WorldWideScience

Sample records for fine structural features

  1. Development of solar flares and features of the fine structure of solar radio emission

    Science.gov (United States)

    Chernov, G. P.; Fomichev, V. V.; Yan, Y.; Tan, B.; Tan, Ch.; Fu, Q.

    2017-11-01

    The reason for the occurrence of different elements of the fine structure of solar radio bursts in the decimeter and centimeter wavelength ranges has been determined based on all available data from terrestrial and satellite observations. In some phenomena, fast pulsations, a zebra structre, fiber bursts, and spikes have been observed almost simultaneously. Two phenomena have been selected to show that the pulsations of radio emission are caused by particles accelerated in the magnetic reconnection region and that the zebra structure is excited in a source, such as a magnetic trap for fast particles. The complex combination of unusual fiber bursts, zebra structure, and spikes in the phenomenon on December 1, 2004, is associated with a single source, a magnetic island formed after a coronal mass ejection.

  2. The Fine Structure Constant

    Indian Academy of Sciences (India)

    IAS Admin

    The article discusses the importance of the fine structure constant in quantum mechanics, along with the brief history of how it emerged. Al- though Sommerfelds idea of elliptical orbits has been replaced by wave mechanics, the fine struc- ture constant he introduced has remained as an important parameter in the field of ...

  3. Electronic structure and fine structural features of the air-grown UNxOy on nitrogen-rich uranium nitride

    Science.gov (United States)

    Long, Zhong; Zeng, Rongguang; Hu, Yin; Liu, Jing; Wang, Wenyuan; Zhao, Yawen; Luo, Zhipeng; Bai, Bin; Wang, Xiaofang; Liu, Kezhao

    2018-06-01

    Oxide formation on surface of nitrogen-rich uranium nitride film/particles was investigated using X-ray photoelectron spectroscopy (XPS), auger electron spectroscopy (AES), aberration-corrected transmission electron microscopy (TEM), and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) coupled with electron energy-loss spectroscopy (EELS). XPS and AES studies indicated that the oxidized layer on UN2-x film is ternary compound uranium oxynitride (UNxOy) in 5-10 nm thickness. TEM/HAADF-STEM and EELS studies revealed the UNxOy crystallizes in the FCC CaF2-type structure with the lattice parameter close to the CaF2-type UN2-x matrix. The work can provide further information to the oxidation mechanism of uranium nitride.

  4. Berry's Phase and Fine Structure

    CERN Document Server

    Binder, B

    2002-01-01

    Irrational numbers can be assigned to physical entities based on iterative processes of geometric objects. It is likely that iterative round trips of vector signals include a geometric phase component. If so, this component will couple back to the round trip frequency or path length generating an non-linear feedback loop (i.e. induced by precession). In this paper such a quantum feedback mechanism is defined including generalized fine structure constants in accordance with the fundamental gravitomagnetic relation of spin-orbit coupling. Supported by measurements, the general relativistic and topological background allows to propose, that the deviation of the fine structure constant from 1/137 could be assigned to Berry's phase. The interpretation is straightforward: spacetime curvature effects can be greatly amplified by non-linear phase-locked feedback-loops adjusted to single-valued phase relationships in the quantum regime.

  5. Fine Structure of Plasmaspheric Hiss

    Science.gov (United States)

    Summers, D.; Omura, Y.; Nakamura, S.; Kletzing, C.

    2014-12-01

    Plasmaspheric hiss plays a key role in controlling the structure and dynamics of Earth's radiation belts.The quiet time slot region between the inner and outer belts can be explained as a steady-state balance between earthward radial diffusion and pitch-angle scattering loss of energetic electrons to the atmosphere induced by plasmaspheric hiss. Plasmaspheric hiss can also induce gradual precipitation loss of MeV electrons from the outer radiation belt. Plasmaspheric hiss has been widely regarded as a broadband,structureless,incoherent emission. Here, by examining burst-mode vector waveform data from the EMFISIS instrument on the Van Allen Probes mission,we show that plasmaspheric hiss is a coherent emission with complex fine structure. Specifically, plasmaspheric hiss appears as discrete rising tone and falling tone elements. By means of waveform analysis we identify typical amplitudes,phase profiles,and sweep rates of the rising and falling tone elements. The new observations reported here can be expected to fuel a re-examination of the properties of plasmaspheric hiss, including a further re-analysis of the generation mechanism for hiss.

  6. A study of human DPOAE fine structure

    DEFF Research Database (Denmark)

    Reuter, Karen; Hammershøi, Dorte

    height and ripple prevalence. Temporary changes of the DPOAE fine structure are analyzed by measuring DPOAE both before and after exposing some of the subjects to an intense sound. The characteristic patterns of fine structure can be found in the DPOAE of all subjects, though they are individual and vary...... fine structures are obtained from 74 normalhearing humans using primary levels of L1/L2=65/45 dB. The subjects belong to groups with different age and exposure history. A classification algorithm is developed, which quantifies the fine structure by the parameters ripple place, ripple width, ripple...

  7. Fine structure of cluster decays

    International Nuclear Information System (INIS)

    Dumitrescu, O.

    1993-07-01

    Within the one level R-matrix approach the hindrance factors of the radioactive decays in which are emitted α and 14 C - nuclei are calculated. The generalization to radioactive decays in which are emitted heavier clusters such as e.g. 20 O, 24 Ne, 25 Ne, 28 Mg. 30 Mg, 32 Si and 34 Si is straightforward. The interior wave functions are supposed to be given by the shell model with effective residual interactions (e.g. the large scale shell model code-OXBASH - in the Michigan State University version for nearly spherical nuclei or by the enlarged superfluid model - ESM - recently proposed for deformed nuclei). The exterior wave functions are calculated from a cluster - nucleus double - folding model potential obtained with the M3Y interaction. As examples of the cluster decay fine structure we analyzed the particular cases of α - decay of 241 Am and 14 C -decay of 233 Ra. Good agreement with the experimental data is obtained. (author). 78 refs, 2 figs, 6 tabs

  8. Fine structure studies of terbium atoms

    International Nuclear Information System (INIS)

    Abhay Kumar; Bandyopadhyay, Krishnanath; Niraj Kumar

    2012-01-01

    Terbium (Z = 65) is a typical rare-earth element. Fine structure of spectural lines of terbium (Tb) are presented using the laser optogalvanic spectroscopic technique. Altogether eighty transitions in the 5686-6367 A range have been observed in the fine structure spectrum of 159 Tb. Wavelengths of all the observed transitions have been determined. Out of 80 transitions of Tb, a total of 59 transitions are being reported for the first time. Classifications of 39 new transitions have been provided using the known energy levels, Doppler-limited optogalvanic spectroscopic technique is employed to study the fine structure (fs) 159 Tb. (author)

  9. Looking inside giant resonance fine structure

    International Nuclear Information System (INIS)

    Ponomarev, V.Yu.; Voronov, V.V.

    1993-01-01

    Microscopic calculations of the fine structure of giant resonances for spherical nuclei are presented. Excited states are treated by wave function which takes into account coupling of simple one-phonon configurations with more complex ones. Nuclear structure calculations are applied to the description of the γ-decay of resonances into the ground and low-lying excited states. 16 refs.; 4 figs

  10. Edge separation using diffraction anomalous fine structure

    International Nuclear Information System (INIS)

    Ravel, B.; Bouldin, C.E.; Renevier, H.; Hodeau, J.L.; Berar, J.F.

    1999-01-01

    We exploit the crystallographic sensitivity of the Diffraction Anomalous Fine-Structure (DAFS) measurement to separate the fine structure contributions of different atomic species with closely spaced resonant energies. In BaTiO 3 the Ti K edge and Ba Lm edges are separated by 281 eV, or about 8.2 Angstrom -1 ), thus severely limiting the information content of the Ti K edge signal. Using the site selectivity of DAFS we can separate the two fine structure spectra using an iterative Kramers-Kronig method, thus extending the range of the Ti K edge spectrum. This technique has application to many rare earth/transition metal compounds, including many magnetic materials of technological significance for which K and L edges overlap in energy. (au)

  11. Study of fine structure of deformed hafnium

    International Nuclear Information System (INIS)

    Voskresenskaya, L.A.; Petukhova, A.S.; Kovalev, K.S.

    1978-01-01

    Variations in the hafnium fine structure following the cold plastic deformation have been studied. The fine structure condition has been studied through the harmonic analysis of the profile of the X-ray diffraction line, obtained at the DRON-I installation. Received has been the dependence of the crystal lattice microdistortions value on the deformation extent for hafnium. This dependence is compared with the corresponding one for zirconium. It is found out that at all the deformations the microdistortion distribution is uniform. The microdistortion value grows with the increase in the compression. During the mechanical impact higher microdistortions of the crystal lattice occur in the hafnium rather than in zirconium

  12. Renal fine structures detected by NMR imaging

    International Nuclear Information System (INIS)

    Zilch, H.G.

    1986-01-01

    A significantly improved image quality is achieved by the technique described, as compared to the magnetic resonance data obtained so far. The detailed analysis of the kidney goes as deep as into anatomic fine structures, and there is reason to hope for far better diagnostic details. (orig.) [de

  13. Derivation of the fine-structure constant

    International Nuclear Information System (INIS)

    Samec, A.

    1980-01-01

    The fine-structure constant is derived as a dynamical property of quantum electrodynamics. Single-particle solutions of the coupled Maxwell and Dirac equations have a physical charge spectrum. The solutions are used to construct lepton-and quark-like particles. The strong, weak, electromagnetic, and gravitational forces are described as the interactions of complex charges in multiple combinations

  14. Fine Structure of 211 Po Alpha Decay

    International Nuclear Information System (INIS)

    Mirea, M.

    2000-01-01

    Recently, a theory based on the Landau-Zener effect was developed intending to describe quantitatively the cluster decay fine structure phenomenon. It was claimed that the same promotion effect can also govern the fine structure in the case of α-decay. This formalism intends to explain the fine structure of α-decay by considering single-particle transitions due to the radial and the rotational couplings. The levels with the same good quantum numbers associated to some symmetries of the system cannot in general intersect, but exhibit quasi-crossings, or pseudo-crossings, or avoided level crossings. The system is characterised by an axial symmetry, therefore the good quantum numbers are the projections of the nucleon spin Ω. The radial coupling causes transitions of the unpaired nucleon near the avoided level crossings. True crossings can also be obtained between levels characterized by different quantum numbers. Generally, the rotational coupling has a maximum strength in the vicinity of the true crossings. Transitions due to both couplings are taken into account in order to explain the excitations of the unpaired nucleon. For a tunnelling velocity of 9 x 10 6 fm/fs, the ratio between the intensity for transitions to the first excited state and to the ground state was found to be 0.0071 and the obtained ratio of the same parameter between the second excited state and the ground state was 0.0062, in good agreement with experimental data. These calculations suggest that the α-decay fine structure phenomenon can be explained quantitatively by describing the decaying system with molecular models and it can be stated that the quantitative characteristics of this phenomenon are ruled by dynamical effects. (author)

  15. Fine structure and analytical quantum-defect wave functions

    International Nuclear Information System (INIS)

    Kostelecky, V.A.; Nieto, M.M.; Truax, D.R.

    1988-01-01

    We investigate the domain of validity of previously proposed analytical wave functions for atomic quantum-defect theory. This is done by considering the fine-structure splitting of alkali-metal and singly ionized alkaline-earth atoms. The Lande formula is found to be naturally incorporated. A supersymmetric-type integer is necessary for finite results. Calculated splittings correctly reproduce the principal features of experimental values for alkali-like atoms

  16. Fine structure transitions in Fe XIV

    Science.gov (United States)

    Nahar, Sultana N.

    2013-07-01

    Results are reported for Fe XIV energy levels and transitions obtained from the ab initio relativistic Breit-Pauli R-matrix (BPRM) method. BPRM method developed under the Iron Project is capable of calculating very large number of fine structure energy levels and corresponding transitions. However, unlike in the atomic structure calculations, where levels are identified spectroscopically based on the leading percentage contributions of configurations, BPRM is incapable of such identification of the levels and hence the transitions. The main reason for it is that the percentage contributions can not be determined exactly from the large number of channels in the R-matrix space. The present report describes an identification method that uses considerations of quantum defects of channels, contributions of channel from outer regions, Hund's rule, and angular momenta algebra for addition and completeness of fine structure components. The present calculations are carried out using a close coupling wave function expansion that included 26 core excitations from configurations 2s22p63s2, 2s22p63s3p,2s22p63p2,2s22p63s3d, and 2s22p63p3d. A total of 1002 fine structure levels with n ⩽ 10, l⩽9, and 0.5 ⩽J⩽ 9.5 with even and odd parities and the corresponding 130,520 electric dipole allowed (E1) fine structure transitions, a most complete set for astrophysical modelings of spectral analysis and opacities, is presented. Large number of new energy levels are found and identified. The energies agree very well, mostly in less than 1% with the highest being 1.9%, with the 68 observed fine structure levels. While the high lying levels may have some uncertainty, an overall accuracy of energy levels should be within 10%. BPRM transitions have been benchmarked with the existing most accurate calculated transition probabilities with very good agreement for most cases. Based on the accuracy of the method and comparisons, most of the transitions can be rated with A (⩽10%) to C (

  17. Recovering the fine structures in solar images

    Science.gov (United States)

    Karovska, Margarita; Habbal, S. R.; Golub, L.; Deluca, E.; Hudson, Hugh S.

    1994-01-01

    Several examples of the capability of the blind iterative deconvolution (BID) technique to recover the real point spread function, when limited a priori information is available about its characteristics. To demonstrate the potential of image post-processing for probing the fine scale and temporal variability of the solar atmosphere, the BID technique is applied to different samples of solar observations from space. The BID technique was originally proposed for correction of the effects of atmospheric turbulence on optical images. The processed images provide a detailed view of the spatial structure of the solar atmosphere at different heights in regions with different large-scale magnetic field structures.

  18. Fine structure of 25 extragalactic radio sources

    International Nuclear Information System (INIS)

    Wittels, J.J.; Knight, C.A.; Shapiro, I.I.; Hinteregger, H.F.; Rogers, A.E.E.; Whitney, A.R.; Clark, T.A.; Hutton, L.K.; Marandino, G.E.; Neill, A.E.; Ronnang, B.G.; Rydbeck, O.E.H.; Klemperer, W.K.; Warnock, W.W.

    1975-01-01

    Between 1972 April and 1973 May, 25 extragalactic radio sources were observed interferometrically at 7.8 GHz(lambdaapprox. =3.8 cm) with five pairings of antennas. These sources exhibit a broad variety of fine structures from very simple to complex. Although the structure and the total power of some of these sources have remained unchanged within the sensitivity of our measurements during the year of observations, both the total flux and the correlated flux of others have undergone large changes in a few weeks

  19. Fine structure of synapses on dendritic spines

    Directory of Open Access Journals (Sweden)

    Michael eFrotscher

    2014-09-01

    Full Text Available Camillo Golgi’s Reazione Nera led to the discovery of dendritic spines, small appendages originating from dendritic shafts. With the advent of electron microscopy (EM they were identified as sites of synaptic contact. Later it was found that changes in synaptic strength were associated with changes in the shape of dendritic spines. While live-cell imaging was advantageous in monitoring the time course of such changes in spine structure, EM is still the best method for the simultaneous visualization of all cellular components, including actual synaptic contacts, at high resolution. Immunogold labeling for EM reveals the precise localization of molecules in relation to synaptic structures. Previous EM studies of spines and synapses were performed in tissue subjected to aldehyde fixation and dehydration in ethanol, which is associated with protein denaturation and tissue shrinkage. It has remained an issue to what extent fine structural details are preserved when subjecting the tissue to these procedures. In the present review, we report recent studies on the fine structure of spines and synapses using high-pressure freezing (HPF, which avoids protein denaturation by aldehydes and results in an excellent preservation of ultrastructural detail. In these studies, HPF was used to monitor subtle fine-structural changes in spine shape associated with chemically induced long-term potentiation (cLTP at identified hippocampal mossy fiber synapses. Changes in spine shape result from reorganization of the actin cytoskeleton. We report that cLTP was associated with decreased immunogold labeling for phosphorylated cofilin (p-cofilin, an actin-depolymerizing protein. Phosphorylation of cofilin renders it unable to depolymerize F-actin, which stabilizes the actin cytoskeleton. Decreased levels of p-cofilin, in turn, suggest increased actin turnover, possibly underlying the changes in spine shape associated with cLTP. The findings reviewed here establish HPF as

  20. Relativistic corrections to fine structure of positronium

    International Nuclear Information System (INIS)

    Martynenko, A.P.; Faustov, R.N.

    1997-01-01

    On the basis of the quasipotential method, we have calculated the relativistic corrections in the positronium fine structure intervals 2 3 S 1 -2 3 P J . The contributions of order of mα 6 for the positronium S-levels were obtained from the one-photon, two-photon interactions and the second-order perturbation theory. We have obtained also the contribution of the two-photon annihilation diagrams to the interaction operator of the P-wave positronium. The corrections of order of α 5 R ∞ and α 5 1nαR ∞ to the P-wave energy levels of positronium were calculated

  1. Fine structure in deformed proton emitting nuclei

    International Nuclear Information System (INIS)

    Sonzogni, A. A.; Davids, C. N.; Woods, P. J.; Seweryniak, D.; Carpenter, M. P.; Ressler, J. J.; Schwartz, J.; Uusitalo, J.; Walters, W. B.

    1999-01-01

    In a recent experiment to study the proton radioactivity of the highly deformed 131 Eu nucleus, two proton lines were detected. The higher energy one was assigned to the ground-state to ground-state decay, while the lower energy, to the ground-state to the 2 + state decay. This constitutes the first observation of fine structure in proton radioactivity. With these four measured quantities, proton energies, half-life and branching ratio, it is possible to determine the Nilsson configuration of the ground state of the proton emitting nucleus as well as the 2 + energy and nuclear deformation of the daughter nucleus. These results will be presented and discussed

  2. Molecular Eigensolution Symmetry Analysis and Fine Structure

    Directory of Open Access Journals (Sweden)

    William G. Harter

    2013-01-01

    Full Text Available Spectra of high-symmetry molecules contain fine and superfine level cluster structure related to J-tunneling between hills and valleys on rovibronic energy surfaces (RES. Such graphic visualizations help disentangle multi-level dynamics, selection rules, and state mixing effects including widespread violation of nuclear spin symmetry species. A review of RES analysis compares it to that of potential energy surfaces (PES used in Born-Oppenheimer approximations. Both take advantage of adiabatic coupling in order to visualize Hamiltonian eigensolutions. RES of symmetric and D2 asymmetric top rank-2-tensor Hamiltonians are compared with Oh spherical top rank-4-tensor fine-structure clusters of 6-fold and 8-fold tunneling multiplets. Then extreme 12-fold and 24-fold multiplets are analyzed by RES plots of higher rank tensor Hamiltonians. Such extreme clustering is rare in fundamental bands but prevalent in hot bands, and analysis of its superfine structure requires more efficient labeling and a more powerful group theory. This is introduced using elementary examples involving two groups of order-6 (C6 and D3~C3v, then applied to families of Oh clusters in SF6 spectra and to extreme clusters.

  3. Revisit to diffraction anomalous fine structure

    International Nuclear Information System (INIS)

    Kawaguchi, T.; Fukuda, K.; Tokuda, K.; Shimada, K.; Ichitsubo, T.; Oishi, M.; Mizuki, J.; Matsubara, E.

    2014-01-01

    The diffraction anomalous fine structure method has been revisited by applying this measurement technique to polycrystalline samples and using an analytical method with the logarithmic dispersion relation. The diffraction anomalous fine structure (DAFS) method that is a spectroscopic analysis combined with resonant X-ray diffraction enables the determination of the valence state and local structure of a selected element at a specific crystalline site and/or phase. This method has been improved by using a polycrystalline sample, channel-cut monochromator optics with an undulator synchrotron radiation source, an area detector and direct determination of resonant terms with a logarithmic dispersion relation. This study makes the DAFS method more convenient and saves a large amount of measurement time in comparison with the conventional DAFS method with a single crystal. The improved DAFS method has been applied to some model samples, Ni foil and Fe 3 O 4 powder, to demonstrate the validity of the measurement and the analysis of the present DAFS method

  4. Angle-resolved photoemission extended fine structure

    International Nuclear Information System (INIS)

    Barton, J.J.

    1985-03-01

    Measurements of the Angle-Resolved Photoemission Extended Fine Structure (ARPEFS) from the S(1s) core level of a c(2 x 2)S/Ni(001) are analyzed to determine the spacing between the S overlayer and the first and second Ni layers. ARPEFS is a type of photoelectron diffraction measurement in which the photoelectron kinetic energy is swept typically from 100 to 600 eV. By using this wide range of intermediate energies we add high precision and theoretical simplification to the advantages of the photoelectron diffraction technique for determining surface structures. We report developments in the theory of photoelectron scattering in the intermediate energy range, measurement of the experimental photoemission spectra, their reduction to ARPEFS, and the surface structure determination from the ARPEFS by combined Fourier and multiple-scattering analyses. 202 refs., 67 figs., 2 tabs

  5. Features and Recursive Structure

    Directory of Open Access Journals (Sweden)

    Kuniya Nasukawa

    2015-01-01

    Full Text Available Based on the cross-linguistic tendency that weak vowels are realized with a central quality such as ə, ɨ, or ɯ, this paper attempts to account for this choice by proposing that the nucleus itself is one of the three monovalent vowel elements |A|, |I| and |U| which function as the building blocks of melodic structure. I claim that individual languages make a parametric choice to determine which of the three elements functions as the head of a nuclear expression. In addition, I show that elements can be freely concatenated to create melodic compounds. The resulting phonetic value of an element compound is determined by the specific elements it contains and by the head-dependency relations between those elements. This concatenation-based recursive mechanism of melodic structure can also be extended to levels above the segment, thus ultimately eliminating the need for syllabic constituents. This approach reinterprets the notion of minimalism in phonology by opposing the string-based flat structure.

  6. Fine-Scale Genetic Structure in Finland

    Directory of Open Access Journals (Sweden)

    Sini Kerminen

    2017-10-01

    Full Text Available Coupling dense genotype data with new computational methods offers unprecedented opportunities for individual-level ancestry estimation once geographically precisely defined reference data sets become available. We study such a reference data set for Finland containing 2376 such individuals from the FINRISK Study survey of 1997 both of whose parents were born close to each other. This sampling strategy focuses on the population structure present in Finland before the 1950s. By using the recent haplotype-based methods ChromoPainter (CP and FineSTRUCTURE (FS we reveal a highly geographically clustered genetic structure in Finland and report its connections to the settlement history as well as to the current dialectal regions of the Finnish language. The main genetic division within Finland shows striking concordance with the 1323 borderline of the treaty of Nöteborg. In general, we detect genetic substructure throughout the country, which reflects stronger regional genetic differences in Finland compared to, for example, the UK, which in a similar analysis was dominated by a single unstructured population. We expect that similar population genetic reference data sets will become available for many more populations in the near future with important applications, for example, in forensic genetics and in genetic association studies. With this in mind, we report those extensions of the CP + FS approach that we found most useful in our analyses of the Finnish data.

  7. Fishermen Follow Fine-Scale Physical Ocean Features for Finance

    Directory of Open Access Journals (Sweden)

    James R. Watson

    2018-02-01

    Full Text Available The seascapes on which many millions of people make their living and secure food have complex and dynamic spatial features—the figurative hills and valleys—that influence where and how people work at sea. Here, we quantify the physical mosaic of the surface ocean by identifying Lagrangian Coherent Structures for a whole seascape—the U.S. California Current Large Marine Ecosystem—and assess their impact on the spatial distribution of fishing. We observe that there is a mixed response: some fisheries track these physical features, and others avoid them. These spatial behaviors map to economic impacts, in particular we find that tuna fishermen can expect to make three times more revenue per trip if fishing occurs on strong Lagrangian Coherent Structures. However, we find no relationship for salmon and pink shrimp fishing trips. These results highlight a connection between the biophysical state of the oceans, the spatial patterns of human activity, and ultimately the economic welfare of coastal communities.

  8. An Einstein-Cartan Fine Structure Constant Definition

    Directory of Open Access Journals (Sweden)

    Stone R. A. Jr.

    2010-01-01

    Full Text Available The fine structure constant definition given in Stone R.A. Jr. Progress in Physics, 2010, v.1, 11-13 is compared to an Einstein-Cartan fine structure constant definition. It is shown that the Einstein-Cartan definition produces the correct pure theory value, just not the measure value. To produce the measured value, the pure theory Einstein-Cartan fine structure constant requires only the new variables and spin coupling of the fine structure constant definition in [1].

  9. Fine structure of charge exchange lines observed in laboratory plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Ida, K.; Nishimura, S. [National Inst. for Fusion Science, Nagoya (Japan); Kondo, K.

    1997-01-01

    The influence of the fine structure of charge exchange lines appears only at the plasma edge or in the recombining phase where the ion temperature is low enough. The observed spectra in Li III and C VI are consistent with the sum of fine-structure components populated by statistical weights (assuming complete l-mixing) not by direct charge exchange cross sections. Some discrepancy was observed in the intensity ratio of fine-structure components between the observation and calculation for C VI in the recombining phase. The fine-structure of charge exchange lines gives an apparent Doppler shift in plasma rotation velocity measurement using charge exchange spectroscopy. (author)

  10. The origin of fine structure in near-field scanning optical lithography of an electroactive polymer

    International Nuclear Information System (INIS)

    Cotton, Daniel V; Belcher, Warwick J; Dastoor, Paul C; Fell, Christopher J

    2008-01-01

    Near-field scanning optical lithography (NSOL) has been used to produce arbitrary structures of the electroactive polymer polyphenylenevinylene at sizes comparable to optical wavelengths, which are of interest for integrated optical devices. The structures are characterized using AFM and SEM and exhibit interesting fine structure. The characteristic size and shape of the lithographic features and their associated fine structure have been examined in the context of the electric field distribution at the near-field scanning optical microscope tip. In particular, the Bethe-Bouwkamp model for electric field distribution at an aperture has been used in combination with a recently developed model for precursor solubility dependence on UV energy dose to predict the characteristics of lithographic features produced by NSOL. The fine structure in the lithographic features is also investigated and explained. Suggestions for the further improvement of the technique are made.

  11. Atomic fine structure in a space of constant curvature

    International Nuclear Information System (INIS)

    Bessis, N.; Bessis, G.; Shamseddine, R.

    1982-01-01

    As a contribution to a tentative formulation of atomic physics in a curved space, the determination of atomic fine structure energies in a space of constant curvature is investigated. Starting from the Dirac equation in a curved space-time, the analogue of the Pauli equation in a general coordinate system is derived. The theoretical curvature induced shifts and splittings of the fine structure energy levels are put in evidence and examined for the particular case of the hydrogenic n=2 levels. (author)

  12. Spin fine structure of optically excited quantum dot molecules

    Science.gov (United States)

    Scheibner, M.; Doty, M. F.; Ponomarev, I. V.; Bracker, A. S.; Stinaff, E. A.; Korenev, V. L.; Reinecke, T. L.; Gammon, D.

    2007-06-01

    The interaction between spins in coupled quantum dots is revealed in distinct fine structure patterns in the measured optical spectra of InAs/GaAs double quantum dot molecules containing zero, one, or two excess holes. The fine structure is explained well in terms of a uniquely molecular interplay of spin-exchange interactions, Pauli exclusion, and orbital tunneling. This knowledge is critical for converting quantum dot molecule tunneling into a means of optically coupling not just orbitals but also spins.

  13. The fine-structure constant before quantum mechanics

    International Nuclear Information System (INIS)

    Kragh, Helge

    2003-01-01

    This paper focuses on the early history of the fine-structure constant, largely the period until 1925. Contrary to what is generally assumed, speculations concerning the interdependence of the elementary electric charge and Planck's constant predated Arnold Sommerfeld's 1916 discussion of the dimensionless constant. This paper pays particular attention to a little known work from 1914 in which G N Lewis and E Q Adams derived what is effectively a numerical expression for the fine-structure constant

  14. Impaired perception of temporal fine structure and musical timbre in cochlear implant users.

    Science.gov (United States)

    Heng, Joseph; Cantarero, Gabriela; Elhilali, Mounya; Limb, Charles J

    2011-10-01

    Cochlear implant (CI) users demonstrate severe limitations in perceiving musical timbre, a psychoacoustic feature of sound responsible for 'tone color' and one's ability to identify a musical instrument. The reasons for this limitation remain poorly understood. In this study, we sought to examine the relative contributions of temporal envelope and fine structure for timbre judgments, in light of the fact that speech processing strategies employed by CI systems typically employ envelope extraction algorithms. We synthesized "instrumental chimeras" that systematically combined variable amounts of envelope and fine structure in 25% increments from two different source instruments with either sustained or percussive envelopes. CI users and normal hearing (NH) subjects were presented with 150 chimeras and asked to determine which instrument the chimera more closely resembled in a single-interval two-alternative forced choice task. By combining instruments with similar and dissimilar envelopes, we controlled the valence of envelope for timbre identification and compensated for envelope reconstruction from fine structure information. Our results show that NH subjects utilize envelope and fine structure interchangeably, whereas CI subjects demonstrate overwhelming reliance on temporal envelope. When chimeras were created from dissimilar envelope instrument pairs, NH subjects utilized a combination of envelope (p = 0.008) and fine structure information (p = 0.009) to make timbre judgments. In contrast, CI users utilized envelope information almost exclusively to make timbre judgments (p < 0.001) and ignored fine structure information (p = 0.908). Interestingly, when the value of envelope as a cue was reduced, both NH subjects and CI users utilized fine structure information to make timbre judgments (p < 0.001), although the effect was quite weak in CI users. Our findings confirm that impairments in fine structure processing underlie poor perception of musical timbre in CI

  15. Connecting traces of galaxy evolution: the missing core mass-morphological fine structure relation

    Science.gov (United States)

    Bonfini, P.; Bitsakis, T.; Zezas, A.; Duc, P.-A.; Iodice, E.; González-Martín, O.; Bruzual, G.; González Sanoja, A. J.

    2018-01-01

    Deep exposure imaging of early-type galaxies (ETGs) are revealing the second-order complexity of these objects, which have been long considered uniform, dispersion-supported spheroidals. `Fine structure' features (e.g. ripples, plumes, tidal tails, rings) as well as depleted stellar cores (i.e. central light deficits) characterize a number of massive ETG galaxies, and can be interpreted as the result of galaxy-galaxy interactions. We discuss how the time-scale for the evolution of cores and fine structures are comparable, and hence it is expected that they develop in parallel after the major interaction event which shaped the ETG. Using archival data, we compare the `depleted stellar mass' (i.e. the mass missing from the depleted stellar core) against the prominence of the fine structure features, and observe that they correlate inversely. This result confirms our expectation that, while the supermassive black hole (SMBH) binary (constituted by the SMBHs of the merger progenitors) excavates the core via three-body interactions, the gravitational potential of the newborn galaxy relaxes, and the fine structures fade below detection levels. We expect the inverse correlation to hold at least within the first Gyr from the merger which created the SMBH binary; after then, the fine structure evolves independently.

  16. Combining fine texture and coarse color features for color texture classification

    Science.gov (United States)

    Wang, Junmin; Fan, Yangyu; Li, Ning

    2017-11-01

    Color texture classification plays an important role in computer vision applications because texture and color are two fundamental visual features. To classify the color texture via extracting discriminative color texture features in real time, we present an approach of combining the fine texture and coarse color features for color texture classification. First, the input image is transformed from RGB to HSV color space to separate texture and color information. Second, the scale-selective completed local binary count (CLBC) algorithm is introduced to extract the fine texture feature from the V component in HSV color space. Third, both H and S components are quantized at an optimal coarse level. Furthermore, the joint histogram of H and S components is calculated, which is considered as the coarse color feature. Finally, the fine texture and coarse color features are combined as the final descriptor and the nearest subspace classifier is used for classification. Experimental results on CUReT, KTH-TIPS, and New-BarkTex databases demonstrate that the proposed method achieves state-of-the-art classification performance. Moreover, the proposed method is fast enough for real-time applications.

  17. The Fine Structure of Herman Rings

    DEFF Research Database (Denmark)

    Fagella, Nuria; Henriksen, Christian

    2017-01-01

    We study the geometric structure of the boundary of Herman rings in a model family of Blaschke products of degree 3 (up to quasiconformal deformation). Shishikura’s quasiconformal surgery relates the Herman ring to the Siegel disk of a quadratic polynomial. By studying the regularity properties...

  18. Spectral fine structure effects on material and doppler reactivity worth

    International Nuclear Information System (INIS)

    Greenspan, E.; Karni, Y.

    1975-01-01

    New formulations concerning the fine structure effects on the reactivity worth of resonances are developed and conclusions are derived following the extension to more general types of perturbations which include: the removal of resonance material at finite temperatures and the temperature variation of part of the resonance material. It is concluded that the flux method can overpredict the reactivity worth of resonance materials more than anticipated. Calculations on the Doppler worth were carried out; the results can be useful for asessing the contribution of the fine structure effects to the large discrepancy that exists between the calculated and measured small sample Doppler worths. (B.G.)

  19. Coupled channels description of the α-decay fine structure

    Science.gov (United States)

    Delion, D. S.; Ren, Zhongzhou; Dumitrescu, A.; Ni, Dongdong

    2018-05-01

    We review the coupled channels approach of α transitions to excited states. The α-decaying states are identified as narrow outgoing Gamow resonances in an α-daughter potential. The real part of the eigenvalue corresponds to the Q-value, while the imaginary part determines the half of the total α-decay width. We first review the calculations describing transitions to rotational states treated by the rigid rotator model, in even–even, odd-mass and odd–odd nuclei. It is found that the semiclassical method overestimates the branching ratios to excited 4+ for some even–even α-emitters and fails in explaining the unexpected inversion of branching ratios of some odd-mass nuclei, while the coupled-channels results show good agreement with the experimental data. Then, we review the coupled channels method for α-transitions to 2+ vibrational and transitional states. We present the results of the Coherent State Model that describes in a unified way the spectra of vibrational, transitional and rotational nuclei. We evidence general features of the α-decay fine structure, namely the linear dependence between α-intensities and excitation energy, the linear correlation between the strength of the α-core interaction and spectroscopic factor, and the inverse correlation between the nuclear collectivity, given by electromagnetic transitions, and α-clustering.

  20. The Fine Structure of Equity-Index Option Dynamics

    DEFF Research Database (Denmark)

    Andersen, Torben G.; Bondarenko, Oleg; Todorov, Viktor

    We analyze the high-frequency dynamics of S&P 500 equity-index option prices by constructing an assortment of implied volatility measures. This allows us to infer the underlying fine structure behind the innovations in the latent state variables driving the movements of the volatility surface...

  1. Fine structure of fields in 2D photonic crystal waveguides

    DEFF Research Database (Denmark)

    Lavrinenko, Andrei; Volkov, V. S.; Bozhevolnyi, S. I.

    2006-01-01

    We resolve fine structure of fields in a single-row missing photonic crystal waveguide by finite-difference time-domain modelling and SNOM measurements. Both linear dispersion and slow-light regimes in proximity of the cutoff are addressed in the analysis....

  2. Fine-structure energy levels, oscillator strengths and lifetimes of ...

    Indian Academy of Sciences (India)

    with the experimental results compiled in the NIST Data Base. Many new ... Keywords. Relativistic fine-structure levels; oscillator strengths; lifetimes. ... have calculated oscillator strengths and lifetimes using the Briet–Pauli R-Matrix ..... [2] The Opacity Project Team, The Opacity Project (Institute of Physics Publishing,. Bristol ...

  3. Strained spiral vortex model for turbulent fine structure

    Science.gov (United States)

    Lundgren, T. S.

    1982-01-01

    A model for the intermittent fine structure of high Reynolds number turbulence is proposed. The model consists of slender axially strained spiral vortex solutions of the Navier-Stokes equation. The tightening of the spiral turns by the differential rotation of the induced swirling velocity produces a cascade of velocity fluctuations to smaller scale. The Kolmogorov energy spectrum is a result of this model.

  4. The prediction and discovery of Rayleigh line fine structure

    International Nuclear Information System (INIS)

    Fabelinskii, Immanuil L

    2000-01-01

    The history of the theoretical prediction and experimental discovery of the Rayleigh line fine structure (which belongs to one of the most important phenomena in optics and physics of condensed matter) is discussed along with the history of first publications concerning this topic. (from the history of physics)

  5. Structural features of lignohumic acids

    Czech Academy of Sciences Publication Activity Database

    Novák, František; Šestauberová, Martina; Hrabal, R.

    2015-01-01

    Roč. 1093, August (2015), s. 179-185 ISSN 0022-2860 Institutional support: RVO:60077344 Keywords : C-13 NMR * FTIR * humic acids * lignohumate * lignosulfonate * structure Subject RIV: DF - Soil Science Impact factor: 1.780, year: 2015

  6. An estimation of the fine structure constant using fiber bundles

    International Nuclear Information System (INIS)

    Ross, D.K.

    1986-01-01

    Ross calculates g 0 /e, where g 0 is the strength of an elementary magnetic monopole and e is the charge on the electron, in terms of a ratio of loop sizes in the twisted and untwisted principal fiber bundles with U (1) the structure group and R 3 -(0) the base space. The result involves the present distance around the U (1) space and, rather surprisingly, the structure of the quantum gravitational vacuum. Combining this result with the expression for eg 0 from the Dirac quantization conditions gives a final estimate for the fine structure constant, alpha, near 1/100

  7. Simple Model with Time-Varying Fine-Structure ``Constant''

    Science.gov (United States)

    Berman, M. S.

    2009-10-01

    Extending the original version written in colaboration with L.A. Trevisan, we study the generalisation of Dirac's LNH, so that time-variation of the fine-structure constant, due to varying electrical and magnetic permittivities is included along with other variations (cosmological and gravitational ``constants''), etc. We consider the present Universe, and also an inflationary scenario. Rotation of the Universe is a given possibility in this model.

  8. Fine structure of the exciton electroabsorption in semiconductor superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Monozon, B.S., E-mail: borismonozon@mail.ru [Physics Department, Marine Technical University, 3 Lotsmanskaya Str., 190008 St.Petersburg (Russian Federation); Schmelcher, P. [Zentrum für Optische Quantentechnologien, The Hamburg Centre for Ultrafast Imaging, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany)

    2017-02-15

    Wannier-Mott excitons in a semiconductor layered superlattice (SL) are investigated analytically for the case that the period of the superlattice is much smaller than the 2D exciton Bohr radius. Additionally we assume the presence of a longitudinal external static electric field directed parallel to the SL axis. The exciton states and the optical absorption coefficient are derived in the tight-binding and adiabatic approximations. Strong and weak electric fields providing spatially localized and extended electron and hole states, respectively, are studied. The dependencies of the exciton states and the exciton absorption spectrum on the SL parameters and the electric field strength are presented in an explicit form. We focus on the fine structure of the ground quasi-2D exciton level formed by the series of closely spaced energy levels adjacent from the high frequencies. These levels are related to the adiabatically slow relative exciton longitudinal motion governed by the potential formed by the in-plane exciton state. It is shown that the external electric fields compress the fine structure energy levels, decrease the intensities of the corresponding optical peaks and increase the exciton binding energy. A possible experimental study of the fine structure of the exciton electroabsorption is discussed.

  9. Helium induced fine structure in the electronic spectra of anthracene derivatives doped into superfluid helium nanodroplets

    International Nuclear Information System (INIS)

    Pentlehner, D.; Slenczka, A.

    2015-01-01

    Electronic spectra of organic molecules doped into superfluid helium nanodroplets show characteristic features induced by the helium environment. Besides a solvent induced shift of the electronic transition frequency, in many cases, a spectral fine structure can be resolved for electronic and vibronic transitions which goes beyond the expected feature of a zero phonon line accompanied by a phonon wing as known from matrix isolation spectroscopy. The spectral shape of the zero phonon line and the helium induced phonon wing depends strongly on the dopant species. Phonon wings, for example, are reported ranging from single or multiple sharp transitions to broad (Δν > 100 cm −1 ) diffuse signals. Despite the large number of example spectra in the literature, a quantitative understanding of the helium induced fine structure of the zero phonon line and the phonon wing is missing. Our approach is a systematic investigation of related molecular compounds, which may help to shed light on this key feature of microsolvation in superfluid helium droplets. This paper is part of a comparative study of the helium induced fine structure observed in electronic spectra of anthracene derivatives with particular emphasis on a spectrally sharp multiplet splitting at the electronic origin. In addition to previously discussed species, 9-cyanoanthracene and 9-chloroanthracene will be presented in this study for the first time

  10. Fine Resolution Termohaline Structure Of The Yuctatan Coastal Sea

    Science.gov (United States)

    Marino-Tapia, I.; Enriquez-Ortiz, C.; Capurro, L.; Euan-Avila, J.

    2007-05-01

    In the Yucatan peninsula there are a variety processes that drastically affect the thermohaline structure of the coastal seas. Some of these include hyperhaline lagoons that export salt to the ocean, upwelling events that propagate to the coast, persistent submarine groundwater discharges, and very high evaporation rates caused by the intense solar radiation. On July 2006 a fine resolution oceanographic campaign was performed on the Yucatan coast to study the detailed structure of thermohaline processes and currents from the shore to the 10 m isobath. A total of sixty nine transects that cover the entire northern stretch of the Yucatan coast were made. The transects extend seven kilometers in the offshore direction and have an alongshore spacing of 5 km. The temperature and salinity characteristics of the water column were monitored with a SEABIRD SBE 19 CTD performing profiles every 500 m along each transect. Ocean currents were measures along the same transect using a 1.5 MHz Acoustic Doppler Profiler (Sontek). The results clearly show the effects of coastal lagoons on the adjoining sea, with net salt export associated with hyperhaline lagoons (e.g. Ria Lagartos) or more estuarine influence of lagoons such as Celestun, where groundwater discharges play the role of rivers on the estuary. An assessment of this influence on the coastal ocean will be presented. It is well known the meteor impact at the end of the Cretacic era at Chicxulub, Yucatan, generated a crater with multiple rings which is evident from horizontal gravity gradients of the Yucatan mainland, and that associated with the outer ring there is a high concentration of cenotes (sinkholes) (Pope et al. 1991; Hildebrand, et al. 1995). It has also been shown that groundwater flows along this cenote ring towards the ocean, and the zones where the ring intersects the coast (Celestun and Dzilam Bravo) have impressive geologic features known as `submarine water springs' where freshwater springs as a fountain

  11. Exploring the fine structure at the limb in coronal holes

    Science.gov (United States)

    Karovska, Magarita; Blundell, Solon F.; Habbal, Shadia Rifai

    1994-01-01

    The fine structure of the solar limb in coronal holes is explored at temperatures ranging from 10(exp 4) to 10(exp 6) K. An image enhancement algorithm orignally developed for solar eclipse observations is applied to a number of simultaneous multiwavelength observations made with the Harvard Extreme Ultraviolet Spectrometer experiment on Skylab. The enhanced images reveal the presence of filamentary structures above the limb with a characteristic separation of approximately 10 to 15 sec . Some of the structures extend from the solar limb into the corona to at least 4 min above the solar limb. The brightness of these structures changes as a function of height above the limb. The brightest emission is associated with spiculelike structures in the proximity of the limb. The emission characteristic of high-temperature plasma is not cospatial with the emission at lower temperatures, indicating the presence of different temperature plasmas in the field of view.

  12. Diffraction anomalous fine structure using X-ray anomalous dispersion

    International Nuclear Information System (INIS)

    Soejima, Yuji; Kuwajima, Shuichiro

    1998-01-01

    A use of X-ray anomalous dispersion effects for structure investigation has recently been developed by using synchrotron radiation. One of the interesting method is the observation of anomalous fine structure which arise on diffraction intensity in energy region of incident X-ray at and higher than absorption edge. The phenomenon is so called Diffraction Anomalous Fine Structure (DAFS). DAFS originates in the same physical process an that of EXAFS: namely photoelectric effect at the corresponding atom and the interaction of photoelectron waves between the atom and neighboring atoms. In contrast with EXAFS, the method is available for only the crystalline materials, but shows effective advantages of the structure investigations by a use of diffraction: one is the site selectivity and the other is space selectivity. In the present study, demonstrations of a use of X-ray anomalous dispersion effect for the superstructure determination will be given for the case of PbZrO 3 , then recent trial investigations of DAFS in particular on the superlattice reflections will be introduced. In addition, we discuss about Forbidden Reflection near Edge Diffraction (FRED) which is more recently investigated as a new method of the structure analysis. (author)

  13. Theoretical approaches to x-ray absorption fine structure

    International Nuclear Information System (INIS)

    Rehr, J. J.; Albers, R. C.

    2000-01-01

    Dramatic advances in the understanding of x-ray absorption fine structure (XAFS) have been made over the past few decades, which have led ultimately to a highly quantitative theory. This review covers these developments from a unified multiple-scattering viewpoint. The authors focus on extended x-ray absorption fine structure (EXAFS) well above an x-ray edge, and, to a lesser extent, on x-ray absorption near-edge structure (XANES) closer to an edge. The discussion includes both formal considerations, derived from a many-electron formulation, and practical computational methods based on independent-electron models, with many-body effects lumped into various inelastic losses and energy shifts. The main conceptual issues in XAFS theory are identified and their relative importance is assessed; these include the convergence of the multiple-scattering expansion, curved-wave effects, the scattering potential, inelastic losses, self-energy shifts, and vibrations and structural disorder. The advantages and limitations of current computational approaches are addressed, with particular regard to quantitative experimental comparisons. (c) 2000 The American Physical Society

  14. The influence of fine-scale habitat features on regional variation in population performance of alpine White-tailed Ptarmigan

    Science.gov (United States)

    Fedy, B.; Martin, K.

    2011-01-01

    It is often assumed (explicitly or implicitly) that animals select habitat features to maximize fitness. However, there is often a mismatch between preferred habitats and indices of individual and population measures of performance. We examined the influence of fine-scale habitat selection on the overall population performance of the White-tailed Ptarmigan (Lagopus leucura), an alpine specialist, in two subdivided populations whose habitat patches are configured differently. The central region of Vancouver Island, Canada, has more continuous and larger habitat patches than the southern region. In 2003 and 2004, using paired logistic regression between used (n = 176) and available (n = 324) sites, we identified food availability, distance to standing water, and predator cover as preferred habitat components . We then quantified variation in population performance in the two regions in terms of sex ratio, age structure (n = 182 adults and yearlings), and reproductive success (n = 98 females) on the basis of 8 years of data (1995-1999, 2002-2004). Region strongly influenced females' breeding success, which, unsuccessful hens included, was consistently higher in the central region (n = 77 females) of the island than in the south (n = 21 females, P = 0.01). The central region also had a much higher proportion of successful hens (87%) than did the south (55%, P < 0.001). In light of our findings, we suggest that population performance is influenced by a combination of fine-scale habitat features and coarse-scale habitat configuration. ?? The Cooper Ornithological Society 2011.

  15. On the value of the fine structure constant

    International Nuclear Information System (INIS)

    Bosi, L.

    1997-01-01

    The fine structure constant can be approximately expressed as α = (20 var-phi 4 ) -1 where var-phi is the golden ratio (1 + √5)/2: the discrepancy between the present and the true value of α -1 is lower than 3.4· 10 -4 . This simple occurrence would be not fortuitous, thus suggesting a hidden physical meaning. A tentative and qualitative explanation is proposed which is based only on symmetry considerations involving both the Von Klitzing resistance and the vacuum impedance

  16. New Tests for Variations of the Fine Structure Constant

    Science.gov (United States)

    Prestage, John D.

    1995-01-01

    We describe a new test for possible variations of the fine structure constant, by comparisons of rates between clocks based on hyperfine transitions in alkali atomos with different atomic number Z. H- maser, Cs and Hg+ clocks have a different dependence on ia relativistic contributions of order (Z. Recent H-maser vs Hg+ clock comparison data improves laboratory limits on a time variation by 100-fold to giveFuture laser cooled clocks (Be+, Rb, Cs, Hg+, etc.), when compared, will yield the most senstive of all tests for.

  17. Relativistic corrections to the fine structure of positronium

    International Nuclear Information System (INIS)

    Faustov, R. N.; Martynenko, A. P.

    1997-01-01

    The quasipotential method is used to calculate relativistic corrections in the positronium-fine-structure intervals 2 3 S 1 -2 3 P J . From analysis of one- and two-photon interactions, corrections of order mα 6 are found for positronium S states in the second order of perturbation theory. The contribution of the two-photon annihilation diagrams to the interaction operator for P-wave positronium is determined, and corrections of orders α 5 R ∞ and α 5 ln αR ∞ to the P-wave levels of positronium are calculated

  18. Distortion product otoacoustic emission fine structure of symphony orchestra musicians

    DEFF Research Database (Denmark)

    Reuter, Karen; Hammershøi, Dorte

    2006-01-01

    Otoacoustic emissions (OAE) are sounds produced by the healthy inner ear. They can be measured as low-level signals in the ear canal and are used to monitor the functioning of outer hair cells.Several studies indicate that OAE might be a more sensitive measure to detect early noise-induced hearing...... losses than puretone audiometry. The distortion product otoacoustic emission (DPOAE) fine structure is obtained when the ear is stimulated by dual tone stimuli using a high frequency resolution. It is characterized by quasi-periodic variations across frequency, as it can be observed in the hearing...

  19. Fine structure study on low concentration zinc substituted hydroxyapatite nanoparticles

    International Nuclear Information System (INIS)

    Hu, Wei; Ma, Jun; Wang, Jianglin; Zhang, Shengmin

    2012-01-01

    The fine structure of zinc substituted hydroxyapatite was studied using experimental analysis and first-principles calculations. The synthetic hydroxyapatite nanoparticles containing low Zn concentration show rod-like morphology. The crystallite sizes and unit-cell volumes tended to decrease with the increased Zn concentration according to X-ray diffraction patterns. The Zn K-edge X-ray absorption spectra and fitting results suggest that the hydroxyapatite doped with 0.1 mole% zinc is different in the zinc coordination environments compared with that containing more zinc. The density function theory calculations were performed on zinc substituted hydroxyapatite. Two mechanisms included replacing calcium by zinc and inserting zinc along the hydroxyl column and were investigated, and the related substitution energies were calculated separately. It is found that the substitution energies are negative and lowest for inserting zinc between the two oxygen atoms along the hydroxyl column (c-axis). Combined with the spectral analysis, it is suggested that the inserting mechanism is favored for low concentration zinc substituted hydroxyapatite. Highlights: ► We investigate the fine structure of hydroxyapatite with low content of Zn. ► XANES spectra are similar but a little different at low zinc content. ► Zinc ions influence hydroxyapatite crystal formation and lattice parameters. ► Formation energies are calculated according to plane-wave density function theory. ► Low content of zinc prefers to locate at hydroxyl column in hydroxyapatite lattice.

  20. QED Based Calculation of the Fine Structure Constant

    Energy Technology Data Exchange (ETDEWEB)

    Lestone, John Paul [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-10-13

    Quantum electrodynamics is complex and its associated mathematics can appear overwhelming for those not trained in this field. Here, semi-classical approaches are used to obtain a more intuitive feel for what causes electrostatics, and the anomalous magnetic moment of the electron. These intuitive arguments lead to a possible answer to the question of the nature of charge. Virtual photons, with a reduced wavelength of λ, are assumed to interact with isolated electrons with a cross section of πλ2. This interaction is assumed to generate time-reversed virtual photons that are capable of seeking out and interacting with other electrons. This exchange of virtual photons between particles is assumed to generate and define the strength of electromagnetism. With the inclusion of near-field effects the model presented here gives a fine structure constant of ~1/137 and an anomalous magnetic moment of the electron of ~0.00116. These calculations support the possibility that near-field corrections are the key to understanding the numerical value of the dimensionless fine structure constant.

  1. Measurement of the fine structure in 33P helium

    International Nuclear Information System (INIS)

    Yang, D.

    1985-01-01

    The author measured two positions of the Zeeman level crossing between the (J,M) = (2,2) and (0,0) and between the (J,M) = (1,1) and (0,0) sublevels of the 3 3 P state in helium. The zero field fine structure splittings were calculated from these two measured values. These splittings are of interest for a precision test of quantum electrodynamics and giving an independent contribution to fine structure constant determination. This experiment uses time resolved level crossing spectroscopy. A pulsed beam of helium 2 3 S metastables is excited by a pulse of 388.9 nm dye laser light to the 3 3 P state in a dc magnetic field interaction region. After a certain delay time, a 532 nm laser pulse ionizes the atoms from the 3 3 P state. The photoelectrons are detected by a microchannel plate. The magnetic field is in the z direction, while the atomic beam and the two laser beams are in the xy plane. These two laser beams couterpropagate at a 45 0 angle for the atomic beam for convenience. The photoionization signal is recorded as a function of magnetic field near each of the two crossing positions. Results for these two crossing positions are in agreement with, but more precise than, the previously reported results

  2. Influence of musical training on sensitivity to temporal fine structure.

    Science.gov (United States)

    Mishra, Srikanta K; Panda, Manasa R; Raj, Swapna

    2015-04-01

    The objective of this study was to extend the findings that temporal fine structure encoding is altered in musicians by examining sensitivity to temporal fine structure (TFS) in an alternative (non-Western) musician model that is rarely adopted--Indian classical music. The sensitivity to TFS was measured by the ability to discriminate two complex tones that differed in TFS but not in envelope repetition rate. Sixteen South Indian classical (Carnatic) musicians and 28 non-musicians with normal hearing participated in this study. Musicians have significantly lower relative frequency shift at threshold in the TFS task compared to non-musicians. A significant negative correlation was observed between years of musical experience and relative frequency shift at threshold in the TFS task. Test-retest repeatability of thresholds in the TFS tasks was similar for both musicians and non-musicians. The enhanced performance of the Carnatic-trained musicians suggests that the musician advantage for frequency and harmonicity discrimination is not restricted to training in Western classical music, on which much of the previous research on musical training has narrowly focused. The perceptual judgments obtained from non-musicians were as reliable as those of musicians.

  3. Black Holes and Quantum Theory: The Fine Structure Constant Connection

    Directory of Open Access Journals (Sweden)

    Cahill R. T.

    2006-10-01

    Full Text Available The new dynamical theory of space is further confirmed by showing that the effective “black hole” masses M BH in 19 spherical star systems, from globular clusters to galaxies, with masses M , satisfy the prediction that M BH = α 2 M , where α is the fine structure constant. As well the necessary and unique generalisations of the Schr ̈ odinger and Dirac equations permit the first derivation of gravity from a deeper theory, showing that gravity is a quantum effect of quantum matter interacting with the dynamical space. As well the necessary generalisation of Maxwell’s equations displays the observed light bending effects. Finally it is shown from the generalised Dirac equation where the spacetime mathematical formalism, and the accompanying geodesic prescription for matter trajectories, comes from. The new theory of space is non-local and we see many parallels between this and quantum theory, in addition to the fine structure constant manifesting in both, so supporting the argument that space is a quantum foam system, as implied by the deeper information-theoretic theory known as Process Physics. The spatial dynamics also provides an explanation for the “dark matter” effect and as well the non-locality of the dynamics provides a mechanism for generating the uniformity of the universe, so explaining the cosmological horizon problem.

  4. FINE MAGNETIC FEATURES AND CHIRALITY IN SOLAR ACTIVE REGION NOAA 10930

    International Nuclear Information System (INIS)

    Zhang Hongqi

    2010-01-01

    In this paper, we present fine magnetic features near the magnetic inversion line in the solar active region NOAA 10930. The high-resolution vector magnetograms obtained by Hinode allow detailed analyses around magnetic fibrils in the active region. The analyses are based on the fact that the electric current density can be divided into two components: the shear component caused by the magnetic inhomogeneity and the twist component caused by the magnetic field twist. The relationships between magnetic field, electric current density, and its two components are examined. It is found that the individual magnetic fibrils are dominated by the current density component caused by the magnetic inhomogeneity, while the large-scale magnetic region is generally dominated by the electric current component associated with the magnetic twist. The microstructure of the magnetic field in the solar atmosphere is far from the force-free field. The current mainly flows around the magnetic flux fibrils in the active regions.

  5. Resolving fine spectral features in lattice vibrational modes using femtosecond coherent spectroscopy

    Directory of Open Access Journals (Sweden)

    A. Card

    2016-02-01

    Full Text Available We show resolution of fine spectral features within several Raman active vibrational modes in potassium titanyl phosphate (KTP crystal. Measurements are performed using a femtosecond time-domain coherent anti-Stokes Raman scattering spectroscopy technique that is capable of delivering equivalent spectral resolution of 0.1 cm−1. The Raman spectra retrieved from our measurements show several spectral components corresponding to vibrations of different symmetry with distinctly different damping rates. In particular, linewidths for unassigned optical phonon mode triplet centered at around 820 cm−1 are found to be 7.5 ± 0.2 cm−1, 9.1 ± 0.3 cm−1, and 11.2 ± 0.3 cm−1. Results of our experiments will ultimately help to design an all-solid-state source for sub-optical-wavelength waveform generation that is based on stimulated Raman scattering.

  6. Fine-scale features on bioreplicated decoys of the emerald ash borer provide necessary visual verisimilitude

    Science.gov (United States)

    Domingue, Michael J.; Pulsifer, Drew P.; Narkhede, Mahesh S.; Engel, Leland G.; Martín-Palma, Raúl J.; Kumar, Jayant; Baker, Thomas C.; Lakhtakia, Akhlesh

    2014-03-01

    The emerald ash borer (EAB), Agrilus planipennis, is an invasive tree-killing pest in North America. Like other buprestid beetles, it has an iridescent coloring, produced by a periodically layered cuticle whose reflectance peaks at 540 nm wavelength. The males perform a visually mediated ritualistic mating flight directly onto females poised on sunlit leaves. We attempted to evoke this behavior using artificial visual decoys of three types. To fabricate decoys of the first type, a polymer sheet coated with a Bragg-stack reflector was loosely stamped by a bioreplicating die. For decoys of the second type, a polymer sheet coated with a Bragg-stack reflector was heavily stamped by the same die and then painted green. Every decoy of these two types had an underlying black absorber layer. Decoys of the third type were produced by a rapid prototyping machine and painted green. Fine-scale features were absent on the third type. Experiments were performed in an American ash forest infested with EAB, and a European oak forest home to a similar pest, the two-spotted oak borer (TSOB), Agrilus biguttatus. When pinned to leaves, dead EAB females, dead TSOB females, and bioreplicated decoys of both types often evoked the complete ritualized flight behavior. Males also initiated approaches to the rapidly prototyped decoy, but would divert elsewhere without making contact. The attraction of the bioreplicated decoys was also demonstrated by providing a high dc voltage across the decoys that stunned and killed approaching beetles. Thus, true bioreplication with fine-scale features is necessary to fully evoke ritualized visual responses in insects, and provides an opportunity for developing insecttrapping technologies.

  7. Acoustic fine structure may encode biologically relevant information for zebra finches.

    Science.gov (United States)

    Prior, Nora H; Smith, Edward; Lawson, Shelby; Ball, Gregory F; Dooling, Robert J

    2018-04-18

    The ability to discriminate changes in the fine structure of complex sounds is well developed in birds. However, the precise limit of this discrimination ability and how it is used in the context of natural communication remains unclear. Here we describe natural variability in acoustic fine structure of male and female zebra finch calls. Results from psychoacoustic experiments demonstrate that zebra finches are able to discriminate extremely small differences in fine structure, which are on the order of the variation in acoustic fine structure that is present in their vocal signals. Results from signal analysis methods also suggest that acoustic fine structure may carry information that distinguishes between biologically relevant categories including sex, call type and individual identity. Combined, our results are consistent with the hypothesis that zebra finches can encode biologically relevant information within the fine structure of their calls. This study provides a foundation for our understanding of how acoustic fine structure may be involved in animal communication.

  8. Sonographic features and ultrasonography-guided fine-needle aspiration of metastases to the thyroid gland

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Jung Hyun; Kim, Eun Kyung; Kwak, Jin Young; Moon, Hee Jung; Kim, Ga Ram [Dept. of Radiology, Research Institute of Radiological Science, Yonsei University College of Medicine, Seoul (Korea, Republic of)

    2014-03-15

    To evaluate the characteristic ultrasonographic (US) features of metastatic carcinoma to the thyroid, and how accurate US features and ultrasonography-guided fine-needle aspiration (US-FNA) are for the diagnosis of thyroid metastases. Twenty-three thyroid lesions in 23 patients (mean age, 66.7 years; range, 46 to 85 years) that had been diagnosed as thyroid metastases were included. The composition, echogenicity, margin, shape, presence of calcifications, underlying parenchymal echotexture, and vascularity were analyzed in US images of the thyroid metastases. Final US assessments were categorized into probably benign and suspicious malignancy. The presence of suspicious metastatic cervical lymph nodes was noted. The medical records, US-FNA cytology, and pathology reports of these patients were retrospectively reviewed. Of the 23 thyroid lesions, the general US appearance was mass-forming in 21 (91.3%) and non-mass-forming in 2 (8.7%). All 23 lesions showed a solid tumor composition. Common US features among the 21 mass-forming thyroid metastases were hypoechogenicity (81.0%), non-circumscribed margins (90.5%), no calcifications (76.2%), and parallel shape (81.0%). Suspicious cervical lymph nodes were present in 18 patients (78.3%). Of the 23 lesions, 21 (91.3%) were classified as suspicious malignancy, and 2 (8.7%) as probably benign. US-FNA showed diagnostic results specific for metastases in 21 of the 22 patients (95.5%) who had undergone US-FNA. Common US features in thyroid metastasis were hypoechogenicity, non-circumscribed margins, no calcifications, parallel shape, and the presence of suspicious cervical lymph nodes. US-FNA can be effectively used in the diagnosis of thyroid metastasis, preventing unnecessary surgery.

  9. Astrophysical extended X-ray absorption fine-structure analysis

    International Nuclear Information System (INIS)

    Woo, J.W.; Forrey, R.C.; Cho, K.; Department of Physics and Division of Applied Sciences, Harvard University)

    1997-01-01

    We present an astrophysical extended X-ray absorption fine-structure (EXAFS) analysis (AEA) tool. The AEA tool is designed to generate a numerical model of the modification to the X-ray absorption coefficient due to the EXAFS phenomenon. We have constructed a complete database (elements up to the atomic number 92) of EXAFS parameters: central atom phase shift (2δ 1 ), backscattering phase shift (φ b ), and backscattering amplitude (F). Using the EXAFS parameter data base, the AEA tool can generate a numerical model of any compound when the atomic numbers of neighboring atoms and their distances to the central X-ray-absorbing atom are given. copyright 1997 The American Astronomical Society

  10. Alpha-decay fine structure versus electromagnetic transitions

    International Nuclear Information System (INIS)

    Peltonen, S.

    2003-01-01

    Alpha decay of even-even Rn isotopes is studied microscopically along the lines of Phys. Rev. C 64, 302 (2001). The results are compared against experimental fine-structure hindrance factors (HFs). We consider problems related to reproducing observed HFs with nuclear models, especially in case of the collective 2 + - excitations. We use the QRPA model with isovector SDI interaction in order to systematically evaluate theoretical HFs. Pairing gaps and the experimental energy of the 2 + - state fix all interaction parameters except the ratio between the isovector and isoscalar interaction strengths that is used as an additional free parameter of the model. Correlation between the electromagnetic E2-strength and HFs is observed, depending both on the isotope and the excitation energy. The choice of the single particle basis appears to affect strongly the theoretical HFs. Further and even more systematical studies are required in order explain this behaviour. (author)

  11. Time variation of the fine structure constant driven by quintessence

    International Nuclear Information System (INIS)

    Anchordoqui, Luis; Goldberg, Haim

    2003-01-01

    There are indications from the study of quasar absorption spectra that the fine structure constant α may have been measurably smaller for redshifts z>2. Analyses of other data ( 149 Sm fission rate for the Oklo natural reactor, variation of 187 Re β-decay rate in meteorite studies, atomic clock measurements) which probe variations of α in the more recent past imply much smaller deviations from its present value. In this work we tie the variation of α to the evolution of the quintessence field proposed by Albrecht and Skordis, and show that agreement with all these data, as well as consistency with Wilkinson Microwave Anisotropy Probe observations, can be achieved for a range of parameters. Some definite predictions follow for upcoming space missions searching for violations of the equivalence principle

  12. Fine structure in the cluster decays of the translead nuclei

    International Nuclear Information System (INIS)

    Dumitrescu, O.; Cioaca, C.

    1994-06-01

    Within the one level R-matrix approach several hindrance factors for the radioactive decays in which are emitted α and other nuclei (such as 14 C and 20 O) are calculated. The interior wave functions are supposed to be given by the shell model with effective residual interactions. The exterior wave functions are calculated from a cluster - nucleus double - folding model potential with the M3Y interaction. As examples of the cluster decay fine structure we analyzed the particular cases of α - decay of 255 Fm, 14 C - decay of 223 Ra and 20 O - decay of 229 Th and 225 Fm. Good agreement with the experimental data is obtained. (author). 38 refs, 6 tabs

  13. An Investigation of the Fine Spatial Structure of Meteor Streams Using the Relational Database ``Meteor''

    Science.gov (United States)

    Karpov, A. V.; Yumagulov, E. Z.

    2003-05-01

    We have restored and ordered the archive of meteor observations carried out with a meteor radar complex ``KGU-M5'' since 1986. A relational database has been formed under the control of the Database Management System (DBMS) Oracle 8. We also improved and tested a statistical method for studying the fine spatial structure of meteor streams with allowance for the specific features of application of the DBMS. Statistical analysis of the results of observations made it possible to obtain information about the substance distribution in the Quadrantid, Geminid, and Perseid meteor streams.

  14. The structure of hydrate bearing fine grained marine sediments

    Energy Technology Data Exchange (ETDEWEB)

    Priest, J.; Kingston, E.; Clayton, C. [Southampton Univ., Highfield (United Kingdom). School of Civil Engineering and the Environment; Schultheiss, P.; Druce, M. [Geotek Ltd., Daventry (United Kingdom)

    2008-07-01

    This paper discussed the structure of naturally occurring methane gas hydrates in fine-grained sediments from core samples recovered using in situ pressures from the eastern margin of the Indian Ocean. High resolution X-ray computed tomography (CT) images were taken of gas hydrate cores. The hydrate structure was examined and comparisons were made between low resolution X-ray images obtained on the cores prior to sub-sectioning and depressurization procedures. The X-ray images showed the presence of high-angle, sub-parallel veins within the recovered sediments. The scans indicated that the hydrates occurred as fracture filing veins throughout the core. Fracture orientation was predominantly sub-vertical. Thick millimetric hydrate veins were composed of sub-millimetric veins with variations in fracture angle. The analysis indicated that hydrate formation was episodic in nature and subject to changes in the stress regime. Results of the study showed that depressurization and subsequent freezing alter the structure of the sediment even when the gas hydrate has not been altered. A large proportion of the hydrate survived when outside of its stability region. The self-preserving behaviour of the hydrate was attributed to the endothermic nature of gas hydrate dissociation. It was concluded that the accurate physical characterization of gas hydrates can only be conducted when the core section remains under in situ stress conditions. 13 refs., 9 figs.

  15. The importance of source positions during radio fine structure observations

    International Nuclear Information System (INIS)

    Chernov, Guennadi P.; Yan Yi-Hua; Fu Qi-Jun

    2014-01-01

    The measurement of positions and sizes of radio sources in the observations of the fine structure of solar radio bursts is a determining factor for the selection of the radio emission mechanism. The identical parameters describing the radio sources for zebra structures (ZSs) and fiber bursts confirm there is a common mechanism for both structures. It is very important to measure the size of the source in the corona to determine if it is distributed along the height or if it is point-like. In both models of ZSs (the double plasma resonance (DPR) and the whistler model) the source must be distributed along the height, but by contrast to the stationary source in the DPR model, in the whistler model the source should be moving. Moreover, the direction of the space drift of the radio source must correlate with the frequency drift of stripes in the dynamic spectrum. Some models of ZSs require a local source, for example, the models based on the Bernstein modes, or on explosive instability. The selection of the radio emission mechanism for fast broadband pulsations with millisecond duration also depends on the parameters of their radio sources. (mini-volume: solar radiophysics — recent results on observations and theories)

  16. Galaxy clusters, type Ia supernovae and the fine structure constant

    Energy Technology Data Exchange (ETDEWEB)

    Holanda, R.F.L. [Departamento de Física, Universidade Estadual da Paraíba, street Baraúnas, Campina Grande, PB, 58429-500 (Brazil); Busti, V.C. [Departamento de Física Matemática, Instituto de Física, Universidade de São Paulo, CP 66318, São Paulo, SP, CEP 05508-090 Brazil (Brazil); Colaço, L.R. [Departamento de Física, Universidade Federal de Campina Grande, street Aprígio Veloso, Campina Grande, PB, 58429-900 (Brazil); Alcaniz, J.S. [Observatório Nacional, Street José Cristino, Rio de Janeiro, RJ, 20921-400 (Brazil); Landau, S.J., E-mail: holanda@uepb.edu.br, E-mail: viniciusbusti@gmail.com, E-mail: colacolrc@gmail.com, E-mail: alcaniz@on.br, E-mail: slandau@df.uba.ar [Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Viamonte, Buenos Aires, 1053 Argentina (Argentina)

    2016-08-01

    As is well known, measurements of the Sunyaev-Zeldovich effect can be combined with observations of the X-ray surface brightness of galaxy clusters to estimate the angular diameter distance to these structures. In this paper, we show that this technique depends on the fine structure constant, α. Therefore, if α is a time-dependent quantity, e.g., α = α{sub 0}φ( z ), where φ is a function of redshift, we argue that current data do not provide the real angular diameter distance, D {sub A}( z ), to the cluster, but instead D {sub A}{sup data}( z ) = φ( z ){sup 2} D {sub A}( z ). We use this result to derive constraints on a possible variation of α for a class of dilaton runaway models considering a sample of 25 measurements of D {sub A}{sup data}( z ) in redshift range 0.023 < z < 0.784 and estimates of D {sub A}( z ) from current type Ia supernovae observations. We find no significant indication of variation of α with the present data.

  17. Chromospheric counterparts of solar transition region unresolved fine structure loops

    Science.gov (United States)

    Pereira, Tiago M. D.; Rouppe van der Voort, Luc; Hansteen, Viggo H.; De Pontieu, Bart

    2018-04-01

    Low-lying loops have been discovered at the solar limb in transition region temperatures by the Interface Region Imaging Spectrograph (IRIS). They do not appear to reach coronal temperatures, and it has been suggested that they are the long-predicted unresolved fine structures (UFS). These loops are dynamic and believed to be visible during both heating and cooling phases. Making use of coordinated observations between IRIS and the Swedish 1-m Solar Telescope, we study how these loops impact the solar chromosphere. We show for the first time that there is indeed a chromospheric signal of these loops, seen mostly in the form of strong Doppler shifts and a conspicuous lack of chromospheric heating. In addition, we find that several instances have a inverse Y-shaped jet just above the loop, suggesting that magnetic reconnection is driving these events. Our observations add several puzzling details to the current knowledge of these newly discovered structures; this new information must be considered in theoretical models. Two movies associated to Fig. 1 are available at http://https://www.aanda.org

  18. Distortion product otoacoustic emission fine structure as an early hearing loss predictor

    DEFF Research Database (Denmark)

    Reuter, Karen; Hammershøi, Dorte

    2006-01-01

    height, and ripple prevalence. Temporary changes of the DPOAE fine structure are analyzed by measuring DPOAE both before and after exposing some of the subjects to an intense sound. The characteristic patterns of fine structure can be found in the DPOAE of all subjects, though they are individual...... fine structures are obtained from 74 normal-hearing humans using primary levels of L1/L2=65/45 dB. The subjects belong to groups with different ages and exposure histories. A classification algorithm is developed, which quantifies the fine structure by the parameter's ripple place, ripple width, ripple...

  19. Ordinary mode auroral kilometric radiation fine structure observed by DE 1

    International Nuclear Information System (INIS)

    Benson, R.F.; Mellott, M.M.; Huff, R.L.; Gurnett, D.A.

    1988-01-01

    The fine structure observed with intense right-hand extraordinary (R-X) mode auroral kilometric radiation (AKR) has received major theoretical attention. Data from the Dynamics Explorer 1 plasma wave instrument indicate that left-hand ordinary (L-O) mode AKR posses similar fine structure. Several theories have been proposed to explain the fine structure of the R-X mode AKR. In order to account for the L-O mode fine structure, these theories will have to be modified to produce the L-O mode directly or will have to rely on mode conversion processes from the R-X to the L-O mode

  20. Exciton fine structure in CdSe nanoclusters

    International Nuclear Information System (INIS)

    Leung, K.; Pokrant, S.; Whaley, K.B.

    1998-01-01

    The fine structure in the CdSe nanocrystal absorption spectrum is computed by incorporating two-particle electron-hole interactions and spin-orbit coupling into a tight-binding model, with an expansion in electron-hole single-particle states. The exchange interaction and spin-orbit coupling give rise to dark, low-lying states that are predominantly triplet in character, as well as to a manifold of exciton states that are sensitive to the nanocrystal shape. Near the band gap, the exciton degeneracies are in qualitative agreement with the effective mass approximation (EMA). However, instead of the infinite lifetimes for dark states characteristic of the EMA, we obtain finite radiative lifetimes for the dark states. In particular, for the lowest, predominantly triplet, states we obtain radiative lifetimes of microseconds, in qualitative agreement with the experimental measured lifetimes. The resonant Stokes shifts obtained from the splitting between the lowest dark and bright states are also in good agreement with experimental values for larger crystallites. Higher-lying states exhibit significantly more complex behavior than predicted by EMA, due to extensive mixing of electron-hole pair states. copyright 1998 The American Physical Society

  1. Fine-structure constant: Is it really a constant

    International Nuclear Information System (INIS)

    Bekenstein, J.D.

    1982-01-01

    It is often claimed that the fine-structure ''constant'' α is shown to be strictly constant in time by a variety of astronomical and geophysical results. These constrain its fractional rate of change alpha-dot/α to at least some orders of magnitude below the Hubble rate H 0 . We argue that the conclusion is not as straightforward as claimed since there are good physical reasons to expect alpha-dot/α 0 . We propose to decide the issue by constructing a framework for a variability based on very general assumptions: covariance, gauge invariance, causality, and time-reversal invariance of electromagnetism, as well as the idea that the Planck-Wheeler length (10 -33 cm) is the shortest scale allowable in any theory. The framework endows α with well-defined dynamics, and entails a modification of Maxwell electrodynamics. It proves very difficult to rule it out with purely electromagnetic experiments. In a cosmological setting, the framework predicts an alpha-dot/α which can be compatible with the astronomical constraints; hence, these are too insensitive to rule out α variability. There is marginal conflict with the geophysical constraints: however, no firm decision is possible because of uncertainty about various cosmological parameters. By contrast the framework's predictions for spatial gradients of α are in fatal conflict with the results of the Eoetvoes-Dicke-Braginsky experiments. Hence these tests of the equivalence principle rule out with confidence spacetime variability of α at any level

  2. Feature Extraction for Structural Dynamics Model Validation

    Energy Technology Data Exchange (ETDEWEB)

    Farrar, Charles [Los Alamos National Laboratory; Nishio, Mayuko [Yokohama University; Hemez, Francois [Los Alamos National Laboratory; Stull, Chris [Los Alamos National Laboratory; Park, Gyuhae [Chonnam Univesity; Cornwell, Phil [Rose-Hulman Institute of Technology; Figueiredo, Eloi [Universidade Lusófona; Luscher, D. J. [Los Alamos National Laboratory; Worden, Keith [University of Sheffield

    2016-01-13

    As structural dynamics becomes increasingly non-modal, stochastic and nonlinear, finite element model-updating technology must adopt the broader notions of model validation and uncertainty quantification. For example, particular re-sampling procedures must be implemented to propagate uncertainty through a forward calculation, and non-modal features must be defined to analyze nonlinear data sets. The latter topic is the focus of this report, but first, some more general comments regarding the concept of model validation will be discussed.

  3. On the fine structure of the Vavilov-Cherenkov radiation

    International Nuclear Information System (INIS)

    Afanas'ev, G.N.; Kartavenko, V.G.; Zrelov, V.P.

    2003-01-01

    The aim of this paper is to study the fine structure of the Cherenkov rings. We analyze Zrelov's experiments in which the Cherenkov radiation was detected without using the special focusing devices. The broad Cherenkov ring was observed in the plane perpendicular to the motion axis. Using the exact and approximate formulae, we investigate how a charge uniformly moving in a medium radiates in a finite space interval. The formulae obtained describe the radiation intensity in the whole space interval, inside and outside the Cherenkov ring. In the plane perpendicular to the motion axis, the radiation fills mainly the finite ring. Its width, proportional to the motion interval, and the energy released in this ring do not depend on the position of the observation plane. Outside the Cherenkov ring, the radiation intensity suddenly drops. Inside it, the radiation intensity exhibits small oscillations which are due to the interference of the Vavilov-Cherenkov radiation and bremsstrahlung. The increase in the radiation intensity at the ends of the Cherenkov ring is associated with the shock waves arising at the beginning and the end of the charge motion and at the moments when the charge velocity coincides with the light velocity in a medium. For the chosen motion interval, the well-known Tamm formula does not describe the radiation intensity inside the Cherenkov ring for any position of the observation plane. Outside the Cherenkov ring, the Tamm formula is valid only at very large observation distances. Theoretical calculations are in satisfactory agreement with experimental data. Thus, the combined experimental and theoretical study of the unfocused Cherenkov rings allows one to obtain information on the physical processes accompanying the Cherenkov radiation (bremsstrahlung, transition of the light velocity barrier, etc.)

  4. [The role of temporal fine structure in tone recognition and music perception].

    Science.gov (United States)

    Zhou, Q; Gu, X; Liu, B

    2017-11-07

    The sound signal can be decomposed into temporal envelope and temporal fine structure information. The temporal envelope information is crucial for speech perception in quiet environment, and the temporal fine structure information plays an important role in speech perception in noise, Mandarin tone recognition and music perception, especially the pitch and melody perception.

  5. A study of the fine structure, enzyme activities and pattern of 14CO2 ...

    African Journals Online (AJOL)

    A detailed study of selected grasses has been made with respect to fine structures characteristics, enzyme activities associated with C-4 and C-3 pathway photosynthesis, and short term carbon dioxide-14 incorporation experiments. A good correlation was obtained between the fine structure, the carbon pathway and the ...

  6. METHODS OF RECEIVING OF FINE-GRAINED STRUCTURE OF CASTINGS AT CRYSTALLIZATION

    Directory of Open Access Journals (Sweden)

    N. K. Tolochko

    2012-01-01

    Full Text Available The article deals with methods for fine-grained structure of ingots during crystallization depending on the used foundry technologies. It is shown that by using modern scientific and technological advances may improve the traditional and the development of new casting processes, providing production of cast parts with over fine-grained structure and enhanced properties.

  7. Coupling Fine-Scale Root and Canopy Structure Using Ground-Based Remote Sensing

    Directory of Open Access Journals (Sweden)

    Brady S. Hardiman

    2017-02-01

    Full Text Available Ecosystem physical structure, defined by the quantity and spatial distribution of biomass, influences a range of ecosystem functions. Remote sensing tools permit the non-destructive characterization of canopy and root features, potentially providing opportunities to link above- and belowground structure at fine spatial resolution in functionally meaningful ways. To test this possibility, we employed ground-based portable canopy LiDAR (PCL and ground penetrating radar (GPR along co-located transects in forested sites spanning multiple stages of ecosystem development and, consequently, of structural complexity. We examined canopy and root structural data for coherence (i.e., correlation in the frequency of spatial variation at multiple spatial scales ≤10 m within each site using wavelet analysis. Forest sites varied substantially in vertical canopy and root structure, with leaf area index and root mass more becoming even vertically as forests aged. In all sites, above- and belowground structure, characterized as mean maximum canopy height and root mass, exhibited significant coherence at a scale of 3.5–4 m, and results suggest that the scale of coherence may increase with stand age. Our findings demonstrate that canopy and root structure are linked at characteristic spatial scales, which provides the basis to optimize scales of observation. Our study highlights the potential, and limitations, for fusing LiDAR and radar technologies to quantitatively couple above- and belowground ecosystem structure.

  8. Simple surface structure determination from Fourier transforms of angle-resolved photoemission extended fine structure

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Y. [Pennsylvania State Univ., University Park, PA (United States)]|[Lawrence Berkeley Lab., CA (United States); Shirley, D.A. [Pennsylvania State Univ., University Park, PA (United States)

    1995-02-01

    The authors show by Fourier analyses of experimental data, with no further treatment, that the positions of all the strong peaks in Fourier transforms of angle-resolved photoemission extended fine structure (ARPEFS) from adsorbed surfaces can be explicitly predicted from a trial structure with an accuracy of about {+-} 0.3 {angstrom} based on a single-scattering cluster model together with the concept of a strong backscattering cone, and without any additional analysis. This characteristic of ARPEFS Fourier transforms can be developed as a simple method for determining the structures of adsorbed surfaces to an accuracy of about {+-} 0.1 {angstrom}.

  9. X-ray absorption fine structure (XAFS) spectroscopy: a tool for structural studies in material sciences (abstract)

    International Nuclear Information System (INIS)

    Akhtar, M.J.

    2011-01-01

    XAFS spectroscopy has revealed itself as a powerful technique for structural characterization of the local atomic environment of individual atomic species, including bond distances, coordination numbers and type of nearest neighbors surrounding the central atom. This technique is particularly useful for materials that show considerable structural and chemical disorder. XAFS spectroscopy has found extensive applications in determining the local atomic and electronic structure of the absorbing centers (atoms) in the materials science, physics, chemistry, biology and geophysics. X-ray absorption edges contain a variety of information on the chemical state and the local structure of the absorbing atom. On the higher energy side of an absorption edge fine structure is observed due to backscattering of the emitted photoelectron. The post-edge region can be divided into two parts. The X-ray Absorption Near Edge Structure (XANES) which extends up to 50 eV of an absorption edge, the spectrum is interpreted in terms of the appropriate components of the local density of states, which would be expected to be sensitive to the valence state of the atom. The intensity, shape and location of the absorption edge features provide information on the valence state, electronic structure and coordination geometry of the absorbing atom.The Extended X-ray Absorption Fine Structure (EXAFS) region is dominated by the single scattering processes and extends up to 1000 eV above the edge and provides information on the radial distribution (coordination number, radial distance and type of neighboring atoms) around the central atom. The results on perovskite based and spinel ferrites systems will be presented, where valence state and cation distributions are determined; the present study will show focus on SrFeO/sub 3/, MnFe/sub 2/O/sub 4/ and Zn/sub 1-x/Ni/sub x/Fe/sub 2/O/sub 4/ materials. (author)

  10. Fine structure and development of the collar enamel in gars, Lepisosteus oculatus, Actinopterygii

    Science.gov (United States)

    Sasagawa, Ichiro; Ishiyama, Mikio; Yokosuka, Hiroyuki; Mikami, Masato

    2008-06-01

    The fine structure of collar enamel and the cells constituting the enamel organ during amelogenesis in Lepisosteus oculatus was observed by light, scanning electron and transmission electron microscopy. In the enamel, slender crystals were arranged perpendicular to the surface and the stripes that were parallel to the surface were observed, suggesting that the enamel in Lepisosteus shares common morphological features with that in sarcopterygian fish and amphibians. Ameloblasts containing developed Golgi apparatus, rough endoplasmic reticulum (rER) and secretory granules were found in the secretory stage. In the maturation stage, a ruffled border was not seen at the distal end of the ameloblasts, while many mitochondria and lysosome-like granules were obvious in the distal cytoplasm. The enamel organ consisted of the outer dental epithelial cells, stratum reticulum cells and ameloblasts, but there was no stratum intermedium. It is likely that the ameloblasts have less absorptive function in comparison with the inner dental epithelial cells facing cap enameloid.

  11. Fine structure and optical properties of biological polarizers in crustaceans and cephalopods

    Science.gov (United States)

    Chiou, Tsyr-Huei; Caldwell, Roy L.; Hanlon, Roger T.; Cronin, Thomas W.

    2008-04-01

    The lighting of the underwater environment is constantly changing due to attenuation by water, scattering by suspended particles, as well as the refraction and reflection caused by the surface waves. These factors pose a great challenge for marine animals which communicate through visual signals, especially those based on color. To escape this problem, certain cephalopod mollusks and stomatopod crustaceans utilize the polarization properties of light. While the mechanisms behind the polarization vision of these two animal groups are similar, several distinctive types of polarizers (i.e. the structure producing the signal) have been found in these animals. To gain a better knowledge of how these polarizers function, we studied the relationships between fine structures and optical properties of four types of polarizers found in cephalopods and stomatopods. Although all the polarizers share a somewhat similar spectral range, around 450- 550 nm, the reflectance properties of the signals and the mechanisms used to produce them have dramatic differences. In cephalopods, stack-plates polarizers produce the polarization patterns found on the arms and around their eyes. In stomatopods, we have found one type of beam-splitting polarizer based on photonic structures and two absorptive polarizer types based on dichroic molecules. These stomatopod polarizers may be found on various appendages, and on the cuticle covering dorsal or lateral sides of the animal. Since the efficiencies of all these polarizer types are somewhat sensitive to the change of illumination and viewing angle, how these animals compensate with different behaviors or fine structural features of the polarizer also varies.

  12. Complementary information on CdSe/ZnSe quantum dot local structure from extended X-ray absorption fine structure and diffraction anomalous fine structure measurements

    International Nuclear Information System (INIS)

    Piskorska-Hommel, E.; Holý, V.; Caha, O.; Wolska, A.; Gust, A.; Kruse, C.; Kröncke, H.; Falta, J.; Hommel, D.

    2012-01-01

    The extended X-ray absorption fine structure (EXAFS) and diffraction anomalous fine structure (DAFS) have been applied to investigate a local structure for the CdSe/ZnSe quantum dots grown by molecular beam epitaxy (MBE) and migration-enhanced epitaxy (MEE). The aim was to study the intermixing of Cd and Zn atoms, chemical compositions and strain induced by cap-layer. The EXAFS at the Cd K-edge and DAFS at the Se K-edge proved the intermixing of Cd and Zn atoms. The distances Cd–Se (2.61 Å) found from EXAFS and DAFS analysis for h 1 region is closer to that in bulk CdSe (2.62 Å). The DAFS analysis revealed the differences in the local structure in two investigated regions (i.e. different iso-strain volumes) on the quantum dots. It was found that the investigated areas differ in the Cd concentration. To explain the experimental results the theoretical calculation based on a full valence-force field (VFF) model was performed. The theoretical VFF model fully explains the experimental data.

  13. Structural features that optimize high temperature superconductivity

    International Nuclear Information System (INIS)

    Jorgensen, J.D.; Argonne Nat. Lab., IL; Hinks, D.G.; Argonne Nat. Lab., IL; Chmaissem, O.; Argonne Nat. Lab., IL; Argyriou, D.N.; Argonne Nat. Lab., IL; Mitchell, J.F.; Argonne Nat. Lab., IL; Dabrowski, B.

    1996-01-01

    Studies of a large number of compounds have provided a consistent picture of what structural features give rise to the highest T c 's in copper-oxide superconductors. For example, various defects can be introduced into the blocking layer to provide the optimum carrier concentration, but defects that form in or adjacent to the CuO 2 layers will lower T c and eventually destroy superconductivity. After these requirements are satisfied, the highest T c 's are observed for compounds (such as the HgBa 2 Ca n-1 Cu n O 2n+2+x family) that have flat and square CuO 2 planes and long apical Cu-O bonds. This conclusion is confirmed by the study of materials in which the flatness of the CuO 2 plane can be varied in a systematic way. In more recent work, attention has focused on how the structure can be modified, for example, by chemical substitution, to improve flux pinning properties. Two strategies are being investigated: (1) Increasing the coupling of pancake vortices to form vortex lines by shortening or ''metallizing'' the blocking layer; and (2) the formation of defects that pin flux. (orig.)

  14. Fine structure and spectral index measurements in natural uranium - graphite lattices; Mesures fines dans des reseaux a graphite

    Energy Technology Data Exchange (ETDEWEB)

    Cogne, F; Journet, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    The experiments described in this report have been carried out for the most part in the critical facility MARIUS, and a few during the start up of the EDF-1 power reactor. The first part deals with the fine structure measurements made in various lattices and with their analysis. Integration over the neutron spectrum of the mono-kinetic disadvantage factor derived by the A.B.H method yields results in good agreement with the experiments. The second part deals with spectral indexes measurements (Pu/U, In/Mn) made at room temperature in MARIUS. Comparison are made of experiments with calculations using various thermalization models. Experiments carried out at higher temperatures in EDF-1 are also described. (authors) [French] Les mesures decrites dans ce rapport ont ete faites pour la plupart dans l'empilement critique MARIUS sur des reseaux a graphite-uranium naturel. Une premiere partie traite des mesures de structure fine faites dans differents reseaux et de leur interpretation. On montre en particulier qu'une integration sur le spectre d'un calcul monocinetique type A.B.H. rend bien compte des experiences. Dans une deuxieme partie, on donne les resultats de mesures d'indices de spectre Pu/U et In/Mn faites sur des reseaux froids a MARIUS et leur comparaison avec les differents modeles de calculs de thermalisation. On donne egalement les resultats de quelques mesures en temperature effectuees lors du demarrage du reacteur EDF-1. (auteurs)

  15. The influence of common stimulus parameters on distortion product otoacoustic emission fine structure.

    Science.gov (United States)

    Johnson, Tiffany A; Baranowski, Lauren G

    2012-01-01

    To determine whether common approaches to setting stimulus parameters influence the depth of fine structure present in the distortion product otoacoustic emission (DPOAE) response. Because the presence of fine structure has been suggested as a possible source of errors, if one of the common parametric approaches results in reduced fine-structure depth, it may be preferred over other approaches. DPOAE responses were recorded in a group of 21 subjects with normal hearing for 1/3-octave intervals surrounding 3 f2s (1, 2, and 4 kHz) at three L2s (30, 45, and 55 dB SPL). For each f2 and L2 combination, L1 and f2/f1 were set according to three commonly used parametric approaches. These included a simple approach, the approach recommended by Kummer et al., and the approach described by Johnson et al. These three approaches primarily differ in the recommended relationship between L1 and L2. For each parametric approach, DPOAE fine structure was evaluated by varying f2 in small steps. Differences in DPOAE level and DPOAE fine-structure depth across f2, L2, and the various stimulus parameters were evaluated using repeated-measures analysis of variance. As expected, significant variations in DPOAE level were observed across the three parametric approaches. For stimulus levels #45 dB SPL, the simple stimuli resulted in lower DPOAE levels than were observed for other approaches. An unexpected finding was that stimulus parameters developed by Johnson et al., which were believed to produce higher DPOAE levels than other approaches, produced the lowest DPOAE levels of the three approaches when f2 = 4 kHz. Significant differences in fine-structure depth were also observed. Greater fine-structure depth was observed with the simple parameters, although this effect was restricted to L2 # 45 dB SPL. When L2 = 55 dB SPL, all three parametric approaches resulted in equivalent fine-structure depth. A significant difference in fine-structure depth across the 3 f2s was also observed. The

  16. Distinctive features of high-ash bituminuos coals combution with low milling fineness in furnace chambers with bottom blowing

    Science.gov (United States)

    Zroychikov, N. A.; Kaverin, A. A.; Biryukov, Ya A.

    2017-11-01

    Nowadays the problem of improvement of pulverized coal combustion schemes is an actual one for national power engineering, especially for combustion of coals with low milling fineness with significant portion of moisture or mineral impurities. In this case a big portion of inert material in the fuel may cause impairment of its ignition and combustion. In addition there are a lot of boiler installations on which nitrogen oxides emission exceeds standard values significantly. Decreasing of milling fineness is not without interest as a way of lowering an electric energy consumption for pulverization, which can reach 30% of power plant’s auxiliary consumption of electricity. Development of a combustion scheme meeting the requirements both for effective coal burning and environmental measures (related to NOx emission) is a complex task and demands compromising between these two factors, because implementation of NOx control by combustion very often leads to rising of carbon-in-ash loss. However widespread occurrence of such modern research technique as computer modeling allows to conduct big amount of variants calculations of combustion schemes with low cost and find an optimum. This paper presents results of numerical research of combined schemes of coal combustion with high portion of inert material based on straight-flow burners and nozzles. Several distinctive features of furnace aerodynamics, heat transfer and combustion has been found. The combined scheme of high-ash bituminouos coals combustion with low milling fineness, which allows effective combustion of pointed type of fuels with nitrogen oxides emission reduction has been proposed.

  17. Directional fine structure in absorption of white x rays: A tomographic interpretation

    International Nuclear Information System (INIS)

    Korecki, P.; Szymonski, M.; Tolkiehn, M.; Novikov, D. V.; Materlik, G.

    2006-01-01

    We discuss directional fine structure in absorption of white x rays for tomographic imaging of crystal structure at the atomic level. The interference between a direct x-ray beam and the secondary waves coherently scattered inside a specimen modifies the total wave field at the position of the absorbing atoms. For a white x-ray beam, the wave field variations cancel out by energy integration for all directions, except for the near forward scattering components, coinciding with the incident beam. Therefore, two-dimensional patterns of the angular-dependent fine structure in absorption of white x rays can be interpreted as real-space projections of atomic structure. In this work, we present a theory describing the directional fine structure in white x-ray absorption and a tomographic approach for crystal structure retrieval developed on its basis. The tomographic algorithm is applied to the experimental x-ray absorption data recorded for GaP crystals

  18. Production of fine structures in type III solar radio bursts due to turbulent density profiles

    International Nuclear Information System (INIS)

    Loi, Shyeh Tjing; Cairns, Iver H.; Li, Bo

    2014-01-01

    Magnetic reconnection events in the corona release energetic electron beams along open field lines, and the beams generate radio emission at multiples of the electron plasma frequency f p to produce type III solar radio bursts. Type III bursts often exhibit irregularities in the form of flux modulations with frequency and/or local temporal advances and delays, and a type IIIb burst represents the extreme case where a type III burst is fragmented into a chain of narrowband features called striae. Remote and in situ spacecraft measurements have shown that density turbulence is ubiquitous in the corona and solar wind, and often exhibits a Kolmogorov power spectrum. In this work, we numerically investigate the effects of one-dimensional macroscopic density turbulence (along the beam direction) on the behavior of type III bursts, and find that this turbulence produces stria-like fine structures in the dynamic spectra of both f p and 2 f p radiation. Spectral and temporal fine structures in the predicted type III emission are produced by variations in the scattering path lengths and group speeds of radio emission, and in the locations and sizes of emitting volumes. Moderate turbulence levels yield flux enhancements with much broader half-power bandwidths in f p than 2 f p emission, possibly explaining the often observed type IIIb-III harmonic pairs as being where intensifications in 2 f p radiation are not resolved observationally. Larger turbulence levels producing trough-peak regions in the plasma density profile may lead to broader, resolvable intensifications in 2 f p radiation, which may account for the type IIIb-IIIb pairs that are sometimes observed.

  19. Investigation on the fine structure of sea-breeze during ESCOMPTE experiment

    Science.gov (United States)

    Puygrenier, V.; Lohou, F.; Campistron, B.; Saïd, F.; Pigeon, G.; Bénech, B.; Serça, D.

    2005-03-01

    Surface and remote-sensing instruments deployed during ESCOMPTE experiment over the Marseille area, along the Mediterranean coast, were used to investigate the fine structure of the atmospheric boundary layer (ABL) during sea-breeze circulation in relation to pollutant transport and diffusion. Six sea-breeze events are analyzed with a particular focus on 25 June 2001. Advection of cool and humid marine air over land has a profound influence on the daytime ABL characteristics. This impact decreases rapidly with the inland distance from the sea. Nearby the coast (3 km inland), the mixing height Zi rises up to 750 m and falls down after 15:00 (UT) when the breeze flow reaches its maximum intensity. A more classical evolution of the ABL is observed at only 11-km inland where Zi culminates in the morning and stabilizes in the afternoon at about 1000 m height. Fine inspection of the data revealed an oscillation of the sea-breeze with a period about 2 h 47 min. This feature, clearly discernable for 3 days at least, is present in several atmospheric variables such as wind, temperature, not only at the ground but also aloft in the ABL as observed by sodar/RASS and UHF wind profilers. In particular, the mixing height Zi deduced from UHF profilers observations is affected also by the same periodicity. This pulsated sea-breeze is observed principally above Marseille and, at the northern and eastern shores of the Berre pond. In summary, the periodic intrusion over land of cool marine air modifies the structure of the ABL in the vicinity of the coast from the point of view of stability, turbulent motions and pollutants concentration. An explanation of the source of this pulsated sea-breeze is suggested.

  20. Fine-tuning structural RNA alignments in the twilight zone

    Directory of Open Access Journals (Sweden)

    Schirmer Stefanie

    2010-04-01

    Full Text Available Abstract Background A widely used method to find conserved secondary structure in RNA is to first construct a multiple sequence alignment, and then fold the alignment, optimizing a score based on thermodynamics and covariance. This method works best around 75% sequence similarity. However, in a "twilight zone" below 55% similarity, the sequence alignment tends to obscure the covariance signal used in the second phase. Therefore, while the overall shape of the consensus structure may still be found, the degree of conservation cannot be estimated reliably. Results Based on a combination of available methods, we present a method named planACstar for improving structure conservation in structural alignments in the twilight zone. After constructing a consensus structure by alignment folding, planACstar abandons the original sequence alignment, refolds the sequences individually, but consistent with the consensus, aligns the structures, irrespective of sequence, by a pure structure alignment method, and derives an improved sequence alignment from the alignment of structures, to be re-submitted to alignment folding, etc.. This circle may be iterated as long as structural conservation improves, but normally, one step suffices. Conclusions Employing the tools ClustalW, RNAalifold, and RNAforester, we find that for sequences with 30-55% sequence identity, structural conservation can be improved by 10% on average, with a large variation, measured in terms of RNAalifold's own criterion, the structure conservation index.

  1. Interfacial Energy and Fine Defect Structures for Incoherent Films

    OpenAIRE

    Cermelli, Paolo; Gurtin, Morton E.; Leoni, Giovanni

    1999-01-01

    This note summarizes recent results in which modern techniques of the calculus of variations are used to obtain qualitative features of film-substrate interfaces for a broad class of interfacial energies. In particular, we show that the existence of a critical thickness for incoherency and the formation of interfacial dislocations depend strongly on the convexity and smoothness of the interfacial energy function.

  2. Size and Ultrasound Features Affecting Results of Ultrasound-Guided Fine-Needle Aspiration of Thyroid Nodules.

    Science.gov (United States)

    Dong, YiJie; Mao, MinJing; Zhan, WeiWei; Zhou, JianQiao; Zhou, Wei; Yao, JieJie; Hu, YunYun; Wang, Yan; Ye, TingJun

    2017-11-09

    Our goal was to assess the diagnostic efficacy of ultrasound (US)-guided fine-needle aspiration (FNA) of thyroid nodules according to size and US features. A retrospective correlation was made with 1745 whole thyroidectomy and hemithyroidectomy specimens with preoperative US-guided FNA results. All cases were divided into 5 groups according to nodule size (≤5, 5.1-10, 10.1-15, 15.1-20, and >20 mm). For target nodules, static images and cine clips of conventional US and color Doppler were obtained. Ultrasound images were reviewed and evaluated by two radiologists with at least 5 years US working experience without knowing the results of pathology, and then agreement was achieved. The Bethesda category I rate was higher in nodules larger than 15 mm (P 20 mm) with several US features tended to yield false-negative FNA results. © 2017 by the American Institute of Ultrasound in Medicine.

  3. The electronic fine structure of 4-nitrophenyl functionalized single-walled carbon nanotubes

    International Nuclear Information System (INIS)

    Chakraborty, Amit K; Coleman, Karl S; Dhanak, Vinod R

    2009-01-01

    Controlling the electronic structure of carbon nanotubes (CNTs) is of great importance to various CNT based applications. Herein the electronic fine structure of single-walled carbon nanotube films modified with 4-nitrophenyl groups, produced following reaction with 4-nitrobenzenediazonium tetrafluoroborate, was investigated for the first time. Various techniques such as x-ray and ultra-violet photoelectron spectroscopy, and near edge x-ray absorption fine structure studies were used to explore the electronic structure, and the results were compared with the measured electrical resistances. A reduction in number of the π electronic states in the valence band consistent with the increased resistance of the functionalized nanotube films was observed.

  4. 2fl-f2 DPOAE fine structure for 12 symphony orchestra musicians before and after rehearsal

    DEFF Research Database (Denmark)

    Reuter, Karen; Hammershøi, Dorte

    2005-01-01

    The distortion product otoacoustic emission (DPOAE) fine structure is revealed, when measuring DPOAE with a very fine frequency resolution. It is characterized by consistent maxima and minima with notches of up to 20 dB depth. The fine structure is known also from absolute hearing thresholds...

  5. Fine- and hyperfine-structure effects in molecular photoionization. I. General theory and direct photoionization

    Energy Technology Data Exchange (ETDEWEB)

    Germann, Matthias; Willitsch, Stefan, E-mail: stefan.willitsch@unibas.ch [Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel (Switzerland)

    2016-07-28

    We develop a model for predicting fine- and hyperfine intensities in the direct photoionization of molecules based on the separability of electron and nuclear spin states from vibrational-electronic states. Using spherical tensor algebra, we derive highly symmetrized forms of the squared photoionization dipole matrix elements from which we derive the salient selection and propensity rules for fine- and hyperfine resolved photoionizing transitions. Our theoretical results are validated by the analysis of the fine-structure resolved photoelectron spectrum of O{sub 2} reported by Palm and Merkt [Phys. Rev. Lett. 81, 1385 (1998)] and are used for predicting hyperfine populations of molecular ions produced by photoionization.

  6. Fine- and hyperfine-structure effects in molecular photoionization. I. General theory and direct photoionization.

    Science.gov (United States)

    Germann, Matthias; Willitsch, Stefan

    2016-07-28

    We develop a model for predicting fine- and hyperfine intensities in the direct photoionization of molecules based on the separability of electron and nuclear spin states from vibrational-electronic states. Using spherical tensor algebra, we derive highly symmetrized forms of the squared photoionization dipole matrix elements from which we derive the salient selection and propensity rules for fine- and hyperfine resolved photoionizing transitions. Our theoretical results are validated by the analysis of the fine-structure resolved photoelectron spectrum of O2 reported by Palm and Merkt [Phys. Rev. Lett. 81, 1385 (1998)] and are used for predicting hyperfine populations of molecular ions produced by photoionization.

  7. Fine tuning of transmission features in nanoporous anodic alumina distributed Bragg reflectors

    Science.gov (United States)

    Lim, Siew Yee; Law, Cheryl Suwen; Santos, Abel

    2018-01-01

    This study introduces an innovative apodisation strategy to tune the filtering features of distributed Bragg reflectors based on nanoporous anodic alumina (NAA-DBRs). The effective medium of NAA-DBRs, which is modulated in a stepwise fashion by a pulse-like anodisation approach, is apodised following a logarithmic negative function to engineer the transmission features of NAA-DBRs. We investigate the effect of various apodisation parameters such as apodisation amplitude difference, anodisation period, current density offset and pore widening time, to tune and optimise the optical properties of NAA-DBRs in terms of central wavelength position, full width at half maximum and quality of photonic stop band. The transmission features of NAA-DBRs are shown to be fully controllable with precision across the spectral regions by means of the apodisation parameters. Our study demonstrates that an apodisation strategy can significantly narrow the width and enhance the quality of the characteristic photonic stop band of NAA-DBRs. This rationally designed anodisation approach based on the combination of apodisation and stepwise pulse anodisation enables the development of optical filters with tuneable filtering features to be integrated into optical technologies acting as essential photonic elements in devices such as optical sensors and biosensors.

  8. Pulsed EM Field Response of a Thin, High-Contrast, Finely Layered Structure With Dielectric and Conductive Properties

    NARCIS (Netherlands)

    De Hoop, A.T.; Jiang, L.

    2009-01-01

    The response of a thin, high-contrast, finely layered structure with dielectric and conductive properties to an incident, pulsed, electromagnetic field is investigated theoretically. The fine layering causes the standard spatial discretization techniques to solve Maxwell's equations numerically to

  9. Applications of random forest feature selection for fine-scale genetic population assignment.

    Science.gov (United States)

    Sylvester, Emma V A; Bentzen, Paul; Bradbury, Ian R; Clément, Marie; Pearce, Jon; Horne, John; Beiko, Robert G

    2018-02-01

    Genetic population assignment used to inform wildlife management and conservation efforts requires panels of highly informative genetic markers and sensitive assignment tests. We explored the utility of machine-learning algorithms (random forest, regularized random forest and guided regularized random forest) compared with F ST ranking for selection of single nucleotide polymorphisms (SNP) for fine-scale population assignment. We applied these methods to an unpublished SNP data set for Atlantic salmon ( Salmo salar ) and a published SNP data set for Alaskan Chinook salmon ( Oncorhynchus tshawytscha ). In each species, we identified the minimum panel size required to obtain a self-assignment accuracy of at least 90% using each method to create panels of 50-700 markers Panels of SNPs identified using random forest-based methods performed up to 7.8 and 11.2 percentage points better than F ST -selected panels of similar size for the Atlantic salmon and Chinook salmon data, respectively. Self-assignment accuracy ≥90% was obtained with panels of 670 and 384 SNPs for each data set, respectively, a level of accuracy never reached for these species using F ST -selected panels. Our results demonstrate a role for machine-learning approaches in marker selection across large genomic data sets to improve assignment for management and conservation of exploited populations.

  10. Structure analysis of InN film using extended X-ray absorption fine structure method

    Energy Technology Data Exchange (ETDEWEB)

    Miyajima, T.; Kobayashi, T.; Hirata, S. [Core Technology Development Center, Core Technology and Network Company, Sony Corporation, 4-14-1 Asahi-cho, Atsugi, Kanagawa 243-0014 (Japan); Kudo, Y.; Liu, K.L. [Technology Solutions Center, Sony Corporation, 4-16-1 Okata, Atsugi, Kanagawa 243-0021 (Japan); Uruga, T.; Honma, T. [Japan Synchrotron Radiation Research Institute, Mikazuki-cho, Hyogo 679-5198 (Japan); Saito, Y.; Hori, M.; Nanishi, Y. [Department of Photonics, Ritsumeikan University, 1-1-1 Noji-Higashi, Kusatsu, Shiga 525-8577 (Japan)

    2002-12-01

    We investigated the local atomic structure around In atoms of MBE-grown InN which has a direct bandgap energy of 0.8 eV, using extended X-ray absorption fine structure (EXAFS) oscillation of In K-edge. The signals from the first-nearest neighbor atoms (N) and second-nearest atoms (In) from In atoms were clearly observed and the atomic bond length of In-N and In-In was estimated to be d{sub In-N}=0.215 nm and d{sub In-In}=0.353 nm, respectively. The In-N bond length of d{sub In-In}=0.353 nm was closed to the a-axis lattice constant of a=0.3536 nm, which was determined using X-ray diffraction measurements. The obtained local atomic structure agreed with the calculated ideal structure. We conclude, therefore, that the InN film with a bandgap energy of 0.8 eV has a high structural symmetry in the range of a few A around In atoms. (Abstract Copyright [2002], Wiley Periodicals, Inc.)

  11. Structure analysis of InN film using extended X-ray absorption fine structure method

    International Nuclear Information System (INIS)

    Miyajima, T.; Kobayashi, T.; Hirata, S.; Kudo, Y.; Liu, K.L.; Uruga, T.; Honma, T.; Saito, Y.; Hori, M.; Nanishi, Y.

    2002-01-01

    We investigated the local atomic structure around In atoms of MBE-grown InN which has a direct bandgap energy of 0.8 eV, using extended X-ray absorption fine structure (EXAFS) oscillation of In K-edge. The signals from the first-nearest neighbor atoms (N) and second-nearest atoms (In) from In atoms were clearly observed and the atomic bond length of In-N and In-In was estimated to be d In-N =0.215 nm and d In-In =0.353 nm, respectively. The In-N bond length of d In-In =0.353 nm was closed to the a-axis lattice constant of a=0.3536 nm, which was determined using X-ray diffraction measurements. The obtained local atomic structure agreed with the calculated ideal structure. We conclude, therefore, that the InN film with a bandgap energy of 0.8 eV has a high structural symmetry in the range of a few A around In atoms. (Abstract Copyright [2002], Wiley Periodicals, Inc.)

  12. Simulations of fine structures on the zero field steps of Josephson tunnel junctions

    DEFF Research Database (Denmark)

    Scheuermann, M.; Chi, C. C.; Pedersen, Niels Falsig

    1986-01-01

    Fine structures on the zero field steps of long Josephson tunnel junctions are simulated for junctions with the bias current injected into the junction at the edges. These structures are due to the coupling between self-generated plasma oscillations and the traveling fluxon. The plasma oscillations...... are generated by the interaction of the bias current with the fluxon at the junction edges. On the first zero field step, the voltages of successive fine structures are given by Vn=[h-bar]/2e(2omegap/n), where n is an even integer. Applied Physics Letters is copyrighted by The American Institute of Physics....

  13. Observations of the birth and fine structure of sunspot penumbrae

    International Nuclear Information System (INIS)

    Collados, M.; Garcia de la Rosa, J.I.; Moreno-Insertis, F.; Vazquez, M.

    1985-01-01

    High resolution white-light pictures of sunspot penumbrae are presented. These include pictures showing details of their filamentary structure and some instances of birth of a penumbra. The observations are discussed in the framework of current penumbra theories. A series of pictures have been presented, which give additional evidence of the existence of dark penumbral filaments as individual structures. With respect to the birth of the penumbra some new observational aspects can be seen. The existence of the filamentary penumbra even in the first moments, its non uniformity and its short length are the major aspects derived from the pictures

  14. Fine Structure of a Laser-Plasma Filament in Air

    International Nuclear Information System (INIS)

    Eisenmann, Shmuel; Pukhov, Anatoly; Zigler, Arie

    2007-01-01

    The ability to select and stabilize a single filament during propagation of an ultrashort high-intensity laser pulse in air makes it possible to examine the longitudinal structure of the plasma channel left in its wake. We present detailed measurements of plasma density variations along laser propagation. Over the length of the filament, electron density variations of 3 orders of magnitude are measured. They display evidence of a meter-long postionization range, along which a self-guided structure is observed coupled with a low plasma density, corresponding to ∼3 orders of magnitude decrease from the peak density level

  15. Fine Structure of a Laser-Plasma Filament in Air

    Science.gov (United States)

    Eisenmann, Shmuel; Pukhov, Anatoly; Zigler, Arie

    2007-04-01

    The ability to select and stabilize a single filament during propagation of an ultrashort high-intensity laser pulse in air makes it possible to examine the longitudinal structure of the plasma channel left in its wake. We present detailed measurements of plasma density variations along laser propagation. Over the length of the filament, electron density variations of 3 orders of magnitude are measured. They display evidence of a meter-long postionization range, along which a self-guided structure is observed coupled with a low plasma density, corresponding to ˜3 orders of magnitude decrease from the peak density level.

  16. Fine structure of the amide i band in acetanilide

    Science.gov (United States)

    Careri, G.; Gratton, E.; Shyamsunder, E.

    1988-05-01

    Their absorption spectrum of both single crystals and powdered samples of acetanilide (a model system for proteins) has been studied in the amide i region, where a narrow band has been identified as a highly trapped soliton state. The powder-sample spectra have been decomposed using four Lorentzian bands. A strong temperature dependence has been found for the intensity of two of the subbands, which also show a complementary behavior. Polarization studies performed on thin crystals have shown that the subbands have the same polarization. Low-temperature spectra of partially deuterated samples show the presence of the subbands at the same absorption frequencies found using the fitting procedure in the spectra of nondeuterated samples. The soliton model currently proposed to explain the origin of the anomalous amide i component at 1650 cm-1 still holds, but some modification of the model is required to account for the new features revealed by this study.

  17. Fine structural dependence of ultraviolet reflections in the King Penguin beak horn.

    Science.gov (United States)

    Dresp, Birgitta; Langley, Keith

    2006-03-01

    The visual perception of many birds extends into the near-ultraviolet (UV) spectrum and ultraviolet is used by some to communicate. The beak horn of the King Penguin (Aptenodytes patagonicus) intensely reflects in the ultraviolet and this appears to be implicated in partner choice. In a preliminary study, we recently demonstrated that this ultraviolet reflectance has a structural basis, resulting from crystal-like photonic structures, capable of reflecting in the near-UV. The present study attempted to define the origin of the photonic elements that produce the UV reflectance and to better understand how the UV signal is optimized by their fine structure. Using light and electron microscopic analysis combined with new spectrophotometric data, we describe here in detail the fine structure of the entire King Penguin beak horn in addition to that of its photonic crystals. The data obtained reveal a one-dimensional structural periodicity within this tissue and demonstrate a direct relationship between its fine structure and its function. In addition, they suggest how the photonic structures are produced and how they are stabilized. The measured lattice dimensions of the photonic crystals, together with morphological data on its composition, permit predictions of the wavelength of reflected light. These correlate well with experimentally observed values. The way the UV signal is optimized by the fine structure of the beak tissue is discussed with regard to its putative biological role.

  18. Lack of sex-biased dispersal promotes fine-scale genetic structure in alpine ungulates

    Science.gov (United States)

    Gretchen H. Roffler; Sandra L. Talbot; Gordon Luikart; George K. Sage; Kristy L. Pilgrim; Layne G. Adams; Michael K. Schwartz

    2014-01-01

    Identifying patterns of fine-scale genetic structure in natural populations can advance understanding of critical ecological processes such as dispersal and gene flow across heterogeneous landscapes. Alpine ungulates generally exhibit high levels of genetic structure due to female philopatry and patchy configuration of mountain habitats. We assessed the spatial scale...

  19. Structural features in Ni-Al alloys

    International Nuclear Information System (INIS)

    Abylkalykova, R.B.; Kveglis, L.I.; Rakhimova, U.A.; Nasokhova, Sh.B.; Tazhibaeva, G.B.

    2007-01-01

    Purpose of the work is study of structural transformations under diverse memory effect in Ni-Al alloys. Examination were conducted in following composition samples: Ni -75 at.% and Al - 25 at.%. The work is devoted to clarification reasons both formation atom-ordered structures in inter-grain boundaries of bulk samples under temperature action and static load. Revealed inter-grain inter-boundary layers in Ni-Al alloy both bulk and surface state have complicated structure

  20. The role of temporal fine structure information for the low pitch of high-frequency complex tones

    DEFF Research Database (Denmark)

    Santurette, Sébastien; Dau, Torsten

    2011-01-01

    The fused low pitch evoked by complex tones containing only unresolved high-frequency components demonstrates the ability of the human auditory system to extract pitch using a temporal mechanism in the absence of spectral cues. However, the temporal features used by such a mechanism have been...... amplitude fluctuations, or temporal fine structure (TFS), of the conveyed signal can be processed. Using a pitch-matching paradigm, the present study found that the low pitch of inharmonic transposed tones with unresolved components was consistent with the timing between the most prominent TFS maxima...... coding as such, and that TFS representation might persist at higher frequencies than previously thought....

  1. Fine structure of dielectric function of cadmium fluoride

    International Nuclear Information System (INIS)

    Kalugin, A.I.; Sobolev, V.V.

    2005-01-01

    Full text : The electric structure of solids has been extensively investigated for several decades within the density functional theory. However many problems are appeared. One of them, the problem of correct calculation of the transition matrix elements, is very important to calculate the optical properties of crystals. In many papers the results are obtained without taking into account the probabilities of transitions. The goal of this work is the calculation of spectrum with and without taking into account the matrix elements influence of matrix elements on the optical properties of cadmium fluoride. Also localizations of transitions in Brillouin Zone (BZ) were calculated. This work contains interesting information about the electronic structure of cadmium fluoride

  2. Fine structure of sprites and proposed global observations

    DEFF Research Database (Denmark)

    Mende, S.B; Frey, H.U.; Rairden, R.l.

    2002-01-01

    structures of columniform sprites (C sprites) consisted of slant directed, nearly vertically aligned columns of intense pinpoint like beads. The distance of the sprites from the observer was measured and the altitude and vertical spacing of the beads were estimated. The distribution of beads showed...... bore-sighted photometers. The imager will locate the sprites near the earth limb and make global synoptic measurements while the photometers will measure the spectral and temporal properties of sprites and other upper atmospheric luminous phenomena in a number of different wavelength regions...

  3. Analysis of syntactic and semantic features for fine-grained event-spatial understanding in outbreak news reports

    Directory of Open Access Journals (Sweden)

    Chanlekha Hutchatai

    2010-03-01

    Full Text Available Abstract Background Previous studies have suggested that epidemiological reasoning needs a fine-grained modelling of events, especially their spatial and temporal attributes. While the temporal analysis of events has been intensively studied, far less attention has been paid to their spatial analysis. This article aims at filling the gap concerning automatic event-spatial attribute analysis in order to support health surveillance and epidemiological reasoning. Results In this work, we propose a methodology that provides a detailed analysis on each event reported in news articles to recover the most specific locations where it occurs. Various features for recognizing spatial attributes of the events were studied and incorporated into the models which were trained by several machine learning techniques. The best performance for spatial attribute recognition is very promising; 85.9% F-score (86.75% precision/85.1% recall. Conclusions We extended our work on event-spatial attribute recognition by focusing on machine learning techniques, which are CRF, SVM, and Decision tree. Our approach avoided the costly development of an external knowledge base by employing the feature sources that can be acquired locally from the analyzed document. The results showed that the CRF model performed the best. Our study indicated that the nearest location and previous event location are the most important features for the CRF and SVM model, while the location extracted from the verb's subject is the most important to the Decision tree model.

  4. Big bang nucleosynthesis with a varying fine structure constant and nonstandard expansion rate

    International Nuclear Information System (INIS)

    Ichikawa, Kazuhide; Kawasaki, Masahiro

    2004-01-01

    We calculate the primordial abundances of light elements produced during big bang nucleosynthesis when the fine structure constant and/or the cosmic expansion rate take nonstandard values. We compare them with the recent values of observed D, 4 He, and 7 Li abundances, which show a slight inconsistency among themselves in the standard big bang nucleosynthesis scenario. This inconsistency is not solved by considering either a varying fine structure constant or a nonstandard expansion rate separately but solutions are found by their simultaneous existence

  5. Cosmological constraints on variations of the fine structure constant at the epoch of recombination

    International Nuclear Information System (INIS)

    Menegoni, E; Galli, S; Archidiacono, M; Calabrese, E; Melchiorri, A

    2013-01-01

    In this brief work we investigate any possible variation of the fine structure constant at the epoch of recombination. The recent measurements of the Cosmic Microwave Background anisotropies at arcminute angular scales performed by the ACT and SPT experiments are probing the damping regime of Cosmic Microwave Background fluctuations. We study the role of a mechanism that could affect the shape of the Cosmic Microwave Background angular fluctuations at those scales, namely a change in the recombination process through variations in the fine structure constant α

  6. On a fine structure of a primary impulse of a magnetic storm sudden commencement

    International Nuclear Information System (INIS)

    Parkhomov, V.A.

    1985-01-01

    A fine structure of a primary reverse impulse of a sudden commencement (SSC*) of a magnetic storm is analyzed. 200 cases of SSC* recorded in 1965-79 have been chosen for the investigation. It is shown that the preliminary impulse of the sudden copmencement of magnetic storms has a fine structure in the form of the train of damped oscillations in Pc2-3 range of < or approximately 2 min durations. The excitation of oscillations is related with the propagation of the fast magnetoacoustic wave which is generated during interaction of the interplanetary shock wave with the earth magnetosphere

  7. Fine structure of the isoscalar giant quadrupole resonance from high-resolution inelastic proton scattering experiments

    International Nuclear Information System (INIS)

    Shevchenko, A.

    2005-02-01

    In the present work the phenomenon of fine structure in the region of the isoscalar giant quadrupole resonance in a number of heavy and medium-heavy nuclei is systematically investigated for the first time. High energy-resolution inelastic proton scattering experiments were carried out in September-October 2001 and in October 2003 at the iThemba LABS cyclotron facility in South Africa with an incident proton energy of 200 MeV. The obtained data with the energy resolution of triangle E 58 Ni, 89 Y, 90 Zr, 120 Sn, 142 Nd, 166 Er, 208 Pb), thereby establishing the global character of this phenomenon. Fine structure can be described using characteristic energy scales, appearing as a result of the decay of collective modes towards the compound nucleus through a hierarchy of couplings to complex degrees of freedom. For the extraction of the characteristic energy scales from the spectra an entropy index method and a novel technique based on the wavelet analysis are utilized. The global analysis of available data shows the presence of three groups of scales, according to their values. To the first group belong the scales with the values around and below 100 keV, which were detected in all the nuclei studied. The second group contains intermediate scales in the range of 100 keV to 1 MeV. These scales show large variations depending on the nuclear structure of the nucleus. The largest scales above 1 MeV are classified to the third group, describing the global structure of the resonance (the width). The interpretation of the observed scales is realized via the comparison with microscopic model calculations including the coupling of the initial one-particle-one-hole excitations to more complex configurations. A qualitative agreement of the experimentally observed scales with those obtained from the theoretical predictions supports the suggestion of the origin of fine structure from the coupling to the two-particle-two-hole states. However, quantitatively, large deviations are

  8. Fine-scaled human genetic structure revealed by SNP microarrays.

    Science.gov (United States)

    Xing, Jinchuan; Watkins, W Scott; Witherspoon, David J; Zhang, Yuhua; Guthery, Stephen L; Thara, Rangaswamy; Mowry, Bryan J; Bulayeva, Kazima; Weiss, Robert B; Jorde, Lynn B

    2009-05-01

    We report an analysis of more than 240,000 loci genotyped using the Affymetrix SNP microarray in 554 individuals from 27 worldwide populations in Africa, Asia, and Europe. To provide a more extensive and complete sampling of human genetic variation, we have included caste and tribal samples from two states in South India, Daghestanis from eastern Europe, and the Iban from Malaysia. Consistent with observations made by Charles Darwin, our results highlight shared variation among human populations and demonstrate that much genetic variation is geographically continuous. At the same time, principal components analyses reveal discernible genetic differentiation among almost all identified populations in our sample, and in most cases, individuals can be clearly assigned to defined populations on the basis of SNP genotypes. All individuals are accurately classified into continental groups using a model-based clustering algorithm, but between closely related populations, genetic and self-classifications conflict for some individuals. The 250K data permitted high-level resolution of genetic variation among Indian caste and tribal populations and between highland and lowland Daghestani populations. In particular, upper-caste individuals from Tamil Nadu and Andhra Pradesh form one defined group, lower-caste individuals from these two states form another, and the tribal Irula samples form a third. Our results emphasize the correlation of genetic and geographic distances and highlight other elements, including social factors that have contributed to population structure.

  9. Structural safety features for superconducting magnets

    International Nuclear Information System (INIS)

    Lehner, J.; Reich, M.; Powell, J.; Bezler, P.; Gardner, D.; Yu, W.; Chang, T.Y.

    1975-01-01

    A survey has been carried out for various potential structural safety problems of superconducting fusion magnets. These areas include: (1) Stresses due to inhomogeneous temperature distributions in magnets where normal regions have been initiated. (2) Stress distributions and yield forces due to cracks and failed regions. (3) Superconducting magnet response due to seismic excitation. These analyses have been carried out using a variety of large capacity finite element computer codes that allow for the evaluation of stresses in elastic or elastic-plastic zones and around singularities in the magnet structure. Thus far, these analyses have been carried out on UWMAK-I type magnet systems

  10. The connection between the electromagnetic fine structure constant α-bar0 and the monster Lie algebra

    International Nuclear Information System (INIS)

    Marek-Crnjac, L.

    2008-01-01

    The essay gives arguments for deriving the electromagnetic fine structure constant from maximally symmetric spaces. A connection between the order of some subgroups of the monster simple group, the ratio of the proton mass to the electron mass and the fine structure constant is found. A derivation of the fine structure constant from the number of elements in the Cristoffel symbol and the order of the reflection group F 4 is given

  11. Feature-based motion control for near-repetitive structures

    NARCIS (Netherlands)

    Best, de J.J.T.H.

    2011-01-01

    In many manufacturing processes, production steps are carried out on repetitive structures which consist of identical features placed in a repetitive pattern. In the production of these repetitive structures one or more consecutive steps are carried out on the features to create the final product.

  12. Subsurface structures of buried features in the lunar Procellarum region

    Science.gov (United States)

    Wang, Wenrui; Heki, Kosuke

    2017-07-01

    The Gravity Recovery and Interior Laboratory (GRAIL) mission unraveled numbers of features showing strong gravity anomalies without prominent topographic signatures in the lunar Procellarum region. These features, located in different geologic units, are considered to have complex subsurface structures reflecting different evolution processes. By using the GRAIL level-1 data, we estimated the free-air and Bouguer gravity anomalies in several selected regions including such intriguing features. With the three-dimensional inversion technique, we recovered subsurface density structures in these regions.

  13. Internet of Things: Structure, Features and Management

    Directory of Open Access Journals (Sweden)

    Aleksandrovičs Vladislavs

    2016-12-01

    Full Text Available Internet of Things (IoT - a rapidly developing technology today and most likely everyday thing in the future. Numerous devices, computing machines and build-in sensors connected in a single dynamic network continuously receive and exchange information from the outer environment. Huge data clusters are collected and put to use in handmade applications that scrupulously manage and control given objectives. In this way, an interactive technical infrastructure is created, which can oversee and infiltrate any person’s vital processes. Though separately every device and technological solution in the IoT can be known for many years, each architecture is unique and provides new challenges for the network owner. This research aims to investigate IoT general structure and management aspects with the knowledge of which the authors will try to answer a trivial question whether it is possible to comprehensively control such a tremendous structure with the current level of technology.

  14. Organizational structure features supporting knowledge management processes

    OpenAIRE

    Claver-Cortés, Enrique; Zaragoza Sáez, Patrocinio del Carmen; Pertusa-Ortega, Eva

    2007-01-01

    Purpose – The idea that knowledge management can be a potential source of competitive advantage has gained strength in the last few years. However, a number of business actions are needed to generate an appropriate environment and infrastructure for knowledge creation, transfer and application. Among these actions there stands out the design of an organizational structure, the link of which with knowledge management is the main concern here. More specifically, the present paper has as its aim...

  15. X-ray absorption fine structure (XAFS) studies of cobalt silicide thin films

    International Nuclear Information System (INIS)

    Naftel, S.J.; Coulthard, I.; Hu, Y.; Sham, T.K.; Zinke-Allmang, M.

    1998-01-01

    Cobalt silicide thin films, prepared on Si(100) wafers, have been studied by X-ray absorption near edge structures (XANES) at the Si K-, L 2,3 - and Co K-edges utilizing both total electron (TEY) and fluorescence yield (FLY) detection as well as extended X-ray absorption fine structure (EXAFS) at the Co K-edge. Samples made using DC sputter deposition on clean Si surfaces and MBE were studied along with a bulk CoSi 2 sample. XANES and EXAFS provide information about the electronic structure and morphology of the films. It was found that the films studied have essentially the same structure as bulk CoSi 2 . Both the spectroscopy and materials characterization aspects of XAFS (X-ray absorption fine structures) are discussed

  16. Local Fine Structural Insight into Mechanism of Electrochemical Passivation of Titanium.

    Science.gov (United States)

    Wang, Lu; Yu, Hongying; Wang, Ke; Xu, Haisong; Wang, Shaoyang; Sun, Dongbai

    2016-07-20

    Electrochemically formed passive film on titanium in 1.0 M H2SO4 solution and its thickness, composition, chemical state, and local fine structure are examined by Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), and X-ray absorption fine structure. AES analysis reveals that the thickness and composition of oxide film are proportional to the reciprocal of current density in potentiodynamic polarization. XPS depth profiles of the chemical states of titanium exhibit the coexistence of various valences cations in the surface. Quantitative X-ray absorption near edge structure analysis of the local electronic structure of the topmost surface (∼5.0 nm) shows that the ratio of [TiO2]/[Ti2O3] is consistent with that of passivation/dissolution of electrochemical activity. Theoretical calculation and analysis of extended X-ray absorption fine structure spectra at Ti K-edge indicate that both the structures of passivation and dissolution are distorted caused by the appearance of two different sites of Ti-O and Ti-Ti. And the bound water in the topmost surface plays a vital role in structural disorder confirmed by XPS. Overall, the increase of average Ti-O coordination causes the electrochemical passivation, and the dissolution is due to the decrease of average Ti-Ti coordination. The structural variations of passivation in coordination number and interatomic distance are in good agreement with the prediction of point defect model.

  17. Unique structural features facilitate lizard tail autotomy.

    Science.gov (United States)

    Sanggaard, Kristian W; Danielsen, Carl Chr; Wogensen, Lise; Vinding, Mads S; Rydtoft, Louise M; Mortensen, Martin B; Karring, Henrik; Nielsen, Niels Chr; Wang, Tobias; Thøgersen, Ida B; Enghild, Jan J

    2012-01-01

    Autotomy refers to the voluntary shedding of a body part; a renowned example is tail loss among lizards as a response to attempted predation. Although many aspects of lizard tail autotomy have been studied, the detailed morphology and mechanism remains unclear. In the present study, we showed that tail shedding by the Tokay gecko (Gekko gecko) and the associated extracellular matrix (ECM) rupture were independent of proteolysis. Instead, lizard caudal autotomy relied on biological adhesion facilitated by surface microstructures. Results based on bio-imaging techniques demonstrated that the tail of Gekko gecko was pre-severed at distinct sites and that its structural integrity depended on the adhesion between these segments.

  18. Structural features of the Compact Ignition Tokamak

    International Nuclear Information System (INIS)

    Citrolo, J.; Brown, G.; Rogoff, P.

    1987-01-01

    The Compact Ignition Tokamak (CIT) is undergoing preliminary structural design and definitions. It will be relatively inexpensive with ignition capabilities. During the definition phase it was concluded that the TF coil should be assembled from the laminate copper-Inconel plates since copper alone cannot sustain the expected magnetic and thermal loads. An extensive test program is being initiated to investigate the various materials, and their elastic and inelastic response and to develop the constitutive equations required for the selection of design criteria and for the stress analysis of this device. Finite element analysis nonlinear material capabilities are being used to study, predict and correlate the machine behavior

  19. Renal fine structures detected by NMR imaging. First communication concerning an optimized technique

    Energy Technology Data Exchange (ETDEWEB)

    Zilch, H.G.

    1986-11-01

    A significantly improved image quality is achieved by the technique described, as compared to the magnetic resonance data obtained so far. The detailed analysis of the kidney goes as deep as into anatomic fine structures, and there is reason to hope for far better diagnostic details.

  20. Fine structure transition cross sections for several alkali+rare gas systems

    International Nuclear Information System (INIS)

    Olson, R.E.

    1975-01-01

    The energy dependence E(cm) 2 P1/2→ 2 P3/2 fine structure transition of the lowest excited states of the alkali are calculated for the following systems: Na, K, Rb+He, Ne, Ar and Cs+He. Encouraging agreement between theory and experiment is obtained [fr

  1. Experimental determination of the relativistic fine structure splitting in a pionic atom

    International Nuclear Information System (INIS)

    Wang, K.-C.; Boehm, F.; Hahn, A.A.; Henrikson, H.E.; Miller, J.P.; Powers, R.J.; Vogel, P.; Vuilleumier, J.-L.; Kunselman, R.

    1978-01-01

    Using a high-resolution crystal spectrometer, the authors have measured the energy splitting of the pionic 5g-4f and 5f-4d transitions in Ti. The observed fine structure splitting agrees, within the experimental error of 3%, with the splitting arising from the calculated relativistic term and other small corrections for spinless particles. (Auth.)

  2. Photoionization modeling of the LWS fine-structure lines in IR bright galaxies

    Science.gov (United States)

    Satyapal, S.; Luhman, M. L.; Fischer, J.; Greenhouse, M. A.; Wolfire, M. G.

    1997-01-01

    The long wavelength spectrometer (LWS) fine structure line spectra from infrared luminous galaxies were modeled using stellar evolutionary synthesis models combined with photoionization and photodissociation region models. The calculations were carried out by using the computational code CLOUDY. Starburst and active galactic nuclei models are presented. The effects of dust in the ionized region are examined.

  3. Temperature-dependent fine structure splitting in InGaN quantum dots

    Science.gov (United States)

    Wang, Tong; Puchtler, Tim J.; Zhu, Tongtong; Jarman, John C.; Kocher, Claudius C.; Oliver, Rachel A.; Taylor, Robert A.

    2017-07-01

    We report the experimental observation of temperature-dependent fine structure splitting in semiconductor quantum dots using a non-polar (11-20) a-plane InGaN system, up to the on-chip Peltier cooling threshold of 200 K. At 5 K, a statistical average splitting of 443 ± 132 μeV has been found based on 81 quantum dots. The degree of fine structure splitting stays relatively constant for temperatures less than 100 K and only increases above that temperature. At 200 K, we find that the fine structure splitting ranges between 2 and 12 meV, which is an order of magnitude higher than that at low temperatures. Our investigations also show that phonon interactions at high temperatures might have a correlation with the degree of exchange interactions. The large fine structure splitting at 200 K makes it easier to isolate the individual components of the polarized emission spectrally, increasing the effective degree of polarization for potential on-chip applications of polarized single-photon sources.

  4. Extended X-ray absorption fine structure investigation of nitrogen stabilized expanded austenite

    DEFF Research Database (Denmark)

    Oddershede, Jette; Christiansen, Thomas; Ståhl, Kenny

    2010-01-01

    As-delivered austenitic stainless steel and nitrogen stabilized expanded austenite, both fully nitrided and denitrided (in H2), were investigated with Cr, Fe and Ni extended X-ray absorption fine structure. The data shows pronounced short-range ordering of Cr and N. For the denitrided specimen...

  5. Fine structure of the CCl3 UV absorption spectrum and CCl3 kinetics

    DEFF Research Database (Denmark)

    Ellermann, T.

    1992-01-01

    The UV gas-phase spectrum of CCl3 was recorded in the range 220-300 nm using pulse radiolysis of CHCl3/SF6 or CCl4/Ar gas mixtures. The UV spectrum exhibits a pronounced vibrational fine structure which is assigned to transition into the (C2A1'(3s)) Rydberg state. The vibronic progression has...

  6. The architecture and fine structure of gill filaments in the brown ...

    African Journals Online (AJOL)

    The architecture and fine structure of gill filaments in the brown mussel, Perna perna. MA Gregory' ... exhibit many of the characteristics which are widely sought in sentinel ... tion surveys (Gardner, Connell, Eagle, Moldan, Oliff, Orren ..... From the undifferentiated cell/lateral cell interface to the cen- .... amorphous material.

  7. On the relationship between multi-channel envelope and temporal fine structure

    DEFF Research Database (Denmark)

    Søndergaard, Peter Lempel; Decorsiere, Remi Julien Blaise; Dau, Torsten

    2011-01-01

    The envelope of a signal is broadly defined as the slow changes in time of the signal, where as the temporal fine structure (TFS) are the fast changes in time, i.e. the carrier wave(s) of the signal. The focus of this paper is on envelope and TFS in multi-channel systems. We discuss the differenc...

  8. Fine structure and immunocytochemistry of a new chemosensory system in the Chiton larva (Mollusca: Polyplacophora)

    DEFF Research Database (Denmark)

    Haszprunar, Gerhard; Friedrich, Stefan; Wanninger, Andreas

    2002-01-01

    symmetrically situated pairs lying dorsolaterally and ventrolaterally in the pretrochal part of the trochophore-like larva and they send axons into the cerebral commissure. They are lost at metamorphosis. The fine structure of these cells strongly resembles that of so-called "ampullary cells" known from various...

  9. Clonal growth and fine-scale genetic structure in tanoak (Notholithocarpus densiflorus: Fagaceae)

    Science.gov (United States)

    Richard S. Dodd; Wasima Mayer; Alejandro Nettel; Zara Afzal-Rafii

    2013-01-01

    The combination of sprouting and reproduction by seed can have important consequences on fine-scale spatial distribution of genetic structure (SGS). SGS is an important consideration for species’ restoration because it determines the minimum distance among seed trees to maximize genetic diversity while not prejudicing locally adapted genotypes. Local environmental...

  10. Unique structural features facilitate lizard tail autotomy.

    Directory of Open Access Journals (Sweden)

    Kristian W Sanggaard

    Full Text Available Autotomy refers to the voluntary shedding of a body part; a renowned example is tail loss among lizards as a response to attempted predation. Although many aspects of lizard tail autotomy have been studied, the detailed morphology and mechanism remains unclear. In the present study, we showed that tail shedding by the Tokay gecko (Gekko gecko and the associated extracellular matrix (ECM rupture were independent of proteolysis. Instead, lizard caudal autotomy relied on biological adhesion facilitated by surface microstructures. Results based on bio-imaging techniques demonstrated that the tail of Gekko gecko was pre-severed at distinct sites and that its structural integrity depended on the adhesion between these segments.

  11. Structural features that optimize high temperature superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Jorgensen, J.D.; Hinks, D.G. Chmaissem, O.; Argyriou, D.N.; Mitchell, J.F. [Argonne National Lab., IL (United States); Dabrowski, B. [Northern Illinois Univ., De Kalb, IL (United States). Dept. of Physics

    1996-01-01

    For example, various defects can be introduced into the blocking layer to provide the optimum carrier concentration, but defects that form in or adjacent to the CuO{sub 2} layers will lower T{sub c} and eventually destroy superconductivity. After these requirements are satisfied, the highest T{sub c}`s are observed for compounds (such as the HgBa{sub 2}Ca{sub n-1}CuO{sub 2n{plus}2{plus}x} family) that have flat and square CuO{sub 2} planes and long apical Cu-O bonds. This conclusion is confirmed by the study of materials in which the flatness of the CuO{sub 2} plane can be varied in a systematic way. In more recent work, attention has focused on how the structure can be modified, for example, by chemical substitution, to improve flux pinning properties. Two strategies are being investigated: (1) Increasing the coupling of pancake vortices to form vortex-lines by shortening or ``metallizing`` the blocking layer; and (2) the formation of defects that pin flux.

  12. Features of micromorphological structure of medicinal hyssop

    Directory of Open Access Journals (Sweden)

    Lyudmyla A. Kotyuk

    2016-06-01

    Full Text Available Micromorphological peculiarities of the structure of vegetative and generative organs of Hyssopus officinalis were analyzed. The epidermis of H. officinalis reveals diacyctic stomata and external outgrowths: glandular and covering trichomes, as well as peltate essential oil glands. Capitate and bent indumentary (covering trichomes occur on the stem, while on the leaves peltate glands, conical and bent uni- and multicellular trichomes were observed. On the calyx, in the midrib region, there are peltate glands while the ribs are densely covered with indumentary and glandular trichomes. The corolla’s adaxial surface is covered with long indumentary trichomes, with sparse peltate glands occurring on the margins. The highest density of essential oil peltate glands is found on the adaxial surface of the calyx upper lip (15.8±2.54 pcs./mm2 and on the leaf abaxial surface (13.6±2.40 pcs./mm2. Glands with the largest diameter (47.82±2.82 μm are located on the leaf adaxial surface.

  13. Structural features that optimize high temperature superconductivity

    International Nuclear Information System (INIS)

    Jorgensen, J.D.; Hinks, D.G. Chmaissem, O.; Argyriou, D.N.; Mitchell, J.F.; Dabrowski, B.

    1996-01-01

    For example, various defects can be introduced into the blocking layer to provide the optimum carrier concentration, but defects that form in or adjacent to the CuO 2 layers will lower T c and eventually destroy superconductivity. After these requirements are satisfied, the highest T c 's are observed for compounds (such as the HgBa 2 Ca n-1 CuO 2n+2+x family) that have flat and square CuO 2 planes and long apical Cu-O bonds. This conclusion is confirmed by the study of materials in which the flatness of the CuO 2 plane can be varied in a systematic way. In more recent work, attention has focused on how the structure can be modified, for example, by chemical substitution, to improve flux pinning properties. Two strategies are being investigated: (1) Increasing the coupling of pancake vortices to form vortex-lines by shortening or ''metallizing'' the blocking layer; and (2) the formation of defects that pin flux

  14. Topological map of the Hofstadter butterfly: Fine structure of Chern numbers and Van Hove singularities

    Energy Technology Data Exchange (ETDEWEB)

    Naumis, Gerardo G., E-mail: naumis@fisica.unam.mx [Departamento de Física–Química, Instituto de Física, Universidad Nacional Autónoma de México (UNAM), Apartado Postal 20-364, 01000 México, Distrito Federal (Mexico); Department of Physics and Astronomy, George Mason University, Fairfax, VA 22030 (United States); Escuela Superior de Física y Matemáticas, ESIA-Zacatenco, Instituto Politécnico Nacional, México D.F. (Mexico)

    2016-04-29

    The Hofstadter butterfly is a quantum fractal with a highly complex nested set of gaps, where each gap represents a quantum Hall state whose quantized conductivity is characterized by topological invariants known as the Chern numbers. Here we obtain simple rules to determine the Chern numbers at all scales in the butterfly fractal and lay out a very detailed topological map of the butterfly by using a method used to describe quasicrystals: the cut and projection method. Our study reveals the existence of a set of critical points that separates orderly patterns of both positive and negative Cherns that appear as a fine structure in the butterfly. This fine structure can be understood as a small tilting of the projection subspace in the cut and projection method and by using a Chern meeting formula. Finally, we prove that the critical points are identified with the Van Hove singularities that exist at every band center in the butterfly landscape. - Highlights: • Use a higher dimensional approach to build a topological map of the Hofstadter butterfly. • There is a fine structure of Chern numbers around each rational flux. • Van Hove singularities are limiting points for topological sequences of the fine flux.

  15. Topological map of the Hofstadter butterfly: Fine structure of Chern numbers and Van Hove singularities

    International Nuclear Information System (INIS)

    Naumis, Gerardo G.

    2016-01-01

    The Hofstadter butterfly is a quantum fractal with a highly complex nested set of gaps, where each gap represents a quantum Hall state whose quantized conductivity is characterized by topological invariants known as the Chern numbers. Here we obtain simple rules to determine the Chern numbers at all scales in the butterfly fractal and lay out a very detailed topological map of the butterfly by using a method used to describe quasicrystals: the cut and projection method. Our study reveals the existence of a set of critical points that separates orderly patterns of both positive and negative Cherns that appear as a fine structure in the butterfly. This fine structure can be understood as a small tilting of the projection subspace in the cut and projection method and by using a Chern meeting formula. Finally, we prove that the critical points are identified with the Van Hove singularities that exist at every band center in the butterfly landscape. - Highlights: • Use a higher dimensional approach to build a topological map of the Hofstadter butterfly. • There is a fine structure of Chern numbers around each rational flux. • Van Hove singularities are limiting points for topological sequences of the fine flux.

  16. Determining the Velocity Fine Structure by a Laser Anemometer with Fixed Orientation

    DEFF Research Database (Denmark)

    Kristensen, Leif; Kirkegaard, Peter; Mikkelsen, Torben

    We have studied the velocity structure functions and spectra which can be determined by a CW-laser anemometer and a (pulsed) lidar anemometer. We have found useful theoretical expressions for both types of anemometers and compared their filtering of the alongbeam turbulent velocity. The purpose h...... been to establish a basis for remote determining of turbulence fine-structure in terms of the rate of dissipation of specific kinetic energy in the atmospheric boundary layer....

  17. Content and structure of future teachers’ aesthetic perception of fine and decorative applied art creations

    Directory of Open Access Journals (Sweden)

    Liudmyla Lisunova

    2017-03-01

    Full Text Available The content and structure of future teachers’ aesthetic perception of fine and decorativeapplied art creations in the system of professional training are delivered in this article. Thestructural components and stages (phases of aesthetic perception process are determined, therole of art as the most powerful source of reality in the process of future teachers’ aestheticperception of art are revealed.Key words: contents and structure of aesthetic perception, future teachers of art, fineand decorative applied art creations

  18. Determining the velocity fine structure by a laser anemometer with fixed orientation

    Energy Technology Data Exchange (ETDEWEB)

    Kristensen, Leif; Kirkegaard, P.; Mikkelsen, Torben

    2011-02-15

    We have studied the velocity structure functions and spectra which can be determined by a CW-laser anemometer and a (pulsed) lidar anemometer. We have found useful theoretical expressions for both types of anemometers and compared their filtering of the along-beam turbulent velocity. The purpose has been to establish a basis for remote determining of turbulence fine-structure in terms of the rate of dissipation of specific kinetic energy in the atmospheric boundary layer. (Author)

  19. Local hydrated structure of an Fe2+/Fe3+ aqueous solution: an investigation using a combination of molecular dynamics and X-ray absorption fine structure methods

    International Nuclear Information System (INIS)

    Ye Qing; Zhou Jing; Zhao Haifeng; Chen Xing; Chu Wangsheng; Zheng Xusheng; Marcelli, Augusto; Wu Ziyu

    2013-01-01

    The hydrated shell of both Fe 2+ and Fe 3+ aqueous solutions are investigated by using the molecular dynamics (MD) and X-ray absorption structure (XAS) methods. The MD simulations show that the first hydrated shells of both Fe 2+ and Fe 3+ are characterized by a regular octahedron with an Fe-O distance of 2.08Å for Fe 2+ and 1.96Å for Fe 3+ , and rule out the occurrence of a Jahn-Teller distortion in the hydrated shell of an Fe 2+ aqueous solution. The corresponding X-ray absorption near edge fine structure (XANES) calculation successfully reproduces all features in the XANES spectra in Fe 2+ and Fe 3+ aqueous solution. A feature that is located at energy 1 eV higher than the white line (WL) in an Fe 3+ aqueous solution may be assigned to the contribution of the charge transfer. (authors)

  20. Electronic fine structure and recombination dynamics in single InAs quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Seguin, R.

    2008-01-28

    In the work at hand single InAs/GaAs quantum dots (QDs) are examined via cathodoluminescence spectroscopy. A thorough analysis of the spectra leads to an unambiguous assignment of the lines to the decay of specific excitonic complexes. A special aspect of the Coulomb interaction, the exchange interaction, gives rise to a fine structure in the initial and final states of an excitonic decay. This leads to a fine structure in the emission spectra that again is unique for every excitonic complex. The exchange interaction is discussed in great detail in this work.QDs of different sizes are investigated and the influence on the electronic properties is monitored. Additionally, the structure is modified ex situ by a thermal annealing process. The changes of the spectra under different annealing temperatures are traced. Finally, recombination dynamics of different excitonic complexes are examined by performing time-resolved cathodoluminescence spectroscopy. (orig.)

  1. Electronic fine structure and recombination dynamics in single InAs quantum dots

    International Nuclear Information System (INIS)

    Seguin, R.

    2008-01-01

    In the work at hand single InAs/GaAs quantum dots (QDs) are examined via cathodoluminescence spectroscopy. A thorough analysis of the spectra leads to an unambiguous assignment of the lines to the decay of specific excitonic complexes. A special aspect of the Coulomb interaction, the exchange interaction, gives rise to a fine structure in the initial and final states of an excitonic decay. This leads to a fine structure in the emission spectra that again is unique for every excitonic complex. The exchange interaction is discussed in great detail in this work.QDs of different sizes are investigated and the influence on the electronic properties is monitored. Additionally, the structure is modified ex situ by a thermal annealing process. The changes of the spectra under different annealing temperatures are traced. Finally, recombination dynamics of different excitonic complexes are examined by performing time-resolved cathodoluminescence spectroscopy. (orig.)

  2. Intensity Mapping of the [CII] Fine Structure Line during the Epoch of Reionization

    Science.gov (United States)

    Gong, Yan; Cooray, A.; Silva, M.; Santos, M. G.; Bock, J.; Bradford, M.; Zemcov, M.

    2012-01-01

    The atomic CII fine-structure line is one of the brightest lines in a typical star-forming galaxy spectrum with a luminosity 0.1% to 1% of the bolometric luminosity. It is otentially a reliable tracer of the dense gas distribution at high edshifts and could provide an additional probe to the era of reionization. By taking into account of the spontaneous, stimulated and collisional emission of the CII line, we calculate the spin temperature and the mean intensity as a function of the redshift. When averaged over a cosmologically large volume, we find that the CII emission from ionized carbon in individual galaxies is larger than the signal generated by carbon in the intergalactic medium (IGM). Assuming that the CII luminosity is proportional to the carbon mass in dark matter halos, we also compute the power spectrum of the CII line intensity at various redshifts. In order to avoid the contamination from CO rotational lines at low redshift when targeting a CII survey at high redshifts, we propose the cross-correlation of CII and 21-cm line emission from high redshifts. To explore the detectability of the CII signal from reionization, we also evaluate the expected errors on the CII power spectrum and CII-21 cm cross power spectrum based on the design of the future milimeter surveys. We note that the CII-21 cm cross power spectrum contains interesting features that captures physics during reionization, including the ionized bubble sizes and the mean ionization fraction, which are challenging to measure from 21-cm data alone. We propose an instrumental concept for the reionization CII experiment targeting the frequency range of 200 to 300 GHz with 1, 3 and 10 meter apertures and a bolometric spectrometer array with 64 independent spectral pixels with about 20,000 bolometers.

  3. FINE-SCALE STRUCTURES OF FLUX ROPES TRACKED BY ERUPTING MATERIAL

    Energy Technology Data Exchange (ETDEWEB)

    Li Ting; Zhang Jun, E-mail: liting@nao.cas.cn, E-mail: zjun@nao.cas.cn [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

    2013-06-20

    We present Solar Dynamics Observatory observations of two flux ropes tracked out by material from a surge and a failed filament eruption on 2012 July 29 and August 4, respectively. For the first event, the interaction between the erupting surge and a loop-shaped filament in the east seems to 'peel off' the filament and add bright mass into the flux rope body. The second event is associated with a C-class flare that occurs several minutes before the filament activation. The two flux ropes are, respectively, composed of 85 {+-} 12 and 102 {+-} 15 fine-scale structures, with an average width of about 1.''6. Our observations show that two extreme ends of the flux rope are rooted in opposite polarity fields and each end is composed of multiple footpoints (FPs) of fine-scale structures. The FPs of the fine-scale structures are located at network magnetic fields, with magnetic fluxes from 5.6 Multiplication-Sign 10{sup 18} Mx to 8.6 Multiplication-Sign 10{sup 19} Mx. Moreover, almost half of the FPs show converging motion of smaller magnetic structures over 10 hr before the appearance of the flux rope. By calculating the magnetic fields of the FPs, we deduce that the two flux ropes occupy at least 4.3 Multiplication-Sign 10{sup 20} Mx and 7.6 Multiplication-Sign 10{sup 20} Mx magnetic fluxes, respectively.

  4. Fine Structure in Helium-like Fluorine by Fast-Beam Laser Spectroscopy

    Science.gov (United States)

    Myers, E. G.; Thompson, J. K.; Silver, J. D.

    1998-05-01

    With the aim of providing an additional precise test of higher-order corrections to high precision calculations of fine structure in helium and helium-like ions(T. Zhang, Z.-C. Yan and G.W.F. Drake, Phys. Rev. Lett. 77), 1715 (1996)., a measurement of the 2^3P_2,F - 2^3P_1,F' fine structure in ^19F^7+ is in progress. The method involves doppler-tuned laser spectroscopy using a CO2 laser on a foil-stripped fluorine ion beam. We aim to achieve a higher precision, compared to an earlier measurement(E.G. Myers, P. Kuske, H.J. Andrae, I.A. Armour, H.A. Klein, J.D. Silver, and E. Traebert, Phys. Rev. Lett. 47), 87 (1981)., by using laser beams parallel and anti-parallel to the ion beam, to obtain partial cancellation of the doppler shift(J.K. Thompson, D.J.H. Howie and E.G. Myers, Phys. Rev. A 57), 180 (1998).. A calculation of the hyperfine structure, allowing for relativistic, QED and nuclear size effects, will be required to obtain the ``hyperfine-free'' fine structure interval from the measurements.

  5. On-line Flagging of Anomalies and Adaptive Sequential Hypothesis Testing for Fine-feature Characterization of Geosynchronous Satellites

    Science.gov (United States)

    Chaudhary, A.; Payne, T.; Kinateder, K.; Dao, P.; Beecher, E.; Boone, D.; Elliott, B.

    The objective of on-line flagging in this paper is to perform interactive assessment of geosynchronous satellites anomalies such as cross-tagging of a satellites in a cluster, solar panel offset change, etc. This assessment will utilize a Bayesian belief propagation procedure and will include automated update of baseline signature data for the satellite, while accounting for the seasonal changes. Its purpose is to enable an ongoing, automated assessment of satellite behavior through its life cycle using the photometry data collected during the synoptic search performed by a ground or space-based sensor as a part of its metrics mission. The change in the satellite features will be reported along with the probabilities of Type I and Type II errors. The objective of adaptive sequential hypothesis testing in this paper is to define future sensor tasking for the purpose of characterization of fine features of the satellite. The tasking will be designed in order to maximize new information with the least number of photometry data points to be collected during the synoptic search by a ground or space-based sensor. Its calculation is based on the utilization of information entropy techniques. The tasking is defined by considering a sequence of hypotheses in regard to the fine features of the satellite. The optimal observation conditions are then ordered in order to maximize new information about a chosen fine feature. The combined objective of on-line flagging and adaptive sequential hypothesis testing is to progressively discover new information about the features of a geosynchronous satellites by leveraging the regular but sparse cadence of data collection during the synoptic search performed by a ground or space-based sensor. Automated Algorithm to Detect Changes in Geostationary Satellite's Configuration and Cross-Tagging Phan Dao, Air Force Research Laboratory/RVB By characterizing geostationary satellites based on photometry and color photometry, analysts can

  6. Time-resolved pump-probe X-ray absorption fine structure spectroscopy of Gaq3

    International Nuclear Information System (INIS)

    Dicke, Benjamin

    2013-01-01

    Gallium(tris-8-hydroxyquinoline) (Gaq 3 ) belongs to a class of metal organic compounds, used as electron transport layer and emissive layer in organic light emitting diodes. Many research activities have concentrated on the optical and electronic properties, especially of the homologue molecule aluminum(tris-8-hydroxyquinoline) (Alq 3 ). Knowledge of the first excited state S 1 structure of these molecules could provide deeper insight into the processes involved into the operation of electronic devices, such as OLEDs and, hence, it could further improve their efficiency and optical properties. Until now the excited state structure could not be determined experimentally. Most of the information about this structure mainly arises from theoretical calculations. X-ray absorption fine structure (XAFS) spectroscopy is a well developed technique to determine both, the electronic and the geometric properties of a sample. The connection of ultrashort pulsed X-ray sources with a pulsed laser system offers the possibility to use XAFS as a tool for studying the transient changes of a sample induced by a laser pulse. In the framework of this thesis a new setup for time-resolved pump-probe X-ray absorption spectroscopy at PETRA III beamline P11 was developed for measuring samples in liquid form. In this setup the sample is pumped into its photo-excited state by a femtosecond laser pump pulse with 343 nm wavelength and after a certain time delay probed by an X-ray probe pulse. In this way the first excited singlet state S 1 of Gaq 3 dissolved in benzyl alcohol was analyzed. A structural model for the excited state structure of the Gaq 3 molecule based on the several times reproduced results of the XAFS experiments is proposed. According to this model it was found that the Ga-N A bond length is elongated, while the Ga-O A bond length is shortened upon photoexcitation. The dynamics of the structural changes were not the focus of this thesis. Nevertheless the excited state lifetime

  7. Fine structure in plasma waves and radiation near the plasma frequency in Earth's foreshock

    Science.gov (United States)

    Cairns, Iver H.

    1994-01-01

    Novel observations are presented of intrunsic fine structure in the frequency spectrum of electomagnetic (EM) radiation and plasma waves near the electron plasma frequency f(sub p) during a period of unusually high interplanetary magnetic field strength. Measured using the wideband receiver on the International Sun-Earth Explorer (ISEE) 1 spacecraft, fine-structured emissions are observed both in the solar wind and the foreshock, The fine structure is shown to correspond to emissions spaced above f(sub p) near half harmonies of the electon cyclotron frequency f(sub ce), i.e., near f(sub p) + nf(sub ce)/2. These appear to be the first space physics observations of emissions spaced by f(sub ce)/2. Indirect but strong arguments are used to discriminate between EM and electrostatic (ES) signals, to identify whether ISEE 1 is in the solar wind or the foreshock, and to determine the relative frequencies of the emissions and the local f(sub p). The data are consistent with generation of the ES and EM emissions in the foreshock, with subsequent propagation of the EM emissions into the solar wind. It remains possible that some emissions currently identified as ES have significant EM character. The ES and EM emisions often merge into one another with minimal changes in frequency, arguing that their source regions and generation mechanisms are related and imposing significant constraints on theories. The f(sub ce)/2 ES and EM fine structures observed may be intrinsic to the emission mechanisms or to superposition of two series of signals with f(sub ce) spacing that differ in starting frequency by f(sub ce)/2. Present theories for nonlinear wave coupling processes, cyclotron maser emission, and other linear instability processes are all unable to explain multiple EM and/or ES components spaced by approximately f(sub ce)/2 above f(sub p) for f(sub p)/f(sub ce) much greater than 1 and typical for shock beams parameters. Suitable avenues for further theoretical research are

  8. STM study on surface relief, ultra-fine structure and transformation mechanism of bainite in steels

    International Nuclear Information System (INIS)

    Fang, H.S.; Yang, Z.G.; Wang, J.J.; Zheng, Y.K.

    1995-01-01

    The surface reliefs accompanying lower bainite transformation in steels have been studied by scanning tunneling microscopy (STM). With the exclusive vertical resolution of STM, we observed that the surface relief associated with bainite is a group of surface reliefs related to subplates, subunits and sub-subunits. From the bainite plate to the sub-subunit in it, the reliefs are in a tent shape, not of invariant plane strain (IPS) type. The fine structure of bainite in a steel has also been shown by STM and TEM that bainite plate is composed of subplates, subunits and sub-subunits. On the basis of the fine structure inside a bainitic ferrite plate observed under STM, sympathetic-ledgewise mechanism of bainite formation is proposed. (orig.)

  9. Fine structures of atomic excited states: precision atomic spectroscopy and electron-ion collision process

    International Nuclear Information System (INIS)

    Gao Xiang; Cheng Cheng; Li Jiaming

    2011-01-01

    Scientific research fields for future energies such as inertial confinement fusion researches and astrophysics studies especially with satellite observatories advance into stages of precision physics. The relevant atomic data are not only enormous but also of accuracy according to requirements, especially for both energy levels and the collision data. The fine structure of high excited states of atoms and ions can be measured by precision spectroscopy. Such precision measurements can provide not only knowledge about detailed dynamics of electron-ion interactions but also a bench mark examination of the accuracy of electron-ion collision data, especially incorporating theoretical computations. We illustrate that by using theoretical calculation methods which can treat the bound states and the adjacent continua on equal footing. The precision spectroscopic measurements of excited fine structures can be served as stringent tests of electron-ion collision data. (authors)

  10. Fine-structure energy levels, oscillator strengths and transition probabilities in Ni XVI

    International Nuclear Information System (INIS)

    Deb, N.C.; Msezane, A.Z.

    2001-01-01

    Fine-structure energy levels relative to the ground state, oscillator strengths and transition probabilities for transitions among the lowest 40 fine-structure levels belonging to the configurations 3s 2 3p, 3s3p 2 , 3s 2 3d, 3p 3 and 3s3p3d of Ni XVI are calculated using a large scale CI in program CIV3 of Hibbert. Relativistic effects are included through the Breit-Pauli approximation via spin-orbit, spin-other-orbit, spin-spin, Darwin and mass correction terms. The existing discrepancies between the calculated and measured values for many of the relative energy positions are resolved in the present calculation which yields excellent agreement with measurement. Also, many of our oscillator strengths for allowed and intercombination transitions are in very good agreement with the recommended data by the National Institute of Standard and Technology (NIST). (orig.)

  11. Fine structure of the isoscalar giant quadrupole resonance in 40Ca due to Landau damping?

    International Nuclear Information System (INIS)

    Usman, I.; Buthelezi, Z.; Carter, J.; Cooper, G.R.J.; Fearick, R.W.; Foertsch, S.V.; Fujita, H.; Fujita, Y.; Kalmykov, Y.; Neumann-Cosel, P. von; Neveling, R.; Papakonstantinou, P.; Richter, A.; Roth, R.; Shevchenko, A.; Sideras-Haddad, E.; Smit, F.D.

    2011-01-01

    The fragmentation of the Isoscalar Giant Quadrupole Resonance (ISGQR) in 40 Ca has been investigated in high energy-resolution experiments using proton inelastic scattering at E p =200 MeV. Fine structure is observed in the region of the ISGQR and its characteristic energy scales are extracted from the experimental data by means of a wavelet analysis. The experimental scales are well described by Random Phase Approximation (RPA) and second-RPA calculations with an effective interaction derived from a realistic nucleon-nucleon interaction by the Unitary Correlation Operator Method (UCOM). In these results characteristic scales are already present at the mean-field level pointing to their origination in Landau damping, in contrast to the findings in heavier nuclei and also to SRPA calculations for 40 Ca based on phenomenological effective interactions, where fine structure is explained by the coupling to two-particle-two-hole (2p-2h) states.

  12. Origin of fine structure of the giant dipole resonance in s d -shell nuclei

    Science.gov (United States)

    Fearick, R. W.; Erler, B.; Matsubara, H.; von Neumann-Cosel, P.; Richter, A.; Roth, R.; Tamii, A.

    2018-04-01

    A set of high-resolution zero-degree inelastic proton scattering data on 24Mg, 28Si, 32S, and 40Ca provides new insight into the long-standing puzzle of the origin of fragmentation of the giant dipole resonance (GDR) in s d -shell nuclei. Understanding is achieved by comparison with random phase approximation calculations for deformed nuclei using for the first time a realistic nucleon-nucleon interaction derived from the Argonne V18 potential with the unitary correlation operator method and supplemented by a phenomenological three-nucleon contact interaction. A wavelet analysis allows one to extract significant scales both in the data and calculations characterizing the fine structure of the GDR. The fair agreement for scales in the range of a few hundred keV supports the surmise that the fine structure arises from ground-state deformation driven by α clustering.

  13. Evidence from n=2 fine structure transitions for the production of fast excited state positronium

    International Nuclear Information System (INIS)

    Ley, R.; Niebling, K.D.; Schwarz, R.; Werth, G.

    1990-01-01

    Fine structure transitions in the first excited state of positronium (Ps) have been measured using 'Backscatter Ps' production on a Mo surface by observation of a change in the emitted Lyman-α intensity under resonant microwave irradiation. Production, fine structure transitions and Lyman-α decay of the Ps atoms took place inside a waveguide designed to transmit the microwave frequencies of 8.6, 13.0 and 18.5 GHz for the transitions from the 2 3 S 1 state to the 2 3 P J , J=2, 1, 0, states, respectively. In the presence of a magnetic field, all transitions observed show a shift to higher frequencies, compared with earlier calculations and measurements in zero magnetic field. The deviations exceed the expected Zeeman shift significantly but may be explained by assuming a motional Stark effect for Ps with kinetic energies of several eV. (author)

  14. Preferred Compression Speed for Speech and Music and Its Relationship to Sensitivity to Temporal Fine Structure

    OpenAIRE

    Moore, Brian C. J.; S?k, Aleksander

    2016-01-01

    Multichannel amplitude compression is widely used in hearing aids. The preferred compression speed varies across individuals. Moore (2008) suggested that reduced sensitivity to temporal fine structure (TFS) may be associated with preference for slow compression. This idea was tested using a simulated hearing aid. It was also assessed whether preferences for compression speed depend on the type of stimulus: speech or music. Twenty-two hearing-impaired subjects were tested, and the stimulated h...

  15. Fusion reaction yield in focused discharges with variable energy and plasma fine structure

    International Nuclear Information System (INIS)

    Bortolotti, A.; Brzosko, J.S.; Chiara, P. De; Kilic, H.; Mezzetti, F.; Nardi, V.; Powell, C.; Wang, J.

    1992-01-01

    The same linear correlation between the distribution parameters (ΔT and Max ΔV) of the radial current density J between electrodes and the fusion reaction yield per pulse, Y, in the plasma focus (PF) pinch was quantitatively determined from different PF machines. Contact prints of current-sheath fragments (CSF) ejected from the pinch are obtained from 2.5-MeV-D + ions. CSF's show the same submillimetric fine structure of the pinch. (author) 3 refs., 2 tabs

  16. Clonal diversity and fine-scale genetic structure in a high andean treeline population

    Czech Academy of Sciences Publication Activity Database

    Peng, Y.; Macek, P.; Macková, Jana; Romoleroux, K.; Hensen, I.

    2015-01-01

    Roč. 47, č. 1 (2015), s. 59-65 ISSN 0006-3606 Grant - others:GA AV ČR(CZ) IAA601110702; GA MŠk(CZ) LM2010009 Program:IA Institutional support: RVO:60077344 Keywords : AFLP * clonal diversity * clonal propagation * fine-scale genetic structure * Polylepis reticulata * treeline Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 1.944, year: 2015

  17. Fine defective structure of silicon carbide powders obtained from different starting materials

    Directory of Open Access Journals (Sweden)

    Tomila T.V.

    2006-01-01

    Full Text Available The fine defective structure of silicon carbide powders obtained from silicic acid-saccharose, aerosil-saccharose, aerosil-carbon black, and hydrated cellulose-silicic acid gel systems was investigated. The relation between IR absorption characteristics and the microstructure of SiC particles obtained from different starting materials was established. The numerical relationship between the lattice parameter a and the frequency νTO is presented.

  18. Structure and properties of permeable fine-fibrous materials fabricated of powders

    Energy Technology Data Exchange (ETDEWEB)

    Fedorchenko, I M; Kostornov, A G; Kirichenko, O V; Guzhva, N S [AN Ukrainskoj SSR, Kiev. Inst. Problem Materialovedeniya

    1982-09-01

    Effect of main structural characteristics of fine fibrous materials (FFM) of nickel and Ni-Cr, Ni-Mo, Ni-Cr-Mo, Ni-Fe-Cr, Ni-Fe alloys on their hydraulic and mechanical properties was studied. FFM was produced by sintering of polymer fibers filled with metal powders and converted to felts. It was shown, that the level of permeable material properties increases with reduction of filament diameter.

  19. Structure and properties of permeable fine-fibrous materials fabricated of powders

    International Nuclear Information System (INIS)

    Fedorchenko, I.M.; Kostornov, A.G.; Kirichenko, O.V.; Guzhva, N.S.

    1982-01-01

    Effect of main structural characteristicf of fine fibrous materials (FFM) of nickel and Ni-Cr, Ni-Mo, Ni-Cr-Mo, Ni-Fe-Cr, Ni-Fe alloys on their hydraulic and mechanical properties was studied. FFM was produced by sintering of polymer fibers filled with metal powders and converted to felts. It was shown, that the level of permeable material properties increases with reduction of filament diameter

  20. Single-particle effects in fine structure of super-asymmetric fission

    International Nuclear Information System (INIS)

    Mirea, M.

    1999-01-01

    Energy spectrum measurements concerning the 14 C decay from 223 Ra revealed a fine structure with an intense branch on the excited state of the daughter 209 Pb. Apart the great number of microscopic--macroscopic attempts of different authors in describing this behavior (compiled recently), this phenomenon was explained quantitatively using the Landau--Zener effect, i.e., the promotion mechanism of a unpaired nucleon between two levels characterised by the same quantum numbers connected to some symmetries of the nuclear system in the region where an avoided level crossing is exhibited. The adiabatic levels during the super-asymmetric fission process were determined with a new version of the two--centre shell model especially constructed for very large mass--asymmetries. The half--lives are obtained in the framework of the Wentzel--Kramers--Brillouin approximation. The amount of the variation of the barrier height in the excited channels was estimated accounting the specialization energy which can be interpreted as the excess of the energy of a nucleon with a given spin over the energy for the same spin nucleon state of lowest energy. It is evidenced that the fine structure of cluster decay is due to two competitive effects: the Landau--Zener effect which enhances the probability to have an excited daughter in the final channel and the specialization energy which increases the potential barrier and therefore leads to a diminution of the penetrability. This formalism was used for predictions of the fine structure in the case of 14 C decay of 225 Ac and to explain the fine structure of alpha decay. (author)

  1. New Constraints on Spatial Variations of the Fine Structure Constant from Clusters of Galaxies

    Directory of Open Access Journals (Sweden)

    Ivan De Martino

    2016-12-01

    Full Text Available We have constrained the spatial variation of the fine structure constant using multi-frequency measurements of the thermal Sunyaev-Zeldovich effect of 618 X-ray selected clusters. Although our results are not competitive with the ones from quasar absorption lines, we improved by a factor 10 and ∼2.5 previous results from Cosmic Microwave Background power spectrum and from galaxy clusters, respectively.

  2. Polarized fine structure in the excitation spectrum of a negatively charged quantum dot

    OpenAIRE

    Ware, M. E.; Stinaff, E. A.; Gammon, D.; Doty, M. F.; Bracker, A. S.; Gershoni, D.; Korenev, V. L.; Badescu, S. C.; Lyanda-Geller, Y.; Reinecke, T. L.

    2005-01-01

    We report polarized photoluminescence excitation spectroscopy of the negative trion in single charge tunable InAs/GaAs quantum dots. The spectrum exhibits a p-shell resonance with polarized fine structure arising from the direct excitation of the electron spin triplet states. The energy splitting arises from the axially symmetric electron-hole exchange interaction. The magnitude and sign of the polarization are understood from the spin character of the triplet states and a small amount of qua...

  3. Astronomical constraints on the cosmic evolution of the fine structure constant and possible quantum dimensions.

    Science.gov (United States)

    Carilli, C L; Menten, K M; Stocke, J T; Perlman, E; Vermeulen, R; Briggs, F; de Bruyn , A G; Conway, J; Moore, C P

    2000-12-25

    We present measurements of absorption by the 21 cm hyperfine transition of neutral hydrogen toward radio sources at substantial look-back times. These data are used in combination with observations of rotational transitions of common interstellar molecules to set limits on the evolution of the fine structure constant: alpha/ alphatheory, the limit on the secular evolution of the scale factor of the compact dimensions, R, is &Rdot/ Rbig bang, of DeltaR /R<10(-5).

  4. Visualization of Wave Propagation and Fine Structure in Frictional Motion of Unconstrained Soft Microstructured Tapes

    DEFF Research Database (Denmark)

    Heepe, Lars; Filippov, Alexander E.; Kovalev, Alexander E.

    2017-01-01

    from previous friction tests of microstructured elastomers fixed onto a rigid support, allowing only for shear deformations of surface microstructures and the backing layer, but not for stretching of the entire sample. Three different types of microstructured tapes were tested and their frictional...... behavior compared to results from numerical simulations. In both experimental and numerical cases, visualization of wave propagation and fine structure in friction is obtained....

  5. The 16th International Conference on X-ray Absorption Fine Structure (XAFS16)

    Science.gov (United States)

    Grunwaldt, J.-D.; Hagelstein, M.; Rothe, J.

    2016-05-01

    This preface of the proceedings volume of the 16th International Conference on X- ray Absorption Fine Structure (XAFS16) gives a glance on the five days of cutting-edge X-ray science which were held in Karlsruhe, Germany, August 23 - 28, 2015. In addition, several satellite meetings took place in Hamburg, Berlin and Stuttgart, a Sino-German workshop, three data analysis tutorials as well as special symposia on industrial catalysis and XFELs were held at the conference venue.

  6. Atomic oxygen fine-structure splittings with tunable far-infrared spectroscopy

    Science.gov (United States)

    Zink, Lyndon R.; Evenson, Kenneth M.; Matsushima, Fusakazu; Nelis, Thomas; Robinson, Ruth L.

    1991-01-01

    Fine-structure splittings of atomic oxygen (O-16) in the ground state have been accurately measured using a tunable far-infrared spectrometer. The 3P0-3pl splitting is 2,060,069.09 (10) MHz, and the 3Pl-3P2 splitting is 4,744,777.49 (16) MHz. These frequencies are important for measuring atomic oxygen concentration in earth's atmosphere and the interstellar medium.

  7. The future of primordial features with large-scale structure surveys

    International Nuclear Information System (INIS)

    Chen, Xingang; Namjoo, Mohammad Hossein; Dvorkin, Cora; Huang, Zhiqi; Verde, Licia

    2016-01-01

    Primordial features are one of the most important extensions of the Standard Model of cosmology, providing a wealth of information on the primordial Universe, ranging from discrimination between inflation and alternative scenarios, new particle detection, to fine structures in the inflationary potential. We study the prospects of future large-scale structure (LSS) surveys on the detection and constraints of these features. We classify primordial feature models into several classes, and for each class we present a simple template of power spectrum that encodes the essential physics. We study how well the most ambitious LSS surveys proposed to date, including both spectroscopic and photometric surveys, will be able to improve the constraints with respect to the current Planck data. We find that these LSS surveys will significantly improve the experimental sensitivity on features signals that are oscillatory in scales, due to the 3D information. For a broad range of models, these surveys will be able to reduce the errors of the amplitudes of the features by a factor of 5 or more, including several interesting candidates identified in the recent Planck data. Therefore, LSS surveys offer an impressive opportunity for primordial feature discovery in the next decade or two. We also compare the advantages of both types of surveys.

  8. The future of primordial features with large-scale structure surveys

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xingang; Namjoo, Mohammad Hossein [Institute for Theory and Computation, Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Dvorkin, Cora [Department of Physics, Harvard University, Cambridge, MA 02138 (United States); Huang, Zhiqi [School of Physics and Astronomy, Sun Yat-Sen University, 135 Xingang Xi Road, Guangzhou, 510275 (China); Verde, Licia, E-mail: xingang.chen@cfa.harvard.edu, E-mail: dvorkin@physics.harvard.edu, E-mail: huangzhq25@sysu.edu.cn, E-mail: mohammad.namjoo@cfa.harvard.edu, E-mail: liciaverde@icc.ub.edu [ICREA and ICC-UB, University of Barcelona (IEEC-UB), Marti i Franques, 1, Barcelona 08028 (Spain)

    2016-11-01

    Primordial features are one of the most important extensions of the Standard Model of cosmology, providing a wealth of information on the primordial Universe, ranging from discrimination between inflation and alternative scenarios, new particle detection, to fine structures in the inflationary potential. We study the prospects of future large-scale structure (LSS) surveys on the detection and constraints of these features. We classify primordial feature models into several classes, and for each class we present a simple template of power spectrum that encodes the essential physics. We study how well the most ambitious LSS surveys proposed to date, including both spectroscopic and photometric surveys, will be able to improve the constraints with respect to the current Planck data. We find that these LSS surveys will significantly improve the experimental sensitivity on features signals that are oscillatory in scales, due to the 3D information. For a broad range of models, these surveys will be able to reduce the errors of the amplitudes of the features by a factor of 5 or more, including several interesting candidates identified in the recent Planck data. Therefore, LSS surveys offer an impressive opportunity for primordial feature discovery in the next decade or two. We also compare the advantages of both types of surveys.

  9. Rotational and fine structure of open-shell molecules in nearly degenerate electronic states

    Science.gov (United States)

    Liu, Jinjun

    2018-03-01

    An effective Hamiltonian without symmetry restriction has been developed to model the rotational and fine structure of two nearly degenerate electronic states of an open-shell molecule. In addition to the rotational Hamiltonian for an asymmetric top, this spectroscopic model includes the energy separation between the two states due to difference potential and zero-point energy difference, as well as the spin-orbit (SO), Coriolis, and electron spin-molecular rotation (SR) interactions. Hamiltonian matrices are computed using orbitally and fully symmetrized case (a) and case (b) basis sets. Intensity formulae and selection rules for rotational transitions between a pair of nearly degenerate states and a nondegenerate state have also been derived using all four basis sets. It is demonstrated using real examples of free radicals that the fine structure of a single electronic state can be simulated with either a SR tensor or a combination of SO and Coriolis constants. The related molecular constants can be determined precisely only when all interacting levels are simulated simultaneously. The present study suggests that analysis of rotational and fine structure can provide quantitative insights into vibronic interactions and related effects.

  10. Atomistic theory of excitonic fine structure in InAs/InP nanowire quantum dot molecules

    Science.gov (United States)

    Świderski, M.; Zieliński, M.

    2017-03-01

    Nanowire quantum dots have peculiar electronic and optical properties. In this work we use atomistic tight binding to study excitonic spectra of artificial molecules formed by a double nanowire quantum dot. We demonstrate a key role of atomistic symmetry and nanowire substrate orientation rather than cylindrical shape symmetry of a nanowire and a molecule. In particular for [001 ] nanowire orientation we observe a nonvanishing bright exciton splitting for a quasimolecule formed by two cylindrical quantum dots of different heights. This effect is due to interdot coupling that effectively reduces the overall symmetry, whereas single uncoupled [001 ] quantum dots have zero fine structure splitting. We found that the same double quantum dot system grown on [111 ] nanowire reveals no excitonic fine structure for all considered quantum dot distances and individual quantum dot heights. Further we demonstrate a pronounced, by several orders of magnitude, increase of the dark exciton optical activity in a quantum dot molecule as compared to a single quantum dot. For [111 ] systems we also show spontaneous localization of single particle states in one of nominally identical quantum dots forming a molecule, which is mediated by strain and origins from the lack of the vertical inversion symmetry in [111 ] nanostructures of overall C3 v symmetry. Finally, we study lowering of symmetry due to alloy randomness that triggers nonzero excitonic fine structure and the dark exciton optical activity in realistic nanowire quantum dot molecules of intermixed composition.

  11. Bloch oscillations of ultracold atoms and measurement of the fine structure constant; Oscillations de Bloch d'atomes ultrafroids et mesure de la constante de structure fine

    Energy Technology Data Exchange (ETDEWEB)

    Clade, P

    2005-10-15

    From a measurement of the recoil velocity of an atom absorbing a photon, it is possible to deduce a determination of the ratio h/m between the Planck constant and the mass of the atoms and then to deduce a value of the fine structure constant alpha. To do this measurement, we use the technique of Bloch oscillations, which allows us to transfer a large number of recoils to atoms. A velocity sensor, based on velocity selective Raman transition, enables us to measure the momentum transferred to the atoms. A measurement with a statistical uncertainty of 4.4 10{sup -9}, in conjunction with a careful study of systematic effects (5 10{sup -9}), has led us to a determination of alpha with an uncertainty of 6.7 10{sup -9}: {alpha}{sup -1}(Rb) = 137.03599878 (91). This uncertainty is similar to the uncertainty of the best determinations of alpha based on atom interferometry. (author)

  12. STRUCTURAL FEATURES OF PLANT CHITINASES AND CHITIN-BINDING PROTEINS

    NARCIS (Netherlands)

    BEINTEMA, JJ

    1994-01-01

    Structural features of plant chitinases and chitin-binding proteins are discussed. Many of these proteins consist of multiple domains,of which the chitin-binding hevein domain is a predominant one. X-ray and NMR structures of representatives of the major classes of these proteins are available now,

  13. Structural health monitoring feature design by genetic programming

    International Nuclear Information System (INIS)

    Harvey, Dustin Y; Todd, Michael D

    2014-01-01

    Structural health monitoring (SHM) systems provide real-time damage and performance information for civil, aerospace, and other high-capital or life-safety critical structures. Conventional data processing involves pre-processing and extraction of low-dimensional features from in situ time series measurements. The features are then input to a statistical pattern recognition algorithm to perform the relevant classification or regression task necessary to facilitate decisions by the SHM system. Traditional design of signal processing and feature extraction algorithms can be an expensive and time-consuming process requiring extensive system knowledge and domain expertise. Genetic programming, a heuristic program search method from evolutionary computation, was recently adapted by the authors to perform automated, data-driven design of signal processing and feature extraction algorithms for statistical pattern recognition applications. The proposed method, called Autofead, is particularly suitable to handle the challenges inherent in algorithm design for SHM problems where the manifestation of damage in structural response measurements is often unclear or unknown. Autofead mines a training database of response measurements to discover information-rich features specific to the problem at hand. This study provides experimental validation on three SHM applications including ultrasonic damage detection, bearing damage classification for rotating machinery, and vibration-based structural health monitoring. Performance comparisons with common feature choices for each problem area are provided demonstrating the versatility of Autofead to produce significant algorithm improvements on a wide range of problems. (paper)

  14. Temperature dependent evolution of the local electronic structure of atmospheric plasma treated carbon nanotubes: Near edge x-ray absorption fine structure study

    International Nuclear Information System (INIS)

    Roy, S. S.; Papakonstantinou, P.; Okpalugo, T. I. T.; Murphy, H.

    2006-01-01

    Near edge x-ray absorption fine structure (NEXAFS) spectroscopy has been employed to obtain the temperature dependent evolution of the electronic structure of acid treated carbon nanotubes, which were further modified by dielectric barrier discharge plasma processing in an ammonia atmosphere. The NEXAFS studies were performed from room temperature up to 900 deg. C. The presence of oxygen and nitrogen containing functional groups was observed in C K edge, N K edge, and O K edge NEXAFS spectra of the multiwalled carbon nanotubes. The N K edge spectra revealed three types of π* features, the source of which was decisively identified by their temperature dependent evolution. It was established that these features are attributed to pyridinelike, NO, and graphitelike structures, respectively. The O K edge indicated that both carbonyl (C=O), π*(CO), and ether C-O-C, σ*(CO), functionalities were present. Upon heating in a vacuum to 900 deg. C the π*(CO) resonances disappeared while the σ*(CO) resonances were still present confirming their higher thermal stability. Heating did not produce a significant change in the π* feature of the C K edge spectrum indicating that the tabular structure of the nanotubes is essentially preserved following the thermal decomposition of the functional groups on the nanotube surface

  15. Metallacyclopentadienes: structural features and coordination in transition metal complexes

    International Nuclear Information System (INIS)

    Dolgushin, Fedor M; Yanovsky, Aleksandr I; Antipin, Mikhail Yu

    2004-01-01

    Results of structural studies of polynuclear transition metal complexes containing the metallacyclopentadiene fragment are overviewed. The structural features of the complexes in relation to the nature of the substituents in the organic moiety of the metallacycles, the nature of the transition metals and their ligand environment are analysed. The main structural characteristics corresponding to different modes of coordination of metallacyclopentadienes to one or two additional metal centres are revealed.

  16. High-resolution x-ray spectroscopy of coherent bremsstrahlung fine structure

    International Nuclear Information System (INIS)

    Lund, M.W.

    1989-01-01

    The aim of this research was to provide experimental evidence for fine structure due to umklapp by distinct reciprocal lattice vectors in coherent bremsstrahlung spectra. The spontaneous emission of photons by relativistic electrons transversing thin crystals is made possible by recoil of the crystal, which absorbs momentum in multiples of ℎG where G is a reciprocal lattice vector. Previous work in the MeV-GeV beam energy range used detectors whose energy resolution was greater than 10%. By fitting a Johann wavelength dispersive spectrometer to a transmission electron microscope the author obtained coherent bremsstrahlung spectra of very high quality with energy resolution of 1%. Important to this result were also the fine angular collimation, small energy width of the electron beam in the microscope, and the accurate control of crystal orientation possible in a modern goniometer stage. The theory of the design of bent crystal x-ray spectrometers is extended to include effects of defocus and aberrations. The theory for diffraction from a stationary three dimensional grating due to a dipole radiator moving at relativistic speeds is derived as well as several other broadening mechanisms stemming from experimental variables. This dissertation provides the first experimental observations and corresponding theoretical background for the fine structure of coherent bremsstrahlung due to umklapp by different G-vectors in the same reciprocal lattice plane

  17. Solution spectroelectrochemical cell for in situ X-ray absorption fine structure

    International Nuclear Information System (INIS)

    Antonio, M.R.; Soderholm, L.

    1995-01-01

    A purpose-built spectroelectrochemical cell for in situ fluorescence XAFS (X-ray Absorption Fine Structure) measurements of bulk solution species during constant-potential electrolysis is described. The cell performance was demonstrated by the collection of europium L 3 -edge XANES (X-ray Absorption Near Edge Structure) throughout the course of electrolysis of an aqueous solution of EuCl 3 ·6H 2 O in 1 M H 2 SO 4 . The europium L 3 -edge resonances reported here for the Eu III and Eu II ions demonstrate that their 2p 3/2 → 5d electronic transition probabilities are not the same

  18. Fine structure and function of the alimentary epithelium in Artemia salina nauplii

    Energy Technology Data Exchange (ETDEWEB)

    Hootman, S R; Conte, F P

    1974-01-01

    The fine structure of the alimentary tract in the second instar nauplius of the brine shrimp, Artemia salina, has been described. The foregut and hindgut of the larva are composed of cuboidal epithelium which is cuticularized. The epithelium of the midgut and gastric caeca is columnar and is characterized by apical microvilli, basal membrane infolds, and abundant mitochondria. The structural characteristics of the midgut cells correlate with previous physiological and biochemical evidence on both adult and larval brine shrimp which indicates that the midgut plays an important role in absorption and osmoregulation in these animals.

  19. Understanding Structural Features of Microbial Lipases–-An Overview

    Directory of Open Access Journals (Sweden)

    John Geraldine Sandana Mala

    2008-01-01

    Full Text Available The structural elucidations of microbial lipases have been of prime interest since the 1980s. Knowledge of structural features plays an important role in designing and engineering lipases for specific purposes. Significant structural data have been presented for few microbial lipases, while, there is still a structure-deficit, that is, most lipase structures are yet to be resolved. A search for ‘lipase structure’ in the RCSB Protein Data Bank ( http://www.rcsb.org/pdb/ returns only 93 hits (as of September 2007 and, the NCBI database ( http://www.ncbi.nlm.nih.gov reports 89 lipase structures as compared to 14719 core nucleotide records. It is therefore worthwhile to consider investigations on the structural analysis of microbial lipases. This review is intended to provide a collection of resources on the instrumental, chemical and bioinformatics approaches for structure analyses. X-ray crystallography is a versatile tool for the structural biochemists and is been exploited till today. The chemical methods of recent interests include molecular modeling and combinatorial designs. Bioinformatics has surged striking interests in protein structural analysis with the advent of innumerable tools. Furthermore, a literature platform of the structural elucidations so far investigated has been presented with detailed descriptions as applicable to microbial lipases. A case study of Candida rugosa lipase (CRL has also been discussed which highlights important structural features also common to most lipases. A general profile of lipase has been vividly described with an overview of lipase research reviewed in the past.

  20. Dispersal, mating events and fine-scale genetic structure in the lesser flat-headed bats.

    Directory of Open Access Journals (Sweden)

    Panyu Hua

    Full Text Available Population genetic structure has important consequences in evolutionary processes and conservation genetics in animals. Fine-scale population genetic structure depends on the pattern of landscape, the permanent movement of individuals, and the dispersal of their genes during temporary mating events. The lesser flat-headed bat (Tylonycteris pachypus is a nonmigratory Asian bat species that roosts in small groups within the internodes of bamboo stems and the habitats are fragmented. Our previous parentage analyses revealed considerable extra-group mating in this species. To assess the spatial limits and sex-biased nature of gene flow in the same population, we used 20 microsatellite loci and mtDNA sequencing of the ND2 gene to quantify genetic structure among 54 groups of adult flat-headed bats, at nine localities in South China. AMOVA and F(ST estimates revealed significant genetic differentiation among localities. Alternatively, the pairwise F(ST values among roosting groups appeared to be related to the incidence of associated extra-group breeding, suggesting the impact of mating events on fine-scale genetic structure. Global spatial autocorrelation analyses showed positive genetic correlation for up to 3 km, indicating the role of fragmented habitat and the specialized social organization as a barrier in the movement of individuals among bamboo forests. The male-biased dispersal pattern resulted in weaker spatial genetic structure between localities among males than among females, and fine-scale analyses supported that relatedness levels within internodes were higher among females than among males. Finally, only females were more related to their same sex roost mates than to individuals from neighbouring roosts, suggestive of natal philopatry in females.

  1. Dispersal, mating events and fine-scale genetic structure in the lesser flat-headed bats.

    Science.gov (United States)

    Hua, Panyu; Zhang, Libiao; Guo, Tingting; Flanders, Jon; Zhang, Shuyi

    2013-01-01

    Population genetic structure has important consequences in evolutionary processes and conservation genetics in animals. Fine-scale population genetic structure depends on the pattern of landscape, the permanent movement of individuals, and the dispersal of their genes during temporary mating events. The lesser flat-headed bat (Tylonycteris pachypus) is a nonmigratory Asian bat species that roosts in small groups within the internodes of bamboo stems and the habitats are fragmented. Our previous parentage analyses revealed considerable extra-group mating in this species. To assess the spatial limits and sex-biased nature of gene flow in the same population, we used 20 microsatellite loci and mtDNA sequencing of the ND2 gene to quantify genetic structure among 54 groups of adult flat-headed bats, at nine localities in South China. AMOVA and F(ST) estimates revealed significant genetic differentiation among localities. Alternatively, the pairwise F(ST) values among roosting groups appeared to be related to the incidence of associated extra-group breeding, suggesting the impact of mating events on fine-scale genetic structure. Global spatial autocorrelation analyses showed positive genetic correlation for up to 3 km, indicating the role of fragmented habitat and the specialized social organization as a barrier in the movement of individuals among bamboo forests. The male-biased dispersal pattern resulted in weaker spatial genetic structure between localities among males than among females, and fine-scale analyses supported that relatedness levels within internodes were higher among females than among males. Finally, only females were more related to their same sex roost mates than to individuals from neighbouring roosts, suggestive of natal philopatry in females.

  2. A Nonlinear Transmission Line Model of the Cochlea With Temporal Integration Accounts for Duration Effects in Threshold Fine Structure

    DEFF Research Database (Denmark)

    Verhey, Jesko L.; Mauermann, Manfred; Epp, Bastian

    2017-01-01

    For normal-hearing listeners, auditory pure-tone thresholds in quiet often show quasi periodic fluctuations when measured with a high frequency resolution, referred to as threshold fine structure. Threshold fine structure is dependent on the stimulus duration, with smaller fluctuations for short...... than for long signals. The present study demonstrates how this effect can be captured by a nonlinear and active model of the cochlear in combination with a temporal integration stage. Since this cochlear model also accounts for fine structure and connected level dependent effects, it is superior...

  3. FeatureMap3D - a tool to map protein features and sequence conservation onto homologous structures in the PDB

    DEFF Research Database (Denmark)

    Wernersson, Rasmus; Rapacki, Krzysztof; Stærfeldt, Hans Henrik

    2006-01-01

    FeatureMap3D is a web-based tool that maps protein features onto 3D structures. The user provides sequences annotated with any feature of interest, such as post-translational modifications, protease cleavage sites or exonic structure and FeatureMap3D will then search the Protein Data Bank (PDB) f...

  4. 5 K extended X-ray absorption fine structure and 40 K 10-s resolved extended X-ray absorption fine structure studies of photolyzed carboxymyoglobin

    International Nuclear Information System (INIS)

    Teng, T.Y.; Huang, H.W.; Olah, G.A.

    1987-01-01

    A previous extended X-ray absorption fine structure (EXAFS) study of photolyzed carboxymyoglobin (MbCO) has provoked much discussion on the heme structure of the photoproduct (Mb*CO). The EXAFS interpretation that the Fe-Co distance increases by no more than 0.05 A following photodissociation has been regarded as inconsistent with optical, infrared, and magnetic susceptibility studies. The present experiment was performed with well-characterized dry film samples in which MbCO molecules were embedded in a poly(vinyl alcohol) matrix. The sample had a high protein concentration (12 mM) to yield adequate EXAFS signals but was very thin (40 μm) so that complete photolysis could be easily achieved by a single flash from a xenon lamp. Although the electronic state of Mb*CO resembles that of deoxymyoglobin (deoxy-Mb), direct comparison of EXAFS spectra indicates that structurally Mb*CO is much closer to MbCO than to deoxy-Mb. Our EXAFS analysis shows that photolysis of MbCO at 5 K leads to a stable intermediate state in which CO has moved away from iron by a distance of 0.27-0.45 A, but the 5-coordinate heme structure is strained in a form similar to that of MbCO; the resolution of the CO position depends on the structure parameters of MbCO which we use as a reference for the analysis of Mb*CO. At 40 K, from 1 to 10 s after photolysis, 42% of the photoproduct has relaxed to the ground state, and the EXAFS spectrum of the remaining photoproduct is indistinguishable from that of the 5 K photoproduct

  5. Lack of sex-biased dispersal promotes fine-scale genetic structure in alpine ungulates

    Science.gov (United States)

    Roffler, Gretchen H.; Talbot, Sandra L.; Luikart, Gordon; Sage, George K.; Pilgrim, Kristy L.; Adams, Layne G.; Schwartz, Michael K.

    2014-01-01

    Identifying patterns of fine-scale genetic structure in natural populations can advance understanding of critical ecological processes such as dispersal and gene flow across heterogeneous landscapes. Alpine ungulates generally exhibit high levels of genetic structure due to female philopatry and patchy configuration of mountain habitats. We assessed the spatial scale of genetic structure and the amount of gene flow in 301 Dall’s sheep (Ovis dalli dalli) at the landscape level using 15 nuclear microsatellites and 473 base pairs of the mitochondrial (mtDNA) control region. Dall’s sheep exhibited significant genetic structure within contiguous mountain ranges, but mtDNA structure occurred at a broader geographic scale than nuclear DNA within the study area, and mtDNA structure for other North American mountain sheep populations. No evidence of male-mediated gene flow or greater philopatry of females was observed; there was little difference between markers with different modes of inheritance (pairwise nuclear DNA F ST = 0.004–0.325; mtDNA F ST = 0.009–0.544), and males were no more likely than females to be recent immigrants. Historical patterns based on mtDNA indicate separate northern and southern lineages and a pattern of expansion following regional glacial retreat. Boundaries of genetic clusters aligned geographically with prominent mountain ranges, icefields, and major river valleys based on Bayesian and hierarchical modeling of microsatellite and mtDNA data. Our results suggest that fine-scale genetic structure in Dall’s sheep is influenced by limited dispersal, and structure may be weaker in populations occurring near ancestral levels of density and distribution in continuous habitats compared to other alpine ungulates that have experienced declines and marked habitat fragmentation.

  6. Analysis of Conserved Structural Features of Selenoprotein K | Al ...

    African Journals Online (AJOL)

    Selenium plays important roles in human health and these roles may be exerted through its presence in selenoproteins. Among the 25 selenoproteins in human is selenoprotein K (SelK) whose exact function is still unclear. Here, we investigated the conserved structural features of SelK using bioinformatics as an approach ...

  7. The fine structure of the sperm of the round goby (Neogobius melanostomus)

    Science.gov (United States)

    Allen, Jeffrey D.; Walker, Glenn K.; Nichols, Susan J.; Sorenson, Dorothy

    2004-01-01

    The fine structural details of the spermatozoon of the round goby are presented for the first time in this study. Scanning and transmission electron microscopic examination of testis reveals an anacrosomal spermatozoon with a slightly elongate head and uniformly compacted chromatin. The midpiece contains a single, spherical mitochondrion. Two perpendicularly oriented centrioles lie in a deep, eccentric nuclear fossa with no regularly observed connection to the nucleus. The flagellum develops bilateral fins soon after emerging from the fossa; each extends approximately 1 A?m from the axoneme and persists nearly the length of the flagellum.

  8. Fine-structural effects of 1200-R abdominal x irradiation on rat intestinal epithelium

    International Nuclear Information System (INIS)

    Lieb, R.J.; McDonald, T.F.; McKenney, J.R.

    1977-01-01

    Male Charles River CD rats were shielded from the xiphoid process cranially with lead and were exposed to 1200-R abdominal x irradiation. Animals were sacrificed at 1 through 4 days following irradiation and tissues from both ileum and jejunum were prepared for electron microscopic examination. At the fine-structural level early changes were confined to a proliferation and dilation of smooth endoplasmic reticulum and to an increase in the number of lysosomes. At 4 days postirradiation, cells covering the villi were cuboidal rather than columnar and appeared to be immature crypt-type cells. The appearance of these cells was coincident with the onset of diarrhea in these animals

  9. Experimental determination of the relativistic fine-structure splitting in pionic Ti and Fe atoms

    International Nuclear Information System (INIS)

    Wang, K.; Boehm, F.; Bovet, E.; Hahn, A.A.; Henrikson, H.E.; Miller, J.P.; Powers, R.J.; Vogel, P.; Vuilleumier, J.; Kunselman, A.R.

    1980-01-01

    Using a high-resolution crystal spectrometer we have measured the relativistic angular-momentum splittings of the 5g-4f and 5f-4d transitions in pionic Ti and Fe atoms. The observed fine-structure splittings of 85.3 +- 3.0 eV in π - Ti and 158.5 +- 7.8 eV in π - Fe agree with the calculated splittings of 88.5 and 167.6 eV, respectively, arising from the Klein-Gordon equation and from small corrections due to vacuum polarization, strong interaction, and electron screening

  10. Evolution of the fine-structure constant in runaway dilaton models

    Energy Technology Data Exchange (ETDEWEB)

    Martins, C.J.A.P., E-mail: Carlos.Martins@astro.up.pt [Centro de Astrofísica, Universidade do Porto, Rua das Estrelas, 4150-762 Porto (Portugal); Instituto de Astrofísica e Ciências do Espaço, CAUP, Rua das Estrelas, 4150-762 Porto (Portugal); Vielzeuf, P.E., E-mail: pvielzeuf@ifae.es [Institut de Física d' Altes Energies, Universitat Autònoma de Barcelona, E-08193 Bellaterra (Barcelona) (Spain); Martinelli, M., E-mail: martinelli@thphys.uni-heidelberg.de [Institute for Theoretical Physics, University of Heidelberg, Philosophenweg 16, 69120, Heidelberg (Germany); Calabrese, E., E-mail: erminia.calabrese@astro.ox.ac.uk [Sub-department of Astrophysics, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); Pandolfi, S., E-mail: stefania@dark-cosmology.dk [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen (Denmark)

    2015-04-09

    We study the detailed evolution of the fine-structure constant α in the string-inspired runaway dilaton class of models of Damour, Piazza and Veneziano. We provide constraints on this scenario using the most recent α measurements and discuss ways to distinguish it from alternative models for varying α. For model parameters which saturate bounds from current observations, the redshift drift signal can differ considerably from that of the canonical ΛCDM paradigm at high redshifts. Measurements of this signal by the forthcoming European Extremely Large Telescope (E-ELT), together with more sensitive α measurements, will thus dramatically constrain these scenarios.

  11. Evolution of the fine-structure constant in runaway dilaton models

    International Nuclear Information System (INIS)

    Martins, C.J.A.P.; Vielzeuf, P.E.; Martinelli, M.; Calabrese, E.; Pandolfi, S.

    2015-01-01

    We study the detailed evolution of the fine-structure constant α in the string-inspired runaway dilaton class of models of Damour, Piazza and Veneziano. We provide constraints on this scenario using the most recent α measurements and discuss ways to distinguish it from alternative models for varying α. For model parameters which saturate bounds from current observations, the redshift drift signal can differ considerably from that of the canonical ΛCDM paradigm at high redshifts. Measurements of this signal by the forthcoming European Extremely Large Telescope (E-ELT), together with more sensitive α measurements, will thus dramatically constrain these scenarios

  12. Surface extended x-ray absorption fine structure of low-Z absorbates using fluorescence detection

    International Nuclear Information System (INIS)

    Stoehr, J.; Kollin, E.B.; Fischer, D.A.; Hastings, J.B.; Zaera, F.; Sette, F.

    1985-05-01

    Comparison of x-ray fluorescence yield (FY) and electron yield surface extended x-ray absorption fine structure spectra above the S K-edge for c(2 x 2) S on Ni(100) reveals an order of magnitude higher sensitivity of the FY technique. Using FY detection, thiophene (C 4 H 4 S) chemisorption on Ni(100) is studied with S coverages down to 0.08 monolayer. The molecule dissociates at temperatures as low as 100K by interaction with fourfold hollow Ni sites. Blocking of these sites by oxygen leaves the molecule intact

  13. Outlier SNP markers reveal fine-scale genetic structuring across European hake populations (Merluccius merluccius)

    DEFF Research Database (Denmark)

    Milano, I.; Babbucci, M.; Cariani, A.

    2014-01-01

    fishery. Analysis of 850 individuals from 19 locations across the entire distribution range showed evidence for several outlier loci, with significantly higher resolving power. While 299 putatively neutral SNPs confirmed the genetic break between basins (FCT = 0.016) and weak differentiation within basins...... even when neutral markers provide genetic homogeneity across populations. Here, 381 SNPs located in transcribed regions were used to assess largeand fine-scale population structure in the European hake (Merluccius merluccius), a widely distributed demersal species of high priority for the European...

  14. Polarized Fine Structure in the Photoluminescence Excitation Spectrum of a Negatively Charged Quantum Dot

    Science.gov (United States)

    Ware, M. E.; Stinaff, E. A.; Gammon, D.; Doty, M. F.; Bracker, A. S.; Gershoni, D.; Korenev, V. L.; Bădescu, Ş. C.; Lyanda-Geller, Y.; Reinecke, T. L.

    2005-10-01

    We report polarized photoluminescence excitation spectroscopy of the negative trion in single charge-tunable InAs/GaAs quantum dots. The spectrum exhibits a p-shell resonance with polarized fine structure arising from the direct excitation of the electron spin triplet states. The energy splitting arises from the axially symmetric electron-hole exchange interaction. The magnitude and sign of the polarization are understood from the spin character of the triplet states and a small amount of quantum dot asymmetry, which mixes the wave functions through asymmetric e-e and e-h exchange interactions.

  15. Fine structure and optical pumping of spins in individual semiconductor quantum dots

    Science.gov (United States)

    Bracker, Allan S.; Gammon, Daniel; Korenev, Vladimir L.

    2008-11-01

    We review spin properties of semiconductor quantum dots and their effect on optical spectra. Photoluminescence and other types of spectroscopy are used to probe neutral and charged excitons in individual quantum dots with high spectral and spatial resolution. Spectral fine structure and polarization reveal how quantum dot spins interact with each other and with their environment. By taking advantage of the selectivity of optical selection rules and spin relaxation, optical spin pumping of the ground state electron and nuclear spins is achieved. Through such mechanisms, light can be used to process spins for use as a carrier of information.

  16. Fine structure and optical pumping of spins in individual semiconductor quantum dots

    International Nuclear Information System (INIS)

    Bracker, Allan S; Gammon, Daniel; Korenev, Vladimir L

    2008-01-01

    We review spin properties of semiconductor quantum dots and their effect on optical spectra. Photoluminescence and other types of spectroscopy are used to probe neutral and charged excitons in individual quantum dots with high spectral and spatial resolution. Spectral fine structure and polarization reveal how quantum dot spins interact with each other and with their environment. By taking advantage of the selectivity of optical selection rules and spin relaxation, optical spin pumping of the ground state electron and nuclear spins is achieved. Through such mechanisms, light can be used to process spins for use as a carrier of information

  17. Extended X-ray absorption fine structure (EXAFS) studies of supported catalysts

    International Nuclear Information System (INIS)

    Joyner, R.W.

    1979-01-01

    Since the rebirth of interest in extended X-ray absorption fine structure there have been several studies of systems of catalytic interest. This note is a preliminary account of an investigation of supported platinum catalysts and NiO/Al 2 O 3 catalysts. Experiments were performed on pressed disc samples at the DESY synchrotron, Hamburg, using the EXAFS spectrometer. The synchrotron operated at 7 GeV energy with a circulating current of approximately 4 mA; spectrum accumulation time was typically 45 minutes. (author)

  18. EXANA, a program for analysing EXtended energy loss fine structures, EXELFS spectra

    International Nuclear Information System (INIS)

    Tafreshi, M.A.; Bohm, C.; Csillag, S.

    1992-09-01

    This paper is a users guide and reference manual for the EXANA, an IBM or IBM compatible PC-based program used for analysing extended fine structures occurring on the high energy side of the ionisation edges. The RDF (Radial Distance Function) obtained from this analysis contains information about the number, distance, and type of the nearby atoms, as well as the inelastic mean free path and disorder in distances from the centre atom to the atoms in a atomic shell around it. The program can be made available on request. (au)

  19. Sensitivity of ultracold-atom scattering experiments to variation of the fine-structure constant

    International Nuclear Information System (INIS)

    Borschevsky, A.; Beloy, K.; Flambaum, V. V.; Schwerdtfeger, P.

    2011-01-01

    We present numerical calculations for cesium and mercury to estimate the sensitivity of the scattering length to the variation of the fine-structure constant α. The method used follows the ideas of Chin and Flambaum [Phys. Rev. Lett. 96, 230801 (2006)], where the sensitivity to the variation of the electron-to-proton mass ratio β was considered. We demonstrate that for heavy systems, the sensitivity to the variation of α is of the same order of magnitude as to the variation of β. Near narrow Feshbach resonances, the enhancement of the sensitivity may exceed nine orders of magnitude.

  20. Fine structure of the giant M1 resonance in 90Zr.

    Science.gov (United States)

    Rusev, G; Tsoneva, N; Dönau, F; Frauendorf, S; Schwengner, R; Tonchev, A P; Adekola, A S; Hammond, S L; Kelley, J H; Kwan, E; Lenske, H; Tornow, W; Wagner, A

    2013-01-11

    The M1 excitations in the nuclide 90Zr have been studied in a photon-scattering experiment with monoenergetic and linearly polarized beams from 7 to 11 MeV. More than 40 J(π)=1+ states have been identified from observed ground-state transitions, revealing the fine structure of the giant M1 resonance with a centroid energy of 9 MeV and a sum strength of 4.17(56) μ(N)(2). The result for the total M1 strength and its fragmentation are discussed in the framework of the three-phonon quasiparticle-phonon model.

  1. Analysis of the local structure of AlN:Mn using X-ray absorption fine structure measurements

    Energy Technology Data Exchange (ETDEWEB)

    Miyajima, Takao [Materials Laboratories, Sony Corporation, 4-14-1 Asahi-cho, Atsugi-shi, Kanagawa 243-0014 (Japan); Kudo, Yoshihiro [Materials Analysis Lab., Sony Corporation, 4-18-1 Okada, Atsugi-shi, Kanagawa 243-0021 (Japan); Uruga, Tomoya [Japan Synchrotron Radiation Institute, 1-1-1 Kouto, Mikazuki-cho, Sayo-gun, Hyogo 679-5198 (Japan); Hara, Kazuhiko [Research Inst. of Electronics, Shizuoka Univ., 3-5-1 Johoku, Hamamatsu, Shizuoka 432-8011 (Japan)

    2006-06-15

    The local structure around the Mn atoms in MOCVD-grown AlN:Mn films which show Mn-related red-orange photoluminescence with a 600nm-peak at room temperature was investigated using the X-ray absorption fine structure (XAFS) measurements. We found that Mn atoms occupy Al lattice sites in the AlN film and that the Mn ions have a charge between +2 and +3. From these results, we think that the red-orange luminescence is caused by the transition of d-electrons in the Mn ions. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. Extended x-ray absorption fine structure: Studies of zinc-neutralized sulfonated polystyrene ionomers

    International Nuclear Information System (INIS)

    Ding, Y.S.; Yarusso, D.J.; Pan, H.K.D.; Cooper, S.L.

    1984-01-01

    Extended x-ray absorption fine structure (EXAFS) measurements were performed on a series of zinc-neutralized sulfonated polystyrene ionomers and the local structure around the zinc atom was determined. An interference effect in the EXAFS signal between sulfur and oxygen atoms was found to be significant in these materials. A model for the local structure in the zinc-neutralized sulfonated polystyrene ionomers is proposed which suggests a highly ordered tetrahedral coordination of oxygen around the zinc atoms at a distance of 1.97 +- 0.02 A. In addition there are four sulfur atoms and four oxygen atoms at a distance of 3.15 +- 0.05 A. No zinc-zinc coordination within 5 A was detected in this study

  3. Fine- and hyperfine structure investigations of the even-parity configuration system of the atomic holmium

    Science.gov (United States)

    Stefanska, D.; Ruczkowski, J.; Elantkowska, M.; Furmann, B.

    2018-04-01

    In this work new experimental results concerning the hyperfine structure (hfs) for the even-parity level system of the holmium atom (Ho I) were obtained; additionally, hfs data obtained recently as a by-product in investigations of the odd-parity level system were summarized. In the present work the values of the magnetic dipole and the electric quadrupole hfs constants A and B were determined for 24 even-parity levels, for 14 of them for the first time. On the basis of these results, as well as on available literature data, a parametric study of the fine structure and the hyperfine structure for the even-parity configurations of atomic holmium was performed. A multi-configuration fit of 7 configurations was carried out, taking into account second-order of the perturbation theory. For unknown electronic levels predicted values of the level energies and hfs constants are given, which can facilitate further experimental investigations.

  4. Revised description of the fine structure of in situ "zooxanthellae" genus Symbiodinium.

    Science.gov (United States)

    Wakefield, T S; Farmer, M A; Kempf, S C

    2000-08-01

    The fine structure of the symbiotic dinoflagellate genus Symbiodinium has been well described. All of the published descriptions are based on tissue that was fixed in standard aldehyde and osmium fixatives and dehydrated in an ethanol series before embedding. When the technique of freeze-substitution was used to fix tissue from Cassiopeia xamachana, Aiptasia pallida, and Phyllactis flosculifera and prepare it for embedding, thecal vesicles were revealed within the in situ symbionts of all three species. Although these structures have been identified in cultured symbionts, they have never been described in the in situ symbionts. A review of the literature has revealed several instances where thecal vesicles were either overlooked or identified incorrectly. Thus the formal description of the genus Symbiodinium, which describes the in situ symbionts, contains information that is based on artifact and should be revised. A revision of the genus is suggested, and the true nature of these structures and their significance in the symbiotic association are discussed.

  5. `Fingerprint' Fine Structure in the Solar Decametric Radio Spectrum Solar Physics

    Science.gov (United States)

    Zlotnik, E. Y.; Zaitsev, V. V.; Melnik, V. N.; Konovalenko, A. A.; Dorovskyy, V. V.

    2015-07-01

    We study a unique fine structure in the dynamic spectrum of the solar radio emission discovered by the UTR-2 radio telescope (Kharkiv, Ukraine) in the frequency band of 20 - 30 MHz. The structure was observed against the background of a broadband type IV radio burst and consisted of parallel drifting narrow bands of enhanced emission and absorption on the background emission. The observed structure differs from the widely known zebra pattern at meter and decimeter wavelengths by the opposite directions of the frequency drift within a single stripe at a given time. We show that the observed properties can be understood in the framework of the radiation mechanism by virtue of the double plasma resonance effect in a nonuniform coronal magnetic trap. We propose a source model providing the observed frequency drift of the stripes.

  6. Fine Structure of Tibetan Kefir Grains and Their Yeast Distribution, Diversity, and Shift

    Science.gov (United States)

    Lu, Man; Wang, Xingxing; Sun, Guowei; Qin, Bing; Xiao, Jinzhou; Yan, Shuling; Pan, Yingjie; Wang, Yongjie

    2014-01-01

    Tibetan kefir grains (TKGs), a kind of natural starter for fermented milk in Tibet, China, host various microorganisms of lactic acid bacteria, yeasts, and occasionally acetic acid bacteria in a polysaccharide/protein matrix. In the present study, the fine structure of TKGs was studied to shed light on this unusual symbiosis with stereomicroscopy and thin sections. The results reveal that TKGs consist of numerous small grain units, which are characterized by a hollow globular structure with a diameter between 2.0 and 9.0 mm and a wall thickness of approximately 200 µm. A polyhedron-like net structure, formed mainly by the bacteria, was observed in the wall of the grain units, which has not been reported previously to our knowledge. Towards the inside of the grain unit, the polyhedron-like net structures became gradually larger in diameter and fewer in number. Such fine structures may play a crucial role in the stability of the grains. Subsequently, the distribution, diversity, and shift of yeasts in TKGs were investigated based on thin section, scanning electron microscopy, cloning and sequencing of D1/D2 of the 26S rRNA gene, real-time quantitative PCR, and in situ hybridization with specific fluorescence-labeled oligonucleotide probes. These show that (i) yeasts appear to localize on the outer surface of the grains and grow normally together to form colonies embedded in the bacterial community; (ii) the diversity of yeasts is relatively low on genus level with three dominant species – Saccharomyces cerevisiae, Kluyveromyces marxianus, and Yarrowia lipolytica; (iii) S. cerevisiae is the stable predominant yeast species, while the composition of Kluyveromyces and Yarrowia are subject to change over time. Our results indicate that TKGs are relatively stable in structure, and culture conditions to some extent shape the microbial community and interaction in kefir grains. These findings pave the way for further study of the specific symbiotic associations between S

  7. Fine structure of Tibetan kefir grains and their yeast distribution, diversity, and shift.

    Directory of Open Access Journals (Sweden)

    Man Lu

    Full Text Available Tibetan kefir grains (TKGs, a kind of natural starter for fermented milk in Tibet, China, host various microorganisms of lactic acid bacteria, yeasts, and occasionally acetic acid bacteria in a polysaccharide/protein matrix. In the present study, the fine structure of TKGs was studied to shed light on this unusual symbiosis with stereomicroscopy and thin sections. The results reveal that TKGs consist of numerous small grain units, which are characterized by a hollow globular structure with a diameter between 2.0 and 9.0 mm and a wall thickness of approximately 200 µm. A polyhedron-like net structure, formed mainly by the bacteria, was observed in the wall of the grain units, which has not been reported previously to our knowledge. Towards the inside of the grain unit, the polyhedron-like net structures became gradually larger in diameter and fewer in number. Such fine structures may play a crucial role in the stability of the grains. Subsequently, the distribution, diversity, and shift of yeasts in TKGs were investigated based on thin section, scanning electron microscopy, cloning and sequencing of D1/D2 of the 26S rRNA gene, real-time quantitative PCR, and in situ hybridization with specific fluorescence-labeled oligonucleotide probes. These show that (i yeasts appear to localize on the outer surface of the grains and grow normally together to form colonies embedded in the bacterial community; (ii the diversity of yeasts is relatively low on genus level with three dominant species--Saccharomyces cerevisiae, Kluyveromyces marxianus, and Yarrowia lipolytica; (iii S. cerevisiae is the stable predominant yeast species, while the composition of Kluyveromyces and Yarrowia are subject to change over time. Our results indicate that TKGs are relatively stable in structure, and culture conditions to some extent shape the microbial community and interaction in kefir grains. These findings pave the way for further study of the specific symbiotic

  8. Linking structural features of protein complexes and biological function.

    Science.gov (United States)

    Sowmya, Gopichandran; Breen, Edmond J; Ranganathan, Shoba

    2015-09-01

    Protein-protein interaction (PPI) establishes the central basis for complex cellular networks in a biological cell. Association of proteins with other proteins occurs at varying affinities, yet with a high degree of specificity. PPIs lead to diverse functionality such as catalysis, regulation, signaling, immunity, and inhibition, playing a crucial role in functional genomics. The molecular principle of such interactions is often elusive in nature. Therefore, a comprehensive analysis of known protein complexes from the Protein Data Bank (PDB) is essential for the characterization of structural interface features to determine structure-function relationship. Thus, we analyzed a nonredundant dataset of 278 heterodimer protein complexes, categorized into major functional classes, for distinguishing features. Interestingly, our analysis has identified five key features (interface area, interface polar residue abundance, hydrogen bonds, solvation free energy gain from interface formation, and binding energy) that are discriminatory among the functional classes using Kruskal-Wallis rank sum test. Significant correlations between these PPI interface features amongst functional categories are also documented. Salt bridges correlate with interface area in regulator-inhibitors (r = 0.75). These representative features have implications for the prediction of potential function of novel protein complexes. The results provide molecular insights for better understanding of PPIs and their relation to biological functions. © 2015 The Protein Society.

  9. The variation of the fine-structure constant from disformal couplings

    Energy Technology Data Exchange (ETDEWEB)

    De Bruck, Carsten van; Mifsud, Jurgen [Consortium for Fundamental Physics, School of Mathematics and Statistics, University of Sheffield, Hounsfield Road, Sheffield S3 7RH (United Kingdom); Nunes, Nelson J., E-mail: c.vandebruck@sheffield.ac.uk, E-mail: jmifsud1@sheffield.ac.uk, E-mail: njnunes@fc.ul.pt [Instituto de Astrofísica e Ciências do Espaço, Faculdade de Ciências da Universidade de Lisboa, Campo Grande, PT1749-016 Lisboa (Portugal)

    2015-12-01

    We study a theory in which the electromagnetic field is disformally coupled to a scalar field, in addition to a usual non-minimal electromagnetic coupling. We show that disformal couplings modify the expression for the fine-structure constant, α. As a result, the theory we consider can explain the non-zero reported variation in the evolution of α by purely considering disformal couplings. We also find that if matter and photons are coupled in the same way to the scalar field, disformal couplings itself do not lead to a variation of the fine-structure constant. A number of scenarios are discussed consistent with the current astrophysical, geochemical, laboratory and the cosmic microwave background radiation constraints on the cosmological evolution of α. The models presented are also consistent with the current type Ia supernovae constraints on the effective dark energy equation of state. We find that the Oklo bound in particular puts strong constraints on the model parameters. From our numerical results, we find that the introduction of a non-minimal electromagnetic coupling enhances the cosmological variation in α. Better constrained data is expected to be reported by ALMA and with the forthcoming generation of high-resolution ultra-stable spectrographs such as PEPSI, ESPRESSO, and ELT-HIRES. Furthermore, an expected increase in the sensitivity of molecular and nuclear clocks will put a more stringent constraint on the theory.

  10. The variation of the fine-structure constant from disformal couplings

    International Nuclear Information System (INIS)

    De Bruck, Carsten van; Mifsud, Jurgen; Nunes, Nelson J.

    2015-01-01

    We study a theory in which the electromagnetic field is disformally coupled to a scalar field, in addition to a usual non-minimal electromagnetic coupling. We show that disformal couplings modify the expression for the fine-structure constant, α. As a result, the theory we consider can explain the non-zero reported variation in the evolution of α by purely considering disformal couplings. We also find that if matter and photons are coupled in the same way to the scalar field, disformal couplings itself do not lead to a variation of the fine-structure constant. A number of scenarios are discussed consistent with the current astrophysical, geochemical, laboratory and the cosmic microwave background radiation constraints on the cosmological evolution of α. The models presented are also consistent with the current type Ia supernovae constraints on the effective dark energy equation of state. We find that the Oklo bound in particular puts strong constraints on the model parameters. From our numerical results, we find that the introduction of a non-minimal electromagnetic coupling enhances the cosmological variation in α. Better constrained data is expected to be reported by ALMA and with the forthcoming generation of high-resolution ultra-stable spectrographs such as PEPSI, ESPRESSO, and ELT-HIRES. Furthermore, an expected increase in the sensitivity of molecular and nuclear clocks will put a more stringent constraint on the theory

  11. Measurement of the fine-structure constant as a test of the Standard Model

    Science.gov (United States)

    Parker, Richard H.; Yu, Chenghui; Zhong, Weicheng; Estey, Brian; Müller, Holger

    2018-04-01

    Measurements of the fine-structure constant α require methods from across subfields and are thus powerful tests of the consistency of theory and experiment in physics. Using the recoil frequency of cesium-133 atoms in a matter-wave interferometer, we recorded the most accurate measurement of the fine-structure constant to date: α = 1/137.035999046(27) at 2.0 × 10‑10 accuracy. Using multiphoton interactions (Bragg diffraction and Bloch oscillations), we demonstrate the largest phase (12 million radians) of any Ramsey-Bordé interferometer and control systematic effects at a level of 0.12 part per billion. Comparison with Penning trap measurements of the electron gyromagnetic anomaly ge ‑ 2 via the Standard Model of particle physics is now limited by the uncertainty in ge ‑ 2; a 2.5σ tension rejects dark photons as the reason for the unexplained part of the muon’s magnetic moment at a 99% confidence level. Implications for dark-sector candidates and electron substructure may be a sign of physics beyond the Standard Model that warrants further investigation.

  12. X-ray absorption fine structure spectroscopic determination of plutonium speciation at the Rocky Flats Environmental Technology Site

    International Nuclear Information System (INIS)

    Lezama-pacheco, Juan S.; Conradson, Steven D.; Clark, David L.

    2008-01-01

    X-ray Absorption Fine Structure spectroscopy was used to probe the speciation of the ppm level Pu in thirteen soil and concrete samples from the Rocky Flats Environmental Technology Site in support of the site remediation effort that has been successfully completed since these measurements. In addition to X-ray Absorption Near Edge Spectra, two of the samples yielded Extended X-ray Absorption Fine Structure spectra that could be analyzed by curve-fits. Most of these spectra exhibited features consistent with PU(IV), and more specificaJly, PuO 2+x -type speciation. Two were ambiguous, possibly indicating that Pu that was originally present in a different form was transforming into PuO 2+x , and one was interpreted as demonstrating the presence of an unusual Pu(VI) compound, consistent with its source being spills from a PUREX purification line onto a concrete floor and the resultant extreme conditions. These experimental results therefore validated models that predicted that insoluble PuO 2+x would be the most stable form of Pu in equilibrium with air and water even when the source terms were most likely Pu metal with organic compounds or a Pu fire. A corollary of these models' predictions and other in situ observations is therefore that the minimal transport of Pu that occurred on the site was via the resuspension and mobilization of colloidal particles. Under these conditions, the small amounts of diffusely distributed Pu that were left on the site after its remediation pose only a negligible hazard.

  13. Local topography shapes fine-scale spatial genetic structure in the Arkansas Valley evening primrose, Oenothera harringtonii (Onagraceae).

    Science.gov (United States)

    Rhodes, Matthew K; Fant, Jeremie B; Skogen, Krissa A

    2014-01-01

    Identifying factors that shape the spatial distribution of genetic variation is crucial to understanding many population- and landscape-level processes. In this study, we explore fine-scale spatial genetic structure in Oenothera harringtonii (Onagraceae), an insect-pollinated, gravity-dispersed herb endemic to the grasslands of south-central and southeastern Colorado, USA. We genotyped 315 individuals with 11 microsatellite markers and utilized a combination of spatial autocorrelation analyses and landscape genetic models to relate life history traits and landscape features to dispersal processes. Spatial genetic structure was consistent with theoretical expectations of isolation by distance, but this pattern was weak (Sp = 0.00374). Anisotropic analyses indicated that spatial genetic structure was markedly directional, in this case consistent with increased dispersal along prominent slopes. Landscape genetic models subsequently confirmed that spatial genetic variation was significantly influenced by local topographic heterogeneity, specifically that geographic distance, elevation and aspect were important predictors of spatial genetic structure. Among these variables, geographic distance was ~68% more important than elevation in describing spatial genetic variation, and elevation was ~42% more important than aspect after removing the effect of geographic distance. From these results, we infer a mechanism of hydrochorous seed dispersal along major drainages aided by seasonal monsoon rains. Our findings suggest that landscape features may shape microevolutionary processes at much finer spatial scales than typically considered, and stress the importance of considering how particular dispersal vectors are influenced by their environmental context. © The American Genetic Association 2014. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  14. Extended x-ray absorption fine structure (EXAFS): a novel probe for local structure of glassy solids

    International Nuclear Information System (INIS)

    Wong, J.

    1979-01-01

    The extended x-ray absorption fine structure (EXAFS) is the oscillation in the absorption coefficient extending a few hundred eVs on the high energy side of an x-ray absorption edge. This mode of spectroscopy has recently been realized to be a powerful tool in probing the local atomic structure of all states of matter, particularly with the advent of intense synchrotron radiation. More importantly is the unique ability of EXAFS to probe the structure and dynamics around individual atomic species in a multi-atomic system. In this paper, the physical processes associated with the EXAFS phenomenon will be discussed. Experimental results obtained at the Stanford Synchrotron Radiation Laboratory on some oxide and metallic glasses will be presented. The local structure in these materials are elucidated using a Fourier transform technique

  15. Estimation of non-linear effective permeability of magnetic materials with fine structure

    International Nuclear Information System (INIS)

    Waki, H.; Igarashi, H.; Honma, T.

    2006-01-01

    This paper describes a homogenization method for magnetic materials with fine structure. In this method, the structures of the magnetic materials are assumed to be periodic, and the unit cell is defined. The effective permeability is determined on the basis of magnetic energy balance in the unit cell. This method can be applied not only for linear problems but also for non-linear ones. In this paper, estimation of the effective permeability of non-linear magnetic materials by using the homogenization method is described in detail, and then the validity for the non-liner problems is tested for two-dimensional problems. It is shown that this homogenization method gives accurate non-linear effective permeability

  16. Understanding Protein-Protein Interactions Using Local Structural Features

    DEFF Research Database (Denmark)

    Planas-Iglesias, Joan; Bonet, Jaume; García-García, Javier

    2013-01-01

    Protein-protein interactions (PPIs) play a relevant role among the different functions of a cell. Identifying the PPI network of a given organism (interactome) is useful to shed light on the key molecular mechanisms within a biological system. In this work, we show the role of structural features...... interacting and non-interacting protein pairs to classify the structural features that sustain the binding (or non-binding) behavior. Our study indicates that not only the interacting region but also the rest of the protein surface are important for the interaction fate. The interpretation...... to score the likelihood of the interaction between two proteins and to develop a method for the prediction of PPIs. We have tested our method on several sets with unbalanced ratios of interactions and non-interactions to simulate real conditions, obtaining accuracies higher than 25% in the most unfavorable...

  17. Structural conceptual models of water-conducting features at Aespoe

    International Nuclear Information System (INIS)

    Bossart, P.; Mazurek, M.; Hermansson, Jan

    1998-01-01

    Within the framework of the Fracture Classification and Characterization Project (FCC), water conducting features (WCF) in the Aespoe tunnel system and on the surface of Aespoe Island are being characterized over a range of scales. The larger-scale hierarchies of WCF are mostly constituted of fault arrays, i.e. brittle structures that accommodated episodes of shear strain. The smaller-scale WCF (contained within blocks 1 m. Structural evidence indicates that the fractures within the TRUE-1 block constitute an interconnected system with a pronounced anisotropy

  18. Critical Features of Fragment Libraries for Protein Structure Prediction.

    Science.gov (United States)

    Trevizani, Raphael; Custódio, Fábio Lima; Dos Santos, Karina Baptista; Dardenne, Laurent Emmanuel

    2017-01-01

    The use of fragment libraries is a popular approach among protein structure prediction methods and has proven to substantially improve the quality of predicted structures. However, some vital aspects of a fragment library that influence the accuracy of modeling a native structure remain to be determined. This study investigates some of these features. Particularly, we analyze the effect of using secondary structure prediction guiding fragments selection, different fragments sizes and the effect of structural clustering of fragments within libraries. To have a clearer view of how these factors affect protein structure prediction, we isolated the process of model building by fragment assembly from some common limitations associated with prediction methods, e.g., imprecise energy functions and optimization algorithms, by employing an exact structure-based objective function under a greedy algorithm. Our results indicate that shorter fragments reproduce the native structure more accurately than the longer. Libraries composed of multiple fragment lengths generate even better structures, where longer fragments show to be more useful at the beginning of the simulations. The use of many different fragment sizes shows little improvement when compared to predictions carried out with libraries that comprise only three different fragment sizes. Models obtained from libraries built using only sequence similarity are, on average, better than those built with a secondary structure prediction bias. However, we found that the use of secondary structure prediction allows greater reduction of the search space, which is invaluable for prediction methods. The results of this study can be critical guidelines for the use of fragment libraries in protein structure prediction.

  19. X-ray Absorption Fine Structure (XAFS) Studies of Oxide Glasses—A 45-Year Overview

    Science.gov (United States)

    Zanotto, Edgar Dutra

    2018-01-01

    X-ray Absorption Fine Structure (XAFS) spectroscopy has been widely used to characterize the short-range order of glassy materials since the theoretical basis was established 45 years ago. Soon after the technique became accessible, mainly due to the existence of Synchrotron laboratories, a wide range of glassy materials was characterized. Silicate glasses have been the most studied because they are easy to prepare, they have commercial value and are similar to natural glasses, but borate, germanate, phosphate, tellurite and other less frequent oxide glasses have also been studied. In this manuscript, we review reported advances in the structural characterization of oxide-based glasses using this technique. A focus is on structural characterization of transition metal ions, especially Ti, Fe, and Ni, and their role in different properties of synthetic oxide-based glasses, as well as their important function in the formation of natural glasses and magmas, and in nucleation and crystallization. We also give some examples of XAFS applications for structural characterization of glasses submitted to high pressure, glasses used to store radioactive waste and medieval glasses. This updated, comprehensive review will likely serve as a useful guide to clarify the details of the short-range structure of oxide glasses. PMID:29382102

  20. Reduced fine-scale spatial genetic structure in grazed populations of Dianthus carthusianorum.

    Science.gov (United States)

    Rico, Y; Wagner, H H

    2016-11-01

    Strong spatial genetic structure in plant populations can increase homozygosity, reducing genetic diversity and adaptive potential. The strength of spatial genetic structure largely depends on rates of seed dispersal and pollen flow. Seeds without dispersal adaptations are likely to be dispersed over short distances within the vicinity of the mother plant, resulting in spatial clustering of related genotypes (fine-scale spatial genetic structure, hereafter spatial genetic structure (SGS)). However, primary seed dispersal by zoochory can promote effective dispersal, increasing the mixing of seeds and influencing SGS within plant populations. In this study, we investigated the effects of seed dispersal by rotational sheep grazing on the strength of SGS and genetic diversity using 11 nuclear microsatellites for 49 populations of the calcareous grassland forb Dianthus carthusianorum. Populations connected by rotational sheep grazing showed significantly weaker SGS and higher genetic diversity than populations in ungrazed grasslands. Independent of grazing treatment, small populations showed significantly stronger SGS and lower genetic diversity than larger populations, likely due to genetic drift. A lack of significant differences in the strength of SGS and genetic diversity between populations that were recently colonized and pre-existing populations suggested that populations colonized after the reintroduction of rotational sheep grazing were likely founded by colonists from diverse source populations. We conclude that dispersal by rotational sheep grazing has the potential to considerably reduce SGS within D. carthusianorum populations. Our study highlights the effectiveness of landscape management by rotational sheep grazing to importantly reduce genetic structure at local scales within restored plant populations.

  1. PROPERTIES AND MODELING OF UNRESOLVED FINE STRUCTURE LOOPS OBSERVED IN THE SOLAR TRANSITION REGION BY IRIS

    Energy Technology Data Exchange (ETDEWEB)

    Brooks, David H. [College of Science, George Mason University, 4400 University Drive, Fairfax, VA 22030 (United States); Reep, Jeffrey W.; Warren, Harry P. [Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States)

    2016-08-01

    Recent observations from the Interface Region Imaging Spectrograph ( IRIS ) have discovered a new class of numerous low-lying dynamic loop structures, and it has been argued that they are the long-postulated unresolved fine structures (UFSs) that dominate the emission of the solar transition region. In this letter, we combine IRIS measurements of the properties of a sample of 108 UFSs (intensities, lengths, widths, lifetimes) with one-dimensional non-equilibrium ionization simulations, using the HYDRAD hydrodynamic model to examine whether the UFSs are now truly spatially resolved in the sense of being individual structures rather than being composed of multiple magnetic threads. We find that a simulation of an impulsively heated single strand can reproduce most of the observed properties, suggesting that the UFSs may be resolved, and the distribution of UFS widths implies that they are structured on a spatial scale of 133 km on average. Spatial scales of a few hundred kilometers appear to be typical for a range of chromospheric and coronal structures, and we conjecture that this could be an important clue for understanding the coronal heating process.

  2. WAVELENGTH ACCURACY OF THE KECK HIRES SPECTROGRAPH AND MEASURING CHANGES IN THE FINE STRUCTURE CONSTANT

    International Nuclear Information System (INIS)

    Griest, Kim; Whitmore, Jonathan B.; Wolfe, Arthur M.; Prochaska, J. Xavier; Howk, J. Christopher; Marcy, Geoffrey W.

    2010-01-01

    We report on an attempt to accurately wavelength calibrate four nights of data taken with the Keck HIRES spectrograph on QSO PHL957, for the purpose of determining whether the fine structure constant was different in the past. Using new software and techniques, we measured the redshifts of various Ni II, Fe II, Si II, etc. lines in a damped Lyα system at z = 2.309. Roughly half the data were taken through the Keck iodine cell which contains thousands of well calibrated iodine lines. Using these iodine exposures to calibrate the normal Th-Ar Keck data pipeline output, we found absolute wavelength offsets of 500 m s -1 to 1000 m s -1 with drifts of more than 500 m s -1 over a single night, and drifts of nearly 2000 m s -1 over several nights. These offsets correspond to an absolute redshift of uncertainty of about Δz ∼ 10 -5 (Δλ ∼ 0.02 A), with daily drifts of around Δz ∼ 5 x 10 -6 (Δλ ∼ 0.01 A), and multiday drifts of nearly Δz ∼ 2 x 10 -5 (∼0.04 A). The causes of the wavelength offsets are not known, but since claimed shifts in the fine structure constant would result in velocity shifts of less than 100 m s -1 , this level of systematic uncertainty may make it difficult to use Keck HIRES data to constrain the change in the fine structure constant. Using our calibrated data, we applied both our own fitting software and standard fitting software to measure Δα/α, but discovered that we could obtain results ranging from significant detection of either sign, to strong null limits, depending upon which sets of lines and which fitting method were used. We thus speculate that the discrepant results on Δα/α reported in the literature may be due to random fluctuations coming from underestimated systematic errors in wavelength calibration and fitting procedure.

  3. Fine structure of the mineralized teeth of the chiton Acanthopleura echinata (Mollusca: Polyplacophora).

    Science.gov (United States)

    Wealthall, Rosamund J; Brooker, Lesley R; Macey, David J; Griffin, Brendan J

    2005-08-01

    The major lateral teeth of the chiton Acanthopleura echinata are composite structures composed of three distinct mineral zones: a posterior layer of magnetite; a thin band of lepidocrocite just anterior to this; and apatite throughout the core and anterior regions of the cusp. Biomineralization in these teeth is a matrix-mediated process, in which the minerals are deposited around fibers, with the different biominerals described as occupying architecturally discrete compartments. In this study, a range of scanning electron microscopes was utilized to undertake a detailed in situ investigation of the fine structure of the major lateral teeth. The arrangement of the organic and biomineral components of the tooth is similar throughout the three zones, having no discrete borders between them, and with crystallites of each mineral phase extending into the adjacent mineral zone. Along the posterior surface of the tooth, the organic fibers are arranged in a series of fine parallel lines, but just within the periphery their appearance takes on a "fish scale"-like pattern, reflective of the cross section of a series of units that are overlaid, and offset from each other, in adjacent rows. The units are approximately 2 microm wide and 0.6 microm thick and comprise biomineral plates separated by organic fibers. Two types of subunits make up each "fish scale": one is elongate and curved and forms a trough, in which the other, rod-like unit, is nestled. Adjacent rod and trough units are aligned into large sheets that define the fracture plane of the tooth. The alignment of the plates of rod-trough units is complex and exhibits extreme spatial variation within the tooth cusp. Close to the posterior surface the plates are essentially horizontal and lie in a lateromedial plane, while anteriorly they are almost vertical and lie in the posteroanterior plane. An understanding of the fine structure of the mineralized teeth of chitons, and of the relationship between the organic and

  4. Electronic structure study of Co doped CeO2 nanoparticles using X-ray absorption fine structure spectroscopy

    International Nuclear Information System (INIS)

    Kumar, Shalendra; Gautam, Sanjeev; Song, T.K.; Chae, Keun Hwa; Jang, K.W.; Kim, S.S.

    2014-01-01

    Highlights: • The electronic structural of Co–CeO 2 nanoparticles is investigated using XAFS. • Ce M 5,4 , Ce L 3 and O K edge NEXAFS reveal that the Ce-ions are in +4 valence state. • The NEXAFS spectrum performed at Co L3,2-edge confirms Co-ion in 2+ state. • The EXAFS analysis also show that Co ions are occupying Ce position in doped CeO 2 . • The distances between Ce–O and Ce–Ce/Co in all shells decreases with Co doping. - Abstract: We investigated the electronic structure of well characterized Co doped CeO 2 nanoparticles using X-ray absorption fine structure (XAFS) spectroscopy. Near edge X-ray absorption fine structure (NEXAFS) spectra at Ce M 5,4 , Ce L 3 and O K-edge conclude that the Ce-ions are in +4 valence state in pure as well as in Co doped CeO 2 nanoparticles. The local structure around Ce-atom in Co doped CeO 2 nanoparticles was also determined using extended X-ray absorption fine structure (EXAFS) spectroscopy at Ce L 3 edge. The EXAFS analysis suggest that the inter-atomic distance of Ce–O, Ce–Ce/Co decreases with Co doping, which indicate a contraction of the lattice. The decease in Ce–O distance also reflect that there is a formation of oxygen vacancies in CeO 2 matrix. The Debye–Waller factor also shows the consistent behaviour for all the coordination shells. The atomic multiplet calculations for Co L 3,2 -edge was performed to determine the valence state, symmetry and field splitting, which reflect that Co-ions are in 2+ state and substituted at Ce-site with crystal field splitting of 10Dq=-0.57eV. The XAFS measurements reveal that the Co-ions occupy the Ce position in the CeO 2 host matrix and create a oxygen vacancy

  5. Atlas of fine structures of dynamic spectra of solar type IV-dm and some type II radio bursts

    International Nuclear Information System (INIS)

    Slottje, C.

    1982-01-01

    The author presents an atlas of spectral fine structures of solar radio bursts of types IV and II around 1 m wavelength, as obtained with a multichannel spectrograph at Dwingeloo. The structures form largely a collection of observations of these events during late 1968 through 1974, thus covering almost entirely the declining branch of solar cycle 20. The spectrograph has an extra enhanced contrast output with properties quite different from those of the commonly used swept frequency spectrographs. The corresponding instrumental characteristics and effects are discussed. A classification of fine structures and an analysis of their statistical properties and of those of the pertinent radio events are also given. (Auth.)

  6. Fine structure of the stimulated Raman spectrum in compressed hydrogen. The relaxation-oscillation mode of backscattered Stokes emission

    International Nuclear Information System (INIS)

    Bespalov, V.G.; Efimov, Yu.N.; Staselko, D.I.

    1992-01-01

    This paper studies the emission spectra of backscattered stimulated Raman scattering (SRS) in compressed hydrogen in the relaxation-oscillation mode and the compression SRS mode for the minimum width of the spontaneous scattering spectrum (in the region of the Dicke dip). It is shown that the generation of a train of Stokes-emission subpulses results in the appearance of fine structure in the backscattered SRS spectrum. The influence of the temporal structure of reflected Stokes pulses on this spectrum and on the appearance of fine structure in it is analyzed. The conditions for generating spectrally limited (without phase modulation), extremely coherent Stokes pulses are explained. 18 refs., 3 figs

  7. Monte Carlo Simulations of Electron Energy-Loss Spectra with the Addition of Fine Structure from Density Functional Theory Calculations.

    Science.gov (United States)

    Attarian Shandiz, Mohammad; Guinel, Maxime J-F; Ahmadi, Majid; Gauvin, Raynald

    2016-02-01

    A new approach is presented to introduce the fine structure of core-loss excitations into the electron energy-loss spectra of ionization edges by Monte Carlo simulations based on an optical oscillator model. The optical oscillator strength is refined using the calculated electron energy-loss near-edge structure by density functional theory calculations. This approach can predict the effects of multiple scattering and thickness on the fine structure of ionization edges. In addition, effects of the fitting range for background removal and the integration range under the ionization edge on signal-to-noise ratio are investigated.

  8. Fine reservoir structure modeling based upon 3D visualized stratigraphic correlation between horizontal wells: methodology and its application

    Science.gov (United States)

    Chenghua, Ou; Chaochun, Li; Siyuan, Huang; Sheng, James J.; Yuan, Xu

    2017-12-01

    As the platform-based horizontal well production mode has been widely applied in petroleum industry, building a reliable fine reservoir structure model by using horizontal well stratigraphic correlation has become very important. Horizontal wells usually extend between the upper and bottom boundaries of the target formation, with limited penetration points. Using these limited penetration points to conduct well deviation correction means the formation depth information obtained is not accurate, which makes it hard to build a fine structure model. In order to solve this problem, a method of fine reservoir structure modeling, based on 3D visualized stratigraphic correlation among horizontal wells, is proposed. This method can increase the accuracy when estimating the depth of the penetration points, and can also effectively predict the top and bottom interfaces in the horizontal penetrating section. Moreover, this method will greatly increase not only the number of points of depth data available, but also the accuracy of these data, which achieves the goal of building a reliable fine reservoir structure model by using the stratigraphic correlation among horizontal wells. Using this method, four 3D fine structure layer models have been successfully built of a specimen shale gas field with platform-based horizontal well production mode. The shale gas field is located to the east of Sichuan Basin, China; the successful application of the method has proven its feasibility and reliability.

  9. Constraints on a possible variation of the fine structure constant from galaxy cluster data

    Energy Technology Data Exchange (ETDEWEB)

    Holanda, R.F.L. [Departamento de Física, Universidade Estadual da Paraíba, 58429-500, Campina Grande – PB (Brazil); Landau, S.J.; Sánchez G, I.E. [Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, and IFIBA, CONICET, Ciudad Universitaria – PabI, Buenos Aires 1428 (Argentina); Alcaniz, J.S. [Departamento de Astronomia, Observatório Nacional, 20921-400, Rio de Janeiro – RJ (Brazil); Busti, V.C., E-mail: holanda@uepb.edu.br, E-mail: slandau@df.uba.ar, E-mail: alcaniz@on.br, E-mail: isg.cos@gmail.com, E-mail: vinicius.busti@astro.iag.usp.br [Departamento de Física Matemática, Instituto de Física, Universidade de São Paulo, CP 66318, 05508-090, São Paulo – SP (Brazil)

    2016-05-01

    We propose a new method to probe a possible time evolution of the fine structure constant α from X-ray and Sunyaev-Zel'dovich measurements of the gas mass fraction ( f {sub gas}) in galaxy clusters. Taking into account a direct relation between variations of α and violations of the distance-duality relation, we discuss constraints on α for a class of dilaton runaway models. Although not yet competitive with bounds from high- z quasar absorption systems, our constraints, considering a sample of 29 measurements of f {sub gas}, in the redshift interval 0.14 < z < 0.89, provide an independent estimate of α variation at low and intermediate redshifts. Furthermore, current and planned surveys will provide a larger amount of data and thus allow to improve the limits on α variation obtained in the present analysis.

  10. Fine structure near the starting frequency of solar type III radio bursts

    Energy Technology Data Exchange (ETDEWEB)

    Benz, A.O.; Zlobec, P.; Jaeggi, M.

    1982-06-01

    We have systematically analyzed the period in time and frequency adjacent to the beginning of type III bursts digitally recorded at Bleien during the second half of 1980. A surprisingly high percentage (10%, possibly more than 20%) of the type III bursts show fine structure in the form of narrow-banded spikes of 0.05 s and less duration, which form clusters of relatively large bandwidth. These spikes are not totally polarized (contrary to claims in the literature) and they are uniformly distributed over the disk. Individual spikes often show highly variable polarization, which may even change sense. The average degree of polarization of the clouds has a wider distribution than that of the associated type III bursts, but generally the same sign. Spikes are considerably different from type I bursts.

  11. Bloch oscillations of ultracold atoms and measurement of the fine structure constant

    International Nuclear Information System (INIS)

    Clade, P.

    2005-10-01

    From a measurement of the recoil velocity of an atom absorbing a photon, it is possible to deduce a determination of the ratio h/m between the Planck constant and the mass of the atoms and then to deduce a value of the fine structure constant alpha. To do this measurement, we use the technique of Bloch oscillations, which allows us to transfer a large number of recoils to atoms. A velocity sensor, based on velocity selective Raman transition, enables us to measure the momentum transferred to the atoms. A measurement with a statistical uncertainty of 4.4 10 -9 , in conjunction with a careful study of systematic effects (5 10 -9 ), has led us to a determination of alpha with an uncertainty of 6.7 10 -9 : α -1 (Rb) = 137.03599878 (91). This uncertainty is similar to the uncertainty of the best determinations of alpha based on atom interferometry. (author)

  12. 3-Space In-Flow Theory of Gravity: Boreholes, Blackholes and the Fine Structure Constant

    Directory of Open Access Journals (Sweden)

    Cahill R. T.

    2006-04-01

    Full Text Available A theory of 3-space explains the phenomenon of gravity as arising from the time-dependence and inhomogeneity of the differential flow of this 3-space. The emergent theory of gravity has two gravitational constants: G - Newton's constant, and a dimensionless constant alpha. Various experiments and astronomical observations have shown that alpha is the fine structure constant ~1/137. Here we analyse the Greenland Ice Shelf and Nevada Test Site borehole g anomalies, and confirm with increased precision this value of alpha. This and other successful tests of this theory of gravity, including the supermassive black holes in globular clusters and galaxies, and the "dark-matter" effect in spiral galaxies, shows the validity of this theory of gravity. This success implies that the non-relativistic Newtonian gravity was fundamentally flawed from the beginning, and that this flaw was inherited by the relativistic General Relativity theory of gravity.

  13. 3-Space In-Flow Theory of Gravity: Boreholes, Blackholes and the Fine Structure Constant

    Directory of Open Access Journals (Sweden)

    Cahill R. T.

    2006-04-01

    Full Text Available A theory of 3-space explains the phenomenon of gravity as arising from the time-dependence and inhomogeneity of the differential flow of this 3-space. The emergent theory of gravity has two gravitational constants: GN — Newton’s constant, and a dimensionless constant α. Various experiments and astronomical observations have shown that α is the fine structure constant ≈ 1/137. Here we analyse the Greenland Ice Shelf and Nevada Test Site borehole g anomalies, and confirm with increased precision this value of α. This and other successful tests of this theory of gravity, including the supermassive black holes in globular clusters and galaxies, and the “dark-matter” effect in spiral galaxies, shows the validity of this theory of gravity. This success implies that the non-relativistic Newtonian gravity was fundamentally flawed from the beginning, and that this flaw was inherited by the relativistic General Relativity theory of gravity.

  14. Fine structure of V2+ energy levels in CsCaF3:V2+

    International Nuclear Information System (INIS)

    Avram, C.N.; Brik, M.G.

    2004-01-01

    Theoretical investigations of the fine structure of the lasing 4 T 2g level in a CsCaF 3 :V 2+ crystal were carried out. The spin-orbit splitting of the 4 T 2g term in the static low crystal field was obtained from the Eisenstein matrices and using parameters (Dq, B, C, ζ SO ) appropriate for the 4 T 2g - 4 A 2g zero-phonon line. The 4 T 2g spinor splitting has been modeled by the second-order spin-orbit Hamiltonian. The effect of the dynamical Jahn-Teller interaction on the spin-orbit splitting of the 4 T 2g term was taken into account; the Jahn-Teller stabilization energy, ZPL splitting and the Huang-Rhys parameter for the e g normal mode were all evaluated

  15. Synchrotron x-ray fluorescence and extended x-ray absorption fine structure analysis

    International Nuclear Information System (INIS)

    Chen, J.R.; Gordon, B.M.; Hanson, A.L.; Jones, K.W.; Kraner, H.W.; Chao, E.C.T.; Minkin, J.A.

    1984-01-01

    The advent of dedicated synchrotron radiation sources has led to a significant increase in activity in many areas of science dealing with the interaction of x-rays with matter. Synchrotron radiation provides intense, linearly polarized, naturally collimated, continuously tunable photon beams, which are used to determine not only the elemental composition of a complex, polyatomic, dilute material but also the chemical form of the elements with improved accuracy. Examples of the application of synchrotron radiation include experiments in synchrotron x-ray fluorescence (SXRF) analysis and extended x-ray absorption fine structure (EXAFS) analysis. New synchrotron radiation x-ray microprobes for elemental analysis in the parts per billion range are under construction at several laboratories. 76 references, 24 figures

  16. New constraints on variations of the fine structure constant from CMB anisotropies

    International Nuclear Information System (INIS)

    Menegoni, Eloisa; Melchiorri, Alessandro; Galli, Silvia; Bartlett, James G.; Martins, C. J. A. P.

    2009-01-01

    We demonstrate that recent measurements of cosmic microwave background temperature and polarization anisotropy made by the ACBAR, QUAD, and BICEP experiments substantially improve the cosmological constraints on possible variations of the fine structure constant in the early universe. This data, combined with the five year observations from the WMAP mission, yield the constraint α/α 0 =0.987±0.012 at 68% C.L. The inclusion of the new Hubble Space Telescope constraints on the Hubble constant further increases the accuracy to α/α 0 =1.001±0.007 at 68% C.L., bringing possible deviations from the current value below the 1% level and improving previous constraints by a factor of ∼3.

  17. Fisher matrix forecasts for astrophysical tests of the stability of the fine-structure constant

    Directory of Open Access Journals (Sweden)

    C.S. Alves

    2017-07-01

    Full Text Available We use Fisher Matrix analysis techniques to forecast the cosmological impact of astrophysical tests of the stability of the fine-structure constant to be carried out by the forthcoming ESPRESSO spectrograph at the VLT (due for commissioning in late 2017, as well by the planned high-resolution spectrograph (currently in Phase A for the European Extremely Large Telescope. Assuming a fiducial model without α variations, we show that ESPRESSO can improve current bounds on the Eötvös parameter—which quantifies Weak Equivalence Principle violations—by up to two orders of magnitude, leading to stronger bounds than those expected from the ongoing tests with the MICROSCOPE satellite, while constraints from the E-ELT should be competitive with those of the proposed STEP satellite. Should an α variation be detected, these measurements will further constrain cosmological parameters, being particularly sensitive to the dynamics of dark energy.

  18. Constraining spatial variations of the fine-structure constant in symmetron models

    Directory of Open Access Journals (Sweden)

    A.M.M. Pinho

    2017-06-01

    Full Text Available We introduce a methodology to test models with spatial variations of the fine-structure constant α, based on the calculation of the angular power spectrum of these measurements. This methodology enables comparisons of observations and theoretical models through their predictions on the statistics of the α variation. Here we apply it to the case of symmetron models. We find no indications of deviations from the standard behavior, with current data providing an upper limit to the strength of the symmetron coupling to gravity (log⁡β2<−0.9 when this is the only free parameter, and not able to constrain the model when also the symmetry breaking scale factor aSSB is free to vary.

  19. Inelastic electron scattering, fine structure of M1 giant resonances and Gamow-Teller states

    International Nuclear Information System (INIS)

    Richter, A.

    1983-01-01

    Recent progress in obtaining detailed fine structure distributions of magnetic giant resonances in nuclei using high resolution inelastic electron scattering at low energy is discussed. Specific examples chosen are the medium heavy nuclei 40 42 44 48 Ca in which M1 excitations are due to neutron spin-flip transitions and the N=28 isotones 50 Ti, 52 Cr and 54 Fe where in addition also proton excitations contribute to the measured M1 strength. It is found that the M1 strength is very fragmented and considerably quenched in comparison to predictions of shell model calculations in a model space that includes up to 2p-2h excitations. Finally, the old problem of M1 strength in 208 Pb is revisited and the results of a form factor measurement of a recently discovered low lying Jsup(π)=1 + state by nuclear resonance fluorescence are presented. (Auth.)

  20. Fine-structure processing, frequency selectivity and speech perception in hearing-impaired listeners

    DEFF Research Database (Denmark)

    Strelcyk, Olaf; Dau, Torsten

    2008-01-01

    Hearing-impaired people often experience great difficulty with speech communication when background noise is present, even if reduced audibility has been compensated for. Other impairment factors must be involved. In order to minimize confounding effects, the subjects participating in this study...... consisted of groups with homogeneous, symmetric audiograms. The perceptual listening experiments assessed the intelligibility of full-spectrum as well as low-pass filtered speech in the presence of stationary and fluctuating interferers, the individual's frequency selectivity and the integrity of temporal...... modulation were obtained. In addition, these binaural and monaural thresholds were measured in a stationary background noise in order to assess the persistence of the fine-structure processing to interfering noise. Apart from elevated speech reception thresholds, the hearing impaired listeners showed poorer...

  1. Representations of U(2∞ and the Value of the Fine Structure Constant

    Directory of Open Access Journals (Sweden)

    William H. Klink

    2005-12-01

    Full Text Available A relativistic quantum mechanics is formulated in which all of the interactions are in the four-momentum operator and Lorentz transformations are kinematic. Interactions are introduced through vertices, which are bilinear in fermion and antifermion creation and annihilation operators, and linear in boson creation and annihilation operators. The fermion-antifermion operators generate a unitary Lie algebra, whose representations are fixed by a first order Casimir operator (corresponding to baryon number or charge. Eigenvectors and eigenvalues of the four-momentum operator are analyzed and exact solutions in the strong coupling limit are sketched. A simple model shows how the fine structure constant might be determined for the QED vertex.

  2. Polarizability of Kr6+ from high-L Kr5+ fine-structure measurements

    International Nuclear Information System (INIS)

    Lundeen, S. R.; Fehrenbach, C. W.

    2007-01-01

    The transition between n=55 and n=109 Rydberg levels of Kr 5+ has been studied at high resolution using the resonant excitation stark ionization spectroscopy method. Resolved excitation of L=6, 7, 8, and 9 levels in n=55 lead to a determination of the fine-structure energies of these levels. Interpreted with the long-range polarization model, this leads to a measurement of the dipole polarizabilities of Zn-like Kr 6+ , α d =2.69(4)a 0 3 . Obtaining a value of the quadrupole polarizability from the data will require additional theoretical input. Factors contributing to the signal and noise levels in measurements of this type are discussed

  3. Sample-angle feedback for diffraction anomalous fine-structure spectroscopy

    International Nuclear Information System (INIS)

    Cross, J.O.; Elam, W.T.; Harris, V.G.; Kirkland, J.P.; Bouldin, C.E.; Sorensen, L.B.

    1998-01-01

    Diffraction anomalous fine-structure (DAFS) experiments measure Bragg peak intensities as continuous functions of photon energy near a core-level excitation. Measuring the integrated intensity at each energy makes the experiments prohibitively slow; however, in many cases DAFS can be collected quickly by measuring only the peak intensity at the center of the rocking curve. A piezoelectric-actuator-driven stage has been designed and tested as part of a sample-angle feedback circuit for locking onto the maximum of the rocking curve while the energy is scanned. Although software peak-tracking requires only a simple calculation of diffractometer angles, it is found that the additional hardware feedback dramatically improves the reproducibility of the data

  4. Grazing incidence diffraction anomalous fine structure of self-assembled semiconductor nanostructures

    International Nuclear Information System (INIS)

    Grenier, S.; Letoublon, A.; Proietti, M.G.; Renevier, H.; Gonzalez, L.; Garcia, J.M.; Priester, C.; Garcia, J.

    2003-01-01

    We have studied self-organized quantum wires of InAs, grown by molecular beam epitaxy onto a InP(0 0 1) substrate, by means of grazing incidence diffraction anomalous fine structure (DAFS). The equivalent quantum wires thickness is 2.5 monolayers. We measured the (4 4 0) and (4 2 0) GIDAFS spectra, at the As K-edge, keeping the incidence and exit angles close to the InP critical angle. The analysis of both the smooth and oscillatory contributions of the DAFS spectrum, provide valuable information about composition and strain inside the quantum wires and close to the interface. We also show preliminary results on InAs wires encapsulated by a 40 A thick InP capping layer, suggesting the DAFS capability of probing different iso-strain regions of the wires

  5. Damping Properties vs. Structure Fineness of the High-zinc Aluminum Alloys

    Directory of Open Access Journals (Sweden)

    W.K. Krajewski

    2012-09-01

    Full Text Available The subject of this study is the presentation of relation between the degree of structure fineness and ultrasonic wave dampingcoefficient for the high-zinc aluminium alloys represented in this study by the sand mould cast alloy Al - 20 wt% Zn (AlZn20. Thestudied alloy was refined with a modifying (Al,Zn-Ti3 ternary master alloy, introducing Ti in the amount of 400 pm into metal. Based on the analysis of the initial and modified alloy macrostructure images and ultrasonic testing, it was found that the addition of (Al,Zn-Ti3 master alloy, alongside a significant fragmentation of grains, does not reduce the coefficient of ultrasonic waves with a frequency of 1 MHz.

  6. Fine-structure energy levels and radiative lifetime in Mo XIV

    International Nuclear Information System (INIS)

    Wang Xiaodong; Pei Dong; Jiang Renbin; Wang Wanjue

    2002-01-01

    Energy levels, radiative lifetime and various transition parameters for allowed transitions among the 1508 fine-structure levels belong to the (1s 2 2s 2 2p 6 3s 2 3p 6 ) 3d 10 4l, 3d 9 4l 2 , 3d 10 5l, 3d 9 4l4m, 3d 10 6l, 3d 10 7l and so on configurations of the Cu-like ions Mo XIV have been calculated by using the expanded fully relativistic GRASP code. The results are compared with those available in the literature, and the accuracy of the present data is assessed. Energy levels are expected to be accurate to within 0.81%. The authors have found some long lifetime levels

  7. Fine-structural changes in the midgut of old Drosophila melanogaster

    Science.gov (United States)

    Anton-Erxleben, F.; Miquel, J.; Philpott, D. E.

    1983-01-01

    Senescent fine-structural changes in the midgut of Drosophila melanogaster are investigated. A large number of midgut mitochondria in old flies exhibit nodular cristae and a tubular system located perpendicular to the normal cristae orientation. Anterior intestinal cells show a senescent accumulation of age pigment, either with a surrounding two-unit membrane or without any membrane. The predominant localization of enlarged mitochondria and pigment in the luminal gut region may be related to the polarized metabolism of the intestinal cells. Findings concur with previous observations of dense-body accumulations and support the theory that mitochondria are involved in the aging of fixed post-mitotic cells. Demonstrated by statistical analyses is that mitochondrial size increase is related to mitochondrial variation increase.

  8. Determining biological fine structure by differential absorption of soft x-rays

    International Nuclear Information System (INIS)

    Panessa-Warren, B.J.; Warren, J.B.

    1979-06-01

    The use of soft x-ray contact microscopy in examining histochemically treated human tissue embedded in plastic and exposed as unstained thin sections is demonstrated. When our preliminary data revealed that we could clearly image not only the histochemical reaction product, but the unstained biological fine structure of the surrounding tissues, we decided to test our hypothesis further and see if we could image unstained biological molecular aggregates as well. For this part of the investigation, we chose to examine hydrated proteoglycan aggregates. Proteoglycans are an essential component of the organic matrix of cartilage, and play a primary role in the retention and maintenance of extracellular water. To avoid any artifacts due to the introduction of exogeneous materials, and examine the proteoglycan aggregates in their hydrated, natural configuration, we made contact x-ray images of isolated proteoglycan aggregates in water

  9. Higher-order Stark effect on magnetic fine structure of the helium atom

    Energy Technology Data Exchange (ETDEWEB)

    Magunov, A.; Pal' chikov, V.; Pivovarov, V. [National Research Inst. for Physical-Technical and Radiotechnical Measurements (VNIIFTRI), Mendeleevo, Moscow Region (Russian Federation); Ovsiannikov, V. [Dept. of Physics, Voronezh State Univ. (Russian Federation); Oppen, G. von [Inst. fuer Analytische und Atomare Physik at Technische Univ. Berlin (Germany)

    2001-07-01

    We have calculated the scalar and tensor dipole polarizabilities ({beta}) and hyperpolarizabilities ({gamma}) of excited 1s2p {sup 3}P{sub 0}, 1s2p {sup 3}P{sub 2}- states of helium. Our theory includes fine structure of triplet sublevels. Semiempirical and accurate electron-correlated wave functions have been used to determine the static values of {beta} and {gamma}. Numerical calculations are carried out using sums of oscillator strengths and, alternatively, with the Green function for the excited valence electron. Specifically, we present results for the integral over the continuum, for second- and fourth-order matrix elements. The corresponding estimations indicate that these corrections are of the order of 23% for the scalar part of polarizability and only of the order of 3% for the tensor part.

  10. Near-Edge X-ray Absorption Fine Structure Spectroscopy of Diamondoid Thiol Monolayers on Gold

    Energy Technology Data Exchange (ETDEWEB)

    Willey, T M; Fabbri, J; Lee, J I; Schreiner, P; Fokin, A A; Tkachenko, B A; Fokina, N A; Dahl, J; Carlson, B; Vance, A L; Yang, W; Terminello, L J; van Buuren, T; Melosh, N

    2007-11-27

    Diamondoids, hydrocarbon molecules with cubic-diamond-cage structures, have unique properties with potential value for nanotechnology. The availability and ability to selectively functionalize this special class of nanodiamond materials opens new possibilities for surface-modification, for high-efficiency field emitters in molecular electronics, as seed crystals for diamond growth, or as robust mechanical coatings. The properties of self-assembled monolayers (SAMs) of diamondoids are thus of fundamental interest for a variety of emerging applications. This paper presents the effects of thiol substitution position and polymantane order on diamondoid SAMs on gold using near-edge X-ray absorption fine structure spectroscopy (NEXAFS) and X-ray photoelectron spectroscopy (XPS). A framework to determine both molecular tilt and twist through NEXAFS is presented and reveals highly ordered diamondoid SAMs, with the molecular orientation controlled by the thiol location. C 1s and S 2p binding energies are lower in adamantane thiol than alkane thiols on gold by 0.67 {+-} 0.05 eV and 0.16 {+-} 0.04 eV respectively. These binding energies vary with diamondoid monolayer structure and thiol substitution position, consistent with different amounts of steric strain and electronic interaction with the substrate. This work demonstrates control over the assembly, in particular the orientational and electronic structure, providing a flexible design of surface properties with this exciting new class of diamond clusters.

  11. Fine-structure excitation of Fe II and Fe III due to collisions with electrons

    Science.gov (United States)

    Wan, Yier; Qi, Yueying; Favreau, Connor; Loch, Stuart; Stancil, P.; Ballance, Connor; McLaughlin, Brendan

    2018-06-01

    Atomic data of iron peak elements are of great importance in astronomical observations. Among all the ionization stages of iron, Fe II and Fe III are of particular importance because of the high cosmic abundance, relatively low ionization potential and complex open d-shell atomic structure. Fe II and Fe III emission are observed from nearly all classes of astronomical objects over a wide spectral range from the infrared to the ultraviolet. To meaningfully interpret these spectra, astronomers have to employ highly complex modeling codes with reliable collision data to simulate the astrophysical observations. The major aim of this work is to provide reliable atomic data for diagnostics. We present new collision strengths and effective collisions for electron impact excitation of Fe II and Fe III for the forbidden transitions among the fine-structure levels of the ground terms. A very fine energy mesh is used for the collision strengths and the effective collision strengths are calculated over a wide range of electron temperatures of astrophysical importance (10-2000 K). The configuration interaction state wave functions are generated with a scaled Thomas-Fermi-Dirac-Amaldi (TFDA) potential, while the R-matrix plus intermediate coupling frame transformation (ICFT), Breit-Pauli R-matrix and Dirac R-matrix packages are used to obtain collision strengths. Influences of the different methods and configuration expansions on the collisional data are discussed. Comparison is made with earlier theoretical work and differences are found to occur at the low temperatures considered here.This work was funded by NASA grant NNX15AE47G.

  12. New algorithm improves fine structure of the barley consensus SNP map

    Directory of Open Access Journals (Sweden)

    Endelman Jeffrey B

    2011-08-01

    Full Text Available Abstract Background The need to integrate information from multiple linkage maps is a long-standing problem in genetics. One way to visualize the complex ordinal relationships is with a directed graph, where each vertex in the graph is a bin of markers. When there are no ordering conflicts between the linkage maps, the result is a directed acyclic graph, or DAG, which can then be linearized to produce a consensus map. Results New algorithms for the simplification and linearization of consensus graphs have been implemented as a package for the R computing environment called DAGGER. The simplified consensus graphs produced by DAGGER exactly capture the ordinal relationships present in a series of linkage maps. Using either linear or quadratic programming, DAGGER generates a consensus map with minimum error relative to the linkage maps while remaining ordinally consistent with them. Both linearization methods produce consensus maps that are compressed relative to the mean of the linkage maps. After rescaling, however, the consensus maps had higher accuracy (and higher marker density than the individual linkage maps in genetic simulations. When applied to four barley linkage maps genotyped at nearly 3000 SNP markers, DAGGER produced a consensus map with improved fine structure compared to the existing barley consensus SNP map. The root-mean-squared error between the linkage maps and the DAGGER map was 0.82 cM per marker interval compared to 2.28 cM for the existing consensus map. Examination of the barley hardness locus at the 5HS telomere, for which there is a physical map, confirmed that the DAGGER output was more accurate for fine structure analysis. Conclusions The R package DAGGER is an effective, freely available resource for integrating the information from a set of consistent linkage maps.

  13. Fine surface structure of unfixed and hydrated macrophages observed by laser-plasma x-ray contact microscopy

    International Nuclear Information System (INIS)

    Yamamoto, Yoshimasa; Friedman, Herman; Yoshimura, Hideyuki; Kinjo, Yasuhito; Shioda, Seiji; Debari, Kazuhiro; Shinohara, Kunio; Rajyaguru, Jayshree; Richardson, Martin

    2000-01-01

    A compact, high-resolution, laser-plasma, x-ray contact microscope using a table-top Nd:glass laser system has been developed and utilized for the analysis of the surface structure of live macrophages. Fine fluffy surface structures of murine peritoneal macrophages, which were live, hydrolyzed and not sliced and stained, were observed by the x-ray microscope followed by analysis using an atomic force microscopy. In order to compare with other techniques, a scanning electron microscopy (SEM) was utilized to observe the surface structure of the macrophages. The SEM offered a fine whole cell image of the same macrophages, which were fixed and dehydrated, but the surfaces were ruffled and different from that of x-ray images. A standard light microscope was also utilized to observe the shape of live whole macrophages. Light microscopy showed some fluffy surface structures of the macrophages, but the resolution was too low to observe the fine structures. Thus, the findings of fine fluffy surface structures of macrophages by x-ray microscopy provide valuable information for studies of phagocytosis, cell spreading and adherence, which are dependent on the surface structure of macrophages. Furthermore, the present study also demonstrates the usefulness of x-ray microscopy for analysis of structures of living cells

  14. Cultural transmission of tool use combined with habitat specializations leads to fine-scale genetic structure in bottlenose dolphins

    NARCIS (Netherlands)

    Kopps, Anna M.; Ackermann, Corinne Y.; Sherwin, William B.; Allen, Simon J.; Bejder, Lars; Kruetzen, Michael

    2014-01-01

    Socially learned behaviours leading to genetic population structure have rarely been described outside humans. Here, we provide evidence of fine-scale genetic structure that has probably arisen based on socially transmitted behaviours in bottlenose dolphins (Tursiops sp.) in western Shark Bay,

  15. An Accurate CT Saturation Classification Using a Deep Learning Approach Based on Unsupervised Feature Extraction and Supervised Fine-Tuning Strategy

    Directory of Open Access Journals (Sweden)

    Muhammad Ali

    2017-11-01

    Full Text Available Current transformer (CT saturation is one of the significant problems for protection engineers. If CT saturation is not tackled properly, it can cause a disastrous effect on the stability of the power system, and may even create a complete blackout. To cope with CT saturation properly, an accurate detection or classification should be preceded. Recently, deep learning (DL methods have brought a subversive revolution in the field of artificial intelligence (AI. This paper presents a new DL classification method based on unsupervised feature extraction and supervised fine-tuning strategy to classify the saturated and unsaturated regions in case of CT saturation. In other words, if protection system is subjected to a CT saturation, proposed method will correctly classify the different levels of saturation with a high accuracy. Traditional AI methods are mostly based on supervised learning and rely heavily on human crafted features. This paper contributes to an unsupervised feature extraction, using autoencoders and deep neural networks (DNNs to extract features automatically without prior knowledge of optimal features. To validate the effectiveness of proposed method, a variety of simulation tests are conducted, and classification results are analyzed using standard classification metrics. Simulation results confirm that proposed method classifies the different levels of CT saturation with a remarkable accuracy and has unique feature extraction capabilities. Lastly, we provided a potential future research direction to conclude this paper.

  16. Calculation of near-edge x-ray-absorption fine structure at finite temperatures: Spectral signatures of hydrogen bond breaking in liquid water

    International Nuclear Information System (INIS)

    Hetenyi, Balazs; De Angelis, Filippo; Giannozzi, Paolo; Car, Roberto

    2004-01-01

    We calculate the near-edge x-ray-absorption fine structure of H 2 O in the gas, hexagonal ice, and liquid phases using heuristic density-functional based methods. We present a detailed comparison of our results with experiment. The differences between the ice and water spectra can be rationalized in terms of the breaking of hydrogen bonds around the absorbing molecule. In particular the increase in the pre-edge absorption feature from ice to water is shown to be due to the breaking of a donor hydrogen bond. We also find that in water approximately 19% of hydrogen bonds are broken

  17. Multiwavelength anomalous diffraction and diffraction anomalous fine structure to study composition and strain of semiconductor nano structures

    International Nuclear Information System (INIS)

    Favre-Nicolin, V.; Proietti, M.G.; Leclere, C.; Renevier, H.; Katcho, N.A.; Richard, M.I.

    2012-01-01

    The aim of this paper is to illustrate the use of Multi-Wavelength Anomalous Diffraction (MAD) and Diffraction Anomalous Fine Structure (DAFS) spectroscopy for the study of structural properties of semiconductor nano-structures. We give a brief introduction on the basic principles of these techniques providing a detailed bibliography. Then we focus on the data reduction and analysis and we give specific examples of their application on three different kinds of semiconductor nano-structures: Ge/Si nano-islands, AlN capped GaN/AlN Quantum Dots and AlGaN/AlN Nano-wires. We show that the combination of MAD and DAFS is a very powerful tool to solve the structural problem of these materials of high technological impact. In particular, the effects of composition and strain on diffraction are disentangled and composition can be determined in a reliable way, even at the interface between nano-structure and substrate. We show the great possibilities of this method and give the reader the basic tools to undertake its use. (authors)

  18. Development of Ultra-Fine-Grained Structure in AISI 321 Austenitic Stainless Steel

    Science.gov (United States)

    Tiamiyu, A. A.; Szpunar, J. A.; Odeshi, A. G.; Oguocha, I.; Eskandari, M.

    2017-12-01

    Ultra-fine-grained (UFG) structure was developed in AISI 321 austenitic stainless steel (ASS) using cryogenic rolling followed by annealing treatments at 923 K, 973 K, 1023 K, and 1073 K (650 °C, 700 °C, 750 °C, and 800 °C) for different lengths of time. The α'-martensite to γ-austenite reversion behavior and the associated texture development were analyzed in the cryo-rolled specimens after annealing. The activation energy, Q, required for the reversion of α'-martensite to γ-austenite in the steel was estimated to be 80 kJ mol-1. TiC precipitates and unreversed triple junction α'-martensite played major roles in the development of UFG structure through the Zener pinning of grain boundaries. The optimum annealing temperature and time for the development of UFG structure in the cryo-rolled AISI 321 steel are (a) 923 K (650 °C) for approximately 28800 seconds and (b) 1023 K (750 °C) for 600 seconds, with average grain sizes of 0.22 and 0.31 µm, respectively. Annealing at 1023 K (750 °C) is considered a better alternative since the volume fraction of precipitated carbides in specimens annealed at 1023 K (750 °C) are less than those annealed at 923 K (650 °C). More so, the energy consumption during prolonged annealing time to achieve an UFG structure at 923 K (650 °C) is higher due to low phase reversion rate. The hardness of the UFG specimens is 195 pct greater than that of the as-received steel. The higher volume fraction of TiC precipitates in the UFG structure may be an additional source of hardening. Micro and macrotexture analysis indicated {110}〈uvw〉 as the major texture component of the austenite grains in the UFG structure. Its intensity is stronger in the specimen annealed at low temperatures.

  19. Correlative Structural Biology: How to Investigate the Fine Details of Viral Structure

    Directory of Open Access Journals (Sweden)

    Elizabeth R. Wright

    2010-01-01

    Full Text Available Commentary on Byeon, I.J.; Meng, X.; Jung, J.; Zhao, G.; Yang, R.; Ahn, J.; Shi, J.; Concel, J.; Aiken, C.; Zhang, P.; Gronenborn, A.M. Structural convergence between Cryo-EM and NMR reveals intersubunit interactions critical for HIV-1 capsid function. Cell 2009, 139, 780-790.

  20. Deep Convolutional Neural Networks: Structure, Feature Extraction and Training

    Directory of Open Access Journals (Sweden)

    Namatēvs Ivars

    2017-12-01

    Full Text Available Deep convolutional neural networks (CNNs are aimed at processing data that have a known network like topology. They are widely used to recognise objects in images and diagnose patterns in time series data as well as in sensor data classification. The aim of the paper is to present theoretical and practical aspects of deep CNNs in terms of convolution operation, typical layers and basic methods to be used for training and learning. Some practical applications are included for signal and image classification. Finally, the present paper describes the proposed block structure of CNN for classifying crucial features from 3D sensor data.

  1. Asymmetric larval head and mandibles of Hydrophilus acuminatus (Insecta: Coleoptera, Hydrophilidae): Fine structure and embryonic development.

    Science.gov (United States)

    Sato, Shun'ichi; Inoda, Toshio; Niitsu, Shuhei; Kubota, Souichirou; Goto, Yuji; Kobayashi, Yukimasa

    2017-11-01

    The larvae of a water scavenger beetle, Hydrophilus acuminatus, have strongly asymmetric mandibles; the right one is long and slender, whereas the left one is short and stout. The fine structure and embryonic development of the head capsule and mandibles of this species were examined using light and scanning electron microscopy, and asymmetries in shape were detected in these structures applying an elliptic Fourier analysis. The larval mandibles are asymmetric in the following aspects: whole length, the number, structure and arrangement of retinacula (inner teeth), and size and shape of both the molar and incisor regions. The larval head is also asymmetric; the left half of the head capsule is larger than the right, and the left adductor muscle of the mandible is much thicker than the right. The origin and developmental process of asymmetric mandibles were traced in developing embryos whose developmental period is about 270 h and divided into 10 stages. Mandibular asymmetries are produced by the cumulative effects of six stepwise modifications that occur from about 36% of the total developmental time onward. The significance of these modifications was discussed with respect to the functional advantages of asymmetries and the phylogeny of members of the Hydrophilidae. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Fine-scale population structure and the era of next-generation sequencing.

    Science.gov (United States)

    Henn, Brenna M; Gravel, Simon; Moreno-Estrada, Andres; Acevedo-Acevedo, Suehelay; Bustamante, Carlos D

    2010-10-15

    Fine-scale population structure characterizes most continents and is especially pronounced in non-cosmopolitan populations. Roughly half of the world's population remains non-cosmopolitan and even populations within cities often assort along ethnic and linguistic categories. Barriers to random mating can be ecologically extreme, such as the Sahara Desert, or cultural, such as the Indian caste system. In either case, subpopulations accumulate genetic differences if the barrier is maintained over multiple generations. Genome-wide polymorphism data, initially with only a few hundred autosomal microsatellites, have clearly established differences in allele frequency not only among continental regions, but also within continents and within countries. We review recent evidence from the analysis of genome-wide polymorphism data for genetic boundaries delineating human population structure and the main demographic and genomic processes shaping variation, and discuss the implications of population structure for the distribution and discovery of disease-causing genetic variants, in the light of the imminent availability of sequencing data for a multitude of diverse human genomes.

  3. Structural features of subtype-selective EP receptor modulators.

    Science.gov (United States)

    Markovič, Tijana; Jakopin, Žiga; Dolenc, Marija Sollner; Mlinarič-Raščan, Irena

    2017-01-01

    Prostaglandin E2 is a potent endogenous molecule that binds to four different G-protein-coupled receptors: EP1-4. Each of these receptors is a valuable drug target, with distinct tissue localisation and signalling pathways. We review the structural features of EP modulators required for subtype-selective activity, as well as the structural requirements for improved pharmacokinetic parameters. Novel EP receptor subtype selective agonists and antagonists appear to be valuable drug candidates in the therapy of many pathophysiological states, including ulcerative colitis, glaucoma, bone healing, B cell lymphoma, neurological diseases, among others, which have been studied in vitro, in vivo and in early phase clinical trials. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  4. Regulation of the demographic structure in isomorphic biphasic life cycles at the spatial fine scale.

    Directory of Open Access Journals (Sweden)

    Vasco Manuel Nobre de Carvalho da Silva Vieira

    Full Text Available Isomorphic biphasic algal life cycles often occur in the environment at ploidy abundance ratios (Haploid:Diploid different from 1. Its spatial variability occurs within populations related to intertidal height and hydrodynamic stress, possibly reflecting the niche partitioning driven by their diverging adaptation to the environment argued necessary for their prevalence (evolutionary stability. Demographic models based in matrix algebra were developed to investigate which vital rates may efficiently generate an H:D variability at a fine spatial resolution. It was also taken into account time variation and type of life strategy. Ploidy dissimilarities in fecundity rates set an H:D spatial structure miss-fitting the ploidy fitness ratio. The same happened with ploidy dissimilarities in ramet growth whenever reproductive output dominated the population demography. Only through ploidy dissimilarities in looping rates (stasis, breakage and clonal growth did the life cycle respond to a spatially heterogeneous environment efficiently creating a niche partition. Marginal locations were more sensitive than central locations. Related results have been obtained experimentally and numerically for widely different life cycles from the plant and animal kingdoms. Spore dispersal smoothed the effects of ploidy dissimilarities in fertility and enhanced the effects of ploidy dissimilarities looping rates. Ploidy dissimilarities in spore dispersal could also create the necessary niche partition, both over the space and time dimensions, even in spatial homogeneous environments and without the need for conditional differentiation of the ramets. Fine scale spatial variability may be the key for the prevalence of isomorphic biphasic life cycles, which has been neglected so far.

  5. Solvation structure determination of nickel(II) ion in six nitriles using extended X-ray absorption fine structure spectroscopy

    International Nuclear Information System (INIS)

    Inada, Yasuhiro; Funahashi, Shigenobu

    1997-01-01

    The solvation structures of the nickel(II) ion in six nitriles have been determined using X-ray absorption fine structure spectroscopy. The coordination number and the Ni-N bond length are 6 and 206.9 ± 0.6 pm in acetonitrile, 5.9 ± 0.2 and 206.9 ± 0.6 pm in propionitrile, 6.0 ± 0.2 and 206.8 ± 0.6 pm in butyronitrile, 6.0 ± 0.2 and 206.8 ± 0.6 pm in isobutyronitrile, 6.0 ± 0.2 and 206.8 ± 0.6 pm in valeronitrile, and 6.0 ± 0.2 and 206.5 ± 0.7 pm in benzonitrile, respectively. The structure parameters around the nickel(II) ion in all the nitriles are not affected by the bulkiness of the nitrile molecules. On the basis of the obtained structure parameters, we have discussed the structural characteristics around the nickel(II) ion with nitrogen and oxygen donor solvents and the reaction mechanisms for nitrile exchange on the nickel(II) ion. (author)

  6. Origin of fine oscillations in the photoluminescence spectrum of 2-dimensional electron gas formed in AlGaN/GaN high electron mobility transistor structures

    Energy Technology Data Exchange (ETDEWEB)

    Jana, Dipankar, E-mail: dip2602@gmail.com; Porwal, S.; Oak, S. M.; Sharma, T. K., E-mail: tarun@rrcat.gov.in [Semiconductor Physics and Devices Laboratory, Raja Ramanna Centre for Advanced Technology, Indore 452013, Madhya Pradesh (India); Jain, Anubha [Solid State Physics Laboratory, Lucknow Road, New Delhi 110054 (India)

    2015-10-28

    An unambiguous identification of the fine oscillations observed in the low temperature photoluminescence (PL) spectra of AlGaN/GaN based high electron mobility transistor (HEMT) structures is carried out. In literature, such oscillations have been erroneously identified as the sub-levels of 2-dimensional electron gas (2DEG) formed at AlGaN/GaN heterointerface. Here, the origin of these oscillations is probed by performing the angle dependent PL and reflectivity measurements under identical conditions. Contrary to the reports available in literature, we find that the fine oscillations are not related to 2DEG sub-levels. The optical characteristics of these oscillations are mainly governed by an interference phenomenon. In particular, peculiar temperature dependent redshift and excitation intensity dependent blueshift, which have been interpreted as the characteristics of 2DEG sub-levels in HEMT structures by other researchers, are understood by invoking the wavelength and temperature dependence of the refractive index of GaN within the framework of interference phenomenon. The results of other researchers are also consistently explained by considering the fine oscillatory features as the interference oscillations.

  7. Fine structure of the absorbed dose rate monitored in Zagreb, Croatia, in the period 1985-2011.

    Science.gov (United States)

    Babić, D; Senčar, J; Petrinec, B; Marović, G; Bituh, T; Skoko, B

    2013-04-01

    We report on the fine structure of the absorbed dose rate D which was measured and recorded on a daily basis at the Institute for Medical Research and Occupational Health in Zagreb, Croatia, throughout the period 1985-2011. After the Chernobyl accident, D increased steeply by a factor of 3.5, but this is the only prominent feature in the D versus time (t) curve. In the absence of accidental conditions, the D(t) is flat and amounts to 30-35 pGy/s. Despite the apparent plainness of D(t), its Fourier transform reveals several periodic modulations hidden in the noise. Some of the corresponding periods (6 and 12 months) can be related to seasonal atmospheric changes but this is not the case with the other periods identified (9.3, 13.7, 15.7, 20, 31, and 39 months). These are found to agree well with literature data on periodicities in solar activity, which implies that they are most probably linked to variations in the atmospheric production of (7)Be by cosmic rays. Copyright © 2012 Elsevier Ltd. All rights reserved.

  8. Adsorption site and structure determination of c(2x2) N{sub 2}/Ni(100) using angle-resolved photoemission extended fine structure

    Energy Technology Data Exchange (ETDEWEB)

    Moler, E.J.; Kellar, S.A.; Huff, W.R.A. [Lawrence Berkeley National Lab., CA (United States)] [and others

    1997-04-01

    The authors have determined the atomic spatial structure of c(2x2) N2Ni(100) with Angle-Resolved Photoemission Extended Fine Structure (ARPEFS) from the nitrogen 1s core level using monochromatized x-rays from beamline 6.1 at SSRL and beamline 9.3.2 at the ALS. The chemically shifted N 1s peak intensities were summed together to obtain ARPEFS curves for both nitrogen atoms in the molecule. They used a new, highly-optimized program based on the Rehr-Albers scattering matrix formalism to find the adsorption site and to quantitatively determine the bond-lengths. The nitrogen molecule stands upright at an atop site, with a N-Ni bond length of 2.25(1) {angstrom}, a N-N bond length of 1.10(7) {angstrom}, and a first layer Ni-Ni spacing of 1.76(4) {angstrom}. The shake-up peak shows an identical ARPEFS diffraction pattern, confirming its intrinsic nature and supporting a previous use of this feature to decompose the peak into contributions from the chemically inequivalent nitrogen atoms. Comparison to a previously published theoretical treatment of N-N-Ni and experimental structures of analogous adsorbate systems demonstrates the importance of adsorbate-adsorbate interactions in weakly chemisorbed systems.

  9. New analysis methods for skin fine-structure via optical image and development of 3D skin Cycloscan(™).

    Science.gov (United States)

    Han, J Y; Nam, G W; Lee, H K; Kim, M J; Kim, E J

    2015-11-01

    This study was conducted to develop methods for measuring skin fine-structure via optical image and apparatus for photographing to analyze efficacy of anti-aging. We developed an apparatus named 3D Skin CycloScan(™) to evaluate the efficacy of cosmetics by imagification of skin fine-structure such as wrinkles, pores, and skin texture. The semi-sphere shaped device has 12 different sequential flashing light sources captures optical image simultaneously in one second to exclude the influence of the subject's movement. The normal map that is extracted through shape from shading method is composed of face contour and skin fine-structure parts. When the low-frequency component which is the result of the Gaussian Filter application is eliminated, we can get only skin fine-structure. In this normal map, it is possible to extract two-dimensional vector map called direction map and we can regulate the intensity of the image of wrinkles, pores, and skin texture after filtering the direction map. We performed a clinical study to apply this new apparatus and methods to evaluate an anti-aging efficacy of cosmetics visually and validate with other conventional methods. After using anti-aging cream including 2% adenosine for 8 weeks, the total amount of fine wrinkle around eye area detected via 3D Skin CycloScan(™) was reduced by 12.1%. Also, wrinkles on crow's feet measured by PRIMOS COMPACT(®) (GFMesstechnik GmbH, Germany) reduced 11.7%. According to an aspect of the present study, by changing the direction of the lights toward to subject's skin, we can obtain the information about the fine structures present on the skin such as wrinkles, pores, or skin texture and represent it as an image. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  10. Angle-resolved photoemission extended fine structure: Multiple layers of emitters and multiple initial states

    International Nuclear Information System (INIS)

    Huff, W.R.A.; Kellar, S.A.; Moler, E.J.; California Univ., Berkeley, CA; Chen, Y.; Wu, H.; Shirley, D.A.; Hussain, Z.

    1995-01-01

    Recently, angle-resolved photoemission extended fine structure (ARPEFS) has been applied to experimental systems involving multiple layers of emitters and non-s core-level photoemission in an effort to broaden the utility of the technique. Most of the previous systems have been comprised of atomic or molecular overlayers adsorbed onto a single-crystal, metal surface and the photoemission data were taken from an s atomic core-level in the overlayer. For such a system, the acquired ARPEFS data is dominated by the p o final state wave backscattering from the substrate atoms and is well understood. In this study, we investigate ARPEFS as a surface-region structure determination technique when applied to experimental systems comprised of multiple layers of photoemitters and arbitrary initial state core-level photoemission. Understanding the data acquired from multiple layers of photoemitters is useful for studying multilayer interfaces, ''buried'' surfaces, and clean crystals in ultra- high vacuum. The ability to apply ARPEFS to arbitrary initial state core-level photoemission obviously opens up many systems to analysis. Efforts have been ongoing to understand such data in depth. We present clean Cu(111) 3s, 3p, and 3d core-level, normal photoemission data taken on a high resolution soft x-ray beamline 9.3.2 at the Advanced Light Source in Berkeley, California and clean Ni(111) 3p normal photoemission data taken at the National Synchrotron Light Source in Upton, New York, USA

  11. Fine resolution mapping of population age-structures for health and development applications.

    Science.gov (United States)

    Alegana, V A; Atkinson, P M; Pezzulo, C; Sorichetta, A; Weiss, D; Bird, T; Erbach-Schoenberg, E; Tatem, A J

    2015-04-06

    The age-group composition of populations varies considerably across the world, and obtaining accurate, spatially detailed estimates of numbers of children under 5 years is important in designing vaccination strategies, educational planning or maternal healthcare delivery. Traditionally, such estimates are derived from population censuses, but these can often be unreliable, outdated and of coarse resolution for resource-poor settings. Focusing on Nigeria, we use nationally representative household surveys and their cluster locations to predict the proportion of the under-five population in 1 × 1 km using a Bayesian hierarchical spatio-temporal model. Results showed that land cover, travel time to major settlements, night-time lights and vegetation index were good predictors and that accounting for fine-scale variation, rather than assuming a uniform proportion of under 5 year olds can result in significant differences in health metrics. The largest gaps in estimated bednet and vaccination coverage were in Kano, Katsina and Jigawa. Geolocated household surveys are a valuable resource for providing detailed, contemporary and regularly updated population age-structure data in the absence of recent census data. By combining these with covariate layers, age-structure maps of unprecedented detail can be produced to guide the targeting of interventions in resource-poor settings.

  12. Fine-Scale Human Population Structure in Southern Africa Reflects Ecogeographic Boundaries.

    Science.gov (United States)

    Uren, Caitlin; Kim, Minju; Martin, Alicia R; Bobo, Dean; Gignoux, Christopher R; van Helden, Paul D; Möller, Marlo; Hoal, Eileen G; Henn, Brenna M

    2016-09-01

    Recent genetic studies have established that the KhoeSan populations of southern Africa are distinct from all other African populations and have remained largely isolated during human prehistory until ∼2000 years ago. Dozens of different KhoeSan groups exist, belonging to three different language families, but very little is known about their population history. We examine new genome-wide polymorphism data and whole mitochondrial genomes for >100 South Africans from the ≠Khomani San and Nama populations of the Northern Cape, analyzed in conjunction with 19 additional southern African populations. Our analyses reveal fine-scale population structure in and around the Kalahari Desert. Surprisingly, this structure does not always correspond to linguistic or subsistence categories as previously suggested, but rather reflects the role of geographic barriers and the ecology of the greater Kalahari Basin. Regardless of subsistence strategy, the indigenous Khoe-speaking Nama pastoralists and the N|u-speaking ≠Khomani (formerly hunter-gatherers) share ancestry with other Khoe-speaking forager populations that form a rim around the Kalahari Desert. We reconstruct earlier migration patterns and estimate that the southern Kalahari populations were among the last to experience gene flow from Bantu speakers, ∼14 generations ago. We conclude that local adoption of pastoralism, at least by the Nama, appears to have been primarily a cultural process with limited genetic impact from eastern Africa. Copyright © 2016 by the Genetics Society of America.

  13. Electron impact excitation of fine-structure levels of neon-like titanium (Ti XIII)

    International Nuclear Information System (INIS)

    Gupta, G.P.; Deb, N.C.; Msezane, A.Z.

    1999-01-01

    The authors present results of a Breit-Pauli R-matrix calculation for the electron impact excitation of neon-like titanium, in which the 27 lowest fine-structure target levels arising out of the 4 lowest configurations 2s 2 2p 6 , 2s 2 2p 5 3s, 2s 2 2p 5 3p, and 2s 2 2p 5 3d are included. These target levels are represented by configuration interaction wave functions using the 1s, 2s, 2p, 3s, 3p, and 3d basic orbitals. The relativistic effects are included in the Breit-Pauli approximation via one-body mass correction, Darwin, and spin-orbit interaction terms in the scattering equations. For many transitions, complex resonance structures are found in the excitation cross sections. The excitation cross sections are integrated over a Maxwellian distribution of electron energies to give electron excitation rate coefficients over a wide temperature range from 150 to 600 eV. The relative populations for different electron densities and temperatures are also presented

  14. Insight into the biological effects of acupuncture points by X-ray absorption fine structure.

    Science.gov (United States)

    Liu, Chenglin; Liu, Qinghua; Zhang, Dongming; Liu, Wei; Yan, Xiaohui; Zhang, Xinyi; Oyanagi, Hiroyuki; Pan, Zhiyun; Hu, Fengchun; Wei, Shiqiang

    2018-06-02

    Exploration of the biological effects of transition metal ions in acupuncture points is essential to clarify the functional mechanism of acupuncture treatment. Here we show that in the SP6 acupuncture point (Sanyinjiao) the Fe ions are in a high-spin state of approximately t 2g 4.5 e g 1.5 in an Fe-N(O) octahedral crystal field. The Fe K-edge synchrotron radiation X-ray absorption fine structure results reveal that the Fe-N and Fe-O bond lengths in the SP6 acupuncture point are 2.05 and 2.13 Å, respectively, and are 0.05-0.10 Å longer than those in the surrounding tissue. The distorted atomic structure reduces the octahedral symmetry and weakens the crystal field around the Fe ions by approximately 0.3 eV, leading to the high-spin configuration of the Fe ions, which is favorable for strengthening the magnetotransport and oxygen transportation properties in the acupuncture point by the enhanced spin coherence. This finding might provide some insight into the microscopic effect of the atomic and electronic interactions of transition metal ions in the acupuncture point. Graphical Abstract ᅟ.

  15. Fine Structure of Glycosaminoglycans from Fresh and Decellularized Porcine Cardiac Valves and Pericardium

    Directory of Open Access Journals (Sweden)

    Antonio Cigliano

    2012-01-01

    Full Text Available Cardiac valves are dynamic structures, exhibiting a highly specialized architecture consisting of cells and extracellular matrix with a relevant proteoglycan and glycosaminoglycan content, collagen and elastic fibers. Biological valve substitutes are obtained from xenogenic cardiac and pericardial tissues. To overcome the limits of such non viable substitutes, tissue engineering approaches emerged to create cell repopulated decellularized scaffolds. This study was performed to determine the glycosaminoglycans content, distribution, and disaccharides composition in porcine aortic and pulmonary valves and in pericardium before and after a detergent-based decellularization procedure. The fine structural characteristics of galactosaminoglycans chondroitin sulfate and dermatan sulfate were examined by FACE. Furthermore, the mechanical properties of decellularized pericardium and its propensity to be repopulated by in vitro seeded fibroblasts were investigated. Results show that galactosaminoglycans and hyaluronan are differently distributed between pericardium and valves and within heart valves themselves before and after decellularization. The distribution of glycosaminoglycans is also dependent from the vascular district and topographic localization. The decellularization protocol adopted resulted in a relevant but not selective depletion of galactosaminoglycans. As a whole, data suggest that both decellularized porcine heart valves and bovine pericardium represent promising materials bearing the potential for future development of tissue engineered heart valve scaffolds.

  16. Fine structure of striations observed in barium plasma injections in the magnetospheric cleft

    International Nuclear Information System (INIS)

    Simons, D.J.; Eastman, T.E.; Pongratz, M.B.

    1976-01-01

    In January and November of 1975, the Los Alamos Scientific Laboratory sponsored four high altitude shaped charge barium plasma injections in the magnetospheric cleft region. These experiments were TORDO UNO (January 6), TORDO DOS (January 11), PERIQUITO UNO (November 25), and PERIQUITO DOS (November 28). All four injections took place near 500 km altitude, and optical data were taken from two aircraft and a ground station. The TORDO DOS and the PERIQUITO experiments showed rapid formation of striations (within one minute after injection), and fast horizontal spreading in contrast with TORDO UNO. In PERIQUITO DOS, the debris cloud spread magnetically east-west with a small net northerly motion. TORDO UNO shows very rapid poleward motion, and the remaining two events resulted in magnetically east-west horizontal spreading, with no noticeable poleward motion. Striations observed in the PERIQUITO DOS experiment separate in opposite directions with relative velocities of up to 3 km/sec. These field-aligned structures appear to form in sheets of approximately constant magnetic latitude. Significant spatial variations occur on a scale of less than 200 meters. Spatial frequency power spectra across these striations have been determined at various times. Observations of the debris cloud and the fast barium streak show strong field-aligned coherency of striation fine structure, indicating a field line mapping of transverse electric fields and gradients

  17. Development of powder diffraction anomalous fine structure method and applications to electrode materials for rechargeable batteries

    International Nuclear Information System (INIS)

    Kawaguchi, Tomoya; Fukuda, Katsutoshi; Oishi, Masatsugu; Ichitsubo, Tetsu; Matsubara, Eiichiro; Mizuki, Jun'ichiro

    2015-01-01

    A powder diffraction anomalous fine structure (P-DAFS) method is developed both in analytical and experimental techniques and applied to cathode materials for lithium ion batteries. The DAFS method, which is an absorption spectroscopic technique through a scattering measurement, enables us to analyze the chemical states and the local structures of a certain element at different sites, thanks to the nature of x-ray diffraction, where the contributions from each site are different at each diffraction. Electrode materials for rechargeable batteries frequently exhibit the interchange between Li and a transition metal, which is known as the cation mixing phenomena. This cation mixing significantly affects the whole electrode properties; therefore, the site-distinguished understanding of the roles of the transition metal is essential for further material design by controlling and positively utilizing this cation mixing phenomenon. However, the developments of the P-DAFS method are required for the applications to the practical materials such as the electrode materials. In the present study, a direct analysis technique to extract the absorption spectrum from the scattering without using the conventional iterative calculations, fast and accurate measurement techniques of the P-DAFS method, and applications to a typical electrode material of Li 1-x Ni 1+x O 2 , which exhibits the significant cation mixing, are described. (author)

  18. Wavelength dispersive X-ray absorption fine structure imaging by parametric X-ray radiation

    International Nuclear Information System (INIS)

    Inagaki, Manabu; Sakai, Takeshi; Sato, Isamu; Hayakawa, Yasushi; Nogami, Kyoko; Tanaka, Toshinari; Hayakawa, Ken; Nakao, Keisuke

    2008-01-01

    The parametric X-ray radiation (PXR) generator system at Laboratory for Electron Beam Research and Application (LEBRA) in Nihon University is a monochromatic and coherent X-ray source with horizontal wavelength dispersion. The energy definition of the X-rays, which depends on the horizontal size of the incident electron beam on the generator target crystal, has been investigated experimentally by measuring the X-ray absorption near edge structure (XANES) spectra on Cu and CuO associated with conventional X-ray absorption imaging technique. The result demonstrated the controllability of the spectrum resolution of XANES by adjusting of the horizontal electron beam size on the target crystal. The XANES spectra were obtained with energy resolution of several eV at the narrowest case, which is in qualitative agreement with the energy definition of the PXR X-rays evaluated from geometrical consideration. The result also suggested that the wavelength dispersive X-ray absorption fine structure measurement associated with imaging technique is one of the promising applications of PXR. (author)

  19. Evidence for the distortion product frequency place as a source of distribution product otoacoustic emission (DPOAE) fine structure in humans : I. Fine structure and higher-order DPOAE as a function of the frequency ratio f2/f1

    NARCIS (Netherlands)

    Mauermann, M; Uppenkamp, S; van Hengel, P.W.J.; Kollmeier, B

    1999-01-01

    Critical experiments were performed in order to validate the two-source hypothesis of distortion product otoacoustic emissions (DPOAE) generation. Measurements of the spectral fine structure of DPOAE in response to stimulation with two sinusoids have been:performed with normal-hearing subjects. The

  20. Malignant nodular hidradenoma on the scalp: report of a case with fine needle aspiration cytology features and histologic correlation.

    Science.gov (United States)

    Garcia-Bonafe, María Magdalena; Campins, Maria M Company; Redecilla, Pere Huguet

    2009-01-01

    Malignant nodular hidradenoma (MNH) is a malignant adnexal tumor of the eccrine sweat glands. The histology is similar to that of benign nodular hidradenoma, but MNH shows an infiltrative and invasive pattern, necrosis and angiolymphatic invasion. A 60-year-old woman, diagnosed with rectal adenocarcinoma 6 months before, underwent fine needle aspiration (FNA) of a nodule on the scalp. The aspirate smears showed (1) necrotic debris; (2) cohesive cell clusters and tissue fragments; (3) tubular formations; (4) globoid or cylindrical clear cells; (5) cells showing dense cytoplasm and a basaloid appearance; (6) cell sheets with anaplasia and squamous differentiation; and (7) multinucleated giant cells. The histology showed a lobulated pattern with necrosis and cyst formation. The clear cells that were seen on cytology occupied the periphery of the lobules, whereas the anaplastic cells were located in the central portion. Squamous differentiation and tubular formations were observed. Rapid, accurate diagnosis of these tumors is important, particularly when they develop at sites where a metastatic process must be ruled out. Cytology of FNA material provides this capability.

  1. Changes in the Fine Structure of Stochastic Distributions as a Consequence of Space-Time Fluctuations

    Directory of Open Access Journals (Sweden)

    Shnoll S. E.

    2006-04-01

    Full Text Available This is a survey of the fine structure stochastic distributions in measurements obtained by me over 50 years. It is shown: (1 The forms of the histograms obtained at each geographic point (at each given moment of time are similar with high probability, even if we register phenomena of completely different nature --- from biochemical reactions to the noise in a gravitational antenna, or alpha-decay. (2 The forms of the histograms change with time. The iterations of the same form have the periods of the stellar day (1.436 min, the solar day (1.440 min, the calendar year (365 solar days, and the sidereal year (365 solar days plus 6 hours and 9 min. (3 At the same instants of the local time, at different geographic points, the forms of the histograms are the same, with high probability. (4 The forms of the histograms depend on the locations of the Moon and the Sun with respect to the horizon. (5 All the facts are proof of the dependance of the form of the histograms on the location of the measured objects with respect to stars, the Sun, and the Moon. (6 At the instants of New Moon and the maxima of solar eclipses there are specific forms of the histograms. (7 It is probable that the observed correlations are not connected to flow power changes (the changes of the gravity force --- we did not find the appropriate periods in changes in histogram form. (8 A sharp anisotropy of space was discovered, registered by alpha-decay detectors armed with collimators. Observations at 54 North (the collimator was pointed at the Pole Star showed no day-long periods, as was also the case for observations at 82 North, near the Pole. Histograms obtained by observations with an Easterly-directed collimator were determined every 718 minutes (half stellar day and with observations using a Westerly-directed collimator. (9 Collimators rotating counter-clockwise, in parallel with the celestial equator, gave the probability of changes in histograms as the number of the

  2. Changes in the Fine Structure of Stochastic Distributions as a Consequence of Space-Time Fluctuations

    Directory of Open Access Journals (Sweden)

    Shnoll S. E.

    2006-04-01

    Full Text Available This is a survey of the fine structure stochastic distributions in measurements obtained by me over 50 years. It is shown: (1 The forms of the histograms obtained at each geographic point (at each given moment of time are similar with high probability, even if we register phenomena of completely different nature — from biochemical reactions to the noise in a gravitational antenna, or α-decay. (2 The forms of the histograms change with time. The iterations of the same form have the periods of the stellar day (1.436 min, the solar day (1.440 min, the calendar year (365 solar days, and the sidereal year (365 solar days plus 6 hours and 9 min. (3 At the same instants of the local time, at different geographic points, the forms of the histograms are the same, with high probability. (4 The forms of the histograms depend on the locations of the Moon and the Sun with respect to the horizon. (5 All the facts are proof of the dependance of the form of the histograms on the location of the measured objects with respect to stars, the Sun, and the Moon. (6 At the instants of New Moon and the maxima of solar eclipses there are specific forms of the histograms. (7 It is probable that the observed correlations are not connected to flow power changes (the changes of the gravity force — we did not find the appropriate periods in changes in histogram form. (8 A sharp anisotropy of space was discovered, registered by α-decay detectors armed with collimators. Observations at 54◦ North (the collimator was pointed at the Pole Star showed no day-long periods, as was also the case for observations at 82◦ North, near the Pole. Histograms obtained by observations with an Easterly-directed collimator were determined every 718 minutes (half stellar day and with observations using a Westerly-directed collimator. (9 Collimators rotating counter-clockwise, in parallel with the celestial equator, gave the probability of changes in histograms as the number of the

  3. Fine-scale crustal structure of the Azores Islands from teleseismic receiver functions

    Science.gov (United States)

    Spieker, K.; Rondenay, S.; Ramalho, R. S.; Thomas, C.; Helffrich, G. R.

    2016-12-01

    The Azores plateau is located near the Mid-Atlantic Ridge (MAR) and consists of nine islands, most of which lie east of the MAR. Various methods including seismic reflection, gravity, and passive seismic imaging have been used to investigate the crustal thickness beneath the islands. They have yielded thickness estimates that range between roughly 10 km and 30 km, but until now models of the fine-scale crustal structure have been lacking. A comparison of the crustal structure beneath the islands that lie west and east of the MAR might give further constraints on the evolution of the islands. For example, geochemical studies carried out across the region predict the existence of volcanic interfaces that should be detected seismically within the shallow crust of some of the islands. In this study, we use data from ten seismic stations located on the Azores Islands to investigate the crustal structure with teleseismic P-wave receiver functions. We query our resulting receiver functions for signals associated with the volcanic edifice, the crust-mantle boundary, and potential underplated layers beneath the various islands. The islands west of the MAR have a crustal structure comprising two discontinuities - an upper one at 1-2 km depth marking the base of the volcanic edifice, and a lower one at 10 km depth that we interpret as crust-mantle boundary. The islands east of the MAR can be subdivided into two groups. The central islands that are closer to the MAR exhibit a crustal structure similar to that of the western islands, with a volcanic edifice reaching a depth of 2 km and an average crust-mantle boundary at around 12 km depth. The easternmost islands, located on the oldest lithosphere, exhibit a more complex crustal structure with evidence for a mid-crustal interface and an underplated layer, yielding an effective crust-mantle boundary at >15 km depth. The difference in structure between proximal and distal islands might be related to the age of the plate at the

  4. Features of Inner Structure of Placer Gold of the North-Eastern Part Siberian Platform

    Science.gov (United States)

    Gerasimov, Boris; Zhuravlev, Anatolii; Ivanov, Alexey

    2017-12-01

    Mineral and raw material base of placer and ore gold is based on prognosis evaluation, which allows to define promising areas regarding gold-bearing deposit prospecting. But there are some difficulties in gold primary source predicting and prospecting at the North-east Siberian platform, because the studied area is overlapped by thick cover of the Cenozoic deposits, where traditional methods of gold deposit prospecting are ineffective. In this connection, detailed study of typomorphic features of placer gold is important, because it contains key genetic information, necessary for development of mineralogical criteria of prognosis evaluation of ore gold content. Authors studied mineralogical-geochemical features of placer gold of the Anabar placer area for 15 years, with a view to identify indicators of gold, typical for different formation types of primary sources. This article presents results of these works. In placer regions, where primary sources of gold are not identified, there is need to study typomorphic features of placer gold, because it contains important genetic information, necessary for the development of mineralogical criteria of prognosis evaluation of ore gold content. Inner structures of gold from the Anabar placer region are studied, as one of the diagnostic typomorphic criteria as described in prominent method, developed by N.V. Petrovskaya [1980]. Etching of gold was carried out using reagent: HCl + HNO3 + FeCl3 × 6H2O + CrO3 +thioureat + water. Identified inner structures wer studied in details by means of scanning electron microscope JEOL JSM-6480LV. Two types of gold are identified according to the features of inner structure of placer gold of the Anabar region. First type - medium-high karat fine, well processed gold with significantly changed inner structure. This gold is allochthonous, which was redeposited many times from ancient intermediate reservoirs to younger deposits. Second type - low-medium karat, poorly rounded gold with

  5. Structural control of ultra-fine CoPt nanodot arrays via electrodeposition process

    Energy Technology Data Exchange (ETDEWEB)

    Wodarz, Siggi [Department of Applied Chemistry, Waseda University, Shinjuku, Tokyo 169-8555 (Japan); Hasegawa, Takashi; Ishio, Shunji [Department of Materials Science, Akita University, Akita City 010-8502 (Japan); Homma, Takayuki, E-mail: t.homma@waseda.jp [Department of Applied Chemistry, Waseda University, Shinjuku, Tokyo 169-8555 (Japan)

    2017-05-15

    CoPt nanodot arrays were fabricated by combining electrodeposition and electron beam lithography (EBL) for the use of bit-patterned media (BPM). To achieve precise control of deposition uniformity and coercivity of the CoPt nanodot arrays, their crystal structure and magnetic properties were controlled by controlling the diffusion state of metal ions from the initial deposition stage with the application of bath agitation. Following bath agitation, the composition gradient of the CoPt alloy with thickness was mitigated to have a near-ideal alloy composition of Co:Pt =80:20, which induces epitaxial-like growth from Ru substrate, thus resulting in the improvement of the crystal orientation of the hcp (002) structure from its initial deposition stages. Furthermore, the cross-sectional transmission electron microscope (TEM) analysis of the nanodots deposited with bath agitation showed CoPt growth along its c-axis oriented in the perpendicular direction, having uniform lattice fringes on the hcp (002) plane from the Ru underlayer interface, which is a significant factor to induce perpendicular magnetic anisotropy. Magnetic characterization of the CoPt nanodot arrays showed increase in the perpendicular coercivity and squareness of the hysteresis loops from 2.0 kOe and 0.64 (without agitation) to 4.0 kOe and 0.87 with bath agitation. Based on the detailed characterization of nanodot arrays, the precise crystal structure control of the nanodot arrays with ultra-high recording density by electrochemical process was successfully demonstrated. - Highlights: • Ultra-fine CoPt nanodot arrays were fabricated by electrodeposition. • Crystallinity of hcp (002) was improved with uniform composition formation. • Uniform formation of hcp lattices leads to an increase in the coercivity.

  6. The morphodynamics and internal structure of intertidal fine-gravel dunes: Hills Flats, Severn Estuary, UK

    Science.gov (United States)

    Carling, P. A.; Radecki-Pawlik, A.; Williams, J. J.; Rumble, B.; Meshkova, L.; Bell, P.; Breakspear, R.

    2006-01-01

    In the macrotidal Severn estuary, UK, the dynamics of intertidal fine-gravel dunes were investigated. These dunes are migrating across a bedrock platform. Systematic observations were made of hydraulic climate, geometry, migration rates and internal sedimentary structures of the dunes. During spring tides, the ebb flow is dominant, dunes grow in height and have ebb orientated geometry with bedrock floors in the troughs. During neap tides, a weak flood flow may dominate. Dunes then are flood orientated or symmetrical. Neap dune heights decrease and the eroded sediment is stored in the dune troughs where the bedrock becomes blanketed by muddy gravel. During spring tides, instantaneous bed shear stresses reach 8 N m - 2 , sufficient to disrupt a 9 mm-gravel armour layer. However, a sustained bed shear stress of 4 N m - 2 is required to initiate dune migration at which time the critical depth-mean velocity is 1 m s - 1 . Ebb and flood inequalities in the bed shear stress explain the changes in dune asymmetry and internal structures. During flood tides, the crests of the dunes reverse such that very mobile sedimentary 'caps' overlie a more stable dune 'core'. Because ebb tides dominate, internal structures of the caps often are characterised by ebb orientated steep open-work foresets developed by strong tidal currents and some lower angle crossbeds deposited as weaker currents degrade foresets. The foresets forming the caps may be grouped into cosets (tidal bundles) and are separated from mud-infused cores of crossbeds that lie below, by reactivation and erosion surfaces blanketed by discontinuous mud drapes. The cores often exhibit distinctive muddy toe sets that define the spacing of tidal cosets.

  7. A tale of two pectins: Diverse fine structures can result from identical processive PME treatments on similar high DM subtrates

    Science.gov (United States)

    The effects of a processive pectin-methylesterase treatment on two different pectins, both possessing a high degree of methylesterification, were investigated. While the starting samples were purportedly very similar in fine structure, and even though the sample-averaged degree of methylesterificati...

  8. Optimum conditions for the determination of ionization potentials, appearance potentials and fine structure in ionization efficiency curves using edd technique

    International Nuclear Information System (INIS)

    Selim, Ezzat T.; El-Kholy, S.B.; Zahran, Nagwa F.

    1978-01-01

    The optimum conditions for determining ionization potentials as well as fine structure in electron impact ionization efficiency curves are studied using energy distribution difference technique. Applying these conditions to Ar + , Kr + , CO + 2 and N + from N 2 , very good agreement is obtained when compared with results determined by other techniques including UV spectroscopy. The merits and limitation of the technique are also discussed

  9. On the effects of the two-body non-fine-structure operators of the Breit-Pauli Hamiltonian

    International Nuclear Information System (INIS)

    Badnell, N.R.

    1997-01-01

    We have incorporated the two-body non-fine-structure operators of the Breit-Pauli Hamiltonian, namely contact spin-spin, two-body Darwin and orbit-orbit, into the program AUTOSTRUCTURE. Illustrative results are presented, including some for reactions involving the process of autoionization. (author)

  10. Standard model and fine structure constant at Planck distances in the Bennett-Brene-Nielsen-Picek random dynamics

    International Nuclear Information System (INIS)

    Laperashvili, L.V.

    1994-01-01

    The first part of the present paper contains a review of papers by Nielsen, Bennett, Brene and Picek which underly the model called random dynamics. The second part of the paper is devoted to calculating the fine structure constant by means of the path integration in the U(1)-lattice gauge theory

  11. Design, construction and operation features of high-rise structures

    Science.gov (United States)

    Mylnik, Alexey; Mylnik, Vladimir; Zubeeva, Elena; Mukhamedzhanova, Olga

    2018-03-01

    The article considers design, construction and operation features of high-rise facilities. The analysis of various situations, that come from improper designing, construction and operation of unique facilities, is carried out. The integrated approach is suggested, when the problems of choosing acceptable constructional solutions related to the functional purpose, architectural solutions, methods of manufacturing and installation, operating conditions for unique buildings and structures are being tackled. A number of main causes for the emergency destruction of objects under construction and operation is considered. A number of measures are proposed on the basis of factor classification in order to efficiently prevent the situations, when various negative options of design loads and emergency impacts occur.

  12. The sequence, structure and evolutionary features of HOTAIR in mammals

    Science.gov (United States)

    2011-01-01

    . Conclusions HOTAIR exists in mammals, has poorly conserved sequences and considerably conserved structures, and has evolved faster than nearby HoxC genes. Exons of HOTAIR show distinct evolutionary features, and a 239 bp domain in the 1804 bp exon6 is especially conserved. These features, together with the absence of some exons and sequences in mouse, rat and kangaroo, suggest ab initio generation of HOTAIR in marsupials. Structure prediction identifies two fragments in the 5' end exon1 and the 3' end domain B of exon6, with sequence and structure invariably occurring in various predicted structures of exon1, the domain B of exon6 and the full HOTAIR. PMID:21496275

  13. Discovery of Finely Structured Dynamic Solar Corona Observed in the Hi-C Telescope

    Science.gov (United States)

    Winebarger, A.; Cirtain, J.; Golub, L.; DeLuca, E.; Savage, S.; Alexander, C.; Schuler, T.

    2014-01-01

    In the summer of 2012, the High-resolution Coronal Imager (Hi-C) flew aboard a NASA sounding rocket and collected the highest spatial resolution images ever obtained of the solar corona. One of the goals of the Hi-C flight was to characterize the substructure of the solar corona. We therefore examine how the intensity scales from AIA resolution to Hi-C resolution. For each low-resolution pixel, we calculate the standard deviation in the contributing high-resolution pixel intensities and compare that to the expected standard deviation calculated from the noise. If these numbers are approximately equal, the corona can be assumed to be smoothly varying, i.e. have no evidence of substructure in the Hi-C image to within Hi-C's ability to measure it given its throughput and readout noise. A standard deviation much larger than the noise value indicates the presence of substructure. We calculate these values for each low-resolution pixel for each frame of the Hi-C data. On average, 70 percent of the pixels in each Hi-C image show no evidence of substructure. The locations where substructure is prevalent is in the moss regions and in regions of sheared magnetic field. We also find that the level of substructure varies significantly over the roughly 160 s of the Hi-C data analyzed here. This result indicates that the finely structured corona is concentrated in regions of heating and is highly time dependent.

  14. Restricted gene flow and fine-scale population structuring in tool using New Caledonian crows

    Science.gov (United States)

    Rutz, C.; Ryder, T. B.; Fleischer, R. C.

    2012-04-01

    New Caledonian crows Corvus moneduloides are the most prolific avian tool users. It has been suggested that some aspects of their complex tool use behaviour are under the influence of cultural processes, involving the social transmission—and perhaps even progressive refinement—of tool designs. Using microsatellite and mt-haplotype profiling of crows from three distinct habitats (dry forest, farmland and beachside habitat), we show that New Caledonian crow populations can exhibit significant fine-scale genetic structuring. Our finding that some sites of cultural isolation of crow groups. Restricted movement of birds between local populations at such small spatial scales, especially across habitat boundaries, illustrates how specific tool designs could be preserved over time, and how tool technologies of different crow groups could diverge due to drift and local selection pressures. Young New Caledonian crows have an unusually long juvenile dependency period, during which they acquire complex tool-related foraging skills. We suggest that the resulting delayed natal dispersal drives population-divergence patterns in this species. Our work provides essential context for future studies that examine the genetic makeup of crow populations across larger geographic areas, including localities with suspected cultural differences in crow tool technologies.

  15. All-Optical dc Nanotesla Magnetometry Using Silicon Vacancy Fine Structure in Isotopically Purified Silicon Carbide

    Directory of Open Access Journals (Sweden)

    D. Simin

    2016-07-01

    Full Text Available We uncover the fine structure of a silicon vacancy in isotopically purified silicon carbide (4H-^{28}SiC and reveal not yet considered terms in the spin Hamiltonian, originated from the trigonal pyramidal symmetry of this spin-3/2 color center. These terms give rise to additional spin transitions, which would be otherwise forbidden, and lead to a level anticrossing in an external magnetic field. We observe a sharp variation of the photoluminescence intensity in the vicinity of this level anticrossing, which can be used for a purely all-optical sensing of the magnetic field. We achieve dc magnetic field sensitivity better than 100  nT/sqrt[Hz] within a volume of 3×10^{-7}mm^{3} at room temperature and demonstrate that this contactless method is robust at high temperatures up to at least 500 K. As our approach does not require application of radio-frequency fields, it is scalable to much larger volumes. For an optimized light-trapping waveguide of 3  mm^{3}, the projection noise limit is below 100  fT/sqrt[Hz].

  16. Atomic transition energies and the variation of the fine-structure constant α

    International Nuclear Information System (INIS)

    Borschevsky, Anastasia; Eliav, Ephraim; Ishikawa, Yasuyuki; Kaldor, Uzi

    2006-01-01

    Relativistic energy shifts of atomic excitation energies, showing the dependence of these energies on the value of the fine-structure constant α, are needed to extract past changes in α from spectra of distant quasars. These shifts are calculated by the Fock-space coupled cluster method and its extrapolated intermediate Hamiltonian extension, which allow high-accuracy treatment of electron correlation. The accuracy of the method is tested by comparing 33 transition energies in heavy atoms (obtained with the laboratory α) with experiment; the average error is 258 cm -1 , and the largest error is 711 cm -1 . This may be compared with an average error of 432 cm -1 and a maximum error of 2150 cm -1 in the work of Dzuba et al., who reported most of the available energy shift calculations. The enhanced accuracy is due to more extensive inclusion of electron correlation. To obtain the energy shifts, we repeated the calculations with different values of α (within 0.1% of the current value). Our shifts differ by up to 30% from the values given by Dzuba et al., with an average difference of 9%. Based on the better quality of the present-day excitation energies, we believe the energy shifts reported here are more accurate than earlier work

  17. Fine-grained parallelism accelerating for RNA secondary structure prediction with pseudoknots based on FPGA.

    Science.gov (United States)

    Xia, Fei; Jin, Guoqing

    2014-06-01

    PKNOTS is a most famous benchmark program and has been widely used to predict RNA secondary structure including pseudoknots. It adopts the standard four-dimensional (4D) dynamic programming (DP) method and is the basis of many variants and improved algorithms. Unfortunately, the O(N(6)) computing requirements and complicated data dependency greatly limits the usefulness of PKNOTS package with the explosion in gene database size. In this paper, we present a fine-grained parallel PKNOTS package and prototype system for accelerating RNA folding application based on FPGA chip. We adopted a series of storage optimization strategies to resolve the "Memory Wall" problem. We aggressively exploit parallel computing strategies to improve computational efficiency. We also propose several methods that collectively reduce the storage requirements for FPGA on-chip memory. To the best of our knowledge, our design is the first FPGA implementation for accelerating 4D DP problem for RNA folding application including pseudoknots. The experimental results show a factor of more than 50x average speedup over the PKNOTS-1.08 software running on a PC platform with Intel Core2 Q9400 Quad CPU for input RNA sequences. However, the power consumption of our FPGA accelerator is only about 50% of the general-purpose micro-processors.

  18. Ecosystem structure and function in the SPRUCE chambers at fine resolution

    Science.gov (United States)

    Glenn, N. F.; Graham, J.; Spaete, L.; Hanson, P. J.

    2017-12-01

    The Spruce and Peatland Responses Under Climatic and Environmental change (SPRUCE; operated by DOE's Oak Ridge National Laboratory) aims to assess biological and ecological responses in a peat bog to a range of increased temperatures and the presence of elevated atmospheric CO2 concentrations. We are using terrestrial laser scanning (TLS) to monitor vegetation productivity and hummock-hollow structure at cm-scale in the SPRUCE plots to complement in-situ measurements of gross and net primary production. The hummock-hollow peatland microtopography is associated with fluctuating water levels and sphagnum mosses, and ultimately controls C and methane cycling. We estimate tree growth by calculating increases in tree height and canopy voxel volume between years with the TLS data. Microtopography is also characterized over time with TLS but by using gridded cells to classify regions into hummocks or hollows. Spectroscopy to quantify water content in the sphagnum is used to further classify these microtopographic regions. As multiple years of data collection occur, we will couple our fine-scale remote sensing measurements with in-situ measurements of CO2 and CH4 flux measures to capture species-specific productivity responses to warming and increased CO2.

  19. The Low Pitch of High-Frequency Complex Tones Relies on Temporal Fine Structure Information

    DEFF Research Database (Denmark)

    Santurette, Sébastien; Dau, Torsten

    2010-01-01

    High-frequency complex tones containing only unresolved harmonic components with a frequency spacing Δf usually evoke a low pitch equal to Δf. However, for inharmonic components, the low pitch is often found to deviate slightly from Δf. Whether this pitch shift relies exclusively on temporal fine...... structure (TFS) cues has been a matter of debate. It is also controversial up to which frequency TFS information remains available, and to what extent envelope cues become dominant as frequency increases. Using a pitch-matching paradigm, this study investigated whether the pitch of transposed tones.......5]. All stimuli were presented at 50 dB SPL in broadband pink-noise (13.5 dB/Hz at 1 kHz), and 40 matches per condition were obtained. For fenv = fc/11.5, the results favored hypothesis A for all values of fc, indicating that TFS cues are available and used for pitch extraction, up to at least 7 k...

  20. Preferred Compression Speed for Speech and Music and Its Relationship to Sensitivity to Temporal Fine Structure.

    Science.gov (United States)

    Moore, Brian C J; Sęk, Aleksander

    2016-09-07

    Multichannel amplitude compression is widely used in hearing aids. The preferred compression speed varies across individuals. Moore (2008) suggested that reduced sensitivity to temporal fine structure (TFS) may be associated with preference for slow compression. This idea was tested using a simulated hearing aid. It was also assessed whether preferences for compression speed depend on the type of stimulus: speech or music. Twenty-two hearing-impaired subjects were tested, and the stimulated hearing aid was fitted individually using the CAM2A method. On each trial, a given segment of speech or music was presented twice. One segment was processed with fast compression and the other with slow compression, and the order was balanced across trials. The subject indicated which segment was preferred and by how much. On average, slow compression was preferred over fast compression, more so for music, but there were distinct individual differences, which were highly correlated for speech and music. Sensitivity to TFS was assessed using the difference limen for frequency at 2000 Hz and by two measures of sensitivity to interaural phase at low frequencies. The results for the difference limens for frequency, but not the measures of sensitivity to interaural phase, supported the suggestion that preference for compression speed is affected by sensitivity to TFS. © The Author(s) 2016.

  1. Updated constraints on spatial variations of the fine-structure constant

    Directory of Open Access Journals (Sweden)

    A.M.M. Pinho

    2016-05-01

    Full Text Available Recent work by Webb et al. has provided indications of spatial variations of the fine-structure constant, α, at a level of a few parts per million. Using a dataset of 293 archival measurements, they further show that a dipole provides a statistically good fit to the data, a result subsequently confirmed by other authors. Here we show that a more recent dataset of dedicated measurements further constrains these variations: although there are only 10 such measurements, their uncertainties are considerably smaller. We find that a dipolar variation is still a good fit to the combined dataset, but the amplitude of such a dipole must be somewhat smaller: 8.1±1.7 ppm for the full dataset, versus 9.4±2.2 ppm for the Webb et al. data alone, both at the 68.3% confidence level. Constraints on the direction on the sky of such a dipole are also significantly improved. On the other hand the data can't yet discriminate between a pure spatial dipole and one with an additional redshift dependence.

  2. HELICAL MOTIONS OF FINE-STRUCTURE PROMINENCE THREADS OBSERVED BY HINODE AND IRIS

    Energy Technology Data Exchange (ETDEWEB)

    Okamoto, Takenori J. [National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan); Liu, Wei [Bay Area Environmental Research Institute, 625 2nd Street, Suite 209, Petaluma, CA 94952 (United States); Tsuneta, Saku, E-mail: joten.okamoto@nao.ac.jp [ISAS/JAXA, Sagamihara, Kanagawa 252-5210 (Japan)

    2016-11-10

    Fine-structure dynamics in solar prominences holds critical clues to understanding their physical nature of significant space-weather implications. We report evidence of rotational motions of horizontal helical threads in two active-region prominences observed by the Hinode and/or Interface Region Imaging Spectrograph satellites at high resolution. In the first event, we found transverse motions of brightening threads at speeds up to 55 km s{sup -1} seen in the plane of the sky. Such motions appeared as sinusoidal space–time trajectories with a typical period of ∼390 s, which is consistent with plane-of-sky projections of rotational motions. Phase delays at different locations suggest the propagation of twists along the threads at phase speeds of 90–270 km s{sup -1}. At least 15 episodes of such motions occurred in two days, none associated with an eruption. For these episodes, the plane-of-sky speed is linearly correlated with the vertical travel distance, suggestive of a constant angular speed. In the second event, we found Doppler velocities of 30–40 km s{sup -1} in opposite directions in the top and bottom portions of the prominence, comparable to the plane-of-sky speed. The moving threads have about twice broader line widths than stationary threads. These observations, when taken together, provide strong evidence for rotations of helical prominence threads, which were likely driven by unwinding twists triggered by magnetic reconnection between twisted prominence magnetic fields and ambient coronal fields.

  3. Fine-structure resolved rotational transitions and database for CN+H2 collisions

    Science.gov (United States)

    Burton, Hannah; Mysliwiec, Ryan; Forrey, Robert C.; Yang, B. H.; Stancil, P. C.; Balakrishnan, N.

    2018-06-01

    Cross sections and rate coefficients for CN+H2 collisions are calculated using the coupled states (CS) approximation. The calculations are benchmarked against more accurate close-coupling (CC) calculations for transitions between low-lying rotational states. Comparisons are made between the two formulations for collision energies greater than 10 cm-1. The CS approximation is used to construct a database which includes highly excited rotational states that are beyond the practical limitations of the CC method. The database includes fine-structure resolved rotational quenching transitions for v = 0 and j ≤ 40, where v and j are the vibrational and rotational quantum numbers of the initial state of the CN molecule. Rate coefficients are computed for both para-H2 and ortho-H2 colliders. The results are shown to be in good agreement with previous calculations, however, the rates are substantially different from mass-scaled CN+He rates that are often used in astrophysical models.

  4. The running fine structure constant α(E) via the Adler function

    International Nuclear Information System (INIS)

    Jegerlehner, F.

    2008-06-01

    We present an up-to-date analysis for a precise determination of the effective fine structure constant and discuss the prospects for future improvements. We advocate to use a determination monitored by the Adler function which allows us to exploit perturbative QCD in an optimal well controlled way. Together with a long term program of hadronic cross section measurements at energies up to a few GeV, a determination of α(M Z ) at a precision comparable to the one of the Z mass M Z should be feasible. Presently α(E) at E >1 GeV is the least precisely known of the fundamental parameters of the SM. Since, in spite of substantial progress due to new BaBar exclusive data, the region 1.4 to 2.4 GeV remains the most problematic one a major step in the reduction of the uncertainties are expected from VEPP-2000 and from a possible ''high-energy'' option DAFNE-2 at Frascati. The up-to-date evaluation reads Δ (5) had (M 2 Z )=0.027515±0.000149 or α -1 (M 2 Z )=128.957±0.020. (orig.)

  5. Fine Structure in Quasar Flows Revealed by Lens-Aided Multi-Angle Spectroscopy (LAMAS)

    Science.gov (United States)

    Green, Paul J.

    2006-09-01

    Spectral differences between lensed quasar image components are common. Since lensing is intrinsically achromatic, these differences are typically explained as the effect of either microlensing, or as light path time delays sampling intrinsic quasar spectral variability. In some cases, neither explanation seems sufficient. Here we advance a novel third hypothesis: some spectral differences are due to small line-of- sight differences through quasar disk wind outflows, taking the widest separation lens SDSSJ1004+4112 as a key example. We show that small changes in sightline may traverse streams with significantly differing columns. The implications are many. Fine structure in these outflows may change the observed spectra on arcsec scales. Though difficult to detect observationally, high ionization, high velocity-width streams may sculpt the optical and X-ray spectra of most quasars. We discuss existing multi-epoch optical/UV spectroscopy and results from X-ray observations both by Chandra and XMM in this context, and sketch further possible tests. The author gratefully acknowledges support through NASA contract NAS8-03060 (CXC).

  6. Fine structure of spermatogenesis in polyopisthocotylid monogeneans (Protomicrocotyle ivoriensis, Gastrocotyle sp.).

    Science.gov (United States)

    Schmahl, G; Obiekezie, A

    1991-01-01

    The development of spermatozoa in the polyopisthocotylean fish-gill flukes Protomicrocotyle ivoriensis and Gastrocotyle sp. was investigated by light and transmission electron microscopy. In both species the spermatogonia were undifferentiated cells, the cytoplasm of which contained numerous free ribosomes, and successive mitoses gave rise to primary spermatocytes, which are clearly identified by the presence of synaptonemal complexes in their nuclei. As compared with that of the spermatogonia, the cytoplasm of the primary spermatocytes contained an increased number of ribosomes. Golgi complexes were frequently seen in the spermatocytes of P. ivoriensis but not in Gastrocotyle sp. In P. ivoriensis the secondary spermatocytes were separated by interspaces between the irregularly shaped cell surfaces. In both species a syncytial mass of spermatids developed, which gave rise to 64 spermatozoa. Cross sections of the mature spermatozoa of both species revealed the presence of numerous submembranous microtubules and two axonemes showing a pattern of 9 doublet peripheral microtubules plus a central one. In contrast to microtubules plus a central one. In contrast to P. ivoriensis, in Gastrocotyle sp. the axonemes originated from different places at the axis of the spermatozoon. With respect to the other results obtained, the spermiogenesis and the fine structure of spermatozoa of both species studied were similar to previous findings in other polyopisthocotyleans.

  7. Finite difference method calculations of X-ray absorption fine structure for copper

    Energy Technology Data Exchange (ETDEWEB)

    Bourke, J.D. [School of Physics, University of Melbourne, Parkville, Vic 3010 (Australia); Chantler, C.T. [School of Physics, University of Melbourne, Parkville, Vic 3010 (Australia)]. E-mail: chantler@physics.unimelb.edu.au; Witte, C. [School of Physics, University of Melbourne, Parkville, Vic 3010 (Australia)

    2007-01-15

    The finite difference method is extended to calculate X-ray absorption fine structure (XAFS) for solid state copper. These extensions include the incorporation of a Monte Carlo frozen phonon technique to simulate the effect of thermal vibrations under a correlated Debye-Waller model, and the inclusion of broadening effects from inelastic processes. Spectra are obtained over an energy range in excess of 300 eV above the K absorption edge-more than twice the greatest energy range previously reported for a solid state calculation using this method. We find this method is highly sensitive to values of the photoelectron inelastic mean free path, allowing us to probe the accuracy of current models of this parameter, particularly at low energies. We therefore find that experimental data for the photoelectron inelastic mean free path can be obtained by this method. Our results compare favourably with high precision measurements of the X-ray mass attenuation coefficient for copper, reaching agreement to within 3%, and improving previous results using the finite difference method by an order of magnitude.

  8. Dynamic magnetization models for soft ferromagnetic materials with coarse and fine domain structures

    Energy Technology Data Exchange (ETDEWEB)

    Zirka, S.E., E-mail: zirka@email.dp.ua [Department of Physics and Technology, Dnepropetrovsk National University, Gagarin 72, 49050 Dnepropetrovsk (Ukraine); Moroz, Y.I. [Department of Physics and Technology, Dnepropetrovsk National University, Gagarin 72, 49050 Dnepropetrovsk (Ukraine); Steentjes, S.; Hameyer, K. [Institute of Electrical Machines, RWTH Aachen University, Schinkelstr. 4, 52056 Aachen (Germany); Chwastek, K. [Faculty of Electrical Engineering, Czestochowa University of Technology, al. AK 17, 42-201 Czestochowa (Poland); Zurek, S. [Megger Instruments Ltd., Archcliffe Road, Dover, Kent, CT17 9EN (United Kingdom); Harrison, R.G. [Department of Electronics, Carleton University, Ottawa, Canada K1S 5B6 (Canada)

    2015-11-15

    We consider dynamic models, both numerical and analytical, that reproduce the magnetization field H(B) and the energy loss in ferromagnetic sheet materials with different domain structures. Conventional non-oriented (NO) and grain-oriented (GO) electrical steels are chosen as typical representatives of fine-domain and coarse-domain materials. The commonly-accepted loss separation procedures in these materials are critically analyzed. The use of a well-known simplified (“classical”) expression for the eddy-current loss is identified as the primary source of mistaken evaluations of excess loss in NO steel, in which the loss components can only be evaluated using the Maxwell (penetration) equation. The situation is quite different in GO steel, in which the loss separation is uncertain, but the total dynamic loss is several times higher than that explained by any version (numerical or analytical) of the classical approach. To illustrate the uncertainty of the loss separation in GO steel, we show that the magnetization field, and thus the total loss, in this material can be represented with equal accuracy using either the existing three-component approach or our proposed two-component technique, which makes no distinction between classical eddy-current and excess fields and losses. - Highlights: • Critical analysis of a ferromagnetic-material loss-separation principle. • This is to warn materials-science engineers about the inaccuracies resulting from this principle. • A transient model having a single dynamic component is proposed.

  9. Can temporal fine structure represent the fundamental frequency of unresolved harmonics?

    Science.gov (United States)

    Oxenham, Andrew J; Micheyl, Christophe; Keebler, Michael V

    2009-04-01

    At least two modes of pitch perception exist: in one, the fundamental frequency (F0) of harmonic complex tones is estimated using the temporal fine structure (TFS) of individual low-order resolved harmonics; in the other, F0 is derived from the temporal envelope of high-order unresolved harmonics that interact in the auditory periphery. Pitch is typically more accurate in the former than in the latter mode. Another possibility is that pitch can sometimes be coded via the TFS from unresolved harmonics. A recent study supporting this third possibility [Moore et al. (2006a). J. Acoust. Soc. Am. 119, 480-490] based its conclusion on a condition where phase interaction effects (implying unresolved harmonics) accompanied accurate F0 discrimination (implying TFS processing). The present study tests whether these results were influenced by audible distortion products. Experiment 1 replicated the original results, obtained using a low-level background noise. However, experiments 2-4 found no evidence for the use of TFS cues with unresolved harmonics when the background noise level was raised, or the stimulus level was lowered, to render distortion inaudible. Experiment 5 measured the presence and phase dependence of audible distortion products. The results provide no evidence that TFS cues are used to code the F0 of unresolved harmonics.

  10. A glimpsing account of the role of temporal fine structure information in speech recognition.

    Science.gov (United States)

    Apoux, Frédéric; Healy, Eric W

    2013-01-01

    Many behavioral studies have reported a significant decrease in intelligibility when the temporal fine structure (TFS) of a sound mixture is replaced with noise or tones (i.e., vocoder processing). This finding has led to the conclusion that TFS information is critical for speech recognition in noise. How the normal -auditory system takes advantage of the original TFS, however, remains unclear. Three -experiments on the role of TFS in noise are described. All three experiments measured speech recognition in various backgrounds while manipulating the envelope, TFS, or both. One experiment tested the hypothesis that vocoder processing may artificially increase the apparent importance of TFS cues. Another experiment evaluated the relative contribution of the target and masker TFS by disturbing only the TFS of the target or that of the masker. Finally, a last experiment evaluated the -relative contribution of envelope and TFS information. In contrast to previous -studies, however, the original envelope and TFS were both preserved - to some extent - in all conditions. Overall, the experiments indicate a limited influence of TFS and suggest that little speech information is extracted from the TFS. Concomitantly, these experiments confirm that most speech information is carried by the temporal envelope in real-world conditions. When interpreted within the framework of the glimpsing model, the results of these experiments suggest that TFS is primarily used as a grouping cue to select the time-frequency regions -corresponding to the target speech signal.

  11. Fine structures in 14C emission of 223Ra and 224Ra

    International Nuclear Information System (INIS)

    Hourani, E.; Rosier, L.; Berrier-Ronsin, G.; Elayi, A.; Mueller, A.C.; Rappenecker, G.; Rotbard, G.; Renou, G.; Liebe, A.; Stab, L.

    1991-01-01

    The measurement of the energy spectrum of 14 C nuclei emitted in the spontaneous radioactivity from 223 Ra and 224 Ra has been carried out, using thin and intense sources (480 MBq for 223 Ra and 3550 MBq for 224 Ra). The sources were obtained by implanting mass-separated beams from ISOLDE (CERN) into Al and vitreous C catchers. The measurement was performed with the supraconducting solenoidal spectrometer SOLENO installed at Orsay. The discovery, of a fine structure in the energy spectrum of 14 C emission from 223 Ra, which is analogous to the one known for α emission, is confirmed. Only 13% of the branching ratio in 14 C decay leads to the ground state of the residual nucleus, while 8l% to the first excited state. For 14 C emission of 224 Ra, a lower limit of 2 for the hindrance factor has been measured for the transition to the first excited state in the residual nucleus. Also, a precise identification in Z with a E·ΔE telescope has been performed for the radiation from the 223 Ra source. (author) 22 refs., 11 figs., 1 tab

  12. The Potamophylax nigricornis group (Trichoptera, Limnephilidae: resolution of phylogenetic species by fine structure analysis

    Directory of Open Access Journals (Sweden)

    Oláh, J.

    2013-11-01

    Full Text Available Applying the phylogenetic species concept and the sexual selection theory we have reviewed some natal aspects of incipient species and their accelerated evolution. How can we recognise early stages of divergence? Which selection pressures are at work during speciation? Which pathways accelerate the speed of speciation? Which kinds of trait variabilities makes difficult to find initial split criteria? Elaborating the principles of Fine Structure Analysis (FSA and the morphological Initial Split Criteria (ISP it was discovered that the European spring dwelling caddisfly Potamophylax nigricornis doesn’tbelong to a single species. It represents an entire species group with seventeen peripatric species evolving on the southernperipheries of the distributional area. Four new species subgroups have been erected: Potamophylax nigricornis new species subgroup, P. elegantulus new species subgroup, P. horgos new species subgroup, P. simas new species subgroup. Eleven new species have been described: Potamophylax apados sp. nov., P. fules sp. nov., P. fureses sp. nov., P. hasas sp. novov., P. horgos sp. nov., P. kethas sp. nov., P. lemezes sp. nov., P. peremes sp. nov., P. simas sp. nov., P. tuskes sp. nov., P. ureges sp. nov. One Potamophylax sp. nov. has been differentiated and three new species status have been documented:Potamophylax elegantulus (Klapálek stat. n., P. mista (Navás stat. nov., P. testaceus (Zetterstedt stat. nov.

  13. X ray absorption fine structure of systems in the anharmonic limit

    Science.gov (United States)

    Mustredeleon, J.; Conradson, S. D.; Batistic, I.; Bishop, A. R.; Raistrick, I.; Jackson, W. E.; Brown, G. E.

    A new approach to the analysis of x-ray absorption fine structure (XAFS) data is presented. It is based on the use of radial distribution functions directly calculated from a single-particle ion Hamiltonian containing model potentials. The starting point of this approach is the statistical average of the XAFS for an atomic pair. This average can be computed using a radial distribution function (RDF), which can be expressed in terms of the eigenvalues and wavefunctions associated with the model potential. The pair potential describing the ionic motion is then expressed in terms of parameters that are determined by fitting this statistical average to the experimental XAFS spectrum. This approach allows the use of XAFS as a tool for mapping near-neighbor interatomic potentials, and allows the treatment of systems which exhibit strongly anharmonic potentials which can be treated by perturbative methods. Using this method we have analyzed the high temperature behavior of the oxygen contributions to the Fe K-edge XAFS in the ferrosilicate minerals andradite (Ca3Fe2Si3O12) and magnesiowustite (Mg(0.9)Fe(0.1)O). Using a temperature dependent anharmonic correction derived from these model compounds, we have found evidence for a local structural change in the Fe-O coordination environment upon melting of the geologically important mineral fayalite (Fe2SiO4). We have also employed this method to the study of the axial oxygen contributions to the polarized Cu K-edge XAFS on oriented samples of YBa2Cu3O7 and related compounds. From this study we find evidence for an axial oxygen-centered lattice distortion accompanying the superconducting phase transition and a correlation between this distortion and Tc. The relation of the observed lattice distortion to mechanisms of superconductivity is discussed.

  14. X-ray absorption fine structure of systems in the anharmonic limit

    International Nuclear Information System (INIS)

    Mustre de Leon, J.; Conradson, S.D.; Batistic, I.; Bishop, A.R.; Raistrick, I.; Jackson, W.E.; Brown, G.E.

    1991-01-01

    A new approach to the analysis of x-ray absorption fine structure (XAFS) data is presented. It is based on the use of radial distribution functions directly calculated from a single-particle ion hamiltonian containing model potentials. The starting point of this approach is the statistical average of the XAFS for an atomic pair. This average can be computed using a radial distribution function (RDF), which can be expressed in terms of the eigenvalues and wavefunctions associated with the model potential. The pair potential describing the ionic motion is then expressed in terms of parameters that are determined by fitting this statistical average to the experimental XAFS spectrum. This approach allow the use of XAFS as a tool for mapping near-neighbor interatomic potentials, and allows the treatment of systems which exhibit strongly anharmonic potentials which can be treated by perturbative methods. Using this method we have analyzed the high temperature behavior of the oxygen contributions to the Fe K-edge XAFS in the ferrosilicate minerals andradite (Ca 3 Fe 2 Si 3 O 12 ) and magnesiowustite (Mg 0.9 Fe 0.1 O). Using a temperature dependent anharmonic correction derived from these model compounds, we have found evidence for a local structural change in the Fe-O coordination environment upon melting of the geologically important mineral fayalite (Fe 2 SiO 4 ). We have also employed this method to the study of the axial oxygen contributions to the polarized Cu K-edge XAFS on oriented samples of YBa 2 Cu 3 O 7 and related compounds. From this study we find evidence for an axial oxygen-centered lattice distortion accompanying the superconducting phase transition and a correlation between this distortion and T c . The relation of the observed lattice distortion to mechanisms of superconductivity is discussed. 33 refs., 6 figs

  15. Structure of bimetallic clusters. Extended x-ray absorption fine structure (EXAFS) studies of Rh--Cu clusters

    International Nuclear Information System (INIS)

    Meitzner, G.; Via, G.H.; Lytle, F.W.; Sinfelt, J.H.

    1983-01-01

    An investigation of the structure of the bimetallic clusters present in rhodium--copper catalysts was conducted with the use of extended x-ray absorption fine structure (EXAFS) measurements. Two catalysts were studied, both employing silica as a support for the clusters and both containing 1 wt. % rhodium. In one catalyst the Cu:Rh atomic ratio was 1:2 and in the other 1:1. Studies were made of the EXAFS associated with the K absorption edges of the rhodium and copper. The results of the EXAFS studies indicate that copper concentrates at the surface of the rhodium--copper clusters. In this regard the results are similar to our earlier reported results on ruthenium--copper clusters. However, the extent of surface segregation of the copper appears to be less pronounced for rhodium--copper clusters. This result is reasonable on the basis that rhodium and copper, unlike ruthenium and copper, exhibit at least some miscibility in the bulk

  16. Characterizing, measuring, and utilizing the resolution of CT imagery for improved quantification of fine-scale features

    Energy Technology Data Exchange (ETDEWEB)

    Ketcham, Richard A., E-mail: ketcham@jsg.utexas.edu; Hildebrandt, Jordan

    2014-04-01

    Quantitative results extracted from computed tomographic (CT) data sets should be the same across resolutions and between different instruments and laboratory groups. Despite the proliferation of scanners and data processing methods and tools, and scientific studies utilizing them, relatively little emphasis has been given to ensuring that these results are comparable or reproducible. This issue is particularly pertinent when the features being imaged and measured are of the same order size as data voxels, as is often the case with fracture apertures, pore throats, and cell walls. We have created a tool that facilitates quantification of the spatial resolution of CT data via its point-spread function (PSF), in which the user draws a traverse across a sharp interface between two materials and a Gaussian PSF is fitted to the blurring across that interface. Geometric corrections account for voxel shape and the angle of the traverse to the interface, which does not need to be orthogonal. We use the tool to investigate a series of grid phantoms scanned at varying conditions and observe how the PSF varies within and between slices. The PSF increases with increasing radial distance within slices, and can increase tangentially with increasing radial distance in CT data sets acquired with relatively few projections. The PSF between CT slices is similar to that within slices when a 2-D detector is used, but is much sharper when the data are acquired one slice at a time with a collimated linear detector array. The capability described here can be used not only to calibrate processing algorithms that use deconvolution operations, but it can also help evaluate scans on a routine basis within and between CT research groups, and with respect to the features within the imagery that are being measured.

  17. Microwave spectroscopy of the 1 s n p P3J fine structure of high Rydberg states in 4He

    Science.gov (United States)

    Deller, A.; Hogan, S. D.

    2018-01-01

    The 1 s n p P3J fine structure of high Rydberg states in helium has been measured by microwave spectroscopy of single-photon transitions from 1 s n s S31 levels in pulsed supersonic beams. For states with principal quantum numbers in the range from n =34 to 36, the J =0 →2 and J =1 →2 fine structure intervals were both observed. For values of n between 45 and 51 only the larger J =0 →2 interval was resolved. The experimental results are in good agreement with theoretical predictions. Detailed characterization of residual uncanceled electric and magnetic fields in the experimental apparatus and calculations of the Stark and Zeeman structures of the Rydberg states in weak fields were used to quantify systematic contributions to the uncertainties in the measurements.

  18. QUIESCENT PROMINENCES IN THE ERA OF ALMA: SIMULATED OBSERVATIONS USING THE 3D WHOLE-PROMINENCE FINE STRUCTURE MODEL

    Energy Technology Data Exchange (ETDEWEB)

    Gunár, Stanislav; Heinzel, Petr [Astronomical Institute, The Czech Academy of Sciences, 25165 Ondřejov (Czech Republic); Mackay, Duncan H. [School of Mathematics and Statistics, University of St Andrews, North Haugh, St Andrews KY16 9SS (United Kingdom); Anzer, Ulrich [Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, D-85740 Garching bei München (Germany)

    2016-12-20

    We use the detailed 3D whole-prominence fine structure model to produce the first simulated high-resolution ALMA observations of a modeled quiescent solar prominence. The maps of synthetic brightness temperature and optical thickness shown in the present paper are produced using a visualization method for synthesis of the submillimeter/millimeter radio continua. We have obtained the simulated observations of both the prominence at the limb and the filament on the disk at wavelengths covering a broad range that encompasses the full potential of ALMA. We demonstrate here extent to which the small-scale and large-scale prominence and filament structures will be visible in the ALMA observations spanning both the optically thin and thick regimes. We analyze the relationship between the brightness and kinetic temperature of the prominence plasma. We also illustrate the opportunities ALMA will provide for studying the thermal structure of the prominence plasma from the cores of the cool prominence fine structure to the prominence–corona transition region. In addition, we show that detailed 3D modeling of entire prominences with their numerous fine structures will be important for the correct interpretation of future ALMA observations of prominences.

  19. DISCOVERY OF FINELY STRUCTURED DYNAMIC SOLAR CORONA OBSERVED IN THE Hi-C TELESCOPE

    Energy Technology Data Exchange (ETDEWEB)

    Winebarger, Amy R.; Cirtain, Jonathan; Savage, Sabrina; Alexander, Caroline [NASA Marshall Space Flight Center, ZP 13, Huntsville, AL 35812 (United States); Golub, Leon; DeLuca, Edward [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Schuler, Timothy, E-mail: amy.r.winebarger@nasa.gov [State University of New York College at Buffalo, 1300 Elmwood Avenue, Buffalo, NY 14222 (United States)

    2014-05-20

    In the Summer of 2012, the High-resolution Coronal Imager (Hi-C) flew on board a NASA sounding rocket and collected the highest spatial resolution images ever obtained of the solar corona. One of the goals of the Hi-C flight was to characterize the substructure of the solar corona. We therefore examine how the intensity scales from AIA resolution to Hi-C resolution. For each low-resolution pixel, we calculate the standard deviation in the contributing high-resolution pixel intensities and compare that to the expected standard deviation calculated from the noise. If these numbers are approximately equal, the corona can be assumed to be smoothly varying, i.e., have no evidence of substructure in the Hi-C image to within Hi-C's ability to measure it given its throughput and readout noise. A standard deviation much larger than the noise value indicates the presence of substructure. We calculate these values for each low-resolution pixel for each frame of the Hi-C data. On average, 70% of the pixels in each Hi-C image show no evidence of substructure. The locations where substructure is prevalent is in the moss regions and in regions of sheared magnetic field. We also find that the level of substructure varies significantly over the roughly 160 s of the Hi-C data analyzed here. This result indicates that the finely structured corona is concentrated in regions of heating and is highly time dependent.

  20. [Study on the fine structure of K-feldspar of Qichun granite].

    Science.gov (United States)

    Du, Deng-Wen; Hong, Han-Lie; Fan, Kan; Wang, Chao-Wen; Yin, Ke

    2013-03-01

    Fine structure of K-feldspar from the Qichun granite was investigated using X-ray diffraction (XRD), Fourier infrared absorption spectroscopy (FTIR), and inductively coupled plasma mass spectrometry methods to understand the evolution of the granitic magmatism and its correlation to molybdenite mineralization. The XRD results showed that K-feldspar of the potassic alteration veins has higher ordering index and triclinicity and is namely microcline with triclinic symmetry. K-feldspar of the early cretaceous granite has relatively lower ordering index and has widening [131] peak and is locally triclinic ordering. K-feldspar of the late cretaceous granite has lowest ordering index and sharp [131] peak and is honiogeneously monoclinic. The FTIR results showed that the IR spectra of the Qichun K-feldspar are similar to that of orthoclase reported by Farmer (1974). The 640 cm-1 absorption band increases while the 540 cm-' absorption band decreases with increase in K-feldspar ordering index, also, the 1,010 cm-1 absorption band separates into 1,010 and 1,046 cm-1 absorption bands, with a change in the band shape from widening to sharp outline. The ICP-MS results suggested that K-feldspar of the early cretaceous granite has relatively higher metal elements and rare earth elements, and the granite exhibits better mineralization background, K-feldspar of the potassic alteration veins has markedly lower Sr and Ba, indicating that the alteration fluid originated from the granitic magmatism, and hence, potassic alteration is a good indicator for molybdenite exploration.

  1. DISCOVERY OF FINELY STRUCTURED DYNAMIC SOLAR CORONA OBSERVED IN THE Hi-C TELESCOPE

    International Nuclear Information System (INIS)

    Winebarger, Amy R.; Cirtain, Jonathan; Savage, Sabrina; Alexander, Caroline; Golub, Leon; DeLuca, Edward; Schuler, Timothy

    2014-01-01

    In the Summer of 2012, the High-resolution Coronal Imager (Hi-C) flew on board a NASA sounding rocket and collected the highest spatial resolution images ever obtained of the solar corona. One of the goals of the Hi-C flight was to characterize the substructure of the solar corona. We therefore examine how the intensity scales from AIA resolution to Hi-C resolution. For each low-resolution pixel, we calculate the standard deviation in the contributing high-resolution pixel intensities and compare that to the expected standard deviation calculated from the noise. If these numbers are approximately equal, the corona can be assumed to be smoothly varying, i.e., have no evidence of substructure in the Hi-C image to within Hi-C's ability to measure it given its throughput and readout noise. A standard deviation much larger than the noise value indicates the presence of substructure. We calculate these values for each low-resolution pixel for each frame of the Hi-C data. On average, 70% of the pixels in each Hi-C image show no evidence of substructure. The locations where substructure is prevalent is in the moss regions and in regions of sheared magnetic field. We also find that the level of substructure varies significantly over the roughly 160 s of the Hi-C data analyzed here. This result indicates that the finely structured corona is concentrated in regions of heating and is highly time dependent

  2. Titanium dioxide fine structures by RF magnetron sputter method deposited on an electron-beam resist mask

    Science.gov (United States)

    Hashiba, Hideomi; Miyazaki, Yuta; Matsushita, Sachiko

    2013-09-01

    Titanium dioxide (TiO2) has been draw attention for wide range of applications from photonic crystals for visible light range by its catalytic characteristics to tera-hertz range by its high refractive index. We present an experimental study of fabrication of fine structures of TiO2 with a ZEP electron beam resist mask followed by Ti sputter deposition techniques. A TiO2 thin layer of 150 nm thick was grown on an FTO glass substrate with a fine patterned ZEP resist mask by a conventional RF magnetron sputter method with Ti target. The deposition was carried out with argon-oxygen gases at a pressure of 5.0 x 10 -1 Pa in a chamber. During the deposition, ratio of Ar-O2 gas was kept to the ratio of 2:1 and the deposition ratio was around 0.5 Å/s to ensure enough oxygen to form TiO2 and low temperature to avoid deformation of fine pattern of the ZPU resist mask. Deposited TiO2 layers are white-transparent, amorphous, and those roughnesses are around 7 nm. Fabricated TiO2 PCs have wider TiO2 slabs of 112 nm width leaving periodic 410 x 410 nm2 air gaps. We also studied transformation of TiO2 layers and TiO2 fine structures by baking at 500 °C. XRD measurement for TiO2 shows that the amorphous TiO2 transforms to rutile and anatase forms by the baking while keeping the same profile of the fine structures. Our fabrication method can be one of a promising technique to optic devices on researches and industrial area.

  3. Detecting PHG frames in wireless capsule endoscopy video by integrating rough global dominate-color with fine local texture features

    Science.gov (United States)

    Liu, Xiaoqi; Wang, Chengliang; Bai, Jianying; Liao, Guobin

    2018-02-01

    Portal hypertensive gastropathy (PHG) is common in gastrointestinal (GI) diseases, and a severe stage of PHG (S-PHG) is a source of gastrointestinal active bleeding. Generally, the diagnosis of PHG is made visually during endoscopic examination; compared with traditional endoscopy, (wireless capsule endoscopy) WCE with noninvasive and painless is chosen as a prevalent tool for visual observation of PHG. However, accurate measurement of WCE images with PHG is a difficult task due to faint contrast and confusing variations in background gastric mucosal tissue for physicians. Therefore, this paper proposes a comprehensive methodology to automatically detect S-PHG images in WCE video to help physicians accurately diagnose S-PHG. Firstly, a rough dominatecolor-tone extraction approach is proposed for better describing global color distribution information of gastric mucosa. Secondly, a hybrid two-layer texture acquisition model is designed by integrating co-occurrence matrix into local binary pattern to depict complex and unique gastric mucosal microstructure local variation. Finally, features of mucosal color and microstructure texture are merged into linear support vector machine to accomplish this automatic classification task. Experiments were implemented on an annotated data set including 1,050 SPHG and 1,370 normal images collected from 36 real patients of different nationalities, ages and genders. By comparison with three traditional texture extraction methods, our method, combined with experimental results, performs best in detection of S-PHG images in WCE video: the maximum of accuracy, sensitivity and specificity reach 0.90, 0.92 and 0.92 respectively.

  4. Structure in galactic soft X-ray features

    International Nuclear Information System (INIS)

    Davelaar, J.

    1979-01-01

    Observations are described of the soft X-ray background in a part of the northern hemisphere in the energy range 0.06 - 3.0 keV. The X-ray instruments, placed onboard a sounding rocket, are a one-dimensional focusing collector with multi-cell proportional counters in the focal plane and eight large area counters on deployable panels. A description of the instruments and their preflight calibration is given. Precautions were taken to prevent UV sensitivity of the X-ray instruments. The observation program, which consisted of a number of pre-programmed slow scans, is outlined. The spectral date on the soft X-ray background in these and previous observations showed that at least two components of different temperature are present. A low temperature component of approximately (3-10)x10 5 is found all over the sky. Components of higher temperature approximately 3x10 6 K are found in regions of soft X-ray enhancement; The North Polar Spur has been observed in two scans at the galactic latitude b=25 0 and b=75 0 . The X-ray ridge structure is found to be strongly energy dependent. The low energy data ( 0 reveals two separate emission features on the ridge, both probably of finite extensions (approximately equal to 0 0 .5). A wider X-ray ridge (approximately equal to 10 0 ) is observed above 0.4 keV. (Auth.)

  5. Ultra-Fine Scale Spatially-Integrated Mapping of Habitat and Occupancy Using Structure-From-Motion.

    Directory of Open Access Journals (Sweden)

    Philip McDowall

    Full Text Available Organisms respond to and often simultaneously modify their environment. While these interactions are apparent at the landscape extent, the driving mechanisms often occur at very fine spatial scales. Structure-from-Motion (SfM, a computer vision technique, allows the simultaneous mapping of organisms and fine scale habitat, and will greatly improve our understanding of habitat suitability, ecophysiology, and the bi-directional relationship between geomorphology and habitat use. SfM can be used to create high-resolution (centimeter-scale three-dimensional (3D habitat models at low cost. These models can capture the abiotic conditions formed by terrain and simultaneously record the position of individual organisms within that terrain. While coloniality is common in seabird species, we have a poor understanding of the extent to which dense breeding aggregations are driven by fine-scale active aggregation or limited suitable habitat. We demonstrate the use of SfM for fine-scale habitat suitability by reconstructing the locations of nests in a gentoo penguin colony and fitting models that explicitly account for conspecific attraction. The resulting digital elevation models (DEMs are used as covariates in an inhomogeneous hybrid point process model. We find that gentoo penguin nest site selection is a function of the topography of the landscape, but that nests are far more aggregated than would be expected based on terrain alone, suggesting a strong role of behavioral aggregation in driving coloniality in this species. This integrated mapping of organisms and fine scale habitat will greatly improve our understanding of fine-scale habitat suitability, ecophysiology, and the complex bi-directional relationship between geomorphology and habitat use.

  6. A theory of self-organized zonal flow with fine radial structure in tokamak

    Science.gov (United States)

    Zhang, Y. Z.; Liu, Z. Y.; Xie, T.; Mahajan, S. M.; Liu, J.

    2017-12-01

    The (low frequency) zonal flow-ion temperature gradient (ITG) wave system, constructed on Braginskii's fluid model in tokamak, is shown to be a reaction-diffusion-advection system; it is derived by making use of a multiple spatiotemporal scale technique and two-dimensional (2D) ballooning theory. For real regular group velocities of ITG waves, two distinct temporal processes, sharing a very similar meso-scale radial structure, are identified in the nonlinear self-organized stage. The stationary and quasi-stationary structures reflect a particular feature of the poloidal group velocity. The equation set posed to be an initial value problem is numerically solved for JET low mode parameters; the results are presented in several figures and two movies that show the spatiotemporal evolutions as well as the spectrum analysis—frequency-wave number spectrum, auto power spectrum, and Lissajous diagram. This approach reveals that the zonal flow in tokamak is a local traveling wave. For the quasi-stationary process, the cycle of ITG wave energy is composed of two consecutive phases in distinct spatiotemporal structures: a pair of Cavitons growing and breathing slowly without long range propagation, followed by a sudden decay into many Instantons that carry negative wave energy rapidly into infinity. A spotlight onto the motion of Instantons for a given radial position reproduces a Blob-Hole temporal structure; the occurrence as well as the rapid decay of Caviton into Instantons is triggered by zero-crossing of radial group velocity. A sample of the radial profile of zonal flow contributed from 31 nonlinearly coupled rational surfaces near plasma edge is found to be very similar to that observed in the JET Ohmic phase [J. C. Hillesheim et al., Phys. Rev. Lett. 116, 165002 (2016)]. The theory predicts an interior asymmetric dipole structure associated with the zonal flow that is driven by the gradients of ITG turbulence intensity.

  7. Unique Structural Features of Influenza Virus H15 Hemagglutinin

    Energy Technology Data Exchange (ETDEWEB)

    Tzarum, Netanel; McBride, Ryan; Nycholat, Corwin M.; Peng, Wenjie; Paulson, James C.; Wilson, Ian A. (Scripps)

    2017-04-12

    Influenza A H15 viruses are members of a subgroup (H7-H10-H15) of group 2 hemagglutinin (HA) subtypes that include H7N9 and H10N8 viruses that were isolated from humans during 2013. The isolation of avian H15 viruses is, however, quite rare and, until recently, geographically restricted to wild shorebirds and waterfowl in Australia. The HAs of H15 viruses contain an insertion in the 150-loop (loop beginning at position 150) of the receptor-binding site common to this subgroup and a unique insertion in the 260-loop compared to any other subtype. Here, we show that the H15 HA has a high preference for avian receptor analogs by glycan array analyses. The H15 HA crystal structure reveals that it is structurally closest to H7N9 HA, but the head domain of the H15 trimer is wider than all other HAs due to a tilt and opening of the HA1 subunits of the head domain. The extended 150-loop of the H15 HA retains the conserved conformation as in H7 and H10 HAs. Furthermore, the elongated 260-loop increases the exposed HA surface and can contribute to antigenic variation in H15 HAs. Since avian-origin H15 HA viruses have been shown to cause enhanced disease in mammalian models, further characterization and immune surveillance of H15 viruses are warranted.

    IMPORTANCEIn the last 2 decades, an apparent increase has been reported for cases of human infection by emerging avian influenza A virus subtypes, including H7N9 and H10N8 viruses isolated during 2013. H15 is the other member of the subgroup of influenza A virus group 2 hemagglutinins (HAs) that also include H7 and H10. H15 viruses have been restricted to Australia, but recent isolation of H15 viruses in western Siberia suggests that they could be spread more globally via the avian flyways that converge and emanate from this region. Here we report on characterization of the three-dimensional structure and receptor specificity of the H15 hemagglutinin, revealing distinct features and specificities that can

  8. Fine Structure of the Core of the Blazar OJ 287-I

    Science.gov (United States)

    Matveyenko, L. I.; Sivakon', S. S.

    2017-12-01

    The fine structure of the active region, the bulge, of the blazar OJ 287 has been investigated with a resolution of 20 μas (0.1 pc) at a wavelength of 7 mm, the epochs of 2007-2017. The structure and kinematics correspond to a vortex nature. The surrounding matter, the plasma, is transferred to the center along two arms from opposite directions. The emerging excess angular momentum is carried away along the rotation axis by bipolar outflows, rotating coaxial tubes, in a direction X ≈ -120° in the plane of the sky as it is accumulated. The central high-velocity bipolar outflow has a helical shape. The diameters of the low-velocity flows are ø1 ≈ 0.3 and ø2 ≈ 0.65 mas, or 1.4 and 3 pc, respectively. Ring currents whose tangential directions are observed as parallel chains of components are excited in the flow walls. The peak brightness temperature of the nozzle reaches Tb ≈ 1012-1013 K. A "disk" with a diameter ø ≈ 0.5 mas (≈2.2 pc) is observed by the absorption of synchrotron radiation. The disk is inclined to the plane of the sky at an angle of 60° in the jet direction. The fragments are seen from a distance of ˜0.2 mas outside the absorption zone. The jet sizes exceed considerably the counterjet ones. An enhanced supply of plasma from the northern arm gives rise to an independent vortex 0.2 mas away from the central one in the NW direction. As in the first case, the helical central bipolar outflow is surrounded by a low-velocity component ø ≈ 0.28 mas in diameter with built-in ring currents. The jet is ejected in the direction X = -50° in the plane of the sky. The jet orientation changes, X = -130° at a distance of 1 mas. A high activity of the central and two side nozzles spaced 0.22 mas apart in the direction X = -40° is occasionally observed simultaneously. The active region of the blazar is observed through an ionized medium, a screen, whose influence is significant even at a wavelength of 7 mm. The absorption and refraction of the

  9. Metre-wavelength fine structure in 30 extragalactic radio sources with sizes of a few arcsec

    International Nuclear Information System (INIS)

    Banhatti, D.G.; Ananthakrishnan, S.; Pramesh Rao, A.

    1983-01-01

    Interplanetary scintillation (IPS) observations at 327 MHz of an unbiased sample of 30 extragalactic radio sources having overall sizes between 1 and 4 arcsec, and flux densities greater than 1 Jy at 327 MHz are reported. From VLBI observations, these sources have been reported to contain compact components of sizes < approx.= to 0.02 arcsec contributing on an average about 25 per cent of the total emission at 5 HGz. The IPS observations show that about 45 per cent of the total emission at 327 MHz arises from structures of sizes between 0.05 and 0.5 arcsec (corresponding typically to 0.5 to 5 kpc). A comparison of the VLBI and IPS results indicates that the VLBI and IPS components probably refer to the same physical features in these sources. (author)

  10. Random dynamics and relations between the number of fermion generations and the fine structure

    International Nuclear Information System (INIS)

    Nielsen, H.B.

    1989-01-01

    By looking at the structure and crude features of the parameters of the Standard Model we argue for some properties of physics at a more fundamental level, presumably the Planck energy scale. These properties suggest a picture of 'anti-grand-unification' in the sense that, contrary to usual grand unification, we do not expect a simple gauge group at the high energy level. Rather we expect to see a gauge algebra which is a cross product of several simple or abelian factors. A symmetry breaking mechanism called confusion may then break each set of isomorphic factors down to the diagonal subgroup, thereby explaining the fact that non of the direct product factors in the Standard Model are repeated. (orig.)

  11. Diagnostic Benefit of Thyroglobulin Measurement in Fine-Needle Aspiration for Diagnosing Metastatic Cervical Lymph Nodes from Papillary Thyroid Cancer: Correlations with US Features

    International Nuclear Information System (INIS)

    Jeon, Se Jeong; Kim, Eun Hee; Son, Kyu Ri; Park, Do Joon; Cho, Bo Youn; Na, Dong Gyu; Park, Jeong Seon; Baek, Jung Hwan; Kim, Yoon Suk

    2009-01-01

    Our goals were to determine the added value of fine-needle aspiration biopsy (FNAB)-thyroglobulin (Tg) measurements over FNAB-cytology alone for diagnosing metastatic nodes, and to determine whether the ultrasound features of lymph nodes can be used to identify lymph nodes that may benefit from FNAB-Tg measurement in patients with papillary thyroid cancer. We retrospectively evaluated 76 surgically proven cervical lymph nodes. Twenty-nine patients were awaiting surgery and 18 patients had undergone thyroid surgery for papillary thyroid cancer. Ultrasound-guided FNAB and Tg measurements were performed and the ultrasound features were evaluated. The accuracies, sensitivities, and specificities of FNAB-cytology, FNAB-Tg, and combined FNAB-Tg/cytology were 90%, 80%, and 100%; 92%, 95%, and 90%; and 93%, 96%, and 90%, respectively. The diagnostic sensitivity of FNAB-Tg for metastatic nodes was significantly higher than that of FNAB-cytology (p = 0.011). Furthermore, combined FNAB-Tg/cytology significantly increased sensitivity (p = 0.002) and accuracy (p = 0.03) as compared with FNAB-cytology. Combined FNAB-Tg/cytology is significantly more sensitive and accurate at detecting metastatic nodes than FNAB-cytology alone. FNAB-Tg was better at diagnosing metastases in small lymph nodes

  12. A search for fine structure of the time-of-flight spectrum of the fission neutrons of 252Cf

    International Nuclear Information System (INIS)

    Scobie, J.; Scott, R.D.; Feather, N.; Vass, D.G.

    1977-01-01

    A standard time-of-flight arrangement, in which start pulses were supplied by fission fragments and stop pulses by neutrons, has been employed in an attempt to check recent claims of the existence of fine structures in the time-of-flight spectrum of the fission neutrons of 252 Cf. This structure, in the form of spikes with tails towards longer times, has been attributed to the emission of neutrons of short delay (with half-lives of a few to a hundred or so nanoseconds) in the fission process. It has not been possible to find any convincing evidence for the existence of such structure. (author)

  13. Band-Edge Exciton Fine Structure and Recombination Dynamics in InP/ZnS Colloidal Nanocrystals.

    Science.gov (United States)

    Biadala, Louis; Siebers, Benjamin; Beyazit, Yasin; Tessier, Mickaël D; Dupont, Dorian; Hens, Zeger; Yakovlev, Dmitri R; Bayer, Manfred

    2016-03-22

    We report on a temperature-, time-, and spectrally resolved study of the photoluminescence of type-I InP/ZnS colloidal nanocrystals with varying core size. By studying the exciton recombination dynamics we assess the exciton fine structure in these systems. In addition to the typical bright-dark doublet, the photoluminescence stems from an upper bright state in spite of its large energy splitting (∼100 meV). This striking observation results from dramatically lengthened thermalization processes among the fine structure levels and points to optical-phonon bottleneck effects in InP/ZnS nanocrystals. Furthermore, our data show that the radiative recombination of the dark exciton scales linearly with the bright-dark energy splitting for CdSe and InP nanocrystals. This finding strongly suggests a universal dangling bonds-assisted recombination of the dark exciton in colloidal nanostructures.

  14. The Charge-Mass-Spin Relation of Clifford Polyparticles, Kerr-Newman Black Holes and the Fine Structure Constant

    CERN Document Server

    Castro, C

    2003-01-01

    A Clifford-algebraic interpretation is proposed of the charge, mass, spin relationship found recently by Cooperstock and Faraoini which was based on the Kerr-Newman metric solutions of the Einstein-Maxwell equations. The components of the polymomentum associated with a Clifford polyparticle in four dimensions provide for such a charge, mass, spin relationship without the problems encountered in Kaluza-Klein compactifications which furnish an unphysically large value for the electron charge. A physical reasoning behind such charge, mass, spin relationship is provided, followed by a discussion on the geometrical derivation of the fine structure constant by Wyler, Smith, Gonzalez-Martin and Smilga. To finalize, the renormalization of electric charge is discussed and some remarks are made pertaining the modifications of the charge-scale relationship, when the spin of the polyparticle changes with scale, that may cast some light into the alleged Astrophysical variations of the fine structure constant.

  15. The fine structure of human germ layers in vivo: clues to the early differentiation of embryonic stem cells in vitro.

    Science.gov (United States)

    Sathananthan, Henry; Selvaraj, Kamala; Clark, Joan

    2011-08-01

    The fine structure of the three germ layers in human ectopic embryos (stage 7) have been documented by digital light and electron microscopy. The formation of ectoderm, endoderm and mesoderm and notochordal cells, and also the extraembryonic membranes, amnion and yolk sac, are imaged. The germ layers give rise to all the cells and tissues of the human body. Possible clues to the early differentiation of embryonic stem cells (ESC) in vitro were obtained, since these events are more or less mimicked in cultures of ESC derived from the inner cell mass of human blastocysts. The findings are discussed with reference to previous studies on the fine structure of ESC using the same technique. Copyright © 2011. Published by Elsevier Ltd.

  16. Diffraction anomalous fine-structure study of strained Ga1-xInxAs on GaAs(001)

    International Nuclear Information System (INIS)

    Woicik, J.C.; Cross, J.O.; Bouldin, C.E.; Ravel, B.; Pellegrino, J.G.; Steiner, B.; Bompadre, S.G.; Sorensen, L.B.; Miyano, K.E.; Kirkland, J.P.

    1998-01-01

    Diffraction anomalous fine-structure measurements performed at both the Ga and As K edges have determined the Ga-As bond length to be 2.442±0.005thinsp Angstrom in a buried, 213-Angstrom-thick Ga 0.785 In 0.215 As layer grown coherently on GaAs(001). This bond length corresponds to a strain-induced contraction of 0.013±0.005thinsp Angstrom relative to the Ga-As bond length in bulk Ga 1-x In x As of the same composition. Together with recent extended x-ray-absorption fine-structure measurements performed at the In K edge [Woicik et al., Phys. Rev. Lett. 79, 5026 (1997)], excellent agreement is found with the uniform bond-length distortion model for strained-layer semiconductors on (001) substrates. copyright 1998 The American Physical Society

  17. Demonstrating the Uneven Importance of Fine-Scale Forest Structure on Snow Distributions using High Resolution Modeling

    Science.gov (United States)

    Broxton, P. D.; Harpold, A. A.; van Leeuwen, W.; Biederman, J. A.

    2016-12-01

    Quantifying the amount of snow in forested mountainous environments, as well as how it may change due to warming and forest disturbance, is critical given its importance for water supply and ecosystem health. Forest canopies affect snow accumulation and ablation in ways that are difficult to observe and model. Furthermore, fine-scale forest structure can accentuate or diminish the effects of forest-snow interactions. Despite decades of research demonstrating the importance of fine-scale forest structure (e.g. canopy edges and gaps) on snow, we still lack a comprehensive understanding of where and when forest structure has the largest impact on snowpack mass and energy budgets. Here, we use a hyper-resolution (1 meter spatial resolution) mass and energy balance snow model called the Snow Physics and Laser Mapping (SnowPALM) model along with LIDAR-derived forest structure to determine where spatial variability of fine-scale forest structure has the largest influence on large scale mass and energy budgets. SnowPALM was set up and calibrated at sites representing diverse climates in New Mexico, Arizona, and California. Then, we compared simulations at different model resolutions (i.e. 1, 10, and 100 m) to elucidate the effects of including versus not including information about fine scale canopy structure. These experiments were repeated for different prescribed topographies (i.e. flat, 30% slope north, and south-facing) at each site. Higher resolution simulations had more snow at lower canopy cover, with the opposite being true at high canopy cover. Furthermore, there is considerable scatter, indicating that different canopy arrangements can lead to different amounts of snow, even when the overall canopy coverage is the same. This modeling is contributing to the development of a high resolution machine learning algorithm called the Snow Water Artificial Network (SWANN) model to generate predictions of snow distributions over much larger domains, which has implications

  18. The impact of mating systems and dispersal on fine-scale genetic structure at maternally, paternally and biparentally inherited markers.

    Science.gov (United States)

    Shaw, Robyn E; Banks, Sam C; Peakall, Rod

    2018-01-01

    For decades, studies have focused on how dispersal and mating systems influence genetic structure across populations or social groups. However, we still lack a thorough understanding of how these processes and their interaction shape spatial genetic patterns over a finer scale (tens-hundreds of metres). Using uniparentally inherited markers may help answer these questions, yet their potential has not been fully explored. Here, we use individual-level simulations to investigate the effects of dispersal and mating system on fine-scale genetic structure at autosomal, mitochondrial and Y chromosome markers. Using genetic spatial autocorrelation analysis, we found that dispersal was the major driver of fine-scale genetic structure across maternally, paternally and biparentally inherited markers. However, when dispersal was restricted (mean distance = 100 m), variation in mating behaviour created strong differences in the comparative level of structure detected at maternally and paternally inherited markers. Promiscuity reduced spatial genetic structure at Y chromosome loci (relative to monogamy), whereas structure increased under polygyny. In contrast, mitochondrial and autosomal markers were robust to differences in the specific mating system, although genetic structure increased across all markers when reproductive success was skewed towards fewer individuals. Comparing males and females at Y chromosome vs. mitochondrial markers, respectively, revealed that some mating systems can generate similar patterns to those expected under sex-biased dispersal. This demonstrates the need for caution when inferring ecological and behavioural processes from genetic results. Comparing patterns between the sexes, across a range of marker types, may help us tease apart the processes shaping fine-scale genetic structure. © 2017 John Wiley & Sons Ltd.

  19. R-matrix calculations for electron-impact excitation of C(+), N(2+), and O(3+) including fine structure

    Science.gov (United States)

    Luo, D.; Pradhan, A. K.

    1990-01-01

    The new R-matrix package for comprehensive close-coupling calculations for electron scattering with the first three ions in the boron isoelectronic sequence, the astrophysically significant C(+), N(2+), and O(3+), is presented. The collision strengths are calculated in the LS coupling approximation, as well as in pair-coupling scheme, for the transitions among the fine-structure sublevels. Calculations are carried out at a large number of energies in order to study the detailed effects of autoionizing resonances.

  20. Changes in fine structure of pericytes and novel desmin-immunopositive perivascular cells during postnatal development in rat anterior pituitary gland.

    Science.gov (United States)

    Jindatip, Depicha; Fujiwara, Ken; Horiguchi, Kotaro; Tsukada, Takehiro; Kouki, Tom; Yashiro, Takashi

    2013-09-01

    Pericytes are perivascular cells associated with capillaries. We previously demonstrated that pericytes, identified by desmin immunohistochemistry, produce type I and III collagens in the anterior pituitary gland of adult rats. In addition, we recently used desmin immunoelectron microscopy to characterize a novel type of perivascular cell, dubbed a desmin-immunopositive perivascular cell, in the anterior pituitary. These two types of perivascular cells differ in fine structure. The present study attempted to characterize the morphological features of pituitary pericytes and novel desmin-immunopositive perivascular cells during postnatal development, in particular their role in collagen synthesis. Desmin immunostaining revealed numerous perivascular cells at postnatal day 5 (P5) and P10. Transmission electron microscopy showed differences in the fine structure of the two cell types, starting at P5. Pericytes had well-developed rough endoplasmic reticulum and Golgi apparatus at P5 and P10. The novel desmin-immunopositive perivascular cells exhibited dilated cisternae of rough endoplasmic reticulum at P5-P30. In addition, during early postnatal development in the gland, a number of type I and III collagen-expressing cells were observed, as were high expression levels of these collagen mRNAs. We conclude that pituitary pericytes and novel desmin-immunopositive perivascular cells contain well-developed cell organelles and that they actively synthesize collagens during the early postnatal period.

  1. A correlational method to concurrently measure envelope and temporal fine structure weights: effects of age, cochlear pathology, and spectral shaping.

    Science.gov (United States)

    Fogerty, Daniel; Humes, Larry E

    2012-09-01

    The speech signal may be divided into spectral frequency-bands, each band containing temporal properties of the envelope and fine structure. This study measured the perceptual weights for the envelope and fine structure in each of three frequency bands for sentence materials in young normal-hearing listeners, older normal-hearing listeners, aided older hearing-impaired listeners, and spectrally matched young normal-hearing listeners. The availability of each acoustic property was independently varied through noisy signal extraction. Thus, the full speech stimulus was presented with noise used to mask six different auditory channels. Perceptual weights were determined by correlating a listener's performance with the signal-to-noise ratio of each acoustic property on a trial-by-trial basis. Results demonstrate that temporal fine structure perceptual weights remain stable across the four listener groups. However, a different weighting typography was observed across the listener groups for envelope cues. Results suggest that spectral shaping used to preserve the audibility of the speech stimulus may alter the allocation of perceptual resources. The relative perceptual weighting of envelope cues may also change with age. Concurrent testing of sentences repeated once on a previous day demonstrated that weighting strategies for all listener groups can change, suggesting an initial stabilization period or susceptibility to auditory training.

  2. On the origin of fine structure in the photoluminescence spectra of the β-sialon:Eu2+ green phosphor

    Directory of Open Access Journals (Sweden)

    Kohsei Takahashi, Ken-ichi Yoshimura, Masamichi Harada, Yoshitaka Tomomura, Takashi Takeda, Rong-Jun Xie and Naoto Hirosaki

    2012-01-01

    Full Text Available The photoluminescence (PL and PL excitation (PLE spectra of Si6−zAlzOzN8−z (β-sialon:Eu2+ phosphors with small z values (z=0.025–0.24 were studied at room temperature and 6 K. The PL and PLE spectra exhibit fine structure with the PL lines being as sharp as 45–55 nm even at room temperature; this fine structure was enhanced by decreasing the z value. These results can be used for expanding the color gamut of liquid crystal displays, particularly in the blue–green region. From low-temperature measurements, the fine PLE structure was ascribed to discrete energy levels of 7FJ states. The 4f65d excited states of Eu2+ are considered to be localized near the 4f orbital. This is because the bonding of Eu2+ with surrounding atoms is ionic rather than covalent. Lattice phonon absorptions were also observed in the PLE spectrum, revealing that the optically active Eu2+ ions are located in the β-sialon crystal. The PL spectrum of the sample with the smallest z value (0.025 consists of a sharp zero-phonon line and lattice phonon replicas, which results in a sharp and asymmetric spectral shape.

  3. Fine-scale population genetic structure of arctic foxes (Vulpes lagopus) in the High Arctic.

    Science.gov (United States)

    Lai, Sandra; Quiles, Adrien; Lambourdière, Josie; Berteaux, Dominique; Lalis, Aude

    2017-12-01

    The arctic fox (Vulpes lagopus) is a circumpolar species inhabiting all accessible Arctic tundra habitats. The species forms a panmictic population over areas connected by sea ice, but recently, kin clustering and population differentiation were detected even in regions where sea ice was present. The purpose of this study was to examine the genetic structure of a population in the High Arctic using a robust panel of highly polymorphic microsatellites. We analyzed the genotypes of 210 individuals from Bylot Island, Nunavut, Canada, using 15 microsatellite loci. No pattern of isolation-by-distance was detected, but a spatial principal component analysis (sPCA) revealed the presence of genetic subdivisions. Overall, the sPCA revealed two spatially distinct genetic clusters corresponding to the northern and southern parts of the study area, plus another subdivision within each of these two clusters. The north-south genetic differentiation partly matched the distribution of a snow goose colony, which could reflect a preference for settling into familiar ecological environments. Secondary clusters may result from higher-order social structures (neighbourhoods) that use landscape features to delimit their borders. The cryptic genetic subdivisions found in our population may highlight ecological processes deserving further investigations in arctic foxes at larger, regional spatial scales.

  4. Fine structure of the vaccinia virion determined by controlled degradation and immunolocalization

    International Nuclear Information System (INIS)

    Moussatche, Nissin; Condit, Richard C.

    2015-01-01

    The vaccinia virion is a membraned, slightly flattened, barrel-shaped particle, with a complex internal structure featuring a biconcave core flanked by lateral bodies. Although the architecture of the purified mature virion has been intensely characterized by electron microscopy, the distribution of the proteins within the virion has been examined primarily using biochemical procedures. Thus, it has been shown that non-ionic and ionic detergents combined or not with a sulfhydryl reagent can be used to disrupt virions and, to a limited degree, separate the constituent proteins in different fractions. Applying a controlled degradation technique to virions adsorbed on EM grids, we were able to immuno-localize viral proteins within the virion particle. Our results show after NP40 and DTT treatment, membrane proteins are removed from the virion surface revealing proteins that are associated with the lateral bodies and the outer layer of the core wall. Combined treatment using high salt and high DTT removed lateral body proteins and exposed proteins of the internal core wall. Cores treated with proteases could be disrupted and the internal components were exposed. Cts8, a mutant in the A3 protein, produces aberrant virus that, when treated with NP-40 and DTT, releases to the exterior the virus DNA associated with other internal core proteins. With these results, we are able to propose a model for the structure the vaccinia virion

  5. Fine-scale structure of the mid-mantle characterised by global stacks of PP precursors

    Science.gov (United States)

    Bentham, H. L. M.; Rost, S.; Thorne, M. S.

    2017-08-01

    Subduction zones are likely a major source of compositional heterogeneities in the mantle, which may preserve a record of the subduction history and mantle convection processes. The fine-scale structure associated with mantle heterogeneities can be studied using the scattered seismic wavefield that arrives as coda to or as energy preceding many body wave arrivals. In this study we analyse precursors to PP by creating stacks recorded at globally distributed stations. We create stacks aligned on the PP arrival in 5° distance bins (with range 70-120°) from 600 earthquakes recorded at 193 stations stacking a total of 7320 seismic records. As the energy trailing the direct P arrival, the P coda, interferes with the PP precursors, we suppress the P coda by subtracting a best fitting exponential curve to this energy. The resultant stacks show that PP precursors related to scattering from heterogeneities in the mantle are present for all distances. Lateral variations are explored by producing two regional stacks across the Atlantic and Pacific hemispheres, but we find only negligible differences in the precursory signature between these two regions. The similarity of these two regions suggests that well mixed subducted material can survive at upper and mid-mantle depth. To describe the scattered wavefield in the mantle, we compare the global stacks to synthetic seismograms generated using a Monte Carlo phonon scattering technique. We propose a best-fitting layered heterogeneity model, BRT2017, characterised by a three layer mantle with a background heterogeneity strength (ɛ = 0.8%) and a depth-interval of increased heterogeneity strength (ɛ = 1%) between 1000 km and 1800 km. The scalelength of heterogeneity is found to be 8 km throughout the mantle. Since mantle heterogeneity of 8 km scale may be linked to subducted oceanic crust, the detection of increased heterogeneity at mid-mantle depths could be associated with stalled slabs due to increases in viscosity

  6. Degree of contribution (DoC) feature selection algorithm for structural brain MRI volumetric features in depression detection.

    Science.gov (United States)

    Kipli, Kuryati; Kouzani, Abbas Z

    2015-07-01

    Accurate detection of depression at an individual level using structural magnetic resonance imaging (sMRI) remains a challenge. Brain volumetric changes at a structural level appear to have importance in depression biomarkers studies. An automated algorithm is developed to select brain sMRI volumetric features for the detection of depression. A feature selection (FS) algorithm called degree of contribution (DoC) is developed for selection of sMRI volumetric features. This algorithm uses an ensemble approach to determine the degree of contribution in detection of major depressive disorder. The DoC is the score of feature importance used for feature ranking. The algorithm involves four stages: feature ranking, subset generation, subset evaluation, and DoC analysis. The performance of DoC is evaluated on the Duke University Multi-site Imaging Research in the Analysis of Depression sMRI dataset. The dataset consists of 115 brain sMRI scans of 88 healthy controls and 27 depressed subjects. Forty-four sMRI volumetric features are used in the evaluation. The DoC score of forty-four features was determined as the accuracy threshold (Acc_Thresh) was varied. The DoC performance was compared with that of four existing FS algorithms. At all defined Acc_Threshs, DoC outperformed the four examined FS algorithms for the average classification score and the maximum classification score. DoC has a good ability to generate reduced-size subsets of important features that could yield high classification accuracy. Based on the DoC score, the most discriminant volumetric features are those from the left-brain region.

  7. Feral pig populations are structured at fine spatial scales in tropical Queensland, Australia.

    Science.gov (United States)

    Lopez, Jobina; Hurwood, David; Dryden, Bart; Fuller, Susan

    2014-01-01

    Feral pigs occur throughout tropical far north Queensland, Australia and are a significant threat to biodiversity and World Heritage values, agriculture and are a vector of infectious diseases. One of the constraints on long-lasting, local eradication of feral pigs is the process of reinvasion into recently controlled areas. This study examined the population genetic structure of feral pigs in far north Queensland to identify the extent of movement and the scale at which demographically independent management units exist. Genetic analysis of 328 feral pigs from the Innisfail to Tully region of tropical Queensland was undertaken. Seven microsatellite loci were screened and Bayesian clustering methods used to infer population clusters. Sequence variation at the mitochondrial DNA control region was examined to identify pig breed. Significant population structure was identified in the study area at a scale of 25 to 35 km, corresponding to three demographically independent management units (MUs). Distinct natural or anthropogenic barriers were not found, but environmental features such as topography and land use appear to influence patterns of gene flow. Despite the strong, overall pattern of structure, some feral pigs clearly exhibited ancestry from a MU outside of that from which they were sampled indicating isolated long distance dispersal or translocation events. Furthermore, our results suggest that gene flow is restricted among pigs of domestic Asian and European origin and non-random mating influences management unit boundaries. We conclude that the three MUs identified in this study should be considered as operational units for feral pig control in far north Queensland. Within a MU, coordinated and simultaneous control is required across farms, rainforest areas and National Park Estates to prevent recolonisation from adjacent localities.

  8. Effect of processing on structural features of anodic aluminum oxides

    Science.gov (United States)

    Erdogan, Pembe; Birol, Yucel

    2012-09-01

    Morphological features of the anodic aluminum oxide (AAO) templates fabricated by electrochemical oxidation under different processing conditions were investigated. The selection of the polishing parameters does not appear to be critical as long as the aluminum substrate is polished adequately prior to the anodization process. AAO layers with a highly ordered pore distribution are obtained after anodizing in 0.6 M oxalic acid at 20 °C under 40 V for 5 minutes suggesting that the desired pore features are attained once an oxide layer develops on the surface. While the pore features are not affected much, the thickness of the AAO template increases with increasing anodization treatment time. Pore features are better and the AAO growth rate is higher at 20 °C than at 5 °C; higher under 45 V than under 40 V; higher with 0.6 M than with 0.3 M oxalic acid.

  9. Grazing incidence x-ray diffraction at free-standing nanoscale islands: fine structure of diffuse scattering

    International Nuclear Information System (INIS)

    Grigoriev, D; Hanke, M; Schmidbauer, M; Schaefer, P; Konovalov, O; Koehler, R

    2003-01-01

    We have investigated the x-ray intensity distribution around 220 reciprocal lattice point in case of grazing incidence diffraction at SiGe nanoscale free-standing islands grown on Si(001) substrate by LPE. Experiments and computer simulations based on the distorted wave Born approximation utilizing the results of elasticity theory obtained by FEM modelling have been carried out. The data reveal fine structure in the distribution of scattered radiation with well-pronounced maxima and complicated fringe pattern. Explanation of the observed diffraction phenomena in their relation to structure and morphology of the island is given. An optimal island model including its shape, size and Ge spatial distribution was elaborated

  10. The Fine Transverse Structure of a Vortex Flow Beyond the Edge of a Disc Rotating in a Stratified Fluid

    Science.gov (United States)

    Chashechkin, Yu. D.; Bardakov, R. N.

    2018-02-01

    By the methods of schlieren visualization, the evolution of elements of the fine structure of transverse vortex loops formed in the circular vortex behind the edge of a disk rotating in a continuously stratified fluid is traced for the first time. An inhomogeneous distribution of the density of a table-salt solution in a basin was formed by the continuous-squeezing method. The development of periodic perturbations at the outer boundary of the circular vortex and their transformation at the vortex-loop vertex are traced. A slow change in the angular size of the structural elements in the supercritical-flow mode is noted.

  11. FINE MAGNETIC STRUCTURE AND ORIGIN OF COUNTER-STREAMING MASS FLOWS IN A QUIESCENT SOLAR PROMINENCE

    International Nuclear Information System (INIS)

    Shen, Yuandeng; Liu, Yu; Xu, Zhi; Liu, Zhong; Liu, Ying D.; Chen, P. F.; Su, Jiangtao

    2015-01-01

    We present high-resolution observations of a quiescent solar prominence that consists of a vertical and a horizontal foot encircled by an overlying spine and has ubiquitous counter-streaming mass flows. While the horizontal foot and the spine were connected to the solar surface, the vertical foot was suspended above the solar surface and was supported by a semicircular bubble structure. The bubble first collapsed, then reformed at a similar height, and finally started to oscillate for a long time. We find that the collapse and oscillation of the bubble boundary were tightly associated with a flare-like feature located at the bottom of the bubble. Based on the observational results, we propose that the prominence should be composed of an overlying horizontal spine encircling a low-lying horizontal and vertical foot, in which the horizontal foot consists of shorter field lines running partially along the spine and has ends connected to the solar surface, while the vertical foot consists of piling-up dips due to the sagging of the spine fields and is supported by a bipolar magnetic system formed by parasitic polarities (i.e., the bubble). The upflows in the vertical foot were possibly caused by the magnetic reconnection at the separator between the bubble and the overlying dips, which intruded into the persistent downflow field and formed the picture of counter-streaming mass flows. In addition, the counter-streaming flows in the horizontal foot were possibly caused by the imbalanced pressure at the both ends

  12. Relevance of echo-structure and texture features

    DEFF Research Database (Denmark)

    Karemore, Gopal; Mullick, Jhinuk Basu; KV, Dr. Rajagopal

    2010-01-01

    Aim: Echostructure is an essential parameter for the evaluation of circumscribed lesions and can be described as a texture feature on ultrasound images. Present study evaluates the possibility of distinguishing between benign and malignant breast tumors using various texture features. Materials...... and Methods: 58 cases of breast tumor (29 each from benign and malignant) were documented under standardized conditions using a linear array machine and 7.5 MHz transducer. In each sonographic image, ROI of tumor was marked and then subjected to the evaluation of tumor status using five parameters of second...... performance ROC= 0.78(pbenign and malignant tumors. It also reveals that when evaluating images of a breast tumor...

  13. Micromorphological features of the fine earth and skeletal fractions of soils of West Antarctica in the areas of Russian Antarctic stations

    Science.gov (United States)

    Abakumov, E. V.; Gagarina, E. I.; Sapega, V. F.; Vlasov, D. Yu.

    2013-12-01

    Micromorphological features of the fine earth and skeletal fractions of soils of West Antarctica forming under different conditions of pedogenesis have been studied in the areas of Russian Antarctic stations. The processes of mineral weathering and alteration of rock fragments are more pronounced in the Subantarctic soils with better developed humification and immobilization of iron compounds under conditions of surface overmoistening. The biogenic accumulative processes in the soils of King George Island result in the appearance of initial forms of humic plasma that have not been detected in the Antarctic soils in the areas of the Russkaya and Leningradskaya stations. Humus films on mineral grains are present in the soils of King George Island, and organic plasmic material is present in the ornithogenic soils under penguin guano on Lindsey Island. High-latitude Antarctic soils may contain surface concentrations of organic matter; rock fragments are covered by iron oxides and soluble salts. The formation of amorphous organic plasma takes place in the ornithogenic soils of Lindsey Island. The microprobe analysis indicates the presence of local concentrations of organic matter and pedogenic compounds not only on the surface of rock fragments but also in the fissures inside them. This analysis has also proved the translocation of guano-derived organic substances inside rock fragments through a system of fissures in the soils of Lindsey Island and the development of a network of pores inside rock fragments in the soils of King George Island.

  14. Effects of proton irradiation on structure of NdFeB permanent magnets studied by X-ray diffraction and X-ray absorption fine structure

    International Nuclear Information System (INIS)

    Yang, L.; Zhen, L.; Xu, C.Y.; Sun, X.Y.; Shao, W.Z.

    2011-01-01

    The effects of proton irradiation on the structure of NdFeB permanent magnet were investigated by X-ray diffraction and X-ray absorption fine structure (XAFS). The results reveal that proton irradiation has no effect on the long-range structure, but significantly affects the atomic local structure of the NdFeB magnet. The alignment degree of the magnet decreases and the internal stress of the lattice increases after proton irradiation. XAFS results show that the coordination number of Fe-Nd in the first neighboring coordination shell of the Fe atoms decreases and the disorder degree increases.

  15. Effects of proton irradiation on structure of NdFeB permanent magnets studied by X-ray diffraction and X-ray absorption fine structure

    Energy Technology Data Exchange (ETDEWEB)

    Yang, L. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Zhen, L., E-mail: lzhen@hit.edu.c [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Xu, C.Y.; Sun, X.Y.; Shao, W.Z. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2011-01-15

    The effects of proton irradiation on the structure of NdFeB permanent magnet were investigated by X-ray diffraction and X-ray absorption fine structure (XAFS). The results reveal that proton irradiation has no effect on the long-range structure, but significantly affects the atomic local structure of the NdFeB magnet. The alignment degree of the magnet decreases and the internal stress of the lattice increases after proton irradiation. XAFS results show that the coordination number of Fe-Nd in the first neighboring coordination shell of the Fe atoms decreases and the disorder degree increases.

  16. Features for Exploiting Black-Box Optimization Problem Structure

    DEFF Research Database (Denmark)

    Tierney, Kevin; Malitsky, Yuri; Abell, Tinus

    2013-01-01

    landscape of BBO problems and show how an algorithm portfolio approach can exploit these general, problem indepen- dent features and outperform the utilization of any single minimization search strategy. We test our methodology on data from the GECCO Workshop on BBO Benchmarking 2012, which contains 21...

  17. Process Features in Writing: Internal Structure and Incremental Value over Product Features. Research Report. ETS RR-15-27

    Science.gov (United States)

    Zhang, Mo; Deane, Paul

    2015-01-01

    In educational measurement contexts, essays have been evaluated and formative feedback has been given based on the end product. In this study, we used a large sample collected from middle school students in the United States to investigate the factor structure of the writing process features gathered from keystroke logs and the association of that…

  18. Measurement of the 22S1/2-22P3/2 fine structure interval in muonium

    International Nuclear Information System (INIS)

    Kettell, S.H.

    1990-08-01

    The (2 2 S 1/2 - 2 2 P 3/2 ) fine structure transition in muonium has been observed for the first time. The measured value is 9895 -30 +35 MHz. This measurement, when included with the theoretical value for the 2 2 P 1/2 - 2 2 P 3/2 fine structure interval, gives a value for the Lamb shift (2 2 S 1/2 - 2 2 P 1/2 ) independent of previous direct measurements. From the theoretical value for the fine structure interval, 10921.833(3) MHz, the value for the Lamb shift determined from this experiment is 1027 -35 +30 MHz and is in agreement with the prediction of quantum electrodynamics (QED) of 1047.5(3) MHz. Previous experimental values for the Lamb shift (2 2 S 1/2 -2 2 P 1/2 ) in muonium are 1070 -15 + 12 MHz and 1042 -23 +21 MHz. Combining this result with these previous results gives a new experimental value of 1058 -12 +10 for the Lamb shift in muonium. Muonium, the bound state of two structureless leptons (μ + e - ), is an ideal system for testing bound state QED because of the lack of hadronic structure as exists in the hydrogen system. The measurement makes use of the techniques of atomic beam microwave spectroscopy. Muonium atoms (μ + e - ) in the 2S states are produced by the beam-foil technique at the Clinton P. Anderson Meson Physics Facility with a low momentum, sub-surface muon beam. A variable frequency microwave field is applied to drive the atoms from the 2S to the 2P states, with the subsequent observation of the Lyman alpha photon from the decay of the 2P state to the 1S ground state. The frequency is varied from 9.0--11.0 GHz, driving the F = 0 → F = 1, F = 1, F = 1 and F = 1 → F = 2 transitions

  19. Evidentials dizque and que in Spanish : Grammaticalization, parameters and the (fine structure of Comp

    Directory of Open Access Journals (Sweden)

    Violeta Demonte

    2013-01-01

    Full Text Available In this paper we study one type of Spanish que (the equivalent to the complementizer “that” that can be shown to belong into the crosslinguistically restricted list of evidentials. In particular, we will claim that it encodes the (most basic marks of nonfirst- hand or indirect (reported evidence. Our point of departure is certain (apparently independent clauses of Spanish headed by an overt complementizer (que. Some tests will be presented that support the idea that that one type of que introducing a well specified subset of root sentences shares most of the properties that have been claimed to characterize reportative evidentials in languages such as Quechua (Faller 2002, 2006. As for the properties of reportative que, it will be further shown that it does not encode any features related to epistemic modality (reliability or (improbability and we will propose that it is better analyzed as an illocutionary operator, affecting the illocutionary force (in line with Faller 2002 among others and not as an epistemic modal (Izvorsky 1997 among others. In order to determine the nature of this reportative element and its origin, we contrast it with an old Spanish form, dizque, which exists nowadays in certain modern American varieties. This particle also has the properties of an evidential but behaves as an epistemic modal. In the last sections, we will propose that both evidential particles (que and dizque are the result of a process of grammaticalization (i.e. ‘upward reanalysis’, or categorial change, of functional material, in the sense of Roberts and Roussou 2003 of the complex structure headed by a communication verb, dicen que “they say that”. We will tentatively describe such process and introduce a hypothesis as to the nature and role of the parameter involved in the claimed reanalysis

  20. Structural and Molecular Modeling Features of P2X Receptors

    Directory of Open Access Journals (Sweden)

    Luiz Anastacio Alves

    2014-03-01

    Full Text Available Currently, adenosine 5'-triphosphate (ATP is recognized as the extracellular messenger that acts through P2 receptors. P2 receptors are divided into two subtypes: P2Y metabotropic receptors and P2X ionotropic receptors, both of which are found in virtually all mammalian cell types studied. Due to the difficulty in studying membrane protein structures by X-ray crystallography or NMR techniques, there is little information about these structures available in the literature. Two structures of the P2X4 receptor in truncated form have been solved by crystallography. Molecular modeling has proven to be an excellent tool for studying ionotropic receptors. Recently, modeling studies carried out on P2X receptors have advanced our knowledge of the P2X receptor structure-function relationships. This review presents a brief history of ion channel structural studies and shows how modeling approaches can be used to address relevant questions about P2X receptors.

  1. Contrasting effects of landscape features on genetic structure in different geographic regions in the ornate dragon lizard, Ctenophorus ornatus.

    Science.gov (United States)

    Levy, Esther; Tomkins, Joseph L; Lebas, Natasha R; Kennington, W Jason

    2013-08-01

    Habitat fragmentation can have profound effects on the distribution of genetic variation within and between populations. Previously, we showed that in the ornate dragon lizard, Ctenophorus ornatus, lizards residing on outcrops that are separated by cleared agricultural land are significantly more isolated and hold less genetic variation than lizards residing on neighbouring outcrops connected by undisturbed native vegetation. Here, we extend the fine-scale study to examine the pattern of genetic variation and population structure across the species' range. Using a landscape genetics approach, we test whether land clearing for agricultural purposes has affected the population structure of the ornate dragon lizard. We found significant genetic differentiation between outcrop populations (FST  = 0.12), as well as isolation by distance within each geographic region. In support of our previous study, land clearing was associated with higher genetic divergences between outcrops and lower genetic variation within outcrops, but only in the region that had been exposed to intense agriculture for the longest period of time. No other landscape features influenced population structure in any geographic region. These results show that the effects of landscape features can vary across species' ranges and suggest there may be a temporal lag in response to contemporary changes in land use. These findings therefore highlight the need for caution when assessing the impact of contemporary land use practices on genetic variation and population structure. © 2013 John Wiley & Sons Ltd.

  2. Probing the KII 3p54p fine structure by photoelectron spectroscopy of laser-excited potassium

    International Nuclear Information System (INIS)

    Meyer, M; Cubaynes, D; Wuilleumier, F J; Heinecke, E; Richter, T; Zimmermann, P; Strakhova, S I; Grum-Grzhimailo, A N

    2006-01-01

    Photoelectron spectra of atomic potassium excited by laser optical pumping into the 3p 6 4p 2 P 1/2 and 2 P 3/2 states are measured with high-energy resolution. The relative intensities of the 3p 5 4p fine-structure lines depend strongly on the initial excitation to one of the 4p spin-orbit components. Similar to the case of sodium, dynamically and quasiforbidden transitions are observed in the photoelectron spectra of potassium. The theoretical predictions of the generalized geometrical model are in excellent agreement with the experimental data. (letter to the editor)

  3. Emission of exotic clusters by nuclei and discovery of a fine structure in the 14C decay of 223Ra

    International Nuclear Information System (INIS)

    Vergnes, M.

    1992-01-01

    This paper is intended as a broad, mainly experimental, survey of the recent field of exotic cluster radioactivity in heavy nuclei. The first part summarizes the development of the field since the first experimental finding in 1984, insisting on 14 C emission, and giving a schematic status of the corresponding models. The second part describes in detail the 1989 discovery, in Orsay, of a fine structure of the 14 C decay of 223 Ra and the search for a similar effect in even-even neighboring nuclei 222 Ra and 224 Ra. A possible qualitative interpretation of the 'hindrance' of the transition to the ground state of 209 Pb is proposed

  4. A cell for extended x-ray absorption fine structure studies of oxygen sensitive products of redox reactions

    International Nuclear Information System (INIS)

    Furenlid, L.R.; Renner, M.W.; Fajer, J.

    1990-01-01

    We describe a cell suitable for extended x-ray absorption fine structure (EXAFS) studies of oxygen and/or water sensitive products of redox reactions. The cell utilizes aluminized Mylar windows that are transparent to x rays, provide low gas permeability, and allow vacuum to be maintained in the cell. The windows are attached to the glassware with an epoxy that resists attack by common organic solvents. Additional side arms allow multiple spectroscopic probes of the same sample under anaerobic and anhydrous conditions

  5. New Equations for Calculating Principal and Fine-Structure Atomic Spectra for Single and Multi-Electron Atoms

    Energy Technology Data Exchange (ETDEWEB)

    Surdoval, Wayne A. [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Berry, David A. [National Energy Technology Lab. (NETL), Morgantown, WV (United States); Shultz, Travis R. [National Energy Technology Lab. (NETL), Morgantown, WV (United States)

    2018-03-09

    A set of equations are presented for calculating atomic principal spectral lines and fine-structure energy splits for single and multi-electron atoms. Calculated results are presented and compared to the National Institute of Science and Technology database demonstrating very good accuracy. The equations do not require fitted parameters. The only experimental parameter required is the Ionization energy for the electron of interest. The equations have comparable accuracy and broader applicability than the single electron Dirac equation. Three Appendices discuss the origin of the new equations and present calculated results. New insights into the special relativistic nature of the Dirac equation and its relationship to the new equations are presented.

  6. Fine structure of the epidermal Leydig cells in the axolotl Ambystoma mexicanum in relation to their function.

    Science.gov (United States)

    Jarial, M S

    1989-01-01

    The fine structure of the Leydig cells in the epidermis of the strictly aquatic adult axolotl Ambystoma mexicanum resembles that of similar cells in larval salamanders. The major finding of this study is that the mucous secretion of the Leydig cells is released into the intercellular spaces from which it is discharged through pores onto the surface of the epidermis where it forms a mucous layer to protect the skin. Images Figs. 1-2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 10 Figs. 11-13 PMID:2630544

  7. The standard model and the fine structure constant at Planck distances in Bennet-Brene-Nielsen-Picek random dynamics

    International Nuclear Information System (INIS)

    Laperashvili, L.V.

    1994-01-01

    An overview of papers by Nielson, Bennet, Brene, and Picek, forming the basis of the model called random dynamics, is given in the first part of this work. The fine structure constant is calculated in the second part of this work by using the technique of path integration in the U(1) lattice gauge theory. It is shown that α U(1),crit -1 ∼ 19.8. This value is in agreement with the prediction of random dynamics. The obtained results are compared with the results of Monte Carlo simulations. 20 refs., 3 figs., 1 tab

  8. Emission of exotic clusters by nuclei and discovery of a fine structure in the 14C decay of 223Ra

    International Nuclear Information System (INIS)

    Vergnes, M.

    1992-01-01

    This paper is intended as a broad, mainly experimental, survey of the recent field of exotic cluster radioactivity in heavy nuclei. The first part summarizes the development of the field since the first experimental finding in 1984, insisting on 14 C emission, and giving a schematic status of the corresponding models. The second part describes in detail the 1989 discovery, in Orsay, of a fine structure of the 14 C decay of 223 Ra and the search for a similar effect in even-even neighboring nuclei 222 Ra and 224 Ra. A possible qualitative interpretation of the ''hindrance'' of the transition to the ground state of 209 Pb is proposed

  9. Characterization of self-organized InGaN/GaN quantum dots by Diffraction Anomalous Fine Structure (DAFS)

    International Nuclear Information System (INIS)

    Piskorska, E.; Holy, V.; Siebert, M.; Schmidt, Th.; Falta, J.; Yamaguchi, T.; Hommel, D.; Renevier, H.

    2006-01-01

    The local chemical composition of InGaN quantum dots grown by a MBE method on GaN virtual substrates was investigated by x-ray diffraction anomalous fine-structure method. From the detailed numerical analysis of the data we were able to reconstruct the local neighborhood of Ga atoms at different positions in the dots. Using this approach, we found that the In content increases from 20% at the dot base to 40-50% at the top. (author) [pl

  10. Apparent wavelength shifts of H-like ions caused by the spectral fine structure observed in CHS plasmas

    International Nuclear Information System (INIS)

    Nishimura, Shin; Ida, Katsumi

    1998-01-01

    A new charge exchange spectroscopy (CXS) system viewing the plasma from the upside and the downside simultaneously was installed on the Compact Helical System (CHS) to detect the absolute value of Doppler shift due to poloidal rotation velocity ( i ∼ 100 eV) and in the after-glow recombining phase (T i ∼ 30 eV). The apparent Doppler shift is always red-shift regardless the direction of plasma rotation and is explained as the effect of the spectral fine structure of hydrogen-like ions. (author)

  11. [Correlation of fine structures of distributions of amplitudes of a photomultiplier dark current fluctuations with the Earth rotations about its axis].

    Science.gov (United States)

    Fedorov, M V; Belousov, L V; Voeĭkov, V L; Zenchenko, K I; Zenchenko, T A; Konradov, A A; Shnol', S E

    2001-01-01

    The fine structures of distributions of photomultiplier dark current fluctuations measured in two laboratories 2000 km distant from other: in the international Institute of Biophysics (Neuss, Germany) and in the Moscow State University (Moscow, Russia) were compared. It is shown that similar forms of appropriate histograms are apparently more often realized at both locations at the same local time. This confirms the previous conclusion that the fine structure of distributions correlates with rotation of the Earth about its axis.

  12. Structural study on Ni nanowires in an anodic alumina membrane by using in situ heating extended x-ray absorption fine structure and x-ray diffraction techniques

    International Nuclear Information System (INIS)

    Cai Quan; Chen Xing; Chen Zhongjun; Wang Wei; Mo Guang; Wu Zhonghua; Zhang Junxi; Zhang Lide; Pan Wei

    2008-01-01

    Polycrystalline Ni nanowires have been prepared by electrochemical deposition in an anodic alumina membrane template with a nanopore size of about 60 nm. In situ heating extended x-ray absorption fine structure and x-ray diffraction techniques are used to probe the atomic structures. The nanowires are identified as being mixtures of nanocrystallites and amorphous phase. The nanocrystallites have the same thermal expansion coefficient, of 1.7 x 10 -5 K -1 , as Ni bulk; however, the amorphous phase has a much larger thermal expansion coefficient of 3.5 x 10 -5 K -1 . Details of the Ni nanowire structures are discussed in this paper

  13. PREFACE: The 15th International Conference on X-ray Absorption Fine Structure (XAFS15)

    Science.gov (United States)

    Wu, Z. Y.

    2013-04-01

    The 15th International Conference on X-ray Absorption Fine Structure (XAFS15) was held on 22-28 July 2012 in Beijing, P. R. China. About 340 scientists from 34 countries attended this important international event. Main hall Figure 1. Main hall of XAFS15. The rapidly increasing application of XAFS to the study of a large variety of materials and the operation of the new SR source led to the first meeting of XAFS users in 1981 in England. Following that a further 14 International Conferences have been held. Comparing a breakdown of attendees according to their national origin, it is clear that participation is spreading to include attendees from more and more countries every year. The strategy of development in China of science and education is increasing quickly thanks to the large investment in scientific and technological research and infrastructure. There are three Synchrotron Radiation facilities in mainland China, Hefei Light Source (HLS) in the National Natural Science Foundation of China (NSRL), Beijing Synchrotron Radiation Facility (BSRF) in the Institute of High Energy Physics, and Shanghai Synchrotron Radiation Facility (SSRF) in the Shanghai Institute of Applied Physics. More than 10000 users and over 5000 proposals run at these facilities. Among them, many teams from the USA, Japan, German, Italy, Russia, and other countries. More than 3000 manuscript were published in SCI journals, including (incomplete) Science (7), Nature (10), Nature Series (7), PNAS (3), JACS (12), Angew. Chem. Int. Ed. (15), Nano Lett. (2), etc. In XAFS15, the participants contributed 18 plenary invited talks, 16 parallel invited talks, 136 oral presentations, 12 special talks, and 219 poster presentations. Wide communication was promoted in the conference halls, the classical banquet restaurant, and the Great Wall. Parallel hallCommunicationPoster room Figure 2. Parallel hallFigure 3. CommunicationFigure 4. Poster room This volume contains 136 invited and contributed papers

  14. Landscape-Level and Fine-Scale Genetic Structure of the Neo tropical Tree Protium spruceanum (Burseraceae)

    International Nuclear Information System (INIS)

    Vieira, F.D.A.; Fajardo, C.G.; De Souza, A.M.; Dulciniea De Carvalho, D.

    2010-01-01

    Knowledge of genetic structure at different scales and correlation with the current landscape is fundamental for evaluating the importance of evolutionary processes and identifying conservation units. Here, we used allozyme loci to examine the spatial genetic structure (SGS) of 230 individuals of Protium spruceanum, a native canopy-emergent in five fragments of Brazilian Atlantic forest (1 to 11.8 ha), and four ecological corridors (460 to 1000 m length). Wright's FST statistic and Mantel tests revealed little evidence of significant genetic structure at the landscape-scale (FST=0.027; rM=-0.051, P=.539). At fine-scale SGS, low levels of relatedness within fragments and corridors (Sp=0.008, P>.05) were observed. Differences in the levels and distribution of the SGS at both spatial scales are discussed in relation to biological and conservation strategies of corridors and forest fragments.

  15. An automated approach to network features of protein structure ensembles

    Science.gov (United States)

    Bhattacharyya, Moitrayee; Bhat, Chanda R; Vishveshwara, Saraswathi

    2013-01-01

    Network theory applied to protein structures provides insights into numerous problems of biological relevance. The explosion in structural data available from PDB and simulations establishes a need to introduce a standalone-efficient program that assembles network concepts/parameters under one hood in an automated manner. Herein, we discuss the development/application of an exhaustive, user-friendly, standalone program package named PSN-Ensemble, which can handle structural ensembles generated through molecular dynamics (MD) simulation/NMR studies or from multiple X-ray structures. The novelty in network construction lies in the explicit consideration of side-chain interactions among amino acids. The program evaluates network parameters dealing with topological organization and long-range allosteric communication. The introduction of a flexible weighing scheme in terms of residue pairwise cross-correlation/interaction energy in PSN-Ensemble brings in dynamical/chemical knowledge into the network representation. Also, the results are mapped on a graphical display of the structure, allowing an easy access of network analysis to a general biological community. The potential of PSN-Ensemble toward examining structural ensemble is exemplified using MD trajectories of an ubiquitin-conjugating enzyme (UbcH5b). Furthermore, insights derived from network parameters evaluated using PSN-Ensemble for single-static structures of active/inactive states of β2-adrenergic receptor and the ternary tRNA complexes of tyrosyl tRNA synthetases (from organisms across kingdoms) are discussed. PSN-Ensemble is freely available from http://vishgraph.mbu.iisc.ernet.in/PSN-Ensemble/psn_index.html. PMID:23934896

  16. Learning about the internal structure of categories through classification and feature inference.

    Science.gov (United States)

    Jee, Benjamin D; Wiley, Jennifer

    2014-01-01

    Previous research on category learning has found that classification tasks produce representations that are skewed toward diagnostic feature dimensions, whereas feature inference tasks lead to richer representations of within-category structure. Yet, prior studies often measure category knowledge through tasks that involve identifying only the typical features of a category. This neglects an important aspect of a category's internal structure: how typical and atypical features are distributed within a category. The present experiments tested the hypothesis that inference learning results in richer knowledge of internal category structure than classification learning. We introduced several new measures to probe learners' representations of within-category structure. Experiment 1 found that participants in the inference condition learned and used a wider range of feature dimensions than classification learners. Classification learners, however, were more sensitive to the presence of atypical features within categories. Experiment 2 provided converging evidence that classification learners were more likely to incorporate atypical features into their representations. Inference learners were less likely to encode atypical category features, even in a "partial inference" condition that focused learners' attention on the feature dimensions relevant to classification. Overall, these results are contrary to the hypothesis that inference learning produces superior knowledge of within-category structure. Although inference learning promoted representations that included a broad range of category-typical features, classification learning promoted greater sensitivity to the distribution of typical and atypical features within categories.

  17. Structural Features and Healthy Properties of Polysaccharides Occurring in Mushrooms

    Directory of Open Access Journals (Sweden)

    Eva Guillamón

    2012-12-01

    Full Text Available Polysaccharides from mushrooms have attracted a great deal of attention due to the many healthy benefits they have demonstrated, such as immunomodulation, anticancer activity, prevention and treatment of cardiovascular diseases, antiviral and antimicrobial effects, among others. Isolation and purification of polysaccharides commonly involve several steps, and different techniques are actually available in order to increase extraction yield and purity. Studies have demonstrated that the molecular structure and arrangement significantly influence the biological activity; therefore, there is a wide range of analytical techniques for the elucidation of chemical structures. Different polysaccharides have been isolated from mushrooms, most of them consisting of β-linked glucans, such as lentinan from Lentinus edodes, pleuran from Pleurotus species, schizophyllan from Schizophyllum commune, calocyban from Calocybe indica, or ganoderan and ganopoly from Ganoderma lucidum. This article reviews the main methods of polysaccharide isolation and structural characterization, as well as some of the most important polysaccharides isolated from mushrooms and the healthy benefits they provide.

  18. Evaluation of feature detection algorithms for structure from motion

    CSIR Research Space (South Africa)

    Govender, N

    2009-11-01

    Full Text Available technique with an application to stereo vision,” in International Joint Conference on Artificial Intelligence, April 1981. [17] C.Tomasi and T.Kanade, “Detection and tracking of point fetaures,” Carnegie Mellon, Tech. Rep., April 1991. [18] P. Torr... Algorithms for Structure from Motion Natasha Govender Mobile Intelligent Autonomous Systems CSIR Pretoria Email: ngovender@csir.co.za Abstract—Structure from motion is a widely-used technique in computer vision to perform 3D reconstruction. The 3D...

  19. Precise Study of Fine Structure in $^{14}$C Emission from $^{223}$Ra

    CERN Multimedia

    2002-01-01

    We request 10 shifts in two sessions of beam time at ISOLDE for the production of a $^{223}$Ra source. This source will be used with the superconducting spectrometer SOLENO at Orsay for a precise measurement (good statistics and energy resolution) of the fine stucture in the energy spectrum of $^{14}$C nuclei emitted by $^{223}$Ra, discovered at Orsay in July 1989. The measurement will be devoted to carry out the hindrance factors of the transitions to 15$\\!^-\\!$/2$\\,$ (1.423 MeV) and 5$\\!^+\\!$/2$\\,$ (1.567 MeV) excited states of $^{209}$Pb, which present a particular interest for obtaining spectroscopic information and testing nuclear models.

  20. Ultrasonic and structural features of some borosilicate glasses ...

    Indian Academy of Sciences (India)

    Therefore, the glass structure becomes contractedand compacted, which decreases its molar volume and increases its rigidity. This concept was asserted from the increase in the ultrasonic velocity, Debye temperature and elastic moduli with the increase of SiO2 content. The present compositional dependence of the elastic ...

  1. Unusual Features of Crystal Structures of Some Simple Copper Compounds

    Science.gov (United States)

    Douglas, Bodie

    2009-01-01

    Some simple copper compounds have unusual crystal structures. Cu[subscript 3]N is cubic with N atoms at centers of octahedra formed by 6 Cu atoms. Cu[subscript 2]O (cuprite) is also cubic; O atoms are in tetrahedra formed by 4 Cu atoms. These tetrahedra are linked by sharing vertices forming two independent networks without linkages between them.…

  2. Band structure features of nonlinear optical yttrium aluminium borate crystal

    Czech Academy of Sciences Publication Activity Database

    Reshak, Ali H; Auluck, S.; Majchrowski, A.; Kityk, I. V.

    2008-01-01

    Roč. 10, č. 10 (2008), s. 1445-1448 ISSN 1293-2558 Institutional research plan: CEZ:AV0Z60870520 Keywords : Electronic structure * DFF * FPLAPW * LDA Subject RIV: BO - Biophysics Impact factor: 1.742, year: 2008

  3. Direct Observation of the M1 Transition between the Ground Term Fine Structure Levels of W VIII

    Directory of Open Access Journals (Sweden)

    Momoe Mita

    2017-03-01

    Full Text Available We present a direct observation of the M1 transition between the fine structure splitting in the 4 f 13 5 s 2 5 p 6 2 F ground term of W VIII. The spectroscopic data of few-times ionized tungsten ions are important for the future ITER diagnostics, but there is a serious lack of data. The present study is part of an ongoing effort to solve this problem. Emission from the tungsten ions produced and trapped in a compact electron beam ion trap is observed with a Czerny–Turner visible spectrometer. Spectra in the EUV range are also observed at the same time to help identify the previously-unreported visible lines. The observed wavelength 574.47 ± 0.03 nm (air, which corresponds to the fine structure splitting of 17,402.5 ± 0.9 cm − 1 , shows reasonable agreement with the previously reported value 17,410 ± 5 cm − 1 obtained indirectly through the analysis of EUV spectra [Ryabtsev et al., Atoms 3 (2015 273].

  4. Fine-scale spatial genetic structure in predominantly selfing plants with limited seed dispersal: A rule or exception?

    Directory of Open Access Journals (Sweden)

    Sergei Volis

    2016-04-01

    Full Text Available Gene flow at a fine scale is still poorly understood despite its recognized importance for plant population demographic and genetic processes. We tested the hypothesis that intensity of gene flow will be lower and strength of spatial genetic structure (SGS will be higher in more peripheral populations because of lower population density. The study was performed on the predominantly selfing Avena sterilis and included: (1 direct measurement of dispersal in a controlled environment; and (2 analyses of SGS in three natural populations, sampled in linear transects at fixed increasing inter-plant distances. We found that in A. sterilis major seed dispersal is by gravity in close (less than 2 m vicinity of the mother plant, with a minor additional effect of wind. Analysis of SGS with six nuclear SSRs revealed a significant autocorrelation for the distance class of 1 m only in the most peripheral desert population, while in the two core populations with Mediterranean conditions, no genetic structure was found. Our results support the hypothesis that intensity of SGS increases from the species core to periphery as a result of decreased within-population gene flow related to low plant density. Our findings also show that predominant self-pollination and highly localized seed dispersal lead to SGS at a very fine scale, but only if plant density is not too high.

  5. Towards atomically resolved EELS elemental and fine structure mapping via multi-frame and energy-offset correction spectroscopy.

    Science.gov (United States)

    Wang, Yi; Huang, Michael R S; Salzberger, Ute; Hahn, Kersten; Sigle, Wilfried; van Aken, Peter A

    2018-01-01

    Electron energy-loss spectroscopy and energy-dispersive X-ray spectroscopy are two of the most common means for chemical analysis in the scanning transmission electron microscope. The marked progress of the instrumentation hardware has made chemical analysis at atomic resolution readily possible nowadays. However, the acquisition and interpretation of atomically resolved spectra can still be problematic due to image distortions and poor signal-to-noise ratio of the spectra, especially for investigation of energy-loss near-edge fine structures. By combining multi-frame spectrum imaging and automatic energy-offset correction, we developed a spectrum imaging technique implemented into customized DigitalMicrograph scripts for suppressing image distortions and improving the signal-to-noise ratio. With practical examples, i.e. SrTiO 3 bulk material and Sr-doped La 2 CuO 4 superlattices, we demonstrate the improvement of elemental mapping and the EELS spectrum quality, which opens up new possibilities for atomically resolved EELS fine structure mapping. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  6. Concordance of visual and structural features between siblings with albinism.

    Science.gov (United States)

    Heinmiller, Laura J; Holleschau, Ann; Summers, C Gail

    2016-02-01

    To evaluate similarities and differences in visual function and ocular structure between siblings with albinism. The medical records of all siblings diagnosed with albinism were retrospectively reviewed. Comparisons were made using examination at oldest age for younger sibling and examination closest to that age for older siblings. A total of 111 patients from 54 families were studied. Mean age was 12.9 years (range, 2 months to 44.2 years). Mean difference in ages between sibling pair examinations was 11.5 months (range, 0-87 months). Of 45 families, best-corrected visual acuity was equal in 9 (20%), within 1/2 octave in 9 (20%), >1/2 but albinism should be counseled with due caution because visual function is often disparate despite similar structural findings. Copyright © 2016 American Association for Pediatric Ophthalmology and Strabismus. Published by Elsevier Inc. All rights reserved.

  7. Structural features in icosahedral Al63Cu25Fe12

    International Nuclear Information System (INIS)

    Howell, R.H.; Solal, F.; Turchi, P.E.A.; Berger, C.; Calvayrac, Y.

    1991-01-01

    Since the discovery of a quasicrystalline phase in Al-Mn alloys a substantial amount of work has been done to understand the structural and physical properties of this new class of materials. More recently the discovery of a thermodynamically stable icosahedral phase in AlCuFe presents the opportunity to study pure quasicrystalline phases of high structural quality by eliminating known defects, especially phason disorder by conventional heat treatment. In particular it was shown that annealing treatments of as quenched samples resulted in a dramatic reduction in the width of the diffraction peaks associated with the elimination of as quenched defects, present in other quasicrystals. Positron annihilation lifetime measurements have a high sensitivity to intrinsic defects and positron annihilation radiation angular correlation measurements are well suited to measurements of electronic structure in systems where the defect effects do not dominate. We have measured positron annihilation lifetime and angular correlations on quasicrystalline samples of Al 63 Cu 25 Fe 12 in the pure icosahedral phase

  8. Fine structure of granal thylakoid membrane organization using cryo electron tomography

    NARCIS (Netherlands)

    Kouril, Roman; Oostergetel, Gert T.; Boekema, Egbert J.

    The architecture of grana membranes from spinach chloroplasts was studied by cryo electron tomography. Tomographic reconstructions of ice-embedded isolated grana stacks enabled to resolve features of photosystem II (PSII) in the native membrane and to assign the absolute orientation of individual

  9. Effect of diurnal photosynthetic activity on the fine structure of amylopectin from normal and waxy barley starch

    DEFF Research Database (Denmark)

    Goldstein, Avi; Annor, George; Blennow, Andreas

    2017-01-01

    growing conditions. The amylopectin fine structures were analysed by characterizing its unit chain length profiles after enzymatic debranching as well as its φ,β-limit dextrins and its clusters and building blocks after their partial and complete hydrolysis with α-amylase from Bacillus amyloliquefaciens...... density and longer average chain lengths than clusters derived from plants grown under constant light conditions. Amylopectin clusters from diurnally grown plants also consisted of a greater number of building blocks, and shorter inter-block chain lengths compared to clusters derived from plants grown......, respectively. Regardless of lighting conditions, no structural effects were found when comparing both the amylopectin side-chain distribution and the internal chain fragments of these amylopectins. However, the diurnally grown NBS and WBS both showed larger amylopectin clusters and these had lower branching...

  10. Transition from two-dimensional photonic crystals to dielectric metasurfaces in the optical diffraction with a fine structure

    Science.gov (United States)

    Rybin, Mikhail V.; Samusev, Kirill B.; Lukashenko, Stanislav Yu.; Kivshar, Yuri S.; Limonov, Mikhail F.

    2016-01-01

    We study experimentally a fine structure of the optical Laue diffraction from two-dimensional periodic photonic lattices. The periodic photonic lattices with the C4v square symmetry, orthogonal C2v symmetry, and hexagonal C6v symmetry are composed of submicron dielectric elements fabricated by the direct laser writing technique. We observe surprisingly strong optical diffraction from a finite number of elements that provides an excellent tool to determine not only the symmetry but also exact number of particles in the finite-length structure and the sample shape. Using different samples with orthogonal C2v symmetry and varying the lattice spacing, we observe experimentally a transition between the regime of multi-order diffraction, being typical for photonic crystals to the regime where only the zero-order diffraction can be observed, being is a clear fingerprint of dielectric metasurfaces characterized by effective parameters. PMID:27491952

  11. Structure of Co-Doped Alq3 thin films investigated by grazing incidence X-ray absorption fine structure and Fourier transform infrared spectroscopy.

    Science.gov (United States)

    Lin, Liang; Pang, Zhiyong; Fang, Shaojie; Wang, Fenggong; Song, Shumei; Huang, Yuying; Wei, Xiangjun; Yu, Haisheng; Han, Shenghao

    2011-02-10

    The structural properties of Co-doped tris(8-hydroxyquinoline)aluminum (Alq(3)) have been studied by grazing incidence X-ray absorption fine structure (GIXAFS) and Fourier transform infrared spectroscopy (FTIR). GIXAFS analysis suggests that there are multivalent Co-Alq(3) complexes and the doped Co atoms tend to locate at the attraction center with respect to N and O atoms and bond with them. The FTIR spectra indicate that the Co atoms interact with the meridional (mer) isomer of Alq(3) rather than forming inorganic compounds.

  12. Mapping the structural and dynamical features of kinesin motor domains.

    Directory of Open Access Journals (Sweden)

    Guido Scarabelli

    Full Text Available Kinesin motor proteins drive intracellular transport by coupling ATP hydrolysis to conformational changes that mediate directed movement along microtubules. Characterizing these distinct conformations and their interconversion mechanism is essential to determining an atomic-level model of kinesin action. Here we report a comprehensive principal component analysis of 114 experimental structures along with the results of conventional and accelerated molecular dynamics simulations that together map the structural dynamics of the kinesin motor domain. All experimental structures were found to reside in one of three distinct conformational clusters (ATP-like, ADP-like and Eg5 inhibitor-bound. These groups differ in the orientation of key functional elements, most notably the microtubule binding α4-α5, loop8 subdomain and α2b-β4-β6-β7 motor domain tip. Group membership was found not to correlate with the nature of the bound nucleotide in a given structure. However, groupings were coincident with distinct neck-linker orientations. Accelerated molecular dynamics simulations of ATP, ADP and nucleotide free Eg5 indicate that all three nucleotide states could sample the major crystallographically observed conformations. Differences in the dynamic coupling of distal sites were also evident. In multiple ATP bound simulations, the neck-linker, loop8 and the α4-α5 subdomain display correlated motions that are absent in ADP bound simulations. Further dissection of these couplings provides evidence for a network of dynamic communication between the active site, microtubule-binding interface and neck-linker via loop7 and loop13. Additional simulations indicate that the mutations G325A and G326A in loop13 reduce the flexibility of these regions and disrupt their couplings. Our combined results indicate that the reported ATP and ADP-like conformations of kinesin are intrinsically accessible regardless of nucleotide state and support a model where neck

  13. Features of structural response of mechanically loaded crystallites to irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Korchuganov, Aleksandr V., E-mail: avkor@ispms.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); National Research Tomsk State University, Tomsk, 634050 (Russian Federation)

    2015-10-27

    A molecular dynamics method is employed to investigate the origin and evolution of plastic deformation in elastically deformed iron and vanadium crystallites due to atomic displacement cascades. Elastic stress states of crystallites result from different degrees of specimen deformation. Crystallites are deformed under constant-volume conditions. Atomic displacement cascades with the primary knock-on atom energy up to 50 keV are generated in loaded specimens. It is shown that irradiation may cause not only the Frenkel pair formation but also large-scale structural rearrangements outside the irradiated area, which prove to be similar to rearrangements proceeding by the twinning mechanism in mechanically loaded specimens.

  14. Applications of UAS-SfM for coastal vulnerability assessment: Geomorphic feature extraction and land cover classification from fine-scale elevation and imagery data

    Science.gov (United States)

    Sturdivant, E. J.; Lentz, E. E.; Thieler, E. R.; Remsen, D.; Miner, S.

    2016-12-01

    Characterizing the vulnerability of coastal systems to storm events, chronic change and sea-level rise can be improved with high-resolution data that capture timely snapshots of biogeomorphology. Imagery acquired with unmanned aerial systems (UAS) coupled with structure from motion (SfM) photogrammetry can produce high-resolution topographic and visual reflectance datasets that rival or exceed lidar and orthoimagery. Here we compare SfM-derived data to lidar and visual imagery for their utility in a) geomorphic feature extraction and b) land cover classification for coastal habitat assessment. At a beach and wetland site on Cape Cod, Massachusetts, we used UAS to capture photographs over a 15-hectare coastal area with a resulting pixel resolution of 2.5 cm. We used standard SfM processing in Agisoft PhotoScan to produce an elevation point cloud, an orthomosaic, and a digital elevation model (DEM). The SfM-derived products have a horizontal uncertainty of +/- 2.8 cm. Using the point cloud in an extraction routine developed for lidar data, we determined the position of shorelines, dune crests, and dune toes. We used the output imagery and DEM to map land cover with a pixel-based supervised classification. The dense and highly precise SfM point cloud enabled extraction of geomorphic features with greater detail than with lidar. The feature positions are reported with near-continuous coverage and sub-meter accuracy. The orthomosaic image produced with SfM provides visual reflectance with higher resolution than those available from aerial flight surveys, which enables visual identification of small features and thus aids the training and validation of the automated classification. We find that the high-resolution and correspondingly high density of UAS data requires some simple modifications to existing measurement techniques and processing workflows, and that the types of data and the quality provided is equivalent to, and in some cases surpasses, that of data

  15. Fine-scale genetic structure and cryptic associations reveal evidence of kin-based sociality in the African forest elephant.

    Directory of Open Access Journals (Sweden)

    Stephanie G Schuttler

    Full Text Available Spatial patterns of relatedness within animal populations are important in the evolution of mating and social systems, and have the potential to reveal information on species that are difficult to observe in the wild. This study examines the fine-scale genetic structure and connectivity of groups within African forest elephants, Loxodonta cyclotis, which are often difficult to observe due to forest habitat. We tested the hypothesis that genetic similarity will decline with increasing geographic distance, as we expect kin to be in closer proximity, using spatial autocorrelation analyses and Tau K(r tests. Associations between individuals were investigated through a non-invasive genetic capture-recapture approach using network models, and were predicted to be more extensive than the small groups found in observational studies, similar to fission-fusion sociality found in African savanna (Loxodonta africana and Asian (Elephas maximus species. Dung samples were collected in Lopé National Park, Gabon in 2008 and 2010 and genotyped at 10 microsatellite loci, genetically sexed, and sequenced at the mitochondrial DNA control region. We conducted analyses on samples collected at three different temporal scales: a day, within six-day sampling sessions, and within each year. Spatial autocorrelation and Tau K(r tests revealed genetic structure, but results were weak and inconsistent between sampling sessions. Positive spatial autocorrelation was found in distance classes of 0-5 km, and was strongest for the single day session. Despite weak genetic structure, individuals within groups were significantly more related to each other than to individuals between groups. Social networks revealed some components to have large, extensive groups of up to 22 individuals, and most groups were composed of individuals of the same matriline. Although fine-scale population genetic structure was weak, forest elephants are typically found in groups consisting of kin and

  16. Fine-scale genetic structure and cryptic associations reveal evidence of kin-based sociality in the African forest elephant.

    Science.gov (United States)

    Schuttler, Stephanie G; Philbrick, Jessica A; Jeffery, Kathryn J; Eggert, Lori S

    2014-01-01

    Spatial patterns of relatedness within animal populations are important in the evolution of mating and social systems, and have the potential to reveal information on species that are difficult to observe in the wild. This study examines the fine-scale genetic structure and connectivity of groups within African forest elephants, Loxodonta cyclotis, which are often difficult to observe due to forest habitat. We tested the hypothesis that genetic similarity will decline with increasing geographic distance, as we expect kin to be in closer proximity, using spatial autocorrelation analyses and Tau K(r) tests. Associations between individuals were investigated through a non-invasive genetic capture-recapture approach using network models, and were predicted to be more extensive than the small groups found in observational studies, similar to fission-fusion sociality found in African savanna (Loxodonta africana) and Asian (Elephas maximus) species. Dung samples were collected in Lopé National Park, Gabon in 2008 and 2010 and genotyped at 10 microsatellite loci, genetically sexed, and sequenced at the mitochondrial DNA control region. We conducted analyses on samples collected at three different temporal scales: a day, within six-day sampling sessions, and within each year. Spatial autocorrelation and Tau K(r) tests revealed genetic structure, but results were weak and inconsistent between sampling sessions. Positive spatial autocorrelation was found in distance classes of 0-5 km, and was strongest for the single day session. Despite weak genetic structure, individuals within groups were significantly more related to each other than to individuals between groups. Social networks revealed some components to have large, extensive groups of up to 22 individuals, and most groups were composed of individuals of the same matriline. Although fine-scale population genetic structure was weak, forest elephants are typically found in groups consisting of kin and based on matrilines

  17. Features of structure of motor nerve endings in the tongue of normal and dehydrated rats

    Directory of Open Access Journals (Sweden)

    S. L. Popel’

    2017-07-01

    Full Text Available This study aims at an analytical review of scientific literature on the structure of the tongue of different animals and humans, and also at studying the features of the structure of motor nerve endings in the tongue muscles of healthy rats and rats that have undergone prolonged dehydration. Over 14 days, using histological methods we studied neuromuscular endings and peculiarities of their distribution in the tongue muscles of 25 mature rats, both in normal condition and under dehydration. The analysis of the results showed different structures of differentiated motor nerve endings among the rats in normal condition, and also revealed the peculiarities and quantitative characteristics of the components of the neuromuscular endings in relation to the duration of dehydration. The type of neuromuscular ending reflects the morphologically interdependent structure of efferent neuromediators in relation to a part of the tongue. This may determine the nature of the processes of prehension and chewing of food. The structure of neuromuscular endings of the muscles of the tip of the tongue is the most differentiated, they are more numerous and larger. The tip of the tongue of rats had a higher number of nuclei and larger size of the neuromuscular endings of the muscles than the other parts. This, perhaps, is determined by the speed of the movements of the tongue due to eating different foods. The number of nuclei and the size of neuromuscular endings are characterized by significant variations in the pattern of axon branching, which is determined by the anatomical, physiological and biomechanical conditions of functioning of the rats’ tongue muscles. The quantitative analysis of structural peculiarities of axomycin synapses showed that muscle fibers of the tongue have neuroumuscular endings with regulated synaptoarchitectonics which is characterized by the sprouting of the motor axon, a certain length and width of the active zones, number and size of

  18. X-ray photoemission spectroscopy (XPS) and extended x-ray absorption fine structure (EXAFS) studies of silicate based glasses

    International Nuclear Information System (INIS)

    Karim, D.; Lam, D.J.

    1979-01-01

    The application of the x-ray photoemission spectroscopy (XPS) technique to study the electronic structure and bonding of heavy metal oxides in alkali- and alkali-earth-silicate glasses had been demonstrated. The bonding characteristics of the iron oxide and uranium oxide in sodium silicate glasses were deduced from the changes in the oxygen 1s levels and the heavy metal core levels. It is reasonable to expect that the effect of leaching on the heavy metal ions can be monitored using the appropriate core levels of these ions. To study the effect of leaching on the glass forming network, the valence band structure of the bridging and nonbridging oxygens in sodium silicate glasses were investigated. The measurement of extended x-ray absorption fine-structure (EXAFS) is a relatively new analytical technique for obtaining short range (<5 A) structural information around atoms of a selected species in both solid and fluid systems. Experiments have recently begun to establish the feasibility of using EXAFS to study the bonding of actinides in silicate glasses. Because of the ability of EXAFS to yield specific structural data even in complex multicomponent systems, it could prove to be an invaluable tool in understanding glass structure

  19. Simulation of Probe Position-Dependent Electron Energy-Loss Fine Structure

    Energy Technology Data Exchange (ETDEWEB)

    Oxley, M. P.; Kapetanakis, M. D.; Prange, Micah P.; Varela, M.; Pennycook, Stephen J.; Pantelides, Sokrates T.

    2014-03-31

    We present a theoretical framework for calculating probe-position-dependent electron energy-loss near-edge structure for the scanning transmission electron microscope by combining density functional theory with dynamical scattering theory. We show how simpler approaches to calculating near-edge structure fail to include the fundamental physics needed to understand the evolution of near-edge structure as a function of probe position and investigate the dependence of near-edge structure on probe size. It is within this framework that density functional theory should be presented, in order to ensure that variations of near-edge structure are truly due to local electronic structure and how much from the diffraction and focusing of the electron beam.

  20. Estimating the collapse of aggregated fine soil structure in a mountainous forested catchment.

    Science.gov (United States)

    Mouri, Goro; Shinoda, Seirou; Golosov, Valentin; Chalov, Sergey; Shiiba, Michiharu; Hori, Tomoharu; Oki, Taikan

    2014-06-01

    This paper describes the relationship of forest soil dryness and antecedent rainfall with suspended sediment (SS) yield due to extreme rainfall events and how this relationship affects the survival of forest plants. Several phenomena contribute to this relationship: increasing evaporation (amount of water vapour discharged from soil) due to increasing air temperature, decreasing moisture content in the soil, the collapse of aggregates of fine soil particles, and the resulting effects on forest plants. To clarify the relationships among climate variation, the collapse of soil particle aggregates, and rainfall-runoff processes, a numerical model was developed to reproduce such aggregate collapse in detail. The validity of the numerical model was confirmed by its application to the granitic mountainous catchment of the Nagara River basin in Japan and by comparison with observational data. The simulation suggests that important problems, such as the collapse of forest plants in response to decreases in soil moisture content and antecedent rainfall, will arise if air temperature continues to increase. Copyright © 2013 The Authors. Published by Elsevier Ltd.. All rights reserved.

  1. Structure, hardness and fracture features of nanostructural materials

    International Nuclear Information System (INIS)

    Noskova, N.I.; Korznikov, A.V.; Idrisova, S.R.

    2000-01-01

    A study is made into nanocrystalline metals Cu and Mo, nanocrystalline intermetallic compound Ni 3 Al produced using severe plastic deformation; nanophase alloys Fe 73.5 Cu 1 Nb 3 Si 1.35 B 9 and Pd 81 Cu 7 Si 12 produced by crystallization from amorphous state as well as nanophase materials TiN and Al 2 O 3 produced by nano powder compacting in the temperature range of 273-573 K. Methods of transmission and scanning electron microscopy, X-ray diffraction analysis, mechanical testing and microhardness measurement are applied to study structure, internal elastic stress, phase composition, hardness, strength and plastic properties, surface fracture mode of nanostructural materials [ru

  2. Some features of borophosphatic catalysts structure with silicate bond

    International Nuclear Information System (INIS)

    Kubasov, A.A.; Kitaev, L.E.; Topchieva, K.V.; Gonchakova, N.N.

    1979-01-01

    The structure of borophosphatic catalysts is studied using the method of IR-spectroscopy. Silica gel and diatomite brick were used as a binding (carriers). To clarify the character of the carrier effect on borophosphate structure obtained were boric and phosphoric acid spectra, covered in the quantity of 10 weight % on SiO 2 , and also industrial catalyst H 3 PO 4 /SiO 2 of hydratation with higher P 2 O 5 content. At calcination of sample 10% H 3 BO 3 /SiO 2 in vacuum 932 cm -1 strip intensity increased with the temperature rise and that can be referred to B-O-Si vibrations. In the area of fundamental vibrations P-O and Si-O spectrum of the 10% H 3 PO 4 /SiO 2 sample, subjected to heating up to 600 deg C in the air, differed but slightly from the initial SiO 2 spectrum. In the spectrum of the sample with higher P 2 O 5 content after thermovapor treatment at 300 deg C in the frequency range of 500-800 cm -1 strips were detected, which testified to the phosphoric acid interaction with silica gel. The state of adsorbed water can be judged by the change of 1630 cm -1 strip optical density in the course of step thermovacuum borophosphate treatment. It was found that water was removed from the sample surface in the range of 200-300 deg C. Thus, at borophosphate catalysts calcination which contains SiO 2 , interaction took place between borophosphate and bind components accompanied by B-O-Si and P-O-Si bonds formation. Water removal from these catalyst surfaces took place at lower temperature as compared to individual borophosphate, which testified to certain release of electron acceptor properties as a result of the bind component introduction. Thus, the bind component introduction not only increases mechanical strength and hydrolytic stability of borophosphates but results in their surface modification

  3. Determination of Structural Parameters from EXAFS (Extended X-Ray Absorption Fine Structure): Application to Solutions and Catalysts.

    Science.gov (United States)

    1984-05-23

    the disorder was accurately known. Inverse Transform To isolate the EAFS contribution due to a single feature in the Fourier transform, the inverse ...is associated with setting the "fold" components to 27 zero in r-space. An inverse transform (real part) of the major feature of the Fig. 4 Fourier...phase of the resulting inverse transform represents only any differences between the material being studied and the reference. This residual is

  4. Structural and functional features of central nervous system lymphatic vessels.

    Science.gov (United States)

    Louveau, Antoine; Smirnov, Igor; Keyes, Timothy J; Eccles, Jacob D; Rouhani, Sherin J; Peske, J David; Derecki, Noel C; Castle, David; Mandell, James W; Lee, Kevin S; Harris, Tajie H; Kipnis, Jonathan

    2015-07-16

    One of the characteristics of the central nervous system is the lack of a classical lymphatic drainage system. Although it is now accepted that the central nervous system undergoes constant immune surveillance that takes place within the meningeal compartment, the mechanisms governing the entrance and exit of immune cells from the central nervous system remain poorly understood. In searching for T-cell gateways into and out of the meninges, we discovered functional lymphatic vessels lining the dural sinuses. These structures express all of the molecular hallmarks of lymphatic endothelial cells, are able to carry both fluid and immune cells from the cerebrospinal fluid, and are connected to the deep cervical lymph nodes. The unique location of these vessels may have impeded their discovery to date, thereby contributing to the long-held concept of the absence of lymphatic vasculature in the central nervous system. The discovery of the central nervous system lymphatic system may call for a reassessment of basic assumptions in neuroimmunology and sheds new light on the aetiology of neuroinflammatory and neurodegenerative diseases associated with immune system dysfunction.

  5. Multiscale pore structure and constitutive models of fine-grained rocks

    Science.gov (United States)

    Heath, J. E.; Dewers, T. A.; Shields, E. A.; Yoon, H.; Milliken, K. L.

    2017-12-01

    A foundational concept of continuum poromechanics is the representative elementary volume or REV: an amount of material large enough that pore- or grain-scale fluctuations in relevant properties are dissipated to a definable mean, but smaller than length scales of heterogeneity. We determine 2D-equivalent representative elementary areas (REAs) of pore areal fraction of three major types of mudrocks by applying multi-beam scanning electron microscopy (mSEM) to obtain terapixel image mosaics. Image analysis obtains pore areal fraction and pore size and shape as a function of progressively larger measurement areas. Using backscattering imaging and mSEM data, pores are identified by the components within which they occur, such as in organics or the clastic matrix. We correlate pore areal fraction with nano-indentation, micropillar compression, and axysimmetic testing at multiple length scales on a terrigenous-argillaceous mudrock sample. The combined data set is used to: investigate representative elementary volumes (and areas for the 2D images); determine if scale separation occurs; and determine if transport and mechanical properties at a given length scale can be statistically defined. Clear scale separation occurs between REAs and observable heterogeneity in two of the samples. A highly-laminated sample exhibits fine-scale heterogeneity and an overlapping in scales, in which case typical continuum assumptions on statistical variability may break down. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc. for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-NA0003525.

  6. Laboratory-based recording of holographic fine structure in X-ray absorption anisotropy using polycapillary optics

    Energy Technology Data Exchange (ETDEWEB)

    Dabrowski, K.M. [Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Krakow (Poland); Korecki, P., E-mail: pawel.korecki@uj.edu.pl [Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Krakow (Poland)

    2012-08-15

    Highlights: Black-Right-Pointing-Pointer Holographic fine structures in X-ray absorption recorded using a tabletop setup. Black-Right-Pointing-Pointer Setup based on polycapillary collimating optics and an HOPG crystal. Black-Right-Pointing-Pointer Demonstration of element sensitivity by detection of X-ray fluorescence. Black-Right-Pointing-Pointer Potential of laboratory-based experiments for heavily doped crystals and thin films. - Abstract: A tabletop setup composed of a collimating polycapillary optics and a highly oriented pyrolytic graphite monochromator (HOPG) was characterized and used for recording two-dimensional maps of X-ray absorption anisotropy (XAA). XAA originates from interference of X-rays directly inside the sample. Depending on experimental conditions, fine structures in XAA can be interpreted in terms of X-ray holograms or X-ray standing waves and can be used for an element selective atomic-resolved structural analysis. The implementation of polycapillary optics resulted in a two-order of magnitude gain in the radiant intensity (photons/s/solid angle) as compared to a system without optics and enabled efficient recording of XAA with a resolution of 0.15 Degree-Sign for Mo K{alpha} radiation. Element sensitivity was demonstrated by acquisition of distinct XAA signals for Ga and As atoms in a GaAs (1 1 1) wafer by using X-ray fluorescence as a secondary signal. These results indicate the possibility of performing laboratory-based XAA experiments for heavily doped single crystals or thin films. So far, because of the weak holographic modulation of XAA, such experiments could be only performed using synchrotron radiation.

  7. Fine-scale population structure and riverscape genetics of brook trout (Salvelinus fontinalis) distributed continuously along headwater channel networks

    Science.gov (United States)

    Kanno, Yoichiro; Vokoun, Jason C.; Letcher, Benjamin H.

    2011-01-01

    Linear and heterogeneous habitat makes headwater stream networks an ideal ecosystem in which to test the influence of environmental factors on spatial genetic patterns of obligatory aquatic species. We investigated fine-scale population structure and influence of stream habitat on individual-level genetic differentiation in brook trout (Salvelinus fontinalis) by genotyping eight microsatellite loci in 740 individuals in two headwater channel networks (7.7 and 4.4 km) in Connecticut, USA. A weak but statistically significant isolation-by-distance pattern was common in both sites. In the field, many tagged individuals were recaptured in the same 50-m reaches within a single field season (summer to fall). One study site was characterized with a hierarchical population structure, where seasonal barriers (natural falls of 1.5–2.5 m in height during summer base-flow condition) greatly reduced gene flow and perceptible spatial patterns emerged because of the presence of tributaries, each with a group of genetically distinguishable individuals. Genetic differentiation increased when pairs of individuals were separated by high stream gradient (steep channel slope) or warm stream temperature in this site, although the evidence of their influence was equivocal. In a second site, evidence for genetic clusters was weak at best, but genetic differentiation between individuals was positively correlated with number of tributary confluences. We concluded that the population-level movement of brook trout was limited in the study headwater stream networks, resulting in the fine-scale population structure (genetic clusters and clines) even at distances of a few kilometres, and gene flow was mitigated by ‘riverscape’ variables, particularly by physical barriers, waterway distance (i.e. isolation-by-distance) and the presence of tributaries.

  8. Fine structure characterization of zero-valent iron nanoparticles for decontamination of nitrites and nitrates in wastewater and groundwater

    Directory of Open Access Journals (Sweden)

    Kuen-Song Lin et al

    2008-01-01

    Full Text Available The main objectives of the present study were to investigate the chemical reduction of nitrate or nitrite species by zero-valent iron nanoparticle (ZVIN in aqueous solution and related reaction kinetics or mechanisms using fine structure characterization. This work also exemplifies the utilization of field emission-scanning electron microscope (FE–SEM, transmission electron microscopy (TEM, and x-ray diffraction (XRD to reveal the speciation and possible reaction pathway in a very complex adsorption and redox reaction process. Experimentally, ZVIN of this study was prepared by sodium borohydride reduction method at room temperature and ambient pressure. The morphology of as-synthesized ZVIN shows that the nearly ball and ultrafine particles ranged of 20–50 nm were observed with FE–SEM or TEM analysis. The kinetic model of nitrites or nitrates reductive reaction by ZVIN is proposed as a pseudo first-order kinetic equation. The nitrite and nitrate removal efficiencies using ZVIN were found 65–83% and 51–68%, respectively, based on three different initial concentrations. Based on the XRD pattern analyses, it is found that the quantitative relationship between nitrite and Fe(III or Fe(II is similar to the one between nitrate and Fe(III in the ZVIN study. The possible reason is due to the faster nitrite reduction by ZVIN. In fact, the occurrence of the relative faster nitrite reductive reaction suggested that the passivation of the ZVIN have a significant contribution to iron corrosion. The extended x-ray absorption fine structure (EXAFS or x-ray absorption near edge structure (XANES spectra show that the nitrites or nitrates reduce to N2 or NH3 while oxidizing the ZVIN to Fe2O3 or Fe3O4 electrochemically. It is also very clear that decontamination of nitrate or nitrite species in groundwater via the in-situ remediation with a ZVIN permeable reactive barrier would be environmentally attractive.

  9. Sequence of structures in fine-grained turbidites: Comparison of recent deep-sea and ancient flysch sediments

    Science.gov (United States)

    Stow, Dorrik A. V.; Shanmugam, Ganapathy

    1980-01-01

    A comparative study of the sequence of sedimentary structures in ancient and modern fine-grained turbidites is made in three contrasting areas. They are (1) Holocene and Pleistocene deep-sea muds of the Nova Scotian Slope and Rise, (2) Middle Ordovician Sevier Shale of the Valley and Ridge Province of the Southern Appalachians, and (3) Cambro-Ordovician Halifax Slate of the Meguma Group in Nova Scotia. A standard sequence of structures is proposed for fine-grained turbidites. The complete sequence has nine sub-divisions that are here termed T 0 to T 8. "The lower subdivision (T 0) comprises a silt lamina which has a sharp, scoured and load-cast base, internal parallel-lamination and cross-lamination, and a sharp current-lineated or wavy surface with 'fading-ripples' (= Type C etc. …)." (= Type C ripple-drift cross-lamination, Jopling and Walker, 1968). The overlying sequence shows textural and compositional grading through alternating silt and mud laminae. A convolute-laminated sub-division (T 1) is overlain by low-amplitude climbing ripples (T 2), thin regular laminae (T 3), thin indistinct laminae (T 4), and thin wipsy or convolute laminae (T 5). The topmost three divisions, graded mud (T 6), ungraded mud (T 7) and bioturbated mud (T 8), do not have silt laminae but rare patchy silt lenses and silt pseudonodules and a thin zone of micro-burrowing near the upper surface. The proposed sequence is analogous to the Bouma (1962) structural scheme for sandy turbidites and is approximately equivalent to Bouma's (C)DE divisions. The repetition of partial sequences characterizes different parts of the slope/base-of-slope/basin plain environment, and represents deposition from different stages of evolution of a large, muddy, turbidity flow. Microstructural detail and sequence are well preserved in ancient and even slightly metamorphosed sediments. Their recognition is important for determining depositional processes and for palaeoenvironmental interpretation.

  10. X-ray diffraction study of the fine structure of twaron fibres in the temperature range 750 kelvin - 9500 kelvin

    International Nuclear Information System (INIS)

    Abu Obaid, A. A.

    1991-01-01

    The thesis dealt with the fine structural behaviour of twaron fibres, spun from the polymer poly (p-phenylene terephthalamide), due to physical treatments in the temperature range 75 to 984 kelvin (-198 to 675 degrees celsius). The treatments were annealing, cooling, cold ageing and vibratory milling. The structure was characterized by wide-angle x-ray diffraction (WAXS) and thermogravimetric analysis (TGA). The structural parameters included crystallinity, microparacrystal (mPc) sizes, net plane spacings, unit cell dimensions and mass stability. The TGA results indicated good mass stability up to 500 degrees celsius. The crystallinity and mPc sizes reached their maximum values after annealing the fibres at 425 degrees celsius (crystallinity increased by 5% and mPC sizes increased by approximately 40 to 50 %). After 500 degrees celsius, the crystallinity and mPC sizes dropped remarkably. Cooling the twaron fibres down to -198 degrees celsius did not affect the structure. Cold ageing of the fibres at -15 degrees celsius for periods up to 100 days, and cold ageing at -198 degrees celsius up to 48 hours did not affect the structure as well; however cold ageing at -198 degrees celsius for 120 hours caused a drop of 5% in the crystallinity and 10% in the mPc sizes. 35 refs., 28 figs., 9 tabs. (A.M.H.)

  11. Effect of the isothermal transformation temperature on the fine structure of steel-12Kh1MF

    International Nuclear Information System (INIS)

    Mints, I.I.; Berezina, T.G.; Lanskaya, K.A.

    1976-01-01

    For detailed analysis of bainite and pearlite in steel 12Kh1MF, homogeneous structures were obtained by isothermal annealing at 350, 450, 500, and 650 0 for 1 h. Isothermal transformation of austenite leads to the formation of bainite at 350-500 0 and pearlite at 650 0 . The austenitizing temperature was 980 0 for both types of samples, with holding for 20 min. For comparison, the plates were quenched from 980 0 and 1050 0 in ice-cold brine. The investigation was conducted with use of light and electron microscopes and x-ray analysis. The long-term strength was also determined. Isothermal treatment of steel 12Kh1MF at 350-500 0 C leads to the formation of a structure consisting of upper and lower bainite. At 500 0 the structure consists primarily of upper bainite, and at 350 0 of lower bainite. With tempering of the steel with a structure of upper and lower bainite at 730 0 for 3 h the dislocations undergo redistribution of the polygonization type within ferrite needles, with development of a cellular substructure. The acicular structure of the matrix is retained in this case. The density and evenness of the distribution of carbides is higher in upper bainite than in lower bainite. Steel 12Kh1MF with a structure of upper bainite is more susceptible to recrystallization as compared with a structure of lower bainite, which is responsible for the higher heat resistance of the latter

  12. Human-modified landscapes: patterns of fine-scale woody vegetation structure in communal savannah rangelands

    CSIR Research Space (South Africa)

    Fisher, T

    2011-11-01

    Full Text Available structure in five communal rangelands around 12 settlements in Bushbuckridge, a municipality in the Kruger to Canyons Biosphere Reserve (South Africa). The importance of underlying abiotic factors was evaluated by measuring size class distributions across...

  13. Fine structures in Fe3Al alloy layer of a new hot dip aluminized steel

    Indian Academy of Sciences (India)

    Unknown

    *National Key Laboratory of Advanced Welding Production Technology, Harbin ... †Key Lab of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, ... improve the adhesion of the liquid aluminum to the base.

  14. Architecture and fine structure of gill filaments in the brown mussel, perna perna

    CSIR Research Space (South Africa)

    Gregory, MA

    1996-10-01

    Full Text Available attention was paid to filament architecture, enervation of filaments, number and type of cells populating filament epithelia and variations in epithelial cell morphotogy and cilia ultra structure. Filament shape was maintained by thickened chitin...

  15. Compressive behavior of pervious concretes and a quantification of the influence of random pore structure features

    International Nuclear Information System (INIS)

    Deo, Omkar; Neithalath, Narayanan

    2010-01-01

    Research highlights: → Identified the relevant pore structure features of pervious concretes, provided methodologies to extract those, and quantified the influence of these features on compressive response. → A model for stress-strain relationship of pervious concretes, and relationship between model parameters and parameters of the stress-strain relationship developed. → Statistical model for compressive strength as a function of pore structure features; and a stochastic model for the sensitivity of pore structure features in strength prediction. - Abstract: Properties of a random porous material such as pervious concrete are strongly dependent on its pore structure features, porosity being an important one among them. This study deals with developing an understanding of the material structure-compressive response relationships in pervious concretes. Several pervious concrete mixtures with different pore structure features are proportioned and subjected to static compression tests. The pore structure features such as pore area fractions, pore sizes, mean free spacing of the pores, specific surface area, and the three-dimensional pore distribution density are extracted using image analysis methods. The compressive stress-strain response of pervious concretes, a model to predict the stress-strain response, and its relationship to several of the pore structure features are outlined. Larger aggregate sizes and increase in paste volume fractions are observed to result in increased compressive strengths. The compressive response is found to be influenced by the pore sizes, their distributions and spacing. A statistical model is used to relate the compressive strength to the relevant pore structure features, which is then used as a base model in a Monte-Carlo simulation to evaluate the sensitivity of the predicted compressive strength to the model terms.

  16. Optical analysis of the fine crystalline structure of artificial opal films.

    Science.gov (United States)

    Lozano, G; Dorado, L A; Schinca, D; Depine, R A; Míguez, H

    2009-11-17

    Herein, we present a detailed analysis of the structure of artificial opal films. We demonstrate that, rather than the generally assumed face centered cubic lattice of spheres, opal films are better approximated by rhombohedral assemblies of distorted colloids. Detailed analysis of the optical response in a very wide spectral range (0.4 opal films is provided, as well as of the photonic band structure of the proposed arrangement. The implications of this distortion in the optical response of the lattice are discussed.

  17. Consequences of fine structure of β-strength function in the nuclear physics and astrophysics

    International Nuclear Information System (INIS)

    Klapdor, H.V.; Wene, C.O.

    1980-01-01

    The consequences of structural effects in the β-strength function Ssub(β) in different fields of nuclear physics and astrophysics are considered. The given structure is shown to affect essentially the lifetimes relative to β-decay, emission of delayed particles, delayed fission and, consequently, all the calculations of synthesis of heavy and superheavy elements in astrophysical and thermonuclear processes. A table of experimental procedures applied for studying the β-strength function in different reactions is given

  18. Laser Control of Self-Organization Process in Microscopic Region and Fabrication of Fine Microporous Structure

    OpenAIRE

    Matsumura, Yukimasa; Inami, Wataru; Kawata, Yoshimasa

    2012-01-01

    We present a controlling technique of microporous structure by laser irradiation during self-organization process. Self-organization process is fabrication method of microstructure. Polymer solution was dropped on the substrate at high humid condition. Water in air appears dropping air temperature below the dew point. The honeycomb structure with regularly aligned pores on the film was fabricated by attaching water droplets onto the solution surface. We demonstrate that it was possible to pre...

  19. DroidEnsemble: Detecting Android Malicious Applications with Ensemble of String and Structural Static Features

    KAUST Repository

    Wang, Wei

    2018-05-11

    Android platform has dominated the Operating System of mobile devices. However, the dramatic increase of Android malicious applications (malapps) has caused serious software failures to Android system and posed a great threat to users. The effective detection of Android malapps has thus become an emerging yet crucial issue. Characterizing the behaviors of Android applications (apps) is essential to detecting malapps. Most existing work on detecting Android malapps was mainly based on string static features such as permissions and API usage extracted from apps. There also exists work on the detection of Android malapps with structural features, such as Control Flow Graph (CFG) and Data Flow Graph (DFG). As Android malapps have become increasingly polymorphic and sophisticated, using only one type of static features may result in false negatives. In this work, we propose DroidEnsemble that takes advantages of both string features and structural features to systematically and comprehensively characterize the static behaviors of Android apps and thus build a more accurate detection model for the detection of Android malapps. We extract each app’s string features, including permissions, hardware features, filter intents, restricted API calls, used permissions, code patterns, as well as structural features like function call graph. We then use three machine learning algorithms, namely, Support Vector Machine (SVM), k-Nearest Neighbor (kNN) and Random Forest (RF), to evaluate the performance of these two types of features and of their ensemble. In the experiments, We evaluate our methods and models with 1386 benign apps and 1296 malapps. Extensive experimental results demonstrate the effectiveness of DroidEnsemble. It achieves the detection accuracy as 95.8% with only string features and as 90.68% with only structural features. DroidEnsemble reaches the detection accuracy as 98.4% with the ensemble of both types of features, reducing 9 false positives and 12 false

  20. In situ X-ray absorption fine structure studies on the structure of nickel phosphide catalyst supported on K-USY

    CERN Document Server

    Kawai, T; Suzuki, S

    2003-01-01

    Local structure around Ni in a nickel phosphide catalyst supported on K-USY was investigated by an situ X-ray absorption fine structure (XAFS) method during the reduction process of the catalyst and the hydrodesulfurization (HDS) reaction of thiophene. In the passivated sample, Ni phosphide was partially oxidized but after the reduction, 1.1 nm diameter Ni sub 2 P particles were formed with Ni-P and Ni-Ni distances at 0.218 and 0.261 nm, respectively, corresponding to those of bulk Ni sub 2 P. In situ XAFS cleary revealed that the Ni sub 2 P structure was stable under reaction conditions and was an active structure for the HDS process.

  1. Chinese wine classification system based on micrograph using combination of shape and structure features

    Science.gov (United States)

    Wan, Yi

    2011-06-01

    Chinese wines can be classification or graded by the micrographs. Micrographs of Chinese wines show floccules, stick and granule of variant shape and size. Different wines have variant microstructure and micrographs, we study the classification of Chinese wines based on the micrographs. Shape and structure of wines' particles in microstructure is the most important feature for recognition and classification of wines. So we introduce a feature extraction method which can describe the structure and region shape of micrograph efficiently. First, the micrographs are enhanced using total variation denoising, and segmented using a modified Otsu's method based on the Rayleigh Distribution. Then features are extracted using proposed method in the paper based on area, perimeter and traditional shape feature. Eight kinds total 26 features are selected. Finally, Chinese wine classification system based on micrograph using combination of shape and structure features and BP neural network have been presented. We compare the recognition results for different choices of features (traditional shape features or proposed features). The experimental results show that the better classification rate have been achieved using the combinational features proposed in this paper.

  2. Rocket photographs of fine structure and wave patterns in the solar temperature minimum

    Science.gov (United States)

    Bonnet, R. M.; Decaudin, M.; Foing, B.; Bruner, M.; Acton, L. W.; Brown, W. A.

    1982-01-01

    A new series of high resolution pictures of the sun has been obtained during the second flight of the Transition Region Camera which occurred on September 23, 1980. The qualitative analysis of the results indicates that a substantial portion of the solar surface at the temperature minimum radiates in non-magnetic regions and from features below 1 arcsec in size. Wave patterns are observed on the 160 nm temperature minimum pictures. They are absent on the Lyman alpha pictures. Their physical characteristics are compatible with those of gravitational and acoustic waves generated by exploding granules.

  3. Preparation of thick silica coatings on carbon fibers with fine-structured silica nanotubes induced by a self-assembly process

    Directory of Open Access Journals (Sweden)

    Benjamin Baumgärtner

    2017-05-01

    Full Text Available A facile method to coat carbon fibers with a silica shell is presented in this work. By immobilizing linear polyamines on the carbon fiber surface, the high catalytic activity of polyamines in the sol–gel-processing of silica precursors is used to deposit a silica coating directly on the fiber’s surface. The surface localization of the catalyst is achieved either by attaching short-chain polyamines (e.g., tetraethylenepentamine via covalent bonds to the carbon fiber surface or by depositing long-chain polyamines (e.g., linear poly(ethylenimine on the carbon fiber by weak non-covalent bonding. The long-chain polyamine self-assembles onto the carbon fiber substrate in the form of nanoscopic crystallites, which serve as a template for the subsequent silica deposition. The silicification at close to neutral pH is spatially restricted to the localized polyamine and consequently to the fiber surface. In case of the linear poly(ethylenimine, silica shells of several micrometers in thickness can be obtained and their morphology is easily controlled by a considerable number of synthesis parameters. A unique feature is the hierarchical biomimetic structure of the silica coating which surrounds the embedded carbon fiber by fibrillar and interconnected silica fine-structures. The high surface area of the nanostructured composite fiber may be exploited for catalytic applications and adsorption purposes.

  4. System of an analysis of a fine time structure of X-ray solar flares in the RGS-1M spectrometer

    International Nuclear Information System (INIS)

    Lazutkov, V.P.

    1980-01-01

    The possibilities of RGS-1M spectral equipment intended for determination of more detailed data on the solar flare structure are discussed. Spectrometer modernization permits to record the fine time structure of solar events in the hard X-ray range (50-90 keV). The main requirement for fine time analysis of nonstationary processes is determination of the maximum possible resolution at the maximum available length of the signal under investigation. The scheme of the time analyzer of splash events with the time resolution Δt=62.5 ms and the length of the range processed T=27.6 s is given and described. Operation of the spectrometer telemetric apparatus is considered in detail. The fine solar flare structure occurred on 14.04.79 with visually chosen periodic structure is shown as an example [ru

  5. Temporal Fine-Structure Coding and Lateralized Speech Perception in Normal-Hearing and Hearing-Impaired Listeners

    DEFF Research Database (Denmark)

    Locsei, Gusztav; Pedersen, Julie Hefting; Laugesen, Søren

    2016-01-01

    This study investigated the relationship between speech perception performance in spatially complex, lateralized listening scenarios and temporal fine-structure (TFS) coding at low frequencies. Young normal-hearing (NH) and two groups of elderly hearing-impaired (HI) listeners with mild or moderate...... hearing loss above 1.5 kHz participated in the study. Speech reception thresholds (SRTs) were estimated in the presence of either speech-shaped noise, two-, four-, or eight-talker babble played reversed, or a nonreversed two-talker masker. Target audibility was ensured by applying individualized linear...... threshold nor the interaural phase difference threshold tasks showed a correlation with the SRTs or with the amount of masking release due to binaural unmasking, respectively. The results suggest that, although HI listeners with normal hearing thresholds below 1.5 kHz experienced difficulties with speech...

  6. Precision test of many-body QED in the Be$^{+} 2p$ fine structure doublet using short-lived isotopes

    CERN Document Server

    Nörtershäuser, Wilfried; Krieger, Andreas; Pachucki, Krzysztof; Puchalski, Mariusz; Blaum, Klaus; Bissell, Mark L; Frömmgen, Nadja; Hammen, Michael; Kowalska, Magdalena; Krämer, Jörg; Kreim, Kim; Neugart, Rainer; Neyens, Gerda; Sánchez, Rodolfo; Yordanov, Deyan T

    2015-01-01

    Absolute transition frequencies of the $2s\\; ^2{\\rm S}_{1/2} \\rightarrow 2p\\;^2\\mathrm{P}_{1/2,3/2}$ transitions in Be$^+$ were measured for the isotopes $^{7,9-12}$Be. The fine structure splitting of the $2p$ state and its isotope dependence are extracted and compared to results of \\textit{ab initio} calculations using explicitly correlated basis functions, including relativistic and quantum electrodynamics effects at the order of $m \\alpha^6$ and $m \\alpha^7 \\ln \\alpha$. Accuracy has been improved in both the theory and experiment by 2 orders of magnitude, and good agreement is observed. This represents one of the most accurate tests of quantum electrodynamics for many-electron systems, being insensitive to nuclear uncertainties.

  7. Fine structure of the 1s5f and 1s5g levels of He I

    International Nuclear Information System (INIS)

    Kriescher, Y.; Hilt, O.; Oppen, G. v.

    1994-01-01

    The fine structure of the 1s 5f and 1s 5g levels of He I was measured using microwave spectroscopy. The helium atoms were excited by ion impact, and the eleven allowed 1s 5f 2S+1 F J -1s 5g 2S'+1 G J , transitions near ν∼15 GHz were induced and detected by measuring the 1s 4d-1s 2p or 1s 3d-1s 2p spectral-line intensities of the impact radiation as a function of the microwave frequency. The measured transition frequencies are in accord with theoretical values and, except for one transition frequency, with earlier experimental data. The existing discrepancy between these earlier data and theory could be solved. (orig.)

  8. Time-resolved pump and probe x-ray absorption fine structure spectroscopy at beamline P11 at PETRA III

    Energy Technology Data Exchange (ETDEWEB)

    Göries, D., E-mail: dennis.goeries@desy.de; Roedig, P.; Stübe, N.; Meyer, J.; Warmer, M.; Weckert, E.; Meents, A., E-mail: alke.meents@desy.de [DESY Photon Science, Deutsches Elektronen-Synchrotron (DESY), Notkestraße 85, 22607 Hamburg (Germany); Dicke, B.; Naumova, M.; Rübhausen, M. [Center for Free-Electron Laser Science (CFEL), Luruper Chaussee 149, 22761 Hamburg (Germany); Galler, A.; Gawelda, W.; Geßler, P.; Sotoudi Namin, H.; Beckmann, A. [European XFEL, Albert-Einstein Ring 19, 22761 Hamburg (Germany); Britz, A.; Bressler, C. [European XFEL, Albert-Einstein Ring 19, 22761 Hamburg (Germany); The Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, 22761 Hamburg (Germany); Schlie, M. [Institut für Experimentalphysik, University of Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany)

    2016-05-15

    We report about the development and implementation of a new setup for time-resolved X-ray absorption fine structure spectroscopy at beamline P11 utilizing the outstanding source properties of the low-emittance PETRA III synchrotron storage ring in Hamburg. Using a high intensity micrometer-sized X-ray beam in combination with two positional feedback systems, measurements were performed on the transition metal complex fac-Tris[2-phenylpyridinato-C2,N]iridium(III) also referred to as fac-Ir(ppy){sub 3}. This compound is a representative of the phosphorescent iridium(III) complexes, which play an important role in organic light emitting diode (OLED) technology. The experiment could directly prove the anticipated photoinduced charge transfer reaction. Our results further reveal that the temporal resolution of the experiment is limited by the PETRA III X-ray bunch length of ∼103 ps full width at half maximum (FWHM).

  9. Measurement of the electron affinity of As and the fine structure of As- using infrared threshold photodetachment spectroscopy

    International Nuclear Information System (INIS)

    Walter, C W; Gibson, N D; Field, R L III; Snedden, A P; Shapiro, J Z; Janczak, C M; Hanstorp, D

    2009-01-01

    The negative ion As - has been investigated using infrared threshold photodetachment spectroscopy. The relative cross section for neutral atom production was measured with a crossed OPO-ion beam apparatus over selected photon energy ranges between 0.63 - 0.82 eV. s-wave thresholds were observed for detachment from As - (4p 4 3 P 0,1,2 ) to the As (4p 3 4 S 3/2 ) ground state. The measurements yield preliminary values for the electron affinity of As (0.8048(2)) eV) and the fine structure intervals of As - (0.1276(2) eV for 3 P 1 - 3 P 2 and 0.1643(10) eV for 3 P 0 - 3 P 2 ). The present results substantially reduce the uncertainties in these quantities.

  10. Evidence of the nature of core-level photoemission satellites using angle-resolved photoemission extended fine structure

    Energy Technology Data Exchange (ETDEWEB)

    Moler, E.J.; Kellar, S.A.; Huff, W.R.A. [Lawrence Berkeley National Lab., CA (United States)] [and others

    1997-04-01

    The authors present a unique method of experimentally determining the angular momentum and intrinsic/extrinsic origin of core-level photoemission satellites by examining the satellite diffraction pattern in the Angle Resolved Photoemission Extended Fine Structure (ARPEFS) mode. They show for the first time that satellite peaks not associated with chemically differentiated atomic species display an ARPEFS intensity oscillation. They present ARPEFS data for the carbon 1s from ({radical}3x{radical}3)R30 CO/Cu(111) and p2mg(2xl)CO/Ni(110), nitrogen 1s from c(2x2) N{sub 2}/Ni(100), cobalt 1s from p(1x1)Co/Cu(100), and nickel 3p from clean nickel (111). The satellite peaks and tails of the Doniach-Sunjic line shapes in all cases exhibit ARPEFS curves which indicate an angular momentum identical to the main peak and are of an intrinsic nature.

  11. Formation Mechanism of Ge Nanocrystals Embedded in SiO2 Studied by Fluorescence X-Ray Absorption Fine Structure

    International Nuclear Information System (INIS)

    Yan Wensheng; Li Zhongrui; Sun Zhihu; Wei Shiqiang; Kolobov, A. V.

    2007-01-01

    The formation mechanism of Ge nanocrystals for Ge (60 mol%) embedded in a SiO2 matrix grown on Si(001) and quartz-glass substrates was studied by fluorescence x-ray absorption fine structure (XAFS). It was found that the formation of Ge nanocrystals strongly depends on the properties of the substrate materials. In the as-prepared samples, Ge atoms exist in amorphous Ge and GeO2 phases. At the annealing temperature of 1073 K, on the quartz-glass substrate, Ge nanocrystals are only formed predominantly from the amorphous Ge phase in the as-prepared sample. However, on the Si(100) substrate the Ge nanocrystals are generated partly from amorphous Ge, and partly from GeO2 phases through the permutation reaction with Si substrate. Quantitative analysis revealed that about 10% of GeO2 in as-prepared sample permutated with Si in the wafer and formed Ge nanocrystals

  12. Lattice distortions in TlInSe{sub 2} thermoelectric material studied by X-ray absorption fine structure

    Energy Technology Data Exchange (ETDEWEB)

    Hosokawa, Shinya; Stellhorn, Jens Ruediger [Department of Physics, Kumamoto University, Kumamoto (Japan); Ikemoto, Hiroyuki [Department of Physics, University of Toyama, Toyama (Japan); Mimura, Kojiro [Department of Mathematical Sciences, Graduate School of Engineering, Osaka Prefecture University, Sakai (Japan); Wakita, Kazuki [Faculty of Engineering, Chiba Institute of Technology, Narashino (Japan); Mamedov, Nazim [Institute of Physics, Azerbaijan National Academy of Sciences, Baku (Azerbaijan)

    2018-01-15

    Tl L{sub II} and In K X-ray absorption fine structure (XAFS) measurements were performed on a TlInSe{sub 2} thermoelectric material in the temperature range of 25-300 K including the incommensurate-commensurate phase transition temperature of about 135 K. Most of the bond lengths obtained from the present XAFS measurements are in good agreement with existing X-ray diffraction data at room temperature, while only the Tl-Tl correlation shows inconsistent values indicating the commensurate properties of the Tl chains expected from the thermodynamic properties. The present XAFS data clearly support positional fluctuations of the Tl atoms found in three-dimensional atomic images reconstructed from X-ray fluorescence holography. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Fine Structure in Proton Emission from the Deformed 141g.sHo and 141mHo

    International Nuclear Information System (INIS)

    Karny, M.; Rykaczewski, Krzysztof Piotr; Grzywacz, R.; Batchelder, J.C.; Bingham, C.R.; Goodin, C. T.; Gross, Carl J.; Hamilton, J.H.; Korgul, A.; Krolas, W.; Liddick, S. N.; Li, K.; Maier, Karl; Mazzocchi, C.; Piechaczek, A.; Shapira, Dan; Simpson, D.; Tantawy, M.N.; Winger, J.A.; Yu, Chang-Hong; Zganjar, E. F.

    2007-01-01

    Fine structure in proton emission from the deformed states 141g.s Ho (T 1/2 = 4.1 ms) and 141 mHo (T 1/2 = 7.4 (micro)s) has been discovered at Oak Ridge by detecting fusion evaporation residues with the Recoil Mass Spectrometer, Si-detectors and digital signal processing electronics. The branching ratios to the first 2 + excited state in 140 Dy were measured to be I p g.s. (2 + ) = 0.9±0.1% and I p m (2 + ) = 1.7±0.5%. A comparison of the available calculations to the experimental values calls for further development of the theoretical models

  14. Evidence of the nature of core-level photoemission satellites using angle-resolved photoemission extended fine structure

    International Nuclear Information System (INIS)

    Moler, E.J.; Kellar, S.A.; Huff, W.R.A.

    1997-01-01

    The authors present a unique method of experimentally determining the angular momentum and intrinsic/extrinsic origin of core-level photoemission satellites by examining the satellite diffraction pattern in the Angle Resolved Photoemission Extended Fine Structure (ARPEFS) mode. They show for the first time that satellite peaks not associated with chemically differentiated atomic species display an ARPEFS intensity oscillation. They present ARPEFS data for the carbon 1s from (√3x√3)R30 CO/Cu(111) and p2mg(2xl)CO/Ni(110), nitrogen 1s from c(2x2) N 2 /Ni(100), cobalt 1s from p(1x1)Co/Cu(100), and nickel 3p from clean nickel (111). The satellite peaks and tails of the Doniach-Sunjic line shapes in all cases exhibit ARPEFS curves which indicate an angular momentum identical to the main peak and are of an intrinsic nature

  15. Role of short-time acoustic temporal fine structure cues in sentence recognition for normal-hearing listeners.

    Science.gov (United States)

    Hou, Limin; Xu, Li

    2018-02-01

    Short-time processing was employed to manipulate the amplitude, bandwidth, and temporal fine structure (TFS) in sentences. Fifty-two native-English-speaking, normal-hearing listeners participated in four sentence-recognition experiments. Results showed that recovered envelope (E) played an important role in speech recognition when the bandwidth was > 1 equivalent rectangular bandwidth. Removing TFS drastically reduced sentence recognition. Preserving TFS greatly improved sentence recognition when amplitude information was available at a rate ≥ 10 Hz (i.e., time segment ≤ 100 ms). Therefore, the short-time TFS facilitates speech perception together with the recovered E and works with the coarse amplitude cues to provide useful information for speech recognition.

  16. Extended x-ray absorption fine structure studies of amorphous and crystalline Si-Ge alloys with synchrotron radiation

    International Nuclear Information System (INIS)

    Kajiyama, Hiroshi

    1988-01-01

    Extended X-ray absorption fine structure (EXAFS) is a powerful probe to study the local structure around the atom of a specific element. In conventional EXAFS analysis, it has been known that reliable structures are obtained with the different values of absorption edge energy for different neighboring atoms. It is shown in this study that the Ge-K edge EXAFS resulting from the Ge-Ge and Ge-Si bonds in hydrogenated amorphous Si-Ge alloys was able to be excellently explained by a unique absorption edge energy value, provided that a newly developed formula based on the spherical wave function of photoelectrons is used. The microscopic structures of hydrogenated amorphous Si-Ge alloys and crystalline Si-Ge alloys have been determined using the EXAFS method. The lengths of Ge-Ge and Ge-Si bonds were constant throughout their entire composition range, and it was found that the length of Ge-Si bond was close to the average value of the bond lengths of both Ge and Si crystals. In crystalline Si-Ge alloys, it has been shown that the bonds relaxed completely, while the lattice constant varied monotonously with the composition. (Kako, I.)

  17. Evaluation of physical structural features on influencing enzymatic hydrolysis efficiency of micronized wood

    Science.gov (United States)

    Jinxue Jiang; Jinwu Wang; Xiao Zhang; Michael Wolcott

    2016-01-01

    Enzymatic hydrolysis of lignocellulosic biomass is highly dependent on the changes in structural features after pretreatment. Mechanical milling pretreatment is an effective approach to alter the physical structure of biomass and thus improve enzymatic hydrolysis. This study examined the influence of structural characteristics on the enzymatic hydrolysis of micronized...

  18. Determining the Velocity Fine Structure by a Laser Anemometer in VAD operation

    DEFF Research Database (Denmark)

    Kristensen, Leif; Kirkegaard, Peter; Mikkelsen, Torben

    . Then it is necessary to “create” a mean wind by turning the laser beam. Since the instrument is not moved the beam will describe a cone which could be a VAD-scanning. In any case the measured velocity components will not be parallel and this implies that the measured structure function will contain a term which...... is proportional to the total variance. The theoretical expression for the line-filtered structure function is derived in two equivalent ways, one in physical space and one in wave-number space, of which the last can be reliably evaluated by numerical integration. Also a practical approximate equation, derived...

  19. The Fine Art in Structure of John Fowles’ Novel “The French Lieutenant’s Woman”

    Directory of Open Access Journals (Sweden)

    Oksana Levytska

    2013-12-01

    Full Text Available The article deals with the role of descriptive context in the structure of John Fowles’ novel “The French Lieutenant’s Woman”. Based on the intermedial analysis there was analyzed the semiotics of fine art in the novel, in particular an appeal to the Pre-Raphaelite art and the Renaissance painting. It was found that John Fowles’ works tend to use the poetics of different kinds of arts: the writer appeals to painting, operates its sign system, recodes signs of visual art by the language of a literary text, expanding the context of its understanding, interpretation and reception. There were studied intermedial connections of the novel with other works of arts. It was found that in the writer’s novels and stories were presented the most clearly visual arts in terms of their classification for the form of sensory perception. Among the arts in relation to time and space are dominated spatial arts: painting, sculpture, architecture, photography, decorative arts. The study focuses on the fine art, especially painting. The descriptive context is multivariation and multifunctional, it has manifestations on a level with the intermedial citation of painting, ekphrasis in landscape or portrait sketches, paintings of visualizing of characters’ imagination, allusions to works of art, etc., explicitly and implicitly represented in the texts. Intermedial analysis allows us to see the relationship of John Fowles’ novel with the Pre-Raphaelite art. In the character context the descriptive component increases literary, cultural and historical contextual characteristics. Introduced in the structure of a literary text the descriptive context on the semiotic level forms the axiological context. The system of ethical and aesthetic values of different cultural eras is extrapolated through the artistic context. So, the article studies the intermedial novel connections with other works of art. The descriptive context of the novel is manifested at

  20. Collisional radiative model for Ar-O2 mixture plasma with fully relativistic fine structure cross sections

    Science.gov (United States)

    Priti, Gangwar, Reetesh Kumar; Srivastava, Rajesh

    2018-04-01

    A collisional radiative (C-R) model has been developed to diagnose the rf generated Ar-O2 (0%-5%) mixture plasma at low temperatures. Since in such plasmas the most dominant process is an electron impact excitation process, we considered several electron impact fine structure transitions in an argon atom from its ground as well as excited states. The cross-sections for these transitions have been obtained using the reliable fully relativistic distorted wave theory. Processes which account for the coupling of argon with the oxygen molecules have been further added to the model. We couple our model to the optical spectroscopic measurements reported by Jogi et al. [J. Phys. D: Appl. Phys. 47, 335206 (2014)]. The plasma parameters, viz. the electron density (ne) and the electron temperature (Te) as a function of O2 concentration have been obtained using thirteen intense emission lines out of 3p54p → 3p54s transitions observed in their spectroscopic measurements. It is found that as the content of O2 in Ar increases from 0%-5%, Te increases in the range 0.85-1.7 eV, while the electron density decreases from 2.76 × 1012-2.34 × 1011 cm-3. The Ar-3p54s (1si) fine-structure level populations at our extracted plasma parameters are found to be in very good agreement with those obtained from the measurements. Furthermore, we have estimated the individual contributions coming from the ground state, 1si manifolds and cascade contributions to the population of the radiating Ar-3p54p (2pi) states as a function of a trace amount of O2. Such information is very useful to understand the importance of various processes occurring in the plasma.

  1. Fine structure of excitons and electron-hole exchange energy in polymorphic CsPbBr3 single nanocrystals.

    Science.gov (United States)

    Ramade, Julien; Andriambariarijaona, Léon Marcel; Steinmetz, Violette; Goubet, Nicolas; Legrand, Laurent; Barisien, Thierry; Bernardot, Frédérick; Testelin, Christophe; Lhuillier, Emmanuel; Bramati, Alberto; Chamarro, Maria

    2018-04-05

    All inorganic CsPbX3 (X = Cl, Br, I) nanocrystals (NCs) belong to the novel class of confined metal-halide perovskites which are currently arousing enthusiasm and stimulating huge activity across several fields of optoelectronics due to outstanding properties. A deep knowledge of the band-edge excitonic properties of these materials is thus crucial to further optimize their performances. Here, high-resolution photoluminescence (PL) spectroscopy of single bromide-based NCs reveals the exciton fine structure in the form of sharp peaks that are linearly polarized and grouped in doublets or triplets, which directly mirror the adopted crystalline structure, tetragonal (D4h symmetry) or orthorhombic (D2h symmetry). Intelligible equations are found that show how the fundamental parameters (spin-orbit coupling, ΔSO, crystal field term, T, and electron-hole exchange energy, J) rule the energy spacings in doublets and triplets. From experimental data, fine estimations of each parameter are obtained. The analysis of the absorption spectra of an ensemble of NCs with a "quasi-bulk" behavior leads to ΔSO = 1.20 ± 0.06 eV and T = -0.34 ± 0.05 eV in CsPbBr3. The study of individual luminescence responses of NCs having sizes comparable to the exciton Bohr diameter, 7 nm, allows us to estimate the value of J to be around ≈3 meV in both tetragonal and orthorhombic phases. This value is already enhanced by confinement.

  2. Fine-scale genetic structure and social organization in female white-tailed deer

    Science.gov (United States)

    Christopher E. Comer; John C. Kilgo; Gino J. D' Angelo; Travis C. Glenn; Karl V. Miller

    2005-01-01

    Social behavior of white-tailed deer (Odocoileus virginianus) can have important management implications. The formation of matrilineal social groups among female deer has been documented and management strategies have been proposed based on this well-developed social structure. Using radiocollared (n = 17) and hunter or vehicle-killed (n = 21) does, we examined spatial...

  3. Fine structure in the inter-critical heat-affected zone of HQ130 super ...

    Indian Academy of Sciences (India)

    Unknown

    †Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, ... The microstructure in the inter-critical heat-affected zone (ICHAZ) of HQ130 steel, has been .... Ac3. The microhardness was measured by using the.

  4. Fine Structure Study of the Plasma Coatings B4C-Ni-P

    Science.gov (United States)

    Kornienko, E. E.; Bezrukova, V. A.; Kuz'min, V. I.; Lozhkin, V. S.; Tutunkova, M. K.

    2017-12-01

    The article considers structure of coatings formed of the B4C-Ni-P powder. The coatings were deposited using air-plasma spraying with the unit for annular injection of powder. The pipes from steel 20 (0.2 % C) were used as a substrate. The structure and phase composition of the coatings were studied by optical microscopy, scanning electron microscopy, transmission electron microscopy and X-ray diffractometry. It is shown that high-density composite coatings consisting of boron carbide particles distributed in the nickel boride metal matrix are formed using air-plasma spraying. The areas with round inclusions characterized by the increased amount of nickel, phosphorus and boron are located around the boron carbide particles. Boron oxides and nickel oxides are also present in the coatings. Thin interlayers with amorphous-crystalline structure are formed around the boron carbide particles. The thickness of these interlayers does not exceed 1 μm. The metal matrix material represents areas with nanocrystalline structure and columnar crystals.

  5. Number Concentrations and Modal Structure of Indoor/Outdoor Fine Particles in Four European Cities.

    Czech Academy of Sciences Publication Activity Database

    Lazaridis, M.; Eleftheriadis, K.; Ždímal, Vladimír; Schwarz, Jaroslav; Wagner, Zdeněk; Ondráček, Jakub; Drossinos, Y.; Glytsos, T.; Vratolis, S.; Torseth, K.; Moravec, Pavel; Hussein, T.; Smolík, Jiří

    2017-01-01

    Roč. 17, č. 1 (2017), s. 131-146 ISSN 1680-8584 EU Projects: European Commission(XE) 315760 - HEXACOMM Institutional support: RVO:67985858 Keywords : indoor/outdoor aerosol * I/O ratio * modal structure Subject RIV: DG - Athmosphere Sciences, Meteorology OBOR OECD: Meteorology and atmospheric sciences Impact factor: 2.606, year: 2016

  6. Fine-scale genetic structure and social organization in female white-tailed deer.

    Energy Technology Data Exchange (ETDEWEB)

    Comer, Christopher E.; Kilgo, John C.; D' Angelo, Gino J.; Glenn, Travis C.; Miller, Karl V.

    2005-07-01

    Abstract: Social behavior of white-tailed deer (Odocoileus virginianus) can have important management implications. The formation of matrilineal social groups among female deer has been documented and management strategies have been proposed based on this well-developed social structure. Using radiocollared (n = 17) and hunter or vehicle-killed (n = 21) does, we examined spatial and genetic structure in white-tailed deer on a 7,000-ha portion of the Savannah River Site in the upper Coastal Plain of South Carolina, USA. We used 14 microsatellite DNA loci to calculate pairwise relatedness among individual deer and to assign doe pairs to putative relationship categories. Linear distance and genetic relatedness were weakly correlated (r = –0.08, P = 0.058). Relationship categories differed in mean spatial distance, but only 60% of first-degree-related doe pairs (full sibling or mother–offspring pairs) and 38% of second-degree-related doe pairs (half sibling, grandmother–granddaughter pairs) were members of the same social group based on spatial association. Heavy hunting pressure in this population has created a young age structure among does, where the average age is <2.5 years, and <4% of does are >4.5 years old. This—combined with potentially elevated dispersal among young does—could limit the formation of persistent, cohesive social groups. Our results question the universal applicability of recently proposed models of spatial and genetic structuring in white-tailed deer, particularly in areas with differing harvest histories.

  7. Fine structure of spectral properties for random correlation matrices: an application to financial markets.

    Science.gov (United States)

    Livan, Giacomo; Alfarano, Simone; Scalas, Enrico

    2011-07-01

    We study some properties of eigenvalue spectra of financial correlation matrices. In particular, we investigate the nature of the large eigenvalue bulks which are observed empirically, and which have often been regarded as a consequence of the supposedly large amount of noise contained in financial data. We challenge this common knowledge by acting on the empirical correlation matrices of two data sets with a filtering procedure which highlights some of the cluster structure they contain, and we analyze the consequences of such filtering on eigenvalue spectra. We show that empirically observed eigenvalue bulks emerge as superpositions of smaller structures, which in turn emerge as a consequence of cross correlations between stocks. We interpret and corroborate these findings in terms of factor models, and we compare empirical spectra to those predicted by random matrix theory for such models.

  8. Fine structure of spectral properties for random correlation matrices: An application to financial markets

    Science.gov (United States)

    Livan, Giacomo; Alfarano, Simone; Scalas, Enrico

    2011-07-01

    We study some properties of eigenvalue spectra of financial correlation matrices. In particular, we investigate the nature of the large eigenvalue bulks which are observed empirically, and which have often been regarded as a consequence of the supposedly large amount of noise contained in financial data. We challenge this common knowledge by acting on the empirical correlation matrices of two data sets with a filtering procedure which highlights some of the cluster structure they contain, and we analyze the consequences of such filtering on eigenvalue spectra. We show that empirically observed eigenvalue bulks emerge as superpositions of smaller structures, which in turn emerge as a consequence of cross correlations between stocks. We interpret and corroborate these findings in terms of factor models, and we compare empirical spectra to those predicted by random matrix theory for such models.

  9. An optimized ultra-fine energy group structure for neutron transport calculations

    International Nuclear Information System (INIS)

    Huria, Harish; Ouisloumen, Mohamed

    2008-01-01

    This paper describes an optimized energy group structure that was developed for neutron transport calculations in lattices using the Westinghouse lattice physics code PARAGON. The currently used 70-energy group structure results in significant discrepancies when the predictions are compared with those from the continuous energy Monte Carlo methods. The main source of the differences is the approximations employed in the resonance self-shielding methodology. This, in turn, leads to ambiguous adjustments in the resonance range cross-sections. The main goal of developing this group structure was to bypass the self-shielding methodology altogether thereby reducing the neutronic calculation errors. The proposed optimized energy mesh has 6064 points with 5877 points spanning the resonance range. The group boundaries in the resonance range were selected so that the micro group cross-sections matched reasonably well with those derived from reaction tallies of MCNP for a number of resonance absorbers of interest in reactor lattices. At the same time, however, the fast and thermal energy range boundaries were also adjusted to match the MCNP reaction rates in the relevant ranges. The resulting multi-group library was used to obtain eigenvalues for a wide variety of reactor lattice numerical benchmarks and also the Doppler reactivity defect benchmarks to establish its adequacy. (authors)

  10. The research of structural features of astralens - nanodimensional carbon particles of fulleroid type

    International Nuclear Information System (INIS)

    Ponomarev, A.N.; Nikitin, V.A.; Rybalko, V.V.

    2006-01-01

    The article is focused on the research of structural features of astralens - nanodimensional carbonic particles of fulleroid type. Astralens are perspective nanomodificators of properties of materials of different types. The potentials os astralens as modificators depend on their characteristic structural features, and in the first place, on the distribution of nanoparticles by sizes. The typical dimensions of astralens are determined to be within the range of 15-75 nm [ru

  11. Effect of electron correlations and Breit interactions on ground-state fine-structures along the nitrogen-like isoelectronic sequence

    International Nuclear Information System (INIS)

    Wang Xiaolu; Lu Wenlai; Gao Xiang; Li Jiaming

    2009-01-01

    The accurate atomic data of nitrogen and nitrogen-like ions have an importance role in fusion plasma studies and astrophysics studies. The precise calculation of fine-structures is required to obtain such atomic data. Along the whole nitrogen isoelectronic sequence, the contributions of the electron correlations, the Breit interactions and the quantum electrodynamics corrections on the ground-state fine-structures are elucidated. When Z is low, the electron correlations are important, and the Breit interactions, which cannot be neglected cause interesting anomalous fine-structure splittings. When Z is high, the electron correlations are less important, and the Breit interactions are important in addition to spin-orbit interactions for precise calculations. (authors)

  12. Microsatellite variation suggests a recent fine-scale population structure of Drosophila sechellia, a species endemic of the Seychelles archipelago.

    Science.gov (United States)

    Legrand, Delphine; Vautrin, Dominique; Lachaise, Daniel; Cariou, Marie-Louise

    2011-07-01

    Drosophila sechellia is closely related to the cosmopolitan and widespread model species, D. simulans. This species, endemic to the Seychelles archipelago, is specialized on the fruits of Morinda citrifolia, and harbours the lowest overall genetic diversity compared to other species of Drosophila. This low diversity is associated with a small population size. In addition, no obvious population structure has been evidenced so far across islands of the Seychelles archipelago. Here, a microsatellite panel of 17 loci in ten populations from nine islands of the Seychelles was used to assess the effect of the D. sechellia's fragmented distribution on the fine-scale population genetic structure, the migration pattern, as well as on the demography of the species. Contrary to previous results, also based on microsatellites, no evidence for population contraction in D. sechellia was found. The results confirm previous studies based on gene sequence polymorphism that showed a long-term stable population size for this species. Interestingly, a pattern of Isolation By Distance which had not been described yet in D. sechellia was found, with evidence of first-generation migrants between some neighbouring islands. Bayesian structuring algorithm results were consistent with a split of D. sechellia into two main groups of populations: Silhouette/Mahé versus all the other islands. Thus, microsatellites suggest that variability in D. sechellia is most likely explained by local genetic exchanges between neighbouring islands that have recently resulted in slight differentiation of the two largest island populations from all the others.

  13. Fine-scale population structure of Malays in Peninsular Malaysia and Singapore and implications for association studies.

    Science.gov (United States)

    Hoh, Boon-Peng; Deng, Lian; Julia-Ashazila, Mat Jusoh; Zuraihan, Zakaria; Nur-Hasnah, Ma'amor; Nur-Shafawati, Ab Rajab; Hatin, Wan Isa; Endom, Ismail; Zilfalil, Bin Alwi; Khalid, Yusoff; Xu, Shuhua

    2015-07-22

    Fine scale population structure of Malays - the major population in Malaysia, has not been well studied. This may have important implications for both evolutionary and medical studies. Here, we investigated the population sub-structure of Malay involving 431 samples collected from all states from peninsular Malaysia and Singapore. We identified two major clusters of individuals corresponding to the north and south peninsular Malaysia. On an even finer scale, the genetic coordinates of the geographical Malay populations are in correlation with the latitudes (R(2) = 0.3925; P = 0.029). This finding is further supported by the pairwise FST of Malay sub-populations, of which the north and south regions showed the highest differentiation (FST [North-south] = 0.0011). The collective findings therefore suggest that population sub-structure of Malays are more heterogenous than previously expected even within a small geographical region, possibly due to factors like different genetic origins, geographical isolation, could result in spurious association as demonstrated in our analysis. We suggest that cautions should be taken during the stage of study design or interpreting the association signals in disease mapping studies which are expected to be conducted in Malay population in the near future.

  14. Metal induced crystallization of amorphous silicon thin films studied by x-ray absorption fine structure spectroscopy

    International Nuclear Information System (INIS)

    Naidu, K Lakshun; Mohiddon, Md Ahamad; Dalba, G; Krishna, M Ghanashyam; Rocca, F

    2013-01-01

    The role of thin metallic layer (Chromium or Nickel) in the crystallization of a-Si film has been studied using X-ray absorption fine structure spectroscopy (XAFS). The films were grown at different substrate temperatures in two different geometrical structures : (a) a 200 nm metal layer (Cr or Ni) was deposited on fused silica (FS) followed by 400 nm of a-Si and (b) the 400 nm a-Si layer was deposited on FS followed by 200 nm of metal layer. XAFS measurements at Cr K-edge and Ni K-edge were done at BM08 – GILDA beamline of the European Synchrotron Research Facility (ESRF, Grenoble, F) in fluorescence mode. To understand the evolution of the local structure of Cr/Ni diffusing from bottom to top and from top to bottom, total reflection and higher incidence angles were employed. The relative content of metal, metal oxide and metal silicides compounds on the upper surface and/or in the bulk of different films has been evaluated as a function of thermal treatment.

  15. Fine structure of the tapetum lucidum of the paca Cuniculus paca.

    Science.gov (United States)

    Braekevelt, C R

    1993-01-01

    The tapetum lucidum of the paca or spotted cavy (Cuniculus paca) has been studied by light and electron microscopy. The reflective layer in this species is a tapetum cellulosum situated in the choroid of the superior fundus. Posteriorly, the tapetum is composed of several layers of ovoid to flattened cells while peripherally the tapetum gradually thins down and disappears. Within the tapetal cells most cell organelles are located near the nucleus. The dominant feature of these cells is, however, a large accumulation of electron-dense rodlets which show a variety of sizes, shapes and orientations. These rodlets are the reflective material of the tapetum, and energy dispersive studies indicate that they are rich in sulphur. The diameter and spacing of these irregular rodlets is too varied to be consistent with the principles of constructive interference, and the tapetum in the paca is probably capable of only diffuse reflectance. The retinal epithelium over the tapetum is nonpigmented while in non-tapetal locations it is normally pigmented.

  16. Coordination Analysis Using Global Structural Constraints and Alignment-based Local Features

    Science.gov (United States)

    Hara, Kazuo; Shimbo, Masashi; Matsumoto, Yuji

    We propose a hybrid approach to coordinate structure analysis that combines a simple grammar to ensure consistent global structure of coordinations in a sentence, and features based on sequence alignment to capture local symmetry of conjuncts. The weight of the alignment-based features, which in turn determines the score of coordinate structures, is optimized by perceptron training on a given corpus. A bottom-up chart parsing algorithm efficiently finds the best scoring structure, taking both nested or non-overlapping flat coordinations into account. We demonstrate that our approach outperforms existing parsers in coordination scope detection on the Genia corpus.

  17. Structural features that predict real-value fluctuations of globular proteins.

    Science.gov (United States)

    Jamroz, Michal; Kolinski, Andrzej; Kihara, Daisuke

    2012-05-01

    It is crucial to consider dynamics for understanding the biological function of proteins. We used a large number of molecular dynamics (MD) trajectories of nonhomologous proteins as references and examined static structural features of proteins that are most relevant to fluctuations. We examined correlation of individual structural features with fluctuations and further investigated effective combinations of features for predicting the real value of residue fluctuations using the support vector regression (SVR). It was found that some structural features have higher correlation than crystallographic B-factors with fluctuations observed in MD trajectories. Moreover, SVR that uses combinations of static structural features showed accurate prediction of fluctuations with an average Pearson's correlation coefficient of 0.669 and a root mean square error of 1.04 Å. This correlation coefficient is higher than the one observed in predictions by the Gaussian network model (GNM). An advantage of the developed method over the GNMs is that the former predicts the real value of fluctuation. The results help improve our understanding of relationships between protein structure and fluctuation. Furthermore, the developed method provides a convienient practial way to predict fluctuations of proteins using easily computed static structural features of proteins. Copyright © 2012 Wiley Periodicals, Inc.

  18. Mechanism of the formation of silver-sheathed HTSC ceramics and its fine structure

    International Nuclear Information System (INIS)

    Blinova, Yu.V.; Sudareva, S.V.; Krinitsina, T.P.; Romanov, E.P.; Akimov, I.I.

    2005-01-01

    Electron microscopical data are reported which point to the fact that two mechanisms of formation of main superconducting phase 2223 in Bi,Pb-2223/Ag exist: liquid phase mechanism and solid-phase one. Along crystallite boundaries the spherical outlined by Ag interlayers are observed. These are former eutectic liquid droplets of ∼ 2223 composition from which Ag is liberated on solidification. In the initial stage of phase formation inside of a 2212 phase the platelets of phase 2223 are found out with the same orientation as the matrix (a solid-phase mechanism). Certain relationships of structure to superconducting properties are shown [ru

  19. Extended fine structure in the K-shell photoionization spectrum of Br2

    International Nuclear Information System (INIS)

    Dill, D.; Dehmer, J.L.

    1975-01-01

    The multiple-scattering approach to molecular wavefunctions in the electronic continuum has been used recently to elucidate the structure of the shape resonance just above threshold in the K-shell photoionization spectrum of N 2 . A similar calculation for Br 2 has yielded significantly different results, i.e., there is no shape resonance; appearing instead is a single resonance in the discrete spectrum, and the photoionization spectrum is found to oscillate with appreciable amplitude throughout the spectral range investigated, from threshold to 60 Ry

  20. Cartilage of the Intervertebral Disc Eng-Plate, A Histological, Histochemical, Fine Structure Study.

    Science.gov (United States)

    1982-08-01

    degeneration (Nachemson et al., 1970). These and related studies consider the end-plates to be composed of hyaline cartilage and thus homologues of articular...results of this study in rhesus indicate, that while present, the cartilage of the end-plate is quite different in structure and presumably...HZSTOLO6ZCAL,-ETCfU) I AUG 82 N 5 NUSSBAUM IUNCLASSIFDATRL8R-1222NL.rnximommmB~iIEND2 AFAMRL-TR-81 - 122 " CARTILAGE OF THE INTERVERTEBRAL DISC END-PLATE A

  1. Fine structures on zero-field steps in low-loss Josephson tunnel junctions

    DEFF Research Database (Denmark)

    Monaco, Roberto; Barbara, Paola; Mygind, Jesper

    1993-01-01

    The first zero-field step in the current-voltage characteristic of intermediate-length, high-quality, low-loss Nb/Al-AlOx/Nb Josephson tunnel junctions has been carefully investigated as a function of temperature. When decreasing the temperature, a number of structures develop in the form...... of regular and slightly hysteretic steps whose voltage position depends on the junction temperature and length. This phenomenon is interesting for the study of nonlinear dynamics and for application of long Josephson tunnel junctions as microwave and millimeter-wavelength oscillators....

  2. Fine structure of the free-living parakeet pineal in relation to the breeding cycle.

    Science.gov (United States)

    Prasadan, T N; Kotak, V C

    1993-10-01

    Seasonal changes in the ultrastructure of the free-living Rose-Ringed Parakeet Psittacula krameri pineal were examined in relation to the sub-tropical environment and seasonal reproduction. Dark and light pinealocytes of the presumptive neuroendocrine cell line predominated, while supporting cells, ependymal cells, myelinated and non-myelinated nerve fibers with nerve endings, and regressed photoreceptor elements were also observed. Unlike in pineals of many animals, particularly mammals, the presence of dense-core vesicles (DCVs) with varying core density, and absence of clear vesicles and vacuoles with flocullent material, indicate the involvement of DCVs in the synthesis and secretion of pineals principle/s. In November (pre-breeding) when the day length registered a drop to LD 10:14, pinealocytes showed significantly decreased and smaller DCVs and mitochondria, nuclei with heterochromatin, and greater distribution of glycogen and lipid droplets, all indicating low pineal metabolic activity. During the shortest day regime from December to March, when the birds peaked breeding, the number and size of DCVs and mitochondria increased, and Golgi body-endoplasmic reticulum-lysosome complex (GERL) was very well defined. Images of DCVs suggested possible secretion of pineal principle/s by dissolution, and exocytosis. Coincidence of these features with peak gonadotrophic (circulating LH) and spermatogenic and testicular endocrine activity described previously suggested an active turnover of pineal products during this short day length regime when parakeets breed. In contrast, during the post-breeding season (April onwards), when the day-length increased to LD 13:11 and hypophyseal-gonadal function was down, nuclei and RER continued to show active profile, the Golgi body and associated complex were moderately seen, and the DCVs and mitochondria were significantly smaller and lesser. It is therefore probable that the pineal is an important relay to translate cues related

  3. Evidence of novel fine-scale structural variation at autism spectrum disorder candidate loci

    Directory of Open Access Journals (Sweden)

    Hedges Dale J

    2012-04-01

    Full Text Available Abstract Background Autism spectrum disorders (ASD represent a group of neurodevelopmental disorders characterized by a core set of social-communicative and behavioral impairments. Gamma-aminobutyric acid (GABA is the major inhibitory neurotransmitter in the brain, acting primarily via the GABA receptors (GABR. Multiple lines of evidence, including altered GABA and GABA receptor expression in autistic patients, indicate that the GABAergic system may be involved in the etiology of autism. Methods As copy number variations (CNVs, particularly rare and de novo CNVs, have now been implicated in ASD risk, we examined the GABA receptors and genes in related pathways for structural variation that may be associated with autism. We further extended our candidate gene set to include 19 genes and regions that had either been directly implicated in the autism literature or were directly related (via function or ancestry to these primary candidates. For the high resolution CNV screen we employed custom-designed 244 k comparative genomic hybridization (CGH arrays. Collectively, our probes spanned a total of 11 Mb of GABA-related and additional candidate regions with a density of approximately one probe every 200 nucleotides, allowing a theoretical resolution for detection of CNVs of approximately 1 kb or greater on average. One hundred and sixty-eight autism cases and 149 control individuals were screened for structural variants. Prioritized CNV events were confirmed using quantitative PCR, and confirmed loci were evaluated on an additional set of 170 cases and 170 control individuals that were not included in the original discovery set. Loci that remained interesting were subsequently screened via quantitative PCR on an additional set of 755 cases and 1,809 unaffected family members. Results Results include rare deletions in autistic individuals at JAKMIP1, NRXN1, Neuroligin4Y, OXTR, and ABAT. Common insertion/deletion polymorphisms were detected at several

  4. Changes to the structure of blood clots formed in the presence of fine particulate matter

    International Nuclear Information System (INIS)

    Metassan, Sofian; Routledge, Michael N; Ariens, Robert A S; Scott, D Julian

    2009-01-01

    Both long-term and short-term exposure (one to two hours) to particulate matter are associated with morbidity and mortality caused by cardiovascular diseases. The underlying mechanisms leading to cardiovascular events are unclear, however, changes to blood coagulability upon exposure to ultrafine particulate matter (UFPM, the smallest of which can enter the circulation) is a plausible mechanism. Objectives: This study aims to investigate the direct effects of particulate matter on fibrin polymerization, lateral aggregation and the formation of fibrin network structure. Methods: Standard Urban Particulate Matter (PM) was suspended in Tris buffer centrifuged and filtered with <200nm filter to obtain ultrafine PM or their water-soluble components. Purified normal fibrinogen was made to clot by adding thrombin and calcium chloride in the presence of varying concentrations of PM. Permeation properties (Darcy constant [Ks]) and turbidity of clots were measured to investigate the effects on flow-rate, pore size, and fibrin polymerization. In addition, confocal microscopy was performed to study detailed clot structure. Results: Total PM increased the Ks of clots in a dose dependant manner (Ks = 4.4, 6.9 and 13.2 x 10-9 cm2 for 0, 50 and 100 |ag/ml total PM concentrations, respectively). Filtered PM also produced a significant increase in Ks at PM concentration of 17 |ag/ml. Final turbidity measurements at 20min were obtained for varying concentrations of PM. Maximum optical density (OD) for 1 mg/ml fibrinogen at 0, 50, 100 and 200 |ag/ml total PM concentrations were 0.39, 0.42, 0.45 and 0.46, respectively. The maximum OD for 0, 17, 34 and 68 |ag/ml filtered PM concentrations were 0.39, 0.42 0.47 and 0.51, respectively, suggesting an increase in fibre diameter with increasing particulate concentration. The lag phase was significantly shorter and the rate of polymerisation was significantly faster in the presence of 68 |ag/ml filtered PM. Confocal microscopy results showed

  5. Coronal Fine Structure in Dynamic Events Observed by Hi-C

    Science.gov (United States)

    Winebarger, Amy; Schuler, Timothy

    2013-01-01

    The High-Resolution Coronal Imager (Hi-C) flew aboard a NASA sounding rocket on 2012 July 11 and captured roughly 345 s of high spatial and temporal resolution images of the solar corona in a narrowband 193 Angstrom channel. We have analyzed the fluctuations in intensity of Active Region 11520. We selected events based on a lifetime greater than 11 s (two Hi-C frames) and intensities greater than a threshold determined from the photon and readout noise. We compare the Hi-C events with those determined from AIA. We find that HI-C detects shorter and smaller events than AIA. We also find that the intensity increase in the Hi-C events is approx. 3 times greater than the intensity increase in the AIA events we conclude the events are related to linear sub-structure that is unresolved by AIA

  6. An investigation of fine structure of the bursts produced by muons in the rock

    International Nuclear Information System (INIS)

    Higashi, S.; Kajino, F.; Nakashita, M.; Osaki, S.; Takahashi, T.; Yamamoto, S.

    1981-01-01

    Two dimensional lateral structures of the shower particles in the bursts, produced by high energy muons in the rock, have been studied by using the four layers of proportional counters. The mean lateral distributions measured fit well to those of Monte Carlo simulation of electromagnetic cascade showers. The distributions of reduced chi 2 which correspond to the fluctuations of each lateral distribution from the mean value show that the rates of the events giving high chi 2 for the data are somewhat greater than those expected from the simulation. The rates of these excesses to the total events are about 10% in the burst size range 578 - 8277 particles which are induced by the muons in the energy range 714 - 9900 GeV. These excesses could be explained by the contributions from the muon nuclear interactions in the rock

  7. Structural evolution and drawability in laser dieless drawing of fine nickel wires

    International Nuclear Information System (INIS)

    Li Yonggang; Quick, Nathaniel R.; Kar, Aravinda

    2003-01-01

    Drawability of Nickel 200 wires in laser dieless drawing was investigated. Influencing factors under consideration include the laser power, the heat-treatment state (as-drawn or annealed), and the initial wire diameter. Microstructural evolutions in laser dieless drawing were studied by scanning electron microscopy (SEM). The wires exhibit optimal drawability at an intermediate laser power range corresponding to the wire temperature in the range of 1000-1300 K. The as-drawn precursor wire has better drawability than that of the annealed wire. The drawability decreases as the precursor wire diameter deceases. Microcrystalline structures were found in nickel 200 wires after being laser-drawn from as-drawn precursor wires. These experimental observations are explained using the concepts of dynamic recovery and recrystallization

  8. Experimental studies of the refined structure within oxide UO{sub 2} clusters (1983); Etudes experimentales de structure fine a l'interieur de grappes d'oxyde UO{sub 2} (1963)

    Energy Technology Data Exchange (ETDEWEB)

    Palmedo, P F [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1963-07-01

    General measurements of neutron fine structure in various UO{sub 2} clusters are described. The experimental techniques that were found useful are presented, as well as the methods of experimental analysis. The results are given in detail. A semi-empirical relation for the fine structure in clusters is suggested and is compared with the various results. (author) [French] Plusieurs experiences de structure fine de la densite neutronique dans diverses grappes de UO{sub 2} sont decrites. On presente les techniques qui ont ete jugees les plus appropriees pour ce genre de mesure, les methodes d'analyae des experiences, et les resultats detailles. Une expression semi-empirique de la structure fine dans de telles grappes est donnee et elle est comparee avec les divers reaultats obtenue. (auteur)

  9. The influence of target structure on topographical features produced by ion beam sputtering

    International Nuclear Information System (INIS)

    Whitton, J.L.; Grant, W.A.

    1981-01-01

    Ion beam erosion of solid surfaces often results in the development of distinctive topographical features. The relationship between the type of features formed by ion erosion and target structure has been investigated. Single crystals of copper and nickel and the amorphous alloy Metglas have been bombarded to high doses (approx. >=10 19 ions cm -2 ) with 40 keV Ar + and P + . Topography changes were monitored using SEM and structural changes by TEM. Targets that retain their long range crystallinity show sharply defined, regular features that are related to the target structure. Targets that are highly disordered, either intrinsically or as a result of the ion bombardment, produce diffuse, smaller features. Those differences are observed at all stages in topographical evolution. (orig.)

  10. Effects of some inhibitors of protein synthesis on the chloroplast fine structure, CO2 fixation and the Hill reaction activity

    Directory of Open Access Journals (Sweden)

    S. Więckowski

    2015-01-01

    Full Text Available A comparative study concerning the effects of chloramphenicol (100 μg ml-1, actidione (10 μg ml-1, 5-bromouracil (190 μg ml-1, actinomycin D (30 μg ml-1 and DL-ethionine (800 μg ml-1 on the chloroplast fine structure, 14CO2 incorporation and the Hill reaction activity was the subject of the experiments presented in this paper. The experiments were conducted on bean seedlings under the conditions when chlorophyll accumulation was inhibited only partially. The results obtained indicate that chloromphenicol is responsible for the reduction of the number of grana per section of plastid and for the formation of numerous vesicles in the stroma. In the presence of actidione, actinomycin D or DL-ethionine the lamellae are poorly differentiated into .stroma and granum regions and there occur disturbances in the typical orientation of lamellae within chloroplasts. Only in the presence of 5-bromouracil the development of chloroplast structure resemble that in control plants. A comparison of the results obtained with those published earlier (Więckowski et al., 1974; Ficek and Więckowski, 1974 shows that such processes as assimilatory pigment accumulation, the rate of CO2 fixation, the Hill reaction activity, and the development of lamellar system are suppressed in a different extent by the inhibitors used.

  11. X-ray-absorption fine structure determination of pressure-induced bond-angle changes in ReO3

    International Nuclear Information System (INIS)

    Houser, B.; Ingalls, R.

    2000-01-01

    We report here on a Marquardt-type method to fit the x-ray absorption fine structure (XAFS) of ReO 3 . We find that, when the ambient-pressure structure of ReO 3 is used as a starting point, the pressure dependence of the angle of the Re-O-Re bond in ReO 3 is fairly straightforwardly and robustly determined using FEFF curved-wave, multiple-scattering programs and is accurate to about ±1.5 degree sign or better. We present an argument that XAFS and scattering experiments fundamentally differ in what they measure in the case of nearly linear atomic bridges. Focussed multiple-scattering paths involving the Re-O-Re bridge make a contribution to the XAFS spectrum that is sensitive to the rms deviation of oxygen from the [100]-type directions. Fits to simulated spectra back up our contention that for XAFS experiments the effective position of the oxygen atom is its rms displacement whether the average displacement is zero or not. (c) 2000 The American Physical Society

  12. Lamb shift and fine structure at n =2 in a hydrogenlike muonic atom with the nuclear spin I =0

    Science.gov (United States)

    Korzinin, Evgeny Yu.; Shelyuto, Valery A.; Ivanov, Vladimir G.; Karshenboim, Savely G.

    2018-01-01

    The paper is devoted to the Lamb shift and fine structure in a hydrogenlike muonic atom with a spinless nucleus up to the order α5m with all the recoil corrections included. Enhanced contributions of a higher order are also considered. We present the results on the pure QED contribution and on the finite-nuclear-size contribution, proportional to RN2, with the higher-order corrections included. We also consider the consistency of the pure QED theory and the evaluation of the nuclear-structure effects. Most of the QED theory is the same as the theory for the case of the nuclear spin 1/2. Additional nuclear-spin-dependent terms are considered in detail. The issue of the difference for the theories with a spinor nucleus and a scalar one is discussed for the recoil contributions in the order (Zα ) 4m ,α (Zα ) 4m , and (Zα ) 5m . The numerical results are presented for the muonic atoms with two lightest scalar nuclei, helium-4 and beryllium-10. We compare the theory of those muonic atoms with theory for the muonic hydrogen. Some higher-order finite-nuclear-size corrections for the Lamb shift in muonic hydrogen are revisited.

  13. Alfvénic Dynamics and Fine Structuring of Discrete Auroral Arcs: Swarm and e-POP Observations

    Science.gov (United States)

    Miles, D.; Mann, I. R.; Pakhotin, I.; Burchill, J. K.; Howarth, A. D.; Knudsen, D. J.; Wallis, D. D.; Yau, A. W.; Lysak, R. L.

    2017-12-01

    The electrodynamics associated with dual discrete arc aurora with anti-parallel flow along the arcs were observed nearly simultaneously by the enhanced Polar Outflow Probe (e-POP) and the Swarm A and C spacecraft. Auroral imaging from e-POP reveal 1-10 km structuring of the arcs, which move and evolve on second timescales and confound the traditional single-spacecraft field-aligned current algorithms. High-cadence magnetic data from e-POP shows 1-10 Hz, presumably Alfvénic perturbations co-incident with and at the same scale size as the observed dynamic auroral fine structures. High-cadence electric and magnetic field data from Swarm A reveals non-stationary electrodynamics involving reflected and interfering Alfvén waves and signatures of modulation consistent with trapping in the Ionospheric Alfvén Resonator (IAR). Together, these observations suggest a role for Alfven waves, perhaps also the IAR, in discrete arc dynamics on 0.2 - 10s timescales and 1-10 km spatial scales.

  14. Two different zinc sites in bovine 5-aminolevulinate dehydratase distinguished by extended x-ray absorption fine structure

    International Nuclear Information System (INIS)

    Dent, A.J.; Hasnain, S.S.; Beyersmann, D.; Block, C.

    1990-01-01

    The zinc coordination in 5-aminolevulinate dehydratase was investigated by extended x-ray absorption fine structure (EXAFS) associated with the zinc K-edge. The enzyme binds 8 mol of zinc/mol of octameric protein, but only four zinc ions seem sufficient for full activity. The authors have undertaken a study on four forms of the enzyme: (a) the eight-zinc native enzyme; (b) the enzyme with only the four zinc sites necessary for full activation occupied; (c) the enzyme with the vacant sites of (b) occupied by four lead ions; (d) the product complex between (b) and porphobilinogen. They have shown that two structurally distinct types of zinc sites are available in the enzyme. The site necessary for activity has an average zinc environment best described by two/three histidines and one/zero oxygen from a group such as tyrosine or a solvent molecule at 2.06 ± 0.02 angstrom, one tyrosine or aspartate at 1.91 ± 0.03 angstrom, and one cysteine sulfur at 2.32 ± 0.03 angstrom with a total coordination of five ligands. The unoccupied site in (b) is dominated by a single contribution of four cysteinyl sulfur atoms at 2.28 ± 0.02 angstrom. Spectra from samples (c) and (d) show only small changes from that of (b), reflecting a slight rearrangement of the ligands around the zinc atom

  15. Effect of Hf on the fine structure of mesophyll cells from Glycine max, Merr

    Energy Technology Data Exchange (ETDEWEB)

    Wei, L.; Miller, G.W.

    1972-04-01

    A series of ultrastructural changes were observed in soybean leaves fumigated with 40 to 50 ppb of hydrogen fluoride. In the cytoplasm the presence of small vacuoles was the first noticeable initial change. The fragmentation of the vacuolar membrane occurred either simultaneously or followed immediately. Lipid-droplet-like globules and numerous vesicles occurred subsequently in the cytoplasm and increased as the injury became more severe. There was a decrease in polysomes and a detachment of ribosome from the rough endoplasmic reticulum. Free ribosome concentration also decreased as the injury became severe. Mitochondrial modifications involving dilation of outer and cristae membranes followed by reduction of both cristae number and matrix electron density and the disappearance of mitochondrial granules were observed in the chlorotic leaves. Electron dense inclusions accumulated in some mitochondria as well. The first noticeable change observed in the chloroplast was the presence of clusters of phytoferritin granules within the stoma after only 2 days of fumigation. Alterations in nuclear structures were observed in later stages of injury. Numerous small electron dense particles were found on various types of membranes in cells of severely chlorotic leaves. They were distributed on outer mitochondrial membranes, endoplasmic reticula, dictyosomes, tonoplasts, plasmalemma, nuclear envelopes, and disintegrating organelles and vesicles, but were never observed on membranes of chloroplasts and microbodies. The presence of fluoride has attracted the attention of many workers primarily in certain industrial areas where the emitted atmospheric fluoride concentrates and is accumulated by plants initiating injury. 6 references.

  16. Analysis of fine structure of X-ray spectra from laser-irradiated gold dot

    International Nuclear Information System (INIS)

    Yang Guohong; Zhang Jiyan; Zhang Baohan; Zhou Yuqing; Li Jun

    2000-01-01

    The X-ray emission spectra from highly stripped plasma of gold has been observed by focusing a Nd-glass frequency tripled laser beam onto the surface of the gold dot at the XINGGUANG II laser facilities. The spectra of gold ions in the range of 0.0003 nm-0.0004 nm was recorded using the plate PET (2d = 0.8742 nm) crystal spectrometer. The code of average energy of relativistic sub-arrays was built on the basis of the code MCDF (Multi-Configuration-Dirac-Fock). Using the spin-orbit-split-arrays (SOSA) formalism, mean wavelengths and full widths at half height of isolated peaks of sub-arrays of lower charged gold ions, isoelectronic with Cu, Zn, Ga and Ge, was calculated. Twenty-six lines are interpreted, they pertain mainly to transitions of 3d-nf (n = 5,6,7) of gold ions from Ni-like to As-like. These results of experiment and calculation have important application in plasma diagnostics and examination of high Z elemental atomic structure calculation

  17. DNA AND THE FINE STRUCTURE OF SYNAPTIC CHROMOSOMES IN THE DOMESTIC ROOSTER (GALLUS DOMESTICUS)

    Science.gov (United States)

    Coleman, James R.; Moses, Montrose J.

    1964-01-01

    The indium trichloride method of Watson and Aldridge (38) for staining nucleic acids for electron microscopy was employed to study the relationship of DNA to the structure of the synaptinemal complex in meiotic prophase chromosomes of the domestic rooster. The selectivity of the method was demonstrated in untreated and DNase-digested testis material by comparing the distribution of indium staining in the electron microscope to Feulgen staining and ultraviolet absorption in thicker sections seen with the light microscope. Following staining by indium, DNA was found mainly in the microfibril component of the synaptinemal complex. When DNA was known to have been removed from aldehyde-fixed material by digestion with DNase, indium stainability was also lost. However, staining of the digested material with non-selective heavy metal techniques demonstrated the presence of material other than DNA in the microfibrils and showed that little alteration in appearance of the chromosome resulted from DNA removal. The two dense lateral axial elements of the synaptinemal complex, but not the central one to any extent, also contained DNA, together with non-DNA material. PMID:14228519

  18. PDI Derivative through Fine-Tuning Molecular Structure for Fullerene-Free Organic Solar Cells

    KAUST Repository

    Sun, Hua

    2017-08-10

    A perylenediimide (PDI)-based small molecular (SM) acceptor with both an extended π-conjugation and a three dimensional structure concurrently is critical for achieving high performance PDI-based fullerene-free organic solar cells (OSCs). In this work, we designed and synthesized a novel PDI-based SM acceptor possessing both characteristics by fusing PDI units with a spiro core of 4,4’-spirobi[cyclopenta[2,1-b;3,4-b’]dithiophene(SCPDT) through the -position of the thiophene rings. An enhanced strong absorption in the range of 350–520 nm and arisen LUMO energy level of FSP was observed, compared with previous reported acceptor SCPDT-PDI4, in which the PDI units and SCPDT are not fused. OSCs based on PTB7-Th donor and FSP acceptor were fabricated and achieved a power conversion efficiency of up to 8.89% with DPE as an additive. Efficient and complementary photo absorption, favorable phase separation and balanced carrier mobilites in the blend film account for the high photovoltaic performance. This study offers an effective strategy to design high performance PDI-based acceptors.

  19. A high-resolution study of mesospheric fine structure with the Jicamarca MST radar

    Directory of Open Access Journals (Sweden)

    R. Sheth

    2006-07-01

    Full Text Available Correlation studies performed on data from recent mesospheric experiments conducted with the 50-MHz Jicamarca radar in May 2003 and July 2004 are reported. The study is based on signals detected from a combination of vertical and off-vertical beams. The nominal height resolution was 150 m and spectral estimates were obtained after ~1 min integration. Spectral widths and backscattered power generally show positive correlations at upper mesospheric heights in agreement with earlier findings (e.g., Fukao et al., 1980 that upper mesospheric echoes are dominated by isotropic Bragg scatter. In many instances in the upper mesosphere, a weakening of positive correlation away from layer centers (towards top and bottom boundaries was observed with the aid of improved height resolution. This finding supports the idea that layer edges are dominated by anisotropic turbulence. The data also suggests that negative correlations observed at lower mesospheric heights are caused by scattering from anisotropic structures rather than reflections from sharp vertical gradients in electron density.

  20. A high-resolution study of mesospheric fine structure with the Jicamarca MST radar

    Science.gov (United States)

    Sheth, R.; Kudeki, E.; Lehmacher, G.; Sarango, M.; Woodman, R.; Chau, J.; Guo, L.; Reyes, P.

    2006-07-01

    Correlation studies performed on data from recent mesospheric experiments conducted with the 50-MHz Jicamarca radar in May 2003 and July 2004 are reported. The study is based on signals detected from a combination of vertical and off-vertical beams. The nominal height resolution was 150 m and spectral estimates were obtained after ~1 min integration. Spectral widths and backscattered power generally show positive correlations at upper mesospheric heights in agreement with earlier findings (e.g., Fukao et al., 1980) that upper mesospheric echoes are dominated by isotropic Bragg scatter. In many instances in the upper mesosphere, a weakening of positive correlation away from layer centers (towards top and bottom boundaries) was observed with the aid of improved height resolution. This finding supports the idea that layer edges are dominated by anisotropic turbulence. The data also suggests that negative correlations observed at lower mesospheric heights are caused by scattering from anisotropic structures rather than reflections from sharp vertical gradients in electron density.