multichip LED light source could provide a high fidelity spectral match with the typical solar spectrum of 5500k by adjusting injection current to each device. The luminous flux, CIE chromaticity coordinate x, y, CCT, and Ra were 104.7 lm, 0.3337, 0.3681, 5460K, and 88.6, respectively. Because of high color-rendering index and highly match to the solar spectrum, the multichip LED light source is a competitive candidate for applications where special spectral is required, such as colorimetric measurements, visual inspection, gemstone identification and agriculture.
Equilibrium energy spectrum of point vortex motion with remarks on ensemble choice and ergodicity
Esler, J. G.
2017-01-01
The dynamics and statistical mechanics of N chaotically evolving point vortices in the doubly periodic domain are revisited. The selection of the correct microcanonical ensemble for the system is first investigated. The numerical results of Weiss and McWilliams [Phys. Fluids A 3, 835 (1991), 10.1063/1.858014], who argued that the point vortex system with N =6 is nonergodic because of an apparent discrepancy between ensemble averages and dynamical time averages, are shown to be due to an incorrect ensemble definition. When the correct microcanonical ensemble is sampled, accounting for the vortex momentum constraint, time averages obtained from direct numerical simulation agree with ensemble averages within the sampling error of each calculation, i.e., there is no numerical evidence for nonergodicity. Further, in the N →∞ limit it is shown that the vortex momentum no longer constrains the long-time dynamics and therefore that the correct microcanonical ensemble for statistical mechanics is that associated with the entire constant energy hypersurface in phase space. Next, a recently developed technique is used to generate an explicit formula for the density of states function for the system, including for arbitrary distributions of vortex circulations. Exact formulas for the equilibrium energy spectrum, and for the probability density function of the energy in each Fourier mode, are then obtained. Results are compared with a series of direct numerical simulations with N =50 and excellent agreement is found, confirming the relevance of the results for interpretation of quantum and classical two-dimensional turbulence.
Spectrum Trading in India and 5G
DEFF Research Database (Denmark)
Tripathi, Purnendu; Prasad, Ramjee
2013-01-01
Currently radio spectrum is largely managed through Command and Control method. Public mobile services require spectrum below 3 GHz for providing cost effective services. The existing method has created artificial shortage of spectrum especially below 3 GHz. Spectrum trading is a new concept in w...... for spectrum trading and it could provide a boost to the Indian telecom sector. Further, it will also discuss spectrum issue related with 5G in the direction of millimeter waves....
SLAM, a Mathematica interface for SUSY spectrum generators
Marquard, Peter; Zerf, Nikolai
2014-03-01
We present and publish a Mathematica package, which can be used to automatically obtain any numerical MSSM input parameter from SUSY spectrum generators, which follow the SLHA standard, like SPheno, SOFTSUSY, SuSeFLAV or Suspect. The package enables a very comfortable way of numerical evaluations within the MSSM using Mathematica. It implements easy to use predefined high scale and low scale scenarios like mSUGRA or mhmax and if needed enables the user to directly specify the input required by the spectrum generators. In addition it supports an automatic saving and loading of SUSY spectra to and from a SQL data base, avoiding the rerun of a spectrum generator for a known spectrum. Catalogue identifier: AERX_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AERX_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.: 4387 No. of bytes in distributed program, including test data, etc.: 37748 Distribution format: tar.gz Programming language: Mathematica. Computer: Any computer where Mathematica version 6 or higher is running providing bash and sed. Operating system: Linux. Classification: 11.1. External routines: A SUSY spectrum generator such as SPheno, SOFTSUSY, SuSeFLAV or SUSPECT Nature of problem: Interfacing published spectrum generators for automated creation, saving and loading of SUSY particle spectra. Solution method: SLAM automatically writes/reads SLHA spectrum generator input/output and is able to save/load generated data in/from a data base. Restrictions: No general restrictions, specific restrictions are given in the manuscript. Running time: A single spectrum calculation takes much less than one second on a modern PC.
Beyond the Spectrum: Rethinking Autism
Directory of Open Access Journals (Sweden)
Heather Thomas
2017-03-01
Full Text Available The "spectrum" has become the dominant metaphor for conceptualizing autism, with fundamental consequences for notions of disability, diversity, and normality. In this article, we draw on ethnographic research with autistic communities to explore how the notion of the autism spectrum has become a focus of explicit identification, reflection, and contestation. To further this inquiry, we place these debates into conversation with earlier debates regarding another spectrum—the Kinsey Scale, a "spectrum" for conceptualizing sexual orientation that first appeared in 1948 but has been critiqued since the 1970s. How might responses to the Kinsey Scale (like the Klein Grid contribute to rethinking the autism spectrum? This is a question about the cultural and political implications of metaphors and conceptual models. It is of broad importance because the spectrum metaphor is being extended to a range of conditions beyond autism itself. Our goal is thus to build on insights from sexuality studies as well as the insights of autistic persons, advocates, and researchers who wish to forestall the naturalization of "the spectrum." In doing so, we seek to contribute to a discussion of what alternative frameworks might bring to questions of social justice, ability, and human flourishing.
Spectrum formation in superluminous supernovae (Type I)
Mazzali, P. A.; Sullivan, M.; Pian, E.; Greiner, J.; Kann, D. A.
2016-06-01
The near-maximum spectra of most superluminous supernovae (SLSNe) that are not dominated by interaction with a H-rich circum-stellar medium (SLSN-I) are characterized by a blue spectral peak and a series of absorption lines which have been identified as O II. SN 2011kl, associated with the ultra-long gamma-ray burst GRB111209A, also had a blue peak but a featureless optical/ultraviolet (UV) spectrum. Radiation transport methods are used to show that the spectra (not including SN 2007bi, which has a redder spectrum at peak, like ordinary SNe Ic) can be explained by a rather steep density distribution of the ejecta, whose composition appears to be typical of carbon-oxygen cores of massive stars which can have low metal content. If the photospheric velocity is ˜10 000-15 000 km s-1, several lines form in the UV. O II lines, however, arise from very highly excited lower levels, which require significant departures from local thermodynamic equilibrium to be populated. These SLSNe are not thought to be powered primarily by 56Ni decay. An appealing scenario is that they are energized by X-rays from the shock driven by a magnetar wind into the SN ejecta. The apparent lack of evolution of line velocity with time that characterizes SLSNe up to about maximum is another argument in favour of the magnetar scenario. The smooth UV continuum of SN 2011kl requires higher ejecta velocities (˜20 000 km s-1): line blanketing leads to an almost featureless spectrum. Helium is observed in some SLSNe after maximum. The high-ionization near-maximum implies that both He and H may be present but not observed at early times. The spectroscopic classification of SLSNe should probably reflect that of SNe Ib/c. Extensive time coverage is required for an accurate classification.
Analytic continuation average spectrum method for transport in quantum liquids
Energy Technology Data Exchange (ETDEWEB)
Kletenik-Edelman, Orly [School of Chemistry, Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978 (Israel); Rabani, Eran, E-mail: rabani@tau.ac.il [School of Chemistry, Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978 (Israel); Reichman, David R. [Department of Chemistry, Columbia University, 3000 Broadway, New York, NY 10027 (United States)
2010-05-12
Recently, we have applied the analytic continuation averaged spectrum method (ASM) to calculate collective density fluctuations in quantum liquid . Unlike the maximum entropy (MaxEnt) method, the ASM approach is capable of revealing resolved modes in the dynamic structure factor in agreement with experiments. In this work we further develop the ASM to study single-particle dynamics in quantum liquids with dynamical susceptibilities that are characterized by a smooth spectrum. Surprisingly, we find that for the power spectrum of the velocity autocorrelation function there are pronounced differences in comparison with the MaxEnt approach, even for this simple case of smooth unimodal dynamic response. We show that for liquid para-hydrogen the ASM is closer to the centroid molecular dynamics (CMD) result while for normal liquid helium it agrees better with the quantum mode coupling theory (QMCT) and with the MaxEnt approach.
Spread spectrum compressed sensing MRI using chirp radio frequency pulses
Qu, Xiaobo; Zhuang, Xiaoxing; Yan, Zhiyu; Guo, Di; Chen, Zhong
2013-01-01
Compressed sensing has shown great potential in reducing data acquisition time in magnetic resonance imaging (MRI). Recently, a spread spectrum compressed sensing MRI method modulates an image with a quadratic phase. It performs better than the conventional compressed sensing MRI with variable density sampling, since the coherence between the sensing and sparsity bases are reduced. However, spread spectrum in that method is implemented via a shim coil which limits its modulation intensity and is not convenient to operate. In this letter, we propose to apply chirp (linear frequency-swept) radio frequency pulses to easily control the spread spectrum. To accelerate the image reconstruction, an alternating direction algorithm is modified by exploiting the complex orthogonality of the quadratic phase encoding. Reconstruction on the acquired data demonstrates that more image features are preserved using the proposed approach than those of conventional CS-MRI.
Hydrodynamics of the Chiral Dirac Spectrum
Liu, Yizhuang; Zahed, Ismail
2016-01-01
We derive a hydrodynamical description of the eigenvalues of the chiral Dirac spectrum in the vacuum and in the large $N$ (volume) limit. The linearized hydrodynamics supports sound waves. The stochastic relaxation of the eigenvalues is captured by a hydrodynamical instanton configuration which follows from a pertinent form of Euler equation. The relaxation from a phase of localized eigenvalues and unbroken chiral symmetry to a phase of de-localized eigenvalues and broken chiral symmetry occurs over a time set by the speed of sound. We show that the time is $\\Delta \\tau=\\pi\\rho(0)/2\\beta N$ with $\\rho(0)$ the spectral density at zero virtuality and $\\beta=1,2,4$ for the three Dyson ensembles that characterize QCD with different quark representations in the ergodic regime.
Physicochemical characteristics of ozonated sunflower oils obtained by different procedures
Energy Technology Data Exchange (ETDEWEB)
Diaz, M. F.; Sanchez, Y.; Gomez, M.; Hernandez, F.; Veloso, M. C.; Pereira, P. A.; Mangrich, A. S.; Andrade, J. B.
2012-07-01
Two ozonation procedures for sunflower oils at different applied ozone dosages were carried out. Ozone was obtained from medicinal oxygen and from air. Peroxide, acidity, and iodine indexes, along with density, viscosity and antimicrobial activity were determined. The fatty acid compositions of the samples were analyzed using GC. The content of oxygen was determined using an elemental analysis. Electronic Paramagnetic Resonance was used to measure the organic free radicals. The reactions were achieved up to peroxide index values of 658 and 675 mmolequiv kg1 using medicinal oxygen and air for 5 and 8 hours, respectively. The samples of ozonized sunflower oil did not present organic free radicals, which is a very important issue if these oils are to be used as drugs. The ozonation reaction is more rapid with medicinal oxygen (5 hours) than with air (8 hours). Ozonized sunflower oil with oxygen as an ozone source was obtained with high potential for antimicrobial activity. (Author) 34 refs.
Obtaining material identification with cosmic ray radiography
Energy Technology Data Exchange (ETDEWEB)
Morris, C. L.; Borozdin, Konstantin; Bacon, Jeffrey; Chen, Elliott; Lukic, Zarija; Milner, Edward; Miyadera, Haruo; Perry, John [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Schwellenbach, Dave; Aberle, Derek; Dreesen, Wendi; Green, J. Andrew; McDuff, George G. [National Security Technologies, Los Alamos, NM 87544 (United States); Nagamine, Kanetada [KEK, Tsukuba, Ibaraki, 305-0801 (Japan); RIKEN, Wako, Saitama, 351-0198 (Japan) and UC-Riverside, CA 92521 (United States); Sossong, Michael [Decision Sciences, 12345 First American Way, Suite 130, Poway, CA 92064 (United States); Spore, Candace; Toleman, Nathan [Department of Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, NM 87131-0001 (United States)
2012-12-15
The passage of muons through matter is dominated by the Coulomb interaction with electrons and nuclei in the matter. The muon interaction with the electrons leads to continuous energy loss and stopping of the muons. The muon interaction with nuclei leads to angular diffusion. Using both stopped muons and angle diffusion interactions allows us to determine density and identify materials. Here we demonstrate material identification using data taken at Los Alamos with a particle tracker built from a set of sealed drift tubes with commercial electronics and software, the Mini Muon Tracker (MMT).
Obtaining material identification with cosmic ray radiography
Directory of Open Access Journals (Sweden)
C. L. Morris
2012-12-01
Full Text Available The passage of muons through matter is dominated by the Coulomb interaction with electrons and nuclei in the matter. The muon interaction with the electrons leads to continuous energy loss and stopping of the muons. The muon interaction with nuclei leads to angular diffusion. Using both stopped muons and angle diffusion interactions allows us to determine density and identify materials. Here we demonstrate material identification using data taken at Los Alamos with a particle tracker built from a set of sealed drift tubes with commercial electronics and software, the Mini Muon Tracker (MMT.
Chluba, Jens; Ben-Dayan, Ido
2012-01-01
In the early Universe, energy stored in small-scale density perturbations is quickly dissipated by Silk-damping, a process that inevitably generates mu- and y-type spectral distortions of the cosmic microwave background (CMB). These spectral distortions depend on the shape and amplitude of the primordial power spectrum at wavenumbers k < 10^4 Mpc^{-1}. Here we study constraints on the primordial power spectrum derived from COBE/FIRAS and forecasted for PIXIE. We show that measurements of mu and y impose strong bounds on the integrated small-scale power, and we demonstrate how to compute these constraints using k-space window functions that account for the effects of thermalization and dissipation physics. We show that COBE/FIRAS places a robust upper limit on the amplitude of the small-scale power spectrum. This limit is about three orders of magnitude stronger than the one derived from primordial black holes in the same scale range. Furthermore, this limit could be improved by another three orders of magn...
Kinetic Scale Density Fluctuations in the Solar Wind
Chen, C H K; Bonnell, J W; Mozer, F S; Klein, K G; Bale, S D
2013-01-01
We motivate the importance of studying kinetic scale turbulence for understanding the macroscopic properties of the heliosphere, such as the heating of the solar wind. We then discuss the technique by which kinetic scale density fluctuations can be measured using the spacecraft potential, including a calculation of the timescale for the spacecraft potential to react to the density changes. Finally, we compare the shape of the density spectrum at ion scales to theoretical predictions based on a cascade model for kinetic turbulence. We conclude that the shape of the spectrum, including the ion scale flattening, can be captured by the sum of passive density fluctuations at large scales and kinetic Alfven wave turbulence at small scales.
Spectrum formation in Superluminous Supernovae (Type I)
Mazzali, P A; Pian, E; Greiner, J; Kann, D A; ARI-LJMU,; UK,; Garching, MPA; Germany,; Southampton, Univ; INAF-IASFBO,; Italy,; Pisa, SNS; Garching, MPE; Tautenburg,; Germany),
2016-01-01
The near-maximum spectra of most superluminous supernovae that are not dominated by interaction with a H-rich CSM (SLSN-I) are characterised by a blue spectral peak and a series of absorption lines which have been identified as OII. SN2011kl, associated with the ultra-long gamma-ray burst GRB111209A, also had a blue peak but a featureless optical/UV spectrum. Radiation transport methods are used to show that the spectra (not including SN2007bi, which has a redder spectrum at peak, like ordinary SNe Ic) can be explained by a rather steep density distribution of the ejecta, whose composition appears to be typical of carbon-oxygen cores of massive stars which can have low metal content. If the photospheric velocity is ~10000-15000 km/s, several lines form in the UV. OII lines, however, arise from very highly excited lower levels, which require significant departures from Local Thermodynamic Equilibrium to be populated. These SLSNe are not thought to be powered primarily by 56Ni decay. An appealing scenario is th...
Principles of spread-spectrum communication systems
Torrieri, Don
2015-01-01
This book provides a concise but lucid explanation of the fundamentals of spread-spectrum systems with an emphasis on theoretical principles. The choice of specific topics is tempered by the author’s judgment of their practical significance and interest to both researchers and system designers. The book contains many improved derivations of the classical theory and presents the latest research results that bring the reader to the frontier of the field. This third edition includes new coverage of topics such as CDMA networks, acquisition and synchronization in DS-CDMA cellular networks, hopsets for FH-CDMA ad hoc networks, implications of information theory, the central limit theorem, the power spectral density of FH/CPM complex envelopes, adaptive filters, and adaptive arrays. · Focuses on the fundamentals of spread-spectrum communication systems and provides current examples of their applications · Includes problem sets at the end of each chapter to assist readers in co...
Population Density Modeling Tool
2014-02-05
194 POPULATION DENSITY MODELING TOOL by Davy Andrew Michael Knott David Burke 26 June 2012 Distribution...MARYLAND NAWCADPAX/TR-2012/194 26 June 2012 POPULATION DENSITY MODELING TOOL by Davy Andrew Michael Knott David Burke...Density Modeling Tool 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Davy Andrew Michael Knott David Burke 5d. PROJECT NUMBER
Visible Spectrum Incandescent Selective Emitter
Energy Technology Data Exchange (ETDEWEB)
Sonsight Inc.
2004-04-30
The purpose of the work performed was to demonstrate the feasibility of a novel bi-layer selective emitter. Selective emitters are incandescent radiant bodies with emissivities that are substantially larger in a selected part of the radiation spectrum, thereby significantly shifting their radiated spectral distribution from that of a blackbody radiating at the same temperature. The major research objectives involved answering the following questions: (1) What maximum VIS/NIR radiant power and emissivity ratios can be attained at 2650 K? (2) What is the observed emitter body life and how does its performance vary with time? (3) What are the design tradeoffs for a dual heating approach in which both an internally mounted heating coil and electrical resistance self-heating are used? (4) What are the quantitative improvements to be had from utilizing a bi-layer emitter body with a low emissivity inner layer and a partially transmissive outer layer? Two approaches to obtaining selective emissivity were investigated. The first was to utilize large optical scattering within an emitter material with a spectral optical absorption that is much greater within the visible spectrum than that within the NIR. With this approach, an optically thick emitter can radiate almost as if optically thin because essentially, scattering limits the distance below the surface from which significant amounts of internally generated radiation can emerge. The performance of thin emitters was also investigated (for optically thin emitters, spectral emissivity is proportional to spectral absorptivity). These emitters were fabricated from thin mono-layer emitter rods as well as from bi-layer rods with a thin emitter layer mounted on a substrate core. With an initially estimated energy efficiency of almost three times that of standard incandescent bulbs, a number of energy, economic and environmental benefits such as less energy use and cost, reduced CO{sub 2} emissions, and no mercury contamination
Chen, Jian; Bai, Xiaolong; Yang, Keji; Ju, Bing-Feng
2015-02-01
To meet the need of efficient, comprehensive and automatic characterization of the properties of thin layers, a nondestructive method using ultrasonic testing to simultaneously measure thickness, density, sound velocity and attenuation through V(z,t) data, recorded by time-resolved acoustic microscopy is proposed. The theoretical reflection spectrum of the thin layer at normal incidence is established as a function of three dimensionless parameters. The measured reflection spectrum R(θ,ω) is obtained from V(z,t) data and the measured thickness is derived from the signals when the lens is focused on the front and back surface of the thin layer, which are picked up from the V(z,t) data. The density, sound velocity and attenuation are then determined by the measured thickness and inverse algorithm utilizing least squares method to fit the theoretical and measured reflection spectrum at normal incidence. It has the capability of simultaneously measuring thickness, density, sound velocity and attenuation of thin layer in a single V(z,t) acquisition. An example is given for a thin plate immersed in water and the results are satisfactory. The method greatly simplifies the measurement apparatus and procedures, which improves the efficiency and automation for simultaneous measurement of basic mechanical and geometrical properties of thin layers.
Toward in Situ Measurement of the Density of Liquid Benzene Using Optical Kerr Effect Spectroscopy.
Bender, John S; Cohen, Samuel R; He, Xiaoxiao; Fourkas, John T; Coasne, Benoit
2016-09-01
The high-frequency portion of the optical Kerr effect (OKE) spectrum of benzene shifts to higher frequency with decreasing temperature at constant pressure. This behavior has been interpreted previously in terms of an increase in librational frequencies due to the decrease in free volume with liquid densification. However, decreasing temperature also provides less access to the more repulsive portion of the intermolecular potential, which would cause the blue edge of the spectrum to red-shift. To explore the relative importance of these phenomena, molecular dynamics simulations of benzene are used to isolate the effects of temperature and density on the spectrum. The simulations show that, at constant density, the high-frequency portion of the spectrum shifts to lower frequency with decreasing temperature. In contrast, at constant temperature, the high-frequency portion of the spectrum shifts to higher frequency with increasing density. These results indicate that density plays a greater role in determining the position of the blue edge of the low-frequency Raman spectrum of benzene than does temperature. Empirical fits show that the effects of changing density or temperature are similar in experimental and simulated OKE spectra. Furthermore, line-shape analysis of simulated spectra under isochoric and isothermal conditions shows that the effects of density and temperature are separable, suggesting that OKE spectroscopy is a viable technique for in situ measurement of the density of van der Waals liquids.
Obtaining Kohn–Sham potential without taking the functional derivative
Indian Academy of Sciences (India)
Manoj K Harbola; K D Sen
2003-01-01
Over the past decade and a half, many new accurate density functionals, based on the generalized gradient approximation, have been proposed, and they give energies close to chemical accuracy. However, accuracy of the energy functional does not guarantee that its functional derivative, which gives the corresponding potential, is also accurate all over space. For example, although the Becke88 exchange–energy functional gives very good exchange energies, its functional derivative goes as $-\\frac{1}{r^2}$ in comparison to the correct $-\\frac{1}{r}$ for $r \\rightarrow \\infty$, where is the distance of the electron from a finite system. On the other hand, accuracy of the potential is of prime importance if one is interested in properties other than the total energy; properties such as optical response depend crucially on the potential in the outer regions of a system. In this paper we present a different approach, based on the ideas of Harbola and Sahni, to obtain the potential directly from the energy density of a given approximation, without taking recourse to the functional derivative route. This leads to a potential that is as accurate as the functional itself. We demonstrate the accuracy of our approach by presenting some results obtained from the Becke88 functional.
Palit, Sourav; Chakrabarti, Sandip K
2015-01-01
X-rays and gamma-rays from astronomical sources such as solar flares are mostly absorbed by the Earth's atmosphere. Resulting electron-ion production rate as a function of height depends on the intensity and wavelength of the injected spectrum and therefore the effects vary from one source to another. In other words, the ion density vs. altitude profile has the imprint of the incident photon spectrum. In this paper, we investigate whether we can invert the problem uniquely by deconvolution of the VLF amplitude signal to obtain the details of the injected spectrum. We find that it is possible to do this up to a certain accuracy. Our method is useful to carry out a similar exercise to infer the spectra of more energetic events such as the Gamma Ray Bursts (GRBs), Soft Gamma Ray Repeaters (SGRs) etc. by probing even the lower part of the atmosphere. We thus show that to certain extent, the Earth's atmosphere could be used as a gigantic detector of relatively strong events.
Palit, S.; Ray, S.; Chakrabarti, S. K.
2016-05-01
X-rays and gamma-rays from astronomical sources such as solar flares are mostly absorbed by the Earth's atmosphere. Resulting electron-ion production rate as a function of height depends on the intensity and wavelength of the injected spectrum and therefore the effects vary from one source to another. In other words, the ion density vs. altitude profile has the imprint of the incident photon spectrum. In this paper, we investigate whether we can invert the problem uniquely by deconvolution of the VLF amplitude signal to obtain the details of the injected spectrum. We find that it is possible to do this up to a certain accuracy. This leads us to the possibility of uninterrupted observation of X-ray photon spectra of solar flares that are often hindered by the restricted observation window of space satellites to avoid charge particle damages. Such continuous means of observation are essential in deriving information on time evolution of physical processes related to electron acceleration and interaction with plasma in solar atmosphere. Our method is useful to carry out a similar exercise to infer the spectra of more energetic events such as the Gamma Ray Bursts (GRBs), Soft Gamma-ray Repeaters (SGRs) etc., by probing even the lower part of the Earth's atmosphere. We thus show that to certain extent, the Earth's atmosphere could be used as a gigantic detector of relatively strong astronomical events.
Cuesta, José A; Law, Richard
2016-01-01
The Sheldon spectrum describes a remarkable regularity in aquatic ecosystems: the biomass density as a function of logarithmic body mass is approximately constant over many orders of magnitude. While size-spectrum models have explained this phenomenon for assemblages of multicellular organisms, this paper introduces a species-resolved size-spectrum model to explain the phenomenon in unicellular plankton. A Sheldon spectrum spanning the cell-size range of unicellular plankton necessarily consists of a large number of coexisting species covering a wide range of characteristic sizes. The coexistence of many phytoplankton species feeding on a small number of resources is known as the Paradox of the Plankton. Our model resolves the paradox by showing that coexistence is facilitated by the allometric scaling of four physiological rates. Two of the allometries have empirical support, the remaining two emerge from predator-prey interactions exactly when the abundances follow a Sheldon spectrum. Our plankton model is ...
A new method of measuring the peculiar velocity power spectrum
Zhang, P; Juszkiewicz, R; Feldman, H A; Zhang, Pengjie; Stebbins, Albert; Juszkiewicz, Roman; Feldman, Hume
2004-01-01
We show that by directly correlating the cluster kinetic Sunyaev Zeldovich (KSZ) flux, the cluster peculiar velocity power spectrum can be measured to $\\sim 10%$ accuracy by future large sky coverage KSZ surveys. This method is almost free of systemics entangled in the usual velocity inversion method. The direct correlation brings extra information of density and velocity clustering. We utilize these information to construct two indicators of the Hubble constant and comoving angular distance and propose a novel method to constrain cosmology.
Phonon spectrum, mechanical and thermophysical properties of thorium carbide
Energy Technology Data Exchange (ETDEWEB)
Pérez Daroca, D., E-mail: pdaroca@tandar.cnea.gov.ar [Gerencia de Investigación y Aplicaciones, Comisión Nacional de Energía Atómica (Argentina); Consejo Nacional de Investigaciones Cientı´ficas y Técnicas (Argentina); Jaroszewicz, S. [Gerencia de Investigación y Aplicaciones, Comisión Nacional de Energía Atómica (Argentina); Instituto de Tecnología Jorge A. Sabato, UNSAM-CNEA (Argentina); Llois, A.M. [Gerencia de Investigación y Aplicaciones, Comisión Nacional de Energía Atómica (Argentina); Consejo Nacional de Investigaciones Cientı´ficas y Técnicas (Argentina); Mosca, H.O. [Gerencia de Investigación y Aplicaciones, Comisión Nacional de Energía Atómica (Argentina); Instituto de Tecnología Jorge A. Sabato, UNSAM-CNEA (Argentina)
2013-06-15
In this work, we study, by means of density functional perturbation theory and the pseudopotential method, mechanical and thermophysical properties of thorium carbide. These properties are derived from the lattice dynamics in the quasi-harmonic approximation. The phonon spectrum of ThC presented in this article, to the best authors’ knowledge, have not been studied, neither experimentally, nor theoretically. We compare mechanical properties, volume thermal expansion and molar specific capacities with previous results and find a very good agreement.
Phonon spectrum of single-walled boron nitride nanotubes
Institute of Scientific and Technical Information of China (English)
Xiao Yang; Yan Xiao-Hong; Cao Jue-Xian; Mao Yu-Liang; Xiang Jun
2004-01-01
Based on a force constant model, we investigated the phonon spectrum and then specific heat of single-walled boron nitride nanotubes. The results show that the frequencies of Raman and infrared active modes decrease with increasing diameter in the low frequency, which is consistent with the results calculated by density functional theory.The fitting formulae for diameter and chirality dependence of specific heat at 300K are given.
Obtaining exact value by approximate computations
Institute of Scientific and Technical Information of China (English)
Jing-zhong ZHANG; Yong FENG
2007-01-01
Numerical approximate computations can solve large and complex problems fast. They have the advantage of high efficiency. However they only give approximate results, whereas we need exact results in some fields. There is a gap between approximate computations and exact results.In this paper, we build a bridge by which exact results can be obtained by numerical approximate computations.
Obtaining the Andersen's chart, triangulation algorithm
DEFF Research Database (Denmark)
Sabaliauskas, Tomas; Ibsen, Lars Bo
Andersen’s chart (Andersen & Berre, 1999) is a graphical method of observing cyclic soil response. It allows observing soil response to various stress amplitudes that can lead to liquefaction, excess plastic deformation or stabilizing soil response. The process of obtaining the original chart has...
47 CFR 54.615 - Obtaining services.
2010-10-01
... non-profit entity that falls within one of the seven categories set forth in the definition of health... provided under § 54.621, that the requester cannot obtain toll-free access to an Internet service provider... thing of value; (6) If the service or services are being purchased as part of an aggregated purchase...