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Sample records for nitrene fine-structure esr

  1. Collapse of the G d3 + ESR fine structure throughout the coherent temperature of the Gd-doped Kondo Semiconductor CeF e4P12

    Science.gov (United States)

    Venegas, P. A.; Garcia, F. A.; Garcia, D. J.; Cabrera, G. G.; Avila, M. A.; Rettori, C.

    2016-12-01

    Recent experiments on G d3 + electron-spin resonance (ESR) in the filled skutterudite C e1 -xG dxF e4P12(x ≈0.001 ) , at temperatures where the host resistivity manifests a smooth insulator-metal crossover, provide evidence of the underlying Kondo physics associated with this system. At low temperatures (below T ≈160 K), C e1 -xG dxF e4P12 behaves as a Kondo insulator with a relatively large hybridization gap, and the G d3 + ESR spectra display a fine structure with Lorentzian line shape, typical of insulating media. In this work, based on previous experiments performed by the same group, we argue that the electronic gap may be attributed to the large hybridization present in the coherent regime of a Kondo lattice. Moreover, mean-field calculations suggest that the electron-phonon interaction is fundamental at explaining such hybridization. The resulting electronic structure is strongly temperature dependent, and at T*≈160 K the system undergoes an insulator-to-metal transition induced by the withdrawal of 4 f electrons from the Fermi volume, the system becoming metallic and nonmagnetic. The G d3 + ESR fine structure coalesces into a single Dysonian resonance, as in metals. Our simulations suggest that exchange narrowing via the usual Korringa mechanism is not enough to describe the thermal behavior of the G d3 + ESR spectra in the entire temperature region (4.2-300 K). We propose that the temperature activated fluctuating valence of the Ce ions is the key ingredient that fully describes this unique temperature dependence of the G d3 + ESR fine structure.

  2. Carbenes and Nitrenes

    Science.gov (United States)

    Coyle, J. D.

    1974-01-01

    Summarizes the general methods for carbene and nitrene formation and the reactions in which carbenes and nitrenes are involved such as their reactions with transition metal atoms, alkenes of aromatic compounds, and uncharged oxygen or nitrogen nucleophiles. (CC)

  3. The azomethine nitrene

    NARCIS (Netherlands)

    Frints, Paul Johan Antoine

    1969-01-01

    This thesis deals with the generation and behavior of the azomethine nitrene. A general introduction (Chapter 1) into the chemistry of nitrenes, summarizing the most pertinent literature is given........ A literature survey of reactions which may involve an azomethine nitrene is presented (Chapter 2

  4. Selective formation of triplet alkyl nitrenes from photolysis of beta-azido-propiophenone and their reactivity.

    Science.gov (United States)

    Singh, Pradeep N D; Mandel, Sarah M; Sankaranarayanan, Jagadis; Muthukrishnan, Sivaramakrishnan; Chang, Mingxin; Robinson, Rachel M; Lahti, Paul M; Ault, Bruce S; Gudmundsdóttir, Anna D

    2007-12-26

    Photolysis of beta-azido propiophenone derivatives, 1, with built-in sensitizer units, leads to selective formation of triplet alkyl nitrenes 2 that were detected directly with laser flash photolysis (lambdamax = 325 nm, tau = 27 ms) and ESR spectroscopy (|D/hc| = 1.64 cm-1, |E/hc| = 0.004 cm-1). Nitrenes 2 were further characterized with argon matrix isolation, isotope labeling, and molecular modeling. The triplet alkyl nitrenes are persistent intermediates that do not abstract H-atoms from the solvent but do decay by dimerizing with another triplet nitrene to form azo products, rather than reacting with an azide precursor. The azo dimer tautomerizes and rearranges to form heterocyclic compound 3. Nitrene 2a, with an n,pi* configuration as the lowest triplet excited state of the its ketone sensitizer moiety, undergoes intramolecular 1,4-H-atom abstraction to form biradical 6, which was identified by argon matrix isolation, isotope labeling, and molecular modeling. beta-Azido-p-methoxy-propiophenone, with a pi,pi* lowest excited state of its triplet sensitizer moiety, does not undergo any secondary photoreactions but selectively yields only triplet alkyl nitrene intermediates that dimerize to form 3b.

  5. Characterization of DPOAE fine structure

    DEFF Research Database (Denmark)

    Reuter, Karen; Hammershøi, Dorte

    2005-01-01

    , and has recently been demonstrated to exist in low level equal-loudness contours. The character of the DPOAE fine structure depends on several parameters, i.e., level, frequencies, and frequency of the two primaries, but also level and character of the noise floor. The prevalence and character of the fine......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...... structures are highly individual, and till now no standardized method has been suggested for a consistent categorization. In the present paper a method developed for the categorization of fine structures is presented. The method has been used in two previous studies on the prevalence of fine structures, 1...

  6. Transient terminal Cu-nitrene intermediates from discrete dicopper nitrenes.

    Science.gov (United States)

    Badiei, Yosra M; Krishnaswamy, Ammani; Melzer, Marie M; Warren, Timothy H

    2006-11-29

    Reaction of the copper(I) beta-diketiminate {[Me3NN]Cu}2(mu-toluene) with the aryl azide N3Ar (Ar = 3,5-Me2C6H3) in toluene results in immediate effervescence and formation of the dicopper nitrene {[Me3NN]Cu}2(mu-NAr) (2) in 77% yield. The X-ray structure of 2 shows nearly symmetric bonding of the nitrene to two Cu centers separated by 2.911(1) A with Cu-N distances of 1.794(5) and 1.808(5) A along with a Cu-N-Cu angle of 107.8(2) degrees . This structure is conceptually related to the dicopper carbenes {[MexNN]Cu}2(mu-CPh2) (x = 2 or 3) (Dai, X.; Warren J. Am. Chem. Soc. 2004, 126, 10085. Badiei, Y. M.; Warren J. Organomet. Chem. 2005, 690, 5989.) which exhibit shorter Cu-Cu distances (2.4635(7) or 2.485(1) A) and acute Cu-C-Cu angles (79.51(14) or 80.1(2) degrees ). Addition of the Cu(I) anilidoimine {[Me2AI]Cu}2 (prepared from CuOtBu and the aniline-imine H[Me2AI] in 77% yield) to a benzene-d6 solution of 2 results in the formation of two new anilidoimine complexes {[Me2AI]Cu(mu- NAr)Cu[Me3NN] (5) and {[Me2AI]Cu}2(mu-NAr) (6) as well as [Me3NN]Cu(benzene) over 3 h. These observations are consistent with the slow dissociation of a [Me3NN]Cu fragment from 2 to generate the transient terminal nitrenes [Me3NN]Cu=NAr and [Me2AI]Cu=NAr quickly trapped by the [Me2AI]Cu fragment to form the new unsymmetrical and symmetrical dicopper nitrenes 5 and 6. Preliminary reactivity studies indicate electrophilic reactivity at the nitrene moiety. Dicopper nitrene 2 reacts with 10 equiv PMe3 and CNtBu to give ArN=PMe3 and ArN=C=NtBu in 94% and 92% yields, respectively, with concomitant formation of [Me3NN]Cu(L) (L = PMe3 and CNtBu). Reaction between 2 and 2 equiv PMe3 allows for observation of the structurally characterized Cu(I) phosphaimide [Me3NN]Cu(ArN=PMe3) (7).

  7. Bonding and structure of copper nitrenes.

    Science.gov (United States)

    Cundari, Thomas R; Dinescu, Adriana; Kazi, Abul B

    2008-11-03

    Copper nitrenes are of interest as intermediates in the catalytic aziridination of olefins and the amination of C-H bonds. However, despite advances in the isolation and study of late-transition-metal multiply bonded complexes, a bona fide structurally characterized example of a terminal copper nitrene has, to our knowledge, not been reported. In anticipation of such a report, terminal copper nitrenes are studied from a computational perspective. The nitrene complexes studied here are of the form (beta-diketiminate)Cu(NPh). Density functional theory (DFT), complete active space self-consistent-field (CASSCF) electronic structure techniques, and hybrid quantum mechanical/molecular mechanical (QM/MM) methods are employed to study such species. While DFT methods indicate that a triplet (S = 1) is the ground state, CASSCF calculations indicate that a singlet (S = 0) is the ground state, with only a small energy gap between the singlet and triplet. Moreover, the ground-state (open-shell) singlet copper nitrene is found to be highly multiconfigurational (i.e., biradical) and to possess a bent geometry about the nitrene nitrogen, contrasting with the linear nitrene geometry of the triplet copper nitrenes. CASSCF calculations also reveal the existence of a closed-shell singlet state with some degree of multiple bonding character for the copper-nitrene bond.

  8. Nitrene Radical Intermediates in Catalytic Synthesis.

    Science.gov (United States)

    Kuijpers, Petrus; van der Vlugt, Jarl Ivar; Schneider, Sven; de Bruin, Bas

    2017-07-04

    Nitrene radical complexes are reactive intermediates with discrete spin density at the nitrogen-atom of the nitrene moiety. These species have become important intermediates for organic synthesis, being invoked in a broad range of C-H functionalization and aziridination reactions. Nitrene radical complexes have intriguing electronic structures, and are best described as one-electron reduced Fischer-type nitrenes. They can be generated by intramolecular single electron transfer to the 'redox non-innocent' nitrene moiety at the metal. Nitrene radicals generated at open-shell cobalt(II) have thus far received most attention in terms of spectroscopic characterization, reactivity screening, catalytic application and (computational and experimental) mechanistic studies, but some interesting iron and precious metal catalysts have also been employed in related reactions involving nitrene radicals. In some cases, redox-active ligands are used to facilitate intramolecular single electron transfer from the complex to the nitrene moiety. Organic azides are among the most attractive nitrene precursors in this field, typically requiring pre-activated organic azides (e.g. RSO2N3, (RO)2P(=O)N3, ROC(=O)N3 and alike) to achieve efficient and selective catalysis. Challenging, non-activated aliphatic organic azides were recently added to the palette of synthetically useful reactions proceeding via nitrene radical intermediates. This concept article describes the electronic structure of nitrene radical complexes, emphasizes on their usefulness in the catalytic synthesis of various organic products, and highlights the important developments in the field. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Observations of substorm fine structure

    Directory of Open Access Journals (Sweden)

    L. L. Lazutin

    Full Text Available Particle and magnetic field measurements on the CRRES satellite were used, together with geosynchronous satellites and ground-based observations, to investigate the fine structure of a magnetospheric substorm on February 9, 1991. Using the variations in the electron fluxes, the substorm activity was divided into several intensifications lasting about 3–15 minutes each. The two main features of the data were: (1 the intensifications showed internal fine structure in the time scale of about 2 minutes or less. We call these shorter periods activations. Energetic electrons and protons at the closest geosynchronous spacecraft (1990 095 were found to have comparable activation structure. (2 The energetic (>69 keV proton injections were delayed with respect to electron injections, and actually coincided in time with the end of the intensifications and partial returns to locally more stretched field line configuration. We propose that the energetic protons could be able to control the dynamics of the system locally be quenching the ongoing intensification and possibly preparing the final large-scale poleward movement of the activity. It was also shown that these protons originated from the same intensification as the preceeding electrons. Therefore, the substorm instability responsible for the intensifications could introduce a negative feedback loop into the system, creating the observed fine structure with the intensification time scales.

    Key words. Magnetospheric Physics (Storms and substorms.

  10. Catalytic intermolecular alkene oxyamination with nitrenes.

    Science.gov (United States)

    Dequirez, Geoffroy; Ciesielski, Jennifer; Retailleau, Pascal; Dauban, Philippe

    2014-07-14

    The Rh(II)-catalyzed intermolecular addition of nitrenes to aromatic and aliphatic alkenes provides vicinal amino alcohols with yields of up to 95 % and complete regioselectivity. This 1,2-oxyamination reaction involves the formation of an aziridine intermediate that undergoes in situ ring opening. The latter is induced by the Rh-bound nitrene that behaves as a Lewis acid. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Nitrenes, diradicals, and ylides. Ring expansion and ring opening in 2-quinazolylnitrenes.

    Science.gov (United States)

    Kvaskoff, David; Bednarek, Pawel; George, Lisa; Waich, Kerstin; Wentrup, Curt

    2006-05-26

    Tetrazolo[1,5-a]quinazoline (9) is converted to 2-azidoquinazoline (10) on sublimation at 200 degrees C and above, and the azide-tetrazole equilibrium is governed by entropy. 2-Quinazolylnitrenes 11 and 27 and/or their ring expansion products 14 and 29 can undergo type I (ylidic) and type II (diradicaloid) ring opening. Argon matrix photolysis of 9/10 affords 2-quinazolylnitrene (11), which has been characterized by ESR, UV, and IR spectroscopy. A minor amount of a second nitrene, formed by rearrangement or ring opening, is also observed. A diradical (19) is formed rapidly by type II ring opening and characterized by ESR spectroscopy; it decays thermally at 15 K with a half-life of ca. 47 min, in agreement with its calculated facile intersystem crossing (19T --> 19OSS) followed by facile cyclization/rearrangement to 1-cyanoindazole (21) (calculated activation barrier 1-2 kcal/mol) and N-cyanoanthranilonitrile (22). 21and 22 are the isolated end products of photolysis. 21 is also the end product of flash vacuum thermolysis. An excellent linear correlation between the zero-field splitting parameter D (cm(-1)) and the spin density rho on the nitrene N calculated at the B3LYP/EPRIII level is reported (R2 = 0.993 for over 100 nitrenes). Matrix photolysis of 3-phenyltetrazolo[1,5-a]quinazoline (25) affords the benzotriazacycloheptatetraene 29, which can be photochemically interconverted with the type I ring opening product 2-isocyano-alpha-diazo-alpha-phenyltoluene (33) as determined by IR and UV spectroscopy. The corresponding carbene 37, obtained by photolysis of 33, was detected by matrix ESR spectroscopy.

  12. The fine structure of the ionosphere

    DEFF Research Database (Denmark)

    D'Angelo, N.; Michelsen, Poul

    1967-01-01

    We consider in this note the excitation of ion-acoustic waves by vertical gradients of density in the ionosphere. The conclusion is reached that the fine structure of the ionosphere is probably affected by the resulting instability, as comparison with observations seems to indicate. Recently, Liu...

  13. The fine structure constant and habitable planets

    DEFF Research Database (Denmark)

    Sandora, McCullen

    2016-01-01

    © 2016 IOP Publishing Ltd and Sissa Medialab srl .We use the existence of habitable planets to impose anthropic requirements on the fine structure constant, α. To this effect, we present two considerations that restrict its value to be very near the one observed. The first, that the end product...

  14. Photolysis of alpha-azidoacetophenones: direct detection of triplet alkyl nitrenes in solution.

    Science.gov (United States)

    Singh, Pradeep N D; Mandel, Sarah M; Robinson, Rachel M; Zhu, Zhendong; Franz, Roberto; Ault, Bruce S; Gudmundsdóttir, Anna D

    2003-10-17

    We report the first detection of triplet alkyl nitrenes in fluid solution by laser flash photolysis of alpha-azido acetophenone derivatives, 1. Alphazides 1 contain an intramolecular triplet sensitizer, which ensures formation of the triplet alkyl nitrene by bypassing the singlet nitrene intermediate. At room temperature, azides 1 cleave to form benzoyl and methyl azide radicals in competition with triplet energy transfer to form triplet alkyl nitrene. The major photoproduct 3 arises from interception of the triplet alkyl nitrene with benzoyl radicals. The triplet alkyl nitrene intermediates are also trapped with molecular oxygen to yield the corresponding 2-nitrophenylethanone. Laser flash photolysis of 1 reveals that the triplet alkyl nitrenes have absorption around 300 nm. The triplet alkyl nitrenes were further characterized by obtaining their UV and IR spectra in argon matrices. (13)C and (15)N isotope labeling studies allowed us to characterize the C-N stretch of the nitrene intermediate at 1201 cm(-)(1).

  15. On a time varying fine structure constant

    CERN Document Server

    Berman, M S; Berman, Marcelo S.; Trevisan, Luis A.

    2001-01-01

    By employing Dirac LNH, and a further generalization by Berman (GLNH), we estimate how should vary the total number of nucleons, the energy density, Newton Gravitational constant, the cosmological constant, the magnetic permeability and electric permitivity, of the Universe,in order to account for the experimentally observed time variation of the fine structure constant. As a bonus,we find an acceptable value for the deceleration parameter of the present Universe, compatible with the Supernovae observations.

  16. Variation of the fine structure constant

    CERN Document Server

    Lipovka, Anton A

    2016-01-01

    In present paper we evaluate the fine structure constant variation which should take place as the Universe is expanded and its curvature is changed adiabatically. This changing of the fine structure constant is attributed to the energy lost by physical system (consist of baryonic component and electromagnetic field) due to expansion of our Universe. Obtained ratio (d alpha)/alpha = 1. 10{-18} (per second) is only five times smaller than actually reported experimental limit on this value. For this reason this variation can probably be measured within a couple of years. To argue the correctness of our approach we calculate the Planck constant as adiabatic invariant of electromagnetic field, from geometry of our Universe in the framework of the pseudo- Riemannian geometry. Finally we discuss the double clock experiment based on Al+ and Hg+ clocks carried out by T. Rosenband et al. (Science 2008). We show that in this particular case there is an error in method and this way the fine structure constant variation c...

  17. Two new [Ni(tren)2]2+ complexes: [Ni(tren)2]Cl2 and [Ni(tren)2]WS4.

    Science.gov (United States)

    Ellermeier, Jan; Stähler, Ralph; Bensch, Wolfgang

    2002-02-01

    Both title compounds, bis[tris(2-aminoethyl)amine]nickel(II) dichloride, [Ni(tren)(2)]Cl(2), (I), and bis[tris(2-aminoethyl)amine]nickel(II) tetrathiotungstate, [Ni(tren)(2)]WS(4), (II), contain the [Ni(tren)(2)](2+) cation [tren is tris(2-aminoethyl)amine, C(6)H(18)N(4)]. The tren molecule acts as a tridentate ligand around the central Ni atom, with the remaining primary amine group not bound to the central atom. In (I), Ni(2+) is located on a centre of inversion surrounded by one crystallographically independent tren molecule. In the [Ni(tren)(2)](2+) cation of (II), the Ni atom is bound to two crystallographically independent tren molecules. The Ni atoms in the [Ni(tren)(2)](2+) complexes are in a distorted octahedral environment consisting of six N atoms from the chelating tren molecules. The counter-ions are chloride anions in (I) and the tetrahedral [WS(4)](2-) anion in (II). Hydrogen bonding is observed in both compounds.

  18. Rhodium-Catalyzed Alkene Difunctionalization with Nitrenes.

    Science.gov (United States)

    Ciesielski, Jennifer; Dequirez, Geoffroy; Retailleau, Pascal; Gandon, Vincent; Dauban, Philippe

    2016-06-27

    The Rh(II) -catalyzed oxyamination and diamination of alkenes generate 1,2-amino alcohols and 1,2-diamines, respectively, in good to excellent yields and with complete regiocontrol. In the case of diamination, the intramolecular reaction provides an efficient method for the preparation of pyrrolidines, and the intermolecular reaction produces vicinal amines with orthogonal protecting groups. These alkene difunctionalizations proceed by aziridination followed by nucleophilic ring opening induced by an Rh-bound nitrene generated in situ, details of which were uncovered by both experimental and theoretical studies. In particular, DFT calculations show that the nitrogen atom of the putative [Rh]2 =NR metallanitrene intermediate is electrophilic and support an aziridine activation pathway by N⋅⋅⋅N=[Rh]2 bond formation, in addition to the N⋅⋅⋅[Rh]2 =NR coordination mode. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  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. Fine Structure Constant: Theme With Variations

    CERN Document Server

    Bezerra, V B; Muniz, C R; Tahim, M O; Vieira, H S

    2016-01-01

    In this paper, we study the spatial variation of the fine structure constant $\\alpha$ due to the presence of a static and spherically symmetric gravitational source. The procedure consists of calculating the solution including the energy eigenvalues of a massive scalar field around that source, considering the weak-field regimen, which yields the gravitational analog of the atomic Bohr levels. From this result, we obtain several values for the effective $\\alpha$ by considering some scenarios of semi-classical and quantum gravities. Constraints on the parameters of the involved theories are calculated from astrophysical observations of the white dwarf emission spectra. Such constraints are compared with those ones obtained in the literature.

  1. The Fine Structure Constant and Habitable Planets

    CERN Document Server

    Sandora, McCullen

    2016-01-01

    We use the existence of habitable planets to impose anthropic requirements on the fine structure constant, $\\alpha$. To this effect, we present two considerations that restrict its value to be very near the one observed. The first, that the end product of stellar fusion is iron and not one of its neighboring elements, restricts $\\alpha^{-1}$ to be $145\\pm 50$. The second, that radiogenic heat in the Earth's interior remains adequately productive for billions of years, restricts it to be $145\\pm9$. A connection with the grand unified theory window is discussed, effectively providing a route to probe ultra-high energy physics with upcoming advances in planetary science.

  2. The fine structure constant and habitable planets

    Science.gov (United States)

    Sandora, McCullen

    2016-08-01

    We use the existence of habitable planets to impose anthropic requirements on the fine structure constant, α. To this effect, we present two considerations that restrict its value to be very near the one observed. The first, that the end product of stellar fusion is iron and not one of its neighboring elements, restricts α-1 to be 145± 50. The second, that radiogenic heat in the Earth's interior remains adequately productive for billions of years, restricts it to be 145±9. A connection with the grand unified theory window is discussed, effectively providing a route to probe ultra-high energy physics with upcoming advances in planetary science.

  3. The fine structure constant and habitable planets

    DEFF Research Database (Denmark)

    Sandora, McCullen

    2016-01-01

    © 2016 IOP Publishing Ltd and Sissa Medialab srl .We use the existence of habitable planets to impose anthropic requirements on the fine structure constant, α. To this effect, we present two considerations that restrict its value to be very near the one observed. The first, that the end product...... of stellar fusion is iron and not one of its neighboring elements, restricts α-1 to be 145± 50. The second, that radiogenic heat in the Earth's interior remains adequately productive for billions of years, restricts it to be 145±9. A connection with the grand unified theory window is discussed, effectively...

  4. Magnetic Tension of Sunspot Fine Structures

    CERN Document Server

    Venkatakrishnan, P

    2010-01-01

    The equilibrium structure of sunspots depends critically on its magnetic topology and is dominated by magnetic forces. Tension force is one component of the Lorentz force which balances the gradient of magnetic pressure in force-free configurations. We employ the tension term of the Lorentz force to clarify the structure of sunspot features like penumbral filaments, umbral light bridges and outer penumbral fine structures. We compute vertical component of tension term of Lorentz force over two active regions namely NOAA AR 10933 and NOAA AR 10930 observed on 05 January 2007 and 12 December 2006 respectively. The former is a simple while latter is a complex active region with highly sheared polarity inversion line (PIL). The vector magnetograms used are obtained from Hinode(SOT/SP). We find an inhomogeneous distribution of tension with both positive and negative signs in various features of the sunspots. The existence of positive tension at locations of lower field strength and higher inclination is compatible...

  5. The fine structure constant and numerical alchemy

    CERN Document Server

    Dattoli, Giuseppe

    2010-01-01

    We comment on past and more recent efforts to derive a formula yielding the fine structure constant in terms of integers and transcendent numbers. We analyse these "exoteric" attitudes and describe the myths regarding {\\alpha}, which seems to have very ancient roots, tracing back to Cabbala and to medieval alchemic conceptions. We discuss the obsession for this constant developed by Pauli and the cultural "environment" in which such an "obsession" grew. We also derive a simple formula for {\\alpha} in terms of two numbers {\\pi} and 137 only. The formula we propose reproduces the experimental values up to the last significant digit, it has not any physical motivation and is the result of an alchemic combination of numbers. We make a comparison with other existing formulae, discuss the relevant limits of validity by comparison with the experimental values and discuss a criterion to recover a physical meaning, if existing, from their mathematical properties.

  6. 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)

  7. 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].

  8. Implications of a Time-Varying Fine Structure Constant

    CERN Document Server

    Alfonso-Faus, A

    2002-01-01

    Much work has been done after the possibility of a fine structure constant being time-varying. It has been taken as an indication of a time-varying speed of light. Here we prove that this is not the case. We prove that the speed of light may or may not vary with time, independently of the fine structure constant being constant or not. Time variations of the speed of light, if present, have to be derived by some other means and not from the fine structure constant. No implications based on the possible variations of the fine structure constant can be imposed on the speed of light.

  9. Cell fine structure and function - Past and present

    Science.gov (United States)

    Fernandez-Moran, H.

    1970-01-01

    Electron microscopic studies of nerve membrane fine structure, discussing cell membrane multienzyme and macromolecular energy and information transduction, protein synthesis and nucleic acids interrelations

  10. The Fine Structure of the Parathyroid Gland

    Science.gov (United States)

    Trier, Jerry Steven

    1958-01-01

    The fine structure of the parathyroid of the macaque is described, and is correlated with classical parathyroid cytology as seen in the light microscope. The two parenchymal cell types, the chief cells and the oxyphil cells, have been recognized in electron micrographs. The chief cells contain within their cytoplasm mitochondria, endoplasmic reticulum, and Golgi bodies similar to those found in other endocrine tissues as well as frequent PAS-positive granules. The juxtanuclear body of the light microscopists is identified with stacks of parallel lamellar elements of the endoplasmic reticulum of the ergastoplasmic or granular type. Oxyphil cells are characterized by juxtanuclear bodies and by numerous mitochondria found throughout their cytoplasm. Puzzling lamellar whorls are described in the cytoplasm of some oxyphil cells. The endothelium of parathyroid capillaries is extremely thin in some areas and contains numerous fenestrations as well as an extensive system of vesicles. The possible significance of these structures is discussed. The connective tissue elements found in the perivascular spaces of macaque parathyroid are described. PMID:13502423

  11. 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.

  12. Cosmological Constant, Fine Structure Constant and Beyond

    CERN Document Server

    Wei, Hao; Li, Hong-Yu; Xue, Dong-Ze

    2016-01-01

    In this work, we consider the cosmological constant model $\\Lambda\\propto\\alpha^{-6}$, which is well motivated from three independent approaches. As is well known, the evidence of varying fine structure constant $\\alpha$ was found in 1998. If $\\Lambda\\propto\\alpha^{-6}$ is right, it means that the cosmological constant $\\Lambda$ should be also varying. In this work, we try to develop a suitable framework to model this varying cosmological constant $\\Lambda\\propto\\alpha^{-6}$, in which we view it from an interacting vacuum energy perspective. We propose two types of models to describe the evolutions of $\\Lambda$ and $\\alpha$. Then, we consider the observational constraints on these models, by using the 293 $\\Delta\\alpha/\\alpha$ data from the absorption systems in the spectra of distant quasars, and the data of type Ia supernovae (SNIa), cosmic microwave background (CMB), baryon acoustic oscillation (BAO). We find that the model parameters can be tightly constrained to the narrow ranges of ${\\cal O}(10^{-5})$ t...

  13. Efficient copper-mediated reactions of nitrenes derived from sulfonimidamides.

    Science.gov (United States)

    Leca, Dominique; Toussaint, Aurélie; Mareau, Camille; Fensterbank, Louis; Lacôte, Emmanuel; Malacria, Max

    2004-09-30

    [reaction: see text] Sulfonimidamides lead efficiently to nitrenes and have been converted to sulfimides, sulfoximines, and aziridines in good yields, through a copper-mediated multicomponent reaction. The stereogenic sulfur atom and the trivalent nitrogen atom present in the molecules open the way to asymmetric synthesis, whose first results are presented.

  14. Different behavior of nitrenes and carbenes on photolysis and thermolysis: formation of azirine, ylidic cumulene, and cyclic ketenimine and the rearrangement of 6-phenanthridylcarbene to 9-phenanthrylnitrene.

    Science.gov (United States)

    Kvaskoff, David; Bednarek, Pawel; George, Lisa; Pankajakshan, Sreekumar; Wentrup, Curt

    2005-09-30

    Flash vacuum thermolysis (FVT) of 9-azidophenanthrene 8, 6-(5-tetrazolyl)phenanthridine 18, and [1,2,3]triazolo[1,5-f]phenanthridine 19 yields 9-cyanofluorene 12 as the principal product and 4-cyanofluorene as a minor product. In all cases, when the product is condensed at or below 77 K, the seven-membered ring ketenimine 24 is detectable by IR spectroscopy (1932 cm(-1)) up to 200 K. Photolysis of Ar matrix isolated 8 at lambda = 308 or 313 nm generates at first the azirine 26, rapidly followed by the ylidic cumulene 27. The latter reverts to azirine 26 at lambda > 405 nm, and the azirine reverts to the ylidic cumulene at 313 nm. Nitrene 9 is observed by ESR spectroscopy following FVT of either azide 8, tetrazole 18, or triazole 19 with Ar matrix isolation of the products. Nitrene 9 and carbene 21 are observed by ESR spectroscopy in the Ar matrix photolyses of azide 8 and triazole 19, respectively.

  15. Search for Possible Variation of the Fine Structure Constant

    OpenAIRE

    2003-01-01

    Determination of the fine structure constant alpha and search for its possible variation are considered. We focus on a role of the fine structure constant in modern physics and discuss precision tests of quantum electrodynamics. Different methods of a search for possible variations of fundamental constants are compared and those related to optical measurements are considered in detail.

  16. Asymmetric nitrene transfer reactions: sulfimidation, aziridination and C-H amination using azide compounds as nitrene precursors.

    Science.gov (United States)

    Uchida, Tatsuya; Katsuki, Tsutomu

    2014-02-01

    Nitrogen functional groups are found in many biologically active compounds and their stereochemistry has a profound effect on biological activity. Nitrene transfer reactions such as aziridination, C-H bond amination, and sulfimidation are useful methods for introducing nitrogen functional groups, and the enantiocontrol of the reactions has been extensively investigated. Although high enantioselectivity has been achieved, most of the reactions use (N-arylsulfonylimino)phenyliodinane, which co-produces iodobenzene, as a nitrene precursor and have a low atom economy. Azide compounds, which give nitrene species by releasing nitrogen, are ideal precursors but rather stable. Their decomposition needs UV irradiation, heating in the presence of a metal complex, or Lewis acid treatment. The examples of previous azide decomposition prompted us to examine Lewis acid and low-valent transition-metal complexes as catalysts for azide decomposition. Thus, we designed new ruthenium complexes that are composed of a low-valent Ru(II) ion, apical CO ligand, and an asymmetry-inducing salen ligand. With these ruthenium complexes and azides, we have achieved highly enantioselective nitrene transfer reactions under mild conditions. Recently, iridium-salen complexes were added to our toolbox. Copyright © 2014 The Chemical Society of Japan and Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Fine Structure of Solar Acoustic Oscillations Due to Rotation

    Science.gov (United States)

    Goode, P. R.; Dziembowski, W.

    1984-01-01

    The nature of the fine structure of high order, low degree five minute period solar oscillations following from various postulated forms of spherical rotation is predicted. The first and second order effects of rotation are included.

  18. Photochemistry of Fluorinated Phenyl Nitrenes: Matrix Isolation of Fluorinated Azirines.

    Science.gov (United States)

    Morawietz, Jens; Sander, Wolfram

    1996-06-26

    2,6-Difluorophenylnitrene and pentafluorophenylnitrene were generated in solid argon at 10 K by irradiation of the corresponding phenyl azides and characterized by IR and UV spectroscopy. Selective irradiation with lambda = 444 nm results in the formation of the corresponding azirines, while ketene imines are not produced. On lambda = 366 nm irradiation the azirines rearrange back to the nitrenes. The assignment of the azirines is confirmed by ab-initio calculations.

  19. Antiviral agents derived from novel 1-adamantyl singlet nitrenes.

    Science.gov (United States)

    Kesel, Andreas J; Weiss, Hans-Christoph; Schönleber, Andreas; Day, Craig W; Barnard, Dale L; Detorio, Mervi A; Schinazi, Raymond F

    2012-12-07

    Amantadine constitutes an interesting, diamond crystal lattice-shaped, antivirally active amine with an inhibitory effect on influenza A viruses causing common 'flu' in humans. Unfortunately, amantadine forfeited most of its therapeutic potential because of resistance development in recent influenza A virus isolates. The antiviral efficacy of amantadine congeners can be chemically modified, resulting in re-constitution, improvement and/or extension of antiviral activities mediated by amino-adamantyls. Newly synthesized compounds were evaluated towards HIV type-1 (HIV-1) replication in primary human lymphocytes. One N-phenacyl amantadine derivative was investigated for inhibiting the in vitro replication of respiratory viruses (influenza A viruses, influenza B virus, human parainfluenza virus type 3 and severe acute respiratory syndrome coronavirus). Two ketone-stabilized 1-adamantyl singlet nitrenes were discovered serendipitously. To our best knowledge these are the first persistently stable nitrenes to be reported. Their structure was proved by determining the X-ray single crystal structure of one hydrolytic elaboration product. This salt adduct revealed an incommensurately modulated crystal structure, which was solved by extensive computational refinement. We could show that ketone-stabilized 1-adamantyl singlet nitrenes are versatile synthons for the synthesis of antiviral drug candidates. An amantadine-folate conjugate was inhibitory on HIV-1 replication in primary human lymphocytes, and one N-phenacyl amantadine derivative was inhibitory towards low pathogenic avian influenza A virus (H5N1) replication in vitro. These results indicate that the aromatic-aliphatic ketone-stabilized 1-adamantyl singlet nitrenes, beyond being of fundamental interest in organic chemistry, represent versatile synthons for the synthesis of new amantadine-related potentially antiviral drugs.

  20. Validation of ESR analyzer using Westergren ESR method.

    Science.gov (United States)

    Sikka, Meera; Tandon, Rajesh; Rusia, Usha; Madan, Nishi

    2007-07-01

    Erythrocyte sedimentation rate (ESR) is one of the most frequently ordered laboratory test. ESR analyzers were developed to provide a quick and efficient measure of ESR. We compared the results of ESR obtained by an ESR analyzer with those by the Westergren method in a group of 75 patients Linear regression analysis showed a good correlation between the two results (r = 0.818, p < 0.01). The intra class correlation was 0.82. The analyzer method had the advantages of safety, decreased technician time and improved patient care by providing quick results.

  1. Photolysis of Carbonyl Diisocyanate: Generation of Isocyanatocarbonyl Nitrene and Diazomethanone.

    Science.gov (United States)

    Liu, Qifan; Li, Hongmin; Wu, Zhuang; Li, Dingqing; Beckers, Helmut; Rauhut, Guntram; Zeng, Xiaoqing

    2016-10-20

    The stepwise decomposition of carbonyl diisocyanate, OC(NCO)2 , has been studied by using IR spectroscopy in solid argon matrices at 16 K. Upon irradiation with an ArF laser (λ=193 nm), carbonyl diisocyanate split off CO and furnished a new carbonyl nitrene, OCNC(O)N, in its triplet ground state. Two conformers of the nitrene, syn and anti, that were derived from the two conformers of OC(NCO)2 (62 % syn-syn and 38 % syn-anti) were identified and characterized by combining IR spectroscopy and quantum chemical calculations. Subsequent irradiation with visible light (λ>395 nm) caused the Curtius rearrangement of the nitrene into OCNNCO. In addition to the expected decomposition products, N2 and CO, further photolysis of OCNNCO with the ArF laser yielded NOCN, through a diazomethanone (NNCO) intermediate. To further validate our proposed reaction mechanism, ArF-laser photolysis of the closely related NNNNCO and cyclo-N2 CO in solid argon matrices were also studied. The observations of NOCN and in situ CO-trapped product OCNNCO provided indirect evidence to support the initial generation of NNCO as a common intermediate during the laser photolysis of OCNNCO, NNNNCO, and cyclo-N2 CO. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Porphyrin Cobalt(III) "Nitrene Radical" Reactivity; Hydrogen Atom Transfer from Ortho-YH Substituents to the Nitrene Moiety of Cobalt-Bound Aryl Nitrene Intermediates (Y = O, NH).

    Science.gov (United States)

    Goswami, Monalisa; Rebreyend, Christophe; de Bruin, Bas

    2016-02-20

    In the field of cobalt(II) porphyrin-catalyzed metallo-radical reactions, organic azides have emerged as successful nitrene transfer reagents. In the pursuit of employing ortho-YH substituted (Y = O, NH) aryl azides in Co(II) porphyrin-catalyzed nitrene transfer reactions, unexpected hydrogen atom transfer (HAT) from the OH or NH₂ group in the ortho-position to the nitrene moiety of the key radical-intermediate was observed. This leads to formation of reactive ortho-iminoquinonoid (Y = O) and phenylene diimine (Y = NH) species. These intermediates convert to subsequent products in non-catalyzed reactions, as is typical for these free organic compounds. As such, the observed reactions prevent the anticipated cobalt-mediated catalytic radical-type coupling of the nitrene radical intermediates to alkynes or alkenes. Nonetheless, the observed reactions provide valuable insights into the reactivity of transition metal nitrene-radical intermediates, and give access to ortho-iminoquinonoid and phenylene diimine intermediates from ortho-YH substituted aryl azides in a catalytic manner. The latter can be employed as intermediates in one-pot catalytic transformations. From the ortho-hydroxy aryl azide substrates both phenoxizinones and benzoxazines could be synthesized in high yields. From the ortho-amino aryl azide substrates azabenzene compounds were obtained as the main products. Computational studies support these observations, and reveal that HAT from the neighboring OH and NH₂ moiety to the nitrene radical moiety has a low energy barrier.

  3. Effects of cellular fine structure on scattered light pattern.

    Science.gov (United States)

    Liu, Caigen; Capjack, Clarence E

    2006-06-01

    Biological cells are complex in both morphological and biochemical structure. The effects of cellular fine structure on light scattered from cells are studied by employing a three-dimensional code named AETHER which solves the full set of Maxwell equations by using the finite-difference time-domain method. It is shown that changes in cellular fine structure can cause significant changes in the scattered light pattern over particular scattering angles. These changes potentially provide the possibility for distinguishability of cellular intrastructures. The effects that features of different intrastructure have on scattered light are discussed from the viewpoint of diagnosing cellular fine structure. Finally, we discuss scattered light patterns for lymphocyte-like cells and basophil-like cells.

  4. 3D WHOLE-PROMINENCE FINE STRUCTURE MODELING

    Energy Technology Data Exchange (ETDEWEB)

    Gunár, Stanislav; Mackay, Duncan H. [School of Mathematics and Statistics, University of St Andrews, North Haugh, St Andrews, KY16 9SS (United Kingdom)

    2015-04-20

    We present the first 3D whole-prominence fine structure model. The model combines a 3D magnetic field configuration of an entire prominence obtained from nonlinear force-free field simulations, with a detailed description of the prominence plasma. The plasma is located in magnetic dips in hydrostatic equilibrium and is distributed along multiple fine structures within the 3D magnetic model. Through the use of a novel radiative transfer visualization technique for the Hα line such plasma-loaded magnetic field model produces synthetic images of the modeled prominence comparable with high-resolution observations. This allows us for the first time to use a single technique to consistently study, in both emission on the limb and absorption against the solar disk, the fine structures of prominences/filaments produced by a magnetic field model.

  5. Helium 23P Fine Structure Measurement in a Discharge Cell

    Science.gov (United States)

    Zelevinsky, T.; Farkas, D.; Gabrielse, G.

    2005-12-01

    A precise measurement of helium 23P fine structure was carried out in a discharge cell using Doppler-free laser spectroscopy. It is the only known experiment to directly measure all three fine structure intervals at a 1 kHz level of accuracy. The 23P1 - 23P2 interval value agrees with other experiments but disagrees with theoretical predictions of two-electron QED. When this disagreement is resolved, the 23P0 - 23P1 interval measurement reported here will allow a determination of the fine structure constant to 14 parts in 109, surpassing the precision of the well known QED-independent quantum Hall effect and Josephson effect determinations. The discharge cell is shown to be advantageous in the study and correction of systematic frequency shifts related to light pressure, and the use of the cell ensures that the possible systematic errors are substantially different from those reported in other experiments.

  6. 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. Many studies indicate that OAE might be a more sensitive measure to detect early noise-induced haring...... losses than pure-tone audiometry. The distortion product otoacoustic emission (DPOAE) fine structure is obtained when the ear is stiumulated 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...... threshold microstructure also. In this study the DPOAE fine structure is obtained for symphony orchestra musicians both for left and right ears and before and after the orchestra rehearsal. The DPOAE fine structure is analyzed in order to investigate, whether it contains more information about the state...

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

    DEFF Research Database (Denmark)

    Reuter, Karen; Hammershøi, Dorte

    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...... threshold microstructure also. In this study DPOAE fine structures and hearing thresholds are obtained for symphony orchestra musicians both for left and right ears and before and after the orchestra rehearsal. DPOAE fine structures are analyzed with an automatic classification algorithm, which describes...

  8. 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.......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....

  9. Nitrenes, carbenes, diradicals, and ylides. Interconversions of reactive intermediates.

    Science.gov (United States)

    Wentrup, Curt

    2011-06-21

    Rearrangements of aromatic and heteroaromatic nitrenes and carbenes can be initiated with either heat or light. The thermal reaction is typically induced by flash vacuum thermolysis, with isolation of the products at low temperatures. Photochemical experiments are conducted either under matrix isolation conditions or in solution at ambient temperature. These rearrangements are usually initiated by ring expansion of the nitrene or carbene to a seven-membered ring ketenimine, carbodiimide, or allene (that is, a cycloheptatetraene or an azacycloheptatetraene when a nitrogen is involved). Over the last few years, we have found that two types of ring opening take place as well. Type I is an ylidic ring opening that yields nitrile ylides or diazo compounds as transient intermediates. Type II ring opening produces either dienylnitrenes (for example, from 2-pyridylnitrenes) or 1,7-(1,5)-diradicals (such as those formed from 2-quinoxalinylnitrenes), depending on which of these species is better stabilized by resonance. In this Account, we describe our achievements in elucidating the nature of the ring-opened species and unraveling the connections between the various reactive intermediates. Both of these ring-opening reactions are found, at least in some cases, to dominate the subsequent chemistry. Examples include the formation of ring-opened ketenimines and carbodiimides, as well as the ring contraction reactions that form five-membered ring nitriles (such as 2- and 3-cyanopyrroles from pyridylnitrenes, N-cyanoimidazoles from 2-pyrazinyl and 4-pyrimidinylnitrenes, N-cyanopyrazoles from 2-pyrimidinylnitrenes and 3-pyridazinylnitrenes, and so forth). The mechanisms of formation of the open-chain and ring-contraction products were unknown at the onset of this study. In the course of our investigation, several reactions with three or more consecutive reactive intermediates have been unraveled, such as nitrene, seven-membered cyclic carbodiimide, and open-chain nitrile ylide

  10. 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....

  11. Binding energy and fine structure of the He- ion

    Institute of Scientific and Technical Information of China (English)

    ZHUO; Lin; ZHU; Jing-jing; GOU; Bing-cong

    2007-01-01

    The variational method using a multiconfiguration wavefunction is carried out on the core-excited state 1s2s2p 4P0 for helium negative ion, including mass polarization and relativistic corrections. Binding energy and fine structure are reported. The results are compared with other theoretical and experimental date in the literature.

  12. UAl2 : Fine structure of the f bands

    NARCIS (Netherlands)

    Groot, R.A. de; Koelling, D.D.; Weger, M.

    1985-01-01

    The electronic structure of the C15, or cubic-Laves-phase material, UAl2 has been calculated using the linearized relativistic augmented-plane-wave method. The anomalous behavior of the electrical resistivity, specific heat, and magnetic susceptibility can be explained by the fine structure of the

  13. 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. In...

  14. The origin of the distortion product otoacoustic emission fine structure

    Science.gov (United States)

    Piskorski, Pawel

    Distortion-product otoacoustic emissions (DPOAEs) are sounds detected in the ear canal which are generated by the nonlinear processes in the inner ear (cochlea) in response to the external stimulation of two or more tones (primaries). Their generation region in the cochlea can be systematically changed by varying the primary frequencies, and they are currently being evaluated for possible clinical use in screening for hearing defects. The phase and amplitude of various orders of DPOAEs of frequencies, f/sb [dp]=f1-n(f2-f1),/ (n=1,2,/...), were measured in human subjects for two- tone stimuli of frequencies f1 and f2 (>f1). A number of experimental paradigms (fixed primary ratio f2/f1, fixed f1, fixed f2, and fixed f/sb [dp]) were used to investigate the nature of peaks and valleys (fine structure) of DPOAEs in their phase and amplitude dependence on the primary frequencies. This fine structure must be taken into account in any potential clinical applications of DPOAEs. The experimental results largely support a model in which the fine structure stems from interference at the base of the cochlea between distortion product (DP) components coming from the primary DPOAE source region (around the f2 tonotopic place) and components coming from the DP tonotopic place (via reflection of an apically moving DP wave). The spectral periodicity of the fine structures for several orders of apical DPOAEs corresponds to a tonotopic displacement of about 0.4 mm along the basilar membrane (BM) (0.4 bark). In agreement with the reaction model, this spectral spacing is also characteristic of synchronous evoked and spontaneous otoacoustic emission spectra as well as the microstructure of the hearing threshold. Approximate analytic expressions for the mechanisms which are responsible for the fine structure are used to interpret the data.

  15. A Laser Flash Photolysis Study of Azo-Compound Formation from Aryl Nitrenes at Room Temperature.

    Science.gov (United States)

    Ribblett, Alec Q; Poole, James S

    2016-06-30

    The species 4-nitrenopyridine 1-oxide is known to exhibit triplet nitrene dominated chemistry to yield azo-dimer products exclusively, even at room temperature. As such, this species, and its analogue 4-nitrenoquinoline 1-oxide, are useful models to probe the mechanism of formation of azo-dimers, which is postulated to proceed by self-reaction of the nitrene or reaction of nitrene with the parent azide. A laser flash photolysis study is described where the kinetics of formation of azo-dimer were found to be most adequately modeled by competition between both mechanisms, and rate coefficients for the competing reactions were determined.

  16. Photolysis of alpha-azidoacetophenones: trapping of triplet alkyl nitrenes in solution.

    Science.gov (United States)

    Mandel, S M; Krause Bauer, J A; Gudmundsdottir, A D

    2001-02-22

    [reaction: see text] Selective excitation of the ketone chromophore in alpha-azidoacetophenones, 1, leads to intramolecular triplet energy transfer to the azido group, which forms the corresponding triplet alkyl nitrene, 2. Azides 1 also undergo alpha-cleavage to form benzoyl and methyl azido radicals in competition with nitrene formation. Thus the major photoproduct, 2-benzoylamino-1-phenylethanone, 3, comes from trapping of 2 with a benzoyl radical. This appears to be the first observation of bimolecular trapping of triplet alkyl nitrenes in solution.

  17. Mechanistic insights into C-H amination via dicopper nitrenes.

    Science.gov (United States)

    Aguila, Mae Joanne B; Badiei, Yosra M; Warren, Timothy H

    2013-06-26

    We examine important reactivity pathways relevant to stoichiometric and catalytic C-H amination via isolable β-diketiminato dicopper alkylnitrene intermediates {[Cl2NN]Cu}2(μ-NR). Kinetic studies involving the stoichiometric amination of ethylbenzene by {[Cl2NN]Cu}2(μ-N(t)Bu) (3) demonstrate that the terminal nitrene [Cl2NN]Cu═N(t)Bu is the active intermediate in C-H amination. Initial rates exhibit saturation behavior at high ethylbenzene loadings and an inverse dependence on the copper species [Cl2NN]Cu, both consistent with dissociation of a [Cl2NN]Cu fragment from 3 prior to C-H amination. C-H amination experiments employing 1,4-dimethylcyclohexane and benzylic radical clock substrate support a stepwise H-atom abstraction/radical rebound pathway. Dicopper nitrenes [Cu]2(μ-NCHRR') derived from 1° and 2° alkylazides are unstable toward tautomerization to copper(I) imine complexes [Cu](HN═CRR'), rendering 1° and 2° alkylnitrene complexes unsuitable for C-H amination.

  18. Law of Localised Fine Structure with application in mass spectrometry

    CERN Document Server

    Łącki, Mateusz Krzysztof

    2014-01-01

    This paper presents a brand new methodology to deal with isotopic fine structure calculations. By using the Poisson approximation in an entirely novel way, we introduce mathematical elegance into the discussion on the trade-off between resolution and tractability. Our considerations unify the concepts of fine-structure, equatransneutronic configurations, and aggregate isotopic structure in a natural and simple way. We show how to boost the theoretical resolution in a seemingly costless way by several orders of magnitude with respect to the already very efficient algorithms operating on isotopic aggregates. We also develop an effective new way to obtain the important peaks in the most disaggregated isotopic structure localised in a precise region in the mass domain.

  19. Metallicity Diagnostics with Infrared Fine-Structure Lines

    CERN Document Server

    Nagao, Tohru; Marconi, Alessandro; Matsuhara, Hideo

    2010-01-01

    Although measuring the gas metallicity in galaxies at various redshifts is crucial to constrain galaxy evolutionary scenarios, only rest-frame optical emission lines have been generally used to measure the metallicity. This has prevented us to accurately measure the metallicity of dust-obscured galaxies, and accordingly to understand the chemical evolution of dusty populations, such as ultraluminous infrared galaxies. Here we propose diagnostics of the gas metallicity based on infrared fine structure emission lines, which are nearly unaffected by dust extinction even the most obscured systems. Specifically, we focus on fine-structure lines arising mostly from HII regions, not in photo-dissociation regions, to minimize the dependence and uncertainties of the metallicity diagnostics from various physical parameters. Based on photoionization models, we show that the emission-line flux ratio of ([OIII]51.80+[OIII]88.33)/[NIII]57.21 is an excellent tracer of the gas metallicity. The individual line ratios [OIII]51...

  20. Theory of the fine structure of auroral kilometric radiation

    Science.gov (United States)

    Grabbe, C. L.

    1982-01-01

    Recent data from ISEE 1 show auroral kilometric radiation (AKR) with finely separated bands in frequency. The observation that the AKR fine structure frequency separation is about equal to the ion cyclotron frequency at the AKR source is strong evidence for the interaction of AKR and electrostatic ion cyclotron (EIC) waves in the source, as proposed by Grabbe et al. (1980) to explain the origin of AKR. It is pointed out that no other wave of frequency close to the band separation is known to exist in the auroral source region. The fine structure observed in the source region AKR is the first evidence for EIC waves in the lower source region (3000 - 5000 km attitude), as required in the theory of Grabbe et al.

  1. Fine structure constant variation or space-time anisotropy?

    CERN Document Server

    Chang, Zhe; Li, Xin

    2011-01-01

    Recent observations on quasar absorption spectra supply evidences for variation of fine structure constant $\\alpha$. In this paper, we propose another interpretation of the observational data on quasar absorption spectra: a scenario with space-time inhomogeneity and anisotropy but uniform fine structure constant. Maybe the space-time is characterized by Finsler geometry instead of Riemann one. Finsler geometry admits less symmetries than Riemann geometry does. We investigate the Finslerian geodesic equations in Randers space-time (a special Finsler space-time). It is found that the cosmological redshift in this space-time is deviated from the one in general relativity. The modification term to redshift could be generally revealed as a monopole plus dipole function about space-time locations and directions. We suggest that this modification corresponds to the observed spatial monopole and Australian Dipole in quasar absorption spectra.

  2. Possible Cosmological Implications of Time Varying Fine Structure Constant

    CERN Document Server

    Berman, M S; Berman, Marcelo S.; Trevisan, Luis A.

    2001-01-01

    We make use of Dirac LNH and results for a time varying fine structure constant in order to derive possible laws of variation for speed of light, the number of nucleons in the Universe, energy density and gravitational constant. By comparing with experimental bounds on G variation, we find that the deceleration paramenter of the present Universe is negative. This is coherent with recent Supernovae observations.

  3. 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.

  4. Fine structure of plastids during androgenesis in Hordeum vulgare L.

    OpenAIRE

    Fortunat Młodzianowski; Krystyna Idzikowska

    2014-01-01

    The fine structure of plastids was studied in the course of androgenesis in in the pollen of Hordeum vulgare L. It was found that these organelles occur in all stages of androgenesis. Their structure was simple and was frequently manifested on the cross section only by the presence of the envelope and matrix of different degree of density. Single thylakoids, nucleoid-like regions and starch grains were, however, also noted. The structure of plastids in embryoids formed from microspores of bar...

  5. Interconversion of nitrenes, azirenes, and diradicals: rearrangement of 3-isoquinolylnitrene to o-cyanophenylketenimine and 1-cyanoisoindole.

    Science.gov (United States)

    Vosswinkel, Michael; Lüerssen, Holger; Kvaskoff, David; Wentrup, Curt

    2009-02-06

    Photolysis of tetrazolo[1,5-b]isoquinoline/3-azidoisoquinoline 22T/22A generates 3-isoquinolylnitrene 23, which has been characterized together with a diradical species (25) by Ar matrix ESR spectroscopy. Photolysis at lambda > 300 nm generates azirene 24, characterized by IR spectroscopy, whereas further broad-band UV photolysis destroys the azirene to produce o-cyanophenylketenimine 17. The use of 15N-labeled tetrazole/azide 22T'/22A' demonstrates rapid equilibration of two regioisomeric 15N-labeled azirenes 24' and 24'' prior to formation of 17. Flash vacuum thermolysis (FVT) of 22T/22A affords 1-cyano-2H-isoindole 27 in quantitative yield. FVT of 15N-labeled tetrazole/azide 22T'/22A' causes scrambling of 15N label in the 1-cyano-2H-isoindole product. It is concluded that the interconversion of azirenes 24 takes place via the unobserved diazacycloheptatetraene/diazacycloheptatrienylidene 32/33, and that the rearrangement of azirene to ketenimine 17 and 1-cyanoisoindole 27 takes place via reversion to nitrene 23 followed by ring opening to diradical 25.

  6. Fine structure of the exciton electroabsorption in semiconductor superlattices

    Science.gov (United States)

    Monozon, B. S.; Schmelcher, P.

    2017-02-01

    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.

  7. Reaction of Ynamides with Iminoiodinane-Derived Nitrenes: Formation of Oxazolones and Polyfunctionalized Oxazolidinones.

    Science.gov (United States)

    Rey-Rodriguez, Romain; Grelier, Gwendal; Habert, Loïc; Retailleau, Pascal; Darses, Benjamin; Gillaizeau, Isabelle; Dauban, Philippe

    2017-09-01

    This article describes the reaction of ynamides with metallanitrenes generated in the presence of an iodine(III) oxidant. N-(Boc)-Ynamides are converted to oxazolones via a cyclization reaction. The reaction is mediated by a catalytic dirhodium-bound nitrene species that first behaves as a Lewis acid. The oxazolones can be converted in a one pot manner to functionalized oxazolidinones following a regio- and stereoselective oxyamination reaction with the same nitrene reagent generated in stoichiometric amounts.

  8. 5-Azido-2-aminopyridine, a new nitrene/nitrenium ion photoaffinity labeling agent that exhibits reversible intersystem crossing between singlet and triplet nitrenes.

    Science.gov (United States)

    Panov, Maxim S; Voskresenska, Valentyna D; Ryazantsev, Mikhail N; Tarnovsky, Alexander N; Wilson, R Marshall

    2013-12-26

    The photochemistry of a new photoaffinity labeling (PAL) agent, 5-azido-2-(N,N-diethylamino)pyridine, was studied in aprotic and protic solvents using femtosecond-to-microsecond transient absorption and product analysis, in conjunction with ab initio multiconfigurational and multireference quantum chemical calculations. The excited singlet S1 state is spectroscopically dark, whereas photoexcitation to higher-lying singlet excited S2 and S3 states drives the photochemical reaction toward a barrierless ultrafast relaxation path via two conical intersections to S1, where N2 elimination leads to the formation of the closed-shell singlet nitrene. The singlet nitrene undergoes intersystem crossing (ISC) to the triplet nitrene in aprotic and protic solvents as well as protonation to form the nitrenium ion. The ISC rate constants in aprotic solvents increase with solvent polarity, displaying a "direct" gap effect, whereas an "inverse" gap effect is observed in protic solvents. Transient absorption actinometry experiments suggest that a solvent-dependent fraction from 20% to 50% of nitrenium ions is generated on a time scale of a few tens of picoseconds. The closed-shell singlet and triplet nitrene are separated by a small energy gap in protic solvents. As a result, the unreactive triplet state nitrene undergoes delayed, thermally activated reverse ISC to reform the reactive closed-shell singlet nitrene, which subsequently protonates, forming the remaining fraction of nitrenium ions. The product studies demonstrate that the resulting nitrenium ion stabilized by the electron-donating 4-amino group yields the final cross-linked product with high, almost quantitative efficiency. The enhanced PAL function of this new azide with respect to the widely applied 4-amino-3-nitrophenyl azide is discussed.

  9. Anionic substituent control of the electronic structure of aromatic nitrenes.

    Science.gov (United States)

    Rau, Nathan J; Welles, Emily A; Wenthold, Paul G

    2013-01-16

    The electronic structures of phenylnitrenes with anionic π-donating substituents are investigated by using mass spectrometry and electronic structure calculations. Reactions of para-CH(2)(-)-substituted phenylnitrene, formed by dissociative deprotonation of p-azidotoluene, with CS(2) and NO indicate that it has a closed-shell singlet ground state, whereas reactions of p-oxidophenylnitrene formed by dissociative deprotonation of p-azidophenol indicate either a triplet ground state or a singlet with a small singlet-triplet splitting. The ground electronic state assignments based on ion reactivity are consistent with electronic structure calculations. The stability of the closed-shell singlet states in nitrenes is shown by Natural Resonance Theory to be very sensitive to the amount of deprotonated-imine character in the wave function, such that large changes in state energies can be achieved by small modifications of the electronic structure.

  10. ESR dating of fault rocks

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hee Kwon [Kangwon National Univ., Chuncheon (Korea, Republic of)

    2002-03-15

    Past movement on faults can be dated by measurement of the intensity of ESR signals in quartz. These signals are reset by local lattice deformation and local frictional heating on grain contacts at the time of fault movement. The ESR signals then trow back as a result of bombardment by ionizing radiation from surrounding rocks. The age is obtained from the ratio of the equivalent dose, needed to produce the observed signal, to the dose rate. Fine grains are more completely reset during faulting, and a plot of age vs grain size shows a plateau for grains below critical size : these grains are presumed to have been completely zeroed by the last fault activity. We carried out ESR dating of fault rocks collected from the Yangsan fault system. ESR dates from the this fault system range from 870 to 240 ka. Results of this research suggest that long-term cyclic fault activity continued into the pleistocene.

  11. Isotope Effects in ESR Spectroscopy

    Directory of Open Access Journals (Sweden)

    Werner Herrmann

    2013-06-01

    Full Text Available In order to present the relationship between ESR spectroscopy and isotope effects three levels are considered: (i ESR spectroscopy is described on a general level up to the models for interpretation of the experimental spectra, which go beyond the usually used time and mass independent spin-Hamilton operator, (ii the main characteristics of the generalized isotope effects are worked out, and finally (iii the basic, mainly quantum mechanical effects are used to describe the coupling of electron spins with the degrees of freedom, which are accessible under the selected conditions, of the respective paramagnetic object under investigation. The ESR parameters and the respective models are formalized so far, that they include the time and mass depending influences and reflect the specific isotope effects. Relations will be established between the effects in ESR spectra to spin relaxation, to spin exchange, to the magnetic isotope effect, to the Jahn-Teller effects, as well as to the influence of zero-point vibrations. Examples will be presented which demonstrate the influence of isotopes as well as the kind of accessible information. It will be differentiated with respect to isotope effects in paramagnetic centres itself and in the respective matrices up to the technique of ESR imaging. It is shown that the use of isotope effects is indispensable in ESR spectroscopy.

  12. Derivation of the fine structure constant using fractional dynamics

    CERN Document Server

    Goldfain, E

    2003-01-01

    Both classical and quantum electrodynamics assume that random fluctuations are absent from the steady-state evolution of the underlying physical system. Our work goes beyond this approximation and accounts for the continuous exposure to stochastic fluctuations. It is known that the asymptotic limit of quantum field dynamics, dominated by large and persistent perturbations, may be described as an anomalous diffusion process. We use fractional calculus as an appropriate tool to handle this highly non-trivial regime. It is shown that the fine structure constant can be recovered from the fractional evolution equation of the density matrix under standard normalization conditions.

  13. Topological Quantization in Units of the Fine Structure Constant

    Energy Technology Data Exchange (ETDEWEB)

    Maciejko, Joseph; /Stanford U., Phys. Dept. /Stanford U., Materials Sci. Dept. /SLAC; Qi, Xiao-Liang; /Station Q, UCSB /Stanford U., Phys. Dept. /Stanford U., Materials Sci. Dept. /SLAC; Drew, H.Dennis; /Maryland U.; Zhang, Shou-Cheng; /Stanford U., Phys. Dept. /Stanford U., Materials Sci. Dept. /SLAC

    2011-11-11

    Fundamental topological phenomena in condensed matter physics are associated with a quantized electromagnetic response in units of fundamental constants. Recently, it has been predicted theoretically that the time-reversal invariant topological insulator in three dimensions exhibits a topological magnetoelectric effect quantized in units of the fine structure constant {alpha} = e{sup 2}/{h_bar}c. In this Letter, we propose an optical experiment to directly measure this topological quantization phenomenon, independent of material details. Our proposal also provides a way to measure the half-quantized Hall conductances on the two surfaces of the topological insulator independently of each other.

  14. Fine-structure constant constraints on Bekenstein-type models

    CERN Document Server

    Leal, P M M; Ventura, L B

    2014-01-01

    Astrophysical tests of the stability of dimensionless fundamental couplings, such as the fine-structure constant $\\alpha$, are an area of much increased recent activity, following some indications of possible spacetime variations at the few parts per million level. Here we obtain updated constraints on the Bekenstein-Sandvik-Barrow-Magueijo model, which is arguably the simplest model allowing for $\\alpha$ variations. Recent accurate spectroscopic measurements allow us to improve previous constraints by about an order of magnitude. We briefly comment on the dependence of the results on the data sample, as well as on the improvements expected from future facilities.

  15. Fine structures of type III radio bursts observed by LOFAR

    Science.gov (United States)

    Magdalenic, Jasmina; Marque, Christophe; Fallows, Richard; Mann, Gottfried; Vocks, Christian

    2017-04-01

    On August 25, 2014, NOAA AR 2146 produced the M2.0 class flare (peaked at 15:11 UT). The flare was associated with a coronal dimming, a EUV wave, a halo CME and a radio event observed by LOFAR (the LOw-Frequency Array). The radio event consisted of a type II, type III and type IV radio emissions. In this study, we focus on LOFAR observations of the type III bursts, generally considered to be radio signatures of fast electron beams propagating along open or quasi open field lines. The group of type III bursts was, as usually, observed during the impulsive phase of the flare. At first hand, type III bursts show no peculiarity, but the high frequency/time resolution LOFAR observations reveal that only few of these type III bursts have a smooth emission profile. The majority of bursts is strongly fragmented. Some show a structuring similar to type IIIb bursts, but on a smaller frequency scale, and others show a non-organized patchy structure which gives indication on the possibly related turbulence processes. Although fine structures of type III bursts were already reported, the wealth of fine structures, and the fragmentation of the radio emission observed in this August 25 event is unprecedented. We show that these LOFAR observations bring completely new insight and pose a new challenge for the physics of the acceleration of electron beams and associated emission processes.

  16. The fine structure line deficit in S 140

    CERN Document Server

    Ossenkopf, Volker; Okada, Yoko; Mookerjea, Bhaswati; van der Tak, Floris F S; Simon, Robert; Pütz, Patrick; Güsten, Rolf

    2015-01-01

    We try to understand the gas heating and cooling in the S 140 star forming region by spatially and spectrally resolving the distribution of the main cooling lines with GREAT/SOFIA. We mapped the fine structure lines of [OI] (63 {\\mu}m) and [CII] (158 {\\mu}m) and the rotational transitions of CO 13-12 and 16-15 with GREAT/SOFIA and analyzed the spatial and velocity structure to assign the emission to individual heating sources. We measure the optical depth of the [CII] line and perform radiative transfer computations for all observed transitions. By comparing the line intensities with the far-infrared continuum we can assess the total cooling budget and measure the gas heating efficiency. The main emission of fine structure lines in S 140 stems from a 8.3'' region close to the infrared source IRS 2 that is not prominent at any other wavelength. It can be explained by a photon-dominated region (PDR) structure around the embedded cluster if we assume that the [OI] line intensity is reduced by a factor seven due ...

  17. 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.

  18. 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.

  19. Solar Radio Bursts with Spectral Fine Structures in Preflares

    CERN Document Server

    Zhang, Yin; Karlický, Marian; Mészárosová, Hana; Huang, Jing; Tan, Chengming; Simões, Paulo

    2014-01-01

    A good observation of preflare activities is important for us to understand the origin and triggering mechanism of solar flares, and to predict the occurrence of solar flares. This work presents the characteristics of microwave spectral fine structures as preflare activities of four solar flares observed by Ond\\v{r}ejov radio spectrograph in the frequency range of 0.8--2.0 GHz. We found that these microwave bursts which occurred 1--4 minutes before the onset of flares have spectral fine structures with relatively weak intensities and very short timescales. They include microwave quasi-periodic pulsations (QPP) with very short period of 0.1-0.3 s and dot bursts with millisecond timescales and narrow frequency bandwidths. Accompanying these microwave bursts, there are filament motions, plasma ejection or loop brightening on the EUV imaging observations and non-thermal hard X-ray emission enhancements observed by RHESSI. These facts may reveal certain independent non-thermal energy releasing processes and partic...

  20. Herschel Galactic plane survey of [NII] fine structure emission

    CERN Document Server

    Goldsmith, Paul F; Langer, William D; Pineda, Jorge L

    2015-01-01

    We present the first large scale high angular resolution survey of ionized nitrogen in the Galactic Plane through emission of its two fine structure transitions ([NII]) at 122 $\\mu$m and 205 $\\mu$m. The observations were largely obtained with the PACS instrument onboard the Herschel Space Observatory. The lines-of-sight were in the Galactic plane, following those of the Herschel OTKP project GOT C+. Both lines are reliably detected at the 10$^{-8}$ - 10$^{-7}$ $W$m$^{-2}$sr$^{-1}$ level over the range -60$^{o}$ $\\leq$ $l$ $\\leq$ 60$^{o}$. The $rms$ of the intensity among the 25 PACS spaxels of a given pointing is typically less than one third of the mean intensity, showing that the emission is extended. [NII] is produced in gas in which hydrogen is ionized, and collisional excitation is by electrons. The ratio of the two fine structure transitions provides a direct measurement of the electron density, yielding $n(e)$ largely in the range 10 to 50 cm$^{-3}$ with an average value of 29 cm$^{-3}$ and N$^+$ colum...

  1. ESR dating of fault rocks

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hee Kwon [Kangwon National Univ., Chuncheon (Korea, Republic of)

    2003-02-15

    Past movement on faults can be dated by measurement of the intensity of ESR signals in quartz. These signals are reset by local lattice deformation and local frictional heating on grain contacts at the time of fault movement. The ESR signals then grow back as a result of bombardment by ionizing radiation from surrounding rocks. The age is obtained from the ratio of the equivalent dose, needed to produce the observed signal, to the dose rate. Fine grains are more completely reset during faulting, and a plot of age vs. grain size shows a plateau for grains below critical size; these grains are presumed to have been completely zeroed by the last fault activity. We carried out ESR dating of fault rocks collected near the Gori nuclear reactor. Most of the ESR signals of fault rocks collected from the basement are saturated. This indicates that the last movement of the faults had occurred before the Quaternary period. However, ESR dates from the Oyong fault zone range from 370 to 310 ka. Results of this research suggest that long-term cyclic fault activity of the Oyong fault zone continued into the Pleistocene.

  2. Characterization and Reactivity Studies of a Terminal Copper-Nitrene Species.

    Science.gov (United States)

    Corona, Teresa; Ribas, Lídia; Rovira, Mireia; Farquhar, Erik R; Ribas, Xavi; Ray, Kallol; Company, Anna

    2016-11-02

    High-valent terminal copper-nitrene species have been postulated as key intermediates in copper-catalyzed aziridination and amination reactions. The high reactivity of these intermediates has prevented their characterization for decades, thereby making the mechanisms ambiguous. Very recently, the Lewis acid adduct of a copper-nitrene intermediate was trapped at -90 °C and shown to be active in various oxidation reactions. Herein, we describe for the first time the synthesis and spectroscopic characterization of a terminal copper(II)-nitrene radical species that is stable at room temperature in the absence of any Lewis acid. The azide derivative of a triazamacrocyclic ligand that had previously been utilized in the stabilization of aryl-Cu(III) intermediates was employed as an ancillary ligand in the study. The terminal copper(II)-nitrene radical species is able to transfer a nitrene moiety to phosphines and abstract a hydrogen atom from weak C-H bonds, leading to the formation of oxidized products in modest yields. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Deep-cavity cavitand octa acid as a hydrogen donor: photofunctionalization with nitrenes generated from azidoadamantanes.

    Science.gov (United States)

    Choudhury, Rajib; Gupta, Shipra; Da Silva, José P; Ramamurthy, V

    2013-03-01

    1-azidoadamantane and 2-azidoadamantane form a 1:1 complex with hosts octa acid (OA) and cucurbit[7]uril (CB7) in water. Isothermal titration calorimetric measurements suggest these complexes to be very stable in aqueous solution. The complexes have been characterized by (1)H NMR in solution and by ESI-MS in gas phase. In both phases, the complexes are stable. Irradiation of these complexes (λ > 280 nm) results in nitrenes via the loss of nitrogen from the guest azidoadamantanes. The behavior of nitrenes within OA differs from that in solution. Nitrenes included within octa acid attack one of the four tertiary benzylic hydrogens present at the lower interior part of OA. While in solution intramolecular insertion is preferred, within OA intermolecular C-H insertion seems to be the choice. When azidoadamantanes included in CB7 were irradiated (λ > 280 nm) the same products as in solution resulted but the host held them tightly. Displacement of the product required the use of a higher binding guest. In this case, no intermolecular C-H insertion occurred. Difference in reactivity between OA and CB7 is the result of the location of hydrogens; in OA they are in the interior of the cavity where the nitrene is generated, and in CB7 they are at the exterior. Reactivity of nitrenes within OA is different from that of carbenes that do not react with the host.

  4. ESR dosimetry: achievements and challenges

    Energy Technology Data Exchange (ETDEWEB)

    Baffa, O., E-mail: baffa@usp.br [Universidade de Sao Paulo, Departamento de Fisica, Av. Bandeirantes 3900, 14040-901 Ribeirao Preto, Sao Paulo (Brazil)

    2015-10-15

    Full text: Electron Spin Resonance (ESR), also known as Electron Paramagnetic Resonance (EPR) and more recently as Electron Magnetic Resonance (Emr), is a spectroscopy technique able to detect unpaired electrons such as those created by the interaction ionizing radiation with matter. When the unpaired electrons created by ionizing radiation are stable over some reasonable time, ESR can be used to measure the radiation dose deposited in the material under study. In principle, any insulating material that satisfies this requisite can be used as a dosimeter. ESR has been used in retrospective dosimetry in case of radiological accidents using natural constituents of human body such as teeth, bones and nails as well as fortuitous materials as sugar, sweeteners and plastics. When using teeth the typical detected dose is 0.5 Gy for, for X-Band spectrometers (9 GHz) and even lower doses if higher frequency spectrometers are used. Clinical dosimetry is another area of potential use of this dosimetric modality. In this application the amino acid alanine has been proposed and being used. Alanine dosimeters are very easy to prepare and require no complicated treatments for use. Alanine/ESR dosimetry satisfies many of the required properties for clinical applications such as water equivalent composition, independence of response for the energy range used in therapy and high precision. Other organic materials such as ammonium tartrate are being investigated to increase the sensitivity of ESR for clinical applications. Finally, industrial applications can also benefit from this dosimetry. The challenges to expand applications, the number of users and research groups of ESR dosimetry will be discussed. (Author)

  5. Further Evidence for Cosmological Evolution of the Fine Structure Constant

    CERN Document Server

    Webb, J K; Flambaum, V V; Dzuba, V A; Barrow, John D; Churchill, C W; Prochaska, J X; Wolfe, A M

    2001-01-01

    We summarise the results of a search for time variability of the fine structure constant, alpha, using absorption systems in the spectra of distant quasars. Three large optical datasets and two 21cm/mm absorption systems provide four independent samples, spanning approximately 23% to 87% of the age of the universe. Each sample yields a negative Delta(alpha)/alpha (smaller alpha in the past) and the whole optical sample shows a 4-sigma deviation: Delta(alpha)/alpha = -0.72 +/- 0.18 x 10^{-5} over the redshift range 0.5 < z < 3.5. A comprehensive search for systematic effects reveals none which can explain our results. The only potentially significant systematic effects push Delta(alpha)/alpha towards positive values, i.e. our results would become more significant were we to correct for them.

  6. Time Variation of the Fine Structure Constant Driven by Quintessence

    CERN Document Server

    Anchordoqui, L A; Anchordoqui, Luis; Goldberg, Haim

    2003-01-01

    There are indications from the study of quasar absorption spectra that the fine structure constant $\\alpha$ 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 $\\beta$-decay rate in meteorite studies, atomic clock measurements) which probe variations of $\\alpha$ in the more recent past imply much smaller deviations from its present value. In this work we tie the variation of $\\alpha$ 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 WMAP observations, can be achieved for a range of parameters. Some definite predictions follow for upcoming space missions searching for violations of the equivalence principle.

  7. Nonlinear Electrodynamics Analysis Of The Fine Structure Constant

    Science.gov (United States)

    Mbelek, Jean Paul

    2010-10-01

    It has been claimed that during the late time history of our universe, the fine structure constant, α, has been increasing [1],[2]. However, other teams has claimed a discordant result [3],[4]. Also, the current precision of laboratory tests is not sufficient to either comfort or reject any of these astronomical observations. Here we suggest that a nonlinear electrodynamics (NLED) interaction of photons with the weak local background magnetic fields of a gas cloud absorber can reconcile the null result of refs.[3] and [4] with the negative variation found by refs. [2] and [1] and also to find a bridge with the positive variation found later by Levshakov et al.. [5]-[7]. Moreover, NLED photon propagation in a vacuum permeated by a background magnetic field is actually in full agreement with constraints from Oklo natural reactor data.

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

    Science.gov (United States)

    Anchordoqui, Luis; Goldberg, Haim

    2003-10-01

    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 (149Sm fission rate for the Oklo natural reactor, variation of 187Re 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.

  9. Varying Fine Structure Constant and Black Hole Physics

    CERN Document Server

    Das, S; Das, Saurya; Kunstatter, Gabor

    2003-01-01

    Recent astrophysical observations suggest that the fine structure constant $\\alpha=e^2/\\hbar c$ may be slowly increasing with time. This may be due to an increase of $e$ or a decrease of $c$, or both. In this article, we argue from model independent considerations that this variation should be considered adiabatic. Then, we examine in detail the consequences of such an adiabatic variation in the context of a specific model of quantized charged black holes. We find that the second law of black hole thermodynamics is obeyed, regardless of the origin of the variation, and that interesting constraints arise on the charge and mass of black holes. Finally, we estimate the work done on a black hole of mass $M$ due to the $\\alpha$ variation.

  10. Thermal stability analysis of the fine structure of solar prominences

    Science.gov (United States)

    Demoulin, Pascal; Malherbe, Jean-Marie; Schmieder, Brigitte; Raadu, Mickael A.

    1986-01-01

    The linear thermal stability of a 2D periodic structure (alternatively hot and cold) in a uniform magnetic field is analyzed. The energy equation includes wave heating (assumed proportional to density), radiative cooling and both conduction parallel and orthogonal to magnetic lines. The equilibrium is perturbed at constant gas pressure. With parallel conduction only, it is found to be unstable when the length scale 1// is greater than 45 Mn. In that case, orthogonal conduction becomes important and stabilizes the structure when the length scale is smaller than 5 km. On the other hand, when the length scale is greater than 5 km, the thermal equilibrium is unstable, and the corresponding time scale is about 10,000 s: this result may be compared to observations showing that the lifetime of the fine structure of solar prominences is about one hour; consequently, our computations suggest that the size of the unresolved threads could be of the order of 10 km only.

  11. Extended X-ray absorption fine structure of bimetallic nanoparticles

    Directory of Open Access Journals (Sweden)

    Carolin Antoniak

    2011-05-01

    Full Text Available Electronic and magnetic properties strongly depend on the structure of the material, especially on the crystal symmetry and chemical environment. In nanoparticles, the break of symmetry at the surface may yield different physical properties with respect to the corresponding bulk material. A useful tool to investigate the electronic structure, magnetic behaviour and local crystallographic structure is X-ray absorption spectroscopy. In this review, recent developments in the field of extended X-ray absorption fine structure measurements and in the analysis methods for structural investigations of bimetallic nanoparticles are highlighted. The standard analysis based on Fourier transforms is compared to the relatively new field of wavelet transforms that have the potential to outperform traditional analysis, especially in bimetallic alloys. As an example, the lattice expansion and inhomogeneous alloying found in FePt nanoparticles is presented, and this is discussed below in terms of the influence of employed density functional theory calculations on the magnetic properties.

  12. Varying Fine-Structure Constant and the Cosmological Constant Problem

    CERN Document Server

    Fujii, Y

    2003-01-01

    We start with a brief account of the latest analysis of the Oklo phenomenon providing the still most stringent constraint on time-variability of the fine- structure constant $\\alpha$. Comparing this with the recent result from the measurement of distant QSO's appears to indicate a non-uniform time-dependence, which we argue to be related to another recent finding of the accelerating universe. This view is implemented in terms of the scalar-tensor theory, applied specifically to the small but nonzero cosmological constant. Our detailed calculation shows that these two phenomena can be understood in terms of a common origin, a particular behavior of the scalar field, dilaton. We also sketch how this theoretical approach makes it appropriate to revisit non- Newtonian gravity featuring small violation of Weak Equivalence Principle at medium distances.

  13. Varying Fine-Structure Constant and the Cosmological Constant Problem

    Science.gov (United States)

    Fujii, Yasunori

    We start with a brief account of the latest analysis of the Oklo phenomenon providing the still most stringent constraint on time variability of the fine-structure constant α. Comparing this with the recent result from the measurement of distant QSO's appears to indicate a non-uniform time-dependence, which we argue to be related to another recent finding of the accelerating universe. This view is implemented in terms of the scalar-tensor theory, applied specifically to the small but nonzero cosmological constant. Our detailed calculation shows that these two phenomena can be understood in terms of a common origin, a particular behavior of the scalar field, dilaton. We also sketch how this theoretical approach makes it appropriate to revisit non-Newtonian gravity featuring small violation of Weak Equivalence Principle at medium distances.

  14. Atomic Clocks and Variations of the FIne Structure Constant

    Science.gov (United States)

    Prestage, John D.; Tjoelker, Robert L.; Maleki, Lute

    1995-01-01

    We describe a new test for possible variations of the fine structure constant alpha by comparisons of rates between clocks based on hyperfine transitions in alkali atoms with different atomic number Z. H-maser, Cs, and Hg(+) clocks have a different dependence on alpha via relativistic contributions of order (Z-alpha)(sup 2). Recent H-maser vs Hg(+) clock comparison data improve laboratory limits on a time variation by 100-fold to give dot-alpha less than or equal to 3.7 x 10(exp -14)/yr. Future laser cooled clocks (Be(+), Rb, Cs, Hg(+), etc.), when compared, will yield the most sensitive of all tests for dot-alpha/alpha.

  15. Varying fine structure "constant" and charged black holes

    CERN Document Server

    Bekenstein, Jacob D

    2009-01-01

    Tension between varying fine-structure "constant'' alpha and charged black hole properties has been invoked in the past to place constraints on cosmological variability of alpha. However, the properties used are those of the standard Reissner-Nordstrom black holes; this ignores modifications of black hole structure that must result from alpha variability. To elucidate this issue we have derived, in 4-D general relativity, and using isotropic coordinates, the solution for a charged spherical black hole according to the framework for dynamical variability of alpha which does not fix its overall scale. This solution coincides with a known one-parameter extension of the dilatonic black hole family. Among the notable properties of varying alpha charged black holes are adherence to the "no hair'' principle, the absence of the inner (Cauchy) horizon, the nonexistence of precisely extremal black holes, and the appearance of naked singularities in a separate sector of the relevant metric. This last hints at the possib...

  16. Fine structures in hearing thresholds and distortion product otoacoustic emissions

    DEFF Research Database (Denmark)

    Hammershøi, Dorte; Ordoñez, Rodrigo Pizarro; Torrente, Marina

    2010-01-01

    Otoacoustic emissions (OAEs) are weak sounds that can be recorded in the external ear. They are generated by the active amplification of the outer hair cells, and are by many believed to reflect the status of the most vulnerable part of the hearing better than ordinary behavioral thresholds...... of these two components. The result is characterized by a distinct fine structure pattern, and generally doesn't directly reflect the status of the hearing at one point on the basilar membrane. The behavioral threshold, on the other hand, is more directly related to given points along the basilar membrane......, but reflects the combined status of outer and inner hair cells. Thus the combination of DPOAE measurements and hearing thresholds has the potential to  provide better basis for hearing diagnosis. In the present study, both DPOAE measurements and hearing thresholds are determined with a fine frequency...

  17. [Morphogenesis and the fine structure of Stibiobacter senarmontii].

    Science.gov (United States)

    Pivovarova, T A; Lialikova, N N

    1980-01-01

    The morphogenesis and fine structure of Stibiobacter senarmontii were studied during its cultivation in the autotrophic conditions of growth in a mineral medium as well as in a medium containing yeast extract. The morphology of the organism was shown to be variable. A young culture was represented mainly by rods with three flagella. Coccoid, club-shaped and branching forms were observed during aging of the culture. The cells multiplied by irregular division and by breaking along the partition of the parent cell. The latter process yielded cell aggregates looking like rings and hieroglyphs. Electronograms revealed a complex membrane apparatus, polyribosomes, large electron-transparent inclusions, and unknown electron-dense inclusions in the nuclear zone. The cell wall looked on cross-sections as a three-layer structure. The assignment of St. senarmontii to Gram-positive bacteria is discussed. The morphogenesis of this organism suggests that it is related to the coryneform group of bacteria.

  18. Measurement of the Running of the Fine-Structure Constant

    CERN Document Server

    Acciarri, M; Adriani, O; Aguilar-Benítez, M; Alcaraz, J; Alemanni, G; Allaby, James V; Aloisio, A; Alviggi, M G; Ambrosi, G; Anderhub, H; Andreev, V P; Angelescu, T; Anselmo, F; Arefev, A; Azemoon, T; Aziz, T; Bagnaia, P; Baksay, L; Balandras, A; Ball, R C; Banerjee, S; Banerjee, Sw; Barczyk, A; Barillère, R; Barone, L; Bartalini, P; Basile, M; Battiston, R; Bay, A; Becattini, F; Becker, U; Behner, F; Bellucci, L; Berdugo, J; Berges, P; Bertucci, B; Betev, B L; Bhattacharya, S; Biasini, M; Biland, A; Blaising, J J; Blyth, S C; Bobbink, Gerjan J; Böhm, A; Boldizsar, L; Borgia, B; Bourilkov, D; Bourquin, Maurice; Braccini, S; Branson, J G; Brigljevic, V; Brochu, F; Buffini, A; Buijs, A; Burger, J D; Burger, W J; Button, A M; Cai, X D; Campanelli, M; Capell, M; Cara Romeo, G; Carlino, G; Cartacci, A M; Casaus, J; Castellini, G; Cavallari, F; Cavallo, N; Cecchi, C; Cerrada-Canales, M; Cesaroni, F; Chamizo-Llatas, M; Chang, Y H; Chaturvedi, U K; Chemarin, M; Chen, A; Chen, G; Chen, G M; Chen, H F; Chen, H S; Chiefari, G; Cifarelli, Luisa; Cindolo, F; Civinini, C; Clare, I; Clare, R; Coignet, G; Colijn, A P; Colino, N; Costantini, S; Cotorobai, F; Cozzoni, B; de la Cruz, B; Csilling, Akos; Cucciarelli, S; Dai, T S; van Dalen, J A; D'Alessandro, R; De Asmundis, R; Déglon, P L; Degré, A; Deiters, K; Della Volpe, D; Denes, P; De Notaristefani, F; De Salvo, A; Diemoz, M; Van Dierendonck, D N; Di Lodovico, F; Dionisi, C; Dittmar, Michael; Dominguez, A; Doria, A; Dova, M T; Duchesneau, D; Dufournaud, D; Duinker, P; Durán, I; El-Mamouni, H; Engler, A; Eppling, F J; Erné, F C; Extermann, Pierre; Fabre, M; Faccini, R; Falagán, M A; Falciano, S; Favara, A; Fay, J; Fedin, O; Felcini, Marta; Ferguson, T; Ferroni, F; Fesefeldt, H S; Fiandrini, E; Field, J H; Filthaut, Frank; Fisher, P H; Fisk, I; Forconi, G; Fredj, L; Freudenreich, Klaus; Furetta, C; Galaktionov, Yu; Ganguli, S N; García-Abia, P; Gataullin, M; Gau, S S; Gentile, S; Gheordanescu, N; Giagu, S; Gong, Z F; Grenier, G; Grimm, O; Grünewald, M W; Guida, M; van Gulik, R; Gupta, V K; Gurtu, A; Gutay, L J; Haas, D; Hasan, A; Hatzifotiadou, D; Hebbeker, T; Hervé, A; Hidas, P; Hirschfelder, J; Hirstius, A; Hofer, H; Holzner, G; Hoorani, H; Hou, S R; Iashvili, I; Jin, B N; Jones, L W; de Jong, P; Josa-Mutuberria, I; Khan, R A; Kaur, M; Kienzle-Focacci, M N; Kim, D; Kim, D H; Kim, J K; Kim, S C; Kirkby, Jasper; Kiss, D; Kittel, E W; Klimentov, A; König, A C; Kopp, A; Koutsenko, V F; Kräber, M H; Krämer, R W; Krenz, W; Krüger, A; Kunin, A; Ladrón de Guevara, P; Laktineh, I; Landi, G; Lassila-Perini, K M; Lebeau, M; Lebedev, A; Lebrun, P; Lecomte, P; Lecoq, P; Le Coultre, P; Lee, H J; Le Goff, J M; Leiste, R; Leonardi, E; Levchenko, P M; Li Chuan; Likhoded, S A; Lin, C H; Lin, W T; Linde, Frank L; Lista, L; Liu, Z A; Lohmann, W; Longo, E; Lü, Y S; Lübelsmeyer, K; Luci, C; Luckey, D; Lugnier, L; Luminari, L; Lustermann, W; Ma Wen Gan; Maity, M; Malgeri, L; Malinin, A; Maña, C; Mangeol, D J J; Marchesini, P A; Marian, G; Martin, J P; Marzano, F; Massaro, G G G; Mazumdar, K; McNeil, R R; Mele, S; Merola, L; Meschini, M; Metzger, W J; Von der Mey, M; Mihul, A; Milcent, H; Mirabelli, G; Mnich, J; Mohanty, G B; Molnár, P; Monteleoni, B; Moulik, T; Muanza, G S; Muheim, F; Muijs, A J M; Musy, M; Napolitano, M; Nessi-Tedaldi, F; Newman, H; Niessen, T; Nisati, A; Nowak, H; Oh, Yu D; Organtini, G; Oulianov, A; Palomares, C; Pandoulas, D; Paoletti, S; Paolucci, P; Paramatti, R; Park, H K; Park, I H; Pascale, G; Passaleva, G; Patricelli, S; Paul, T; Pauluzzi, M; Paus, C; Pauss, Felicitas; Pedace, M; Pensotti, S; Perret-Gallix, D; Petersen, B; Piccolo, D; Pierella, F; Pieri, M; Piroué, P A; Pistolesi, E; Plyaskin, V; Pohl, M; Pozhidaev, V; Postema, H; Pothier, J; Produit, N; Prokofev, D; Prokofiev, D O; Quartieri, J; Rahal-Callot, G; Rahaman, M A; Raics, P; Raja, N; Ramelli, R; Rancoita, P G; Raspereza, A V; Raven, G; Razis, P A; Ren, D; Rescigno, M; Reucroft, S; Van Rhee, T; Riemann, S; Riles, K; Robohm, A; Rodin, J; Roe, B P; Romero, L; Rosca, A; Rosier-Lees, S; Rubio, Juan Antonio; Ruschmeier, D; Rykaczewski, H; Saremi, S; Sarkar, S; Salicio, J; Sánchez, E; Sanders, M P; Sarakinos, M E; Schäfer, C; Shchegelskii, V; Schmidt-Kärst, S; Schmitz, D; Schopper, Herwig Franz; Schotanus, D J; Schwering, G; Sciacca, C; Sciarrino, D; Seganti, A; Servoli, L; Shevchenko, S; Shivarov, N; Shoutko, V; Shumilov, E; Shvorob, A V; Siedenburg, T; Son, D; Smith, B; Spillantini, P; Steuer, M; Stickland, D P; Stone, A; Stone, H; Stoyanov, B; Strässner, A; Sudhakar, K; Sultanov, G G; Sun, L Z; Suter, H; Swain, J D; Szillási, Z; Sztaricskai, T; Tang, X W; Tauscher, Ludwig; Taylor, L; Timmermans, C; Ting, Samuel C C; Ting, S M; Tonwar, S C; Tóth, J; Tully, C; Tung, K L; Uchida, Y; Ulbricht, J; Valente, E; Vesztergombi, G; Vetlitskii, I; Vicinanza, D; Viertel, Gert M; Villa, S; Vivargent, M; Vlachos, S; Vodopyanov, I; Vogel, H; Vogt, H; Vorobev, I; Vorobyov, A A; Vorvolakos, A; Wadhwa, M; Wallraff, W; Wang, M; Wang, X L; Wang, Z M; Weber, A; Weber, M; Wienemann, P; Wilkens, H; Wu, S X; Wynhoff, S; Xia, L; Xu, Z Z; Yang, B Z; Yang, C G; Yang, H J; Yang, M; Ye, J B; Yeh, S C; Zalite, A; Zalite, Yu; Zhang, Z P; Zhu, G Y; Zhu, R Y; Zichichi, A; Zilizi, G; Zöller, M

    2000-01-01

    Small-angle Bhabha scattering data recorded at the Z resonance and large-angleBhabha scattering data recorded at $\\sqrt{s} = 189$ \\textrm{Ge\\kern -0.1em V} bythe L3 detector at LEP are used to measure the running of the effective fine-structure constant for spacelike momentum transfers. The results are\\begin{eqnarray*} \\alpha^{-1}(-2.1 \\mathrm{Ge\\kern -0.1em V}^{2}) - \\alpha^{-1}(-6.25 \\mathrm{Ge\\kern -0.1em V}^{2}) & = & 0.78 \\pm 0.26 \\\\ \\alpha^{-1}(-12.25 \\mathrm{Ge\\kern -0.1em V}^{2}) - \\alpha^{-1}(-3434 \\mathrm{Ge\\kern -0.1em V}^{2}) & = & 3.80 \\pm 1.29, \\\\\\end{eqnarray*}in agreement with theoretical predictions.

  19. Fine structure of plastids during androgenesis in Hordeum vulgare L.

    Directory of Open Access Journals (Sweden)

    Fortunat Młodzianowski

    2014-01-01

    Full Text Available The fine structure of plastids was studied in the course of androgenesis in in the pollen of Hordeum vulgare L. It was found that these organelles occur in all stages of androgenesis. Their structure was simple and was frequently manifested on the cross section only by the presence of the envelope and matrix of different degree of density. Single thylakoids, nucleoid-like regions and starch grains were, however, also noted. The structure of plastids in embryoids formed from microspores of barley was compared with embryos developed from fertilized egg cell, and we did not found any fundamental differences between them. However, only plastid ribosomes were difficult to identify on ultrathin sections in embryoids and in the embryos.

  20. HERSCHEL GALACTIC PLANE SURVEY OF [N ii] FINE STRUCTURE EMISSION

    Energy Technology Data Exchange (ETDEWEB)

    Goldsmith, Paul F.; Yıldız, Umut A.; Langer, William D.; Pineda, Jorge L., E-mail: Paul.F.Goldsmith@jpl.nasa.gov [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States)

    2015-12-01

    We present the first large-scale high angular resolution survey of ionized nitrogen in the Galactic Plane through emission of its two fine structure transitions ([N ii]) at 122 and 205 μm. The observations were largely obtained with the PACS instrument onboard the Herschel Space Observatory. The lines of sight were in the Galactic plane, following those of the Herschel OTKP project GOT C+. Both lines are reliably detected at the 10{sup −8}–10{sup −7} Wm{sup −2} sr{sup −1} level over the range –60° ≤ l ≤ 60°. The rms of the intensity among the 25 PACS spaxels of a given pointing is typically less than one third of the mean intensity, showing that the emission is extended. [N ii] is produced in gas in which hydrogen is ionized, and collisional excitation is by electrons. The ratio of the two fine structure transitions provides a direct measurement of the electron density, yielding n(e) largely in the range 10–50 cm{sup −3} with an average value of 29 cm{sup −3} and N{sup +} column densities 10{sup 16}–10{sup 17} cm{sup −2}. [N ii] emission is highly correlated with that of [C ii], and we calculate that between 1/3 and 1/2 of the [C ii] emission is associated with the ionized gas. The relatively high electron densities indicate that the source of the [N ii] emission is not the warm ionized medium (WIM), which has electron densities more than 100 times smaller. Possible origins of the observed [N ii] include the ionized surfaces of dense atomic and molecular clouds, the extended low-density envelopes of H ii regions, and low-filling factor high-density fluctuations of the WIM.

  1. Unexpected effect of substituents on the zero-field splitting of triplet phenyl nitrenes

    Science.gov (United States)

    Korchagin, Denis V.; Akimov, Alexander V.; Yureva, Elena A.; Aldoshin, Sergei M.; Misochko, Eugenii Ya.

    2016-08-01

    The EPR spectrum of triplet 2,4,6-tribromophenyl nitrene was obtained in glassy methylcyclohexane at 15 K. Surprisingly, the zero-field splitting parameter D = 0.989 cm-1 derived from this spectrum is much lower than that reported previously for triplet 3,5-diazido-2,4,6-tribromophenyl nitrene and has the same value as in phenyl nitrenes composed with light atoms. DFT calculations of the zero-field splitting parameters support this unexpected experimental observation. Experimental and theoretical data provide evidence that the enhanced by bromine atoms spin-orbit contribution to the parameter D (the so called ;heavy-atom effect;) is strongly modulated by other substituents attached to the aromatic cycle.

  2. Spin-Selective Generation of Triplet Nitrenes: Olefin Aziridination through Visible-Light Photosensitization of Azidoformates.

    Science.gov (United States)

    Scholz, Spencer O; Farney, Elliot P; Kim, Sangyun; Bates, Desiree M; Yoon, Tehshik P

    2016-02-01

    Azidoformates are interesting potential nitrene precursors, but their direct photochemical activation can result in competitive formation of aziridination and allylic amination products. Herein, we show that visible-light-activated transition-metal complexes can be triplet sensitizers that selectively produce aziridines through the spin-selective photogeneration of triplet nitrenes from azidoformates. This approach enables the aziridination of a wide range of alkenes and the formal oxyamination of enol ethers using the alkene as the limiting reagent. Preparative-scale aziridinations can be easily achieved under continuous-flow conditions.

  3. Bumblebee Homing: The Fine Structure of Head Turning Movements.

    Directory of Open Access Journals (Sweden)

    Norbert Boeddeker

    Full Text Available Changes in flight direction in flying insects are largely due to roll, yaw and pitch rotations of their body. Head orientation is stabilized for most of the time by counter rotation. Here, we use high-speed video to analyse head- and body-movements of the bumblebee Bombus terrestris while approaching and departing from a food source located between three landmarks in an indoor flight-arena. The flight paths consist of almost straight flight segments that are interspersed with rapid turns. These short and fast yaw turns ("saccades" are usually accompanied by even faster head yaw turns that change gaze direction. Since a large part of image rotation is thereby reduced to brief instants of time, this behavioural pattern facilitates depth perception from visual motion parallax during the intersaccadic intervals. The detailed analysis of the fine structure of the bees' head turning movements shows that the time course of single head saccades is very stereotypical. We find a consistent relationship between the duration, peak velocity and amplitude of saccadic head movements, which in its main characteristics resembles the so-called "saccadic main sequence" in humans. The fact that bumblebee head saccades are highly stereotyped as in humans, may hint at a common principle, where fast and precise motor control is used to reliably reduce the time during which the retinal images moves.

  4. Fine structure in the cluster decay of radium isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Santhosh, K P [School of Pure and Applied Physics, Kannur University, Payyanur Campus, Payyanur 670 327 (India)], E-mail: kpsanthosh@eth.net

    2010-01-15

    Half-life times for {sup 14}C cluster emission from various radium isotopes are computed taking interacting potential as the sum of Coulomb and proximity potentials. The half-life time values are compared with experimental data and with the values reported by Poenaru et al using the analytical super-asymmetric fission model (ASAFM). The lowest half-life time for {sup 222}Ra stresses the role of the doubly magic {sup 208}Pb daughter in the exotic decay process. It is found that neutron excess in the parent nucleus slows down the exotic decay process. The high hindrance factor (HF) of the {sup 14}C branch to the ground state (9/2{sup +}) and the low HF to the first excited state (11/2{sup +}) of the {sup 209}Pb daughter are in good agreement with the experimental result. The fine structure from {sup 223}Ra gives direct evidence of the presence of a spherical component in the deformed parent nucleus.

  5. Benzene at 1 GHz. Magnetic field-induced fine structure

    Science.gov (United States)

    Heist, L. M.; Poon, C.-D.; Samulski, E. T.; Photinos, D. J.; Jokisaari, J.; Vaara, J.; Emsley, J. W.; Mamone, S.; Lelli, M.

    2015-09-01

    The deuterium NMR spectrum of benzene-d6 in a high field spectrometer (1 GHz protons) exhibits a magnetic field-induced deuterium quadrupolar splitting Δν. The magnitude of Δν observed for the central resonance is smaller than that observed for the 13C satellite doublets Δν‧. This difference, Δ(Δν) = Δν‧ - Δν, is due to unresolved fine structure contributions to the respective resonances. We determine the origins of and simulate this difference, and report pulse sequences that exploit the connectivity of the peaks in the 13C and 2H spectra to determine the relative signs of the indirect coupling, JCD, and Δν. The positive sign found for Δν is consonant with the magnetic field biasing of an isolated benzene molecule-the magnetic energy of the aromatic ring is lowest for configurations where the C6 axis is normal to the field. In the neat liquid the magnitude of Δν is decreased by the pair correlations in this prototypical molecular liquid.

  6. Hymenolepis nana: the fine structure of the embryonic envelopes.

    Science.gov (United States)

    Fairweather, I; Threadgold, L T

    1981-06-01

    The fine structure of the envelopes surrounding hatched and unhatched oncospheres of Hymenolepis nana has been investigated by transmission and scanning electron microscopy (SEM), together with light microscope histochemical observations of JB-4 embedded material. The oncosphere is surrounded by 3 layers--the capsule, the outer envelope and the inner envelope, the latter giving rise to the embryophore and the 'oncospheral membrane'. An additional layer--the polar filament layer--lies between the 'oncospheral membrane' and the oncosphere. Shell material is deposited on the capsule as a thin layer. It is secreted by the outer envelope, which degenerates once shell formation is complete. The uterus may also contribute to shell formation. The embryophore forms a thin incomplete and peripheral layer within the inner envelope. In the basal region of this envelope, partial development of an 'oncospheral membrane' takes place, but it does not become detached as a separate layer. The polar filaments, which are characteristic of the oncosphere of H. nana, are derived from the epithelial covering of the oncosphere itself, which delaminates to form a separate polar filament layer. The filaments arise from knob-like projections at opposite poles of this layer. The design of the embryonic envelopes in H. nana show a number of modifications from the basic cyclophyllidean pattern, and these can be related to the demands of its 'direct' life-cycle.

  7. The Fine Structure Lines of Hydrogen in HII Regions

    CERN Document Server

    Dennison, B; Minter, A H; Dennison, Brian; Minter, Anthony H.

    2005-01-01

    The 2s_{1/2} state of hydrogen is metastable and overpopulated in HII regions. In addition, the 2p states may be pumped by ambient Lyman-alpha radiation. Fine structure transitions between these states may be observable in HII regions at 1.1 GHz (2s_{1/2}-2p_{1/2}) and/or 9.9 GHz (2s_{1/2}-2p_{3/2}), although the details of absorption versus emission are determined by the relative populations of the 2s and 2p states. The n=2 level populations are solved with a parameterization that allows for Lyman-alpha pumping of the 2p states. The density of Lyman-alpha photons is set by their creation rate, easily determined from the recombination rate, and their removal rate. Here we suggest that the dominant removal mechanism of Lyman-alpha radiation in HII regions is absorption by dust. This circumvents the need to solve the Lyman-alpha transfer problem, and provides an upper limit to the rate at which the 2p states are populated by Lyman-alpha photons. In virtually all cases of interest, the 2p states are predominantl...

  8. Fine structure behaviour of VVER-1000 RPV materials under irradiation

    Science.gov (United States)

    Gurovich, B. A.; Kuleshova, E. A.; Shtrombakh, Ya. I.; Erak, D. Yu.; Chernobaeva, A. A.; Zabusov, O. O.

    2009-06-01

    Changes in the fine structure and mechanical properties of the base metal (BM) and weld metal (WM) of VVER-1000 pressure vessels during accumulation of neutron dose in the range of fluences ˜(3.2-15) × 10 23 m -2 ( E > 0.5 MeV) at 290 °C are studied using methods of transmission electron microscopy, fractographic analysis, and Auger electron spectroscopy. A correlation was found between the changes of mechanical properties and the micro- and nano-structures of the studied steels. Accumulation of neutron dose considerably raises the strength characteristics and transition temperature of VVER-1000 pressure vessel steels. The rate of changes in the mechanical properties of the weld metal is significantly higher than that of the base metal. The slower growth of strength characteristics and transition temperature shift of the base metal under irradiation as compared with the weld metal is due to the slower growth of the density of radiation defects and radiation-induced precipitates. The level of intergranular embrittlement under irradiation in the weld metal is not higher then in the base metal in spite of the higher content of nickel.

  9. Fine-structure constant: Is it really a constant?

    Science.gov (United States)

    Bekenstein, Jacob D.

    1982-03-01

    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 α˙α to at least some orders of magnitude below the Hubble rate H0. We argue that the conclusion is not as straightforward as claimed since there are good physical reasons to expect α˙α<

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

    CERN Document Server

    Holanda, R F L; Colaço, L R; Alcaniz, J S; Landau, S J

    2016-01-01

    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, $\\alpha$. Therefore, if $\\alpha$ is a time-dependent quantity, e.g., $\\alpha=\\alpha_0 \\phi(z)$, where $\\phi$ is a function of redshift, we argue that current data do not provide the real angular diameter distance, $D_{\\rm{A}}(z)$, to the cluster but instead $D_A^{data}(z) = \\phi(z)^2 D_{\\rm{A}}(z)$. We use this result to derive constraints on a possible variation of $\\alpha$ for a class of dilaton runaway models considering a sample of 25 measurements of $D_A^{data}(z)$ in redshift range $0.023 < z < 0.784$ and estimates of $D_{\\rm{A}}(z)$ from current type Ia supernovae observations. We find no significant indication of variation of $\\alpha$ with the present data.

  11. Mutagenic nitrenes/nitrenium ions from azido-imidazoarenes and their structure-activity relationships.

    Science.gov (United States)

    Wild, D; Dirr, A

    1989-11-01

    New heterocyclic arylazides (azido-imidazoarenes) structurally related to the food mutagen/carcinogen 2-amino-3-methyl-imidazo[4,5-f]quinoline (IQ) have been prepared. Their photolysis yields nitrenes and/or nitrenium ions which induce mutations in Salmonella typhimurium. The relationships between the chemical structure and mutagenic activity of these species are the same as those found in our previous studies of the amino- and nitro-imidazoarenes. Therefore the efficiency of the reaction with DNA of the ultimate metabolite, the nitrene/nitrenium ion, is the critical step governing the mutagenic potency of the amino- and nitro-imidazoarenes. The efficiency of DNA-binding depends on the delocalization of the positive charge of the nitrenium ion or of the electron deficiency of the nitrene. It is typical of the N-1-substituted and N-3-substituted arenimidazolyl-nitrenium ions that they can form another nitrenium resonance structure very similar to the parent nitrenium ion structure. We suggest that this property of the nitrene/nitrenium ion, in combination with its aromatic structure facilitating carbonium ion resonance structures, is the basic reason for the extremely potent mutagenic activity of IQ and related food mutagens/carcinogens.

  12. Microwave-assisted functionalization of carbon nanohorns via [2+1] nitrenes cycloaddition.

    Science.gov (United States)

    Karousis, Nikolaos; Ichihashi, Toshinari; Yudasaka, Masako; Iijima, Sumio; Tagmatarchis, Nikos

    2011-02-07

    The microwave-assisted functionalization of carbon nanohorns (CNHs) via [2+1] nitrenes cycloaddition, providing well dispersible hybrid materials possessing aziridino-rings covalently grafted onto the graphitic network of CNHs, was accomplished, while condensation of hydroxy-functionalized CNHs with thioctic acid, furnishing an endocyclic disulfide bond extended from the aziridino-rings, allowed the stabilization of Au nanoparticles.

  13. Functionalization of diamond (100) by organic cycloaddition reactions of nitrenes: a theoretical prediction.

    Science.gov (United States)

    Xu, Yi-Jun; Zhang, Yong-Fan; Li, Jun-Qian

    2005-09-16

    [structure: see text] We predict the viability of organic cycloadditions of nitrenes onto the diamond (100) surface. This new type of surface reaction can be employed to functionalize diamond surface at low temperature, which might introduce new functionalities to the diamond surface for novel applications in a diversity of fields.

  14. ESR powder line shape calculations

    Energy Technology Data Exchange (ETDEWEB)

    Vitko, J. Jr.; Huddleston, R.E.

    1976-05-01

    A program has been developed for computing the ESR spectrum of a collection of randomly oriented spins subject only to an electronic Zeeman interaction and having a Lorentzian single crystal line shape. Other single crystal line shapes, including numerical solutions of the Bloch equations, can be accommodated with minor modifications. The program differs in several features from those existing elsewhere, thus enabling one to study saturation effects, over-modulation effects, both absorptive and dispersive signals, and second and higher order derivative signals.

  15. Fine structure of Pn velocity beneath Sichuan-Yunnan region

    Institute of Scientific and Technical Information of China (English)

    黄金莉; 宋晓东; 汪素云

    2003-01-01

    We use 23298 Pn arrival-time data from Chinese national and provincial earthquake bulletins to invert fine structure of Pn velocity and anisotropy at the top of the mantle beneath the Sichuan-Yunnan and its adjacent region. The results suggest that the Pn velocity in this region shows significant lateral variation; the Pn velocity varies from 7.7 to 8.3 km/s. The Pn-velocity variation correlates well with the tectonic activity and heat flow of the region. Low Pn velocity is observed in southwest Yunnan , Tengchong volcano area, and the Panxi tectonic area. These areas have very active seismicity and tectonic activity with high surface heat flow. On the other hand, high Pn velocity is observed in some stable regions, such as the central region of the Yangtze Platform; the most pronounced high velocity area is located in the Sichuan Basin, south of Chengdu. Pn anisotropy shows a complex pattern of regional deformation. The Pn fast direction shows a prominent clockwise rotation pattern from east of the Tibetan block to the Sichuan-Yunnan diamond block to southwest Yunnan, which may be related to southeastward escape of the Tibetan Plateau material due to the collision of the Indian Plate to the Eurasia Plate. Thus there appears to be strong correlation between the crustal deformation and the upper mantle structure in the region. The delay times of events and stations show that the crust thickness decreases from the Tibetan Plateau to eastern China, which is consistent with the results from deep seismic sounding.

  16. Does over-exposure modify the fine structure of distortion product otoacoustic emissions?

    DEFF Research Database (Denmark)

    Reuter, Karen; Hammershøi, Dorte

    2008-01-01

    It is investigated, whether the pattern of distortion product otoacoustic emission (DPOAE) fine structure (quasi-periodic variations across frequency) is altered by an acoustical over-exposure. DPOAE fine structures are determined in 16 normal-hearing humans using a high frequency-resolution and ......It is investigated, whether the pattern of distortion product otoacoustic emission (DPOAE) fine structure (quasi-periodic variations across frequency) is altered by an acoustical over-exposure. DPOAE fine structures are determined in 16 normal-hearing humans using a high frequency...... within 20 minutes. The DPOAE fine structure pattern is analyzed by an automatic classification algorithm, which determines ripple center frequency, ripple spacing, ripple height and ripple prevalence. For some individuals, an alteration of some of the parameters could be observed after the exposure, i...

  17. Fine structure of high-power microwave-induced resistance oscillations

    Science.gov (United States)

    Shi, Q.; Zudov, M. A.; Dmitriev, I. A.; Baldwin, K. Â. W.; Pfeiffer, L. Â. N.; West, K. Â. W.

    2017-01-01

    We report on observation of a fine structure of microwave-induced resistance oscillations in an ultraclean two-dimensional electron gas. This fine structure is manifested by multiple secondary sharp extrema, residing beside the primary ones, which emerge at high radiation power. Theoretical considerations reveal that this fine structure originates from multiphoton-assisted scattering off short-range impurities. Unique properties of the fine structure allow us to access all experimental parameters, including microwave power, and to separate different contributions to photoresistance. Furthermore, we show that the fine structure offers a convenient means to quantitatively assess the correlation properties of the disorder potential in high-quality systems, allowing separation of short- and long-range disorder contributions to the electron mobility.

  18. ESR and iron status in pregnancy.

    Science.gov (United States)

    Madan, N; Kapoor, S; Rusia, U; Sharma, S; Nayyar, V L; Sundaram, K R; Sood, S K

    1997-10-01

    ESR (Westergen) correlated significantly with the iron status (as measured by Hb concentration, haematocrit, red cell count, MCH, P/H ratio, serum iron, TIBC and percent saturation of transferrin) in a group of pregnant women (PW) at term. Serum ferritin correlated negatively with the ESR but the correlation was not statistically significant. Serum ferritin levels of or = 50 mm 1st hour and 5 (19.2%) PW with ESR or = 50 mm 1st hour in 50% and 50 micrograms/L had ESR > or = 50 mm 1st hour, suggesting the possible effect of chronic infection in raising ferritin levels in these PW.

  19. Current topics in ESR dating

    Energy Technology Data Exchange (ETDEWEB)

    Skinner, Anne R., E-mail: Anne.R.Skinner@williams.edu [Williams College, Williamstown, MA (United States)

    2011-09-15

    After over 25 years, the use of electron spin resonance (ESR) is well-established in dating sites of geological, paleontological and archaeological interest. Like any scientific technique, there have been changes in understanding and in methodology. Improvements have not, however, changed the observation that external dose calculations are still a significant source of uncertainty in ages. Examples from Europe, Africa and the Americans illustrate this point. For Pradayrol Cave (France), the occupation age, 330 ka, is unchallenged, making this the oldest known Neanderthal site in France. For Roc de Marsal, also in France, on the other hand, discrepancies between TL and sedimentary dose rates imply substantial differences in interpretation. In the Western Egyptian Desert, where artifacts and datable material are not well-correlated, the dating results show consistency with expectations based on global climate change, even in deflated sites. Climate change is also the question in geological studies in the Bahamas where, despite concerns about cosmic dose history, ESR dates confirm other evidence for sea level changes. We show that an uncertain age is not the same as an impossible one.

  20. Theoretical Study of Relativistic Retardation Effects: the Abnormal Fine Structure of O Ⅱ

    Institute of Scientific and Technical Information of China (English)

    CHEN Shao-Hao; HAN Xiao-Ying; WANG Xiao-Lu; LI Ji

    2007-01-01

    Using multi-configuration Dirac-Fock and relativistic configuration interaction methods with high-order corrections, we report our precise calculation results of the fine-structure energy levels of the ground-state configuration of OⅡ(1s22s22p3). Our calculated fine-structure splittings of 2D3/2,5/2 and 2P1/2,3/2 are abnormal. We elucidate that the transverse (Breit) interaction, i.e. relativistic retardation effect, plays an important role for the abnormal fine-structure splittings. Our calculation results are in good agreement with experimental measurements.

  1. A Singlet Thiophosphoryl Nitrene and Its Interconversion with Thiazyl and Thionitroso Isomers.

    Science.gov (United States)

    Li, Hongmin; Wu, Zhuang; Li, Dingqing; Zeng, Xiaoqing; Beckers, Helmut; Francisco, Joseph S

    2015-09-02

    Thiophosphoryl nitrenes, R2P(S)N, are thiazirine-like intermediates that have been chemically inferred from trapping products in early solution studies. In this work, photolysis of the simplest thiophosphoryl azide, F2P(S)N3, in solid noble-gas matrices enabled a first-time spectroscopic (IR and UV-vis) identification of the thiophosphoryl nitrene F2P(S)N in its singlet ground state. Upon visible-light irradiation (≥495 nm), it converts into the thionitroso isomer F2P-N═S, which can also be produced in the gas phase from flash vacuum pyrolysis of F2P(S)N3. Further irradiation of F2P-NS with 365 nm UV light leads to the reformation of F2P(S)N and isomerization to the thiazyl species F2P-S≡N.

  2. Solution phase isomerization of vibrationally excited singlet nitrenes to vibrationally excited 1,2-didehydroazepine.

    Science.gov (United States)

    Burdzinski, Gotard T; Middleton, Chris T; Gustafson, Terry L; Platz, Matthew S

    2006-11-22

    Photolysis of phenyl and o-biphenylyl azide (at 270 nm) releases vibrationally excited singlet nitrene which isomerizes to the corresponding hot 1,2-didehydroazepine at a rate competitive with thermal relaxation. Using ultrafast vibrational spectroscopy we observe the formation of vibrationally excited 1,2-4,6-azacycloheptatetraene (1,2-didehydroazepine) in picoseconds following photolysis of phenyl azide in chloroform and o-biphenylyl azide in acetonitrile at ambient temperature.

  3. Fine structure of the oesophageal and gastric glands of the red ...

    African Journals Online (AJOL)

    maculata Dumeril were studied uSing the electron microscope. The cells of the oesophageal glands contained abundant secretory granules, rough endoplasmic .... The normal human gastric epithelia. A fine structural study. Lab. Invest.

  4. Estimate on the deceleration parameter in a Universe with variable fine structure constant

    CERN Document Server

    Berman, M S; Berman, Marcelo S.; Trevisan, Luis A.

    2001-01-01

    We determine a cosmological model that include a positive acceleration of the Universe and a time decreasing fine structure constant. The present day deceleration parameter is estimated by us, according to our model and the available experimental data .

  5. Tunable, Chemo- and Site-Selective Nitrene Transfer Reactions through the Rational Design of Silver(I) Catalysts.

    Science.gov (United States)

    Alderson, Juliet M; Corbin, Joshua R; Schomaker, Jennifer M

    2017-08-08

    Carbon-nitrogen (C-N) bonds are ubiquitous in pharmaceuticals, agrochemicals, diverse bioactive natural products, and ligands for transition metal catalysts. An effective strategy for introducing a new C-N bond into a molecule is through transition metal-catalyzed nitrene transfer chemistry. In these reactions, a metal-supported nitrene can either add across a C═C bond to form an aziridine or insert into a C-H bond to furnish the corresponding amine. Typical catalysts for nitrene transfer include Rh2Ln and Ru2Ln complexes supported by bridging carboxylate and related ligands, as well as complexes based on Cu, Co, Ir, Fe, and Mn supported by porphyrins and related ligands. A limitation of metal-catalyzed nitrene transfer is the ability to predictably select which specific site will undergo amination in the presence of multiple reactive groups; thus, many reactions rely primarily on substrate control. Achieving true catalyst-control over nitrene transfer would open up exciting possibilities for flexible installation of new C-N bonds into hydrocarbons, natural product-inspired scaffolds, existing pharmaceuticals or biorenewable building blocks. Silver-catalyzed nitrene transfer enables flexible control over the position at which a new C-N bond is introduced. Ag(I) supported by simple N-donor ligands accommodates a diverse range of coordination geometries, from linear to tetrahedral to seesaw, enabling the electronic and steric parameters of the catalyst to be tuned independently. In addition, the ligand, Ag salt counteranion, Ag/ligand ratio and the solvent all influence the fluxional and dynamic behavior of Ag(I) complexes in solution. Understanding the interplay of these parameters to manipulate the behavior of Ag-nitrenes in a predictable manner is a key design feature of our work. In this Account, we describe successful applications of a variety of design principles to tunable, Ag-catalyzed aminations, including (1) changing Ag/ligand ratios to influence

  6. Uncatalyzed thermal gas phase aziridination of alkenes by organic azides. Part I: Mechanisms with discrete nitrene species

    Indian Academy of Sciences (India)

    S PREMILA DEVI; TEJESHWORI SALAM; R H DUNCAN LYNGDOH

    2016-05-01

    Alkene aziridination by azides through uncatalyzed thermal gas phase routes has been studiedusing the DFT B3LYP/6-31G(d,p) method, where the possible role of discrete nitrene intermediates is emphasized.The thermal decomposition of azides is studied using the MP2/aug-cc-pVDZ strategy as well. The MP2(but not the B3LYP) results discount the existence of singlet alkylnitrenes where the alkyl group has an α-hydrogen. Addition of the lowest lying singlet and triplet nitrenes R-N (R = H, Me, Ac) to four different alkenesubstrates leading to aziridine formation was studied by the B3LYP method. Singlet nitrenes with alkenes canyield aziridines via a concerted mechanism, where H-N insertion takes place without a barrier, whereas Me-Nshows larger barriers than Ac-N. Methyl substitution in the alkene favors this reaction. Triplet nitrene additionto alkenes is studied as a two-step process, where the initially formed diradical intermediates cyclize to formaziridines by ISC (intersystem crossing) and collapse. Scope for C-C bond rotation in the diradical leads to lossof stereochemical integrity for triplet nitrene addition to cis- and trans-2-butenes. Geometries of the transitionstates in the various reaction steps studied here are described as “early” or “late” in good accordance with theHammond postulate.

  7. Physics book: CRYRING@ESR

    Science.gov (United States)

    Lestinsky, M.; Andrianov, V.; Aurand, B.; Bagnoud, V.; Bernhardt, D.; Beyer, H.; Bishop, S.; Blaum, K.; Bleile, A.; Borovik, At.; Bosch, F.; Bostock, C. J.; Brandau, C.; Bräuning-Demian, A.; Bray, I.; Davinson, T.; Ebinger, B.; Echler, A.; Egelhof, P.; Ehresmann, A.; Engström, M.; Enss, C.; Ferreira, N.; Fischer, D.; Fleischmann, A.; Förster, E.; Fritzsche, S.; Geithner, R.; Geyer, S.; Glorius, J.; Göbel, K.; Gorda, O.; Goullon, J.; Grabitz, P.; Grisenti, R.; Gumberidze, A.; Hagmann, S.; Heil, M.; Heinz, A.; Herfurth, F.; Heß, R.; Hillenbrand, P.-M.; Hubele, R.; Indelicato, P.; Källberg, A.; Kester, O.; Kiselev, O.; Knie, A.; Kozhuharov, C.; Kraft-Bermuth, S.; Kühl, T.; Lane, G.; Litvinov, Yu. A.; Liesen, D.; Ma, X. W.; Märtin, R.; Moshammer, R.; Müller, A.; Namba, S.; Neumeyer, P.; Nilsson, T.; Nörtershäuser, W.; Paulus, G.; Petridis, N.; Reed, M.; Reifarth, R.; Reiß, P.; Rothhardt, J.; Sanchez, R.; Sanjari, M. S.; Schippers, S.; Schmidt, H. T.; Schneider, D.; Scholz, P.; Schuch, R.; Schulz, M.; Shabaev, V.; Simonsson, A.; Sjöholm, J.; Skeppstedt, Ö.; Sonnabend, K.; Spillmann, U.; Stiebing, K.; Steck, M.; Stöhlker, T.; Surzhykov, A.; Torilov, S.; Träbert, E.; Trassinelli, M.; Trotsenko, S.; Tu, X. L.; Uschmann, I.; Walker, P. M.; Weber, G.; Winters, D. F. A.; Woods, P. J.; Zhao, H. Y.; Zhang, Y. H.

    2016-09-01

    The exploration of the unique properties of stored and cooled beams of highly-charged ions as provided by heavy-ion storage rings has opened novel and fascinating research opportunities in the realm of atomic and nuclear physics research. Since the late 1980s, pioneering work has been performed at the CRYRING at Stockholm (Abrahamsson et al. 1993) and at the Test Storage Ring (TSR) at Heidelberg (Baumann et al. 1988). For the heaviest ions in the highest charge-states, a real quantum jump was achieved in the early 1990s by the commissioning of the Experimental Storage Ring (ESR) at GSI Helmholtzzentrum für Schwerionenforschung (GSI) in Darmstadt (Franzke 1987) where challenging experiments on the electron dynamics in the strong field regime as well as nuclear physics studies on exotic nuclei and at the borderline to atomic physics were performed. Meanwhile also at Lanzhou a heavy-ion storage ring has been taken in operation, exploiting the unique research opportunities in particular for medium-heavy ions and exotic nuclei (Xia et al. 2002).

  8. Excitonic fine structure of elongated InAs/InP quantum dots

    Science.gov (United States)

    Zieliński, M.

    2013-10-01

    The bright exciton splitting in nanosystems and its origins are of primary importance for quantum-dot-based entangled-photon-pair generation. In this paper, I investigate excitonic energies and fine structure for million-atom InAs/InP quantum dots using many-body theory in conjunction with the empirical tight-binding method. Whereas the phenomenological theories relate the fine-structure splitting to quantum-dot-shape asymmetry, using an atomistic approach I demonstrate that for certain elongated quantum-dot shapes the bright exciton splitting can be significantly reduced. I demonstrate that strain effects play an essential role as the main contribution to the bright exciton splitting in InAs/InP quantum dots and observe highly reduced fine-structure splitting for high-symmetry quantum dots without wetting layer. I report the “intrinsic” fine-structure splitting, due to the underlying crystal lattice, to be generally significantly larger than the values predicted by the empirical pseudopotential calculations. Finally, I study excitonic properties of alloyed InAsP quantum dots and demonstrate that alloying effects can significantly reduce fine-structure splitting even in significantly elongated quantum dots.

  9. 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 timbre judgments (p musical timbre in CI users.

  10. ESR investigations on ion beam irradiated polycarbonate

    Energy Technology Data Exchange (ETDEWEB)

    Chipara, M.I. (Institute for Physics and Technology of Materials, P.O. Box MG-7, Magurele, Bucharest, R-76900 (Romania)); Grecu, V.V. (University of Bucharest, Faculty of Physics, P.O. Box MG-11, Magurele, Bucharest, R-76900 (Romania)); Notingher, P.V. (University Politehnica of Bucharest, Electrotechnical Faculty, 313, Splaiul Independentei, Str., 77206 Bucharest (Romania)); Romero, J.R. (Universidad Central de Venezuela, Facultad de Ingineria, Dept. de Fisica Aplicada, Ciudad Universitaria, Chaguaramos, Caracas (Venezuela)); Chipara, M.D. (Research Institute for Electrotechnics, 45-47 Tudor Vladimirescu, Bd., Bucharest, R-79623 (Romania))

    1994-06-01

    Electron spin resonance (ESR) investigations with a polycarbonate solid state nuclear detector, irradiated with oxygen ions, are reported. The nature of the paramagnetic defects induced by irradiation is discussed. The temperature dependence of resonance line parameters is studied. From the experimental data, obtained by ESR, spectroscopy, the activation energy for defect recombination, the average isotropic exchange integral between paramagnetic defects as well as the average distance between defects, are estimated. Correlations with latent tracks structure are discussed. ((orig.))

  11. Targeting ESR1-Mutant Breast Cancer

    Science.gov (United States)

    2015-09-01

    AWARD NUMBER: W81XWH-14-1-0359 TITLE: Targeting ESR1-Mutant Breast Cancer PRINCIPAL INVESTIGATOR: Dr. Sarat Chandarlapaty CONTRACTING...31 Aug 2015 4. TITLE AND SUBTITLE Targeting ESR1-Mutant Breast Cancer 5a. CONTRACT NUMBER 5b. GRANT NUMBER W81XWH-14-1-0359 5c. PROGRAM ELEMENT...mutations found in breast cancer using both structural and cell based assays. We have now have evidence for the effects of the most recurrent

  12. ESR dating of the fault rocks

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hee Kwon [Kangwon National Univ., Chuncheon (Korea, Republic of)

    2004-01-15

    Past movement on faults can be dated by measurement of the intensity of ESR signals in quartz. These signals are reset by local lattice deformation and local frictional heating on grain contacts at the time of fault movement. The ESR signals then grow back as a result of bombardment by ionizing radiation from surrounding rocks. The age is obtained from the ratio of the equivalent dose, needed to produce the observed signal, to the dose rate. Fine grains are more completely reset during faulting, and a plot of age vs, grain size shows a plateau for grains below critical size : these grains are presumed to have been completely zeroed by the last fault activity. We carried out ESR dating of fault rocks collected near the Ulzin nuclear reactor. ESR signals of quartz grains separated from fault rocks collected from the E-W trend fault are saturated. This indicates that the last movement of these faults had occurred before the quaternary period. ESR dates from the NW trend faults range from 300ka to 700ka. On the other hand, ESR date of the NS trend fault is about 50ka. Results of this research suggest that long-term cyclic fault activity near the Ulzin nuclear reactor continued into the pleistocene.

  13. Functional-Group-Tolerant, Silver-Catalyzed N-N Bond Formation by Nitrene Transfer to Amines.

    Science.gov (United States)

    Maestre, Lourdes; Dorel, Ruth; Pablo, Óscar; Escofet, Imma; Sameera, W M C; Álvarez, Eleuterio; Maseras, Feliu; Díaz-Requejo, M Mar; Echavarren, Antonio M; Pérez, Pedro J

    2017-02-15

    Silver(I) promotes the highly chemoselective N-amidation of tertiary amines under catalytic conditions to form aminimides by nitrene transfer from PhI═NTs. Remarkably, this transformation proceeds in a selective manner in the presence of olefins and other functional groups without formation of the commonly observed aziridines or C-H insertion products. The methodology can be applied not only to rather simple tertiary amines but also to complex natural molecules such as brucine or quinine, where the products derived from N-N bond formation were exclusively formed. Theoretical mechanistic studies have shown that this selective N-amidation reaction proceeds through triplet silver nitrenes.

  14. Light-induced ruthenium-catalyzed nitrene transfer reactions: a photochemical approach towards N-acyl sulfimides and sulfoximines.

    Science.gov (United States)

    Bizet, Vincent; Buglioni, Laura; Bolm, Carsten

    2014-05-26

    1,4,2-Dioxazol-5-ones are five-membered heterocycles known to decarboxylate under thermal or photochemical conditions, thus yielding N-acyl nitrenes. Described herein is a light-induced ruthenium-catalyzed N-acyl nitrene transfer to sulfides and sulfoxides by decarboxylation of 1,4,2-dioxazol-5-ones at room temperature, thus providing direct access to N-acyl sulfimides and sulfoximines under mild reaction conditions. In addition, a one-pot sulfur imidation/oxidation sequence catalyzed by a single ruthenium complex is reported. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. N-tosyloxycarbamates as a source of metal nitrenes: rhodium-catalyzed C-H insertion and aziridination reactions.

    Science.gov (United States)

    Lebel, Hélène; Huard, Kim; Lectard, Sylvain

    2005-10-19

    The rhodium-catalyzed decomposition of N-tosyloxycarbamates to generate metal nitrenes which undergo intramolecular C-H insertion or aziridination reaction is described. Aliphatic N-tosyloxycarbamates produce oxazolidinones with high yields and stereospecificity through insertion in benzylic, tertiary, and secondary C-H bonds. Intramolecular aziridination occurs with allylic N-tosyloxycarbamates to produce aziridines as single diastereomers. The reaction proceeds at room temperature using a rhodium catalyst and an excess of potassium carbonate and does not require the use of strong oxidant, such as hypervalent iodine reagents. A rhodium nitrene species is presumably involved, as both reactions are stereospecific.

  16. A simulation for gravity fine structure recovery from high-low GRAVSAT SST data

    Science.gov (United States)

    Estes, R. H.; Lancaster, E. R.

    1976-01-01

    Covariance error analysis techniques were applied to investigate estimation strategies for the high-low SST mission for accurate local recovery of gravitational fine structure, considering the aliasing effects of unsolved for parameters. Surface density blocks of 5 deg x 5 deg and 2 1/2 deg x 2 1/2 deg resolution were utilized to represent the high order geopotential with the drag-free GRAVSAT configured in a nearly circular polar orbit at 250 km. altitude. GEOPAUSE and geosynchronous satellites were considered as high relay spacecraft. It is demonstrated that knowledge of gravitational fine structure can be significantly improved at 5 deg x 5 deg resolution using SST data from a high-low configuration with reasonably accurate orbits for the low GRAVSAT. The gravity fine structure recoverability of the high-low SST mission is compared with the low-low configuration and shown to be superior.

  17. A density functional theory study of the zero-field splitting in high-spin nitrenes

    Science.gov (United States)

    Misochko, Eugenii Ya.; Korchagin, Denis V.; Bozhenko, Konstantin V.; Chapyshev, Sergei V.; Aldoshin, Sergei M.

    2010-08-01

    This work presents a detailed evaluation of the performance of density functional theory (DFT) for the prediction of zero-field splittings (ZFSs) in high-spin nitrenes. A number of well experimentally characterized triplet mononitrenes, quartet nitrenoradicals, quintet dinitrenes, and septet trinitrenes have been considered. Several DFT-based approaches for the prediction of ZFSs have been compared. It is shown that the unrestricted Kohn-Sham and the Pederson-Khanna approaches are the most successful for the estimation of the direct spin-spin (SS) interaction and the spin-orbit coupling (SOC) parts, respectively, to the final ZFS parameters. The most accurate theoretical predictions (within 10%) are achieved by using the PBE density functional in combination with the DZ, EPR-II, and TZV basis sets. For high-spin nitrenes constituted from light atoms, the contribution of the SOC part to ZFS parameters is quite small (7%-12%). By contrast, for chlorine-substituted septet trinitrenes, the contribution of the SOC part is small only to D value but, in the case of E value, it is as large as the SS part and has opposite sign. Due to this partial cancellation of two different contributions, SS and SOC, the resulting values of E in heavy molecules are almost two times smaller than those predicted by analysis of the widely used semiempirical one-center spin-spin interaction model. The decomposition of DSS into n-center (n =1-4) interactions shows that the major contribution to DSS results from the one-center spin-spin interactions. This fact indicates that the semiempirical SS interaction model accurately predicts the ZFS parameters for all types of high-spin nitrenes with total spin S =2 and 3, if their molecules are constructed from the first-row atoms.

  18. Distortion product otoacoustic emission fine-structure: An insight into the ear asymmetries

    Directory of Open Access Journals (Sweden)

    Bhamini Sharma

    2014-01-01

    Full Text Available Context: Use of distortion product otoacoustic emission (DPOAE as a measure of hearing sensitivity is common in clinical practice. However, use of a more informative DPOAE fine-structure has been limited due to non-reliability of DPOAE fine-structure. Aim: The current study was aimed at testing the interaural differences between the DPOAE fine-structure across three age groups. Settings and Design: Acoustically treated room with a calibrated dual channel audiometer (Orbiter 922 along with TDH-39 headphones and B-71 bone vibrator. GSI Tympstar was used for tympanometry and acoustic reflex measurements while ′ILO V6′ OAE analyzer was used for recording of DPOAE and DPOAE fine-structure. Material and Methods : A total of 98 subjects with normal peripheral hearing sensitivity were tested for DPOAE fine-structure. The three age groups consisted of young (8-18 years; n = 50, middle aged (30-40 years; n = 30, and elderly (50-60 years; n = 18. DPOAE fine-structure was studied at 8 points per octave on a total of 25 frequencies from 1000 to 8000 Hz. Statistical Analysis Used: Repeated measure analysis of variance. Results: There was a significant difference (P < 0.05 in the amplitudes at frequencies between 2000 and 3000 Hz. This was evident irrespective of the age groups. There was also a decrease in DPOAE amplitude in elderly group. Conclusions: Interaural asymmetry can be attributed as a reason to these findings and it occurred mostly in the speech perception frequencies. Reduced amplitude of DPAOE in the elderly group can be attributed to presbycusis.

  19. Precision Measurement of the Three 23PJ Helium Fine Structure Intervals

    Science.gov (United States)

    Zelevinsky, T.; Farkas, D.; Gabrielse, G.

    2005-11-01

    The three 23P fine structure intervals of He4 are measured at an improved accuracy that is sufficient to test two-electron QED theory and to determine the fine structure constant α to 14 parts in 109. The more accurate determination of α, to a precision higher than attained with the quantum Hall and Josephson effects, awaits the reconciliation of two inconsistent theoretical calculations now being compared term by term. A low pressure helium discharge presents experimental uncertainties quite different than for earlier measurements and allows direct measurements of light pressure shifts.

  20. A five dimensional model of varying effective gravitational and fine structure constants

    Science.gov (United States)

    Mbelek, J. P.; Lachièze-Rey, M.

    2003-01-01

    We explore the possibility that the reported time variation of the fine structure constant alpha is due to a coupling between electromagnetism and gravitation. We predict such a coupling from a very simple effective theory of physical interactions, under the form of an improved version of the Kaluza-Klein theory. We show that it precisely leads to a variation of the effective fine structure constant with cosmic conditions, and thus with cosmic time. The comparison with the recent data from distant quasars absorption line spectra gives a good agreement; moreover, this may reconcile the claimed results on alpha with the upper limit from the Oklo naturel Uranium fission reactor.

  1. Fine structure in a strong magnetic field: Paschen-Back effect reconsidered in Rydberg atoms

    Science.gov (United States)

    Liu, Wenyu; Gu, Sihong; Li, Baiwen

    1996-05-01

    Using a kind of potential model wave function for alkali metal atoms, we nonperturbatively study the effect of fine structure on the Rydberg spectra of Cs atom in a strong magnetic field. Our numerical results reveal spectral structure dramatically different from the well-established Paschen-Back effect, and we argue that the fine structure of the Rydberg Cs atom cannot be neglected even in a magnetic field as strong as several teslas. We also give an error estimate of our results and a word on possible experimental verification.

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

    DEFF Research Database (Denmark)

    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...

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

    DEFF Research Database (Denmark)

    Reuter, Karen; Hammershøi, Dorte

    2006-01-01

    Otoacoustic emissions (OAEs) are a promising method to monitor early noise-induced hearing losses. When distortion product otoacoustic emissions (DPOAEs) are obtained with a high-frequency resolution, a ripple structure across frequency can be seen, called DPOAE fine structure. In this study DPOA...

  4. Comment on ``Interpretation of the fine structure in the 14C radioactive decay of 223'

    Science.gov (United States)

    Hussonnois, M.; Le Du, J. F.; Brillard, L.; Ardisson, G.

    1991-12-01

    Priority of our interpretation of the fine structure in the 14C radioactive decay of 223Ra is asserted. It seems that the deformation parameter values, used in the framework of ARM to interpret properties of both 223Ra ground and excited states, partly allow for the qualitative interpretation of the experimental hindrance factors to the 209Pb states.

  5. 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

    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....

  6. MULTIPLET FINE-STRUCTURE IN THE PHOTOEMISSION OF THE GADOLINIUM AND TERBIUM 5P LEVELS

    NARCIS (Netherlands)

    THOLE, BT; WANG, XD; HARMON, BN; LI, DQ; DOWBEN, PA

    1993-01-01

    Fine structure is observed in the photoemission of the gadolinium and terbium 5p levels. The 5p levels are split into multiplets due to spin-orbit splitting and to Coulomb and exchange interactions with the f shell. The calculated theoretical spectra are in good agreement with the experimental resul

  7. 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.

  8. The plasma processes of some solar radio burst and their fine structures on the time

    Science.gov (United States)

    Ning, Z.-J.; Lu, Q.-K.; Fu, Q.-J.; Yan, Y.

    2003-04-01

    We present three special solar radio bursts or fine structures on the frequency band of 1.00-7.60Ghz. Firstly, we study the type III burst pair, which was recorded by spectrometer 1.00-2.00GHz at National Astronomical Observatory of China on Jan. 05, 1994. A plausible model might be thought that this event could be the observational evidence of two electron beams traveling bi-directions simultanuously due to the acceleration of magnetic reconnection in the corona. Secondly, a fine structure of microwave type IV bursts is microwave type M-burst on May 03 1999. Partial N-burst, which is a fine structure of solar III-V bursts recorded on August 251999 by both separated spectrometers 4.50-7.50 GHz at Purple Mountain observatory and 5.20-7.60GHz at NAO respectively, is the third phenomenon studied here. As the N-burst documented before, the last two fine structures are thought to the new observational evidences of electron beam reflected by magnetic mirror in the corona.

  9. Room-Temperature Synthesis of Thiostannates from {[Ni(tren)]2[Sn2S6]}n.

    Science.gov (United States)

    Hilbert, Jessica; Näther, Christian; Weihrich, Richard; Bensch, Wolfgang

    2016-08-15

    The compound {[Ni(tren)]2[Sn2S6]}n (1) (tren = tris(2-aminoethyl)amine, C6H18N4) was successfully applied as source for the room-temperature synthesis of the new thiostannates [Ni(tren)(ma)(H2O)]2[Sn2S6]·4H2O (2) (ma = methylamine, CH5N) and [Ni(tren)(1,2-dap)]2[Sn2S6]·2H2O (3) (1,2-dap = 1,2-diaminopropane, C3H10N2). The Ni-S bonds in the Ni2S2N8 bioctahedron in the structure of 1 are analyzed with density functional theory calculations demonstrating significantly differing Ni-S bond strengths. Because of this asymmetry they are easily broken in the presence of an excess of ma or 1,2-dap immediately followed by Ni-N bond formation to N donor atoms of the amine ligands thus generating [Ni(tren)(amine)](2+) complexes. The chemical reactions are fast, and compounds 2 and 3 are formed within 1 h. The synthesis concept presented here opens hitherto unknown possibilities for preparation of new thiostannates.

  10. Functionalization of single-walled carbon nanotubes with (R-)oxycarbonyl nitrenes.

    Science.gov (United States)

    Holzinger, Michael; Abraham, Juergen; Whelan, Paul; Graupner, Ralf; Ley, Lothar; Hennrich, Frank; Kappes, Manfred; Hirsch, Andreas

    2003-07-16

    Sidewall functionalization of single-walled carbon nanotubes (SWCNTs) via the addition of (R-)oxycarbonyl nitrenes allows for the covalent binding of a variety of different groups such as alkyl chains, aromatic groups, dendrimers, crown ethers, and oligoethylene glycol units. Such additions lead to a considerable increase in the solubility in organic solvents such as 1,1,2,2-tetrachloroethane (TCE), dimethyl sulfoxide (DMSO), and 1,2-dichlorobenzene (ODCB). The highest solubilities of 1.2 mg/mL were found for SWCNT adducts with nitrenes containing crown ether of oligoethylene glycol moieties in DMSO and TCE, respectively. The presence of chelating donor groups within the addends allowed for the complexation of Cu(2+) and Cd(2+). Atomic force microscopy (AFM) and transmission electron microscopy (TEM) revealed that the functionalized tubes form thin bundles with typical diameters of 10 nm. The presence of thin bundles in solution is supported by (1)H NMR spectroscopy. The elemental composition of the functionalized SWCNT was determined by X-ray photoelectron spectroscopy (XPS). The use of Raman and electron absorption spectroscopy (UV/Vis-nIR) showed that the electronic properties of the SWCNTs are mostly retained after functionalization, indicating a low degree of addition within this series of SWCNT derivatives.

  11. Targeting ESR1-Mutant Breast Cancer

    Science.gov (United States)

    2015-09-01

    cell line, biochemical and structural biology techniques to uncover the best candidate drugs for the clinical targeting of these mutants. Targeting...ESR1-­‐Mutant  Breast  Cancer   W81XWH-­‐14-­‐1-­‐0360   4   2. Keywords Estrogen Receptor Acquired Drug Resistance Metastatic Breast...preparations for publication: 1) “ESR1 Somatic Mutations Y537S and D538G Confer Breast Cancer Endocrine Resistance by Stabilizing the Active AF-2 conformation

  12. Time resolved ESR spectroscopy. ESR pulse radiolysis equipment with microsecond time resolution

    Energy Technology Data Exchange (ETDEWEB)

    Beckert, D.; Mehler, K. (Akademie der Wissenschaften der DDR, Leipzig. Zentralinstitut fuer Isotopen- und Strahlenforschung)

    1983-01-01

    Time resolved ESR experiments allow the study of the chemical kinetics as well as spin dynamics of free radicals in the liquid phase. Starting from the physical and chemical requirements the experimental parameters of a universal time resolved ESR spectrometer are derived. The main components of the ESR pulse radiolysis equipment are described and their technical parameters are discussed. By two experimental examples it is shown that at a time resolution of 0.3 ..mu..s a sensitivity of c/sub min/ = 10/sup -6/ mol dm/sup -3/ for simple radical spectra can be achieved.

  13. Analysis list: ESR1 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available ESR1 Breast,Others,Prostate,Uterus + hg19 http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/target/ESR1....1.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/target/ESR1.5.tsv http://dbarchive....biosciencedbc.jp/kyushu-u/hg19/target/ESR1.10.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/colo/ESR1....Breast.tsv,http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/colo/ESR1.Others.tsv,h...ttp://dbarchive.biosciencedbc.jp/kyushu-u/hg19/colo/ESR1.Prostate.tsv,http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/colo/ESR1

  14. Radiation dosimetry by ESR in bone

    Energy Technology Data Exchange (ETDEWEB)

    Gallegos, R. (Universidad de San Agustin de Arequipa (Peru)); Marticorena, B. (Instituto Peruano de Energia Nuclear, Lima)

    1983-05-01

    The absorption speed in bovine bone samples irradiated with a /sup 90/Sr ..beta..-source of 45 mCi is studied with ESR. The signal changes linearly with the absorbed quantity of radiation to a maximum dose of 1.5 x 10/sup 6/ rads. This positive result allows to foresee the use of bone as a radiation dosimeter.

  15. Temporal integration near threshold fine structure - The role of cochlear processing

    DEFF Research Database (Denmark)

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

    structure, but lack a decrease of thresholds with increased pulse duration. The model was extended by including a temporal integrator which introduces a low-pass behavior of the data with different slopes of the predicted threshold curves, producing good agreement with the data. On the basis of the model......The hearing thresholds of normal hearing listeners often show quasi-periodic variations when measured with a high frequency resolution. This hearing threshold fine structure is related to other frequency specific variations in the perception of sound such as loudness and amplitude modulated tones...... at low intensities. The detection threshold of a pulsed tone also depends not only on the pulse duration, but also on the position of its frequency within threshold fine structure. The present study investigates if psychoacoustical data on detection of a pulsed tone can be explained with a nonlinear...

  16. Solar Cycle Fine Structure and Surface Rotation from Ca II K-Line Time Series Data

    Science.gov (United States)

    Scargle, Jeff; Keil, Steve; Worden, Pete

    2011-01-01

    Analysis of three and a half decades of data from the NSO/AFRL/Sac Peak K-line monitoring program yields evidence for four components to the variation: (a) the solar cycle, with considerable fine structure and a quasi-periodicity of 122.4 days; (b) a stochastic process, faster than (a) and largely independent of it, (c) a quasi-periodic signal due to rotational modulation, and of course (d) observational errors (shown to be quite small). Correlation and power spectrum analyses elucidate periodic and aperiodic variation of these chromospheric parameters. Time-frequency analysis is especially useful for extracting information about differential rotation, and in particular elucidates the connection between its behavior and fine structure of the solar cycle on approximately one-year time scales. These results further suggest that similar analyses will be useful at detecting and characterizing differential rotation in stars from stellar light-curves such as those being produced at NASA's Kepler observatory.

  17. TEM and HREM study on the fine structure and the interfacial structure of bainite

    Institute of Scientific and Technical Information of China (English)

    李凤照; 敖青; 顾英妮; 姜江; 孙东升; 戴吉岩; 彭红樱

    1996-01-01

    The fine structure of bainite,the morphology and distribution of carbide in steels and the morphology of bainite in Cu-Zn-Al alloys have been investigated with TEM.The interfacial structure ledges and interfacial crystal lattice images of Cu-Zn-Al alloys have also been investigated with HREM.The addition of alloying microelements can fine the structure of bainitic ferrite markedly.The bainitic ferrite is composed of subunits or subchunks.The carbides differ in morphologies and are distributed in between laths,inside the plates and on the boundaries of subunits.There are abundant fine structures in bainitic ferrite.In the primary bainite of Cu-Zn-Al alloy there are interfacial structure ledges,the height of which is about 3 -40 nm,equal to 15-200 atomic layers.The phase transformation mechanism of bainite is discussed.

  18. Precision Measurements: Testing the Time Variation of the Fine Structure Constant

    Science.gov (United States)

    Lamoreaux, Steve

    2004-05-01

    Often, precision measurements from diverse fields can be used to learn new facts about the universe. The usual definition of "precision" is based on improvements over previous measurements. A review of the present state of knowledge regarding the possible time variation of the fine structure constant α will be presented; "precise" data from natural phenomena, which include an apparent shift in the red-shift-scaled fine structure in the absorption spectra of quasar light, and the isotopic abundances in the fission products of a prehistoric natural reactor in Oklo, Gabon. Prospects to improve the accuracy for the constancy of α with laboratory experiments will be discussed. Our two experimental investigations currently being developed are based on optical spectroscopy of trapped ions and on radiofrequency spectroscopy of an atomic dysprosium beam. A sensitivity of dotα/α≈ 10-18/yr is anticipated. Because this accuracy exceeds that by which the second is defined, these measurements will necessarily be differential.

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

    Energy Technology Data Exchange (ETDEWEB)

    Naftel, S.J.; Coulthard, I.; Hu, Y.; Sham, T.K.; Zinke-Allmang, M. [Univ. of Western Ontario, London, Ontario (Canada)

    1998-12-31

    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{sub 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{sub 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{sub 2}. Both the spectroscopy and materials characterization aspects of XAFS (X-ray absorption fine structures) are discussed.

  20. Exciton fine structure splitting in InP quantum dots in GaInP.

    Science.gov (United States)

    Ellström, C; Seifert, W; Pryor, C; Samuelson, L; Pistol, M-E

    2007-07-25

    We have investigated the electronic structure of excitons in InP quantum dots in GaInP. The exciton is theoretically expected to have four states. Two of the states are allowed to optically decay to the ground (vacuum) state in the dipole approximation. We see these two lines in photoluminescence (PL) experiments and find that the splitting between the lines (the fine structure splitting) is 150(± 30) µeV. The lines were perpendicularly polarized. We verified that the lines arise from neutral excitons by using correlation spectroscopy. The theoretical calculations show that the polarization of the emission lines are along and perpendicular to the major axis of elongated dots. The fine structure splitting depends on the degree of elongation of the dots and is close to zero for dots of cylindrical symmetry, despite the influence of the piezoelectric polarization, which is included in the calculation.

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

    Science.gov (United States)

    Naumis, Gerardo G.

    2016-04-01

    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.

  2. A five dimensional model of varying effective gravitational and fine structure constants

    CERN Document Server

    Mbelek, J P

    2003-01-01

    We explore the possibility that the reported time variation of the fine structure constant $\\alpha$ is due to a coupling between electromagnetism and gravitation. We consider the coupling predicted by a very simple {\\sl effective} theory of physical interactions, under the form of an improved version of the Kaluza-Klein theory. We show that it is precisely expressed by a variation of the effective fine structure constant with cosmic conditions, and thus with cosmic time. We compare the predicted variation with the recent data from distant quasars absorption line spectra: we find a good agreement, which moreover reconcile the claimed results on $\\alpha$ with the upper limit from the Oklo naturel Uranium fission reactor.

  3. How Strongly does Dating Meteorites Constrain the Time-Dependence of the Fine-Structure Constant?

    Science.gov (United States)

    Fujii, Yasunori; Iwamoto, Akira

    We review our argument on the nature of the so-called meteorite constraint on the possible time-dependence of the fine-structure constant, emphasizing that dating meteorites at the present time is different in principle from searching directly for the traces in the past, as in the Oklo phenomenon and the QSO absorption lines. In the related literature, we still find some arguments not necessarily consistent with this difference to be taken properly into account. It does not immediately follow that any model-dependent approaches are useless in practice, though we cannot help suspecting that dating meteorites is no match for the Oklo and the QSO in probing the time-variability of the fine-structure constant, at this moment. Some of the relevance to the QSO data particularly in terms of the scalar field will be discussed.

  4. Constraints on field theoretical models for variation of the fine structure constant

    Science.gov (United States)

    Steinhardt, Charles L.

    2005-02-01

    Recent theoretical ideas and observational claims suggest that the fine structure constant α may be variable. We examine a spectrum of models in which α is a function of a scalar field. Specifically, we consider three scenarios: oscillating α, monotonic time variation of α, and time-independent α that is spatially varying. We examine the constraints imposed upon these theories by cosmological observations, particle detector experiments, and “fifth force” experiments. These constraints are very strong on models involving oscillation but cannot compete with bounds from the Oklo subnuclear reactor on models with monotonic timelike variation of α. One particular model with spatial variation is consistent with all current experimental and observational measurements, including those from two seemingly conflicting measurements of the fine structure constant using the many multiplet method on absorption lines.

  5. Fine-structure-resolved laser-photodetachment electron spectroscopy of In{sup {minus}}

    Energy Technology Data Exchange (ETDEWEB)

    Williams, W.W.; Carpenter, D.L.; Covington, A.M.; Thompson, J.S. [Department of Physics and Chemical Physics Program, University of Nevada, Reno, Nevada, 89557-0058 (United States); Kvale, T.J. [Department of Physics and Astronomy, University of Toledo, Toledo, Ohio, 43606-3390 (United States); Seely, D.G. [Department of Physics, Albion College, Albion, Michigan, 49224 (United States)

    1998-11-01

    The electron affinity of indium has been measured using the laser-photodetachment electron spectroscopy technique. Fine-structure-resolved photoelectron kinetic energy spectra of In{sup {minus}} were analyzed and the electron affinity of In({sup 2}P{sub 1/2}) was determined to be 0.404{plus_minus}0.009 eV. The fine-structure splittings in the ground state of In{sup {minus}}({sup 3}P{sub 0,1,2}) were determined to be 0.076{plus_minus}0.009 eV (J=0{r_arrow}J=1) and 0.175{plus_minus}0.009 eV (J=0{r_arrow}J=2). This measurement is compared to several recent calculations of the electron affinity of indium. {copyright} {ital 1998} {ital The American Physical Society}

  6. Origin of fine structure of the giant dipole resonance in sd-shell nuclei

    CERN Document Server

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

    2014-01-01

    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 sd-shell nuclei. Understanding is provided by state-of-the-art theoretical Random Phase Approximation (RPA) calculatios 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 to extract significant scales both in the data and calculations characterizing the fine structure of the GDR. The fair agreement supports that the fine structure arises from ground-state deformation driven by alpha clustering.

  7. Fine structural analysis of the stinger in venom apparatus of the scorpion Euscorpius mingrelicus (Scorpiones: Euscorpiidae

    Directory of Open Access Journals (Sweden)

    N Yigit

    2010-01-01

    Full Text Available In this study, the morphology, histology and fine structure of the stinger, a part of the venom apparatus of Euscorpius mingrelicus (Kessler, 1874 (Scorpiones: Euscorpiidae were studied by light microscopy and transmission electron microscopy (TEM. The stinger, located at the end section of the telson, is sickle-shaped. The venom is ejected through a pair of venom pores on its subterminal portion. Both venom ducts extend along the stinger without contact with each other since they are separated by connective tissue cells. The stinger cuticle is composed of two layers. Additionally, there are many pore canals and some hemolymph vessels in the cuticle. This work constitutes the first histological and fine structure study on Euscorpius mingrelicus stinger.

  8. Ab initio self-consistent x-ray absorption fine structure analysis for metalloproteins.

    Science.gov (United States)

    Dimakis, Nicholas; Bunker, Grant

    2006-12-01

    X-ray absorption fine structure is a powerful tool for probing the structures of metals in proteins in both crystalline and noncrystalline environments. Until recently, a fundamental problem in biological XAFS has been that ad hoc assumptions must be made concerning the vibrational properties of the amino acid residues that are coordinated to the metal to fit the data. Here, an automatic procedure for accurate structural determination of active sites of metalloproteins is presented. It is based on direct multiple-scattering simulation of experimental X-ray absorption fine structure spectra combining electron multiple scattering calculations with density functional theory calculations of vibrational modes of amino acid residues and the genetic algorithm differential evolution to determine a global minimum in the space of fitting parameters. Structure determination of the metalloprotein active site is obtained through a self-consistent iterative procedure with only minimal initial information.

  9. The fine structure of Garnia gonadati and its association with the host cell.

    Science.gov (United States)

    Diniz, J A; Silva, E O; Lainson, R; de Souza, W

    2000-12-01

    Most of the studies on the fine structure of protozoa of the Apicomplexa group have been carried out with members of the ToxoPlasma, Eimeria, and Plasmodium genera. In the present study we analyzed the fine structure of Garnia gonadoti parasitizing the red blood cells of the Amazonian reptile Gonatodes humeralis (Reptilia; Lacertilia). Transmission electron microscopy of thin sections showed that G. gonadoti presented all structures characteristic of the group, including the apicoplast. However, four special features were observed: (1) absence of the hemozoin (malarial) pigment; (2) a group of microtubules associated with the mitochondrion; (3) a vacuole containing electron-dense material, which resembled the acidocalcisome described in trypanosomatids; and (4) a special array of the host-cell endoplasmic reticulum around the parasitophorous vacuole.

  10. 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.)

  11. How strongly does dating meteorites constrain the time-dependence of the fine-structure constant?

    CERN Document Server

    Fujii, Y; Fujii, Yasunori; Iwamoto, Akira

    2005-01-01

    We review our argument on the nature of the so-called meteorite constraint on the possible time-dependence of the fine-structure constant, emphasizing that dating meteorites at the present time is different in principle from searching directly for the traces in the past, as in the Oklo phenomenon and the QSO absorption lines. In the related literature, we still find some arguments not necessarily consistent with this difference to be taken properly into account. This does not imply that any of the model-dependent approaches are useless in practice, though we cannot help guessing that dating meteorites is no match for the Oklo and the QSO in probing time-dependence of the fine-structure constant, at this moment. Some of the relevance to the QSO data particularly in terms of the scalar field will be discussed.

  12. Energies, fine structures and transition wavelengths of the core-excited states in Be * ions

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The fine structures of doubly excited resonances of lithium-like beryllium are calculated using the saddle-point and saddle-point complex-rotation methods. A restricted variational method is used to obtain a more accurate value for the nonrelativistic energy. Relativistic and mass polarization corrections to the resonance energy are included. Transition wavelengths are also calculated and compared with other theories and experimental results.

  13. Is there correlation between fine structure and dark energy cosmic dipoles?

    Science.gov (United States)

    Mariano, Antonio; Perivolaropoulos, Leandros

    2012-10-01

    We present a detailed analysis (including redshift tomography) of the cosmic dipoles in the Keck+VLT quasar absorber and in the Union2 SnIa samples. We show that the fine structure constant cosmic dipole obtained through the Keck+VLT quasar absorber sample at 4.1σ level is anomalously aligned with the corresponding dark energy dipole obtained through the Union2 sample at 2σ level. The angular separation between the two dipole directions is 11.3°±11.8°. We use Monte Carlo simulations to find the probability of obtaining the observed dipole magnitudes with the observed alignment, in the context of an isotropic cosmological model with no correlation between dark energy and fine structure constant α. We find that this probability is less than one part in 106. We propose a simple physical model (extended topological quintessence) which naturally predicts a spherical inhomogeneous distribution for both dark energy density and fine structure constant values. The model is based on the existence of a recently formed giant global monopole with Hubble scale core which also couples nonminimally to electromagnetism. Aligned dipole anisotropies would naturally emerge for an off-center observer for both the fine structure constant and for dark energy density. This model smoothly reduces to ΛCDM for proper limits of its parameters. Two predictions of this model are (a) a correlation between the existence of strong cosmic electromagnetic fields and the value of α and (b) the existence of a dark flow on Hubble scales due to the repulsive gravity of the global defect core (“Great Repulser”) aligned with the dark energy and α dipoles. The direction of the dark flow is predicted to be towards the spatial region of lower accelerating expansion. Existing data about the dark flow are consistent with this prediction.

  14. 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.

  15. Photoconductivity measurement of polymers by x-ray absorption fine structure

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    Photoconductivity spectra measurement of polymers at x-ray energies around the Zn and Co K edges,shows obvious x-ray absorption fine structure oscillations.The photoconductivity spectra obtained for gapped and sandwiched electrode geometric samples,indicate that the shape of photoconductivity spectrum depends on the electrode configuration of the samples.The thickness of the conduction layer can be estimated from the photoconductivity spectrum.

  16. The Anthropic Principle and numerical coincidences involving the cosmological, gravitational and fine structure constants

    CERN Document Server

    Eaves, Laurence

    2014-01-01

    Christian Beck has proposed a set of Shannon-Khinchin axioms to derive a formula for the cosmological constant, {\\Lambda}. We discuss this result in relation to numerical coincidences involving the measured values of {\\Lambda} and the gravitational and fine structure constants, G and {\\alpha}. The empirical formulae that inter-relate the three constants suggest that the measured values of G and {\\Lambda} are consistent with the apparent anthropic fine-tuning of {\\alpha}.

  17. 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.

  18. HRTS observations of the fine structure and dynamics of the solar chromosphere and transition zone

    Science.gov (United States)

    Dere, K. P.

    1983-01-01

    Arc-second UV observations of the Sun by the NRL High Resolution Telescope and Spectrograph (HRTS) have led to the discovery of dynamic fine structures such as 400 km/s coronal jets and chromospheric jets (spicules) and have provided new information about the structure and dynamics of the transition zone. These observations are reviewed and their relevance to the origin of the solar wind is discussed.

  19. Fine Structure Constant, Domain Walls, and Generalized Uncertainty Principle in the Universe

    Directory of Open Access Journals (Sweden)

    Luigi Tedesco

    2011-01-01

    Full Text Available We study the corrections to the fine structure constant from the generalized uncertainty principle in the spacetime of a domain wall. We also calculate the corrections to the standard formula to the energy of the electron in the hydrogen atom to the ground state, in the case of spacetime of a domain wall and generalized uncertainty principle. The results generalize the cases known in literature.

  20. An extended anomalous fine structure of X-ray quasi-Bragg diffuse scattering from multilayers

    CERN Document Server

    Chernov, V A; Mytnichenko, S V

    2001-01-01

    An X-ray quasi-Bragg diffuse scattering anomalous fine structure technique was probed near the absorption Ni K-edge to study the interfacial structure of the Ni/C multilayer deposited by the laser ablation. Like other combinations of the EXAFS and diffraction techniques, this method has a spatial selectivity and was shown qualitatively to provide atomic structural information from the mixed interfacial layers. The possibilities and advantages of this technique are discussed.

  1. Re/Os Constraint on the Time Variability of the Fine-Structure Constant

    Science.gov (United States)

    Fujii, Yasunori; Iwamoto, Akira

    2003-12-01

    We argue that the accuracy by which the isochron parameters of the decay 187Re→187Os are determined by dating iron meteorites may constrain the possible time dependence of the decay rate and hence of the fine-structure constant α, not directly but only in a model-dependent manner. From this point of view, some of the attempts to analyze the Oklo constraint and the results of the quasistellar-object absorption lines are reexamined.

  2. Re/Os constraint on the time-variability of the fine-structure constant

    CERN Document Server

    Fujii, Y; Fujii, Yasunori; Iwamoto, Akira

    2003-01-01

    We argue that the accuracy by which the isochron parameters of the decay $^{187}{\\rm Re}\\to ^{187}{\\rm Os}$ are determined by dating iron meteorites may not directly constrain the possible time-dependence of the decay rate and hence of the fine-structure constant $\\alpha$. From this point of view, some of the attempts to analyze the Oklo constraint and the results of the QSO absorption lines are re-examined.

  3. 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.

  4. Time variation of the fine structure constant in the early universe and the Bekenstein model

    CERN Document Server

    Mosquera, Mercedes E; Landau, Susana J; Vucetich, Hector

    2007-01-01

    We use observational primordial abundances of $\\De$, $\\Het$, $\\He$ and $\\Li$, recent data from the Cosmic Microwave Background and the 2dFGRS power spectrum, to put limits on the variation of the fine structure constant in the early universe. Furthermore, we use these constraints together with other astronomical and geophysical bounds from the late universe to test Bekenstein's model for the variation of $\\alpha$. The model is not able to fit all observational and experimental data.

  5. 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)

  6. Cosmological implications in electrodynamics due to variations of the fine structure constant

    CERN Document Server

    Martínez-Ledesma, J L

    2002-01-01

    Astronomical observations are strongly suggesting that the fine structure constant varies cosmologically. We present an analysis on the consequences that this variations might induce on the electromagnetic field as a whole. We show that under this circumstances the electrodynamics in vacuum of the universe are described by two fields, the ``standard'' Maxwell's field and a new scalar field. We provide a generalized Lorentz force which can be used to test our results experimentally.

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

    Energy Technology Data Exchange (ETDEWEB)

    Pentlehner, D.; Slenczka, A., E-mail: alkwin.slenczka@chemie.uni-regensburg.de [Institut für Physikalische und Theoretische Chemie, Universität Regensburg, 93040 Regensburg (Germany)

    2015-01-07

    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{sup −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.

  8. Complete study of excitonic fine-structure splitting in GaN/AlN quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Hoenig, Gerald; Winkelnkemper, Momme; Schliwa, Andrei; Hoffmann, Axel; Bimberg, Dieter [Institut fuer Festkoerperphysik, Technische Universitaet Berlin (Germany); Kindel, Christian [Institut fuer Festkoerperphysik, Technische Universitaet Berlin (Germany); Research Center for Advanced Science and Technology, University of Tokyo (Japan); Kako, Satoshi [Institute for Nano Quantum Information Electronics, University of Tokyo (Japan); Kawano, Takeshi; Oishi, Hiroaki [Research Center for Advanced Science and Technology, University of Tokyo (Japan); Arakawa, Yasuhiko [Research Center for Advanced Science and Technology, University of Tokyo (Japan); Institute for Nano Quantum Information Electronics, University of Tokyo (Japan); Institute of Industrial Science, University of Tokyo, Komaba, Meguro, Tokyo (Japan)

    2010-07-01

    A detailed understanding of the excitonic fine structure in quantum dots (QDs) is indispensable for their use in quantum cryptography devices. While the fine structure in As-based QDs has been studied extensively, there is a lack of such investigations for N-based QDs, which might operate at room temperature. We present the first complete study of excitonic fine-structure splitting (FSS) in GaN/AlN QDs. Our experimental studies reveal a huge FSS of up to 7 meV with a strong dependence on the emission energy inverse to that in As-based QDs. Our theoretical studies, performed with a configuration-interaction method based on realistic 8-band-k.p Hartree-Fock states, confirm the experimental results and identify the origin of FSS as lattice strain induced. Based on our results it is possible to induce a strain gradient (by micro mechanic techniques or structuring methods), which will reduce the FSS to zero for the emission of entangled photon pairs.

  9. Considering distortion product otoacoustic emission fine structure in measurements of the medial olivocochlear reflex.

    Science.gov (United States)

    Abdala, Carolina; Mishra, Srikanta K; Williams, Tracy L

    2009-03-01

    In humans, when the medial olivocochlear (MOC) pathway is activated by noise in the opposite ear, changes in distortion product otoacoustic emission (DPOAE) level, i.e., the MOC reflex, can be recorded in the test ear. Recent evidence suggests that DPOAE frequency influences the direction (suppression/enhancement) of the reflex. In this study, DPOAEs were recorded at fine frequency intervals from 500 to 2500 Hz, with and without contralateral acoustic stimulation (CAS) in a group of 15 adults. The MOC reflex was calculated only at DPOAE frequencies corresponding to peaks in the fine structure. Additionally, inverse fast-Fourier transform was conducted to evaluate MOC effects on individual DPOAE components. Results show the following: (1) When considering peaks only, the mean MOC reflex was -2.05 dB and 97% of observations reflected suppression, (2) CAS reduced distortion characteristic frequency component levels more than overlap component levels, and (3) CAS produced an upward shift in fine structure peak frequency. Results indicate that when the MOC reflex is recorded at DPOAE frequencies corresponding to fine structure maxima (i.e., when DPOAE components are constructive and in phase), suppression is reliably observed and level enhancement, which probably reflects component mixing in the ear canal rather than strength of the MOC reflex, is eliminated.

  10. Strong limit on the spatial and temporal variations of the fine-structure constant

    Science.gov (United States)

    Le, T. D.

    2016-10-01

    Observed spectra of quasars provide a powerful tool to test the possible spatial and temporal variations of the fine-structure constant α = e 2/ћc over the history of the Universe. It is demonstrated that high sensitivity to the variation of α can be obtained from a comparison of the spectra of quasars and laboratories. We reported a new constraint on the variation of the fine-structure constant based on the analysis of the optical spectra of the fine-structure transitions in [NeIII], [NeV], [OIII], [OI] and [SII] multiplets from 14 Seyfert 1.5 galaxies. The weighted mean value of the α-variation derived from our analysis over the redshift range 0.035 < z < 0.281 Δα/α= (4.50 +/- 5.53) \\times 10-5. This result presents strong limit improvements on the constraint on Δα/α compared to the published in the literature

  11. 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.

  12. Photografting of perfluoroalkanes onto polyethylene surfaces via azide/nitrene chemistry

    Science.gov (United States)

    Siegmann, Konstantin; Inauen, Jan; Villamaina, Diego; Winkler, Martin

    2017-02-01

    The purpose of this study is to render polyethylene surfaces strongly and permanently hydrophobic. Polyethylene is a common plastic and, because of its inertness, difficult to graft. We chose polyethylene as example because of its ubiquity and model character. As graft chains linear perfluoroalkyl residues (-C4F9, -C6F13, -C8F17 and -C10F21) were chosen, and photografting was selected as grafting method. Photolytically generated nitrenes can insert into carbon-hydrogen bonds and are therefore suited for binding to polyethylene. Hydrophobic photo reactive surface modifiers based on azide/nitrene chemistry are designed, synthesized in high yield and characterized. Four new molecules are described. Water contact angles exceeding 110° were achieved on grafted polyethylene. One problem is to demonstrate that the photografted surface modifiers are bound covalently to the polyethylene. Abrasion tests show that all new molecules, when photografted to polyethylene, have a higher abrasion resistance than a polyethylene surface coated with a long-chain perfluoroalkane. Relative abrasion resitances of 1.4, 2.0, 2.1 and 2.5 compared to the fluoroalkane coating were obtained for the four compounds. An abrasion model using ice is developed. Although all four compounds have the same λmax of 266 nm in acetonitrile solution, their molar extincition coefficients increase from 1.6·104 to 2.2·104 with increasing length of the fluorotelomer chain. Exitonic coupling of the chromophores of the surface modifiers is observed for specific molecules in the neat state. A linear correlation of water contact angle with fluorine surface content, as measured by photoelectron spectroscopy, in grafted polyethylene surfaces is established.

  13. Persistent free radical ESR signals in marine bivalve tissues. [Electron Spin Resonance (ESR)

    Energy Technology Data Exchange (ETDEWEB)

    Mehlorn, R.J. (California Univ., Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering); Mendez, A.T. (Fundacion Educativa Ana G. Mendez, Rio Piedras (Puerto Rico)); Higashi, R. (California Univ., Bodega Bay, CA (United States). Bodega Marine Lab.); Fan, T. (California Univ., Davis, CA (United States))

    1992-08-01

    Freeze-dried homogenates of the oyster Crassostrea rhizophorae collected from waters in Puerto Rico near urban and industrial sites as well as at relatively pristine locations yielded electron spin resonance (ESR) spectra characteristic of free radicals as well as spectral components of transition metal ions, dominated by manganese. The magnitudes of these ESR signals and the concentrations of trace elements (determined by X-ray fluorescence) varied considerably among oyster samples, masking any potential correlation with polluted waters. Laboratory studies were initiated to identify the factors controlling the magnitudes of the tissue free radical ESR signals. Another mollusc, Mytilus californianus collected at the Bodega Marine laboratory in northern California, was fractionated into goneds and remaining tissue. Freeze-dried homogenates of both fractions exhibited ESR signals that increased gradually with time. ESR signals were observed in freeze-dried perchloric acid (PCA) precipitates of the homogenates, delipidated PCA precipitates, and in chloroform extracts of these precipitates. Acid hydrolysis to degrade proteins to amino acids produced a residue, which yielded much larger ESR free radical signals after freeze-drying. Freshly thawed homogenates of Crassostrea rhizophorae also exhibited ESR signals. A laboratory model of copper stress in Crassostrea rhizophorae was developed to study the effect of this transition metal on dssue free radicals. Preliminary results suggested that sublethal copper exposure had little effect on tissue fire radicals, except possibly for a signal enhancement in an oyster fraction that was enriched in kidney granules. Since kidney granules are known to accumulate heavy metals in mussels and probably other marine bivalves, this signal enhancement may prove to be an indicator of free radical processes associated with heavy metal deposition in molluscs.

  14. ESR study of free radicals in mango

    Science.gov (United States)

    Kikuchi, Masahiro; Hussain, Mohammad S.; Morishita, Norio; Ukai, Mitsuko; Kobayashi, Yasuhiko; Shimoyama, Yuhei

    2010-01-01

    An electron spin resonance (ESR) spectroscopic study of radicals induced in irradiated fresh mangoes was performed. Mangoes in the fresh state were irradiated with γ-rays, lyophilized and then crushed into a powder. The ESR spectrum of the powder showed a strong main peak at g = 2.004 and a pair of peaks centered at the main peak. The main peak was detected from both flesh and skin specimens. This peak height gradually decreased during storage following irradiation. On the other hand, the side peaks showed a well-defined dose-response relationship even at 9 days post-irradiation. The side peaks therefore provide a useful means to define the irradiation of fresh mangoes.

  15. A new approach to produce amino-carbon nanotubes as plasmid transfection vector by [2 + 1] cycloaddition of nitrenes

    Science.gov (United States)

    Jiang, Yongjian; Jin, Chen; Yang, Feng; Yu, Xianjun; Wang, Guojian; Cheng, Si; Di, Yang; Li, Ji; Fu, Deliang; Ni, Quanxing

    2011-01-01

    Amino-carbon nanotubes (amino-CNTs) can conjugate with the DNA by electrostatic interactions and shuttle the DNA to the cell cytoplasm or even the nucleus. Here we report a new approach to produce amino-CNTs by cycloaddition of nitrenes. Fourier transform infrared spectroscopy was used to verify the success of the functionalization, and the functionalization degree was calculated by thermal gravity analysis. Transmission electron microscope (TEM) was used to observe the solubility of the CNTs and the interactions of the amino-CNTs with the plasmids. Cell ultrathin sections were made and observed under the TEM to confirm the amino-CNTs enter the cells. Transfection experiments ultimately verify the amino-CNTs produced through cycloadditions of nitrenes can serve as plasmid vector.

  16. Gold-catalyzed synthesis of functionalized pyridines by using 2H-azirines as synthetic equivalents of alkenyl nitrenes.

    Science.gov (United States)

    Prechter, Agnes; Henrion, Guilhem; Faudot dit Bel, Pierre; Gagosz, Fabien

    2014-05-05

    2H-Azirines are easily synthesized from the corresponding ketones and, despite possessing a CN bond embedded in a strained three-membered cycle, they are sufficiently stable to be isolated, stored, and manipulated. 2H-Azirines can be regarded as valuable synthetic equivalents of alkenyl nitrenes, however, reactions capitalizing on the cyclic strain of the heterocyclic motif and involving the cleavage of the CN single bond remain surprisingly limited. A gold-catalyzed reaction that allows the formation of polysubstituted functionalized pyridines from easily accessible 2-propargyl 2H-azirine derivatives was developed. This transformation, which corresponds to an unprecedented intramolecular transfer of an alkenyl nitrene to an alkyne, proceeds with low catalyst loading, is efficient, and exhibits a high functional-group tolerance and a wide substrate scope. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. The ESR Characterization of Oligomeric Thiophene Materials

    Science.gov (United States)

    1994-06-28

    1955). 16 Table 1. Summary of cyclic voltametry results. Table 2. Summary of ESR results. 17 Figure 1. Structures of molecules studied. Figure 2...H20 removal system). The cyclic voltammetry experiments were performed with a potentiostat/galvanostat EG&G model 273 and recorded on an X-Y IBM...Results of cyclic voltammetry measurements are given in Table 1 and representative voltammograms are shown in Figures 2-3. The cyclic voltammetry of 7

  18. Targeting ESR1-Mutant Breast Cancer

    Science.gov (United States)

    2015-09-01

    Introduction Approximately 70% of ER+ breast cancers harbor expression of the estrogen receptor and are dependent upon its activity for various aspects of the...resistance to current FDA approved ER antagonists, but that more potent and selective estrogen receptor antagonists will be sufficiently active to...antagonists and their potency against ER mutants both in vitro and in vivo . Targeting ESR1-Mutant Breast Cancer W81XWH-14-1-0359 9 4. Impact A) Impact

  19. ESR dating at Mezmaiskaya Cave, Russia

    Energy Technology Data Exchange (ETDEWEB)

    Skinner, A.R. [Department of Chemistry, Williams College, Williamstown, MA, 01267 (United States)]. E-mail: anne.r.skinner@williams.edu; Blackwell, B.A.B. [Department of Chemistry, Williams College, Williamstown, MA, 01267 (United States); Martin, Sara [Department of Chemistry, Williams College, Williamstown, MA, 01267 (United States); Ortega, A. [RFK Science Research Institute, Flushing, NY, 11366 (United States); Blickstein, J.I.B. [RFK Science Research Institute, Flushing, NY, 11366 (United States); Golovanova, L.V. [Laboratory of Prehistory, St. Petersburg (Russian Federation); Doronichev, V.B. [Laboratory of Prehistory, St. Petersburg (Russian Federation)

    2005-02-01

    Mezmaiskaya Cave has yielded more than 10,000 artifacts, thousands of very well preserved faunal remains, and hominin remains, found in seven Middle Paleolithic (Mousterian) and three Upper Paleolithic levels. A complete Neanderthal infant skeleton was preserved in anatomical juxtaposition lying on a large limestone block, overlain by the earliest Mousterian layer, Layer 3. Twenty-four skull fragments from a 1-2 year-old Neanderthal infant, showing post-mortem deformation, occurred in a pit originating in the Mousterian Layer 2 and penetrating into underlying layers 2A and 2B(1). Bone from Layer 2A was dated by AMS {sup 14}C at 35.8-36.3{+-}0.5 kyr BP. Direct dating of Neanderthal bone from Layer 3 gave an age of 29 kyr, but that is now considered to be due to contamination by modern carbon. Fourteen large mammal teeth from Layers 2 through 3 have been dated by standard electron spin resonance (ESR). Low U concentrations in both the enamel and dentine ensure that ESR ages do not depend significantly on the U uptake model, but do depend strongly on the sedimentary dose rates. Assuming a sedimentary water concentration equal to 20 wt%, ESR ages for the Mousterian layers range from 36.2 to 73.0{+-}5.0 ka.

  20. ESR identification of gamma-irradiated albendazole

    Science.gov (United States)

    Çolak, Seyda

    2010-01-01

    The use of ionizing radiation for sterilization of pharmaceuticals is a well-established technology. In the present work, the spectroscopic and kinetic features of the radicals induced in gamma-irradiated solid albendazole samples is investigated at different temperatures in the dose range of 3-34 kGy by electron spin resonance (ESR) spectroscopy. Irradiation with gamma radiation produced two different radical species in albendazole. They were fairly stable at room temperature but relatively unstable above room temperature, giving rise to an unresolved ESR spectrum consisting of three resonance peaks centered at g=2.0057. Decay activation energies of the contributing radical species were calculated to be 47.8 (±13.5) and 50.5 (±9.7) kJ/mol using the signal intensity decay data derived from annealing studies performed at high temperatures. A linear function of the applied dose was found to best describe the experimental dose-response data. Albendazole does not present the characteristics of good dosimetric materials. However, the discrimination of irradiated albendazole from its unirradiated form was possible even 6 months after storage in normal conditions. Based on these findings, it is concluded that albendazole and albendazole-containing drugs can be safely sterilized by gamma radiation and that ESR spectroscopy could be successfully used as a potential technique for monitoring their radiosterilization.

  1. Computational study of the Curtius-like rearrangements of phosphoryl, phosphinyl, and phosphinoyl azides and their corresponding nitrenes.

    Science.gov (United States)

    McCulla, Ryan D; Gohar, Gamal A; Hadad, Christopher M; Platz, Matthew S

    2007-12-07

    The free energies of reaction (DeltaG) and activation (DeltaG) were determined for the Curtius-like rearrangement of dimethylphosphinoyl, dimethylphosphinyl, and dimethylphosphoryl azides as well as the corresponding singlet and triplet nitrenes by CBS-QB3 and B3LYP computational methods. From CASSCF calculations, it was established that the closed-shell configuration was the lower energy singlet state for each of these nitrenes. The triplet states of dimethylphosphinyl- and dimethylphosphorylnitrene are the preferred ground states. However, the closed-shell singlet state is the ground state for dimethylphosphinoylnitrene. The CBS-QB3 DeltaG values for the Curtius-like rearrangements of dimethylphosphinyl and dimethylphosphoryl azides were 45.4 and 47.0 kcal mol-1, respectively. For the closed-shell singlet dimethylphosphinyl- and dimethylphosphorylnitrene, the CBS-QB3 DeltaG values for the rate-limiting step of the Curtius-like rearrangement were 22.9 and 18.0 kcal mol-1, respectively. It is unlikely that the nitrenes will undergo a Curtius-like rearrangement because of competing bimolecular reactions that have lower activation barriers. The pharmacology of weaponized organophosphorus compounds can be investigated using phosphorylnitrenes as photoaffinity labels. Dominant bimolecular reactivity is a desirable quality for a photoaffinity label to possess, and thus, the resistance of phosphorylnitrenes to intramolecular Curtius-like rearrangements increases their usefulness as photoaffinity labels.

  2. COLLISIONAL EXCITATION OF THE [C II] FINE STRUCTURE TRANSITION IN INTERSTELLAR CLOUDS

    Energy Technology Data Exchange (ETDEWEB)

    Goldsmith, Paul F.; Langer, William D.; Pineda, Jorge L.; Velusamy, T., E-mail: Paul.F.Goldsmith@jpl.nasa.gov [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States)

    2012-11-15

    We analyze the collisional excitation of the 158 {mu}m (1900.5 GHz) fine structure transition of ionized carbon in terms of line intensities produced by simple cloud models. The single C{sup +} fine structure transition is a very important coolant of the atomic interstellar medium (ISM) and of photon-dominated regions in which carbon is partially or completely in ionized form. The [C II] line is widely used as a tracer of star formation in the Milky Way and other galaxies. Excitation of the [C II] fine structure transition can be via collisions with hydrogen molecules, atoms, and electrons. Analysis of [C II] observations is complicated by the fact that it is difficult to determine the optical depth of the line. We discuss the excitation of the [C II] line, deriving analytic results for several limiting cases and carry out numerical solutions using a large velocity gradient model for a more inclusive analysis. For antenna temperatures up to 1/3 of the brightness temperature of the gas kinetic temperature, the antenna temperature is linearly proportional to the column density of C{sup +} irrespective of the optical depth of the transition. This is appropriately referred to as the effectively optically thin approximation. We review the critical densities for excitation of the [C II] line by various collision partners, briefly analyze C{sup +} absorption, and conclude with a discussion of C{sup +} cooling and how the considerations for line intensities affect the behavior of this important coolant of the ISM.

  3. 3D WHOLE-PROMINENCE FINE STRUCTURE MODELING. II. PROMINENCE EVOLUTION

    Energy Technology Data Exchange (ETDEWEB)

    Gunár, Stanislav; Mackay, Duncan H. [School of Mathematics and Statistics, University of St. Andrews, North Haugh, St. Andrews, KY16 9SS (United Kingdom)

    2015-10-20

    We use the new three-dimensional (3D) whole-prominence fine structure model to study the evolution of prominences and their fine structures in response to changes in the underlying photospheric magnetic flux distribution. The applied model combines a detailed 3D prominence magnetic field configuration with a realistic description of the prominence plasma distributed along multiple fine structures. In addition, we utilize an approximate Hα visualization technique to study the evolution of the visible cool prominence plasma both in emission (prominence) and absorption (filament). We show that the initial magnetic field configuration of the modeled prominence is significantly disturbed by the changing position of a single polarity of a magnetic bipole as the bipole is advected toward the main body of the filament. This leads to the creation of a barb, which becomes the dominant feature visible in the synthetic Hα images of both the prominence and filament views. The evolution of the bipole also creates conditions that lead to the disappearance and reappearance of large portions of the main body. We also show that an arch-like region containing a dark void (a bubble) can be naturally produced in the synthetic prominence Hα images. While not visible in terms of the magnetic field lines, it is due to a lack of Hα emission from low-pressure, low-density plasma located in shallow magnetic dips lying along the lines of sight intersecting the dark void. In addition, a quasi-vertical small-scale feature consisting of short and deep dips, piled one above the other, is produced.

  4. Fine Structure in the Mm-Wavelength Spectra of the Active Region

    Science.gov (United States)

    Sawant, H. S.; Cecatto, J. R.

    1990-11-01

    RESUMEN. Faltan observaciones solares espectrosc6picas en la longitud de onda milimetrica. Hay sugerencias de que se puede superponer una fi na estructura en frecuencia a la componente-S de la regi6n solar activa, asi como a la componente del brote en las longitudes de onda milimetri- cas. Se ha desarrollado un receptor de alta sensibilidad de pasos de frecuencia que opera en el intervalo de 23-18 GHz con una resoluci6n de 1 GHz y resoluci6n de tiempo variable entre 1.2 y 96 sec, usando la an- tena de Itapetinga de 13.7-m para estudiar la estructura fina en frecuencia y tiempo. Discutimos el espectro en longitud de onda-mm en re- giones activas y su evoluci6n en el tiempo. El estudio de Ia evoluci6n en el tiempo de la regi6n activa en AR 5569 observada el 29 de junio de 1989, sugiere la existencia de estructuras finas como funci6n deltiempo. ABSTRACT. There is a lack of mm-wavelength spectroscopic solar observations. There are suggestions that a fine structure in frequency may be superimposed on the S-component of solar active region as well as on the burst component at inm-wavelengths. To study fine structure in frequency and time, a high sensitivity step frequency receiver operating in the frequency range 23-18 GHz with frequency resolution of 1 GHz and variable time resolution 1.2 to 96 sec, using 13.7 m diameter Itapetinga radome covered antenna, has been developed. Here, we discuss mm-wavelength spectra of active regions and their time evolution. Study of time evolution of an active region AR 5569 observed on 29th June, 1989 suggests existence of fine structures as a function of time. ( Ck : SUN-ACTIVITY - SUN-RADIO RADIATION

  5. A Note on Transfinite M Theory and the Fine Structure Constant

    CERN Document Server

    Castro, C

    2001-01-01

    In this short note, using notions from $p$-Adic QFT and $p$-branes, we derive the transfinite M $theoretical$ corrections $(\\alpha_M)^{-1} = 100 + 61 \\phi$ to El Naschie's inverse fine structure constant value $(\\alpha_{HS})^{-1}= 100 + 60\\phi$ which was based on a transfinite Heterotic string theory ormalism . $\\phi$ is the Golden Mean $0.6180339...$. Our results are consistent with recent Astrophysical observations of he Boomerang and Maxima experiments, with previous results based on the four dimensional gravitational conformal anomaly calculations and with an enhanced hierarchy of the number of lines on Del Pezzo surfaces.

  6. 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...... the N atoms remaining in the solid state after H2-reduction are trapped by Cr atoms. Quantitative interpretation in terms of the local distortions around Cr atoms and their N coordination number reveals that no Cr–N clusters or CrN platelets are present....

  7. X-ray reflection anomalous fine structure analysis of the stability of permalloy/copper multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Luo, G.M.; Mai, Z.H.; Hase, T.P.A. E-mail: t.p.a.hase@dur.ac.uk; Fulthorpe, B.D.; Tanner, B.K.; Marrows, C.H.; Hickey, B.J

    2001-05-01

    We report the application of reflection anomalous fine structure analysis to the study of the changes in the layer density and local environment in sputtered permalloy/copper multilayers. By fitting the smoothly varying component of the plot of multilayer Bragg peak intensity versus incident X-ray energy, we find a strained permalloy layer at the permalloy/copper but not the copper/permalloy interface. The density difference between copper and strained permalloy layers increases on annealing at 275 deg. C and from the oscillatory component of the spectrum, we show that it is the nearest-neighbour distance around the Ni atoms which decreases.

  8. Tailoring the exciton fine structure of cadmium selenide nanocrystals with shape anisotropy and magnetic field.

    Science.gov (United States)

    Sinito, Chiara; Fernée, Mark J; Goupalov, Serguei V; Mulvaney, Paul; Tamarat, Philippe; Lounis, Brahim

    2014-11-25

    We use nominally spheroidal CdSe nanocrystals with a zinc blende crystal structure to study how shape perturbations lift the energy degeneracies of the band-edge exciton. Nanocrystals with a low degree of symmetry exhibit splitting of both upper and lower bright state degeneracies due to valence band mixing combined with the isotropic exchange interaction, allowing active control of the level splitting with a magnetic field. Asymmetry-induced splitting of the bright states is used to reveal the entire 8-state band-edge fine structure, enabling complete comparison with band-edge exciton models.

  9. Prospect of China's Auroral Fine-structure Imaging System (CAFIS) at Zhongshan station in Antarctica

    Institute of Scientific and Technical Information of China (English)

    LIU Shun-lin; HAN De-sheng; HU Hong-qiao; HUANG De-hong; ZHANG Bei-chen; YANG Hui-gen

    2008-01-01

    A new auroral imaging system is reported which is planned to be deployed at Zhongshan Station in Antarctica in the end of 2009. The system will focus on study of optical auroras in small scales and be called China' s Auroral Fine-structure Imaging System (CAFIS). The project of CAFIS is carried out by support of 'the tenth five-year plan for capacity building' of China. CAFIS will be a powerful groundbased platform for aurora observational experiments. Composing and advantages of CAFIS are introduced in this brief report. Some potential study topics involved CAFIS are also considered.

  10. Tuning Photoluminescence Energy and Fine Structure Splitting in Single Quantum Dots by Uniaxial Stress

    Institute of Scientific and Technical Information of China (English)

    DOU Xiu-Ming; SUN Bao-Quan; WANG Bao-Rui; MA Shan-Shan; ZHOU Rong; HUANG She-Song; NI Hai-Qiao; NIU Zhi-Chuan

    2008-01-01

    @@ We report a photoluminescence (PL) energy red-shift of single quantum dots(QDs)by applying an in-plane compressive uniaxial stress along the[110]direction at a liquid nitrogen temperature.Uniaxial stress has an effect not only on the confinement potential in the growth direction which results in the PL shift,but also on the cylindrical symmetry of QDs which can be reflected by the change of the full width at half maximum of PL peak.This implies that uniaxial stress has an important role in tuning PL energy and fine structure splitting of QDs.

  11. The fine structure levels for ground states of negative ions of nitrogen and phosphorus

    Directory of Open Access Journals (Sweden)

    Leyla Özdemir

    2013-01-01

    Full Text Available The fine structure levels for negative ions (anions of nitrogen and phosphorus have been investigated using multiconfiguration Hartree-Fock method within the framework of Breit-Pauli Hamiltonian (MCHF+BP. Nitrogen and phosphorus have half-filled outer shell in ground state 1s22s22p3 4S and 1s22s22p33s23p3 4S, respectively. It has been stated in most works that the negative ion of nitrogen is instable whereas the negative ion of phosphorus is stable. The results obtained have been compared with other works.

  12. Enhanced laboratory sensitivity to variation of the fine-structure constant using highly charged ions.

    Science.gov (United States)

    Berengut, J C; Dzuba, V A; Flambaum, V V

    2010-09-17

    We study atomic systems that are in the frequency range of optical atomic clocks and have enhanced sensitivity to potential time variation of the fine-structure constant α. The high sensitivity is due to coherent contributions from three factors: high nuclear charge Z, high ionization degree, and significant differences in the configuration composition of the states involved. Configuration crossing keeps the frequencies in the optical range despite the large ionization energies. We discuss a few promising examples that have the largest α sensitivities seen in atomic systems.

  13. Time Variation of the Fine Structure Constant in the Spacetime of a Cosmic Domain Wall

    Science.gov (United States)

    Campanelli, L.; Cea, P.; Tedesco, L.

    The gravitational field produced by a domain wall acts as a medium with spacetime-dependent permittivity ɛ. Therefore, the fine structure constant α=e2/4πɛ will be a time-dependent function at fixed position. The most stringent constraint on the time-variation of α comes from the natural reactor Oklo and gives |˙ α /α | < few × 10-17 yr-1. This limit constrains the tension of a cosmic domain wall to be less than σ ≲ 10-2 MeV3, and then represents the most severe limit on the energy density of a cosmic wall stretching our Universe.

  14. Time Variation of the Fine Structure Constant in the Spacetime of a Domain Wall

    CERN Document Server

    Campanelli, L; Tedesco, L

    2005-01-01

    The gravitational field produced by a domain wall acts as a medium with spacetime-dependent permittivity \\epsilon. Therefore, the fine structure constant \\alpha = e^2/4 \\pi \\epsilon will be a time-dependent function at fixed position. The most stringent constraint on the time-variation of \\alpha comes from the natural reactor Oklo and gives |\\dot{\\alpha}/\\alpha| < few 10^{-17} yr^{-1}. This limit constrains the tension of a cosmic domain wall to be less than \\sigma \\lesssim 10^{-2} MeV^3, and then represents the most severe limit on the energy density of a cosmic wall stretching our Universe.

  15. 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.

  16. Morphology, fine structure, biochemistry, and function of the spermatic ducts in marine fish.

    Science.gov (United States)

    Lahnsteiner, Franz

    2003-10-01

    The spermatic ducts and the testicular efferent ducts were investigated in different marine teleost fish species (Diplodus sargus, Mullus barbatus, Thalassoma pavo, Trachinus draco, Uranuscopus scaber, Sparisoma cretense, Synodon saurus). From the morphological, histological, fine structural and biochemical investigations it appeared that the testicular main ducts and spermatic ducts of the investigated marine fish have the following functions: storage of spermatozoa, monosacharide synthesis for nutrition of spermatozoa, synthesis of steroid glucuronides, synthesis of seminal plasma proteins, formation of a ionic gradient in the seminal fluid and phagocytotic activity. Species-specific differences were only found in the morphology of the gonads and in the histology of the spermatic duct epithelium.

  17. Anisotropic Beam Model for the Spectral Observations of Radio Burst Fine Structures on 1998 April 15

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A fine structure consisting of three almost equidistant frequency bands was observed in the high frequency part of a solar burst on 1998 April 15 by the spectrometer of Beijing Astronomical Observatory in the range 2.6-3.8 GHz. A model for this event based on beam-anisotropic instability in the solar corona is presented. Longitudinal plasma waves are excited at cyclotron resonance and then transformed into radio emission at their second harmonic. The model is in accordance with the observations if we suppose a magnetic field strength in the region of emission generation of about 200 G.

  18. The fine structure of muscle attachments in a spider (Latrodectus mactans, Fabr.).

    Science.gov (United States)

    Smith, D S; Järlfors, U; Russell, F E

    1969-01-01

    The fine structure of a spider myo-apodeme junction is described, and discussed in terms of other arthropod muscle attachments. This is contrasted with the situation in the venom gland, equipped with muscle fibers that control expulsion of the secreted material. The latter involves a cell-free collagenous matrix, lying between the muscle cells and the sheath of the gland. As in other arthropods, skeletal fibers are attached to the apodeme cuticle via specialized epidermal cells, containing oriented microtubules. Interdigitations between these cells and muscle, basally, and cuticle, apically, are described. Extracellular tonofibrillae described elsewhere are inconspicuous in the apodeme cuticle.

  19. Calculation of the fine structure of the level in Rydberg state of lithium

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The level shift and level formula of lithium atom in Rydberg states are achieved by means of the calculation of polarization of the atomic core (including the contribution of dipole moment, quadrupole moment and octupole moment);meanwhile, the effect of relativity theory, the orbital angular momentum L and the spin angular momentum S coupling (LS coupling), and high order correction of the effective potential are considered. The some fine structures (N=5~12,L=4~9,J=L±1/2) and the corresponding level intervals in Rydberg states can be calculated by the above-mentioned level formula and compared with correlated experimental data.

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

    CERN Document Server

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

    2015-01-01

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

  1. Oklo Constraint on the Time-Variability of the Fine-Structure Constant

    CERN Document Server

    Fujii, Y

    2003-01-01

    The Oklo phenomenon, natural fission reactors which had taken place in Gabon about 2 billion years ago, porvides one of the most stringent constraints on the possible time-variability of the fine-structure constant $\\alpha$. We first review briefly what it is and how reliable it is in constraining $\\alpha$. We then compare the result with a more recent result on the nonzero change of $\\alpha$ obtained from the observation of the QSO absoorption lines. We suggest a possible way to make these results consistent with each other in terms of the behavior of a scalar field which is expected to be responsible for the accelaration of the universe.

  2. Oklo Constraint on the Time-Variabilityof the Fine-Structure Constant

    Science.gov (United States)

    Fujii, Yasunori

    The Oklo phenomenon, natural fission reactors which had taken place in Gabon about 2 billion years ago, provides one of the most stringent constraints on the possible time-variability of the fine-structure constant . We first review briefly what it is and how reliable it is in constraining . We then compare the result with a more recent result on the nonzero change of obtained from the observation of the QSO absorption lines. We suggest a possible way to make these results consistent with each other in terms of the behavior of a scalar field which is expected to be responsible for the acceleration of the universe.

  3. Time Evolution of the Fine Structure Constant in a Two-Field Quintessence Model

    CERN Document Server

    Bento, M C; Santos, N M C

    2004-01-01

    We examine the variation of the fine structure constant in the context of a two-field quintessence model. We find that, for solutions that lead to a transient late period of accelerated expansion, it is possible to fit the data arising from quasar spectra and comply with the bounds on the variation of $\\alpha$ from the Oklo reactor, meteorite analysis, atomic clock measurements, Cosmic Microwave Background Radiation and Big Bang Nucleosynthesis. That is more difficult if we consider solutions corresponding to a late period of permanent accelerated expansion.

  4. Time evolution of the fine structure constant in a two-field quintessence model

    Science.gov (United States)

    Bento, M. C.; Bertolami, O.; Santos, N. M.

    2004-11-01

    We examine the variation of the fine structure constant in the context of a two-field quintessence model. We find that, for solutions that lead to a transient late period of accelerated expansion, it is possible to fit the data arising from quasar spectra and comply with the bounds on the variation of α from the Oklo reactor, meteorite analysis, atomic clock measurements, cosmic microwave background radiation, and big bang nucleosynthesis. That is more difficult if we consider solutions corresponding to a late period of permanent accelerated expansion.

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

    Directory of Open Access Journals (Sweden)

    C.J.A.P. Martins

    2015-04-01

    Full Text Available 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.

  6. Variation of the fine-structure constant from the de Sitter invariant special relativity

    Institute of Scientific and Technical Information of China (English)

    CHEN Shao-Xia; XIAO Neng-Chao; YAN Mu-Lin

    2008-01-01

    We discuss the variation of the fine-structure constant,α.There are obvious discrepancies among the results of α-variation from recent Quasi-stellar observation experiments and from the Oklo uranium mine analysis.We use dS Sitter invariant Special Relativity (SRc,R) and Dirac large number hypothesis to discuss this puzzle,and present a possible solution to the disagreement.By means of the observational data and the discussions presented in this paper,we estimate the radius of the Universe in SRc,R which is about ~2(√5)×1011l.y.

  7. Ground-based and spaceborn observations of the type II burst with developed fine structure

    Science.gov (United States)

    Dorovskyy, V.; Melnik, V.; Konovalenko, A.; Brazhenko, A.; Rucker, H.; Stanislavskyy, A.; Panchenko, M.

    2012-09-01

    The combination of two huge ground-based radio telescopes (UTR-2 and URAN-2) operated in decameter wavelengths with three spatially separated spacecrafts (SOHO, STEREO-A and STEREO-B) equipped with white light coronagraphs, UV telescopes and decameter-hectometer band radio telescopes created a unique opportunity to investigate the high energy solar transients, such as CMEs and their manifestations in radio bands - type II bursts. In this paper we made detailed analysis of the powerful and complex event occurred on 7 June 2011 consisted of Halo-CME and type II burst with rich fine 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. Constraining spatial variations of the fine-structure constant in symmetron models

    Science.gov (United States)

    Pinho, A. M. M.; Martinelli, M.; Martins, C. J. A. P.

    2017-06-01

    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 constrain the model when also the symmetry breaking scale factor aSSB is free to vary.

  10. ESR Dating Research of Glacial Tills in Tibetan Plateau

    Science.gov (United States)

    Bi, W.; Yi, C.

    2016-12-01

    In recent years, Quaternary Glacial-chronology has been made remarkable progress in the Tibetan Platean(TP) with the development of several numeric dating techniques, such as cosmogenic nuclides(NC), optically stimulated luminescence(OSL) and 14C. In constrast, the dating of Quaternary glacial tills in 100,000 years even more than million-year has been a challenge, just because the techniques has defects themselves and the sediments were stransformed during the geological and geomorphology progress later. Electron Spin Resonance(ESR) has been becoming one of the key methods of Quaternary Glacial-chronology with wide range of dating, expecially for the sample older than 100,000 years up to million-year scale. The accurate measurement of equivalent dose significantly impacts on accuracy and reliability of ESR dating method. Therefore, the study of the mechanisms of resetting processes is fundamental for accurate and reliable ESR dating. To understand the mechanism and characteristics of quartz ESR signal resetting of different samples, a series of laboratory simulation and field observation studies were carried out, which made lots of important breakthrough. But the research in quartz ESR signal of moraines is less and the test of ESR dating method is still in the qualitative investigation. Therefor, we use ESR dating and study on the mechanism and characteristics of quartz ESR signals in tills in the Tibetan Platean. In the adjust method of Modern, the quartz ESR signals in Modern glacial tills represent residual values which can be adjusted signals in the older glacial tills. As a consequence, ESR dating of the quartz in moraines needs to be explored in deep with building models to adjust ages which are measured by ESR dating. Therefore, ESR dating will become the trusted one of the cross dating methods in Quaternary Glacial-chronology with the adjust mothod improving the accuracy of ESR dating ages.

  11. The Fine-Structure of the Net-Circular Polarization in a Sunspot Penumbra

    CERN Document Server

    Tritschler, A; Schlichenmaier, R; Hagenaar, H J

    2007-01-01

    We present novel evidence for a fine structure observed in the net-circular polarization (NCP) of a sunspot penumbra based on spectropolarimetric measurements utilizing the Zeeman sensitive FeI 630.2 nm line. For the first time we detect a filamentary organized fine structure of the NCP on spatial scales that are similar to the inhomogeneities found in the penumbral flow field. We also observe an additional property of the visible NCP, a zero-crossing of the NCP in the outer parts of the center-side penumbra, which has not been recognized before. In order to interprete the observations we solve the radiative transfer equations for polarized light in a model penumbra with embedded magnetic flux tubes. We demonstrate that the observed zero-crossing of the NCP can be explained by an increased magnetic field strength inside magnetic flux tubes in the outer penumbra combined with a decreased magnetic field strength in the background field. Our results strongly support the concept of the uncombed penumbra.

  12. Retinular fine structure in compound eyes of diurnal and nocturnal sphingid moths.

    Science.gov (United States)

    Eguchi, E

    1982-01-01

    Retinular fine structure has been compared in the superposition compound eyes of three sphingid moths, one nocturnal, Cechenena, and two diurnal, Cephonodes and Macroglossum. Cechenena and Cephonodes have tiered retinas with three kinds of retinular cells: two distal, six regular and one basal. The distal retinular cells in Cechenena are special in having a complex partially intracellular rhabdomere not present in Cephonodes. Macroglossum lacks the distal retinular cell. In Cephonodes a unique rhabdom type, formed by the six regular retinular cells in the middle region of the retinula, is divided into three separate longitudinal plates arranged closely parallel to one another. Their constituent microvilli are consequently all nearly unidirectional. The ratio of rhabdom volume to retinular cell volume in the two diurnal sphingids is 10-27%; this is about the same as that (25%) of skipper butterflies, but significantly smaller than in the nocturnal Cechenena (60%). In the diurnal sphingids retinular cell membranes show elongate meandering profiles with septate junctions between adjacent retinular cells. From the comparative fine structure of their eyes the diurnal sphingids and the skippers would appear to be phylogenetically closely related.

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

    CERN Document Server

    van de Bruck, Carsten; 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, alpha. As a result, the theory we consider can explain the non-zero reported variation in the evolution of alpha 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 alpha. 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 r...

  14. Fine structure in the {alpha}-decay of odd-even nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Santhosh, K.P., E-mail: drkpsanthosh@gmail.com [School of Pure and Applied Physics, Kannur University, Payyanur Campus, Payyanur 670 327 (India); Joseph, Jayesh George; Priyanka, B. [School of Pure and Applied Physics, Kannur University, Payyanur Campus, Payyanur 670 327 (India)

    2012-03-01

    Systematic study on {alpha}-decay fine structure is presented for the first time in the case of odd-even nuclei in the range 83 Less-Than-Or-Slanted-Equal-To Z Less-Than-Or-Slanted-Equal-To 101. The model used for the study is the recently proposed Coulomb and proximity potential model for deformed nuclei (CPPMDN), which employs deformed Coulomb potential, deformed two term proximity potential and centrifugal potential. The computed partial half-lives, total half-lives and branching ratios are compared with experimental data and are in good agreement. The standard deviation of partial half-life is 1.08 and that for branching ratio is 1.21. Our formalism is also successful in predicting angular momentum hindered and structure hindered transitions. The present study reveals that CPPMDN is successful in explaining alpha-decay from ground and isomeric state; and alpha fine structure of even-even, even-odd and odd-even nuclei. Our study relights that the differences in the parent and daughter surfaces or the changes in the deformation parameters as well as the shell structure of the parent and daughter nuclei, influences the alpha decay probability.

  15. Fine structure in the {\\alpha}-decay of odd-even nuclei

    CERN Document Server

    Santhosh, K P; Priyanka, B

    2012-01-01

    Systematic study on {\\alpha}-decay fine structure is presented for the first time in the case of odd-even nuclei in the range 83 \\leq Z \\leq 101. The model used for the study is the recently proposed Coulomb and proximity potential model for deformed nuclei (CPPMDN), which employs deformed Coulomb potential, deformed two term proximity potential and centrifugal potential. The computed partial half lives, total half lives and branching ratios are compared with experimental data and are in good agreement. The standard deviation of partial half-life is 1.08 and that for branching ratio is 1.21. Our formalism is also successful in predicting angular momentum hindered and structure hindered transitions. The present study reveals that CPPMDN is a unified theory which is successful in explaining alpha decay from ground and isomeric state; and alpha fine structure of even-even, even-odd and odd-even nuclei. Our study relights that the differences in the parent and daughter surfaces or the changes in the deformation p...

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

    Science.gov (United States)

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

    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.

  17. On the fine structure of the sunspot penumbrae. II. The nature of the Evershed flow

    CERN Document Server

    Borrero, J M; Solanki, S K; Collados, M

    2005-01-01

    We investigate the fine structure of the sunspot penumbra by means of a model that allows for a flux tube in horizontal pressure balance with the magnetic background atmosphere in which it is embedded. We apply this model to spectropolarimetric observations of two neutral iron lines at 1.56 $\\mu$m and invert several radial cuts in the penumbra of the same sunspot at two different heliocentric angles. In the inner part of the penumbra we find hot flux tubes that are somewhat inclined to the horizontal. They become gradually more horizontal and cooler with increasing radial distance. This is accompanied by an increase in the velocity of the plasma and a decrease of the gas pressure difference between flux tube and the background component. At large radial distances the flow speed exceeds the critical speed and evidence is found for the formation of a shock front. These results are in good agreement with simulations of the penumbral fine structure and provide strong support for the siphon flow as the physical me...

  18. Oscillatory behavior of chromospheric fine structures in a network and a semi-active regions

    CERN Document Server

    Bostanci, Z F; Al, N

    2014-01-01

    In the present work, we study the periodicities of oscillations in dark fine structures using observations of a network and a semi-active region close to the solar disk center. We simultaneously obtained spatially high resolution time series of white light images and narrow band images in the H$\\alpha$ line using the 2D G\\"ottingen spectrometer, which were based on two Fabry-Perot interferometers and mounted in the VTT/Observatorio del Teide/Tenerife. During the observations, the H$\\alpha$ line was scanned at 18 wavelength positions with steps of 125 m\\AA. We computed series of Doppler and intensity images by subtraction and addition of the H$\\alpha$ $\\pm$ 0.3 \\AA\\ and $\\pm$ 0.7 \\AA\\ pairs, sampling the upper chromosphere and the upper photosphere, respectively. Then we obtained power, coherence and phase difference spectra by performing a wavelet analysis to the Doppler fluctuations. Here, we present comparative results of oscillatory properties of dark fine structures seen in a network and a semi-active reg...

  19. Low-energy fine-structure resonances in photoionization of O ii

    Science.gov (United States)

    Nahar, Sultana N.; Montenegro, Maximiliano; Eissner, Werner; Pradhan, Anil K.

    2010-12-01

    Resonant features in low-energy photoionization cross sections are reported in coupled-channel calculations for O ii including relativistic fine structure. The calculations reveal extensive near-threshold resonant structures in the small energy region between the fine structure levels of the ground state 2p2(3P0,1,2) of the residual ion O iii. Although the resonances have not yet been observed, they are similar to other experimentally observed features. They are expected to significantly enhance the very-low-temperature dielectronic recombination rates, potentially leading to the resolution of an outstanding nebular abundances anomaly. Higher energy partial and total photoionization cross sections of the ground configuration levels 2p3(4S3/2o,2D3/2,5/2o,2P1/2,3/2o) are found to be in agreement with experimental measurements on synchrotron-based photon sources [1-3], thereby identifying the excited O iii levels present in the ion beams. These are also the first results from a recently developed version of Breit-Pauli R-matrix (BPRM) codes, with inclusion of two-body magnetic interaction terms. The improved relativistic treatment could be important for other astrophysical applications and for more precise benchmarking of experimental measurements.

  20. Constraining spatial variations of the fine structure constant using clusters of galaxies and Planck data

    CERN Document Server

    de Martino, I; Ebeling, H; Kocevski, D

    2016-01-01

    We propose an improved methodology to constrain spatial variations of the fine structure constant using clusters of galaxies. We use the {\\it Planck} 2013 data to measure the thermal Sunyaev-Zeldovich effect at the location of 618 X-ray selected clusters. We then use a Monte Carlo Markov Chain algorithm to obtain the temperature of the Cosmic Microwave Background at the location of each galaxy cluster. When fitting three different phenomenological parameterizations allowing for monopole and dipole amplitudes in the value of the fine structure constant we improve the results of earlier analysis involving clusters and CMB power spectrum, and we also found that the best-fit direction of a hypothetical dipole is compatible with the direction of other known anomalies. Although the constraining power of our current datasets do not allow us to test the indications of a dipole obtained though high-resolution optical/UV spectroscopy, our results do highlight that clusters of galaxies will be a very powerful tool to pr...

  1. Fine structure of uterus and non-functioning paruterine organ in Orthoskrjabinia junlanae (Cestoda, Cyclophyllidea).

    Science.gov (United States)

    Korneva, Janetta V; Kornienko, Svetlana A; Jones, Malcolm K

    2016-06-01

    Some cyclophyllidean cestodes provide protection for their eggs in the external environment by providing them with additional protective layers around the egg membranes. In attempting to examine such adaptations, the microanatomy and fine structure of the uterus of pregravid and gravid proglottids of the cyclophyllidean cestode Orthoskrjabinia junlanae, a parasite of mammals that inhabit a terrestrial but moist environment, were studied. In the initial stages of uterine development, developing embryos locate freely in the lumen of a saccate uterus that later partitions into chambers. Each chamber that forms encloses several embryos. The chambers are surrounded by muscle cells that synthesize extracellular matrix actively. The paruterine organs consist of stacks of flattened long outgrowths of muscular cells, interspersed with small lipid droplets. In the gravid proglottids, the size of paruterine organ increases and consists of flattened basal and small rounded apical parts separated by constrictions. The fine structure of the organ wall remains the same: sparse nuclei and stacks of flattened cytoplasmic outgrowths but internal invaginations or lumen in the paruterine organ are absent. Completely developed eggs remain localized in the uterus. Based on the comparative morpho-functional analysis of uterine and paruterine organs and uterine capsules in cestodes, we conclude that these non-functioning paruterine organ in O. junlanae is an example of an atavism. We postulate that the life cycle of the parasite, which infects mammals living in wet habitats, where threats of desiccation of parasite ova is reduced, has favoured a reversion to a more ancestral form of uterine development.

  2. Sensitivity to temporal fine structure and hearing-aid outcomes in older adults

    Directory of Open Access Journals (Sweden)

    Elvira ePerez Vallejos

    2014-02-01

    Full Text Available Objective: to investigate the effect of sensitivity to temporal fine structure on subjective measures of hearing aid outcome.Design: Prior to receiving hearing aids, participants completed a test to assess sensitivity to temporal fine structure (TFS, the Glasgow Hearing Aid Benefit Profile (GHABP, and the Speech, Spatial and Qualities of hearing (SSQ-A. Follow-up appointments, comprised the GHABP, the SSQ-B , and the International Outcome Inventory for Hearing Aid Outcomes (IOI-HA.Study sample: 75 adults were recruited from direct referral clinics. Results: Two thirds of participants were found to have good sensitivity to TFS; listeners with good sensitivity to TFS rated their hearing abilities higher at pre-fitting (SSQ-A than those with poor sensitivity to TFS. At follow-up, participants with good sensitivity to TFS showed a small improvement on SSQ-B over listeners with poor sensitivity to TFS. Conclusions: The clinical identification of a patient’s ability to process TFS information at an early stage in the treatment pathway could prove useful in managing expectations about hearing aid outcomes.

  3. Neon Fine-Structure Line Emission By X-ray Irradiated Protoplanetary Disks

    CERN Document Server

    Glassgold, A E; Igea, J; Glassgold, Alfred E.; Najita, Joan R.; Igea, Javier

    2006-01-01

    Using a thermal-chemical model for the generic T-Tauri disk of D'Alessio et al. (1999), we estimate the strength of the fine-structure emission lines of NeII and NeIII at 12.81 and 15.55 microns that arise from the warm atmosphere of the disk exposed to hard stellar X-rays. The Ne ions are produced by the absorption of keV X-rays from the K shell of neutral Ne, followed by the Auger ejection of several additional electrons. The recombination cascade of the Ne ions is slow because of weak charge transfer with atomic hydrogen in the case of Ne2+ and by essentially no charge transfer for Ne+. For a distance of 140pc, the 12.81 micron line of Ne II has a flux of 1e-14 erg/cm2s, which should be observable with the Spitzer Infrared Spectrometer and suitable ground based instrumentation. The detection of these fine-structure lines would clearly demonstrate the effects of X-rays on the physical and chemical properties of the disks of young stellar objects and provide a diagnostic of the warm gas in protoplanetary dis...

  4. 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.

  5. The coefficient of bond thermal expansion measured by extended x-ray absorption fine structure.

    Science.gov (United States)

    Fornasini, P; Grisenti, R

    2014-10-28

    The bond thermal expansion is in principle different from the lattice expansion and can be measured by correlation sensitive probes such as extended x-ray absorption fine structure (EXAFS) and diffuse scattering. The temperature dependence of the coefficient α(bond)(T) of bond thermal expansion has been obtained from EXAFS for CdTe and for Cu. A coefficient α(tens)(T) of negative expansion due to tension effects has been calculated from the comparison of bond and lattice expansions. Negative lattice expansion is present in temperature intervals where α(bond) prevails over α(tens); this real-space approach is complementary but not equivalent to the Grüneisen theory. The relevance of taking into account the asymmetry of the nearest-neighbours distribution of distances in order to get reliable bond expansion values and the physical meaning of the third cumulant are thoroughly discussed.

  6. He I vector magnetic field maps of a sunspot and its superpenumbral fine-structure

    CERN Document Server

    Schad, T A; Lin, H; Tritschler, A

    2015-01-01

    Advanced inversions of high-resolution spectropolarimetric observations of the He I triplet at 1083 nm are used to generate unique maps of the chromospheric magnetic field vector across a sunspot and its superpenumbral canopy. The observations were acquired by the Facility Infrared Spectropolarimeter (FIRS) at the Dunn Solar Telescope (DST) on 29 January 2012. Multiple atmospheric models are employed in the inversions, as superpenumbral Stokes profiles are dominated by atomic-level polarization while sunspot profiles are Zeeman-dominated but also exhibit signatures perhaps induced by symmetry breaking effects of the radiation field incident on the chromospheric material. We derive the equilibrium magnetic structure of a sunspot in the chromosphere, and further show that the superpenumbral magnetic field does not appear finely structured, unlike the observed intensity structure. This suggests fibrils are not concentrations of magnetic flux but rather distinguished by individualized thermalization. We also dire...

  7. The tardigrade cuticle. I. Fine structure and the distribution of lipids.

    Science.gov (United States)

    Wright, J C

    1988-01-01

    Fine structure and lipid distribution are studied in cuticles of five tardigrade species using TEM and SEM. Double osmication using partitioning methods reveals a substantial lipid component in the intracuticle and in irregular granular regions within the procuticle. These results are substantiated by the loss of osmiophily following lipid extraction with chloroform and methanol. Other lipid components are revealed by osmication following unmasking of lipo-protein complexes with thymol. These occur in the outer epicuticle and in the trilaminar layer lying between the epi- and intracuticles. Anhydrous fixation of dehydrated tardigrades (tuns) reveals dense, superficial masses of osmiophilic material, apparently concentrated lumps of the surface mucopolysaccharide ('flocculent coat'). However, cryo-SEMs of tuns reveal similar dense aggregations which apparently exude from pores (not visible) and are removed by chloroform. These results suggest extruded lipids since the flocculent coat is unaffected by chloroform; likely functions of such lipids are discussed.

  8. Near-edge X-ray absorption fine structure spectroscopy of MDI and TDI polyurethane polymers

    Energy Technology Data Exchange (ETDEWEB)

    Urquhart, S.G.; Smith, A.P.; Ade, H.W. [North Carolina State Univ., Raleigh, NC (United States). Dept. of Physics; Hitchcock, A.P. [McMaster Univ., Hamilton, Ontario (Canada). Brockhouse Inst. for Materials Research; Rightor, E.G. [Dow Chemical USA, Midland, MI (United States); Lidy, W. [Dow Chemical USA, Freeport, TX (United States)

    1999-06-03

    The sensitivity of near-edge X-ray absorption fine structure (NEXAFS) to differences in key chemical components of polyurethane polymers is presented. Carbon is NEXAFS spectra of polyurethane polymers made from 4,4{prime}-methylene di-p-phenylene isocyanate (MDI) and toluene diisocyanate (TDI) isocyanate monomers illustrate that there is an unambiguous spectroscopic fingerprint for distinguishing between MDI-based and TDI-based polyurethane polymers. NEXAFS spectra of MDI and TDI polyurea and polyurethane models show that the urea and carbamate (urethane) linkages in these polymers can be distinguished. The NEXAFS spectroscopy of the polyether component of these polymers is discussed, and the differences between the spectra of MDI and TDI polyurethanes synthesized with polyether polyols of different molecular composition and different molecular weight are presented. These polymer spectra reported herein provide appropriate model spectra to represent the pure components for quantitative microanalysis.

  9. Fine structures in Fe3Al alloy layer of a new hot dip aluminized steel

    Indian Academy of Sciences (India)

    Li Yajiang; Wang Juan; Zhang Yonglan; X Holly

    2002-12-01

    The fine structure in the Fe–Al alloy layer of a new hot dip aluminized steel (HDA) was examined by means of X-ray diffractometry (XRD), electron diffraction technique, etc. The test results indicated that the Fe–Al alloy layer of the new aluminized steel mainly composed of Fe3Al, FeAl and -Fe (Al) solid solution. There was no brittle phase containing higher aluminum content, such as FeAl3 (59.18% Al) and Fe2Al7 (62.93% Al). The tiny cracks and embrittlement, formerly caused by these brittle phases in the conventional aluminum-coated steel, were effectively eliminated. There was no microscopic defect (such as tiny cracks, pores or loose layer) in the coating. This is favourable to resist high temperature oxidation and corrosion of the aluminized steel.

  10. The fine structure splitting of the level of lithium in Rydberg states

    Institute of Scientific and Technical Information of China (English)

    胡先权; 胡文江; 孔春阳

    2002-01-01

    The Hamiltonian of the four-body problem for a lithium atom is expanded in series. The level shift and levelformula of a lithium atom in Rydberg states are achieved by means of the calculation of polarization of the atomic core(including the contribution of dipole, quadrupole and octupole components). We also consider the effect of relativitytheory, the orbital angular momentum L and the spin angular momentum S coupling scheme (LS coupling) and high-order correction of the effective potential to the level shift. The fine structure splitting (N=5-12, L=4-9, J=L±l/2)and level intervals in B ydberg states have been calculated by the above-mentioned formula and compared with recentexperimental data.

  11. Single shot near edge x-ray absorption fine structure spectroscopy in the laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Mantouvalou, I., E-mail: ioanna.mantouvalou@tu-berlin.de; Witte, K.; Martyanov, W.; Jonas, A.; Grötzsch, D.; Kanngießer, B. [Institute for Optics and Atomic Physics, Technical University of Berlin, D-10623 Berlin (Germany); Streeck, C. [Physikalisch-Technische Bundesanstalt (PTB), D-10587 Berlin (Germany); Löchel, H.; Rudolph, I.; Erko, A. [Helmholtz-Zentrum Berlin, D-14109 Berlin (Germany); Stiel, H. [Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, D-12489 Berlin (Germany)

    2016-05-16

    With the help of adapted off-axis reflection zone plates, near edge X-ray absorption fine structure spectra at the C and N K-absorption edge have been recorded using a single 1.2 ns long soft X-ray pulse. The transmission experiments were performed with a laser-produced plasma source in the laboratory rendering time resolved measurements feasible independent on large scale facilities. A resolving power of E/ΔE ∼ 950 at the respective edges could be demonstrated. A comparison of single shot spectra with those collected with longer measuring time proves that all features of the used reference samples (silicon nitrate and polyimide) can be resolved in 1.2 ns. Hence, investigations of radiation sensitive biological specimen become possible due to the high efficiency of the optical elements enabling low dose experiments.

  12. Study on Fine Structure of Gas Atomized LaNi5-based Alloys

    Institute of Scientific and Technical Information of China (English)

    Hai JING; Hong GUO; Shuguang ZHANG; Zili MA; Shaoming ZHANG

    2003-01-01

    The fine structure of hydrogen storage alloy powders MINi4.3-xCoxMn0.4Al0.3(x=0.75, 0.45, 0.10; MI: La-rich mischmetal) prepared by rapidly solidifying gas atomization was investigated using a Rietveld analysis method. Two setsof CaCu5-type crystal constants were observed in the studied alloys and one set was larger than the other. Withdecreasing powder radius the solidification rate of powder increased, and so did the percentage of a particle partwith larger crystal constants. The reason why there were two sets of crystal constants might be the difference ofsolidification rate between the outside and inside of a particle.

  13. Theory of the Lamb shift and Fine Structure in $\\boldsymbol{(\\mu{}^{4}\\mathrm{He})^{+}}$

    CERN Document Server

    Diepold, Marc; Franke, Beatrice; Antognini, Aldo; Kottmann, Franz; Pohl, Randolf

    2016-01-01

    An up to date review of the theoretical contributions to the $2S\\rightarrow{}2P$ Lamb shift and the fine structure of the $2P$-state in the $(\\mu^4\\mathrm{He})^+$ ion is given. This summary will serve as the basis for the extraction of the alpha particle charge radius from the muonic helium Lamb shift measurements at the Paul Scherrer Institute Switzerland. Individual theoretical contributions needed for a charge radius extraction were compared and compiled into a consistent summary using the already established framework we used for muonic hydrogen and deuterium. The influence of the alpha particle charge distribution on the elastic two-photon exchange is studied to rule out possible model dependencies of the energy levels on the electric form factor of the nucleus.

  14. Possible evidence for a variable fine structure constant from QSO absorption lines systematic errors

    CERN Document Server

    Murphy, M T; Flambaum, V V; Churchill, C W; Prochaska, J X

    2001-01-01

    Comparison of quasar absorption spectra with laboratory spectra allow us to probe possible variations in the fundamental constants over cosmological time-scales. In a companion paper we present an analysis of Keck/HIRES spectra and report possible evidence suggesting that the fine structure constant, alpha, may have been smaller in the past: da/a = (-0.72 +/- 0.18) * 10^{-5} over the redshift range 0.5 < z < 3.5. In this paper we describe a comprehensive investigation into possible systematic effects. Most of these do not significantly influence our results. When we correct for those which do produce a significant systematic effect in the data, the deviation of da/a from zero becomes more significant. We are lead increasingly to the interpretation that alpha was slightly smaller in the past.

  15. Fine structure of inelastic electron scattering cross-section spectra for MN

    Science.gov (United States)

    Parshin, A. S.; Igumenov, A. Yu; Mikhlin, Yu L.; Pchelyakov, O. P.; Zhigalov, V. S.

    2016-04-01

    The comparative analysis of the reflection electron energy loss spectra and the inelastic electron scattering cross-section spectra for Mn was carried out. It is shown that inelastic electron scattering cross-section spectra have certain advantages in the study of the interaction of electrons with the substance as compared to the electron energy loss spectra. The inelastic electron scattering cross section spectra fine structure was analysed by fitting the experimental spectra using the 3 parameters Lorentzian-type formula of Tougaard. This method was used for the quantitative analysis of the contributions of various loss processes in the inelastic electron scattering cross section spectra, determination of the loss peaks energies and origin.

  16. 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.

  17. 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.

  18. Strain-driven growth of GaAs(111) quantum dots with low fine structure splitting

    Energy Technology Data Exchange (ETDEWEB)

    Yerino, Christopher D.; Jung, Daehwan; Lee, Minjoo Larry, E-mail: minjoo.lee@yale.edu [Department of Electrical Engineering, Yale University, New Haven, Connecticut 06520 (United States); Simmonds, Paul J. [Departments of Physics and Materials Science and Engineering, Boise State University, Boise, Idaho 83725 (United States); Liang, Baolai; Huffaker, Diana L. [California NanoSystems Institute and Department of Electrical Engineering, University of California, Los Angeles, California 90095 (United States); Schneider, Christian; Unsleber, Sebastian; Vo, Minh; Kamp, Martin [Technische Physik, Physikalisches Institut and Wilhelm Conrad Röntgen-Research Center for Complex Material Systems, Universität Würzburg, Am Hubland, D-97074 Würzburg (Germany); Höfling, Sven [Technische Physik, Physikalisches Institut and Wilhelm Conrad Röntgen-Research Center for Complex Material Systems, Universität Würzburg, Am Hubland, D-97074 Würzburg (Germany); SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews, KY16 9SS (United Kingdom)

    2014-12-22

    Symmetric quantum dots (QDs) on (111)-oriented surfaces are promising candidates for generating polarization-entangled photons due to their low excitonic fine structure splitting (FSS). However, (111) QDs are difficult to grow. The conventional use of compressive strain to drive QD self-assembly fails to form 3D nanostructures on (111) surfaces. Instead, we demonstrate that (111) QDs self-assemble under tensile strain by growing GaAs QDs on an InP(111)A substrate. Tensile GaAs self-assembly produces a low density of QDs with a symmetric triangular morphology. Coherent, tensile QDs are observed without dislocations, and the QDs luminescence at room temperature. Single QD measurements reveal low FSS with a median value of 7.6 μeV, due to the high symmetry of the (111) QDs. Tensile self-assembly thus offers a simple route to symmetric (111) QDs for entangled photon emitters.

  19. Engineering quantum dots for electrical control of the fine structure splitting

    Science.gov (United States)

    Pooley, M. A.; Bennett, A. J.; Farrer, I.; Ritchie, D. A.; Shields, A. J.

    2013-07-01

    We have studied the variation in fine-structure splitting (FSS) under application of vertical electric field in a range of quantum dots grown by different methods. In each sample, we confirm that this energy splitting changes linearly over the field range we can access. We conclude that this linear tuning is a general feature of self-assembled quantum dots, observed under different growth conditions, emission wavelengths, and in different material systems. Statistical measurements of characteristic parameters such as emission energy, Stark shift, and FSS tuning are presented which may provide a guide for future attempts to increase the yield of quantum dots that can be tuned to a minimal value of FSS with vertical electric field.

  20. 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.

  1. Fine structure in the cosmic ray spectrum: Further analysis and the next step

    CERN Document Server

    Erlykin, A D

    2011-01-01

    An analysis is made of the fine structure in the cosmic ray energy spectrum: new facets of present observations and their interpretation and the next step. It is argued that less than about 10% of the intensity of the helium `peak' at the knee at $\\simeq 5PeV$ is due to just a few sources (SNR) other than the single source. The apparent concavity in the rigidity spectra of protons and helium nuclei which have maximum curvature at about 200 GV is confirmed by a joint analysis of the PAMELA, CREAM and ATIC experiments. The spectra of heavier nuclei also show remarkable structure in the form of `ankles' at several hundred GeV/nucleon. Possible mechanisms are discussed. The search for `pulsar peaks' has not yet proved successful.

  2. Hemicellulose fine structure is affected differently during ripening of tomato lines with contrasted texture.

    Science.gov (United States)

    Lahaye, Marc; Quemener, Bernard; Causse, Mathilde; Seymour, Graham B

    2012-11-01

    The impact of genetic and fruit ripening on hemicelluloses fine structure was studied in twelve near isogenic lines of tomato fruits harboring firmness QTL. The sugar composition and the MALDI-TOF MS oligosaccharides profile after glucanase hydrolysis of the cell walls were determined from all green and red fruits pericarp tissue. MS profiles showed two major series of oligomers attributed to xyloglucan (XG) and glucomannan (GM) with minor peaks for xylan and ions attributed to galacto-oligomers. The oligosaccharides MS intensity varied significantly with the fruit genetic and ripening status. Correlations between MS intensity indicated structural regulations of both XG and GM structures with genetics and ripening. These results point to a region on the tomato chromosome 9 controlling cell wall galactose metabolism.

  3. Systematics of fine structure in the α decay of deformed odd-mass nuclei

    Science.gov (United States)

    Ren, Zhongzhou; Ni, Dongdong

    2014-12-01

    We present a detailed analysis of the a-decay fine structure in 32 deformed odd-mass nuclei from Z = 93 to Z = 102. The α-decay half-lives are systematically calculated within the multichannel cluster model (MCCM), which turns out to well reproduce the experimental data and show the neutron deformed shell structure. The branching ratios for various daughter states are investigated in the MCCM and in the WKB barrier penetration approach, respectively. It is found that the MCCM results agree well with the experimental data, while the WKB results have relatively large deviations from the experimental data for the α transitions to the high-lying members of the rotational band.

  4. Half-lives and fine structure for the α decay of deformed even-even nuclei

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The α-decay properties of well-deformed even-even nuclei are systematically calculated within the multichannel cluster model (MCCM). Instead of working in the WKB framework, the quasibound solution to the coupled Schro¨dinger equation is presented with outgoing wave boundary conditions, and the coupling potential is taken into full account in terms of the general quantum theories. The calculated α-decay half-lives are found to agree well with the experimental data with a mean factor of less than 2. The fine structure observed in α decay is also well reproduced by the four-channel microscopic calculation. Very strikingly, the MCCM can give relatively precise descriptions of the branching ratio to excited 4+ states, which is often overestimated in the usual WKB calculations. We expect it to be a significant development of theoretical models toward quantitative descriptions of α transitions to high-spin daughter states.

  5. Half-lives and fine structure for the α decay of deformed even-even nuclei

    Science.gov (United States)

    Ni, DongDong; Ren, ZhongZhou

    2011-08-01

    The α-decay properties of well-deformed even-even nuclei are systematically calculated within the multichannel cluster model (MCCM). Instead of working in the WKB framework, the quasibound solution to the coupled Schrödinger equation is presented with outgoing wave boundary conditions, and the coupling potential is taken into full account in terms of the general quantum theories. The calculated α-decay half-lives are found to agree well with the experimental data with a mean factor of less than 2. The fine structure observed in α decay is also well reproduced by the four-channel microscopic calculation. Very strikingly, the MCCM can give relatively precise descriptions of the branching ratio to excited 4+ states, which is often overestimated in the usual WKB calculations. We expect it to be a significant development of theoretical models toward quantitative descriptions of α transitions to high-spin daughter states.

  6. Theoretical description of fine structure in the α decay of heavy odd-odd nuclei

    Science.gov (United States)

    Ni, Dongdong; Ren, Zhongzhou

    2013-02-01

    The newly developed multichannel cluster model (MCCM), based on the coupled-channel Schrödinger equation with outgoing wave boundary conditions, is extended to study the α-decay fine structure in heavy odd-odd nuclei. Calculations are performed for the α transitions to favored rotational bands where the unpaired nucleons remain unchanged. The simple WKB barrier penetration formula is also used to evaluate the branching ratios for various daughter states. It is found that the WKB formula seems to overestimate the branching ratios for the second and third members of the favored rotational band, while the MCCM gives a precise description of them without any adjustable parameters. Moreover, the experimental total α-decay half-lives are well reproduced within the MCCM.

  7. High resolution telescope and spectrograph observations of solar fine structure in the 1600 A region

    Science.gov (United States)

    Cook, J. W.; Brueckner, G. E.; Bartoe, J.-D. F.

    1983-01-01

    High spatial resolution spectroheliograms of the 1600 A region obtained during the HRTS rocket flight of 1978 February 13 are presented. The morphology, fine structure, and temporal behavior of emission bright points (BPs) in active and quiet regions are illustrated. In quiet regions, network elements persist as morphological units, although individual BPs may vary in intensity while usually lasting the flight duration. In cell centers, the BPs are highly variable on a 1 minute time scale. BPs in plages remain more constant in brightness over the observing sequence. BPs cover less than 4 percent of the quiet surface. The lifetime and degree of packing of BPs vary with the local strength of the magnetic field.

  8. THE FINE STRUCTURE OF STALKED BACTERIA BELONGING TO THE FAMILY CAULOBACTERACEAE.

    Science.gov (United States)

    STOVEPOINDEXTER, J L; COHEN-BAZIRE, G

    1964-12-01

    The fine structure of a series of stalked bacteria belonging to the genera Caulobacter and Asticcacaulis has been examined in thin sections. The cell wall has the multilayered structure typical of many Gram-negative bacteria, and continues without interruption throughout the length of the stalk. The core of the stalk, continuous with the cytoplasmic region of the cell, is enclosed in an extension of the cell membrane, and contains a system of internal membranes: it is devoid of ribosomes and nucleoplasm. A membranous organelle occupies the juncture of stalk and cell, separating the ribosomal region from the core of the stalk. Typical mesosomes also occur in the cell, being particularly frequent at the plane of division. The secreted holdfast is located at the tip of the stalk in Caulobacter, and at the pole of the cell adjacent to the stalk in Asticcacaulis.

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

    Energy Technology Data Exchange (ETDEWEB)

    Antonio, M.R.; Soderholm, L. [Argonne National Lab., IL (United States). Chemistry Div.; Song, I. [Case Western Reserve Univ., Cleveland, OH (United States)

    1995-06-12

    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{sub 3}-edge XANES (X-ray Absorption Near Edge Structure) throughout the course of electrolysis of an aqueous solution of EuCl{sub 3}{center_dot}6H{sub 2}O in 1 M H{sub 2}SO{sub 4}. The europium L{sub 3}-edge resonances reported here for the Eu{sup III} and Eu{sup II} ions demonstrate that their 2p{sub 3/2} {yields} 5d electronic transition probabilities are not the same.

  10. Impact of heavy hole-light hole coupling on the exciton fine structure in quantum dots

    Science.gov (United States)

    Tsitsishvili, E.

    2017-03-01

    We present analytical results which describe the properties of the exciton ground state in a single semiconductor quantum dot (QD). Calculations are performed within the Luttinger-Kohn and Bir-Pikus Hamiltonian theory. We show in an explicit form that an interplay of the exchange interaction and the heavy hole-light hole coupling, which is due to the in-plane asymmetries of the dot shape and the strain distribution, plays an essential role. For both the bright and dark exciton, this combined effect leads to a dependence of the fine structure splitting and polarizations on the main anisotropy axis direction relative to the dot orientation. Basing on the obtained analytical expressions, we discuss some special cases in details.

  11. Constraints on the time variation of the fine structure constant by the 5-year WMAP data

    CERN Document Server

    Nakashima, Masahiro; Yokoyama, Jun'ichi

    2008-01-01

    The constraints on the time variation of the fine structure constant at recombination epoch relative to its present value, $\\Delta\\alpha/\\alpha \\equiv (\\alpha_{\\mathrm{rec}} - \\alpha_{\\mathrm{now}})/\\alpha_{\\mathrm{now}}$, are obtained from the analysis of the 5-year WMAP cosmic microwave background data. As a result of Markov-Chain Monte-Carlo analysis, it is found that, contrary to the analysis based on the previous WMAP data, the mean value of $\\Delta\\alpha/\\alpha=-0.0009$ does not change significantly whether we use the Hubble Space Telescope (HST) measurement of the Hubble parameter as a prior or not. The resultant 95% confidence ranges of $\\Delta\\alpha/\\alpha$ are $-0.028 < \\Delta\\alpha/\\alpha < 0.026$ with HST prior and $-0.050 < \\Delta\\alpha/\\alpha < 0.042$ without HST prior.

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

    CERN Document Server

    Cahill, R T

    2006-01-01

    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, demonstrates the validity of this theory of gravity. This success implies that Newtonian gravity was fundamentally flawed from the beginning.

  13. Variation of the fine-structure constant from the de Sitter invariant special relativity

    Science.gov (United States)

    Chen, Shao-Xia; Xiao, Neng-Chao; Yan, Mu-Lin

    2008-08-01

    We discuss the variation of the fine-structure constant, α. There are obvious discrepancies among the results of α-variation from recent Quasi-stellar observation experiments and from the Oklo uranium mine analysis. We use dS Sitter invariant Special Relativity (Script SScript Rc,R) and Dirac large number hypothesis to discuss this puzzle, and present a possible solution to the disagreement. By means of the observational data and the discussions presented in this paper, we estimate the radius of the Universe in Script SScript Rc,R which is about ~2√5×1011l.y. Supported by National Natural Science Foundation of China (90403021) and PhD Program Funds of Education Ministry of China (20020358040)

  14. New determination of the fine structure constant and test of the quantum electrodynamics.

    Science.gov (United States)

    Bouchendira, Rym; Cladé, Pierre; Guellati-Khélifa, Saïda; Nez, François; Biraben, François

    2011-02-25

    We report a new measurement of the ratio h/m(Rb) between the Planck constant and the mass of (87)Rb atom. A new value of the fine structure constant is deduced, α(-1)=137.035999037(91) with a relative uncertainty of 6.6×10(-10). Using this determination, we obtain a theoretical value of the electron anomaly a(e)=0.00115965218113(84), which is in agreement with the experimental measurement of Gabrielse [a(e)=0.00115965218073(28)]. The comparison of these values provides the most stringent test of the QED. Moreover, the precision is large enough to verify for the first time the muonic and hadronic contributions to this anomaly.

  15. Capturing a photoexcited molecular structure through time-domain x-ray absorption fine structure.

    Energy Technology Data Exchange (ETDEWEB)

    Chen, L. X.; Jaeger, W. J. H.; Jennings, G.; Gosztola, D. J.; Munkholm, A.; Hessler, J. P.

    2001-04-13

    The determination of the structure of transient molecules, such as photoexcited states, in disordered media (such as in solution) usually requires methods with high temporal resolution. The transient molecular structure of a reaction intermediate produced by photoexcitation of NiTPP-L{sub 2} (NiTPP, nickeltetraphenylporphyrin; L, piperidine) in solution was determined by x-ray absorption fine structure (XAFS) data obtained on a 14-nanosecond time scale from a third-generation synchrotron source. The XAFS measurements confirm that photoexcitation leads to the rapid removal of both axial ligands to produce a transient square-planar intermediate, NiTPP, with a lifetime of 28 nanoseconds. The transient structure of the photodissociated intermediate is nearly identical to that of the ground state NiTPP, suggesting that the intermediate adopts the same structure as the ground state in a noncoordinating solvent before it recombines with two ligands to form the more stable octahedrally coordinated NiTPP-L{sub 2}.

  16. 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

    Combined electron microscopy and immunocytochemistry of the larvae of several polyplacophoran species (Chiton olivaceus, Lepidochitona aff. corrugata, Mopalia muscosa) revealed a sensory system new to science, a so-called "ampullary system." The cells of the "ampullary system" are arranged in four...... 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...... sensory organs of other molluscs, such as the apical complex of gastropod and bivalve larvae, osphradia of vetigastropods, and olfactory organs of cephalopods, and nuchal organs of certain polychaetes. The ampullary cells and their nerves are densely stained by anti-FMRF-amide fluorescence dyes, whereas...

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

    CERN Document Server

    Holanda, R F L; Alcaniz, J S; G., I E Sanchez; Busti, V C

    2015-01-01

    We propose a new method to probe a possible time evolution of the fine structure constant $\\alpha$ from X-ray and Sunyaev-Zeldovich measurements of the gas mass fraction ($f_{gas}$) in galaxy clusters. Taking into account a direct relation between variations of $\\alpha$ and violations of the distance-duality relation, we discuss constraints on $\\alpha$ 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 $f_{gas}$, in the redshift interval $0.14 < z < 0.89$, provide an independent estimate of $\\alpha$ 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 $\\alpha$ variation obtained in the present analysis.

  18. The variation of the fine structure constant: an update of statistical analysis with recent data

    CERN Document Server

    Kraiselburd, Lucila; Simeone, Claudio

    2013-01-01

    We analyze different astronomical data of the variation in the fine structure constant obtained with KECK and VLT to check their consistency. We test consistency using the Student test and confidence intervals. We split the data sets in smaller intervals and group them by i) redshift and ii) angular position. Another statistical analysis is proposed considering phenomenological models for the variation in \\alpha\\ . Results show consistency for reduced intervals for each pair of data sets considered and suggest that the variation in \\alpha\\ is important at higher redshifts.Even though the "dipole model" proposed by Webb et al. seems to be the most accurate phenomenological model, the statistical analyses indicates that the variation in \\alpha\\ might be depending both on redshift and angular position.

  19. The variation of the fine structure constant: testing the dipole model with thermonuclear supernovae

    CERN Document Server

    Kraiselburd, Lucila; Negrelli, Carolina; Berro, Enrique García

    2014-01-01

    The large-number hypothesis conjectures that fundamental constants may vary. Accordingly, the spacetime variation of fundamental constants has been an active subject of research for decades. Recently, using data obtained with large telescopes a phenomenological model in which the fine structure constant might vary spatially has been proposed. We test whether this hypothetical spatial variation of {\\alpha}, which follows a dipole law, is compatible with the data of distant thermonuclear supernovae. Unlike previous works, in our calculations we consider not only the variation of the luminosity distance when a varying {\\alpha} is adopted, but we also take into account the variation of the peak luminosity of Type Ia supernovae resulting from a variation of {\\alpha}. This is done using an empirical relation for the peak bolometric magnitude of thermonuclear supernovae that correctly reproduces the results of detailed numerical simulations. We find that there is no significant difference between the several phenome...

  20. `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.

  1. X-ray absorption fine structure spectroscopy of plutonium complexes with bacillus sphaericus

    Energy Technology Data Exchange (ETDEWEB)

    Panak, P.J.; Booth, C.H.; Caulder, D.L.; Bucher, J.J.; Shuh, D.K. [Lawrence Berkeley National Lab. (LBNL), Chemical Sciences Div., The Glenn T. Seaborg Center, Berkeley, CA (United States); Nitsche, H. [Lawrence Berkeley National Lab. (LBNL), Chemical Sciences Div., The Glenn T. Seaborg Center, Berkeley, CA (United States); Univ. of California at Berkeley, Dept. of Chemistry, Berkeley, CA (United States)

    2002-07-01

    Knowledge of the plutonium complexes formed with bacterial cells is critical for predicting the influence of microbial interactions on the migration behavior of actinides in the environment. This investigation describes the interaction of plutonium(VI) with cells of the aerobic soil bacteria, Bacillus sphaericus. The studies include the quantification of carboxylate and phosphate functional groups on the cell walls by potentiometric titration and the determination of the plutonium speciation by X-ray absorption fine structure (XAFS). Extended-XAFS (EXAFS) was used to determine the identity of the Pu(VI) interfacial complex with the bacteria, and the Pu(VI) was found primarily bound to phosphate groups on the cell surface. No carboxylate complexation was detected. (orig.)

  2. The Young Modulus of Black Strings and the Fine Structure of Blackfolds

    CERN Document Server

    Armas, Jay; Harmark, Troels; Obers, Niels A

    2011-01-01

    We explore corrections in the blackfold approach, which is a worldvolume theory capturing the dynamics of thin black branes. The corrections probe the fine structure of the branes, going beyond the approximation in which they are infinitely thin, and account for the dipole moment of worldvolume stress-energy as well as the internal spin degrees of freedom. We show that the dipole correction is induced elastically by bending a black brane. We argue that the long-wavelength transport coefficient capturing this response is a relativistic generalization of the Young modulus of elastic materials and we compute it analytically. Using this we draw predictions for black rings in dimensions greater than six. Furthermore, we employ our corrected blackfold equations to various multi-spinning black hole configurations in the blackfold limit, finding perfect agreement with known analytic solutions.

  3. Fine structure in the cosmic ray spectrum: Further analysis and the next step

    Science.gov (United States)

    Erlykin, A. D.; Wolfendale, A. W.

    2012-01-01

    An analysis is made of the fine structure in the cosmic ray energy spectrum: new facets of present observations and their interpretation and the next step. It is argued that less than about 10% of the intensity of the helium 'peak' at the knee at ≈5 PeV is due to just a few sources (SNR) other than the single source. The apparent concavity in the rigidity spectra of protons and helium nuclei which have maximum curvature at about 200 GV is confirmed by a joint analysis of the PAMELA, CREAM and ATIC experiments. The spectra of heavier nuclei also show remarkable structure in the form of 'ankles' at several hundred GeV/nucleon. Possible mechanisms are discussed. The search for 'pulsar peaks' has not yet proved successful.

  4. Relations between frequency selectivity, temporal fine-structure processing, and speech reception in impaired hearing

    DEFF Research Database (Denmark)

    Strelcyk, Olaf; Dau, Torsten

    2009-01-01

    and binaural TFS-processing deficits in the HI listeners, no relation was found between TFS processing and frequency selectivity. The effect of noise on TFS processing was not larger for the HI listeners than for the NH listeners. Finally, TFS-processing performance was correlated with speech reception......Frequency selectivity, temporal fine-structure (TFS) processing, and speech reception were assessed for six normal-hearing (NH) listeners, ten sensorineurally hearing-impaired (HI) listeners with similar high-frequency losses, and two listeners with an obscure dysfunction (OD). TFS processing...... was investigated at low frequencies in regions of normal hearing, through measurements of binaural masked detection, tone lateralization, and monaural frequency modulation (FM) detection. Lateralization and FM detection thresholds were measured in quiet and in background noise. Speech reception thresholds were...

  5. 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...

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

    Science.gov (United States)

    Holanda, R. F. L.; Landau, S. J.; Alcaniz, J. S.; Sánchez G., I. E.; Busti, V. C.

    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 (fgas) 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 fgas, in the redshift interval 0.14 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.

  7. 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.

  8. A study of fine structure of diffuse aurora with ALIS-FAST measurements

    Directory of Open Access Journals (Sweden)

    T. Sergienko

    2008-10-01

    Full Text Available We present results of an investigation of the fine structure of the night sector diffuse auroral zone, observed simultaneously with optical instruments (ALIS from the ground and the FAST electron spectrometer from space 16 February 1997. Both the optical and particle data show that the diffuse auroral zone consisted of two regions. The equatorward part of the diffuse aurora was occupied by a pattern of regular, parallel auroral stripes. The auroral stripes were significantly brighter than the background luminosity, had widths of approximately 5 km and moved southward with a velocity of about 100 m/s. The second region, located between the region with auroral stripes and the discrete auroral arcs to the north, was filled with weak and almost homogeneous luminosity, against which short-lived auroral rays and small patches appeared chaotically. From analysis of the electron differential fluxes corresponding to the different regions of the diffuse aurora and based on existing theories of the scattering process we conclude the following: Strong pitch angle diffusion by electron cyclotron harmonic waves (ECH of plasma sheet electrons in the energy range from a few hundred eV to 3–4 keV was responsible for the electron precipitation, that produced the background luminosity within the whole diffuse zone. The fine structure, represented by the auroral stripes, was created by precipitation of electrons above 3–4 keV as a result of pitch angle diffusion into the loss cone by whistler mode waves. A so called "internal gravity wave" (Safargaleev and Maltsev, 1986 may explain the formation of the regular spatial pattern formed by the auroral stripes in the equatorward part of the diffuse auroral zone.

  9. A study of fine structure of diffuse aurora with ALIS-FAST measurements

    Science.gov (United States)

    Sergienko, T.; Sandahl, I.; Gustavsson, B.; Andersson, L.; Brändström, U.; . Steen, Ã.

    2008-10-01

    We present results of an investigation of the fine structure of the night sector diffuse auroral zone, observed simultaneously with optical instruments (ALIS) from the ground and the FAST electron spectrometer from space 16 February 1997. Both the optical and particle data show that the diffuse auroral zone consisted of two regions. The equatorward part of the diffuse aurora was occupied by a pattern of regular, parallel auroral stripes. The auroral stripes were significantly brighter than the background luminosity, had widths of approximately 5 km and moved southward with a velocity of about 100 m/s. The second region, located between the region with auroral stripes and the discrete auroral arcs to the north, was filled with weak and almost homogeneous luminosity, against which short-lived auroral rays and small patches appeared chaotically. From analysis of the electron differential fluxes corresponding to the different regions of the diffuse aurora and based on existing theories of the scattering process we conclude the following: Strong pitch angle diffusion by electron cyclotron harmonic waves (ECH) of plasma sheet electrons in the energy range from a few hundred eV to 3 4 keV was responsible for the electron precipitation, that produced the background luminosity within the whole diffuse zone. The fine structure, represented by the auroral stripes, was created by precipitation of electrons above 3 4 keV as a result of pitch angle diffusion into the loss cone by whistler mode waves. A so called "internal gravity wave" (Safargaleev and Maltsev, 1986) may explain the formation of the regular spatial pattern formed by the auroral stripes in the equatorward part of the diffuse auroral zone.

  10. Spectral fine structure of the atomic ground states based on full relativistic theory

    Institute of Scientific and Technical Information of China (English)

    Zhenghe Zhu; Yongjian Tang

    2011-01-01

    @@ We focus on the full relativistic quantum mechanical calculations from boron to fluorine atoms with electronic configuration of 1s22s22pn (n = 1, 2, 3, 4, and 5), where 1s22s2 is the closed shell and 2pn is the open shell. Their active electrons in the open shell occupy all the six spinors as far as possible.Therefore, we suggest a new rule called "maximum probability" for the full symmetry group relativistic theory. Furthermore, the spectral fine structure of the atomic ground states based on the full relativistic theory and their intervals of L-S splitting are all reasonable. It is impossible to calculate the L-S splitting through non-relativistic quantum mechanics. The relativistic effect of atomic mass is increased significantly by about 12 folds from boron atom to fluorine atom.%We focus on the full relativistic quantum mechanical calculations from boron to fluorine atoms with electronic configuration of 1s22s22pn (n = 1, 2, 3, 4, and 5), where 1s22s2 is the closed shell and 2pn is the open shell. Their active electrons in the open shell occupy all the six spinors as far as possible.Therefore, we suggest a new rule called "maximum probability" for the full symmetry group relativistic theory. Furthermore, the spectral fine structure of the atomic ground states based on the full relativistic theory and their intervals of L-S splitting are all reasonable. It is impossible to calculate the L-S splitting through non-relativistic quantum mechanics. The relativistic effect of atomic mass is increased significantly by about 12 folds from boron atom to fluorine atom.

  11. 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

  12. On the Visibility of Prominence Fine Structures at Radio Millimeter Wavelengths

    Science.gov (United States)

    Heinzel, P.; Berlicki, A.; Bárta, M.; Karlický, M.; Rudawy, P.

    2015-07-01

    Prominence temperatures have so far mainly been determined by analyzing spectral line shapes, which is difficult when the spectral lines are optically thick. The radio spectra in the millimeter range offer a unique possibility to measure the kinetic temperature. However, studies in the past used data with insufficient spatial resolution to resolve the prominence fine structures. The aim of this article is to predict the visibility of prominence fine structures in the submillimeter/millimeter (SMM) domain, to estimate their brightness temperatures at various wavelengths, and to demonstrate the feasibility and usefulness of future high-resolution radio observations of solar prominences with ALMA ( Atacama Large Millimeter-submillimeter Array). Our novel approach is the conversion of H coronagraphic images into microwave spectral images. We show that the spatial variations of the prominence brightness both in the H line and in the SMM domain predominantly depend on the line-of-sight emission measure of the cool plasma, which we derive from the integrated intensities of the observed H line. This relation also offers a new possibility to determine the SMM optical thickness from simultaneous H observations with high resolution. We also describe how we determine the prominence kinetic temperature from SMM spectral images. Finally, we apply the ALMA image-processing software Common Astronomy Software Applications (CASA) to our simulated images to assess what ALMA would detect at a resolution level that is similar to the coronagraphic H images used in this study. Our results can thus help in preparations of first ALMA prominence observations in the frame of science and technical verification tests.

  13. Experimental fine-structure branching ratios for Na-rare-gas optical collisions

    Energy Technology Data Exchange (ETDEWEB)

    Havey, M.D.; Delahanty, F.T.; Vahala, L.L.; Copeland, G.E.

    1986-10-01

    Experimental ratios for branching into the fine-structure levels of the Na 3p multiplet, as a consequence of an optical collision with He, Ne, Ar, Kr, or Xe, are reported. The process studied is Na(3s /sup 2/S/sub 1/2/)+scrR+nh..nu -->..Na(3p /sup 2/P/sub j/)+scrR+(n-1)h..nu.., where scrR represents a rare-gas atom and where the laser frequency ..nu.. is tuned in the wings of the Na resonance transitions. The branching ratios are defined as I(D1)/I(D2) where I(D1) and I(D2) are measured intensities of the atomic Na D1 and D2 lines. The ratios are determined for detunings ranging from about 650 cm/sup -1/ in the blue wing to 170 cm/sup -1/ in the red wing of the Na 3p multiplet. The branching is found to be strongly detuning dependent in the vicinity of the NaAr, NaKr, and NaXe near-red-wing satellites. The blue-wing branching ratios show a detuning-dependent approach to a recoil, or sudden statistical, limit of 0.5, irrespective of the rare gas. Fine-structure changing cross sections have also been measured for resonant excitation of the Na 3p /sup 2/P/sub j/ state; the results are consistent with cross sections obtained from wing excitation.

  14. 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

  15. Bond forming reactions of carbyne and nitrene complexes. Final technical report for DE-FG02-96ER14608

    Energy Technology Data Exchange (ETDEWEB)

    Templeton, J.L.

    2002-09-01

    An isolobal relationship among terminal carbyne, nitrene and oxo ligands provided the basis for our efforts to explore new synthetic routes to such complexes and to probe bond forming reactions of these ligands. The specific goals of this project were to explore reactions of carbyne and nitrene ligands, and a summary of our results follows. Manipulation of metal-ligand pi bonds to control reactivity patterns provided the conceptual basis for this work. New transformations and coupling reactions of the CR and NR moieties bound to metal centers have been explored and transformations of carbyne or nitrene ligands have been achieved. Perhaps the most exciting results have come in the area of the simplest ligand: the CH carbyne unit. Treatment of [Tp'(CO){sub 2}W{triple_bond}C-PPh{sub 3}] [PF{sub 6}] Tp' = hydridotris(3,5-dimethylpyrazolylborate) with Na[HBEt{sub 3}] forms the methylidyne complex Tp' (CO){sub 2}W{triple_bond}C-H via formyl and carbene intermediates. Protonation of the Tp'(CO){sub 2}W{triple_bond}C-H methylidyne complex yields the cationic agostic methylidene complex, [Tp'(CO){sub 2}W=CH{sub 2}][BF{sub 4}]. The methylidyne complex with a pK{sub a} of 28.7 can be deprotonated to provide the anionic terminal carbide Tp' (CO){sub 2}W{triple_bond}C-Li; a resonance at 556 ppm in the {sup 13}C NMR spectrum has been assigned to the carbide carbon. Addition of excess Na[HBEt{sub 3}] to Tp'(CO){sub 2}W{triple_bond}C-H generates the anionic methylidene complex [Na] [Tp'(CO){sub 2}W{triple_bond}CH{sub 2}].

  16. 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

    The impact of diurnal photosynthetic activity on the fine structure of the amylopectin fraction of starch synthesized by normal barley (NBS) and waxy barley (WBS), the latter completely devoid of amylose biosynthesis, was determined following the cultivation under normal diurnal or constant light...... 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...... under constant light. Our data demonstrate that the diurnal light regime influences the fine structure of the amylopectin component both in amylose and non-amylose starch granules....

  17. Status and outlook of the CRYRING@ESR project

    Energy Technology Data Exchange (ETDEWEB)

    Geithner, W., E-mail: w.geithner@gsi.de; Andelkovic, Z.; Beck, D.; Bräuning, H.; Bräuning-Demian, A. [GSI Helmholtzzentrum für Schwerionenforschung (Germany); Danared, H. [European Spallation Source ESS (Sweden); Dimopoulou, C. [GSI Helmholtzzentrum für Schwerionenforschung (Germany); Engström, M. [Fysikum, Stockholm University (Sweden); Fedotova, S.; Gorda, O.; Herfurth, F.; Hess, R. [GSI Helmholtzzentrum für Schwerionenforschung (Germany); Källberg, A. [Fysikum, Stockholm University (Sweden); Kleffner, C.; Kotovskiy, N.; Kraus, I.; Lestinsky, M.; Litvinov, S.; Nolden, F.; Reiter, A. [GSI Helmholtzzentrum für Schwerionenforschung (Germany); and others

    2017-11-15

    Once operational, CRYRING@ESR will store and decelerate ions delivered by the experimental storage ring ESR at energies well below those of ESR. In addition to that, CRYRING@ESR has an electron cooler operating with an ultracold electron beam, allowing to provide cooled ion beams for precision experiments. These ions will be delivered to a broad range of experiments presently in preparation; either in-ring or extracted to a dedicated beamline for experiments. An overview and status report of the installation and commissioning of the CRYRING-@ESR storage ring for highly charged ions at the GSI Helmholtzzentrum für Schwerionenforschung is presented. The installation of this storage ring started in 2014 and was completing end of 2016, when this publication was written.

  18. Global and local reactivity of simple substituted nitrenes and phosphinidenes within the spin-polarized density functional theory framework

    Science.gov (United States)

    Rincón, Elizabeth; Pérez, Patricia; Chamorro, Eduardo

    2007-11-01

    The local reactivity proclivities in a series of simple substituted nitrenes (N-X) and phosphinidenes (P-X) have been explored for the lowest-lying singlet and triplet electronic states within the framework of spin-polarized density functional theory (SP-DFT). Linear correlations have been found between both the global and local philicities for spin polarization and the vertical singlet-triplet energy gaps. The accumulation and depletion of the electron or spin density can be directly related to the electronegativity of the substituent atoms. The local analysis has been achieved on the basis of a recent implementation of condensed-to-site SP-DFT Fukui functions.

  19. Criticality accident dosimetry with ESR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    D`Errico, F. [DCMN, Universita degli Studi di Pisa (Italy); Fattibene, P.; Onori, S.; Pantaloni, M. [Istituto Superiore di Sanita, Rome (Italy). Lab. di Fisica

    1997-01-01

    The suitability of the ESR alanine and sugar detectors for criticality accident dosimetry was experimentally investigated during an intercomparison of dosimetry techniques. Tests were performed irradiating detectors both free-in-air and on-phantom during controlled criticality excursions at the SILENE reactor in Valduc, France. Several grays of absorbed dose were imparted in neutron gamma-ray fields of various relative intensities and spectral distributions. Analysed results confirmed the potential of these systems which can immediately provide an acute dose assessment with an average underestimate of 30% in the various fields. This performance allows for the screening of severely exposed individuals and meets the IAEA recommendations on the early estimate of accident absorbed doses. (Author).

  20. Observation of the fine structure for rovibronic spectral lines in visible part of emission spectra of $D_2$

    CERN Document Server

    Lavrov, B P; Zhukov, A S

    2011-01-01

    For the first time the fine structure of rovibronic spectral lines in visible part of emission spectra of $D_2$ molecule has been observed. Observed splitting in visible doublets is about 0.2 cm$^{-1}$ in good accordance with previous observations in the infrared part of the spectrum ($a^3\\Sigma_g^+ \\to c^3\\Pi_u$ electronic transition) by means of FTIR and laser spectroscopy. Relative intensities of the fine structure components are in agreement with our calculations of adiabatic line strengths for Hund's case "b" coupling scheme.

  1. Interesting Features of n2D Rydberg Series Fine-Structure Splittings along the Sodium-Like Isoelectronic Sequence

    Institute of Scientific and Technical Information of China (English)

    WANG Xiao-Lu; LIU Ling-Tao; GAO Xiang; SHEN Chun; LI Jia-Ming

    2008-01-01

    @@ Using a simplified multi-configuration Dirac-Fock (SMCDF) scheme based on the multi-configuration Dirac-Fock (MCDF) theory, we study the systematic variations of the fine-structure splittings of n2 D3/2,5/2 Rydberg series along the sodium-like isoelectronic sequence, i.e.the fine-structure orderings vary with increasing atomic number Z.The competition between the spin-orbit interactions and the exchange interactions due to relativistic effects of the nd orbital wavefunctions well explain such variations.Furthermore, the effect of Breit interactions which plays the secondary role is studied.

  2. Theoretical Study of Interesting Fine-Structure Splittings for 23P0,1,2 States along Helium Isoelectronic Sequence

    Institute of Scientific and Technical Information of China (English)

    QING Bo; CHEN Shao-Hao; GAO Xiang; LI Jia-Ming

    2008-01-01

    Using the multi-configuration Dirac-Fock method including the Breit interactions and QED corrections, we calculate the fine-structure energy levels of the 23P,0,1,2 states along the helium isoelectronic sequence with atomic number up to Z=36, where LS-coupling is appropriate. Our calculation results agree with the experimental results within about 1%. We elucidate the mechanism of the interesting fine-structure splittings for the 23P,0,1,2 states along the helium isoelectronic sequence, I. E. The competitions between the spin-orbit interactions and the Breit interactions which represent the relativistic retardation effect of electromagnetic interactions.

  3. Model for the fine structure of zero field steps in long Josephson tunnel junctions and its comparison with experiment

    DEFF Research Database (Denmark)

    Barbara, Paola; Monaco, R.; Ustinov, A. V.

    1996-01-01

    The single fluxon dynamics in the resonant regime has been investigated on high-quality low-loss Nb/Al–AlOx/Nb window Josephson tunnel junctions. A new model accounting for the fine structure of zero field steps in linear junctions is proposed. Depending on the fluxon velocity and on the junction...... simulations, and experiments. The presence of the idle region has been proved to play a determinant role for the occurrence of the fine structure. ©1996 American Institute of Physics....

  4. Cluster model calculation of N near K-edge energy-loss fine structures in hexagonal GaN crystal

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A cluster model is used to calculate electron energy-loss fine structures in crystal. The multiple-scattering self-consistent-field method is employed in the calculation. Our theoretical results of N near K-edge energy loss fine structures in hexagonal GaN crystal are in good agreement with the experimental spectra. Future possible experiments in energy-filtered transmission electron microscopy (EFTEM) are discussed and proposed because our theoretical work can provide clear assignments for transmitted electrons with different energy losses.

  5. 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

  6. 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

  7. Rotational and Fine Structure of Pseudo-Jahn Molecules with C_1 Symmetry

    Science.gov (United States)

    Liu, Jinjun

    2016-06-01

    It has been found in our previous works that rotational and fine-structure analysis of spectra involving nearly degenerate electronic states may aid in interpretation and analysis of the vibronic structure, specifically in the case of pseudo-Jahn-Teller (pJT) molecules with C_s symmetry. The spectral analysis of pJT derivatives (isopropoxy and cyclohexoxy of a prototypical JT molecule (the methoxy radical) allowed for quantitative determination of various contributions to the energy separation between the nearly degenerate electronic states, including the relativistic spin-orbit (SO) effect, the electrostatic interaction, and their zero-point energy difference. These states are coupled by SO and Coriolis interactions, which can also be determined accurately in rotational and fine structure analysis. Most recently, the spectroscopic model for rotational analysis of pJT molecules has been extended for analysis of molecules with C_1 symmetry, i.e., no symmetry. This model includes the six independently determinable components of the spin-rotation (SR) tensor and the three components of the SO and Coriolis interactions. It has been employed to simulate and fit high-resolution laser-induced fluorescence (LIF) spectra of jet-cooled alkoxy radicals with C_1 symmetry, including the 2-hexoxy and the 2-pentoxy radicals, as well as previously recorded LIF spectrum of the trans-conformer (defined by its OCCC dihedral angle) of the 2-butoxy radical. Although the LIF spectra can be reproduced by using either the SR constants or SO and Coriolis constants, the latter simulation offers results that are physically more meaningful whereas the SR constants have to be regarded as effective constants. Furthermore, we will review the SO and Coriolis constants of alkoxy radicals that have been investigated, starting from the well-studied methoxy radical (CH_3O). J. Liu, D. Melnik, and T. A. Miller, J. Chem. Phys. 139, 094308 (2013) J. Liu and T. A. Miller, J. Phys. Chem. A 118, 11871

  8. Periodicity extraction in the anuran auditory nerve. II: Phase and temporal fine structure.

    Science.gov (United States)

    Simmons, A M; Reese, G; Ferragamo, M

    1993-06-01

    Discharge patterns of single eighth nerve fibers in the bullfrog, Rana catesbeiana, were analyzed in response to signals consisting of multiple harmonics of a common, low-amplitude fundamental frequency. The signals were chosen to reflect the frequency and amplitude spectrum of the bullfrog's species-specific advertisement call. The phase spectrum of the signals was manipulated to produce envelopes that varied in their shapes from impulselike (sharp) to noiselike (flattened). Peripheral responses to these signals were analyzed by computing the autocorrelation functions of the spike trains and their power spectra, as well as by constructing period histograms over the time intervals of the low-frequency harmonics. In response to a phase aligned signal with an impulsive envelope, most fibers, regardless of their characteristic frequencies or place of origin within the inner ear, synchronize to the fundamental frequency of the signal. The temporal patterns of fiber discharge to these stimuli are not typically captured by that stimulus harmonic closet to the fiber characteristic frequency, as would be expected from a spectral coding mechanism for periodicity extraction, but instead directly reflect the periodicity of the stimulus envelope. Changing the phase relations between the individual harmonics constituting the signal produces changes in temporal discharge patterns of some fibers by shifting predominant synchronization away from the fundamental frequency to the low-frequency spectral peak in the complex stimuli. The proportion of fibers whose firing is captured by the fundamental frequency decreases as the waveform envelope becomes less impulselike. Fiber characteristic frequency is not highly correlated with the harmonic number to which synchronization is strongest. The higher-harmonic spectral fine structure of the signals is not reflected in fiber temporal response, regardless of the shape of the stimulus envelope, even for those harmonics within the range of

  9. 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

  10. Spin-state dependent radical stabilization in nitrenes: the unusually small singlet-triplet splitting in 2-furanylnitrene.

    Science.gov (United States)

    Wenthold, Paul G

    2012-01-06

    Geometries and energies of the triplet and singlet states of 2-furanylnitrene and 3-furanylnitrene have been calculated by using spin-flip coupled-cluster methods. Calculations with triple-ζ basis sets predict a singlet-triplet splitting of 10.9 kcal/mol for 2-furanylnitrene, 4.5 kcal/mol smaller than that in phenylnitrene. In contrast, the singlet-triplet splitting in 3-furanylnitrene is computed to be 1.9 kcal/mol larger than that in phenylnitrene. The differences in the singlet-triplet splittings for the furanylnitrenes are attributed to the differences in the radical stabilizing abilities of the 2-furanyl- and 3-furanyl-groups compared to a phenyl ring. Comparison of the singlet-triplet splittings of more than 20 substituted aromatic nitrenes and the radical stabilizing ability of the aromatic systems reveals a high degree of correlation between the singlet-triplet splitting and the radical stabilizing ability, indicating that singlet states of aromatic nitrenes are preferentially stabilized by radical stabilizing substituents. The preferential stabilization of the singlet states is attributed to the decrease in electron pair repulsion resulting from increased delocalization of the radical electron.

  11. Organic functionalization of the Si (100) and Ge (100) surfaces by cycloadditions of carbenes and nitrenes: a theoretical prediction.

    Science.gov (United States)

    Xu, Yi-Jun; Zhang, Yong-Fan; Li, Jun-Qian

    2006-02-23

    By means of density functional theory (B3LYP/6-31G*) coupled with effective cluster models, we predict that the well-known cycloaddition reactions of carbenes and nitrenes to alkenes in organic chemistry can be employed as a new type of surface reaction to organically functionalize the Si (100) and Ge (100) surfaces at low temperature. The well-established abundance of carbenes and nitrenes addition chemistry in organic chemistry provides versatile flexibility of functionalizing the surfaces of Si (100) and Ge (100), which can potentially impart new organic functionalities to the semiconductors surface for novel applications in a diversity of fields. Our predictions strongly advance the concept of using organic reactions to modify the solid surface in a controlled manner and quite intriguing chemistry can lie in the material featuring the analogous bonding motif. In further perspective, implications for other theoretical work, regarding disilenes, digermenes, silenes, and germenes that all feature the bonding motif similar to alkenes, are also discussed.

  12. Control of the Chemoselectivity of Metal N-Aryl Nitrene Reactivity: C-H Bond Amination versus Electrocyclization.

    Science.gov (United States)

    Kong, Chen; Jana, Navendu; Jones, Crystalann; Driver, Tom G

    2016-10-04

    A mechanism study to identify the elements that control the chemoselectivity of metal-catalyzed N-atom transfer reactions of styryl azides is presented. Our studies show that the proclivity of the metal N-aryl nitrene to participate in sp(3)-C-H bond amination or electrocyclization reactions can be controlled by either the substrate or the catalyst. Electrocyclization is favored for mono-β-substituted and sterically noncongested styryl azides, whereas sp(3)-C-H bond amination through an H-atom abstraction-radical recombination mechanism is preferred when a tertiary allylic reaction center is present. Even when a weakened allylic C-H bond is present, our data suggest that the indole is still formed through an electrocyclization instead of a common allyl radical intermediate. The site selectivity of metal N-aryl nitrenes was found to be controlled by the choice of catalyst: Ir(I)-alkene complexes trigger electrocyclization processes while Fe(III) porphyrin complexes catalyze sp(3)-C-H bond amination in substrates where Rh2(II) carboxylate catalysts provide both products.

  13. Properties of the prominence magnetic field and plasma distributions as obtained from 3D whole-prominence fine structure modeling

    Science.gov (United States)

    Gunár, S.; Mackay, D. H.

    2016-07-01

    Aims: We analyze distributions of the magnetic field strength and prominence plasma (temperature, pressure, plasma β, and mass) using the 3D whole-prominence fine structure model. Methods: The model combines a 3D magnetic field configuration of an entire prominence, obtained from non-linear force-free field simulations, with a detailed semi-empirically derived description of the prominence plasma. The plasma is located in magnetic dips in hydrostatic equilibrium and is distributed along multiple fine structures within the 3D magnetic model. Results: We show that in the modeled prominence, the variations of the magnetic field strength and its orientation are insignificant on scales comparable to the smallest dimensions of the observed prominence fine structures. We also show the ability of the 3D whole-prominence fine structure model to reveal the distribution of the prominence plasma with respect to its temperature within the prominence volume. This provides new insights into the composition of the prominence-corona transition region. We further demonstrate that the values of the plasma β are small throughout the majority of the modeled prominences when realistic photospheric magnetic flux distributions and prominence plasma parameters are assumed. While this is generally true, we also find that in the region with the deepest magnetic dips, the plasma β may increase towards unity. Finally, we show that the mass of the modeled prominence plasma is in good agreement with the mass of observed non-eruptive prominences.

  14. Fine structure of the entanglement entropy in the O(2) model

    Science.gov (United States)

    Yang, Li-Ping; Liu, Yuzhi; Zou, Haiyuan; Xie, Z. Y.; Meurice, Y.

    2016-01-01

    We compare two calculations of the particle density in the superfluid phase of the O(2) model with a chemical potential μ in 1+1 dimensions. The first relies on exact blocking formulas from the Tensor Renormalization Group (TRG) formulation of the transfer matrix. The second is a worm algorithm. We show that the particle number distributions obtained with the two methods agree well. We use the TRG method to calculate the thermal entropy and the entanglement entropy. We describe the particle density, the two entropies and the topology of the world lines as we increase μ to go across the superfluid phase between the first two Mott insulating phases. For a sufficiently large temporal size, this process reveals an interesting fine structure: the average particle number and the winding number of most of the world lines in the Euclidean time direction increase by one unit at a time. At each step, the thermal entropy develops a peak and the entanglement entropy increases until we reach half-filling and then decreases in a way that approximately mirrors the ascent. This suggests an approximate fermionic picture.

  15. 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.

  16. ;Long-hissler; fine structure within auroral hiss: A review and synthesis

    Science.gov (United States)

    Kim, Howard F.; LaBelle, James; Spasojević, Maria

    2017-04-01

    One of the most prominent fine-structures of auroral hiss is the ;long-hissler;, defined here as a dispersed feature embedded within broadband auroral hiss emissions in the frequency range 1-40 kHz and lasting longer than 0.3 s. While theory is limited, there is evidence that hisslers can be used in remote sensing of density characteristics at altitudes of thousands of km. By applying an automatic threshold algorithm to VLF data collected at South Pole 2230-0130 UT daily during June-August 2014, 22 h of auroral hiss are identified on 49 of 93 days analyzed, for an occurrence rate of 9.7% during the applicable MLT interval. From manual inspection of these intervals, 414 groups (trains) of long hisslers are identified on 34 of the 49 days on which hiss occurred. Median lower (upper) frequency bounds of these features are 8 (22) kHz, median frequency-time slope is -10 kHz/s, and median hissler repetition time within a train (hissler period) is 1.2 s. Hissler period and frequency-time slope are inversely related. Data from previous studies are reviewed to provide a comprehensive description of the phenomenon. Contrary to some previous studies, subsequent long hissler features are found to commonly overlap in time, and no evidence is found for an inverse relationship between hissler train duration and geomagnetic activity.

  17. 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].

  18. Fine structures and dynamics in auroral initial brightening at substorm onsets

    Directory of Open Access Journals (Sweden)

    K. Sakaguchi

    2009-02-01

    Full Text Available We show four auroral initial brightening events at substorm onsets focusing on fine structures and their longitudinal dynamics, which were observed by all-sky TV cameras (30-Hz sampling on January 2008, in Canada. For two initial brightenings started in the field of views of the cameras, we found that they started at longitudinal segments with a size of less than ~30–60 km. One brightening expanded with wavy structures and the other expanded as a straight arc. Although the two events had different structures, both brightening auroras expanded with an average speed of ~20 km/s in the first 10 s, and ~10 km/s in the following 10 s. The other two events show that brightening auroras developed with periodic structures, with longitudinal wavelengths of ~100–200 km. Assuming that the brightening auroras are mapped to the physical processes occurring in the plasma sheet, we found that the scale size (30–60 km and the expanding speed (20 km/s of brightening auroras correspond to the order of ion gyro radii (~500–1400 km and Alfvén speed or fast ion-flow speed (~400 km/s, respectively, in the plasma sheet.

  19. Radio Fiber Fine Structure During the Solar Flare on July 14,2000

    Institute of Scientific and Technical Information of China (English)

    钟晓春; 王蜀娟

    2004-01-01

    On July 14, 2000, a type IV solar radio burst was observed at 10:43-11:00 UT with the 1-2 GHz digital spectrometer of National Astronomical Observatories of China (NAOC). Many fiber fine structures superposed on the type IV burst were detected in the same interval. A theoretical interpretation for the fibers is performed based upon a model of magnetic-mirror loop configuration in the solar corona. In this model, the source of the fiber emission is considered as the ducting of whistler solitons within the magnetic-mirror loop. A quantitative estimation using the observed data indicats that the magnetic field strength of the radio source is about 1.451×10-2≤B0≤2.734×10-2 T, and that a fiber is composed of 4×1015 solitons occupying a volume of about 1.2×108 km3. For the duct through which the whistler solitons passed within the magnetic-mirror loop, its diameter and the length are worked out, namely, d≈120 km and Δr≈104 km, respectively.

  20. Propagation of whistler waves driven by fine structured ion beams in the magnetotail

    Science.gov (United States)

    Burinskaya, T.; Schriver, D.; Ashour-Abdalla, M.

    1994-01-01

    In a previous paper, which examined the propagation of low-frequency whistler waves generated by ion beams in the Earth's plasma sheet boundary layer (PSBL), it was found that whistler waves driven in the PSBL are focused toward the central plasma sheet due to the global magnetotail inhomogeneities; this finding may help explain the observations of magnetic noise bursts in the tail (Burinskaya et al., 1993). In this paper the same phenomenon is examined, but this time a much more realistic model is used for the ion beam in the PSBL. While the PSBL has been modeled as a solid, homogeneous ion beams with a width of one Earth radius, observations and theoretical considerations have shown that PSBL ion beams actually have a decreasing velocity profile toward the plasma sheet and that the density of the beams within the PSBL can vary locally. We consider again the propagation and generation of electromagnetic waves but in the presence of fine structured ion beams in the PSBL. Our results show that whistler waves, generated quasi-parallel to the background magnetic field, can be trapped locally within small spatial regions where the ion beam density is enhanced compared to the density of the adjacent PSBL region. Wave spectra and nonlinear saturation mechanisms are discussed.

  1. FDMX: extended X-ray absorption fine structure calculations using the finite difference method.

    Science.gov (United States)

    Bourke, Jay D; Chantler, Christopher T; Joly, Yves

    2016-03-01

    A new theoretical approach and computational package, FDMX, for general calculations of X-ray absorption fine structure (XAFS) over an extended energy range within a full-potential model is presented. The final-state photoelectron wavefunction is calculated over an energy-dependent spatial mesh, allowing for a complete representation of all scattering paths. The electronic potentials and corresponding wavefunctions are subject to constraints based on physicality and self-consistency, allowing for accurate absorption cross sections in the near-edge region, while higher-energy results are enabled by the implementation of effective Debye-Waller damping and new implementations of second-order lifetime broadening. These include inelastic photoelectron scattering and, for the first time, plasmon excitation coupling. This is the first full-potential package available that can calculate accurate XAFS spectra across a complete energy range within a single framework and without fitted parameters. Example spectra are provided for elemental Sn, rutile TiO2 and the FeO6 octahedron.

  2. Electronic fine structure in the nickel carbide superconductor Th2NiC2

    Science.gov (United States)

    Quan, Y.; Pickett, W. E.

    2013-07-01

    The recently reported nickel carbide superconductor body centered tetragonal I4/mmm Th2NiC2 with Tc=8.5 K increasing to 11.2 K upon alloying Th with Sc is found to have very fine structure in its electronic spectrum, according to density functional based first-principles calculations. The filled Ni 3d band complex is hybridized with C 2p and Th character to and through the Fermi level (EF), and a sharply structured density of states arises only when spin-orbit coupling is included, which splits a zone-center degeneracy, leaving a very flat band edge lying at the Fermi level. The flat part of the band corresponds to an effective mass mz*→∞ with large and negative mx*=my*. Although the region over which the effective mass characterization applies is less than 1% of the zone volume, it supplies on the order of half the states at (or just above) the Fermi level. The observed increase of Tc by hole doping is accounted for if the reference as-synthesized sample is minutely hole doped, which decreases the Fermi level density of states and will provide some stabilization. In this scenario, electron doping will increase the Fermi level density of states and the superconducting critical temperature. Vibrational properties are presented, and enough coupling to the C-Ni-C stretch mode at 70 meV is obtained to imply that superconductivity is electron-phonon mediated.

  3. Possible evidence for a variable fine structure constant from QSO absorption lines motivations, analysis and results

    CERN Document Server

    Murphy, M T; Flambaum, V V; Dzuba, V A; Churchill, C W; Prochaska, J X; Barrow, John D; Wolfe, A M

    2001-01-01

    An experimental search for variation in the fundamental coupling constants is strongly motivated by modern high-energy physics theories. Comparison of quasar absorption line spectra with laboratory spectra provides a sensitive probe for variability of the fine structure constant, alpha, over cosmological time-scales. We have previously developed and applied a new method providing an order of magnitude gain in precision over previous optical astrophysical constraints. Here we extend that work by including new quasar spectra of damped Lyman-alpha absorption systems. We also re-analyse our previous lower redshift data and confirm our initial results. The constraints on alpha come from simultaneous fitting of absorption lines of subsets of the following species: Mg I, Mg II, Al II, Al III, Si II, Cr II, Fe II, Ni II and Zn II. We present a detailed description of our methods and results based on an analysis of 49 quasar absorption systems (towards 28 QSOs) covering the redshift range 0.5 < z < 3.5. There is...

  4. Formation of galaxies in {\\Lambda}CDM cosmologies. I. The fine structure of disc galaxies

    CERN Document Server

    Doménech-Moral, Mariola; Domínguez-Tenreiro, Rosa; Serna, Arturo

    2012-01-01

    We present a detailed analysis of the global and fine structure of four middle-mass disc galaxies obtained from simulations in a $\\Lambda$CDM scenario. These objects have photometric D/T ratios in good agreement with those observed for late-type spirals, as well as kinematic properties in agreement with the observational Tully-Fisher relation. We identify the different dynamical components at z=0 on the basis of both orbital parameters and the binding energy of stars in the galaxy. In this way, we recognize a slowly rotating centrally concentrated spheroid, and two disc components supported by rotation: a thin disc with stars in nearly circular orbits, and a thick disc with orbital parameters transitional between the thin disc and the spheroid. The spheroidal component is composed mainly by old, metal-poor and {\\alpha}-enhanced stars. The distribution of metals in this component shows, however, a clear bimodality with a low-metallicity peak, which could be related to a classical bulge, and a high-metallicity ...

  5. Non-linear electrodynamics and the variation of the fine structure constant

    Science.gov (United States)

    Mbelek, Jean Paul; Mosquera Cuesta, Herman J.

    2008-09-01

    It has been claimed that during the late-time history of our Universe, the fine structure constant of electromagnetism, α, has been increasing. The conclusion is achieved after looking at the separation between lines of ions like CIV, MgII, SiII, FeII, among others in the absorption spectra of very distant quasars, and comparing them with their counterparts obtained in the laboratory. However, in the meantime, other teams have claimed either a null result or a decreasing α with respect to the cosmic time. Also, the current precision of laboratory tests does not allow one to either comfort or reject any of these astronomical observations. Here, we suggest that as photons are the sidereal messengers, a non-linear electrodynamics (NLED) description of the interaction of photons with the weak local background magnetic fields of a gas cloud absorber around the emitting quasar can reconcile the Chand et al. and Levshakov et al. findings with the negative variation found by Murphy et al. and Webb et al., and also to find a bridge with the positive variation argued more recently by Levshakov et al. We also show that NLED photon propagation in a vacuum permeated by a background magnetic field presents a full agreement with constraints from Oklo natural reactor data. Finally, we show that NLED may render a null result only in a narrow range of the local background magnetic field which should be the case of both the claims by Chand et al. and by Srianand et al.

  6. 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.

  7. Sorption mechanisms of zinc to calcium silicate hydrate: X-ray absorption fine structure (XAFS) investigation.

    Science.gov (United States)

    Ziegler, F; Scheidegger, A M; Johnson, C A; Dähn, R; Wieland, E

    2001-04-01

    In this study, X-ray absorption fine structure (XAFS) spectroscopy has been used to further elucidate the binding mechanisms of Zn(II) to calcium silicate hydrate (C-S-H), the quantitatively most important cement mineral. Such knowledge is essential for the assessment of the longterm behavior of cement-stabilized waste materials. XAFS spectra of the Zn(II) equilibrated with C-S-H(I) for up to 28 days are best modeled by tetrahedral coordination of Zn(II) by four O atoms in the first atomic shell. Beyond the first coordination shell, data analysis of more highly concentrated samples suggests the presence of two distinct Zn distances and possibly the presence of an Si shell. On the basis of the comparison with a set of reference compounds, this coordination environment can be reasonably related to the structure of hemimorphite, a naturally occurring zinc silicate, and/or the presence of gamma-Zn(OH)2. At the lowest Zn uptake, the above fitting approach failed and data could be described best with a Zn-Si and a Zn-Ca shell. Previous work has been able to show that Zn(II) diffuses into the C-S-H(I) particles and does not form discrete precipitates, so the findings appear to confirm the incorporation of Zn(II) in the interlayer of C-S-H(I).

  8. A new analysis of fine-structure constant measurements and modelling errors from quasar absorption lines

    CERN Document Server

    Wilczynska, Michael R; King, Julian A; Murphy, Michael T; Bainbridge, Matthew B; Flambaum, Victor V

    2015-01-01

    We present an analysis of 23 absorption systems along the lines of sight towards 18 quasars in the redshift range of $0.4 \\leq z_{abs} \\leq 2.3$ observed on the Very Large Telescope (VLT) using the Ultraviolet and Visual Echelle Spectrograph (UVES). Considering both statistical and systematic error contributions we find a robust estimate of the weighted mean deviation of the fine-structure constant from its current, laboratory value of $\\Delta\\alpha/\\alpha=\\left(0.22\\pm0.23\\right)\\times10^{-5}$, consistent with the dipole variation reported in Webb et al. and King et al. This paper also examines modelling methodologies and systematic effects. In particular we focus on the consequences of fitting quasar absorption systems with too few absorbing components and of selectively fitting only the stronger components in an absorption complex. We show that using insufficient continuum regions around an absorption complex causes a significant increase in the scatter of a sample of $\\Delta\\alpha/\\alpha$ measurements, th...

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

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    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.

  10. Synthesis, fine structural characterization, and CO2 adsorption capacity of metal organic frameworks-74.

    Science.gov (United States)

    Adhikari, Abhijit Krishna; Lin, Kuen-Song

    2014-04-01

    Two metal organic frameworks of MOF-74 group (zinc and copper-based) were successfully synthesized, characterized, and evaluated for CO2 adsorption. The both samples such as MOF-74(Zn) and MOF-74(Cu) were characterized with FE-SEM for morphology and particle size, XRD patterns for phase structure, FTIR for organic functional groups, nitrogen adsorption for pore textural properties, and X-ray absorption spectroscopy for fine structural parameters and oxidation states of central metal atoms. CO2 adsorption isotherms of MOF-74 samples were measured in a volumetric adsorption unit at 273 K and pressure up to 1.1 bar. The MOF-74(Zn) and MOF-74(Cu) adsorbents have the pore widths of 8.58 and 8.04 angstroms with the BET specific surface areas of 1,474 and 1,345 m2 g(-1), respectively. CO2 adsorption capacities of MOF-74(Zn) and MOF-74(Cu) were 4.10 and 3.38 mmol x g(-1), respectively measured at 273 K and 1.1 bar. The oxidation state of central atoms in MOF-74(Zn) was Zn(II) confirmed by XANES spectra while MOF-74(Cu) was composed of Cu(I) and Cu(II) central atoms. The bond distances of Zn--O and Cu--O were 1.98 and 1.94 angstroms, respectively.

  11. Scattering pulse of label free fine structure cells to determine the size scale of scattering structures

    Science.gov (United States)

    Zhang, Lu; Chen, Xingyu; Zhang, Zhenxi; Chen, Wei; Zhao, Hong; Zhao, Xin; Li, Kaixing; Yuan, Li

    2016-04-01

    Scattering pulse is sensitive to the morphology and components of each single label-free cell. The most direct detection result, label free cell's scattering pulse is studied in this paper as a novel trait to recognize large malignant cells from small normal cells. A set of intrinsic scattering pulse calculation method is figured out, which combines both hydraulic focusing theory and small particle's scattering principle. Based on the scattering detection angle ranges of widely used flow cytometry, the scattering pulses formed by cell scattering energy in forward scattering angle 2°-5° and side scattering angle 80°-110° are discussed. Combining the analysis of cell's illuminating light energy, the peak, area, and full width at half maximum (FWHM) of label free cells' scattering pulses for fine structure cells with diameter 1-20 μm are studied to extract the interrelations of scattering pulse's features and cell's morphology. The theoretical and experimental results show that cell's diameter and FWHM of its scattering pulse agree with approximate linear distribution; the peak and area of scattering pulse do not always increase with cell's diameter becoming larger, but when cell's diameter is less than about 16 μm the monotone increasing relation of scattering pulse peak or area with cell's diameter can be obtained. This relationship between the features of scattering pulse and cell's size is potentially a useful but very simple criterion to distinguishing malignant and normal cells by their sizes and morphologies in label free cells clinical examinations.

  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. Strain-tuning of the excitonic fine structure splitting in semiconductor quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Plumhof, Johannes D.; Ding, Fei; Herklotz, Andreas; Doerr, Kathrin; Rastelli, Armando; Schmidt, Oliver G. [IFW Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany); Krapek, Vlastimil; Klenovsky, Petr [Institute of Condensed Matter Physics, Masaryk University, Kotlarska 2, 61137 Brno (Czech Republic); Joens, Klaus D.; Hafenbrak, Robert; Michler, Peter [Institut fuer Halbleiteroptik und Funktionelle Grenzflaechen, University of Stuttgart, Allmandring 3, 70569 Stuttgart (Germany)

    2011-07-01

    For the creation of polarization entangled photon pairs from semiconductor quantum dots (QDs) it is important to decrease the fine structure splitting (FSS) of the neutral exciton to energies comparable to the emission linewidth. We employ a piezoelectric actuator (PMN-PT) to manipulate the excitonic emission of GaAs/AlGaAs as well as InGaAs/GaAs QDs embedded in {approx}200 nm thick (Al)GaAs membranes. By attaching the membranes on the PMN-PT we can apply anisotropic strain to the nanostructures. Polarization resolved {mu}-photoluminescence spectroscopy is used to estimate the excitonic FSS as well as the orientation of the linear polarization of the emitted light. The strain makes it possible to manipulate the FSS in a range of 70 {mu} eV. We also observe rotations of up to 70 of the linear polarization of the light emitted by neutral excitons. These effects can be explained as an strain-induced anticrossing of the bright excitonic states.

  14. Retinal pigment epithelial fine structure in the red-tailed hawk (Buto jamaicensis).

    Science.gov (United States)

    Braekevelt, C R

    1992-03-01

    As part of a comparative morphological study, the fine structure of the retinal epithelium (RPE), choriocapillaris and Bruch's membrane (complexus basalis) has been studied by electron microscopy in the red-tailed hawk (Buteo jamaicensis). In this species the RPE consists of a single layer of low cuboidal cells which display numerous basal (scleral) infoldings and extensive apical (vitreal) processes which interdigitate with photoreceptor outer segments. These epithelial cells are joined laterally by a series of basally located tight junctions. Internally SER is the most abundant cell organelle while only small amounts of RER are present. Polysomes are however abundant as are mitochondria. The RPE cell nucleus is large and vesicular. Melanosomes are mainly located in the apical processes of the RPE cells in light-adaptation. Myeloid bodies are large and numerous in light-adaptation and often show ribosomes on their outer border. Bruch's membrane (complexus basalis) shows the typical pentalaminate structure noted in most vertebrates but with only a poorly defined central elastic layer. The endothelium of the choriocapillaris is very thin facing the RPE but is only moderately fenestrated. The choriocapillaris in this species is unusual however in that many of the fenestrae show a double-layered diaphragm.

  15. Active region fine structure observed at 0.08 arcsec resolution

    CERN Document Server

    Schlichenmaier, R; Hoch, S; Soltau, D; Berkefeld, T; Schmidt, D; Schmidt, W; Denker, C; Balthasar, H; Hofmann, A; Strassmeier, K G; Staude, J; Feller, A; Lagg, A; Solanki, S K; Collados, M; Sigwarth, M; Volkmer, R; Waldmann, T; Kneer, F; Nicklas, H; Sobotka, M

    2016-01-01

    The various mechanisms of magneto-convective energy transport determines the structure of sunspots and active regions. We characterise the appearance of light bridges and other fine structure details and elaborate on their magneto-convective nature. We present speckle-reconstructed images taken with the broad band imager at the 1.5 m GREGOR telescope in the 486nm and 589nm bands. We estimate the spatial resolution from the noise characteristics of the image bursts and obtain 0.08" at 589nm. We describe structure details in individual best images as well as the temporal evolution of selected features. We find branched dark lanes extending along thin (~1") light bridges in sunspots at various heliocentric angles. In thick (~2") light bridges the branches are disconnected from the central lane and have a `Y' shape with a bright grain toward the umbra. The images reveal that light bridges exist on varying intensity levels and that their small-scale features evolve on time scales of minutes. Faint light bridges sh...

  16. Constraining the Variation in Fine-Structure Constant Using SDSS DR8 QSO Spectra

    CERN Document Server

    Rahmani, H; Srianand, R

    2013-01-01

    We report a robust constrain on the possible variation of fine-structure constant, alpha = e^2/(hbar*c), obtained using O III 4959,5007, nebular emission lines from QSOs. We find Delta-alpha/alpha=-(2.1 +/- 1.6) x 10^(-5) based on a well selected sample of 2347 QSOs from Sloan Digital Sky Survey Data Release 8 with 0.02 < z < 0.74. Our result is consistent with a non-varying alpha at a level of 2 x 10^(-5) over approximately 7 Gyr. This is the largest sample of extragalactic objects yet used to constrain the variation of alpha. While this constraint is not as stringent as those determined using many-multiplet method it is free from various systematic effects. A factor of ~ 4 improvement in Delta-alpha/alpha achieved here compared to the previous study (Bahcall et al. 2004) is just consistent with what is expected based on a factor of 14 times bigger sample used here. This suggests that errors are mainly dominated by the statistical uncertainty. We also find the ratio of transition probabilities correspo...

  17. Upper Chromospheric Magnetic Field of a Sunspot Penumbra: Observations of Fine Structure

    CERN Document Server

    Joshi, J; Solanki, S K; Feller, A; Collados, M; Suárez, D Orozco; Schlichenmaier, R; Franz, M; Balthasar, H; Denker, C; Berkefeld, T; Hofmann, A; Kiess, C; Nicklas, H; Yabar, A Pastor; Rezaei, R; Schmidt, D; Schmidt, W; Sobotka, M; Soltau, D; Staude, J; Strassmeier, K G; Volkmer, R; von der Lühe, O; Waldmann, T

    2016-01-01

    The fine-structure of magnetic field of a sunspot penumbra in the upper chromosphere is to be explored and compared to that in the photosphere. High spatial resolution spectropolarimetric observations were recorded with the 1.5-meter GREGOR telescope using the GREGOR Infrared Spectrograph (GRIS). The observed spectral domain includes the upper chromospheric He I triplet at 1083.0 nm and the photospheric Si I 1082.7 nm and Ca I 1083.3 nm spectral lines. The upper chromospheric magnetic field is obtained by inverting the He I triplet assuming a Milne-Eddington type model atmosphere. A height dependent inversion was applied to the Si I 1082.7 nm and Ca I 1083.3 nm lines to obtain the photospheric magnetic field. We find that the inclination of the magnetic field shows variations in the azimuthal direction both in the photosphere, but also in the upper chromosphere. The chromospheric variations remarkably well coincide with the variations in the inclination of the photospheric field and resemble the well-known sp...

  18. Fine Structure ENA Sources Beyond the Termination Shock: Observational Constraints and Detection Limits

    Science.gov (United States)

    Demajistre, R.; Janzen, P. H.; Allegrini, F.; Dayeh, M. A.; McComas, D. J.; Schwadron, N.

    2015-12-01

    High spatial resolution maps from the IBEX mission (McComas et al, Science, 2009) suggest the presence of "fine structure" in the signal from beyond the termination shock. That is, areas of enhanced ENA emission that span less than a degree in the IBEX sky map. If confirmed, this would suggest very concentrated areas of emission from sources with scales of a few AU embedded in the outer heliosphere (or proportionally larger if they are located beyond the heliopause). This, in turn, would require the presence of unanticipated structures (plasma or neutral) beyond the termination shock for which the physics is poorly defined. It is therefore crucial to confirm the presence of these structures through careful analysis, or to establish the detection limits if the data taken to date is not sufficient for such a confirmation. In this work, we use 5 years worth of IBEX data to examine the statistical significance of these enhancements. We examine correlations in time, ENA energy and coincidence type for evidence of these small-scale spatial structures. Then, using the known spatial response of the IBEX instrument, establish the conditions under which such structure, if present, would be detectable. This detection threshold analysis is fully applicable future measurements, such as those planned for IMAP.

  19. Fine structure of the landers fault zone: segmentation and the rupture process.

    Science.gov (United States)

    Li, Y G; Aki, K; Vidale, J E; Lee, W H; Marone, C J

    1994-07-15

    Observations and modeling of 3- to 6-hertz seismic shear waves trapped within the fault zone of the 1992 Landers earthquake series allow the fine structure and continuity of the zone to be evaluated. The fault, to a depth of at least 12 kilometers, is marked by a zone 100 to 200 meters wide where shear velocity is reduced by 30 to 50 percent. This zone forms a seismic waveguide that extends along the southern 30 kilometers of the Landers rupture surface and ends at the fault bend about 18 kilometers north of the main shock epicenter. Another fault plane waveguide, disconnected from the first, exists along the northern rupture surface. These observations, in conjunction with surface slip, detailed seismicity patterns, and the progression of rupture along the fault, suggest that several simple rupture planes were involved in the Landers earthquake and that the inferred rupture front hesitated or slowed at the location where the rupture jumped from one to the next plane. Reduction in rupture velocity can tentatively be attributed to fault plane complexity, and variations in moment release can be attributed to variations in available energy.

  20. Emission wavelength tuning of fluorescence by fine structural control of optical metamaterials with Fano resonance

    Science.gov (United States)

    Moritake, Y.; Kanamori, Y.; Hane, K.

    2016-09-01

    We demonstrated fine emission wavelength tuning of quantum dot (QD) fluorescence by fine structural control of optical metamaterials with Fano resonance. An asymmetric-double-bar (ADB), which was composed of only two bars with slightly different bar lengths, was used to obtain Fano resonance in the optical region. By changing the short bar length of ADB structures with high dimensional accuracy in the order of 10 nm, resonant wavelengths of Fano resonance were controlled from 1296 to 1416 nm. Fluorescence of QDs embedded in a polymer layer on ADB metamaterials were modified due to coupling to Fano resonance and fine tuning from 1350 to 1376 nm was observed. Wavelength tuning of modified fluorescence was reproduced by analysis using absorption peaks of Fano resonance. Tuning range of modified fluorescence became narrow, which was interpreted by a simple Gaussian model and resulted from comparable FWHM in QD fluorescence and Fano resonant peaks. The results will help the design and fabrication of metamaterial devices with fluorophores such as light sources and biomarkers.

  1. Emission wavelength tuning of fluorescence by fine structural control of optical metamaterials with Fano resonance.

    Science.gov (United States)

    Moritake, Y; Kanamori, Y; Hane, K

    2016-09-13

    We demonstrated fine emission wavelength tuning of quantum dot (QD) fluorescence by fine structural control of optical metamaterials with Fano resonance. An asymmetric-double-bar (ADB), which was composed of only two bars with slightly different bar lengths, was used to obtain Fano resonance in the optical region. By changing the short bar length of ADB structures with high dimensional accuracy in the order of 10 nm, resonant wavelengths of Fano resonance were controlled from 1296 to 1416 nm. Fluorescence of QDs embedded in a polymer layer on ADB metamaterials were modified due to coupling to Fano resonance and fine tuning from 1350 to 1376 nm was observed. Wavelength tuning of modified fluorescence was reproduced by analysis using absorption peaks of Fano resonance. Tuning range of modified fluorescence became narrow, which was interpreted by a simple Gaussian model and resulted from comparable FWHM in QD fluorescence and Fano resonant peaks. The results will help the design and fabrication of metamaterial devices with fluorophores such as light sources and biomarkers.

  2. Properties and Modeling of Unresolved Fine Structure Loops Observed by IRIS

    CERN Document Server

    Brooks, David H; Warren, Harry P

    2016-01-01

    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 (UFS) that dominate the emission of the solar transition region. In this letter, we combine IRIS measurements of the properties of a sample of 108 UFS (intensities, lengths, widths, lifetimes) with 1-D non-equilibrium ionization simulations using the HYDRAD hydrodynamic model to examine whether the UFS are now truly spatially resolved in the sense of being individual structures rather than 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 UFS may be resolved, and the distribution of UFS widths implies that they are structured on a spatial scale of 133km on average. Spatial scales of a few hundred km appear to be typical for a range of chromospheric and coronal st...

  3. The Oklo bound on the time variation of the fine-structure constant revisited

    CERN Document Server

    Damour, Thibault Marie Alban Guillaume; Damour, Thibault; Dyson, Freeman

    1996-01-01

    It has been pointed out by Shlyakhter that data from the natural fission reactors which operated about two billion years ago at Oklo (Gabon) had the potential of providing an extremely tight bound on the variability of the fine-structure constant alpha. We revisit the derivation of such a bound by: (i) reanalyzing a large selection of published rare-earth data from Oklo, (ii) critically taking into account the very large uncertainty of the temperature at which the reactors operated, and (iii) connecting in a new way (using isotope shift measurements) the Oklo-derived constraint on a possible shift of thermal neutron-capture resonances with a bound on the time variation of alpha. Our final (95% C.L.) results are: -0.9 \\times 10^{-7} <(alpha^{Oklo} - alpha^{now})/alpha <1.2\\times 10^{-7} and -6.7 \\times 10^{-17} {yr}^{-1} < {\\dot alpha}^{averaged}/alpha <5.0\\times10^{-17} {yr}^{-1}.

  4. Accelerating universe and the time-dependent fine-structure constant

    Science.gov (United States)

    Fujii, Yasunori

    2010-11-01

    I start with assuming a gravitational scalar field as the dark-energy supposed to be responsible for the accelerating universe. Also from the point of view of unification, a scalar field implies a time-variability of certain “constants” in Nature. In this context I once derived a relation for the time-variability of the fine-structure constant α: Δα/α =ζ Ƶ(α/π) Δσ, where ζ and Ƶ are the constants of the order one, while σ on the right-hand side is the scalar field in action in the accelerating universe. I use the reduced Planckian units with c=ℏ =MP(=(8π G)-1/2)=1. I then compared the dynamics of the accelerating universe, on one hand, and Δα/α derived from the analyses of QSO absorption lines, Oklo phenomenon, also different atomic clocks in the laboratories, on the other hand. I am here going to discuss the theoretical background of the relation, based on the scalar-tensor theory invented first by Jordan in 1955.

  5. Cosmological variation of the fine structure constant from an ultralight scalar field: The effects of mass

    Science.gov (United States)

    Gardner, Carl L.

    2003-08-01

    Cosmological variation of the fine structure constant α due to the evolution of a spatially homogeneous ultralight scalar field (m˜H0) during the matter and Λ dominated eras is analyzed. Agreement of Δα/α with the value suggested by recent observations of quasar absorption lines is obtained by adjusting a single parameter, the coupling of the scalar field to matter. Asymptotically α(t) in this model goes to a constant value α¯≈α0 in the early radiation and the late Λ dominated eras. The coupling of the scalar field to (nonrelativistic) matter drives α slightly away from α¯ in the epochs when the density of matter is important. Simultaneous agreement with the more restrictive bounds on the variation |Δα/α| from the Oklo natural fission reactor and from meteorite samples can be achieved if the mass of the scalar field is on the order of 0.5 0.6 HΛ, where HΛ=Ω1/2ΛH0. Depending on the scalar field mass, α may be slightly smaller or larger than α0 at the times of big bang nucleosynthesis, the emission of the cosmic microwave background, the formation of early solar system meteorites, and the Oklo reactor. The effects on the evolution of α due to nonzero mass for the scalar field are emphasized. An order of magnitude improvement in the laboratory technique could lead to a detection of (α˙/α)0.

  6. Time variation of the fine structure constant α from realistic models of Oklo reactors.

    Science.gov (United States)

    Gould, C. R.; Sharapov, E. I.; Lamoreaux, S. K.

    2006-11-01

    The topic of whether the fundamental constants of nature vary with time has been a subject of great interest since Dirac originally proposed the possibility that GN˜1/tuniverse. Recent observations of absorption spectra lines from distant quasars appeared to indicate a possible increase in the fine structure constant α over ten billion years. Contrarily, analyses of the time evolution of α from Oklo natural nuclear reactor data have yielded inconsistent results, some indicating a decrease over two billion years while others indicated no change. We have used known Oklo reactor epithermal spectral indices as criteria for selecting realistic reactor models. Reactors RZ2 and RZ10 were modeled with MCNP and the resulting neutron spectra were used to calculate the change in the ^149Sm capture cross section as a function of a possible shift in the energy of the 97.3-meV resonance. Our study resolves the contradictory situation with previous Oklo α-results. Our suggested 2 σ bound on a possible time variation of α over two billion years is stringent: -0.11 <=δαα <=0.24, in units of 10-7, but model dependent in that it assumes only α has varied over time.

  7. Bound on the variation in the fine structure constant implied by Oklo data

    CERN Document Server

    Hamdan, Leila

    2015-01-01

    Dynamical models of dark energy can imply that the fine structure constant $\\alpha$ varies over cosmological time scales. Data on shifts in resonance energies $E_r$ from the Oklo natural fission reactor have been used to place restrictive bounds on the change in $\\alpha$ over the last 1.8 billion years. We review the uncertainties in these analyses, focussing on corrections to the standard estimate of $k_\\alpha\\!=\\!\\alpha\\,dE_r/d\\alpha$ due to Damour and Dyson. Guided, in part, by the best practice for assessing systematic errors in theoretical estimates spelt out by Dobaczewski et al. [in J. Phys. G: Nucl. Part. Phys. 41, 074001 (2014)], we compute these corrections in a variety of models tuned to reproduce existing nuclear data. Although the net correction is uncertain to within a factor of 2 or 3, it constitutes at most no more than 25% of the Damour-Dyson estimate of $k_\\alpha$. Making similar allowances for the uncertainties in the modeling of the operation of the Oklo reactors, we conclude that the rela...

  8. Fine structure of the copulatory apparatus of the tapeworm Tetrabothrius erostris (Cestoda: Tetrabothriidea).

    Science.gov (United States)

    Korneva, Janetta V; Jones, Malcolm K; Kuklin, Vadim V

    2015-05-01

    The organization and fine structure of the complex copulatory apparatus of Tetrabothrius erostris (Tetrabothriidea) is investigated by light and transmission electron microscopy. A diversity of microstructures was found on the surface of genital ducts. The apical surfaces of male gonadoducts possess tubular and blade-like microtriches that have specific structure in each section of the duct. The apical part of the tubular microtriches contains numerous constrictions in the proximal section of the sperm duct; blade-like microtriches of cirrus possess longitudinal striation in the apical part, and their basal part is reinforced with electron-dense strands. Two types of microtriches occur on the surface of cirrus, and their presence may be considered as systematic features. Prostate glands containing granules of medium electron density (up to 130 nm diameter) are localized in the cirrus sac. The genital atrium contains numerous non-ciliated receptors. Paramyosin-like fibers (up to 200 nm) were found in the muscle fibers surrounding the male atrium canal. Microtriches on the surface of the distal region of the male atrial canal are covered by a glycocalyx. Electron-dense, membrane-like structures (up to 40 nm) lie under the apical membrane of the genital atrium and vagina. These structures do not form a continuous layer; its edges turn down and sink into the apical invaginations of epithelium. Hypotheses on the possible ways of copulation in T. erostris based on the observed ultrastructure are discussed.

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

    Science.gov (United States)

    Sęk, 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 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. PMID:27604778

  10. Extended x-ray absorption fine structure investigation of annealed carbon expanded austenite

    DEFF Research Database (Denmark)

    Oddershede, Jette; Christiansen, Thomas L.; Somers, Marcel A. J.;

    2012-01-01

    Carbon expanded austenite synthesized through carburizing of austenitic stainless steel powder at 380°C was annealed at 470°C and investigated with extended X-ray absorption fine structure (EXAFS) and synchrotron powder diffraction (SPD). SPD showed that the samples consisted of carbon expanded...... austenite and Hägg carbide, Ξ-M5C2. EXAFS showed that the Cr atoms were mainly present in environments similar to the carbides Hägg Ξ-M5C2 and M23C6. The environments of the Fe and Ni atoms were concluded to be largely metallic austenite. Light optical micrograph of stainless steel AISI 316 gas......-carburized in a temperature regime around 470°C. The surface zone is converted into carbon expanded austenite; the high interstitial content of carbon dissolved in the surface results in highly favorable materials properties. In the present article the local atomic environment of (annealed) carbon expanded austenite...

  11. Universal Growth Scheme for Quantum Dots with Low Fine-Structure Splitting at Various Emission Wavelengths

    Science.gov (United States)

    Skiba-Szymanska, Joanna; Stevenson, R. Mark; Varnava, Christiana; Felle, Martin; Huwer, Jan; Müller, Tina; Bennett, Anthony J.; Lee, James P.; Farrer, Ian; Krysa, Andrey B.; Spencer, Peter; Goff, Lucy E.; Ritchie, David A.; Heffernan, Jon; Shields, Andrew J.

    2017-07-01

    Efficient sources of individual pairs of entangled photons are required for quantum networks to operate using fiber-optic infrastructure. Entangled light can be generated by quantum dots (QDs) with naturally small fine-structure splitting (FSS) between exciton eigenstates. Moreover, QDs can be engineered to emit at standard telecom wavelengths. To achieve sufficient signal intensity for applications, QDs have been incorporated into one-dimensional optical microcavities. However, combining these properties in a single device has so far proved elusive. Here, we introduce a growth strategy to realize QDs with small FSS in the conventional telecom band, and within an optical cavity. Our approach employs ``droplet-epitaxy'' of InAs quantum dots on (001) substrates. We show the scheme improves the symmetry of the dots by 72%. Furthermore, our technique is universal, and produces low FSS QDs by molecular beam epitaxy on GaAs emitting at ˜900 nm , and metal-organic vapor-phase epitaxy on InP emitting at ˜1550 nm , with mean FSS 4 × smaller than for Stranski-Krastanow QDs.

  12. Growth scheme for quantum dots with low fine structure splitting at telecom wavelengths (Conference Presentation)

    Science.gov (United States)

    Muller, Tina; Skiba-Szymanska, Joanna; Stevenson, R. Mark; Varnava, Christiana; Felle, Martin; Huwer, Jan; Farrer, Ian; Krysa, Andrey B.; Spencer, Peter; Ritchie, David A.; Heffernan, Jon; Shields, Andrew J.

    2017-02-01

    Quantum dots based on InAs/InP hold the promise to deliver entangled photons with wavelength suitable for the standard telecom window around 1550 nm, which makes them predestined to be used in future quantum networks applications based on existing fiber optics infrastructure. A prerequisite for the generation of such entangled photons is a small fine structure splitting (FSS) in the quantum dot excitonic eigenstates, as well as the ability to integrate the dot into photonic structures to enhance and direct its emission. Using optical spectroscopy, we show that a growth strategy based on droplet epitaxy can simultaneously address both issues. Contrary to the standard Stranski-Krastanow technique, droplet epitaxy dots do not rely on material strains during growth, which results in a drastic improvement in dot symmetry. As a consequence, the average exciton FSS is reduced by more than a factor 4, which in fact makes all the difference between easily finding a dot with the required FSS and not finding one at all. Furthermore, we demonstrate that droplet epitaxy dots can be grown on the necessary surface (001) for high quality optical microcavities, which increases dot emission count rates by more than a factor of five. Together, these properties make droplet epitaxy quantum dots readily suitable for the generation of entangled photons at telecom wavelengths.

  13. Molecular characterization of brominated persistent pollutants using extended X-ray absorption fine structure (EXAFS) spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Bergknut, Magnus; Skyllberg, Ulf [Swedish University of Agricultural Sciences (SLU), Department of Forest Ecology and Management, Umeaa (Sweden); Persson, Per [Umeaa University, Department of Chemistry, Umeaa (Sweden)

    2008-02-15

    X-ray absorption fine structure (EXAFS) spectroscopy spectra were collected for three brominated persistent pollutants: 6-bromo-2,4,5-trichlorophenol (BrTriClP), pentabromophenol (PentaBrP) and 3,3',5,5'-tetrabromobisphenol A (TBBA). The substances were selected to be symmetrical (BrTriClP and TBBA) or asymmetrical (PentaBrP) with respect to the atomic Br positions and to differ in the number of bromine and other halide atoms, as well as their relative positions. The asymmetrical PentaBrP was modelled with special detail as not all bromine atoms have identical coordination environments. The studied substances displayed unique EXAFS spectra, which could be used to determine the molecular structure in fair detail. We conclude that EXAFS spectroscopy is a suitable technique for molecular characterization of the comparatively complex molecules within the class of compounds of brominated organic persistent pollutants. A detailed understanding of the EXAFS spectra of the pure compounds opens up possibilities to study the interactions with soil and sediment matrices by means of EXAFS spectroscopy. (orig.)

  14. Fine structure of Langmuir waves observed upstream of the bow shock at Venus

    Science.gov (United States)

    Hospodarsky, G. B.; Gurnett, D. A.; Kurth, W. S.; Kivelson, M. G.; Strangeway, R. J.; Bolton, S. J.

    1994-01-01

    Highly structured Langmuir waves, also known as electron plasma oscillations, have been observed in the foreshock of Venus using the plasma wave experiment on the Galileo spacecraft during the gravity assist flyby on February 10, 1990. The Galileo wideband sampling system provides digital electric field waveform measurements at sampling rates up to 201,600 samples per second, much higher than any previous instrument of this type. The main Langmuir wave emission band occurs near the local electron plasma frequency, which was approximately 43 kHz. The Langmuir waves are observed to shift above and below the plasma frequency, sometimes by as much as 20 kHz. The shifts in frequency are closely correlated with the downstream distance from the tangent field line, implying that the shifts are controlled by the electron beam velocity. Considerable fine structure is also evident, with timescales as short as 0.15 ms, corresponding to spatial scales of a few tens of Debye lengths. The frequency spectrum often consists of beat-type waveforms, with beat frequencies ranging from 0.2 to 7 kHz, and in a few cases, isolated wave packets. The peak electric field strengths are approximately 1 mV/m. These field strengths are too small for strongly nonlinear processes to be important. The beat-type waveforms are suggestive of a parametric decay process.

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

    Science.gov (United States)

    Simin, D.; Soltamov, V. A.; Poshakinskiy, A. V.; Anisimov, A. N.; Babunts, R. A.; Tolmachev, D. O.; Mokhov, E. N.; Trupke, M.; Tarasenko, S. A.; Sperlich, A.; Baranov, P. G.; Dyakonov, V.; Astakhov, G. V.

    2016-07-01

    We uncover the fine structure of a silicon vacancy in isotopically purified silicon carbide (4H-28SiC) 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 /√{Hz } within a volume of 3 ×10-7m m3 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 mm3 , the projection noise limit is below 100 fT /√{Hz } .

  16. Helical motions of fine-structure prominence threads observed by Hinode and IRIS

    CERN Document Server

    Okamoto, Takenori J; Tsuneta, Saku

    2016-01-01

    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 \\emph{Hinode} and/or \\emph{IRIS} satellites at high resolution. In the first event, we found transverse motions of brightening threads at speeds up to 55~km~s$^{-1}$ seen in the plane of the sky. Such motions appeared as sinusoidal space--time trajectories with a typical period of $\\sim$390~s, which is consistent with plane-of-sky projections of rotational motions. Phase delays at different locations suggest propagation of twists along the threads at phase speeds of 90--270~km~s$^{-1}$. At least 15 episodes of such motions occurred in two days, none associated with any 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...

  17. Variation of the fine structure constant and the electron mass at early Universe

    CERN Document Server

    Scóccola, Claudia G

    2009-01-01

    In this thesis, we focus on the study of the variation of the electron mass $m_e$, and the fine structure constant $\\alpha$, at different cosmic times. We analyze the details of the recombination physics, including helium recombination, in order to find the dependences of the physical quantities on the fundamental constants. Using up-to-date CMB data, and the final 2dFGRS power spectrum, we set limits to the possible variation of the constants at recombination. We analyze the variation of $\\alpha$ and $m_e$ independently, and the case in which both variations are allowed, fitting also a set of cosmological parameters. We find a fenomenological relationship between the variation of $\\alpha$ and the variation of $m_e$, between decoupling and present time. We analyze the Barrow-Magueijo fenomenological model, which propose a variation in the electron mass induced by changes in a space-time scalar field. We present improved solutions and we estimate the model parameters using bounds on the variation of the electr...

  18. Excitonic fine structure and binding energies of excitonic complexes in single InAs quantum dashes

    Science.gov (United States)

    Mrowiński, P.; Zieliński, M.; Świderski, M.; Misiewicz, J.; Somers, A.; Reithmaier, J. P.; Höfling, S.; Sek, G.

    2016-09-01

    The fundamental electronic and optical properties of elongated InAs nanostructures embedded in quaternary InGaAlAs barrier are investigated by means of high-resolution optical spectroscopy and many-body atomistic tight-binding theory. These wire-like shaped, self-assembled nanostructures are known as quantum dashes and are typically formed during the molecular beam epitaxial growth on InP substrates. In this paper, we study properties of excitonic complexes confined in quantum dashes emitting in a broad spectral range from below 1.2 to 1.55 μm. We find peculiar trends for the biexciton and negative trion binding energies, with pronounced trion binding in smaller size quantum dashes. These experimental findings are then compared and qualitatively explained by atomistic theory. The theoretical analysis shows a fundamental role of correlation effects for the absolute values of excitonic binding energies. Eventually, we determine the bright exciton fine structure splitting (FSS), where both the experiment and theory predict a broad distribution of the splitting varying from below 50 to almost 180 μeV. We identify several key factors determining the FSS values in such nanostructures, including quantum dash size variation and composition fluctuations.

  19. 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.

  20. The morphology and fine structure of the giant interneurons of the wood cricket Nemobius sylvestris.

    Science.gov (United States)

    Insausti, T C; Lazzari, C R; Casas, J

    2011-02-01

    The structural and ultrastructural characteristics of giant interneurons in the terminal abdominal ganglion of the cricket Nemobius sylvestris were investigated by means of cobalt and fluorescent dye backfilling and transmission electron microscopy. The projections of the 8 eight pairs of the biggest ascending interneurons (giant interneurons) are described in detail. The somata of all interneurons analyzed are located contralateral to their axons, which project to the posterior region of the terminal ganglion and arborise in the cercal glomerulus. Neuron 7-1a is an exception, because its arborisation is restricted to the anterior region of the ganglion. The fine structure of giant interneurons shows typical features of highly active cells. We observed striking indentations in the perineural layer, enabling the somata of the giant interneurons to be very close to the haemolymph. The cercal glomerulus exhibits a high diversity of synaptic contacts (i.e. axo-dendritic, axo-axonic, dendro-axonic, and dendro-dendritic), as well as areas of tight junctions. Electrical synapses seem to be present, as well as mixed synapses. The anatomical organization of the giant interneurons is finally discussed in terms of functional implications and on a comparative basis.

  1. Fine structure and functional comments of mouthparts in Platypus cylindrus (Col., Curculionidae: Platypodinae).

    Science.gov (United States)

    Belhoucine, Latifa; Bouhraoua, Rachid T; Prats, Eva; Pulade-Villar, Juli

    2013-02-01

    Oak pinhole borer, Platypus cylindrus is seen in recent years as one of the biggest enemies directly involved in the observed decline of cork oak in Mediterranean forests with all the economic implications. As an ambrosia beetle, it has developed its effective drilling mouthpart enough to make tunnels in hardwood of the tree. The fine structural aspects of the mouthpart using the field emission scanning electron microscopy are analyzed about 23 adults collected in galleries of infested cork oak trees (Quercus suber) in a littoral forest of northwest Algeria. These adults are preserved in alcohol 70%, cleaned and coated with gold. The mouthparts of this beetle consist commonly of a labrum, a pair of mandibles, a pair of maxillae and the labium but with adapted structure to excavate galleries in the hardwood. In this role is also involved the first pair of legs. The function that present the different structures related to the construction of the tunnels is discussed. Both of maxillary and labial palpi direct the food to the mouth and hold it while the mandibles chew the food. The distal ends of these palpi are flattened and have shovel-like setae. Females have larger maxillary palpi than males and this is related to the particular biology of each sex.

  2. Ribavirin restores ESR1 gene expression and tamoxifen sensitivity in ESR1 negative breast cancer cell lines

    Directory of Open Access Journals (Sweden)

    Sappok Anne

    2011-12-01

    Full Text Available Abstract Tumor growth is estrogen independent in approximately one-third of all breast cancers, which makes these patients unresponsive to hormonal treatment. This unresponsiveness to hormonal treatment may be explained through the absence of the estrogen receptor alpha (ESR1. The ESR1 gene re-expression through epigenetic modulators such as DNA methyltransferase inhibitors and/or histone deacetylase inhibitors restores tamoxifen sensitivity in ESR1 negative breast cancer cell lines and opens new treatment horizons in patients who were previously associated with a poor prognosis. In the study presented herein, we tested the ability of ribavirin, which shares some structural similarities with the DNA-methyltransferase inhibitor 5-azacytidine and which is widely known as an anti-viral agent in the treatment of hepatitis C, to restore ESR1 gene re-expression in ESR1 negative breast cancer cell lines. In our study we identified ribavirin to restore ESR1 gene re-expression alone and even more in combination with suberoylanilide hydroxamic acid (SAHA - up to 276 fold induction. Ribavirin and analogs could pave the way to novel translational research projects that aim to restore ESR1 gene re-expression and thus the susceptibility to tamoxifen-based endocrine treatment strategies.

  3. Irradiation detection of coffee mate by electron spin resonance (ESR)

    Science.gov (United States)

    Özsayin, Fulya; Polat, Mustafa

    2011-06-01

    Un-irradiated coffee mate samples do not exhibit any ESR signal. However, the samples exposed to UV and gamma radiation exhibit an ESR singlet and a large unresolved ESR signal, respectively. The dose-response curves of the samples exposed to UV and gamma radiations were found to be described well by an exponential and linear functions, respectively. Variable temperature and fading studies at room temperature showed that the radiation-induced radicals in coffee mate sample are very sensitive to temperature. The discrimination between un-irradiated and irradiated coffee mate samples can be done just comparing their ESR spectra. However, determination of the radiation dose received by the sample cannot be possible because of the fast decay of signal intensity at room temperature.

  4. Comparative Study of Erythrocyte Sedimentation Rate (ESR) Using ...

    African Journals Online (AJOL)

    MICHAEL

    Committee for Standardization in Haematology (ICSH). The tests were read ... Secondly, ESR is time dependent; therefore, the conventional time of 1 hour should be ... auto-immune diseases, systemic lupus erythematosus, rheumatoid arthritis ...

  5. ESR STUDY OF PLASMA-TREATED POLYTETRAFLUOROETHYLENE FILMS

    Institute of Scientific and Technical Information of China (English)

    ZHOU Maotang; WANG Shicai; LIU Guizhen; CHEN Jie

    1990-01-01

    The plasma treatment of polytetrafluoroethylene (PTFE) films was carried out in a capacitively coupled reactor with external electrodes. The free radicals generated in the process of treatment were detected by ESR techniques. The ESR spectra tended to indicate that the free radicals of the plasma-treated PTFE film sample were turned into peroxy radicals on exposure to air. The extrema separation (W) of the ESR spectrum of the peroxy radical increased with the lowering temperature and underwent a sudden change within the temperature range of 170 to 190K. The ESR spectrum observed at 77K was quite different from that observed at room temperature. Finally, the effects of treatment time, input power and system pressure on radical concentration of the treated samples were studied. The attenuation of the peroxy radical at room temperature was also investigated.

  6. [Fine structural study of keratinization of the filiform papillae in the tongue in humans].

    Science.gov (United States)

    Placková, A; Skach, M

    1975-01-01

    The fine structure of the keratinization of the papilla filiformis of the human tongue was described for the first time; Two biopsies of normal tongue tissue were fixed in 2,5% phosphate-buffered glutaraldehyde, postfixed in 1% osmiumtetroxyde, embedded in Durcopan und contrasted ultrathin sections were examined by electron microscopes JEM 7A and 100B. The findings show a highly configurated epithel-connective tissue border with basal lamina and irregular hemidesmosomes. The epithelial structure of the interpapillary area is identical with the fine structure of the human buccal mucosa, which was classified as non-keratinized or incompletely keratinized. Accordingly, a stratum granulosum is missing. After loss of nucleus and organelles, surface cells become flattened, parallel to the surface of the tongue and have a fine fibrillar cytoplasm. The papilla filiformis is formed by cell growth along the secondary connective tissue papillae and consequently tube-like epithelial structures appear. In the papillary area basal and stratum spinosum cells show epidermal structural features. A difference from epidermal and other oral epithelial cells becomes apparent for the first time in the stratum granulosum by the appearance of a great number of round, small, electron-dense KHG, surrounded by ribosomes. The KHG are not associated with tonofilaments. In the area of the walls of the tubes 1...3 mum large, electron-dense structures are formed by fusion of several KHG. With further differentiation these large KHG disintegrate into bulky or granular masses, filling the cell cytoplasm and thus mask the tonofilaments. The cells at the borders of the tubes show a great structural variability. After the disintegration of nucleus and organelles, the cytoplasm is formed by randomly oriented filaments of different packing or by fiber-bundles. Yet the interfibrilla embedding substance, typical of orthokeratinization is mostly lackingmin some cells of the tubeborders, masses of

  7. 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.

  8. Observations and modeling of the fine structure of loops in the transition region and corona

    Science.gov (United States)

    Brooks, David

    2017-08-01

    The physical dimensions of loops hold important clues to the coronal heating process. Theoretical arguments universally indicate that coronal heating should operate on very small spatial scales and loops should be unresolvable by current instrumentation. There are a number of observational results, however, that suggest that coronal loops are organized on spatial scales of several hundred km. For example, recent observations from IRIS have discovered a new class of low-lying dynamic loops structures, and it has been argued that they are the long-postulated unresolved fine structures (UFS) that dominate the emission of the solar transition region. Here we show that the properties of the UFS (intensities, lengths, widths, lifetimes) are consistent with 1-D non-equilibrium ionization simulations of an impulsively heated single strand, suggesting that they are resolved, and that the distribution of UFS widths implies that like coronal loops they are also structured on a spatial scale of a few hundred km. Spatial scales of a few hundred kilometers appear to be typical for a range of chromospheric and coronal structures, but it is unclear whether the true distribution of loop widths is normalized around this scale, or whether it extends to much smaller scales - perhaps by a power-law - below the resolution of current instruments. We have extended our previous modeling of the cross-field intensity profiles of coronal loops observed by EIS and AIA, to investigate what the modeled profiles would look like at Hi-C resolution, what they would look like if loops are composed only of temperatures and densities, and the intensity profiles from the power-law simulations are dominated by emission from the largest strands.

  9. A New Catalogue of Fine Structures Superimposed on Solar Microwave Bursts

    Institute of Scientific and Technical Information of China (English)

    Qi-Jun Fu; Yi-Hua Yan; Yu-Ying Liu; Min Wang; Shu-Juan Wang

    2004-01-01

    The 2.6-3.8 GHz, 4.5-7.5 GHz, 5.2-7.6 GHz and 0.7-1.5 GHz component spectrometers of Solar Broadband Radio Spectrometer (SBRS) started routine observations, respectively, in late August 1996, August 1999, August 1999, and June 2000. They just managed to catch the coming 23rd solar active maximum. Consequently, a large amount of microwave burst data with high temporal and high spectral resolution and high sensitivity were obtained. A variety of fine structures (FS)superimposed on microwave bursts have been found. Some of them are known, such as microwave type Ⅲ bursts, microwave spike emission, but these were observed with more detail; some are new. Reported for the first time here are microwave type U bursts with similar spectral morphology to those in decimetric and metric wavelengths, and with outstanding characteristics such as very short durations(tens to hundreds ms), narrow bandwidths, higher frequency drift rates and higher degrees of polarization. Type N and type M bursts were also observed. Detailed zebra pattern and fiber bursts at the high frequency were found. Drifting pulsation structure (DPS) phenomena closely associated with CME are considered to manifest the initial phase of the CME, and quasi-periodic pulsation with periods of tens ms have been recorded. Microwave "patches", unlike those reported previously, were observed with very short durations (about 300 ms), very high flux densities (up to 1000 sfu), very high polarization (about 100% RCP), extremely narrow bandwidths(about 5%), and very high spectral indexes. These cannot be interpreted with the gyrosynchrotron process. A superfine structure in the form of microwave FS (ZPS,type U), consisting of microwave millisecond spike emission (MMS), was also found.

  10. A surface extended X-ray absorption fine structure study of tellurium adsorbed onto Si(100)

    Science.gov (United States)

    Burgess, S. R.; Cowie, B. C. C.; Wilks, S. P.; Dunstan, P. R.; Dunscombe, C. J.; Williams, R. H.

    1996-09-01

    The adsorption of tellurium on Si(100) has been studied using surface extended X-ray adsorption fine structure (SEXAFS) and X-ray standing wave spectroscopy (XSW). This particular system is of interest due to its potential applicability in the surfactant aided growth of CdHgTeCdTeSi(100) based infra-red detectors. The Te/Si(100) structure was generated by depositing a thick layer (˜ 100 Å) of CdTe onto a clean Si (2 × 1) double domain surface, and annealing the sample to 350°C. This resulted is a ˜ 1 ML Te terminated surface where the (2 × 1) reconstruction was lost in favour of a (1 × 1) symmetry. X-ray absorption of the Te L 3 edge ( E = 4341 eV), with a photon energy range of 4440-4700 eV, was probed using a total yield detection scheme. The SEXAFS results indicated that the Te atoms sat in 2-fold bridge sites directly above a fourth layer Si atom. The corresponding bond length was measured to be 2.52 ± 0.05 Å. The XSW measurements of the (400) reflection gave a coherent position of 1.63 ± 0.03 Å and a coherent fraction of 0.65. This is consistent with the breaking of the SiSi dimers and thus could be an example of the phenomena of adsorbate-induced dereconstruction of the surface. These results are compared with those of Bennet et al. who examined a similar system using soft X-ray photoemission (SXPS) and the STM study of Yoshikawa et al.

  11. Rate Constants for Fine-structure Excitations in O-H Collisions with Error Bars Obtained by Machine Learning

    Science.gov (United States)

    Vieira, Daniel; Krems, Roman V.

    2017-02-01

    We present an approach using a combination of coupled channel scattering calculations with a machine-learning technique based on Gaussian Process regression to determine the sensitivity of the rate constants for non-adiabatic transitions in inelastic atomic collisions to variations of the underlying adiabatic interaction potentials. Using this approach, we improve the previous computations of the rate constants for the fine-structure transitions in collisions of O({}3{P}j) with atomic H. We compute the error bars of the rate constants corresponding to 20% variations of the ab initio potentials and show that this method can be used to determine which of the individual adiabatic potentials are more or less important for the outcome of different fine-structure changing collisions.

  12. Comparison of the coupled-channel calculation with the WKB method for α-decay fine structure

    Science.gov (United States)

    Ni, Dongdong; Ren, Zhongzhou

    2013-05-01

    The α-decay fine structures in heavy deformed even-even and odd-mass nuclei are investigated using the newly developed multichannel cluster model (MCCM) and the WKB barrier penetration formalism. The MCCM is based on the coupled-channel Schrödinger equation with outgoing wave boundary conditions. For even-even nuclei, the two methods yield comparable results concerning the branching ratios for 0+ and 2+ states but the WKB formula fails in reproducing the branching ratios for excited 4+ states. For odd-mass nuclei, it is hard to use the WKB formula to interpret the unexpected behavior BRI+1 >BRI while the MCCM succeeds. These emphasize that the coupling effects of decay channels cannot be ignored in describing the α-decay fine structure.

  13. Avoiding unrealistic priors: the case of dark energy constraints from the time variation of the fine-structure constant

    CERN Document Server

    Avelino, P P

    2016-01-01

    We critically assess recent claims suggesting that upper limits on the time variation of the fine-structure constant tightly constrain the coupling of a dark energy scalar field to the electromagnetic sector, and, indirectly, the violation of the weak equivalence principle. We show that such constraints depend crucially on the assumed priors, even if the dark energy was described by a dynamical scalar field with a constant equation of state parameter $w$ linearly coupled to the electromagnetic sector through a dimensionless coupling $\\zeta$. We find that, although local atomic clock tests, as well as other terrestrial, astrophysical and cosmological data, put stringent bounds on $|\\zeta| {\\sqrt {|w+1|}}$, the time variation of the fine-structure constant cannot be used to set or to improve upper limits on $|\\zeta|$ or $|w+1|$ without specifying priors, consistent but not favoured by current data, which strongly disfavour low values of $|w+1|$ or $|\\zeta|$, respectively. We briefly discuss how this might chang...

  14. A unified description for dipoles of the fine-structure constant and SnIa Hubble diagram in Finslerian universe

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xin [Chongqing University, Department of Physics, Chongqing (China); Chinese Academy of Sciences, State Key Laboratory Theoretical Physics, Institute of Theoretical Physics, Beijing (China); Lin, Hai-Nan [Chinese Academy of Sciences, Institute of High Energy Physics, Beijing (China); Wang, Sai [Chinese Academy of Sciences, State Key Laboratory Theoretical Physics, Institute of Theoretical Physics, Beijing (China); Chang, Zhe [Chinese Academy of Sciences, Institute of High Energy Physics, Beijing (China); Chinese Academy of Sciences, State Key Laboratory Theoretical Physics, Institute of Theoretical Physics, Beijing (China)

    2015-05-15

    We propose a Finsler spacetime scenario of the anisotropic universe. The Finslerian universe requires both the fine-structure constant and the accelerating cosmic expansion to have a dipole structure and the directions of these two dipoles to be the same. Our numerical results show that the dipole direction of the SnIa Hubble diagram locates at (l,b) = (314.6 {sup circle} ± 20.3 {sup circle},-11.5 {sup circle} ± 12.1 {sup circle}) with magnitude B = (-3.60 ± 1.66) x 10{sup -2}. The dipole direction of the fine-structure constant locates at (l,b) = (333.2 {sup circle} ± 8.8 {sup circle},-12.7 {sup circle} ± 6.3 {sup circle}) with magnitude B = (0.97 ± 0.21) x 10{sup -5}. The angular separation between the two dipole directions is about 18.2 {sup circle}. (orig.)

  15. A unified description for dipoles of the fine-structure constant and SnIa Hubble diagram in Finslerian universe

    CERN Document Server

    Li, Xin; Wang, Sai; Chang, Zhe

    2015-01-01

    We propose a Finsler spacetime scenario of the anisotropic universe. The Finslerian universe requires both the fine-structure constant and accelerating cosmic expansion have dipole structure, and the directions of these two dipoles are the same. Our numerical results show that the dipole direction of SnIa Hubble diagram locates at $(l,b)=(314.6^\\circ\\pm20.3^\\circ,-11.5^\\circ\\pm12.1^\\circ)$ with magnitude $B=(-3.60\\pm1.66)\\times10^{-2}$. And the dipole direction of the fine-structure constant locates at $(l,b)=(333.2^\\circ\\pm8.8^\\circ,-12.7^\\circ\\pm6.3^\\circ)$ with magnitude $B=(0.97\\pm0.21)\\times10^{-5}$. The angular separation between the two dipole directions is about $18.2^\\circ$.

  16. Flare processes evolution and polarization changes of fine structures of solar radio emission in the April 11, 2013 event

    CERN Document Server

    Chernov, Gennady; Tan, Baolin; Yan, Yihua; Tan, Chengming; Fu, Qijun; Karlicky, Marian; Fomichev, Valery

    2015-01-01

    The measurement of positions and sizes of radio sources in the observations of solar radio spectral fine structures in an M6.5 flare on April 11, 2013 were observed simultaneously by several radio instruments at four different observatories: Chinese Solar Broadband Radio Spectrometers at Huairou (SBRS/Huairou), Ondrejov Radio spectrograph in the Czech Republic (ORSC/Ondrejov), Badary Broadband Microwave spectropolarimeter (BMS/Irkutsk), and spectrograph/IZMIRAN (Moscow, Troitsk). The fine structures include microwave zebra patterns (ZP), fast pulsations, and fibers. They were observed during the flare brightening located at the tops of a loop arcade. The dynamics of the polarization was associated with the motion of the flare exciter, which was observed in EUV images at 171A and 131A (SDO/AIA). Combining magnetograms observed by the SDO Helioseismic and Magnetic Imager (HMI) with the homologous assumption of EUV flare brightening and ZP bursts, we deduced that the observed ZPs correspond to the ordinary radio...

  17. Modeling of 1—D Lossy Fine Structures Using Transformed—Space Non—Uniform PSTD

    Institute of Scientific and Technical Information of China (English)

    LIQingliang; CHENYinchao

    2003-01-01

    Although the advantages of the pseu-dospectral time domain (PSTD) has been validated in di-verse applications of electromagnetic problems based on a uniform grid, it faces a difficulty when an electromagnetic structure involves highly conductivity due to the Gibbs phenomena. In addition, its efficiency will be greatly re-duced in solving a problem with fine structure, since a denser grid is needed. In this paper, we apply a newly de-veloped transformed-space non-uniform grid PSTD tech-nique (TSNU-PSTD) to handle an application with very fine structure. By using a quadratic interpolation, we transform an non-unlform grid into a uniform one, and then we simply implement the conventional PSTD by only utilizing the standard fast Fourier transform (FFT) to de-rive PSTD update equations.

  18. An unexpected copper catalyzed ‘reduction’ of an arylazide to amine through the formation of a nitrene intermediate

    Science.gov (United States)

    Draganov, Alexander B.; Chen, Weixuan; Dai, Chaofeng; Nelson, William H.; Liu, Aimin; Wang, Binghe

    2013-01-01

    Azido nitrobenzoxadiazole (NBD) was observed to undergo a ‘reduction’ reaction in the absence of an obvious reducing agent, leading to amine formation. In the presence of an excess amount of DMSO, a sulfoxide conjugate was also formed. The ratio of these two products was both temperature- and solvent-dependent, with the addition of water significantly enhancing the ratio of the ‘reduction’ product. Two intermediates of the azido-NBD reaction in DMSO were trapped and characterized by low-temperature EPR spectroscopy. One was an organic free radical (S=1/2) and another was a triplet nitrene (S=1) species. A mechanism was proposed based on the characterized free radical and triplet intermediates. PMID:23997313

  19. Symmetry Breaking and Fine Structure Splitting in Zincblende Quantum Dots: Atomistic Simulations of Long-Range Strain and Piezoelectric Field

    Science.gov (United States)

    Ahmed, Shaikh; Usman, Muhammad; Heitzinger, Clemens; Rahman, Rajib; Schliwa, Andrei; Klimeck, Gerhard

    2007-04-01

    Electrons and holes captured in self-assembled quantum dots (QDs) are subject to symmetry breaking that cannot be represented in with continuum material representations. Atomistic calculations reveal symmetry lowering due to effects of strain and piezo-electric fields. These effects are fundamentally based on the crystal topology in the quantum dots. This work studies these two competing effects and demonstrates the fine structure splitting that has been demonstrated experimentally can be attributed to the underlying atomistic structure of the quantum dots.

  20. 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.

  1. Fine structure of the epidermal Leydig cells in the axolotl Ambystoma mexicanum in relation to their function.

    Science.gov (United States)

    Jarial, M S

    1989-12-01

    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.

  2. Persistent free radical ESR signals in marine bivalve tissues

    Energy Technology Data Exchange (ETDEWEB)

    Mehlorn, R.J. [California Univ., Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering; Mendez, A.T. [Fundacion Educativa Ana G. Mendez, Rio Piedras (Puerto Rico); Higashi, R. [California Univ., Bodega Bay, CA (United States). Bodega Marine Lab.; Fan, T. [California Univ., Davis, CA (United States)

    1992-08-01

    Freeze-dried homogenates of the oyster Crassostrea rhizophorae collected from waters in Puerto Rico near urban and industrial sites as well as at relatively pristine locations yielded electron spin resonance (ESR) spectra characteristic of free radicals as well as spectral components of transition metal ions, dominated by manganese. The magnitudes of these ESR signals and the concentrations of trace elements (determined by X-ray fluorescence) varied considerably among oyster samples, masking any potential correlation with polluted waters. Laboratory studies were initiated to identify the factors controlling the magnitudes of the tissue free radical ESR signals. Another mollusc, Mytilus californianus collected at the Bodega Marine laboratory in northern California, was fractionated into goneds and remaining tissue. Freeze-dried homogenates of both fractions exhibited ESR signals that increased gradually with time. ESR signals were observed in freeze-dried perchloric acid (PCA) precipitates of the homogenates, delipidated PCA precipitates, and in chloroform extracts of these precipitates. Acid hydrolysis to degrade proteins to amino acids produced a residue, which yielded much larger ESR free radical signals after freeze-drying. Freshly thawed homogenates of Crassostrea rhizophorae also exhibited ESR signals. A laboratory model of copper stress in Crassostrea rhizophorae was developed to study the effect of this transition metal on dssue free radicals. Preliminary results suggested that sublethal copper exposure had little effect on tissue fire radicals, except possibly for a signal enhancement in an oyster fraction that was enriched in kidney granules. Since kidney granules are known to accumulate heavy metals in mussels and probably other marine bivalves, this signal enhancement may prove to be an indicator of free radical processes associated with heavy metal deposition in molluscs.

  3. ESR - a retinal protein with unusual properties from Exiguobacterium sibiricum.

    Science.gov (United States)

    Petrovskaya, L E; Balashov, S P; Lukashev, E P; Imasheva, E S; Gushchin, I Yu; Dioumaev, A K; Rubin, A B; Dolgikh, D A; Gordeliy, V I; Lanyi, J K; Kirpichnikov, M P

    2015-06-01

    This review covers the properties of a retinal protein (ESR) from the psychrotrophic bacterium Exiguobacterium sibiricum that functions as a light-driven proton pump. The presence of a lysine residue at the position corresponding to intramolecular proton donor for the Schiff base represents a unique structural feature of ESR. We have shown that Lys96 successfully facilitates delivery of protons from the cytoplasmic surface to the Schiff base, thus acting as a proton donor in ESR. Since proton uptake during the photocycle precedes Schiff base reprotonation, we conclude that this residue is initially in the uncharged state and acquires a proton for a short time after Schiff base deprotonation and M intermediate formation. Involvement of Lys as a proton donor distinguishes ESR from the related retinal proteins - bacteriorhodopsin (BR), proteorhodopsin (PR), and xanthorhodopsin (XR), in which the donor function is performed by residues with a carboxyl side chain. Like other eubacterial proton pumps (PR and XR), ESR contains a histidine residue interacting with the proton acceptor Asp85. In contrast to PR, this interaction leads to shift of the acceptor's pKa to more acidic pH, thus providing its ability to function over a wide pH range. The presence of a strong H-bond between Asp85 and His57, the structure of the proton-conducting pathways from cytoplasmic surface to the Schiff base and to extracellular surface, and other properties of ESR were demonstrated by solving its three-dimensional structure, which revealed several differences from known structures of BR and XR. The structure of ESR, its photocycle, and proton transfer reactions are discussed in comparison with homologous retinal proteins.

  4. Application of gadolinium ion-doped glaserite to ESR imaging

    Energy Technology Data Exchange (ETDEWEB)

    Ohta, Masatoshi [Niigata Univ. (Japan). Faculty of Engineering; Furukawa, Hiroaki

    1997-02-01

    The imperfections and defects are well known to form in the alkaline metal sulfates after X-ray irradiation. The Gd ion-doped K{sub 3}Na(SO{sub 4}){sub 2} had high susceptibility to X-ray irradiation. The ESR signal of SO{sub 3}{sup -} radical was isotropic and thermally stable in Gd ion-doped K{sub 3}Na(SO{sub 4}){sub 2} irradiated by X-ray. The result described is the application of the Gd ion-doped K{sub 3}Na(SO{sub 4}){sub 2} to the ESR imaging method which can monitor both absorbed dose and irradiation direction. Zupancic-typed coils were used to produce the magnetic field gradient with a direction for ESR imaging. The parallel wires of Zupancic-typed coils were connected to each other and to the current sources, forming four independent current loops to change the direction of magnetic field. The ESR spectra were measured using an X-band ESR spectrometer with a 100 kHz magnetic field modulator and a phase-sensitive detector. The current values of the four loops were controlled by using four regulated DC power supplies controlled by 12 bit D/A converters. A two-dimensional image was reconstructed using a filtered back projection method from the projection data of 180 directions (1-degree steps), which were obtained by using a field gradient of 1.05 mTmm{sup -1}. The obtained results suggest that the Gd-doped K{sub 3}Na(SO{sub 4}){sub 2} sample can be utilized as the ESR-CT image and the ESR dosimeter in the range from 20{mu}Gy to 100 Gy. (author)

  5. Association of polymorphisms in genes encoding hormone receptors ESR1, ESR2 and LHCGR with the risk and clinical features of testicular germ cell cancer

    DEFF Research Database (Denmark)

    Brokken, Leon J S; Lundberg-Giwercman, Yvonne; Rajpert-De Meyts, Ewa

    2012-01-01

    (rs7371084; OR=2.37, 95% CI: 1.26-4.49) associated with risk of seminoma and metastasis, respectively. SNPs in ESR1 (rs9397080) and LHCGR (rs7371084) were predictors of higher LH levels and higher androgen sensitivity index in healthy subjects. The results suggest that polymorphisms in ESR1, ESR2...

  6. FAR-INFRARED FINE-STRUCTURE LINE DIAGNOSTICS OF ULTRALUMINOUS INFRARED GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Farrah, D.; Petty, S. M.; Harris, K. [Department of Physics, Virginia Tech, Blacksburg, VA 24061 (United States); Lebouteiller, V.; Spoon, H. W. W. [Cornell University, CRSR, Space Sciences Building, Ithaca, NY 14853 (United States); Bernard-Salas, J.; Pearson, C. [Department of Physics and Astronomy, The Open University, Milton Keynes MK7 6AA (United Kingdom); Rigopoulou, D. [RAL Space, Rutherford Appleton Laboratory, Harwell, Oxford OX11 0QX (United Kingdom); Smith, H. A. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); González-Alfonso, E. [Universidad de Alcalá, Departamento de Física y Matemáticas, Campus Universitario, E-28871 Alcalá de Henares, Madrid (Spain); Clements, D. L. [Physics Department, Imperial College London, Prince Consort Road, London SW7 2AZ (United Kingdom); Efstathiou, A. [School of Sciences, European University Cyprus, Diogenes Street, Engomi, 1516 Nicosia (Cyprus); Cormier, D. [Institut für theoretische Astrophysik, Zentrum für Astronomie der Universität Heidelberg, Albert-Ueberle Str. 2, D-69120 Heidelberg (Germany); Afonso, J. [Centro de Astronomia e Astrofísica da Universidade de Lisboa, Observatório Astronómico de Lisboa, Tapada da Ajuda, 1349-018 Lisbon (Portugal); Hurley, P. [Department of Physics and Astronomy, University of Sussex, Falmer, Brighton BN1 9QH (United Kingdom); Borys, C. [Infrared Processing and Analysis Center, MS220-6, California Institute of Technology, Pasadena, CA 91125 (United States); Verma, A. [Oxford Astrophysics, Denys Wilkinson Building, University of Oxford, Keble Rd, Oxford OX1 3RH (United Kingdom); Cooray, A.; Salvatelli, V. [Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States)

    2013-10-10

    We present Herschel observations of 6 fine-structure lines in 25 ultraluminous infrared galaxies at z < 0.27. The lines, [O III]52 μm, [N III]57 μm, [O I]63 μm, [N II]122 μm, [O I]145 μm, and [C II]158 μm, are mostly single Gaussians with widths <600 km s{sup –1} and luminosities of 10{sup 7}-10{sup 9} L{sub ☉}. There are deficits in the [O I]63/L{sub IR}, [N II]/L{sub IR}, [O I]145/L{sub IR}, and [C II]/L{sub IR} ratios compared to lower luminosity systems. The majority of the line deficits are consistent with dustier H II regions, but part of the [C II] deficit may arise from an additional mechanism, plausibly charged dust grains. This is consistent with some of the [C II] originating from photodissociation regions or the interstellar medium (ISM). We derive relations between far-IR line luminosities and both the IR luminosity and star formation rate. We find that [N II] and both [O I] lines are good tracers of the IR luminosity and star formation rate. In contrast, [C II] is a poor tracer of the IR luminosity and star formation rate, and does not improve as a tracer of either quantity if the [C II] deficit is accounted for. The continuum luminosity densities also correlate with the IR luminosity and star formation rate. We derive ranges for the gas density and ultraviolet radiation intensity of 10{sup 1} < n < 10{sup 2.5} and 10{sup 2.2} < G{sub 0} < 10{sup 3.6}, respectively. These ranges depend on optical type, the importance of star formation, and merger stage. We do not find relationships between far-IR line properties and several other parameters: active galactic nucleus (AGN) activity, merger stage, mid-IR excitation, and SMBH mass. We conclude that these far-IR lines arise from gas heated by starlight, and that they are not strongly influenced by AGN activity.

  7. Recovery and fine structure variability of RGII sub-domains in wine (Vitis vinifera Merlot).

    Science.gov (United States)

    Buffetto, F; Ropartz, D; Zhang, X J; Gilbert, H J; Guillon, F; Ralet, M-C

    2014-10-01

    Rhamnogalacturonan II (RGII) is a structurally complex pectic sub-domain composed of more than 12 different sugars and 20 different linkages distributed in five side chains along a homogalacturonan backbone. Although RGII has long been described as highly conserved over plant evolution, recent studies have revealed variations in the structure of the polysaccharide. This study examines the fine structure variability of RGII in wine, focusing on the side chains A and B obtained after sequential mild acid hydrolysis. Specifically, this study aims to differentiate intrinsic structural variations in these RGII side chains from structural variations due to acid hydrolysis. RGII from wine (Vitis vinifera Merlot) was sequentially hydrolysed with trifluoroacetic acid (TFA) and the hydrolysis products were separated by anion-exchange chromatography (AEC). AEC fractions or total hydrolysates were analysed by MALDI-TOF mass spectrometry. The optimal conditions to recover non-degraded side chain B, side chain A and RGII backbone were 0·1 m TFA at 40 °C for 16 h, 0·48 m TFA at 40 °C for 16 h (or 0·1 m TFA at 60 °C for 8 h) and 0·1 m TFA at 60 °C for 16 h, respectively. Side chain B was particularly prone to acid degradation. Side chain A and the RGII GalA backbone were partly degraded by 0·1 m TFA at 80 °C for 1-4 h. AEC allowed separation of side chain B, methyl-esterified side chain A and non-methyl-esterified side chain A. The structure of side chain A and the GalA backbone were highly variable. Several modifications to the RGII structure of wine were identified. The observed dearabinosylation and deacetylation were primarily the consequence of acidic treatment, while variation in methyl-esterification, methyl-ether linkages and oxidation reflect natural diversity. The physiological significance of this variability, however, remains to be determined. © The Author 2014. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights

  8. Structural studies of molecular and metallic overlayers using angle- resolved photoemission extended fine structure

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Z.

    1992-10-01

    Angle-resolved photoemission extended fine structure (ARPEFS) was used to study molecular and metallic overlayers on metal surfaces through analysis of p2mg(2[times]1)CO/Ni(110) and the p(2[times]2)K/Ni(111) adsorption. For the dense p2mg(2[times]1)CO/Ni(110) surface layer, photoemission intensities from C 1s level were measured in three directions at photoelectron kinetic energies 60-400 eV. Using multiple-scattering spherical-wave (MSSW) modeling, it was found that CO molecules are adsorbed on short-bridge sites, with adjacent CO along the [110] direction displaced alternatively in opposite directions towards the [001] azimuths to form a zigzag chain geometry. The tilt angle is 16[plus minus]2[degree] from the surface normal for the direction linking the C atom and the center of the Ni bridge. The carbon C-Ni interatomic distance was determined to be 1.94[plus minus]0.02[Angstrom]. The first- to second-layer spacing of Ni is 1.27[plus minus]0.04[Angstrom], up from 1.10[Angstrom] for the clean Ni(110) surface, but close to the 1.25[Angstrom] Ni interlayer spacing in the bulk. The C-O bond length and tilt angle were varied within small ranges (1.10--1.20[Angstrom] and 15--23[degrees]) in our MSSW simulations. Best agreement between experiment and simulations was achieved at 1.16[Angstrom] and 19[degrees]. This yields an O-O distance of 2.95[Angstrom] for the two nearest CO molecules, (van der Waals' radius [approximately] 1.5 [Angstrom] for oxygen). Two different partial-wave phase-shifts were used in MSSW, and structural results from both are in very good agreement. For the p(2[times]2)K/Ni(111) overlayer, ARPEFS [chi](k) curves from K 1s level measured along [111] and [771] at 130K showed that the K atoms are preferentially adsorbed on the atop sites, in agreement with a LEED study of the same system.

  9. Structural studies of molecular and metallic overlayers using angle- resolved photoemission extended fine structure

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Z.

    1992-10-01

    Angle-resolved photoemission extended fine structure (ARPEFS) was used to study molecular and metallic overlayers on metal surfaces through analysis of p2mg(2{times}1)CO/Ni(110) and the p(2{times}2)K/Ni(111) adsorption. For the dense p2mg(2{times}1)CO/Ni(110) surface layer, photoemission intensities from C 1s level were measured in three directions at photoelectron kinetic energies 60-400 eV. Using multiple-scattering spherical-wave (MSSW) modeling, it was found that CO molecules are adsorbed on short-bridge sites, with adjacent CO along the [110] direction displaced alternatively in opposite directions towards the [001] azimuths to form a zigzag chain geometry. The tilt angle is 16{plus_minus}2{degree} from the surface normal for the direction linking the C atom and the center of the Ni bridge. The carbon C-Ni interatomic distance was determined to be 1.94{plus_minus}0.02{Angstrom}. The first- to second-layer spacing of Ni is 1.27{plus_minus}0.04{Angstrom}, up from 1.10{Angstrom} for the clean Ni(110) surface, but close to the 1.25{Angstrom} Ni interlayer spacing in the bulk. The C-O bond length and tilt angle were varied within small ranges (1.10--1.20{Angstrom} and 15--23{degrees}) in our MSSW simulations. Best agreement between experiment and simulations was achieved at 1.16{Angstrom} and 19{degrees}. This yields an O-O distance of 2.95{Angstrom} for the two nearest CO molecules, (van der Waals` radius {approximately} 1.5 {Angstrom} for oxygen). Two different partial-wave phase-shifts were used in MSSW, and structural results from both are in very good agreement. For the p(2{times}2)K/Ni(111) overlayer, ARPEFS {chi}(k) curves from K 1s level measured along [111] and [771] at 130K showed that the K atoms are preferentially adsorbed on the atop sites, in agreement with a LEED study of the same system.

  10. Fine structure analysis of biocompatible ceramic materials based hydroxyapatite and metallic biomaterials 316L

    Energy Technology Data Exchange (ETDEWEB)

    Anghelina, F.V.; Ungureanu, D.N.; Bratu, V. [Faculty of Materials Engineering and Mechanics, Valahia University of Targoviste, 18-24 Unirii Bd., 130082 (Romania); Popescu, I.N., E-mail: pinicoleta24@yahoo.com [Faculty of Materials Engineering and Mechanics, Valahia University of Targoviste, 18-24 Unirii Bd., 130082 (Romania); Rusanescu, C.O. [Politehnica University, 060042 Bucharest (Romania)

    2013-11-15

    The aim of this paper was to obtain and characterize (surface morphology and fine structure) two types of materials: Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2} hydroxyapatite powder (HAp) as biocompatible ceramic materials and AISI 316L austenitic stainless steels as metallic biomaterials, which are the components of the metal–ceramic composites used for medical implants in reconstructive surgery and prosthetic treatment. The HAp was synthesized by coprecipitation method, heat treated at 200 °C, 800 °C and 1200 °C for 4 h, analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM). The stainless steel 316L type was made by casting, annealing and machined with a low speed (100 mm/s) in order to obtain a smooth surface and after that has been studied from residual stresses point of view in three polishing regimes conditions: at low speed polishing (150 rpm), at high speed polishing (1500 rpm) and high speed-vibration contact polishing (1500 rpm) using wide angle X-ray diffractions (WAXD). The chemical compositions of AISI 316 steel samples were measured using a Foundry Master Spectrometer equipped with CCD detector for spectral lines and the sparking spots of AISI 316L samples were analyzed using SEM. By XRD the phases of HAp powders have been identified and also the degree of crystallinity and average size of crystallites, and with SEM, we studied the morphology of the HAp. It has been found from XRD analysis that we obtained HAp with a high degree of crystallinity at 800 °C and 1200 °C, no presence of impurity and from SEM analysis we noticed the influence of heat treatment on the ceramic particles morphology. From the study of residual stress profiles of 316L samples were observed that it differs substantially for different machining regimes and from the SEM analysis of sparking spots we revealed the rough surfaces of stainless steel rods necessary for a better adhesion of HAp on it.

  11. Close-coupling calculations of fine-structure excitation of Ne II due to H and electron collisions

    Science.gov (United States)

    Stancil, Phillip C.; Cumbee, Renata; Wang, Qianxia; Loch, Stuart; Pindzola, Michael; Schultz, David R.; Buenker, Robert; McLaughlin, Brendan; Ballance, Connor

    2016-06-01

    Fine-structure transitions within the ground term of ions and neutral atoms dominate the cooling in a variety of molecular regions and also provide important density and temperature diagnostics. While fine-structure rates due to electron collisions have been studied for many systems, data are generally sparse for elements larger than oxygen, at low temperatures, and for collisions due to heavy particles. We provide rate coefficients for H collisions for the first time. The calculations were performed using the quantum molecular-orbital close-coupling approach and the elastic approximation. The heavy-particle collisions use new potential energies for the lowest-lying NeH+ states computed with the MRDCI method. The focus of the electron-impact calculations is to provide fine-structure excitation rate coefficients down to 10 K. We compare with previous calculations at higher temperatures (Griffin et al. 2001), and use a range of calculations to provide an estimate of the uncertainty on our recommended rate coefficients. A brief discussion of astrophysical applications is also provided.Griffin, D.C., et al., 2001, J. Phys. B, 34, 4401This work partially supported by NASA grant No. NNX15AE47G.

  12. Quiescent Prominences in the Era of ALMA: Simulated Observations Using the 3D Whole-prominence Fine Structure Model

    Science.gov (United States)

    Gunár, Stanislav; Heinzel, Petr; Mackay, Duncan H.; Anzer, Ulrich

    2016-12-01

    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.

  13. Flaring loop parameters estimated from solar decimeter type U-like and type J-like fine structures

    Science.gov (United States)

    Fernandes, Francisco C. R.; Dutra, José Augusto S. S.; Cunha da Silva, Rafael D.; Sawant, Hanumant S.

    2012-06-01

    This work presents the analysis of five fine structures in the solar radio emission, observed between June 2000 and October 2001 by the Brazilian Solar Spectroscope (BSS), in the decimeter frequency band of 950-2500 MHz. Based on their morphological characteristics identified in the dynamic spectra, the fine structures had been classified as type U-like or type J-like bursts. Such emissions are variants of the type III bursts. They support the hypothesis of generation by plasma emission mechanism, from interaction of electron beams accelerated during solar flares, propagating along closed magnetic structures, within the trapped plasma of the solar corona. The spectral and temporal characteristics of the five fine structures had been obtained from the dynamic spectra and the parameters of the agent and the emitting source have been determined, assuming both fundamental and harmonic emissions. The analysis revealed the flux density of the structures is less than 20-80 s.f.u. For assumption of harmonic emission, the interval of values for the source parameters estimated are: the loop size is (0.3-5.1) × 1010 cm; the electron beam velocity is in the range of 0.16-0.53 c; the temperature of coronal loop top is of the order of (0.25-1.55) × 107 K; and the low limit for the magnetic field is of 7-26 G. These results are in agreement with previous determinations reported in the literature.

  14. Laser Spectroscopy of the Fine-Structure Splitting in the 2 PJ 3 Levels of He 4

    Science.gov (United States)

    Zheng, X.; Sun, Y. R.; Chen, J.-J.; Jiang, W.; Pachucki, K.; Hu, S.-M.

    2017-02-01

    The fine-structure splitting in the 2 PJ 3 (J =0 , 1, 2) levels of He 4 is of great interest for tests of quantum electrodynamics and for the determination of the fine-structure constant α . The 2 P0 3 -2 P2 3 and 2 P1 3 -2 P2 3 intervals are measured by laser spectroscopy of the PJ 3 -2 S1 3 transitions at 1083 nm in an atomic beam, and are determined to be 31 908 130.98 ±0.13 kHz and 2 291 177.56 ±0.19 kHz , respectively. Compared with calculations, which include terms up to α5Ry , the deviation for the α -sensitive interval 2 P0 3 -2 P2 3 is only 0.22 kHz. It opens the window for further improvement of theoretical predictions and an independent determination of the fine-structure constant α with a precision of 2 ×10-9 .

  15. Catalog of fine-structured electron velocity distribution functions - Part 1: Antiparallel magnetic-field reconnection (Geospace Environmental Modeling case)

    Science.gov (United States)

    Bourdin, Philippe-A.

    2017-09-01

    To understand the essential physics needed to reproduce magnetic reconnection events in 2.5-D particle-in-cell (PIC) simulations, we revisit the Geospace Environmental Modeling (GEM) setup. We set up a 2-D Harris current sheet (that also specifies the initial conditions) to evolve the reconnection of antiparallel magnetic fields. In contrast to the GEM setup, we use a much smaller initial perturbation to trigger the reconnection and evolve it more self-consistently. From PIC simulation data with high-quality particle statistics, we study a symmetric reconnection site, including separatrix layers, as well as the inflow and the outflow regions. The velocity distribution functions (VDFs) of electrons have a fine structure and vary strongly depending on their location within the reconnection setup. The goal is to start cataloging multidimensional fine-structured electron velocity distributions showing different reconnection processes in the Earth's magnetotail under various conditions. This will enable a direct comparison with observations from, e.g., the NASA Magnetospheric MultiScale (MMS) mission, to identify reconnection-related events. We find regions with strong non-gyrotropy also near the separatrix layer and provide a refined criterion to identify an electron diffusion region in the magnetotail. The good statistical significance of this work for relatively small analysis areas reveals the gradual changes within the fine structure of electron VDFs depending on their sampling site.

  16. 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.

  17. ESR dosimetry using eggshells and tooth enamel for accidental dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Oka, Toshihide; Yamanaka, Chihiro; Ikeya, Motoji [Department of Earth and Space Science, Faculty of Science, Osaka Univ., Toyonaka, Osaka (Japan)

    1997-07-01

    The CO{sub 2}{sup -} signal of eggshells showed a good dose linearity and was appropriate in the wide dose range from 1 to 10 kGy, while ESR signal of CO{sub 2}{sup -} in sea and fresh water shells were saturated at a dose od below 10 kGy. The minimum detectable dose and G-value of CO{sub 2}{sup -} in eggshells were estimated 0.3 Gy and 0.28, respectively. The lifetime of CO{sub 2}{sup -} in eggshells could not be determined exactly because of overlapping organic signals, however it is still sufficiently long for practical use as ESR dosimeter materials. Various bird`s or reptile`s eggshells would be available as natural retrospective ESR dosimeter materials after nuclear accidents. Eggshells will be useful for the food irradiation dosimetry in the dose range of about a few kGy. Tooth enamel is one of the most useful dosimeter materials in public at a accident because of its high sensitivity. ESR dosimetry will replace TLD in near future if the cost of an ESR reader is further reduced . (author)

  18. Functionalization of Phenyl Rings by Imidoylnitrenes. 3 The Effects of Resonance, Steric, and Inductive Properties on the Reactivity or Selectivity of Nitrenes and the Stability of their Precursors

    Directory of Open Access Journals (Sweden)

    Reza Karimzadeh

    2002-02-01

    Full Text Available The thermal decomposition of imidoyl azides (ArO-C=N-Z-N3, (Ar = p-NO2-C6H4-, p-Br-C6H4-, p-Cl-C6H4-, p-C6H5-, p-CH3-C6H4-, 2,4-dimethyl-C6H3-, 2,4,6-trimethyl-C6H2-, p-CH3O-C6H4- and Z = p-CH3-C6H4-SO2-, 2,4,6-trimethyl-C6H2-SO2-,CN in the solid phase and in anisole has been studied in detail. The sensitivity of nitrenes and nitrene precursors (imidoyl azides towards substitution changes in the aryloxy (ArO and Z moieties is examined.

  19. ESR studies on flint with a difference-spectrum method

    Science.gov (United States)

    Walther, R.; Zilles, D.

    Dating of fired flints with ESR is often difficult because of disturbing signals in the ESR spectrum. Flint samples from the archaeological sites 'San Quintin de Mediona' (NE Spain) and 'Berigoule' (in the south of France) were used for studies on the Al centre in heated material. Our samples measured at 100 K show the Al signal with very weak hyperfine structure and an unidentified disturbing signal, similar to the spectra described by Porat and Schwarcz (1991). We tested a new method for subtracting the spectrum of a disturbing signal from the Al spectrum (as an alternative procedure to the method proposed by Porat and Schwarcz, 1991), using different measurement temperatures. The DE determination with these filtered Al spectra was carried out and was compared with the usual procedure on one flint sample. For comparison with the ESR results we measured TL on some of the samples.

  20. ESR studies of E' centres in geological flint

    Energy Technology Data Exchange (ETDEWEB)

    Bartoll, J. E-mail: bartoll@mcmail.cis.mcmaster.ca; Schwarcz, H.P.; Rink, W.J

    2001-12-01

    Properties of E' centres of high geological age in flint from different locations have been studied. ESR spectra of {gamma}-irradiated samples of heated and unheated Silurian and Eocene flint show thermally unstable components. The spectrum of one species could be simulated using the g values: 2.00164, 2.00059, and 2.00046. Two others deliver ESR-signals at g=2.0015 and 2.0012, respectively. These unstable components cannot be identified with any known E' centres. About 50% of the ESR intensity of the E' centres in unheated flint induced by artificial {gamma}-rays is thermally stable. This effect is probably due to a steady state and might be useful for dating of unburned flint tools ('skinflint dating')

  1. Mobility Studies on Nitroxyl Radicals using ESR 300 MHz Spectrometer

    Science.gov (United States)

    Dhas, M. Kumara; Franklin Benial, A. Milton; Jawahar, A.

    2011-07-01

    The mobility studies on 14N labeled TEMPOL, carboxy PROXYL, carbamoyl PROXYL in pure water, pure water and glycerol at ratio (15:85) was carried out using 300 MHz ESR spectrometer. The ESR parameters such as linewidth, signal intensity ratio and correlation time were determined. The isotropic g-factor and hyperfine coupling constant were also estimated. This ESR study reveals that the dipolar and spin exchange interactions are less in the 14N labeled TEMPOL radical. This phenomenon can be explained in terms of the structural, physical and chemical properties of the TEMPOL molecule. The mobility of TEMPOL radical is not much affected by the high viscous medium. Hence the TEMPOL radical can be used as a good spin probe in high viscous medium.

  2. Application of ESR spin label oximetry in food science.

    Science.gov (United States)

    Zhou, Yu-Ting; Yin, Jun-Jie; Lo, Y Martin

    2011-12-01

    Lipid oxidation attributed to the presence of oxygen has long been a focal area for food science research due in early years mainly to its broad impact on the quality and shelf stability. The need to effectively strategize interventions to detect and eventually eliminate lipid oxidation in food remains as evidence on nutritional and health implications continue to accumulate. Electron spin resonance (ESR) spin label oximetry has been shown capable of detecting dissolved oxygen concentration in both liquid and gaseous phases based on the collision between oxygen and stable free radicals. This review aimed to summarize not just the principles and rationale of ESR spin label oximetry but also the wide spectrum of ESR spin label oximetry applications to date. The feasibility to identify in very early stage oxygen generation and consumption offers a promising tool for controlling lipid oxidation in food and biological systems.

  3. Proper Versus Improper Mixtures in the ESR Model

    CERN Document Server

    Garola, Claudio

    2011-01-01

    The interpretation of mixtures is problematic in quantum mechanics (QM) because of nonobjectivity of properties. The ESR model restores objectivity reinterpreting quantum probabilities as conditional on detection and embodying the mathematical formalism of QM into a broader noncontextual (hence local) framework. We have recently provided a Hilbert space representation of the generalized observables that appear in the ESR model. We show here that each proper mixture is represented by a family of density operators parametrized by the macroscopic properties characterizing the physical system $\\Omega$ that is considered and that each improper mixture is represented by a single density operator which coincides with the operator that represents it in QM. The new representations avoid the problems mentioned above and entail some predictions that differ from the predictions of QM. One can thus contrive experiments for distinguishing empirically proper from improper mixtures, hence for confirming or disproving the ESR...

  4. Photoluminescence and extended X-ray absorption fine structure studies on cadmium telluride material

    Science.gov (United States)

    Liu, Xiangxin

    The direct-band-gap semiconductor CdTe is an important material for fabricating high efficiency, polycrystalline thin-film solar cells in a heterojunction configuration. The outstanding physical properties of this material such as its good band-gap match to the solar spectrum, ease of fabrication of stoichiometric films, and easy grain boundary passivation make it an important candidate for large area, thin-film solar cells. However, there are several poorly understood processing steps that are commonly utilized in cell fabrication. One of these is a CdCl2 treatment near 400°C in the presence of oxygen, which can improve the cell efficiency a factor of two or more. Another factor is the role of copper in cell performance. In high performance CdS/CdTe thin-film solar cells, copper is usually included in the fabrication of low-resistance back contacts to obtain heavy p-type doping of the absorber CdTe at the contact. However, most of the copper is not electrically active. For example, secondary ion mass spectroscopy (SIMS) on typical CdTe cells has shown Cu concentrations of 1019 atoms/cm3 and even higher, although capacitance-voltage (C-V) measurements indicate typical ionized acceptor levels on the order of 1014/cm 3. Thus, there is great interest in the location and role of this inactive copper in CdTe photovoltaic (PV) devices. In this thesis, I will describe results obtained on magnetron-sputtered CdTe films that were diffused with copper following the procedure used for creating a cell back contact. Extended X-ray Absorption Fine Structure (EXAFS) measurements identified the chemical environment of the majority of the copper and show major differences depending on whether the CdTe film has been treated with chloride prior to the Cu diffusion. The EXAFS data indicate that the Cu chemistry is strongly affected by the chloride treatments---predominantly Cu2Te when Cu was diffused into the as-deposited CdTe film, but a Cu2O environment when Cu was diffused after

  5. Predicting ESR Peaks in Copper (II Chelates Having Quadrupolar Coordinating Sites by NMR, ESR and NQR Techniques: A DFT Study

    Directory of Open Access Journals (Sweden)

    Harminder Singh

    2015-06-01

    Full Text Available Computational chemistry was helpful in predicting the number of ESR peaks in Cu (II complexes having a large number of spatially different NMR and ESR active nuclei. The presence of the large Jahn-Teller effect and the high value of spin-orbit coupling constant of the metal ion made the experimental determination of the exact number of ESR peaks quite difficult in such complexes. Fourteen distorted poly-dentate chelating Cu(II complexes included in this study were of two types such as [Cu(gly2] , [Cu(edta]4-,[Cu(tpyX2] (X= Cl, Br, I, NCS and [Cu(en2]2+, [Cu(teta]2+, Cu(tepa]2+ ,[Cu(peha]2+, [Cu(detaX2] (X= Cl, Br, I, NCS.The latter eight complexes belonged to an important class of ligands called polyethylene polyamines. Density functional theory implemented in ADF: 2010.02 was applied. Three parameters of both the ESR (A ten and NQR (NQCC, for the Cu(II and the coordinating atoms of the ligands were obtained from “ESR/EPR program” and two NMR parameters namely the shielding constants (σ and chemical shifts (δ were obtained from “NMR/EPR program” after optimization of the complexes. The species having the same values of these 5 parameters were expected to be spatially equivalent to undergo the same hyperfine interaction with Cu (II.

  6. Photoaffinity Labeling via Nitrenium Ion Chemistry: Protonation of the Nitrene Derived from a 4-Amino-3-nitrophenylazide to Afford Reactive Nitrenium Ion Pairs

    Science.gov (United States)

    Voskresenska, Valentyna; Wilson, R. Marshall; Panov, Maxim; Tarnovsky, Alexander N.; Krause, Jeanette A.; Vyas, Shubham; Winter, Arthur H.; Hadad, Christopher M.

    2009-01-01

    Phenyl azides with powerful electron-donating substituents are known to deviate from the usual photochemical behavior of other phenyl azides. They do not undergo ring expansion, but form basic nitrenes that protonate to form nitrenium ions. The photochemistry of the widely used photoaffinity labeling system 4-amino-3-nitrophenyl azide, 5, has been studied by transient absorption spectroscopy from femtosecond to microsecond time domains and from a theoretical perspective. The nitrene generation from azide 5 occurs on the S2 surface, in violation of Kasha's rule. The resulting nitrene is a powerful base and abstracts protons extremely rapidly from a variety of sources to form a nitrenium ion. In methanol, this protonation occurs in about 5 ps, which is the fastest intermolecular protonation observed to date. Suitable proton sources include alcohols, amine salts, and even acidic C-H bonds such as acetonitrile. The resulting nitrenium ion is stabilized by the electron-donating 4-amino group to afford a diiminoquinone-like species that collapses relatively slowly to form the ultimate cross-linked product. In some cases in which the anion is a good hydride donor, cross-linking is replaced by reduction of the nitrenium ion to the corresponding amine. PMID:19624129

  7. Mechanistic Insight into the Intramolecular Benzylic C-H Nitrene Insertion Catalyzed by Bimetallic Paddlewheel Complexes: Influence of the Metal Centers.

    Science.gov (United States)

    Zhang, Xuepeng; Xu, Huiying; Liu, Xueping; Phillips, David Lee; Zhao, Cunyuan

    2016-05-17

    The intramolecular benzylic C-H amination catalyzed by bimetallic paddlewheel complexes was investigated by using density functional theory calculations. The metal-metal bonding characters were investigated and the structures featuring either a small HOMO-LUMO gap or a compact SOMO energy scope were estimated to facilitate an easier one-electron oxidation of the bimetallic center. The hydrogen-abstraction step was found to occur through three manners, that is, hydride transfer, hydrogen migration, and proton transfer. The imido N species are more preferred in the Ru-Ru and Pd-Mn cases whereas coexisting N species, namely, singlet/triplet nitrene and imido, were observed in the Rh-Rh and Pd-Co cases. On the other hand, the triplet nitrene N species were found to be predominant in the Pd-Ni and Pd-Zn systems. A concerted asynchronous mechanism was found to be modestly favorable in the Rh-Rh-catalyzed reactions whereas the Pd-Co-catalyzed reactions demonstrated a slight preference for a stepwise pathway. Favored stepwise pathways were seen in each Ru-Ru- and Pd-Mn-catalyzed reactions and in the triplet nitrene involved Pd-Ni and Pd-Zn reactions. The calculations suggest the feasibility of the Pd-Mn, Pd-Co, and Pd-Ni paddlewheel complexes as being economical alternatives for the expensive dirhodium/diruthenium complexes in C-H amination catalysis. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Activation of Carbon-Hydrogen and Hydrogen-Hydrogen Bonds by Copper-Nitrenes: A Comparison of Density Functional Theory with Single- and Multireference Correlation Consistent Composite Approaches.

    Science.gov (United States)

    Tekarli, Sammer M; Williams, T Gavin; Cundari, Thomas R

    2009-11-10

    The kinetics and thermodynamics of copper-mediated nitrene insertion into C-H and H-H bonds (the former of methane) have been studied using several levels of theory: B3LYP/6-311++G(d,p), B97-1/cc-pVTZ, PBE1KCIS/cc-pVTZ, and ccCA (correlation consistent Composite Approach). The results show no significant difference among the DFT methods. All three DFT methods predict the ground state of the copper-nitrene model complex, L'Cu(NH), to be a triplet, while single reference ccCA predicts the singlet to be the ground state. The contributions to the total ccCA energy indicate that the singlet state is favored at the MP2/CBS level of theory, while electron correlation beyond this level (CCSD(T)) favors a triplet state, resulting in a close energetic balance between the two states. A multireference ccCA method is applied to the nitrene active species and supports the assignment of a singlet ground state. In general, the largest difference in the model reaction cycles between DFT and ccCA methods is for processes involving radicals and bond dissociation.

  9. An alternative procedure for ESR identification of irradiated chicken drumsticks

    Energy Technology Data Exchange (ETDEWEB)

    Bordi, F. (Rome-2 Univ. (Italy). Dip. di Medicina Interna); Fattibene, P.; Onori, S.; Pantaloni, M. (Istituto Superiore di Sanita, Rome (Italy) Istituto Nazionale di Fisica Nucleare, Rome (Italy))

    The ESR spectroscopy is, at present, the most established technique for quantitative analysis of irradiated chicken bone using the additive dose method. In this paper we tried a different approach to the problem analyzing the ESR behavior of a batch of chicken bone samples coming randomly from the market. Using a suitable and standardized sample preparation technique and sample positioning in the microwave cavity, we obtained a coefficient of variation of about 30% for the batch response. The calibration curve, obtained using the batch behavior up to 10 kGy, was used for a quantitative test on unknown samples. (author).

  10. ESR STUDY OF FREE RADICALS IN IRRADIATED POLYAMIDE- 1010

    Institute of Scientific and Technical Information of China (English)

    ZHOU Maotang; ZHANG Lihua; LIU Yayan; CHEN Donglin

    1993-01-01

    Polyamide-1010 samples were irradiated in vacuum at room temperature by Cobalt-60γ-rays. The free radicals formed in irradiation were studied by means of electron spin resonance (ESR)techniques. The ESR spectra consisted of a quartet and a superimposed singlet whichwere attributed to radical - CO - NH - CH - CH2 and - CH2 - C = O, respectively. The effects of temperature and crystallinity on the radicals were discussed and the mechanism for the production and decay of the radicals was also proposed.

  11. FS4, FS4-p, and FSP: a 4-month crossover study of 3 fine structure sound-coding strategies.

    Science.gov (United States)

    Riss, Dominik; Hamzavi, Jafar-Sasan; Blineder, Michaela; Honeder, Clemens; Ehrenreich, Isabella; Kaider, Alexandra; Baumgartner, Wolf-Dieter; Gstoettner, Wolfgang; Arnoldner, Christoph

    2014-01-01

    The aim of the present study was to compare two novel fine structure strategies "FS4" and "FS4-p" with the established fine structure processing (FSP) strategy. FS4 provides fine structure information on the apical four-electrode channels. With FS4-p, these electrodes may be stimulated in a parallel manner. The authors evaluated speech perception, sound quality, and subjective preference. A longitudinal crossover study was done on postlingually deafened adults (N = 33) who were using FSP as their default strategy. Each participant was fitted with FS4, FS4-p, and FSP, for 4 months in a randomized and blinded order. After each run, an Adaptive Sentence test in noise (Oldenburger Sentence Test [OLSA]) and a Monosyllable test in quiet (Freiburger Monosyllables) were performed, and subjective sound quality was determined with a Visual Analogue Scale. At the end of the study the preferred strategy was noted. Scores of the OLSA did not reveal any significant differences among the three strategies, but the Freiburger test showed a statistically significant effect (p = 0.03) with slightly worse scores for FS4 (49.7%) compared with FSP (54.3%). Performance of FS4-p (51.8%) was comparable with the other strategies. Both audiometric tests depicted a high variability among subjects. The number of best-performing strategies for each participant individually was as follows: (a) for the OLSA: FSP, N = 10.5; FS4, N = 10.5; and FS4-p, N = 12; and (b) for the Freiburger test: FSP, N = 14; FS4, N = 9; and FS4-p, N = 10. A moderate agreement was found in the best-performing strategies of the Speech tests within the participants. For sound quality, speech in quiet, classical, and pop music were assessed. No significant effects of strategy were found for speech in quiet and classical music, but auditory impression of pop music was rated as more natural in FSP compared with FS4 (p = 0.04). It is interesting that at the end of the study, a majority of the participants favored the new

  12. Optical transitions in highly charged californium ions with high sensitivity to variation of the fine-structure constant.

    Science.gov (United States)

    Berengut, J C; Dzuba, V A; Flambaum, V V; Ong, A

    2012-08-17

    We study electronic transitions in highly charged Cf ions that are within the frequency range of optical lasers and have very high sensitivity to potential variations in the fine-structure constant, α. The transitions are in the optical range despite the large ionization energies because they lie on the level crossing of the 5f and 6p valence orbitals in the thallium isoelectronic sequence. Cf(16+) is a particularly rich ion, having several narrow lines with properties that minimize certain systematic effects. Cf(16+) has very large nuclear charge and large ionization energy, resulting in the largest α sensitivity seen in atomic systems. The lines include positive and negative shifters.

  13. 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

  14. Time-variability of the fine-structure constant expected from the Oklo constraint and the QSO absorption lines

    CERN Document Server

    Fujii, Y

    2003-01-01

    The data from the QSO absorption lines indicating a nonzero time-variability of the fine-structure constant has been re-analyzed on the basis of a "damped-oscillator" fit, as motivated by the same type of behavior of a scalar field, dilaton, which mimics a cosmological constant to understand the accelerating universe. We find nearly as good fit to the latest data as the simple weighted mean. In this way, we offer a way to fit the more stringent result from the Oklo phenomenon, as well.

  15. Time-variability of the fine-structure constant expected from the Oklo constraint and the QSO absorption lines

    Science.gov (United States)

    Fujii, Yasunori

    2003-10-01

    The data from the QSO absorption lines indicating a nonzero time-variability of the fine-structure constant has been re-analyzed on the basis of a ``damped-oscillator'' fit, as motivated by the same type of behavior of a scalar field, dilaton, which mimics a cosmological constant to understand the accelerating universe. We find nearly as good fit to the latest data as the simple weighted mean. In this way, we offer a way to fit the more stringent result from the Oklo phenomenon, as well.

  16. Determination of the fine structure constant based on BLOCH oscillations of ultracold atoms in a vertical optical lattice.

    Science.gov (United States)

    Cladé, Pierre; de Mirandes, Estefania; Cadoret, Malo; Guellati-Khélifa, Saïda; Schwob, Catherine; Nez, François; Julien, Lucile; Biraben, François

    2006-01-27

    We report an accurate measurement of the recoil velocity of 87Rb atoms based on Bloch oscillations in a vertical accelerated optical lattice. We transfer about 900 recoil momenta with an efficiency of 99.97% per recoil. A set of 72 measurements of the recoil velocity, each one with a relative uncertainty of about 33 ppb in 20 min integration time, leads to a determination of the fine structure constant with a statistical relative uncertainty of 4.4 ppb. The detailed analysis of the different systematic errors yields to a relative uncertainty of 6.7 ppb. The deduced value of alpha-1 is 137.035 998 78(91).

  17. Combination of BLOCH oscillations with a Ramsey-Bordé interferometer: new determination of the fine structure constant.

    Science.gov (United States)

    Cadoret, Malo; de Mirandes, Estefania; Cladé, Pierre; Guellati-Khélifa, Saïda; Schwob, Catherine; Nez, François; Julien, Lucile; Biraben, François

    2008-12-01

    We report a new experimental scheme which combines atom interferometry with Bloch oscillations to provide a new measurement of the ratio h/mRb. By using Bloch oscillations, we impart to the atoms up to 1600 recoil momenta and thus we improve the accuracy on the recoil velocity measurement. The deduced value of h/mRb leads to a new determination of the fine structure constant alpha(-1) =137.03599945 (62) with a relative uncertainty of 4.6 x 10(-9). The comparison of this result with the value deduced from the measurement of the electron anomaly provides the most stringent test of QED.

  18. 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

    a matter of debate. For stimuli with components lying exclusively in high-frequency spectral regions, the slowly varying temporal envelope of sounds is often assumed to be the only information contained in auditory temporal representations, and it has remained controversial to what extent the fast...... 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...

  19. Relativistic energy, fine structure and hyperfine structure of the low-lying excited states for Be-like system

    Institute of Scientific and Technical Information of China (English)

    Zhang Meng; Gou Bing-Cong

    2005-01-01

    Variational calculations are carried out with a multiconfiguration-interaction wavefunction on the 1s22p2p 1De and 1s22p3p 3pe states to obtain the energies including the mass polarization and relativistic corrections for the beryllium isoelectronic sequence (Z=4-10). The oscillator strengths, transition rates and wavelengths are also calculated. Our results are compared with other theoretical and experimental data in the literatures. The fine structure and hyperfine structure of 1s22p3p 3pe state are also explored.

  20. Atomic sulfur: Frequency measurement of the J = 0 left arrow 1 fine-structure transition at 56.3 microns by laser magnetic resonance

    Science.gov (United States)

    Brown, John M.; Evenson, Kenneth M.; Zink, Lyndon R.

    1994-01-01

    The J = 0 left arrow 1 fine-structure transition in atomic sulfur (S I) in its ground (3)P state has been detected in the laboratory by far-infrared laser magnetic resonance. The fine-structure interval has been measured accurately as 5,322,492.9 +/- 2.8 MHz which corresponds to a wavelength of 56.325572 +/- 0.000030 micrometers.

  1. 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

  2. Theory of two-dimensional ESR with nuclear modulation

    Science.gov (United States)

    Gamliel, Dan; Freed, Jack H.

    A formalism for computing 2D ESR lineshapes with nuclear modulation is developed in a form which is useful for planning phase cycles for particular purposes. A simple method of processing spectra, utilizing quadrature detection, is shown to enhance the selectivity of the phase cycling techniques. Computed ESR-COSY, ESR-SECSY, and 2D ELDOR lineshapes are presented for several kinds of polycrystalline and single-crystal samples which exhibit nuclear modulation, due to one or several nuclei. The two-dimensional methods are found to give more detailed structural information than the corresponding ESEEM spectra. New phase cycles are found to eliminate completely all transverse and axial peaks in 2D ELDOR and in ESR-COSY, and at the same time eliminate all artifacts arising from incomplete image rejection. Other phase cycles are presented for selecting in those experiments only axial peaks, for measuring T1. It is also shown how selective phase cycles may help to distinguish between coherent and exchange cross peaks. In the special case of nitroxides in typical Zeeman fields, there are no significant nuclear modulation effects from the 14N nuclear spin interaction, but those from the protons (or deuterons) will, in general, be significant.

  3. File list: Oth.ALL.50.ESR1.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  4. File list: Oth.ALL.05.ESR1.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  5. File list: Oth.Prs.20.ESR1.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  9. File list: Oth.Prs.05.ESR1.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  10. File list: Oth.Utr.10.ESR1.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  1. ESR1 inhibits hCG-induced steroidogenesis and proliferation of progenitor Leydig cells in mice.

    Science.gov (United States)

    Oh, Yeong Seok; Koh, Il Kyoo; Choi, Bomi; Gye, Myung Chan

    2017-03-07

    Oestrogen is an important regulator in reproduction. To understand the role of oestrogen receptor 1 (ESR1) in Leydig cells, we investigated the expression of ESR1 in mouse Leydig cells during postnatal development and the effects of oestrogen on steroidogenesis and proliferation of progenitor Leydig cells (PLCs). In Leydig cells, the ESR1 expression was low at birth, increased until postnatal day 14 at which PLCs were predominant, and then decreased until adulthood. In foetal Leydig cells, ESR1 immunoreactivity increased from birth to postnatal day 14. These suggest that ESR1 is a potential biomarker of Leydig cell development. In PLCs, 17β-estradiol and the ESR1-selective agonist propylpyrazoletriol suppressed human chorionic gonadotropin (hCG)-induced progesterone production and steroidogenic gene expression. The ESR2-selective agonist diarylpropionitrile did not affect steroidogenesis. In PLCs from Esr1 knockout mice, hCG-stimulated steroidogenesis was not suppressed by 17β-estradiol, suggesting that oestrogen inhibits PLC steroidogenesis via ESR1. 17β-estradiol, propylpyrazoletriol, and diarylpropionitrile decreased bromodeoxyuridine uptake in PLCs in the neonatal mice. In cultured PLCs, 17β-estradiol, propylpyrazoletriol, and diarylpropionitrile reduced hCG-stimulated Ki67 and Pcna mRNA expression and the number of KI67-positive PLCs, suggesting that oestrogen inhibits PLC proliferation via both ESR1 and ESR2. In PLCs, ESR1 mediates the oestrogen-induced negative regulation of steroidogenesis and proliferation.

  2. Direct observation of the M1 transition between the ground state fine structure splitting of W VIII

    CERN Document Server

    Mita, Momoe; Kato, Daiji; Murakami, Izumi; Nakamura, Nobuyuki

    2016-01-01

    We present direct observation of the M1 transition between the fine structure splitting in the 4f13 5s2 5p6 2F ground state 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 lack. 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 the identification of the previously-unreported visible lines. The observed wavelength 574.47 pm 0.03 nm (air), which corresponds to the fine structure splitting of 17402.5 pm 0.9 cm-1, shows reasonable agreement with the previously reported value 17410 pm 5 cm-1 obtained indirectly through the analysis of EUV spectra [Ryabtsev et al., Atoms 3 (2015) 273].

  3. Study on the coordination structure of pt sorbed on bacterial cells using x-ray absorption fine structure spectroscopy.

    Directory of Open Access Journals (Sweden)

    Kazuya Tanaka

    Full Text Available Biosorption has been intensively investigated as a promising technology for the recovery of precious metals from solution. However, the detailed mechanism responsible for the biosorption of Pt on a biomass is not fully understood because of a lack of spectroscopic studies. We applied X-ray absorption fine structure spectroscopy to elucidate the coordination structure of Pt sorbed on bacterial cells. We examined the sorption of Pt(II and Pt(IV species on bacterial cells of Bacillus subtilis and Shewanella putrefaciens in NaCl solutions. X-ray absorption near-edge structure and extended X-ray absorption fine structure (EXAFS of Pt-sorbed bacteria suggested that Pt(IV was reduced to Pt(II on the cell's surface, even in the absence of an organic material as an exogenous electron donor. EXAFS spectra demonstrated that Pt sorbed on bacterial cells has a fourfold coordination of chlorine ions, similar to PtCl42-, which indicated that sorption on the protonated amine groups of the bacterial cells. This work clearly demonstrated the coordination structure of Pt sorbed on bacterial cells. The findings of this study will contribute to the understanding of Pt biosorption on biomass, and facilitate the development of recovery methods for rare metals using biosorbent materials.

  4. What could the value of the cosmological constant tell us about the future variation of the fine structure constant?

    CERN Document Server

    Romano, Antonio Enea

    2014-01-01

    Motivated by reported claims of the measurements of a variation of the fine structure constant $\\alpha$ we consider a theory where the electric charge, and consequently $\\alpha$, is not a constant but depends on the Ricci scalar $R$. %We then show how this can be considered a particular case of the Bekenstein theory in which there is no need to %introduce an additional kinetic term for the scalar field associated to the electric charge, since the Einstein's% %equations are sufficient to determine the geometry and, consequently the Ricci scalar. We then study the cosmological implications of this theory, considering in particular the effects of dark energy and of a cosmological constant on the evolution of $\\alpha$. Some low-red shift expressions for the variation of $\\alpha(z)$ are derived, showing the effects of the equation of state of dark energy on $\\alpha$ and observing how future measurements of the variation of the fine structure constant could be used to determine indirectly the equation of state of d...

  5. X-ray absorption fine structure analysis of the local environment of zinc in dentine treated with zinc compounds.

    Science.gov (United States)

    Takatsuka, Tsutomu; Hirano, Junko; Matsumoto, Hitoshi; Honma, Tetsuo

    2005-04-01

    It has been reported that zinc oxide (ZnO) inhibits dentine demineralization. By using the X-ray absorption fine structure (XAFS) technique, our aims in this study were to provide information about the local environment of zinc atoms in dentine that had been treated with zinc compounds. We measured the Zn K-edge X-ray absorption near-edge structure (XANES) and the extended X-ray absorption fine structure (EXAFS) of dentine specimens treated with zinc chloride or ZnO. In XAFS analyses, the spectra of dentine specimens treated with ZnO (D-ZO) or with zinc chloride (D-ZC) were similar and obviously different from the reference ZnO spectrum. This suggests that most of the zinc atoms detected in D-ZO are not derived from particles of ZnO. The spectra of D-ZO and D-ZC were similar to the spectrum of the synthetic, zinc-containing hydroxyapatite, but were not similar to that of zinc in ZnCl2-treated collagen. The results of this study suggest that most of the zinc atoms detected were attached to hydroxyapatite and not to collagen.

  6. An observation of further splitting of the new fine-structure in magneto-optical spectra of CuO

    Science.gov (United States)

    Masumi, Taizo; Imanaka, Yasutaka; Takehana, Kanji; Yamaguchi, Hiroyuki; Kido, Giyuu

    2001-04-01

    Regarding CuO first in 1998 (Masumi et al., J. Phys. Soc. Japan 67 (1998) 67), we reported an observation of the new fine structures near the optical absorption edge below 90 K. They consist of two sharp peaks A and B at EA=1.57511 eV and EB=1.58097 eV, respectively, at T=7 K. Two peaks emerge only below 90 K and their integrated intensity remarkably grows below 90 and 60 K. Here, we have started a magneto-optical study to seek further natures of these fine structures in the absorption edge of CuO by applying high magnetic fields up to B=25 T with a resolution of δE=1.24 meV, Δ ν=1 cm -1. Peaks A and B exhibit rather little variations up to 10 T. Above 12 T, however, there starts to emerge a potential splitting in the peak A, whereas peak B simply indicates a broadening. Finally, we clearly recognize new finer structures due to splitting in peak A at B=25 T. These results reveal a possibility of an existence of further peculiar magnetic characters in CuO even at lower temperature side besides the antiferromagnetic transitions at TN1=213 K and TN2=230 K.

  7. Unprecedented Fine Structure of a Solar Flare Revealed by the 1.6 m New Solar Telescope.

    Science.gov (United States)

    Jing, Ju; Xu, Yan; Cao, Wenda; Liu, Chang; Gary, Dale; Wang, Haimin

    2016-04-13

    Solar flares signify the sudden release of magnetic energy and are sources of so called space weather. The fine structures (below 500 km) of flares are rarely observed and are accessible to only a few instruments world-wide. Here we present observation of a solar flare using exceptionally high resolution images from the 1.6 m New Solar Telescope (NST) equipped with high order adaptive optics at Big Bear Solar Observatory (BBSO). The observation reveals the process of the flare in unprecedented detail, including the flare ribbon propagating across the sunspots, coronal rain (made of condensing plasma) streaming down along the post-flare loops, and the chromosphere's response to the impact of coronal rain, showing fine-scale brightenings at the footpoints of the falling plasma. Taking advantage of the resolving power of the NST, we measure the cross-sectional widths of flare ribbons, post-flare loops and footpoint brighenings, which generally lie in the range of 80-200 km, well below the resolution of most current instruments used for flare studies. Confining the scale of such fine structure provides an essential piece of information in modeling the energy transport mechanism of flares, which is an important issue in solar and plasma physics.

  8. E 1 transitions from the. Upsilon. prime prime state and the fine structure of the. chi. sub b prime states

    Energy Technology Data Exchange (ETDEWEB)

    Narain, M.; Lovelock, D.M.J.; Heintz, U.; Lee-Franzini, J.; Schamberger, R.D.; Willins, J.; Yanagisawa, C. (State University of New York at Stony Brook, Stony Brook, New York 11794 (USA)); Franzini, P.; Tuts, P.M.; Kanekal, S.; Wu, Q.W. (Columbia University, New York, New York 10027 (USA))

    1991-06-17

    Using the CUSB-II detector at the Cornell Electron Storage Ring, we have made precision measurements of the electric dipole transition rates from {Upsilon}{prime}{prime} to {chi}{sub {ital b}}{sup {prime}}, which are in excellent agreement with theory. The fine-structure splitting is found to be {ital M}({chi}{sub {ital b}2}{sup {prime}}){minus}{ital M}({chi}{sub {ital b}1}{sup {prime}})=13.5{plus minus}0.4{plus minus}0.5 MeV and {ital M}({chi}{sub {ital b}1}{sup {prime}}){minus}{ital M}({chi}{sub {ital b}0}{sup {prime}})=23.3{plus minus}0.7{plus minus}0.7 MeV, leading to a ratio {ital R}=0.584{plus minus}0.024{plus minus}0.02. The fine structure measures the relative contributions of the spin-orbit interaction {ital a}=9.5{plus minus}0.2{plus minus}0.1 MeV and tensor interaction {ital b}=2.3{plus minus}0.1{plus minus}0.1 MeV. We also find that the long-range confining potential transforms as a Lorentz scalar.

  9. Polarized Light Scattering with the Paschen-Back Effect, Level-crossing of Fine Structure States, and Partial Frequency Redistribution

    Science.gov (United States)

    Sowmya, K.; Nagendra, K. N.; Sampoorna, M.; Stenflo, J. O.

    2014-10-01

    The quantum interference between the fine structure states of an atom modifies the shapes of the emergent Stokes profiles in the second solar spectrum. This phenomenon has been studied in great detail both in the presence and absence of magnetic fields. By assuming a flat-spectrum for the incident radiation, the signatures of this effect have been explored for arbitrary field strengths. Even though the theory which takes into account the frequency dependence of the incident radiation is well developed, it is restricted to the regime in which the magnetic splitting is much smaller than the fine structure splitting. In the present paper, we carry out a generalization of our scattering matrix formalism including the effects of partial frequency redistribution for arbitrary magnetic fields. We test the formalism using available benchmarks for special cases. In particular, we apply it to the Li I 6708 Å D1 and D2 line system, for which observable effects from the Paschen-Back regime are expected in the Sun's spectrum.

  10. Polarized light scattering with the Paschen-back effect, level-crossing of fine structure states, and partial frequency redistribution

    Energy Technology Data Exchange (ETDEWEB)

    Sowmya, K.; Nagendra, K. N.; Sampoorna, M. [Indian Institute of Astrophysics, Koramangala, Bengaluru (India); Stenflo, J. O., E-mail: ksowmya@iiap.res.in, E-mail: knn@iiap.res.in, E-mail: sampoorna@iiap.res.in, E-mail: stenflo@astro.phys.ethz.ch [Institute of Astronomy, ETH Zurich, CH-8093 Zurich (Switzerland)

    2014-10-01

    The quantum interference between the fine structure states of an atom modifies the shapes of the emergent Stokes profiles in the second solar spectrum. This phenomenon has been studied in great detail both in the presence and absence of magnetic fields. By assuming a flat-spectrum for the incident radiation, the signatures of this effect have been explored for arbitrary field strengths. Even though the theory which takes into account the frequency dependence of the incident radiation is well developed, it is restricted to the regime in which the magnetic splitting is much smaller than the fine structure splitting. In the present paper, we carry out a generalization of our scattering matrix formalism including the effects of partial frequency redistribution for arbitrary magnetic fields. We test the formalism using available benchmarks for special cases. In particular, we apply it to the Li I 6708 Å D{sub 1} and D{sub 2} line system, for which observable effects from the Paschen-Back regime are expected in the Sun's spectrum.

  11. Polarized light scattering with Paschen-Back effect, level-crossing of fine structure states and partial frequency redistribution

    CERN Document Server

    Sowmya, K; Sampoorna, M; Stenflo, J O

    2014-01-01

    The quantum interference between the fine structure states of an atom modifies the shapes of the emergent Stokes profiles in the Second Solar Spectrum. This phenomenon has been studied in great detail both in the presence and absence of magnetic fields. By assuming a flat-spectrum for the incident radiation, the signatures of this effect have been explored for arbitrary field strengths. Even though the theory which takes into account the frequency dependence of the incident radiation is well developed, it is restricted to the regime in which the magnetic splitting is much smaller than the fine structure splitting. In the present paper, we carry out a generalization of our scattering matrix formalism including the effects of partial frequency redistribution (PRD) for arbitrary magnetic fields. We test the formalism using available benchmarks for special cases. In particular we apply it to the Li\\,{\\sc i} 6708\\,\\AA\\ D$_1$ and D$_2$ line system, for which observable effects from the Paschen-Back regime are expec...

  12. 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.

  13. Stereoselective synthesis of chiral sulfilimines from N-mesyloxycarbamates: metal-nitrenes versus metal-nitrenoids species.

    Science.gov (United States)

    Lebel, Hélène; Piras, Henri

    2015-04-03

    The synthesis of a variety of chiral sulfilimines and sulfoximines is described. The amination of thioethers with a chiral N-mesyloxycarbamate was achieved in high yields and stereoselectivities using Rh2[(S)-nttl]4 as catalyst in the presence of 4-dimethylaminopyridine (DMAP) and a pyridinium salt, such as bis(DMAP)CH2Cl2 or a viologen salt. These additives proved instrumental to enhance both the yield and the stereochemical discrimination of the reaction. Mechanistic studies and control experiments have elucidated the role of these additives. DMAP served as an apical ligand for the rhodium catalyst: an X-ray crystal structure of the (DMAP)2·[Rh2{(S)-nttl}4] complex was obtained. This complex displayed a lower and irreversible redox potential. Control experiments with preformed Rh(II)-Rh(III) complex suggested such a catalytically active species in the thioether amination process. Diastereoselectivities were influenced by the sulfonyloxy leaving group, ruling out the possibility of a common metal nitrene species and instead suggesting a rhodium-nitrenoid complex. It is believed that the bispyridinium salt played the role of a phase transfer catalyst, influencing both the yield and the diastereoselectivity of the reaction.

  14. Reaction of alkynes and azides: not triazoles through copper-acetylides but oxazoles through copper-nitrene intermediates.

    Science.gov (United States)

    Haldón, Estela; Besora, Maria; Cano, Israel; Cambeiro, Xacobe C; Pericàs, Miquel A; Maseras, Feliu; Nicasio, M Carmen; Pérez, Pedro J

    2014-03-17

    Well-defined copper(I) complexes of composition [Tpm*(,Br) Cu(NCMe)]BF4 (Tpm*(,Br) =tris(3,5-dimethyl-4-bromo-pyrazolyl)methane) or [Tpa(*) Cu]PF6 (Tpa(*) =tris(3,5-dimethyl-pyrazolylmethyl)amine) catalyze the formation of 2,5-disubstituted oxazoles from carbonyl azides and terminal alkynes in a direct manner. This process represents a novel procedure for the synthesis of this valuable heterocycle from readily available starting materials, leading exclusively to the 2,5-isomer, attesting to a completely regioselective transformation. Experimental evidence and computational studies have allowed the proposal of a reaction mechanism based on the initial formation of a copper-acyl nitrene species, in contrast to the well-known mechanism for the copper-catalyzed alkyne and azide cycloaddition reactions (CuAAC) that is triggered by the formation of a copper-acetylide complex. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Difluorophosphoryl nitrene F2P(O)N: matrix isolation and unexpected rearrangement to F2PNO.

    Science.gov (United States)

    Zeng, Xiaoqing; Beckers, Helmut; Willner, Helge; Neuhaus, Patrik; Grote, Dirk; Sander, Wolfram

    2009-12-14

    Triplet difluorophosphoryl nitrene F(2)P(O)N (X(3)A'') was generated on ArF excimer laser irradiation (lambda=193 nm) of F(2)P(O)N(3) in solid argon matrix at 16 K, and characterized by its matrix IR, UV/Vis, and EPR spectra, in combination with DFT and CBS-QB3 calculations. On visible light irradiation (lambda>420 nm) at 16 K F(2)P(O)N reacts with molecular nitrogen and some of the azide is regenerated. UV irradiation (lambda=255 nm) of F(2)P(O)N (X(3)A'') induced a Curtius-type rearrangement, but instead of a 1,3-fluorine shift, nitrogen migration to give F(2)PON is proposed to be the first step of the photoisomerization of F(2)P(O)N into F(2)PNO (difluoronitrosophosphine). Formation of novel F(2)PNO was confirmed with (15)N- and (18)O-enriched isotopomers by IR spectroscopy and DFT calculations. Theoretical calculations predict a rather long P-N bond of 1.922 A [B3LYP/6-311+G(3df)] and low bond-dissociation energy of 76.3 kJ mol(-1) (CBS-QB3) for F(2)PNO.

  16. ESR measurements of background doses in teeth of Japanese residents

    Energy Technology Data Exchange (ETDEWEB)

    Toyoda, S., E-mail: toyoda@dap.ous.ac.jp [Department of Applied Physics, Okayama University of Science, Okayama (Japan); Kondo, A. [Department of Applied Physics, Okayama University of Science, Okayama (Japan); Zumadilov, K.; Hoshi, M. [Research Institute of Radiation Biology and Medicine, Hiroshima University, Hiroshima (Japan); Miyazawa, C. [Deparment of Dentistry, Ohu University, Fukushima (Japan); Ivannikov, A. [Medical Radiological Research Center, Obninsk (Russian Federation)

    2011-09-15

    The background doses for the teeth of Japanese residents were obtained by electron spin resonance (ESR) method. The doses obtained from 77 of 92 samples are less than 100 mGy while the doses of the other samples are high up to 250 mGy. The doses for buccal part of the teeth are higher than lingual part possibly due to contributions from dental X ray examination. A positive correlation was found between the ages of the donors and the obtained doses. The averaged annual ESR dose was calculated to be 0.87 mGy/y. These doses have to be considered in actual retrospective dosimetry studies for possible radiation accidents. The statistically significant critical level for Japanese residents would be about 200 mGy for individual doses and about 100 mGy for averaged group doses for {alpha} = 5% for those with ages older than 50.

  17. ESR spectroscopic investigations of the radiation-grafting of fluoropolymers

    Energy Technology Data Exchange (ETDEWEB)

    Huebner, G.; Roduner, E. [University of Stuttgart (Germany); Brack, H.P.; Scherer, G.G. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    ESR spectroscopic investigations have clarified the influence of several preparative parameters on the reaction rates and yields obtained in the radiation-grafting method used at PSI to prepare proton-conducting polymer membranes. At a given irradiation dose, a higher concentration of reactive radical sites was detected in ETFE films than in FEP films. This higher concentration explains the higher grafting levels and rates of the ETFE films found in our previous grafting experiments. Taken together, the in-situ ESR experiments and grafting experiments show that the rates of disappearance of radical species and grafting rates and final grafting levels depend strongly on the reaction temperature and the oxygen content of the system. Average grafted chain lengths were calculated to contain about 1,000 monomer units. (author) 2 figs., 4 refs.

  18. Exponential stretch-rotation (ESR) formulation of general relativity

    CERN Document Server

    Khokhlov, A M

    2003-01-01

    We study a tensorial exponential transformation of a three-dimensional metric of space-like hypersurfaces embedded in a four-dimensional space-time, $\\gamma_{ij} = e^{\\epsilon_{ikm}\\theta_m} e^{\\phi_k} e^{-\\epsilon_{jkn}\\theta_n}$, where $\\phi_k$ are logarithms of the eigenvalues of $\\gamma_{ij}$, $\\theta_k$ are rotation angles, and $\\epsilon_{ijk}$ is a fully anti-symmetric symbol. Evolution part of Einstein's equations, formulated in terms of $\\phi_k$ and $\\theta_k$, describes time evolution of the metric at every point of a hyper-surface as a continuous stretch and rotation of a local coordinate system in a tangential space. The exponential stretch-rotation (ESR) transformation generalizes particular exponential transformations used previously in cases of spatial symmetry. The ESR 3+1 formulation of Einstein's equations may have certain advantages for long-term stable integration of these equations.

  19. Electronic structure calculations of ESR parameters of melanin units.

    Science.gov (United States)

    Batagin-Neto, Augusto; Bronze-Uhle, Erika Soares; Graeff, Carlos Frederico de Oliveira

    2015-03-21

    Melanins represent an important class of natural pigments present in plants and animals that are currently considered to be promising materials for applications in optic and electronic devices. Despite their interesting properties, some of the basic features of melanins are not satisfactorily understood, including the origin of their intrinsic paramagnetism. A number of experiments have been performed to investigate the electron spin resonance (ESR) response of melanin derivatives, but until now, there has been no consensus regarding the real structure of the paramagnetic centers involved. In this work, we have employed electronic structure calculations to evaluate the ESR parameters of distinct melanin monomers and dimers in order to identify the possible structures associated with unpaired spins in this biopolymer. The g-factors and hyperfine constants of the cationic, anionic and radicalar structures were investigated. The results confirm the existence of at least two distinct paramagnetic centers in melanin structure, identifying the chemical species associated with them and their roles in electrical conductivity.

  20. Usability of tartaric acid in dose measurements: an ESR study

    Science.gov (United States)

    Korkmaz, Güney; Polat, Mustafa; Korkmaz, Mustafa

    2010-03-01

    Unirradiated tartaric acid samples do not exhibit any ESR signal. However, the ESR spectra of irradiated samples contain many resonance signals. The dose-responce curves of the resonance signals, denoted as I 1, I 2, I 3 and I 4 in the present study, were found to increase linearly with the applied radiation dose in the range of 0.04-25 kGy. Adjusting the microvawe power and modulation amplitudes of 1.0 mW and 1.0 mT, respectively, was found to increase the sensitivity of tartaric acid. From the dose-response curves and room temperature decay data, it was concluded that the I 3 resonance signal of tartaric acid can be used for dose measurements at intermediate (0.04-0.4 kGy) and high dose (0.5-25 kGy) levels.

  1. ESR dating of teeth from northeastern Brazilian megafauna

    Energy Technology Data Exchange (ETDEWEB)

    Kinoshita, Angela [Departamento de Fisica e Matematica, FFCLRP, Universidade de Sao Paulo, 14040-901 Ribeirao Preto-SP (Brazil); Universidade Sagrado Coracao, 17011-160 Bauru-SP (Brazil); Barreto, Alcina; Alves, Rosenberg [Universidade Federal de Pernambuco, Recife-PE (Brazil); Maria Figueiredo, Ana; Eduardo de Souza Sarkis, Jorge; Dias, Marcelo L. [Instituto de Pesquisas Energeticas e Nucleares (IPEN), 05422-970 Sao Paulo-SP (Brazil); Baffa, Oswaldo [Departamento de Fisica e Matematica, FFCLRP, Universidade de Sao Paulo, 14040-901 Ribeirao Preto-SP (Brazil)], E-mail: baffa@ffclrp.usp.br

    2008-02-15

    Two Stegomastodon waringi teeth from Brazilian northeastern megafauna were dated by electron spin resonance (ESR) spectroscopy. The samples were collected in Pernambuco state, Brazil. The dating of these samples will contribute to the better knowledge of megafauna presence in this region as well as to the events associated to the extinction of these species. Additive dose method was used to evaluate the archeological dose (AD) and a non-linear relation between ESR signal amplitude and dose was obtained. The AD obtained by the exponential fitting was 120{+-}1 and 112{+-}1Gy, leading to an estimation of an age of 63{+-}8 and 60{+-}9ky for radioisotope early uptake model, 64{+-}8 and 60{+-}9ky for linear uptake and 60{+-}9ky for a combination of uptake processes.

  2. Experimental Progress in Fast Cooling in the ESR

    CERN Document Server

    Steck, Markus; Beller, Peter; Franzke, Bernhard; Nolden, Fritz

    2005-01-01

    The ESR storage ring at GSI is operated with highly charged heavy ions. Due to the high electric charge the ions interact much stronger with electromagnetic fields. Therefore both cooling methods which are applied to stored ions in the ESR, stochastic cooling and electron cooling, are more powerful than for singly charged particles. The experimental results exhibit cooling times for stochastic cooling of a few seconds. For cold ion beams, electron cooling provides cooling times which are one to two orders of magnitude smaller. The beams are cooled to beam parameters which are limited by intrabeam scattering. At small ion numbers, however, intrabeam scattering is suppressed by electron cooling, clear evidence was found that the ion beam forms a one-dimensional ordered structure, a linear chain of ions. The strengths of stochastic cooling and electron cooling are complementary and can be combined favorably. Stochastic cooling is employed for pre-cooling of hot secondary beams followed by electron cooling to pro...

  3. ESR detection procedure of irradiated papaya containing high water content

    Science.gov (United States)

    Kikuchi, Masahiro; Shimoyama, Yuhei; Ukai, Mitsuko; Kobayashi, Yasuhiko

    2011-05-01

    ESR signals were recorded from irradiated papaya at liquid nitrogen temperature (77 K), and freeze-dried irradiated papaya at room temperature (295 K). Two side peaks from the flesh at the liquid nitrogen temperature indicated a linear dose response for 3-14 days after the γ-irradiation. The line shapes recorded from the freeze-dried specimens were sharper than those at liquid nitrogen temperature.

  4. ESR detection procedure of irradiated papaya containing high water content

    Energy Technology Data Exchange (ETDEWEB)

    Kikuchi, Masahiro, E-mail: kikuchi.masahiro@jaea.go.j [Quantum Beam Science Directorate, Japan Atomic Energy Agency, 1233 Watanuki-machi, Takasaki, Gunma 370-1292 (Japan); Shimoyama, Yuhei [Quantum Beam Science Directorate, Japan Atomic Energy Agency, 1233 Watanuki-machi, Takasaki, Gunma 370-1292 (Japan); Ukai, Mitsuko [Hokkaido University of Education, 1-2 Hachiman-cho, Hakodate, Hokkaido 040-8567 (Japan); Kobayashi, Yasuhiko [Quantum Beam Science Directorate, Japan Atomic Energy Agency, 1233 Watanuki-machi, Takasaki, Gunma 370-1292 (Japan)

    2011-05-15

    ESR signals were recorded from irradiated papaya at liquid nitrogen temperature (77 K), and freeze-dried irradiated papaya at room temperature (295 K). Two side peaks from the flesh at the liquid nitrogen temperature indicated a linear dose response for 3-14 days after the {gamma}-irradiation. The line shapes recorded from the freeze-dried specimens were sharper than those at liquid nitrogen temperature.

  5. Tenth-Order QED Contribution to the Electron g-2 and an Improved Value of the Fine Structure Constant

    CERN Document Server

    Aoyama, Tatsumi; Kinoshita, Toichiro; Nio, Makiko

    2012-01-01

    This paper presents the complete QED contribution to the electron g-2 up to the tenth order. With the help of the automatic code generator, we have evaluated all 12672 diagrams of the tenth-order diagrams and obtained a_e^{(10)} = 9.16 (58) in units of (\\alpha/\\pi)^5. We have also improved the eighth-order contribution obtaining a_e^{(8)} = -1.9097 (20) in units of (\\alpha/\\pi)^4, which includes the mass-dependent contributions. These results together with the measurement of a_e lead to the improved value of the fine-structure constant \\alpha^{-1} = 137.035 999 166 (34) [0.25 ppb].

  6. 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.

  7. 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

    2016-08-05

    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.

  8. Constraining possible variations of the fine structure constant in strong gravitational fields with the K$\\alpha$ iron line

    CERN Document Server

    Bambi, Cosimo

    2013-01-01

    Extensions of general relativity and theories aiming at unifying gravity with the forces of the Standard Model are usually characterized by new degrees of freedom and violations of the Einstein Equivalence Principle. The search for time and/or space variations of fundamental parameters like the fine structure constant $\\alpha$ tests the assumption of Local Position Invariance. In this letter, I show that the analysis of the K$\\alpha$ iron line observed in the X-ray spectrum of black holes can probe $\\alpha$ in gravitational potentials relative to Earth of $\\Delta \\phi \\approx 0.1$. From the measurements of the black hole in Cygnus X-1 reported in the literature, one obtains $|\\Delta \\alpha / \\alpha| \\lesssim 0.01$.

  9. Quantum beats and fine structure in atto-second chronoscopy of strong-field photoionization of atoms

    Energy Technology Data Exchange (ETDEWEB)

    Kazansky, A.K. [Sankt Petersburg State Univ., 1 Fock Institute of Physics (Russian Federation); Donostia International Physics Center, San Sebastian/Donostia, Basque Country (Spain); Kabachnik, N.M. [Bielefeld Univ., Fakultat fur Physik (Germany); Kabachnik, N.M.; Sazhina, I.P. [Moscow State Univ., Institute of Nuclear Physics (Russian Federation)

    2008-04-15

    A theoretical model is presented which describes the time evolution of strong-field photoionization as studied in recent extreme ultraviolet (XUV) pump-IR probe atto-second tunneling (atto-second chronoscopy) experiments. The excitation of intermediate weakly bound states by an ultra-short XUV pulse (pump) is described within a sudden approximation. The photoionization of these states by a delayed strong IR pulse (probe) is described by solving the non-stationary Schroedinger equation. The results of the calculations show that the coherence of the excited states plays an important role resulting in quantum beats when the XUV pulse precedes the IR pulse. For a large overlap of the pulses a pronounced fine structure in the cross-section is revealed. The calculations for Ne agree qualitatively with the experiment. (authors)

  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.

    2016-08-01

    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.

  11. Boron carbide: Consistency of components, lattice parameters, fine structure and chemical composition makes the complex structure reasonable

    Science.gov (United States)

    Werheit, Helmut

    2016-10-01

    The complex, highly distorted structure of boron carbide is composed of B12 and B11C icosahedra and CBC, CBB and B□B linear elements, whose concentration depends on the chemical composition each. These concentrations are shown to be consistent with lattice parameters, fine structure data and chemical composition. The respective impacts on lattice parameters are estimated and discussed. Considering the contributions of the different structural components to the energy of the overall structure makes the structure and its variation within the homogeneity range reasonable; in particular that of B4.3C representing the carbon-rich limit of the homogeneity range. Replacing in B4.3C virtually the B□B components by CBC yields the hypothetical moderately distorted B4.0C (structure formula (B11C)CBC). The reduction of lattice parameters related is compatible with recently reported uncommonly prepared single crystals, whose compositions deviate from B4.3C.

  12. Tuning exciton energy and fine-structure splitting in single InAs quantum dots by applying uniaxial stress

    Energy Technology Data Exchange (ETDEWEB)

    Su, Dan; Dou, Xiuming; Wu, Xuefei; Liao, Yongping; Zhou, Pengyu; Ding, Kun; Ni, Haiqiao; Niu, Zhichuan; Zhu, Haijun; Jiang, Desheng; Sun, Baoquan, E-mail: bqsun@semi.ac.cn [State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China)

    2016-04-15

    Exciton and biexciton emission energies as well as excitonic fine-structure splitting (FSS) in single InAs/GaAs quantum dots (QDs) have been continuously tuned in situ in an optical cryostat using a developed uniaxial stress device. With increasing tensile stress, the red shift of excitonic emission is up to 5 nm; FSS decreases firstly and then increases monotonically, reaching a minimum value of approximately 10 μeV; biexciton binding energy decreases from 460 to 106 μeV. This technique provides a simple and convenient means to tune QD structural symmetry, exciton energy and biexciton binding energy and can be used for generating entangled and indistinguishable photons.

  13. Artificial intelligence applied to the automatic analysis of absorption spectra. Objective measurement of the fine structure constant

    CERN Document Server

    Bainbridge, Matthew B

    2016-01-01

    A new and fully-automated method is presented for the analysis of high-resolution absorption spectra (GVPFIT). The method has broad application but here we apply it specifically to the problem of measuring the fine structure constant at high redshift. For this we need objectivity and reproducibility. GVPFIT is also motivated by the importance of obtaining a large statistical sample of measurements of $\\Delta\\alpha/\\alpha$. Interactive analyses are both time consuming and complex and automation makes obtaining a large sample feasible. Three numerical methods are unified into one artificial intelligence process: a genetic algorithm that emulates the Darwinian processes of reproduction, mutation and selection, non-linear least-squares with parameter constraints (VPFIT), and Bayesian model averaging. In contrast to previous methodologies, which relied on a particular solution as being the most likely model, GVPFIT plus Bayesian model averaging derives results from a large set of models, and helps overcome systema...

  14. 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.

  15. The influence of age and high-frequency hearing loss on sensitivity to temporal fine structure at low frequencies (L).

    Science.gov (United States)

    Moore, Brian C J; Glasberg, Brian R; Stoev, Martin; Füllgrabe, Christian; Hopkins, Kathryn

    2012-02-01

    Sensitivity to temporal fine structure (TFS) at low frequencies may be adversely affected by hearing loss at high frequencies even when absolute thresholds at low frequencies are within the normal range. However, in several studies suggesting this, the effects of hearing loss and age were confounded. Here, interaural phase discrimination (IPD) thresholds for pure tones at 500 and 750 Hz were measured for 39 subjects with ages from 61 to 83 yr. All subjects had near-normal audiometric thresholds at low frequencies, but thresholds varied across subjects at high frequencies. IPD thresholds were correlated with age. IPD thresholds for the test frequency of 750 Hz were weakly correlated with absolute thresholds at high frequencies, but these correlations became non-significant when the effect of age was partialed out. The results do not confirm that sensitivity to TFS at low frequencies is influenced by hearing loss at high frequencies, independently of age.

  16. Zinc cysteine active sites of metalloproteins: A density functional theory and x-ray absorption fine structure study

    Science.gov (United States)

    Dimakis, Nicholas; Farooqi, Mohammed Junaid; Garza, Emily Sofia; Bunker, Grant

    2008-03-01

    Density functional theory (DFT) and x-ray absorption fine structure (XAFS) spectroscopy are complementary tools for the biophysical study of active sites in metalloproteins. DFT is used to compute XAFS multiple scattering Debye Waller factors, which are then employed in genetic algorithm-based fitting process to obtain a global fit to the XAFS in the space of fitting parameters. Zn-Cys sites, which serve important functions as transcriptional switches in Zn finger proteins and matrix metalloproteinases, previously have proven intractable by this method; here these limitations are removed. In this work we evaluate optimal DFT nonlocal functionals and basis sets for determining optimal geometries and vibrational densities of states of mixed ligation Zn(His)4-n(Cys)n sites. Theoretical results are compared to experimental XAFS measurements and Raman spectra from the literature and tabulated for use.

  17. Near Edge X-Ray Absorption Fine Structure Spectroscopy with X-Ray Free-Electron Lasers

    Energy Technology Data Exchange (ETDEWEB)

    Bernstein, D.P.; Acremann, Y.; Scherz, A.; Burkhardt, M.; Stohr, J.; /SLAC; Beye, M.; Schlotter, W.F.; Beeck, T.; Sorgenfrei, F.; Pietzsch, A.; Wurth, W.; Fohlisch, A.; /Hamburg U.

    2009-12-11

    We demonstrate the feasibility of Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy on solids by means of femtosecond soft x-ray pulses from a free-electron laser (FEL). Our experiments, carried out at the Free-Electron Laser at Hamburg (FLASH), used a special sample geometry, spectrographic energy dispersion, single shot position-sensitive detection and a data normalization procedure that eliminates the severe fluctuations of the incident intensity in space and photon energy. As an example we recorded the {sup 3}D{sub 1} N{sub 4,5}-edge absorption resonance of La{sup 3+}-ions in LaMnO{sub 3}. Our study opens the door for x-ray absorption measurements on future x-ray FEL facilities.

  18. The fine-structure constant a new observational limit on its cosmological variation and some theoretical consequences

    CERN Document Server

    Ivanchik, A V; Varshalovich, D A

    1999-01-01

    Endeavours of the unification of the four fundamental interactions have resulted in a development of theories having cosmological solutions in which low-energy limits of fundamental physical constants vary with time. The validity of such theoretical models should be checked by comparison of the theoretical predictions with observational and experimental bounds on possible time-dependences of the fundamental constants. Based on high-resolution measurements of quasar spectra, we obtain the following direct limits on the average rate of the cosmological time variation of the fine-structure constant limit, and |\\dot{\\alpha}/\\alpha| < 3.1 \\times 10^{-14} yr^{-1} is the most conservative limit. Analogous estimates published previously, as well as other contemporary tests for possible variations of \\alpha (those based on the "Oklo phenomenon", on the primordial nucleosynthesis models, and others) are discussed and compared with the present upper limit. We argue that the present result is the most conservative one...

  19. Near-edge X-ray absorption fine structure spectroscopy-assisted purification of single-walled carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Yan Dongwei [Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080 (China); Zhong Jun [Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Wang Chunru [Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080 (China)], E-mail: crwang@iccas.ac.cn; Wu Ziyu [Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China)], E-mail: wuzy@ihep.ac.cn

    2007-07-15

    Single-walled carbon nanotubes were produced by the conventional arc discharge method, and purified with a two-step treatment. First, the raw soot containing single-walled carbon nanotubes was burned up at ca. 350 deg. C in air to remove amorphous carbon, and then it was treated by strong acidic solvents to remove metal catalysts. Near-edge X-ray absorption fine structure spectroscopy was applied to analyze the defects on single-walled carbon nanotubes in whole purification process, so the experimental conditions can be optimized, and finally high-purity single-walled carbon nanotubes were obtained as revealed by various spectroscopic characterizations such as scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, and Raman spectroscopy.

  20. Zinc cysteine active sites of metalloproteins: a density functional theory and x-ray absorption fine structure study.

    Science.gov (United States)

    Dimakis, Nicholas; Farooqi, Mohammed Junaid; Garza, Emily Sofia; Bunker, Grant

    2008-03-21

    Density functional theory (DFT) and x-ray absorption fine structure (XAFS) spectroscopy are complementary tools for the biophysical study of active sites in metalloproteins. DFT is used to compute XAFS multiple scattering Debye Waller factors, which are then employed in genetic algorithm-based fitting process to obtain a global fit to the XAFS in the space of fitting parameters. Zn-Cys sites, which serve important functions as transcriptional switches in Zn finger proteins and matrix metalloproteinases, previously have proven intractable by this method; here these limitations are removed. In this work we evaluate optimal DFT nonlocal functionals and basis sets for determining optimal geometries and vibrational densities of states of mixed ligation Zn(His)(4-n)(Cys)(n) sites. Theoretical results are compared to experimental XAFS measurements and Raman spectra from the literature and tabulated for use.

  1. Extended x-ray absorption fine structure spectroscopy in Co{sub 0.013}NbSe{sub 2}.

    Energy Technology Data Exchange (ETDEWEB)

    Weber, F.; Castellan, J.-P.; Rosenkranz, S.; Osborn, R.; Rosenmann, D.; Iavarone, M.; Materials Science Division

    2010-01-01

    We present a study of the local environment of the Co atom in single crystalline Co{sub x}NbSe{sub 2}, x = 0.013, via Extended X-ray Absorption Fine Structure (EXAFS) measurements at the Co K-edge (7.7 keV) at various temperatures. Co intercalation quickly suppresses superconductivity and the charge-density wave (CDW) present in pure NbSe{sub 2}. In order to study the effect of impurities on superconducting and CDW states one has to verify the random distribution of the intercalated atoms in contrast to possible clustering which could lead to additional, e.g. magnetic, interactions in the case of Co intercalation. Our measurements show that the Co atoms are indeed randomly distributed in Co{sub 0.013}NbSe{sub 2}.

  2. Extended X-ray Absorption Fine Structure spectroscopy in Co{sub 0.013}NbSe{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Weber, F; Castellan, J-P; Rosenkranz, S; Osborn, R; Rosenmann, D; Iavarone, M, E-mail: fweber@anl.go [Materials Science Division, Argonne National Laboratory, Argonne, Illinois (United States)

    2010-01-15

    We present a study of the local environment of the Co atom in single crystalline Co{sub x}NbSe{sub 2}, x = 0.013, via Extended X-ray Absorption Fine Structure (EXAFS) measurements at the Co K-edge (7.7 keV) at various temperatures. Co intercalation quickly suppresses superconductivity and the charge-density wave (CDW) present in pure NbSe{sub 2}. In order to study the effect of impurities on superconducting and CDW states one has to verify the random distribution of the intercalated atoms in contrast to possible clustering which could lead to additional, e.g. magnetic, interactions in the case of Co intercalation. Our measurements show that the Co atoms are indeed randomly distributed in Co{sub 0.013}NbSe{sub 2}.

  3. Fine structure of the sensilla and immunolocalisation of odorant binding proteins in the cerci of the migratory locust, Locusta migratoria.

    Science.gov (United States)

    Yu, Yanxue; Zhou, Shuhui; Zhang, Shangan; Zhang, Long

    2011-01-01

    Using light and electron microscopy (both scanning and transmission), we observed the presence of sensilla chaetica and hairs on the cerci of the migratory locust, Locusta migratoria L. (Orthoptera: Acrididae). Based on their fine structures, three types of sensilla chaetica were identified: long, medium, and short. Males presented significantly more numbers of medium and short sensilla chaetica than females (pmigratoria (LmigOBP2) and chemosensory protein class I from the desert locust, Schistocerca gregaria Forsskål (SgreCSPI) strongly stained the outer lymph of sensilla chaetica of the cerci. The other two types of hairs were never labeled. The results indicate that the cerci might be involved in contact chemoreception processes.

  4. Attempts at a determination of the fine-structure constant from first principles: A brief historical overview

    CERN Document Server

    Jentschura, U D

    2014-01-01

    It has been a notably elusive task to find a remotely sensical ansatz for a calculation of Sommerfeld's electrodynamic fine-structure constant alpha_QED ~ 1/137.036 based on first principles. However, this has not prevented a number of researchers to invest considerable effort into the problem, despite the formidable challenges, and a number of attempts have been recorded in the literature. Here, we review a possible approach based on the quantum electrodynamic (QED) beta function, and on algebraic identities relating alpha_QED to invariant properties of "internal" symmetry groups, as well as attempts to relate the strength of the electromagnetic interaction to the natural cut-off scale for other gauge theories. Conjectures based on both classical as well as quantum-field theoretical considerations are discussed. We point out apparent strengths and weaknesses of the most prominent attempts that were recorded in the literature. This includes possible connections to scaling properties of the Einstein-Maxwell La...

  5. Fine structure and Ca-ATPase activity of the stratum intermedium cells during odontogenesis in gars, Lepisosteus, Actinopterygii.

    Science.gov (United States)

    Sasagawa, Ichiro; Ishiyama, Mikio

    2002-01-01

    This is the first report on the stratum intermedium in vertebrates other than mammals. The aim of this study is to elucidate the fine structure and cytochemical features of the stratum intermedium during the stages of enameloid formation in Lepisosteus. Inner dental epithelium, stratum intermedium, stellate reticulum, and outer dental epithelium are consistently present in the tooth germs of Lepisosteus. The stratum intermedium cells are oval in shape, contain elliptical nuclei, and extend many small processes. It is implied that the structure of the enamel organ is different among actinopterygians, and that constitution of the enamel organ in Lepisosteus resembles that in higher vertebrates. Marked Ca-ATPase activity is observed at the cell membrane of the stratum intermedium cells, suggesting that the cells are involved in calcium transport during the stages of enameloid formation.

  6. Analysis of the fine structure of Sn$^{11+...14+}$ ions by optical spectroscopy in an electron beam ion trap

    CERN Document Server

    Windberger, A; Borschevsky, A; Ryabtsev, A; Dobrodey, S; Bekker, H; Eliav, E; Kaldor, U; Ubachs, W; Hoekstra, R; López-Urrutia, J R Crespo; Versolato, O O

    2016-01-01

    We experimentally re-evaluate the fine structure of Sn$^{11+...14+}$ ions. These ions are essential in bright extreme-ultraviolet (EUV) plasma-light sources for next-generation nanolithography, but their complex electronic structure is an open challenge for both theory and experiment. We combine optical spectroscopy of magnetic dipole $M1$ transitions, in a wavelength range covering 260\\,nm to 780\\,nm, with charge-state selective ionization in an electron beam ion trap. Our measurements confirm the predictive power of \\emph{ab initio} calculations based on Fock space coupled cluster theory. We validate our line identification using semi-empirical Cowan calculations with adjustable wavefunction parameters. Available Ritz combinations further strengthen our analysis. Comparison with previous work suggests that line identifications in the EUV need to be revisited.

  7. Fine-structure electron-impact excitation of Ne+ and Ne2+ for low temperature astrophysical plasmas

    CERN Document Server

    Wang, Qianxia; Li, Y; Pindzola, M S; Cumbee, R; Stancil, P; McLaughlin, B; Ballance, C P

    2016-01-01

    Collision strengths for electron-impact of fine-structure level excitation within the ground term of Ne+ and Ne2+ are calculated using the Breit-Pauli, Intermediate Coupling Frame Transformation, and DARC R-matrix methods. Maxwellian-averaged effective collision strengths and excitation rate coefficient qij are presented for each. The application of the current calculations is to very low temperature astrophysical plasmas, thus we examine the sensitivity of the effective collision strengths down to 10 K. The use of the various theoretical methods allows us to place estimated uncertainties on the recommended effective collision strengths. We also investigate the sensitivity of the collision strengths to the resonance positions and underlying atomic structure. Good agreement is found with previous R-matrix calculations at higher temperature.

  8. An ESR study on biological dosimeters: Human hair

    Energy Technology Data Exchange (ETDEWEB)

    Colak, Seyda, E-mail: seyda@hacettepe.edu.t [Hacettepe University, Physics Engineering Department, 06800 Ankara (Turkey); Ozbey, Turan [Hacettepe University, Physics Engineering Department, 06800 Ankara (Turkey)

    2011-05-15

    In the present work, characteristic features of the radicals found in untreated, gamma and UV-irradiated and mechanical damaged human hair samples were investigated by ESR spectroscopy. Heights of the resonance peaks measured with respect to the spectrum base line were used to monitor microwave power, dose-response, storage time and temperature dependent kinetic features of the radical species contributing to the formation of recorded experimental ESR spectra. Peak heights and g-values (2.0037-2.0052) determined from recorded spectra of hair were color dependent with {Delta}Hpp-0.47 mT. The act of cutting hair samples gene rates sulfur centered radicals which are found in the a-keratin structure of hair. The variations of the peak heights with temperature were related with the water content found in the hair samples. In the 6-1100 Gy dose range, a linear + quadratic dose-response curve was recorded for hair and the mean radiation yield (G{sub mean}) was calculated to be 0.4. The gamma radiation induced radicals were stable for a several hours at room temperature storage conditions. Based on these findings it was concluded that human hair samples could be used as biological/personnel dosimeters and that ESR spectroscopy could be successfully used as a potential technique for monitoring its dosimetric behaviours.

  9. Magnetic phase coexistence in CMR manganites: ESR evidence

    Energy Technology Data Exchange (ETDEWEB)

    Ccahuana, D. Laura [Instituto Balseiro, Universidad Nacional de Cuyo and Comision Nacional de Energia Atomica and Centro Atomico Bariloche, Comision Nacional de Eenrgia Atomica. Av. Ezequiel Bustillo 9500, 8400 San Carlos de Bariloche, Rio Negro (Argentina)]. E-mail: ccahuana@cab.cnea.gov.ar; Winkler, E. [Instituto Balseiro, Universidad Nacional de Cuyo and Comision Nacional de Energia Atomica and Centro Atomico Bariloche, Comision Nacional de Eenrgia Atomica. Av. Ezequiel Bustillo 9500, 8400 San Carlos de Bariloche, Rio Negro (Argentina); Prado, F. [Instituto Balseiro, Universidad Nacional de Cuyo and Comision Nacional de Energia Atomica and Centro Atomico Bariloche, Comision Nacional de Eenrgia Atomica. Av. Ezequiel Bustillo 9500, 8400 San Carlos de Bariloche, Rio Negro (Argentina); Butera, A. [Instituto Balseiro, Universidad Nacional de Cuyo and Comision Nacional de Energia Atomica and Centro Atomico Bariloche, Comision Nacional de Eenrgia Atomica. Av. Ezequiel Bustillo 9500, 8400 San Carlos de Bariloche, Rio Negro (Argentina); Ramos, C.A. [Instituto Balseiro, Universidad Nacional de Cuyo and Comision Nacional de Energia Atomica and Centro Atomico Bariloche, Comision Nacional de Eenrgia Atomica. Av. Ezequiel Bustillo 9500, 8400 San Carlos de Bariloche, Rio Negro (Argentina); Causa, M.T. [Instituto Balseiro, Universidad Nacional de Cuyo and Comision Nacional de Energia Atomica and Centro Atomico Bariloche, Comision Nacional de Eenrgia Atomica. Av. Ezequiel Bustillo 9500, 8400 San Carlos de Bariloche, Rio Negro (Argentina); Tovar, M. [Instituto Balseiro, Universidad Nacional de Cuyo and Comision Nacional de Energia Atomica and Centro Atomico Bariloche, Comision Nacional de Eenrgia Atomica. Av. Ezequiel Bustillo 9500, 8400 San Carlos de Bariloche, Rio Negro (Argentina)

    2004-12-31

    The coexistence of magnetic phases in colossal magnetoresistant (CMR) manganites is characteristic of this family of compounds. We studied this phenomenon in a hole doped sample of La{sub 0.75}Ca{sub 0.25}MnO{sub 3} by means of magnetization measurements and electron spin resonance (ESR) technique. The magnetic transition at T{sub c}=220 K was determined as the maximum slope in the M(T) curve. Above 250 K the ESR spectrum consists of a single lorentzian line centered at g=1.99(1). The ESR resonance splits below 250 K and a second resonance, of FM character, is present with a T dependent resonance field (H{sub r}). When T decreases, H{sub r} diminishes for the FM line while the PM line remains essentially centered at a constant H{sub r}. At the same time, a continuous transference of intensity takes place, from the PM line to the FM one. We observed the coexistence of both, PM and FM lines, down to 220 K. In this extended range of coexistence (250-220 K) the magnetization shows also a peculiar behavior.

  10. X-ray absorption fine structure spectroscopic determination of plutonium speciation at the Rocky Flats environmental technology

    Energy Technology Data Exchange (ETDEWEB)

    Lezama-pacheco, Juan S [Los Alamos National Laboratory; Conradson, Steven D [Los Alamos National Laboratory; Clark, David L [Los Alamos National Laboratory

    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{sub 2+x}-type speciation. Two were ambiguous, possibly indicating that Pu that was originally present in a different form was transforming into PuO{sub 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{sub 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.

  11. 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.

  12. Effect of Electron Correlations and Breit Interactions on Ground-State Fine-Structures along the Nitrogen-Like Isoelectronic Sequence

    Institute of Scientific and Technical Information of China (English)

    WANG Xiao-Lu; LU Wen-Lai; GAO Xiang; LI Jia-Ming

    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.

  13. Fine structure of histograms of alpha-activity measurements depends on direction of alpha particles flow and the Earth rotation: experiments with collimators

    CERN Document Server

    Shnoll, S E; Berulis, I I; Udaltsova, N V; Rubinstein, I A; Shnoll, Simon E.; Zenchenko, Konstantin I.; Berulis, Iosas I.; Udaltsova, Natalia V.; Rubinstein, Ilia A.

    2004-01-01

    The fine structure of histograms of measurements of 239Pu alpha-activity varies periodically, and the period of these variations is equal to sidereal day (1436 minutes). The periodicity is not observed in the experiments with collimator that restricts the alpha particles flow to be oriented to the Polar Star. Based on this study and other independent data, such as measurements conducted by the Arctic expedition, and similarity of the histograms in processes observed at different locations at the same local time, the conclusion was made, that the fine structure of statistical distributions of the observed processes depends on the celestial sphere.

  14. Recovery of distortion product otoacoustic emissions after a 2-kHz monaural sound-exposure in humans: effects on fine structures

    DEFF Research Database (Denmark)

    de Toro, Miguel Angel Aranda; Ordoñez, Rodrigo Pizarro; Reuter, Karen

    2010-01-01

    A better understanding of the vulnerability of the fine structures of distortion-product otoacoustic emissions (DPOAEs) after acoustic overexposure may improve the knowledge about DPOAE generation, cochlear damage, and lead to more efficient diagnostic tools. It is studied whether the DPOAE fine...... structures of 16 normal-hearing human subjects are systematically affected after a moderate monaural sound-exposure of 10 min to a 2-kHz tone normalized to an exposure level LEX,8h of 80 dBA. DPOAEs were measured before and in the following 70 min after the exposure. The experimental protocol allowed...

  15. Dynamics of flare processes and variety of the fine structure of solar radio emission over a wide frequency range of 30 - 7000 MHz

    CERN Document Server

    Chernov, Gennady; Tan, Baolin; Yan, Yihua; Tan, Chengming; Fu, Qijun

    2014-01-01

    Radiobursts exibiting fine structure observed over two years during the rising phase of Cycle 24 by the SBRS are analyzed. In five events zebra structure, various fiber bursts and fast pulsations were observed. Events on 15 and 24 February 2011 are of the greatest interest. The polarization of radio emission in all three cases is related to the ordinary wave mode of radio emission.Almost all events in the microwave range contain superfine structure. It is possible that each type of fine structure is excited by the same mechanism, and the broad variety of events is related to the dynamics of flare processes.

  16. Intronic SNP in ESR1 encoding human estrogen receptor alpha is associated with brain ESR1 mRNA isoform expression and behavioral traits.

    Science.gov (United States)

    Pinsonneault, Julia K; Frater, John T; Kompa, Benjamin; Mascarenhas, Roshan; Wang, Danxin; Sadee, Wolfgang

    2017-01-01

    Genetic variants of ESR1 have been implicated in multiple diseases, including behavioral disorders, but causative variants remain uncertain. We have searched for regulatory variants affecting ESR1 expression in human brain, measuring allelic ESR1 mRNA expression in human brain tissues with marker SNPs in exon4 representing ESR1-008 (or ESRα-36), and in the 3'UTR of ESR1-203, two main ESR1 isoforms in brain. In prefrontal cortex from subjects with bipolar disorder, schizophrenia, and controls (n = 35 each; Stanley Foundation brain bank), allelic ESR1 mRNA ratios deviated from unity up to tenfold at the exon4 marker SNP, with large allelic ratios observed primarily in bipolar and schizophrenic subjects. SNP scanning and targeted sequencing identified rs2144025, associated with large allelic mRNA ratios (p = 1.6E10-6). Moreover, rs2144025 was significantly associated with ESR1 mRNA levels in the Brain eQTL Almanac and in brain regions in the Genotype-Tissue Expression project. In four GWAS cohorts, rs2104425 was significantly associated with behavioral traits, including: hypomanic episodes in female bipolar disorder subjects (GAIN bipolar disorder study; p = 0.0004), comorbid psychological symptoms in both males and females with attention deficit hyperactivity disorder (GAIN ADHD, p = 0.00002), psychological diagnoses in female children (eMERGE study of childhood health, subject age ≥9, p = 0.0009), and traits in schizophrenia (e.g., grandiose delusions, GAIN schizophrenia, p = 0.0004). The first common ESR1 variant (MAF 12-33% across races) linked to regulatory functions, rs2144025 appears conditionally to affect ESR1 mRNA expression in the brain and modulate traits in behavioral disorders.

  17. X-ray absorption fine structure and X-ray excited optical luminescence studies of II-VI semiconducting nanostructures

    Science.gov (United States)

    Murphy, Michael Wayne

    2010-06-01

    Various II-VI semiconducting nanomaterials such as ZnO-ZnS nanoribbons (NRs), CdSxSe1-x nanostructures, ZnS:Mn NRs, ZnS:Mn,Eu nanoprsims (NPs), ZnO:Mn nanopowders, and ZnO:Co nanopowders were synthesized for study. These materials were characterized by techniques such as scanning electron microscopy, transmission electron microscopy, element dispersive X-ray spectroscopy, selected area electron diffraction, and X-ray diffraction. The electronic and optical properties of these nanomaterials were studied by X-ray absorption fine structure (XAFS) spectroscopy and X-ray excited optical luminescence (XEOL) techniques, using tuneable soft X-rays from a synchrotron light source. The complementary nature ofthe XAFS and XEOL techniques give site, element and chemical specific measurements which allow a better understanding of the interplay and role of each element in the system. Chemical vapour deposition (CVD) of ZnS powder in a limited oxygen environment resulted in side-by-side biaxial ZnO-ZnS NR heterostructures. The resulting NRs contained distinct wurtzite ZnS and wurtzite ZnO components with widths of 10--100 nm and 20 --500 nm, respectively and a uniform interface region of 5-15 nm. XAFS and XEOL measurements revealed the luminescence of ZnO-ZnS NRs is from the ZnO component. The luminescence of CdSxSe1-x nanostructures is shown to be dependent on the S to Se ratio, with the band-gap emission being tunable between that of pure CdS and CdSe. Excitation of the CdSxSe 1-x nanostructures by X-ray in XEOL has revealed new de-excitation channels which show a defect emission band not seen by laser excitation. CVD of Mn2+ doped ZnS results in nanostructures with luminescence dominated by the yellow Mn2+ emission due to energy transfer from the ZnS host to the Mn dopant sites. The addition of EuCl3 to the reactants in the CVD process results in a change in morphology from NR to NP. Zn1-xMnxO and Zn1-xCOxO nanopowders were prepared by sol-gel methods at dopant concentrations

  18. Sulfur X-ray absorption fine structure in porous Li–S cathode films measured under argon atmospheric conditions

    Energy Technology Data Exchange (ETDEWEB)

    Müller, Matthias, E-mail: matthias.mueller@ptb.de [Physikalisch-Technische Bundesanstalt, Abbestr. 2-12, 10587 Berlin (Germany); Choudhury, Soumyadip [Leibniz-Institut für Polymerforschung, Hohe Strasse 6, 01069 Dresden (Germany); Technische Universität Dresden, Physical Chemistry of Polymeric Materials ,01062 Dresden (Germany); Gruber, Katharina [VARTA Micro Innovation GmbH, Stremayrgasse 9, 8010 Graz (Austria); Cruz, Valene B. [Universität Ulm, Institut für Elektrochemie, 89069 Ulm (Germany); Helmholtz-Institut Ulm (HIU), 89069 Ulm (Germany); Fuchsbichler, Bernd [VARTA Micro Innovation GmbH, Stremayrgasse 9, 8010 Graz (Austria); Jacob, Timo [Universität Ulm, Institut für Elektrochemie, 89069 Ulm (Germany); Helmholtz-Institut Ulm (HIU), 89069 Ulm (Germany); Koller, Stefan [VARTA Micro Innovation GmbH, Stremayrgasse 9, 8010 Graz (Austria); Stamm, Manfred [Leibniz-Institut für Polymerforschung, Hohe Strasse 6, 01069 Dresden (Germany); Technische Universität Dresden, Physical Chemistry of Polymeric Materials ,01062 Dresden (Germany); Ionov, Leonid [Leibniz-Institut für Polymerforschung, Hohe Strasse 6, 01069 Dresden (Germany); Beckhoff, Burkhard [Physikalisch-Technische Bundesanstalt, Abbestr. 2-12, 10587 Berlin (Germany)

    2014-04-01

    In this paper we present the first results for the characterization of highly porous cathode materials with pore sizes below 1 μm for Lithium Sulfur (Li–S) batteries by Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy. A novel cathode material of porous carbon films fabricated with colloidal array templates has been investigated. In addition, an electrochemical characterization has been performed aiming on an improved correlation of physical and chemical parameters with the electrochemical performance. The performed NEXAFS measurements of cathode materials allowed for a chemical speciation of the sulfur content inside the cathode material. The aim of the presented investigation was to evaluate the potential of the NEXAFS technique to characterize sulfur in novel battery material. The long term goal for the characterization of the battery materials is the sensitive identification of undesired side reactions, such as the polysulfide shuttle, which takes place during charging and discharging of the battery. The main drawback associated with the investigation of these materials is the fact that NEXAFS measurements can usually only be performed ex situ due to the limited in situ instrumentation being available. For Li–S batteries this problem is more pronounced because of the low photon energies needed to study the sulfur K absorption edge at 2472 eV. We employed 1 μm thick Si{sub 3}N{sub 4} windows to construct sealed argon cells for NEXAFS measurements under ultra high vacuum (UHV) conditions as a first step towards in situ measurements. The cells keep the sample under argon atmosphere at any time and the X-ray beam passes mainly through vacuum which enables the detection of the low energy X-ray emission of sulfur. Using these argon cells we found indications for the presence of lithium polysulfides in the cathode films whereas the correlations to the offline electrochemical results remain somewhat ambiguous. As a consequence of these findings one

  19. Comparison of the DAS28-CRP and DAS28-ESR in patients with rheumatoid arthritis.

    Science.gov (United States)

    Sengul, Ilker; Akcay-Yalbuzdag, Seniz; Ince, Bugra; Goksel-Karatepe, Altinay; Kaya, Taciser

    2015-07-01

    To compare the Disease Activity Score with 28 joint (DAS28) using erythrocyte sedimentation rate (ESR) (DAS28-ESR) and DAS28 using C-reactive protein (CRP) (DAS28-CRP) with thresholds validated for DAS28-ESR in Turkish patients with rheumatoid arthritis. The DAS28 data of 112 patients with rheumatoid arthritis followed in a local outpatient clinic were used. First, the correlation between DAS28-CRP and DAS28-ESR and the correlation between their unique components ([0.36 × In (CRP + 1) + 0.96] and [0.70 × In (ESR)]) were analyzed. Second, a Bland-Altman plot was constructed for the evaluation of the level of agreement between DAS28-CRP and DAS28-ESR. Lastly, the agreement between these two methods was analyzed by κ coefficient. Although there was a strong correlation between DAS28-CRP and DAS28-ESR, the correlation between their unique components was fair. Although more than 95% of the point data fall between the upper and lower bounds of the limit of agreement, the percentage error (46%) was higher than the acceptable proportion of 30%. The κ coefficient of agreement between DAS28- ESR and DAS28-CRP with validated thresholds for DAS28-ESR was 0.42, which was close to the lower boundary for moderate agreement. The results of this study demonstrated that there is discordance between DAS28-ESR and DAS28-CRP with the validated thresholds for DAS28-ESR. Using the DAS28-CRP with threshold values validated for DAS28-ESR may lead to errors in the determination of disease activity and therefore may lead to errors in the management of patients with rheumatoid arthritis. © 2015 Asia Pacific League of Associations for Rheumatology and Wiley Publishing Asia Pty Ltd.

  20. File list: Oth.Oth.05.ESR1.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.Oth.05.ESR1.AllCell hg19 TFs and others ESR1 Others SRX371435,SRX371448,SRX3714...1434,SRX371427,SRX371443,SRX371442,SRX371444,SRX371439,SRX371436,SRX371428,SRX371449,SRX371445 http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Oth.Oth.05.ESR1.AllCell.bed ...