Improved Abel transform inversion: First application to COSMIC/FORMOSAT-3
NASA Astrophysics Data System (ADS)
Aragon-Angel, A.; Hernandez-Pajares, M.; Juan, J.; Sanz, J.
2007-05-01
In this paper the first results of Ionospheric Tomographic inversion are presented, using the Improved Abel Transform on the COSMIC/FORMOSAT-3 constellation of 6 LEO satellites, carrying on-board GPS receivers.[- 4mm] The Abel transform inversion is a wide used technique which in the ionospheric context makes it possible to retrieve electron densities as a function of height based of STEC (Slant Total Electron Content) data gathered from GPS receivers on board of LEO (Low Earth Orbit) satellites. Within this precise use, the classical approach of the Abel inversion is based on the assumption of spherical symmetry of the electron density in the vicinity of an occultation, meaning that the electron content varies in height but not horizontally. In particular, one implication of this assumption is that the VTEC (Vertical Total Electron Content) is a constant value for the occultation region. This assumption may not always be valid since horizontal ionospheric gradients (a very frequent feature in some ionosphere problematic areas such as the Equatorial region) could significantly affect the electron profiles. [- 4mm] In order to overcome this limitation/problem of the classical Abel inversion, a studied improvement of this technique can be obtained by assuming separability in the electron density (see Hernández-Pajares et al. 2000). This means that the electron density can be expressed by the multiplication of VTEC data and a shape function which assumes all the height dependency in it while the VTEC data keeps the horizontal dependency. Actually, it is more realistic to assume that this shape fuction depends only on the height and to use VTEC information to take into account the horizontal variation rather than considering spherical symmetry in the electron density function as it has been carried out in the classical approach of the Abel inversion.[-4mm] Since the above mentioned improved Abel inversion technique has already been tested and proven to be a useful
Abel inversion method for cometary atmospheres.
NASA Astrophysics Data System (ADS)
Hubert, Benoit; Opitom, Cyrielle; Hutsemekers, Damien; Jehin, Emmanuel; Munhoven, Guy; Manfroid, Jean; Bisikalo, Dmitry V.; Shematovich, Valery I.
2016-04-01
Remote observation of cometary atmospheres produces a measurement of the cometary emissions integrated along the line of sight joining the observing instrument and the gas of the coma. This integration is the so-called Abel transform of the local emission rate. We develop a method specifically adapted to the inversion of the Abel transform of cometary emissions, that retrieves the radial profile of the emission rate of any unabsorbed emission, under the hypothesis of spherical symmetry of the coma. The method uses weighted least squares fitting and analytical results. A Tikhonov regularization technique is applied to reduce the possible effects of noise and ill-conditioning, and standard error propagation techniques are implemented. Several theoretical tests of the inversion techniques are carried out to show its validity and robustness, and show that the method is only weakly dependent on any constant offset added to the data, which reduces the dependence of the retrieved emission rate on the background subtraction. We apply the method to observations of three different comets observed using the TRAPPIST instrument: 103P/ Hartley 2, F6/ Lemmon and A1/ Siding spring. We show that the method retrieves realistic emission rates, and that characteristic lengths and production rates can be derived from the emission rate for both CN and C2 molecules. We show that the emission rate derived from the observed flux of CN emission at 387 nm and from the C2 emission at 514.1 nm of comet Siding Spring both present an easily-identifiable shoulder that corresponds to the separation between pre- and post-outburst gas. As a general result, we show that diagnosing properties and features of the coma using the emission rate is easier than directly using the observed flux. We also determine the parameters of a Haser model fitting the inverted data and fitting the line-of-sight integrated observation, for which we provide the exact analytical expression of the line-of-sight integration
The Filtered Abel Transform and Its Application in Combustion Diagnostics
NASA Technical Reports Server (NTRS)
Simons, Stephen N. (Technical Monitor); Yuan, Zeng-Guang
2003-01-01
Many non-intrusive combustion diagnosis methods generate line-of-sight projections of a flame field. To reconstruct the spatial field of the measured properties, these projections need to be deconvoluted. When the spatial field is axisymmetric, commonly used deconvolution method include the Abel transforms, the onion peeling method and the two-dimensional Fourier transform method and its derivatives such as the filtered back projection methods. This paper proposes a new approach for performing the Abel transform method is developed, which possesses the exactness of the Abel transform and the flexibility of incorporating various filters in the reconstruction process. The Abel transform is an exact method and the simplest among these commonly used methods. It is evinced in this paper that all the exact reconstruction methods for axisymmetric distributions must be equivalent to the Abel transform because of its uniqueness and exactness. Detailed proof is presented to show that the two dimensional Fourier methods when applied to axisymmetric cases is identical to the Abel transform. Discrepancies among various reconstruction method stem from the different approximations made to perform numerical calculations. An equation relating the spectrum of a set of projection date to that of the corresponding spatial distribution is obtained, which shows that the spectrum of the projection is equal to the Abel transform of the spectrum of the corresponding spatial distribution. From the equation, if either the projection or the distribution is bandwidth limited, the other is also bandwidth limited, and both have the same bandwidth. If the two are not bandwidth limited, the Abel transform has a bias against low wave number components in most practical cases. This explains why the Abel transform and all exact deconvolution methods are sensitive to high wave number noises. The filtered Abel transform is based on the fact that the Abel transform of filtered projection data is equal
NASA Astrophysics Data System (ADS)
Gladwin Pradeep, R.; Chandrasekar, V. K.; Mohanasubha, R.; Senthilvelan, M.; Lakshmanan, M.
2016-07-01
We identify contact transformations which linearize the given equations in the Riccati and Abel chains of nonlinear scalar and coupled ordinary differential equations to the same order. The identified contact transformations are not of Cole-Hopf type and are new to the literature. The linearization of Abel chain of equations is also demonstrated explicitly for the first time. The contact transformations can be utilized to derive dynamical symmetries of the associated nonlinear ODEs. The wider applicability of identifying this type of contact transformations and the method of deriving dynamical symmetries by using them is illustrated through two dimensional generalizations of the Riccati and Abel chains as well.
Fast algorithm for computing the Abel inversion integral in broadband reflectometry
Nunes, F.D.
1995-10-01
The application of the Hansen--Jablokow recursive technique is proposed for the numerical computation of the Abel inversion integral which is used in ({ital O}-mode) frequency-modulated broadband reflectometry to evaluate plasma density profiles. Compared to the usual numerical methods the recursive algorithm allows substantial time savings that can be important when processing massive amounts of data aiming to control the plasma in real time. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.
A new asymmetric Abel-inversion method for plasma interferometry in tokamaks
Park, H.K.
1989-02-01
In order to get precise local electron density information from chordal interferometric measurement of a tokamak plasma, a self- consistent and reliable inversion method is necessary. In this paper, a new asymmetric Abel-inversion method is introduced. This method includes flexible boundary conditions, application to a non-circular geometry, and estimation of the plasma in the scrape-off layer. The advantages of this method are demonstrated by comparison with other methods. This new inversion method is applied to a parametric study which includes dependence on the Shafranov shift and elongation of the profile. The inverted results are integrated along different views and compared with other density measurements. This new method can also be applied to plasma spectroscopy. 6 refs., 6 figs.
A generalized Abel inversion method for gamma-ray imaging of thermonuclear plasmas
NASA Astrophysics Data System (ADS)
Nocente, M.; Pavone, A.; Tardocchi, M.; Goloborod'ko, V.; Schoepf, K.; Yavorskij, V.
2016-03-01
A method to determine the gamma-ray emissivity profile from measurements along a few multiple collimated lines of sight in thermonuclear plasmas is presented. The algorithm is based on a generalisation of the known Abel inversion and takes into account the non circular shape of the plasma flux surfaces and the limited number of data points available. The method is applied to synthetic experimental measurements originating from parabolic and non parabolic JET gamma-ray emissivity profiles, where the aim is to compare the results of the inversion with the original, known input parameters. We find that profile parameters, such as the peak value, width and centre of the emissivity, are determined with an accuracy between 1 and 20% for parabolic and 2 to 25% for non parabolic profiles, respectively, which compare to an error at the 10% level for the input data. The results presented in this paper are primarily of relevance for the reconstruction of emissivity profiles from radiation measurements in tokamaks, but the method can also be applied to measurements along a sparse set of collimated lines of sight in general applications, provided that the surfaces at constant emissivity are known to have rotational simmetry.
Mechanisms for Galaxy Transformation in the Complex Environment of SuperGroup Abell 1882
NASA Astrophysics Data System (ADS)
Sengupta, Aparajita; Keel, W. C.; Morrison, G. E.; Windhorst, R. A.; Smith, B.
2013-01-01
We present our results from a multi-wavelength study of galaxy transformations in the outskirts of SuperGroup Abell 1882, a highly filamentary and clumpy structure caught in the early stages of coalescing into a Coma-like cluster. Our data have been drawn from MMT, GMOS, WIYN, SDSS, SARA, CFHT, GALEX, Spitzer and Chandra. Clusters grow by accretion through filaments, and these accreted galaxies undergo transformations due to environmental effects. Radial locations of these transformations in cluster outskirts can be mapped to a time sequence. In relaxed clusters, several evolutionary mechanisms take effect on similar spatial and temporal scales, thus making it almost impossible to disentangle different local and global mechanisms. A SuperGroup, on the other hand, has shallower Dark Matter potential. Here, the accreting galaxies are subjected to evolutionary mechanisms over larger time and spatial scales. This separates processes that are otherwise superimposed in rich cluster-filament interfaces. We have studied transformations in Specific Star Formation Rate, birth rate parameter, color and morphological properties of 342 spectroscopically confirmed member galaxies of Abell 1882, as they make their journey through the feeding filaments into the high density core of the structure, as a function of their local galaxy density and structure-centric distance. Our results show that significant transformations in galaxies begin to occur much before the galaxies reach the X-ray gas environments of the dense groups. This indicates that ram pressure stripping is unlikely driver of early galaxy transformations in proto-clusters.
Inversion and approximation of Laplace transforms
NASA Technical Reports Server (NTRS)
Lear, W. M.
1980-01-01
A method of inverting Laplace transforms by using a set of orthonormal functions is reported. As a byproduct of the inversion, approximation of complicated Laplace transforms by a transform with a series of simple poles along the left half plane real axis is shown. The inversion and approximation process is simple enough to be put on a programmable hand calculator.
Mass dependent galaxy transformation mechanisms in the complex environment of SuperGroup Abell 1882
NASA Astrophysics Data System (ADS)
Sengupta, Aparajita
We present our data and results from panchromatic photometry and optical spectrometry of the nearest (extremely rich) filamentary large scale structure, SuperGroup Abell 1882. It is a precursor of a cluster and is an inevitable part of the narrative in the study of galaxy transformations. There has been strong empirical evidence over the past three decades that galaxy environment affects galaxy properties. Blue disky galaxies transform into red bulge-like galaxies as they traverse into the deeper recesses of a cluster. However, we have little insight into the story of galaxy evolution in the early stages of cluster formation. Besides, in relaxed clusters that have been studied extensively, several evolutionary mechanisms take effect on similar spatial and temporal scales, making it almost impossible to disentangle different local and global mechanisms. A SuperGroup on the other hand, has a shallower dark-matter potential. Here, the accreting galaxies are subjected to evolutionary mechanisms over larger time and spatial scales. This separates processes that are otherwise superimposed in rich cluster-filament interfaces. As has been found from cluster studies, galaxy color and morphology tie very strongly with local galaxy density even in a complex and nascent structure like Abell 1882. Our major results indicate that there is a strong dependence of galaxy transformations on the galaxy masses themselves. Mass- dependent evolutionary mechanisms affect galaxies at different spatial scales. The galaxy color also varies with radial projected distance from the assumed center of the structure for a constant local galaxy density, indicating the underlying large scale structure as a second order evolutionary driver. We have looked for clues to the types of mechanisms that might cause the transformations at various mass regimes. We have found the thoroughly quenched low mass galaxies confined to the groups, whereas there are evidences of intermediate-mass quenched galaxies
NASA Astrophysics Data System (ADS)
Huestis, D. L.
Forward integration calculation of air mass, refraction, and time delay requires care even for very smooth model atmospheres. The literature abounds in examples of injudicious approximations, assumptions, transformations, variable substitutions, and failures to verify that the formulas work with unlimited accuracy for simple cases and also survive challenges from mathematically pathological but physically realizable cases. A few years ago we addressed the problem of evaluation of the Chapman function for attenuation along a straight line path in an exponential atmosphere. In this presentation we will describe issues and approaches for integration over light paths curved by refraction. The inverse problem, determining the altitude profile of mass density (index of refraction) or the concentration of an individual chemical species (absorption), from occultation data, also has its mathematically interesting (i.e., difficult) aspects. Now we automatically have noise and thus statistical analysis is just as important as calculus and numerical analysis. Here we will describe a new approach of least-squares fitting occultation data to an expansion over compact basis functions. This approach, which avoids numerical differentiation and singular integrals, was originally developed to analyze laboratory imaging data.Forward integration calculation of air mass, refraction, and time delay requires care even for very smooth model atmospheres. The literature abounds in examples of injudicious approximations, assumptions, transformations, variable substitutions, and failures to verify that the formulas work with unlimited accuracy for simple cases and also survive challenges from mathematically pathological but physically realizable cases. A few years ago we addressed the problem of evaluation of the Chapman function for attenuation along a straight line path in an exponential atmosphere. In this presentation we will describe issues and approaches for integration over light paths
An approximation for inverse Laplace transforms
NASA Technical Reports Server (NTRS)
Lear, W. M.
1981-01-01
Programmable calculator runs simple finite-series approximation for Laplace transform inversions. Utilizing family of orthonormal functions, approximation is used for wide range of transforms, including those encountered in feedback control problems. Method works well as long as F(t) decays to zero as it approaches infinity and so is appliable to most physical systems.
An efficient and flexible Abel-inversion method for noisy data
NASA Astrophysics Data System (ADS)
Antokhin, Igor I.
2016-08-01
We propose an efficient and flexible method for solving Abel integral equation of the first kind, frequently appearing in many fields of astrophysics, physics, chemistry, and applied sciences. This equation represents an ill-posed problem, thus solving it requires some kind of regularization. Our method is based on solving the equation on a so-called compact set of functions and/or using Tikhonov's regularization. A priori constraints on the unknown function, defining a compact set, are very loose and can be set using simple physical considerations. Tikhonov's regularization on itself does not require any explicit a priori constraints on the unknown function and can be used independently of such constraints or in combination with them. Various target degrees of smoothness of the unknown function may be set, as required by the problem at hand. The advantage of the method, apart from its flexibility, is that it gives uniform convergence of the approximate solution to the exact solution, as the errors of input data tend to zero. The method is illustrated on several simulated models with known solutions. An example of astrophysical application of the method is also given.
Some inversion formulas for the cone transform
NASA Astrophysics Data System (ADS)
Terzioglu, Fatma
2015-11-01
Several novel imaging applications have lead recently to a variety of Radon type transforms, where integration is made over a family of conical surfaces. We call them cone transforms (in 2D they are also called V-line or broken ray transforms). Most prominently, they are present in the so called Compton camera imaging that arises in medical diagnostics, astronomy, and lately in homeland security applications. Several specific incarnations of the cone transform have been considered separately. In this paper, we address the most general (and overdetermined) cone transform, obtain integral relations between cone and Radon transforms in {{{R}}}n, and a variety of inversion formulas. In many applications (e.g., in homeland security), the signal to noise ratio is very low. So, if overdetermined data is collected (as in the case of Compton imaging), attempts to reduce the dimensionality might lead to essential elimination of the signal. Thus, our main concentration is on obtaining formulas involving overdetermined data.
NASA Astrophysics Data System (ADS)
Syndergaard, S.; Kirchengast, G.
2016-03-01
We have developed a formula for the retrieval of the line-of-sight (l.o.s.) wind speed from future low Earth orbit (LEO) satellite-to-satellite infrared laser occultation measurements. The formula involves an Abelian integral transform akin to the Abel transform widely used for deriving refractive index from bending angle in Global Navigation Satellite System radio occultation measurements. Besides the Abelian integral transform, the formula is derived from a truncated series expansion of the volume absorption coefficient as a function of frequency and includes a simple absorption-line-asymmetry correction term. A first-order formulation (referred to as the standard formula) is complemented by higher-order terms that can be used for high-accuracy computations. Under the assumptions of spherical symmetry and perfect knowledge of spectroscopy, the residual l.o.s. wind error from using the standard formula rather than the high-accuracy formula is assessed to be small compared to that anticipated from measurement errors in a real experiment. Applying the new formula just in standard form to future infrared laser transmission profiles would therefore enable the retrieval of l.o.s. stratospheric wind profiles with an accuracy limited mainly by measurement errors, residual spectroscopic errors, and deviations from spherical symmetry.
Rapid Inversion of Angular Deflection Data for Certain Axisymmetric Refractive Index Distributions
NASA Technical Reports Server (NTRS)
Rubinstein, R.; Greenberg, P. S.
1994-01-01
Certain functions useful for representing axisymmetric refractive-index distributions are shown to have exact solutions for Abel transformation of the resulting angular deflection data. An advantage of this procedure over direct numerical Abel inversion is that least-squares curve fitting is a smoothing process that reduces the noise sensitivity of the computation
The duality principle and inversion of Laplace-Stielties transforms
NASA Astrophysics Data System (ADS)
Pavelyev, A. G.
2016-04-01
The fundamental relation between the Laplace transform, the Stielties transform, and the generalized integral equation of refraction is revealed, and a duality principle is formulated for the solution of inverse problems of radio physics. New formulas of the Laplace-transform inversion satisfying the duality principle are obtained. There is no necessity of contour integration in a complex plane for the relations found, which considerably simplifies the reconstruction of originals and makes it possible to control systematic errors in the experimental data.
Abel reconstruction of piecewise constant radial density profiles from x-ray radiographs.
Deutsch, M; Notea, A; Pal, D
1989-08-01
We present a method for reconstructing the radial density profile of a cylindrically symmetric object from a single x-ray projection, when the profile consists of a number of different constant sections. A forward Abel transform based algorithm is employed whereby the profile is recovered recursively, onion peelinglike, starting from the outside diameter of the object and moving in. Distortions originating in the Gibbs phenomenon, unavoidable in most available Abel inversion methods, are completely eliminated. The method is simple enough to be carried out on a handheld calculator or a spreadsheet program on a personal computer, and no elaborate computer fits or application programming are required. The method is demonstrated by inverting a simulated three-section noisy set of data and is shown to yield results of a quality equal to that of a recent powerful Abel inversion method, based on full nonlinear least-squares computer fits. PMID:20555668
Numerical Laplace Transform Inversion Employing the Gaver-Stehfest Algorithm.
ERIC Educational Resources Information Center
Jacquot, Raymond G.; And Others
1985-01-01
Presents a technique for the numerical inversion of Laplace Transforms and several examples employing this technique. Limitations of the method in terms of available computer word length and the effects of these limitations on approximate inverse functions are also discussed. (JN)
General inversion formulas for wavelet transforms
NASA Astrophysics Data System (ADS)
Holschneider, Matthias
1993-09-01
This article is the continuation of a series of articles about group theory and wavelet analysis [A. Grossmann, J. Morlet, and T. Paul, J. Math. Phys. 26, 2473 (1985)]. As is well-known in the case of the afine group, the reconstruction wavelet and the analyzing wavelet need not be identic. In this article it is shown that this holds for arbitrary groups. In addition it is shown that even for nonadmissible analyzing wavelets the wavelet transform may be inverted. Accordingly the image of the wavelet transform can be characterized by many different reproducing kernels.
Book review: Nonlinear ocean waves and the inverse scattering transform
Geist, Eric L.
2011-01-01
Nonlinear Ocean Waves and the Inverse Scattering Transform is a comprehensive examination of ocean waves built upon the theory of nonlinear Fourier analysis. The renowned author, Alfred R. Osborne, is perhaps best known for the discovery of internal solitons in the Andaman Sea during the 1970s. In this book, he provides an extensive treatment of nonlinear water waves based on a nonlinear spectral theory known as the inverse scattering transform. The writing is exceptional throughout the book, which is particularly useful in explaining some of the more difficult mathematical concepts. Review info: Nonlinear Ocean Waves and the Inverse Scattering Transform. By Alfred R. Osborne, 2010. ISBN: 978-125286299, 917 pp.
Fast transforms: Banded matrices with banded inverses
Strang, Gilbert
2010-01-01
It is unusual for both A and A-1 to be banded—but this can be a valuable property in applications. Block-diagonal matrices F are the simplest examples; wavelet transforms are more subtle. We show that every example can be factored into A = F1…FN where N is controlled by the bandwidths of A and A-1 (but not by their size, so this extends to infinite matrices and leads to new matrix groups). PMID:20615937
Wavelet transform analysis of the small-scale X-ray structure of the cluster Abell 1367
NASA Technical Reports Server (NTRS)
Grebeney, S. A.; Forman, W.; Jones, C.; Murray, S.
1995-01-01
We have developed a new technique based on a wavelet transform analysis to quantify the small-scale (less than a few arcminutes) X-ray structure of clusters of galaxies. We apply this technique to the ROSAT position sensitive proportional counter (PSPC) and Einstein high-resolution imager (HRI) images of the central region of the cluster Abell 1367 to detect sources embedded within the diffuse intracluster medium. In addition to detecting sources and determining their fluxes and positions, we show that the wavelet analysis allows a characterization of the sources extents. In particular, the wavelet scale at which a given source achieves a maximum signal-to-noise ratio in the wavelet images provides an estimate of the angular extent of the source. To account for the widely varying point response of the ROSAT PSPC as a function of off-axis angle requires a quantitative measurement of the source size and a comparison to a calibration derived from the analysis of a Deep Survey image. Therefore, we assume that each source could be described as an isotropic two-dimensional Gaussian and used the wavelet amplitudes, at different scales, to determine the equivalent Gaussian Full Width Half-Maximum (FWHM) (and its uncertainty) appropriate for each source. In our analysis of the ROSAT PSPC image, we detect 31 X-ray sources above the diffuse cluster emission (within a radius of 24 min), 16 of which are apparently associated with cluster galaxies and two with serendipitous, background quasars. We find that the angular extents of 11 sources exceed the nominal width of the PSPC point-spread function. Four of these extended sources were previously detected by Bechtold et al. (1983) as 1 sec scale features using the Einstein HRI. The same wavelet analysis technique was applied to the Einstein HRI image. We detect 28 sources in the HRI image, of which nine are extended. Eight of the extended sources correspond to sources previously detected by Bechtold et al. Overall, using both the
Application of inverse, strict conformal transformation to design waveguide devices.
Ma, Y G; Wang, N; Ong, C K
2010-05-01
Integration of transformation optics with development of metamaterials offers great opportunities to create exotic material with electromagnetic functionality absent from nature. It has already led to several significant advancements in physical conceptions and technological applications such as invisible cloaking. Unfortunately practical application is often restricted by the complex requirements on material properties imposed by the general optical transformation theory. It is therefore necessary to relax the stringent requirements of materials properties in order to practicably use the power of transformation optics to design exotic optical devices. Development of new coordinate transformation mathematics to compromise between the stringent materials properties and the ultimate performance required by a useful novel device is required. In this work the authors employed strict conformal transformation to design physical materials that could guide light in a predetermined way. A simple and efficient numerical approach based on unusual inverse transformation is proposed here to quickly solve partial differential equations and construct the mapping relationship. The results showed that a transformed optical device could be made by purely using isotropic dielectric materials. Two application examples were numerically proposed to verify the versatility of conformal transformation and the robustness of the inverse approach. One was a 90 degrees waveguide beam bend, and the other was a waveguide-type beam splitter or coupler. PMID:20448761
Kinugawa, Tohru
2014-02-15
This paper presents a simple but nontrivial generalization of Abel's mechanical problem, based on the extended isochronicity condition and the superposition principle. There are two primary aims. The first one is to reveal the linear relation between the transit-time T and the travel-length X hidden behind the isochronicity problem that is usually discussed in terms of the nonlinear equation of motion (d{sup 2}X)/(dt{sup 2}) +(dU)/(dX) =0 with U(X) being an unknown potential. Second, the isochronicity condition is extended for the possible Abel-transform approach to designing the isochronous trajectories of charged particles in spectrometers and/or accelerators for time-resolving experiments. Our approach is based on the integral formula for the oscillatory motion by Landau and Lifshitz [Mechanics (Pergamon, Oxford, 1976), pp. 27–29]. The same formula is used to treat the non-periodic motion that is driven by U(X). Specifically, this unknown potential is determined by the (linear) Abel transform X(U) ∝ A[T(E)], where X(U) is the inverse function of U(X), A=(1/√(π))∫{sub 0}{sup E}dU/√(E−U) is the so-called Abel operator, and T(E) is the prescribed transit-time for a particle with energy E to spend in the region of interest. Based on this Abel-transform approach, we have introduced the extended isochronicity condition: typically, τ = T{sub A}(E) + T{sub N}(E) where τ is a constant period, T{sub A}(E) is the transit-time in the Abel type [A-type] region spanning X > 0 and T{sub N}(E) is that in the Non-Abel type [N-type] region covering X < 0. As for the A-type region in X > 0, the unknown inverse function X{sub A}(U) is determined from T{sub A}(E) via the Abel-transform relation X{sub A}(U) ∝ A[T{sub A}(E)]. In contrast, the N-type region in X < 0 does not ensure this linear relation: the region is covered with a predetermined potential U{sub N}(X) of some arbitrary choice, not necessarily obeying the Abel-transform relation. In discussing
NASA Astrophysics Data System (ADS)
Kinugawa, Tohru
2014-02-01
This paper presents a simple but nontrivial generalization of Abel's mechanical problem, based on the extended isochronicity condition and the superposition principle. There are two primary aims. The first one is to reveal the linear relation between the transit-time T and the travel-length X hidden behind the isochronicity problem that is usually discussed in terms of the nonlinear equation of motion {d^2X}/{dt^2} + {dU}/{dX} = 0 with U(X) being an unknown potential. Second, the isochronicity condition is extended for the possible Abel-transform approach to designing the isochronous trajectories of charged particles in spectrometers and/or accelerators for time-resolving experiments. Our approach is based on the integral formula for the oscillatory motion by Landau and Lifshitz [Mechanics (Pergamon, Oxford, 1976), pp. 27-29]. The same formula is used to treat the non-periodic motion that is driven by U(X). Specifically, this unknown potential is determined by the (linear) Abel transform X(U) ∝ A[T(E)], where X(U) is the inverse function of U(X), A = (1/sqrt{π })int 0E {dU}/sqrt{E-U} is the so-called Abel operator, and T(E) is the prescribed transit-time for a particle with energy E to spend in the region of interest. Based on this Abel-transform approach, we have introduced the extended isochronicity condition: typically, τ = TA(E) + TN(E) where τ is a constant period, TA(E) is the transit-time in the Abel type [A-type] region spanning X > 0 and TN(E) is that in the Non-Abel type [N-type] region covering X < 0. As for the A-type region in X > 0, the unknown inverse function XA(U) is determined from TA(E) via the Abel-transform relation XA(U) ∝ A[TA(E)]. In contrast, the N-type region in X < 0 does not ensure this linear relation: the region is covered with a predetermined potential UN(X) of some arbitrary choice, not necessarily obeying the Abel-transform relation. In discussing the isochronicity problem, there has been no attempt of N-type regions that are
Non-thermal Hard X-Ray Emission from Coma and Several Abell Clusters
Correa, C
2004-02-05
We report results of hard X-Ray observations of the clusters Coma, Abell 496, Abell754, Abell 1060, Abell 1367, Abell2256 and Abell3558 using RXTE data from the NASA HEASARC public archive. Specifically we searched for clusters with hard x-ray emission that can be fitted by a power law because this would indicate that the cluster is a source of non-thermal emission. We are assuming the emission mechanism proposed by Vahk Petrosian where the inter cluster space contains clouds of relativistic electrons that by themselves create a magnetic field and emit radio synchrotron radiation. These relativistic electrons Inverse-Compton scatter Microwave Background photons up to hard x-ray energies. The clusters that were found to be sources of non-thermal hard x-rays are Coma, Abell496, Abell754 and Abell 1060.
Approximate inverse and Sobolev estimates for the attenuated Radon transform
NASA Astrophysics Data System (ADS)
Rigaud, G.; Lakhal, A.
2015-10-01
The ill-posedness of the attenuated Radon transform is a challenging issue in practice due to the Poisson noise and the high level of attenuation. The investigation of the smoothing properties of the underlying operator is essential for developing a stable inversion. In this paper, we consider the framework of Sobolev spaces and derive analytically a reconstruction algorithm based on the method of the approximate inverse. The derived method inherits the efficiency and stability of the approximate inverse and supplies a method of extraction of contours. These algorithms appear to be efficient for an attenuation of human body type. However, for higher attenuations the ill-posedness increases exponentially what deteriorates accordingly the quality of reconstructions. Nevertheless, a high attenuation map affects less the contour extraction of a high contrast function and so can be neglected. This leads to simplifying the proposed method and circumvents in this case the artifacts due to the attenuation as attested by simulation results.
Inversion transformations in geometrical optics and allied subjects
NASA Astrophysics Data System (ADS)
Cornbleet, S.
Practical application of the inversion transformation to two problems in the field of perfectly imaging optics, (1) the basic reflection/refraction process and (2) imaging in a spherically symmetrical nonuniform medium, is discussed. The refraction construction involved in the "zero distance phase front" and the application of Damien's theorem to it are addressed, and the propagation of rays through spherical lenses is analyzed. Transformation of the spherical medium is considered, and the mechanical analogue to the optical concept of the phase front is discussed.
Digital signal processing based on inverse scattering transform.
Turitsyna, Elena G; Turitsyn, Sergei K
2013-10-15
Through numerical modeling, we illustrate the possibility of a new approach to digital signal processing in coherent optical communications based on the application of the so-called inverse scattering transform. Considering without loss of generality a fiber link with normal dispersion and quadrature phase shift keying signal modulation, we demonstrate how an initial information pattern can be recovered (without direct backward propagation) through the calculation of nonlinear spectral data of the received optical signal. PMID:24321955
Local inversion of the sonar transform regularized by the approximate inverse
NASA Astrophysics Data System (ADS)
Quinto, Eric Todd; Rieder, Andreas; Schuster, Thomas
2011-03-01
A new reconstruction method is given for the spherical mean transform with centers on a plane in {{ R}^3} which is also called the sonar transform. Standard inversion formulas require data over all spheres, but typically, the data are limited in the sense that the centers and radii are in a compact set. Our reconstruction operator is local because, to reconstruct at \\mathbf {x}, one needs only spheres that pass near \\mathbf {x}, and the operator reconstructs singularities, such as object boundaries. The microlocal properties of the reconstruction operator, including its symbol as a pseudodifferential operator, are given. The method is implemented using the approximate inverse, and reconstructions are given. They are evaluated in light of the microlocal properties of the reconstruction operator.
Real Variable Inversion of Laplace Transforms: An Application in Plasma Physics.
ERIC Educational Resources Information Center
Bohn, C. L.; Flynn, R. W.
1978-01-01
Discusses the nature of Laplace transform techniques and explains an alternative to them: the Widder's real inversion. To illustrate the power of this new technique, it is applied to a difficult inversion: the problem of Landau damping. (GA)
A numerical inversion of a the Laplace transform solution to radial dispersion in a porous medium.
Moench, A.F.; Ogata, A.
1981-01-01
A special form of the numerical inversion of the Laplace transform described by Stehfest (1970) is applied to the transformed solution of dispersion in a radial flow system in a porous medium. The inversion is extremely simple to use because the weighting coefficients depend only on the number of terms used in the computation and not upon the transform solution as required by most numerical inversion techniques.-from Authors
Semi-local inversion of the geodesic ray transform in the hyperbolic plane
NASA Astrophysics Data System (ADS)
Courdurier, Matias; Saez, Mariel
2013-06-01
The inversion of the ray transform on the hyperbolic plane has applications in geophysical exploration and in medical imaging techniques (such as electrical impedance tomography). The geodesic ray transform has been studied in more general geometries and including attenuation, but all of the available inversion formulas require knowledge of the ray transform for all the geodesics. In this paper we present a different inversion formula for the ray transform on the hyperbolic plane, which has the advantage of only requiring knowledge of the ray transform in a reduced family of geodesics. The required family of geodesics is directly related to the set where the original function is to be recovered.
Fair and Square Computation of Inverse "Z"-Transforms of Rational Functions
ERIC Educational Resources Information Center
Moreira, M. V.; Basilio, J. C.
2012-01-01
All methods presented in textbooks for computing inverse "Z"-transforms of rational functions have some limitation: 1) the direct division method does not, in general, provide enough information to derive an analytical expression for the time-domain sequence "x"("k") whose "Z"-transform is "X"("z"); 2) computation using the inversion integral…
Optimal inversion of the generalized Anscombe transformation for Poisson-Gaussian noise.
Mäkitalo, Markku; Foi, Alessandro
2013-01-01
Many digital imaging devices operate by successive photon-to-electron, electron-to-voltage, and voltage-to-digit conversions. These processes are subject to various signal-dependent errors, which are typically modeled as Poisson-Gaussian noise. The removal of such noise can be effected indirectly by applying a variance-stabilizing transformation (VST) to the noisy data, denoising the stabilized data with a Gaussian denoising algorithm, and finally applying an inverse VST to the denoised data. The generalized Anscombe transformation (GAT) is often used for variance stabilization, but its unbiased inverse transformation has not been rigorously studied in the past. We introduce the exact unbiased inverse of the GAT and show that it plays an integral part in ensuring accurate denoising results. We demonstrate that this exact inverse leads to state-of-the-art results without any notable increase in the computational complexity compared to the other inverses. We also show that this inverse is optimal in the sense that it can be interpreted as a maximum likelihood inverse. Moreover, we thoroughly analyze the behavior of the proposed inverse, which also enables us to derive a closed-form approximation for it. This paper generalizes our work on the exact unbiased inverse of the Anscombe transformation, which we have presented earlier for the removal of pure Poisson noise. PMID:22692910
NASA Astrophysics Data System (ADS)
Hu, Li-Yun; Fan, Hong-Yi
2010-07-01
In a preceding letter (2007 Opt. Lett. 32 554) we propose complex continuous wavelet transforms and found Laguerre-Gaussian mother wavelets family. In this work we present the inversion formula and Parseval theorem for complex continuous wavelet transform by virtue of the entangled state representation, which makes the complex continuous wavelet transform theory complete. A new orthogonal property of mother wavelet in parameter space is revealed.
Arikan and Alamouti matrices based on fast block-wise inverse Jacket transform
NASA Astrophysics Data System (ADS)
Lee, Moon Ho; Khan, Md Hashem Ali; Kim, Kyeong Jin
2013-12-01
Recently, Lee and Hou (IEEE Signal Process Lett 13: 461-464, 2006) proposed one-dimensional and two-dimensional fast algorithms for block-wise inverse Jacket transforms (BIJTs). Their BIJTs are not real inverse Jacket transforms from mathematical point of view because their inverses do not satisfy the usual condition, i.e., the multiplication of a matrix with its inverse matrix is not equal to the identity matrix. Therefore, we mathematically propose a fast block-wise inverse Jacket transform of orders N = 2 k , 3 k , 5 k , and 6 k , where k is a positive integer. Based on the Kronecker product of the successive lower order Jacket matrices and the basis matrix, the fast algorithms for realizing these transforms are obtained. Due to the simple inverse and fast algorithms of Arikan polar binary and Alamouti multiple-input multiple-output (MIMO) non-binary matrices, which are obtained from BIJTs, they can be applied in areas such as 3GPP physical layer for ultra mobile broadband permutation matrices design, first-order q-ary Reed-Muller code design, diagonal channel design, diagonal subchannel decompose for interference alignment, and 4G MIMO long-term evolution Alamouti precoding design.
Composite Weibull-Inverse Transformed Gamma distribution and its actuarial application
NASA Astrophysics Data System (ADS)
Maghsoudi, Mastoureh; Bakar, Shaiful Anuar Abu; Hamzah, Nor Aishah
2014-07-01
This paper introduces a new composite model, namely, composite Weibull-Inverse Transformed Gamma distribution which assumes Weibull distribution for the head up to a specified threshold and inverse transformed gamma distribution beyond it. The closed form of probability density function (pdf) as well as the estimation of parameters by maximum likelihood method is presented. The model is compared with several benchmark distributions and their performances are measured. A well-known data set, Danish fire loss data, is used for this purpose and it's Value at Risk (VaR) using the new model is computed. In comparison to several standard models, the composite Weibull- Inverse Transformed Gamma model proved to be a competitor candidate.
Aranda, A; Bonizzi, P; Karel, J; Peeters, R
2015-08-01
This study performs a comparison between Dower's inverse transform and Frank lead system for Myocardial Infarction (MI) identification. We have selected a set of relevant features for MI detection from the vectorcardiogram and used the lasso method after that to build a model for the Dower's inverse transform and one for the Frank leads system. Then we analyzed the performance between both models on MI detection. The proposed methods have been tested using PhysioNet PTB database that contains 550 records from which 368 are MIs. Two main conclusions are coming from this study. The first one is that Dower's inverse transform performs equally well than Frank leads in identification of MI patients. The second one is that lead positions have a large influence on the accuracy of MI patient identification. PMID:26737293
Single- and coupled-channel radial inverse scattering with supersymmetric transformations
NASA Astrophysics Data System (ADS)
Baye, Daniel; Sparenberg, Jean-Marc; Pupasov-Maksimov, Andrey M.; Samsonov, Boris F.
2014-06-01
The present status of the three-dimensional inverse-scattering method with supersymmetric transformations is reviewed for the coupled-channel case. We first revisit in a pedagogical way the single-channel case, where the supersymmetric approach is shown to provide a complete, efficient and elegant solution to the inverse-scattering problem for the radial Schrödinger equation with short-range interactions. A special emphasis is put on the differences between conservative and non-conservative transformations, i.e. transformations that do or do not conserve the behaviour of solutions of the radial Schrödinger equation at the origin. In particular, we show that for the zero initial potential, a non-conservative transformation is always equivalent to a pair of conservative transformations. These single-channel results are illustrated on the inversion of the neutron-proton triplet eigenphase shifts for the S- and D-waves. We then summarize and extend our previous works on the coupled-channel case, i.e. on systems of coupled radial Schrödinger equations, and stress remaining difficulties and open questions of this problem by putting it in perspective with the single-channel case. We mostly concentrate on two-channel examples to illustrate general principles while keeping mathematics as simple as possible. In particular, we discuss the important difference between the equal-threshold and different-threshold problems. For equal thresholds, conservative transformations can provide non-diagonal Jost and scattering matrices. Iterations of such transformations in the two-channel case are studied and shown to lead to practical algorithms for inversion. A convenient particular technique where the mixing parameter can be fitted without modifying the eigenphases is developed with iterations of pairs of conjugate transformations. This technique is applied to the neutron-proton triplet S-D scattering matrix, for which exactly-solvable matrix potential models are constructed. For
NASA Astrophysics Data System (ADS)
Hamimid, M.; Mimoune, S. M.; Feliachi, M.
2013-11-01
In this paper, we present a Langevin transforms model which evaluates accurately minor hysteresis loops for the modified inverse Jiles-Atherton model by using appropriate expressions in order to improve minor hysteresis loops characteristics. The parameters of minor hysteresis loops are then related to the parameters of the major hysteresis loop according to each level of maximal induction by using Langevin transforms expressions. The stochastic optimization method “simulated annealing” is used for the determination of the Langevin transforms coefficients. This model needs only two experimental tests to generate all hysteresis loops. The validity of the Langevin transforms model is justified by comparison of calculated minor hysteresis loops to measured ones and good agreements are obtained with better results than the exponential transforms model (Hamimid et al., 2011 [4]).
A real-time inverse quantised transform for multi-standard with dynamic resolution support
NASA Astrophysics Data System (ADS)
Sun, Chi-Chia; Lin, Chun-Ying; Zhang, Ce
2016-06-01
In this paper, a real-time configurable intelligent property (IP) core is presented for image/video decoding process in compatibility with the standard MPEG-4 Visual and the standard H.264/AVC. The inverse quantised discrete cosine and integer transform can be used to perform inverse quantised discrete cosine transform and inverse quantised inverse integer transforms which only required shift and add operations. Meanwhile, COordinate Rotation DIgital Computer iterations and compensation steps are adjustable in order to compensate for the video compression quality regarding various data throughput. The implementations are embedded in publicly available software XVID Codes 1.2.2 for the standard MPEG-4 Visual and the H.264/AVC reference software JM 16.1, where the experimental results show that the balance between the computational complexity and video compression quality is retained. At the end, FPGA synthesised results show that the proposed IP core can bring advantages to low hardware costs and also provide real-time performance for Full HD and 4K-2K video decoding.
ERIC Educational Resources Information Center
Brown, Malcolm
2009-01-01
Inversions are fascinating phenomena. They are reversals of the normal or expected order. They occur across a wide variety of contexts. What do inversions have to do with learning spaces? The author suggests that they are a useful metaphor for the process that is unfolding in higher education with respect to education. On the basis of…
Casey, F X; Simůnek, J
2001-01-01
Chemical and biological transformations can significantly affect contaminant transport in the subsurface. To better understand such transformation reactions, an equilibrium-nonequilibrium sorption transport model, HYDRUS-1D, was modified by including inverse solutions for multiple breakthrough curves resulting from the transport of solutes undergoing sequential transformations. The inverse solutions were applied to miscible-displacement experiments involving dissolved concentrations of trichloroethylene (TCE) undergoing reduction and/or transformations in the presence of zero-valent metal porous media (i.e., iron or copper-coated iron filings) to produce ethylene. The inverse model solutions provided a reasonable description of the transport and transformation processes. Simultaneous fitting of multiple breakthrough curves of TCE and ethylene placed additional constraints on the inverse solution and improved the reliability of parameter estimates. Confidence intervals of optimized parameters were reduced significantly in comparison with those obtained by fitting TCE breakthrough curves independently. Further evidence for accurate parameter estimates was given when the parameter values agreed with previously reported values from independent batch and degradation experiments. Optimized values of the normalized degradation rates for the equilibrium (1.4 x 10(-4) to 7.2 x 10(-5) L h(-1)m(-2)) and nonequilibrium (1.2 x 10(-4) to 5.5 x 10(-5)L h(-1)m(-2)) models compared well with values (0.03 to 6.5 x 10(-5) L h(-1) m(-2)) obtained from previous studies. The estimated TCE-iron sorption coefficients (0.52 to 2.85 L kg(-1)) were also consistent with a previously reported value (1.47 L kg(-1)). PMID:11476514
NASA Astrophysics Data System (ADS)
Galizzi, Gustavo E.; Cuadrado-Laborde, Christian
2015-10-01
In this work we study the joint transform correlator setup, finding two analytical expressions for the extensions of the joint power spectrum and its inverse Fourier transform. We found that an optimum efficiency is reached, when the bandwidth of the key code is equal to the sum of the bandwidths of the image plus the random phase mask (RPM). The quality of the decryption is also affected by the ratio between the bandwidths of the RPM and the input image, being better as this ratio increases. In addition, the effect on the decrypted image when the detection area is lower than the encrypted signal extension was analyzed. We illustrate these results through several numerical examples.
NASA Astrophysics Data System (ADS)
Migukin, Artem; Katkovnik, Vladimir; Astola, Jaakko
2010-04-01
The phase retrieval is formulated as an inverse problem, where the forward propagation is defined by Discrete Diffraction Transform (DDT) [1], [2]. This propagation model is precise and aliasing free for pixelwise invariant (pixelated) wave field distributions in the sensor and object planes. Because of finite size of sensors DDT can be ill-conditioned and the regularization is an important component of the inverse. The proposed algorithm is designed for multiple plane observations and can be treated as a generalization of the Gerchberg-Saxton iterative algorithm. The proposed algorithm is studied by numerical experiments produced for phase and amplitude modulated object distributions. Comparison versus the conventional forward propagation models such as the angular spectrum decomposition and the convolutional model used in the algorithm of the same structure shows a clear advantage of DDT enabling better accuracy and better imaging.
NASA Astrophysics Data System (ADS)
Engel, Megan C.; Ritchie, Dustin B.; Foster, Daniel A. N.; Beach, Kevin S. D.; Woodside, Michael T.
2014-12-01
The energy landscapes that drive structure formation in biopolymers are difficult to measure. Here we validate experimentally a novel method to reconstruct landscape profiles from single-molecule pulling curves using an inverse Weierstrass transform (IWT) of the Jarzysnki free-energy integral. The method was applied to unfolding measurements of a DNA hairpin, replicating the results found by the more-established weighted histogram (WHAM) and inverse Boltzmann methods. Applying both WHAM and IWT methods to reconstruct the folding landscape for a RNA pseudoknot having a stiff energy barrier, we found that landscape features with sharper curvature than the force probe stiffness could not be recovered with the IWT method. The IWT method is thus best for analyzing data from stiff force probes such as atomic force microscopes.
Conn, Charlotte E.; Ces, Oscar; Mulet, Xavier; Seddon, John M.; Templer, Richard H.; Finet, Stephanie; Winter, Roland
2006-03-17
The liquid crystalline lamellar (L{sub {alpha}}) to double-diamond inverse bicontinuous cubic (Q{sub II}{sup D}) phase transition for the amphiphile monoelaidin in excess water exhibits a remarkable sequence of structural transformations for pressure or temperature jumps. Our data imply that the transition dynamics depends on a coupling between changes in molecular shape and the geometrical and topological constraints of domain size. We propose a qualitative model for this coupling based on theories of membrane fusion via stalks and existing knowledge of the structure and energetics of bicontinuous cubic phases.
Prediction inverse d'un front de solidification dans un four de transformation a haute temperature
NASA Astrophysics Data System (ADS)
Marois, Marc-Andre
Ce projet de recherche porte sur une methode numerique permettant de predire l'evolution du profil 2D de la couche solide qui recouvre l'interieur des parois de plusieurs fours de transformation a haute temperature. Un modele mathematique base sur la formulation faible de l'energie est d'abord developpe et valide. Une methode de transfert thermique inverse reposant sur ce modele est ensuite developpee afin d'obtenir une mesure rapide et continue de l'evolution du profil de cette couche solide. Vu la grande inertie thermique du systeme a l'etude, differentes strategies sont proposees afin de faciliter la mise en uvre de cette methode numerique. Finalement, cette approche inverse est confrontee aux resultats experimentaux obtenus a l'aide d'un reacteur metallurgique. Une etude preliminaire montre que les fours de transformation presentent une tres grande inertie thermique qui limite grandement l'utilisation des methodes inverses. En effet, la sensibilite de cette methode numerique repose essentiellement sur le delai temporel observe entre la variation du profil du banc et la fluctuation de la temperature a la surface externe de la paroi du four. Les resultats obtenus demontrent qu'une partie de ce delai est proportionnel a la chaleur latente de fusion lorsque le materiau a changement de phase est constitue d'un melange non eutectique. Afin de limiter l'impact de ce delai temporel, deux astuces numeriques sont proposees : reutiliser plus d'une fois les mesures de temperature et modifier le probleme thermique dans les regions pateuse et liquide. D'une part, le concept de chevauchement propose permet de reduire le temps d'acquisition des donnees entre chacune des predictions. D'autre part, l'approche virtuelle developpee permet de reduire l'inertie thermique du systeme et, par le fait meme, le delai temporel associe a la diffusion de la chaleur. Ces deux strategies ont permis de predire efficacement l'evolution 1D de l'epaisseur de la couche de gelee qui se solidifie a
A comparison of techniques for inversion of radio-ray phase data in presence of ray bending
NASA Technical Reports Server (NTRS)
Wallio, H. A.; Grossi, M. D.
1972-01-01
Derivations are presented of the straight-line Abel transform and the seismological Herglotz-Wiechert transform (which takes ray bending into account) that are used in the reconstruction of refractivity profiles from radio-wave phase data. Profile inversion utilizing these approaches, performed in computer-simulated experiments, are compared for cases of positive, zero, and negative ray bending. For thin atmospheres and ionospheres, such as the Martian atmosphere and ionosphere, radio wave signals are shown to be inverted accurately with both methods. For dense media, such as the solar corona or the lower Venus atmosphere, the refractive recovered by the seismological Herglotz-Wiechert transform provide a significant improvement compared with the straight-line Abel transform.
A systolic array for efficient execution of the radon and inverse radon transforms
De Groot, A.J.; Azevedo, S.G.; Schneberk, D.J.; Johansson, E.M.; Parker, S.R.
1988-08-11
The Systolic Processor with a Reconfigurable Interconnection Network of Transputers (SPRINT) is a sixty-four-element multiprocessor developed at Lawrence Livermore National Laboratory to evaluate systolic algorithms and architectures experimentally. The processors are interconnected in a reconfigurable network which can emulate networks such as the two-dimensional mesh, the triangular mesh, the tree, and the shuffle-exchange network. New systolic algorithms and architectures are described which perform the Radon transform and inverse Radon transform with efficiency arbitrarily close to 100%. High efficiency is possible with any connected network topology, even with low communication bandwidth. The results of the algorithms executed on the SPRINT compare closely with theory. 8 refs., 5 figs.
Stability estimates for the regularized inversion of the truncated Hilbert transform
NASA Astrophysics Data System (ADS)
Alaifari, Rima; Defrise, Michel; Katsevich, Alexander
2016-06-01
In limited data computerized tomography, the 2D or 3D problem can be reduced to a family of 1D problems using the differentiated backprojection method. Each 1D problem consists of recovering a compactly supported function f\\in {L}2({ F }), where { F } is a finite interval from its partial Hilbert transform data. When the Hilbert transform is measured on a finite interval { G } that only overlaps but does not cover { F }, this inversion problem is known to be severely ill-posed (Alaifari et al 2015 SIAM J. Math. Anal. 47 797–824). In this paper, we study the reconstruction of f restricted to the overlap region { F }\\cap { G }. We show that with this restriction and by assuming prior knowledge on the L 2 norm or on the variation of f, better stability with Hölder continuity (typical for mildly ill-posed problems) can be obtained.
Oncogenic transformation through the cell cycle and the LET dependent inverse dose rate effect
NASA Technical Reports Server (NTRS)
Geard, C. R.; Miller, R. C.; Brenner, D. J.; Hall, E. J.; Wachholz, B. W. (Principal Investigator)
1994-01-01
Synchronised populations of mouse C3H/10T-1/2 cells were obtained by a stringent mitotic dislodgment procedure. Mitotic cells rapidly attach and progress sequentially through the cell cycle. Irradiation (3 Gy of X rays) was carried out at intervals from 0 to 18 h after initiating cell cycle progression of the mitotic cells. Oncogenic transformation was enhanced 10-fold over cells irradiated soon after replating (G1 and S phases) for cells in a near 2 h period corresponding to cells in G2 phase but not in mitosis. The cell surviving fraction had a 2-1/2-fold variation with resistant peaks corresponding to the late G1 and late S phases. These findings provide experimental support for the hypothesis initiated by Rossi and Kellerer and developed by Brenner and Hall to explain the LET dependent inverse dose rate effect for oncogenic transformation.
Even more inversion formulas for the 2D Radon Transform of functions of compact and convex support.
Mohamed, M-S Ould; Mennessier, C; Clackdoyle, R
2007-01-01
In 2004, Clackdoyle and Noo published a class of inversion formulas for the 2D Radon Transform which depends on the known radius of support of the unknown function. In this work, we extend this class of inversion formulas from functions of circular support to functions with any compact and convex support. We point out the potential benefits of these new inversion formulas in the context of reconstruction from truncated projections. A preliminary implementation of these new inversion formulas is also presented. PMID:18002982
NASA Astrophysics Data System (ADS)
Ouyang, Wei; Mao, Weijian; Li, Xuelei; Li, Wuqun
2014-08-01
Sound velocity inversion problem based on scattering theory is formulated in terms of a nonlinear integral equation associated with scattered field. Because of its nonlinearity, in practice, linearization algorisms (Born/single scattering approximation) are widely used to obtain an approximate inversion solution. However, the linearized strategy is not congruent with seismic wave propagation mechanics in strong perturbation (heterogeneous) medium. In order to partially dispense with the weak perturbation assumption of the Born approximation, we present a new approach from the following two steps: firstly, to handle the forward scattering by taking into account the second-order Born approximation, which is related to generalized Radon transform (GRT) about quadratic scattering potential; then to derive a nonlinear quadratic inversion formula by resorting to inverse GRT. In our formulation, there is a significant quadratic term regarding scattering potential, and it can provide an amplitude correction for inversion results beyond standard linear inversion. The numerical experiments demonstrate that the linear single scattering inversion is only good in amplitude for relative velocity perturbation () of background media up to 10 %, and its inversion errors are unacceptable for the perturbation beyond 10 %. In contrast, the quadratic inversion can give more accurate amplitude-preserved recovery for the perturbation up to 40 %. Our inversion scheme is able to manage double scattering effects by estimating a transmission factor from an integral over a small area, and therefore, only a small portion of computational time is added to the original linear migration/inversion process.
Interpretation of gravity data using 2-D continuous wavelet transformation and 3-D inverse modeling
NASA Astrophysics Data System (ADS)
Roshandel Kahoo, Amin; Nejati Kalateh, Ali; Salajegheh, Farshad
2015-10-01
Recently the continuous wavelet transform has been proposed for interpretation of potential field anomalies. In this paper, we introduced a 2D wavelet based method that uses a new mother wavelet for determination of the location and the depth to the top and base of gravity anomaly. The new wavelet is the first horizontal derivatives of gravity anomaly of a buried cube with unit dimensions. The effectiveness of the proposed method is compared with Li and Oldenburg inversion algorithm and is demonstrated with synthetics and real gravity data. The real gravity data is taken over the Mobrun massive sulfide ore body in Noranda, Quebec, Canada. The obtained results of the 2D wavelet based algorithm and Li and Oldenburg inversion on the Mobrun ore body had desired similarities to the drill-hole depth information. In all of the inversion algorithms the model non-uniqueness is the challenging problem. Proposed method is based on a simple theory and there is no model non-uniqueness on it.
Inversion of the broken ray transform in the case of energy-dependent attenuation.
Krylov, R; Katsevich, A
2015-06-01
Broken Ray transform (BRT) arises when one considers a narrow x-ray beam propagating through medium under the assumption of single scattering. Previous algorithms for inverting the BRT assumed that the medium is characterized by a single attenuation coefficient μ. However x-rays lose their energy after Compton scattering and the energy loss depends on the scattering angle. Since the attenuation coefficient depends on energy, the μ's before and after scattering are different. When there are three or more detectors one should distinguish not only between μ's that are 'seen' by x-rays before and after scattering, but also between μ's that are 'seen' by x-rays traveling towards different detectors.The main thrust of this paper is inversion of the BRT with N ⩾ 3 detectors under the assumption that the attenuation coefficient can be accurately approximated by a linear function of energy within the window of relevant energies. When the number of detectors is four or greater, we derive a family of inversion formulas. If N > 4, we find the optimal formula, which provides the best stability with respect to noise in the data. If N = 4, the family collapses into a single formula and no optimization is possible. If μ is independent of energy, N = 3 is sufficient for inversion. We also develop iterative reconstruction algorithms that can use global and local data. The results of testing the algorithms are presented. PMID:25974246
NASA Astrophysics Data System (ADS)
Lu, Wei; Tan, Jinglu; Floyd, Randall C.
2005-04-01
Object detection in ultrasound fetal images is a challenging task for the relatively low resolution and low signal-to-noise ratio. A direct inverse randomized Hough transform (DIRHT) is developed for filtering and detecting incomplete curves in images with strong noise. The DIRHT combines the advantages of both the inverse and the randomized Hough transforms. In the reverse image, curves are highlighted while a large number of unrelated pixels are removed, demonstrating a "curve-pass filtering" effect. Curves are detected by iteratively applying the DIRHT to the filtered image. The DIRHT was applied to head detection and measurement of the biparietal diameter (BPD) and head circumference (HC). No user input or geometric properties of the head were required for the detection. The detection and measurement took 2 seconds for each image on a PC. The inter-run variations and the differences between the automatic measurements and sonographers" manual measurements were small compared with published inter-observer variations. The results demonstrated that the automatic measurements were consistent and accurate. This method provides a valuable tool for fetal examinations.
NASA Astrophysics Data System (ADS)
Li, Guo; Xia, Jun; Li, Lei; Wang, Lidai; Wang, Lihong V.
2015-03-01
Linear transducer arrays are readily available for ultrasonic detection in photoacoustic computed tomography. They offer low cost, hand-held convenience, and conventional ultrasonic imaging. However, the elevational resolution of linear transducer arrays, which is usually determined by the weak focus of the cylindrical acoustic lens, is about one order of magnitude worse than the in-plane axial and lateral spatial resolutions. Therefore, conventional linear scanning along the elevational direction cannot provide high-quality three-dimensional photoacoustic images due to the anisotropic spatial resolutions. Here we propose an innovative method to achieve isotropic resolutions for three-dimensional photoacoustic images through combined linear and rotational scanning. In each scan step, we first elevationally scan the linear transducer array, and then rotate the linear transducer array along its center in small steps, and scan again until 180 degrees have been covered. To reconstruct isotropic three-dimensional images from the multiple-directional scanning dataset, we use the standard inverse Radon transform originating from X-ray CT. We acquired a three-dimensional microsphere phantom image through the inverse Radon transform method and compared it with a single-elevational-scan three-dimensional image. The comparison shows that our method improves the elevational resolution by up to one order of magnitude, approaching the in-plane lateral-direction resolution. In vivo rat images were also acquired.
NASA Astrophysics Data System (ADS)
Liu, Lisheng; Jiang, Zhenhua; Wang, Tingfeng; Guo, Jin
2015-03-01
An angular spectrum propagation (ASP) algorithm with a scaling parameter to simulate optical diffraction propagation through optical systems is studied. The alterable observation size is obtained by adding the scaling parameter to the Collins formula. A directly mathematical inverse transformation of the ASP algorithm (IASP) is proposed to calculate the source optical field from the known observation optical field, and the results are proved more precise. The IASP algorithm is applied to execute the phase retrieval to derive the aberrations of optical systems from intensity profiles measured in the observation plane. The derived aberrations are fitted by Zernike polynomials under the constraint that the wavefront aberrations are smooth. Numerical simulations are performed to test the accuracy of this method.
Rank-Based Inverse Normal Transformations are Increasingly Used, But are They Merited?
Beasley, T. Mark; Erickson, Stephen; Allison, David B.
2010-01-01
Many complex traits studied in genetics have markedly non-normal distributions. This often implies that the assumption of normally distributed residuals has been violated. Recently, inverse normal transformations (INTs) have gained popularity among genetics researchers and are implemented as an option in several software packages. Despite this increasing use, we are unaware of extensive simulations or mathematical proofs showing that INTs have desirable statistical properties in the context of genetic studies. We show that INTs do not necessarily maintain proper Type 1 error control and can also reduce statistical power in some circumstances. Many alternatives to INTs exist. Therefore, we contend that there is a lack of justification for performing parametric statistical procedures on INTs with the exceptions of simple designs with moderate to large sample sizes, which makes permutation testing computationally infeasible and where maximum likelihood testing is used. Rigorous research evaluating the utility of INTs seems warranted. PMID:19526352
NASA Astrophysics Data System (ADS)
Zhou, Xin
1990-03-01
For the direct-inverse scattering transform of the time dependent Schrödinger equation, rigorous results are obtained based on an opertor-triangular-factorization approach. By viewing the equation as a first order operator equation, similar results as for the first order n x n matrix system are obtained. The nonlocal Riemann-Hilbert problem for inverse scattering is shown to have solution.
Generalized Hough transform for the stress inversion of calcite twin data
NASA Astrophysics Data System (ADS)
Yamaji, Atsushi
2015-11-01
Since the mechanical twinning along calcite e-planes has a critical resolved shear stress, not only principal stress axes but also differential stress can be determined from the orientations of twin lamellae. Based on the five-dimensional stress space that fulfills the principle of coordinate invariance, it is shown in this article that the inversion of twin and untwin data is comparable with fitting a spherical cap to data points on a unit sphere in the space. The principal stress orientations and stress ratio are indicated by the center of the cap, whereas differential stress is denoted by the size of the cap. Based on this geometrical interpretation, the generalized Hough transform was applied to the inversion of the data in this study. The new method is demonstrated to be robust to sampling bias, variability in the critical resolved shear stress. The determination of differential stress was difficult when the differential stress to be detected was ∼10 times larger than the critical resolved shear stress. Stresses were separated by the method from heterogeneous data successfully as long as the spherical caps corresponding to the stresses to be detected had no or a small intersection.
NASA Astrophysics Data System (ADS)
Malezan, A.; Tomal, A.; Antoniassi, M.; Watanabe, P. C. A.; Albino, L. D.; Poletti, M. E.
2015-11-01
In this work, a spectral reconstruction methodology for diagnostic X-ray, using Laplace inverse transform of the attenuation, was successfully applied to dental X-ray equipments. The attenuation curves of 8 commercially available dental X-ray equipment, from 3 different manufactures (Siemens, Gnatus and Dabi Atlante), were obtained by using an ionization chamber and high purity aluminium filters, while the kVp was obtained with a specific meter. A computational routine was implemented in order to adjust a model function, whose inverse Laplace transform is analytically known, to the attenuation curve. This methodology was validated by comparing the reconstructed and the measured (using semiconductor detector of cadmium telluride) spectra of a given dental X-ray unit. The spectral reconstruction showed the Dabi Atlante equipments generating similar shape spectra. This is a desirable feature from clinic standpoint because it produces similar levels of image quality and dose. We observed that equipments from Siemens and Gnatus generate significantly different spectra, suggesting that, for a given operating protocol, these units will present different levels of image quality and dose. This fact claims for the necessity of individualized operating protocols that maximize image quality and dose. The proposed methodology is suitable to perform a spectral reconstruction of dental X-ray equipments from the simple measurements of attenuation curve and kVp. The simplified experimental apparatus and the low level of technical difficulty make this methodology accessible to a broad range of users. The knowledge of the spectral distribution can help in the development of operating protocols that maximize image quality and dose.
NASA Astrophysics Data System (ADS)
Salman, Yehonatan
2016-03-01
In this article, an inversion formula is obtained for the spherical transform which integrates functions, defined on the unit sphere S2, on circles. The inversion formula is for the case where the circles of integration are obtained by intersections of S2 with hyperplanes passing through a common point overline{a} strictly inside S2. In particular, this yields inversion formulas for two well-known special cases. The first inversion formula is for the special case where the family of circles of integration consists of great circles; this formula is obtained by taking overline{a} = 0. The second inversion formula is for the special case where the circles of integration pass through a common point p on S2; this formula is obtained by taking the limit overline{a}→ p.
ERIC Educational Resources Information Center
Debnath, Lokenath
2007-01-01
This paper deals with a brief introduction to major remarkable discoveries of the "soliton" and the "inverse scattering transform" in the 1960s. The discovery of the soliton (or the solitary waves) began with the famous physical experiments of the Scottish Engineer and Naval Architect John Scott Russell in the Glasgow-Edinburgh Canal in 1834. The…
Fast and Scalable Computation of the Forward and Inverse Discrete Periodic Radon Transform.
Carranza, Cesar; Llamocca, Daniel; Pattichis, Marios
2016-01-01
The discrete periodic radon transform (DPRT) has extensively been used in applications that involve image reconstructions from projections. Beyond classic applications, the DPRT can also be used to compute fast convolutions that avoids the use of floating-point arithmetic associated with the use of the fast Fourier transform. Unfortunately, the use of the DPRT has been limited by the need to compute a large number of additions and the need for a large number of memory accesses. This paper introduces a fast and scalable approach for computing the forward and inverse DPRT that is based on the use of: a parallel array of fixed-point adder trees; circular shift registers to remove the need for accessing external memory components when selecting the input data for the adder trees; an image block-based approach to DPRT computation that can fit the proposed architecture to available resources; and fast transpositions that are computed in one or a few clock cycles that do not depend on the size of the input image. As a result, for an N × N image (N prime), the proposed approach can compute up to N(2) additions per clock cycle. Compared with the previous approaches, the scalable approach provides the fastest known implementations for different amounts of computational resources. For example, for a 251×251 image, for approximately 25% fewer flip-flops than required for a systolic implementation, we have that the scalable DPRT is computed 36 times faster. For the fastest case, we introduce optimized just 2N + ⌈log(2) N⌉ + 1 and 2N + 3 ⌈log(2) N⌉ + B + 2 cycles, architectures that can compute the DPRT and its inverse in respectively, where B is the number of bits used to represent each input pixel. On the other hand, the scalable DPRT approach requires more 1-b additions than for the systolic implementation and provides a tradeoff between speed and additional 1-b additions. All of the proposed DPRT architectures were implemented in VHSIC Hardware Description Language
NASA Technical Reports Server (NTRS)
Pinkney, J.; Rhee, George F.; Burns, Jack O.; Batuski, D.; Hill, J. M.; Hintzen, P.; Oegerle, W.
1993-01-01
We have amassed a large sample of velocity data for the cluster of galaxies Abell 2634 which contains the wide-angle tail (WAT) radio source 3C 465. Robust indicators of location and scale and their confidence intervals are used to determine if the cD galaxy, containing the WAT, has a significant peculiar motion. We find a cD peculiar radial velocity of 219 plus or minus 98 km s(exp -1). Further dynamical analyses, including substructure and normality tests, suggest that A 2634 is an unrelaxed cluster whose radio source structure may be bent by the turbulent gas of a recent cluster-subcluster merger.
Inverse scattering transform analysis of rogue waves using local periodization procedure.
Randoux, Stéphane; Suret, Pierre; El, Gennady
2016-01-01
The nonlinear Schrödinger equation (NLSE) stands out as the dispersive nonlinear partial differential equation that plays a prominent role in the modeling and understanding of the wave phenomena relevant to many fields of nonlinear physics. The question of random input problems in the one-dimensional and integrable NLSE enters within the framework of integrable turbulence, and the specific question of the formation of rogue waves (RWs) has been recently extensively studied in this context. The determination of exact analytic solutions of the focusing 1D-NLSE prototyping RW events of statistical relevance is now considered as the problem of central importance. Here we address this question from the perspective of the inverse scattering transform (IST) method that relies on the integrable nature of the wave equation. We develop a conceptually new approach to the RW classification in which appropriate, locally coherent structures are specifically isolated from a globally incoherent wave train to be subsequently analyzed by implementing a numerical IST procedure relying on a spatial periodization of the object under consideration. Using this approach we extend the existing classifications of the prototypes of RWs from standard breathers and their collisions to more general nonlinear modes characterized by their nonlinear spectra. PMID:27385164
Inverse scattering transform analysis of rogue waves using local periodization procedure
Randoux, Stéphane; Suret, Pierre; El, Gennady
2016-01-01
The nonlinear Schrödinger equation (NLSE) stands out as the dispersive nonlinear partial differential equation that plays a prominent role in the modeling and understanding of the wave phenomena relevant to many fields of nonlinear physics. The question of random input problems in the one-dimensional and integrable NLSE enters within the framework of integrable turbulence, and the specific question of the formation of rogue waves (RWs) has been recently extensively studied in this context. The determination of exact analytic solutions of the focusing 1D-NLSE prototyping RW events of statistical relevance is now considered as the problem of central importance. Here we address this question from the perspective of the inverse scattering transform (IST) method that relies on the integrable nature of the wave equation. We develop a conceptually new approach to the RW classification in which appropriate, locally coherent structures are specifically isolated from a globally incoherent wave train to be subsequently analyzed by implementing a numerical IST procedure relying on a spatial periodization of the object under consideration. Using this approach we extend the existing classifications of the prototypes of RWs from standard breathers and their collisions to more general nonlinear modes characterized by their nonlinear spectra. PMID:27385164
NASA Astrophysics Data System (ADS)
Gao, Yingjie; Zhang, Jinhai; Yao, Zhenxing
2016-06-01
The symplectic integration method is popular in high-accuracy numerical simulations when discretizing temporal derivatives; however, it still suffers from time-dispersion error when the temporal interval is coarse, especially for long-term simulations and large-scale models. We employ the inverse time dispersion transform (ITDT) to the third-order symplectic integration method to reduce the time-dispersion error. First, we adopt the pseudospectral algorithm for the spatial discretization and the third-order symplectic integration method for the temporal discretization. Then, we apply the ITDT to eliminate time-dispersion error from the synthetic data. As a post-processing method, the ITDT can be easily cascaded in traditional numerical simulations. We implement the ITDT in one typical exiting third-order symplectic scheme and compare its performances with the performances of the conventional second-order scheme and the rapid expansion method. Theoretical analyses and numerical experiments show that the ITDT can significantly reduce the time-dispersion error, especially for long travel times. The implementation of the ITDT requires some additional computations on correcting the time-dispersion error, but it allows us to use the maximum temporal interval under stability conditions; thus, its final computational efficiency would be higher than that of the traditional symplectic integration method for long-term simulations. With the aid of the ITDT, we can obtain much more accurate simulation results but with a lower computational cost.
Cai, Xiaoyu; Li, Huiyun; Liu, Aiyi
2016-08-30
The increase in incidence of obesity and chronic diseases and their health care costs have raised the importance of quality diet on the health policy agendas. The healthy eating index is an important measure for diet quality which consists of 12 components derived from ratios of dependent variables with distributions hard to specify, measurement errors and excessive zero observations difficult to model parametrically. Hypothesis testing involving data of such nature poses challenges because the widely used multiple comparison procedures such as Hotelling's T(2) test and Bonferroni correction may suffer from substantial loss of efficiency. We propose a marginal rank-based inverse normal transformation approach to normalizing the marginal distribution of the data before employing a multivariate test procedure. Extensive simulation was conducted to demonstrate the ability of the proposed approach to adequately control the type I error rate as well as increase the power of the test, with data particularly from non-symmetric or heavy-tailed distributions. The methods are exemplified with data from a dietary intervention study for type I diabetic children. Published 2016. This article is a U.S. Government work and is in the public domain in the USA. PMID:26990442
Inverse scattering transform analysis of rogue waves using local periodization procedure
NASA Astrophysics Data System (ADS)
Randoux, Stéphane; Suret, Pierre; El, Gennady
2016-07-01
The nonlinear Schrödinger equation (NLSE) stands out as the dispersive nonlinear partial differential equation that plays a prominent role in the modeling and understanding of the wave phenomena relevant to many fields of nonlinear physics. The question of random input problems in the one-dimensional and integrable NLSE enters within the framework of integrable turbulence, and the specific question of the formation of rogue waves (RWs) has been recently extensively studied in this context. The determination of exact analytic solutions of the focusing 1D-NLSE prototyping RW events of statistical relevance is now considered as the problem of central importance. Here we address this question from the perspective of the inverse scattering transform (IST) method that relies on the integrable nature of the wave equation. We develop a conceptually new approach to the RW classification in which appropriate, locally coherent structures are specifically isolated from a globally incoherent wave train to be subsequently analyzed by implementing a numerical IST procedure relying on a spatial periodization of the object under consideration. Using this approach we extend the existing classifications of the prototypes of RWs from standard breathers and their collisions to more general nonlinear modes characterized by their nonlinear spectra.
Mass Substructure in Abell 3128
NASA Astrophysics Data System (ADS)
McCleary, J.; dell'Antonio, I.; Huwe, P.
2015-05-01
We perform a detailed two-dimensional weak gravitational lensing analysis of the nearby (z = 0.058) galaxy cluster Abell 3128 using deep ugrz imaging from the Dark Energy Camera (DECam). We have designed a pipeline to remove instrumental artifacts from DECam images and stack multiple dithered observations without inducing a spurious ellipticity signal. We develop a new technique to characterize the spatial variation of the point-spread function that enables us to circularize the field to better than 0.5% and thereby extract the intrinsic galaxy ellipticities. By fitting photometric redshifts to sources in the observation, we are able to select a sample of background galaxies for weak-lensing analysis free from low-redshift contaminants. Photometric redshifts are also used to select a high-redshift galaxy subsample with which we successfully isolate the signal from an interloping z = 0.44 cluster. We estimate the total mass of Abell 3128 by fitting the tangential ellipticity of background galaxies with the weak-lensing shear profile of a Navarro-Frenk-White (NFW) halo and also perform NFW fits to substructures detected in the 2D mass maps of the cluster. This study yields one of the highest resolution mass maps of a low-z cluster to date and is the first step in a larger effort to characterize the redshift evolution of mass substructures in clusters.
NASA Astrophysics Data System (ADS)
Nasedkina, Yuliya F.; Eliseeva, Svetlana V.; Sementsov, Dmitry I.
2016-04-01
A computer analysis of transformation of Gaussian pulse profile after transmission and reflection at a photonic-crystal structure containing an inversion type defect has been performed. The deformation mode depends significantly on duration of the incident pulse and its carrier frequency values. Deformation for short pulses and pulses whose carrier frequency is close to one of the PBG boundaries or coincides with the defective miniband frequency are most significant.
NASA Technical Reports Server (NTRS)
Chung, W. W.; Mcneill, W. E.; Stortz, M. W.
1993-01-01
The nonlinear inverse transformation flight control system design method is applied to the Lockheed Ft. Worth Company's E-7D short takeoff and vertical land (STOVL) supersonic fighter/attack aircraft design with a modified General Electric F110 engine which has augmented propulsive lift capability. The system is fully augmented to provide flight path control and velocity control, and rate command attitude hold for angular axes during the transition and hover operations. In cruise mode, the flight control system is configured to provide direct thrust command, rate command attitude hold for pitch and roll axes, and sideslip command with turn coordination. A control selector based on the nonlinear inverse transformation method is designed specifically to be compatible with the propulsion system's physical configuration which has a two dimensional convergent-divergent aft nozzle, a vectorable ventral nozzle, and a thrust augmented ejector. The nonlinear inverse transformation is used to determine the propulsive forces and nozzle deflections, which in combination with the aerodynamic forces and moments (including propulsive induced contributions), and gravitational force, are required to achieve the longitudinal and vertical acceleration commands. The longitudinal control axes are fully decoupled within the propulsion system's performance envelope. A piloted motion-base flight simulation was conducted on the Vertical Motion Simulator (VMS) at NASA Ames Research Center to examine the handling qualities of this design. Based on results of the simulation, refinements to the control system have been made and will also be covered in the report.
SHOCKING TAILS IN THE MAJOR MERGER ABELL 2744
Owers, Matt S.; Couch, Warrick J.; Nulsen, Paul E. J.; Randall, Scott W.
2012-05-01
We identify four rare 'jellyfish' galaxies in Hubble Space Telescope imagery of the major merger cluster Abell 2744. These galaxies harbor trails of star-forming knots and filaments which have formed in situ in gas tails stripped from the parent galaxies, indicating they are in the process of being transformed by the environment. Further evidence for rapid transformation in these galaxies comes from their optical spectra, which reveal starburst, poststarburst, and active galactic nucleus features. Most intriguingly, three of the jellyfish galaxies lie near intracluster medium features associated with a merging 'Bullet-like' subcluster and its shock front detected in Chandra X-ray images. We suggest that the high-pressure merger environment may be responsible for the star formation in the gaseous tails. This provides observational evidence for the rapid transformation of galaxies during the violent core passage phase of a major cluster merger.
Shocking Tails in the Major Merger Abell 2744
NASA Astrophysics Data System (ADS)
Owers, Matt S.; Couch, Warrick J.; Nulsen, Paul E. J.; Randall, Scott W.
2012-05-01
We identify four rare "jellyfish" galaxies in Hubble Space Telescope imagery of the major merger cluster Abell 2744. These galaxies harbor trails of star-forming knots and filaments which have formed in situ in gas tails stripped from the parent galaxies, indicating they are in the process of being transformed by the environment. Further evidence for rapid transformation in these galaxies comes from their optical spectra, which reveal starburst, poststarburst, and active galactic nucleus features. Most intriguingly, three of the jellyfish galaxies lie near intracluster medium features associated with a merging "Bullet-like" subcluster and its shock front detected in Chandra X-ray images. We suggest that the high-pressure merger environment may be responsible for the star formation in the gaseous tails. This provides observational evidence for the rapid transformation of galaxies during the violent core passage phase of a major cluster merger.
NASA Astrophysics Data System (ADS)
Guan, Shenheng; Marshall, Alan G.
1996-12-01
Stored waveform excitation produced by inverse Fourier transformation of a specified magnitude/phase excitation spectrum offers the most general and versatile means for broadband mass-selective excitation and ejection in Penning (FT-ICR) and Paul (quadrupole) ion trap mass spectrometry. Since the last comprehensive review of SWIFT excitation in 1987, the technique has been adopted, modified, and extended widely in both the ICR and quadrupole ion trap communities. Here, we review the principles, variations, algorithms, hardware implementation, and some applications of SWIFT for both ICR and quadrupole ion trap mass spectrometry. We show that the most desirable SWIFT waveform is that optimized to reduce both the time-domain SWIFT maximum amplitude and the amplitude near the start and end of the SWIFT waveform. We examine the "true" magnitude excitation spectrum, obtained by zero-filling and forward Fourier transforming the SWIFT time-domain waveform, in order to evaluate the trade-off between spectral magnitude uniformity and frequency (mass) selectivity. Apodization of the SWIFT waveform is optimally conducted by smoothing the excitation magnitude spectrum prior to generation of the SWIFT waveform by inverse FT. When (as for broadband ejection in a quadrupole ion trap) it is important that ions be excited near-simultaneously over a wide mass range, the phase spectrum (before inverse FT to generate the SWIFT waveform) may be overmodulated or randomly modulated ("filtered noise field"), with the recognition that very substantial non-uniformity in the "true" excitation magnitude spectrum will result.
Ravetto, P.; Sumini, M.; Ganapol, B.D.
1988-01-01
In an attempt to better understand the influence of prompt and delayed neutrons on nuclear reactor dynamics, a continuous slowing down model based on Fermi age theory was developed several years ago. This model was easily incorporated into the one-group diffusion equation and provided a realistic physical picture of how delayed and prompt neutrons slow down and simultaneously diffuse throughout a medium. The model allows for different slowing down times for each delayed neutron group as well as for prompt neutrons and for spectral differences between the two typed of neutrons. Because of its generality, this model serves not only a a useful predictive tool to anticipate reactor transients, but also as an excellent educational tool to demonstrate the effect of delayed neutrons in reactor kinetics. However, because of numerical complications, the slowing down model could not be developed to its full potential. In particular, the major limitation was the inversion of the Laplace transform, which relied on a knowledge of the poles associated with the resulting transformed flux. For this reason, only one group of delayed neutrons and times longer than the slowing down times could be considered. As is shown, the new inversion procedure removes the short time limitation as well as allows for any number of delayed neutron groups. The inversion technique is versatile and is useful in teaching numerical methods in nuclear science.
NASA Astrophysics Data System (ADS)
Driver, Simon
1999-07-01
We request 24 orbits to obtain a deep mosaic {6 * 4-orbit pointings} of the central region of A868, a rich Abell cluster which we have imaged comprehensively from the ground. The objective is to identify and characterise the morphological nature of the dwarf galaxy population{s} responsible for the steep upturn seen in this cluster's luminosity function. While similar upturns have been reported in many clusters, the specifics of the dwarf population remain unknown as these objects cannot be resolved from the ground. What type of dwarf galaxies are they ? Is there more than one population contributing ? How are they clustered ? By obtaining deep high-resolution HST WFPC2 imaging over a central field roughly 7.5' * 3.75' we will be able to measure morphologies, light- profiles and the clustering properties of the dwarf population{s} down to M_I = -16 mags {H_o=75kms^-1Mpc^-1}. Although we shall primarily concentrate on the dwarf galaxies, we will also recover the cluster's morphological luminosity distributions for elliptical, spirals and irregulars over a broad absolute magnitude range {-24 < M_I < -16 mags} as well as the more quantitative bivariate brightness distribution {- 24 < M_I < -16 mags, 17.0 < mu_e^I < 25 mags per sq arcsec}. Comparing these results to those recently derived for the general field will provide an insight into the environmental influences on morphology and surface brightness.
NASA Astrophysics Data System (ADS)
Windhari, Ayuty; Handayani, Gunawan
2015-04-01
The 3D inversion gravity anomaly to estimate topographical density using a matlab source code from gridded data provided by Parker Oldenburg algorithm based on fast Fourier transform was computed. We extend and improved the source code of 3DINVERT.M invented by Gomez Ortiz and Agarwal (2005) using the relationship between Fourier transform of the gravity anomaly and the sum of the Fourier transform from the topography density. We gave density contrast between the two media to apply the inversion. FFT routine was implemented to construct amplitude spectrum to the given mean depth. The results were presented as new graphics of inverted topography density, the gravity anomaly due to the inverted topography and the difference between the input gravity data and the computed ones. It terminates when the RMS error is lower than pre-assigned value used as convergence criterion or until maximum of iterations is reached. As an example, we used the matlab program on gravity data of Banten region, Indonesia.
Goerg, Georg M.
2015-01-01
I present a parametric, bijective transformation to generate heavy tail versions of arbitrary random variables. The tail behavior of this heavy tail Lambert W × FX random variable depends on a tail parameter δ ≥ 0: for δ = 0, Y ≡ X, for δ > 0 Y has heavier tails than X. For X being Gaussian it reduces to Tukey's h distribution. The Lambert W function provides an explicit inverse transformation, which can thus remove heavy tails from observed data. It also provides closed-form expressions for the cumulative distribution (cdf) and probability density function (pdf). As a special case, these yield analytic expression for Tukey's h pdf and cdf. Parameters can be estimated by maximum likelihood and applications to S&P 500 log-returns demonstrate the usefulness of the presented methodology. The R package LambertW implements most of the introduced methodology and is publicly available on CRAN. PMID:26380372
NASA Astrophysics Data System (ADS)
Hamimid, M.; Mimoune, S. M.; Feliachi, M.; Atallah, K.
2014-10-01
In this present work, a non centered minor hysteresis loops evaluation is performed using the exponential transforms (ET) of the modified inverse Jiles-Atherton model parameters. This model improves the non centered minor hysteresis loops representation. The parameters of the non centered minor hysteresis loops are obtained from exponential expressions related to the major ones. The parameters of minor loops are obtained by identification using the stochastic optimization method “simulated annealing”. The four parameters of JA model (a,α, k and c) obtained by this transformation are applied only in both ascending and descending branches of the non centered minor hysteresis loops while the major ones are applied to the rest of the cycle. This proposal greatly improves both branches and consequently the minor loops. To validate this model, calculated non-centered minor hysteresis loops are compared with measured ones and good agreements are obtained.
Goerg, Georg M
2015-01-01
I present a parametric, bijective transformation to generate heavy tail versions of arbitrary random variables. The tail behavior of this heavy tail Lambert W × F X random variable depends on a tail parameter δ ≥ 0: for δ = 0, Y ≡ X, for δ > 0 Y has heavier tails than X. For X being Gaussian it reduces to Tukey's h distribution. The Lambert W function provides an explicit inverse transformation, which can thus remove heavy tails from observed data. It also provides closed-form expressions for the cumulative distribution (cdf) and probability density function (pdf). As a special case, these yield analytic expression for Tukey's h pdf and cdf. Parameters can be estimated by maximum likelihood and applications to S&P 500 log-returns demonstrate the usefulness of the presented methodology. The R package Lambert W implements most of the introduced methodology and is publicly available on CRAN. PMID:26380372
Bakhos, Tania; Saibaba, Arvind K.; Kitanidis, Peter K.
2015-10-15
We consider the problem of estimating parameters in large-scale weakly nonlinear inverse problems for which the underlying governing equations is a linear, time-dependent, parabolic partial differential equation. A major challenge in solving these inverse problems using Newton-type methods is the computational cost associated with solving the forward problem and with repeated construction of the Jacobian, which represents the sensitivity of the measurements to the unknown parameters. Forming the Jacobian can be prohibitively expensive because it requires repeated solutions of the forward and adjoint time-dependent parabolic partial differential equations corresponding to multiple sources and receivers. We propose an efficient method based on a Laplace transform-based exponential time integrator combined with a flexible Krylov subspace approach to solve the resulting shifted systems of equations efficiently. Our proposed solver speeds up the computation of the forward and adjoint problems, thus yielding significant speedup in total inversion time. We consider an application from Transient Hydraulic Tomography (THT), which is an imaging technique to estimate hydraulic parameters related to the subsurface from pressure measurements obtained by a series of pumping tests. The algorithms discussed are applied to a synthetic example taken from THT to demonstrate the resulting computational gains of this proposed method.
Application and sensitivity investigation of Fourier transforms for microwave radiometric inversions
NASA Technical Reports Server (NTRS)
Holmes, J. J.; Balanis, C. A.
1974-01-01
Existing microwave radiometer technology now provides a suitable method for remote determination of the ocean surface's absolute brightness temperature. To extract the brightness temperature of the water from the antenna temperature equation, an unstable Fredholm integral equation of the first kind was solved. Fast Fourier Transform techniques were used to invert the integral after it is placed into a cross-correlation form. Application and verification of the methods to a two-dimensional modeling of a laboratory wave tank system were included. The instability of the Fredholm equation was then demonstrated and a restoration procedure was included which smooths the resulting oscillations. With the recent availability and advances of Fast Fourier Transform techniques, the method presented becomes very attractive in the evaluation of large quantities of data. Actual radiometric measurements of sea water are inverted using the restoration method, incorporating the advantages of the Fast Fourier Transform algorithm for computations.
Abel's Theorem Simplifies Reduction of Order
ERIC Educational Resources Information Center
Green, William R.
2011-01-01
We give an alternative to the standard method of reduction or order, in which one uses one solution of a homogeneous, linear, second order differential equation to find a second, linearly independent solution. Our method, based on Abel's Theorem, is shorter, less complex and extends to higher order equations.
NASA Astrophysics Data System (ADS)
Singh, Anshika; Kumari, Reetu; Kumar, Vinay; Krishnia, Lucky; Naqvi, Zainab; Panwar, Amrish K.; Bhatta, Umananda M.; Ghosh, Arnab; Satyam, P. V.; Tyagi, Pawan K.
2016-01-01
The present study aims to deduce the in-situ response of iron carbide (Fe3C) nanorod filled inside carbon nanotube (CNT) under electron irradiation. Electron irradiation on Fe3C filled-CNT at both high and room temperature (RT) has been performed inside transmission electron microscope. At high temperature (HT), it has been found that γ-Fe atoms in lattice of Fe3C nanorod accumulate first and then form the cluster. These clusters follow the inverse Ostwald ripening whereas if e-irradiation is performed at RT then only the morphological changes in both carbon nanotube as well as nanorod are observed. Compression generated either by electron beam heating or by shrinkage of CNT walls is observed to be a decisive factor.
The clusters Abell 222 and Abell 223: a multi-wavelength view
NASA Astrophysics Data System (ADS)
Durret, F.; Laganá, T. F.; Adami, C.; Bertin, E.
2010-07-01
Context. The Abell 222 and 223 clusters are located at an average redshift z ~ 0.21 and are separated by 0.26 deg. Signatures of mergers have been previously found in these clusters, both in X-rays and at optical wavelengths, thus motivating our study. In X-rays, they are relatively bright, and Abell 223 shows a double structure. A filament has also been detected between the clusters both at optical and X-ray wavelengths. Aims: We analyse the optical properties of these two clusters based on deep imaging in two bands, derive their galaxy luminosity functions (GLFs) and correlate these properties with X-ray characteristics derived from XMM-Newton data. Methods: The optical part of our study is based on archive images obtained with the CFHT Megaprime/Megacam camera, covering a total region of about 1 deg2, or 12.3 × 12.3 Mpc2 at a redshift of 0.21. The X-ray analysis is based on archive XMM-Newton images. Results: The GLFs of Abell 222 in the g' and r' bands are well fit by a Schechter function; the GLF is steeper in r' than in g'. For Abell 223, the GLFs in both bands require a second component at bright magnitudes, added to a Schechter function; they are similar in both bands. The Serna & Gerbal method allows to separate well the two clusters. No obvious filamentary structures are detected at very large scales around the clusters, but a third cluster at the same redshift, Abell 209, is located at a projected distance of 19.2 Mpc. X-ray temperature and metallicity maps reveal that the temperature and metallicity of the X-ray gas are quite homogeneous in Abell 222, while they are very perturbed in Abell 223. Conclusions: The Abell 222/Abell 223 system is complex. The two clusters that form this structure present very different dynamical states. Abell 222 is a smaller, less massive and almost isothermal cluster. On the other hand, Abell 223 is more massive and has most probably been crossed by a subcluster on its way to the northeast. As a consequence, the
Ho, Derek; Kim, Sanghoon; Drake, Tyler K.; Eldridge, Will J.; Wax, Adam
2014-01-01
We present a fast approach for size determination of spherical scatterers using the continuous wavelet transform of the angular light scattering profile to address the computational limitations of previously developed sizing techniques. The potential accuracy, speed, and robustness of the algorithm were determined in simulated models of scattering by polystyrene beads and cells. The algorithm was tested experimentally on angular light scattering data from polystyrene bead phantoms and MCF-7 breast cancer cells using a 2D a/LCI system. Theoretical sizing of simulated profiles of beads and cells produced strong fits between calculated and actual size (r2 = 0.9969 and r2 = 0.9979 respectively), and experimental size determinations were accurate to within one micron. PMID:25360350
Yan, Hui; Yin, Fang-Fang
2008-01-01
In inverse planning for intensity-modulated radiation therapy (IMRT), the dose specification and related weighting factor of an objective function for involved organs is usually predefined by a single value and then iteratively optimized, subject to a set of dose-volume constraints. Because the actual dose distribution is essentially non-uniform and considerably affected by the geometric shape and distribution of the anatomic structures involved, the spatial information regarding those structures should be incorporated such that the predefined parameter distribution is made to approach the clinically expected distribution. Ideally, these parameter distributions should be predefined on a voxel basis in a manual method. However, such an approach is too time-consuming to be feasible in routine use. In the present study, we developed a computer-aided method to achieve the goal described above, producing a non-uniform parameter distribution based on spatial information about the anatomic structures involved. The method consists of two steps: Use distance transformation technique to calculate the distance distribution of the structures. Based on the distance distribution, produce the parameter distribution via a function guided by prior knowledge. We use two simulated cases to examine the effectiveness of the method. The results indicate that application of a non-uniform parameter distribution produced by distance transformation clearly improves dose-sparing of critical organs without compromising dose coverage of the planning target. PMID:18714279
A Strong Merger Shock in Abell 665
NASA Astrophysics Data System (ADS)
Dasadia, S.; Sun, M.; Sarazin, C.; Morandi, A.; Markevitch, M.; Wik, D.; Feretti, L.; Giovannini, G.; Govoni, F.; Vacca, V.
2016-03-01
Deep (103 ks) Chandra observations of Abell 665 have revealed rich structures in this merging galaxy cluster, including a strong shock and two cold fronts. The newly discovered shock has a Mach number of M = 3.0 ± 0.6, propagating in front of a cold disrupted cloud. This makes Abell 665 the second cluster, after the Bullet cluster, where a strong merger shock of M ≈ 3 has been detected. The shock velocity from jump conditions is consistent with (2.7 ± 0.7) × 103 km s-1. The new data also reveal a prominent southern cold front with potentially heated gas ahead of it. Abell 665 also hosts a giant radio halo. There is a hint of diffuse radio emission extending to the shock at the north, which needs to be examined with better radio data. This new strong shock provides a great opportunity to study the re-acceleration model with the X-ray and radio data combined.
NASA Technical Reports Server (NTRS)
Kurtz, M. J.; Huchra, J. P.; Beers, T. C.; Geller, M. J.; Gioia, I. M.
1985-01-01
X-ray and optical observations of the cluster of galaxies Abell 744 are presented. The X-ray flux (assuming H(0) = 100 km/s per Mpc) is about 9 x 10 to the 42nd erg/s. The X-ray source is extended, but shows no other structure. Photographic photometry (in Kron-Cousins R), calibrated by deep CCD frames, is presented for all galaxies brighter than 19th magnitude within 0.75 Mpc of the cluster center. The luminosity function is normal, and the isopleths show little evidence of substructure near the cluster center. The cluster has a dominant central galaxy, which is classified as a normal brightest-cluster elliptical on the basis of its luminosity profile. New redshifts were obtained for 26 galaxies in the vicinity of the cluster center; 20 appear to be cluster members. The spatial distribution of redshifts is peculiar; the dispersion within the 150 kpc core radius is much greater than outside. Abell 744 is similar to the nearby cluster Abell 1060.
Gridding-based direct Fourier inversion of the three-dimensional ray transform.
Penczek, Pawel A; Renka, Robert; Schomberg, Hermann
2004-04-01
We describe a fast and accurate direct Fourier method for reconstructing a function f of three variables from a number of its parallel beam projections. The main application of our method is in single particle analysis, where the goal is to reconstruct the mass density of a biological macromolecule. Typically, the number of projections is extremely large, and each projection is extremely noisy. The projection directions are random and initially unknown. However, it is possible to determine both the directions and f by an iterative procedure; during each stage of the iteration, one has to solve a reconstruction problem of the type considered here. Our reconstruction algorithm is distinguished from other direct Fourier methods by the use of gridding techniques that provide an efficient means to compute a uniformly sampled version of a function g from a nonuniformly sampled version of Fg, the Fourier transform of g, or vice versa. We apply the two-dimensional reverse gridding method to each available projection of f, the function to be reconstructed, in order to obtain Ff on a special spherical grid. Then we use the three-dimensional gridding method to reconstruct f from this sampled version of Ff. This stage requires a proper weighting of the samples of Ff to compensate for their nonuniform distribution. We use a fast method for computing appropriate weights that exploits the special properties of the spherical sampling grid for Ff and involves the computation of a Voronoi diagram on the unit sphere. We demonstrate the excellent speed and accuracy of our method by using simulated data. PMID:15078020
ROSAT HRI images of Abell 85 and Abell 496: Evidence for inhomogeneities in cooling flows
NASA Technical Reports Server (NTRS)
Prestwich, Andrea H.; Guimond, Stephen J.; Luginbuhl, Christian; Joy, Marshall
1994-01-01
We present ROSAT HRI images of two clusters of galaxies with cooling flows, Abell 496 and Abell 85. In these clusters, x-ray emission on small scales above the general cluster emission is significant at the 3 sigma level. There is no evidence for optical counterparts. The enhancements may be associated with lumps of gas at a lower temperature and higher density than the ambient medium, or hotter, denser gas perhaps compressed by magnetic fields. These observations can be used to test models of how thermal instabilities form and evolve in cooling flows.
An improved inversion for FORMOSAT-3/COSMIC ionosphere electron density profiles
NASA Astrophysics Data System (ADS)
Pedatella, N. M.; Yue, X.; Schreiner, W. S.
2015-10-01
An improved method to retrieve electron density profiles from Global Positioning System (GPS) radio occultation (RO) data is presented and applied to Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) observations. The improved inversion uses a monthly grid of COSMIC F region peak densities (NmF2), which are obtained via the standard Abel inversion, to aid the Abel inversion by providing information on the horizontal gradients in the ionosphere. This lessens the impact of ionospheric gradients on the retrieval of GPS RO electron density profiles, reducing the dominant error source in the standard Abel inversion. Results are presented that demonstrate the NmF2 aided retrieval significantly improves the quality of the COSMIC electron density profiles. Improvements are most notable at E region altitudes, where the improved inversion reduces the artificial plasma cave that is generated by the Abel inversion spherical symmetry assumption at low latitudes during the daytime. Occurrence of unphysical negative electron densities at E region altitudes is also reduced. Furthermore, the NmF2 aided inversion has a positive impact at F region altitudes, where it results in a more distinct equatorial ionization anomaly. COSMIC electron density profiles inverted using our new approach are currently available through the University Corporation for Atmospheric Research COSMIC Data Analysis and Archive Center. Owing to the significant improvement in the results, COSMIC data users are encouraged to use electron density profiles based on the improved inversion rather than those inverted by the standard Abel inversion.
The cluster of galaxies Abell 2670
NASA Astrophysics Data System (ADS)
Shambrook, Anouk Aimee
2001-10-01
The rich cluster of galaxies Abell 2670 provides a laboratory in which to observe how galaxy properties change as a function of environment. Though initially considered a relaxed cluster, Abell 2670 exhibits substructure in optical, x-ray, and radio 21 cm H I line data. The cluster hosts a plethora of elliptical galaxies as well as spiral galaxies including galaxies rich in cold gas (some with more than 1010 Msolar in H I), and K+A galaxies. A group of galaxies rich in cold gas may be entering the cluster environment for the first time, making Abell 2670 a valuable case study. This thesis presents a catalog of UBV RI colors for objects located in an area 1° x 1° centered on Abell 2670, based on observations using the CTIO 0.9-m Schmidt telescope. Follow up observations using the Keck II 10-m and the CTIO 4-m telescopes will enable the classification of galaxy morphology. Using evolutionary synthesis models by Poggianti and Barbaro, a photometric redshift analysis yields a best- fit redshift and spectral energy distribution for each galaxy. The results are checked with galaxies observed by Sharples, Ellis, and Gray, which are known cluster members. Radial density profiles of cluster and field galaxies are modeled by King and uniform distributions respectively. A set of simulated galaxies, drawn from a combination of the two models, is compared to the data; for each redshift classification (based on the photometric redshift analysis), Kolmogorov-Smirnov tests characterize the probable fraction of cluster galaxies relative to the total. For the galaxies classified by the photometric redshift analysis as E, Sa, and Sc, an overdensity value is calculated, quantifying the density-morphology relation for this sample. A detailed study of this low redshift (z = 0.076) cluster may inform future studies of high redshift clusters. The optical UBV RI catalog is an important part of a multiwavelength set of data on Abell 2670 which in the future will probably lend itself well
Tauberian theorems for Abel summability of sequences of fuzzy numbers
NASA Astrophysics Data System (ADS)
Yavuz, Enes; ćoşkun, Hüsamettin
2015-09-01
We give some conditions under which Abel summable sequences of fuzzy numbers are convergent. As corollaries we obtain the results given in [E. Yavuz, Ö. Talo, Abel summability of sequences of fuzzy numbers, Soft computing 2014, doi: 10.1007/s00500-014-1563-7].
Konrad-Martin, D; Neely, S T; Keefe, D H; Dorn, P A; Gorga, M P
2001-06-01
Primary and secondary sources combine to produce the 2f1-f2 distortion product otoacoustic emission (DPOAE) measured in the ear canals of humans. DPOAEs were obtained in nine normal-hearing subjects using a fixed-f2 paradigm in which f1 was varied. The f2 was 2 or 4 kHz, and absolute and relative primary levels were varied. Data were obtained with and without a third tone (f3) placed 15.6 Hz below 2f1-f2. The level of f3 was varied in order to suppress the stimulus frequency otoacoustic emission (SFOAE) coming from the 2f1-f2 place. These data were converted from the complex frequency domain into an equivalent time representation using an inverse fast Fourier transform (IFFT). IFFTs of unsuppressed DPOAE data were characterized by two or more peaks. Relative amplitudes of these peaks depended on overall primary level and on primary-level differences. The suppressor eliminated later peaks, but early peaks remained relatively unaltered. Results are interpreted to mean that the DPOAE measured in humans includes components from the f2 place (intermodulation distortion) and DP place (in the form of a SFOAE). These findings build on previous work by providing evidence that multiple peaks in the IFFT are due to a secondary source at the DP place. PMID:11425129
X-ray morphologies of Abell clusters
NASA Technical Reports Server (NTRS)
Mcmillan, S. L. W.; Kowalski, M. P.; Ulmer, M. P.
1989-01-01
Results are presented for X-ray measurements made with the Einstein Observatory's IPC for a sample of 49 Abell clusters, which were used to determine quantitative measures of two morphological parameters of these clusters, the orientation and ellipticity. Consideration is given to the techniques used for estimating and removing background noise in the images and for determining the variation of these parameters with the flux level of a cluster. It was found that most clusters are clearly flattened; for 20 of these clusters, the orientation was unambiguously determined. A catalog of cluster properties is presented.
Mapping the intracluster medium of Abell 3627
NASA Astrophysics Data System (ADS)
Banfield, Julie; Koribalski, Baerbel; Johnston-Hollitt, Melanie; Wong, O. Ivy; Serra, Paolo; Schnitzeler, Dominic; Dehghan, Siamak
2013-10-01
Galaxy clusters are among the largest structures in the Universe. They provide a high density environment where galaxies undergo high-speed collisions, ram pressure stripping, and tidal interactions. The resulting debris can sometimes be detected in the form of neutral or ionised intergalactic filaments. Abell 3627 lies at a distance of ~66kpc right in the heart of the Great Attractor and is one of the most massive clusters known. We propose to map an area of 1 sq. deg. around Abell 3627 at 1 - 3 GHz to study the polarised emission in and between cluster members and search for HI absorption of neutral intracluster gas. We will be able to: (1) test cluster magnetic field turbulence on very small scales; (2) examine rotation measure (RM) spectra to understand the effect of radio sources in cluster environments; (3) detect the intracluster medium (ICM) magnetic field; (4) determine the magnetic field strength of the cluster and place upper limits on the age; and (5) constrain the HI column density in the ICM. All of these goals together will provide information to understand how the large-scale structure of the Universe evolves.
Zantema, A; de Jong, E; Lardenoije, R; van der Eb, A J
1989-01-01
We isolated a monoclonal antibody that immunoprecipitated two proteins of 22 and 27 kilodaltons (kDa) from nononcogenic adenovirus type 5 early region 1 (E1)-transformed rat cells but not from oncogenic adenovirus type 12 E1-transformed rat cells. In a variety of adenovirus-transformed cells including cells transformed by E1A and the c-H-ras oncogene, we found a perfect, inverse correlation between the presence of these two proteins and the oncogenicity of these cells in syngeneic immunocompetent rats. Characterization of the two proteins revealed that they occur in a large (700-kDa) complex and that the 27-kDa protein is identical to the already known 27-kDa (28-kDa) heat shock protein hsp27. The suppression of the hsp27 protein in oncogenic cells is further demonstrated by the fact that its mRNA is absent even after heat-shock induction. Images PMID:2746733
Wen Junhai; Liang Zhengrong
2006-03-15
Inverting the exponential Radon transform has a potential use for SPECT (single photon emission computed tomography) imaging in cases where a uniform attenuation can be approximated, such as in brain and abdominal imaging. Tretiak and Metz derived in the frequency domain an explicit inversion formula for the exponential Radon transform in two dimensions for parallel-beam collimator geometry. Progress has been made to extend the inversion formula for fan-beam and varying focal-length fan-beam (VFF) collimator geometries. These previous fan-beam and VFF inversion formulas require a spatially variant filtering operation, which complicates the implementation and imposes a heavy computing burden. In this paper, we present an explicit inversion formula, in which a spatially invariant filter is involved. The formula is derived and implemented in the spatial domain for VFF geometry (where parallel-beam and fan-beam geometries are two special cases). Phantom simulations mimicking SPECT studies demonstrate its accuracy in reconstructing the phantom images and efficiency in computation for the considered collimator geometries.
NASA Technical Reports Server (NTRS)
Schlegel, Todd T.; Cortez, Daniel
2010-01-01
Our primary objective was to ascertain which commonly used 12-to-Frank-lead transformation yields spatial QRS-T angle values closest to those obtained from simultaneously collected true Frank-lead recordings. Simultaneous 12-lead and Frank XYZ-lead recordings were analyzed for 100 post-myocardial infarction patients and 50 controls. Relative agreement, with true Frank-lead results, of 12-to-Frank-lead transformed results for the spatial QRS-T angle using Kors regression versus inverse Dower was assessed via ANOVA, Lin s concordance and Bland-Altman plots. Spatial QRS-T angles from the true Frank leads were not significantly different than those derived from the Kors regression-related transformation but were significantly smaller than those derived from the inverse Dower-related transformation (P less than 0.001). Independent of method, spatial mean QRS-T angles were also always significantly larger than spatial maximum (peaks) QRS-T angles. Spatial QRS-T angles are best approximated by regression-related transforms. Spatial mean and spatial peaks QRS-T angles should also not be used interchangeably.
NASA Astrophysics Data System (ADS)
Wei, Yuchun; Cheng, Chunmei; Wang, Lei; Zhang, Jing
2010-10-01
Estimation and monitoring Chlorophyll-a concentration (CHLA), especially low CHLA in lake using remote sensing data is very important for early warning of blue-green algal bloom. In spite of better overall goodness fit in three-band CHLA inversion model of turbidity water proposed by Gitelson, the estimation errors of samples with low CHLA are often higher, and this kind of error has great influence on the evaluation of lake nutritional status. In this paper, two methods of data transformation-logarithm of CHLA and continuum removal of spectrum-were used to decrease model error. Data set includes the routine monitoring sampling data collected from June to September, 2004 in Taihu Lake and field data in March, 2010 in Meiliangwan of Taihu Lake. Water surface spectrum data were measured in situ by ASD FieldPro. Comparative analysis showed that both logarithm transformation (LT) and continuum removal transformation (CRT) can increase model's accuracy. For all sample data, the average relative accuracy of model built by data after LT increased by 30%, and that of model built by data after LT and CRT increased by 35%. For the samples with CHLA lower than 50μg/L, the average relative error decreased from 76% of model built by data without transformation to 36% of LT and 27% of LT and CRT. The paper concluded that data transform is a simple and effective method to increase precision of CHLA remote sensing inversion.
Are Abell Clusters Correlated with Gamma-Ray Bursts?
NASA Technical Reports Server (NTRS)
Hurley, K.; Hartmann, D.; Kouveliotou, C.; Fishman, G.; Laros, J.; Cline, T.; Boer, M.
1997-01-01
A recent study has presented marginal statistical evidence that gamma-ray burst (GRB) sources are correlated with Abell clusters, based on analyses of bursts in the BATSE 3B catalog. Using precise localization information from the Third Interplanetary Network, we have reanalyzed this possible correlation. We find that most of the Abell clusters that are in the relatively large 3B error circles are not in the much smaller IPN/BATSE error regions. We believe that this argues strongly against an Abell cluster-GRB correlation.
Quantification of Substructure in Nearby Abell Clusters
NASA Astrophysics Data System (ADS)
Kriessler, J. R.; Beers, T. C.; Odewahn, S. C.
1995-05-01
Theory, as well as numerical simulations, suggests that Omega_o may be observationally constrained by the amount of substructure observed in present-day clusters of galaxies. We have therefore begun a study of the 116 Abell clusters with richness class greater than or equal to 1 and distance class less than or equal to 4, the so-called ``volume-limited'' sample of Hoessel, Gunn, & Thuan 1980 (ApJ 241, 486) to determine the prevalence of substructure in the clusters' projected galaxy positions. We use positions of galaxies identified by the Minnesota Automated Plate Scanner to obtain contour plots of the available clusters using an adaptive kernel routine. Significance of substructure is evaluated using the 2-D Lee test as well as a likelihood-ratio test on fits made with mixtures of two-dimensional gaussians. We also present nonparametric density profile estimates obtained with the program MAPEL (Merritt and Tremblay 1994, AJ 108, 514).
The genus curve of the Abell clusters
NASA Technical Reports Server (NTRS)
Rhoads, James E.; Gott, J. Richard, III; Postman, Marc
1994-01-01
We study the topology of large-scale structure through a genus curve measurement of the recent Abell catalog redshift survey of Postman, Huchra, and Geller (1992). The structure is found to be spongelike near median density and to exhibit isolated superclusters and voids at high and low densities, respectively. The genus curve shows a slight shift toward 'meatball' topology, but remains consistent with the hypothesis of Gaussian random phase initial conditions. The amplitude of the genus curve corresponds to a power-law spectrum with index n = 0.21(sub -0.47 sup +0.43) on scales of 48/h Mpc or to a cold dark matter power spectrum with omega h = 0.36(sub -0.17 sup +0.46).
The magnitude-redshift relation for 561 Abell clusters
NASA Technical Reports Server (NTRS)
Postman, M.; Huchra, J. P.; Geller, M. J.; Henry, J. P.
1985-01-01
The Hubble diagram for the 561 Abell clusters with measured redshifts has been examined using Abell's (1958) corrected photo-red magnitudes for the tenth-ranked cluster member (m10). After correction for the Scott effect and K dimming, the data are in good agreement with a linear magnitude-redshift relation with a slope of 0.2 out to z = 0.1. New redshift data are also presented for 20 Abell clusters. Abell's m10 is suitable for redshift estimation for clusters with m10 of no more than 16.5. At fainter m10, the number of foreground galaxies expected within an Abell radius is large enough to make identification of the tenth-ranked galaxy difficult. Interlopers bias the estimated redshift toward low values at high redshift. Leir and van den Bergh's (1977) redshift estimates suffer from this same bias but to a smaller degree because of the use of multiple cluster parameters. Constraints on deviations of cluster velocities from the mean cosmological flow require greater photometric accuracy than is provided by Abell's m10 magnitudes.
Separating the BL Lac and cluster X-ray emissions in Abell 689 with Chandra
NASA Astrophysics Data System (ADS)
Giles, P. A.; Maughan, B. J.; Birkinshaw, M.; Worrall, D. M.; Lancaster, K.
2012-01-01
We present the results of a Chandra observation of the galaxy cluster Abell 689 (z = 0.279). Abell 689 is one of the most luminous clusters detected in the ROSAT All Sky Survey (RASS), but was flagged as possibly including significant point source contamination. The small point spread function of the Chandra telescope allows us to confirm this and separate the point source from the extended cluster X-ray emission. For the cluster, we determine a bolometric luminosity of Lbol= (3.3 ± 0.3) × 1044 erg s-1 and a temperature of kT = 5.1+2.2- 1.3 keV when including a physically motivated background model. We compare our measured luminosity for A689 to that quoted in the RASS, and find L0.1-2.4 keV= 2.8 × 1044 erg s-1, a value ˜10 times lower than the ROSAT measurement. Our analysis of the point source shows evidence for significant pile-up, with a pile-up fraction of ≃60 per cent. Sloan Digital Sky Survey spectra and Hubble Space Telescope (HST) images lead us to the conclusion that the point source within Abell 689 is a BL Lac object. Using radio and optical observations from the Very Large Array and HST archives, we determine αro= 0.50, αox= 0.77 and αrx= 0.58 for the BL Lac, which would classify it as being of 'high-energy peak BL Lac' type. Spectra extracted of A689 show a hard X-ray excess at energies above 6 keV that we interpret as inverse-Compton emission from aged electrons that may have been transported into the cluster from the BL Lac.
NASA Technical Reports Server (NTRS)
Rummel, R.; Sjoeberg, L.; Rapp, R. H.
1978-01-01
A numerical method for the determination of gravity anomalies from geoid heights is described using the inverse Stokes formula. This discrete form of the inverse Stokes formula applies a numerical integration over the azimuth and an integration over a cubic interpolatory spline function which approximates the step function obtained from the numerical integration. The main disadvantage of the procedure is the lack of a reliable error measure. The method was applied on geoid heights derived from GEOS-3 altimeter measurements in the calibration area of the GEOS-3 satellite.
Noo, Frédéric; Clackdoyle, Rolf; Wagner, Jean-Marc
2002-08-01
This work presents new mathematical results on the inversion of the exponential x-ray transform. It is shown that a reconstruction formula can be obtained for any dataset whose projection directions consist of a union of half great circles on the unit sphere. A basic example of such a dataset is the semi-equatorial band. The discussion in the paper is mostly focused on this example. The reconstruction formula takes the form of a Neumann (geometric) series and is both exact and stable. The exponential x-ray transform has been mainly studied in SPECT imaging. In this context, our results demonstrate mathematically that fully 3D image reconstruction in SPECT with non-zero attenuation does not always require symmetric datasets (opposing views). PMID:12200935
Chandra View of Galaxy Cluster Abell 2554
NASA Astrophysics Data System (ADS)
kıyami Erdim, Muhammed; Hudaverdi, Murat
2016-07-01
We study the structure of the galaxy cluster Abell 2554 at z = 0.11, which is a member of Aquarius Super cluster using the Chandra archival data. The X-ray peak coincides with a bright elliptical cD galaxy. Slightly elongated X-ray plasma has an average temperature and metal abundance values of ˜6 keV and 0.28 solar, respectively. We observe small-scale temperature variations in the ICM. There is a significantly hot wall-like structure with 9 keV at the SE and also radio-lope locates at the tip of this hot region. A2554 is also part of a trio-cluster. Its close neighbors A2550 (at SW) and A2556 (at SE) have only 2 Mpc and 1.5 Mpc separations with A2554. Considering the temperature fluctuations and the dynamical environment of super cluster, we examine the possible ongoing merger scenarios within A2554.
Abell 1033: birth of a radio phoenix
NASA Astrophysics Data System (ADS)
de Gasperin, F.; Ogrean, G. A.; van Weeren, R. J.; Dawson, W. A.; Brüggen, M.; Bonafede, A.; Simionescu, A.
2015-04-01
Extended steep-spectrum radio emission in a galaxy cluster is usually associated with a recent merger. However, given the complex scenario of galaxy cluster mergers, many of the discovered sources hardly fit into the strict boundaries of a precise taxonomy. This is especially true for radio phoenixes that do not have very well defined observational criteria. Radio phoenixes are aged radio galaxy lobes whose emission is reactivated by compression or other mechanisms. Here, we present the detection of a radio phoenix close to the moment of its formation. The source is located in Abell 1033, a peculiar galaxy cluster which underwent a recent merger. To support our claim, we present unpublished Westerbork Synthesis Radio Telescope and Chandra observations together with archival data from the Very Large Array and the Sloan Digital Sky Survey. We discover the presence of two subclusters displaced along the N-S direction. The two subclusters probably underwent a recent merger which is the cause of a moderately perturbed X-ray brightness distribution. A steep-spectrum extended radio source very close to an active galactic nucleus (AGN) is proposed to be a newly born radio phoenix: the AGN lobes have been displaced/compressed by shocks formed during the merger event. This scenario explains the source location, morphology, spectral index, and brightness. Finally, we show evidence of a density discontinuity close to the radio phoenix and discuss the consequences of its presence.
The SAMI Pilot Survey: stellar kinematics of galaxies in Abell 85, 168 and 2399
NASA Astrophysics Data System (ADS)
Fogarty, L. M. R.; Scott, N.; Owers, M. S.; Croom, S. M.; Bekki, K.; Houghton, R. C. W.; van de Sande, J.; D'Eugenio, F.; Cecil, G. N.; Colless, M. M.; Bland-Hawthorn, J.; Brough, S.; Cortese, L.; Davies, R. L.; Jones, D. H.; Pracy, M.; Allen, J. T.; Bryant, J. J.; Goodwin, M.; Green, A. W.; Konstantopoulos, I. S.; Lawrence, J. S.; Lorente, N. P. F.; Richards, S.; Sharp, R. G.
2015-12-01
We present the SAMI Pilot Survey, consisting of integral field spectroscopy of 106 galaxies across three galaxy clusters, Abell 85, Abell 168 and Abell 2399. The galaxies were selected by absolute magnitude to have Mr < -20.25 mag. The survey, using the Sydney-AAO Multi-object Integral field spectrograph (SAMI), comprises observations of galaxies of all morphological types with 75 per cent of the sample being early-type galaxies (ETGs) and 25 per cent being late-type galaxies (LTGs). Stellar velocity and velocity dispersion maps are derived for all 106 galaxies in the sample. The λR parameter, a proxy for the specific stellar angular momentum, is calculated for each galaxy in the sample. We find a trend between λR and galaxy concentration such that LTGs are less concentrated higher angular momentum systems, with the fast-rotating ETGs (FRs) more concentrated and lower in angular momentum. This suggests that some dynamical processes are involved in transforming LTGs to FRs, though a significant overlap between the λR distributions of these classes of galaxies implies that this is just one piece of a more complicated picture. We measure the kinematic misalignment angle, Ψ, for the ETGs in the sample, to probe the intrinsic shapes of the galaxies. We find the majority of FRs (83 per cent) to be aligned, consistent with them being oblate spheroids (i.e. discs). The slow rotating ETGs (SRs), on the other hand, are significantly more likely to show kinematic misalignment (only 38 per cent are aligned). This confirms previous results that SRs are likely to be mildly triaxial systems.
NASA Astrophysics Data System (ADS)
Hsu, Annjia T.; Hunter, William W.; Schmalbrock, Petra; Marshall, Alan G.
Proton NMR spectroscopy for the in vivo study of metabolites in a spatially resolved region with a clinical NMR imaging device must contend with the 70% hydration of normal man. Theoretical and experimental comparisons of several excitation waveforms designed to suppress the H 2O signal in proton NMR spectroscopy and chemical shift imaging have been conducted. In particular, we have compared the 1 overline33 overline1 and 1 overline1 pulse sequences with those obtained via a stored waveform inverse Fourier-transform (SWIFT) time-domain apodized waveform generated by inverse Fourier transformation of a quadratically phase-encoded excitation magnitude spectrum. Theoretical excitation profiles are compared to those measured in a slice selected with a General Electric Signa 1.5 T whole-body imaging system, and demonstrated for a phantom (toluene, dioxane, and dichloromethane). The SWIFT waveform is theoretically and experimentally superior to 1 overline1 and 1 overline33 overline1 for selective suppression of one spectral segment with simultaneous uniform excitation over the rest of the spectral frequency range. SWIFT-excited water-suppressed depth-resolved chemical shift spectra are demonstrated for human brain and human calf muscle of normal volunteers.
NASA Astrophysics Data System (ADS)
Basile, C.; Maillard, A.; Patriat, M.; Gaullier, V.; Loncke, L.; Roest, W.; Mercier de Lépinay, M.; Pattier, F.
2013-04-01
We present the structure and evolution of the eastern part of the Demerara plateau, offshore French Guiana, from the analysis of geophysical data collected during GUYAPLAC cruise. This area is located at the intersection of a transform segment and a divergent segment of a continental margin related to the Early Cretaceous opening of the Equatorial Atlantic. The main structures are NNE-SSW to NNW-SSE trending normal faults on the eastern edge of the plateau, and WNW-ESE to NW-SE trending acoustic basement ridges on its northern edge. When replaced in their Albian position, these structures appear to be parallel to the coeval oceanic accretion axis and transform faults, respectively. The most striking structures are related to a post-rift but syn-transform tectonic inversion, producing E-W to WNW-ESE trending folds, sealed by a regional unconformity. This shortening cannot be related to ridge push, but is probably related to a plate kinematic change 105 My ago, that modified the deformation in the vicinity of the transform fault. Late post-rift evolution also includes a significant Tertiary oceanward tilt of the edge of the Demerara plateau. The driving mechanism of this late tilt is unclear, but may be related to a lithospheric flexure resulting from the loading of the abyssal plain by the Orinoco and Amazon deep-sea fans.
NASA Astrophysics Data System (ADS)
Ansari, R.; Campagne, J. E.; Colom, P.; Ferrari, C.; Magneville, Ch.; Martin, J. M.; Moniez, M.; Torrentó, A. S.
2016-02-01
We have observed regions of three galaxy clusters at z˜[0.06÷0.09] (Abell85, Abell1205, Abell2440) with the Nançay radiotelescope (NRT) to search for 21 cm emission and to fully characterize the FPGA based BAORadio digital backend. We have tested the new BAORadio data acquisition system by observing sources in parallel with the NRT standard correlator (ACRT) back-end over several months. BAORadio enables wide band instantaneous observation of the [1250,1500] MHz frequency range, as well as the use of powerful RFI mitigation methods thanks to its fine time sampling. A number of questions related to instrument stability, data processing and calibration are discussed. We have obtained the radiometer curves over the integration time range [0.01,10 000] seconds and we show that sensitivities of few mJy over most of the wide frequency band can be reached with the NRT. It is clearly shown that in blind line search, which is the context of H I intensity mapping for Baryon Acoustic Oscillations, the new acquisition system and processing pipeline outperforms the standard one. We report a positive detection of 21 cm emission at 3 σ-level from galaxies in the outer region of Abell85 at ≃1352 MHz (14400 km/s) corresponding to a line strength of ≃0.8 Jy km/s. We also observe an excess power around ≃1318 MHz (21600 km/s), although at lower statistical significance, compatible with emission from Abell1205 galaxies. Detected radio line emissions have been cross matched with optical catalogs and we have derived hydrogen mass estimates.
LACKS,S.A.
2003-10-09
Transformation, which alters the genetic makeup of an individual, is a concept that intrigues the human imagination. In Streptococcus pneumoniae such transformation was first demonstrated. Perhaps our fascination with genetics derived from our ancestors observing their own progeny, with its retention and assortment of parental traits, but such interest must have been accelerated after the dawn of agriculture. It was in pea plants that Gregor Mendel in the late 1800s examined inherited traits and found them to be determined by physical elements, or genes, passed from parents to progeny. In our day, the material basis of these genetic determinants was revealed to be DNA by the lowly bacteria, in particular, the pneumococcus. For this species, transformation by free DNA is a sexual process that enables cells to sport new combinations of genes and traits. Genetic transformation of the type found in S. pneumoniae occurs naturally in many species of bacteria (70), but, initially only a few other transformable species were found, namely, Haemophilus influenzae, Neisseria meningitides, Neisseria gonorrheae, and Bacillus subtilis (96). Natural transformation, which requires a set of genes evolved for the purpose, contrasts with artificial transformation, which is accomplished by shocking cells either electrically, as in electroporation, or by ionic and temperature shifts. Although such artificial treatments can introduce very small amounts of DNA into virtually any type of cell, the amounts introduced by natural transformation are a million-fold greater, and S. pneumoniae can take up as much as 10% of its cellular DNA content (40).
Barysz, Maria; Mentel, Lukasz; Leszczynski, Jerzy
2009-04-28
The two-component Hamiltonian of the infinite-order two-component (IOTC) theory is obtained by a unitary block-diagonalizing transformation of the Dirac-Hamiltonian. Once the IOTC spin orbitals are calculated, they can be back transformed into four-component solutions. The transformed four component solutions are then used to evaluate different moments of the electron density distribution. This formally exact method may, however, suffer from certain approximations involved in its numerical implementation. As shown by the present study, with sufficiently large basis set of Gaussian functions, the Dirac values of these moments are fully recovered in spite of using the approximate identity resolution into eigenvectors of the p{sup 2} operator.
A 1400-MHz survey of 1478 Abell clusters of galaxies
NASA Technical Reports Server (NTRS)
Owen, F. N.; White, R. A.; Hilldrup, K. C.; Hanisch, R. J.
1982-01-01
Observations of 1478 Abell clusters of galaxies with the NRAO 91-m telescope at 1400 MHz are reported. The measured beam shape was deconvolved from the measured source Gaussian fits in order to estimate the source size and position angle. All detected sources within 0.5 corrected Abell cluster radii are listed, including the cluster number, richness class, distance class, magnitude of the tenth brightest galaxy, redshift estimate, corrected cluster radius in arcmin, right ascension and error, declination and error, total flux density and error, and angular structure for each source.
Radio Galaxies in Abell Rich Clusters
NASA Astrophysics Data System (ADS)
Ledlow, M. J.
1994-05-01
We have defined a complete sample of radio galaxies chosen from Abell's northern catalog consisting of all clusters with measured redshifts < 0.09. This sample consists of nearly 300 clusters. A multiwavelength survey including optical CCD R-Band imaging, optical spectroscopy, and VLA 20 cm radio maps has been compiled. I have used this database to study the optical/radio properties of radio galaxies in the cluster environment. In particular, optical properties have been compared to a radio-quiet selected sample to look for optical signatures which may distinguish radio galaxies from normal radio-quiet ellipticals. The correlations between radio morphology and galaxy type, the optical dependence of the FR I/II break, and the univariate and bivariate luminosity functions have been examined for this sample. This study is aimed at understanding radio galaxies as a population and examining their status in the AGN heirarchy. The results of this work will be applied to models of radio source evolution. The results from the optical data analysis suggest that radio galaxies, as a class, cannot be distinguished from non-radio selected elliptical galaxies. The magnitude/size relationship, the surface-brightness profiles, the fundamental plane, and the intrinsic shape of the radio galaxies are consistent between our radio galaxy and control sample. The radio galaxies also trace the elliptical galaxy optical luminosity function in clusters very well; with many more L(*) galaxies than brightest cluster members. Combined with the results of the spectroscopy, the data are consistent with the idea that all elliptical galaxies may at some point in their lifetimes become radio sources. In conclusion, I present a new observational picture for radio galaxies and discuss the important properties which may determine the evolution of individual sources.
LensPerfect Analysis of Abell 1689
NASA Astrophysics Data System (ADS)
Coe, Dan A.
2007-12-01
I present the first massmap to perfectly reproduce the position of every gravitationally-lensed multiply-imaged galaxy detected to date in ACS images of Abell 1689. This massmap was obtained using a powerful new technique made possible by a recent advance in the field of Mathematics. It is the highest resolution assumption-free Dark Matter massmap to date, with the resolution being limited only by the number of multiple images detected. We detect 8 new multiple image systems and identify multiple knots in individual galaxies to constrain a grand total of 168 knots within 135 multiple images of 42 galaxies. No assumptions are made about mass tracing light, and yet the brightest visible structures in A1689 are reproduced in our massmap, a few with intriguing positional offsets. Our massmap probes radii smaller than that resolvable in current Dark Matter simulations of galaxy clusters. And at these radii, we observe slight deviations from the NFW and Sersic profiles which describe simulated Dark Matter halos so well. While we have demonstrated that our method is able to recover a known input massmap (to limited resolution), further tests are necessary to determine the uncertainties of our mass profile and positions of massive subclumps. I compile the latest weak lensing data from ACS, Subaru, and CFHT, and attempt to fit a single profile, either NFW or Sersic, to both the observed weak and strong lensing. I confirm the finding of most previous authors, that no single profile fits extremely well to both simultaneously. Slight deviations are revealed, with the best fits slightly over-predicting the mass profile at both large and small radius. Our easy-to-use software, called LensPerfect, will be made available soon. This research was supported by the European Commission Marie Curie International Reintegration Grant 017288-BPZ and the PNAYA grant AYA2005-09413-C02.
The Merger Dynamics of Abell 2061
NASA Astrophysics Data System (ADS)
Bailey, Avery; Sarazin, Craig L.; Clarke, Tracy E.; Chatzikos, Marios; Hogge, Taylor; Wik, Daniel R.; Rudnick, Lawrence; Farnsworth, Damon; Van Weeren, Reinout J.; Brown, Shea
2016-04-01
Abell 2061, a galaxy cluster at a redshift of z=.0784 in the Corona Borealis Supercluster, displays features in both the X-ray and radio indicative of merger activity. Observations by the GBT and the Westerbork Northern Sky Survey (WENSS) have indicated the presence of an extended, central radio halo/relic coincident with the cluster's main X-ray emission and a bright radio relic to the SW of the center of the cluster. Previous observations by ROSAT, Beppo-SAX, and Chandra show an elongated structure (referred to as the ‘Plume’), emitting in the soft X-ray and stretching to the NE of the cluster’s center. The Beppo-SAX and Chandra observations also suggest the presence of a hard X-ray shock slightly NE of the cluster’s center. Here we present the details of an August 2013 XMM-Newton observation of A2061 which has greater field of view and longer exposure (48.6 ks) than the previous Chandra observation. We present images displaying the cluster’s soft and hard X-ray emission and also a temperature map of the cluster. This temperature map highlights the presence of a previously unseen cool region of the cluster which we hypothesize to be the cool core of one of the subclusters involved in this merger. We also discuss the structural similarity of this cluster with a simulated high mass-ratio offset cluster merger taken from the Simulation Library of Astrophysical cluster Mergers (SLAM). This simulation would suggest that the Plume is gas from the cool core of a subcluster which is now falling back into the center of the cluster after initial core passage.
ERIC Educational Resources Information Center
Iqbal, M.
2002-01-01
In this paper we have converted the Laplace transform into an integral equation of the first kind of convolution type, which is an ill-posed problem, and used a statistical regularization method to solve it. The method is applied to three examples. It gives a good approximation to the true solution and compares well with the method given by…
Baker, W.R.
1959-08-25
Transformers of a type adapted for use with extreme high power vacuum tubes where current requirements may be of the order of 2,000 to 200,000 amperes are described. The transformer casing has the form of a re-entrant section being extended through an opening in one end of the cylinder to form a coaxial terminal arrangement. A toroidal multi-turn primary winding is disposed within the casing in coaxial relationship therein. In a second embodiment, means are provided for forming the casing as a multi-turn secondary. The transformer is characterized by minimized resistance heating, minimized external magnetic flux, and an economical construction.
Cleaver, J.E. )
1989-01-01
Human cells transformed by simian virus 40 (SV40) are more sensitive to killing by ultraviolet light when grown in caffeine after irradiation. The degree of sensitization at 2 mM caffeine (expressed as the ratio of the 37% survival dose for control cells divided by the 37% survival dose for cells grown in caffeine, i.e., the dose modification factor) was approximately 1.9 in transformed normal cells and 3.8-5.8 in excision-defective xeroderma pigmentosum (XP) groups A, C, and D cells. A large dose modification factor of 12 was observed in a transformed XP variant cell line. Chinese hamster ovary cells were not significantly different from transformed normal human cells, with a maximum dose modification factor of 1.5. Two radioresistant XP revertants that do not excise cyclobutane dimers gave different responses; one resembled its group A parent in being sensitized by caffeine, and one did not. These results can be interpreted on the basis of a single hypothesis that cells are killed as a result of attempts to replicate damaged DNA. Increased replication rates caused by transformation, increased numbers of replication forks in DNA caused by caffeine, and increased numbers of damaged sites ahead of replication forks in excision-defective cells are all processes that will consequently increase killing according to this hypothesis. A corollary is that the XP variant may be highly sensitized to caffeine because of excision defects at the DNA replication forks, an idea that may be important in designing cloning strategies for the XP variant gene.
Mass Profile of Abell 2204 An X-Ray Analysis of Abell 2204 using XMM-Newton Data
Lau, Travis
2003-09-05
The vast majority of the matter in the universe is of an unknown type. This matter is called dark matter by astronomers. The dark matter manifests itself only through gravitational interaction and is otherwise undetectable. The distribution of this matter in can be better understood by studying the mass profile of galaxy clusters. The X-ray emissions of the galaxy cluster Abell 2204 were analyzed using archived data from the XMM-Newton space telescope. We analyze a 40ks observation of Abell 2204 and present a radial temperature and radial mass profile based on hydrostatic equilibrium calculations.
Bracken, Robert E.
2004-01-01
A subroutine (FFTDC2) coded in Fortran 77 is described, which performs a Fast Fourier Transform or Discrete Fourier Transform together with necessary conditioning steps of trend removal, extension, and windowing. The source code for the entire library of required subroutines is provided with the digital release of this report. But, there is only one required entry point, the subroutine call to FFTDC2; all the other subroutines are operationally transparent to the user. Complete instructions for use of FFTDC2.F (as well as for all the other subroutines) and some practical theoretical discussions are included as comments at the beginning of the source code. This subroutine is intended to be an efficient tool for the programmer in a variety of production-level signal-processing applications.
Zhan, X.
2005-01-01
A parallel Fortran-MPI (Message Passing Interface) software for numerical inversion of the Laplace transform based on a Fourier series method is developed to meet the need of solving intensive computational problems involving oscillatory water level's response to hydraulic tests in a groundwater environment. The software is a parallel version of ACM (The Association for Computing Machinery) Transactions on Mathematical Software (TOMS) Algorithm 796. Running 38 test examples indicated that implementation of MPI techniques with distributed memory architecture speedups the processing and improves the efficiency. Applications to oscillatory water levels in a well during aquifer tests are presented to illustrate how this package can be applied to solve complicated environmental problems involved in differential and integral equations. The package is free and is easy to use for people with little or no previous experience in using MPI but who wish to get off to a quick start in parallel computing. ?? 2004 Elsevier Ltd. All rights reserved.
AGES Observations of Abell1367 and its Outskirts
NASA Astrophysics Data System (ADS)
Cortese, L.; Minchin, R. F.; Auld, R. R.; Davies, J. I.; Catinella, B.; Momjian, E.; Rosenberg, J. L.; O'Neil, K.
2007-05-01
The Arecibo Galactic Environment Survey (AGES) will map over the next years ˜200 square degrees using the ALFA feed array at the 305-m Arecibo Telescope. AGES is specifically designed to investigate various galactic environments from local voids to interacting groups and cluster of galaxies. AGES will map 20 square degrees in the Coma-Abell1367 supercluster covering all the Abell cluster 1367 and its outskirts (˜2 virial radii). In Spring 2006 we nearly completed the observations of 5 square degrees in the range (11:34
Retrieval Performance and Indexing Differences in ABELL and MLAIB
ERIC Educational Resources Information Center
Graziano, Vince
2012-01-01
Searches for 117 British authors are compared in the Annual Bibliography of English Language and Literature (ABELL) and the Modern Language Association International Bibliography (MLAIB). Authors are organized by period and genre within the early modern era. The number of records for each author was subdivided by format, language of publication,…
Arnott, W P; Schmitt, C; Liu, Y; Hallett, J
1997-07-20
Infrared extinction optical depth (500-5000 cm(-1)) has been measured with a Fourier transform infrared spectrometer for clouds produced with an ultrasonic nebulizer. Direct measurement of the cloud droplet size spectra agree with size spectra retrieved from inversion of the extinction measurements. Both indicate that the range of droplet sizes is 1-14 mum. The retrieval was accomplished with an iterative algorithm that simultaneously obtains water-vapor concentration. The basis set of droplet extinction functions are computed once by using numerical integration of the Lorenz-Mie theory over narrow size bins, and a measured water-vapor extinction curve was used. Extinction and size spectra are measured and computed for both steady-state and dissipating clouds. It is demonstrated that anomalous diffraction theory produces relatively poor droplet size and synthetic extinction spectra and that extinction measurements are helpful in assessing the validity of various theories. Calculations of cloud liquid-water content from retrieved size distributions agree with a parameterization based on optical-depth measurements at a wave number of 906 cm(-1) for clouds that satisfy the size spectral range assumptions of the parameterization. Significance of droplet and vapor contribution to the total optical depth is used to evaluate the reliability of spectral inversions. PMID:18259335
The Morphological Decomposition of Abell 868
NASA Astrophysics Data System (ADS)
Driver, S. P.; Odewahn, S. C.; Echevarria, L.; Cohen, S. H.; Windhorst, R. A.; Phillipps, S.; Couch, W. J.
2003-12-01
We report on the morphological luminosity functions (LFs) and radial profiles derived for the galaxy population within the rich cluster Abell 868 (z=0.153) based purely on Hubble Space Telescope imaging in F606W. We recover Schechter functions (-24.0
NASA Astrophysics Data System (ADS)
Bauer, R.; Hansen, M.; Hansen, S.; Øgendal, L.; Lomholt, S.; Qvist, K.; Horne, D.
1995-08-01
Aggregation of casein micelles after addition of the proteolytic enzyme chymosin has been studied by static and dynamic light scattering at three different concentrations of casein corresponding to dilutions 1:100, 1:500, and 1:1000 of native milk. The static light scattering data have been analyzed by an indirect Fourier transformation method which gives the distance distributions as a function of time. From these curves radius of gyration and an average number of casein micelles in the aggregates have been derived as a function of time. The dynamic light scattering experiments give the hydrodynamic radius as a function of time after the addition of rennet. The initial radius of gyration for the intact casein micelles is 140 nm. The corresponding hydrodynamic radius is also 140 nm. This shows that the casein micelles are not solid spheres. Inspection of a plot of relative mass versus radius of gyration for the aggregates appearing after the addition of chymosin shows that two processes take place. First extended linear aggregates are built up to a relative mass of the aggregates of about 10 and then restructuring of aggregates occurs such that increasingly compact objects are formed. Whereas the first process exhibits a relatively fast growth in size, the aggregates grow slowly in size during the second process. Further evidence of the formation of linear aggregates followed by more dense aggregates was obtained by forming the ratio between the radius of gyration and the hydrodynamic radius. This ratio increases to values of about 2.5 (indicating that linearly extended molecules are present followed) by a decrease to about 1. The log-log plot of mass versus radius of gyration is linear up to relative masses of about 10 with a slope of about 2. This extends up to sizes of 1 μm in diameter. The slope then increases to values indicating branching and thereby the formation of more compact aggregates. For relative masses below 10 and sizes below 1 μm sedimentation is
Basis set expansion for inverse problems in plasma diagnostic analysis.
Jones, B; Ruiz, C L
2013-07-01
A basis set expansion method [V. Dribinski, A. Ossadtchi, V. A. Mandelshtam, and H. Reisler, Rev. Sci. Instrum. 73, 2634 (2002)] is applied to recover physical information about plasma radiation sources from instrument data, which has been forward transformed due to the nature of the measurement technique. This method provides a general approach for inverse problems, and we discuss two specific examples relevant to diagnosing fast z pinches on the 20-25 MA Z machine [M. E. Savage, L. F. Bennett, D. E. Bliss, W. T. Clark, R. S. Coats, J. M. Elizondo, K. R. LeChien, H. C. Harjes, J. M. Lehr, J. E. Maenchen, D. H. McDaniel, M. F. Pasik, T. D. Pointon, A. C. Owen, D. B. Seidel, D. L. Smith, B. S. Stoltzfus, K. W. Struve, W. A. Stygar, L. K. Warne, J. R. Woodworth, C. W. Mendel, K. R. Prestwich, R. W. Shoup, D. L. Johnson, J. P. Corley, K. C. Hodge, T. C. Wagoner, and P. E. Wakeland, in Proceedings of the Pulsed Power Plasma Sciences Conference (IEEE, 2007), p. 979]. First, Abel inversion of time-gated, self-emission x-ray images from a wire array implosion is studied. Second, we present an approach for unfolding neutron time-of-flight measurements from a deuterium gas puff z pinch to recover information about emission time history and energy distribution. Through these examples, we discuss how noise in the measured data limits the practical resolution of the inversion, and how the method handles discontinuities in the source function and artifacts in the projected image. We add to the method a propagation of errors calculation for estimating uncertainties in the inverted solution. PMID:23902066
Basis set expansion for inverse problems in plasma diagnostic analysis
NASA Astrophysics Data System (ADS)
Jones, B.; Ruiz, C. L.
2013-07-01
A basis set expansion method [V. Dribinski, A. Ossadtchi, V. A. Mandelshtam, and H. Reisler, Rev. Sci. Instrum. 73, 2634 (2002)], 10.1063/1.1482156 is applied to recover physical information about plasma radiation sources from instrument data, which has been forward transformed due to the nature of the measurement technique. This method provides a general approach for inverse problems, and we discuss two specific examples relevant to diagnosing fast z pinches on the 20-25 MA Z machine [M. E. Savage, L. F. Bennett, D. E. Bliss, W. T. Clark, R. S. Coats, J. M. Elizondo, K. R. LeChien, H. C. Harjes, J. M. Lehr, J. E. Maenchen, D. H. McDaniel, M. F. Pasik, T. D. Pointon, A. C. Owen, D. B. Seidel, D. L. Smith, B. S. Stoltzfus, K. W. Struve, W. A. Stygar, L. K. Warne, J. R. Woodworth, C. W. Mendel, K. R. Prestwich, R. W. Shoup, D. L. Johnson, J. P. Corley, K. C. Hodge, T. C. Wagoner, and P. E. Wakeland, in Proceedings of the Pulsed Power Plasma Sciences Conference (IEEE, 2007), p. 979]. First, Abel inversion of time-gated, self-emission x-ray images from a wire array implosion is studied. Second, we present an approach for unfolding neutron time-of-flight measurements from a deuterium gas puff z pinch to recover information about emission time history and energy distribution. Through these examples, we discuss how noise in the measured data limits the practical resolution of the inversion, and how the method handles discontinuities in the source function and artifacts in the projected image. We add to the method a propagation of errors calculation for estimating uncertainties in the inverted solution.
Basis set expansion for inverse problems in plasma diagnostic analysis
Jones, B.; Ruiz, C. L.
2013-07-15
A basis set expansion method [V. Dribinski, A. Ossadtchi, V. A. Mandelshtam, and H. Reisler, Rev. Sci. Instrum. 73, 2634 (2002)] is applied to recover physical information about plasma radiation sources from instrument data, which has been forward transformed due to the nature of the measurement technique. This method provides a general approach for inverse problems, and we discuss two specific examples relevant to diagnosing fast z pinches on the 20–25 MA Z machine [M. E. Savage, L. F. Bennett, D. E. Bliss, W. T. Clark, R. S. Coats, J. M. Elizondo, K. R. LeChien, H. C. Harjes, J. M. Lehr, J. E. Maenchen, D. H. McDaniel, M. F. Pasik, T. D. Pointon, A. C. Owen, D. B. Seidel, D. L. Smith, B. S. Stoltzfus, K. W. Struve, W. A. Stygar, L. K. Warne, J. R. Woodworth, C. W. Mendel, K. R. Prestwich, R. W. Shoup, D. L. Johnson, J. P. Corley, K. C. Hodge, T. C. Wagoner, and P. E. Wakeland, in Proceedings of the Pulsed Power Plasma Sciences Conference (IEEE, 2007), p. 979]. First, Abel inversion of time-gated, self-emission x-ray images from a wire array implosion is studied. Second, we present an approach for unfolding neutron time-of-flight measurements from a deuterium gas puff z pinch to recover information about emission time history and energy distribution. Through these examples, we discuss how noise in the measured data limits the practical resolution of the inversion, and how the method handles discontinuities in the source function and artifacts in the projected image. We add to the method a propagation of errors calculation for estimating uncertainties in the inverted solution.
NASA Astrophysics Data System (ADS)
Julia, J.; Nyblade, A.; Pasyanos, M. E.; Matzel, E.; Rodgers, A.; Al-Amri, A. M.
2012-12-01
The Dead Sea Transform (DST) is a ~1000 km long fault system that separates the Arabian and African plates and links the active spreading center of the Red Sea with the continental collision zone in the Zagros mountains. Independent thermo-mechanical modeling had suggested that a mantle plume intruding from the south might have eroded the lithosphere East of the DST, but recent results from a number of temporary seismic deployments in the area have found little variation in lithospheric thickness to support it and proposed that such geodynamic processes might have operated on both sides of the DST. Those lithospheric thickness estimates have been obtained through the stack and migration of Sp conversions in S-receiver functions, which assumes a global background velocity model to calibrate the depth-scale that might not represent mantle structure under the DST accurately. In this study, we obtain lithospheric and sub-lithospheric S-velocity structure under several permanent broadband stations along the DST from the joint inversion of P- and S-wave receiver functions and tomographic surface-wave dispersion velocities. The joint inversion approach simultaneously models S-P times and Ps amplitudes in P-receiver functions, P-S times and Sp amplitudes in S-receiver functions, and fundamental-mode, Rayleigh-wave group velocities, providing local 1D models of S-velocity under individual recording stations. Our velocity models display interesting variations in crustal thickness along the DST, with values under 40 km in the southern portions and values well over 40 km more to the North, near Lebanon. The models also display S-velocity values in the lithospheric mantle that are generally slow, in the 4.3-4.4 km/s range, sometimes overlaying a relatively shallow asthenospheric low velocity channel, above 150 km depth.
X-Ray Imaging-Spectroscopy of Abell 1835
NASA Technical Reports Server (NTRS)
Peterson, J. R.; Paerels, F. B. S.; Kaastra, J. S.; Arnaud, M.; Reiprich T. H.; Fabian, A. C.; Mushotzky, R. F.; Jernigan, J. G.; Sakelliou, I.
2000-01-01
We present detailed spatially-resolved spectroscopy results of the observation of Abell 1835 using the European Photon Imaging Cameras (EPIC) and the Reflection Grating Spectrometers (RGS) on the XMM-Newton observatory. Abell 1835 is a luminous (10(exp 46)ergs/s), medium redshift (z = 0.2523), X-ray emitting cluster of galaxies. The observations support the interpretation that large amounts of cool gas are present in a multi-phase medium surrounded by a hot (kT(sub e) = 8.2 keV) outer envelope. We detect O VIII Ly(alpha) and two Fe XXIV complexes in the RGS spectrum. The emission measure of the cool gas below kT(sub e) = 2.7 keV is much lower than expected from standard cooling-flow models, suggesting either a more complicated cooling process than simple isobaric radiative cooling or differential cold absorption of the cooler gas.
The GenABEL Project for statistical genomics.
Karssen, Lennart C; van Duijn, Cornelia M; Aulchenko, Yurii S
2016-01-01
Development of free/libre open source software is usually done by a community of people with an interest in the tool. For scientific software, however, this is less often the case. Most scientific software is written by only a few authors, often a student working on a thesis. Once the paper describing the tool has been published, the tool is no longer developed further and is left to its own device. Here we describe the broad, multidisciplinary community we formed around a set of tools for statistical genomics. The GenABEL project for statistical omics actively promotes open interdisciplinary development of statistical methodology and its implementation in efficient and user-friendly software under an open source licence. The software tools developed withing the project collectively make up the GenABEL suite, which currently consists of eleven tools. The open framework of the project actively encourages involvement of the community in all stages, from formulation of methodological ideas to application of software to specific data sets. A web forum is used to channel user questions and discussions, further promoting the use of the GenABEL suite. Developer discussions take place on a dedicated mailing list, and development is further supported by robust development practices including use of public version control, code review and continuous integration. Use of this open science model attracts contributions from users and developers outside the "core team", facilitating agile statistical omics methodology development and fast dissemination. PMID:27347381
The GenABEL Project for statistical genomics
Karssen, Lennart C.; van Duijn, Cornelia M.; Aulchenko, Yurii S.
2016-01-01
Development of free/libre open source software is usually done by a community of people with an interest in the tool. For scientific software, however, this is less often the case. Most scientific software is written by only a few authors, often a student working on a thesis. Once the paper describing the tool has been published, the tool is no longer developed further and is left to its own device. Here we describe the broad, multidisciplinary community we formed around a set of tools for statistical genomics. The GenABEL project for statistical omics actively promotes open interdisciplinary development of statistical methodology and its implementation in efficient and user-friendly software under an open source licence. The software tools developed withing the project collectively make up the GenABEL suite, which currently consists of eleven tools. The open framework of the project actively encourages involvement of the community in all stages, from formulation of methodological ideas to application of software to specific data sets. A web forum is used to channel user questions and discussions, further promoting the use of the GenABEL suite. Developer discussions take place on a dedicated mailing list, and development is further supported by robust development practices including use of public version control, code review and continuous integration. Use of this open science model attracts contributions from users and developers outside the “core team”, facilitating agile statistical omics methodology development and fast dissemination. PMID:27347381
Ganguly, A. E-mail: aganguly@maths.iitkgp.ernet.in; Das, A.
2014-11-15
We consider one-dimensional stationary position-dependent effective mass quantum model and derive a generalized Korteweg-de Vries (KdV) equation in (1+1) dimension through Lax pair formulation, one being the effective mass Schrödinger operator and the other being the time-evolution of wave functions. We obtain an infinite number of conserved quantities for the generated nonlinear equation and explicitly show that the new generalized KdV equation is an integrable system. Inverse scattering transform method is applied to obtain general solution of the nonlinear equation, and then N-soliton solution is derived for reflectionless potentials. Finally, a special choice has been made for the variable mass function to get mass-deformed soliton solution. The influence of position and time-dependence of mass and also of the different representations of kinetic energy operator on the nature of such solitons is investigated in detail. The remarkable features of such solitons are demonstrated in several interesting figures and are contrasted with the conventional KdV-soliton associated with constant-mass quantum model.
Soni, M.H.; Cooks, R.G. )
1994-08-01
Broad-band excitation of ions is accomplished in the quadrupole ion trap mass spectrometer using notched waveforms created by the SWIFT (stored waveform inverse Fourier transform) technique. A series of notched SWIFT pulses are applied during the period of ion injection from an external Cs[sup +] source to resonantly eject all ions whose resonance frequencies fall within the frequency range of the pulse while injecting only those analyte ions whose resonance frequencies fall within the limits of the notch. This allows selective injection and accumulation of the ions of interest and continuous ejection of the unwanted ions. This is shown to result in significant improvement in S/N ratio, resolution, and sensitivity for the analyte ions of interest. Selective ion injection is demonstrated by injecting the protonated molecules of peptides VSV and gramicidin S and the intact cation of l-carnitine hydrochloride, using singly notched SWIFT pulses. Multiply notched SWIFT pulses are used to simultaneously inject ions of different m/z values of l-carnitine hydrochloride into the ion trap. A new coarse/fine ion isolation procedure, which employs a doubly notched SWIFT pulse, is demonstrated for isolating ions of a single m/z value of 4-bromobiphenyl from a population of trapped ions. 36 refs., 10 figs., 2 tabs.
RADIO AND DEEP CHANDRA OBSERVATIONS OF THE DISTURBED COOL CORE CLUSTER ABELL 133
Randall, S. W.; Nulsen, P. E. J.; Forman, W. R.; Murray, S. S.; Clarke, T. E.; Owers, M. S.; Sarazin, C. L.
2010-10-10
We present results based on new Chandra and multi-frequency radio observations of the disturbed cool core cluster Abell 133. The diffuse gas has a complex bird-like morphology, with a plume of emission extending from two symmetric wing-like features. The plume is capped with a filamentary radio structure that has been previously classified as a radio relic. X-ray spectral fits in the region of the relic indicate the presence of either high-temperature gas or non-thermal emission, although the measured photon index is flatter than would be expected if the non-thermal emission is from inverse Compton scattering of the cosmic microwave background by the radio-emitting particles. We find evidence for a weak elliptical X-ray surface brightness edge surrounding the core, which we show is consistent with a sloshing cold front. The plume is consistent with having formed due to uplift by a buoyantly rising radio bubble, now seen as the radio relic, and has properties consistent with buoyantly lifted plumes seen in other systems (e.g., M87). Alternatively, the plume may be a gas sloshing spiral viewed edge-on. Results from spectral analysis of the wing-like features are inconsistent with the previous suggestion that the wings formed due to the passage of a weak shock through the cool core. We instead conclude that the wings are due to X-ray cavities formed by displacement of X-ray gas by the radio relic. The central cD galaxy contains two small-scale cold gas clumps that are slightly offset from their optical and UV counterparts, suggestive of a galaxy-galaxy merger event. On larger scales, there is evidence for cluster substructure in both optical observations and the X-ray temperature map. We suggest that the Abell 133 cluster has recently undergone a merger event with an interloping subgroup, initialing gas sloshing in the core. The torus of sloshed gas is seen close to edge-on, leading to the somewhat ragged appearance of the elliptical surface brightness edge. We show
NASA Astrophysics Data System (ADS)
Edwards, L. O. V.; Alpert, H. S.; Trierweiler, I. L.; Abraham, T.; Beizer, V. G.
2016-09-01
We present the first results from an integral field unit (IFU) spectroscopic survey of a ˜75 kpc region around three brightest cluster galaxies (BCGs), combining over 100 IFU fibres to study the intracluster light (ICL). We fit population synthesis models to estimate age and metallicity. For Abell 85 and Abell 2457, the ICL is best-fit with a fraction of old, metal-rich stars like in the BCG, but requires 30-50 per cent young and metal-poor stars, a component not found in the BCGs. This is consistent with the ICL having been formed by a combination of interactions with less massive, younger, more metal-poor cluster members in addition to stars that form the BCG. We find that the three galaxies are in different stages of evolution and may be the result of different formation mechanisms. The BCG in Abell 85 is near a relatively young, metal-poor galaxy, but the dynamical friction time-scale is long and the two are unlikely to be undergoing a merger. The outer regions of Abell 2457 show a higher relative fraction of metal-poor stars, and we find one companion, with a higher fraction of young, metal-poor stars than the BCG, which is likely to merge within a gigayear. Several luminous red galaxies are found at the centre of the cluster IIZw108, with short merger time-scales, suggesting that the system is about to embark on a series of major mergers to build up a dominant BCG. The young, metal-poor component found in the ICL is not found in the merging galaxies.
NASA Astrophysics Data System (ADS)
Edwards, L. O. V.; Alpert, H. S.; Trierweiler, I. L.; Abraham, T.; Beizer, V. G.
2016-06-01
We present the first results from an integral field (IFU) spectroscopic survey of a ˜75 kpc region around three Brightest Cluster Galaxies (BCGs), combining over 100 IFU fibres to study the intracluster light (ICL). We fit population synthesis models to estimate age and metallicity. For Abell 85 and Abell 2457, the ICL is best-fit with a fraction of old, metal-rich stars like in the BCG, but requires 30-50% young and metal-poor stars, a component not found in the BCGs. This is consistent with the ICL having been formed by a combination of interactions with less massive, younger, more metal-poor cluster members in addition to stars that form the BCG. We find that the three galaxies are in different stages of evolution and may be the result of different formation mechanisms. The BCG in Abell 85 is near a relatively young, metal-poor galaxy, but the dynamical friction timescale is long and the two are unlikely to be undergoing a merger. The outer regions of Abell 2457 show a higher relative fraction of metal-poor stars, and we find one companion, with a higher fraction of young, metal-poor stars than the BCG, which is likely to merge within a gigayear. Several luminous red galaxies are found at the centre of the cluster IIZw108, with short merger timescales, suggesting the system is about to embark on a series of major mergers to build up a dominant BCG. The young, metal-poor component found in the ICL is not found in the merging galaxies.
NASA Astrophysics Data System (ADS)
Azuma, Hiroo
In this paper, we give an analytical treatment to study the behavior of the collapse and the revival of the Rabi oscillations in the Jaynes-Cummings model (JCM). The JCM is an exactly soluble quantum mechanical model, which describes the interaction between a two-level atom and a single cavity mode of the electromagnetic field. If we prepare the atom in the ground state and the cavity mode in a coherent state initially, the JCM causes the collapse and the revival of the Rabi oscillations many times in a complicated pattern in its time-evolution. In this phenomenon, the atomic population inversion is described with an intractable infinite series. (When the electromagnetic field is resonant with the atom, the nth term of this infinite series is given by a trigonometric function for √ {n} t, where t is a variable of the time.) According to Klimov and Chumakov's method, using the Abel-Plana formula, we rewrite this infinite series as a sum of two integrals. We examine the physical meanings of these two integrals and find that the first one represents the initial collapse (the semi-classical limit) and the second one represents the revival (the quantum correction) in the JCM. Furthermore, we evaluate the first- and second-order perturbations for the time-evolution of the JCM with an initial thermal coherent state for the cavity mode at low temperature, and write down their correction terms as sums of integrals by making use of the Abel-Plana formula.
Disentangling Structures in the Cluster of Galaxies Abell 133
NASA Technical Reports Server (NTRS)
Way, Michael J.; DeVincenzi, Donald (Technical Monitor)
2002-01-01
A dynamical analysis of the structure of the cluster of galaxies Abell 133 will be presented using multi-wavelength data combined from multiple space and earth based observations. New and familiar statistical clustering techniques are used in combination in an attempt to gain a fully consistent picture of this interesting nearby cluster of galaxies. The type of analysis presented should be typical of cluster studies in the future, especially those to come from the surveys like the Sloan Digital Sky Survey and the 2DF.
Buoyant Bubbles and the Disturbed Cool Core of Abell 133
NASA Astrophysics Data System (ADS)
Randall, Scott W.; Clarke, T.; Nulsen, P.; Owers, M.; Sarazin, C.; Forman, W.; Jones, C.; Murray, S.
2010-03-01
X-ray cavities, often filled with radio-emitting plasma, are routinely observed in the intracluster medium of clusters of galaxies. These cavities, or "bubbles", are evacuated by jets from central AGN and subsequently rise buoyantly, playing a vital role in the "AGN feedback" model now commonly evoked to explain the balance between heating and radiative cooling in cluster cores. As the bubbles rise, they can displace cool central gas, promoting mixing and the redistribution of metals. I will show a few examples of buoyant bubbles, then argue that the peculiar morphology of the Abell 133 is due to buoyant lifting of cool central gas by a radio-filled bubble.
The discovery of diffuse steep spectrum sources in Abell 2256
NASA Astrophysics Data System (ADS)
van Weeren, R. J.; Intema, H. T.; Oonk, J. B. R.; Röttgering, H. J. A.; Clarke, T. E.
2009-12-01
Context: Hierarchical galaxy formation models indicate that during their lifetime galaxy clusters undergo several mergers. An example of such a merging cluster is Abell 2256. Here we report on the discovery of three diffuse radio sources in the periphery of Abell 2256, using the Giant Metrewave Radio Telescope (GMRT). Aims: The aim of the observations was to search for diffuse ultra-steep spectrum radio sources within the galaxy cluster Abell 2256. Methods: We have carried out GMRT 325 MHz radio continuum observations of Abell 2256. V, R and I band images of the cluster were taken with the 4.2 m William Herschel Telescope (WHT). Results: We have discovered three diffuse elongated radio sources located about 1 Mpc from the cluster center. Two are located to the west of the cluster center, and one to the southeast. The sources have a measured physical extent of 170, 140 and 240 kpc, respectively. The two western sources are also visible in deep low-resolution 115-165 MHz Westerbork Synthesis Radio Telescope (WSRT) images, although they are blended into a single source. For the combined emission of the blended source we find an extreme spectral index (α) of -2.05 ± 0.14 between 140 and 351 MHz. The extremely steep spectral index suggests these two sources are most likely the result of adiabatic compression of fossil radio plasma due to merger shocks. For the source to the southeast, we find that {α < -1.45} between 1369 and 325 MHz. We did not find any clear optical counterparts to the radio sources in the WHT images. Conclusions: The discovery of the steep spectrum sources implies the existence of a population of faint diffuse radio sources in (merging) clusters with such steep spectra that they have gone unnoticed in higher frequency (⪆1 GHz) observations. Simply considering the timescales related to the AGN activity, synchrotron losses, and the presence of shocks, we find that most massive clusters should possess similar sources. An exciting possibility
ERIC Educational Resources Information Center
Grimm, C. A.
This document contains two units that examine integral transforms and series expansions. In the first module, the user is expected to learn how to use the unified method presented to obtain Laplace transforms, Fourier transforms, complex Fourier series, real Fourier series, and half-range sine series for given piecewise continuous functions. In…
NASA Astrophysics Data System (ADS)
Lin, Jian; Wu, Yun; Qiao, Xuejun; Zhou, Yiyan
2012-01-01
Multi-channel Global Positioning System (GPS) carrier phase signals, received by the six low Earth orbiting (LEO) satellites from the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) program, were used to undertake active limb sounding of the Earth's atmosphere and ionosphere via radio occultation. In the ionospheric radio occultation (IRO) data processing, the standard Shell inversion technique (SIT), transformed from the traditional Abel inversion technique (AIT), is widely used, and can retrieve good electron density profiles. In this paper, an alternative SIT method is proposed. The comparison between different inversion techniques will be discussed, taking advantage of the availability of COSMIC datasets. Moreover, the occultation results obtained from the SIT and alternative SIT at 500 km and 800 km, are compared with ionosonde measurements. The electron densities from the alternative SIT show excellent consistency to those from the SIT, with strong correlations over 0.996 and 0.999 at altitudes of 500 km and 800 km, respectively, and the peak electron densities (NmF2) from the alternative SIT are equivalent to the SIT, with 0.839 vs. 0.844, and 0.907 vs. 0.909 correlation coefficients when comparing to those by the ionosondes. These results show that: (1) the NmF2 and hmF2 retrieved from the SIT and alternative SIT are highly consistent, and in a good agreement with those measured by ionosondes, (2) no matter which inversion technique is used, the occultation results at the higher orbits (˜800 km) are better than those at the lower orbits (˜500 km).
NASA Astrophysics Data System (ADS)
Harko, T.; Mak, M. K.
2015-11-01
We consider quasi-stationary (travelling wave type) solutions to a general nonlinear reaction-convection-diffusion equation with arbitrary, autonomous coefficients. The second order nonlinear equation describing one dimensional travelling waves can be reduced to a first kind first order Abel equation. By using two integrability conditions for the Abel equation (the Chiellini lemma and the Lemke transformation), several classes of exact travelling wave solutions of the general reaction-convection-diffusion equation are obtained, corresponding to different functional relations imposed between the diffusion, convection and reaction functions. In particular, we obtain travelling wave solutions for two non-linear second order partial differential equations, representing generalizations of the standard diffusion equation and of the classical Fisher-Kolmogorov equation, to which they reduce for some limiting values of the model parameters. The models correspond to some specific, power law type choices of the reaction and convection functions, respectively. The travelling wave solutions of these two classes of differential equation are investigated in detail by using both numerical and semi-analytical methods.
The Noble-Abel Stiffened-Gas equation of state
NASA Astrophysics Data System (ADS)
Le Métayer, Olivier; Saurel, Richard
2016-04-01
Hyperbolic two-phase flow models have shown excellent ability for the resolution of a wide range of applications ranging from interfacial flows to fluid mixtures with several velocities. These models account for waves propagation (acoustic and convective) and consist in hyperbolic systems of partial differential equations. In this context, each phase is compressible and needs an appropriate convex equation of state (EOS). The EOS must be simple enough for intensive computations as well as boundary conditions treatment. It must also be accurate, this being challenging with respect to simplicity. In the present approach, each fluid is governed by a novel EOS named "Noble Abel stiffened gas," this formulation being a significant improvement of the popular "Stiffened Gas (SG)" EOS. It is a combination of the so-called "Noble-Abel" and "stiffened gas" equations of state that adds repulsive effects to the SG formulation. The determination of the various thermodynamic functions and associated coefficients is the aim of this article. We first use thermodynamic considerations to determine the different state functions such as the specific internal energy, enthalpy, and entropy. Then we propose to determine the associated coefficients for a liquid in the presence of its vapor. The EOS parameters are determined from experimental saturation curves. Some examples of liquid-vapor fluids are examined and associated parameters are computed with the help of the present method. Comparisons between analytical and experimental saturation curves show very good agreement for wide ranges of temperature for both liquid and vapor.
Hierarchical Velocity Structure in the Core of Abell 2597
NASA Technical Reports Server (NTRS)
Still, Martin; Mushotzky, Richard
2004-01-01
We present XMM-Newton RGS and EPIC data of the putative cooling flow cluster Abell 2597. Velocities of the low-ionization emission lines in the spectrum are blue shifted with respect to the high-ionization lines by 1320 (sup +660) (sub -210) kilometers per second, which is consistent with the difference in the two peaks of the galaxy velocity distribution and may be the signature of bulk turbulence, infall, rotation or damped oscillation in the cluster. A hierarchical velocity structure such as this could be the direct result of galaxy mergers in the cluster core, or the injection of power into the cluster gas from a central engine. The uniform X-ray morphology of the cluster, the absence of fine scale temperature structure and the random distribution of the the galaxy positions, independent of velocity, suggests that our line of sight is close to the direction of motion. These results have strong implications for cooling flow models of the cluster Abell 2597. They give impetus to those models which account for the observed temperature structure of some clusters using mergers instead of cooling flows.
NASA Astrophysics Data System (ADS)
Auer, L.; Greenhalgh, S. A.; Maurer, H. R.; Marelli, S.; Nuber, A.
2012-04-01
Seismic full waveform inversion is often based on forward modeling in the computationally attractive 2-D domain. Any solution of the 2-D cartesian wave equation inherently carries the implicit assumption of a line source extended in the out-of-plane medium invariant direction. This implies that the source energy in homogeneous media spreads over the surface of an approximately expanding cylinder, such that the wavefield amplitudes (at least in the far field) scale inversely with the square-root of distance. However, realistic point sources like explosives or airguns, fired in a 3-D medium, generate amplitudes that decay inversely with the first power of distance, since the wavefield expands quasi-spherically in all three dimensions. Usually, practitioners correct for this amplitude difference and the associated phase shift of π/4 by transforming the recorded 3-D field data to the approximate 2-D situation by using simplistic, asymptotic filter algorithms. Such filters operate on a square root of time-sample convolutional basis and implicitly assume straight ray paths and a constant velocity medium. The unsubstantiated usage of these asymptotic filters is in contradiction to their well known limitations. In this study, we present an extensive quantitative appraisal of 3D-to-2D data transformation procedures. Our analysis relies on a simple numerical modeling study, based on propagating 3-D and 2-D wavefields through 2-D media and comparing the true 2-D and the filtered 3-D synthetic data. It is shown that the filtering errors are moderate in purely acoustic situations but become substantial in complex media when arrivals overlap each other or ray paths deviate strongly from straight lines. Normalized root-mean-square deviations up to 5% and maximum relative time domain errors of up to 40% were found in high contrast media, when full elastic treatment was considered. In order to examine if this error translates into a deficient model reconstruction in full waveform
Brig. Gen. Richard F. Abel and Col. Natan J. Lindsay answering questions
NASA Technical Reports Server (NTRS)
1982-01-01
Brigadier General Richard F. Abel, right, director of public affairs for the Air Force, and Colonel Nathan J. Lindsay of the USAF's space division, answer questions concerning STS-4 during a press conference at JSC on May 20, 1982.
Large Scale Diffuse X-ray Emission from Abell 3571
NASA Technical Reports Server (NTRS)
Molnar, Sandor M.; White, Nicholas E. (Technical Monitor)
2001-01-01
Observations of the Luman alpha forest suggest that there are many more baryons at high redshift than we can find in the Universe nearby. The largest known concentration of baryons in the nearby Universe is the Shapley supercluster. We scanned the Shapley supercluster to search for large scale diffuse emission with the Rossi X-ray Timing Explorer (RXTE), and found some evidence for such emission. Large scale diffuse emission may be associated to the supercluster, or the clusters of galaxies within the supercluster. In this paper we present results of scans near Abell 3571. We found that the sum of a cooling flow and an isothermal beta model adequately describes the X-ray emission from the cluster. Our results suggest that diffuse emission from A3571 extends out to about two virial radii. We briefly discuss the importance of the determination of the cut off radius of the beta model.
The cD galaxy in Abell cluster 1775
NASA Technical Reports Server (NTRS)
Hayes, J. J. E.; Bhattacharya, B.
1990-01-01
Over the last 20 years, a number of workers have studied the multiple nuclei cD galaxy in the rich Abell cluster 1775, trying to discover its nature. In all the cases though, very little has been published concerning its morphology. The majority of arguments about the nature of this object have been based on the relative radial velocities of the 2 components with each other and with the other galaxies in the cluster, or its radio morphology. Very little work has been done on the optical morphology. To rectify that lack of data, the authors have obtained charge coupled device (CCD) images of the cD. The authors find from the CCD data that the cD is unlikely to be a bound object and that there is strong evidence for a collision.
Comparison of four stable numerical methods for Abel's integral equation
NASA Technical Reports Server (NTRS)
Murio, Diego A.; Mejia, Carlos E.
1991-01-01
The 3-D image reconstruction from cone-beam projections in computerized tomography leads naturally, in the case of radial symmetry, to the study of Abel-type integral equations. If the experimental information is obtained from measured data, on a discrete set of points, special methods are needed in order to restore continuity with respect to the data. A new combined Regularized-Adjoint-Conjugate Gradient algorithm, together with two different implementations of the Mollification Method (one based on a data filtering technique and the other on the mollification of the kernal function) and a regularization by truncation method (initially proposed for 2-D ray sample schemes and more recently extended to 3-D cone-beam image reconstruction) are extensively tested and compared for accuracy and numerical stability as functions of the level of noise in the data.
Diffuse Radio Emission in the Galaxy Cluster Abell 754
NASA Astrophysics Data System (ADS)
Kale, R.; Dwarakanath, K. S.
2009-09-01
We present a low frequency (<1.4GHz) study of the diffuse radio halo and relic emission in the galaxy cluster Abell 0754. Images at 150 MHz made using the Giant Metrewave Radio Telescope (GMRT) revealed 4 diffuse features; 3 of which are new. Images at 330 and 1363 MHz were created using archival data from the GMRT and the VLA respectively. These yield synchrotron spectral indices, α (S ∝ν-α), steeper than 2 for the new features. Adiabatic compression of fossil radio galaxy cocoon by shocks can lead to the formation of radio relics (Ensslin & Gopal-Krishna, 2001). In the framework of this model we find that the relic in A754 can be explained as a lurking cocoon of a radio galaxy; no shock compression is required to produce this emission. The implications of this result to the merger scenario in A754 are discussed.
A shock front at the radio relic of Abell 2744
NASA Astrophysics Data System (ADS)
Eckert, D.; Jauzac, M.; Vazza, F.; Owers, M. S.; Kneib, J.-P.; Tchernin, C.; Intema, H.; Knowles, K.
2016-09-01
Radio relics are Mpc-scale diffuse radio sources at the peripheries of galaxy clusters which are thought to trace outgoing merger shocks. We present XMM-Newton and Suzaku observations of the galaxy cluster Abell 2744 (z = 0.306), which reveal the presence of a shock front 1.5 Mpc east of the cluster core. The surface-brightness jump coincides with the position of a known radio relic. Although the surface-brightness jump indicates a weak shock with a Mach number M=1.7_{-0.3}^{+0.5}, the plasma in the post-shock region has been heated to a very high temperature (˜13 keV) by the passage of the shock wave. The low-acceleration efficiency expected from such a weak shock suggests that mildly relativistic electrons have been re-accelerated by the passage of the shock front.
Giant ringlike radio structures around galaxy cluster Abell 3376.
Bagchi, Joydeep; Durret, Florence; Neto, Gastão B Lima; Paul, Surajit
2006-11-01
In the current paradigm of cold dark matter cosmology, large-scale structures are assembling through hierarchical clustering of matter. In this process, an important role is played by megaparsec (Mpc)-scale cosmic shock waves, arising in gravity-driven supersonic flows of intergalactic matter onto dark matter-dominated collapsing structures such as pancakes, filaments, and clusters of galaxies. Here, we report Very Large Array telescope observations of giant ( approximately 2 Mpc by 1.6 Mpc), ring-shaped nonthermal radio-emitting structures, found at the outskirts of the rich cluster of galaxies Abell 3376. These structures may trace the elusive shock waves of cosmological large-scale matter flows, which are energetic enough to power them. These radio sources may also be the acceleration sites where magnetic shocks are possibly boosting cosmic-ray particles with energies of up to 10(18) to 10(19) electron volts. PMID:17082451
Single florescent nanodiamond in a three dimensional ABEL trap
Kayci, Metin; Radenovic, Aleksandra
2015-01-01
Three dimensional single particle trapping and manipulation is an outstanding challenge in various fields ranging from basic physics to life sciences. By monitoring the response of a trapped particle to a designed environment one can extract its characteristics. In addition, quantum dynamics of a spatially scanned well-known particle can provide environmental information. Precise tracking and positioning of such a particle in aqueous environment is crucial task for achieving nano-scale resolution. Here we experimentally demonstrate three dimensional ABEL trap operating at high frequency by employing a hybrid approach in particle tracking. The particle location in the transverse plane is detected via a scanning laser beam while the axial position is determined by defocused imaging. The scanning of the trapped particle is accomplished through a nano positioning stage integrated to the trap platform. PMID:26559890
The central star of the planetary nebula Abell 78
NASA Technical Reports Server (NTRS)
Kaler, J. B.; Feibelman, W. A.
1984-01-01
The ultraviolet spectrum of the nucleus of Abell 78, one of the two planetaries known to contain zones of nearly pure helium, is studied. The line spectrum and wind velocities are examined, the determination of interstellar extinction for assessing circumstellar dust is improved, and the temperature, luminosity, and core mass are derived. The results for A78 are compared with results for A30, and it is concluded that the dust distributions around the two central stars are quite different. The temperature of the A78 core is not as high as previously believed, and almost certainly lies between 67,000 K and 130,000 K. The most likely temperature range is 77,000-84,000 K. The core mass lies between 0.56 and 0.70 solar mass, with the most likely values between 0.56 and 0.58 solar mass.
Properties of the Blue Galaxy Population in Abell 754
NASA Astrophysics Data System (ADS)
McIntosh, D. H.; Rix, H.-W.; Caldwell, N.
2000-12-01
Do star-forming spirals accreted recently by massive clusters evolve in a few Gyrs. into smooth disk galaxies with little or no current star formation? Hierarchical models of large-scale structure and the observed effect of the cluster environment on galaxy morphologies and star formation rates have given rise to many theories predicting such cluster galaxy evolution. Depending on the star formation truncation mechanism timescale, the more recent cluster arrivals should still have relatively young stellar populations and thus bluer colors (esp. in U-V) than the older, red early-types (E/S0) that define the cluster color-magnitude relation. Yet to date no significant population of bluer S0's has been found in local clusters, though we note previous studies have concentrated on the inner regions (R<0.5Mpc) of nearby clusters, which are expected to be dominated by older members. Therefore, we have obtained wide-field (R>0.6/h Mpc) UVI imaging for 10 local (z<0.06) Abell clusters, with 100's of spectroscopically confirmed members, to search the cluster outskirts for bluer S0's which may be recently accreted spirals. From our detailed photometry, we have measured structural parameters for a sample of over 300 U-band selected, spectroscopically confirmed members, by fitting each galaxy surface brightness profile with a PSF-convolved, de Vaucouleur's bulge plus exponential disk model. We have found a population of blue, disk-dominated galaxies, that are predominately in the outskirts (>0.75/h Mpc projected radius) of our first analyzed cluster, Abell 754 at z=0.053. We present the photometric and structural properties of this blue population.
The distribution of dark and luminous matter in the unique galaxy cluster merger Abell 2146
NASA Astrophysics Data System (ADS)
King, Lindsay J.; Clowe, Douglas I.; Coleman, Joseph E.; Russell, Helen R.; Santana, Rebecca; White, Jacob A.; Canning, Rebecca E. A.; Deering, Nicole J.; Fabian, Andrew C.; Lee, Brandyn E.; Li, Baojiu; McNamara, Brian R.
2016-06-01
Abell 2146 (z = 0.232) consists of two galaxy clusters undergoing a major merger. The system was discovered in previous work, where two large shock fronts were detected using the Chandra X-ray Observatory, consistent with a merger close to the plane of the sky, caught soon after first core passage. A weak gravitational lensing analysis of the total gravitating mass in the system, using the distorted shapes of distant galaxies seen with Advanced Camera for Surveys - Wide Field Channel on Hubble Space Telescope, is presented. The highest peak in the reconstruction of the projected mass is centred on the brightest cluster galaxy (BCG) in Abell 2146-A. The mass associated with Abell 2146-B is more extended. Bootstrapped noise mass reconstructions show the mass peak in Abell 2146-A to be consistently centred on the BCG. Previous work showed that BCG-A appears to lag behind an X-ray cool core; although the peak of the mass reconstruction is centred on the BCG, it is also consistent with the X-ray peak given the resolution of the weak lensing mass map. The best-fitting mass model with two components centred on the BCGs yields M200 = 1.1^{+0.3}_{-0.4} × 1015 and 3^{+1}_{-2} × 1014 M⊙ for Abell 2146-A and Abell 2146-B, respectively, assuming a mass concentration parameter of c = 3.5 for each cluster. From the weak lensing analysis, Abell 2146-A is the primary halo component, and the origin of the apparent discrepancy with the X-ray analysis where Abell 2146-B is the primary halo is being assessed using simulations of the merger.
Radon transforms and Gegenbauer-Chebyshev integrals, I
NASA Astrophysics Data System (ADS)
Rubin, Boris
2016-04-01
We suggest new modifications of the Helgason's support theorem and description of the kernel for the hyperplane Radon transform and its dual. The assumptions for functions are formulated in integral terms and close to minimal. The proofs rely on the properties of the Gegenbauer-Chebyshev integrals which generalize Abel type fractional integrals on the positive half-line.
The merging cluster Abell 1758: an optical and dynamical view
NASA Astrophysics Data System (ADS)
Monteiro-Oliveira, Rogerio; Serra Cypriano, Eduardo; Machado, Rubens; Lima Neto, Gastao B.
2015-08-01
The galaxy cluster Abell 1758-North (z=0.28) is a binary system composed by the sub-structures NW and NE. This is supposed to be a post-merging cluster due to observed detachment between the NE BCG and the respective X-ray emitting hot gas clump in a scenario very close to the famous Bullet Cluster. On the other hand, the projected position of the NW BCG coincides with the local hot gas peak. This system was been targeted previously by several studies, using multiple wavelengths and techniques, but there is still no clear picture of the scenario that could have caused this unusual configuration. To help solving this complex puzzle we added some pieces: firstly, we have used deep B, RC and z' Subaru images to perform both weak lensing shear and magnification analysis of A1758 (including here the South component that is not in interaction with A1758-North) modeling each sub-clump as an NFW profile in order to constrain masses and its center positions through MCMC methods; the second piece is the dynamical analysis using radial velocities available in the literature (143) plus new Gemini-GMOS/N measurements (68 new redshifts).From weak lensing we found that independent shear and magnification mass determinations are in excellent agreement between them and combining both we could reduce mass error bar by ~30% compared to shear alone. By combining this two weak-lensing probes we found that the position of both Northern BCGs are consistent with the masses centers within 2σ and and the NE hot gas peak to be offseted of the respective mass peak (M200=5.5 X 1014 M⊙) with very high significance. The most massive structure is NW (M200=7.95 X 1014 M⊙ ) where we observed no detachment between gas, DM and BCG.We have calculated a low line-of-sight velocity difference (<300 km/s) between A1758 NW and NE. We have combined it with the projected velocity of 1600 km/s which was estimated by previous X-ray analysis (David & Kempner 2004) and we have obtained a small angle between
Searching for Young S0 Galaxies in Abell 2052
NASA Astrophysics Data System (ADS)
McIntosh, D. H.; Rix, H.-W.; Caldwell, N.
1999-12-01
Numerous studies have established strong observational evidence for evolution in cluster member color and morphology. Such evolution is predicted by hierarchical structure formation scenarios where galaxy clusters evolve via accretion of mass from the field. It has been hypothesized that recently accreted large surface brightness spirals will rapidly evolve via some star formation (SF) truncation mechanism into smooth disk galaxies with little or no current SF, but relatively young stellar populations. These younger S0's (hereafter bluer S0's = BS0's) would have bluer colors than the older early-types (E/S0) that define the mean cluster color-magnitude relation (CMR). The existence of such galaxies provides explanations for the disappearance of the blue, star-forming disk galaxies that were common in clusters at z 0.5 (the Butcher-Oemler effect), and the increased fraction of S0's in present-day clusters. To date a significant population of BS0's in nearby clusters has not been found. Therefore, we have obtained wide field (R > 0.6 Mpc), high precision UVI photometry for a sample of 14 local (z < 0.06) Abell clusters, most with over <100 spectroscopically confirmed members. We present photometric results for our first completely reduced cluster, Abell 2052. We have selected candidate BS0's as those early-type members that deviate blueward from the CMR by more than the intrinsic CMR scatter. We used 2-D bulge/disk (B/D) decomposition as an indicator of morphology to refine our sample. This spring, we will obtain spectroscopy of this sample to confirm the relative youth of the stellar populations. In addition, we will use the B/D decompositions of these candidate BS0's to address the following questions: (1) do BS0's make up a significant fraction of the early-type members that deviated from the cluster mean CMR; (2) do BS0's avoid the inner cluster; (3) are BS0's bluer in their disks or bulges; (4) do BS0's exhibit a range of B/D ratios similar to that found in
NASA Astrophysics Data System (ADS)
Ammari, Amara; Karoui, Abderrazek
2012-05-01
In this paper, we build a stable scheme for the solution of a deconvolution problem of the Abel integral equation type. This scheme is obtained by further developing the orthogonal polynomial-based techniques for solving the Abel integral equation of Ammari and Karoui (2010 Inverse Problems 26 105005). More precisely, this method is based on the simultaneous use of the two families of orthogonal polynomials of the Legendre and Jacobi types. In particular, we provide an explicit formula for the computation of the Legendre expansion coefficients of the solution. This explicit formula is based on some known formulae for the exact computation of the integrals of the product of some Jacobi polynomials with the derivatives of the Legendre polynomials. Besides the explicit and the exact computation of the expansion coefficients of the solution, our proposed method has the advantage of ensuring the stability of the solution under a fairly weak condition on the functional space to which the data function belongs. Finally, we provide the reader with some numerical examples that illustrate the results of this work.
Strzemiecka, B; Voelkel, A; Zięba-Palus, J; Lachowicz, T
2014-09-12
The chemical changes occurring in the phenol-formaldehyde resins (resol and novolac type) during their storage were investigated. In this paper the FT-IR, py-GCMS and inverse gas chromatography methods were applied for assessment of the changes occurring during storage of the phenolic resins. We have found that during storage some examined resins occurred partial curing. The results from all techniques applied are consistent. Py-GCMS is useful technique for screening the storage processes but IGC seems to be most sensitive one. PMID:25092596
An ionospheric occultation inversion technique based on epoch difference
NASA Astrophysics Data System (ADS)
Lin, Jian; Xiong, Jing; Zhu, Fuying; Yang, Jian; Qiao, Xuejun
2013-09-01
Of the ionospheric radio occultation (IRO) electron density profile (EDP) retrievals, the Abel based calibrated TEC inversion (CTI) is the most widely used technique. In order to eliminate the contribution from the altitude above the RO satellite, it is necessary to utilize the calibrated TEC to retrieve the EDP, which introduces the error due to the coplanar assumption. In this paper, a new technique based on the epoch difference inversion (EDI) is firstly proposed to eliminate this error. The comparisons between CTI and EDI have been done, taking advantage of the simulated and real COSMIC data. The following conclusions can be drawn: the EDI technique can successfully retrieve the EDPs without non-occultation side measurements and shows better performance than the CTI method, especially for lower orbit mission; no matter which technique is used, the inversion results at the higher altitudes are better than those at the lower altitudes, which could be explained theoretically.
The Sunyaev-Zeldovich Effect in Abell 370
NASA Technical Reports Server (NTRS)
Grego, Laura; Carlstrom, John E.; Joy, Marshall K.; Reese, Erik D.; Holder, Gilbert P.; Patel, Sandeep; Cooray, Asantha R.; Holzappel, William L.
2000-01-01
We present interferometric measurements of the Sunyaev-Zeldovich (SZ) effect toward the galaxy cluster Abell 370. These measurements, which directly probe the pressure of the cluster's gas, show the gas distribution to be strongly aspherical, as do the X-ray and gravitational lensing observations. We calculate the cluster's gas mass fraction in two ways. We first compare the gas mass derived from the SZ measurements to the lensing-derived gravitational mass near the critical lensing radius. We also calculate the gas mass fraction from the SZ data by deprojecting the three-dimensional gas density distribution and deriving the total mass under the assumption that the gas is in hydrostatic equilibrium (HSE). We test the assumptions in the HSE method by comparing the total cluster mass implied by the two methods and find that they agree within the errors of the measurement. We discuss the possible system- atic errors in the gas mass fraction measurement and the constraints it places on the matter density parameter, Omega(sub M).
A shock at the radio relic position in Abell 115
NASA Astrophysics Data System (ADS)
Botteon, A.; Gastaldello, F.; Brunetti, G.; Dallacasa, D.
2016-07-01
We analysed a deep Chandra observation (334 ks) of the galaxy cluster Abell 115 and detected a shock cospatial with the radio relic. The X-ray surface brightness profile across the shock region presents a discontinuity, corresponding to a density compression factor {C}=2.0± 0.1, leading to a Mach number {M}=1.7± 0.1 ({M}=1.4-2 including systematics). Temperatures measured in the upstream and downstream regions are consistent with what expected for such a shock: T_u=4.3^{+1.0}_{-0.6}{keV} and T_d=7.9^{+1.4}_{-1.1}{keV}, respectively, implying a Mach number {M}=1.8^{+0.5}_{-0.4}. So far, only few other shocks discovered in galaxy clusters are consistently detected from both density and temperature jumps. The spatial coincidence between this discontinuity and the radio relic edge strongly supports the view that shocks play a crucial role in powering these synchrotron sources. We suggest that the relic is originated by shock re-acceleration of relativistic electrons rather than acceleration from the thermal pool. The position and curvature of the shock and the associated relic are consistent with an off-axis merger with unequal mass ratio where the shock is expected to bend around the core of the less massive cluster.
ABELL 1201: A MINOR MERGER AT SECOND CORE PASSAGE
Ma Chengjiun; Nulsen, Paul E. J.; McNamara, Brian R.; Murray, Stephen S.; Owers, Matt; Couch, Warrick J.
2012-06-20
We present an analysis of the structures and dynamics of the merging cluster Abell 1201, which has two sloshing cold fronts around a cooling core, and an offset gas core approximately 500 kpc northwest of the center. New Chandra and XMM-Newton data reveal a region of enhanced brightness east of the offset core, with breaks in surface brightness along its boundary to the north and east. This is interpreted as a tail of gas stripped from the offset core. Gas in the offset core and the tail is distinguished from other gas at the same distance from the cluster center chiefly by having higher density, hence lower entropy. In addition, the offset core shows marginally lower temperature and metallicity than the surrounding area. The metallicity in the cool core is high and there is an abrupt drop in metallicity across the southern cold front. We interpret the observed properties of the system, including the placement of the cold fronts, the offset core, and its tail in terms of a simple merger scenario. The offset core is the remnant of a merging subcluster, which first passed pericenter southeast of the center of the primary cluster and is now close to its second pericenter passage, moving at {approx_equal} 1000 km s{sup -1}. Sloshing excited by the merger gave rise to the two cold fronts and the disposition of the cold fronts reveals that we view the merger from close to the plane of the orbit of the offset core.
The Sunyaev-Zel'dovich Effect Spectrum of Abell 2163
NASA Technical Reports Server (NTRS)
LaRoque, S. J.; Carlstrom, J. E.; Reese, E. D.; Holder, G. P.; Holzapfel, W. L.; Joy, M.; Grego, L.; Six, N. Frank (Technical Monitor)
2002-01-01
We present an interferometric measurement of the Sunyaev-Zel'dovich effect (SZE) at 1 cm for the galaxy cluster Abell 2163. We combine this data point with previous measurements at 1.1, 1.4, and 2.1 mm from the SuZIE experiment to construct the most complete SZE spectrum to date. The intensity in four wavelength bands is fit to determine the Compton y-parameter (y(sub 0)) and the peculiar velocity (v(sub p)) for this cluster. Our results are y(sub 0) = 3.56((sup +0.41+0.27)(sub -0.41-0.19)) X 10(exp -4) and v(sub p) = 410((sup +1030+460) (sub -850-440)) km s(exp -1) where we list statistical and systematic uncertainties, respectively, at 68% confidence. These results include corrections for contamination by Galactic dust emission. We find less contamination by dust emission than previously reported. The dust emission is distributed over much larger angular scales than the cluster signal and contributes little to the measured signal when the details of the SZE observing strategy are taken into account.
Dynamical analysis of galaxy cluster merger Abell 2146
NASA Astrophysics Data System (ADS)
White, J. A.; Canning, R. E. A.; King, L. J.; Lee, B. E.; Russell, H. R.; Baum, S. A.; Clowe, D. I.; Coleman, J. E.; Donahue, M.; Edge, A. C.; Fabian, A. C.; Johnstone, R. M.; McNamara, B. R.; O'Dea, C. P.; Sanders, J. S.
2015-11-01
We present a dynamical analysis of the merging galaxy cluster system Abell 2146 using spectroscopy obtained with the Gemini Multi-Object Spectrograph on the Gemini North telescope. As revealed by the Chandra X-ray Observatory, the system is undergoing a major merger and has a gas structure indicative of a recent first core passage. The system presents two large shock fronts, making it unique amongst these rare systems. The hot gas structure indicates that the merger axis must be close to the plane of the sky and that the two merging clusters are relatively close in mass, from the observation of two shock fronts. Using 63 spectroscopically determined cluster members, we apply various statistical tests to establish the presence of two distinct massive structures. With the caveat that the system has recently undergone a major merger, the virial mass estimate is M_vir= 8.5^{+4.3}_{-4.7} × 10^{14} M_{⊙} for the whole system, consistent with the mass determination in a previous study using the Sunyaev-Zel'dovich signal. The newly calculated redshift for the system is z = 0.2323. A two-body dynamical model gives an angle of 13°-19° between the merger axis and the plane of the sky, and a time-scale after first core passage of ≈0.24-0.28 Gyr.
An optical analysis of the merging cluster Abell 3888
NASA Astrophysics Data System (ADS)
Shakouri, S.; Johnston-Hollitt, M.; Dehghan, S.
2016-05-01
In this paper we present new AAOmega spectroscopy of 254 galaxies within a 30 arcmin radius around Abell 3888. We combine these data with the existing redshifts measured in a one degree radius around the cluster and performed a substructure analysis. We confirm 71 member galaxies within the core of A3888 and determine a new average redshift and velocity dispersion for the cluster of 0.1535 ± 0.0009 and 1181 ± 197 km s-1, respectively. The cluster is elongated along an East-West axis and we find the core is bimodal along this axis with two subgroups of 26 and 41 members detected. Our results suggest that A3888 is a merging system putting to rest the previous conjecture about the morphological status of the cluster derived from X-ray observations. In addition to the results on A3888 we also present six newly detected galaxy overdensities in the field, three of which we classify as new galaxy clusters.
The Radio Luminosity Function and Galaxy Evolution of Abell 2256
NASA Astrophysics Data System (ADS)
Forootaninia, Zahra
2015-05-01
This thesis presents a study of the radio luminosity function and the evolution of galaxies in the Abell 2256 cluster (z=0.058, richness class 2). Using the NED database and VLA deep data with an rms sensitivity of 18 mu Jy.beam--1, we identified 257 optical galaxies as members of A2256, of which 83 are radio galaxies. Since A2256 is undergoing a cluster-cluster merger, it is a good candidate to study the radio activity of galaxies in the cluster. We calculated the Univariate and Bivariate radio luminosity functions for A2256, and compared the results to studies on other clusters. We also used the SDSS parameter fracDev to roughly classify galaxies as spirals and ellipticals, and investigated the distribution and structure of galaxies in the cluster. We found that most of the radio galaxies in A2256 are faint, and are distributed towards the outskirts of the cluster. On the other hand, almost all very bright radio galaxies are ellipticals which are located at the center of the cluster. We also found there is an excess in the number of radio spiral galaxies in A2256 compared to the number of radio ellipticals, counting down to a radio luminosity of log(luminosity)=20.135 W/Hz..
Measuring Galaxy Properties in the Cluster Abell 160
NASA Astrophysics Data System (ADS)
Koontz, Craig; Pinkney, Jason
2007-10-01
We develop a procedure for building a large catalog of cluster galaxies and their photometric properties, as measured with CCDs. Our first case, Abell 160, is relatively nearby and we have already obtained spectroscopic redshifts for its brightest galaxies. We have mosaiced this cluster in R and V filters using a CCD imager on the 1.3-meter McGraw-Hill telescope. We fit a world coordinate system to the images using the software ``WCStools.'' We use ``SExtractor'' to extract sources from the images. We create software for merging catalogs in such a way as to avoid double counting, to reject cosmic rays, and to combine redundant measurements. The measured properties include magnitude, ellipticity, position angle, size, and color (V-R). We investigate the efficacy of our separation of galaxies and stars and find that it begins breaking down around R=19.0. We attempt to separate cluster members from foreground and background galaxies using the color-magnitude relation. In future work, we will investigate substructure (clumping) within clusters and its correlation with galaxy properties (especially color, size and morphology).
Galaxy Properties and Substructure in the Cluster Abell 160
NASA Astrophysics Data System (ADS)
Koontz, Craig; Pinkney, Jason
2009-04-01
We have developed a procedure for building a large catalog of cluster galaxies and their photometric properties as measured with CCDs. Our first case, Abell 160, is relatively nearby and redshifts exist for its brightest galaxies. We have mosaiced this cluster in R and V filters using a CCD imager on the 1.3-meter McGraw-Hill telescope. We fitted a world coordinate system to the images using the software ``WCStools,'' then used ``Source Extractor'' to extract sources from the images. We have created software for merging catalogs in such a way as to avoid double counting, to reject cosmic rays, and to combine redundant measurements. The software also corrects magnitude differences by comparing the mean difference and adding this to each individual catalog before merging it to a master catalog. The measured properties included in this study were magnitude, ellipticity, position angle, size, and color (V-R). We investigate the efficacy of our separation of galaxies and stars and find that it begins breaking down around R=19.0. We divide our master catalog into several subsamples for substructure analysis. For one subsample, we attempt to separate cluster members from foreground and background galaxies using the color-magnitude relation. We compare the results of substructure diagnostics for the subsamples. In future work, we will examine correlation of substructure with galaxy properties (especially color, size and morphology).
Shedding light on the matter of Abell 781
NASA Astrophysics Data System (ADS)
Wittman, D.; Dawson, William; Benson, Bryant
2014-02-01
The galaxy cluster Abell 781 West has been viewed as a challenge to weak gravitational lensing mass calibration, as Cook & dell'Antonio found that the weak lensing signal-to-noise ratio in three independent sets of observations was consistently lower than expected from mass models based on X-ray and dynamical measurements. We correct some errors in statistical inference in Cook & dell'Antonio and show that their own results agree well with the dynamical mass and exhibit at most 2.2-2.9σ low compared to the X-ray mass, similar to the tension between the dynamical and X-ray masses. Replacing their simple magnitude cut with weights based on source photometric redshifts eliminates the tension between lensing and X-ray masses; in this case the weak lensing mass estimate is actually higher than, but still in agreement with, the dynamical estimate. A comparison of lensing analyses with and without photometric redshifts shows that a 1-2σ chance alignment of low-redshift sources lowers the signal-to-noise ratio observed by all previous studies which used magnitude cuts rather than photometric redshifts. The fluctuation is unexceptional, but appeared to be highly significant in Cook & dell'Antonio due to the errors in statistical interpretation.
Infrared observations of gravitational lensing in Abell 2219 with CIRSI
NASA Astrophysics Data System (ADS)
Gray, Meghan E.; Ellis, Richard S.; Refregier, Alexandre; Bézecourt, Jocelyn; McMahon, Richard G.; Beckett, Martin G.; Mackay, Craig D.; Hoenig, Michael D.
2000-10-01
We present the first detection of a gravitational depletion signal at near-infrared wavelengths, based on deep panoramic images of the cluster Abell 2219 (z=0.22) taken with the Cambridge Infrared Survey Instrument (CIRSI) at the prime focus of the 4.2-m William Herschel Telescope. Infrared studies of gravitational depletion offer a number of advantages over similar techniques applied at optical wavelengths, and can provide reliable total masses for intermediate-redshift clusters. Using the maximum-likelihood technique developed by Schneider, King & Erben, we detect the gravitational depletion at the 3σ confidence level. By modelling the mass distribution as a singular isothermal sphere and ignoring the uncertainty in the unlensed number counts, we find an Einstein radius of θE ~= 13.7+3.9-4.2 arcsec (66per cent confidence limit). This corresponds to a projected velocity dispersion of σv~800kms-1, in agreement with constraints from strongly lensed features. For a Navarro, Frenk & White mass model, the radial dependence observed indicates a best-fitting halo scalelength of 125h-1kpc. We investigate the uncertainties arising from the observed fluctuations in the unlensed number counts, and show that clustering is the dominant source of error. We extend the maximum-likelihood method to include the effect of incompleteness, and discuss the prospects of further systematic studies of lensing in the near-infrared band.
Chandra Observations of Point Sources in Abell 2255
NASA Technical Reports Server (NTRS)
Davis, David S.; Miller, Neal A.; Mushotzky, Richard F.
2003-01-01
In our search for "hidden" AGN we present results from a Chandra observation of the nearby cluster Abell 2255. Eight cluster galaxies are associated with point-like X-ray emission, and we classify these galaxies based on their X-ray, radio, and optical properties. At least three are associated with active galactic nuclei (AGN) with no optical signatures of nuclear activity, with a further two being potential AGN. Of the potential AGN, one corresponds to a galaxy with a post-starburst optical spectrum. The remaining three X-ray detected cluster galaxies consist of two starbursts and an elliptical with luminous hot gas. Of the eight cluster galaxies five are associated with luminous (massive) galaxies and the remaining three lie in much lower luminosity systems. We note that the use of X-ray to optical flux ratios for classification of X-ray sources is often misleading, and strengthen the claim that the fraction of cluster galaxies hosting an AGN based on optical data is significantly lower than the fraction based on X-ray and radio data.
U(1)-invariant membranes: The geometric formulation, Abel, and pendulum differential equations
Zheltukhin, A. A.; Trzetrzelewski, M.
2010-06-15
The geometric approach to study the dynamics of U(1)-invariant membranes is developed. The approach reveals an important role of the Abel nonlinear differential equation of the first type with variable coefficients depending on time and one of the membrane extendedness parameters. The general solution of the Abel equation is constructed. Exact solutions of the whole system of membrane equations in the D=5 Minkowski space-time are found and classified. It is shown that if the radial component of the membrane world vector is only time dependent, then the dynamics is described by the pendulum equation.
The Sunyaev-Zel'dovich Effect in Abell 370
NASA Technical Reports Server (NTRS)
Grego, Laura; Carlstrom, John E.; Joy, Marshall K.; Reese, Erik D.; Holder, Gilbert P.; Patel, Sandeep; Holzapfel, William L.; Cooray, Asantha K.
1999-01-01
We present interferometric measurements of the Sunyaev-Zel'dovich (SZ) effect towards the galaxy cluster Abell 370. These measurements, which directly probe the pressure of the cluster's gas, show the gas is strongly aspherical, on agreement with the morphology revealed by x-ray and gravitational lensing observations. We calculate the cluster's gas mass fraction by comparing the gas mass derived from the SZ measurements to the lensing-derived gravitational mass near the critical lensing radius. We also calculate the gas mass fraction from the SZ data by deriving the total mass under the assumption that the gas is in hydrostatic equilibrium (HSE). We test the assumptions in the HSE method by comparing the total cluster mass implied by the two methods. The Hubble constant derived for this cluster, when the known systematic uncertainties are included, has a very wide range of values and therefore does not provide additional constraints on the validity of the assumptions. We examine carefully the possible systematic errors in the gas fraction measurement. The gas fraction is a lower limit to the cluster's baryon fraction and so we compare the gas mass fraction, calibrated by numerical simulations to approximately the virial radius, to measurements of the global mass fraction of baryonic matter, OMEGA(sub B)/OMEGA(sub matter). Our lower limit to the cluster baryon fraction is f(sub B) = (0.043 +/- 0.014)/h (sub 100). From this, we derive an upper limit to the universal matter density, OMEGA(sub matter) <= 0.72/h(sub 100), and a likely value of OMEGA(sub matter) <= (0.44(sup 0.15, sub -0.12)/h(sub 100).
Galaxy Properties and Substructure in the Cluster Abell 160
NASA Astrophysics Data System (ADS)
Koontz, Craig; Pinkney, Jason
2008-10-01
We continue development of a procedure for building a large catalog of cluster galaxies and their photometric properties, as measured with CCDs. Our first case, Abell 160, is relatively nearby and we have already obtained spectroscopic redshifts for its brightest galaxies. We have mosaiced this cluster in R and V filters using a CCD imager on the 1.3-meter McGraw-Hill telescope. For each CCD frame we fit a WCS (world coordinate system), remove bright cosmic rays, and extract sources using ``SExtractor.'' We create software for merging source catalogs in such a way as to reject residual cosmic rays and other invalid sources, and to combine redundant measurements without double counting. The measured properties include magnitude, ellipticity, position angle, size, and color (V-R). We compare our data to those of the HST (Hubble Space Telescope) and SDSS (Sloan Digital Sky Survey) archives to examine the accuracy of our star/galaxy separation and our color measurements. For our substructure investigation, we draw several subsamples of galaxies based on stellarity index, color (the color-magnitude relation), magnitude and velocity. The smallest subsample of spectroscopically confirmed members produces significant substructure signals from 1D (velocity) and 3D (x,y,velocity) diagnostics - a small, offset group may be the culprit. The 2D (x,y) diagnostics applied to the larger samples produce some significant statistics, the cause does not seem to be a large-scale merger, but perhaps several small groups. This is consistent with previous X-ray data showing X-ray emitting gas clumped around small groupings of galaxies.
Advances in the Natural transform
NASA Astrophysics Data System (ADS)
Belgacem, F. B. M.; Silambarasan, R.
2012-11-01
The literature review of the Natural transform and the existing definitions and connections to the Laplace and Sumudu transforms are discussed in this communication. Along with the complex inverse Natural transform and Heaviside's expansion formula, the relation of Bessel's function to Natural transform (and hence Laplace and Sumudu transforms) are defined.
NASA Astrophysics Data System (ADS)
Sergienko, Olga
2013-04-01
Since Doug MacAyeal's pioneering studies of the ice-stream basal traction optimizations by control methods, inversions for unknown parameters (e.g., basal traction, accumulation patterns, etc) have become a hallmark of the present-day ice-sheet modeling. The common feature of such inversion exercises is a direct relationship between optimized parameters and observations used in the optimization procedure. For instance, in the standard optimization for basal traction by the control method, ice-stream surface velocities constitute the control data. The optimized basal traction parameters explicitly appear in the momentum equations for the ice-stream velocities (compared to the control data). The inversion for basal traction is carried out by minimization of the cost (or objective, misfit) function that includes the momentum equations facilitated by the Lagrange multipliers. Here, we build upon this idea, and demonstrate how to optimize for parameters indirectly related to observed data using a suite of nested constraints (like Russian dolls) with additional sets of Lagrange multipliers in the cost function. This method opens the opportunity to use data from a variety of sources and types (e.g., velocities, radar layers, surface elevation changes, etc.) in the same optimization process.
VizieR Online Data Catalog: Deep spectroscopy of Abell 85 (Agulli+, 2016)
NASA Astrophysics Data System (ADS)
Agulli, I.; Aguerri, J. A. L.; Sanchez-Janssen, R.; Dalla Vecchia, C.; Diaferio, A.; Barrena, R.; Palmero, L. D.; Yu, H.
2016-07-01
File a85_memb.dat contains 5 columns with the sky coordinates (RA;DE), the r and g band magnitudes and the recessional velocities for each 460 confirmed members of Abell 85 cluster. Details on the data set can be found in the paper. (1 data file).
Abell 58 - a Planetary Nebula with an ONe-rich knot: a signature of binary interaction? .
NASA Astrophysics Data System (ADS)
Lau, H. H. B.; De Marco, O.; Liu, X.-W.
We have investigated the possibility that binary evolution is involved in the formation of the planetary nebula Abell 58. In particular, we assume a neon nova is responsible for the observed high oxygen and neon abundances of the central hydrogen-deficient knot of the H-deficient planetary nebula Abell 58 and the ejecta from the explosion are mixed with the planetary nebula. We have investigated different scenarios involving mergers and wind accretion and found that the most promising formation scenario involves a primary SAGB star that ends its evolution as an ONe white dwarf with an AGB companion at a moderately close separation. Mass is deposited on the white dwarf through wind accretion. So neon novae could occur just after the secondary AGB companion undergoes its final flash. However, the initial separation has to be fine-tuned. To estimate the frequency of such systems we evolve a population of binary systems and find that that Abell 58-like objects should indeed be rare and the fraction of Abell-58 planetary nebula is on the order of 10-4, or lower, among all planetary nebulae.
Dark matter distribution in the merging cluster Abell 2163
NASA Astrophysics Data System (ADS)
Soucail, G.
2012-04-01
Context. The cluster Abell 2163 is a merging system of several subclusters with complex dynamics. It presents exceptional X-rays properties (high temperature and luminosity), suggesting that it is a very massive cluster. Recent 2D analysis of the gas distribution has revealed a complex and multiphase structure. Aims: This paper presents a wide-field weak lensing study of the dark matter distribution in the cluster in order to provide an alternative vision of the merging status of the cluster. The 2D mass distribution was built and compared to the galaxies and gas distributions. Methods: A Bayesian method, implemented in the Im2shape software, was used to fit the shape parameters of the faint background galaxies and to correct for PSF smearing. A careful color selection on the background galaxies was applied to retrieve the weak lensing signal. Shear signal was measured out to more than 2 Mpc (≃12' from the center). The radial shear profile was fit with different parametric mass profiles. The 2D mass map was built from the shear distribution and used to identify the different mass components. Results: The 2D mass map agrees with the galaxy distribution, while the total mass inferred from weak lensing shows a strong discrepancy to the X-ray deduced mass. Regardless of the method used, the virial mass M200 falls in the range 8 to 14 × 1014 h70-1 M⊙, a value that is two times less than the mass deduced from X-rays. The central mass clump appears bimodal in the dark matter distribution, with a mass ratio ~3:1 between the two components. The infalling clump A2163-B is detected in weak lensing as an independent entity. All these results are interpreted in the context of a multiple merger seen less than 1 Gyr after the main crossover. Based on observations obtained with MegaPrime/MegaCam, a joint project of Canada-France-Hawaii Telescope (CFHT) and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council (NRC) of
MUSE observations of the lensing cluster Abell 1689
NASA Astrophysics Data System (ADS)
Bina, D.; Pelló, R.; Richard, J.; Lewis, J.; Patrício, V.; Cantalupo, S.; Herenz, E. C.; Soto, K.; Weilbacher, P. M.; Bacon, R.; Vernet, J. D. R.; Wisotzki, L.; Clément, B.; Cuby, J. G.; Lagattuta, D. J.; Soucail, G.; Verhamme, A.
2016-05-01
Context. This paper presents the results obtained with the Multi Unit Spectroscopic Explorer (MUSE) for the core of the lensing cluster Abell 1689, as part of MUSE's commissioning at the ESO Very Large Telescope. Aims: Integral-field observations with MUSE provide a unique view of the central 1 × 1 arcmin2 region at intermediate spectral resolution in the visible domain, allowing us to conduct a complete census of both cluster galaxies and lensed background sources. Methods: We performed a spectroscopic analysis of all sources found in the MUSE data cube. Two hundred and eighty-two objects were systematically extracted from the cube based on a guided-and-manual approach. We also tested three different tools for the automated detection and extraction of line emitters. Cluster galaxies and lensed sources were identified based on their spectral features. We investigated the multiple-image configuration for all known sources in the field. Results: Previous to our survey, 28 different lensed galaxies displaying 46 multiple images were known in the MUSE field of view, most of them were detected through photometric redshifts and lensing considerations. Of these, we spectroscopically confirm 12 images based on their emission lines, corresponding to 7 different lensed galaxies between z = 0.95 and 5.0. In addition, 14 new galaxies have been spectroscopically identified in this area thanks to MUSE data, with redshifts ranging between 0.8 and 6.2. All background sources detected within the MUSE field of view correspond to multiple-imaged systems lensed by A1689. Seventeen sources in total are found at z ≥ 3 based on their Lyman-α emission, with Lyman-α luminosities ranging between 40.5 ≲ log (Lyα) ≲ 42.5 after correction for magnification. This sample is particularly sensitive to the slope of the luminosity function toward the faintest end. The density of sources obtained in this survey is consistent with a steep value of α ≤ -1.5, although this result still
A weak-lensing analysis of the Abell 383 cluster
NASA Astrophysics Data System (ADS)
Huang, Z.; Radovich, M.; Grado, A.; Puddu, E.; Romano, A.; Limatola, L.; Fu, L.
2011-05-01
Aims: We use deep CFHT and SUBARU uBVRIz archival images of the Abell 383 cluster (z = 0.187) to estimate its mass by weak-lensing. Methods: To this end, we first use simulated images to check the accuracy provided by our Kaiser-Squires-Broadhurst (KSB) pipeline. These simulations include shear testing programme (STEP) 1 and 2 simulations, as well as more realistic simulations of the distortion of galaxy shapes by a cluster with a Navarro-Frenk-White (NFW) profile. From these simulations we estimate the effect of noise on shear measurement and derive the correction terms. The R-band image is used to derive the mass by fitting the observed tangential shear profile with an NFW mass profile. Photometric redshifts are computed from the uBVRIz catalogs. Different methods for the foreground/background galaxy selection are implemented, namely selection by magnitude, color, and photometric redshifts, and the results are compared. In particular, we developed a semi-automatic algorithm to select the foreground galaxies in the color-color diagram, based on the observed colors. Results: Using color selection or photometric redshifts improves the correction of dilution from foreground galaxies: this leads to higher signals in the inner parts of the cluster. We obtain a cluster mass Mvir = 7.5+2.7_{-1.9 × 1014} M⊙: this value is 20% higher than previous estimates and is more consistent the mass expected from X-ray data. The R-band luminosity function of the cluster is computed and gives a total luminosity Ltot = (2.14 ± 0.5) × 1012 L⊙ and a mass-to-luminosity ratio M/L 300 M⊙/L⊙. Based on: data collected with the Subaru Telescope (University of Tokyo) and obtained from the SMOKA, which is operated by the Astronomy Data Center, National Astronomical Observatory of Japan; observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT), which is operated by the National Research Council (NRC) of Canada
Crazy heart: kinematics of the "star pile" in Abell 545
NASA Astrophysics Data System (ADS)
Salinas, R.; Richtler, T.; West, M. J.; Romanowsky, A. J.; Lloyd-Davies, E.; Schuberth, Y.
2011-04-01
We study the structure and internal kinematics of the "star pile" in Abell 545 - a low surface brightness structure lying in the center of the cluster. We have obtained deep long-slit spectroscopy of the star pile using VLT/FORS2 and Gemini/GMOS, which is analyzed in conjunction with deep multiband CFHT/MEGACAM imaging. As presented in a previous study the star pile has a flat luminosity profile and its color is consistent with the outer parts of elliptical galaxies. Its velocity map is irregular, with parts being seemingly associated with an embedded nucleus, and others which have significant velocity offsets to the cluster systemic velocity with no clear kinematical connection to any of the surrounding galaxies. This would make the star pile a dynamically defined stellar intra-cluster component. The complicated pattern in velocity and velocity dispersions casts doubts on the adequacy of using the whole star pile as a dynamical test for the innermost dark matter profile of the cluster. This status is fulfilled only by the nucleus and its nearest surroundings which lie at the center of the cluster velocity distribution. Based on observations taken at the European Southern Observatory, Cerro Paranal, Chile, under programme ID 080.B-0529. Also based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Science and Technology Facilities Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência e Tecnologia (Brazil) and SECYT (Argentina); and on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council (NRC) of Canada, the Institut National
NASA Technical Reports Server (NTRS)
Goel, N. S.; Thompson, R. L.; Strebel, D. E.
1984-01-01
The technique for inverting a vegetation canopy reflectance model described earlier (Goel and Strebel, 1983) is investigated further. The novel concept of an 'angle transform' is introduced. This concept allows the formation of functions of reflectances at different view zenith and azimuth angles, which are either sensitive or insensitive to a certain agronomic parameter. A proper combination of these functions can allow determination of all the important agronomic and spectral parameters from measured canopy reflectance data. The technique is demonstrated using Suits' (1972) model for homogeneous canopies. It is shown that leaf area index, leaf reflectance and transmittance, and average leaf angle all can be determined from the canopy reflectance at a set of selected view zenith and azimuth angles. A sensitivity analysis of the calculated values to the errors in the data is also carried out. Guidelines are formulated for the number and types of observations required to obtain the values of a particular canopy variable to within a given degree of accuracy for a given level of error in the measurement of canopy reflectance.
NASA Astrophysics Data System (ADS)
Nath, Saurabh; Mukherjee, Anish; Chatterjee, Souvick; Ganguly, Ranjan; Sen, Swarnendu; Mukhopadhyay, Achintya; Boreyko, Jonathan
2014-11-01
We have observed that capillarity forces may cause floatation in a few non-intuitive configurations. These may be divided into 2 categories: i) floatation of heavier liquid droplets on lighter immiscible ones and ii) fully submerged floatation of lighter liquid droplets in a heavier immiscible medium. We call these counter-intuitive because of the inverse floatation configuration. For case (i) we have identified and studied in detail the several factors affecting the shape and maximum volume of the floating drop. We used water and vegetable oil combinations as test fluids and established the relation between Bond Number and maximum volume contained in a floating drop (in the order of μL). For case (ii), we injected vegetable oil drop-wise into a pool of water. The fully submerged configuration of the drop is not stable and a slight perturbation to the system causes the droplet to burst and float in partially submerged condition. Temporal variation of a characteristic length of the droplet is analyzed using MATLAB image processing. The constraint of small Bond Number establishes the assumption of lubrication regime in the thin gap. A brief theoretical formulation also shows the temporal variation of the gap thickness. Jadavpur University, Jagadis Bose Centre of Excellence, Virginia Tech.
The nature of the driving mechanism in the pulsating hybrid PG 1159 star Abell 43
NASA Astrophysics Data System (ADS)
Quirion, P.-O.; Fontaine, G.; Brassard, P.
2005-10-01
We extend our previous pulsational stability analyses of PG 1159 stars by modeling the hybrid PG 1159 type star Abell 43. We show that the standard κ-mechanism due to the ionization of C and O in the envelope of this H-rich PG 1159 star is perfectly able to drive g-mode pulsations. Thus, contrary to a recent suggestion, there is no need to invoke any new or exotic mechanism to explain the pulsational instabilities observed in this particular star. Our expected instability band for l=1 modes extends in period from ~2604 s to ~5529 s, which is consistent with the available photometric observations of Abell 43. We also suggest that efforts to detect luminosity variations in its sibling NGC 7094 be pursued.
UV Observations of the Galaxy Cluster Abell 1795 with the Optical Monitor on XMM-Newton
NASA Technical Reports Server (NTRS)
Mittaz, J. P. D.; Kaastra, J. S.; Tamura, T.; Fabian, A. C.; Mushotzky, F.; Peterson, J. R.; Ikebe, Y.; Lumb, D. H.; Paerels, F.; Stewart, G.
2000-01-01
We present the results of an analysis of broad band UV observations of the central regions of Abell 1795 observed with the optical monitor on XMM-Newton. As have been found with other UV observations of the central regions of clusters of galaxies, we find evidence for star formation. However, we also find evidence for absorption in the cD galaxy on a more extended scale than has been seen with optical imaging. We also report the first UV observation of part of the filamentary structure seen in H-alpha, X-rays and very deep U band imaging. The part of the filament we see is very blue with UV colours consistent with a very early (O/B) stellar population. This is the first direct evidence of a dominant population of early type stars at the centre of Abell 1795 and implies very recent star formation. The relationship of this emission to emission at other wavebands is discussed.
VizieR Online Data Catalog: Halpha measurements in Abell 2465 (Wegner+, 2015)
NASA Astrophysics Data System (ADS)
Wegner, G. A.; Chu, D. S.; Hwang, H. S.
2015-07-01
The wavelength of the Hα line at the redshift of Abell 2465 is near 817nm in a clear spectral region between the many telluric emission lines. A custom narrow-band filter for observing Hα was obtained from the Andover Corp. It has a peak transmission at 817.7nm (m817) and a full width at half-maximum (FWHM) of 8.77nm. The wide filter was a Gunn i (ig) filter with nearly the same central wavelength of 820nm and a FWHM of 185nm, and was manufactured by Custom Scientific. Hα observations of Abell 2465 were obtained 2012 September 19-23 using the 2.4m Hiltner telescope at the MDM Observatory on Kitt Peak. The 'Nellie' CCD was used. (1 data file).
A survey by HEAO 1 of clusters of galaxies. III - The complete Abell catalog
NASA Technical Reports Server (NTRS)
Johnson, M. W.; Cruddace, R. G.; Wood, K. S.; Ulmer, M. P.; Kowalski, M. P.
1983-01-01
A catalog of 128 X-ray emitting clusters, including the Virgo Cluster, is presented. Ninety-one of these are new identifications. The catalog was obtained by searching the HEAO 1 survey observations for coincidences of X-ray sources with Abell clusters. The distribution of these sources in the sky has been examined in search of associations with other Abell clusters, with a null result. The X-ray luminosity has been correlated with cluster richness, but no association with Bautz-Morgan class has been found. The cluster luminosity function has been evaluated, and using this function the contribution of clusters to the diffuse X-ray background radiation has been estimated. It amounts to less than 15% at 2 keV and 3% at 6 keV.
A combined optical/X-ray study of the Galaxy cluster Abell 2256
NASA Technical Reports Server (NTRS)
Fabricant, Daniel G.; Kent, Stephen M.; Kurtz, Michael J.
1989-01-01
The dynamics of Abell 2256 is investigated by combining X-ray observations of the intracluster gas with optical observations of the galaxy distribution and kinematics. Magnitudes and positions are presented for 172 galaxies and new redshifts for 75. Abell 2256 is similar to the Coma Cluster in its X-ray luminosity, mass, and galaxy density. Both the X-ray surface brightness and the galaxy surface density distributions exhibit an elliptical morphology. The radial galaxy distribution is steeper than the density profile of the X-ray-emitting gas, yet the galaxy velocity dispersion is higher than the equivalent value for the gas. Under the simplest assumptions that the galaxy velocity distribution is isotropic and the gas is isothermal, the galaxies and gas cannot be in hydrostatic equilibrium in a common gravitational potential. Models consistent with available data have mass-to-light ratios which increase with radius and galaxy orbits that are anisotropic with a radial bias.
An X-ray temperature map of Abell 754: A major merger
NASA Technical Reports Server (NTRS)
Henry, J. Patrick; Briel, Ulrich G.
1995-01-01
We present the first two-dimensional X-ray temperature map of the rich cluster of galaxies Abell 754. We also present an X-ray surface brightness map with improved spatial resolution and sensitivity compared with previous maps. Both the temperature map and the surface brightness map show that A754 is in the throes of a violent merger; it is probably far from hydrostatic equilibrium.
Statistical analysis of catalogs of extragalactic objects. II - The Abell catalog of rich clusters
NASA Technical Reports Server (NTRS)
Hauser, M. G.; Peebles, P. J. E.
1973-01-01
The results of a power-spectrum analysis are presented for the distribution of clusters in the Abell catalog. Clear and direct evidence is found for superclusters with small angular scale, in agreement with the recent study of Bogart and Wagoner (1973). It is also found that the degree and angular scale of the apparent superclustering varies with distance in the manner expected if the clustering is intrinsic to the spatial distribution rather than a consequence of patchy local obscuration.
RELICS Discovery of a Probable Lens-magnified SN behind Galaxy Cluster Abell 1763
NASA Astrophysics Data System (ADS)
Rodney, S.; Coe, D.; Bradley, L.; Strolger, L.; Brammer, G.; Avila, R.; Ryan, R.; Ogaz, S.; Riess, A.; Sharon, K.; Johnson, T.; Paterno-Mahler, R.; Molino, A.; Graham, M.; Kelly, P.; Filippenko, A.; Frye, B.; Foley, R.; Schmidt, K.; Umetsu, K.; Czakon, N.; Weiner, B.; Stark, D.; Mainali, R.; Zitrin, A.; Sendra, I.; Graur, O.; Grillo, C.; Hjorth, J.; Selsing, J.; Christensen, L.; Rosati, P.; Nonino, M.; Balestra, I.; Vulcani, B.; McCully, C.; Dawson, W.; Bouwens, R.; Lam, D.; Trenti, M.; Nunez, D. Carrasco; Matheson, T.; Merten, J.; Jha, S.; Jones, C.; Andrade-Santos, F.; Salmon, B.; Bradac, M.; Hoag, A.; Huang, K.; Wang, X.; Oesch, P.
2016-07-01
We report the discovery of a likely supernova (SN) in the background field of the galaxy cluster Abell 1763 (a.k.a. RXC J1335.3+4059, ZwCl 1333.7+4117). The SN candidate was detected in Hubble Space Telescope (HST) observations collected on June 17, 2016 as part of the Reionization Lensing Cluster Survey (RELICS, HST program ID: 14096, PI: D.Coe).
The Extraordinary Amount of Substructure in the Hubble Frontier Fields Cluster Abell 2744
NASA Astrophysics Data System (ADS)
Jauzac, M.; Eckert, D.; Schwinn, J.; Harvey, D.; Baugh, C. M.; Robertson, A.; Bose, S.; Massey, R.; Owers, M.; Ebeling, H.; Shan, H. Y.; Jullo, E.; Kneib, J.-P.; Richard, J.; Atek, H.; Clément, B.; Egami, E.; Israel, H.; Knowles, K.; Limousin, M.; Natarajan, P.; Rexroth, M.; Taylor, P.; Tchernin, C.
2016-09-01
We present a joint optical/X-ray analysis of the massive galaxy cluster Abell 2744 (z=0.308). Our strong- and weak-lensing analysis within the central region of the cluster, i.e., at R < 1 Mpc from the brightest cluster galaxy, reveals eight substructures, including the main core. All of these dark-matter halos are detected with a significance of at least 5σ and feature masses ranging from 0.5 to 1.4× 1014M⊙ within R < 150 kpc. Merten et al. (2011) and Medezinski et al. (2016) substructures are also detected by us. We measure a slightly higher mass for the main core component than reported previously and attribute the discrepancy to the inclusion of our tightly constrained strong-lensing mass model built on Hubble Frontier Fields data. X-ray data obtained by XMM-Newton reveal four remnant cores, one of them a new detection, and three shocks. Unlike Merten et al. (2011), we find all cores to have both dark and luminous counterparts. A comparison with clusters of similar mass in the MXXL simulations yields no objects with as many massive substructures as observed in Abell 2744, confirming that Abell 2744 is an extreme system. We stress that these properties still do not constitute a challenge to ΛCDM, as caveats apply to both the simulation and the observations: for instance, the projected mass measurements from gravitational lensing and the limited resolution of the sub-haloes finders. We discuss implications of Abell 2744 for the plausibility of different dark-matter candidates and, finally, measure a new upper limit on the self-interaction cross-section of dark matter of σDM < 1.28 cm2g-1(68% CL), in good agreement with previous results from Harvey et al. (2015).
High-Performance Mixed Models Based Genome-Wide Association Analysis with omicABEL software
Fabregat-Traver, Diego; Sharapov, Sodbo Zh.; Hayward, Caroline; Rudan, Igor; Campbell, Harry; Aulchenko, Yurii; Bientinesi, Paolo
2014-01-01
To raise the power of genome-wide association studies (GWAS) and avoid false-positive results in structured populations, one can rely on mixed model based tests. When large samples are used, and when multiple traits are to be studied in the ’omics’ context, this approach becomes computationally challenging. Here we consider the problem of mixed-model based GWAS for arbitrary number of traits, and demonstrate that for the analysis of single-trait and multiple-trait scenarios different computational algorithms are optimal. We implement these optimal algorithms in a high-performance computing framework that uses state-of-the-art linear algebra kernels, incorporates optimizations, and avoids redundant computations, increasing throughput while reducing memory usage and energy consumption. We show that, compared to existing libraries, our algorithms and software achieve considerable speed-ups. The OmicABEL software described in this manuscript is available under the GNU GPL v. 3 license as part of the GenABEL project for statistical genomics at http: //www.genabel.org/packages/OmicABEL. PMID:25717363
The Two-Point Spatial Correlation Function for the MX Northern Abell Cluster Survey
NASA Astrophysics Data System (ADS)
Miller, C. J.; Slinglend, K. A.; Batuski, D. J.; Hill, J.
1997-12-01
The results from the COBE satellite show the existence of structure in the cosmic microwave background radiation on scales ~ 10% or more of the horizon scale of the Universe. Rich clusters of galaxies from the Abell/ACO catalogs show evidence of structure on scales of 100h(-1) Mpc and hold the promise of confirming structure on the scale of the COBE results. However, previous analyses for large-scale structure based on the clusters in these catalogs suffer from small sample sizes, imcomplete samples, and large uncertainties in the measured data. Our efforts with the MX Cluster Redshift Survey have resulted in galaxy redshifts for 95 rich Abell clusters returning 88 positive cluster identifications. Five cluster fields did not supply enough data for cluster positions and two clusters were found to be simply projections of galaxies strung out along the line of sight. By obtaining an average of 9 member galaxy redshifts per cluster, we have greatly reduced uncertainty in cluster locations. The Abell catalog is now 98% complete out to m10 <= 16.8. This complete sample has provided us with the necessary data to calculate the two-point spatial correlation function, xi (r), characterized by the slope of its power-law fit gamma and a scale length r_o. Preliminary results give gamma = -2.26+/-0.14 and r_o = 21.9+/- 1.5 h(-1) Mpc. These results are then compared with other spatial analyses based on different samples.
High-Performance Mixed Models Based Genome-Wide Association Analysis with omicABEL software.
Fabregat-Traver, Diego; Sharapov, Sodbo Zh; Hayward, Caroline; Rudan, Igor; Campbell, Harry; Aulchenko, Yurii; Bientinesi, Paolo
2014-01-01
To raise the power of genome-wide association studies (GWAS) and avoid false-positive results in structured populations, one can rely on mixed model based tests. When large samples are used, and when multiple traits are to be studied in the 'omics' context, this approach becomes computationally challenging. Here we consider the problem of mixed-model based GWAS for arbitrary number of traits, and demonstrate that for the analysis of single-trait and multiple-trait scenarios different computational algorithms are optimal. We implement these optimal algorithms in a high-performance computing framework that uses state-of-the-art linear algebra kernels, incorporates optimizations, and avoids redundant computations, increasing throughput while reducing memory usage and energy consumption. We show that, compared to existing libraries, our algorithms and software achieve considerable speed-ups. The OmicABEL software described in this manuscript is available under the GNU GPL v. 3 license as part of the GenABEL project for statistical genomics at http: //www.genabel.org/packages/OmicABEL. PMID:25717363
Chandra Observation of Abell 1142: A Cool-core Cluster Lacking a Central Brightest Cluster Galaxy?
NASA Astrophysics Data System (ADS)
Su, Yuanyuan; Buote, David A.; Gastaldello, Fabio; van Weeren, Reinout
2016-04-01
Abell 1142 is a low-mass galaxy cluster at low redshift containing two comparable brightest cluster galaxies (BCGs) resembling a scaled-down version of the Coma Cluster. Our Chandra analysis reveals an X-ray emission peak, roughly 100 kpc away from either BCG, which we identify as the cluster center. The emission center manifests itself as a second beta-model surface brightness component distinct from that of the cluster on larger scales. The center is also substantially cooler and more metal-rich than the surrounding intracluster medium (ICM), which makes Abell 1142 appear to be a cool-core cluster. The redshift distribution of its member galaxies indicates that Abell 1142 may contain two subclusters, each of which contain one BCG. The BCGs are merging at a relative velocity of ≈1200 km s‑1. This ongoing merger may have shock-heated the ICM from ≈2 keV to above 3 keV, which would explain the anomalous LX–TX scaling relation for this system. This merger may have displaced the metal-enriched “cool core” of either of the subclusters from the BCG. The southern BCG consists of three individual galaxies residing within a radius of 5 kpc in projection. These galaxies should rapidly sink into the subcluster center due to the dynamical friction of a cuspy cold dark matter halo.
Deciphering the bipolar planetary nebula Abell 14 with 3D ionization and morphological studies
NASA Astrophysics Data System (ADS)
Akras, S.; Clyne, N.; Boumis, P.; Monteiro, H.; Gonçalves, D. R.; Redman, M. P.; Williams, S.
2016-04-01
Abell 14 is a poorly studied object despite being considered a born-again planetary nebula. We performed a detailed study of its 3D morphology and ionization structure using the SHAPE and MOCASSIN codes. We found that Abell 14 is a highly evolved, bipolar nebula with a kinematical age of ˜19 400 yr for a distance of 4 kpc. The high He abundance, and N/O ratio indicate a progenitor of 5 M⊙ that has experienced the third dredge-up and hot bottom burning phases. The stellar parameters of the central source reveal a star at a highly evolved stage near to the white dwarf cooling track, being inconsistent with the born-again scenario. The nebula shows unexpectedly strong [N I] λ5200 and [O I] λ6300 emission lines indicating possible shock interactions. Abell 14 appears to be a member of a small group of highly evolved, extreme type-I planetary nebulae (PNe). The members of this group lie at the lower-left corner of the PNe regime on the [N II]/Hα versus [S II]/Hα diagnostic diagram, where shock-excited regions/objects are also placed. The low luminosity of their central stars, in conjunction with the large physical size of the nebulae, result in a very low photoionization rate, which can make any contribution of shock interaction easily perceptible, even for small velocities.
ASCA Temperature Maps of Three Clusters of Galaxies: Abell 1060, AWM 7, and the Centaurus Cluster
NASA Astrophysics Data System (ADS)
Furusho, Tae; Yamasaki, Noriko Y.; Ohashi, Takaya; Shibata, Ryo; Kagei, Tomohiro; Ishisaki, Yoshitaka; Kikuchi, Ken'ichi; Ezawa, Hajime; Ikebe, Yasushi
2001-06-01
We present two-dimensional temperature maps of three bright clusters of galaxies (Abell 1060, AWM 7, and the Centaurus cluster), based on multi-pointing observations with the ASCA GIS. The temperatures were derived from hardness ratios by taking into account the XRT response. For the Centaurus cluster, we subtracted the central cool component using the previous ASCA and ROSAT results, and the metallicity gradients observed in AWM 7 and the Centaurus cluster were included in deriving the temperatures. The intracluster medium in Abell 1060 and AWM 7 is almost isothermal from the center to the outer regions with temperatures of 3.3 and 3.9 keV, respectively. The Centaurus cluster exhibits remarkable hot regions within about 30' from the cluster center, showing a temperature increase of ×0.8 keV from the surrounding level of 3.5keV, and the outer cool regions with lower temperatures by -1.3 keV. These results imply that a strong merger has occurred in the Centaurus in the recent 2-3Gyr, and that the central cool component has survived it. In contrast, the gas in Abell 1060 was well-mixed in an early period, which probably has prevented the development of a central cool component. In AWM 7, mixing of the gas should have occurred in a period earlier than the epoch of metal enrichment.
Probing single biomolecules in solution using the anti-Brownian electrokinetic (ABEL) trap.
Wang, Quan; Goldsmith, Randall H; Jiang, Yan; Bockenhauer, Samuel D; Moerner, W E
2012-11-20
Single-molecule fluorescence measurements allow researchers to study asynchronous dynamics and expose molecule-to-molecule structural and behavioral diversity, which contributes to the understanding of biological macromolecules. To provide measurements that are most consistent with the native environment of biomolecules, researchers would like to conduct these measurements in the solution phase if possible. However, diffusion typically limits the observation time to approximately 1 ms in many solution-phase single-molecule assays. Although surface immobilization is widely used to address this problem, this process can perturb the system being studied and contribute to the observed heterogeneity. Combining the technical capabilities of high-sensitivity single-molecule fluorescence microscopy, real-time feedback control and electrokinetic flow in a microfluidic chamber, we have developed a device called the anti-Brownian electrokinetic (ABEL) trap to significantly prolong the observation time of single biomolecules in solution. We have applied the ABEL trap method to explore the photodynamics and enzymatic properties of a variety of biomolecules in aqueous solution and present four examples: the photosynthetic antenna allophycocyanin, the chaperonin enzyme TRiC, a G protein-coupled receptor protein, and the blue nitrite reductase redox enzyme. These examples illustrate the breadth and depth of information which we can extract in studies of single biomolecules with the ABEL trap. When confined in the ABEL trap, the photosynthetic antenna protein allophycocyanin exhibits rich dynamics both in its emission brightness and its excited state lifetime. As each molecule discontinuously converts from one emission/lifetime level to another in a primarily correlated way, it undergoes a series of state changes. We studied the ATP binding stoichiometry of the multi-subunit chaperonin enzyme TRiC in the ABEL trap by counting the number of hydrolyzed Cy3-ATP using stepwise
GENERATING FRACTAL PATTERNS BY USING p-CIRCLE INVERSION
NASA Astrophysics Data System (ADS)
Ramírez, José L.; Rubiano, Gustavo N.; Zlobec, Borut Jurčič
2015-10-01
In this paper, we introduce the p-circle inversion which generalizes the classical inversion with respect to a circle (p = 2) and the taxicab inversion (p = 1). We study some basic properties and we also show the inversive images of some basic curves. We apply this new transformation to well-known fractals such as Sierpinski triangle, Koch curve, dragon curve, Fibonacci fractal, among others. Then we obtain new fractal patterns. Moreover, we generalize the method called circle inversion fractal be means of the p-circle inversion.
The merging cluster Abell 1758 revisited: multi-wavelength observations and numerical simulations
NASA Astrophysics Data System (ADS)
Durret, F.; Laganá, T. F.; Haider, M.
2011-05-01
Context. Cluster properties can be more distinctly studied in pairs of clusters, where we expect the effects of interactions to be strong. Aims: We here discuss the properties of the double cluster Abell 1758 at a redshift z ~ 0.279. These clusters show strong evidence for merging. Methods: We analyse the optical properties of the North and South cluster of Abell 1758 based on deep imaging obtained with the Canada-France-Hawaii Telescope (CFHT) archive Megaprime/Megacam camera in the g' and r' bands, covering a total region of about 1.05 × 1.16 deg2, or 16.1 × 17.6 Mpc2. Our X-ray analysis is based on archive XMM-Newton images. Numerical simulations were performed using an N-body algorithm to treat the dark-matter component, a semi-analytical galaxy-formation model for the evolution of the galaxies and a grid-based hydrodynamic code with a parts per million (PPM) scheme for the dynamics of the intra-cluster medium. We computed galaxy luminosity functions (GLFs) and 2D temperature and metallicity maps of the X-ray gas, which we then compared to the results of our numerical simulations. Results: The GLFs of Abell 1758 North are well fit by Schechter functions in the g' and r' bands, but with a small excess of bright galaxies, particularly in the r' band; their faint-end slopes are similar in both bands. In contrast, the GLFs of Abell 1758 South are not well fit by Schechter functions: excesses of bright galaxies are seen in both bands; the faint-end of the GLF is not very well defined in g'. The GLF computed from our numerical simulations assuming a halo mass-luminosity relation agrees with those derived from the observations. From the X-ray analysis, the most striking features are structures in the metal distribution. We found two elongated regions of high metallicity in Abell 1758 North with two peaks towards the centre. In contrast, Abell 1758 South shows a deficit of metals in its central regions. Comparing observational results to those derived from numerical
Two long H I tails in the outskirts of Abell 1367
NASA Astrophysics Data System (ADS)
Scott, T. C.; Cortese, L.; Brinks, E.; Bravo-Alfaro, H.; Auld, R.; Minchin, R.
2012-01-01
We present VLA D-array H I observations of the RSCG 42 and FGC 1287 galaxy groups, in the outskirts of the Abell 1367 cluster. These groups are projected ˜1.8 and 2.7 Mpc west from the cluster centre. The Arecibo Galaxy Environment Survey provided evidence for H I extending over as much as 200 kpc in both groups. Our new, higher resolution observations reveal that the complex H I features detected by Arecibo are in reality two extraordinary long H I tails extending for ˜160 and 250 kpc, respectively, i.e. among the longest H I structures ever observed in groups of galaxies. Although in the case of RSCG 42 the morphology and dynamics of the H I tail, as well as the optical properties of the group members, support a low-velocity tidal interaction scenario, less clear is the origin of the unique features associated with FGC 1287. This galaxy displays an exceptionally long 'dog leg' H I tail, and the large distance from the X-ray-emitting region of Abell 1367 makes a ram-pressure stripping scenario highly unlikely. At the same time, a low-velocity tidal interaction seems unable to explain the extraordinary length of the tail and the lack of any sign of disturbance in the optical properties of FGC 1287. An intriguing possibility could be that this galaxy might have recently experienced a high-speed interaction with another member of the Coma-Abell 1367 Great Wall. We searched for the interloper responsible for this feature and, although we find a possible candidate, we show that without additional observations it is impossible to settle this issue. While the mechanism responsible for this extraordinary H I tail remains to be determined, our discovery highlights how little we know about environmental effects in galaxy groups.
Temperature and elemental abundances in the Abell cluster A 576 derived from X-ray observations
NASA Technical Reports Server (NTRS)
Rothenflug, R.; Vigroux, L.; Mushotzky, R. F.; Holt, S. S.
1983-01-01
Results of Einstein solid state spectrometer observations of the central region of Abell 576 combined with HEAO 1 spectra of the total cluster are given. Line emission was detected due to Fe, Si, and S from a hot plasma in the central region. The temperature of the total cluster spectrum may be in conflict with the central temperature. This difference can be explained either if cooling takes place in the center, or if part of the measured emission is due to individual galaxies. If the X-ray emission comes from the intergalactic gas only, there is some difficulty in producing all the silicon observed in the galaxies of A 576.
Morphological study of three Abell's planetary nebulae - A33, A36, and A79
NASA Astrophysics Data System (ADS)
Hua, C. T.; Nguyen-Trong, T.
1983-01-01
The Abell list discovered in the Palomar Sky Survey includes the three objects A33, A36 and A79, which have been classified as old planetary nebulae. The monochromatic images of these three objects in H-alpha, H-beta, and the forbidden lines N II 6584 A and S II 6717 A, are presented and discussed. The forbidden line N II/H-alpha intensity ratio is found to be useful because of its implications in the evolutionary behavior of planetary nebulae.
The hydrogen-deficient knot of the `born-again' planetary nebula Abell 58 (V605 Aql)
NASA Astrophysics Data System (ADS)
Wesson, R.; Barlow, M. J.; Liu, X.-W.; Storey, P. J.; Ercolano, B.; De Marco, O.
2008-02-01
We have analysed deep optical spectra of the `born-again' planetary nebula Abell 58 and its hydrogen-deficient knot, surrounding V605 Aql, which underwent a nova-like eruption in 1919. Our analysis shows that the extinction towards the central knot is much higher than previously thought, with c(Hβ) = 2.0. The outer nebula is less reddened, with c(Hβ) = 1.04. We find that the outer nebula has a Ne/O ratio higher than the average PN value. The electron temperature we derive for the central knot varies widely depending on the diagnostic used. The [OIII] nebular-to-auroral transition ratio gives a temperature of 20800K, while the ratio of the [NII] nebular and auroral lines gives Te = 15200K. The helium line ratios λ5876/λ4471 and λ6678/λ4471 imply temperatures of 350 and 550K, respectively. Weakly temperature-sensitive OII recombination line ratios imply similarly low electron temperatures. Abundances derived from recombination lines are vastly higher than those found from collisionally excited lines, with the abundance discrepancy factor (ADF) for O2+ reaching 89 - the second highest known value after that found for the hydrogen-deficient knots in Abell 30. The observed temperature diagnostics and abundances support the idea that, like Abell 30, the knot of Abell 58 contains some very cold ionized material. Although the central star is carbon-rich (C/O > 1), the knot is found to be oxygen-rich, a situation not predicted by the single-star `born-again' theory of its formation. We compare the known properties of Abell 58 to those of Abell 30, Sakurai's Object and several novae and nova remnants. We argue that the abundances in the ejecta observed in A30 and A58 have more in common with neon novae than with Sakurai's Object, which is believed to have undergone a final helium flash. In particular, the C/O ratio of less than unity and the presence of substantial quantities of neon in the ejecta of both Abell 30 and Abell 58 are not predicted by very late thermal
The X-ray luminosity functions of Abell clusters from the Einstein Cluster Survey
NASA Technical Reports Server (NTRS)
Burg, R.; Giacconi, R.; Forman, W.; Jones, C.
1994-01-01
We have derived the present epoch X-ray luminosity function of northern Abell clusters using luminosities from the Einstein Cluster Survey. The sample is sufficiently large that we can determine the luminosity function for each richness class separately with sufficient precision to study and compare the different luminosity functions. We find that, within each richness class, the range of X-ray luminosity is quite large and spans nearly a factor of 25. Characterizing the luminosity function for each richness class with a Schechter function, we find that the characteristic X-ray luminosity, L(sub *), scales with richness class as (L(sub *) varies as N(sub*)(exp gamma), where N(sub *) is the corrected, mean number of galaxies in a richness class, and the best-fitting exponent is gamma = 1.3 +/- 0.4. Finally, our analysis suggests that there is a lower limit to the X-ray luminosity of clusters which is determined by the integrated emission of the cluster member galaxies, and this also scales with richness class. The present sample forms a baseline for testing cosmological evolution of Abell-like clusters when an appropriate high-redshift cluster sample becomes available.
Uniform upper bounds for the cyclicity of the zero solution of the Abel differential equation
NASA Astrophysics Data System (ADS)
Batenkov, Dmitry; Binyamini, Gal
2015-12-01
Given two polynomials P, q we consider the following question: "how large can the index of the first non-zero moment m˜k = ∫ab Pk q be, assuming the sequence is not identically zero?" The answer K to this question is known as the moment Bautin index, and we provide the first general upper bound: K ⩽ 2 + deg q + 3(deg P - 1) 2. The proof is based on qualitative analysis of linear ODEs, applied to Cauchy-type integrals of certain algebraic functions. The moment Bautin index plays an important role in the study of bifurcations of periodic solution in the polynomial Abel equation y‧ = py2 + εqy3 for p, q polynomials and ε ≪ 1. In particular, our result implies that for p satisfying a well-known generic condition, the number of periodic solutions near the zero solution does not exceed 5 + deg q + 3deg2 p. This is the first such bound depending solely on the degrees of the Abel equation.
The double galaxy cluster Abell 2465 - II. Star formation in the cluster
NASA Astrophysics Data System (ADS)
Wegner, Gary A.; Chu, Devin S.; Hwang, Ho Seong
2015-02-01
We investigate the star formation rate and its location in the major merger cluster Abell 2465 at z = 0.245. Optical properties of the cluster are described in Paper I. Measurements of the Hα and infrared dust emission of galaxies in the cluster were made with an interference filter centred on the redshifted line at a wavelength of 817 nm and utilized data from the Wide-field Infrared Survey Explorer satellite 12 μm band. Imaging in the Johnson U and B bands was obtained, and along with Sloan Digital Sky Survey u and r was used to study the blue fraction, which appears enhanced, as a further signature of star formation in the cluster. Star formation rates were calculated using standard calibrations. The total star formation rate normalized by the cluster mass, ΣSFR/Mcl compared to compilations for other clusters indicate that the components of Abell 2465 lie above the mean z and Mcl relations, suggestive that interacting galaxy clusters have enhanced star formation. The projected radial distribution of the star-forming galaxies does not follow an NFW profile and is relatively flat indicating that fewer star-forming galaxies are in the cluster centre. The morphologies of the Hα sources within R200 for the cluster as a whole indicate that many are disturbed or merging, suggesting that a combination of merging or harassment is working.
ERIC Educational Resources Information Center
Blasingame, Gerry D.; Abel, Gene G.; Jordan, Alan; Wiegel, Markus
2011-01-01
This article describes the development and utility of the Abel-Blasingame Assessment System for "individuals with intellectual disabilities" (ABID) for assessment of sexual interest and problematic sexual behaviors. The study examined the preliminary psychometric properties and evaluated the clinical utility of the ABID based on a sample of 495…
Spatio-kinematic modelling of Abell 65, a double-shelled planetary nebula with a binary central star
NASA Astrophysics Data System (ADS)
Huckvale, L.; Prouse, B.; Jones, D.; Lloyd, M.; Pollacco, D.; López, J. A.; O'Brien, T. J.; Sabin, L.; Vaytet, N. M. H.
2013-09-01
We present the first detailed spatio-kinematical analysis and modelling of the planetary nebula Abell 65, which is known to host a post-common envelope, binary, central star system. As such, this object is of great interest in studying the link between nebular morphology and central star binarity. [O III]5007 Å and Hα+[N II]6584 Å longslit spectra and imagery of Abell 65 were obtained with the Manchester Échelle Spectrometer on the 2.1-m telescope at the San Pedro Martír Observatory (MES-SPM). Further [O III]5007 Å longslit spectra were obtained with the Ultraviolet and Visual Échelle Spectrograph on the Very Large Telescope (VLT-UVES). These data were used to develop a spatio-kinematical model for the [O III]5007 Å emission from Abell 65. A `best-fitting' model was found by comparing synthetic spectra and images rendered from the model to the data. The model comprises an outer shell and an inner shell, with kinematical ages of 15000 ± 5000 yr kpc-1 and 8000 ± 3000 yr kpc-1, respectively. Both shells have peanut-shaped bipolar structures with symmetry axes at inclinations of (55 ± 10)° (to the line of sight) for the outer shell and (68 ± 10)° for the inner shell. The near alignment between the nebular shells and the binary orbital inclination [of (68 ± 2)°] is strongly indicative that the binary is responsible for shaping the nebula. Abell 65 is one of a growing number of planetary nebulae (seven to date, including Abell 65 itself) for which observations and modelling support the shaping influence of a central binary.
A Statistical Study of Multiply Imaged Systems in the Lensing Cluster Abell 68
NASA Astrophysics Data System (ADS)
Richard, Johan; Kneib, Jean-Paul; Jullo, Eric; Covone, Giovanni; Limousin, Marceau; Ellis, Richard; Stark, Daniel; Bundy, Kevin; Czoske, Oliver; Ebeling, Harald; Soucail, Geneviève
2007-06-01
We have carried out an extensive spectroscopic survey with the Keck and VLT telescopes, targeting lensed galaxies in the background of the massive cluster Abell 68. Spectroscopic measurements are obtained for 26 lensed images, including a distant galaxy at z=5.4. Redshifts have been determined for 5 out of 7 multiple-image systems. Through a careful modeling of the mass distribution in the strongly lensed regime, we derive a mass estimate of 5.3×1014 Msolar within 500 kpc. Our mass model is then used to constrain the redshift distribution of the remaining multiply imaged and singly imaged sources. This enables us to examine the physical properties for a subsample of 7 Lyα emitters at 1.7<~z<~5.5, whose unlensed luminosities of ~=1041 ergs s-1 are fainter than similar objects found in blank fields. Of particular interest is an extended Lyα emission region surrounding a highly magnified source at z=2.6, detected in VIMOS integral field spectroscopy data. The physical scale of the most distant lensed source at z=5.4 is very small (<300 pc), similar to the lensed z~5.6 emitter reported by Ellis et al. in Abell 2218. New photometric data available for Abell 2218 allow for a direct comparison between these two unique objects. Our survey illustrates the practicality of using lensing clusters to probe the faint end of the z~2-5 Lyα luminosity function in a manner that is complementary to blank-field narrowband surveys. Data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. Also based on observations collected at the Very Large Telescope (Antu/UT1 and Melipal/UT3), European Southern Observatory, Paranal, Chile (ESO programs 070.A-0643 and 073.A-0774), the NASA/ESA Hubble Space Telescope
Quasi MT Inversion of Short-Offset Transient Electromagnetic Data
NASA Astrophysics Data System (ADS)
Chen, Wei-ying; Xue, Guo-qiang; Khan, Muhammad Younis
2016-07-01
The short-offset transient electromagnetic method (SOTEM) has been extensively used for mineral and hydrocarbon exploration and hydrogeological investigations due to its ease of use and capability to generate diagnostic subsurface information. At present, the data processing methods of SOTEM are mainly focused on one dimensional inversion. To apply the proven inversion methods of frequency domain electromagnetic methods to SOTEM data, this paper presents a new transformation relation from time to frequency based on the similarity between SOTEM all-time apparent resistivity and magnetotelluric (MT) apparent resistivity. Results show that the transformation coefficients depend on the variation trend of SOTEM all-time apparent resistivity curves. Bostick inversion and conjugate gradient inversion techniques were applied to transformed SOTEM data and the results were validated by some simulated calculations and field measured data. This study provides a novel method to SOTEM data processing and a useful aid to join inversion with MT data.
Quasi MT Inversion of Short-Offset Transient Electromagnetic Data
NASA Astrophysics Data System (ADS)
Chen, Wei-ying; Xue, Guo-qiang; Khan, Muhammad Younis
2016-03-01
The short-offset transient electromagnetic method (SOTEM) has been extensively used for mineral and hydrocarbon exploration and hydrogeological investigations due to its ease of use and capability to generate diagnostic subsurface information. At present, the data processing methods of SOTEM are mainly focused on one dimensional inversion. To apply the proven inversion methods of frequency domain electromagnetic methods to SOTEM data, this paper presents a new transformation relation from time to frequency based on the similarity between SOTEM all-time apparent resistivity and magnetotelluric (MT) apparent resistivity. Results show that the transformation coefficients depend on the variation trend of SOTEM all-time apparent resistivity curves. Bostick inversion and conjugate gradient inversion techniques were applied to transformed SOTEM data and the results were validated by some simulated calculations and field measured data. This study provides a novel method to SOTEM data processing and a useful aid to join inversion with MT data.
Bédard, Catherine; Belin, Pascal
2004-07-01
Voice is the carrier of speech but is also an "auditory face" rich in information on the speaker's identity and affective state. Three experiments explored the possibility of a "voice inversion effect," by analogy to the classical "face inversion effect," which could support the hypothesis of a voice-specific module. Experiment 1 consisted of a gender identification task on two syllables pronounced by 90 speakers (boys, girls, men, and women). Experiment 2 consisted of a speaker discrimination task on pairs of syllables (8 men and 8 women). Experiment 3 consisted of an instrument discrimination task on pairs of melodies (8 string and 8 wind instruments). In all three experiments, stimuli were presented in 4 conditions: (1) no inversion; (2) temporal inversion (e.g., backwards speech); (3) frequency inversion centered around 4000 Hz; and (4) around 2500 Hz. Results indicated a significant decrease in performance caused by sound inversion, with a much stronger effect for frequency than for temporal inversion. Interestingly, although frequency inversion markedly affected timbre for both voices and instruments, subjects' performance was still above chance. However, performance at instrument discrimination was much higher than for voices, preventing comparison of inversion effects for voices vs. non-vocal stimuli. Additional experiments will be necessary to conclude on the existence of a possible "voice inversion effect." PMID:15177788
Dirac neutrino mass from a neutrino dark matter model for the galaxy cluster Abell 1689
NASA Astrophysics Data System (ADS)
Nieuwenhuizen, Theodorus Maria
2016-03-01
The dark matter in the galaxy cluster Abell 1689 is modelled as an isothermal sphere of neutrinos. New data on the 2d mass density allow an accurate description of its core and halo. The model has no “missing baryon problem” and beyond 2.1 Mpc the baryons have the cosmic mass abundance. Combination of cluster data with the cosmic dark matter fraction - here supposed to stem from the neutrinos - leads to a solution of the dark matter riddle by left and right handed neutrinos with mass (1.861 ± 0.016)h 70 -2eV/c 2. The thus far observed absence of neutrinoless double beta decay points to (quasi-) Dirac neutrinos: uncharged electrons with different flavour and mass eigenbasis, as for quarks. Though the cosmic microwave background spectrum is matched up to some 10% accuracy only, the case is not ruled out because the plasma phase of the early Universe may be turbulent.
NASA Technical Reports Server (NTRS)
Hoessel, J. G.; Gunn, J. E.; Thuan, T. X.
1980-01-01
Two-color aperture photometry of the brightest galaxies in a complete sample of nearby Abell clusters is presented. The results are used to anchor the bright end of the Hubble diagram; essentially the entire formal error for this method is then due to the sample of distant clusters used. New determinations of the systematic trend of galaxy absolute magnitude with the cluster properties of richness and Bautz-Morgan type are derived. When these new results are combined with the Gunn and Oke (1975) data on high-redshift clusters, a formal value (without accounting for any evolution) of q sub 0 = -0.55 + or - 0.45 (1 standard deviations) is found.
An Approximation to the Periodic Solution of a Differential Equation of Abel
NASA Astrophysics Data System (ADS)
Mickens, Ronald E.
2011-10-01
The Abel equation, in canonical form, is y^' = sint- y^3 (*) and corresponds to the singular (ɛ --> 0) limit of the nonlinear, forced oscillator ɛy^'' + y^' + y^3 = sint, ɛ-> 0. (**) Equation (*) has the property that it has a unique periodic solution defined on (-∞,∞). Further, as t increases, all solutions are attracted into the strip |y| < 1 and any two different solutions y1(t) and y2(t) satisfy the condition Lim [y1(t) - y2(t)] = 0, (***) t --> ∞ and for t negatively decreasing, each solution, except for the periodic solution, becomes unbounded.ootnotetextU. Elias, American Mathematical Monthly, vol.115, (Feb. 2008), pps. 147-149. Our purpose is to calculate an approximation to the unique periodic solution of Eq. (*) using the method of harmonic balance. We also determine an estimation for the blow-up time of the non-periodic solutions.
New bibenzyl glycosides from leaves of Camellia oleifera Abel. with cytotoxic activities.
Chen, Yuelong; Tang, Ling; Feng, Baomin; Shi, Liying; Wang, Huiguo; Wang, Yongqi
2011-04-01
Studies on the chemical constituents of leaves of Camellia oleifera Abel. led to the isolation of 3 new bibenzyl glycosides. Their structures have been elucidated as 1-(3',5'-dihydroxy)phenyl-2-(4″-O-β-D-glucopyranosyl)phenylethane (1), 1-(3',5'-dimethoxy)phenyl-2-(4″-O-β-D-glucopyranosyl)phenylethane (2) and 1-(3',5'-dimethoxy)phenyl-2-[4″-O-β-D-glucopyranosyl(6→1)-O-α-L-rhamnopyranosyl]phenylethane (3) through spectral studies including HR-ESI-MS, ((1))H NMR, ((13))C NMR and 2D NMR experiments. All the above 3 bibenzyl glycosides showed cytotoxic activities to Hela and hep2 cell lines. PMID:21219989
X-ray constraints on the shape of the dark matter in five Abell clusters
NASA Technical Reports Server (NTRS)
Buote, David A.; Canizares, Claude R.
1992-01-01
X-ray observations obtained with the Einstein Observatory are used to constrain the shape of the dark matter in the inner regions of Abell clusters A401, A426, A1656, A2029, and A2199, each of which exhibits highly flattened optical isopleths. The dark matter is modeled as an ellipsoid with a mass density of about r exp -2. The possible shapes of the dark matter is constrained by comparing these model isophotes to the image isophotes. The X-ray isophotes, and therefore the gravitational potentials, have ellipticities of about 0.1-0.2. The dark matter within the central 1 Mpc is found to be substantially rounder for all the clusters. It is concluded that the shape of the galaxy distributions in these clusters traces neither the gravitational potential nor the gravitating matter.
Temperature and elemental abundances in the Abell cluster A576 derived from X-ray observations
NASA Technical Reports Server (NTRS)
Rothenflug, R.; Vigroux, L.; Mushotzky, R. F.; Holt, S. S.
1984-01-01
Results of the Einstein Solid State Spectrometer (SSS) observations of the central region of Abell 576 combined with HEAO 1 spectra of the total cluster are reported. Line emission due to Fe, Si, and S from a hot plasma in the central region of the object are detected. Abundances roughly one-half of the solar value are derived for these elements. The total cluster spectrum is well fitted by a thermal bremsstrahlung model with a temperature of 4 +3.5 or -1.4 x 10 to the 7th K. This temperature is in conflict with the SSS temperature determination for the center of the cluster. This difference can be explained if cooling takes place in the central part of the cluster, or if the X-ray emission in the center is dominated by the emission of a single galaxy.
A Chandra Study of the Large-Scale Shock Front in Abell 2219
NASA Astrophysics Data System (ADS)
Allen, Steven
2011-09-01
Abell 2219 (z=0.225) is the third galaxy cluster in which a clear, large-scale shock front, viewed approximately edge-on and generated by ongoing merging activity, has been discovered. It is highly X-ray luminous and 2.5 times brighter in X-rays than either 1E0657-56 or A520. We propose a 150ks ACIS-I observation to obtain the first precise measurements of the pre- and post-shock gas temperature, enabling improved estimates of the Mach number and shock velocity. The observed gradient of the temperature jump across the shock will constrain the process of post-shock electron-ion equilibration. We will probe the origin of very hot (kT>20 keV) gas observed in the cluster center. High quality radio, optical-dynamical, and ground- and space-based gravitational lensing data are in hand.
Cheng, Yu-Ting; Lu, Chi-Cheng; Yen, Gow-Chin
2015-01-01
Epidemiological studies have shown that increased dietary intake of natural antioxidants is beneficial for health because of their bioactivities, including antioxidant and anti-inflammation actions. Camellia oil made from tea seed (Camellia oleifera Abel.) is commonly used as an edible oil and a traditional medicine in Taiwan and China. Until now, the camellia oil has been widely considered as a dietary oil for heath. In this review, we summarize the protective effects of camellia oil with antioxidant activity against oxidative stress leading to hepatic damage and gastrointestinal ulcers. The information in this review leads to the conclusion that camellia oil is not only an edible oil but also a vegetable oil with a potential function for human health. PMID:26598814
Sloshing, Shocks, and Bubbles in the Cool Core Cluster Abell 2052
NASA Astrophysics Data System (ADS)
Blanton, Elizabeth L.; Randall, S. W.; Clarke, T. E.; Sarazin, C. L.; McNamara, B. R.; Douglass, E. M.; McDonald, M.
2011-05-01
We present results from a very deep (650 ksec) Chandra X-ray observation of Abell 2052, as well as archival VLA radio observations. The data reveal exquisite detail in the inner parts of the cluster, including bubbles evacuated by the AGN's radio lobes, compressed bubble rims, filaments, and loops. Two concentric shocks are seen, and a temperature rise is measured for the innermost one. On larger scales, an excess surface brightness spiral feature is detected. The spiral has cooler temperatures and higher abundances than its surroundings, and is likely the result of sloshing gas initiated by a previous cluster-cluster or sub-cluster merger. Initial evidence for previously unseen bubbles at larger radii related to earlier outbursts from the AGN is presented. Support for this work was provided by the National Aeronautics and Space Administration, through Chandra Award Number GO9-0147X.
Narrow-angle tail radio sources and evidence for radial orbits in Abell clusters
NASA Technical Reports Server (NTRS)
O'Dea, Christopher P.; Owen, Frazer N.; Sarazin, Craig L.
1986-01-01
Published observational data on the tail orientations (TOs) of 60 narrow-angle-tail (NAT) radio sources in Abell clusters of galaxies are analyzed statistically using a maximum-likelihood approach. The results are presented in a table, and it is found that the observed TO distributions in the whole sample and in subsamples of morphologically regular NATs and NATs with pericentric distances d greater than 500 kpc are consistent with isotropic orbits, whereas the TOs for NATs with d less than 500 kpc are consistent with highly radial orbits. If radial orbits were observed near the centers of other types of cluster galaxies as well, it could be inferred that violent relaxation during cluster formation was incomplete, and that clusters form by spherical collapse and secondary infall, as proposed by Gunn (1977).
The Mass of Abell 1060 and AWM 7 from Spatially Resolved X-Ray Spectroscopy
NASA Astrophysics Data System (ADS)
Loewenstein, M.; Mushotzky, R. F.
1996-11-01
Using X-ray temperature and surface brightness profiles of the hot intracluster medium (ICM) derived from ASCA (Astro-D) and ROSAT observations, we place constraints on the dark matter (DM) and baryon fraction distributions in the poor clusters Abell 1060 (A1060) and AWM 7. Although their total mass distributions are similar, AWM 7 has twice the baryon fraction of A1060 in the best-fit models. The functional form of the DM distribution is ill determined; however, mass models where the baryon fractions in A1060 and AWM 7 significantly overlap are excluded. Such variations in baryon fraction are not predicted by standard models and imply that some mechanism in addition to gravity plays a major role in organizing matter on cluster scales.
Television documentary, history and memory. An analysis of Sergio Zavoli's The Gardens of Abel
Foot, John
2014-01-01
This article examines a celebrated documentary made for Italian state TV in 1968 and transmitted in 1969 to an audience of millions. The programme – The Gardens of Abel – looked at changes introduced by the radical psychiatrist Franco Basaglia in an asylum in the north-east of Italy (Gorizia). The article examines the content of this programme for the first time, questions some of the claims that have been made for it, and outlines the sources used by the director, Sergio Zavoli. The article argues that the film was as much an expression of Zavoli's vision and ideas as it was linked to those of Franco Basaglia himself. Finally, the article highlights the way that this programme has become part of historical discourse and popular memory. PMID:25937804
Search for a non-equilibrium plasma in the merging galaxy cluster Abell 754
NASA Astrophysics Data System (ADS)
Inoue, Shota; Hayashida, Kiyoshi; Ueda, Shutaro; Nagino, Ryo; Tsunemi, Hiroshi; Koyama, Katsuji
2016-06-01
Abell 754 is a galaxy cluster in which an ongoing merger is evident on the plane of the sky, from the southeast to the northwest. We study the spatial variation of the X-ray spectra observed with Suzaku along the merging direction, centering on the Fe Ly α/Fe He α line ratio to search for possible deviation from ionization equilibrium. Fitting with a single-temperature collisional non-equilibrium plasma model shows that the electron temperature increases from the southeast to the northwest. The ionization parameter is consistent with that in equilibrium (net > 1013 s cm-3) except for the specific region with the highest temperature (kT=13.3_{-1.1}^{+1.4}keV) where n_et=10^{11.6_{-1.7}^{+0.6}}s cm-3. The elapsed time from the plasma heating estimated from the ionization parameter is 0.36-76 Myr at the 90% confidence level. This timescale is quite short but consistent with the traveling time of a shock to pass through that region. We thus interpret that the non-equilibrium ionization plasma in Abell 754 observed is a remnant of the shock heating in the merger process. However, we note that the X-ray spectrum of the specific region where the non-equilibrium is found can also be fitted with a collisional ionization plasma model with two temperatures, low kT=4.2^{+4.2}_{-1.5}keV and very high kT >19.3 keV. The very high temperature component is alternatively fitted with a power-law model. Either of these spectral models is interpreted as a consequence of the ongoing merger process as in the case of the non-equilibrium ionization plasma.
The galaxy population of Abell 1367: the stellar mass-metallicity relation
NASA Astrophysics Data System (ADS)
Mouhcine, M.; Kriwattanawong, W.; James, P. A.
2011-04-01
Using wide baseline broad-band photometry, we analyse the stellar population properties of a sample of 72 galaxies, spanning a wide range of stellar masses and morphological types, in the nearby spiral-rich and dynamically young galaxy cluster Abell 1367. The sample galaxies are distributed from the cluster centre out to approximately half the cluster Abell radius. The optical/near-infrared colours are compared with simple stellar population synthesis models from which the luminosity-weighted stellar population ages and metallicities are determined. The locus of the colours of elliptical galaxies traces a sequence of varying metallicity at a narrow range of luminosity-weighted stellar ages. Lenticular galaxies in the red sequence, however, exhibit a substantial spread of luminosity-weighted stellar metallicities and ages. For red-sequence lenticular galaxies and blue cloud galaxies, low-mass galaxies tend to be on average dominated by stellar populations of younger luminosity-weighted ages. Sample galaxies exhibit a strong correlation between integrated stellar mass and luminosity-weighted stellar metallicity. Galaxies with signs of morphological disturbance and ongoing star formation activity, tend to be underabundant with respect to passive galaxies in the red sequence of comparable stellar masses. We argue that this could be due to tidally driven gas flows towards the star-forming regions, carrying less enriched gas and diluting the pre-existing gas to produce younger stellar populations with lower metallicities than would be obtained prior to the interaction. Finally, we find no statistically significant evidence for changes in the luminosity-weighted ages and metallicities for either red-sequence or blue-cloud galaxies, at fixed stellar mass, with location within the cluster. We dedicate this work to the memory of our friend and colleague C. Moss who died suddenly recently.
Revisiting Abell 2744: a powerful synergy of the GLASS spectroscopy and the HFF photometry.
NASA Astrophysics Data System (ADS)
Wang, Xin; Borello Schmidt, Kasper; Treu, Tommaso
2015-08-01
We present new emission line identifications and improve the strong lensing reconstruction of the massive cluster Abell 2744 using the Grism Lens-Amplified Survey from Space (GLASS) observations and the full depth of the Hubble Frontier Fields (HFF) imaging. We performed a blind and targeted search for emission lines in objects within the full field of view (FoV) of the GLASS prime pointings, including all the previously known multiple arc images. We report over 50 high quality spectroscopic redshifts, 4 of which are for the arc images. We also present an extensive analysis based on the HFF photometry, measuring the colors and photometric redshifts of all objects within the FoV, and comparing the spectroscopic and photometric results of the same ensemble of sources. In order to improve the lens model of Abell 2744, we develop a rigorous alogorithm to screen arc images, based on their colors and morphology, and selecting the most reliable ones to use. As a result, 21 systems (corresponding to 59 images) pass the screening process and are used to reconstruct the gravitational potential of the cluster pixellated on an adaptive mesh. The resulting total mass distribution is compared with a stellar mass map obtained from the deep Spitzer Frontier Fields data in a fashion very similar to the reduction of the Spitzer UltRa Faint SUrvey Program (SURFS UP) clusters, in order to study the relative distribution of stars and dark matter in the cluster. The maps of convergence, shear, and magnification are made publicly available in the standard HFF format.
Deep spectroscopy of nearby galaxy clusters - I. Spectroscopic luminosity function of Abell 85
NASA Astrophysics Data System (ADS)
Agulli, I.; Aguerri, J. A. L.; Sánchez-Janssen, R.; Dalla Vecchia, C.; Diaferio, A.; Barrena, R.; Dominguez Palmero, L.; Yu, H.
2016-05-01
We present a new deep spectroscopic catalogue for Abell 85, within 3.0 × 2.6 Mpc2 and down to Mr ˜ Mr^{ast } +6. Using the Visible Multi-Object Spectrograph at the Very Large Telescope and the AutoFiber 2 at the William Herschel Telescope, we obtained almost 1430 new redshifts for galaxies with mr ≤ 21 mag and <μe,r> ≤ 24 mag arcsec-2. These redshifts, together with Sloan Digital Sky Survey Data Release 6 and NASA/IPAC Extragaalctic Database spectroscopic information, result in 460 confirmed cluster members. This data set allows the study of the luminosity function (LF) of the cluster galaxies covering three orders of magnitudes in luminosities. The total and radial LFs are best modelled by a double Schechter function. The normalized LFs show that their bright (Mr ≤ -21.5) and faint (Mr ≥ -18.0) ends are independent of clustercentric distance and similar to the field LFs unlike the intermediate luminosity range (-21.5 ≤ Mr ≤ -18.0). Similar results are found for the LFs of the dominant types of galaxies: red, passive, virialized and early-infall members. On the contrary, the LFs of blue, star forming, non-virialized and recent-infall galaxies are well described by a single Schechter function. These populations contribute to a small fraction of the galaxy density in the innermost cluster region. However, in the outskirts of the cluster, they have similar densities to red, passive, virialized and early-infall members at the LF faint end. These results confirm a clear dependence of the colour and star formation of Abell 85 members in the cluster centric distance.
Suzaku observation of a high-entropy cluster Abell 548W
NASA Astrophysics Data System (ADS)
Nakazawa, Kazuhiro; Kato, Yuichi; Gu, Liyi; Kawaharada, Madoka; Takizawa, Motokazu; Fujita, Yutaka; Makishima, Kazuo
2016-06-01
Abell 548W, one of the galaxy clusters located in the Abell 548 region, has about an order of magnitude lower X-ray luminosity compared to ordinal clusters in view of the well-known intracluster medium (ICM) temperature vs. X-ray luminosity (kT-LX) relation. The cluster hosts a pair of diffuse radio sources to the northwest and north, both about 10' apart from the cluster center. They are candidate radio relics, frequently associated with merging clusters. A Suzaku deep observation with exposure of 84.4 ks was performed to search for signatures of merging in this cluster. The XIS detectors successfully detected the ICM emission out to 16' from the cluster center. The temperature is ˜ 3.6 keV around its center, and ˜ 2 keV at the outermost regions. The hot region (˜ 6 keV) beside the relic candidates shifted to the cluster center reported by XMM-Newton was not seen in the Suzaku data, although its temperature of 3.6 keV itself is higher than the average temperature of 2.5 keV around the radio sources. In addition, the signature of a cool (kT ˜ 0.9 keV) component was found around the northwest source. A marginal temperature jump at its outer edge was also found, consistent with the canonical idea of the shock acceleration origin of the radio relics. The cluster has among the highest central entropy of ˜ 400 keV cm2 and is one of the so-called low surface brightness clusters. Taking into account the fact that its shape itself is relatively circular and smooth and also that its temperature structure is nearly flat, possible scenarios for merging are discussed.
Discovery of an overlapping cluster in the Abell 1674 field with Suzaku
NASA Astrophysics Data System (ADS)
Inoue, Shota; Hayashida, Kiyoshi; Akamatsu, Hiroki; Ueda, Shutaro; Nagino, Ryo; Tsunemi, Hiroshi; Tawa, Noriaki; Koyama, Katsuji
2014-07-01
We present the results of a Suzaku observation of Abell 1674, an optically very rich (richness class 3) cluster cataloged as z = 0.1066. We discover the He-like Fe K-shell line from the central region for the first time, and find that the X-ray spectrum yields a high redshift of 0.215^{+0.007}_{-0.006}. On the other hand, the spectrum of the south-western region is fitted with a redshift of 0.11 ± 0.02 by the He-like Fe L-shell lines, consistent with the optically determined value. The gas temperature, metal abundance, and core radius of the X-ray emission in the central region are 3.8 ± 0.2 keV, 0.20 ± 0.05 Z⊙, and 450 ± 40 kpc, respectively, while those in the south-western region are 2.0 ± 0.2 keV, 0.41^{+0.17}_{-0.13} Z⊙, and 220^{+90}_{-70} kpc, respectively. These parameters are typical for clusters. We thus conclude that Abell 1674 consists of two independent clusters, A 1674-C at z ˜ 0.22 and A 1674-SW at z ˜ 0.11, overlapping along the line of sight. The X-ray luminosity of A 1674-C within r = 2 Mpc is (15.9 ± 0.6) × 1043 erg s-1 in the 0.1-2.4 keV energy band, while that for A 1674-SW is (1.25 ± 0.07) × 1043 erg s-1. Both are consistent with those expected from the L-T relation of clusters within a factor of 2. This is another supporting factor for our conclusion.