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1

Relativistically parametrized extended Hueckel calculations. 11. Energy bands for elemental tellurium and polonium  

Energy Technology Data Exchange (ETDEWEB)

An extension of the REX relativistically parametrized extended Hueckel LCAO molecular orbital method to periodic solids is outlined. The method provides a simple and systematic approach to the description of the spin-orbit splitting of energy bands. The method is illustrated with results for the main-group elements tellurium and polonium, with trigonal-helical and simple-cubic structures, respectively. The helical structure of tellurium is described as a distortion of a simple-cubic structure, with the distortion being quenched in the case of polonium by its very large spin-orbit coupling. 36 references, 10 figures, 1 table.

Lohr, L.L.

1987-06-17

2

Relativistically parameterized extended Hueckel calculations. 3. Structure and bonding for some compounds of uranium and other heavy elements  

Energy Technology Data Exchange (ETDEWEB)

The relativistically parameterized extended Hueckel molecular orbital method REX is used to explore the effects of relativity upon molecular orbital energies and compositions. The uranium compounds studied are UO/sub 2//sup 2 +/, UO/sub 2/Cl/sub 4//sup 2 -/, UF/sub 6/, UCl/sub 6/, UCl/sub 4/, U(BH/sub 4/)/sub 4/, and U(C/sub 8/H/sub 8/)/sub 2/. Other heavy element compounds studied are MI/sub 3/ (M = La, Gd, Lu), PoH/sub 2/, (eka)PoH/sub 2/, I/sub 3//sup -/, AtI/sub 2//sup -/, and RnF/sub 2/. Relativistic orbital energy parameters and atomic orbital exponents are presented as supplementary material for all elements with Z = 1 to 120 together with corresponding nonrelativistic values for all elements with Z = 1 to 100. It is concluded that the REX method provides semiquantitative estimates of spin-orbit splittings and relativistic bonding effects for compounds of heavy elements.

Pyykkoe, P. (Aabo Akademi, Tarku, Finland); Lohr, L.L. Jr.

1981-07-01

3

Magnetoresistance in pulsed fields, band structure calculations and charge-density wave instability in (TSeT){sub 2}Cl  

Energy Technology Data Exchange (ETDEWEB)

Diffuse X-rays measurements assign the 26 K metal-semimetal transition in (TSeT){sub 2}Cl, where TSeT = tetraselenotetracene, to the stabilization of a 2k{sub F}=c{sup *}/4 charge-density wave ground state. Tight-binding extended Hueckel band calculations suggest that 2k{sub F} yields to a partial nesting of the four conduction bands. Transverse magnetoresistance experiments performed up to 37 T confirm the previous observation of SdH oscillations. The 0{sup +} Landau level is evidenced for the first time. (orig.)

Goze, F. [Lab. de Physique des Solides et Service National des Champs Magnetiques Pulses du CNRS, 31 Toulouse (France); Audouard, A. [Lab. de Physique des Solides et Service National des Champs Magnetiques Pulses du CNRS, 31 Toulouse (France); Brossard, L. [Lab. de Physique des Solides et Service National des Champs Magnetiques Pulses du CNRS, 31 Toulouse (France); Laukhin, V.N. [Lab. de Physique des Solides et Service National des Champs Magnetiques Pulses du CNRS, 31 Toulouse (France)]|[Inst. of Chemical Physics, Chernogolovka (Russian Federation); Ulmet, J.P. [Lab. de Physique des Solides et Service National des Champs Magnetiques Pulses du CNRS, 31 Toulouse (France); Doublet, M.L. [Lab. de Chimie Theorique, Univ. Paris-Sud, 91 Orsay (France); Canadell, E. [Lab. de Chimie Theorique, Univ. Paris-Sud, 91 Orsay (France); Pouget, J.P. [Lab. de Physique des Solides, Univ. Paris-Sud, 91 Orsay (France); Zavodnik, V.E. [Karpov`s Physics and Chemistry Inst., Moscow (Russian Federation); Shibaeva, R.P. [Inst. of Solid State Physics, Chernogolovka (Russian Federation); Hilti, B. [Central Research Lab., Basel (Switzerland); Mayer, C.W. [Central Research Lab., Basel (Switzerland)

1995-03-15

4

Calculations of laser dye absorption band shape  

International Nuclear Information System (INIS)

Brilliant green molecule vibrational frequencies were determined by calculation its Hessian matrix. Calculated absorption band of the molecule was compared with spectral ellipsometry experimental data. The band shape was treated in frames of ? conjugated chain model. Numerical simulation with complete active space approach confirmed the presence of the chain in the molecule.

2009-01-01

5

Ab initio electronic band structure calculations for calcium monochalcogenides  

Energy Technology Data Exchange (ETDEWEB)

The first principles tight-binding linear muffin-tin orbital method within the local density approximation was used to calculate the electronic band structures and the total energies of CaS, CaSe and CaTe in NaCl-type and CsCl-type structures. The total energies were used to calculate the ground state properties such as lattice parameter, bulk modulus and the structural phase stability of these compounds. The transition pressure at which these compounds undergo the structural phase transition from NaCl-type to CsCl-type structure was calculated. The ground state properties, the transition pressures and the transition volumes are found to agree with the experimental and other theoretical results. The energy band gap at ambient condition in the NaCl-type structure were calculated and compared with the experimental results available for CaS and CaSe. For CaTe the experimental values of energy gap are not available. The valence-band width and the pressure coefficient of energy gap were also calculated. The closure of band gap at transition in CaCl structure for CaSe, and CaTe were explained by comparing the band structures of BaSe and SrSe in this phase.

Banu, I.B.S.; Kalpana, G.; Palanivel, B.; Shenbagaraman, P. [Crescent Engineering Coll., Vandahur (India). Dept. of Physics; Rajagopalan, M. [Anna Univ., Chenni (India). Dept. of Physics; Yousuf, M. [IGCAR, Kalpakkam (India)

1998-07-10

6

Neutrino flux calculations for the AGS narrow band beam  

International Nuclear Information System (INIS)

[en] Presented are results of calculations of nu/sub ?/ fluxes in the AGS neutrino beam with the new dichromatic horn. The wide band beam nu/sub ?/, as well as the nu/sub e/ backgrounds, are discussed. The nu/sub e//nu/sub ?/ ratio is about 8 x 10-3. The possible sources and magnitudes of uncertainties are discussed. Finally, the calculated fluxes are compared with beam measurements

1987-01-01

7

Calculation of the band gap energy of ionic crystals  

Energy Technology Data Exchange (ETDEWEB)

The band gap of alkali halides, alkaline-earth oxides, Al{sub 2}O{sub 3} and SiO{sub 2} crystals has been calculated using the perturbed-ion model supplemented with some assumptions for the treatment of excited states. The gap is calculated in several ways: as a difference between one-electron energy eigenvalues and as a difference between the total energies of appropriate electronic states of the crystal, both at the HF level and with inclusion of Coulomb correlation effects. The results compare well with experimental band gap energies and with other theoretical calculations, suggesting that the picture of bonding and excitation given by the model can be useful in ionic materials. (Author)

Aguado, A.; Lopez, J.M.; Alonso, J.A. [Departamento de Fisica Teorica, Facultad de Ciencias, Universidad de Valladolid, 47011, Valladolid (Spain); Ayuela, A. [Institut fur Theoretische Physik, Technische Universitat Dresden, 01062 Dresden (Germany); Rivas S, J.F. [Instituto de Fisica, Universidad Autonoma de Puebla, 72750 Puebla (Mexico); Berrondo, M. [Brigham Young University, Provo, UT84602 (United States)

1998-12-31

8

Calculation of the Band Gap Energy of Ionic Crystals  

CERN Multimedia

The band gap of alkali halides, alkaline-earth oxides, Al2O3 and SiO2 crystals has been calculated using the Perturbed-Ion model supplemented with some assumptions for the treatment of excited states. The gap is calculated in several ways: as a difference between one-electron energy eigenvalues and as a difference between the total energies of appropriate electronic states of the crystal, both at the HF level and with inclusion of Coulomb correlation effects. The results compare well with experimental band gap energies and with other theoretical calculations, suggesting that the picture of bonding and excitation given by the model can be useful in ionic materials.

Aguado, A; López, J M; Rivas-Silva, J F; Berrondo, M; Alonso, J A

1998-01-01

9

Calculation of the band gap energy of ionic crystals  

International Nuclear Information System (INIS)

[en] The band gap of alkali halides, alkaline-earth oxides, Al2O3 and SiO2 crystals has been calculated using the perturbed-ion model supplemented with some assumptions for the treatment of excited states. The gap is calculated in several ways: as a difference between one-electron energy eigenvalues and as a difference between the total energies of appropriate electronic states of the crystal, both at the HF level and with inclusion of Coulomb correlation effects. The results compare well with experimental band gap energies and with other theoretical calculations, suggesting that the picture of bonding and excitation given by the model can be useful in ionic materials. (Author)

1998-01-01

10

Relativistic Band Calculation and the Optical Properties of Gold  

DEFF Research Database (Denmark)

The energy band structure of gold is calculated by the relativistic augmented-plane-wave (RAPW) method. A nonrelativistic calculation is also presented, and a comparison between this and the RAPW results demonstrates that the shifts and splittings due to relativistic effects are of the same order of magnitude as the gaps (approximately 1 eV). Various integrated functions, density of states, joint density of states, and energy distributions of joint density of states are derived from the RAPW calculation. These functions are used in an interpretation of photoemission and static reflectance measurements. It is shown that the photoemission results are extremely well described in terms of a model assuming all transitions to be direct whereas a nondirect model fails. The ?2 profile calculated in a crude model assuming constant matrix elements matches well the corresponding experimental results. The calculated interband edge (??i=2.38 eV) agrees with experimental values, and the absorption tail below the interband edge which is found in experimental traces is also contained in the theoretical curve. By means of a calculation of the Fermi surface and the constant-energy-difference surfaces it has been possible to trace out the regions in k? space where the edge and tail transitions occur. It is demonstrated that structure in the static reflection curves are not related to critical points in the band structure. The arguments are supported by calculations of temperature shifts of the critical-point energies and comparison to the observed temperature shifts of the elements of structure in the experimental ?2 function. Such structure may originate in extended rather than localized regions of k? space. In contrast, critical-point transitions show up clearly in modulated reflectance spectra, and all elements of structure are fully accounted for by our band model. The temperature and strain responses in the band structure are determined by performing the RAPW calculation with two lattice constants and estimating the effects ofthe lattice vibrations by means of an OPW-LCAO (linear combination of atomic orbitals) scheme with pseudopotential Fourier constants reduced by the appropriate Debye-Waller factors. The phonon spectrum has been calculated for the latter purpose.

Christensen, N Egede; Seraphin, B. O.

1971-01-01

11

Electronic band structure of graphite-boron nitride alloys  

Energy Technology Data Exchange (ETDEWEB)

Extended-Hueckel crystal orbital band calculations, frontier crystal orbital analysis, and degenerate-level perturbation theory are used to explore the electronic structure of several graphite-boron nitride alloys: BC{sub 3}, C{sub 3}N, BC{sub 2}N, and their structural isomers. These materials are treated as two-dimensional solids, and the effect of crystal relaxation on the bandgap is considered. Similarities and differences between the band diagrams of the structurally similar materials are discussed and understood in a simple crystal orbital framework.

LaFemina, J.P. (Pacific Northwest Lab., Richland, WA (USA))

1990-05-17

12

Nonlocal pseudopotentials in complex band-structure and photoemission calculations  

Energy Technology Data Exchange (ETDEWEB)

Based on a recently proposed localization procedure, a nonlocal pseudopotential scheme is derived to calculate potential coefficients V{sub {rvec G}{rvec G}{sup {prime}}}({rvec k}) which can be decomposed into terms, each being quadratic in {rvec k} and multiplied by a function of ({rvec G}{minus}{rvec G}{sup {prime}}), thus making them applicable to some important cases where local potential coefficients are required. Electronic structure calculations for semiconductors are in agreement with well-known semiempirical local pseudopotential band structures, as shown for GaAs. Nevertheless, the potential may significantly deviate from the semiempirical results. In order to test wave functions and transition probabilities, we prove the success of the procedure in a more troublesome case, i.e., applying it to a transition-metal compound as the experimentally well-investigated layered crystal TiSe{sub 2}, which up to now was not treated with a pseudopotential. Photoemission spectra within the one-step model are presented using Pendry`s method of complex band-structure calculation. The latter formalism had to be slightly generalized for the quasilocal properties of the potential. The agreement of the spectra with experimental data shows this method to be a reliable and practical tool to use nonlocal pseudopotentials for conduction-band wave functions of electron spectroscopies. {copyright} {ital 1997} {ital The American Physical Society}

Boedicker, A.; Schattke, W. [Institut fuer Theoretische Physik, Leibnizstrae 15, D-24118 Kiel (Germany)

1997-02-01

13

Nonlocal pseudopotentials in complex band-structure and photoemission calculations  

International Nuclear Information System (INIS)

Based on a recently proposed localization procedure, a nonlocal pseudopotential scheme is derived to calculate potential coefficients Vrvec Grvec G'(rvec k) which can be decomposed into terms, each being quadratic in rvec k and multiplied by a function of (rvec G-rvec G'), thus making them applicable to some important cases where local potential coefficients are required. Electronic structure calculations for semiconductors are in agreement with well-known semiempirical local pseudopotential band structures, as shown for GaAs. Nevertheless, the potential may significantly deviate from the semiempirical results. In order to test wave functions and transition probabilities, we prove the success of the procedure in a more troublesome case, i.e., applying it to a transition-metal compound as the experimentally well-investigated layered crystal TiSe2, which up to now was not treated with a pseudopotential. Photoemission spectra within the one-step model are presented using Pendry's method of complex band-structure calculation. The latter formalism had to be slightly generalized for the quasilocal properties of the potential. The agreement of the spectra with experimental data shows this method to be a reliable and practical tool to use nonlocal pseudopotentials for conduction-band wave functions of electron spectroscopies. copyright 1997 The American Physical Society.

1997-01-01

14

Emission bands of phosphorus and calculation of band structure of rare earth phosphides  

International Nuclear Information System (INIS)

[en] The method of x-ray emission spectroscopy has been used to investigate the electronic structure of monophosphides of rare-earth metals (REM). The fluorescence K bands of phosphorus have been obtained in LaP, PrP, SmP, GdP, TbP, DyP, HoP, ErP, TmP, YbP, and LuP and also the Lsub(2,3) bands of phosphorus in ErP, TmP, YbP, and LuP. Using the Green function technique involving the muffin-tin potential, the energy spectrum for ErP has been calculated in the single-electron approximation. The hystogram of electronic state distribution N(E) is compared with the experimental K and Lsub(2,3) bands of phosphorus in ErP. The agreement between the main details of N(E) and that of x-ray spectra allows to state that the model used provides a good description of the electron density distribution in crystals of REM monophosphides. In accordance with the character of the N(E) distribution the compounds under study are classified as semimetals or semiconductors with a very narrow forbidden band

1976-09-16

15

Plasmon-pole models affect band gaps in GW calculations  

Science.gov (United States)

Density functional theory calculations have long been known to underestimate the band gaps in semiconductors. Significant improvements have been made by using GW calculations that uses the self energy, defined as the product of the Green function (G) and screened Coulomb exchange (W). However, many approximations are made in the GW method, specifically the plasmon-pole approximation. This approximation replaces the integration necessary to produce W with a simple approximation to the inverse dielectric function. Four different plasmon-pole approximations have been tested using the tight-binding program ABINIT: Godby-Needs, Hybertsen-Louie, von der Linden-Horsch, and Engel-Farid. For many materials, the differences in the GW band gaps for the different plasmon-pole models are negligible, but for systems with localized electrons, the difference can be larger than 1 eV. The plasmon-pole approximation is generally chosen to best agree with experimental data, but this is misleading in that this ignores all of the other approximations used in the GW method. Improvements in plasmon-pole models in GW can only come about by trying to reproduce the results of the numerical integration rather than trying to reproduce experimental results.

Larson, Paul; Wu, Zhigang

2013-03-01

16

Band-structure calculations of specular reflection in spin valves  

Energy Technology Data Exchange (ETDEWEB)

Band structure calculations are carried out on three types of spin-valve structures: (1) simple spin valves, (2) dual spin valves, and (3) spin valves with a synthetic antiferromagnet. The effect of specular reflection is studied by comparing the transport properties of spin valves with resistive metallic and insulating layers at the outer boundaries. In the spin valve with a synthetic antiferromagnet, an insulating layer needs to be inserted inside the reference layer to achieve similar enhancement to the giant magnetoresistance as the other two types of spin valves with insulating outer boundaries. Results are analyzed in terms of s{endash}d scattering in the different spin channels with different boundary conditions. {copyright} 2001 American Institute of Physics.

Chen, Jian; Fernandez-de-Castro, Juan

2001-06-01

17

A Calculation of the Pressure Dependent Energy Bands of CuCl.  

Science.gov (United States)

The calculation of the energy bands of CuCl by the cluster method is presented. Several clusters were used, all giving the same results. The calculated energy bands coincide with the known experimental facts on CuCl. The calculated bands present a sudden ...

P. S. Guimaraes N. D. J. Parada

1980-01-01

18

Self-consistent Hartree energy band calculation for manganese oxide (MnO)  

Energy Technology Data Exchange (ETDEWEB)

A self-consistent Hartree energy band calculation was done for the MnO crystal using the linear combination of atomic orbitals (LCAO) method. Gaussian type atomic orbitals were used in the LCAO method. This calculation was done for paramagnetic MnO with the NaCl lattice structure. The results show that the energy bands around the Fermi level of MnO are unusually flat, meaning that the electrons in this region are strongly localized. Therefore short range correlation was added to the results of this band calculation. The short range correlation effects were added by calculating atomic type corrections to the original band structure. The results of this correlation calculation show that a large amount of energy is required to excite an electron from the Mn 3d band. Therefore the lowest excitation (the one that requires the least energy) is an excitation from the top of the O 2p band to the Fermi level. This yields a fundamental band gap of 4.8 eV which is in good agreement with optical absorption experiments. This fundamental band gap of 4.8 eV implies that MnO is an insulator, in agreement with conductivity experiments. The Hartree results for the valence bands of MnO agree very well with the results of photoemission experiments. In comparison to the photoemission data, the results of the self-consistent Hartree calculation are an order of magnitude better than the results of the only other band calculation for MnO. Comparison with band calculations for other transition metal oxides (other than MnO) imply that with a good self-consistent Hartree energy band calculation for MnO can be superior.

Bakhshai, A.

1982-01-01

19

Energy band calculation of amorphous indium tin oxide films on polyethylene terephthalate substrate with indirect transition  

International Nuclear Information System (INIS)

Amorphous indium tin oxide films were grown on a polyethylene terephthalate substrate by RF-magnetron sputtering. The energy band, which contained not only the width of the optical band but also detailed information about the Fermi level (Ef) and mobility edge (Ec'), was calculated according to the theory of amorphous semiconductors with the experimental parameters of transmittance and electrical conductivity. Furthermore, the calculated energy band can be used to effectively explain both the variation of electrical conductivity and the weak absorption at the wavelength range of 750-800 nm in our experiment. An indirect transition was also clearly observed in our samples during the calculation of the optical energy band.

2009-01-21

20

Perturbation expansion of the ground-state energy for the one-dimensional cyclic Hubbard system in the Hueckel limit  

International Nuclear Information System (INIS)

The perturbation expansion coefficients for the ground-state energy of the half-filled one-dimensional Hubbard model with N = 4? + 2, (? = 1,2,...) sites and satisfying cyclic boundary conditions were calculated in the Hueckel limit (U/? ? 0), where ? designates the one-electron hopping or resonance integral, and U, the two-electron on-site Coulomb integral. This was achieved by solving-order by order-the Lieb-Wu equations, a system of transcendental equations that determines the set of quasi-momenta (ki) and spin variable ?? for this model. The exact values for these quantities were found for the N = 6 member ring up to the 20th order in terms of the coupling constant B = U/2?, as well as numerically for 10 ? N ? 50, and the N = 6 Lieb-Wu system was reduced to a system of sextic algebraic equations. These results are compared with those of the infinite system derived analytically by Misurkin and Ovchinnikov. It is further shown how the results of this article can be used for the interpolation by the root of a polynomial. It is demonstrated that a polynomial of relatively small degree provides a very good approximation for the energy in the intermediate coupling region. 20 refs., 3 tabs.

1995-01-01

 
 
 
 
21

Perturbation expansion of the ground-state energy for the one-dimensional cyclic Hubbard system in the Hueckel limit  

Energy Technology Data Exchange (ETDEWEB)

The perturbation expansion coefficients for the ground-state energy of the half-filled one-dimensional Hubbard model with N = 4{sub {nu}} + 2, ({nu} = 1,2,...) sites and satisfying cyclic boundary conditions were calculated in the Hueckel limit (U/{beta} {r_arrow} 0), where {beta} designates the one-electron hopping or resonance integral, and U, the two-electron on-site Coulomb integral. This was achieved by solving-order by order-the Lieb-Wu equations, a system of transcendental equations that determines the set of quasi-momenta (k{sub i}) and spin variable {tau}{sub {alpha}} for this model. The exact values for these quantities were found for the N = 6 member ring up to the 20th order in terms of the coupling constant B = U/2{beta}, as well as numerically for 10 {le} N {le} 50, and the N = 6 Lieb-Wu system was reduced to a system of sextic algebraic equations. These results are compared with those of the infinite system derived analytically by Misurkin and Ovchinnikov. It is further shown how the results of this article can be used for the interpolation by the root of a polynomial. It is demonstrated that a polynomial of relatively small degree provides a very good approximation for the energy in the intermediate coupling region. 20 refs., 3 tabs.

Takahashi, M. [Ajinomoto Central Research Lab., Kawasaki (Japan); Bracken, P.; Cizek, J.; Paldus, J. [Univ. of Waterloo, Ontario (Canada)

1995-03-05

22

IBM-2 calculation of band mixing in 132Ba  

International Nuclear Information System (INIS)

The band crossing in 132Ba has been investigated by using the interacting boson model. A broken neutron pair has been coupled to a collective boson core. The boson-fermion interaction hamiltonian contains terms which can transform a boson into a pair of quasiparticles and vice versa. The parameters were partly determined by fitting the collective states of 132,134Ba and the yrast states of 131Ba. The energy backbending has been satisfactorily reproduced. Good agreement of the electromagnetic moments has been reached. The structure of the wave functions has been discussed. (author)

2000-01-01

23

Band-to-band Auger recombination in GaInN from first principle calculations  

International Nuclear Information System (INIS)

Recent theoretical work implies that inter-band Auger recombination causes a resonance in the Auger coefficient in the blue to green spectrum and opened a discussion whether this effect may lead to a loss in quantum efficiency of nitrite based light emitters. We investigate the possibility of intra- and inter-band Auger recombination in wurtzite Ga1-xInxN alloys. Using density functional theory and the local density approximation we compute Auger recombination rates for Indium concentrations x ranging from 0 to 100%.

2011-01-01

24

BoltzTraP. A code for calculating band-structure dependent quantities  

CERN Multimedia

A program for calculating the semi-classic transport coefficients is described. It is based on a smoothed Fourier interpolation of the bands. From this analytical representation we calculate the derivatives necessary for the transport distributions. The method is compared to earlier calculations, which in principle should be exact within Boltzmann theory, and a very convincing agreement is found.

Madsen, G K H; Madsen, Georg K. H.; Singh, David J.

2006-01-01

25

Self-consistent band structure calculations and optical properties of the La-H system  

Energy Technology Data Exchange (ETDEWEB)

The results of self-consistent band structure calculations of lanthanum dihydride and trihydride which were performed in the framework of local density functional theory are presented. The calculated density and joint density of states are compared with the results of experimental UV photoelectron spectroscopy and X-ray photoelectron spectroscopy studies and optical experimental measurements. Indirect overlap between the conduction and valence bands of LaH/sub 3/ appears when the approximations for the crystal potential are improved.

Kulikov, N.I.

1982-12-01

26

IBM-2 calculations of the uranium isotopes and their relationship to superdeformed bands  

International Nuclear Information System (INIS)

Neutron-proton Interacting Boson Model (IBM-2) calculations have been carried out for the uranium isotopes. Because of their large number of valence protons and neutrons, the uranium isotopes should have ground-state bands of the same structure as multiparticle-multihole (mp-nh) excited bands in such nuclei as the mercury isotopes. In particular, the rotational band built on the 4p-6h proton excited state in 192Hg should have the same IBM-2 structure as the ground-state band in 232U, because theoretically both of these bands contain five active proton bosons and seven active neutron bosons. Comparison between the authors theoretical results and the experimental results for the superdeformed band in 192Hg indicates that this is a reasonable assumption.

1993-01-01

27

IBM-2 calculations of the uranium isotopes and their relationship to superdeformed bands  

Energy Technology Data Exchange (ETDEWEB)

Neutron-proton Interacting Boson Model (IBM-2) calculations have been carried out for the uranium isotopes. Because of their large number of valence protons and neutrons, the uranium isotopes should have ground-state bands of the same structure as multiparticle-multihole (mp-nh) excited bands in such nuclei as the mercury isotopes. In particular, the rotational band built on the 4p-6h proton excited state in {sup 192}Hg should have the same IBM-2 structure as the ground-state band in {sup 232}U, because theoretically both of these bands contain five active proton bosons and seven active neutron bosons. Comparison between the authors theoretical results and the experimental results for the superdeformed band in {sup 192}Hg indicates that this is a reasonable assumption.

Barrett, B.R.; Barfield, A.F.

1993-04-01

28

Two-band calculations on the upper critical field of superconductor NbSe2  

International Nuclear Information System (INIS)

We study the temperature dependence of upper critical field for NbSe2. Temperature dependence of the anisotropy parameter is also determined. The band with the smaller gap is most probably located on the bonding Nb Fermi sheet. Based on two-band Ginzburg–Landau theory, we study the temperature dependence of upper critical field for superconducting crystal NbSe2. The results reproduce the experimental data in a broad temperature range, especially the upward curvature near the transition temperature. Our calculations also indicate that in NbSe2 the band with the smaller gap is almost isotropic, and most probably located on the bonding Nb Fermi sheets.

2011-01-01

29

Dielectric band structure of crystals: General properties, and calculations for silicon  

International Nuclear Information System (INIS)

We shift the dielectric band structure method, orginially proposed by Baldereschi and Tosatti for the description of microscopic electronic screening in crystals. Some general properties are examined first, including the requirements of causality and stability. The specific test case of silicon is then considered. Dielectric bands are calculated, according to several different prescriptions for the construction of the dielectric matrix. It is shown that the results allow a very direct appraisal of the screening properties of the system, as well as of the quality of the dielectric model adopted. The electronic charge displacement induced by ?sub(25') and X3 phonon-like displacements of the atoms is also calculated and compared with the results of existent full self-consistent calculations. Conclusions are drawn on the relative accuracies of the dielectric band structures. (author)

1981-01-01

30

Large-scale local-density-approximation band gap corrected GaAsN calculations  

Energy Technology Data Exchange (ETDEWEB)

A novel method is used to calculate the electronic structure of GaAsN alloy. The charge density of a thousand atom supercell is generated by patching the charge density of a small unit cell with the charge density of bulk GaAs. The LDA band gap error is corrected by modifying the nonlocal pseudopotentials. A localized nitrogen state [a{sub 1}(N)] is obtained for the first time through an ab initio quality calculation. We found that it plays an important role in the band gap reduction of GaAsN.

Wang, Lin-Wang

2000-03-01

31

CsSnX3 (X= Cl, Br, I) band structure calculations by the QSGW method  

Science.gov (United States)

CsSnX3 (X=Cl,Br,I) perovskite compounds are of interest because of their strong photoluminescence and their potential application to solar cells. We present quasiparticle self-consistent GW (QSGW) calculations for the cubic (?-phase) including spin-orbit coupling and study the changes in band structures from the ?-phase to the ?- and ?-phases in LDA. The QSGW gaps are in good agreement with experiment. An analysis of the orbital character of the bands shows that they have an ``inverted'' band structure: the VBM has a non-degenerate s-like character (Sn-s and X-p antibonding), while the (CBM) has Sn-p character. The strongly intra-atomic dipole allowed nature of the direct gap explains the high photoluminescent intensity. The low hole mass indicates high hole mobility in agreement with experiment. The pressure dependence of the gap is found to be anomalous: the band gap decreases when the lattice constant is decreased. Effective masses and the Kohn-Luttinger type Hamiltonian of the CBM are extracted from the band structures and subsequently used to estimate exciton binding energies using our calculated dielectric constants. These indicate a much lower exciton binding energy for CsSnI3 than recently proposed.

Huang, Ling-Yi; Lambrecht, Walter R. L.

2013-03-01

32

Calculations of N2 triplet states vibrational populations and band emissions in Venusian dayglow  

CERN Document Server

A model for N2 triplet states band emissions in the Venusian dayglow has been developed for low and high solar activity conditions. Steady state photoelectron fluxes and volume excitation rates for N2 triplet states have been calculated using the Analytical Yield Spectra (AYS) technique. Model calculated photoelectron flux is in good agreement with Pioneer Venus Orbiter-observed electron flux. Since inter-state cascading is important for the triplet states of N2, populations of different levels of N2 triplet states are calculated under statistical equilibrium considering direct electron impact excitation, and cascading and quenching effects. Densities of all vibrational levels of each triplet state are calculated in the model. Height-integrated overhead intensities of N2 triplet band emissions are calculated, the values for Vegard-Kaplan (A^3Sigma_u^+ - X^1Pi_g^+), First Positive (B^3Pi_g - A^3Sigma_u^+), Second Positive (C^3Pi_u - B^3Pi_g), and Wu-Benesch (W^3Delta_u - B^3Pi_g) bands of N2, are 1.9 (3.2), 3 ...

Bhardwaj, Anil

2011-01-01

33

Calculation of isotopic profile during band displacement on ion exchange resins  

International Nuclear Information System (INIS)

A method has been developed to calculate the isotopic profile during band displacement on ion exchange resins using computer simulation. Persoz had utilized this technique earlier for calculating the isotopic profile during band displacement as well as frontal analysis. The present report deals with a simplification of the method used by Persoz by reducing the number of variables and making certain approximations where the separation factor is not far from unity. Calculations were made for the typical case of boron isotope separation. The results obtained by the modified method were found to be in very good agreement with those obtained by using an exact equation, at the same time requiring conside--rably less computer time. (author)

1981-01-01

34

Large-scale local-density-approximation band gap-corrected GaAsN calculations  

Energy Technology Data Exchange (ETDEWEB)

The electronic structure of a GaAsN alloy is calculated using a 4096 atom supercell, with a 70 Ry plane wave basis cutoff and Ga atom 3d electrons as valence electrons. The charge density of this supercell is generated by patching the charge density of a small unit cell with the charge density of bulk GaAs. The local-density-approximation band gap error is corrected by modifying the nonlocal pseudopotentials. A localized nitrogen state [a{sub 1}(N)] is obtained,and it plays an important role in the band gap reduction of GaAsN.

Wang, Lin-Wang

2001-03-12

35

Large-scale local-density-approximation band gap-corrected GaAsN calculations  

International Nuclear Information System (INIS)

The electronic structure of a GaAsN alloy is calculated using a 4096 atom supercell, with a 70 Ry plane wave basis cutoff and Ga atom 3d electrons as valence electrons. The charge density of this supercell is generated by patching the charge density of a small unit cell with the charge density of bulk GaAs. The local-density-approximation band gap error is corrected by modifying the nonlocal pseudopotentials. A localized nitrogen state [a1(N)] is obtained,and it plays an important role in the band gap reduction of GaAsN.

2001-03-12

36

Precision photonic band structure calculation of Abrikosov periodic lattice in type-II superconductors  

International Nuclear Information System (INIS)

We have performed a numerical solution for band structure of an Abrikosov vortex lattice in type-II superconductors forming a periodic array in two dimensions for applications of incorporating the photonic crystals concept into superconducting materials with possibilities for optical electronics. The implemented numerical method is based on the extensive numerical solution of the Ginzburg-Landau equation for calculating the parameters of the two-fluid model and obtaining the band structure from the permittivity, which depends on the above parameters and the frequency. This is while the characteristics of such crystals highly vary with an externally applied static normal magnetic field, leading to nonlinear behavior of the band structure, which also has nonlinear dependence on the temperature. The similar analysis for every arbitrary lattice structure is also possible to be developed by this approach as presented in this work. We also present some examples and discuss the results.

2007-09-01

37

Two-band calculations on the upper critical field of superconductor NbSe{sub 2}  

Energy Technology Data Exchange (ETDEWEB)

We study the temperature dependence of upper critical field for NbSe{sub 2}. Temperature dependence of the anisotropy parameter is also determined. The band with the smaller gap is most probably located on the bonding Nb Fermi sheet. Based on two-band Ginzburg-Landau theory, we study the temperature dependence of upper critical field for superconducting crystal NbSe{sub 2}. The results reproduce the experimental data in a broad temperature range, especially the upward curvature near the transition temperature. Our calculations also indicate that in NbSe{sub 2} the band with the smaller gap is almost isotropic, and most probably located on the bonding Nb Fermi sheets.

Chen Lei; Zuo Jing; Lu Yanyan [Department of Mathematics and Physics, North China Electric Power University, Beijing 102206 (China); Huang Hai, E-mail: huanghai@pku.edu.cn [Department of Mathematics and Physics, North China Electric Power University, Beijing 102206 (China); State Key Laboratory for Mesoscopic Physics, Peking University, Beijing 100871 (China)

2011-12-15

38

Calculating the Energy Band Structure Using Sampling and Greens Function Techniques  

CERN Document Server

In this paper, a new method based on Greens function theory and Fourier transform analysis has been proposed for calculating band structure with high accuracy and low processing time. This method utilizes sampling of potential energy in some points of crystals unit cell with Dirac delta functions, then through lattice Fourier transform gives us a simple and applicable formula for most of nanostructures. Sampling of potential in a crystal lattice of any kind contains accurate approximation of actual potential energy of atoms in the crystal. The step forward regarding the method concentrated on two novel ideas, Firstly, the potential was sampled and approximated by delta functions spread over the unit cell. Secondly, the principal equation of lattice is translated into reciprocal lattice and resulted in a huge reduction of calculations. By this method, it is possible to extract the band structure of any one, two or three dimensional crystalline structure.

Khoshnegar, Milad; Arjmandi, Nima; Khorasani, Sina

2012-01-01

39

Numerical extraction of de Haas - van Alphen frequencies from calculated band energies  

CERN Multimedia

A new algorithm for extracting de Haas - van Alphen frequencies, effective masses, and electronic density of states contributions from calculated band energies is presented. The algorithm creates an interpolated k-space "super cell", which is broken into slices perpendicular to the desired magnetic field direction. Fermi surface orbits are located within each slice, and de Haas - van Alphen frequencies, effective masses and density of states contributions are calculated. Orbits are then matched across slices, and extremal orbits determined. This technique has been successful in locating extremal orbits not previously noticed in the complicated topology of existing UPt3 band-structure data; these new orbits agree with experimental de Haas - van Alphen measurements on this material, and solidify the case for a fully-itinerant model of UPt3.

Rourke, P M C

2008-01-01

40

Tight binding electronic band structure calculation of achiral boron nitride single wall nanotubes  

International Nuclear Information System (INIS)

In this paper we report the Tight-Binding method, for the electronic structure calculations of achiral single wall Boron Nitride nanotubes. We have used the contribution of ? electron only to define the electronic band structure for the solid. The Zone-folding method is used for the Brillouin Zone definition. Calculation of tight binding model parameters is done by fitting them to available experimental results of two-dimensional hexagonal monolayers of Boron Nitride. It has been found that all the boron nitride nanotubes (both zigzag and armchair) are constant gap semiconductors with a band gap of 5.27eV. All zigzag BNNTs are found to be direct gap semiconductors while all armchair nanotubes are indirect gap semiconductors. (author)

2006-01-01

 
 
 
 
41

Explicit dynamic finite element method for band-structure calculations of 2D phononic crystals  

Science.gov (United States)

A fluid solid coupling numerical algorithm based on explicit dynamic finite element method (DFEM) for band-structure calculation in phononic crystals is presented. Numerical examples are developed for 2D square phononic lattice with Au cylinders in epoxy matrix, and mercury cylinders in Al matrix. The results are compared with those calculated by FDTD and PWE methods, which indicate that DFEM is efficient in dealing with the wave propagation in phononic crystals, and displays potential abilities in dealing with anisotropic and nonlinear problems.

Liu, Ying; Gao, Ling-Tian

2007-10-01

42

Calculation of the band structure of 2d conducting polymers using the network model  

International Nuclear Information System (INIS)

the network model has been used to calculate the band structure the gap energy and Fermi level of conducting polymers in two dimensions. For this purpose, a geometrical classification of possible polymer chains configurations in two dimensions has been introduced leading to a classification of the unit cells based on the number of bonds in them. The model has been applied to graphite in 2D, represented by a three bonds unit cell, and, as a new case, the anti-parallel Polyacetylene chains (PA) in two dimensions, represented by a unit cell with four bons. The results are in good agreement with the first principles calculations. (author)

2007-01-01

43

Model calculation of N2 Vegard-Kaplan band emissions in Martian dayglow  

CERN Document Server

A model for N2 Vegard-Kaplan (VK) band (A^3Sigma_u^+ - X^1Sigma_g^+) emissions in Martian dayglow has been developed to explain the recent observations made by the Spectroscopy for Investigation of Characteristics of the Atmosphere of Mars (SPICAM) ultraviolet spectrograph aboard Mars Express. Steady state photoelectron fluxes and volume excitation rates have been calculated using the analytical yield spectra technique. Since interstate cascading is important for triplet states of N2, the population of any given level of N2 triplet states is calculated under statistical equilibrium considering direct excitation, cascading, and quenching effects. Relative population of all vibrational levels of each triplet state is calculated in the model. Line of sight intensities and height-integrated overhead intensities have been calculated for VK, first positive (B^3Pi_g - A^3Sigma_u^+), second positive (C^3Pi_u - B^3Pi_g), and Wu-Benesch (W^3Delta_u - B^3Pi_g) bands of N2. A reduction in the N2 density by a factor of 3 ...

Jain, Sonal Kumar

2011-01-01

44

A method for the calculation of induced band power: implications for the significance of brain oscillations.  

Science.gov (United States)

A method for the calculation of significant changes in induced band power (IBP) is presented. In contrast to traditional measures of event-related band power (ERBP) which are composed of evoked and not evoked EEG components, the proposed measure for IBP is deprived from phase locked (or evoked) EEG activity. It is assumed that changes in IBP reflect the modulation of brain oscillations that are largely independent from ERPs. The results of a visual oddball task show that significant changes in IBP can be observed in response to the presentation of a warning signal (preceding a target or nontarget) and the imperative stimulus (i.e. a target or nontarget) in the alpha, theta and delta band. Only a few significant changes in IBP were obtained for the warning signal in the theta band although highly significant changes in ERBP were found. Our findings document that changes in IBP may be considered a phenomenon that is largely independent from the occurrence of ERPs. They underline the significance of oscillatory processes and suggest that induced rhythms are modulated by stimuli and/or events in a not phase locked way. PMID:9566625

Klimesch, W; Russegger, H; Doppelmayr, M; Pachinger, T

1998-03-01

45

A method for the calculation of induced band power: implications for the significance of brain oscillations.  

UK PubMed Central (United Kingdom)

A method for the calculation of significant changes in induced band power (IBP) is presented. In contrast to traditional measures of event-related band power (ERBP) which are composed of evoked and not evoked EEG components, the proposed measure for IBP is deprived from phase locked (or evoked) EEG activity. It is assumed that changes in IBP reflect the modulation of brain oscillations that are largely independent from ERPs. The results of a visual oddball task show that significant changes in IBP can be observed in response to the presentation of a warning signal (preceding a target or nontarget) and the imperative stimulus (i.e. a target or nontarget) in the alpha, theta and delta band. Only a few significant changes in IBP were obtained for the warning signal in the theta band although highly significant changes in ERBP were found. Our findings document that changes in IBP may be considered a phenomenon that is largely independent from the occurrence of ERPs. They underline the significance of oscillatory processes and suggest that induced rhythms are modulated by stimuli and/or events in a not phase locked way.

Klimesch W; Russegger H; Doppelmayr M; Pachinger T

1998-03-01

46

Extracting E Versus K Effective Band Structure from Supercell Calculations on Alloys and Impurities  

International Nuclear Information System (INIS)

The supercell approach to defects and alloys has circumvented the limitations of those methods that insist on using artificially high symmetry, yet this step usually comes at the cost of abandoning the language of E versus k band dispersion. Here we describe a computational method that maps the energy eigenvalues obtained from large supercell calculations into an effective band structure (EBS) and recovers an approximate E(k) for alloys. Making use of supercells allows one to model a random alloy A1-xBxC by occupying the sites A and B via a coin-toss procedure, affording many different local environments (polymorphic description) to occur. We present the formalism and implementation details of the method and apply it to study the evolution of the impurity band appearing in the dilute GaN:P alloy. We go beyond the perfectly random case, realizing that many alloys may have nonrandom microstructures, and investigate how their formation is reflected in the EBS. It turns out that the EBS is extremely sensitive in determining the critical disorder level for which delocalized states start to appear in the intermediate band. In addition, the EBS allows us to identify the role played by atomic relaxation in the positioning of the impurity levels.

2012-02-15

47

Band-structure calculations and structure-factor estimates of Cu - their complementarity  

International Nuclear Information System (INIS)

Rather than an uncritical comparison of experimental and theoretical values, the various sets of structure-factor values of copper metal derived from experimental diffraction procedures are mutally compared as also are the various sets of theoretical values derived from band-structure calculations. This approach reveals the presence of outlier sets in each group and allows recognition of their condition before any attempt is made to intercompare the groups. Within the experimental group, the ?-ray values do not appear to sustain the absolute status originally claimed from them. Within the theoretical group, an inadequacy in defining the core contribution is indicated. The latter conclusion suggests that it is an inappropriate operation to make direct comparison between diffraction-sourced experimental values of structure factors and theoretical values from band-structure calculations. Instead, the latter should be used on a complementary basis with the full (sin ?)/? range of experimental values to establish the best core contribution. The minor valence-bond contribution to scattering, which is largely restricted to the low (sin ?)/? region, is most sensitively defined by reference to band-structure prediction of photoemission spectral distribution. Attention is drawn to the possible significance of the form-factor curve versus (sin ?)/? being dependent on the unit-cell dimension. (orig.).

1992-01-01

48

Band-structure calculations and structure-factor estimates of Cu - their complementarity  

Energy Technology Data Exchange (ETDEWEB)

Rather than an uncritical comparison of experimental and theoretical values, the various sets of structure-factor values of copper metal derived from experimental diffraction procedures are mutally compared as also are the various sets of theoretical values derived from band-structure calculations. This approach reveals the presence of outlier sets in each group and allows recognition of their condition before any attempt is made to intercompare the groups. Within the experimental group, the {gamma}-ray values do not appear to sustain the absolute status originally claimed from them. Within the theoretical group, an inadequacy in defining the core contribution is indicated. The latter conclusion suggests that it is an inappropriate operation to make direct comparison between diffraction-sourced experimental values of structure factors and theoretical values from band-structure calculations. Instead, the latter should be used on a complementary basis with the full (sin {theta})/{lambda} range of experimental values to establish the best core contribution. The minor valence-bond contribution to scattering, which is largely restricted to the low (sin {theta})/{lambda} region, is most sensitively defined by reference to band-structure prediction of photoemission spectral distribution. Attention is drawn to the possible significance of the form-factor curve versus (sin {theta})/{lambda} being dependent on the unit-cell dimension. (orig.).

Mackenzie, J.K. (Div. of Materials Science and Technology, CSIRO, Clayton, Victoria (Australia)); Mathieson, A.M. (Div. of Materials Science and Technology, CSIRO, Clayton, Victoria (Australia) Chemistry Dept., La Trobe Univ., Bundoora, Victoria (Australia))

1992-03-01

49

A Hartree-Fock ab initio band-structure calculation employing Wannier-type orbitals  

CERN Multimedia

An ab initio Wannier-function-based approach to electronic ground-state calculations for crystalline solids is outlined. In the framework of the linear combination of atomic orbitals method the infinite character of the solid is rigorously taken into account. The Hartree-Fock ground-state energy, cohesive energy, lattice constant and bulk modulus are calculated in a fully ab initio manner as it is demonstrated for sodium chloride, NaCl, using basis sets close to the Hartree-Fock limit. It is demonstrated that the Hartree-Fock band-structure can easily be recovered with the current approach and agrees with the one obtained from a more conventional Bloch-orbital-based calculation. It is argued that the advantage of the present approach lies in its capability to include electron correlation effects for crystalline insulators by means of well-established quantum chemical procedures.

Albrecht, M; Dolg, M; Fulde, P; Stoll, H; Albrecht, Martin; Shukla, Alok; Dolg, Michael; Fulde, Peter; Stoll, Hermann

1998-01-01

50

From Metal Cluster to Metal Nanowire: A Topological Analysis of Electron Density and Band Structure Calculation  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract:We investigate a theoretical model of molecular metalwire constructed from linear polynuclear metal complexes. In particular we study the linear Crn metal complex and Cr molecular metalwire. The electron density distributions of the model nanowire and the linear Crn metal complexes, with n = 3, 5, and 7, are calculated by employing CRYSTAL98 package with topological analysis. The preliminary results indicate that the bonding types between any two neighboring Cr are all the same, namely the polarized open-shell interaction. The pattern of electron density distribution in metal complexes resembles that of the model Cr nanowire as the number of metal ions increases. The conductivity of the model Cr nanowire is also tested by performing the band structure calculation.

Feng-Yin Li; Likey Chen; Chung-Yuan Mou; Shie-Ming Peng; Yu Wang

2002-01-01

51

Calculation of the Band Gap Energy and Study of Cross Luminescence in Alkaline-Earth Dihalide Crystals  

CERN Multimedia

The band gap energy as well as the possibility of cross luminescence processes in alkaline-earth dihalide crystals have been calculated using the ab initio Perturbed-Ion (PI) model. The gap is calculated in several ways: as a difference between one-electron energy eigenvalues and as a difference between total energies of appropriate electronic states of the crystal, both at the HF level and with inclusion of Coulomb correlation effects. In order to study the possibility of ocurrence of cross luminescence in these materials, the energy difference between the valence band and the upmost core band for some representative crystals has been calculated. Both calculated band gap energies and cross luminescence predictions compare very well with the available experimental results.

Aguado, A; López, J M; Alonso, J A; Aguado, Andres; Ayuela, Andres; Lopez, Jose M.; Alonso, Julio A.

1999-01-01

52

The use of bulk states to accelerate the band edge state calculation of a semiconductor quantum dot  

International Nuclear Information System (INIS)

We present a new technique to accelerate the convergence of the folded spectrum method in empirical pseudopotential band edge state calculations for colloidal quantum dots. We use bulk band states of the materials constituent of the quantum dot to construct initial vectors and a preconditioner. We apply these to accelerate the convergence of the folded spectrum method for the interior states at the top of the valence and the bottom of the conduction band. For large CdSe quantum dots, the number of iteration steps until convergence decreases by about a factor of 4 compared to previous calculations

2007-05-01

53

Energy and momentum resolved band structure of K2O : electron momentum spectroscopy and linear combination of atomic orbitals calculation  

International Nuclear Information System (INIS)

[en] This paper details an experimental and theoretical investigation into the electronic structure of the highly ionic, alkali oxide, potassium oxide (K2O). The experiments were carried out using the relatively new technique of electron momentum spectroscopy. This is an electron impact technique that is capable of measuring the electron intensity distribution as a function of energy and momentum. Calculations were performed within the linear combination of atomic orbitals approximation using both Hartree-Fock and density functional theory formalisms. We have been able to map the band dispersions and intensities in the oxygen valence bands and potassium 3p and 3s bands for the first time. Overlap of the O 2s and K 3p binding energy peaks makes it difficult to extract the band gaps involving either of these bands. The O 2p and K 3s peaks are resolved, however, and we observe a gap of 30.4 ± 0.2 deg. eV. This value is reproduced by the PBE0 calculation. Intensities within the s bands are reproduced well by all our calculations, whereas the observed p bands show anomalous intensity at the ?-point, which is not present in any of the calculations

2003-10-22

54

First calculation of phase and coherence of longitudinally separated L-band equatorial ionospheric scintillation  

Science.gov (United States)

We present the first calculation of phase and coherence of cross-wavelet transform applied to longitudinally separated L-band equatorial ionospheric scintillation observations received from Geostationary Earth Orbit (GEO) satellites. The phase and coherence analysis were employed on two pairs of observations: (1) São Luís and Rio Branco and (2) Alta Floresta and Huancayo. For these case studies, in statistically significant and high-coherence regions, scintillation observations over São Luís (Alta Floresta) lead that of Rio Branco (Huancayo) by ˜2 to 3 h with a 95%frequency. If L-band scintillation happens over São Luís (Alta Floresta), there is a 95%likelihood that scintillation would happen to the west over Rio Branco (Huancayo) after ˜2 to 3 h, suggesting that a forecast can be made ahead of scintillation occurrences. The phase and coherence relationships between the longitudinally separated scintillation-producing regions can be connected to the large-scale wave structures which are reported to be related to the generation of equatorial spread F and scintillation.

Shume, E. B.; Mannucci, A. J.

2013-07-01

55

Full band calculations of the intrinsic lower limit of contact resistivity  

Science.gov (United States)

The intrinsic lower limit of contact resistivity (?cLL) for InAs, In0.53Ga0.47As, GaSb, and Si is calculated using a full band ballistic quantum transport approach. Surprisingly, our results show that ?cLL is almost independent of the semiconductor. An analytical model, derived for 1D, 2D, and 3D, correctly reproduces the numerical results and explains why ?cLL is very similar in all cases. Our analysis sets a minimal carrier density required to meet the International Technology Roadmap for Semiconductors call for ?c=10-9 ?-cm2 by 2023. Comparison with experiments shows there is room for improvement, which will come from optimizing interfacial properties.

Maassen, J.; Jeong, C.; Baraskar, A.; Rodwell, M.; Lundstrom, M.

2013-03-01

56

Ab-initio calculations of the Optical band-gap of TiO2 thin films  

CERN Multimedia

Titanium dioxide has been extensively studied in recent decades for its important photocatalytic application in environmental purification. The search for a method to narrow the optical band-gap of TiO2 plays a key role for enhancing its photocatalytic application. The optical band gap of epitaxial rutile and anatase TiO2 thin films deposited by helicon magnetron sputtering on sapphire and on SrTiO3 substrates was correlated to the lattice constants estimated from HRTEM images and SAED. The optical band-gap of 3.03 eV for bulk-rutile increased for the thin films to 3.37 on sapphire. The band gap of 3.20 eV for bulk-anatase increases to 3.51 on SrTiO3. In order to interpret the optical band gap expansion for both phases, ab-initio calculations were performed using the Vienna ab-initio software. The calculations for rutile as well anatase show an almost linear increase of the band gap width with decreasing volume or increasing lattice constant a. The calculated band gap fits well with the experimental values. T...

Wunderlich, W; Tanemura, M; Tanemura, S; Jin, P; Kaneko, K; Terai, A; Nabatova-Gabin, N; Belkada, R; Wunderlich, Wilfried; Miao, Lei; Tanemura, Masaki; Tanemura, Sakae; Jin, Ping; Kaneko, Kenji; Terai, Asuka; Nabatova-Gabin, Nataliya; Belkada, Rachid

2004-01-01

57

Voltage effect in PTCR ceramics: Calculation by the method of tilted energy band  

International Nuclear Information System (INIS)

[en] A numerical model for the calculation of the electrical characteristics of donor-doped BaTiO3 semiconducting ceramics is suggested. This paper established a differential equation about electron level on the base of Poisson equation, and solved the equation with Runge-Kutta method. Under extra electric field, electrical characteristics have been calculated by the method of tilted energy band. We have quantitatively computed the positive temperature coefficient of resistivity (PTCR) behavior of donor-doped BaTiO3 semiconducting ceramics and its voltage effect, and further obtained non-linear current-voltage characteristics with different grain sizes at different temperature. The results pointed out that the resistance jumping is reduced with increasing electric field applied; current and voltage relation follows Ohm's law below Curie temperature, and exhibits strong non-linear above Curie temperature; the non-linear coefficient shows a maximum value at temperature the resistivity reaches maximum and with grain size closed to depletion region width. The results are compared with experimental data.

2010-02-01

58

Voltage effect in PTCR ceramics: Calculation by the method of tilted energy band  

Science.gov (United States)

A numerical model for the calculation of the electrical characteristics of donor-doped BaTiO3 semiconducting ceramics is suggested. This paper established a differential equation about electron level on the base of Poisson equation, and solved the equation with Runge-Kutta method. Under extra electric field, electrical characteristics have been calculated by the method of tilted energy band. We have quantitatively computed the positive temperature coefficient of resistivity (PTCR) behavior of donor-doped BaTiO3 semiconducting ceramics and its voltage effect, and further obtained non-linear current-voltage characteristics with different grain sizes at different temperature. The results pointed out that the resistance jumping is reduced with increasing electric field applied; current and voltage relation follows Ohm's law below Curie temperature, and exhibits strong non-linear above Curie temperature; the non-linear coefficient shows a maximum value at temperature the resistivity reaches maximum and with grain size closed to depletion region width. The results are compared with experimental data.

Fang, Chao; Zhou, Dong-Xiang; Gong, Shu-Ping

2010-02-01

59

Calculation and spectroscopy of the Landau band structure at a thin and atomically precise tunneling barrier  

CERN Document Server

Two laterally adjacent quantum Hall systems separated by an extended barrier of a thickness on the order of the magnetic length possess a complex Landau band structure in the vicinity of the line junction. The energy dispersion is obtained from an exact quantum-mechanical calculation of the single electron eigenstates for the coupled system by representing the wave functions as a superposition of parabolic cylinder functions. For orbit centers approaching the barrier, the separation of two subsequent Landau levels is reduced from the cyclotron energy to gaps which are much smaller. The position of the anticrossings increases on the scale of the cyclotron energy as the magnetic field is raised. In order to experimentally investigate a particular gap at different field strengths but under constant filling factor, a GaAs/AlGaAs heterostructure with a 52 Angstrom thick tunneling barrier and a gate electrode for inducing the two-dimensional electron systems was fabricated by the cleaved edge overgrowth method. The...

Habl, M; Wegscheider, W; Bichler, M; Abstreiter, G; Habl, Matthias; Reinwald, Matthias; Wegscheider, Werner; Bichler, Max; Abstreiter, Gerhard

2006-01-01

60

Correlation of CO{sub 2} solubility in N-methyldiethanolamine + piperazine aqueous solutions using extended Debye-Hueckel model  

Energy Technology Data Exchange (ETDEWEB)

Solubility data of CO{sub 2} in aqueous N-methyldiethanolamine (MDEA) solutions of concentration (2.52, 3.36, and 4.28) kmol/m{sup 3} were obtained at temperatures (313, 323, and 343) K and partial pressures ranging from about (30 to 5000) kPa. A thermodynamic model based on extended Debye-Hueckel theory was applied to predict and correlate of CO{sub 2} solubility in various aqueous amine solutions. The effect of piperazine (PZ) concentration on CO{sub 2} loading in MDEA solutions was determined at PZ concentration (0.36, 0.86, and 1.36) kmol/m{sup 3}. Using experimental data in various temperatures the interaction parameters of activity coefficient model for these systems were determined. The results show the model consistency with experimental and literature data and PZ is beneficial to the CO{sub 2} loading. The comparison of results of this study with previous data work shows the wide range of CO{sub 2} loading considered in this work and the better agreement of model with experimental data. The average absolute relative deviation percent ({delta}{sub AAD}) for all data points were 8.11%.

Vahidi, Mehdi [Research Institute of Petroleum Industry (R.I.P.I.), National Iranian Oil Company (N.I.O.C.), P.O. Box 14665-1998, Tehran (Iran, Islamic Republic of)], E-mail: vahidim@ripi.ir; Matin, Naser Seyed [Research Institute of Petroleum Industry (R.I.P.I.), National Iranian Oil Company (N.I.O.C.), P.O. Box 14665-1998, Tehran (Iran, Islamic Republic of); Goharrokhi, Mahdi [Department of Chemical Engineering, Tehran South Campus, Islamic Azad University, Tehran (Iran, Islamic Republic of); Jenab, Masih Hosseini; Abdi, Majid Abedinzadegan [Research Institute of Petroleum Industry (R.I.P.I.), National Iranian Oil Company (N.I.O.C.), P.O. Box 14665-1998, Tehran (Iran, Islamic Republic of); Najibi, Seyed Hesam [Department of Petroleum Engineering, Petroleum University of Technology, Ahwaz (Iran, Islamic Republic of); R and D Department, National Iranian Gas Co. (N.I.G.C.), Tehran (Iran, Islamic Republic of)

2009-11-15

 
 
 
 
61

Correlation of CO2 solubility in N-methyldiethanolamine + piperazine aqueous solutions using extended Debye-Hueckel model  

International Nuclear Information System (INIS)

Solubility data of CO2 in aqueous N-methyldiethanolamine (MDEA) solutions of concentration (2.52, 3.36, and 4.28) kmol/m3 were obtained at temperatures (313, 323, and 343) K and partial pressures ranging from about (30 to 5000) kPa. A thermodynamic model based on extended Debye-Hueckel theory was applied to predict and correlate of CO2 solubility in various aqueous amine solutions. The effect of piperazine (PZ) concentration on CO2 loading in MDEA solutions was determined at PZ concentration (0.36, 0.86, and 1.36) kmol/m3. Using experimental data in various temperatures the interaction parameters of activity coefficient model for these systems were determined. The results show the model consistency with experimental and literature data and PZ is beneficial to the CO2 loading. The comparison of results of this study with previous data work shows the wide range of CO2 loading considered in this work and the better agreement of model with experimental data. The average absolute relative deviation percent (?AAD) for all data points were 8.11%.

2009-01-01

62

Quantum Debye-Hueckel theory and the possible plasma phase transition  

International Nuclear Information System (INIS)

In this paper the author first sketches the calculation of the pressure of a neutral, ion-electron gas as an expansion in powers of the electron charge, e, by means of the Matsubara, finite-temperature, many-body, perturbation theory. He then goes on to derive the Debye-Hue term and other equations to support his contentions. His results support but do not prove the existence of a phase transition

1998-01-01

63

Quantum Debye-Hueckel theory and the possible plasma phase transition  

Energy Technology Data Exchange (ETDEWEB)

In this paper the author first sketches the calculation of the pressure of a neutral, ion-electron gas as an expansion in powers of the electron charge, e, by means of the Matsubara, finite-temperature, many-body, perturbation theory. He then goes on to derive the Debye-H{umlt u} term and other equations to support his contentions. His results support but do not prove the existence of a phase transition.

Baker, G. Jr.

1998-09-03

64

Application of the new LDA+GTB method for the band structure calculation of n-type cuprates  

International Nuclear Information System (INIS)

A novel hybrid scheme is proposed and applied for band structure calculations of undoped n-type cuprate Nd2CuO4. The ab initio LDA calculation is used to obtain single electron and Coulomb parameters of the multiband Hubbard-type model. In strong correlation regime the electronic structure within this model is calculated by the generalized tight-binding (GTB) method, that combines the exact diagonalization of the model Hamiltonian for a small cluster with perturbation treatment of the intercluster hopping and interactions. For Nd2CuO4, this scheme results in charge transfer insulator with value of the gap and band dispersion in agreement to the experimental data.

2006-05-01

65

Symmetry Aspects of the Band Structure and Motion Equations Applied in Calculating the Cyclotron Frequency of Electrons in Metals  

Directory of Open Access Journals (Sweden)

Full Text Available Cyclotron frequency of a crystal electron is, in general, not an easily accessible parameter. Nevertheless, its calculation can be simplified when the symmetry properties of the band structure and those of the motion equations in the magnetic field are simultaneously taken into account. In effect, a combined symmetry of the electron Hamiltonian and that of the Lorentz equation provide us with a non-linear oscillator problem of high symmetry. In the next step, the kinetic energy of the oscillator can be separated from the whole of electron energy and applied in a new kind of calculation of the cyclotron frequency which is much more simple than before. In consequence, a detailed approach to the electron circulation, also in more complex band structures, becomes a relatively easy task. For different crystal lattices of cubic symmetry taken as examples the cyclotron frequency of the present and a former method are compared numerically giving the same results.

Stanislaw Olszewski; Tomasz Roli?ski

2011-01-01

66

Theoretical calculation of spectrum of M band for Ni-like Au ion using the model of unresolved transition array  

International Nuclear Information System (INIS)

[en] Unresolved transition array model is applied to calculate the characteristic parameters of eight transition arrays consisted in the spectrum of Ni-like Au(Au51+), i.e., mean wave number, full width at half maximum, total strength, number of line. The eight transition arrays are superposed according to their total strength with a Gaussian curve, agreement with experiment is generally excellent and makes measurement with high space and time resolution of M band spectrum for Au possible

1998-01-01

67

Theory of composite-band Wannier states and order-N electronic-structure calculations  

CERN Document Server

'Exact' composite-band Wannier states are constructed and analyzed for the diamond-structure solids. The direct relations between the Wannier states and the order-N electronic-structure theory are also discussed as a general theory. The results imply that the locality of Wannier states directly depends on Hamiltonians and can be insensitive to the value of the bandgap.

Hoshi, T; Hoshi, Takeo; Fujiwara, Takeo

1999-01-01

68

First principles calculations of complex intermediate band materials for photovoltaic devices  

Digital Repository Infrastructure Vision for European Research (DRIVER)

An ab initio study of several compounds candidates to behave as intermediate band materials is presented. The use of these materials as the active element in solar cells is a promising way to enhance the photovoltaic efficiency. Indeed from this point of view, most interesting compounds are those...

Wahnón Benarroch, Perla; Aguilera Bonet, Irene; Palacios Clemente, Pablo; Sánchez Noriega, Kefrén

69

Electronic structure of perovskite-type YBRh3: X-ray photoelectron spectroscopy and ab initio band calculations  

International Nuclear Information System (INIS)

[en] The perovskite structure type YBRh3 was synthesized by the arc melting method. Its electronic structure was studied by XPS and ab initio band calculations. The chemical shifts of the Y and Rh 3d levels from the elements were negative. The experimental and calculated valence band XPS coincided well with each other. The band calculation indicated that the metallic behavior of the compound originates from the Rh 4d electrons. The atomic distance between Y and Rh is 93% of the sum of the radii of the elements. The electron density has a maximum between the Y and Rh atoms, and the distance between the maximum point and center of the Y atom is 77% of its atomic radius. This indicates that charge transfer occurs from Y to Rh. The nearly equal electronegativities of B and Rh result in a covalent bond between them, which is shown as an asymmetric electron distribution in the circumference of the B and Rh atoms. The covalent bond results from hybridization of the B 2p and Rh 4d levels

2003-02-03

70

Electronic structure of NaxCu1-xIn5S8 compounds: X-ray photoemission spectroscopy study and band structure calculations  

International Nuclear Information System (INIS)

[en] The aim of the present work is to complete a preliminary study concerning the electronic band structure investigations of NaxCu1-xIn5S8 compounds with 0?x?1, which are expected to be formed at the Cu(In,Ga)Se2/In2S3 interface. The band structure calculations demonstrate that for the compounds containing both Na and Cu, as the Cu content increases the band gap tends to decrease, and x-ray photoemission spectroscopy measurements show that this variation is mainly due to valence-band-maximum shift along the solid solution. The band gap strongly depends on the nature of the monovalent cation, and the band structure calculations demonstrate that the d electrons of copper are responsible for the shift of the valence band. In addition, it is worth noting that the Cu-containing compounds have indirect gaps

2008-12-15

71

Multi-band tight-binding calculation of electronic transport in Fe/trans-polyacetylene/Fe tunnel junctions  

International Nuclear Information System (INIS)

In this paper, the electronic transport characteristics of Fe/trans-polyacetylene/Fe magnetic tunnel junctions (MTJs) are investigated using multi-band tight-binding calculations within the framework of nonequilibrium Green function theory. A CH2 radical is added to different positions on the polymer chain and its effects on the tunnelling magnetoresistance of the MTJ are studied. The ferromagnetic electrodes are assumed to be single-band and their tight-binding parameters are chosen in such a way as to simulate the ab initio density functional calculations of the band structure of bcc-Fe along its [001] crystallographic direction. In building the Hamiltonian of the trans-polyacetylene (t-PA) chain, we have assumed an s orbital on the H atoms and one s and three p(px,py,pz) orbitals on the C atoms, and the dimerization effects are taken into account. It is found that moving the radical out of the centre of the polymer chain enhances the tunnelling magnetoresistance of the MTJ.

2012-01-01

72

Three-band charge fluctuation model for electron pairing: A many-body calculation  

Energy Technology Data Exchange (ETDEWEB)

We apply many-body techniques to the study of a model Hamiltonian withon-site and nearest-neighbor Coulomb interactions. We calculate polarization propagators and effective interactions. Our results give support to a charge fluctuation mechanism for pairing.

Castillo, H.; Balseiro, C.; Alascio, B.; Ceva, H.

1989-07-01

73

Structural phase transition in IrTe?: a combined study of optical spectroscopy and band structure calculations.  

UK PubMed Central (United Kingdom)

Ir(1-x)Pt(x)Te? is an interesting system showing competing phenomenon between structural instability and superconductivity. Due to the large atomic numbers of Ir and Te, the spin-orbital coupling is expected to be strong in the system which may lead to nonconventional superconductivity. We grew single crystal samples of this system and investigated their electronic properties. In particular, we performed optical spectroscopic measurements, in combination with density function calculations, on the undoped compound IrTe? in an effort to elucidate the origin of the structural phase transition at 280?K. The measurement revealed a dramatic reconstruction of band structure and a significant reduction of conducting carriers below the phase transition. We elaborate that the transition is not driven by the density wave type instability but caused by the crystal field effect which further splits/separates the energy levels of Te (p(x), p(y)) and Te p(z) bands.

Fang AF; Xu G; Dong T; Zheng P; Wang NL

2013-01-01

74

Theoretical calculation of spectrum of M band for Au using UTA model  

International Nuclear Information System (INIS)

[en] Unresolved transition array model was applied to calculate the characteristic parameters of 35 transition arrays consisted in the spectrum of M and for Au in the 0.43?0.62 nm range. Those arrays were superposed according to their total strength of UTA for each ionic spectrum and weight of ion for whole M and with a Gaussian curve. The agreement between theoretical calculation and experiment results was excellent

1998-01-01

75

A modified band approach for the accurate calculation of online photolysis rates in stratospheric-tropospheric Chemical Transport Models  

Directory of Open Access Journals (Sweden)

Full Text Available Here we present an efficient and accurate method for the online calculation of photolysis rates relevant to both the stratosphere and troposphere for use in global Chemistry Transport Models and General Circulation Models. The method is a modified version of the band model introduced by Landgraf and Crutzen (1998) which has been updated to improve the performance of the approach for solar zenith angles >72° without the use of any implicit parameterisations. For this purpose, additional sets of band parameters have been defined for instances where the incident angle of the light beam is between 72–93°, in conjunction with a scaling component for the far UV region of the spectrum (?=178.6–202.0 nm). For incident angles between 85–93° we introduce a modification for pseudo-sphericity that improves the accuracy of the 2-stream approximation. We show that this modified version of the Practical Improved Flux Method (PIFM) is accurate for angles <93° by comparing the resulting height resolved actinic fluxes with a recently developed full spherical reference model. We also show that the modified band method is more accurate than the original, with errors generally being less than ±10% throughout the atmospheric column for a diverse range of chemical species. Moreover, we perform certain sensitivity studies that indicate it is robust and performs well over a wide range of conditions relevant to the atmosphere.

J. E. Williams; J. Landgraf; A. Bregman; H. H. Walter

2006-01-01

76

A modified band approach for the accurate calculation of online photolysis rates in stratospheric-tropospheric Chemical Transport Models  

Science.gov (United States)

Here we present an efficient and accurate method for the online calculation of photolysis rates relevant to both the stratosphere and troposphere for use in global Chemistry Transport Models and General Circulation Models. The method is a modified version of the band model introduced by Landgraf and Crutzen (1998) which has been updated to improve the performance of the approach for solar zenith angles >72° without the use of any implicit parameterisations. For this purpose, additional sets of band parameters have been defined for instances where the incident angle of the light beam is between 72-93°, in conjunction with a scaling component for the far UV region of the spectrum (?=178.6-202.0 nm). For incident angles between 85-93° we introduce a modification for pseudo-sphericity that improves the accuracy of the 2-stream approximation. We show that this modified version of the Practical Improved Flux Method (PIFM) is accurate for angles <93° by comparing the resulting height resolved actinic fluxes with a recently developed full spherical reference model. We also show that the modified band method is more accurate than the original, with errors generally being less than ±10% throughout the atmospheric column for a diverse range of chemical species. Moreover, we perform certain sensitivity studies that indicate it is robust and performs well over a wide range of conditions relevant to the atmosphere.

Williams, J. E.; Landgraf, J.; Bregman, A.; Walter, H. H.

2006-09-01

77

Inelastic plasmon and inter-band electron-scattering potentials for Si from dielectric matrix calculations  

International Nuclear Information System (INIS)

Inelastic scattering of electrons in a crystalline environment may be represented by a complex non-hermitian potential. Completed generalised expressions for this inelastic electron scattering potential matrix, including virtual inelastic scattering, are derived for outer-shell electron and plasmon excitations. The relationship between these expressions and the general anisotropic dielectric response matrix of the solid is discussed. These generalised expressions necessarily include the off-diagonal terms representing effects due to departure from translational invariance in the interaction. Results are presented for the diagonal back structure dependent inelastic and virtual inelastic scattering potentials for Si, from a calculation of the inverse dielectric matrix in the random phase approximation. Good agreement is found with experiment as a function of incident energies from 10 eV to 100 keV. Anisotropy effects and hence the interaction de localisation represented by the off-diagonal scattering potential terms, are found to be significant below 1 keV. 38 refs., 2 figs

1994-01-01

78

Surface alloying in the Sn/Ni(111) system studied by synchrotron radiation photoelectron valence band spectroscopy and ab-initio density of states calculations  

International Nuclear Information System (INIS)

Photoelectron spectroscopy using synchrotron radiation and ab-initio electronic structure calculations were used in order to describe the fine structure of the valence band in the Sn/Ni(111) system. The characteristic contributions of each metal in the valence band photoemission spectra obtained with a photon energy of 80 eV and their changes upon the formation of the (?3 x ?3)R30o Sn/Ni(111) surface alloy were also born out in the calculated density-of-states curves in fair agreement with the experiments. The Sn-Ni interaction leads to a considerable broadening of the valence band width at the bimetallic surfaces.

2008-03-31

79

Electronic band structure and specific features of Sm2NiMnO6 compound: DFT calculation  

Science.gov (United States)

The band structure, density of states, electronic charge density, Fermi surface and optical properties of Sm2NiMnO6 compound have been investigated with the support of density functional theory (DFT). The atomic positions of Sm2NiMnO6 compound were optimized by minimizing the forces acting on the atoms, using the full potential linear augmented plane wave method. We employed the local density approximation (LDA), generalized gradient approximation (GGA) and Engel-Vosko GGA (EVGGA) to treat the exchange correlation potential by solving Kohn-Sham equations. The calculation shows that the compound is metallic with strong hybridization near the Fermi energy level (EF). The calculated density of states at the EF is about 21.60, 24.52 and 26.21 states/eV, and the bare linear low-temperature electronic specific heat coefficient (?) is found to be 3.74, 4.25 and 4.54 mJ/mol K2 for EVGGA, GGA and LDA, respectively. The Fermi surface is composed of two sheets. The bonding features of the compounds are analyzed using the electronic charge density in the (011) crystallographic plane. The dispersion of the optical constants was calculated and discussed.

Reshak, A. H.; Azam, Sikander

2013-09-01

80

Spin-polarized relativistic band structure calculations and their application to the magnetic X-ray dichroism  

International Nuclear Information System (INIS)

The recent development of fully relativistic spin-polarized schemes of band structure calculations allows us nowadays to investigate physical phenomena that are caused by the interplay of spin-orbital and spin polarization, without using a perturbational approach. Among these effects, the magnetic X-ray dichroism is receiving much interest because it allows us to probe the magnetic aspects of electronic structure in a rather direct and detailed way. This is demonstrated by a comparison of experimental data for 5d impruities in Fe with corresponding theoretical data, obtained by using a spin-polarized relativistic multiple-scattering formalism. The spectra calculated for the L2 and L3 edges are found to be in excellent agreeement with experiment. It is shown that a very reliable estimate for the local spin magnetic moments of the 5d atoms can be deduced from the experimental spectra. This is not possible in the case of pure Gd, although our calculations give a very satisfying description for the various L-edge spectra of this f-electron metal. (orig.).

1991-01-01

 
 
 
 
81

Electronic structure of MoSe2, MoS2, and WSe2. I. Band-structure calculations and photoelectron spectroscopy  

Science.gov (United States)

The band structures of the semiconducting layered compounds MoSe2, MoS2, and WSe2 have been calculated self-consistently with the augmented-spherical-wave method. Angle-resolved photoelec- tron spectroscopy of MoSe2 using He i, He ii, and Ne i radiation, and photon-energy-dependent normal-emission photoelectron spectroscopy using synchrotron radiation, show that the calculational results give a good description of the valence-band structure. At about 1 eV below the top of the valence band a dispersionless state was measured, almost completely of Mo 4d character. Such a state, which is not predicted by band-structure calculations, has also been observed in metallic layered compounds. Suggestions are given for the explanation of this phenomenon.

Coehoorn, R.; Haas, C.; Dijkstra, J.; Flipse, C. J. F.; de Groot, R. A.; Wold, A.

1987-04-01

82

A band Lanczos approach for calculation of vibrational coupled cluster response functions: simultaneous calculation of IR and Raman anharmonic spectra for the complex of pyridine and a silver cation.  

UK PubMed Central (United Kingdom)

We describe new methods for the calculation of IR and Raman spectra using vibrational response theory. Using damped linear response functions that incorporate a Lorentzian line-shape function from the outset, it is shown how the calculation of Raman spectra can be carried out through the calculation of a set of vibrational response functions in the same manner as described previously for IR spectra. The necessary set of response functions can be calculated for both vibrational coupled cluster (VCC) and vibrational configuration interaction (VCI) anharmonic vibrational wave-functions. For the efficient and simultaneous calculation of the full set of necessary response functions, a non-hermitian band Lanczos algorithm is implemented for VCC, and a hermitian band Lanczos algorithm is implemented for VCI. It is shown that the simultaneous calculation of several response functions is often advantageous. Sample calculations are presented for pyridine and the complex between pyridine and the silver cation.

Godtliebsen IH; Christiansen O

2013-07-01

83

A Formulation for the Static Permittivity of Water and Steam at Temperatures from 238 K to 873 K at Pressures up to 1200 MPa, Including Derivatives and Debye Hueckel Coefficients  

International Nuclear Information System (INIS)

A new formulation is presented of the static relative permittivity or dielectric constant of water and steam, including supercooled and supercritical states. The range is from 238 K to 873 K, at pressures up to 1200 MPa. The formulation is based on the ITS-90 temperature scale. It correlates a selected set of data from a recently published collection of all experimental data. The set includes new data in the liquid water and the steam regions that have not been part of earlier correlations. The physical basis for the formulation is the so-called g-factor in the form proposed by Harris and Alder. An empirical 12-parameter form for the g-factor as a function of the independent variables temperature and density is used. For the conversion of experimental pressures to densities, the newest formulation of the equation of state of water on the ITS-90, prepared by Wagner and Pruss, has been used. All experimental data are compared with the formulation. The reliability of the new formulation is assessed in all subregions. Comparisons with previous formulations are presented. Auxiliary dielectric-constant formulations as functions of temperature are included for the saturated vapor and liquid states. The pressure and temperature derivatives of the dielectric constant and the Debye endash Hueckel limiting-law slopes are calculated, their reliability is estimated, and they are compared with experimentally derived values and with previous correlations. All equations are given in this paper, along with short tables. An implementation of this formulation for the dielectric constant is available on disk [A. H. Harvey, A. P. Peskin, and S. A. Klein, NIST/ASME Steam Properties, NIST Standard Reference Database 10, Version 2.1, Standard Reference Data Program, NIST, Gaithersburg, MD (1997)]. copyright 1997 American Institute of Physics and American Chemical Society

1997-01-01

84

Calculation of the composition dependence of the energy band gap in semiconducting solid solutions based on zinc, cadmium, and lead chalcogenides  

Energy Technology Data Exchange (ETDEWEB)

Our study, based on interpolation methods, looked at the composition dependence of the energy band gap E/sub g/ in ternary and quaternary semiconducting solid solutions based on zinc, cadmium, and lead chalcogenides. Change in the energy band gap dependent on composition is not linear in most ternary systems. The nonlinear character of the composition dependent energy band gap for solid solutions based on A/sup II/B/sup VI/compounds may be explained from the point of view of a psuedopotential model. In the case of four-component solid solutions, we made use of a diagram of the composition dependence of the energy band gap in quaternary semiconductors. We calculated the energy band gap dependence on composition for a wide range of ternary compounds based on zinc, cadmium, and lead chalcogenides.

Galeeva, F.U.; Tarzimanov, K.D.; Akhmetshin, I.K.

1988-08-01

85

Calculation of the band structure of GdCo2, GdRh2 e GdIr2 by the APW method  

International Nuclear Information System (INIS)

[en] The band structure of GdCo2, GdRh2, GdIr2 has been calculated by the APW method. A histogram of the density of states is presented for each compound. The bands are transition-metal-like, with s-d hybridization near the Fermi level. The 5d character near the Fermi level increases as one goes from Co to Ir

1974-01-01

86

Energy band structure of LaCuOCh (Ch = S, Se and Te) calculated by the full-potential linearized augmented plane-wave method  

International Nuclear Information System (INIS)

Energy band diagrams of LaCuOCh (Ch = S, Se and Te) were calculated by a full-potential linearized augmented plane-wave method. The calculations, based on the local density approximation with/without an on-site Coulomb repulsion parameter, were to examine the energy levels of La 4f states. The results of the calculations showed that the on-site correlation parameter is necessary for evaluating the energy levels of La 4f states appropriately. The calculations for LaCuOCh with the on-site correlation parameter revealed that LaCuOS and LaCuOSe have almost the same energy band structure with a direct allowed-type band gap, while LaCuOTe has significantly different conduction band structure that exhibits an indirect-type band gap. This difference in electronic structure between LaCuOCh (Ch = S, Se and Te) is consistent with the observed optical properties of these materials.

2004-07-21

87

A plane-wave expansion method based on the effective medium theory for calculating the band structure of a two-dimensional photonic crystal  

Energy Technology Data Exchange (ETDEWEB)

A plane-wave expansion method based on the effective medium theory for calculating the band structure of a two-dimensional photonic crystal is presented. Compared to two other plane-wave expansion methods, the present method has a faster convergence and advantage to calculate the band structure for complicated structures. Using the present fast method, a photonic crystal with a large complete bandgap {delta}{omega}=0.1111(2{pi}c/a) (a is the lattice constant) is found. The designed photonic crystal is formed by a triangular array of elliptic air holes in GaAs medium.

Xiao, Sanshui; Shen, Linfang; He, Sailing

2003-06-23

88

A plane-wave expansion method based on the effective medium theory for calculating the band structure of a two-dimensional photonic crystal  

International Nuclear Information System (INIS)

A plane-wave expansion method based on the effective medium theory for calculating the band structure of a two-dimensional photonic crystal is presented. Compared to two other plane-wave expansion methods, the present method has a faster convergence and advantage to calculate the band structure for complicated structures. Using the present fast method, a photonic crystal with a large complete bandgap ??=0.1111(2?c/a) (a is the lattice constant) is found. The designed photonic crystal is formed by a triangular array of elliptic air holes in GaAs medium.

2003-06-23

89

Odd-odd interacting-boson-approximation calculations: Experimental agreement for doubly decoupled and highly distorted bands in sup 176--180 Re  

Energy Technology Data Exchange (ETDEWEB)

We present results of interacting-boson-fermion-fermion approximation (IBFFA) calculations for deformed odd-odd {sup 176}Re and {sup 178}Re. Such calculations yield accurate structural information for many different rotational band types, including highly distorted and doubly decoupled bands. Thus, they can help in interpreting experimental data, predicting spin-parity assignments that agree with those obtained by other methods, and giving rather good predictions for interband transition energies. We also compare our previously published IBFFA predictions for {sup 180}Re with new experimental data.

Chou, W.; Olivier, W.A.; McHarris, W.C. (National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI (USA) Departments of Chemistry, Michigan State University, East Lansing, MI (USA) Physics/Astronomy, Michigan State University, East Lansing, MI (USA)); Scholten, O. (Kernfysisch Versneller Instituut, 9747 AA Groningen (The Netherlands))

1990-07-01

90

Odd-odd interacting-boson-approximation calculations: Experimental agreement for doubly decoupled and highly distorted bands in 176--180Re  

International Nuclear Information System (INIS)

[en] We present results of interacting-boson-fermion-fermion approximation (IBFFA) calculations for deformed odd-odd 176Re and 178Re. Such calculations yield accurate structural information for many different rotational band types, including highly distorted and doubly decoupled bands. Thus, they can help in interpreting experimental data, predicting spin-parity assignments that agree with those obtained by other methods, and giving rather good predictions for interband transition energies. We also compare our previously published IBFFA predictions for 180Re with new experimental data

1990-01-01

91

Nudged elastic band calculation of minimal energy paths for the conformational change of a GG non-canonical pair.  

UK PubMed Central (United Kingdom)

The nudged elastic band (NEB) technique has been implemented in AMBER to calculate low-energy paths for conformational changes. A novel simulated annealing protocol that does not require an initial hypothesis for the path is used to sample low-energy paths. This was used to study the conformational change of an RNA cis Watson-Crick/Hoogsteen GG non-canonical pair, with one G syn around the glycosidic bond and the other anti. A previous solution structure, determined by NMR-constrained modeling, demonstrated that the GG pairs change from (syn)G-(anti)G to (anti)G-(syn)G in the context of duplex r(GCAGGCGUGC) on the millisecond timescale. The set of low-energy paths found by NEB show that each G flips independently around the glycosidic bond, with the anti G flipping to syn first. Guanine bases flip without opening adjacent base-pairs by protruding into the major groove, accommodated by a transient change by the ribose to C2'-exo sugar pucker. Hydrogen bonds between bases and the backbone, which lower the energetic barrier to flipping, are observed along the path. The results show the plasticity of RNA base-pairs in helices, which is important for biological processes, including mismatch repair, protein recognition, and translation. The modeling of the GG conformational change also demonstrates that NEB can be used to discover non-trivial paths for macromolecules and therefore NEB can be used as an exploratory method for predicting putative conformational change paths.

Mathews DH; Case DA

2006-04-01

92

[ital Ab] [ital initio] calculation of band structure, x-ray emission, quantum yield, and electron-energy-loss spectra of hexagonal boron nitride  

Energy Technology Data Exchange (ETDEWEB)

The band structure of hexagonal boron nitride (BN) has been calculated using an [ital ab] [ital initio] linear combination of pseudoatomic-orbitals method. The calculated band structure confirms a previous finding that this material is an indirect band-gap insulator and has two empty interlayer bands. Projected densities of states are compared with the experimental x-ray emission spectra of B and N [ital K] edges and the agreement is good. This good agreement between the present ground-state calculation and the experimental x-ray emission spectra supports our previous finding that there should be very little valence electron relaxation effect on x-ray emission spectra. A real-space Green's function technique and the [ital Z]+1 approximation have been used to calculate the exciton spectra of B and N [ital K] edges. The first peak at 192 eV in B [ital K] edge is found to be a bound exciton with a binding energy of 1.7[plus minus]0.4 eV. Only resonance is found for the N [ital K] edge. The calculated exciton spectra agree very well with the experimental quantum-yield and electron-energy-loss spectra.

Ma, H.; Lin, S.H.; Carpenter, R.W.; Rice, P.; Sankey, O.F. (Center for Solid State Science, Arizona State University, Tempe, Arizona 85287-1704 (United States))

1993-06-01

93

Ab initio calculation of band structure, x-ray emission, quantum yield, and electron-energy-loss spectra of hexagonal boron nitride  

International Nuclear Information System (INIS)

The band structure of hexagonal boron nitride (BN) has been calculated using an ab initio linear combination of pseudoatomic-orbitals method. The calculated band structure confirms a previous finding that this material is an indirect band-gap insulator and has two empty interlayer bands. Projected densities of states are compared with the experimental x-ray emission spectra of B and N K edges and the agreement is good. This good agreement between the present ground-state calculation and the experimental x-ray emission spectra supports our previous finding that there should be very little valence electron relaxation effect on x-ray emission spectra. A real-space Green's function technique and the Z+1 approximation have been used to calculate the exciton spectra of B and N K edges. The first peak at 192 eV in B K edge is found to be a bound exciton with a binding energy of 1.7±0.4 eV. Only resonance is found for the N K edge. The calculated exciton spectra agree very well with the experimental quantum-yield and electron-energy-loss spectra

1993-06-01

94

Surface alloying in the Sn/Ni(111) system studied by synchrotron radiation photoelectron valence band spectroscopy and ab-initio density of states calculations  

Energy Technology Data Exchange (ETDEWEB)

Photoelectron spectroscopy using synchrotron radiation and ab-initio electronic structure calculations were used in order to describe the fine structure of the valence band in the Sn/Ni(111) system. The characteristic contributions of each metal in the valence band photoemission spectra obtained with a photon energy of 80 eV and their changes upon the formation of the ({radical}3 x {radical}3)R30{sup o} Sn/Ni(111) surface alloy were also born out in the calculated density-of-states curves in fair agreement with the experiments. The Sn-Ni interaction leads to a considerable broadening of the valence band width at the bimetallic surfaces.

Karakalos, S.; Ladas, S. [Department of Chemical Engineering, University of Patras and FORTH/ICE-HT, POB 1414, 26504 Rion (Patras) (Greece); Janecek, P.; Sutara, F.; Nehasil, V. [Department of Electronic and Vacuum Physics, Charles University, V.Holesovickach 2, 18000 Prague 8 (Czech Republic); Tsud, N. [Sincrotrone Trieste, Strada Statale 14, km 163.5, 34012 Basovizza-Trieste (Italy); Prince, K. [Sincrotrone Trieste, Strada Statale 14, km 163.5, 34012 Basovizza-Trieste (Italy); INFM, Laboratorio TASC, in Area Science Park, Strada Statale 14, km 163.5, 34012 Basovizza-Trieste (Italy); Matolin, V. [Department of Electronic and Vacuum Physics, Charles University, V.Holesovickach 2, 18000 Prague 8 (Czech Republic); Chab, V. [Institute of Physics, Czech Academy of Sciences, Cucrovarnicka 10, 16200 Prague (Czech Republic); Papanicolaou, N.I. [Department of Physics, University of Ioannina, P.O. Box 1186, 45110 Ioannina (Greece)], E-mail: nikpap@uoi.gr; Dianat, A.; Gross, A. [Institute of Theoretical Chemistry, University of Ulm, D-89069 Ulm (Germany)

2008-03-31

95

Analysis of the partially-filled d-block band of the layered metal LaI[sub 2] and probable cause for the absence of structural instability  

Energy Technology Data Exchange (ETDEWEB)

The electronic band structure of the layered metal LaI[sub 2] was calculated by employing the extended Hueckel tight binding method, and the orbital compositions of the partially filled bands were analyzed. The partially-filled bands are mainly composed of the La z[sup 2] and x[sup 2]-y[sup 2] orbitals, but their relative contributions depend strongly on the wave vectors. Thus the Fermi surface is strongly warped so that LaI[sub 2] does not possess an electronic instability typically expected for a system with a nested Fermi surface. The absence of a metal atom clustering in LaI[sub 2] was discussed from the viewpoints of the strain and the preferential direction of metal-metal bonding of the square lattice. The Fermi surface has the shape of a warped-square cylinder running along the [Sigma] [yields] Z direction (i.e., perpendicular to the layer), and the cross-sectional are (taken perpendicular to [Sigma] [yields] Z) oscillates between two slightly different values, so that the magnetoresistance of LaI[sub 2] is predicted to exhibit angle-dependent oscillations.

Canadell, E. (Universite de Paris, Orsay (France)); Whangbo, M.H. (North Carolina State Univ., Raleigh, NC (United States))

1994-01-19

96

Band structure of MoS_2, MoSe_2, and alpha-MoTe_2 Angle-resolved photoelectron spectroscopy and ab-initio calculations  

CERN Multimedia

In this work the complete valence-band structure of the molybdenum dichalcogenides MoS_2, MoSe_2, and alpha-MoTe_2 is presented and discussed in comparison. The valence bands have been studied using both angle-resolved photoelectron spectroscopy (ARPES) with synchrotron radiation, as well as, ab-initio band-structure calculations. The ARPES measurements have been carried out in the constant-final-state (CFS) mode. The results of the calculations show in general very good agreement with the experimentally determined valence-band structures allowing for a clear identification of the observed features. The dispersion of the valence bands as a function of the perpendicular component k_perp of the wave vector reveals a decreasing three-dimensional character from MoS_2 to alpha-MoTe_2 which is attributed to an increasing interlayer distance in the three compounds. The effect of this k_perp dispersion on the determination of the exact dispersion of the individual states as a function of k_parallel is discussed. By p...

Böker, T; Müller, A; Janowitz, C; Manzke, R; Voss, D; Krüger, P; Mazur, A I; Pollmann, J; Boeker, Th.

2001-01-01

97

Theoretical calculations of the optical band positions and spin-Hamiltonian parameters for Cr3+ ions in Y2Ti2O7 crystal  

Science.gov (United States)

The optical band positions and spin-Hamiltonian parameters (g factors g?g? and zero-field splitting D) for the trigonal Cr3+ centers in Y2Ti2O7 crystal are calculated from the complete diagonalization (of energy matrix) method based on the two-spin-orbit-parameter model. In the calculations, the contributions to spectral data from both the spin-orbit parameter of central dn ion and that of ligand ion are considered and the crystal field parameters used are estimated from the superposition model. The calculated results are in reasonable agreement with the experimental values. The defect structures of Cr3+ center is suggested.

Yang, Mei; Yu-Guang, Yang; Wen-Chen, Zheng

2012-09-01

98

Band-structure calculations of noble-gas and alkali halide solids using accurate Kohn-Sham potentials with self-interaction correction  

International Nuclear Information System (INIS)

[en] The optimized-effective-potential (OEP) method and a method developed recently by Krieger, Li, and Iafrate (KLI) are applied to the band-structure calculations of noble-gas and alkali halide solids employing the self-interaction-corrected (SIC) local-spin-density (LSD) approximation for the exchange-correlation energy functional. The resulting band gaps from both calculations are found to be in fair agreement with the experimental values. The discrepancies are typically within a few percent with results that are nearly the same as those of previously published orbital-dependent multipotential SIC calculations, whereas the LSD results underestimate the band gaps by as much as 40%. As in the LSD---and it is believed to be the case even for the exact Kohn-Sham potential---both the OEP and KLI predict valence-band widths which are narrower than those of experiment. In all cases, the KLI method yields essentially the same results as the OEP

1991-11-15

99

Band-structure calculations of noble-gas and alkali halide solids using accurate Kohn-Sham potentials with self-interaction correction  

Energy Technology Data Exchange (ETDEWEB)

The optimized-effective-potential (OEP) method and a method developed recently by Krieger, Li, and Iafrate (KLI) are applied to the band-structure calculations of noble-gas and alkali halide solids employing the self-interaction-corrected (SIC) local-spin-density (LSD) approximation for the exchange-correlation energy functional. The resulting band gaps from both calculations are found to be in fair agreement with the experimental values. The discrepancies are typically within a few percent with results that are nearly the same as those of previously published orbital-dependent multipotential SIC calculations, whereas the LSD results underestimate the band gaps by as much as 40%. As in the LSD---and it is believed to be the case even for the exact Kohn-Sham potential---both the OEP and KLI predict valence-band widths which are narrower than those of experiment. In all cases, the KLI method yields essentially the same results as the OEP.

Li, Y.; Krieger, J.B. (Department of Physics, Brooklyn College, City University of New York, Brooklyn, New York 11210 (United States)); Norman, M.R. (Material Sciences Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)); Iafrate, G.J. (U.S. Army Research Office, Research Triangle Park, North Carolina 27709-2211 (United States))

1991-11-15

100

First-principles calculation of the band gap of AlxGa1¡-xN and InxGa1¡-xN  

Directory of Open Access Journals (Sweden)

Full Text Available Ab-initio calculations of the band gap variation of AlxGa1¡xN and InxGa1¡xN ternary compounds were carried out using the Full-Potential Linearized Augmented Plane Waves (FLAPW) method, within the Density Functional Theory (DFT). These nitrides were modeled in their wurtzite structure using the supercell method, for concentrations x = 0, 0.25, 0.50, 0.75 and 1.0. To optimize the cell parameters of the binary compounds we used the PBE96 (Perdew et al., Phys. Rev. Lett. 77 (1996) 3865) exchange correlation functional. For the band structure calculations, we used both PBE96 and EV93 (Engel et al., Phys. Rev. B 47 (1993) 13164) exchange correlation functionals. We considered experimental and calculated (with PBE96) lattice parameters to work out the electronic properties. We found that the fundamental gap is direct in all compounds. The calculation with EV93 functional gives a better band gap estimation for binary nitrides. The bowing parameter was also estimated obtaining the values b = 0.74 eV for AlxGa1¡xN and b = 2.12 eV for InxGa1¡xN.

Roberto Núñez-González; Armando Reyes-Serrato; Alvaro Posada-Amarillas; Donald H. Galván

2008-01-01

 
 
 
 
101

Hopping and band mobilities of pentacene, rubrene, and 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) from first principle calculations.  

UK PubMed Central (United Kingdom)

Hopping and band mobilities of holes in organic semiconductors at room temperature were estimated from first principle calculations. Relaxation times of charge carriers were evaluated using the acoustic deformation potential model. It is found that van der Waals interactions play an important role in determining accurate relaxation times. The hopping mobilities of pentacene, rubrene, and 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) in bulk single crystalline structures were found to be smaller than 4 cm(2)?Vs, whereas the band mobilities were estimated between 36 and 58 cm(2)?Vs, which are close to the maximum reported experimental values. This strongly suggests that band conductivity is dominant in these materials even at room temperature.

Kobayashi H; Kobayashi N; Hosoi S; Koshitani N; Murakami D; Shirasawa R; Kudo Y; Hobara D; Tokita Y; Itabashi M

2013-07-01

102

Absorption cross section of ozone isotopologues calculated with the multiconfiguration time-dependent hartree (MCTDH) method: I. The Hartley and Huggins bands.  

UK PubMed Central (United Kingdom)

The absorption cross sections of 18 isotopologues of the ozone molecule have been calculated in the range of the Hartley-Huggins bands (27000-55000 cm(-1)). All 18 possible ozone isotopologues made with (16)O, (17)O, and (18)O have been considered, with emphasis on those of geophysics interest like (16)O(3) (17)O(16)O(2), (16)O(17)O(16)O, (18)O(16)O(2), and (16)O(18)O(16)O. We have used the MCTDH algorithm to propagate wavepackets. As an initial wavepacket, we took the vibrational ground state multiplied by the transition dipole moment surface. The cross sections have been obtained from the autocorrelation function of this wavepacket. Only two potential energy surfaces (PESs) and the corresponding transition dipole moment are involved in the calculation. The dissociating R state has been omitted. The calculations have been performed only for J = 0. The comparison with the experimental absorption cross sections of (16)O(3) and (18)O(3) has been performed after an empirical smoothing which mimics the rotational envelop. The isotopologue dependence of the cross sections of 18 isotopologues can be split into two energy ranges, (a) from 27000 to 32000 cm(-1), the Huggins band, which is highly structured, and (b) from 32000 to 55000 cm(-1), the main part of the cross section which has a bell shape, the Hartley band. This bell-shaped envelop has been characterized by a new analytic model depending on only four parameters, amplitude, center, width, and asymmetry. The isotopologue dependence of these parameters reveals the tiny differences between the absorption cross sections of the various isotopologues. In contrast to the smooth shape of the Hartley band, the Huggins band exhibits pronounced vibrational structures and therefore shows large isotopologue differences which may induce a significant isotopologue dependence of the ozone photodissociation rates under actinic flux.

Ndengué SA; Gatti F; Schinke R; Meyer HD; Jost R

2010-09-01

103

Band-edge ultrafast pump-probe spectroscopy of core/shell CdSe/CdS rods: assessing electron delocalization by effective mass calculations.  

Science.gov (United States)

CdSe/CdS dot/rods nanocrystals show interesting physical properties related to the band-alignment at the hetero-interface, which controls the band-edge electron delocalization over the rods. Here the differential transmission spectra of CdSe/CdS nanorod samples with different core sizes have been measured using excitation resonant to the core transition. The photo bleaching ratio between dot and rod transitions increases with the dot size, indicating a trend towards electron localization. This trend has been further quantified by performing effective mass calculations in which the conduction band misalignment was varied in order to reproduce the observed bleaching feature ratio. The best agreement was found for negligible conduction band misalignment for small dots of around 2.3 nm in diameter, and about -0.1 eV misalignment was estimated for the larger dots, above 3.5 nm in diameter. This shows that the band misalignment might be dependent on the geometry of the system, and we argue that this might be related to different strain developed at the hetero-interface. PMID:22523752

Lupo, Maria Grazia; Scotognella, Francesco; Zavelani-Rossi, Margherita; Lanzani, Guglielmo; Manna, Liberato; Tassone, Francesco

2012-04-20

104

Band-edge ultrafast pump-probe spectroscopy of core/shell CdSe/CdS rods: assessing electron delocalization by effective mass calculations.  

UK PubMed Central (United Kingdom)

CdSe/CdS dot/rods nanocrystals show interesting physical properties related to the band-alignment at the hetero-interface, which controls the band-edge electron delocalization over the rods. Here the differential transmission spectra of CdSe/CdS nanorod samples with different core sizes have been measured using excitation resonant to the core transition. The photo bleaching ratio between dot and rod transitions increases with the dot size, indicating a trend towards electron localization. This trend has been further quantified by performing effective mass calculations in which the conduction band misalignment was varied in order to reproduce the observed bleaching feature ratio. The best agreement was found for negligible conduction band misalignment for small dots of around 2.3 nm in diameter, and about -0.1 eV misalignment was estimated for the larger dots, above 3.5 nm in diameter. This shows that the band misalignment might be dependent on the geometry of the system, and we argue that this might be related to different strain developed at the hetero-interface.

Lupo MG; Scotognella F; Zavelani-Rossi M; Lanzani G; Manna L; Tassone F

2012-05-01

105

Electronic structure and optical absorption bands of the U center in alkaline earth fluorides calculated by the SCF-MSX? method  

International Nuclear Information System (INIS)

[en] The self-consistent-field multiple-scattering method in the X? approximation is used to calculate the electronic structure and the optical transition energies of the U center in CaF2, SrF2 and BaF2. The very good agreement obtained between the experimental and theoretical results concerning the optical bands indicates that the scheme used is convenient to treat this type of defect

1976-01-01

106

Band gap engineering of (N, Ta)-codoped TiO2 : a first-principles calculation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The electronic properties and photocatalytic activity of X (N, C) / transition metal (TM=Ta, Hf, Fe) – codoped anatase TiO2 have been investigated using density functional theory. It was found that only the (N, Ta)-codoping case narrows the band gap significantly by about 0.48 eV, driven by the cont...

Long, Run; English, Niall J.

107

Application of high precision band structure calculations to the equation of state for beryllium oxide: SESAME equation of state number 7612  

Energy Technology Data Exchange (ETDEWEB)

High precision electronic band structure calculations for BeO have revealed a large volume discontinuity structural phase transition on the 0 K isotherm at about 1 Mbar. Although, this transition has not been observed experimentally, the accuracy of the calculations is such that the existence of this transition is unambiguous. A transition of this magnitude is likely to have a substantial impact on hydrodynamic simulations involving BeO. Here we report the creation of a new SESAME equations of state for BeO which incorporates the effect of the theoretically determined phase transition. This new EOS will be added to the SESAME library as material number 7612.

Boettger, J.C.; Wills, J.M.

1992-03-01

108

LDA + GTB (generalized tight-binding) method for the electronic structure calculations of strongly correlated electron systems: Application for the band structure calculations of p-type cuprates  

International Nuclear Information System (INIS)

Mean-field theory of the non-superconducting phase of the high-Tc cuprates is formulated within the effective t-t'-t''-J model with three-site correlated hoppings. This model with the ab initio calculated parameters results from the LDA + GTB method. The static spin and kinematical correlation functions beyond Hubbard I approximation are calculated self-consistently taking into account hoppings to the first, the second, and the third neighboring sites, as well as the three-site correlated hoppings. The obtained Fermi surface evolves from hole-pockets at low-doping to large hole-type Fermi surface at higher doping concentrations. Calculated doping dependence of the nodal Fermi velocity, the effective mass and the chemical potential shift are in good agreement with experimental data.

2007-09-01

109

Molecular orbital calculations on transition metal clusters  

Energy Technology Data Exchange (ETDEWEB)

Transition metal clusters have been the subject of experimental and theoretical interest due to their catalytic activity, as well as their unusual physical properties. Semi-empirical extended Hueckel molecular orbital calculations are presented for a series of small metal clusters with nuclearity ranging from 3 to 6. Naked and carbonylated clusters of Fe, Ru, and Os are studied. The charge transfer between ligands shell and metal core is found to be a function of nuclearity, CO coordination and the chemical species forming the bare cluster. The observed magnetic properties of these systems are discussed in terms of their electronic structure and CO-metal charge transfer.

Santos, M.C. dos; Albino O de Aguiar, J.

1989-06-01

110

Estimation of forbidden band widths in CuGa(SxSe1-x)2 solid solutions on calculated total densities of electronic states  

International Nuclear Information System (INIS)

Using method of local coherent potential one calculated the local partial and total densities of electronic states of CuGa(SxSe1-x)2 solid solutions (x = 0, 0.17, 0.33, 0.50, 0.67, 0.83, 1.0) and in approximation of a virtual crystal. Parameters of the crystalline lattice of the investigated chalcopyrite solid solutions were calculated using the Jaffe and Zunger theory with application of tetrahedral Poling radii. Evaluation of Eg linear forbidden band width shows Eg linear dependence on sulfur x concentration in anion sublattice. It corresponds to the experimental data, but Eg values in the calculations turned to be by 0.5 eV smaller than the experimental ones

2001-01-01

111

Local ab initio methods for calculating optical band gaps in periodic systems. I. Periodic density fitted local configuration interaction singles method for polymers.  

UK PubMed Central (United Kingdom)

We present a density fitted local configuration interaction singles (CIS) method for calculating optical band gaps in 1D-periodic systems. The method is based on the Davidson diagonalization procedure, carried out in the reciprocal space. The one-electron part of the matrix-vector products is also evaluated in the reciprocal space, where the diagonality of the Fock matrix can be exploited. The contraction of the CIS vectors with the two electron integrals is performed in the direct space in the basis of localized occupied (Wannier) and virtual (projected atomic) orbitals. The direct space approach allows to utilize the sparsity of the integrals due to the local representation and locality of the exciton. The density fitting approximation employed for the two electron integrals reduces the nominal scaling with unit cell size to O(N(4)). Test calculations on a series of prototypical systems demonstrate that the method in its present stage can be used to calculate the excitonic band gaps of polymers with up to a few dozens of atoms in the cell. The computational cost depends on the locality of the exciton, but even relatively delocalized excitons occurring in the polybiphenyl in the parallel orientation, can be routinely treated with this method.

Lorenz M; Usvyat D; Schütz M

2011-03-01

112

Band gap engineering of compensated (N, H) and (C, 2H) codoped anatase TiO2: A first-principles calculation  

Science.gov (United States)

The electronic structures and optical properties of non-compensated (C, H)-, compensated (N, H)- and (C, 2H)-doped anatase TiO2 have been investigated using spin-polarized density functional theory. The calculated results indicated that compensated (N, H) codoped TiO2 exhibited the enhanced optical absorption under visible-light irradiation in comparison with N doped TiO2 and pure TiO2. Compensated (C, 2H) codoped TiO2 may also be a good candidate for visible-light photocatalyst materials due to the band gap narrowing significantly and the elimination of some local states.

Li, Min; Zhang, Junying; Guo, Dong; Zhang, Yue

2012-06-01

113

Photolysis rate coefficients in the upper atmosphere: Effect of line by line calculations of the O2 absorption cross section in the Schumann-Runge bands  

International Nuclear Information System (INIS)

A line by line (LBL) method to calculate highly resolved O2 absorption cross sections in the Schumann-Runge (SR) bands region was developed and integrated in the widely used Tropospheric Ultraviolet Visible (TUV) model to calculate accurate photolysis rate coefficients (J values) in the upper atmosphere at both small and large solar zenith angles (SZA). In order to obtain the O2 cross section between 49,000 and 57,000cm-1, an algorithm which considers the position, strength, and half width of each spectral line was used. Every transition was calculated by using the HIgh-resolution TRANsmission molecular absorption database (HITRAN) and a Voigt profile. The temperature dependence of both the strength and the half widths was considered within the range of temperatures characteristic of the US standard atmosphere, although the results show a very good agreement also at 79K. The cross section calculation was carried out on a 0.5cm-1 grid and the contributions from all the lines lying at +/-500cm-1 were considered for every wavelength. Both the SR and the Herzberg continuums were included. By coupling the LBL method to the TUV model, full radiative transfer calculations that compute J values including Rayleigh scattering at high altitudes and large SZA can now be done. Thus, the J values calculations were performed for altitudes from 0 to 120km and for SZA up to 89o. The results show, in the JO2 case, differences of more than +/-10% (e.g. at 96km and 30o) when compared against the last version of the TUV model (4.4), which uses the Koppers and Murtagh parameterization for the O2 cross section. Consequently, the J values of species with cross sections overlapping the SR band region show variable differences at lower altitudes. Although many species have been analyzed, the results for only four of them (O2, N2O, HNO3, CFC12) are presented. Due to the fact that the HNO3 absorption cross section extends up to 350nm this molecule was used to verify the consistency of the new TUV-LBL at lower altitudes. Thus, it shows differences up to 5.7% at 21km but 0% in the troposphere. Because of the more accurate consideration of the Rayleigh scattering the distribution of the actinic flux in its direct and diffuse components (in the SR bands wavelength interval) is also modified

2007-01-01

114

A modified band approach for the accurate calculation of on-line photolysis rates in stratospheric-tropospheric Chemical Transport Models  

Directory of Open Access Journals (Sweden)

Full Text Available Here we present an efficient and accurate method for the online calculation of photolysis rates relevant to both the stratosphere and troposphere for use in global Chemistry Transport Models. The method is a modified version of the band model introduced by Landgraf and Crutzen (1998) which has been updated to improve the performance of the approach for solar zenith angles >75° without the use of any implicit parameterisations. For this purpose, additional sets of band parameters have been defined for instances where the incident angle of the light beam is between 75–93°, in conjunction with a scaling component for the far UV region of the spectrum (?=176.6–202.0 nm). For incident angles between 85–93° we introduce a modification for pseudo-sphericity that improves the accuracy of the 2-stream approximation. We show that this modified version of PIFM is accurate for angles <93° by comparing the resulting height resolved actinic fluxes with a recently developed full spherical reference model. We also show that the modified band method is more accurate than the original, with errors generally being ±10% throughout the atmospheric column for a diverse range of chemical species. Moreover, we perform certain sensitivity studies that indicate it is robust and performs well over a wide range of conditions relevant to the atmosphere.

J. E. Williams; J. Landgraf; A. Bregman; H. Walter

2006-01-01

115

A modified band approach for the accurate calculation of on-line photolysis rates in stratospheric-tropospheric Chemical Transport Models  

Science.gov (United States)

Here we present an efficient and accurate method for the online calculation of photolysis rates relevant to both the stratosphere and troposphere for use in global Chemistry Transport Models. The method is a modified version of the band model introduced by Landgraf and Crutzen (1998) which has been updated to improve the performance of the approach for solar zenith angles >75° without the use of any implicit parameterisations. For this purpose, additional sets of band parameters have been defined for instances where the incident angle of the light beam is between 75-93°, in conjunction with a scaling component for the far UV region of the spectrum (?=176.6-202.0 nm). For incident angles between 85-93° we introduce a modification for pseudo-sphericity that improves the accuracy of the 2-stream approximation. We show that this modified version of PIFM is accurate for angles <93° by comparing the resulting height resolved actinic fluxes with a recently developed full spherical reference model. We also show that the modified band method is more accurate than the original, with errors generally being ±10% throughout the atmospheric column for a diverse range of chemical species. Moreover, we perform certain sensitivity studies that indicate it is robust and performs well over a wide range of conditions relevant to the atmosphere.

Williams, J. E.; Landgraf, J.; Bregman, A.; Walter, H.

2006-05-01

116

Prediction of the Band Offsets at the CdS/Cu2ZnSnS4 Interface Based on the First-Principles Calculation  

Science.gov (United States)

The valance band offset ? Ev for the CdS/Cu2ZnSnS4 heterojunction is obtained on the basis of the first-principles pseudopotential method. Cu2ZnSnS4 is considered to crystallize in the kesterite structure. The total density of states and the local density of states for each atoms are calculated for the CdS(001)/Cu2ZnSnS4(001) supercell. There are two inequivalent interfaces between CdS and Cu2ZnSnS4 in the supercell, and different values of ? Ev are obtained for them, i.e., ? Ev1 = 1.1 eV and ? Ev2 = 1.6 eV. The corresponding conduction band offsets ? Ec are ? Ec1 = 0.2 eV and ? Ec2 = 0.7 eV with the conduction band minimum of Cu2ZnSnS4 higher than that of CdS.

Bao, Wujisiguleng; Ichimura, Masaya

2012-10-01

117

Combining GW calculations with exact-exchange density-functional theory: an analysis of valence-band photoemission for compound semiconductors  

International Nuclear Information System (INIS)

We report quasi-particle energy calculations of the electronic bandstructure as measured by valence-band photoemission for selected II-VI compounds and group III nitrides. By applying GW as perturbation to the ground state of the fictitious, non-interacting Kohn-Sham electrons of density-functional theory (DFT), we systematically study the electronic structure of zinc-blende GaN, ZnO, ZnS and CdS. Special emphasis is put on analysing the role played by the cation semicore d-electrons that are explicitly included as valence electrons in our pseudo-potential approach. Unlike in the majority of previous GW studies, which are almost exclusively based on ground state calculations in the local-density approximation (LDA), we combine GW with exact-exchange DFT calculations in the optimized-effective potential approach (OEPx). This is a much more elaborate and computationally expensive approach. However, we show that applying the OEPx approach leads to an improved description of the d-electron hybridization compared to the LDA. Moreover, we find that it is essential to use OEPx pseudo-potentials in order to treat core-valence exchange consistently. Our OEPx-based quasi-particle valence bandstructures are in good agreement with available photoemission data in contrast to the ones based on the LDA. We therefore conclude that for these materials, OEPx constitutes the better starting point for subsequent GW calculations.

2005-01-01

118

Valence bands of the Cu-III-VI2 chalcopyrites studied by photoemission spectra, X-ray emission spectra, and electronic structure calculations  

International Nuclear Information System (INIS)

Ultraviolet and X-ray excited photoemission spectra and Cu K?5 X-ray emission spectra are used to measure the valence band density of states in CuGaTe2 and CuInTe2. In both compounds the density of states exhibits five structures which are ascribed to Cu 3d-Te 5p hybridized states, Ga 4s/In 5s-Te 5p bonding states, and Te 5s states. The valence band density of states of all Ga- and In-containing Cu-III-VI2 is calculated in an atomic orbital basis with the noble metal d states explicitly included. The agreement between theory and experiment is good for CuGaTe2 and except the In 5s-VI p bonding states also for the Cu-In-VI2 chalcopyrites. Larger discrepancies between theory and experiment are found for CuGaS2 and CuGaSe2. (author)

1984-02-01

119

Exploring the structure of a photosynthetic model by quantum-chemical calculations and time-resolved Q-band electron paramagnetic resonance  

Energy Technology Data Exchange (ETDEWEB)

The structure of the covalent photosynthetic model system N,N,N{prime},N{double{underscore}prime}-tetraalkyl-p-phenylenediamine-zinc porphyrin-naphthoquinone (TAPD-ZnP-NQ) has been explored by using a combination of theoretical and experimental techniques. Structural information is extracted from high-level quantum-chemical ab initio calculations, which is a nontrivial task for a large molecule like TAPD-ZnP-NQ. The authors tackle this problem by dividing the model system into smaller molecular fragments, whose geometries can be optimized separately. The fragments are subsequently fitted together, thus providing an approximate structure of the entire model system. To verify this structure, time-resolved Q-band electron paramagnetic resonance (EPR) experiments on the light-induced radical pair TAPD{sup +} NQ{sup {minus}} is monitored at various static magnetic fields. Quantum beat oscillations are observed at early times after the laser pulse. These quantum beats are highly sensitive probes for the geometry of the underlying radical pair. From the good agreement between observed and simulated EPR time profiles, it was concluded that the ab initio calculations predict the correct geometry within the experimental precision.

Kiefer, A.M.; Kast, S.M.; Wasielewski, M.R.; Laukenmann, K.; Kothe, G.

1999-01-13

120

Investigation of high-k materials RScO{sub 3}(R=Sm,Gd,Dy) by XPS and band structure calculations  

Energy Technology Data Exchange (ETDEWEB)

There has been considerable interest in high-k-dielectrics rare earth oxides as replacement for SiO{sub 2} in advanced field-effect transistors (FETs). Promising candidates are the perovskites SmScO{sub 3}, GdScO{sub 3} and DyScO{sub 3}. A tendency towards antiferromagnetic ordering at low temperatures is observed for the high magnetic moments at rare earth atoms. We analyse the electronic structure of the single crystalline samples by means of X-ray photoelectron spectroscopy and firstprinciples theory. The electronic structure calculations are performed with the augmented plane waves method (WIEN2k code) of the density functional theory, taking into account the spin-orbit interaction and orbital-dependent potential (LDA+U). The calculated positions of the main features in the valence band agree with the XPS data, the underlying chemical bonding can be analysed in detail. Small differences in the electronic structure, resulting in different stability of ferro and antiferromagnetic configurations, are discussed.

Raekers, M.; Bartkowski, S.; Neumann, M. [Universitaet Osnabrueck, Fachbereich Physik, Osnabrueck (Germany); Kuepper, K.; Zhou, S.; Potzger, K. [FZ Dresden- Rossendorf, Dresden (Germany); Postnikov, A. [Universite Paul Verlaine, Metz (France); Uecker, R. [IKZ, Berlin (Germany)

2007-07-01

 
 
 
 
121

The band 12 issue in the electron momentum spectra of norbornane: a comparison with additional Green's Function calculations and ultraviolet photoemission measurements.  

Science.gov (United States)

In continuation of a recent study of the electronic structure of norbornane [J. Chem. Phys., 2004, 121, 10525] by means of electron momentum spectroscopy (EMS), we present Green's Function calculations of the ionization spectrum of this compound at the ADC(3) level using basis sets of varying quality, along with accurate evaluations at the CCSD(T) level of the vertical (26.5 eV) and adiabatic (22.1 eV) double ionization thresholds under C(2v) symmetry. The obtained results are compared with newly recorded ultraviolet photoemission spectra (UPS), up to binding energies of 40 eV. The theoretical predictions are entirely consistent with experiment and indicate that, in a vertical depiction of ionization, shake-up states at binding energies larger than approximately 26.5 eV tend to decay via emission of a second electron in the continuum. A band of s-type symmetry that has been previously seen at approximately 25 eV in the electron impact ionization spectra of norbornane is entirely missing in the UPS measurements and theoretical ADC(3) spectra. With regard to these results and to the time scales characterizing electron-electron interactions in EMS (10(-17) s) as compared with that (10(-13) s) of photon-electron interactions in UPS, and considering the p-type symmetry of the electron momentum distributions for the nearest 1b(1) and 1b(2) orbitals, this additional band can certainly not be due to adiabatic double ionization processes starting from the ground electronic state of norbornane, or to exceptionally strong vibronic coupling interactions between cationic states derived from ionization of the latter orbitals. It is therefore tentatively ascribed to autoionization processes via electronically excited and possibly dissociating states. PMID:16833755

Knippenberg, S; Deleuze, M S; Cleij, T J; François, J-P; Cederbaum, L S; Eland, J H D

2005-05-19

122

The application of the Modified Band Approach for the calculation of on-line photodissociation rate constants in TM5: implications for oxidative capacity  

Science.gov (United States)

A flexible and explicit on-line parameterization for the calculation of tropospheric photodissociation rate constants (J-values) has been integrated into the global Chemistry Transport Model TM5. Here we provide a comprehensive description of this Modified Band Approach (MBA) including details of the optimization procedure employed, the methodology applied for calculating actinic fluxes, the photochemical reaction data used for each chemical species, the aerosol climatology which is adopted and the parameterizations adopted for improving the description of scattering and absorption by clouds. The resulting J-values change markedly throughout the troposphere when compared to the offline approach used to date, with significant increases in the boundary layer and upper troposphere. Conversely, for the middle troposphere a reduction in the actinic flux results in a decrease in J-values. Integrating effects shows that application of the MBA introduces seasonal dependent differences in important trace gas oxidants. Tropospheric ozone (O3) changes by ±10% in the seasonal mean mixing ratios throughout the troposphere, especially over land. These changes and the perturbations in the photolysis rate of O3 induce changes of ±15% in tropospheric OH. In part this is due to an increase in the re-cycling efficiency of nitrogen oxides. The overall increase in northern hemispheric tropospheric ozone strengthens the oxidizing capacity of the troposphere significantly and reduces the lifetime of CO and CH4 by ~5 % and ~4%, respectively. Changes in the tropospheric CO burden, however, are limited to a few percent due to competing effects. Comparing the distribution of tropospheric ozone in the boundary layer and middle troposphere against observations in Europe shows there are improvements in the model performance during boreal winter in the Northern Hemisphere near regions affected by high nitrogen oxide emissions. Monthly mean total columns of nitrogen dioxide and formaldehyde also compare more favorably against OMI and SCIAMACHY total column observations.

Williams, J. E.; Strunk, A.; Huijnen, V.; van Weele, M.

2012-01-01

123

Cathode catalysts for fuel cell development: A theoretical study based on band structure calculations for tungsten nitride and cobalt tungsten nitrides  

Energy Technology Data Exchange (ETDEWEB)

Band structure calculations were performed for tungsten nitride, cobalt tungsten nitrides, and platinum slabs. The major requirements for the development of a superior cathode catalyst are: (1) that the Fermi level of the cathode catalyst is close to the energy level of the lowest unoccupied molecular orbital of O{sub 2}, the lowest unoccupied atomic orbital of an oxygen atom, and the lowest unoccupied atomic orbital of a hydrogen atom so that they can readily interact with one another; and (2) that the cathode catalysts have smaller {delta}E value which represent the difference between the Fermi level and the peak position of the density of states of the O{sub p} orbital of O{sub 2} adsorbed on the catalyst. The active site structures of cobalt tungsten nitrides for activation of the oxygen reduction reaction were found to have the surface structure of Co-O-Co, which lowered the unoccupied orbital of the oxygen atom to approximately that of the Fermi level. However, this structure concomitantly lowered the Fermi level, which resulted in an increase in {delta}E. Consequently, the optimal cathode catalyst regarding the surface conformation contains a Co-O-Co structure that is dispersed on the surface of the cobalt tungsten nitride. The cobalt tungsten oxynitride exhibited a catalytic activity for the oxygen reduction reaction. A linear dependence is observed between the {delta}E and the oxygen reduction reaction offset potentials of the tungsten nitride, cobalt tungsten nitride, cobalt tungsten oxynitride, and platinum.

Tominaga, Hiroyuki [Graduate School of Bio-applications and Systems Engineering, Tokyo University of Agriculture and Technology, 2-24 Nakamachi, Koganei, Tokyo 184-8588 (Japan)], E-mail: tomi@cc.tuat.ac.jp; Nagai, Masatoshi [Graduate School of Bio-applications and Systems Engineering, Tokyo University of Agriculture and Technology, 2-24 Nakamachi, Koganei, Tokyo 184-8588 (Japan)], E-mail: mnagai@cc.tuat.ac.jp

2009-11-01

124

Cathode catalysts for fuel cell development: A theoretical study based on band structure calculations for tungsten nitride and cobalt tungsten nitrides  

International Nuclear Information System (INIS)

Band structure calculations were performed for tungsten nitride, cobalt tungsten nitrides, and platinum slabs. The major requirements for the development of a superior cathode catalyst are: (1) that the Fermi level of the cathode catalyst is close to the energy level of the lowest unoccupied molecular orbital of O2, the lowest unoccupied atomic orbital of an oxygen atom, and the lowest unoccupied atomic orbital of a hydrogen atom so that they can readily interact with one another; and (2) that the cathode catalysts have smaller ?E value which represent the difference between the Fermi level and the peak position of the density of states of the Op orbital of O2 adsorbed on the catalyst. The active site structures of cobalt tungsten nitrides for activation of the oxygen reduction reaction were found to have the surface structure of Co-O-Co, which lowered the unoccupied orbital of the oxygen atom to approximately that of the Fermi level. However, this structure concomitantly lowered the Fermi level, which resulted in an increase in ?E. Consequently, the optimal cathode catalyst regarding the surface conformation contains a Co-O-Co structure that is dispersed on the surface of the cobalt tungsten nitride. The cobalt tungsten oxynitride exhibited a catalytic activity for the oxygen reduction reaction. A linear dependence is observed between the ?E and the oxygen reduction reaction offset potentials of the tungsten nitride, cobalt tungsten nitride, cobalt tungsten oxynitride, and platinum.

2009-11-01

125

Photodissociation of water. II. Wave packet calculations for the photofragmentation of H2O and D2O in the B~ band  

Science.gov (United States)

A complete three-dimensional quantum mechanical description of the photodissociation of water in the B~ band, starting from its rotational ground state, is presented. In order to include B~-X~ vibronic coupling and the B~-A~ Renner-Teller coupling, diabatic electronic states have been constructed from adiabatic electronic states and matrix elements of the electronic angular momentum operators, following the procedure developed by A. J. Dobbyn and P. J. Knowles [Mol. Phys. 91, 1107 (1997)], using the ab initio results discussed in the preceding paper. The dynamics is studied using wave packet methods, and the evolution of the time-dependent wave function is discussed in detail. Results for the H2O and D2O absorption spectra, OH(A)/OH(X) and OD(A)/OD(X) branching ratios, and rovibrational distributions of the OH and OD fragments are presented and compared with available experimental data. The present theoretical results agree at least qualitatively with the experiments. The calculations show that the absorption spectrum and the product state distributions are strongly influenced by long-lived resonances on the adiabatic B~ state. It is also shown that molecular rotation plays an important role in the photofragmentation process, due to both the Renner-Teller B~-X~ mixing, and the strong effect of out-of-plane molecular rotations (K>0) on the dynamics at near linear HOH and HHO geometries.

van Harrevelt, Rob; van Hemert, Marc C.

2000-04-01

126

Synchrotron-based far-infrared spectroscopic investigation and ab initio calculations of 3-oxetanone: observation and analysis of the ?7 band and the Coriolis coupled ?16 and ?20 bands.  

UK PubMed Central (United Kingdom)

Rotationally resolved vibrational spectra of the four-membered heterocycle 3-oxetanone (c-C(3)H(4)O(2)) have been investigated in the 360-720 cm(-1) region with a resolution of 0.000 959 cm(-1) using synchrotron radiation from the Canadian Light Source. The observed bands correspond to motions best described as C?O deformation out-of-plane (?(20)) at 399.6 cm(-1), C?O deformation in-plane (?(16)) at 448.2 cm(-1), and the ring deformation (?(7)) at 685.0 cm(-1). Infrared ground state combination differences along with previously reported pure rotational transitions were used to obtain the ground state spectroscopic parameters. Band centers, rotational and centrifugal distortion constants for the ?(7), ?(16), and ?(20) vibrational excited states were accurately determined by fitting a total of 10,319 assigned rovibrational transitions in a global analysis. The two adjacent carbonyl deformation bands, ?(16) and ?(20), were found to be mutually perturbed through a first-order a-type Coriolis interaction which was accounted for in the multiband analysis. The band centers agree within 3% of the ab initio estimates using DFT theory.

Chen Z; van Wijngaarden J

2012-09-01

127

A two-band model for the calculation of clear sky solar irradiance, illuminance, and photosynthetically active radiation at the earth's surface  

Energy Technology Data Exchange (ETDEWEB)

A two-band radiation modelling technique is proposed for the clear sky case. The solar spectrum is divided into a UV/Visible band (0.29-0.7 {mu}m) and an infra-red band (0.7-2.7 {mu}m). In each band, the transmittance of each extinction layer (ozone, water vapor, mixed gases, molecules and aerosols) is parameterized using preliminary integrations of state-of-the-art spectral transmittance functions. The beam and diffuse radiation components are obtained as functions of these layer transmittances. The photosynthetically active radiation (0.4-0.7 {mu}m) and illuminance (0.39-0.76 {mu}m) components may be easily derived from the UV/Visible band irradiances. In the case of typical atmospheric conditions, the model predictions are generally in good agreement with results from three accepted rigorous spectral codes. The effect of changing the solar elevation, the Angstrom turbidity coefficient and the site altitude on the beam, diffuse and global components (or their ratio) is further discussed.

Gueymard, C. (Serres Bio-Solaire Inc., Ham-Nord (Canada))

1989-01-01

128

Ultrawide Band Electromagnetic Pulses  

International Science & Technology Center (ISTC)

Development of New Calculation-Theoretical and Metrologic Approaches in Technology of Ultrawide Band Electromagnetic Pulses, Elaboration and Investigation of Standard Field-Forming Systems of Subnanosecond Pulse Field

129

Off-center impurity in alkali halides: reorientation, electric polarization and pairing to F center. III. Numerical calculations  

CERN Document Server

We carried out numerical calculations by an extended-Hueckel program in order to check the analytical results reported in the preceding Part I and Part II. We typically consider alkali halide clusters composed of some tens of constituent atoms to calculate electronic energies under static conditions or versus the displacements of particular atoms. Among other things, the off-center displacement of substitutional Li+ impurity in most alkali halides is evidenced. The trigonometric profile of the rotational barriers is also confirmed for KCl.

Baldacchini, G; Grassano, U M; Scacco, A; Petrova, P; Mladenova, M; Ivanovich, M; Georgiev, M

2007-01-01

130

Excited bands in fixed CNS configurations  

International Nuclear Information System (INIS)

Exact and approximate quantum numbers of the cranked Nilsson-Strutinsky (CNS) formalism are exploited to calculate excited bands in fixed configurations with the energy of the individual bands minimized with respect to deformation for all spin values. The formalism is illustrated to calculate all bands which appear important in the decay out of the superdeformed band in 59Cu.

2003-03-03

131

Real-structure effects: Band gaps of Mg_xZn_{1-x}O, Cd_xZn_{1-x}O, and n-type ZnO from ab-initio calculations  

Energy Technology Data Exchange (ETDEWEB)

Many-body perturbation theory is applied to compute the quasiparticle electronic structures and the optical-absorption spectra (including excitonic effects) for several transparent conducting oxides. We discuss HSE+G{sub 0}W{sub 0} results for band structures, fundamental band gaps, and effective electron masses of MgO, ZnO, CdO, SnO{sub 2}, SnO, In{sub 2}O{sub 3}, and SiO{sub 2}. The Bethe-Salpeter equation is solved to account for excitonic effects in the calculation of the frequency-dependent absorption coefficients. We show that the HSE+G{sub 0}W{sub 0} approach and the solution of the Bethe-Salpeter equation are very well-suited to describe the electronic structure and the optical properties of various transparent conducting oxides in good agreement with experiment.

Schleife, A; Bechstedt, F

2012-02-15

132

Mental Calculation Methods Used by 11-Year-Olds in Different Attainment Bands: A Reanalysis of Data from the 1987 APU Survey in the UK.  

Science.gov (United States)

Reanalyzes data obtained in 1987 on mental calculation strategies used by 11-year-olds in England, Wales, and Northern Ireland. Classifies mental strategies developed in the past decade in international research. Compares frequency and effectiveness of the strategies used by pupils of different levels of attainment. Discusses basic arithmetic…

Foxman, Derek; Beishuizen, Meindert

2002-01-01

133

The interaction strength between bands in 166Yb nucleus  

International Nuclear Information System (INIS)

In this article the interactions strength between super band (s-band) and the ground band (g-band) s-, ?-band and ?-band are calculated. Also the interaction strength ?- and ?-bands is calculated. The unperturbed energy states for g-, ?- and ?-bands are predicted by variable moment of inertia model (VMI) and the s-band is considered as pure rotational one. The calculations of the interaction strength between bands are performed in the frame work of the two-levels approach. The predicted values of the interaction strength is in good agreement with experimental and other theoretical one. (author). 10 refs., 1 fig., 2 tabs.

1995-01-01

134

K Emission Band of Ferromagnetic Ni  

Science.gov (United States)

The K emission band of ferromagnetic nickel has been calculated using a one-electron model and dipole approximation. The nickel K band emission was measured using a two crystal X-ray spectrometer. The FWHM of the calculated K emission band shows only about 0.1 eV broadening as compared to the calculated band of paramagnetic nickel. The experimental band is very sensitive to the correction procedure applied to the measured data but any reasonable realistic correction treatment still yields a considerably broader band than the theoretical one. This is contrary to the case of the L emission and XPS valence band for which the calculated bands are much broader than the measured ones. Consequently, the many-body effects already found in XPS and UPS spectra of nickel may also play a significant role in the Ni K band emission.

Lähdeniemi, M.; Ojala, E.; Suoninen, E.; Terakura, I.; Terakura, K.

1982-06-01

135

Gastric Banding  

Science.gov (United States)

... and certain drugs should not have gastric banding. Surgical Procedure Before Surgery If you are considering whether to ... risks, including death. There are risks from the surgical procedure and the medications or anesthesia used during surgery. ...

136

Band crossing in 172HF  

International Nuclear Information System (INIS)

The use of a multiplicity filter to enhance the observation of high spin states following the 160Gd(16O,4n)172Hf reaction has enabled the yrast band to be seen up to spin 22+. The energy of the 22+ ? 20+ transition is consistent with that predicted recently in a band crossing calculation. (Author)

1977-01-01

137

Band crossings in 170Os  

International Nuclear Information System (INIS)

Excited states in the neutron-deficient nucleus 170Os were identified up to spin (24+) in the yrast band and to spin (23-) in the lowest negative-parity band. Deformation systematics implied by the 2+ state energies for the very light osmium isotopes are compared with theory. Band-crossing frequencies, alignments and alignment gains are compared with cranked shell-model calculations. Deformation changes are required to obtain detailed agreement. A three-band mixing approach is invoked to explain the low-spin yrast anomaly in 172Os and to reproduce the yrast band in 170Os. The excitation energy of the postulated 'intruder' band in 170Os and 172Os is deduced. (orig.).

1988-01-01

138

Calculation of attenuation by rain using the DAH model and diameter of antennas for the Ka Band in Mexico; Calculo de atenuacion por lluvia usando el modelo DAH y diametro de antena para Banda Ka en Mexico  

Energy Technology Data Exchange (ETDEWEB)

In the last years, the peak in the demand of satellite communication service has caused the saturation in the use of the frequencies corresponding to the band, Cand Ku. Due to this, the engineers have looked for viable alternatives, in order to satisfy the current requisition, as well as the future demand, for which a considerable increment is expected. One of these alternatives is the use of the Ka Band (20Hz/30Hz), that is why the importance of studying the propagation effects that are experienced at these frequencies, especially the attenuation effect by rain, as in this case, where it is significant. The present article has the purpose to describe the use of the Modelo DAH (whose authors are Asoka Dissanayake, Jeremy Allnutt and Fatim Haidara), mixed with the global maps of distribution of rain by Crane, for the calculation of the attenuation by rain in satellite communication systems operated in the Ka Band. Besides, antenna diameters for the systems of communications in Ka Band in different locations of the Mexican Republic, using for it the attenuation margins for rain obtained through the Modelo DAH, and using as references the characteristics of the ANIK F2 satellite and a terrestrial station VSAT, are proposed. [Spanish] En los ultimos anos, el auge en la demanda de servicios de comunicacion por satelite ha provocado la saturacion en los uso de la frecuencia correspondientes a las bandas C y Ku. Debido a esta razon, se han buscado alternativas viables para poder satisfacer la demanda actual, asi como la demanda futura, para la cual se espera un incremento considerable. Una de estas alternativas es el uso de Banda Ka (20Hz/30Hz), de ahi la importancia del estudio sobre los efectos de programacion que se experimentan a esta frecuencia, en especial, el efecto de atencion por lluvias, ya que sen este caso resulta ser significativa. El presente articulo tiene como finalidad describir el uso del Modelo DAH (cuyos autores son Asoka Dissanayake, Jeremy Allnutt y Fatim Haidara), combinado con los mapas globales de distribucion de lluvia de Crane, para el calculo de la atencion por lluvia en sistema de comunicacion por satelite que operen en la Banda Ka. Ademas, se proponen diametros de antena para los sistemas de comunicaciones en Banda Ka en diferentes localidades de la Republica Mexicana, empleando para ello, los margenes de atencion por lluvia obtenidos a trav del Modelo DAH, y usando como referencia las caracteristicas del satelite de comunicaciones ANIK F2 y de una estacion terrena VSAT.Se muestra una fig. de la atenuacion por lluvia a 27.5 gHz y de los diametros de antena para banda Ka en Mexico. Se da una tabla de la atenuacion por lluvia a 29.5 GHz y a 20.2 GHz.

Landeros-Ayala, S.; Neri-Vela, R; Cruz-Sanchez, H.; Hernandez-Bautista, H. [Universidad Nacional Autonoma de Mexico, Mexico, D.F. (Mexico)

2002-03-01

139

Chemically induced compaction bands in geomaterials  

Science.gov (United States)

Compaction bands play an important role in oil production and may provide useful information on various geological processes. Various mechanisms can be involved at different scales: the micro scale (e.g. the grain scale), the meso scale (e.g. the Representative Element Volume) and the macro scale (e.g. the structure). Moreover, hydro-chemo-mechanical couplings might play an important role in triggering instabilities in the form of compaction bands. Compaction bands can be seen as an instability of the underneath mathematical problem leading to localization of deformation [1,2,3]. Here we explore the conditions of compaction banding in quartz-based geomaterials by considering the effect of chemical dissolution and precipitation [4,5]. In due course of the loading process grain crushing affects the residual strength, the porosity and the permeability of the material. Moreover, at the micro-level, grain crushing results in an increase of the grain specific surface, which accelerates the dissolution [6]. Consequently, the silica is removed more rapidly from the grain skeleton and the overall mechanical properties are degraded due to chemical factors. The proposed model accounts for these phenomena. In particular, the diffusion of the diluted in the water silica is considered through the mass balance equation of the porous medium. The reduction of the mechanical strength of the material is described through a macroscopic failure criterion with chemical softening. The grain size reduction is related to the total energy input [7]. A grain size and porosity dependent permeability law is adopted. These degradation mechanisms are coupled with the dissolution/precipitation reaction kinetics. The obtained hydro-chemo-mechanical model is used to investigate the conditions, the material parameters and the chemical factors inducing compaction bands formation. References [1] J.W. Rudnicki, and J.R. Rice. "Conditions for the Localization of Deformation in Pressure-sensitive Dilatant Materials." Journal of the Mechanics and Physics of Solids 23.6 (1975): 371-394. [2] I. Vardoulakis and J. Sulem: Bifurcation analysis in geomechanics. Blackie. 1995. [3] J.W. Rudnicki, "Conditions for Compaction and Shear Bands in a Transversely Isotropic Material." International Journal of Solids and Structures 39.13-14 (2002): 3741-3756. [4] L.-B. Hu and T. Hueckel. "Coupled Chemo-mechanics of Intergranular Contact: Toward a Three-scale Model." Computers and Geotechnics 34.4 (2007): 306-327. [5] R. Nova, R. Castellanza, and C. Tamagnini. "A Constitutive Model for Bonded Geomaterials Subject to Mechanical And/or Chemical Degradation." International Journal for Numerical and Analytical Methods in Geomechanics 27.9 (2003): 705-732. [6] J.D. Rimstidt and H.L. Barnes. "The Kinetics of Silica-water Reactions." Geochimica et Cosmochimica Acta 44.11 (1980): 1683-1699. [7] P.V. Lade, J.A. Yamamuro and P.A. Bopp "Significance of Particle Crushing in Granular Materials." Journal of Geotechnical Engineering, 122.4 (1996): 309-316.

Stefanou, Ioannis; Sulem, Jean

2013-04-01

140

A superdeformed band in 151Dy  

International Nuclear Information System (INIS)

[en] A rotational band of 19 (possibly 20) transitions extending to spin ? 131/2? has been observed in 151Dy with an average dynamic moment of inertia I(2) = 79 ?2 MeV-1. This band is identified as a superdeformed band in 151Dy. The value of I(2) agrees with cranked Strutinsky calculations. Similarities as well as striking differences with the superdeformed bands of neighboring nuclei are observed. (orig.)

1988-08-04

 
 
 
 
141

Excited superdeformed bands in sup 191 Hg  

Energy Technology Data Exchange (ETDEWEB)

Two weakly populated rotational bands have been observed in {sup 191}Hg with properties (energy spacings, moments of inertia and lifetimes) very similar to those of the previously reported superdeformed band. Based on cranked Woods-Saxon calculations, these structures are interpreted as the first excited bands in the superdeformed minimum of {sup 191}Hg. Comparison between the data and the calculations highlight the role of specific orbitals at large deformations. (orig.).

Carpenter, M.P.; Janssens, R.V.F.; Moore, E.F.; Ahmad, I.; Fernandez, P.B.; Khoo, T.L.; Wolfs, F.L.H. (Argonne National Lab. (USA)); Ye, D.; Beard, K.B.; Garg, U. (Notre Dame Univ., IN (USA)); Drigert, M.W. (Idaho National Engineering Lab., Idaho Falls (USA)); Benet, P. (Purdue Univ., Lafayette, IN (USA)); Wyss, R.; Satula, W. (Manne Siegbahn Inst. of Physics, Stockholm (Sweden)); Nazarewicz, W.; Riley, M.A. (Liverpool Univ. (UK). Oliver Lodge Lab.)

1990-04-19

142

Excited superdeformed bands in 191Hg  

International Nuclear Information System (INIS)

[en] Two weakly populated rotational bands have been observed in 191Hg with properties (energy spacings, moments of inertia and lifetimes) very similar to those of the previously reported superdeformed band. Based on cranked Woods-Saxon calculations, these structures are interpreted as the first excited bands in the superdeformed minimum of 191Hg. Comparison between the data and the calculations highlight the role of specific orbitals at large deformations. (orig.)

1990-04-19

143

Laparoscopic gastric banding - discharge  

Science.gov (United States)

... discharge; Laparoscopic adjustable gastric banding - discharge; Bariatric surgery - laparoscopic gastric banding - discharge ... You had laparoscopic gastric banding surgery to help with weight loss. Your surgeon placed a band around the upper part of your stomach ...

144

Laparoscopic gastric banding  

Science.gov (United States)

... Band; LAGB; Laparoscopic adjustable gastric banding; Bariatric surgery - laparoscopic gastric banding ... able to lose weight through diet and exercise. Laparoscopic gastric banding is not a "quick fix" for obesity . It ...

145

Bernauer's bands.  

UK PubMed Central (United Kingdom)

Ferdinand Bernauer proposed in his monograph, "Gedrillte" Kristalle (1929), that a great number of simple, crystalline substances grow from solution or from the melt as polycrystalline spherulites with helically twisting radii that give rise to distinct bull's-eye patterns of concentric optical bands between crossed polarizers. The idea that many common molecular crystals can be induced to grow as mesoscale helices is a remarkable proposition poorly grounded in theories of polycrystalline pattern formation. Recent reinvestigation of one of the systems Bernauer described revealed that rhythmic precipitation in the absence of helical twisting accounted for modulated optical properties [Gunn, E. et al. J. Am. Chem. Soc. 2006, 128, 14234-14235]. Herein, the Bernauer hypothesis is re-examined in detail for three substances described in "Gedrillte" Kristalle, potassium dichromate, hippuric acid, and tetraphenyl lead, using contemporary methods of analysis not available to Bernauer, including micro-focus X-ray diffraction, electron microscopy, and Mueller matrix imaging polarimetry. Potassium dichromate is shown to fall in the class of rhythmic precipitates of undistorted crystallites, while hippuric acid spherulites are well described as helical fibrils. Tetraphenyl lead spherulites grow by twisting and rhythmic precipitation. The behavior of tetraphenyl lead is likely typical of many substances in "Gedrillte" Kristalle. Rhythmic precipitation and helical twisting often coexist, complicating optical analyses and presenting Bernauer with difficulties in the characterization and classification of the objects of his interest.

Shtukenberg A; Gunn E; Gazzano M; Freudenthal J; Camp E; Sours R; Rosseeva E; Kahr B

2011-06-01

146

Investigation of chiral bands in 106Ag  

International Nuclear Information System (INIS)

Dipole bands in 106Ag have been studied with the ?-detector array AFRODITE at iThemba LABS, South Africa. A 96Zr(14N,4n)106Ag reaction at a beam energy of 71 MeV has been used. The three previously known negative-parity bands in 106Ag have been extended. Bands 1 and 2 were proposed to be chiral partner bands. However, in view of the present results, bands 2 and 3 seem to be better candidates for chiral partner bands since their staggering parameters, B(M1)/B(E2) ratios, kinematic moments of inertia and quasiparticle alignments agree much better than those of bands 1 and 2. Triaxial relativistic mean field (RMF) and particle-rotor model (PRM) calculations support this interpretation. In the potential energy surface of 106Ag, obtained in RMF calculations, two minima have been found in the ?2-? plane. Based on PRM calculations using the deformation parameters of the two minima and a ?h11/2 x ?g-19/2 particle-hole configuration, bands 2 and 3 may represent partners with chiral vibration at ??12degree. Band 1, located in the other minimum, may be a magnetic dipole band or the partner of a second pair of chiral bands.

2010-01-01

147

Study on the d-bands in ferromagnetic iron  

Energy Technology Data Exchange (ETDEWEB)

d-bands in ferromagnetic iron have been calculated by the linear combination of atomic orbitals (LCAO) method, using d-d tight binding parameters previously obtained. d-band contributions to the band structure of this metal have been analyzed. Results of calculation for density of states, the Fermi surface, and magneton number, are presented.

Moh, H.J.; Shim, K.R.

1983-03-01

148

Microscopic analysis of the valence band and impurity band theories of (Ga,Mn)As.  

UK PubMed Central (United Kingdom)

We analyze microscopically the valence and impurity band models of ferromagnetic (Ga,Mn)As. We find that the tight-binding Anderson approach with conventional parametrization and the full potential local-density approximation+U calculations give a very similar band structure whose microscopic spectral character is consistent with the physical premise of the k·p kinetic-exchange model. On the other hand, the various models with a band structure comprising an impurity band detached from the valence band assume mutually incompatible microscopic spectral character. By adapting the tight-binding Anderson calculations individually to each of the impurity band pictures in the single Mn impurity limit and then by exploring the entire doping range, we find that a detached impurity band does not persist in any of these models in ferromagnetic (Ga,Mn)As.

Mašek J; Máca F; Kudrnovský J; Makarovsky O; Eaves L; Campion RP; Edmonds KW; Rushforth AW; Foxon CT; Gallagher BL; Novák V; Sinova J; Jungwirth T

2010-11-01

149

Cranked Skyrme-Hartree-Fock calculation for superdeformed and hyperdeformed rotational bands in N=Z nuclei from sup 3 sup 2 S to sup 4 sup 8 Cr  

CERN Multimedia

With the use of the symmetry-unrestricted cranked Skyrme-Hartree-Fock method in the three-dimensional coordinate-mesh representation, we have carried out a systematic theoretical search for the superdeformed and hyperdeformed rotational bands in the mass A=30-50 region. Along the N=Z line, we have found superdeformed solutions in sup 3 sup 2 S, sup 3 sup 6 Ar, sup 4 sup 0 Ca, sup 4 sup 4 Ti, and hyperdeformed solutions in sup 3 sup 6 Ar, sup 4 sup 0 Ca, sup 4 sup 4 Ti, sup 4 sup 8 Cr. The superdeformed band in sup 4 sup 0 Ca is found to be extremely soft against both the axially symmetric (Y sub 3 sub 0) and asymmetric (Y sub 3 sub 1) octupole deformations. An interesting role of symmetry breaking in the mean field is pointed out.

Inakura, T; Yamagami, M; Matsuyanagi, K

2002-01-01

150

Band structure of boron doped carbon nanotubes  

CERN Document Server

We present {\\it ab initio} and self-consistent tight-binding calculations on the band structure of single wall semiconducting carbon nanotubes with high degrees (up to 25 %) of boron substitution. Besides a lowering of the Fermi energy into the valence band, a regular, periodic distribution of the p-dopants leads to the formation of a dispersive ``acceptor''-like band in the band gap of the undoped tube. This comes from the superposition of acceptor levels at the boron atoms with the delocalized carbon $\\pi$-orbitals. Irregular (random) boron-doping leads to a high concentration of hybrids of acceptor and unoccupied carbon states above the Fermi edge.

Wirtz, L; Wirtz, Ludger; Rubio, Angel

2003-01-01

151

Superdeformed band in /sup 151/Dy  

Energy Technology Data Exchange (ETDEWEB)

A rotational band of 19 (possibly 20) transitions extending to spin approx. = 131/2Planck constant has been observed in /sup 151/Dy with an average dynamic moment of inertia I/sup (2)/ = 79 Planck constant/sup 2/ MeV/sup -1/. This band is identified as a superdeformed band in /sup 151/Dy. The value of I/sup (2)/ agrees with cranked Strutinsky calculations. Similarities as well as striking differences with the superdeformed bands of neighboring nuclei are observed.

Rathke, G.E.; Janssens, R.V.F.; Ahmad, I.; Chasman, R.R.; Hass, M.; Khoo, T.L.; Koerner, H.J.; Ma, W.C.; Wolfs, F.L.H.; Drigert, M.W.

1988-08-04

152

Highly deformed band structure in 57Co  

International Nuclear Information System (INIS)

Rotational bands have been found in 57Co using the 28Si(32S,3p) reaction at 130 MeV. The bands, extending the mass 60 region of large deformation down to Z=27, are signature-partner sequences. Their quadrupole moments are similar to those of bands in the neighboring nuclei. The features of the new bands are described by Skyrme Hartree-Fock calculations favoring a configuration assignment with one neutron and one proton excited in the respective 1g9/2 intruder orbital. An attempt to describe the magnetic (M1) properties of the signature-partner structure is also presented.

2002-01-01

153

Collective band structures and identification of one-photon and two-phonon ?-vibrational bands in 109Tc  

International Nuclear Information System (INIS)

The high spin states of the neutron-rich 109Tc nucleus are reinvestigated by observing prompt ?-rays from the spontaneous fission of 252Cf. The previously known yrast band based on the 7/2+ state is updated. A side band built on the 11/2+ state is expanded and a new band based on the 15/2+ state is identified. Band crossing in the yrast band occurs around ???0.36 MeV. This band crossing is associated with the alignment of two h11/2 neutrons according to the cranked shell model calculations. The band based on the 11/2+ state is proposed as a candidate for the one-phonon ?-vibrational band, and the band built on the 15/2+ state is proposed as a candidate for the two-phonon ?-vibrational band. Other characteristics for the observed bands are discussed. (authors)

2010-01-01

154

Rotational band properties of 173W  

Science.gov (United States)

High-spin states in 173W have been studied using the 150Nd(28Si,5n)173W reaction at beam energies of 135 and 140 MeV. The previously known bands associated with the 7/2+[633], 5/2-[512], and 1/2-[521] configurations are extended significantly, and the unfavored signature branch of the 1/2-[521] band is established for the first time. The band properties, such as level spacings, band-crossing frequencies, alignment gains, and signature splittings, are discussed with an emphasis on the low-spin signature inversion observed in the 5/2-[512] band. By comparing the experimental B(M1)/B(E2) ratios with the theoretical values, we conclude that the configuration of the 5/2-[512] band is quite pure at low spins without appreciable admixture of the 5/2-[523] orbit, in conflict with the particle rotor model calculated results.

Wang, H. X.; Zhang, Y. H.; Zhou, X. H.; Liu, M. L.; Ding, B.; Li, G. S.; Hua, W.; Zhou, H. B.; Guo, S.; Qiang, Y. H.; Oshima, M.; Koizumi, M.; Toh, Y.; Kimura, A.; Harada, H.; Furutaka, K.; Kitatani, F.; Nakamura, S.; Hatsukawa, Y.; Ohta, M.; Hara, K.; Kin, T.; Meng, J.

2012-10-01

155

Rotational bands in 167Hf  

International Nuclear Information System (INIS)

High-spin states in 167Hf, populated in the 141Pr(30Si,p3n)167Hf reaction, have been studied using the NORDBALL Ge detector array. Three rotational cascades have been observed for the first time and the previously-known level scheme has been extended to significantly higher spin. Band-crossing effects are discussed within the framework of Woods-Saxon cranking calculations and are found to be in good agreement. (orig.)

1999-01-01

156

Competition between triaxial bands and highly deformed intruder bands around sup 180 Os  

Energy Technology Data Exchange (ETDEWEB)

Angular momentum alignment processes in nuclei around {sup 180}Os are discussed within the deformed shell model using the Woods-Saxon potential and the monopole pairing interaction. The crossings between bands of different structures are analysed and predictions are made for the possible observation of highly deformed intruder bands. Predictions of Q{sub 0} moments are presented for the highly deformed bands and tables of calculated deformations for {sup 178-183}Os are given. (orig.).

Wyss, R.; Satula, W.; Nazarewicz, W.; Johnson, A. (Manne Siegbahn Inst. of Physics, Stockholm (Sweden) Royal Inst. of Tech., Stockholm (Sweden). Physics Dept. 1)

1990-05-07

157

Coexistence of terminating bands and more collective bands in the A ?100 region of nuclei  

International Nuclear Information System (INIS)

Nilsson-Strutinsky cranking calculations on A ?100 Ru and Pd nuclei suggest that, contrary to other mass regions, it should be possible to follow the ground state rotational bands to their termination at spins just above I=30 ? and then also to observe other bands which terminate at higher spins. (orig.).

1996-01-01

158

Band structure analysis of the conduction-band mass anisotropy in 6H and 4H SiC  

CERN Multimedia

The band structures of 6H and 4H SiC calculated by means of the FP-LMTO method are used to determine the effective mass tensors for their conduction-band minima. The results are shown to be consistent with recent optically detected cyclotron resonance measurements and predict an unusual band filling dependence for 6H-SiC.

Lambrecht, W R L; Lambrecht, Walter R. L.; Segall, Benjamin

1995-01-01

159

Rotational bands of {sup 155}Gd  

Energy Technology Data Exchange (ETDEWEB)

High spin states of {sup 155}Gd have been investigated using the {sup 150}Nd({sup 12}C, {alpha}3n) reaction. Three rotational bands have been observed. Two of them have been extended up to ((51(2))){sup +} and (45(2)){sup -}, respectively, and another band has been newly observed. The backbending and blocking effects are discussed in comparison with the calculation of cranked shell model. The routhians and the B(M1)/B(E2) ratio of the high-{omega} rotational band are compared with the calculation by the tilted axis cranking model. In addition the ground state rotational band of {sup 156}Gd has been extended up to 22{sup +}.

Hayakawa, T.; Oshima, M.; Hatsukawa, Y.; Katakura, J.; Iimura, H.; Matsuda, M.; Mitarai, S.; Shimizu, Y.R.; Ohtsubo, S.-I.; Shizuma, T.; Sugawara, M.; Kusakari, H

1999-09-13

160

Superdeformed bands in 189,190Hg  

International Nuclear Information System (INIS)

[en] Experiments using the 160Gd(34S, xn) reaction at 159 and 162 MeV have revealed two ?-ray cascades which have properties similar to those of the previously reported superdeformed bands in the heavier Hg isotopes. These sequences have been identified as superdeformed structures in 189Hg and 190Hg. For the band in 190Hg, an average quadrupole moment Q0=18±3 e.b was obtained from a DSAM measurement. The data are interpreted within the cranked Woods-Saxon formalism and the rise in the dynamical moment of inertia for both bands is linked to the presence of pairs correlations and quasiparticle alignments. For the 189-194Hg superdeformed bands, the variations in the observed population intensity and in the rotational frequencies at which decay out of the bands occur are found to be consistent with the calculated change in the well depth of the superdeformed minimum with mass. (orig.)

1991-08-05

 
 
 
 
161

Multiple band structures in sup 191 Hg  

Energy Technology Data Exchange (ETDEWEB)

The level structure of the nucleus {sup 191}Hg has been considerably extended from previous studies by using the {sup 160}Gd({sup 36}S, 5n) reaction in conjunction with an array of Compton-suppressed germanium detectors. A series of 13 different level sequences has been established in addition to three superdeformed bands. A majority of the band structures can be understood in cranked shell model calculations assuming on oblate collective nuclear shape. There is some evidence for the onset of triaxiality. Finally, two bands of single-particle character have been found. They are interpreted as being associated with a prolate non-collective shape ({gamma}=-120deg). (orig.).

Ye, D.; Beard, K.B.; Garg, U. (Univ. of Notre Dame, IN (United States)); Janssens, R.V.F.; Carpenter, M.P.; Ahmad, I.; Khoo, T.L.; Moore, E.F.; Wolfs, F.L.H. (Argonne National Lab., IL (United States)); Benet, P.; Grabowski, Z.W. (Purdue Univ., West Lafayette, IN (United States)); Drigert, M.W. (Idaho National Engineering Lab., EG and G Idaho Inc., Idaho Falls, ID (United States))

1992-02-01

162

Multiple band structures in 191Hg  

International Nuclear Information System (INIS)

[en] The level structure of the nucleus 191Hg has been considerably extended from previous studies by using the 160Gd(36S, 5n) reaction in conjunction with an array of Compton-suppressed germanium detectors. A series of 13 different level sequences has been established in addition to three superdeformed bands. A majority of the band structures can be understood in cranked shell model calculations assuming on oblate collective nuclear shape. There is some evidence for the onset of triaxiality. Finally, two bands of single-particle character have been found. They are interpreted as being associated with a prolate non-collective shape (?=-120deg). (orig.)

1992-01-01

163

Electronic band structure of beryllium oxide  

CERN Multimedia

The energy-momentum resolved valence band structure of beryllium oxide has been measured by electron momentum spectroscopy (EMS). Band dispersions, bandwidths and intervalence bandgap, electron momentum density (EMD) and density of occupied states have been extracted from the EMS data. The experimental results are compared with band structure calculations performed within the full potential linear muffin-tin orbital approximation. Our experimental bandwidths of 2.1 +- 0.2 and 4.8 +- 0.3 eV for the oxygen s and p bands, respectively, are in accord with theoretical predictions, as is the s-band EMD after background subtraction. Contrary to the calculations, however, the measured p-band EMD shows large intensity at the GAMMA point. The measured full valence bandwidth of 19.4 +- 0.3 eV is at least 1.4 eV larger than the theory. The experiment also finds a significantly higher value for the p-to-s-band EMD ratio in a broad momentum range compared to the theory.

Sashin, V A; Kheifets, A S; Ford, M J

2003-01-01

164

Electronic band structure of beryllium oxide  

International Nuclear Information System (INIS)

[en] The energy-momentum resolved valence band structure of beryllium oxide has been measured by electron momentum spectroscopy (EMS). Band dispersions, bandwidths and intervalence bandgap, electron momentum density (EMD) and density of occupied states have been extracted from the EMS data. The experimental results are compared with band structure calculations performed within the full potential linear muffin-tin orbital approximation. Our experimental bandwidths of 2.1 ± 0.2 and 4.8 ± 0.3 eV for the oxygen s and p bands, respectively, are in accord with theoretical predictions, as is the s-band EMD after background subtraction. Contrary to the calculations, however, the measured p-band EMD shows large intensity at the ? point. The measured full valence bandwidth of 19.4 ± 0.3 eV is at least 1.4 eV larger than the theory. The experiment also finds a significantly higher value for the p-to-s-band EMD ratio in a broad momentum range compared to the theory

2003-06-04

165

Electronic band structure of beryllium oxide  

Energy Technology Data Exchange (ETDEWEB)

The energy-momentum resolved valence band structure of beryllium oxide has been measured by electron momentum spectroscopy (EMS). Band dispersions, bandwidths and intervalence bandgap, electron momentum density (EMD) and density of occupied states have been extracted from the EMS data. The experimental results are compared with band structure calculations performed within the full potential linear muffin-tin orbital approximation. Our experimental bandwidths of 2.1 {+-} 0.2 and 4.8 {+-} 0.3 eV for the oxygen s and p bands, respectively, are in accord with theoretical predictions, as is the s-band EMD after background subtraction. Contrary to the calculations, however, the measured p-band EMD shows large intensity at the {gamma} point. The measured full valence bandwidth of 19.4 {+-} 0.3 eV is at least 1.4 eV larger than the theory. The experiment also finds a significantly higher value for the p-to-s-band EMD ratio in a broad momentum range compared to the theory.

Sashin, V A [School of Chemistry, Physics and Earth Science, Flinders University of South Australia, GPO Box 2100, Adelaide SA 5001 (Australia); Bolorizadeh, M A [Physics Department, Shahid Bahonar University, Kerman (Iran, Islamic Republic of); Kheifets, A S [Atomic and Molecular Physics Laboratories, Research School of Physical Sciences and Engineering, The Australian National University, Canberra ACT 0200 (Australia); Ford, M J [Institute for Nanoscale Technology, University of Technology Sydney, PO Box 123, Broadway NSW 2007 (Australia)

2003-06-04

166

Band structure parameters of the nitrides: The origin of the small band gap of InN  

CERN Multimedia

Using a band-structure method that includes the correction to the band gap error in the local density approximation (LDA), we study the chemical trends of the band gap variation in III-V semiconductors and predict that the band gap for InN is 0.8 +/- 0.1 eV, which is much smaller than previous experimental value of approx. 1.9 eV. The unusually small band gap for InN is explained in terms of the high electronegativity of nitrogen and consequently the small band gap deformation potential of InN. The possible origin of the measured large band gaps is discussed in terms of the non-parabolicity of the bands and the Moss-Burstein shift. Based on the error analysis of our LDA calculation and available experimental data we have compiled the recommended band structure parameters for wurtzite AlN, GaN and InN.

Wei, S H; Wei, Su-Huai; Carrier, Pierre

2004-01-01

167

E/sub 1//sup '/ centre in SiO/sub 2/. MO calculation of the /sup 17/O, /sup 29/Si, and /sup 1/H hyperfine splittings  

Energy Technology Data Exchange (ETDEWEB)

Starting from the relaxed O/sup -/ vacancy model the /sup 29/Si, /sup 17/O, and /sup 1/H hyperfine splitting (hfs) parameters are calculated by means of the extended Hueckel theory (EHT) within the cluster approach for different models of the E/sub 1//sup '/ centre in SiO/sub 2/. The /sup 29/Si hyperfine splittings atrongly depend on the lattice relaxation. The accordance of calculated and experimental hfs data, recently observed by Griscom, is checked. Two modified O/sup -/ vacancy models are proposed to explain the E/sub 1//sup '/ centre: one for the centre exhibiting 'weak' hfs and the other for the centre exhibiting no 'weak' hfs.

Haberlandt, H. (Akademie der Wissenschaften der DDR, Berlin. Zentralinstitut fuer Physikalische Chemie)

1982-04-01

168

Pressure induced band gap opening of AlH3  

Science.gov (United States)

Pressure-induced band gap opening (PIBGO) of AlH3 with a Pm3¯n structure is verified by using first-principles calculations. With increasing pressure, the semimetallic band structures change to the indirect band gap semiconducting band structure at about 300 GPa. The key points of this phenomenon are (1) the moderately large difference of electronegativity between aluminium and hydrogen and (2) the orthogonality between the 3s states and 2s states of Al. We have been confirmed that the structure is stable up to and including 500 GPa resulting from the structural relaxation and phonon calculations. The band gap is more accurately confirmed by GW calculations than done by DFT-GGA ones. The band gap may open at about 200 GPa. This phenomenon may be verified by means of a leading-edge experimental technique.

Geshi, Masaaki; Fukazawa, Taro

2013-02-01

169

Investigation of chiral bands in {sup 106}Ag  

Energy Technology Data Exchange (ETDEWEB)

Dipole bands in {sup 106}Ag have been studied with the {gamma}-detector array AFRODITE at iThemba LABS, South Africa. A {sup 96}Zr({sup 14}N,4n){sup 106}Ag reaction at a beam energy of 71 MeV has been used. The three previously known negative-parity bands in {sup 106}Ag have been extended. Bands 1 and 2 were proposed to be chiral partner bands. However, in view of the present results, bands 2 and 3 seem to be better candidates for chiral partner bands since their staggering parameters, B(M1)/B(E2) ratios, kinematic moments of inertia and quasiparticle alignments agree much better than those of bands 1 and 2. Triaxial relativistic mean field (RMF) and particle-rotor model (PRM) calculations support this interpretation. In the potential energy surface of {sup 106}Ag, obtained in RMF calculations, two minima have been found in the {beta}{sub 2}-{gamma} plane. Based on PRM calculations using the deformation parameters of the two minima and a {nu}h{sub 11/2} x {pi}g{sup -1}{sub 9/2} particle-hole configuration, bands 2 and 3 may represent partners with chiral vibration at {gamma}{approx}12degree. Band 1, located in the other minimum, may be a magnetic dipole band or the partner of a second pair of chiral bands.

Lieder, Evgenia [Themba LABS, Somerset West (South Africa); FhG, INT, Euskirchen (Germany); Lieder, Rainer; Bark, Rob; Lawrie, Elena; Lawrie, Kobus; Ntshangase, Sifiso; Mullins, Simon; Papka, Paul; Kheswa, Ntombi [Themba LABS, Somerset West (South Africa); Meng, Jie [PhS, PKU, Beijing (China); PhS, BUAA, Beijing (China); Qi, Bin [SDU, Weihai (China); Zhang, Shuangquan; Li, Zhipan [PhS, PKU, Beijing (China)

2010-07-01

170

Broad Band Inverse Scattering.  

Science.gov (United States)

The extraction of target characteristics from the broad band, impulse-generated echo at a single target aspect is demonstrated for spherical and spheroidal targets. Target recognition by broad band echo-ranging is further compared with CW echo-ranging on ...

J. Schwartz

1974-01-01

171

Stretch Band Exercise Program  

Science.gov (United States)

This article discusses how to use stretch bands for improving total body fitness and quality of life. A stretch band exercise program offers a versatile and inexpensive option to motivate participants to exercise. The authors suggest practical exercises that can be used in physical education to improve or maintain muscular strength and endurance,…

Skirka, Nicholas; Hume, Donald

2007-01-01

172

Lower and upper bounds to photonic band gap edges  

Science.gov (United States)

A photonic band gap is determined by its edges, which are frequently calculated by the Rayleigh-Ritz method, producing a sequence of upper bounds. Since there are no error estimates available on these approximations, the level of accuracy of the computed band-gap edges, and thus of the extent of the band gap, remains undetermined. We adopt the method of intermediate problems to develop a procedure to calculate the lower bounds to the photonic band-gap edges. Lower bounds, supplemented with the Rayleigh-Ritz approximations, determine a band gap with arbitrary and known degree of accuracy, as well as provide error bounds on approximate calculations by other methods. Calculation of the lower bounds by the present method requires slightly more computational effort than the Rayleigh-Ritz method with a plane-wave basis. A parallel method to compute the alternative upper bounds is also developed in the process.

Vatsya, S. R.; Nikumb, S. K.

2002-08-01

173

Electronic band structure of lithium, sodium and potassium fluorides  

International Nuclear Information System (INIS)

[en] A mixed tight-binding, pseudopotential method is proposed to calculate the energy band structure of large-gap crystals and is tested here on LiF, NaF and KF. Three-centre terms are included in the determination of the valence bands by the tight-binding method and for the conduction bands we use a pseudopotential model proposed by Bassani and Giuliano, modified for the positive ions. By taking into account the polarization corrections, transitions calculated from the energy band structures are compared with experimental data and the agreement is generally good

1975-08-11

174

Is the rigid-band model valid for Mosub(c)Nbsub(1-c) alloys  

International Nuclear Information System (INIS)

[en] The electronic structure of disordered Nb-Mo alloys has been calculated using the CPA for a muffin-tin potential model of the alloy potential. The bonding part of the alloy 'band' structure is rigid-band-like. In the antibonding bands there are significant non-rigid-band effects. (author)

1977-08-19

175

Multiple superdeformed bands in {sup 132}Nd  

Energy Technology Data Exchange (ETDEWEB)

High-spin states have been studied in neutron-deficient {sup 132}Nd, produced in the {sup 105}Pd({sup 35}Cl,{alpha}{ital p}3{ital n}{gamma}) reaction, using the Gammasphere {gamma}-ray spectrometer in conjunction with the Microball charged-particle detector array. Three new, weakly populated rotational bands have been found, which are believed to be associated with a superdeformed (second minimum) prolate shape. Comparison of the properties of these bands with Woods-Saxon cranking calculations suggests that they are built upon negative-parity neutron configurations that involve only one intruder orbital ({nu}{ital i}{sub 13/2}) from the {ital N}=6 shell. One of the bands has been linked into the normally deformed states allowing an estimation of the spin, parity, and excitation energy of the band. {copyright} {ital 1996 The American Physical Society.}

Joss, D.T.; Paul, E.S.; Archer, D.E.; Devlin, M.; Fallon, P.; Hibbert, I.M.; LaFosse, D.R.; Nolan, P.J.; OBrien, N.J.; Pfohl, J.; Riley, M.A.; Sarantites, D.G.; Sheline, R.; Simpson, J.; Wadsworth, R. [Oliver Lodge Laboratory, University of Liverpool, P.O. Box 147, Liverpool L69 3BX (United Kingdom)]|[Department of Physics, Florida State University, Tallahassee, Florida 32306 (United States)]|[Department of Chemistry, Washington University, St. Louis, Missouri 63130 (United States)]|[Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)]|[Department of Physics, University of York, Heslington, York Y01 5DD (United Kingdom)]|[CCLRC, Daresbury Laboratory, Daresbury, Warrington, WA4 4AD (United Kingdom)

1996-09-01

176

Multiple superdeformed bands in 132Nd  

International Nuclear Information System (INIS)

High-spin states have been studied in neutron-deficient 132Nd, produced in the 105Pd(35Cl,?p3n?) reaction, using the Gammasphere ?-ray spectrometer in conjunction with the Microball charged-particle detector array. Three new, weakly populated rotational bands have been found, which are believed to be associated with a superdeformed (second minimum) prolate shape. Comparison of the properties of these bands with Woods-Saxon cranking calculations suggests that they are built upon negative-parity neutron configurations that involve only one intruder orbital (?i13/2) from the N=6 shell. One of the bands has been linked into the normally deformed states allowing an estimation of the spin, parity, and excitation energy of the band. copyright 1996 The American Physical Society.

1996-01-01

177

Band gap of a topological insulator nanotube  

International Nuclear Information System (INIS)

We study the electronic structure of a topological insulator Bi2Te3 cylindrical nanotube. The energy spectrum was calculated in the framework of the kp theory near the ? point of the surface Brilloiun zone. A band gap size dependence of the topological insulator nanotube was studied. A comparative analysis of the topological insulator direct band gap of Bi2Te3 and Bi2Se3 nanowires as a function of radius was performed. Due to a high surface-to-volume ratio, a variation in the ratio of the nanotube external radius to internal radius provides a 50-fold decrease in the topological insulator band gap compared to the respective bulk value. The size dependence of the topological insulator nanotube band gap is much stronger than that for the topological insulator nanowires. (authors)

2011-01-01

178

Generalized seniority scheme for bands in odd-A nuclei  

Energy Technology Data Exchange (ETDEWEB)

The microscopic generalized seniority scheme is applied for the description of bands in odd-A nuclei. A perturbation expansion in terms of the core-particle interaction is performed. The first-order correction for the band head and the first member of the band is discussed. The specific band structure of a given nucleus, as well as the systematic trend of bands, is described in an explicit N-dependent analytical formula. This formula involves a linear dependence on N which arises from the first-order perturbation expansion. This term is shown responsible for the large deviation of the 11/2/sup -/ ..delta..J=2 band spacing in I isotopes from the spacing of the Te core. All observed band structures of an odd-A nucleus arise from one simple core-particle coupling. Hence decoupled-E2 bands and strongly coupled ..delta..J=1 bands, particle or hole bands of low-spin or high-spin orbits, all follow one simple N-dependence. This uniformity of bands is manifested in E2 bands in /sub 53/I isotopes and deltaJ=1 bands in /sub 51/Sb that have the same /sub 52/Te cores. For the calculations a particle-particle force with a large contribution from a g delta force is used with a coupling constant that is deduced from /sup 210/Pb. 1 figure.

Gai, M.; Arima, A.; Strottman, D.

1980-01-01

179

Adaptive Confidence Bands  

CERN Multimedia

We show that there do not exist adaptive confidence bands for curve estimation except under very restrictive assumptions. We propose instead to construct adaptive bands that cover a surrogate function f^\\star which is close to, but simpler than, f. The surrogate captures the significant features in f. We establish lower bounds on the width for any confidence band for f^\\star and construct a procedure that comes within a small constant factor of attaining the lower bound for finite-samples.

Genovese, C R; Genovese, Christopher R.; Wasserman, Larry

2007-01-01

180

New results on the superdeformed {sup 196}Pb nucleus: The decay of the excited bands to the yrast band  

Energy Technology Data Exchange (ETDEWEB)

The study of the superdeformed (SD) {sup 196}Pb nucleus has been revisited using the EUROGAM phase 2 spectrometer. In addition to the known yrast and two lowest excited SD bands, a third excited SD band has been seen. All of the three excited bands were found to decay to the yrast SD band through, presumably, E1 transitions, allowing relative spin and excitation energy assignments. Comparisons with calculations using the random-phase approximation suggest that all three excited bands can be interpreted as octupole vibrational structures.

Bouneau, S.; Azaiez, F.; Duprat, J. [IPN, Orsay (France)] [and others

1996-12-31

 
 
 
 
181

Band Gap Engineering of Crystal Materials: Band Gap Estimation of Semiconductors via Electronegativity  

Science.gov (United States)

We have developed empirical equations to quantitatively calculate the band gap values of binary ANB8-N and ternary ABC2 chalcopyrite semiconductors from the general viewpoint of chemical bonding processes upon electronegativity (EN). It is found that the band gap of crystal materials is essentially determined by the binding energy of chemical bonds to the bonding electrons, which can be effectively described by the average attractive abilities of two bonded atoms to their valence electrons and the delocalization degree of the valence electrons. The calculated band gap values of a large number of compounds can agree well with the available experimental data. This work provides us an efficient approach to quantitatively predict the band gap values of inorganic crystal materials on the basis of fundamental atom parameters such as EN, atomic radius, etc.

Li, Keyan; Li, Yanju; Xue, Dongfeng

2012-06-01

182

Quasiparticle band structure of lanthanum hydride  

Energy Technology Data Exchange (ETDEWEB)

We address the problem of the ground-state character of LaH{sub 3}, a semiconductor compound predicted to be semimetallic within density-functional theory. An ab initio, quasiparticle calculation is peformed whose results indicate a very large 1.1 eV opening of the band gap. Such results are obtained using the GW approximation in the calculation of the self-energy operator. The results are compared to existing experimental data.

Chang, Eric K.; Blase, Xavier; Louie, Steven G.

2001-10-15

183

Diagnostic test band cassette  

UK PubMed Central (United Kingdom)

The diagnostic band cartridge for blood sugar test, comprises a test band equipped with a test pad for testing the body fluid, and a housing for the reception of the test band. The housing has an outsert-molding part formed out of a metal carrier and extruded plastic (30). The molding part has integrated function elements (36) having a spring element formed at the metal carrier, which is formed out of a sheet metal cut. The cut portion of the sheet metal is bent as an elastic spring element. The function element is arranged in the form of a laminated spring (38). The diagnostic band cartridge for blood sugar test, comprises a test band equipped with a test pad for testing the body fluid, and a housing for the reception of the test band. The housing has an outsert-molding part formed out of a metal carrier and extruded plastic (30).The molding part has integrated function elements (36) having a spring element formed at the metal carrier, which is formed out of a sheet metal cut. The cut portion of the sheet metal is bent as an elastic spring element. The function element is arranged in the form of a laminated spring (38) for the sealing function against the test band or in the form of a spiral spring (40) for a spring impact of a spool. The laminated spring is detachably held at a free end through a wall (46) out of extruded plastic in a screwing position. The spiral spring deepens against a plain of the metal carrier and is bent coil-forming in the housing. The spiral spring is externally covered through a cover out of extruded plastic against interference. The extruded plastic has a wall perforation in the area of the spring element for an articulate and/or a center pin from the spring element.The function element has an anchor element for the housing part and a cover arranged between two spool transported test bands. The metal carrier is over molded with plastic in the form of a rest element. The cover is formed with the plastic through undercut flap of the metal carrier. The molding part forms a cartridge cover or a cartridge body. The function element comprises a band deflector for sliding guide of the test band. An independent claim is included for a method for the production of diagnostic band cartridge.

SACHERER KLAUS DIETER

184

LHC Bellows Impedance Calculations  

CERN Multimedia

To compensate for thermal expansion the LHC ring has to accommodate about 2500 bellows which, together with beam position monitors, are the main contributors to the LHC broad-band impedance budget. In order to reduce this impedance to an acceptable value the bellows have to be shielded. In this paper we compare different designs proposed for the bellows and calculate their transverse and longitudinal wakefields and impedances. Owing to the 3D geometry of the bellows, the code MAFIA was used for the wakefield calculations; when possible the MAFIA results were compared to those obtained with ABCI. The results presented in this paper indicate that the latest bellows design, in which shielding is provided by sprung fingers which can slide along the beam screen, has impedances smaller tha those previously estimated according to a rather conservative scaling of SSC calculations and LEP measurements. Several failure modes, such as missing fingers and imperfect RF contact, have also been studied.

Dyachkov, M

1997-01-01

185

Multi bunch dynamics in detuned x-band structures  

International Nuclear Information System (INIS)

The multi bunch dynamics of a 2 x 250 GeV version of the JLC is studied. The rf-properties of detuned x-band tubes are calculated with the Computer codes URMEL and MAFIA. The dispersion curve found with these codes is compared with an equivalent circuit model. The calculation of the dipole mode loss parameters is investigated in detail. Tracking calculations are used to investigate the misalignment tolerances for detuned x-band structures. Also tilted x-band tubes are considered. (author).

1992-01-01

186

Supersymmetry and Identical Bands  

CERN Document Server

Supersymmetry as applied to identical bands is discussed. A review of the work of the Koeln-Dubna group on this topic is given and examples in 171,172Yb, 173,174Hf, and 195,194Pt are discussed. The role of pseudo-spin in the supersymmetry is investigated. A recent precision lifetime measurement for identical bands in 171,172Yb is discussed.

Von Brentano, P

2003-01-01

187

Laparoscopic adjustable gastric banding.  

Science.gov (United States)

Laparoscopic adjustable gastric banding is one of several weight loss procedures in the bariatric surgeon's armamentarium to treat morbid obesity. Laparoscopic gastric banding has the lowest perioperative risk compared to laparoscopic gastric bypass, sleeve gastrectomy, and duodenal switch (Buchwald et al., JAMA 292:1724-1737, 2004). The adjustable gastric band results in approximately 50% excess weight loss at 5 years (O'Brien and Dixon,J Laparoendosc Adv Surg Tech A 13:265-270, 2003). In the long-term, reoperation rates can be high with the percentage of reoperations varying enormously in reported studies from 2% to 80% (Schouten et al., Surg Obes Relat Dis 7:99-109, 2011), although with changes in technique, reoperation rates after gastric banding have decreased (O'Brien et al., Obes Surg 15:820-826, 2005). Aftercare is critical to the success of the banded patient, in terms of adjusting the band as well as monitoring the patient's symptoms (Weichman et al., Surg Endosc 25:397-403, 2011). Several studies have shown that patients who are seen more than six to seven times in the first postoperative year have better weight loss. PMID:22446895

Beitner, Melissa; Kurian, Marina S

2012-10-01

188

Laparoscopic adjustable gastric banding.  

UK PubMed Central (United Kingdom)

Laparoscopic adjustable gastric banding is one of several weight loss procedures in the bariatric surgeon's armamentarium to treat morbid obesity. Laparoscopic gastric banding has the lowest perioperative risk compared to laparoscopic gastric bypass, sleeve gastrectomy, and duodenal switch (Buchwald et al., JAMA 292:1724-1737, 2004). The adjustable gastric band results in approximately 50% excess weight loss at 5 years (O'Brien and Dixon,J Laparoendosc Adv Surg Tech A 13:265-270, 2003). In the long-term, reoperation rates can be high with the percentage of reoperations varying enormously in reported studies from 2% to 80% (Schouten et al., Surg Obes Relat Dis 7:99-109, 2011), although with changes in technique, reoperation rates after gastric banding have decreased (O'Brien et al., Obes Surg 15:820-826, 2005). Aftercare is critical to the success of the banded patient, in terms of adjusting the band as well as monitoring the patient's symptoms (Weichman et al., Surg Endosc 25:397-403, 2011). Several studies have shown that patients who are seen more than six to seven times in the first postoperative year have better weight loss.

Beitner M; Kurian MS

2012-10-01

189

Mechanisms of chromosome banding. V. Quinacrine banding.  

UK PubMed Central (United Kingdom)

A series of biochemical investigations were undertaken to determine the mechanism of Q-banding. The results were as follows: 1. In agreement with previous studies, highly AT-rich DNA, such as poly(dA)-poly(dT), markedly enhanced quinacrine fluorescence while GC containing DNA quenched fluorescence. These effects persisted at DNA concentrations comparable to those in the metaphase chromosome. 2. Studies of quinacrine-DNA complexes in regard to the hypochromism of quanacrine, DNA Tm, DNA viscosity, and equilibrium dialysis, indicated the quinacrine was bound be intercalation with relatively little sid binding. 3. Single or double stranded nucleotide polymers, in the form of complete or partial helices, were 1000-fold more effective in quenching than solutions of single nucleotides, suggesting that base stacking is required for quenching. 4. Studies of polymers in the A conformation, such as transfer RNA and DNA-RNA hybrids, indicated that marked base tilting does not affect the ability of nuclei acids to cause quenching or enhancement of quinacrine fluorescence. 5. Salts inhibit the binding of quinacrine to DNA. 6. Spermine, polylysine and polyarginine, which bind in the small groove of DNA, inhibited quinacrine binding and quenching, while histones, which probably bind in the large groove, had little effect. This correlated with the observation that removal of histones with acid has no effect on Q-banding. 7. Mouse liver chromatin was separated into five fractions. At concentrations of quinacrine from 2 times 10-6 to 2 times 10-5 M all fractions inhibited to varying degrees the ability of the chromatin DNA to bind quinacrine and quench quinacrine fluorescence. At saturating levels of quinacrine two fractions, the 400 g pellet (rich in heterochromatin) and a dispersed euchromatin supernatant fraction, showed a decreased number of binding sites for quinacrine. These two fractions were also the richest in non-histone proteins. 8. DNA isolated from the different fractions all showed identical quenching of quinacrine fluorescenc. 9. Mouse GC-rich, mid-band, AT-rich, and satellite DNA, isolated by CsCL AND Cs-2SO-4-Ag+ centrifugation all showed identical quenching of quinacrine fluorescence, indicating that within a given organism, except for very AT or GC-rich satellites, the variation in base composition is not adequate to explain Q-banding. We interpret these results to indicate that: (a) quinacrine binds to chromatin by intercalation of the three planar rings with the large group at position 9 lying in the small groove of DNA, (b) most pale staining regions are due to a decrease binding of quinacrine, and (c) this inhibition of binding is predominately due to non-histone proteins.

Comings OE; Kovacs BW; Avelino E; Harris DC

1975-01-01

190

Level density calculation for deformed nuclei  

International Nuclear Information System (INIS)

[en] Level densities for the rare earth and actinide nuclei have been calculated using a modified version of the Ericson formalism. The assumption was made, that K (the projection of J on the symmetry axis of the nucleus) is a good quantum number in the compound nucleus. Individual level densities for the different (K,J) values of the compound nucleus formed by low energy neutron interactions were calculated. The results show good agreement with the interpretation of recent results obtained on U-235 in this laboratory. Using the above calculations it is also possible to infer from the measured level densities the locations of the band heads of different K bands in the compound nucleus. The results also indicate that the K bands responsible for the level densities exclude the ground state rotational band. Levels built on the higher lying ? and ? vibrational bands and their composites are sufficient in number to explain the observed level densities. (4 tables) (U.S.)

1975-03-03

191

High-K band crossings in osmium and rhenium isotopes  

International Nuclear Information System (INIS)

In a quantum many-body calculation using deformed Hartree-Fock and angular momentum projection formalism, the nature of K-mixing around the first band crossings in the high-spin structure of 182,184,186Os and 181,183Re is studied. For Z = 75 181,183Re (N = 106, 108) our calculation reproduces the observed lowering of the high-K (t-band) structure compared to the low-K (s-band) structure, arising due to the coupling of a pair of i13/2 neutrons. We find a transition in even-even osmium nuclei, at N = 108, from the conventional s-band crossing to the t-band crossing. The degree of high-K mixing obtained in the calculation provides a microscopic understanding of the K-forbidden transitions from the high-K bandheads to the yrast states with low-K intrinsic structure.

2004-09-01

192

Band structures and shape coexistence in {sup 187}Pt  

Energy Technology Data Exchange (ETDEWEB)

High-spin states in {sup 187}Pt have been studied by means of {gamma}-ray spectroscopy techniques. Known bands have been significantly extended and new bands have been found. The band structures are discussed in the framework of the cranking model and negative-parity states are compared with calculations performed with a semi-microscopic axial-rotor plus one-quasiparticle coupling model. Shape coexistence is observed from low excitation energy. (orig.)

Hojman, D. [Comision Nacional de Energia Atomica, Departamento de Fisica, Buenos Aires (Argentina); CONICET, Buenos Aires (Argentina); Cardona, M.A. [Comision Nacional de Energia Atomica, Departamento de Fisica, Buenos Aires (Argentina); CONICET, Buenos Aires (Argentina); Universidad Nacional de San Martin, Buenos Aires (Argentina); Roussiere, B.; Sauvage, J. [IN2P3/CNRS/Universite Paris-Sud, Institut de Physique Nucleaire, Orsay (France); Riley, M.A.; Tabor, S.L.; Hoffman, C.R.; Aguilar, A.; Cluff, W.T.; Hinners, T.; Lagergren, K.; Lee, S.; Perry, M.; Pipidis, A.; Tripathi, V. [Florida State University, Department of Physics, Tallahassee, Florida (United States)

2012-06-15

193

Analytical results for random band matrices with preferential basis  

CERN Document Server

Using the supersymmetry method we analytically calculate the local density of states, the localiztion length, the generalized inverse participation ratios, and the distribution function of eigenvector components for the superposition of a random band matrix with a strongly fluctuating diagonal matrix. In this way we extend previously known results for ordinary band matrices to the class of random band matrices with preferential basis. Our analytical results are in good agreement with (but more general than) recent numerical findings by Jacquod and Shepelyansky.

Frahm, K M

1995-01-01

194

Superdeformed Band in Asymmetric N > Z Nucleus 40Ar  

Science.gov (United States)

A rotational band with five cascade ?-ray transitions was newly found in 40Ar. The deduced transition quadrupole moment of 1.45-0.31+0.49 eb has demonstrated this band as having a superdeformed shape of ?2 0.5. The structure of the band was discussed in the framework of cranked Hartree-Fock-Bogoliubov calculations and the assignment of multiparticle-multihole configuration has been made.

Morikawa, Tsuneyasu; Ideguchi, Eiji; Ota, Shinsuke; Oshima, Masumi; Koizumi, Mitsuo; Toh, Yosuke; Kimura, Atsushi; Harada, Hideo; Furutaka, Kazuyoshi; Nakamura, Shoji; Kitatani, Fumito; Hatsukawa, Yuichi; Shizuma, Toshiyuki; Sugawara, Masahiko; Miyatake, Hiroari; Watanabe, Yutaka; Hirayama, Yoshikazu; Oi, Makito

195

Lyman-Birge-Hopfield bands in proton aurorae  

International Nuclear Information System (INIS)

[en] Numerical model of Lyman-Birge-Hopfield (LBH) system band radiation of molecular nitrogen stimulated by proton precipitations that enables to calculate LBH-band luminescence pattern for given source of protons, is suggested. It is shown that for 10 keV peculiar energy values of proton precipitation the main contribution into LBH-band excitation is introduced by H-atoms. 22 refs

1995-01-01

196

A Holographic Model of Two-Band Superconductor  

CERN Multimedia

We construct a holographic two-band superconductor model with interband Josephson coupling. We investigate the effects the Josephson coupling has on the superconducting condensates and the critical temperature for their formation numerically, as well as analytically where possible. We calculate the AC conductivity and find it qualitatively similar to the single band superconductor. We investigate the nodal structure of our holographic two-band superconductor from the low temperature behavior of the thermal conductivity and find it nodeless.

Wen, Wen-Yu; Wu, Shang-Yu

2013-01-01

197

Loss of solutions in shear banding fluids in shear banding fluids driven by second normal stress differences  

CERN Document Server

Edge fracture occurs frequently in non-Newtonian fluids. A similar instability has often been reported at the free surface of fluids undergoing shear banding, and leads to expulsion of the sample. In this paper the distortion of the free surface of such a shear banding fluid is calculated by balancing the surface tension against the second normal stresses induced in the two shear bands, and simultaneously requiring a continuous and smooth meniscus. We show that wormlike micelles typically retain meniscus integrity when shear banding, but in some cases can lose integrity for a range of average applied shear rates during which one expects shear banding. This meniscus fracture would lead to ejection of the sample as the shear banding region is swept through. We further show that entangled polymer solutions are expected to display a propensity for fracture, because of their much larger second normal stresses. These calculations are consistent with available data in the literature. We also estimate the meniscus di...

Skorski, Stanislav

2011-01-01

198

Weak morphology dependent valence band structure of boron nitride  

Science.gov (United States)

We report a hard X-ray photoelectron spectroscopy (HX-PES) investigation on valence band structure of Boron Nitrides (BN) having different morphologies, including nanosheets, nanotubes, and micro-sized particles. Very weak morphology/valence band structure dependence was observed. For each case, the B-N ?-band overlapping with ?-band between 0 to -12.5 eV and the s-band below -15 eV were identified. No obvious morphology-induced band shifts and intensity variations were observed. First-principles calculations based on density functional theory were performed and the results were compared with the experimental data. This theoretical analysis well explains the weak morphology dependent valence band spectra of BN nanomaterials obtained during HX-PES measurements.

Zhi, Chunyi; Ueda, Shigenori; Zeng, Haibo; Wang, Xuebin; Tian, Wei; Wang, Xi; Bando, Yoshio; Golberg, Dmitri

2013-08-01

199

Quasiparticle calculations for metal hydrides  

Science.gov (United States)

The rare-earth hydrides YHx and LaH x are known to undergo both a conductive (metal to insulator) and optical transition (reflecting to transparent) as a function of hydrogen concentration for 2 LaH 3 and YH3, respectively. Due to mixing of the wavefunctions near the overlap region in the original band structures, we found that the dipole selection rule between the H s valence bands and the metal d bands does not hold. This is reflected in the calculated absorption spectra. A similar study of the alpha and gamma phases of MgH2 was also performed. LDA structural parameters for both phases and the alpha phase absorption edge determined from quasiparticle band structures were found to be in remarkable agreement with experiment. We completed our work with an LDA structural study of the hydrogen storage material NaAlH4.

Alford, John Ashley, II

200

Variationally-optimized muffin-tin potentials for band calculations  

International Nuclear Information System (INIS)

A method is suggested to determine the best local periodic crystal potential V(r) by minimizing the Hartree-Fock expectation value of the energy. The explicit form of the integral equation for the local exchange potential is obtained for the special case of the Muffin-tin aproximation. (author)

1979-01-01

 
 
 
 
201

Restrictive techniques: gastric banding  

Directory of Open Access Journals (Sweden)

Full Text Available Surgery for the treatment of severe obesity has a definite role onthe therapeutic armamentarium all over the world. Initiated 40years ago, bariatric surgery has already a long way thanks tohundred of surgeons, who had constantly searched for the besttechnique for the adequate control of severe obesity. Among theimportant breakthroughs in obesity surgery there is theadjustable gastric band. It is a sylastic band, inflatable andadjustable, which is placed on the top of the stomach in order tocreate a 15-20 cc pouch, with an outlet of 1.3cm. The adjustablegastric band has also a subcutaneous reservoir through whichadjustments can be made, according to the patient evolution.The main feature of the adjustable gastric band is the fact thatis minimal invasive, reversible, adjustable and placedlaparoscopically. Then greatly diminishing the surgical traumato the severe obese patient. Belachew and Favretti’s techniqueof laparoscopic application of the adjustable gastric band isdescribed and the evolution of the technique during this years,as we has been practiced since 1998. The perioperative care ofthe patient is also described, as well as the follow-up and shortand long term controls.

Sergio Roll; Katia Cristina da Cunha

2006-01-01

202

Superconducting instability in three-band metallic nanotubes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Motivated by recent experiments on small radius nanotubes, we study the superconducting instabilities of cylindrical (5,0) nanotubes. According to band-structure calculations, these nanotubes possess three bands at the Fermi energy. Using a Fermionic renormalization-group approach and a careful Boso...

Carpentier, David; Orignac, Edmond

203

Electronic band structure of PuCoGa sub 5  

CERN Multimedia

The electronic band structure is presented for PuCoGa sub 5 , the recently discovered superconductor with T sub C approx 18 K. The band structure is calculated by the tight-binding linear muffin-tin orbital method in the atomic sphere approximation. (letter to the editor)

Szajek, A

2003-01-01

204

Valence band spectroscopy in V-grooved quantum wires  

CERN Document Server

We present a combined theoretical and experimental study of the anisotropy in the optical absorption of V-shaped quantum wires. By means of realistic band structure calculations for these structures, we show that detailed information on the heavy- and light-hole states can be singled out from the anisotropy spectra {\\em independently of the electron confinement}, thus allowing accurate valence band spectroscopy.

Goldoni, G; Molinari, E; Fasolino, A; Rinaldi, R; Cingolani, R

1996-01-01

205

Exploring the origin of degenerate doublet bands in $^{106}$Ag  

CERN Document Server

The electromagnetic transition probabilities of the excited levels for the two nearly degenerate bands of $^{106}$Ag have been measured using the Doppler Shift Attenuation Method. A comparison with the calculated values using triaxial projected shell model approach indicates that these bands originate from two different quasi-particle configurations but constructed from the same mean-field deformation.

Rather, N; Chattopadhyay, S; Roy, S; Rajbanshi, S; Gowsami, A; Bhat, G H; Sheikh, J A; Palit, R; Pal, S; Saha, S; Sethi, J; Biswas, S; Singh, P; Jain, H C

2013-01-01

206

Configuration-dependent bands in 169Re  

Science.gov (United States)

High-spin states in 169Re were studied and resulted in the identification of a strongly coupled band based on the 9/2-[514] Nilsson state and a decoupled band built on the h 9/2 1/2-[541] intruder proton orbit. The cranked-shell-model calculations present configuration-dependent deformations that can explain the different band crossing frequencies. The 9/2-[514] band in 169Re shows the largest signature splitting at low spin among the known odd-mass Re isotopes. After the alignment of a pair of i 13/2 neutrons, the phase of the splitting is inverted with a significantly reduced amplitude. For the 9/2-[514] bands in light odd- A Re isotopes, the signature splitting of the Routhians and its relation with the signature dependence of M1 transition matrix elements are investigated in connection with the deviation of nuclear shape from axial symmetry, suggesting an appreciable negative ? deformation for the very neutron-deficient odd- A Re isotopes. Additionally, a three-quasipariticle band was observed and assigned to be built likely on the ? 9/2-[514] ? AE configuration.

Zhou, X. H.; Oshima, M.; Xu, F. R.; Toh, Y.; Zhang, Y. H.; Zheng, Y.; Xu, Y. B.; Koizumi, M.; Osa, A.; Hayakawa, T.; Hatsukawa, Y.; Shizuma, T.; Sugawara, M.

2004-01-01

207

Photonic band structure and omnidirectional band gap in anisotropic superlattice  

International Nuclear Information System (INIS)

We investigate theoretically the photonic band structure of one-dimensional superlattice (SL) composed of alternating anisotropic layers with their principal axis oriented at arbitrary directions. The dispersion relation of order two is calculated analytically by using the 4 x 4 matrix method which is based on boundary conditions of the electric and magnetic fields at each interface. It is shown that such structures can exhibit coupled electromagnetic modes between transverse magnetic TM and transverse electric TE modes, and dispersion curves that do not exist in superlattices composed only of isotropic layers. For a given value of the wave vector kparallel (parallel to the layers), the dispersion curves (frequency ?) versus kB (where kB is the Bloch wave vector of the periodic system along the axis of the superlattice) is illustrated. Specific applications of these results are given for the case of biaxial superlattice. With an appropriate choice of the superlattice parameters, we show that it is possible to realise, for these coupled electromagnetic waves, an absolute (or omnidirectional) band gap of width depending on the anisotropic parameters of the media forming the SL. (author)

2004-01-01

208

MEMS Calculator  

Science.gov (United States)

SRD 166 MEMS Calculator (Web, free access)   This MEMS Calculator determines the following thin film properties from data taken with an optical interferometer or comparable instrument: a) residual strain from fixed-fixed beams, b) strain gradient from cantilevers, c) step heights or thicknesses from step-height test structures, and d) in-plane lengths or deflections. Then, residual stress and stress gradient calculations can be made after an optical vibrometer or comparable instrument is used to obtain Young's modulus from resonating cantilevers or fixed-fixed beams. In addition, wafer bond strength is determined from micro-chevron test structures using a material test machine.

209

Green function approach to interface states in band inverted junctions  

CERN Document Server

We calculate interface states in semiconductor heterostructures with band inversion using a Green function approach and the so called {\\em point interaction potentials}. Effects of external fields can be included in a straightforward fashion.

Domínguez-Adame, F

1994-01-01

210

Study of positive parity bands in 137Pr  

International Nuclear Information System (INIS)

In this paper the analysis and interpretation of the positive parity states in 137Pr have been reported. The detailed interpretation with configuration assignments and the calculations for the bands will be reported

2006-01-01

211

Band structures of 121,123I  

International Nuclear Information System (INIS)

The band structures of 121,123I nuclei have been studied using a version of the particle-rotor-model in which the experimental excitation energies of the neighbouring (A-1) cores can be fed directly as input parameters. The calculations have been carried out with axially symmetric Nilsson potential with both prolate and oblate deformations. The parameters of the model have been chosen from earlier theoretical work and experimental odd-even mass differences. Only the Coriolis attenuation factor has been treated as adjustable parameter. The theoretical band structures are in very good agreement with the available experimental data. (orig.)

1995-01-01

212

Characterization of superdeformed bands in 62Zn  

International Nuclear Information System (INIS)

Combined data from four fusion-evaporation reaction experiments were utilized to investigate deformed and superdeformed structures in 3062Zn32. Combination of the Gammasphere ?-ray spectrometer and ancillary particle detection systems allowed for the connection of rotational bands to well-known, low-lying excited states in 62Zn, as well as spectroscopy of discrete high-spin states reaching excitation energies of Ex=42.5 MeV. Four well- or superdeformed bands in 62Zn are characterized and described by means of cranked Nilsson-Strutinsky calculations.

2009-01-01

213

HEMORRHOIDECTOMY VS RUBBER BAND  

Directory of Open Access Journals (Sweden)

Full Text Available Objectives: To compare open hemorrhoidectomy and Rubber Band Ligation (RBL) in the management of 2nd and 3rd degree hemorrhoids in terms post operative and hospital stay. Design: Experiential Randomized Control Trial. Setting: Department of surgery, Allied Hospital and Independent University Hospital Faisalabad. Period: Dec 2008 to May 2009. Patients & Methods: 100 consecutive patients with second and third degree hemorrhoids were randomly divided into two groups. Group A (50 patients) were operated by open hemorrhoidectomy (Milligan morgan technique) while in group B (50 patients) rubber band ligations was performed. Open hemorrhoidectomy was performed underspinal anesthesia while rubber bands were applied with local xylocaine gel using Barron’s rubber band ligator. All the three hemorrhoids wereligated in single session. Results: Average hospital stay was 24 hours in patient operated by open hemorrhoidectomy as compared to one hour in rubber band ligation. 60% patients in group A developed moderate to severe pain requiring I/V morphine derivatives while 40% developed mild pain and treated with NSAIDS. In group B only 20% patients developed moderate pain and were dealt with I/M diclofenac sodium. Eightyeight percent patients in group A and 60% patients in group B developed mild to moderate bleeding in first postoperative week, which was self limiting. 6 patients developed severe bleeding after hemorrhoidectomy requiring blood transfusion. During six month follow up, two patients (4%) of open hemorrhoidectomy and 3 patients (6%) of RBL presented with recurrence and respective procedures were repeated. Conclusions: Rubber band ligation is safe, quick, economical and effective method for the treatment of 2nd and 3rd degree hemorrhoids.

MUHAMMAD DILAWAIZ; MUHAMMAD ABID BASHIR; ABID RASHID

2011-01-01

214

Laparoscopic gastric banding.  

UK PubMed Central (United Kingdom)

Laparoscopic adjustable gastric banding is a highly effective treatment for obesity, with the broadest indications and lowest rate of early complications among the various bariatric surgeries commonly performed in the United States. Weight loss is accompanied by improvement or resolution of multiple comorbid conditions in addition to improvements in quality of life. The technique of band insertion has evolved over time, resulting in dramatic improvements of outcomes. As with any bariatric surgery, optimal results require evidence-based perioperative management, long-term routine followup, and the participation of committed patients both before and after surgery. This review encompasses the indications, technique, outcomes, and complications associated with this operation.

Richardson J; Smith B

2012-04-01

215

Ultra wide band antennas  

CERN Multimedia

Ultra Wide Band Technology (UWB) has reached a level of maturity that allows us to offer wireless links with either high or low data rates. These wireless links are frequently associated with a location capability for which ultimate accuracy varies with the inverse of the frequency bandwidth. Using time or frequency domain waveforms, they are currently the subject of international standards facilitating their commercial implementation. Drawing up a complete state of the art, Ultra Wide Band Antennas is aimed at students, engineers and researchers and presents a summary of internationally recog

Begaud, Xavier

2013-01-01

216

CONTAIN calculations  

International Nuclear Information System (INIS)

In the first phase of a benchmark comparison, the CONTAIN code was used to calculate an assumed EPR accident 'medium-sized leak in the cold leg', especially for the first two days after initiation of the accident. The results for global characteristics compare well with those of FIPLOC, MELCOR and WAVCO calculations, if the same materials data are used as input. However, significant differences show up for local quantities such as flows through leakages. (orig.).

1995-01-01

217

Electronic Band Structure of Carbon Nanotubes with Quinoid Structure  

Science.gov (United States)

In this paper, we fully describe the geometry of atomic structure of carbon nanotube with quinoid structure. Electronic energy band structure of carbon nanotubes with quinoid structure is studied by tight-binding approximation. In the presence of bond alternation, calculations show that only armchair (n, n) carbon nanotube (without twisting) remains metallic and zigzag (3? - 1, -3? + 1) CNT becomes metallic at the critical elongation. Effect of deformation on the change of band gap is also calculated and discussed.

Hieu, Nguyen Ngoc; Anh, Nguyen Pham Quynh

2013-10-01

218

Band Structure of New ReFeAsO Superconductors  

Directory of Open Access Journals (Sweden)

Full Text Available We investigate the band structure of Fe-based superconductors using the first-principle method of density-functional theory. We calculated the band structure and the density of states at the Fermi level for ReFeAsO (Re = Sm, Er) superconductors. Our calculations indicate that the maximum critical superconducting transition temperature Tc will be observed for compounds with Sm and Er at 55 and 46 K, respectively.

Sergei P. Kruchinin; Arkadiy A. Zolotovsky; Hyun-Tak Kim

2013-01-01

219

DUAL BAND MONOPOLE ANTENNA DESIGN  

Directory of Open Access Journals (Sweden)

Full Text Available The WLAN and Bluetooth applications become popular in mobile devices, integrating GSM and ISM bands operation in one compact antenna, can reduce the size of mobile devices. Recently, lot many investigations are carried out in designing a dual band antennas with operating frequencies in GSM band and in ISM band for mobile devices. Printed monopoles are under this investigation. In this paper, dual-band printed monopoles are presented to operate at GSM band i.e. 900 MHz and ISM band i.e. 2.4 GHz. We intend to observe the antenna characteristics on the network analyzer and verify the theoretical results with the practical ones.

P. Jithu; A. Paul; V. Pithadia; R. Misquitta; U. P. Khot

2013-01-01

220

Rubber Band newton Scale  

Science.gov (United States)

In this activity, learners make a simple spring-like scale using a rubber band instead of a spring, and calibrate the scale in newtons (N). Learners will gain an understanding of and familiarity with the newton as a unit of force, and use the scale to weigh common objects.

Rathjen, Don

2009-01-01

 
 
 
 
221

Rubber Band Thermodynamics  

Science.gov (United States)

In this demonstration, learners explore the thermal properties of rubber. Learners investigate whether a rubber band contracts or expands when heated. Learners discover that when rubber is heated it behaves differently than most familiar materials. Most materials expand when they are heated, but rubber contracts.

Amherst, University O.

2011-01-01

222

Rubber Band Racer  

Science.gov (United States)

In this activity, learners construct speedy vehicles made out of paper plates and powered by twisted rubber bands. This toy is an excellent demonstration of potential and kinetic energy and how things move. This project can also be used to help learners understand Newton's Laws of Motion and friction. Activity guide has detailed step-by-step instructions, illustrations, and focus questions.

Workshop, Watsonville E.

2011-01-01

223

A Holographic Flat Band  

CERN Multimedia

We describe a novel implementation of non-relativistic fermions in AdS/CFT by imposing Lorentz violating boundary conditions for a Dirac spinor in AdS4. The dual boundary theory is scale invariant and exhibits a number of interesting properties, including a dispersionless flat band of gapless excitations.

Laia, João N

2011-01-01

224

Dual band printed antenna  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The invention consists of a dual band printed antenna planned to be implemented preferably in base stations of dual mobile telephony which use GSM and DCS-1800 systems, although other applications are not rejected.Similarly to the well-known printed antennas, the invented antenna has a dielectric su...

225

Inverse of Banded Matrices.  

Science.gov (United States)

The inverses of r-banded matrices, for r = 1, 2, 3 have been thoroughly investigated as one can see from the references we provide. Let Br,n (1 less than or equal to r less than or equal to n) be an n x n matrix of entries (ai sub j), -r less than or equa...

E. Kilic P. Stanica

2013-01-01

226

Multiple antimagnetic rotation bands in odd-A 107Cd  

Science.gov (United States)

Lifetimes of the excited states of a pair of positive-parity ?I=2 bands of 107Cd have been measured by using the Doppler-shift attenuation method. The obtained B(E2) transition rates significantly decrease with increasing spin, a behavior typical of antimagnetic rotation (AMR). The observed results, interpreted by the semiclassical model (SCM) calculations, confirm these bands to be AMR bands resulting from the coupling of a pair of high-? g9/2 proton holes to aligned g7/2(h11/2)2 neutron particles. This is the first evidence for two AMR bands in a single nucleus.

Choudhury, Deepika; Jain, A. K.; Kumar, G. Anil; Kumar, Suresh; Singh, Sukhjeet; Singh, P.; Sainath, M.; Trivedi, T.; Sethi, J.; Saha, S.; Jadav, S. K.; Naidu, B. S.; Palit, R.; Jain, H. C.; Chaturvedi, L.; Pancholi, S. C.

2013-03-01

227

Multiple superdeformed bands in Sr, Y, and Zr nuclei.  

Energy Technology Data Exchange (ETDEWEB)

Multiple superdeformed bands in the nuclei [sup 80-83]Sr,[sup 82-84]Y, and [sup 83.84]Zr have been studied in a backed-target experiment using the Gammasphere and Microball detector arrays. For 15 bands in these nuclei, average transition quadrupole moments (Q[sub t]) have been measured accurately. Among those are two pairs of "isospectral" bands and the Q[sub t] values obtained in each case are nearly identical. The measured Q[sub t] values and dynamical moments of inertia place stringent conditions on configuration assignments for the bands obtained from mean field calculations.

Reviol, W.; Sarantites, D. G.; Lerma, F.; Devlin, M.; LaFosse, D. R.; Chiara, C. J.; Wyss, R.; Baktash, C.; Jin, H. Q.; Tabor, S. L.; Soltysik, D.; Clark, R. M.; Lee, I. Y.; Macchiavelli, A. O.

2003-08-14

228

Multiple Superdeformed Bands In Sr, Y, And Zr Nuclei  

Science.gov (United States)

Multiple superdeformed bands in the nuclei 80-83Sr, 82-84Y, and 83,84Zr have been studied in a backed-target experiment using the Gammasphere and Microball detector arrays. For 15 bands in these nuclei, average transition quadrupole moments (Qt) have been measured accurately. Among those are two pairs of ``isospectral'' bands and the Qt values obtained in each case are nearly identical. The measured Qt values and dynamical moments of inertia place stringent conditions on configuration assignments for the bands obtained from mean field calculations.

Reviol, W.; Sarantites, D. G.; Lerma, F.; Devlin, M.; Lafosse, D. R.; Chiara, C. J.; Wyss, R.; Baktash, C.; Jin, H.-Q.; Tabor, S. L.; Soltysik, D.; Clark, R. M.; Lee, I. Y.; Macchiavelli, A. O.; MacLeod, R. W.

2003-03-01

229

Multiple superdeformed bands in Sr, Y, and Zr nuclei  

International Nuclear Information System (INIS)

Multiple superdeformed bands in the nuclei 80-83Sr, 82-84Y, and 83,84Zr have been studied in a backed-target experiment using the Gammasphere and Microball detector arrays. For 15 bands in these nuclei, average transition quadrupole moments (Qt) have been measured accurately. Among those are two pairs of 'isospectral' bands and the Qt values obtained in each case are nearly identical. The measured Qt values and dynamical moments of inertia place stringent conditions on configuration assignments for the bands obtained from mean field calculations.

2003-03-03

230

Braille Calculator  

Directory of Open Access Journals (Sweden)

Full Text Available A thorough grounding in mathematics enhances educational and occupational opportunities for all people, whether sighted or visually impaired. In day-to-day routines, a practical understanding of mathematics allows a person to function more successfully and independently.? Access to, and doing mathematics, is one of the biggest obstacles for blind students in school and at the university. Our Braille Calculator will present new approaches to offering blind students better access to math, to provide new tools for doing math. In this report, the basic problems and solutions to the problem are discussed as a means of laying the groundwork for our Braille Calculator. Many aspects and concepts of mathematics are visual and spatial in nature. Students who are blind or visually impaired, and their teachers, now have standards which are closely aligned with those used for sighted students. Braille mathematics standards are essential to ensure that functionally blind students become literate in mathematics. However for complex engineering and statistical calculations even sighted students have to depend on Calculator. So we came up with an idea of Braille Calculator

Yoshit V. Gidh; Mahesh S. Latey; Arpita roy, Kunal Shah; Savita Ingle

2013-01-01

231

Linear methods in band theory  

DEFF Research Database (Denmark)

Two approximate methods for solving the band-structure problem in an efficient and physically transparent way are presented and discussed in detail. The variational principle for the one-electron Hamiltonian is used in both schemes, and the trial functions are linear combinations of energy-independent augmented plane waves (APW) and muffin-tin orbitals (MTO), respectively. The secular equations are therefore eigenvalue equations, linear in energy. The trial functions are defined with respect to a muffin-tin (MT) potential and the energy bands depend on the potential in the spheres through potential parameters which describe the energy dependence of the logarithmic derivatives. Inside the spheres, the energy-independent APW is that linear combination of an exact solution, at the arbitrary but fixed energy E?, and its energy derivative which matches continuously and differentiably onto the plane-wave part in the interstitial region. The energies obtained with the linear-APW method for the MT potential have errors of order (E-Ev)4. Similarly, the energy-independent MTO is that linear combination which matches onto that solution of the Laplace equation in the interstitial region which is regular at infinity. The energies obtained with the linear-MTO method have additional errors of order (E-Vmtz)2, arising from the interstitial region where the potential is Vmtz. The linear-APW (LAPW) method combines desirable features of the APW and OPW methods; it can treat d bands, the energy dependence of its pseudopotential is linear and, owing to the smoothness of the energy-independent APW at the spheres, non-MT contributions to the potential are included principally through their Fourier components. The linear-MTO (LMTO) method is particularly suited for closely packed structures and it combines desirable features of Korringa-Kohn-Rostoker, linear-combination-of-atomic-orbitals, and cellular methods; the secular matrix is linear in energy, the overlap integrals factorize as potential parameters and structure constants, the latter are canonical in the sense that they neither depend on the energy nor the cell volume and they specify the boundary conditions on a single MT or atomic sphere in the most convenient way. This method is very well suited for self-consistent calculations. The empty-lattice test is applied to the linear-MTO method and the free-electron energy bands are accurately reproduced. Finally, it is shown how relativistic effects may be included in both the LAPW and LMTO methods.

Andersen, O. Krogh

1975-01-01

232

Mercury Calculator  

Science.gov (United States)

This interactive calculator produced by Teachers' Domain helps you determine the mercury levels in various types of fish, and enables you to make more informed choices about which fish are safe to eat and which should be avoided or eaten infrequently.

Foundation, Wgbh E.

2010-12-23

233

Inflation Calculator  

Science.gov (United States)

This simple inflation calculator uses the Consumer Price Index to adjust any given amount of money, from 1800 to 1998. Creator S. Morgan Friedman uses data from the Historical Statistics of the United States for statistics predating 1975 and the annual Statistics Abstracts of the United States for data from 1975 to 1998. Links to other online inflation information are also included.

Friedman, S. M.

234

Firewood calculator  

Energy Technology Data Exchange (ETDEWEB)

Rotating cardboard discs are used to read off total tree or topwood firewood volume (tons or cords) that can be expected from trees of d.b.h. 6 to 24 inches and tree height 10 to 90 feet. One side of the calculator is used for broadleaved species with deliquescent crowns and the other side for braodleaves with excurrent crowns.

Clark, A.; Curtis, A.B.; Darwin, W.N.

1981-01-01

235

HELIOS calculations  

International Nuclear Information System (INIS)

[en] Comparison of HELIOS and KASSETA-TWEG spectral codes is presented. Benchmark for WWER-440 FA Burn-Up Comparison (P. Mikolas, Sixth Symposium of AER, Kirkonummi 1996) and typical Kasseta type burn-up calculation for macro code data preparation are used for comparison. Differences of reactivity effects are discussed. (Authors)

2000-01-01

236

NANO CALCULATORS  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The whole circuit is obtained from the sun through a molecule called "Rhodopsin and bacteriorhodopsin". These molecules have the capability of trapping and storing energy from the sun light. These molecules are placed on the outer surface of the calculator to trap the energy and store it themselves ...

Venkatesh Kumaran, P.

237

Rotational band 111Sn  

International Nuclear Information System (INIS)

Partial level scheme of the neutron deficient 111Sn isotope is established upto an excitation energy of about 9 MeV and I? = 43/2- from ?-rays following 103Rh(12C,p3n) reaction. Clear evidence for the existence of a negative parity rotational band above I? = 23/2-, most probably based on 3p-2h configuration, is obtained. (orig.)

1995-01-01

238

Banded electromagnetic stator core  

Energy Technology Data Exchange (ETDEWEB)

A stator core for an electromagnetic pump includes a plurality of circumferentially adjoining groups of flat laminations disposed about a common centerline axis and collectively defining a central bore and a discontinuous outer perimeter, with adjacent groups diverging radially outwardly to form V-shaped gaps. An annular band surrounds the groups and is predeterminedly tensioned to clamp together the laminations, and has a predetermined flexibility in a radial direction to form substantially straight bridge sections between the adjacent groups.

Fanning, Alan W. (San Jose, CA); Gonzales, Aaron A. (San Jose, CA); Patel, Mahadeo R. (San Jose, CA); Olich, Eugene E. (Aptos, CA)

1996-01-01

239

Banded electromagnetic stator core  

Energy Technology Data Exchange (ETDEWEB)

A stator core for an electromagnetic pump includes a plurality of circumferentially adjoining groups of flat laminations disposed about a common centerline axis and collectively defining a central bore and a discontinuous outer perimeter, with adjacent groups diverging radially outwardly to form V-shaped gaps. An annular band surrounds the groups and is predeterminedly tensioned to clamp together the laminations, and has a predetermined flexibility in a radial direction to form substantially straight bridge sections between the adjacent groups.

Fanning, Alan W. (San Jose, CA); Gonzales, Aaron A. (San Jose, CA); Patel, Mahadeo R. (San Jose, CA); Olich, Eugene E. (Aptos, CA)

1994-01-01

240

Energy band picture  

International Nuclear Information System (INIS)

By a refined one-electron band theory, the origins of the major experimental frequency branches of de Haas-van Alphen effect observed in the Ce compounds belonging to the valence-fluctuation regime and the moderately heavy-electron regime have recently been clarified on an itinerant-electron model for the 4f electrons. It means that the energy band picture works fairly well for the 4f electrons in the Ce compounds of these regimes, as far as the Fermi surface shape is concerned. In this review, a newly completed, self-consistent symmetrized relativistic APW approach is outlined, and results of the application to CeSn3, CeNi and CeRu2Si2 are summarized. The same approach has been applied to such U compounds as UC and UB12 on an itinerant-electron model for the 5f electrons, and their Fermi surface has been clarified successfully. Results for these U compounds are summarized also. The large cyclotron effective masses and the large electronic specific heat coefficients which are observed in all these f-electron compounds except UB12 cannot be explained by the band structure alone, and their quantitative analysis remains to be solved by many-body theory. (author).

1993-01-01

 
 
 
 
241

Calculator thermometer  

International Nuclear Information System (INIS)

An inexpensive substitution for calibrated thermocouples, linearizing electronics, and the NBS thermocouple tables is obtained through the use of a hand-held calculator. Automatic offset corrections and interpolations to an output temperature are possible in a one button operation beginning with voltmeter EMF. The inverse operation is also given. Appropriate constants have been found for the Cu-constantan, iron-constantan, and chromel-alumel thermocouples

1979-01-01

242

Burnout calculation  

International Nuclear Information System (INIS)

[en] Reviewed is the effect of heat flux of different system parameters on critical density in order to give an initial view on the value of several parameters. A thorough analysis of different equations is carried out to calculate burnout is steam-water flows in uniformly heated tubes, annular, and rectangular channels and rod bundles. Effect of heat flux density distribution and flux twisting on burnout and storage determination according to burnout are commended

1980-01-01

243

Confidence Bands under Proportional Hazards.  

Science.gov (United States)

Asymptotic simultaneous confidence bands are derived for the survival function under the proportional hazards model of random right-censorship. These bands are based on the maximum likelihood estimater of the survival function, rather than the well-known ...

M. Hollander E. Pena

1986-01-01

244

Remote Sensing Interactive: Band Combination  

Science.gov (United States)

Band Combination is one of a number of interactive tools being developed to illustrate basic remote sensing concepts. Here, the user is able to experiment with RGB bands on three different image modes: MODIS, ASTER and LANDSAT.

245

The energy bands of deformed and superdeformed nuclei  

International Nuclear Information System (INIS)

With the help of quantum group SUq(2) the energy bands of deformed and superdeformed nuclei has been calculated and their comparison with the experimental data has been made. For illustration calculation were made for 194Pb and 162Dy nuclei

1995-01-01

246

Velcro band type fixing band for clavicalis fracture  

UK PubMed Central (United Kingdom)

A catch compression band of fracture of clavicle belongs to medical appliances. It solves the current problem of difficult fixation of the fracture of clavicle in the reposition operation. The clavicle pressure pad is connected with the long band in the manner of slip-joint connection through a sleeve band. There are catches in the two ends of the long band, and there is soft material on the sides of both the pressure pad and the long band to contact with the body. When in use, the long band is surrounding the neck of the patient, adjust the position of the pressure pad to make it press on the clavicle for fixation, and the long band passes by the armpit to the back of the patient for connection and fixation. The fixation method is simple, the patient feels comfortable after use, and it is easy to adjust the device for stable fixation of the bone fracture.

SUN CHUNRUI FENG

247

Broad band waveguide spectrometer  

Science.gov (United States)

A spectrometer for analyzing a sample of material utilizing a broad band source of electromagnetic radiation and a detector. The spectrometer employs a waveguide possessing an entry and an exit for the electromagnetic radiation emanating from the source. The waveguide further includes a surface between the entry and exit portions which permits interaction between the electromagnetic radiation passing through the wave guide and a sample material. A tapered portion forms a part of the entry of the wave guide and couples the electromagnetic radiation emanating from the source to the waveguide. The electromagnetic radiation passing from the exit of the waveguide is captured and directed to a detector for analysis.

Goldman, Don S. (Folsom, CA)

1995-01-01

248

Broad band waveguide spectrometer  

Energy Technology Data Exchange (ETDEWEB)

A spectrometer is disclosed for analyzing a sample of material utilizing a broad band source of electromagnetic radiation and a detector. The spectrometer employs a waveguide possessing an entry and an exit for the electromagnetic radiation emanating from the source. The waveguide further includes a surface between the entry and exit portions which permits interaction between the electromagnetic radiation passing through the waveguide and a sample material. A tapered portion forms a part of the entry of the waveguide and couples the electromagnetic radiation emanating from the source to the waveguide. The electromagnetic radiation passing from the exit of the waveguide is captured and directed to a detector for analysis. 16 figs.

Goldman, D.S.

1995-08-29

249

Band structure and superconductivity of BCC tellurium under pressure  

International Nuclear Information System (INIS)

[en] We report a theoretical calculation of the band structure and superconductivity of Te in the BCC phase under pressure. The energy band structure and the effect of pressure on the band structure is obtained by means of the linear muffin-tin orbital method. The superconducting transition temperature (Tc) is calculated using McMillan's formula. The calculated value of Tc of Te in the BCC phase at 27.3 GPa is 7.16 K. Further increase in pressure decreases the Tc values. The calculated value of resistivity at 27.3 GPa is 4.37 ?? cm and further increase in pressure decreases the resistivity, which is a typical behaviour of a number of elemental metals under pressure. (orig.)

1993-01-01

250

Reliability calculations  

International Nuclear Information System (INIS)

[en] Risk and reliability analysis is increasingly being used in evaluations of plant safety and plant reliability. The analysis can be performed either during the design process or during the operation time, with the purpose to improve the safety or the reliability. Due to plant complexity and safety and availability requirements, sophisticated tools, which are flexible and efficient, are needed. Such tools have been developed in the last 20 years and they have to be continuously refined to meet the growing requirements. Two different areas of application were analysed. In structural reliability probabilistic approaches have been introduced in some cases for the calculation of the reliability of structures or components. A new computer program has been developed based upon numerical integration in several variables. In systems reliability Monte Carlo simulation programs are used especially in analysis of very complex systems. In order to increase the applicability of the programs variance reduction techniques can be applied to speed up the calculation process. Variance reduction techniques have been studied and procedures for implementation of importance sampling are suggested. (author)

1986-01-01

251

About a possibility of mixing of gr, ?-, ?- and S bands (example of 232Th nucleus)  

International Nuclear Information System (INIS)

To study characteristics of states of positive parity in 232Th nucleus a simple phenomenological model is proposed in which the existence of S-band (Ksup(?)=1+) and Coriolis coupling of gr, ?, ? and S-bands is assumed. The spectra of states, E2-transition ratios out of ? and ?-bands into ground band states have been calculated. The comparison with experimental values is presented. The model used reproduces well the known levels of rotational bands and complicated spin dependence of the ratio of E2-transitions out of ?-band

1985-01-01

252

Hybrid Functional Studies on Impurity-Concentration-Controlled Band Engineering of Chalcogen-Hyperdoped Silicon  

Science.gov (United States)

We employ the hybrid functional method to study the impurity-concentration-controlled band engineering of chalcogen-hyperdoped silicon. The variations of defect band width and distance to the conduction band with increasing impurity concentration are given, in which at very low concentration, the reasonable depths of defect states and the energy gap compared with the experiments indicate the good accuracy of hybrid functional calculations for the band structures. For S- and Se-doped silicon, the critical concentrations for the merging of defect and conduction bands are obtained. At the key concentrations related to the insulator-to-metal transition, the characteristics of band structures are discussed.

Shao, Hezhu; Liang, Cong; Zhu, Zhen; Ning, Bo-Yuan; Dong, Xiao; Ning, Xi-Jing; Zhao, Li; Zhuang, Jun

2013-08-01

253

Structures calculation  

International Nuclear Information System (INIS)

Structures calculation is a research and applications field in permanent evolution thanks to the development of more and more performing computer tools for the modeling and the numerical simulation of complex structures taking into account the behaviour of more and more sophisticated materials. The aim of the Computational Structural Mechanics Association (CSMA) is to develop technical and scientific exchanges between industrial and research partners. This colloquium, organized every 2 years comprises 4 general conferences and 125 communications. Five papers were selected for INIS. Three of them deal with the dynamical modeling of the vibrational behaviour of reactor core components (fuel assemblies and control rod clusters), one concerns the load resistance of multi-perforated metal structures like steam generator tube plates or turbine blades, and the last paper concerns the humidity stability of composite materials used in particle detectors. (J.S.).

1997-01-01

254

Probability Calculator  

Science.gov (United States)

This tool lets you calculate the probability that a random variable X is in a specified range, for a variety of probability distributions for X: the normal distribution, the binomial distribution with parameters n and p, the chi-square distribution, the exponential distribution, the geometric distribution, the hypergeometric distribution, the negative binomial distribution, the Poisson distribution, and Student's t-distribution. The first choice box lets you select a probability distribution. Depending on the distribution you select, text areas will appear for you to enter the values of the parameters of the distribution. Parameters that are probabilities (e.g., the chance of success in each trial for a binomial distribution) can be entered either as decimal numbers between 0 and 1, or as percentages. If you enter a probability as a percentage, be sure to include the percent sign (%) after the number.

Stark, Philip B.

2009-01-08

255

Rotational bands of 156Gd  

Science.gov (United States)

High-spin states of 156Gd have been studied by using the reaction 150Nd(13C/,?3n). The ground-state band, /? band, and octupole band have been extended up to 26+, 16+, and 21- states respectively. Gamma-ray branchings between E2 decays down the K=1- band and E1 decays across to the ground band are discussed on the basis of the Generalized Intensity Relations. It is found that the /B(E1)/B(E2) ratios have the maximum value at the intermediate spin. This feature is quite similar to the the case of the lowest octupole K=0- band in 238U and is not yet resolved. Moreover a new band in the spin range of /(10,11)<=I<=(20,21) was observed, whose /?-rays turned out to be almost identical in energy to the ones found in the isotone 158Dy.

Sugawara, M.; Mitarai, S.; Kusakari, H.; Oshima, M.; Hayakawa, T.; Toh, Y.; Hatsukawa, Y.; Katakura, J.; Iimura, H.; Zhang, Y. H.; Sugie, M.; Sato, Y.

2001-04-01

256

Lone conduction band in Cu2ZnSnSe4  

Science.gov (United States)

We present experimental proof for a narrow first conduction band in Cu2ZnSnSe4 semiconductor films as it has been predicted by theoretical calculations. The optical absorption characteristics of Cu2ZnSnSe4 thin films are analyzed by optical transmission spectroscopy. The experimental data show strong evidence for three absorption edges, as expected from theory, involving the valence band and two conduction bands, which are separated by a second band gap.

Gütay, Levent; Redinger, Alex; Djemour, Rabie; Siebentritt, Susanne

2012-03-01

257

Ab Initio Calculations of Oxosulfatovanadates  

DEFF Research Database (Denmark)

Restricted Hartree-Fock and multi-configurational self-consistent-field calculations together with secondorder perturbation theory have been used to study the geometry, the electron density, and the electronicspectrum of (VO2SO4)-. A bidentate sulphate attachment to vanadium was found to be stable with anO-V-O angle of 72.5 degrees . The calculated spectrum shows bands in reasonable agreement with anexperimental spectrum which has been attributed to (VO2SO4)-. The geometry and the electron density fortwo binuclear vanadium complexes proposed as intermediates in the vanadium catalyzed SO2 oxidationhave further been studied.

FrØberg, Torben; Johansen, Helge

1996-01-01

258

A Multi-band Wavelet Watermarking Scheme  

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents a new multi-band wavelet watermarking scheme. Compared with conventional watermarking schemes implemented in two-band wavelet domain, by incorporating the principal component analysis (PCA) technique the proposed blind watermarking in the multi-band wavelet domain can achieve higher perceptual transparency and stronger robustness. Specifically, the developed watermarking scheme can successfully resist common signal processing such as JPEG compression with quality factor as low as 15, and some geometric distortions such as cropping (cropped by 50\\%). In addition, the proposed multi-band wavelet based watermarking scheme can be parameterized, thus resulting in more security. That is, an attacker may not be able to detect the embedded watermark if the attacker does not know the parameter. Different from many other watermarking schemes, in which the watermark detection threshold is chosen empirically, the false positive rate of the proposed watermarking scheme can be calculated analytically so that watermark detection threshold can be chosen based solely on the targeted false positive.

Xiangui Kang; Wenjun Zeng; Jiwu Huang

2008-01-01

259

Spectral electron momentum density calculation in graphite  

Energy Technology Data Exchange (ETDEWEB)

The linear muffin-tin orbital method has been used to calculate energy-momentum distribution of valence electrons in graphite along major symmetry directions and as the spherical average over the irreducible wedge of the Brillouin zone. These data bridge the gap between existing band structure calculations and emerging electron momentum spectroscopy of solids. The calculation has been validated by comparison to the most accurate experimental data on the highly oriented laser annealed carbon films. 14 refs., 1 tab., 4 figs.

Kheifets, A.S.; Vos, M.

1995-02-01

260

Spectral electron momentum density calculation in graphite  

International Nuclear Information System (INIS)

The linear muffin-tin orbital method has been used to calculate energy-momentum distribution of valence electrons in graphite along major symmetry directions and as the spherical average over the irreducible wedge of the Brillouin zone. These data bridge the gap between existing band structure calculations and emerging electron momentum spectroscopy of solids. The calculation has been validated by comparison to the most accurate experimental data on the highly oriented laser annealed carbon films. 14 refs., 1 tab., 4 figs.

1995-01-01

 
 
 
 
261

Theory of two-photon absorption by exciton states in cubic semiconductors with degenerate valence bands  

International Nuclear Information System (INIS)

[en] The coefficient of the absorption of two polarized photons is calculated for direct band gap semiconductors with degenerate valence bands. Wannier-Mott exciton states are included in both the intermediate and final states. Numerical calculations are performed for ZnSe and are compared with Sondergeld's experimental and theoretical results. (author). 11 refs, 2 tabs

1987-01-01

262

Tunable and sizable band gap in silicene by surface adsorption.  

UK PubMed Central (United Kingdom)

Opening a sizable band gap without degrading its high carrier mobility is as vital for silicene as for graphene to its application as a high-performance field effect transistor (FET). Our density functional theory calculations predict that a band gap is opened in silicene by single-side adsorption of alkali atom as a result of sublattice or bond symmetry breaking. The band gap size is controllable by changing the adsorption coverage, with an impressive maximum band gap up to 0.50 eV. The ab initio quantum transport simulation of a bottom-gated FET based on a sodium-covered silicene reveals a transport gap, which is consistent with the band gap, and the resulting on/off current ratio is up to 10(8). Therefore, a way is paved for silicene as the channel of a high-performance FET.

Quhe R; Fei R; Liu Q; Zheng J; Li H; Xu C; Ni Z; Wang Y; Yu D; Gao Z; Lu J

2012-01-01

263

Band crossing in the superdeformed bands in {sup 145}Gd  

Energy Technology Data Exchange (ETDEWEB)

Gamma-rays emitted from {sup 145}Gd excited in the heavy ion reaction of {sup 36}S with the {sup 114}Cd target at energy of 182 MeV have been investigated. Two new superdeformed bands have been established, consisting of 18 and 17 transitions. The first excited superdeformed band shows two subsequent band crossing at rotational frequency of about 0.4 and 0.68 MeV. 2 figs, 2 refs.

Rzaca-Urban, T. [Warsaw Univ., Inst. of Experimental Physics, Warsaw (Poland); Lieder, R.M.; Utzelmann, S. [Forschungszentrum Juelich GmbH, Inst. fuer Kernphysik, Juelich (Germany)

1995-12-31

264

M-Band Graphic Equalizer  

Directory of Open Access Journals (Sweden)

Full Text Available This paper deals with the concept of filter banks. Filter banks are a group of band-pass filters connected in parallel. Each parallel connection forms a channel for different frequency-bands present in the input signal. The output of the filter bank is formed by merging these channels. The main theme behind the use of filter banksis to boost or attenuate different individual bands of frequencies present in a signal, without affecting other bands. There are several ways of realizing an filter bank and one such way is the Cosine Modulated filter bank. Instead of designing band-pass filters for different bands, the cosine modulated filter banks, modulates a lowpass filter. In simple words, it simply shifts the pass band of the low pass filter towards higher frequencies, and there by covering the entire band of frequencies of the input signal. Filter banks have many applications in the field of signal processing. Perhaps one of the biggest applications is Graphic Equalizer, where in, the user can‘graphically’ modify different bands. The design and implementation of a filter bank as M-Band Graphic Equalizer is covered in this paper.

Prof. Ch.Srinivasa Kumar; Dr. P. Mallikarjuna Rao

2011-01-01

265

Systematic description of superdeformed bands in the mass-190 region  

Energy Technology Data Exchange (ETDEWEB)

Superdeformed bands for the mass-190 region are described by the Projected Shell Model. Even-even, odd mass and odd-odd nuclei are equally well described. Good agreement with available data for all isotopes studied is obtained. The authors calculation of electromagnetic properties and pairing correlations provides an understanding of the observed gradual increase of dynamical moments of inertia with angular momentum observed in many bands in this mass region.

Sun, Yang; Guidry, M. [Oak Ridge National Lab., TN (United States)]|[Univ. of Tennessee, Knoxville, TN (United States); Zhang, Jing-ye [Univ. of Tennessee, Knoxville, TN (United States)

1996-12-31

266

Systematic description of superdeformed bands in the Mass-190 region  

Energy Technology Data Exchange (ETDEWEB)

Superdeformed bands for the mass-190 region are described by the Projected Shell Model. Even-even, odd mass and odd-odd nuclei are equally well described. Good agreement with available data for all isotopes studied is obtained. Our,calculation of electromagnetic properties and pairing correlations provides an understanding of the observed gradual increase of dynamical moments of inertia with angular momentum observed in many bands in this mass region.

Sun, Y.; Guidry, M. [Oak Ridge National Lab., TN (United States)][Tennessee Univ., Knoxville, TN (United States). Dept. of Physics and Astronomy; Zhang, J. [Tennessee Univ., Knoxville, TN (United States). Dept. of Physics and Astronomy

1996-12-31

267

Prompt Proton Decay and Deformed Bands in 56Ni  

International Nuclear Information System (INIS)

High-spin states in the doubly magic N=Z nucleus 56Ni have been investigated with three fusion-evaporation reaction experiments. New ?-ray transitions are added, and a confirmation of a previously suggested prompt proton decay from a rotational band in 56Ni into the ground state of 55Co is presented. The rotational bands in 56Ni are discussed within the framework of cranked Nilsson-Strutinsky calculations.

2008-06-01

268

Band erosion: laparoscopic removal of lap-band.  

UK PubMed Central (United Kingdom)

Laparoscopic gastric banding is in the category of purely restrictive gastric procedures. It offers the advantage of being minimally invasive, adjustable, and reversible. The incidence of band erosion with penetration into stomach is well documented in literature. We present a case of band erosion and simultaneous laparoscopic removal of lap-band through the same incisions used for its placement. The stomach was repaired with laparoscopic suture placement and an omental patch was placed on top of the repair along with fibrin glue and a JP drain. An upper gastrointestinal study demonstrated no extravasation of contrast and the patient was discharged postoperative day 1.

Ayloo S; Bueno R

2009-03-01

269

High-spin intruder band in $^{107}$In  

CERN Multimedia

High-spin states in the neutron deficient nucleus $^{107}$In were studied via the $^{58}$Ni($^{52}$Cr, 3p) reaction. In-beam $\\gamma$ rays were measured using the JUROGAM detector array. A rotational cascade consisting of ten $\\gamma$-ray transitions which decays to the 19/2$^{+}$ level at 2.002 MeV was observed. The band exhibits the features typical for smooth terminating bands which also appear in rotational bands of heavier nuclei in the A$\\sim$100 region. The results are compared with Total Routhian Surface and Cranked Nilsson-Strutinsky calculations.

Ideguchi, E; Ganio?lu, E; Hadinia, B; Lagergren, K; Bäck, T; Johnson, A; Wyss, R; Eeckhaudt, S; Grahn, T; Greenlees, P; Julin, R; Juutinen, S; Kettunen, H; Leino, M; Leppanen, A -P; Nieminen, P; Nyman, M; Pakarinen, J; Rahkila, P; Scholey, C; Uusitalo, J; Joss, D T; Paul, E S; Wiseman, D R; Wadsworth, R; Afanasjev, A V; Ragnarsson, I

2010-01-01

270

High-spin intruder band in 107In  

International Nuclear Information System (INIS)

High-spin states in the neutron-deficient nucleus 107In were studied via the 58Ni(52Cr,3p) reaction. In-beam ? rays were measured using the JUROGAM detector array. A rotational cascade consisting of ten ?-ray transitions, which decays to the 19/2+ level at 2.002 MeV, was observed. The band exhibits the features typical for smooth terminating bands that also appear in rotational bands of heavier nuclei in the A ? 100 region. The results are compared with total Routhian surface and cranked Nilsson-Strutinsky calculations.

2010-01-01

271

Rotational bands and noncollective structures in 85Zr  

International Nuclear Information System (INIS)

The structure of the transitional nucleus 85Zr has been investigated through spectroscopy and lifetime measurements. States up to spins of (45/2)(?/2?) and (39/2)(?/2?) in the positive and negative parity bands, respectively, have been established through ?-? coincidence measurements. The results indicate that there is a competition between collective and noncollective modes of excitation. Two pronounced band crossings have been observed in the positive parity sequence, while none is evident in the negative parity states. The pattern of shape evolution in the positive and negative parity bands is markedly different. The results of the experiments qualitatively corroborate the predictions of total Routhian surface calculations

2002-01-01

272

Banding on the waders and terns between Australia and China  

UK PubMed Central (United Kingdom)

The paper summarizes the methods (catch, bio-metric data, banding, recoveries, flagging, satellite tracking, data analysis on computer, fox control et al.) and results (species of wader and tern, number of banding from 1975 to 1999, calculate the minimum age, breeding success, age of first breeding, levels of fat deposits, molt, the distance of moved) and discuss. The total 141 787 waders, about 35 species (from 1975 to 1999) and 6 057 chicks and adults of terns, about 7-9 species (1998-1999) were captured and banded by the Victorian Wader Study Group.

Ma Ming; Minton C; Kraaijeveld K; Jessop R; Gosbell K

2001-01-01

273

Detailed band structures in 189Hg and 190Hg  

International Nuclear Information System (INIS)

The level structures of the 189Hg and 190Hg nuclei have been extended considerably from earlier studies by using the 160Gd(34S, 4n and 5n) reactions in conjunction with an array of twelve Compton suppressed Ge detectors. Eight band structures have been delineated in 189Hg and ten in 190Hg. Most bands can be understood within the framework of cranked shell model calculations assuming an oblate collective shape and specific quasiparticle configurations are proposed. There is also some evidence for the onset of triaxiality. In both nuclei level structures which appear to be non-collective in character are interpreted in a band termination picture. ((orig.)).

1994-01-01

274

Electronic band structure and photoemission: A review and projection  

International Nuclear Information System (INIS)

A brief review of electronic-structure calculations in solids, as a means of interpreting photoemission spectra, is presented. The calculations are, in general, of three types: ordinary one-electron-like band structures, which apply to bulk solids and are the basis of all other calculations; surface modified calculations, which take into account, self-consistently if at all possible, the presence of a vacuum-solid interface and of the electronic modifications caused thereby; and many-body calculations, which go beyond average-field approximations and consider dynamic rearrangement effects caused by electron-electron correlations during the photoemission process. 44 refs

1987-01-01

275

Scarless platysmaplasty for platysmal bands  

Directory of Open Access Journals (Sweden)

Full Text Available Transection of plastysmal bands has required a surgical approach that leaves scars and limits patient activities for a period of time. The author has developed a simple method to transect the platysmal bands under local anesthesia without resorting to skin incisions. The transection is performed with the use of a Vicryl ® suture that is inserted through the skin, around the platysmal band, and then out through the original entry point. A back and forth motion of the suture cuts through the band.

Shiffman Melvin; Mirrafati Sid

2004-01-01

276

Superdeformed band in 192Hg  

International Nuclear Information System (INIS)

[en] The observation of a superdeformed band in the nucleus 192Hg is reported. The band has sixteen transitions with an average energy spacing of 36 keV and an average dynamic moment of inertia scrI(2) of 112 ?2 MeV-1. This band persists to rather low rotational frequency (???0.125 MeV) and is proposed to extend in spin from 10+ to 42+. No transitions linking the superdeformed states and the low deformation yrast levels were found and the decay out of the superdeformed band appears to be statistical. This is the second case of superdeformation in the A?190 region

1990-01-01

277

Smooth band termination at high spin in 113I  

Science.gov (United States)

The 113I nucleus has been studied using the 58Ni(58Ni,3p) reaction at 250 MeV with the Gammasphere/Microball facility. Gamma-ray three- and four-fold data gated by charged particle combinations were analyzed. Multipolarities of the ? rays were assigned following the angular correlation measurements. The present study is focused on the high spin properties, where the structure is dominated by 2p-2h excitations across the Z=50 gap. Ten decoupled bands showing the features of smooth band termination were observed; three of those bands are linked to known low-spin states, which allows the identification of configurations by direct comparisons with configuration-dependent cranked Nilsson-Strutinsky calculations. The yrast band, which was linked along with the signature partner, was followed up to (101/2+) and ??~1.3 MeV. The other linked band was a negative-parity band observed up to (95/2-). Tentative configurations for the unlinked bands are discussed. Comparisons with the theoretical results suggest that the band built on a configuration involving the neutron i13/2 intruder orbital originating from the N=6 harmonic oscillator subshell was observed in this experiment.

Starosta, K.; Chiara, C. J.; Fossan, D. B.; Koike, T.; Lafosse, D. R.; Lane, G. J.; Sears, J. M.; Smith, J. F.; Boston, A. J.; Nolan, P. J.; Paul, E. S.; Semple, A. T.; Devlin, M.; Sarantites, D. G.; Lee, I. Y.; Macchiavelli, A. O.; Ragnarsson, I.

2001-07-01

278

Band properties of the transitional nucleus Pt187  

Science.gov (United States)

High-spin states in Pt187 have been studied experimentally using the Yb173(O18, 4n) reaction at beam energies of 78 and 85 MeV. The previously known bands based on the ?i13/2,?7/2-[503], and ?i13/22?j configurations have been extended to high-spin states, and new rotational bands associated with the ?3/2-[512] and ?1/2-[521] Nilsson orbits have been identified. The total Routhian surface calculations indicate that the transitional nucleus Pt187 is very soft with respect to ? and ? deformations. The band properties, such as level spacings, band crossing frequencies, alignment gains, and signature splittings, have been compared with the systematics observed in neighboring nuclei and have been interpreted within the framework of the cranked shell model. The rotational bands show different band crossing frequencies, which can be explained by the alignment either of i13/2 neutrons or of h9/2 protons. Importantly, evidence is presented for a ?h9/2 alignment at very low frequency in the ?7/2-[503] band. The proton nature of the band crossing is strongly suggested by comparing the measured B(M1;I?I-1)/B(E2;I?I-2) ratios with the theoretical values from the semiclassical Dönau and Frauendof approach.

Zhou, X. H.; Xing, Y. B.; Liu, M. L.; Zhang, Y. H.; Guo, Y. X.; Ma, L.; Lei, X. G.; Guo, W. T.; Oshima, M.; Toh, Y.; Koizumi, M.; Osa, A.; Hatsukawa, Y.; Xu, F. R.; Sugawara, M.

2007-03-01

279

GW quasiparticle band structures of stibnite, antimonselite, bismuthinite, and guanajuatite  

Science.gov (United States)

We present first-principles calculations of the quasiparticle band structures of four isostructural semiconducting metal chalcogenides A2B3 (with A = Sb, Bi and B = S, Se) of the stibnite family within the G0W0 approach. We perform extensive convergence tests and identify a sensitivity of the quasiparticle corrections to the structural parameters and to the semicore d electrons. Our calculations indicate that all four chalcogenides exhibit direct band gaps, if we exclude some indirect transitions marginally below the direct gap. Relativistic spin-orbit effects are evaluated for the Kohn-Sham band structures, and included as scissor corrections in the quasiparticle band gaps. Our calculated band gaps are 1.5 eV (Sb2S3), 1.3 eV (Sb2Se3), 1.4 eV (Bi2S3), and 0.9 eV (Bi2Se3). By comparing our calculated gaps with the ideal Shockley-Queisser value we find that all four chalcogenides are promising as light sensitizers for nanostructured photovoltaics.

Filip, Marina R.; Patrick, Christopher E.; Giustino, Feliciano

2013-05-01

280

Spectra of {gamma} rays feeding superdeformed bands  

Energy Technology Data Exchange (ETDEWEB)

The spectrum of {gamma}rays coincident with SD transitions contains the transitions which populate the SD band. This spectrum can provide information on the feeding mechanism and on the properties (moment of inertia, collectivity) of excited SD states. We used a model we developed to explain the feeding of SD bands, to calculate the spectrum of feeding {gamma}rays. The Monte Carlo simulations take into account the trigger conditions present in our Eurogam experiment. Both experimental and theoretical spectra contain a statistical component and a broad E2 peak (from transitions occurring between excited states in the SD well). There is good resemblance between the measured and calculated spectra although the calculated multiplicity of an E2 bump is low by {approximately}30%. Work is continuing to improve the quality of the fits, which will result in a better understanding of excited SD states. In addition, a model for the last steps, which cool the {gamma} cascade into the SD yrast line, needs to be developed. A strong M1/E2 low-energy component, which we believe is responsible for this cooling, was observed.

Lauritsen, T.; Khoo, T.L.; Henry, R.G. [and others

1995-08-01

 
 
 
 
281

A model for shear-band formation and high-explosive initiation in a hydrodynamics code  

Energy Technology Data Exchange (ETDEWEB)

This report describes work in progress to develop a shear band model for MESA-2D. The object of this work is (1) to predict the formation of shear bands and their temperature in high explosive (HE) during a MESA-2D calculation, (2) to then assess whether the HE would initiate, and (3) to allow a detonation wave initiated from a shear band to propagate. This requires developing a model that uses average cell data to estimate the size and temperature of narrow region (generally much narrower than the cell size) that is undergoing shear within the cell. The shear band temperature (rather than the average cell temperature) can be used to calculate the flow stress of the material in the cell or to calculate heat generation from reactive materials. Modifications have been made to MESA-2D to calculate shear band size and temperature, and to initiate HE detonation when conditions warrant. Two models have been used for shear-band size and temperature calculation, one based on an independent estimate of the shear band width and a second based on the temperature distribution around the shear band. Both models have been tested for calculations in which shear band formation occurs in steel. A comparison of the measured and calculated local temperature rise in a shear band has been made. A model for estimating the time to initiation of the HE based on the type of HE and the temperature distribution in a shear band has also been added to MESA-2D. Calculations of conditions needed to initiate HE in projectile-impact tests have been done and compared with experimental data. Further work is d to test the model.

Kerrisk, J.F.

1996-03-01

282

A theoretical approach to the design of reduced band gap noncorrosive electrodes for photoelectrochemical solar cells  

International Nuclear Information System (INIS)

[en] Preliminary results from our charge self-consistent LCAO band structure (CSCBS) calculations with Bloch sums as the basis reveal that a noncorrosive reduced band gap electrode for photoelectrochemical solar cells may be produced from a (1:1) mixture of ?-PbO2 and TiO2 (both rutile). The band gaps for the constituents (?-PbO2 and TiO2) and the 1:1 mixture are calculated and a detailed characterization of the valence and the conduction bands is undertaken to offer a possible mechanism for the reduction of the band gap of the mixture. The band gap for the perovskite PbTiO3 is also calculated to offer a guideline for selecting from the competing pathways to the fabrication of noncorrosive photoelectrochemical electrodes

1990-01-01

283

Rotational bands in {sup 167}Hf  

Energy Technology Data Exchange (ETDEWEB)

High-spin states in {sup 167}Hf, populated in the {sup 141}Pr({sup 30}Si,p3n){sup 167}Hf reaction, have been studied using the NORDBALL Ge detector array. Three rotational cascades have been observed for the first time and the previously-known level scheme has been extended to significantly higher spin. Band-crossing effects are discussed within the framework of Woods-Saxon cranking calculations and are found to be in good agreement. (orig.) With 4 figs., 2 tabs., 23 refs.

Smith, M.B.; Campbell, G.J.; Chapman, R.; Middleton, D.J.; Spohr, K.M. [Paisley Univ. (United Kingdom). Dept. of Electronic Eng. and Phys.; Tjoem, P.O. [Department of Physics, University of Oslo, N-0316 Oslo (Norway); Bark, R.A.; Ryde, H. [Department of Physics, University of Lund, S-223 62 Lund (Sweden); Hagemann, G.B. [Niels Bohr Institute, University of Copenhagen (Denmark); Keeley, N. [Schuster Laboratory, University of Manchester, Manchester M13 9PL (United Kingdom)

1999-09-01

284

Rotational bands in [sup 167]Hf  

Energy Technology Data Exchange (ETDEWEB)

High-spin states in [sup 167]Hf, populated in the [sup 141]Pr([sup 30]Si,p3n)[sup 167]Hf reaction, have been studied using the NORDBALL Ge detector array. Three rotational cascades have been observed for the first time and the previously-known level scheme has been extended to significantly higher spin. Band-crossing effects are discussed within the framework of Woods-Saxon cranking calculations and are found to be in good agreement. (orig.) With 4 figs., 2 tabs., 23 refs.

Smith, M.B.; Campbell, G.J.; Chapman, R.; Middleton, D.J.; Spohr, K.M. (Paisley Univ. (United Kingdom). Dept. of Electronic Eng. and Phys.); Tjoem, P.O. (Department of Physics, University of Oslo, N-0316 Oslo (Norway)); Bark, R.A.; Ryde, H. (Department of Physics, University of Lund, S-223 62 Lund (Sweden)); Hagemann, G.B. (Niels Bohr Institute, University of Copenhagen (Denmark)); Keeley, N. (Schuster Laboratory, University of Manchester, Manchester M13 9PL (United Kingdom))

1999-09-01

285

Single Band Helical Antenna in Axial Mode  

Directory of Open Access Journals (Sweden)

Full Text Available Helical antennas have been widely used in a various useful applications, due to their low weight and low profile conformability, easy and cheap realization.Radiation properties of this antenna are examined both theoretically and experimentally. In this paper, an attempt has been made to investigate new helical antenna structure for Applications. CST MWS Software is used for the simulation and design calculations of the helical antennas. The axial ratio, return loss, VSWR, Directivity, gain, radiation pattern is evaluated. Using CST MWS simulation software proposed antenna is designed/simulated and optimized. The antenna exhibits a single band from 0 GHz to 3 GHz for GPS and several satellite applications

Parminder Singh; Manju; Manpreet Kaur; Manpreet Kaur

2012-01-01

286

Rotational and vibrational bands in 108Pd  

Scientific Electronic Library Online (English)

Full Text Available Abstract in english The 108Pd nucleus has been studied with the 100Mo(11B, p2ngamma) reaction at 43 MeV incident energy. gamma -gamma - t, gamma -gamma - charged particle coincidences and directional correlation ratios were measured using the gamma spectrometer formed by four Compton suppressed HPGe detectors and a 4pi charged-particle ancillary detector system. The struture of the bands was interpreted within the framework of the cranked shell model and total Routhian calculations.

Alcántara-Núñez, J.A.; Oliveira, J.R.B.; Cybulska, E.W.; Medina, N.H.; Rao, M.N.; Ribas, R.V.; Rizzutto, M.A.; Seale, W.A.; Falla-Sotelo, F.

2004-09-01

287

Paleomagnetic dating of liesegang bands  

Energy Technology Data Exchange (ETDEWEB)

Paleomagnetic analysis, in conjunction with petrographic studies, was used to date the formation of hematite liesegang bands in the Ordovician Upper Arbuckle Group in southern Oklahoma. The hematite bands form symmetrical patterns on both sides of calcite-filled fractures in dolomite beds. The bands decrease in abundance and become more diffuse away from the fractures. Dedolomite is common near the fractures. Samples from distinctly banded dolomite near the fractures contain a relatively strong chemical remanent magnetization (CRM) with a southeasterly declination and shallow inclination. Samples farther from the fractures that are less distinctly banded or have no bands contain a weaker and less table CRM. Petrographic evidence and stable demagnetization to 600/sup 0/C indicate that the CRM resides in hematite. Samples were collected from both flanks of the Arbuckle Anticline (late Pennsylvanian folding), and a fold test demonstrates that the CRM is post-folding. The pole position for the CRM corresponds to the Early Permian (approx. 280 Ma) part of the Apparent Polar Wander Path for stable North America. These results suggest that the liesegang bands formed in the Early Permian, probably by rhythmic precipitation of hematite from fluids that moved out from the fractures. The fluids also apparently caused dedolomitization and precipitation of calcite in intercrystalline pore spaces. These fluids were probably the source of iron for the bands, although iron released from dedolimitization of ferroan dolomite may have been a local source.

Cochran, K.A.; Elmore, R.

1985-01-01

288

Band crossings in 86Zr  

International Nuclear Information System (INIS)

The level scheme of 86Zr has been investigated experimentally and theoretically. Band crossings due to g/sub 9/2/ protons and neutrons as well as the second backbend in the yrast line have been observed. The triaxial cranked shell model has been applied in order to study the quasiparticle content of different bands and to determine the underlying nuclear shape

1983-01-01

289

Rotational bands of 159Dy  

Science.gov (United States)

High-spin states of 159Dy have been studied by using reaction 150Nd(13C,4n). Two rotational bands based on the configurations /?[521]3/2 and /?[642]5/2 have been extended to 57/2- and 61/2+ states, respectively. A neutron AB crossing has been observed around /??=0.26 MeV in the /?[521]3/2 band. It has been observed that the signature splitting is inverted after the band crossing in the /?[521]3/2 band. The first band crossing has been observed around /??=0.38 MeV in the /?[642]5/2 band. Seven E1 transitions from the /?[521]3/2 band to the /?[642]5/2 band have been observed and discussed on the base of Generalized Intensity Relation. It is found that the /B(E1)/B(E2) ratios for 47/2- and 43/2- states become enhanced relatively to those for the lower-spin states.

Sugawara, M.; Mitarai, S.; Kusakari, H.; Oshima, M.; Hayakawa, T.; Toh, Y.; Hatsukawa, Y.; Katakura, J.; Iimura, H.; Zhang, Y. H.; Sugie, M.; Sato, Y.

2002-03-01

290

Rotational bands of 159Dy  

International Nuclear Information System (INIS)

[en] High-spin states of 159Dy have been studied by using reaction 150Nd(13C, 4n). Two rotational bands based on the configurations ?[521]3/2 and ?[642]5/2 have been extended to 57/2- and 61/2+ states, respectively. A neutron AB crossing has been observed around ??=0.26 MeV in the ?[521]3/2 band. It has been observed that the signature splitting is inverted after the band crossing in the ?[521]3/2 band. The first band crossing has been observed around ??=0.38 MeV in the ?[642]5/2 band. Seven E1 transitions from the ?[521]3/2 band to the ?[642]5/2 band have been observed and discussed on the base of Generalized Intensity Relation. It is found that the B(E1)/B(E2) ratios for 47/2- and 43/2- states become enhanced relatively to those for the lower-spin states

2002-03-11

291

Characterization of band structure for transverse acoustic phonons in Fibonacci superlattices by a bandedge formalism  

International Nuclear Information System (INIS)

We present a divergence-free method to determine the characteristics of band structures and projected band structures of transverse acoustic phonons in Fibonacci superlattices. A set of bandedge equations is formulated to solve the band structures for the phonon instead of using the traditional dispersion relation. Numerical calculations show band structures calculated by the present method for the Fibonacci superlattice without numerical instability, which may occur in traditional methods. Based on the present formalism, the band structure for the acoustic phonons has been characterized by closure points and the projected bandgaps of the forbidden bands. The projected bandgaps are determined by the projected band structure, which is characterized by the cross points of the projected bandedges. We observed that the band structure and projected band structure and their characteristics were quite different for different generation orders and the basic layers for the Fibonacci superlattice. In this study, concise rules to determine these characteristics of the band structure and the projected band structure, including the number and the location of closure points of forbidden bands and those of projected bandgaps, in Fibonacci superlattices with arbitrary generation order and basic layers are proposed.

2008-11-05

292

Diffusion Quantum Monte Carlo Calculations of Excited States of Silicon  

CERN Multimedia

The band structure of silicon is calculated at the Gamma, X, and L wave vectors using diffusion quantum Monte Carlo methods. Excited states are formed by promoting an electron from the valence band into the conduction band. We obtain good agreement with experiment for states around the gap region and demonstrate that the method works equally well for direct and indirect excitations, and that one can calculate many excited states at each wave vector. This work establishes the fixed-node DMC approach as an accurate method for calculating the energies of low lying excitations in solids.

Williamson, A J; Needs, R J; Rajagopal, G; Hood, Randolph Q.

1998-01-01

293

Superdeformed band in 130Ce  

International Nuclear Information System (INIS)

An open-quotes identicalclose quotes superdeformed (SD) band has been discovered in the nucleus 130Ce. This band has transition energies which are identical to the half-way points between the energies in the yrast SD band of 131Ce to a mean degeneracy of 0.4%. The discovery of this band completes the chain of SD Ce isotopes from 129Ce to 133Ce. However, at 0.5% of the reaction channel, it is populated with an intensity which is an order of magnitude smaller than neighboring SD bands. The valence neutron configuration is assigned as ?61 with a hole in either the [523]7/2- or [411]1/2+ Nilsson orbitals. copyright 1996 The American Physical Society.

294

Band anticrossing in dilute nitrides  

Energy Technology Data Exchange (ETDEWEB)

Alloying III-V compounds with small amounts of nitrogen leads to dramatic reduction of the fundamental band-gap energy in the resulting dilute nitride alloys. The effect originates from an anti-crossing interaction between the extended conduction-band states and localized N states. The interaction splits the conduction band into two nonparabolic subbands. The downward shift of the lower conduction subband edge is responsible for the N-induced reduction of the fundamental band-gap energy. The changes in the conduction band structure result in significant increase in electron effective mass and decrease in the electron mobility, and lead to a large enhance of the maximum doping level in GaInNAs doped with group VI donors. In addition, a striking asymmetry in the electrical activation of group IV and group VI donors can be attributed to mutual passivation process through formation of the nearest neighbor group-IV donor nitrogen pairs.

Shan, W.; Yu, K.M.; Walukiewicz, W.; Wu, J.; Ager III, J.W.; Haller, E.E.

2003-12-23

295

Plasmon dispersion and quasiparticle band structures for noble metals  

International Nuclear Information System (INIS)

Full text: In density-functional theory the Kohn-Sham eigenvalues cannot be interpreted as excitation energies, but band structures are often qualitatively correct and can be used as a starting point for perturbation-theoretical treatments. The GW approximation for the electronic self-energy is a particularly successful method for accurate quantitative band-structure calculations. The screened interaction W incorporates local field effects from the inversion of the dielectric matrix determined in the Random Phase Approximation. The inverted dielectric matrix combined with non-local empirical pseudopotentials also yields adequately calculated low energy excited state properties of materials. Dielectric calculations based on the pseudo-wavefunctions and energy band structure within a plasmon picture determine mean free path lengths and Fourier components of the inelastic scattering potential. Efficient band structures simulate ballistic transport effects in copper and surface state changes with strain during silver epitaxial film growth on silicon, but care must be taken with convergence, in order to obtain good agreement with first principle calculations and experimental values. Comparisons are made with recent LDA and GW calculations for silver

2002-01-01

296

Franck–Condon factors and observed band strength distribution in the vibrational structure of the Ag2 D-X band system  

Directory of Open Access Journals (Sweden)

Full Text Available TPotential curves for the X1Sg+ and D1Su+ states of three diatomic silver isotopomers, 107Ag2, 107Ag109Ag and 109Ag2, were determined from the best available molecular constants by the Rydberg–Klein–Rees method. From these potentials, Franck–Condon factors and band-origin wavenumbers were computed, and the reliability of the obtained values was verified by comparison with the observed band strength distribution and the measured band origin po¬sitions in a previously recorded D-X spectrum. The ratios of the Franck–Con¬don factors to those of corresponding isotopic bands were found to be very close to unity, revealing only a very small isotopic effect on the Franck–Condon factors of Ag2 D-X bands. The isotopic shifts of the calculated band origins agree well with previously measured displacements of band heads.

ANKICA ANTI?-JOVANOVI?; MILOŠ MOM?ILOVI?; VOJISLAV BOJOVI?; MURTADHA A. KHAKOO; RUSS R. LAHER

2010-01-01

297

Superdeformed bands of odd nuclei in A=190 region in the quasiparticle picture  

Energy Technology Data Exchange (ETDEWEB)

Properties of the superdeformed (SD) bands of {sup 195}Pb and {sup 193}Hg have been studied by the cranked Hartree-Fock-Bogoliubov method. The calculations reproduce the flat behavior of the dynamical moment of inertia of two of the SD bands of {sup 195}Pb measured recently. Possible configuration assignments for the observed bands 3 and 4 of {sup 195}Pb are discussed. The two interacting SD bands of {sup 193}Hg have also been calculated. The analysis confirms the superiority of a density-dependent pairing force over a seniority pairing interaction. (author). 25 refs.

Terasaki, J.; Flocard, H. [Paris-11 Univ., 91 - Orsay (France). Inst. de Physique Nucleaire; Heenen, P.H. [Brussels Univ. (Belgium). Service de Physique Nucleare Therorique; Bonche, P. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Service de Physique Theorique

1996-07-01

298

Photonic band gap structures for accelerator applications  

International Nuclear Information System (INIS)

We report the results of our theoretical investigation and cold test of a two-dimensional (2D) metal photonic band gap (PBG) accelerator cell and propose to construct a 2?/3 linear accelerator structure with reduced wakefields as a stack of PBG cells set between disks with irises. We developed a computer code, called Photonic Band Gap Structure Simulator (PBGSS), to calculate the complete dispersion curves for square and triangular arrays of metal rods. Using the PBGSS code, the global photonic band gaps of the arrays were determined and employed to design the PBG cavities. The modes of the 2D PBG cavity formed by a defect (missing rod) in the triangular array of metal rods were studied numerically using the HFSS code. The cavity was designed with only the fundamental TM01 mode confined and higher order modes suppressed. The cold test was performed and the results proved the suppression of the wakefields. Dielectric PBG structures were also studied as applied to microwave devices. A dielectric PBG resonator with the TM02 mode confined and TM01 and TM11 modes absent was designed. The construction of such a resonator overcomes the problem of mode competition in overmoded structures and thus will allow the extension of the operating frequency of the devices to higher frequencies at higher order modes.

2002-12-12

299

Population of rotational bands in superheavy nuclei  

Directory of Open Access Journals (Sweden)

Full Text Available Using the statistical approach, we study the population of ground-state rotational bands of superheavy nuclei produced in the fusion-evaporation reactions 208Pb(48Ca, 2n)254No, 206Pb(48Ca, 2n)252No, and 204Hg(48Ca, 2n)250Fm. We calculate relative intensities of E2-transitions between the rotational states and entry spin distributions of the residual nuclei, evaporation residue cross sections, and excitation functions for these reactions. Fermi-gas model is used for the calculation of level density, and damping of shell effects both with excitation energy and angular momentum is taking into account. The results are in a good agreement with the experiment data.

Zubov A.S.; Sargsyan V.V.; Adamian G.G.; Antonenko N.V.

2012-01-01

300

Electronic structure of periodic curved surfaces -- topological band structure  

CERN Multimedia

Electronic band structure for electrons bound on periodic minimal surfaces is differential-geometrically formulated and numerically calculated. We focus on minimal surfaces because they are not only mathematically elegant (with the surface characterized completely in terms of "navels") but represent the topology of real systems such as zeolites and negative-curvature fullerene. The band structure turns out to be primarily determined by the topology of the surface, i.e., how the wavefunction interferes on a multiply-connected surface, so that the bands are little affected by the way in which we confine the electrons on the surface (thin-slab limit or zero thickness from the outset). Another curiosity is that different minimal surfaces connected by the Bonnet transformation (such as Schwarz's P- and D-surfaces) possess one-to-one correspondence in their band energies at Brillouin zone boundaries.

Aoki, H; Takeda, D; Morise, H

2001-01-01

 
 
 
 
301

Electromagnetic properties of pseudo-Nilsson bands in 185Os  

International Nuclear Information System (INIS)

[en] New data have been obtained for 185Os following the 176Yb(13C,4n)185Os reaction, extending the pseudo-Nilsson 1-/2, 3-/2 [411] doublet structure and the 7-/2 [404] band to significantly higher spins. Gamma-ray branching ratio data have been analysed to obtain extensive B(M1) and B(E2) ratios for intraband and interband transitions. The data are compared with particle-rotor calculations based on the pseudo-Nilsson potential and the Woods-Saxon potential. The results indicate that the pseudo-Nilsson approximation provides a good description of the 1-/2, 3-/2 [411] bands up to the first band crossing;the difference in magnitude between the model predictions and data for the 7-/2 [404] band may be attributed to a lower deformation for the higher-K structure. (orig.)

2004-01-01

302

Shape coexistence and band crossings in 174Pt  

International Nuclear Information System (INIS)

High-spin states in 174Pt were populated via the 92Mo(84Sr,2p) and 92Mo(84Sr,2p2n) reactions. The ground-state band has been extended from I=14 to 24 (tentatively 26) and a new side band is observed up to a spin of 21 (tentatively 23). A low-frequency crossing is observed in the latter band at a rotational frequency that is similar to that seen in the ground-state band. The first and second i13/2 neutron alignments are also observed in 174Pt. Surprisingly, these crossings occur at approximately the same frequency. Total Routhian surface and cranked shell model calculations are used in an attempt to understand this behavior

2004-01-01

303

Analysis of Factors Affecting Log Band Saw Capacity  

Directory of Open Access Journals (Sweden)

Full Text Available The goal of this research was to measure the capacity of the log band saw by monitoring the sawing process per operation for each log and to determine what the influencing factors were and their effect on the technological capacity of the log band saw, based on recorded and processed data. The analysis of the recorded data shows that the processed log volume, whose increase also increases the saw capacity, has the most important effect on log band saw capacity. It is imperative to take into account the volume of logs being processed when calculating the capacity of the log band saw. When monitoring the work of the operator, the use of fixed norms is not recommended and it is imperative that norms are connected to the volume of logs being processed.

Josip Ištvani?; Ružica Beljo Lu?i?; Matija Jug; Rajka Karan

2009-01-01

304

The effect of the band edges on the Seebeck coefficient.  

UK PubMed Central (United Kingdom)

The classical thermopower formulae generally applied for the calculation of the Seebeck coefficient S are argued to be incomplete. S can be separated into two different contributions, a scattering term, S(0), and a thermodynamic term, ?S, representing the additional change of the electrochemical potential ? with temperature T caused by 'non-scattering' effects, for instance, the band edge shift with T. On the basis of this separation into S(0) and ?S, it is shown that shifts of the band edges with T lead to an additional contribution to the classical thermopower formulae. This separation provides the basis for an interpretation of positive thermopowers measured for many metals. Positive thermopower is expected if the energy of the conduction band edge increases with T and if this effect overcompensates for the influence of the energy dependent conductivity, ?(E). Using experimental thermopower data, the band edge shifts are determined for a series of liquid normal metals.

Sonntag J

2010-06-01

305

Large magnon band gaps created by introducing additional lattice scatterers  

Science.gov (United States)

Magnon band gaps (MBGs) in 2D square and honeycomb lattices of circular cross-section rods can be increased by introducing a smaller diameter rod into the center of each lattice unit cell. The additional lattice scatterers reduce the structure symmetry to create significantly larger band gaps for original lattice. Magnon band structures are numerically calculated using the plane-wave method. The results show that the normalized width of band gaps in square-hybrid-rods and honeycomb-hybrid-rods structure are 167% and 285% sizes of those in the corresponding square-single-rods and honeycomb-single-rods structure. Crystal symmetry reduction by introducing additional scatterers opens up a new way for engineering MBGs of 2D magnonic crystals.

Wang, Qi; Zhong, Zhiyong; Jin, Lichuan; Tang, Xiaoli; Bai, Feimin; Zhang, Huaiwu

2013-04-01

306

Theoretical approach to heterogeneous catalysis using large finite crystals  

Energy Technology Data Exchange (ETDEWEB)

A theoretical-approach is described for heterogeneous catalysis using large finite crystals and an exactly soluble model. First, reviews of some themes which are well-known to physicists but need a translation into chemical language: wave vectors, the tight-binding model, and energy bands. Next a description of the finite simple cubic crystal and its analytical wave functions and energies in the Hueckel scheme is given. Also the analytical Hueckel wave functions for a finite face-centered cubic (FCC) crystal cut along square, (100)-type faces is described. Then the calculation of the perturbation interaction energy between H/sub 2/ and large finite (simple cubic or FCC) crystals of Ni atoms, having up to 13,824 atoms is described. The interaction energy is shown to be independent of crystal size, whatever the position of attack of the H/sub 2/ molecule. 28 references, 9 figures, 8 tables.

Salem, L.

1985-12-19

307

Performance Analysis of IIR Digital Band Stop Filter  

Directory of Open Access Journals (Sweden)

Full Text Available IIR Band-stop filter is recursive in nature i.e. the present output sample depends on the past input sample, past output samples and the present input samples. If the past and present inputs and output are varied the resulting present output will be changed. The Band-stop filter rejects one band of frequency and allows all other frequency band to pass. In this paper, the performance analysis of Band-stop filter is done using the Modified Analog-to-Digital Mapping technique and simulated in Matlab7. The response of the filter can be modified by changing the value of the components. The coefficients that are essentially required to design a IIR Digital Band-stop filter, are also calculated using the above mentioned algorithm and finally the magnitude response and the stability of the filter are determined using Matlab7 with satisfying results. The pole-zero plot of a system, filter in this case, determines the stability of the predesigned IIR Band-stop filter.

Subhadeep Chakraborty, Abhirup Patra

2013-01-01

308

Valence band structure of Bi2Se3  

Science.gov (United States)

Bi2Se3 is an interesting candidate for thermoelectric application because Se is a more abundant element than Te, which is commercially used in Bi2Te3-based Peltier coolers. However, intrinsic Se vacancies dominate in Bi2Se3 and dope the material n-type. Due to unfavourable conduction band structure, n-type Bi2Se3 does not have a high power factor. Recently, it has been calculated [1] that Bi2Se3 has a favourable valence band structure for thermoelectric application. In this presentation, high-quality p-type Bi2Se3 single crystals are prepared and Shubnikov de Haas measurement are carried out on them to characterize the band structure. Cross-sectional areas of Fermi surface are mapped out and compared with the theoretical calculation. Reference: [1] Phys. Rev. X 1, 021005 (2011)

Gao, Yi-Bin; Parker, David; Heremans, Joseph P.

2013-03-01

309

Band-edge diagrams for strained III-V semiconductor quantum wells, wires, and dots  

CERN Document Server

We have calculated band-edge energies for most combinations of zincblende AlN, GaN, InN, GaP, GaAs, InP, InAs, GaSb and InSb in which one material is strained to the other. Calculations were done for three different geometries, quantum wells, wires, and dots, and mean effective masses were computed in order to estimate confinement energies. For quantum wells, we have also calculated band-edges for ternary alloys. Energy gaps, including confinement, may be easily and accurately estimated using band energies and a simple effective mass approximation, yielding excellent agreement with experimental results. By calculating all material combinations we have identified novel and interesting material combinations, such as artificial donors, that have not been experimentally realized. The calculations were perfomed using strain-dependent k-dot-p theory and provide a comprehensive overview of band structures for strained heterostructures.

Pryor, C E

2005-01-01

310

Calculating reference intervals for laboratory measurements.  

UK PubMed Central (United Kingdom)

Reference intervals are used in laboratory medicine to detect measurements which are extreme, possibly abnormal. Methods of estimating reference intervals and age-specific reference intervals (where the measurement is dependent on a covariate, typically age) are reviewed. The issues of calculating confidence bands, determining appropriate sample sizes and assessing goodness-of-fit are discussed.

Wright EM; Royston P

1999-06-01

311

MAGNETIC BAND STRUCTURE OF CrO2  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Spin-resolved photoemission of polycrystalline CrO2 films shows 3d states with a nearly + 100 % spin polarization about 2 eV below the Fermi level (EF). Extremely low intensity is observed near EF. Our findings are in contrast to recent band structure calculations, predicting CrO2 to be a half-metal...

Kämper, K.; Schmitt, W.; Güntherodt, G.; Gambino, R.; Ruf, R.

312

Confidence Bands for ROC Curves.  

Science.gov (United States)

We address the problem of comparing the performance of classifiers. In this paper we study techniques for generating and evaluating confidence bands on ROC curves. Historically this has been done using one-dimensional confidence intervals by freezing one ...

S. A. Macskassy F. J. Provost M. L. Littman

2003-01-01

313

Shear banding in polymer solutions  

Science.gov (United States)

The current theoretical belief is that the steady-state shear banding in viscoelastic liquids requires a non-monotonic constitutive relationship between shear stress and shear rate. Although existing rheological studies conclude that the constitutive equation for entangled polymers is monotonic, recent experimental evidence suggests shear banding can nevertheless occur in polymer solutions. In this work, we predict, for the first time, steady state shear banding with a realistic monotonic constitutive theory for polymeric liquids. The key is that a proper account must be taken of the coupling of polymer stress to polymer concentration. We also predict multiple steady states at some shear rates as seen experimentally, with shear banding if the flow is ramped quickly enough from rest, but homogeneous linear shear flow otherwise.

Cromer, Michael; Villet, Michael C.; Fredrickson, Glenn H.; Leal, L. Gary

2013-05-01

314

Fitting the observed PAH bands  

Science.gov (United States)

The interstellar infrared emission spectrum with strong bands near 3.3, 6.2, 7.7, and 11.2 micron is common throughout the Universe. These bands -- often called the Unidentified InfraRed (UIR) bands or Aromatic InfraRed Bands (AIB) -- dominate the mid-IR spectra of most galactic objects and they have been detected in a large number of extragalactic objects. Not only are these features observed in many different objects, there is also significant variability in the spectroscopic details from one object to another and from one region to another within extended sources. Clearly, these spectra contain a wealth of information which reflects the physical conditions in the emission zones and composition of the emitting materials. Many studies have therefore attempted to use these easily observed features as diagnostic tools for various purposes. It is now widely accepted that this spectrum is produced by fluorescent emission from highly vibrationally excited polycyclic aromatic hydrocarbon molecules (PAHs) and closely related species and the features are now often referred to as the PAH emission bands. In this presentation, we use the NASA Ames PAH IR Spectroscopic Database and a simplified model for PAH physics to present a detailed comparison with observations of the UIR bands representing the different characteristic classes of UIR spectra. We find that we can closely reproduce the observed UIR spectra for all classes in the ranges 6--9 micron and 10--14 micron, offering credibility for the hypothesis that the UIR bands are indeed due to the various vibrational modes of PAHs and related species. We will also show how the spectral variations of the PAH bands in different environments can be explained by differences in the size distribution, the charge state and the precise chemical composition of the contributing molecules.

Cami, Jan; Bauschlicher, C.; Peeters, E.; Mattioda, A.; Allamandola, L.

2009-01-01

315

The 3 micron ice band  

International Nuclear Information System (INIS)

[en] Ever since it was proposed that H2O could be a dominant constituent of interstellar grains, its detection, or lack thereof, has played a large role in theories of grains and their evolution. It now appears possible to provide a basic theoretical structure for the evolution of grains in molecular clouds based on current observational evidence and laboratory experiments on the ice band. Both band strengths and shapes can be reasonably predicted by grain models. (U.K.)

1984-01-01

316

Narrow-Band Microwave Filters  

Directory of Open Access Journals (Sweden)

Full Text Available Original design of the narrow-band compact filters based on the high-quality waveguide-dielectric resonator with anisotropic materials has been presented in this work. Designed filters satisfy the contradictory requirements: they provide the narrow frequency band (0.05 ÷ 0.1 % of the main frequency f0) and the low initial losses ?0 ? 1 dB).

A.V. Strizhachenko; A.A. Zvyagintsev; S.N. Shul’ga; V.V. Chizhov

2010-01-01

317

Electronic band structure and optical properties of the cubic, Sc, Y and La hydride systems  

International Nuclear Information System (INIS)

Electronic band structure calculations are used to interpret the optical spectra of the cubic Sc, Y and La hydride systems. Self-consistent band calculations of ScH2 and YH2 were carried out. The respective joint densities of states are computed and compared to the dielectric functions determined from the optical measurements. Additional calculations were performed in which the Fermi level or band gap energies are rigidly shifted by a small energy increment. These calculations are then used to simulate the derivative structure in thermomodulation spectra and relate the origin of experimental interband features to the calculated energy bands. While good systematic agreement is obtained for several spectral features, the origin of low-energy interband transitions in YH2 cannot be explained by these calculated bands. A lattice-size-dependent premature occupation of octahedral sites by hydrogen atoms in the fcc metal lattice is suggested to account for this discrepancy. Various non-self-consistent calculations are used to examine the effect of such a premature occupation. Measurements of the optical absorptivity of LaH/sub x/ with 1.6 2 lattice. These experimental results also suggest that, in contrast to recent calculations, LaH3 is a small-band-gap semiconductor.

1980-01-01

318

Electronic band structure and optical properties of the cubic, Sc, Y and La hydride systems  

Energy Technology Data Exchange (ETDEWEB)

Electronic band structure calculations are used to interpret the optical spectra of the cubic Sc, Y and La hydride systems. Self-consistent band calculations of ScH/sub 2/ and YH/sub 2/ were carried out. The respective joint densities of states are computed and compared to the dielectric functions determined from the optical measurements. Additional calculations were performed in which the Fermi level or band gap energies are rigidly shifted by a small energy increment. These calculations are then used to simulate the derivative structure in thermomodulation spectra and relate the origin of experimental interband features to the calculated energy bands. While good systematic agreement is obtained for several spectral features, the origin of low-energy interband transitions in YH/sub 2/ cannot be explained by these calculated bands. A lattice-size-dependent premature occupation of octahedral sites by hydrogen atoms in the fcc metal lattice is suggested to account for this discrepancy. Various non-self-consistent calculations are used to examine the effect of such a premature occupation. Measurements of the optical absorptivity of LaH/sub x/ with 1.6 < x < 2.9 are presented which, as expected, indicate a more premature occupation of the octahedral sites in the larger LaH/sub 2/ lattice. These experimental results also suggest that, in contrast to recent calculations, LaH/sub 3/ is a small-band-gap semiconductor.

Peterman, D.J.

1980-01-01

319

Dilatational band formation in bone.  

UK PubMed Central (United Kingdom)

Toughening in hierarchically structured materials like bone arises from the arrangement of constituent material elements and their interactions. Unlike microcracking, which entails micrometer-level separation, there is no known evidence of fracture at the level of bone's nanostructure. Here, we show that the initiation of fracture occurs in bone at the nanometer scale by dilatational bands. Through fatigue and indentation tests and laser confocal, scanning electron, and atomic force microscopies on human and bovine bone specimens, we established that dilatational bands of the order of 100 nm form as ellipsoidal voids in between fused mineral aggregates and two adjacent proteins, osteocalcin (OC) and osteopontin (OPN). Laser microdissection and ELISA of bone microdamage support our claim that OC and OPN colocalize with dilatational bands. Fracture tests on bones from OC and/or OPN knockout mice (OC(-/-), OPN(-/-), OC-OPN(-/-;-/-)) confirm that these two proteins regulate dilatational band formation and bone matrix toughness. On the basis of these observations, we propose molecular deformation and fracture mechanics models, illustrating the role of OC and OPN in dilatational band formation, and predict that the nanometer scale of tissue organization, associated with dilatational bands, affects fracture at higher scales and determines fracture toughness of bone.

Poundarik AA; Diab T; Sroga GE; Ural A; Boskey AL; Gundberg CM; Vashishth D

2012-11-01

320

Dilatational band formation in bone.  

Science.gov (United States)

Toughening in hierarchically structured materials like bone arises from the arrangement of constituent material elements and their interactions. Unlike microcracking, which entails micrometer-level separation, there is no known evidence of fracture at the level of bone's nanostructure. Here, we show that the initiation of fracture occurs in bone at the nanometer scale by dilatational bands. Through fatigue and indentation tests and laser confocal, scanning electron, and atomic force microscopies on human and bovine bone specimens, we established that dilatational bands of the order of 100 nm form as ellipsoidal voids in between fused mineral aggregates and two adjacent proteins, osteocalcin (OC) and osteopontin (OPN). Laser microdissection and ELISA of bone microdamage support our claim that OC and OPN colocalize with dilatational bands. Fracture tests on bones from OC and/or OPN knockout mice (OC(-/-), OPN(-/-), OC-OPN(-/-;-/-)) confirm that these two proteins regulate dilatational band formation and bone matrix toughness. On the basis of these observations, we propose molecular deformation and fracture mechanics models, illustrating the role of OC and OPN in dilatational band formation, and predict that the nanometer scale of tissue organization, associated with dilatational bands, affects fracture at higher scales and determines fracture toughness of bone. PMID:23129653

Poundarik, Atharva A; Diab, Tamim; Sroga, Grazyna E; Ural, Ani; Boskey, Adele L; Gundberg, Caren M; Vashishth, Deepak

2012-11-05

 
 
 
 
321

Terminating Bands in ^86Zr  

Science.gov (United States)

High angular momentum states in ^86Zr were populated through the ^58Ni(^32S,4p) reaction at 135 MeV using the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory. Recoiling ^86Zr nuclei were stopped in a thick Ta backing. Prompt multi-? coincidences with evaporated charged particles were detected using the full array of uc(Gammasphere) and the uc(Microball.) Mean lifetimes of 36 levels in ^86Zr were measured using the Doppler-shift attenuation method. Transition quadrupole moments Qt were found in the range of about 0.3 to 1.5 eb in the positive-parity bands, corresponding to a quadrupole deformation ?2 from 0.04 to 0.17 in an axial rotational model. The negative-parity bands show Qt values from about 0.25 to 1.20 eb corresponding to ?2 between 0.03 and 0.13. In the yrast positive-parity band sharp drops in collectivity approaching the 24^+ and 30^+ states support the interpretation of band termination in these configurations. A drop in Qt in the negative-parity band towards the 27^- state may indicate another terminating band.

Wiedeking, M.; Tabor, S. L.; Cristancho, F.; Devlin, M.; Döring, J.; Jackson, C. B.; Johns, G. D.; Kaye, R. A.; Lee, I. Y.; Lerma, F.; Macchiavelli, A. O.; Naidu, M.; Ragnarsson, I.; Sarantites, D. G.; Solomon, G. Z.

2002-10-01

322

Rotational bands in 169Re  

Science.gov (United States)

High-spin states in 169Re have been investigated by means of in-beam ?-ray spectroscopy techniques with the 144Sm(28Si, 1p2n?)169Re reaction. X-? and ?-?-t coincidences, ?-ray anisotropies, and DCO ratios were measured. A strongly coupled band based on the 9/2-[514] Nilsson state and a decoupled band built on the h9/2 intruder proton orbital (nominally 1/2-[541]) have been established. The AB neutron crossings are observed at ?? = 0.23 and 0.27 MeV for the 9/2-[514] and 1/2-[541] bands, respectively. The 9/2-[514] band in 169Re shows the largest signature splitting at low spin among the odd-mass Re isotopes. Band properties of the AB neutron crossing frequencies, alignment gains, and signature splittings are discussed, and compared with those in the heavier odd-A Re isotopes. Additionally, a three-quasipariticle band is observed, and the ?9/2 -[514] ? ?AE configuration is proposed tentatively.

Zhou, X. H.; Oshima, M.; Toh, Y.; Zhang, Y. H.; Zheng, Y.; Koizumi, M.; Osa, A.; Hayakawa, T.; Hatsukawa, Y.; Shizuma, T.; Sugawara, M.

323

Rotational bands in 169Re  

International Nuclear Information System (INIS)

[en] High-spin states in 169Re have been investigated by means of in-beam ?-ray spectroscopy techniques with the 144Sm(28Si,1p2n?)169Re reaction. X-? and ?-?-t coincidences, ?-ray anisotropies, and DCO ratios were measured. A strongly coupled band based on the 9/2-[514] Nilsson state and a decoupled band built on the h9/2 intruder proton orbital (nominally 1/2-[541]) have been established. The AB neutron crossings are observed at ?? = 0.23 and 0.27 MeV for the 9/2-[514] and 1/2-[541] bands, respectively. The 9/2-[514] band in 169Re shows the largest signature splitting at low spin among the odd-mass Re isotopes. Band properties of the AB neutron crossing frequencies, alignment gains, and signature splittings are discussed, and compared with those in the heavier odd-A Re isotopes. Additionally, a three-quasipariticle band is observed, and the ?9/2-[514] x ?AE configuration is proposed tentatively. (orig.)

2002-01-01

324

Band crossing in isovalent semiconductor alloys with large size mismatch  

Science.gov (United States)

Mixing isovalent compounds AC with BC to form alloys A1-xBxC has been an effective way in band structure engineering to enhance the availability of material properties. In most cases, the mixed isovalent atoms A and B, such as Al and Ga in Al1-xGaxAs or As and Sb in GaAs1-xSbx are similar in their atomic sizes and chemical potentials; therefore, the physical properties of A1-xBxC change smoothly from AC to BC. However, in some cases when the chemical and size differences between the isovalent atoms A and B are large, adding a small amount of B to AC or vice versa can lead to a discontinuous change in the electronic band structure. These large size- and chemicalmismatched (LSCM) systems often show unusual and abrupt changes in the alloys' material properties, which provide great potential in material design for novel device applications. In this report, based on first-principles band-structure calculations we show that for LSCM GaAs1-xNx and GaAs1-xBix alloys at the impurity limit the N (Bi)-induced impurity level is above (below) the conduction-(valence-) band edge of GaAs. These trends reverse at high concentration, i.e., the conduction-band edge of GaAs1-xNx becomes an N-derived state and the valence-band edge of GaAs1-xBix becomes a Bi-derived state, as expected from their band characters. We show that this band crossing phenomenon cannot be described by the popular BAC model but can be naturally explained by a simple band broadening picture.

Deng, Hui-Xiong; Wei, Su-Huai

2012-02-01

325

Cancer Drug Development Calculators  

Science.gov (United States)

... Cancer Drug Approval Endpoints; Cancer Drug Development Calculators. -. Cancer Drug Development Calculators. Dose Calculator. ... More results from www.fda.gov/drugs/developmentapprovalprocess/developmentresources

326

Triaxial projected shell model study of gamma-vibrational bands in even-even Er isotopes  

CERN Multimedia

We expand the triaxial projected shell model basis to include triaxially-deformed multi-quasiparticle states. This allows us to study the yrast and gamma-vibrational bands up to high spins for both gamma-soft and well-deformed nuclei. As the first application, a systematic study of the high-spin states in Er-isotopes is performed. The calculated yrast and gamma-bands are compared with the known experimental data, and it is shown that the agreement between theory and experiment is quite satisfactory. The calculation leads to predictions for bands based on one- and two-gamma phonon where current data are still sparse. It is observed that gamma-bands for neutron-deficient isotopes of 156Er and 158Er are close to the yrast band, and further these bands are predicted to be nearly degenerate for high-spin states.

Sheikh-Javid, A; Sun, Y; Vakil, G B; Palit, R

2008-01-01

327

First-principles study of Cu2ZnSnS4 and the related band offsets for photovoltaic applications  

Science.gov (United States)

First-principles calculations of the band offsets between Cu2ZnSnS4 (CZTS) and XS (X = Cd, Zn) are performed. While the interface dipole contribution for the band offsets is calculated using the Perdew-Burke-Ernzerhof functional, the Heyd-Scuseria-Ernzerhof hybrid functional is employed to introduce the quasiparticle corrections to the band offsets. The calculated conduction band offset between CZTS and CdS is 0.2 eV, validating CdS for the buffer layer of the CZTS solar cell. The small conduction band offset stems from the band gap narrowing of CdS under the interface strain caused by the lattice misfit with CZTS. A large valence band offset over 0.9 eV between CZTS and ZnS indicates that precipitated ZnS is regarded as an inactive insulator phase in CZTS absorbers.

Nagoya, A.; Asahi, R.; Kresse, G.

2011-10-01

328

First-principles study of Cu2ZnSnS4 and the related band offsets for photovoltaic applications  

International Nuclear Information System (INIS)

[en] First-principles calculations of the band offsets between Cu2ZnSnS4 (CZTS) and XS (X = Cd, Zn) are performed. While the interface dipole contribution for the band offsets is calculated using the Perdew-Burke-Ernzerhof functional, the Heyd-Scuseria-Ernzerhof hybrid functional is employed to introduce the quasiparticle corrections to the band offsets. The calculated conduction band offset between CZTS and CdS is 0.2 eV, validating CdS for the buffer layer of the CZTS solar cell. The small conduction band offset stems from the band gap narrowing of CdS under the interface strain caused by the lattice misfit with CZTS. A large valence band offset over 0.9 eV between CZTS and ZnS indicates that precipitated ZnS is regarded as an inactive insulator phase in CZTS absorbers.

2011-10-12

329

Dosimetry of narrow band UVB treatments  

International Nuclear Information System (INIS)

Full text: For many years psoriasis has been treated with broad band UVB lamps. These lamps have a bell shaped spectrum which peaks at 305 nm and extends from 280 nm to 350 nm. However research with monochromatic UV radiation has shown that wavelengths between 300 nm and 320 nm are the most efficacious for clearing psoriasis while wavelengths below 305 nm are most effective for producing the undesirable side effect of erythema (sunburn). In response to these findings Philips developed a narrow band UVB tube in which a large fraction of the output was confined to a narrow peak (bandwidth 2.5 nm) situated at 311 nm. Christchurch Hospital replaced broad band UVB with narrow band treatments in August 1995 and as this required UV exposures to be substantially increased new protocols had to be developed. Three aspects needed to be addressed. These were translating the dose from broad band to narrow band for current patients, determining the initial dose for new patients and developing a formula for increasing subsequent exposures to both types of patient. To translate doses the spectral irradiance (?W/cm2/nm) that would fall on the patient was measured in both the old broad band and the new narrow band treatment units and from this UV doses were calculated. All doses were expressed in mJ/cm2 of unweighted UV over the range 250 nm to 400 nm. The erythemal effectiveness of the two units were compared by using the CIE 1987 curve to express doses in terms of the equivalent exposure of monochromatic 297 nm radiation. It was found that an exposure of 3.96 mJ/cm2 from the broad band FS40 tubes and 12.79 mJ/cm2 from the narrow band TL/01 tubes were both equivalent to 1.00 mJ/cm2 of monochromatic 297 nm radiation so when transferring patients all broad band doses needed to be increased by a factor of 3.2. Before transferring any patients this factor was confirmed by conducting two minimal erythema dose (MED) tests on a normal subject, one in each unit. For new patients a narrow band treatment schedule has been developed which is based on the patient' s MED. Before commencing treatments the patient is given an MED test using untanned skin on the inner surface of the forearm. The initial dose is 70% of the MED and each subsequent exposure is increased by a constant increment, namely 21.4% of the initial dose. This progression continues until the dose reaches three times the MED at which time it is held constant. Treatments are given twice per week up to a maximum of 30 treatments or until the psoriasis clears. If mild erythema occurs the next treatment is held at the previous dose while for more severe erythema it is missed entirely. This schedule is similar to the one in use at The Royal Victoria Infirmary, Newcastle upon Tyne, but with two minor exceptions. In Newcastle the increments are larger (on average 45% of the initial dose) but they only occur once a week. The transfer from broad band to narrow band was accomplished successfully without any incidence of erythema. After four months experience the 31 patients who were currently following the MED based protocol were reviewed. The lowest MED measured was 500 mJ/cm2 while the highest (three in number) exceeded 1110 mJ/cm2. Eleven of the patients exhibited erythema at some point in their treatment but it was only necessary to reduce the dose increment in one case. Of the remaining 20 patients, 13 who showed poor clearing of their psoriasis were placed on a dose schedules in which the dose increments were increased by between 20 % to 33%. In view of the fact almost equal numbers of patients received too large or too small a dose the schedule can be considered to be a good compromise

1996-01-01

330

Acoustic band gaps of the woodpile sonic crystal with the simple cubic lattice  

International Nuclear Information System (INIS)

This study theoretically and experimentally investigates the acoustic band gap of a three-dimensional woodpile sonic crystal. Such crystals are built by blocks or rods that are orthogonally stacked together. The adjacent layers are perpendicular to each other. The woodpile structure is embedded in air background. Their band structures and transmission spectra are calculated using the finite element method with a periodic boundary condition. The dependence of the band gap on the width of the stacked rods is discussed. The deaf bands in the band structure are observed by comparing with the calculated transmission spectra. The experimental transmission spectra for the ?-X and ?-X' directions are also presented. The calculated results are compared with the experimental results.

2011-02-02

331

Coupling of unpaired nucleons and collective band level structure in odd-odd nuclei  

International Nuclear Information System (INIS)

[en] The phenomenological approximation can be used for calculation energies of collective bands in odd-odd nuclei based on conflicting state of unpaired nucleons. The rule of decoupled particle as a spectator have been deduced. This mean that the energy spacing of collective bands in odd-odd nuclei are similar for energy spacing of collective bands based on state of coupled particle in adjacent odd nuclei. 44 refs.; 8 figs.; 2 tabs

1989-01-01

332

Rotational bands in deformed odd-A nuclei in the actinide region  

Energy Technology Data Exchange (ETDEWEB)

Tables of experimentally known energy levels of odd-A rotational bands in the actinide region (A {ge} 221) are presented along with the configuration assignments. This includes the newly defined quadrupole-octupole deformation region (A {le} 229). The moment of inertia and the decoupling parameters have been calculated for each band if sufficient data are available. Useful theoretical and experimental information for each band/nucleus is also given. The cutoff date for the present compilation is December 1990.

Jain, K.; Jain, A.K. (Univ. of Roorkee (India))

1992-03-01

333

New Band Structures in Neutron-Rich Mo and Ru Isotopes  

International Nuclear Information System (INIS)

Rotational bands in 110,112Ru and 108Mo have been investigated by means of ?-?-? and ?-?(?) coincidences of prompt ? rays emitted in the spontaneous fission of 252Cf. New ?I = 1 negative parity doublet bands are found. These bands in 110,112Ru and 108Mo have all the properties expected for chiral vibrations. Microscopic calculations that combine the TAC mean-field with random phase approximation support this interpretation. (author)

2009-01-01

334

Study of Band Structure of Two-Dimensional Anisotropic Honeycomb Photonic Crystals  

Science.gov (United States)

Using the plane wave expansion method, we have calculated, for both E and H polarizations, the band structure of 2D anisotropic photonic crystals with honeycomb lattice composed of anisotropic tellurium (Te) rods embedded in air background. The two rods in the unit cell are chosen square and circular in shape. Here, from a practical point of view, in order to obtain maximum band gaps, we have also studied the band structure as a function of size of rods.

Sedghi, A.; Soufiani, A. Rounaghi

2013-10-01

335

Fluctuations in a superconducting quantum critical point of multi-band metals  

CERN Multimedia

In multi-band metals quasi-particles arising from different atomic orbitals coexist at a common Fermi surface. Superconductivity in these materials may appear due to interactions within a band (intra-band) or among the distinct metallic bands (inter-band). Here we consider the suppression of superconductivity in the intra-band case due to hybridization. The fluctuations at the superconducting quantum critical point (SQCP) are obtained calculating the response of the system to a fictitious space and time dependent field, which couples to the superconducting order parameter. The appearance of superconductivity is related to the divergence of a generalized susceptibility. For a single band superconductor this coincides with the \\textit{Thouless criterion}. For fixed chemical potential and large hybridization, the superconducting state has many features in common with breached pair superconductivity with unpaired electrons at the Fermi surface. The T=0 phase transition from the superconductor to the normal state ...

Ramires, Aline

2011-01-01

336

Band theoretical study of the Fermi surface of CeB{sub 6}  

Energy Technology Data Exchange (ETDEWEB)

Fully relativistic band structure calculations have been performed for CeB{sub 6} and preliminary results are presented. The Fermi surface is obtained and the dHvA frequency of the {alpha} orbit is calculated. A good quantitative agreement with the experimental results suggests the importance of including both the spin-polarisation and spin-orbit coupling in the calculations. ((orig.)).

Suvasini, M.B. [Sheffield Univ. (United Kingdom). Dept. of Physics; Guo, G.Y. [Daresbury Laboratory, Warrington (United Kingdom); Temmerman, W.M. [Daresbury Laboratory, Warrington (United Kingdom); Gehring, G.A. [Sheffield Univ. (United Kingdom). Dept. of Physics

1995-02-01

337

THE FLUORESCENCE EFFICIENCIES OF THE CN VIOLET BANDS IN COMETS  

International Nuclear Information System (INIS)

We have carried out calculations of the fluorescent equilibrium of the CN molecule in the solar radiation field as a function of heliocentric radial velocity and distance. The detailed rotational line intensities of the CN violet 0-0 band have been recalculated for radial velocities between -60 and +60 km s-1 and at 10 distances in steps of ?2 from 0.25 to 5.7 AU. Comparisons with observed CN violet 0-0 band profiles yield reasonable agreement and remaining discrepancies are well understood. Based on the derived equilibrium rotational level populations of the ground state, 1-1 band rotational line intensities were also calculated. Total band fluorescence efficiencies for the violet ?? = 0 sequence are tabulated for the above range of distances and velocities, permitting the interpolation to any given comet's observational circumstances. These fluorescence efficiencies, L/N, or 'g-factors', needed to reduce CN emission band fluxes to CN abundances, are also accessible via a Web-based service. The values at any heliocentric distance vary by about a factor of two with varying velocities, but the specific structure of this variation with velocity changes dramatically with distance.

2010-01-01

338

Band oscillator strengths of the (2, 1)-(12, 1) Schumann-Runge Bands of O sub 2 from absolute absorption cross-section measurements at room temperature  

Energy Technology Data Exchange (ETDEWEB)

The absolute absorption cross sections of the (2, 1)-(12, 1) Schumann-Runge bands of O{sub 2} at room temperature have been obtained from measurements of the total absolute absorption cross sections arising from transitions from the ground-state levels with {upsilon}{double prime} = 0 and 1 by subtraction of the {upsilon}{double prime} = 0 contributions, which have synthesized from our previous determinations of the band oscillator strengths, line center positions and predissociation line widths of the ({upsilon}{prime}, 0) Schumann-Runge bands of O{sub 2}. The resultant absolute absorption cross sections of the (2, 1)-(12, 1) bands have been integrated numerically to obtain the band oscillator strengths. Our experimental band oscillator strengths are somewhat lower than the experimental values of Lewis et al. (1986) but are in good agreement with the recently calculated values of Friedman (1990).

Yoshino, K.; Esmond, J.R.; Cheung, A.S.C.; Freeman, D.E.; Parkinson, W.H. (Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (USA))

1990-07-20

339

Search for superdeformed bands in {sup 154}Dy  

Energy Technology Data Exchange (ETDEWEB)

The island of superdeformation in the vicinity of the doubly magic {sup 152}Dy yrast superdeformed (SD) band is thought to be well understood in the framework of cranked mean field calculations. In particular, the calculations suggested that in {sup 154}Dy there should be no yrast or near yrast SD minimum in the 40-60 h spin range, where SD bands in this mass region are thought to be {sup 153}Dy nucleus, it is populated. However, with the presence of five SD bands in the neighboring necessary to ascertain if the addition of one single neutron diminishes the importance of shell effects to the extent that superdeformation can no longer be sustained. In an experiment utilizing the increased resolving power of the early implementation phase of Gammasphere, the reaction {sup 122}Sn({sup 36}S,4n) at 165 MeV was employed to populate high spin states in {sup 154}Dy. In a four-day run with 36 detectors, over one billion triple and higher fold coincidence events were recorded. One new SD band was identified and was assigned to {sup 154}Dy. From comparisons with the Im{sup (2)} moments of inertia of the SD bands in {sup 152}Dy and {sup 153}Dy, a configuration based on (514)9/2{sup 2} neutrons coupled to the {sup 152}Dy SD core was proposed. One unexpected and as yet unexplained feature of this new SD band is that the transition energies are almost identical to those of an excited SD band in {sup 153}Dy. It is also worth noting that the feeding of the yrast states is similar to that achieved by the deexcitation from the ensemble of all entry states in the reaction. This observation emphasizes the statistical nature of the decay-out process. A paper reporting these results was accepted for publication.

Nisius, D.; Janssens, R.V.F.; Khoo, T.L. [and others

1995-08-01

340

BAND-TAIL SHOCKLEY-READ-HALL RECOMBINATION IN HEAVILY DOPED SILICON  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Shockley-Read-Hall recombination center density due to the localized states in the minority carrier band tail has been calculated. It is shown that in heavily doped silicon, the effect of these band tail states is comparable to or more important than that due to deep states and modifies the lifetime...

Ghannam, M.; Mertens, R.; Jain, S.; Nijs, J.; Van Overstraeten, R.

 
 
 
 
341

New band structures and an unpaired crossing in 78Kr  

International Nuclear Information System (INIS)

High-spin states in 78Kr were studied using the 58Ni(23Na,3p) reaction at 70 MeV and the 58Ni(28Si,?4p) reaction at 130 MeV. Prompt ?-? coincidences were measured using the Pitt-FSU detector array and the GAMMASPHERE-MICROBALL array. Results from these experiments have led to 26 new excitation levels, some of which have been grouped into 3 new bands. Spins were assigned based on directional correlations of oriented nuclei. Two of the new negative-parity bands appear to form a signature-partner pair based on a two-quasineutron structure, in contrast to the previously known two-quasiproton negative-parity bands. A forking has been observed at the 24+ state in the yrast band, which calculations suggest may result from an unpaired crossing. The available evidence suggests oblate shapes in the yrast band coexist with prolate shapes in the negative-parity bands. copyright 1999 The American Physical Society.

1999-01-01

342

Configuration-dependent bands in {sup 169}Re  

Energy Technology Data Exchange (ETDEWEB)

High-spin states in {sup 169}Re were studied and resulted in the identification of a strongly coupled band based on the 9/2{sup -}[514] Nilsson state and a decoupled band built on the h{sub 9/2} 1/2{sup -}[541] intruder proton orbit. The cranked-shell-model calculations present configuration-dependent deformations that can explain the different band crossing frequencies. The 9/2{sup -}[514] band in {sup 169}Re shows the largest signature splitting at low spin among the known odd-mass Re isotopes. After the alignment of a pair of i{sub 13/2} neutrons, the phase of the splitting is inverted with a significantly reduced amplitude. For the 9/2{sup -}[514] bands in light odd-A Re isotopes, the signature splitting of the Routhians and its relation with the signature dependence of M1 transition matrix elements are investigated in connection with the deviation of nuclear shape from axial symmetry, suggesting an appreciable negative {gamma} deformation for the very neutron-deficient odd-A Re isotopes. Additionally, a three-quasiparticle band was observed and assigned to be built likely on the {pi}9/2{sup -}[514] x AE configuration. (orig.)

Zhou, X.H.; Zhang, Y.H.; Zheng, Y.; Xu, Y.B. [Institute of Modern Physics, Chinese Academy of Sciences, 730000, Lanzhou (China); Oshima, M.; Toh, Y.; Koizumi, M.; Osa, A.; Hayakawa, T.; Hatsukawa, Y.; Shizuma, T. [Japan Atomic Energy Research Institute, 319-1195, Ibaraki, Tokai (Japan); Xu, F.R. [Department of Technical Physics and MOE Key Laboratory, Peking University, 100871, Beijing (China); Sugawara, M. [Chiba Institute of Technology, 275-0023, Chiba, Narashino (Japan)

2004-01-01

343

Spins of superdeformed band in {sup 192}Hg  

Energy Technology Data Exchange (ETDEWEB)

Determination of the spins of SD states is the most important challenge in the study of superdeformation. Knowledge of the spin will provide crucial information on SD bands, in particular on the fascinating phenomenon of bands with identical energies and moments of inertia. Angular distribution coefficients of the {gamma}rays decaying out of the {sup 192}Hg SD band were determined using Eurogam data. These coefficients, as well as the spectral shape and multiplicity of the spectrum, are compared with the results of calculations, thereby providing a check on these calculations. From the measured decay multiplicity and the calculated average spin removed per photon (0.3 h), we deduce the average spin {bar I}{sub decay} removed by the {gamma} rays connecting SD and normal states. The spin I{sub SD} of the SD band from which the decay occurs is given by I{sub SD} = {bar I} decay + {bar I} ND, where {bar I} ND is the average spin removed by the normal yrast states. The state from which the major decay out of the SD band occurs is found to have spin 9.5 {plus_minus} 0.8 h. Since angular momentum is (quantized), this leads to a spin assignment of 9 or 10 h. The latter value is favored since the yrast band in the SD well must have only even spin values. This constitutes the first deduction of spin from data in the mass 150 and 190 regions. The spin of 10 h agrees with the spin which is inferred from a model, using the observed moment of inertia (Im){sup (2)}{omega}.

Lauritsen, T.; Khoo, T.L.; Henry, R.G. [and others

1995-08-01

344

Optically detecting spin-split bands in semiconductors in magnetic fields  

Science.gov (United States)

We report on combined theoretical and experimental studies of spin-split bands in semiconductors in magnetic fields. We have studied a wide range of systems including: 1) electron and valence band splitting in dilute magnetically doped semiconductors (DMS) systems like InMnAs, 2) electron and valence band splitting in strained InSb/AlInSb heterostructures and 3) valence band splitting in GaAs. The systems have been studied with a variety of experimental techniques including: i) ultra-high magnetic field cyclotron resonance ii) magnetoabsorption and iii) optically pumped NMR (OPNMR). Calculations are based on the 8-band Pidgeon-Brown model generalized to include the effects of the quantum confinement potential as well as pseudomorphic strain at the interfaces and sp-d coupling between magnetic impurities and conduction band electrons and valence band holes. Optical properties are calculated within the golden rule approximation and compared with experiments. Detailed comparison to experiment allows one to accurately determine conduction and valence band parameters including effective masses and g-factors. Results for InMnAs show shifts in the cyclotron resonance peaks with Mn doping. For InSb, we find a sensitive dependence of the elecronic structure on the strain at the pseudomorphic interfaces. For GaAs, we show that OPNMR allows us to spin-resolve the valence bands and that structure in the OPNMR signal is dominated by the weaker light hole to conduction band Landau level transitions.

Pan, X.; Sun, Y.; Saha, D.; Sanders, G. D.; Santos, M. B.; Doezema, R. E.; Hayes, S.; Khodaparast, G.; Munekata, H.; Matsuda, Y. H.; Kono, J.; Stanton, C. J.

2012-10-01

345

Two-dimensional shear bands growing dynamically in plates: An investigation of transient deformation fields, temperature fields and shear band toughness  

Energy Technology Data Exchange (ETDEWEB)

The phenomenon of dynamic initiation and propagation of two-dimensional adiabatic shear bands is experimentally and numerically investigated. Prenotched metal plates are subjected to asymmetric impact load histories (dynamic mode-II loading). Dynamic shear bands emanate from the notch-tip and propagate rapidly in a direction nearly parallel to the direction of impact. Real time temperature histories along a line intersecting and perpendicular to the shear band paths are recorded by means of a high speed infrared detector system. The materials studied are C-300 (a maraging steel), HY-100 steel and Ti-6Al-4V. Experiments show that the peak temperatures inside the propagating shear bands are approaching 90% of the melting point for C-300 and are significantly lower for the titanium alloy (up to 6000C). Additionally, measured distances of shear band propagation indicate stronger resistance to shear banding by HY-100 steel and Ti-6Al-4V. Deformation fields around the propagating shear band are recorded using high speed photography. Shear band speeds are found to strongly depend on impact velocity are as high as 1200 m/s for C-300 steel. Finite element simulations of the experiment are carried out under the context of plane strain, considering finite deformations, inertia, heat conduction, thermal softening, strain hardening and strain-rate hardening. In the simulations, the shear band propagation is assumed to be governed by a critical plastic strain criterion. The results are compared with experimental measurements obtained using the high speed infrared detectors and high speed photography. Finally, the numerical calculations are used to investigate motions of shear band toughness. The shear band driving force is calculated as a function of shear band velocity and compared to the crack driving force versus velocity relations for mode-I, opening cracks in the same material.

Rosakis, A.J. [California Institute of Technology, Pasadena, CA (United States)

1995-12-31

346

Transistorized wide band pulse amplifier  

International Nuclear Information System (INIS)

[en] A simple wide band amplifier is described below, having a stability better than 10/00 deg-1 centigrade, a current gain of 103, bandwidth of 30 MHz, and a signal to noise current ratio of about 100. This amplifier has been studied to answer the necessity of a fast transistor head amplifier for nuclear detectors, having in mind pile up and overloading problems. (author)[fr] Un amplificateur simple, a large bande, est decrit ci-apres, il a une stabilite meilleure que le 0/00 par degre centigrade, un gain en courant de 103 une largeur de bande de 30 MHz, et un rapport signal sur bruit en courant d'environ 100. Cet amplificateur a ete etudie pour repondre a la necessite de l'amplification des impulsions provenant de detecteurs nucleaires, ayant a l'esprit les problemes d'empilement et de saturation. (auteur)

1960-01-01

347

Positron band structures of GaAs and CdTe  

International Nuclear Information System (INIS)

The problem of positron and structure in a periodic lattice is similar to its electron counterpart. GaAs and CdTe positron band structures are calculated, a comparison between the electron and positron energies is discussed. (author).

1990-01-01

348

Interband electronic Raman scattering of polarized light in cubic semiconductors with degenerate valence bands  

International Nuclear Information System (INIS)

[en] The cross-sections are calculated for the Raman scattering processes with polarized light in cubic semiconductors where the valence band top is fourfold degenerate ?8. The exciton effect is taken into account. (author). 17 refs

1987-01-01

349

Electronic band parameters for zinc-blende Al1-xGaxN  

International Nuclear Information System (INIS)

Band-structure calculations are performed for cubic Al1-xGaxN using the empirical pseudopotential method. The band gaps at ?, X and L points and the electron effective masses of ? and X valleys are calculated as a function of the gallium fraction x. It is found that there is no significant change in these electronic band parameters on taking into account the alloy disorder. On the basis of a model solid theory, we have calculated the band discontinuities for heterointerfaces between strained Al1-xGaxN and relaxed Al1-yGayN. The latter calculations are extended to the whole range of compositions x and y. The information derived from this investigation will be useful in the design of lattice-mismatched heterostructures in blue-light optoelectronics applications. (author)

2002-07-29

350

Copper-Band Winding Magnetic Lens of the High-Voltage Electron Microscope.  

Science.gov (United States)

The winding of a transmission electron microscope magnetic lens by a copper band is shown to have the advantages of better magnetic circuit section utilization and greater current density. An exemplary calculation of the magnetomotive force of such lens a...

G. A. Soldatenko

1977-01-01

351

Lifetimes in E2 bands of 142Gd measured with DSAM at EUROBALL  

International Nuclear Information System (INIS)

Lifetimes have been measured for four quadrupole bands in 142Gd with EUROBALL using the Doppler-shift attenuation method. The deduced B(E2) values have been compared with results of Interacting Boson Model calculations.

2006-01-01

352

Isomer ratio calculations using modeled discrete levels  

International Nuclear Information System (INIS)

We have calculated isomer ratios for the 175Lu(n,?), 175Lu(n,2n), 237Np(n,2n), 241Am(n,?), and 243Am(n,?) reactions using modeled level structures in the deformed, odd-odd product nuclei. We find: that the hundreds of discrete levels and their gamma-ray branching ratios provided by the modeling are necessary to achieve agreement with experiment, that many rotational bands must be included in order to obtain a sufficiently representative selection of K quantum numbers, and that the levels of each band must be extended to appropriately high values of angular momentum. 8 references

1984-01-01

353

Band structures of {sup 121,123}I  

Energy Technology Data Exchange (ETDEWEB)

The band structures of {sup 121,123}I nuclei have been studied using a version of the particle-rotor-model in which the experimental excitation energies of the neighbouring (A-1) cores can be fed directly as input parameters. The calculations have been carried out with axially symmetric Nilsson potential with both prolate and oblate deformations. The parameters of the model have been chosen from earlier theoretical work and experimental odd-even mass differences. Only the Coriolis attenuation factor has been treated as adjustable parameter. The theoretical band structures are in very good agreement with the available experimental data. (orig.)

Goswami, R. [Saha Inst. of Nuclear Physics, Calcutta (India); Sethi, B. [Saha Inst. of Nuclear Physics, Calcutta (India); Sarkar, M.S. [Saha Inst. of Nuclear Physics, Calcutta (India); Sen, S. [Saha Inst. of Nuclear Physics, Calcutta (India)

1995-09-01

354

High-spin structure beyond band termination in Er157  

International Nuclear Information System (INIS)

The angular-momentum induced transition from a deformed state of collective rotation to a noncollective configuration has been studied. In Er157 this transition manifests itself as favored band termination near I=45(?/2?). The feeding of these band terminating states has been investigated for the first time using the Gammasphere spectrometer. Many weakly populated states lying at high excitation energy that decay into these special states have been discovered. Cranked Nilsson-Strutinsky calculations suggest that these states arise from weakly collective 'core-breaking' configurations.

2004-06-25

355

Triaxial strongly deformed bands in 160,161Tm  

International Nuclear Information System (INIS)

High-spin states in 160,161Tm were populated using the 128Te(37Cl, 5n and 4n) reactions at a beam energy of 170 MeV. Emitted ? rays were detected in the Gammasphere spectrometer. Two rotational bands with high moments of inertia were discovered, one assigned to 160Tm, while the other tentatively assigned to 161Tm. These sequences display features similar to bands observed in neighboring Er, Tm, Yb, and Lu nuclei which have been discussed in terms of triaxial strongly deformed structures. Cranked Nilsson Strutinsky calculations have been performed that predict well-deformed triaxial shapes at high spin in 160,161Tm

2008-01-01

356

The thermodynamic properties of BaNd2O4  

International Nuclear Information System (INIS)

Using the method of electromotive forces with fluorine-ionic electrolyte within 1040-1170 K range one determined temperature dependence of the Hibbs energy for BaNd2O4 formation from single oxides. he calculated values of the Hibbs energy and enthalpy of BaNd2O4 formation from oxides under 1100 K constituted -19.4 and -30.4 kJ/mole, respectively. One demonstrated absence of essential oxygen nonstoichiometry in the investigated compound under O2?1-10-5 atm partial pressures

2001-01-01

357

Evidence for Nontermination of Rotational Bands in 74Kr  

International Nuclear Information System (INIS)

Three rotational bands in 74Kr were studied up to (in one case one transition short of) the maximum spin Imax of their respective single-particle configurations. Their lifetimes have been determined using the Doppler-shift attenuation method. The deduced transition quadrupole moments reveal a modest decrease, but far from a complete loss of collectivity at the maximum spin Imax. This feature, together with the results of mean field calculations, indicates that the observed bands do not terminate at I=Imax.

2005-12-02

358

Development of TE11 mode X-band RF window  

International Nuclear Information System (INIS)

[en] Development of a TE11 mode X-band RF window capable above RF pulses of 100 MW, 1?s, is underway to realize a X-band high-power klystron for JLC. This paper describes design and a high-power test for the window which comprises TE10(WRJ-10)-TE11 mode(WC-5) converters, circular waveguide tapers and a alumina ceramic with a circular wave guide frame. Evaluation circuit method and numerical calculations were used for the design. The result of the test using a resonant ring has been successfully carried out with the circulating power of '100 MW, 300 ns'. (author)

1994-01-01

359

Band structure of 68Ge  

Science.gov (United States)

The nucleus 68Ge has been studied by gamma-ray spectroscopy following its population at high spin in the reaction 40Ca(32S,4p)68Ge. The reaction channel was selected with the Microball array and gamma rays were detected with the Gammasphere array. The level scheme is very complex, reflecting the many different, and presumably mixed, excitation modes in this nucleus. Nevertheless, there appear to be some simplifications in the spin range above 18? where we have identified a superdeformed band and several terminating bands. The results are compared with a cranked Nilsson-Strutinsky model without pairing.

Ward, D.; Svensson, C. E.; Ragnarsson, I.; Baktash, C.; Bentley, M. A.; Cameron, J. A.; Carpenter, M. P.; Clark, R. M.; Cromaz, M.; Deleplanque, M. A.; Devlin, M.; Diamond, R. M.; Fallon, P.; Flibotte, S.; Galindo-Uribarri, A.; Haslip, D. S.; Janssens, R. V.; Lampman, T.; Lane, G. J.; Lee, I. Y.; Lerma, F.; Macchiavelli, A. O.; Paul, S. D.; Radford, D.; Rudolph, D.; Sarantites, D. G.; Schaly, B.; Seweryniak, D.; Stephens, F. S.; Thelen, O.; Vetter, K.; Waddington, J. C.; Wilson, J. N.; Yu, C.-H.

2001-01-01

360

Quasiparticle semiconductor band structures including spin-orbit interactions  

Science.gov (United States)

We present first-principles calculations of the quasiparticle band structure of the group IV materials Si and Ge and the group III-V compound semiconductors AlP, AlAs, AlSb, InP, InAs, InSb, GaP, GaAs and GaSb. Calculations are performed using the plane wave pseudopotential method and the ‘one-shot’ GW method, i.e. G0W0. Quasiparticle band structures, augmented with the effects of spin-orbit, are obtained via a Wannier interpolation of the obtained quasiparticle energies and calculated spin-orbit matrix. Our calculations explicitly treat the shallow semicore states of In and Ga, which are known to be important in the description of the electronic properties, as valence states in the quasiparticle calculation. Our calculated quasiparticle energies, combining both the ab initio evaluation of the electron self-energy and the vector part of the pseudopotential representing the spin-orbit effects, are in generally very good agreement with experimental values. These calculations illustrate the predictive power of the methodology as applied to group IV and III-V semiconductors.

Malone, Brad D.; Cohen, Marvin L.

2013-03-01

 
 
 
 
361

Regional confidence bands for ROC curves.  

UK PubMed Central (United Kingdom)

The performance of a diagnostic test is characterised by its specificity and sensitivity. For a quantitative diagnostic test these criteria depend on the selected cut-off point. The receiver operating characteristic (ROC) curve of a quantitative diagnostic test is generated by plotting sensitivity against specificity as the cut-off point runs through the whole range of possible test values. In practice, the ROC curve is estimated from clinical data. One important goal is to select an optimal cut-off point. For this purpose the sample variability has to be taken into account. Recently, Campbell has introduced nonparametric asymptotic simultaneous confidence bands that are valid for the whole ROC curve. In this paper a nonparametric asymptotic approach for the construction of regional confidence bands for ROC curves is proposed. It can be applied for any specificity interval of interest. Our approach is based on the asymptotic theory of empirical and quantile processes. To investigate the small sample properties of the different approaches, a Monte Carlo study was conducted using normal and log-normal data. A method for sample size calculation is presented. Finally, the approaches are applied to a tumour marker in the diagnosis of bone marrow metastases.

Jensen K; Müller HH; Schäfer H

2000-02-01

362

Possible Smooth Band Termination in ^123La  

Science.gov (United States)

The power of GAMMASPHERE was combined with the selectivity of the MICROBALL in an experiment to investigate rotational structures of near-drip-line nuclei in the La-Nd region. The reaction ^40Ca + ^92Mo was used with a beam energy of 184 MeV. One of the weaker charged-particle channels (2? p), which comprised ˜1.3% of the events recorded, was investigated to study high-spin states in ^123La. Three new decoupled sequences were identified and the previously known structures [1] were significantly extended towards ˜40hbar. It is within this spin region that smooth band termination has been observed in ^127,129La [2]. A minimum in an energy minus a rigid rotor reference plot, which is often attributed to smooth band termination, is in fact observed for the lowest (?,?) = (+,-1/2) configuration. Therefore, cranked Nilsson-Strutinsky calculations were performed and compared with experimental data in order to determine whether the observed sequence is approaching a terminating state. [1] R. Wyss et al., Nucl. Phys. A 503, 244 (1989); [2] R. Wadsworth et al., Phys. Rev. C 62, 034315 (2000).

Park, H. I.; Hartley, D. J.; Riedinger, L. L.; Zeidan, O.; Zhang, Jing-Ye; Galindo-Uribarri, A.; Carpenter, M. P.; Janssens, R. V. F.; Seweryniak, D.; Devlin, M.; Reviol, W.; Sarantites, D. G.; Dong, B. G.; Ragnarsson, I.

2002-10-01

363

Crossing of shears bands in 196Pb  

International Nuclear Information System (INIS)

[en] High-spin states in 196Pb have been populated using the reaction 170Er(30Si, 4n). The previously observed shear bands in this nucleus have been extended and some of their transitions have been reordered. They now form regular bands with band crossings. One of the bands splits into two pathways at high spin. (orig.)

1996-01-01

364

Yield strain in shear banding amorphous solids.  

UK PubMed Central (United Kingdom)

In recent research it was found that the fundamental shear-localizing instability of amorphous solids under external strain, which eventually results in a shear band and failure, consists of a highly correlated array of Eshelby quadrupoles all having the same orientation and some density ?. In this paper we calculate analytically the energy E(?,?) associated with such highly correlated structures as a function of the density ? and the external strain ?. We show that for strains smaller than a characteristic strain ?(Y) the total strain energy initially increases as the quadrupole density increases, but that for strains larger than ?(Y) the energy monotonically decreases with quadrupole density. We identify ?(Y) as the yield strain. Its value, derived from values of the qudrupole strength based on the atomistic model, agrees with that from the computed stress-strain curves and broadly with experimental results.

Dasgupta R; Hentschel HG; Procaccia I

2013-02-01

365

Yield strain in shear banding amorphous solids  

Science.gov (United States)

In recent research it was found that the fundamental shear-localizing instability of amorphous solids under external strain, which eventually results in a shear band and failure, consists of a highly correlated array of Eshelby quadrupoles all having the same orientation and some density ?. In this paper we calculate analytically the energy E(?,?) associated with such highly correlated structures as a function of the density ? and the external strain ?. We show that for strains smaller than a characteristic strain ?Y the total strain energy initially increases as the quadrupole density increases, but that for strains larger than ?Y the energy monotonically decreases with quadrupole density. We identify ?Y as the yield strain. Its value, derived from values of the qudrupole strength based on the atomistic model, agrees with that from the computed stress-strain curves and broadly with experimental results.

Dasgupta, Ratul; Hentschel, H. George E.; Procaccia, Itamar

2013-02-01

366

Metaphyseal bands in osteogenesis imperfecta  

Directory of Open Access Journals (Sweden)

Full Text Available An increasing number of patients with osteogenesis imperfecta are undergoing pamidronate therapy to prevent the incidence of fragility fractures. The authors herein report a child aged 3 years who received five cycles of pamidronate, resulting in metaphyseal bands, known as "zebra lines."

Suresh S; Thomas John

2010-01-01

367

Band structure and nuclear dynamics  

International Nuclear Information System (INIS)

The relation between the Variable Moment of Inertia model and the Interacting Boson Model are discussed from a phenomenological viewpoint. New results on ground state mean-square radii in nuclei far from stability are reported, and a discussion of band structure extending to high angular momentum states and methods of extracting information on the underlying dynamics is given.

1981-09-11

368

Impurity bands in Kondo insulators  

Energy Technology Data Exchange (ETDEWEB)

Kondo insulators like Ce{sub 3}Bi{sub 4}Pt{sub 3} and CeNiSn are compounds with small-band-gap semiconductor properties. Nonmagnetic impurities, so-called Kondo holes, break the translational invariance and hence the coherence of the ground state. Isolated impurities give rise to a bound state in the gap, which pins the Fermi level and has magnetic properties (Curie susceptibility and Schottky anomaly in the specific heat). A finite concentration of Kondo holes gives rise to an impurity band inside the gap of the {ital f}-electron density of states, whose height and width are proportional to {radical}{ital c} for small concentrations. The specific heat is proportional to {ital T} at very low temperatures and the susceptibility is Pauli-like at low {ital T}. The correlations within the {ital f} band are introduced via a self-energy, evaluated to second-order perturbation in {ital U}. We use the (1/{ital d})-expansion method of Schweitzer and Czycholl to leading order in which the {bold k} integrations are properly carried out, but the {bold k} dependence of the self-energy is neglected. The main effect of {ital U} is to narrow the gap, as well as the impurity band.

Schlottmann, P. (Department of Physics and Center for Materials Research and Technology, Florida State University, Tallahassee, Florida 32306 (United States))

1992-07-01

369

K-band latching switches  

Science.gov (United States)

Design, development, and tests are described for two single-pole-double-throw latching waveguide ferrite switches: a K-band switch in WR-42 waveguide and a Ka-band switch in WR-28 waveguide. Both switches have structurally simple junctions, mechanically interlocked without the use of bonding materials; they are impervious to the effects of thermal, shock, and vibration stresses. Ferrite material for the Ka-band switch with a proper combination of magnetic and dielectric properties was available and resulted in excellent low loss, wideband performance. The high power handling requirement of the K-band switch limited the choice of ferrite to nickel-zinc compositions with adequate magnetic properties, but with too low relative dielectric constant. The relative dielectric constant determines the junction dimensions for given frequency responses. In this case the too low value unavoidably leads to a larger than optimum junction volume, increasing the insertion loss and restricting the operating bandwidth. Efforts to overcome the materials-related difficulties through the design of a composite junction with increased effective dielectric properties efforts to modify the relative dielectric constant of nickel-zinc ferrite are examined.

Piotrowski, W. S.; Raue, J. E.

1984-05-01

370

A numerical study into the influence of quantum dot size on the sub-bandgap interband photocurrent in intermediate band solar cells  

Directory of Open Access Journals (Sweden)

Full Text Available A numerical study is presented of the sub-bandgap interband photon absorption in quantum dot intermediate band solar cells. Absorption coefficients and photocurrent densities are calculated for the valence band to intermediate band transitions using a four-band k·p method. It is found that reducing the quantum dot width in the plane perpendicular to the growth direction increases the photocurrent from the valence band to the intermediate-band ground state if the fractional surface coverage of quantum dots is conserved. This provides a path to increase the sub-bandgap photocurrent in intermediate band solar cells.

Alexander Mellor; Antonio Luque; Ignacio Tobías; Antonio Martí

2013-01-01

371

Decoupled 2-quasiparticle bands and backbending in 174W and 172Hf  

International Nuclear Information System (INIS)

Negative parity sidebands have been observed to high spin in the N = 100 isotones 174W and 172Hf. Their high and constant moment of inertia, and decay characteristics, identify them as semi-decoupled bands, probably of a configuration involving a psub(3/2) or hsub(9/2) neutron and an isub(13/2) neutron. The character of these bands is used to estimate the properties of the (isub(13/2))2 neutron band responsible for backbending, and through a two-band mixing calculation, the details of backbending. (Author)

1977-01-01

372

Quasiparticle band structure of bulk hexagonal boron nitride and related systems  

Energy Technology Data Exchange (ETDEWEB)

The quasiparticle band structure of bulk hexagonal boron nitride is studied within the [ital GW] approximation for the self-energy operator. The influence of the interlayer distance on the band structure is investigated both within the local density approximation and the quasiparticle approach, and the importance of an interlayer state in determining the gap is demonstrated. Also, the quasiparticle band structure for an isolated sheet of boron nitride is calculated. We show that the equivalent of the interlayer state in the case of the isolated boron nitride sheet plays the same role as in the bulk case in determing the band gap.

Blase, X.; Rubio, A.; Louie, S.G.; Cohen, M.L. (Department of Physics, University of California at Berkeley, Berkeley, California 94720 (United States) Materials Sciences Division, Lawrence Berkeley Laboratory, Berkeley, California 94720 (United States))

1995-03-15

373

Crossing of negative parity bands in even-even nuclei around A approximately 150  

International Nuclear Information System (INIS)

Level energies of negative parity yrast bands (NPB) have been studied with a recently proposed, sensitive method. The irregular behaviour of the NPB's in the N = 88 nuclei around spin 9-11 and the smooth behaviour in 156Dy (up to I = 13) and in 238U (up to I = 19) support calculations by Vogel, where NPB's are described as aligned octupole bands up to a critical spin where intersection with two-quasiparticle bands takes place. Considering the NPB levels (I 156Dy as members of an aligned octupole band, we obtain a remarkably good reproduction of their decay properties and energies using the VMI model. (orig.)

1978-01-01

374

Chiral geometry of higher excited bands in triaxial nuclei with particle-hole configuration  

International Nuclear Information System (INIS)

The lowest six rotational bands have been studied in the particle-rotor model with the particle-hole configuration ?h11/21 x ?h11/2-1 and different values of the triaxiality parameter ?. Both constant and spin-dependent variable moments of inertia (CMI and VMI, respectively) are introduced. The energy spectra, electromagnetic transition probabilities, angular momentum components, and K distribution are examined. It is shown that, besides bands 1 and 2, the predicted bands 3 and 4 in the calculations with both CMI and VMI for atomic nuclei with ?=30 deg. could be interpreted as chiral doublet bands.

2010-01-01

375

Analysis of high-spin rotational band in odd-odd 170Re  

International Nuclear Information System (INIS)

One high-spin rotational band in neutron deficient odd-odd nucleus 170Re has been identified and assigned to the ?h1/2 direct x ?i13/2 configuration through the 142Nd (32S, 1p3n ?) 170Re reaction. The band is analyzed on the basis of the arguments of energy systematics, signature inversion systematics, intra-band B (M1)/B (E2) ratios, quasiparticle Routhians, dynamic moment of inertia and Total Routhian Surface (TRS) calculations. From detailed analyses on its structural properties, the configuration, spins and parity have been further assigned for this rotational band. (authors)

2010-01-01

376

Quasiparticle band structure of bulk hexagonal boron nitride and related systems  

International Nuclear Information System (INIS)

The quasiparticle band structure of bulk hexagonal boron nitride is studied within the GW approximation for the self-energy operator. The influence of the interlayer distance on the band structure is investigated both within the local density approximation and the quasiparticle approach, and the importance of an interlayer state in determining the gap is demonstrated. Also, the quasiparticle band structure for an isolated sheet of boron nitride is calculated. We show that the equivalent of the interlayer state in the case of the isolated boron nitride sheet plays the same role as in the bulk case in determing the band gap.

1995-01-01

377

MANIFESTATION OF DEFORMATION EFFECT IN BAND SPECTRA IN CRYSTALS WITH INHOMOGENEOUS BONDING  

Directory of Open Access Journals (Sweden)

Full Text Available The effect of the shear strains on the energy spectrum of the strongly anisotropic SbSI crystal has been investigated by group-theoretical method in combination with the Pikus method of invariants. The first-principles local density approximation has been implemented to determine the band structure of the crystal. Ab initio calculations of the band structure have shown an exact localization of twofold degenerate maximum of the valence band in the T point. It turned out that the shear strains result in the band topology changes in the vicinity of the T point and the k-linear term appears in the corresponding dispersion law.

D.M.Bercha; K.Z.Rushchanskii; I.V.Slipukhina; I.V.Bercha

2003-01-01

378

Shadow band in the one-dimensional large U Hubbard model  

CERN Document Server

We show that the factorized wave-function of Ogata and Shiba can be used to calculate the k dependent spectral functions of the one-dimensional, infinite U Hubbard model, and of some extensions to finite U. The resulting spectral function is remarkably rich: In addition to low energy features typical of Luttinger liquids, there is a well defined band, which we identify as the shadow band resulting from 2k_F spin fluctuations. This band should be detectable experimentally because its intensity is comparable to that of the main band for a large range of momenta.

Penc, K; Mila, F; Shiba, H; Penc, Karlo; Hallberg, Karen; Mila, Frederic; Shiba, Hiroyuki

1996-01-01

379

Search for excited superdeformed bands in {sup 151}Dy  

Energy Technology Data Exchange (ETDEWEB)

Following the first report of superdeformed (SD) bands with identical transition energies in the pairs ({sup 151}Tb*,{sup 152}Dy), ({sup 150}Gd*, {sup 151}Tb) and ({sup 153}Dy*, {sup 152}Dy) (where * denotes an excited SD band), it was proposed by Nazarewicz et al. that the observations could be understood in a strong-coupling approach if pseudo SU(3) symmetry were invoked. In this model there are three limiting values of the decoupling parameter; i.e. a = 0, {plus_minus}1. In the first two cases mentioned above the pairs of bands have nearly identical transition energies and are interpreted as proton excitations involving the [200]1/2 pseudospin orbital coupled to the {sup 152}Dy core, for which the value of the decoupling parameter is calculated to be a =+1.

Nisius, D.; Janssens, R.V.F.; Crowell, B. [and others

1995-08-01

380

Neutron i13/2 intruder band in 139Sm  

International Nuclear Information System (INIS)

The high-spin structure of 139Sm has been investigated with the 110Pd(34S,5n) reaction at a beam energy of 159 MeV at the Stony Brook Tandem/Superconducting LINAC facility. The TESSA3 spectrometer array was used to collect ?-? coincidence data from which an extended decoupled band structure has been found. It is proposed that this band is based on the i13/2 (?=1/2) neutron intruder orbital. The decay pattern, enhanced dynamic moments of inertia, and aligned spins are consistent with the ?i13/2 bands in neighboring odd-neutron nuclides. Total Routhian surface and cranked shell model calculations reproduce qualitative features of these nuclides, further supporting the proposed interpretation.

1994-01-01

 
 
 
 
381

Simple description of double bands with mass of approximately 100  

International Nuclear Information System (INIS)

A simple collective model is applied to understand the structure of the ?I=1 doublet bands with the ?h11/2 x ?g9/2 configuration in the doubly-odd nuclei, 98-104Tc and 100-106Rh. In the model, a doubly-odd nucleus is realized when there is one neutron in the 0h11/2 orbital and one proton in the 0g9/2 orbital, and the collective core represents the even-even part of the nucleus. The calculation reproduces the energy spectra and the ratios B(M1; I ? I-1) / B(E2; I ? I-2) for the doublet bands quite well. The analysis of the wave functions reveals new band structure, showing various angular momentum configurations of the neutron and the proton, weakly coupled with the quadrupole collective excitations of the core. (author)

2008-01-01

382

Band Structures and Nucleon Alignments in ^173,175W  

Science.gov (United States)

Spectroscopic study of nuclei in the A˜180 region is essential to better understand regional relationships between Nilsson orbitals. Highly excited rotational states in both nuclei were populated at Argonne National Laboratory via a 230 MeV ^50Ti beam from the ATLAS accelerator incident on a ^128Te target. The Gammasphere array was used to detect ? decays from excited states. Rotational bands built on the level 1/2^-[521], p3/2 in ^173,175W have been extended to spins of 40 and 35 respectively, and bands built on the 7/2^+[633], i13/2 configuration extended to 38 and 27 respectively. New sidebands in ^173W have been observed in all previously-discovered bands. Alignments from i13/2 neutron and h11/2 proton crossings are consistent with predictions of Woods-Saxon cranking calculations. Experimental results and regional systematics will be presented.

Guess, C. J.; Tandel, S. K.; Chowdhury, P.; Shirwadkar, U.; Carpenter, M. P.; Janssens, R. V. F.; Khoo, T. L.; Lauritsen, T.; Lister, C. J.; Seweryniak, D.; Wang, X.; Zhu, S.; Hartley, D. J.

2012-10-01

383

Extensive ?-ray spectroscopy of band structures in 3062Zn32  

Science.gov (United States)

An experimental study of the 62Zn nucleus has been performed by combining the data sets from four fusion-evaporation reaction experiments. Apart from the previously published data, the present results include ten new rotational band structures and two more superdeformed bands. The Gammasphere Ge-detector array in conjunction with the 4? charged-particle detector array Microball allowed for the detection of ? rays in coincidence with evaporated light particles. The deduced level scheme includes some 260 excited states, which are connected with more than 450 ?-ray transitions. Spins and parities of the excited states have been determined via directional correlations of ? rays emitted from oriented states. The experimental characteristics of the rotational bands are analyzed and compared with results from cranked Nilsson-Strutinsky calculations. The present analysis, combined with available experimental results in the A˜60 mass region, can be used to improve the current set of Nilsson parameters in the N=3 and N=4 oscillator shells.

Gellanki, J.; Rudolph, D.; Ragnarsson, I.; Andersson, L.-L.; Andreoiu, C.; Carpenter, M. P.; Ekman, J.; Fahlander, C.; Johansson, E. K.; Kardan, A.; Reviol, W.; Sarantites, D. G.; Seweryniak, D.; Svensson, C. E.; Waddington, J. C.

2012-09-01

384

Collective band properties in actinide nuclei well deformed  

International Nuclear Information System (INIS)

In actinides, proton i13/2 orbitals and neutron j15/2 orbitals are both near Fermi surface. At a great rotation speed, driving and Coriolis forces change the surface forces, in particular, they lower pairing forces inside the nucleus. The use of Coulomb excitation with the help of heavy and very heavy projectiles such as 32S, 84Kr, 142Nd, 208Pb at 232Th together with the most recent techniques of spectroscopy allowed to populate yrast bands of 230Th, 232Th, 235U and 237Np nuclei up to high spin states and together the even-even nuclei states in different collective bands. Experimental results have been analyzed in the frame of the different current models. The low spin states of rotational bands have been reproduced in a previous calculation using the nucleon-nucleon effective interaction of Skyrme III.

1984-01-01

385

Band structure analysis in SiGe nanowires  

International Nuclear Information System (INIS)

[en] One of the main challenges for Silicon-Germanium nanowires (SiGe NWs) electronics is the possibility to modulate and engine their electronic properties in an easy way, in order to obtain a material with the desired electronic features. Diameter and composition constitute two crucial ways for the modification of the band gap and of the band structure of SiGe NWs. Within the framework of density functional theory we present results of ab initio calculations regarding the band structure dependence of SiGe NWs on diameter and composition. We point out the main differences with respect to the case of pure Si and Ge wires and we discuss the particular features of SiGe NWs that are useful for future technological applications.

2012-06-05

386

Corrugated flat band as an origin of large thermopower in hole doped PtSb2  

Directory of Open Access Journals (Sweden)

Full Text Available The origin of the recently discovered large thermopower in hole-doped PtSb2 is theoretically analyzed based on a model constructed from first principles band calculation. It is found that the valence band dispersion has an overall flatness combined with some local ups and downs, which gives small Fermi surfaces scattered over the entire Brillouin zone. The Seebeck coefficient is calculated using this model, which gives good agreement with the experiment. We conclude that the good thermoelectric property originates from this “corrugated flat band”, where the coexistence of large Seebeck coefficient and large electric conductivity is generally expected.

Kouta Mori; Hidetomo Usui; Hirofumi Sakakibara; Kazuhiko Kuroki

2012-01-01

387

Algorithm for extraction of quantum oscillation orbits from band structure data  

Science.gov (United States)

In determining the Fermi surface of a material, quantum oscillation measurements are often compared to band structure calculations. Each oscillation frequency corresponds to an electron (or hole) orbit on the Fermi surface, perpendicular to the applied magnetic field; only orbits enclosing areas that are locally extremal are detected. To facilitate comparisons between theory and experiment, we have developed an algorithm, ``SKEAF,'' which finds extremal orbits in band structure calculations and determines quantum oscillation frequencies, effective masses and band specific heat contributions. Our code uses a k-space supercell approach, and can successfully locate geometrically-complicated orbits. Example results will be presented for the heavy fermion material UPt3.

Rourke, Patrick; Julian, Stephen

2008-03-01

388

The use of bulk states to accelerate the band edge statecalculation of a semiconductor quantum dot  

Energy Technology Data Exchange (ETDEWEB)

We present a new technique to accelerate the convergence of the folded spectrum method in empirical pseudopotential band edge state calculations for colloidal quantum dots. We use bulk band states of the materials constituent of the quantum dot to construct initial vectors and a preconditioner. We apply these to accelerate the convergence of the folded spectrum method for the interior states at the top of the valence and the bottom of the conduction band. For large CdSe quantum dots, the number of iteration steps until convergence decreases by about a factor of 4 compared to previous calculations.

Vomel, Christof; Tomov, Stanimire Z.; Wang, Lin-Wang; Marques,Osni A.; Dongarra, Jack J.

2006-05-10

389

Lamb wave band gaps in a homogenous plate with periodic Gaussian surfaces  

Science.gov (United States)

The Lamb wave band structure of a one-dimensional thin plate with periodic Gaussian surfaces is calculated based on the eigen-mode matching theory (EMMT) method. The finite element method is also employed to calculate the transmission power spectra and the band structure, which are both in good agreement with the results of the EMMT method. In contrast with the straight stubs, the low-frequency band gap of the system with the Gaussian surfaces is wider, when the Gaussian domain's height and area are equal to those of the stub, and the two systems' main plate size and materials are the same. This can be confirmed by the ‘spring–mass' model, which can be used to estimate the resonant frequency. We also investigate the effects of the geometrical parameters on band structure, including the height of the Gaussian domain, the plate thickness and the filling fraction. The results suggest that the band gaps have a close relevance to them.

Ming, Chen; Chen, Jiujiu; Han, Xu; Zhang, Hongbo

2013-09-01

390

Ginzburg-Landau theory: the case of two-band superconductors  

International Nuclear Information System (INIS)

Recent studies of two-band superconductors using Ginzburg-Landau (GL)theory are reviewed. The upper and lower critical fields, thermodynamic magnetic fields, critical current density, magnetization near the upper critical field, and the upper critical field of thin films are examined from the viewpoint of their temperature dependence at Tc using two-band GL theory. The results are shown to be in good agreement with the experimental data for the bulk samples of superconducting magnesium diborides and nonmagnetic borocarbides LuNi2B2C and YNi2B2C. The specific heat jump turns out to be smaller than calculated by single-band GL theory. The upper critical field of thin films of two-band superconductors is calculated, and the Little-Parks effect is analyzed. Extension of two-band GL theory to the case of layered anisotropy is presented

2006-01-01

391

Zero-point motion and temperature effects on the band gap of semiconductor nanoclusters  

Science.gov (United States)

We calculate the band gap renormalization of semiconductor nanoclusters, avoiding the large computational costs associated with the calculations of the self-energy (Fan) and the Debye-Waller terms. This approach allows us to address clusters with a few hundred atoms. For Silicon nanoclusters, we obtain a band gap reduction of hundreds of of meV associated with the quantum zero point motion. This reduction rapidly increases with decreasing cluster size. Based on the Bose-Einstein distribution, we further study the temperature dependence of the band gap in semiconductor nanoclusters and find a band gap shift of -580 meV and -270 meV when going from T=0 to room temperature for silicon clusters with radius of 9.6 and 11.9 ,espectively. Furthermore, we find that the band gap renormalization of semiconductor nanoclusters is dominated by the optic-like vibrational modes with ?4 point group symmetry.

Bester, Gabriel; Han, P.

2013-03-01

392

Total Routhian surface calculations for neutron-rich 149Ce  

CERN Document Server

Total Routhian Surface (TRS) calculations were performed for the 149Ce nucleus. The equilibrium deformation parameters and total angular momentum values have been calculated as a function of rotational frequency for both signatures of the lowest positive- and negative-parity rotational bands. Theoretical predictions are compared with the results of experimental studies of this nucleus.

Kaczarowski, R; Syntfeld, A; Mach, H; Kurcewicz, W; Fogelberg, B; Hoff, P

2001-01-01

393

Semiempirical calculations of the electronic structure in ionic crystals  

International Nuclear Information System (INIS)

Calculations of the electronic structure in ionic crystals with and without defects were performed using the standard molecular orbit CNDO/INDO program for molecular calculation but some important modifications and parameters optimization have been adopted to be suited to the ionic crystal condition. The calculated results, such as the width of valence bands and band gap, ground levels of perfect ionic crystals and F colour center in LIF, are listed and compared with previous results in our knowledge. (author). 11 refs, 1 fig., 3 tabs

1990-01-01

394

Band termination and signature crossing observation in some rare-earth nuclei  

International Nuclear Information System (INIS)

Predictions are very interesting features of moderately high angular momentum configurations as Band Termination, in nuclei with 10-12 valence particles outside the gadolinium 146Gd core. Which are made by core excitation or by promotion as the valence particles to the next shell. General properties of terminating bands are reviewed and exemplified on the observed high-angular momentum properties of 153Ho, 155Ho, 157Ho holmium nuclei. The very similar features are observed in the non-collective ones with N=88 isotones of dysprosium Dy, Erbium Er and tribium Yb nuclei.The spin contribution from different bands is calculated in terminating bands as well as more collective bands. The relation between the level energy minus rigid-rotor rotational energy versus spin for the yrast states is discussed and the plot serves to indicate that something interesting is happing above a certain value of (I). Above this value the nuclei seem to exhibit dominantly band termination behavior

2005-01-01

395

Dynamic analysis of slender launching system connected by clamp band joint using harmonic balance method  

Science.gov (United States)

Clamp band joints are widely used to fasten spacecrafts onto launching systems. Due to the unilateral constraints and the frictional slippage at the joint interface, clamp band joints may bring nonlinearity into launching systems during launching process. In this paper, the dynamics of a slender launching system with clamp band joint is investigated using harmonic balance method. Firstly, the formulas for the joint stiffness of the clamp band joint are proposed. Then, the finite element model for the launch vehicle and the spacecraft connected by the clamp band joint is developed, where the clamp band joint is represented by a massless beam element. Finally, harmonic balance method is applied to calculate the steady state response of the launching system.

Qin, Z. Y.; Yan, S. Z.; Chu, F. L.

2013-07-01

396

Counter-countermeasure identification based on multi-element dual band infrared detector.  

UK PubMed Central (United Kingdom)

An infrared (IR) dual band multi-element detector with the abilities of dual band IR counter-countermeasure (IRCCM) and spatial filtering is presented for effective target detection in a complex tactical environment. The detection elements of the detector are specially arranged like a conventional reticle pattern. With special design, the ratio of radiation intensity from two IR bands can be calculated to distinguish the target from the IR target-flare mixed signal and the two detection bands use a common aperture in the seeker. Without a reticle in the optical system of the IR seeker, the dual band detector can still perform spatial filtering to eliminate background noise effectively. The design details of the detector are presented. The performance of the detector's dual band IRCCM and spatial filtering are analyzed. Simulation results are presented verifying validity of the presented method.

Li M; Sun W; Chen H; Si J

2013-07-01

397

Long-term results and complications following adjustable gastric banding.  

UK PubMed Central (United Kingdom)

This study was performed to assess our long-term results with laparoscopic gastric banding in patients with an observation period of at least 9 years calculated from the date of operation. Between January 1996 and December 2000, a total of 276 patients (83% female) underwent laparoscopic gastric banding at our institution. Mean preoperative body mass index (BMI) was 44 +/- 6 kg/m(2). BMI after 1, 5, 7, 9, and 10 years was 33 +/- 6, 30 +/- 6, 31 +/- 6, 32 +/- 7, and 31 +/- 7 kg/m(2), respectively. Mean excess weight loss after 1 year was 57.1 +/- 23.0% and after 5, 7, 9, and 10 years 73.2 +/- 29.6%, 65.9 +/- 29.3%, 61.8 +/- 32.8%, and 64.0 +/- 32.1%, respectively. Median completeness of follow-up was 80%. Of the study population, 146 (52.9%) patients had at least one complication requiring reoperation. Presently, only 148 (53.6%) patients still have their original band, 49 (17.8%) had their original band replaced with a new one, and 79 (28.6%) had their band removed. Thirty-three patients had no second bariatric operation, a Roux-en-Y gastric bypass was done in 39 patients, and six patients underwent sleeve gastrectomy. Our long-term results are good with regard to weight loss in those patients who still have their band in situ. This is accompanied by a high complication rate and a 29% band loss rate.

Lanthaler M; Aigner F; Kinzl J; Sieb M; Cakar-Beck F; Nehoda H

2010-08-01

398

Long-term results and complications following adjustable gastric banding.  

Science.gov (United States)

This study was performed to assess our long-term results with laparoscopic gastric banding in patients with an observation period of at least 9 years calculated from the date of operation. Between January 1996 and December 2000, a total of 276 patients (83% female) underwent laparoscopic gastric banding at our institution. Mean preoperative body mass index (BMI) was 44 +/- 6 kg/m(2). BMI after 1, 5, 7, 9, and 10 years was 33 +/- 6, 30 +/- 6, 31 +/- 6, 32 +/- 7, and 31 +/- 7 kg/m(2), respectively. Mean excess weight loss after 1 year was 57.1 +/- 23.0% and after 5, 7, 9, and 10 years 73.2 +/- 29.6%, 65.9 +/- 29.3%, 61.8 +/- 32.8%, and 64.0 +/- 32.1%, respectively. Median completeness of follow-up was 80%. Of the study population, 146 (52.9%) patients had at least one complication requiring reoperation. Presently, only 148 (53.6%) patients still have their original band, 49 (17.8%) had their original band replaced with a new one, and 79 (28.6%) had their band removed. Thirty-three patients had no second bariatric operation, a Roux-en-Y gastric bypass was done in 39 patients, and six patients underwent sleeve gastrectomy. Our long-term results are good with regard to weight loss in those patients who still have their band in situ. This is accompanied by a high complication rate and a 29% band loss rate. PMID:20496124

Lanthaler, Monika; Aigner, Franz; Kinzl, Johann; Sieb, Michael; Cakar-Beck, Ferguel; Nehoda, Hermann

2010-08-01

399

Table of superdeformed nuclear bands and fission isomers  

Energy Technology Data Exchange (ETDEWEB)

A minimum in the second potential well of deformed nuclei was predicted and the associated shell gaps are illustrated in the harmonic oscillator potential shell energy surface calculations shown in this report. A strong superdeformed minimum in {sup 152}Dy was predicted for {beta}{sub 2}-0.65. Subsequently, a discrete set of {gamma}-ray transitions in {sup 152}DY was observed and, assigned to the predicted superdeformed band. Extensive research at several laboratories has since focused on searching for other mass regions of large deformation. A new generation of {gamma}-ray detector arrays is already producing a wealth of information about the mechanisms for feeding and deexciting superdeformed bands. These bands have been found in three distinct regions near A=l30, 150, and 190. This research extends upon previous work in the actinide region near A=240 where fission isomers were identified and also associated with the second potential well. Quadrupole moment measurements for selected cases in each mass region are consistent with assigning the bands to excitations in the second local minimum. As part of our committment to maintain nuclear structure data as current as possible in the Evaluated Nuclear Structure Reference File (ENSDF) and the Table of Isotopes, we have updated the information on superdeformed nuclear bands. As of April 1994, we have complied data from 86 superdeformed bands and 46 fission isomers identified in 73 nuclides for this report. For each nuclide there is a complete level table listing both normal and superdeformed band assignments; level energy, spin, parity, half-life, magneto moments, decay branchings; and the energies, final levels, relative intensities, multipolarities, and mixing ratios for transitions deexciting each level. Mass excess, decay energies, and proton and neutron separation energies are also provided from the evaluation of Audi and Wapstra.

Firestone, R.B. [Lawrence Berkeley Lab., CA (United States); Singh, B. [McMaster Univ., Hamilton, ON (Canada)

1994-06-01

400

The surface band structure of ?-Ga2O3  

International Nuclear Information System (INIS)

Ga2O3 belongs to the group of transparent conducting oxides (TCOs) with a wide band gap and electrical conductivity. It exhibits the largest band gap with Eg = 4.8 eV and thus a unique transparency from the visible into the UV region. The information on the electronic structure of ?-Ga2O3 is very scarce. This is in part due to the challenging problem of growing high purity single crystals. Transparent semiconducting ?-Ga2O3 single crystals were grown by the Czochralski method from an iridium crucible under a dynamic protective atmosphere to control partial pressures of volatile species of Ga2O3. The investigated samples were characterized by different techniques (LEED, Laue, and STM). The experimental valence band structure of the of ?-Ga2O3 single crystals along ?-Z and A-M symmetry directions of the (100)-surface of Brillouin zone was determined by high-resolution angle-resolved photoelectron spectroscopy (ARPES) utilizing synchrotron radiation. The experimental band structure is compared and discussed with the theoretical calculations. The effect of changing the temperature from 300 K to 20 K on the experimental band structure ?-Ga2O3 was studied.

2011-03-01

 
 
 
 
401

Superdeformed bands in sup 189,190 Hg  

Energy Technology Data Exchange (ETDEWEB)

Experiments using the {sup 160}Gd({sup 34}S, xn) reaction at 159 and 162 MeV have revealed two {gamma}-ray cascades which have properties similar to those of the previously reported superdeformed bands in the heavier Hg isotopes. These sequences have been identified as superdeformed structures in {sup 189}Hg and {sup 190}Hg. For the band in {sup 190}Hg, an average quadrupole moment Q{sub 0}=18{+-}3 e.b was obtained from a DSAM measurement. The data are interpreted within the cranked Woods-Saxon formalism and the rise in the dynamical moment of inertia for both bands is linked to the presence of pairs correlations and quasiparticle alignments. For the {sup 189-194}Hg superdeformed bands, the variations in the observed population intensity and in the rotational frequencies at which decay out of the bands occur are found to be consistent with the calculated change in the well depth of the superdeformed minimum with mass. (orig.).

Drigert, M.W. (Idaho National Engineering Lab., Idaho Falls, ID (USA)); Carpenter, M.P.; Janssens, R.V.F.; Moore, E.F.; Ahmad, I.; Fernandez, P.B.; Khoo, T.L.; Wolfs, F.L.H. (Argonne National Lab., IL (USA)); Bearden, I.G.; Benet, P.; Daly, P.J. (Purdue Univ., West Lafayette, IN (USA)); Garg, U.; Reviol, W.; Ye, D. (Notre Dame Univ., IN (USA)); Wyss, R. (Joint Inst. for Heavy Ion Research, Oak Ridge, TN (USA))

1991-08-05

402

Monolayer semiconducting transition metal dichalcogenide alloys: Stability and band bowing  

Science.gov (United States)

The stability and band bowing effects of two-dimensional transition metal dichalcogenide alloys MX2(1-x)X'2x (M = Mo, W, and X, X' = S, Se, Te) are investigated by employing the cluster expansion method and the special quasi-random structure approach. It is shown that for (S, Se) alloys, there exist stable ordered alloy structures with concentration x equal to 1/3, 1/2, and 2/3, which can be explained by the small lattice mismatch between the constituents and a large additional charge exchange, while no ordered configuration exists for (Se, Te) and (S, Te) alloys at 0 K. The calculated phase diagrams indicate that complete miscibility in the alloys can be achieved at moderate temperatures. The bowing in lattice constant for the alloys is quite small, while the bowing in band gap, and more so in band edge positions, is much more significant. By decomposing the formation of alloy into multiple steps, it is found that the band bowing is the joint effect of volume deformation, chemical difference, and a low-dimensionality enhanced structure relaxation. The direct band gaps in these alloys continuously tunable from 1.8 eV to 1.0 eV, along with the moderate miscibility temperatures, make them good candidates for two-dimensional optoelectronics.

Kang, Jun; Tongay, Sefaattin; Li, Jingbo; Wu, Junqiao

2013-04-01

403

Shear band formation in plastic bonded explosive (PBX)  

Energy Technology Data Exchange (ETDEWEB)

Adiabatic shear bands can be a source of ignition and lead to detonation. At low to moderate deformation rates, 10-1000/s , two other mechanisms can also give rise to shear bands. These mechanisms are: 1) softening caused by microcracking and 2) a constitutive response with a non-associated flow rule as is observed in granular material such as soil. Brittle behavior at small strains and the granular nature of HMX suggest that PBX-9501 constitutive behavior may be similar to sand. A constitutive model for the first of these mechanisms is studied in a series of calculations. This viscoelastic constitutive model for PBX-9501 softens via a statistical crack model. A sand model is used to provide a non-associated flow rule and detailed results will be reported elsewhere. Both models generate shear band formation at 1-2% strain at nominal strain rates at and below 1000/s. Shear band formation is suppressed at higher strain rates. Both mechanisms may accelerate the formation of adiabatic shear bands.

Dey, T.N.; Johnson, J.N.

1997-07-01

404

VLF saucers with attenuation bands  

International Nuclear Information System (INIS)

From a study of 43 VLF saucers exhibiting attenuation bands related to the proton gyrofrequency and observed on the ISIS satellites over Kerguelen in local winter (June-August, 1977), it is deduced that the generation/interaction region is generally located very near the satellite at distances often smaller than 50 km, either below or above it. It is also found that saucers with attenuation bands are observed in the 2000-0500 local time sector, between 60 deg and 70 deg geomagnetic latitude, in an auroral region closely correlated to the plasmapause. It is inferred from observations that the equatorward edges of the saucers region and of the plasma sheet are closely related.

1985-01-01

405

Configuration mixing calculation in the framework of the interacting boson model (2) in even 112-118Sn isotopes  

Science.gov (United States)

In this paper, the normal and the intruder 2p-2h bands in even 112-118Sn isotopes have been studied through configuration mixing calculation in the framework of IBM-2. The states belonging to the normal and the intruder bands have been calculated separately and then allowed to mix by using a simple band-mixing Hamiltonian. Energy values, E2 transition probabilities, and quadrupole moments of the first 2+ state have been calculated and compared with the experimental values.

Singh, A. K.; Gangopadhyay, G.; Banerjee, D.

1997-02-01

406

Rotational band {sup 111}Sn  

Energy Technology Data Exchange (ETDEWEB)

Partial level scheme of the neutron deficient {sup 111}Sn isotope is established upto an excitation energy of about 9 MeV and I{sup {pi}} = 43/2{sup -} from {gamma}-rays following {sup 103}Rh({sup 12}C,p3n) reaction. Clear evidence for the existence of a negative parity rotational band above I{sup {pi}} = 23/2{sup -}, most probably based on 3p-2h configuration, is obtained. (orig.)

Gangopadhyay, G. [University Coll. of Science, Calcutta (India). Dept. of Physics; Singh, A.K. [University Coll. of Science, Calcutta (India). Dept. of Physics; Banerjee, D. [University Coll. of Science, Calcutta (India). Dept. of Physics; Bhattacharya, R. [University Coll. of Science, Calcutta (India). Dept. of Physics; Bhowmik, R.K. [Nuclear Science Centre, New Delhi (India); Muralithar, S. [Nuclear Science Centre, New Delhi (India); Rodrigues, G. [Nuclear Science Centre, New Delhi (India); Singh, R.P. [Nuclear Science Centre, New Delhi (India); Goswami, A. [Saha Inst. of Nuclear Physics, Calcutta (India); Bhattacharya, S. [Saha Inst. of Nuclear Physics, Calcutta (India); Dasmahapatra, B. [Saha Inst. of Nuclear Physics, Calcutta (India); Sen, S. [Saha Inst. of Nuclear Physics, Calcutta (India)

1995-02-01

407

Band structure and nuclear dynamics  

International Nuclear Information System (INIS)

This Comment examines some of the developments which were discussed during the international conference on band structure and nuclear dynamics held in early 1980 in New Orleans and considers, in particular, the ideas available for the analysis of data at relatively low excitation energies. Subjects discussed include the Bohr-Mottelson or geometrical model, VMI models, the IBM, microscopic theory, and high-spin phenomena in rotational nuclei. (U.K.).

1981-01-01

408

Band structures in 96Ru  

International Nuclear Information System (INIS)

Nuclei in the A ? 100 mass region exhibit a wide variety of nuclear shapes ranging from spherical to highly deformed. High spin states in deformed odd-odd nuclei in the rare-earth are of utmost important during the recent past because of observation of a number of interesting phenomena. Investigations have revealed diversity in band structures. The present work reports in-beam ?-ray spectroscopic measurements to study level structures in 96Ru nucleus

2011-01-01

409

Identification of a new negative-parity band in ^154Nd and new negative-parity levels in ^152Nd  

Science.gov (United States)

From an experiment with Gammasphere and a ^252Cf spontaneous fission source, a new negative-parity band in ^154Nd and new negative-parity levels in ^152Nd were identified in a triple gamma coincidence study. It is very interesting to note: although there is a constant difference between J1 for the negative-parity band in ^152Nd and J1 for the negative-parity band in ^154Nd, their J2 values are nearly identical. These bands indicate a new kind of identical bands. In addition, these new octupole vibration excitation levels may provide new opportunities to test the calculations about the octupole vibration mode.

Zhang, X. Q.; Hamilton, J. H.; Ramayya, A. V.; Hwang, J. K.; Komicki, J.; Beyer, C. J.; Peker, L. K.; Babu, B. R. S.; Ginter, T. N.; Ter-Akopian, G. M.; Oganessian, Yu. Ts; Daniel, A. V.; Ma, W. C.; Varmette, P. G.; Asztalos, S. J.; Chu, S. Y.; Gregorich, K. E.; Lee, I. Y.; Macchiavelli, A. O.; MacLeod, R. W.; Rasmussen, J. O.; Cole, J. D.; Aryaeinejad, R.; Butler-Moore, K.; Dardenne, Y. X.; Drigert, M. W.; Stoyer, M. A.; Wild, J. F.; Becker, J. A.; Bernstein, L. A.; Lougheed, R. W.; Moody, K. J.; Donangelo, R.; Prussin, S. G.; Griffin, H. C.

1997-11-01

410

Properties of the ?h 9/2 ? ?i 13/2 band in odd-odd 188Au  

Science.gov (United States)

A new rotational band has been identified and assigned to 188Au for the first time using the 173Yb(19F,4n ?) reaction at the beam energies of 86 and 90 MeV. This band is proposed to be built on the ?h 9/2 ? ?i 13/2 configuration by comparing the band properties with known bands in neighboring nuclei. The prolate-to-oblate shape transition through triaxial shape has been proposed to occur around 188Au for the ?h 9/2 ? ?i 13/2 bands in odd-odd Au isotopes on the basis of total Routhian surface (TRS) calculations.

Fang, YongDe; Zhang, YuHu; Oshima, M.; Toh, Y.; Xu, FuRong; Shi, Yue; Zhou, XiaoHong; Liu, MinLiang; Guo, YingXiang; Koizumi, M.; Kimura, A.; Hatsukawa, Y.; Morikawa, T.; Nakamura, M.; Sugaware, M.; Kusakari, H.

2011-08-01

411

Deformation bands in porous sandstones their microstructure and petrophysical properties  

Energy Technology Data Exchange (ETDEWEB)

Deformation bands are commonly thin tabular zones of crushed or reorganized grains that form in highly porous rocks and sediments. Unlike a fault, typically the slip is negligible in deformation bands. In this dissertation the microstructure and petrophysical properties of deformation bands have been investigated through microscopy and numerical analysis of experimental and natural examples. The experimental work consists of a series of ring-shear experiments performed on porous sand at 5 and 20 MPa normal stresses and followed by microscopic examination of thin sections from the sheared samples. The results of the ring-shear experiments and comparison of them to natural deformation bands reveals that burial depth (level of normal stress in the experiments) and the amount of shear displacement during deformation are the two significant factors influencing the mode in which grains break and the type of shear zone that forms. Two end-member types of experimental shear zones were identified: (a) Shear zones with diffuse boundaries, which formed at low levels of normal stress and/or shear displacement; and (b) Shear zones with sharp boundaries, which formed at higher levels of normal stress and/or shear displacement. Our interpretation is that with increasing burial depth (approximately more than one kilometer, simulated in the experiments by higher levels of normal stress), the predominant mode of grain fracturing changes from flaking to splitting; which facilitates the formation of sharp-boundary shear zones. This change to grain splitting increases the power law dimension of the grain size distribution (D is about 1.5 in sharp boundary shear zones). Based on our observations, initial grain size has no influence in the deformation behavior of the sand at 5 MPa normal stresses. A new type of cataclastic deformation band is described through outcrop and microscopic studies; here termed a 'slipped deformation band'. Whereas previously reported cataclastic deformation bands are characterized by strain hardening, these new bands feature a central slip surface, which indicates late strain softening. They lack the characteristic compaction envelop, and are typified by higher porosity and lower permeability than previously-described cataclastic deformation bands. Intense background fracturing of the host rock and significant initial porosity are considered to be important in creating these newly-discovered deformation bands. In a related study, we investigate, for millimeter- wide deformation bands, the scale limitation inherent in laboratory measurements of porosity and permeability. The scale limitations imposed by the deformation band relative to the physical sample size motivated us to develop a new method for determining porosity and permeability based on image processing. While plug measurements measure the effective permeability across a 25.4 mm (1 inch) long sample, which includes both host rock and deformation band, the method presented here provides a means to estimate porosity and permeability of deformation band on microscale. This method utilizes low-order (one- and two orders) spatial correlation functions to analyze high-resolution, high-magnification backscatter images, to estimate the porosity and specific surface area of the pore-grain interface in the deformed sandstones. Further, this work demonstrates the use of a modified version of the Kozeny-Carmen relation to calculate permeability by using porosity and specific surface area obtained through the image processing. The result shows that permeability difference between the band and the host rock is up to four orders of magnitude. Moreover, the porosities and permeabilities estimated from image processing are lower than those obtained from their plug measurements; hence the traditional laboratory measurements have been overestimating permeability because of the previously-unrecognized scale problem. In addition, the image processing results clearly show that, as a result of microstructural variation, both porosity and permeability vary along the leng

Torabi, Anita

2007-12-15

412

Generalized pseudopotential theory of d-band metals  

Energy Technology Data Exchange (ETDEWEB)

The generalized pseudopotential theory (GPT) of metals is reviewed with emphasis on recent developments. This theory, which attempts to rigorously extend to d-band metals the spirit of conventional simple-metal pseudopotential perturbation theory, has now been optimized and fully integrated with the Kohn-Sham local-density-functional formalism, allowing for systematic first-principles calculations. Recent work on the problems of cohesion, lattice dynamics, structural phase stability, pressure- and temperature-induced phase transitions, and melting is discussed.

Moriarty, J.A.

1983-01-01

413

A simple description of doublet bands in mass around 100  

International Nuclear Information System (INIS)

The structure of doublet bands associated with neutron 0h11/2 and proton 0g9/2 orbital in the doubly-odd nuclei, 98-104Tc and 100-106Rh is studied theoretically using the quadrupole coupling model. The calculated energy levels and electromagnetic transitions are in excellent agreement with experimental data. The internal structure of the yrast states is discussed in terms of the QCM wave functions.

2009-05-04

414

Collective excitations and band termination in {sup 85}Nb  

Energy Technology Data Exchange (ETDEWEB)

High-spin states in {sup 85}Nb were studied using the GAMMASPHERE Ge detector array and the MICROBALL charged-particle detector system. Three {gamma}-ray cascades with collective rotational characteristics were observed. One of the bands exhibits a forking at the top, most likely reflecting the termination of one branch into a favoured non-collective, near spherical state. The data are interpreted in terms of cranked Strutinsky-type calculations.

Jonsson, K.; Cederwall, B.; Johnson, A.; Wyss, R.; Baeck, T.; Cederkaell, J.; Devlin, M.; Elson, J.; LaFosse, D.R.; Lerma, F.; Sarantites, D.G.; Clark, R.M.; Lee, I.Y.; Macchiavelli, A.O.; Macleod, R.W

1999-01-04

415

Collective excitations and band termination in 85Nb  

International Nuclear Information System (INIS)

High-spin states in 85Nb were studied using the GAMMASPHERE Ge detector array and the MICROBALL charged-particle detector system. Three ?-ray cascades with collective rotational characteristics were observed. One of the bands exhibits a forking at the top, most likely reflecting the termination of one branch into a favoured non-collective, near spherical state. The data are interpreted in terms of cranked Strutinsky-type calculations.

1999-01-04

416

Lifetime measurements in the superdeformed band of sup 192 Hg  

Energy Technology Data Exchange (ETDEWEB)

Lifetimes were measured for transitions in the superdeformed band of {sup 192}Hg with the Doppler-shift attenuation method. The results yield an essentially constant quadrupole moment of 20{plus minus}2 {ital e} b and indicate that the sidefeeding lifetimes are of the same order as the state lifetimes. The data are consistent with calculations using the cranked Woods-Saxon Strutinsky method with pairing.

Moore, E.F.; Janssens, R.V.F.; Ahmad, I.; Carpenter, M.P.; Fernandez, P.B.; Khoo, T.L.; Ridley, S.L.; Wolfs, F.L.H. (Argonne National Laboratory, Argonne, IL (USA)); Ye, D.; Beard, K.B.; Garg, U. (University of Notre Dame, Notre Dame, Indiana (USA)); Drigert, M.W. (Idaho National Engineering Laboratory, EG G Idaho Inc., Idaho Falls, ID (USA)); Benet, P.; Daly, P.J. (Purdue University, West Lafayette, IN (USA)); Wyss, R. (Manne Siegbahn Institute of Physics, S-10405 Stockholm (Sweden) Royal Institute of Technology, S-10444 Stockholm (Sweden)); Nazarewicz, W. (Institute of Physics, Warsaw University of Technology, PL 00-662 Warsaw (Poland))

1990-06-25

417

Lifetime measurements in the superdeformed band of 192Hg  

International Nuclear Information System (INIS)

[en] Lifetimes were measured for transitions in the superdeformed band of 192Hg with the Doppler-shift attenuation method. The results yield an essentially constant quadrupole moment of 20±2 e b and indicate that the sidefeeding lifetimes are of the same order as the state lifetimes. The data are consistent with calculations using the cranked Woods-Saxon Strutinsky method with pairing

1990-06-25

418

Nuclear structure calculations in vanadium isotopes  

International Nuclear Information System (INIS)

Nuclear structure calculations for the low-lying states in even-N isotopes sup(47, 49, 51)V and odd-N isotopes sup(48, 50)V are performed in the framework of Hartree-Fock projection formalism. All the nucleous outside 40Ca core are explicitly treated in the pf-shell configuration space by employing a realistic nucleon-nucleon interaction. The energy levels, static electromagnetic moments and the electromagnetic transition probabilities are evaluated from band-mixing calculations wherein the lowest four energetically close intrinsic states of the nuclei are taken into account. The theoretical results are in fair agreement with the experimental data. (author)

1977-01-01

419

Study on a method for atmospheric correction by a numerical calculation model using weather parameters; Atmospheric correction for thermal infrared band of airborne MSS data. Kisho yoso wo mochiita suchi keisan model ni yoru taiki hosei shuho ni kansuru kenkyu; Kokuki MSS no netsu sekigai iki data ni taisuru taiki hosei  

Energy Technology Data Exchange (ETDEWEB)

Difference of atmospheric effect in seasons and districts was discussed by the results of ground truth. In addition, we proposed an effective method for atmospheric correction using weather parameter which can be obtained readily. Following results were shown. 1. Difference of atmospheric effect in two seasons and in three districts was clarified by the regression lines by using the CCT value of thermal infrared band and surface temperatures measured by ground truth. In summer when mass of water vapor is big, although it was obserevd that 10 {degree} C difference between measuring data and correcting data was occurred by atmospheric effect, there was a little effect in winter. The regression line of Tajima district located in an industrial zone was different from those of other districts. 2. Two black body temperatures of MSS which were corrected atmospheric absorption by simulation almost lay on the regression line with the ground truth data in Takatsu and districts except Tajima district. In addition to the correction of atmospheric scattering, corrected MSS two black body temperatures of MSS almost lay on the line of Tajima district. 7 refs., 13 figs., 3 tabs.

Hoyano, A. (Tokyo Inst. of Technology, Tokyo (Japan). Faculty of Engineering); Uchiyama, K. (Tokyo Inst. of Technology, Tokyo (Japan). Graduate School)

1990-08-30

420

Atomistic band gap engineering in donor-acceptor polymers.  

UK PubMed Central (United Kingdom)

We have synthesized a series of cyclopentadithiophene-benzochalcogenodiazole donor-acceptor (D-A) copolymers, wherein a single atom in the benzochalcogenodiazole unit is varied from sulfur to selenium to tellurium, which allows us to explicitly study sulfur to selenium to tellurium substitution in D-A copolymers for the first time. The synthesis of S- and Se-containing polymers is straightforward; however, Te-containing polymers must be prepared by postpolymerization single atom substitution. All of the polymers have the representative dual-band optical absorption profile, consisting of both a low- and high-energy optical transition. Optical spectroscopy reveals that heavy atom substitution leads to a red-shift in the low-energy transition, while the high-energy band remains relatively constant in energy. The red-shift in the low-energy transition leads to optical band gap values of 1.59, 1.46, and 1.06 eV for the S-, Se-, and Te-containing polymers, respectively. Additionally, the strength of the low-energy band decreases, while the high-energy band remains constant. These trends cannot be explained by the present D and A theory where optical properties are governed exclusively by the strength of D and A units. A series of optical spectroscopy experiments, solvatochromism studies, density functional theory (DFT) calculations, and time-dependent DFT calculations are used to understand these trends. The red-shift in low-energy absorption is likely due to both a decrease in ionization potential and an increase in bond length and decrease in acceptor aromaticity. The loss of intensity of the low-energy band is likely the result of a loss of electronegativity and the acceptor unit's ability to separate charge. Overall, in addition to the established theory that difference in electron density of the D and A units controls the band gap, single atom substitution at key positions can be used to control the band gap of D-A copolymers.

Gibson GL; McCormick TM; Seferos DS

2012-01-01

 
 
 
 
421

Insect behaviour: migratory bands give crickets protection.  

Science.gov (United States)

Mormon crickets and juvenile locusts form huge migratory bands--millions of individuals march in unison across the landscape and devastate vast agricultural areas, but little is known about why these bands form. Here we use radiotelemetry to show that band membership benefits these insects by greatly reducing the probability that they will become victims of predators. It is likely that migratory banding has evolved because it gives substantial protection to individuals within the group. PMID:15716941

Sword, Gregory A; Lorch, Patrick D; Gwynne, Darryl T

2005-02-17

422

High-spin structure of normal-deformed bands in 84Zr  

International Nuclear Information System (INIS)

The reaction 58Ni(32S,?2p) at Elab=135 MeV was used to populate high-spin states in 84Zr. The complete GAMMASPHERE and MICROBALL arrays were used to obtain clean ?-?-? line shapes to be analyzed by the Doppler shift attenuation method and to determine 27 lifetimes in the ground-state band and in two excited bands. Side-feeding times were also measured by comparing the line shapes gated with transitions above and below the state under study. The deduced electric quadrupole moments for the ground-state band are consistent with a very slow reduction with frequency with values ranging between 2.4(3) and 2.0(1)e b. The negative-parity bands feature also an approximate constancy of quadrupole moment with values similar to those in the ground-state band. Cranking calculations agree with this behavior in both parity bands and suggest an interpretation of the upper states in the ground-state band as part of a very slowly terminating band. Shell-dependent cranked Nilsson calculations explain a fourth ? cascade as pertaining to a noncollective structure terminating at I=20+.

2003-01-01

423

High-spin structure of normal-deformed bands in 84Zr  

Science.gov (United States)

The reaction 58Ni(32S,?2p) at Elab=135 MeV was used to populate high-spin states in 84Zr. The complete GAMMASPHERE and MICROBALL arrays were used to obtain clean ?-?-? line shapes to be analyzed by the Doppler shift attenuation method and to determine 27 lifetimes in the ground-state band and in two excited bands. Side-feeding times were also measured by comparing the line shapes gated with transitions above and below the state under study. The deduced electric quadrupole moments for the ground-state band are consistent with a very slow reduction with frequency with values ranging between 2.4(3) and 2.0(1)e b. The negative-parity bands feature also an approximate constancy of quadrupole moment with values similar to those in the ground-state band. Cranking calculations agree with this behavior in both parity bands and suggest an interpretation of the upper states in the ground-state band as part of a very slowly terminating band. Shell-dependent cranked Nilsson calculations explain a fourth ? cascade as pertaining to a noncollective structure terminating at I=20+.

Cardona, R.; Cristancho, F.; Tabor, S. L.; Kaye, R. A.; Solomon, G. Z.; Döring, J.; Johns, G. D.; Devlin, M.; Lerma, F.; Sarantites, D. G.; Lee, I.-Y.; Macchiavelli, A. O.; Ragnarsson, I.

2003-08-01

424

The laparoscopic banded gastric bypass – operation technique  

Directory of Open Access Journals (Sweden)

Full Text Available The banded Roux-en-Y gastric bypass can be used as a primary or revisionary bariatric procedure. This article describesthe operation technique including materials, size and placement of the banding and gives an overview con cerningevolution and indications of the operation. A video of a primary banded Roux-en-Y gastric bypass is presented.

Simon Küsters; Goran Marjanovic; Tobias Baumann; Philipp Holzner; Wojciech K. Karcz

2010-01-01

425

[Long-term fever after gastric banding].  

UK PubMed Central (United Kingdom)

We report a 65-year-old male, suffering from aspiration pneumonia after gastric banding revealed by intermittent fever inducing a delayed diagnosis. Several early and later pulmonary complications following laparoscopic gastric banding have been reported. Removal or deflation of the band should be considered in unexplained persistent fever to avoid more severe complications such as respiratory distress.

Gonzva J; Roseau JB; Legodec J; Louis C; N'guyen Huy Thuy G; Gaussens S; Bérard H

2012-08-01

426

[Long-term fever after gastric banding].  

Science.gov (United States)

We report a 65-year-old male, suffering from aspiration pneumonia after gastric banding revealed by intermittent fever inducing a delayed diagnosis. Several early and later pulmonary complications following laparoscopic gastric banding have been reported. Removal or deflation of the band should be considered in unexplained persistent fever to avoid more severe complications such as respiratory distress. PMID:22475663

Gonzva, J; Roseau, J-B; Legodec, J; Louis, C; N'guyen Huy Thuy, G; Gaussens, S; Bérard, H

2012-04-03

427

Esophageal motility disorders after gastric banding.  

UK PubMed Central (United Kingdom)

The long-term effects of gastric banding on esophageal function are not well described. This report describes a 28-year-old woman who developed signs and symptoms of abnormal esophageal motility and lower esophageal sphincter hypotension after gastric banding for morbid obesity. The current literature addressing the effects of gastric banding on esophageal function in light of this case report is discussed.

O'Rourke RW; Deveney CW; McConnell DB; Wolfe BM; Jobe BA

2007-01-01

428

Raman scattering in two-band superconductors  

Energy Technology Data Exchange (ETDEWEB)

The electron Raman scattering in a two-band superconductor has been theoretically investigated. The fluctuational effects, Coulomb interaction, and electron scattering by non-magnetic impurities are taken into account. Two contributions to the light scattering intensity are found: an additive contribution from two bands, and an inter-band term which exists for arbitrary light polarization. (author)

Kon, L.Z.; Ciobanu, I.P.; Digor, D.F. [Institute of Applied Physics, Academy of Sciences of Moldova, 5 Academiei Street, 2028, Chisinau (Moldova, Republic of)

1997-05-05

429

Observation of rotational bands in hadron spectroscopy  

International Nuclear Information System (INIS)

A few excellent rotational bands are identified in N and ? mass spectra. They are not multifold and therefore are of a different kind from molecular bands. Apparently the hadronic rotation occurs around the axis perpendicular to the symmetry axis only as in the nucleus. Nevertheless, these rotational bands again differ from nuclear ones because each consists of a series of states of alternating parity.

1984-01-01

430

Origin of wide-band IP type II bursts  

Science.gov (United States)

Context. Different types of interplanetary (IP) type II bursts have been observed, where the more usual ones show narrow-band and patchy emissions, sometimes with harmonics, and which at intervals may disappear completely from the dynamic spectrum. The more unusual bursts are wide-band and diffuse, show no patches or breaks or harmonic emission, and often have long durations. Type II bursts are thought to be plasma emission, caused by propagating shock waves, but a synchrotron-emitting source has also been proposed as the origin for the wide-band type IIs. Aims: Our aim is to find out where the wide-band IP type II bursts originate and what is their connection to particle acceleration. Methods: We analyzed in detail 25 solar events that produced well-separated, wide-band IP type II bursts in 2001-2011. Their associations to flares, coronal mass ejections (CMEs), and solar energetic particle events (SEPs) were investigated. Results: Of the 25 bursts, 18 were estimated to have heights corresponding to the CME leading fronts, suggesting that they were created by bow shocks ahead of the CMEs. However, seven events were found in which the burst heights were significantly lower and which showed a different type of height-time evolution. Almost all the analyzed wide-band type II bursts were associated with very high-speed CMEs, originating from different parts of the solar hemisphere. In terms of SEP associations, many of the SEP events were weak, had poor connectivity due to the eastern limb source location, or were masked by previous events. Some of the events had precursors in specific energy ranges. These properties and conditions affected the intensity-time profiles and made the injection-time-based associations with the type II bursts difficult to interpret. In several cases where the SEP injection times could be determined, the radio dynamic spectra showed other features (in addition to the wide-band type II bursts) that could be signatures of shock fronts. Conclusions: We conclude that in most cases (in 18 out of 25 events) the wide-band IP type II bursts can be plasma emission, formed at or just above the CME leading edge. The results for the remaining seven events might suggest the possibility of a synchrotron source. These events, however, occurred during periods of high solar activity, and coronal conditions affecting the results of the burst height calculations cannot be ruled out. The observed wide and diffuse emission bands may also indicate specific CME leading edge structures and special shock conditions. Figures 2-26 and Table 4 are available in electronic form at http://www.aanda.org

Pohjolainen, S.; Allawi, H.; Valtonen, E.

2013-10-01

431

Confidence bands in density estimation  

CERN Multimedia

Given a sample from some unknown continuous density $f:\\mathbb{R}\\to\\mathbb{R}$, we construct adaptive confidence bands that are honest for all densities in a "generic" subset of the union of $t$-H\\"older balls, $0

Giné, Evarist; 10.1214/09-AOS738

2010-01-01

432

Progress in calculations of the superconducting properties of transition metals  

International Nuclear Information System (INIS)

[en] First principles calculations of the electron--phonon parameters of d-band metals can now be performed to an accuracy of about 10% for averaged quantities such as the mass enhancement or the room temperature resistivity. Quantities such as the spectral function ?2F(?) or the phonon linewidth which describe the electron--phonon interaction in more detail can also be calculated. Agreement between calculated and experimental phonon linewidths is generally good but there are differences between the experimental and calculated versions of ?2F(?). Calculations of the thermodynamic critical field and the upper critical field for Nb agree well with experiment

1979-06-23

433

Superconducting transition temperatures of Zr, Os And Th from band structure results  

International Nuclear Information System (INIS)

[en] The superconducting transition tenperatures of Zr, Os and Th are calculated using their band-structure results. Under spherical band approximation, the theory of Gaspari and Gyorffy (1972) is used in conjunction with the McMillan's formula (1968) to calculate Tsub(c). As the band-structure calculations have been done for potentials constructed with and without the correlation part, the superconducting transition temperatures are also calculated for all the potentials. The theoretical values of Tsub(c) are found to be very sensitive to the changes in the electron-phonon enhancement factor lambda and the Coulomb Pseudopotential ?sup(asterisk). The theoretical values are compared with the experimental values. (author)

1980-01-01

434

Flow phase diagrams for concentration-coupled shear banding.  

Science.gov (United States)

After surveying the experimental evidence for concentration coupling in the shear banding of wormlike micellar surfactant systems, we present flow phase diagrams spanned by shear stress Sigma (or strain rate gamma) and concentration, calculated within the two-fluid, non-local Johnson-Segalman (d-JS-phi) model. We also give results for the macroscopic flow curves Sigma(gamma,phi) for a range of (average) concentrations phi. For any concentration that is high enough to give shear banding, the flow curve shows the usual non-analytic kink at the onset of banding, followed by a coexistence "plateau" that slopes upwards, dSigma/dgamma>0. As the concentration is reduced, the width of the coexistence regime diminishes and eventually terminates at a non-equilibrium critical point [Sigmac,phic,gammac]. We outline the way in which the flow phase diagram can be reconstructed from a family of such flow curves, Sigma(gamma,phi), measured for several different values of phi. This reconstruction could be used to check new measurements of concentration differences between the coexisting bands. Our d-JS-phi model contains two different spatial gradient terms that describe the interface between the shear bands. The first is in the viscoelastic constitutive equation, with a characteristic (mesh) length l. The second is in the (generalised) Cahn-Hilliard equation, with the characteristic length xi for equilibrium concentration-fluctuations. We show that the phase diagrams (and so also the flow curves) depend on the ratio r congruent with l/xi, with loss of unique state selection at r=0. We also give results for the full shear-banded profiles, and study the divergence of the interfacial width (relative to l and xi) at the critical point. PMID:15015089

Fielding, S M; Olmsted, P D

2003-05-01

435

Flow phase diagrams for concentration-coupled shear banding.  

UK PubMed Central (United Kingdom)

After surveying the experimental evidence for concentration coupling in the shear banding of wormlike micellar surfactant systems, we present flow phase diagrams spanned by shear stress Sigma (or strain rate gamma) and concentration, calculated within the two-fluid, non-local Johnson-Segalman (d-JS-phi) model. We also give results for the macroscopic flow curves Sigma(gamma,phi) for a range of (average) concentrations phi. For any concentration that is high enough to give shear banding, the flow curve shows the usual non-analytic kink at the onset of banding, followed by a coexistence "plateau" that slopes upwards, dSigma/dgamma>0. As the concentration is reduced, the width of the coexistence regime diminishes and eventually terminates at a non-equilibrium critical point [Sigmac,phic,gammac]. We outline the way in which the flow phase diagram can be reconstructed from a family of such flow curves, Sigma(gamma,phi), measured for several different values of phi. This reconstruction could be used to check new measurements of concentration differences between the coexisting bands. Our d-JS-phi model contains two different spatial gradient terms that describe the interface between the shear bands. The first is in the viscoelastic constitutive equation, with a characteristic (mesh) length l. The second is in the (generalised) Cahn-Hilliard equation, with the characteristic length xi for equilibrium concentration-fluctuations. We show that the phase diagrams (and so also the flow curves) depend on the ratio r congruent with l/xi, with loss of unique state selection at r=0. We also give results for the full shear-banded profiles, and study the divergence of the interfacial width (relative to l and xi) at the critical point.

Fielding SM; Olmsted PD

2003-05-01

436

First-principles study of Cu{sub 2}ZnSnS{sub 4} and the related band offsets for photovoltaic applications  

Energy Technology Data Exchange (ETDEWEB)

First-principles calculations of the band offsets between Cu{sub 2}ZnSnS{sub 4} (CZTS) and XS (X = Cd, Zn) are performed. While the interface dipole contribution for the band offsets is calculated using the Perdew-Burke-Ernzerhof functional, the Heyd-Scuseria-Ernzerhof hybrid functional is employed to introduce the quasiparticle corrections to the band offsets. The calculated conduction band offset between CZTS and CdS is 0.2 eV, validating CdS for the buffer layer of the CZTS solar cell. The small conduction band offset stems from the band gap narrowing of CdS under the interface strain caused by the lattice misfit with CZTS. A large valence band offset over 0.9 eV between CZTS and ZnS indicates that precipitated ZnS is regarded as an inactive insulator phase in CZTS absorbers.

Nagoya, A; Asahi, R [Toyota Central R and D Laboratories, Incorporated, Nagakute, Aichi 480-1192 (Japan); Kresse, G, E-mail: e1405@mosk.tytlabs.co.jp [Faculty of Physics, Universitaet Wien and Center for Computational Materials Science, Sensengasse 8/12, A-1090, Wien (Austria)

2011-10-12

437